Autoimmune Encephalitis History & Current Knowledge

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Autoimmune encephalitis History & current knowledge

Short compendium

Version 5.8, April 2016

By Finn E. Somnier, M.D., D.Sc. (Med.), copyright ®

Department of Autoimmunology and Biomarkers, Statens Serum Institut, Copenhagen, Denmark

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Table of contents GENERAL SECTIONS ...... 3

INTRODUCTION ...... 3 BACKGROUND ...... 4 DEFINITION OF AUTOIMMUNE ENCEPHALITIS ...... 4 CURRENT KNOWLEDGE (THREE MAJOR GROUPS OF AUTOANTIBODIES) ...... 5 EPIDEMIOLOGY ...... 6 T-CELL VERSUS B-CELL MEDIATED AUTOIMMUNITY ...... 7 Intrathecal synthesis of autoantibodies ...... 7 Experimental autoimmune encephalitis ...... 7 IMMUNOLOGICAL MECHANISMS ...... 8 PRESENTING SYMPTOMS OF SUCH DISORDERS AND THAT FREQUENTLY ARE NOT PARANEOPLASTIC...... 9 OVERVIEW OF PARANEOPLASTIC ENCEPHALITIDES...... 10 CO-OCCURRENCE OF AUTOANTIBODIES ...... 10 REPORTED PRESENTING AND SUBSEQUENTLY OCCURRING SYMPTOMS VS. SPECIFIC TYPE OF AUTOANTIBODY ...... 11 AUTOIMMUNE ENCEPHALITIS AND EPILEPTIC SEIZURES ...... 12 AUTOIMMUNE EPILEPSY AND PSYCHIATRY...... 14 CHILD & ADOLESCENT PSYCHIATRY AND NEUROLOGY: OCCURRENCE OF ANALOGOUS SYMPTOMS ...... 15 PROPOSED DIAGNOSTIC STRATEGY - AUTOANTIBODIES ...... 16 GENERAL COMMENTS ...... 18 PROMPT RECOGNITION OF ALL THE DISORDERS ASSOCIATED WITH ANTIBODIES AGAINST CELL SURFACE ANTIGENS IS IMPORTANT ...... 18 ALGORITHMIC APPROACH TO DIAGNOSIS AND TREATMENT OF ENCEPHALITIS WITH ANTIBODIES TO INTRACELLULAR OR CELL SURFACE NEURONAL ANTIGENS ...... 19 VARIOUS SPECIFIC DISORDERS: AUTOIMMUNE ENCEPHALITIS DIRECTED AT EXTRACELLULAR STRUCTURES, INCLUDING SYNAPTIC, PRESYNAPTIC AND OTHER RELATED ONES...... 20

CHARACTERISTICS OF ANTI-NMDAR (NR1) - GLUTAMATE RECEPTOR SUBUNIT ZETA-1 – GLUN1 - ENCEPHALITIS ...... 20 CHARACTERISTICS OF ANTI-AMPAR (GLUR1, GLUR2) ENCEPHALITIS ...... 25 CHARACTERISTICS OF ANTI-LGI1, ANTI-CASPR2, DPPX - ACCESSORY PROTEINS AND SUBUNIT OF VGKCS - ENCEPHALITIS ...... 27 Characteristics of anti-LGI1 (leucine-rich, glioma inactivated 1) encephalitis ...... 27 Differential diagnoses – various autoantibodies ...... 29 Characteristics of anti-CASPR2 (contactin-associated protein-like 2) encephalitis ...... 30 Characteristics of anti-DPPX (DPP6, a subunit of Kv4.2 potassium channels) encephalitis ...... 31 CHARACTERISTICS OF ANTI-GABABR1 - GAMMA-AMINOBUTYRIC ACID TYPE B RECEPTOR SUBUNIT 1 - ENCEPHALITIS ...... 34 CHARACTERISTICS OF ANTI-GABAAR - Α1/Β3 SUBUNITS - ENCEPHALITIS ...... 37 CHARACTERISTICS OF ANTI-MGLUR1 AND OF ANTI-HOMER3 ENCEPHALITIS (CEREBELLITIS) ...... 38 Cerebellar degeneration associated with various autoantibodies ...... 38 CHARACTERISTICS OF ANTI-MGLUR5 ENCEPHALITIS (OPHELIA SYNDROME) ...... 39 CHARACTERISTICS OF ANTI-IGLON5 - CELL ADHESION MOLECULE IGLON5 - ENCEPHALITIS ...... 40 Differential diagnosis ...... 40 STIFF-PERSON SPECTRUM OF SYMPTOMS (SPS) ...... 41 Characteristics of anti-Glutamate decarboxylase 2 (anti-GAD65) encephalitis – a spectrum of disorders ...... 41 CHARACTERISTICS OF ANTI-GLYR-ALPHA1 ENCEPHALOMYELITIS – A SPECTRUM OF DISORDERS ...... 45 CHARACTERISTICS OF NEUROMYELITIS OPTICA SPECTRUM OF DISORDERS...... 47 ANTI-MOG ASSOCIATED ENCEPHALOMYELITIS ...... 52 ANTI-DOPAMINE RECEPTOR (BASAL GANGLIA - POST-STREPTOCOCCAL) SPECTRUM OF ENCEPHALITIS ...... 54 Epidemiology and clinical features ...... 55

Diagnostic algorithm ...... 58 Treatment ...... 59 Scientific documentation ...... 60 Animal and cell models ...... 62 AUTOIMMUNE ENCEPHALITIS DIRECTED AT OTHER STRUCTURES ...... 66 GLUTEN ASSOCIATED AUTOIMMUNE ENCEPHALITIS ...... 66 HASHIMOTO’S ENCEPHALITIS AND AUTOIMMUNE THYROIDITIS ...... 70 GENERAL REFERENCES (CHRONOLOGICAL LISTING BY YEAR OF PUBLICATION) ...... 72 PARANEOPLASTIC NEUROLOGICAL AND MUSCULAR SYNDROMES – PLEASE SEE SEPARATE COMPENDIUM ...... 77 CHANNELOPATHIES, RECEPTOR AND SOLUTE CARRIERS DISORDERS IN NEUROLOGY, PLEASE SEE SEPARATE COMPENDIUM ...... 78

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

General sections

Introduction The acute fulminating epidemic form of encephalitis lethargica (von Economo, EL) seems to have disappeared, since there have been no further reported epidemics after 1916-1927. During that period, both rheumatic fever (RF) and Sydenham chorea (SC) were associated with and later proven to be provoked by streptococcal infections. The occurrence of RF including SC has become much less frequent in the industrial world.

Unfortunately, sporadic cases of similar encephalitis are still reported and presenting with  Neuropsychiatric symptoms, including behavioural problems, attention deficit/hyperactivity disorder (ADHD), obsessions, compulsions (OCD), anorexia, bulimia, anxiety, depression, psychosis, stupor, sleeping disorders: drowsiness, sluggishness (lethargy), sleep inversion  Cognitive problems, memory loss or amnesia, ataxia, mutism, parkinsonism, oculogyric crises, tics, chorea, catatonia, epilepsy, myoclonus, myokymia

 These patients range <1 and 70 years of age, but are most frequently children or teenagers

At least, four key features appear to be evident Courses of these disorders  Idiopathic (as yet of unknown cause)  Monophasic  Post-infectious (viral, bacterial and more)  Multiphasic (relapsing, recovering)  Paraneoplastic  Chronic - with or without relapses - with  Genetic predisposition continuing problems of neuropsychiatric  (Consider possible immunodeficiency) and movement disorders Wide range of clinical appearances and courses  Mild with a single or only a few symptoms  May mimic a psychiatric disorder and not arise suspicion of encephalitis  More complex symptomatology  The patient may be seen by either a neurologist, paediatrician or a psychiatrist depending on the presenting symptoms  Fulminating and maybe lethal course

Discoveries that are more recent appear to point towards a variety of different aetiologies of EL-like disorders and within a context of autoimmune encephalitis.

Background

The 1916-1927 epidemics of encephalitis lethargica (von Economo, EL) The patients, mostly children of either sex, characteristically presented with headache and malaise, lethargy, insomnia, sleep inversion, ophthalmoplegia, catatonia, parkinsonism, and psychosis.

The evidence for EL as caused by flu is mostly of an associative nature, and delivery of more direct evidence has failed  EL was associated by many observers to the influenza epidemic (Spanish flu), which expanded from America to Europe  However, the epidemic of EL began earlier and lasted longer, and which - in contrast to the flu – spread from Europe to America  Influenza is a known cause of viral meningoencephalitis, although extremely rare  Post-influenza encephalitis syndrome is extremely rare  Flu virus has not been found in archival post‐mortem tissue  Experimental infections with the reconstituted 1918 virus in mice did not identify virus outside the lung, including brain Summary: previously, we have known very little about the aetiology of EL It is not until the more recent decades that a concept of autoimmune encephalitis has become recognized Vilensky JA, Gilman S. Encephalitis lethargica: could this disease be recognised if the epidemic recurred? Pract Neurol 2006; 6: 360-367; Dale RC, Church AJ, Surtees RAJ, et. al. Encephalitis lethargica syndrome: 20 new cases and evidence of basal ganglia autoimmunity. Brain (2004) 127 (1): 21-33; Vilensky J. Encephalitis Lethargica: During and After the Epidemic. Oxford University Press 2010

Definition of autoimmune encephalitis The term autoimmune encephalitis is used to describe a group of disorders characterised by symptoms of the CNS (limbic, extra-limbic, basal ganglia, autonomic structures or more widespread) and occurring in recognised association with autoantibodies directed at epitopes expressed at such sites. If the brain stem, spinal cord or both are also affected, then the term encephalomyelitis is more accurate. Moreover, T-cell or humoral autoimmunity must also be either established or very likely to being so.

The autoantibodies may be against 1. Synaptic antigens at neurons (e.g. autoimmune synaptic encephalitis) 2. Presynaptic structures (e.g. GAD, Amphiphysin) 3. Structures localised at or within other cell surfaces of neurons and including axons 4. Channels at glial cells (e.g. AQP4) 5. Intracellular structures (e.g. paraneoplastic syndromes)

Please also see following page for details

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Current knowledge (three major groups of autoantibodies) In recent years, there is an increasing description of novel anti-neuronal & anti-glial antibodies that are associated with paraneoplastic and non-paraneoplastic neurological syndromes. These antibodies are useful in clinical practice to confirm the immune-mediated origin of the neurological disorder and are helpful in tumour search.

Currently, such antibodies can be classified according to the location of the recognized antigen into three major groups: 1. Intracellular antigens  Neuronal nuclear or nucleolar o Hu (ANNA1), Ri (ANNA2), ANNA3, Ta (Ma2), Ma1, ZIC4  Neuronal or muscular cytoplasmatic o Yo (PCA1), Tr, PCA2, GAD67, Gephyrin, CARP8, TG6 (TGM6), ENO1, striational muscle (Titin, RyR1, etc.) o Presynaptic stuctures: GAD65, Amphiphysin  Glial o CV2 (CRMP-5, POP66, oligodendrocytes), Bergman (AGNA, SOX-1), ENO1

2. Antigens located at or within the cell membrane  Voltage- or ligand-gated CSF or plasma membrane structures o Ionotropic channels and receptors . AChR (adult, foetal, alpha3, M1-types), NMDAR (NR1, NR2), AMPAR (GluR1, GluR2), Ca-channel (P/Q-type), GlyR-alpha1, DPPX (DPP6, Kv4.2) o Metabotropic channels and receptors . D1, D2, D3, D4, D5, GABABR1, GABABR3, mGluR1, mGluR5, 5HT2A, 5HT2C  Other membrane structures o AQP4 (astrocytes), MuSK, CASPR2, myelin oligodendrocyt glycoprotein (MOG), gangliosides including lyso-GM1, ENO1

3. Extracellular location of antigens  Synaptic proteins: LGI1

Different techniques are established for detecting these antibodies and other factors: 1. Tissue-based assay (TBA), detecting most of the antibodies 2. Cell-based assay (CBA, using transfected cells)  It appears that for some antigens (e.g. aquaporin, GlyR) in vivo cells are better, and for others (NMDAR, AMPAR, GABAR) fixed cells are superior 3. ELISA, immunoblot (IB, line blots), immunoprecipitation assay (IP) 4. Incubation of cultures nerve cells with serum or cerebrospinal fluid: measurement of enzymes (e.g. CamKII)

The group of disorders associated with antibodies to cell surface or synaptic proteins appears to be characterised by a more promising outcome of therapy – as opposed to those associated with autoantibodies to intracellular structures.

Epidemiology

Mean annual incidence rates per 100.000 population in Denmark Anti-NMDAR (NR1) Anti-LGI1 Paraneoplastic neurology Post-Streptococcal neurology 0.33 0.10 0.49 0.55

Mean annual incidence rates per 100,000 population Herpes simplex encephalitis in Sweden 0.22 Neuroborreliosis 3-11

Selected references 1. Berglund J, Eitrem R, Ornstein K, Lindberg A, Ringér A, Elmrud H, Carlsson M, Runehagen A, Svanborg C, Norrby R. An epidemiologic study of Lyme disease in southern Sweden. N Engl J Med 1995; 333: 1319-1327. 2. Hjalmarsson A, Blomqvist P, Sköldenberg B. Herpes simplex encephalitis in Sweden, 1990-2001: incidence, morbidity, and mortality. Clin Infect Dis 2007; 45 (7): 875-80. 3. Fingerle V, Schulte-Spechtel UC, Ruzic-Sabljic E et al.: Epidemiological aspects and molecular characterization of Borrelia burgdorferi s.l. from southern Germany with special respect to the new species Borrelia spielmanii sp. nov. Int J Med Microbiol 2008; 298 (3-4):279-90.

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

T-cell versus B-cell mediated autoimmunity

Autoimmunity directed at

Extracellular structures: B-cell mediated-humoral immunity – detected autoantibodies are both makers and of direct diagnostic significance

Intracellular structures: T-cell mediated, detected autoantibodies are markers

1. Autoimmunity provoked at locations outside the CNS and maybe later transferred into the brain  Autoimmune factors are present in a serum sample  Initially, autoimmune factors are not present in the cerebrospinal fluid  As long as the blood brain barrier (BBB) is intact, no CNS disorder is likely to occur  On the other hand, any later or current BBB defect may cause passive transfer and autoimmune encephalitis  Example: post-infectious autoimmune encephalitis

2. Autoimmunity provoked at locations inside the CNS (see table below) and maybe later transferred into the blood stream  Autoimmune factors are present in the cerebrospinal fluid  Initially, autoimmune factors are not present in the blood stream  Irrespectively of seropositivity and of the BBB, an autoimmune encephalitis is likely to be present – unless the levels of such factors are below a certain tolerated limit  Seropositivity may occur as a secondary event

Intrathecal synthesis of autoantibodies Year Type of encephalitis Reference 2001 Anti-GAD encephalitis Neurology 2001; 57: 780-784 2009 Anti-AMPAR (GluR1, GluR2) Ann Neurol 2009; 65 (4): 424–434 2010 Anti-NMDAR (NR1) J Neurosci 2010; 30 (17): 5866–5875 2014 Anti-DPPX (DPP6, Kv4.2) Neurology 2014; 82 (17): 1521-28

Experimental autoimmune encephalitis Year Type of encephalitis Reference 2003 Passive transfer of mGluR1 antibodies Ann Neurol 2003; 53 (3): 325-36 2004 Transfer of T-cells specific for the onconeural antigen Ma1 Brain 2004; 127: 1822–1830 2005 / Lancet. 2005; 365 (9468): 1406-11 Passive transfer of anti-Amphiphysin 2010 Brain (2010) 133 (11): 3166-3180 Experimental Neurology 2007; 204 (2): 808- 2007 Experimental autoimmune agrypnia 18 2009/ Ann Neurol 2009; 66 (5): 617-29 Passive transfer of anti-AQP4 2010 Ann Neurol 2009; 66 (5): 630-43 2010 Passive transfer of anti-NMDAR J Neurosci. 2010 April 28; 30(17): 5866–5875 2010 Mouse model – intra-cerebral injection of anti-AQP4 Brain 2010: 133; 349–361 Lewis rat animal model of Sydenham chorea and related Neuropsychopharmacology 2012; 37: 2076– 2012 neuropsychiatric disorders 2087 2014 Rat model – intra-striatal infusion of anti-streptococcal antibodies Brain Behav Immun 2014; 38: 249-62 2016 Rat model of anti-NMDAR encephalitis Brain Res. 2016;1 633: 10-8.

Immunological mechanisms It is likely that T-cell mediated autoimmunity is a key factor of many of the “classical” paraneoplastic neurological disorders associated with autoantibodies directed at intracellular epitopes.

In contrast, it appears that autoantibodies associated Synaptic encephalitis with synaptic encephalitis are B-cell mediated and Mechanisms of antibody-induced loss of operate by cross-linking their targets resulting in receptor immunomodulation (more rapid internalization of such structures), and thereby resulting in a relative lack of receptors. [J Neurosci 2010; 30 (17): 5866–5875] Currently, there are no scientific data to suggest that activated complement is a feature of synaptic encephalitis. Moreover, it appears that there are copious infiltrates of plasma cells/plasmablasts (antibody secreting) in the Modulation of the number and density of CNS of some of these patients. [J Neurosci 2010; 30 (17): receptors – more rapid internalization 5866–5875]. Such documented mechanisms are in agreement with the reported reversibility of autoimmune synaptic encephalitis upon adequate immunotherapy provided that such remedy is initiated as soon as possible, since such structures may be synthesized and then at a rate greater than that of the loss.

Mechanisms underlying cellular and synaptic effects of anti-NMDA receptor antibodies A-C: AMPA and NMDA receptors are localized in the postsynaptic membrane and are clustered at the postsynaptic density (A). Patient antibodies in the CNS bind selectively to NMDA receptors at the synapse as well as extrasynaptic receptors. This binding leads to receptor cross-linking (B). NMDA receptors that have been bound and cross-linked by antibodies are internalized, resulting in a decrease of surface, synoptically localized NMDA receptors. Other synaptic components, such as postsynaptic AMPA receptor clusters, PSD-95, as well as presynaptic terminals, dendrite branches, dendritic spines and cell viability, are unaffected (C). Thus patient anti-NMDA receptor antibodies lead to a rapid, selective excision of NMDA receptors from neuronal membranes. This effect is titer-dependent and reverses after antibody titres are reduced (not shown). J Neurosci 2010; 30 (17): 5866–5875

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Presenting symptoms of such disorders and that frequently are not paraneoplastic

Neuropsychiatric symptoms  Behavioural problems, changed personality  Depression, anxiety, fear, hallucinations, psychosis  Attention deficit/hyperactivity disorder (ADHD)  Obsessions, compulsions (OCD)  Anorexia

Neurological features  Memory loss or amnesia  Movement disorders & dystonia: motor or vocal tics, chorea, myokymia, oculogyric crises, catatonia, parkinsonism, rigidity, acute dystonia  Epilepsy: generalized, partial, myoclonus, episodes with series of hiccups (myoclonic jerks of the diaphragm)  Aphasia, mutism  Nystagmus, ataxia  Sleeping disorders: drowsiness, sluggishness (lethargy), sleep inversion  Decreased level of consciousness, stupor, unconsciousness  Autonomic features: instability of BT, hypoventilation, respiratory failure

Nephrologic  Hyponatriaemia (anti-LGI1) Gastrointestinal  Diarrhoea (anti-DPPX, DPP6)

Apart from in Hashimoto’s encephalitis, Rasmussen’s encephalitis and anti-GlyR encephalomyelitis, it appears that usually, paresis is not a feature. Moreover, fever is usually not an aspect.

In an individual patient, the clinical features can vary from one or a few symptoms to a more complex combination from this palette. The severity may be from mild to very severe. An expected finding of a particular autoantibody as well as distinguishing clinical features – in other words, the likelihood of any particular type of autoimmune encephalitis versus others, is related to the more specific molecular mechanisms. However and to speed up the diagnostic procedure, consider testing serum and often CSF for all relevant autoantibodies at once.

Overview of paraneoplastic encephalitides Paraneoplastic encephalitides: autoantibodies vs. neoplasms Short name (alphabetical order) Alias: anti- Primary analysis Associated neoplasms AGNA SOX1 Yes SCLC Anti-AMPAR GluR1/2 SCLC, non-SCLC, thymoma, breast Anti-Amphiphysin Yes Breast, SCLC Anti-BRSK2 SCLC Anti-CASPR2 Thymoma Anti-CV2 CRMP5,POP66 Yes SCLC, thymoma Anti-EFA6A Ovarian Anti-GAD SCLC, thymoma, breast Anti-GabaBR1 GABBR1 SCLC Anti-Hu ANNA-1 Yes SCLC, non-SCLC, Anti-K-channel-complex (anti-CASPR2, VgKC, VgPC SCLC, thymoma anti-LGI1) Anti-LGI1 90% idiotypic else paraneoplastic Anti-mGluR1 Ovarian, morbus Hodgkin Anti-mGluR5 Morbus Hodgkin Anti-NMDAR NR1 Idiotypic or teratoma Anti-Neurofilament Neuroblastoma Anti-PCA-2 SCLC Anti-Ri ANNA-2, Nova-1 Yes SCLC, non-SCLC, breast, ovarian Anti-Ta Ma2, PNMA2 Yes Testicular, ovarian Anti-Tr Purkinje cell (Tr) Yes Morbus Hodgkin Anti-Yo APCA-1, CDR-62 Yes Breast, ovarian, SCLC The true targets of antibodies previously attributed to voltage-gated potassium channels (VGKC) may in many cases by the recently reported antigens LGI1 and CASPR2 . LGI1 and CASPR2 are closely associated structures of the Kv1.1/Kv1.2-channel complex.

Co-occurrence of autoantibodies Autoantibody Anti- Anti- Anti-GAD Anti-GlyR Anti-DPPX Anti-ENO1 Anti-Hu AMPAR GABABR1 alpha1 Anti-NMDAR X Anti-AMPAR X Anti-GABABR1 X Anti-GAD X X X Anti-GlyR-alpha1 X Anti-CV2 (CRMP5) X X Anti-VGCC X X X LGI1, CASPR3 (“anti- X VGKC”) AGNA (anti-SOX1) X X Anti-BRSK2 X Anti-Amphiphysin X Anti-Ri X Anti-ZIC4 X Anti-thyreoglobulin X Anti-thyroid peroxidase X X X Anti-TSH receptor X Anti-M X Anti-dsDNA X ANA X X Anti-Cardiolipin X

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Reported presenting and subsequently occurring symptoms vs. specific type of autoantibody o Behavioural or personality change, psychosis o Cognitive dysfunctions, loss of memory o Dyskinesias, dystonia, or stereotyped movements, catatonia o Speech reduction o Seizures, status epilepticus Anti-NMDAR encephalitis o Sleep dysfunction, e.g. excessive daytime sleepiness (associated with decreased level of hypocretin) o Autonomic instability, decreased consciousness, hypoventilation (about 25%) o Recently, anti-NMDAR (IgA) has been reported in schizophrenia without noticeable signs of encephalitis o Behavioural change o Confusion, confabulation, agitation, combativeness, perseveration o Short-term memory loss o Various types of nystagmus: down or right beating Anti-AMPAR encephalitis o Epilepsy: focal motor seizures, generalized tonic-clonic seizures o Dysdiadochokinesia, gait ataxia o Insomnia, lethargy o Decreased level of consciousness o Cerebellitis Anti-mGluR1 encephalitis o Ataxia (truncal and gait), intention tremor Anti-mGluR5 encephalitis o Ophelia syndrome o Behavioural , personality change, psychosis o Cognitive dysfunctions, loss of memory Anti-LGI1 encephalitis o Faciobrachial tonic seizures; similar fits also affecting the lower extremities and slightly slower than typical myoclonus; generalized tonic-clonic seizures o Hyponatriaemia o Hyperexcitability (agitation, tremor, myoclonus, seizures) Anti-DPPX encephalitis o Diarrhoea o Behavioural problem o Paranoia, psychosis, gustatory and/or visual hallucinations o Confusion, disorientation, confabulation, agitation o Memory impairments o Abnormal orolingual movements, fluent aphasia o Epilepsy Anti-GABABR1 encephalitis o complex partial seizures o partial motor o generalised, generalised tonic-clonic seizures o status epilepticus o Sleeping disorder, agrypnia o Requiring intubation and ventilation o Decline in mental status leading to coma o Similar to anti-GABABR1 encephalitis Anti-GABAAR encephalitis o Epilepsy, status epilepticus, epilepsia partialis continua o Opticus neuritis o Longitudinally extensive transverse myelitis o Encephalopathy Anti-Aqp4 encephalitis o Ophthalmoparesis o Intractable vomiting, or hiccups o Seizures o Ataxia o ADEM, clinically isolated syndrome (CIS) Anti-MOG encephalitis o Recurrent opticus neuritis, transverse myelitis including LETM o Stiff-person spectrum of symptoms (SPS, and variants) including o PERM: progressive encephalomyelitis with rigidity and myoclonus o Also with anti-Glycine receptor [Neurology 2008; 71: 1291-1292] Anti-GAD encephalitis o Paraneoplastic limbic encephalitis with epilepsy o Palatal myoclonus o Autoimmune hyperekplexia (pronounced startle responses) o Progressive encephalomyelitis with rigidity and myoclonus (PERM), Stiff person sprctrum of Anti-GlyR α1 encephalitis symptoms o Hyperekplexia o Intial and prominent sleep disorder Anti-IgLON5 encephalitis

o Video polysomnography showing features of obstructive sleep apnoea, stridor, and abnormal sleep architecture o Maybe preceded by gait instability followed by dysarthria, dysphagia, ataxia, or chorea o Rapid progression with disequilibrium, dysarthria, dysphagia, and central hypoventilation o Movement disorders: tics (motor, vocal), chorea (usually affecting limbs; maybe unilateral), facial grimacing, motor hyperactivity , dystonia Anti-Dopamine receptor o Obsessive compulsive disorder (OCD) and / or restricted food intake (anorexia) encephalitis o Anxiety, episodes of unmotivated fear, emotional lability, psychosis o Behavioral (developmental) regression , aggression o Epilepsy, multifocal myoclonus (maybe elicited from thalamus) Post-streptococcal o Multifocal myokymia encephalitis o Slowed cognition, memory dysfunction o Sleep disorders, including sleep inversion o Gait ataxia o Ataxia Anti-TG6 encephalitis o Chorea o Myclonus, palatal tremor o Partial complex seizures o Polyneuropathy

Autoimmune encephalitis and epileptic seizures

In summary: recent studies in the field of paraneoplastic syndromes and autoimmune encephalitides provide several clues that suggest the immune aetiology of some types of epileptic disorders, including the acute presentation of symptoms, the frequent detection of CSF pleocytosis and oligoclonal bands in the context of negative viral studies, and the detection of CSF antibodies reacting with the neuropil of hippocampus and the cell surface of neurons.

These disorders can be divided into limbic and cortical extralimbic encephalitides (often combined) and may have paraneoplastic or non-paraneoplastic aetiology.

Paraneoplastic autoimmune encephalitis with epilepsy

Paraneoplastic associated While there is strong evidence that the first four immune responses are mediated antibodies include by cytotoxic T-cells responses, there are studies indicating that amphiphysin Anti-Hu antibodies may be directly pathogenic. Anti-mGluR5 encephalitis (Ophelia Anti-CV2 (CRMP5) syndrome) may also be antibody-mediated [84]. Anti-Ta (Ma2) Anti-Ri Of these five immune responses, the anti-Hu antibodies are those most Anti-Amphiphysin frequently described with seizures, epilepsia partialis continua, and status Anti-mGluR1 epilepticus. The underlying tumours are small-cell lung cancer (all antibodies), Anti-mGluR5 breast cancer (anti-Ri), germ-cell tumours of the testis (Ta/Ma2), and thymoma (CV2/CRMP5). With the exception of the encephalitis associated with Ta/Ma2 antibodies, in which approximately 30% of patients respond to tumour removal and immunotherapy, the other disorders are rarely treatment-responsive.

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Autoimmune encephalitides that are not strictly paraneoplastic

An expanding group of autoimmune encephalitides occur both with or without tumour association, and depending on the type of antibody. A frequent feature of these immune responses is that the autoantigens are extracellular and therefore accessible to circulating antibodies.

These antigens include o LGI1 and CASPR2, accessory proteins and being the true target antigens of antibodies previously attributed to voltage-gated potassium channels (VGKC).

LGI1, a secreted neuronal protein, is a Not strictly paraneoplastic associated antibodies target antigen of limbic encephalitis. include Interestingly, this disorder associates with Extracellular frequent seizures (about 80% of such patients) along with hyponatriaemia. Anti-NMDAR (NR1) Yes Moreover, mutations of LGI1 are the cause Anti-LGI1 Yes of autosomal dominant partial epilepsy Anti-AMPAR (GluR1, GluR2) Yes with features (ADPEAF), also called Anti-AMPAR (GluR3, GluR4) Yes autosomal dominant lateral temporal lobe Anti-GABABR1 Yes epilepsy. Anti-GABAAR (α1/β3 subunits) Yes In contrast, CASPR2, a protein that is Anti-GlyR alpha1 Yes expressed in brain and peripheral nerve, Anti-AQP4 (astrocytes) Yes clustering the VGKC at the juxtaparanodal Anti-D1, anti-D2, anti-lyso-GM1 Yes regions of myelinated axons is the target Anti-DPPX (Kv4.2) Yes antigen of encephalitis (Morvan’s Anti-IgLON5 Yes syndrome) and peripheral nerve Anti-Alpha-enolase (ENO1) Yes/No hyperexcitability (Isaacs syndrome Anti-GAD Yes/No# Anti-TG6 No o Excitatory glutamatergic receptors A finding of antibodies to extracellular epitopes at synapses would classify a (NMDA, AMPA) disorder as autoimmune synaptic encephalopathy # Located at presynaptic vesicles (GAD65) or intracellularly (GAD67) Antibodies to the NR1 subunit of the NMDAR associate with a characteristic syndrome that presents with behavioural change or psychosis and usually progresses to a decline of the level of consciousness, catatonia, seizures, dyskinesias, autonomic instability, and frequent hypoventilation. Anti-AMPAR (GluR1 and GluR2) encephalitis is not associated with neoplasia in about 30 %. Anti-GluR3 is associated with autoimmune epilepsy, including after bone marrow transplantation. o Inhibitory GABA-receptors Both GABABR1 and GABAAR (α1/β3 subunits) associate with a clinical picture of limbic encephalitis and with early and prominent seizures. o GABAAR Epilepsy, status epilepticus, epilepsia partialis continua o Anti-AQP4 Associated with neuromyelitis (NMO, Devic’s syndrome including LETM) and epilepsy

13 o GAD antibodies usually associate with stiff-person syndrome and cerebellar dysfunction, but there are increasing number of reports showing that these antibodies also occur with subtypes of limbic encephalitis and refractory epilepsy o Glycine receptors antibodies (anti-GlyR alpha1) usually associate with atypical stiff-person or stiff-limb syndrome (without anti-GAD), progressive encephalomyelitis with rigidity and myoclonus (PERM), or autoimmune hyperekplexia. The GlyR are among the most widely distributed inhibitory receptors in the central nervous system. GlyRs are primarily expressed in spinal cord, brain stem, caudal brain, and retina. In adult neurons, the inhibitory chloride influx upon glycine receptor activation stabilizes the resting potential of the cell, rendering them electrically quiescent o Anti-D1, anti-D2, anti-lyso-GM1 are findings related to the post-streptococcal neurological syndrome o Anti-Alpha-enolase (ENO1) is associated with Hashimoto’s encephalitis and autoimmune thyroiditis o Anti-TG6 (neuronal transglutaminase; TGM6; Transglutiminase Y; TGY) is a feature of gluten associoated ataxia and coeliac disease

Autoimmune epilepsy and psychiatry Autoantibodies Autoimmune disorder Characteristic epileptic activity Psychiatry Anti-NMDAR (NR1) Encephalitis Generalized motor Behavioural or personality change, Status epilepticus , dystonic fits psychosis Anti-AMPAR (GluR1, Encephalitis Focal motor seizures Behavioural change, confusion, GluR2) Generalized tonic-clonic seizures confabulation, agitation, combativeness, perseveration Anti-AMPAR (GluR3) Encephalitis Myoclonic, maybe refractory Anti-LGI1 Limbic encephalitis Faciobrachial tonic seizures; similar fits Confusion, personality change or also affecting the lower extremities, psychosis slightly slower than typical myoclonus Generalized tonic-clonic seizures

Anti-GABABR1 Encephalitis Complex partial seizures Behavioural problems, confusion, Partial or generalised motor disorientation, confabulation, Generalised tonic-clonic seizures agitation, Status epilepticus paranoia, gustatory and/or visual hallucinations, psychosis Anti-D1, anti-D2, anti- Post-streptococcal neurology Multifocal myoclonic OCD, anxiety, fear lyso-GM1 Multifocal myokymia Anti-GAD Stiff-person complex, Motor seizures, maybe refractory Unspecific, resembling encephalitis psychosomatic Anti-GlyR alpha1 Stiff-person complex, Motor seizures Unspecific, resembling encephalitis psychosomatic Anti-Hu Paraneoplastic Motor seizures Mental status and mood changes encephalomyelitis, Epilepsia partialis continua neuronopathy Status epilepticus Anti-CV2 (CRMP5) Paraneoplastic encephalitis Motor seizures Mental status and mood changes Status epilepticus Anti-TG6 Gluten associated ataxia Myoclonus, complex partial seizures ADHD?

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Child & Adolescent Psychiatry and Neurology: occurrence of analogous symptoms Autoimmune encephalitis – autoimmune psychosis Disorder Aliases, various diagnoses Presenting and distinctive features Autoantibodies and more Anti-NMDAR encephalitis: Anti-NMDAR (glutamate NR1); frequent in children and Behaviour changes, cognitive maybe with a coexistent in a major number of Dyskinetic encephalitis dysfunctions, loss of memory, seizures, teratoma and also associated psychosis, dyskinesias, catatonia, sleep with mycoplasma pneumoniae cases previously lethargica disorder, mutism, and sometimes, infection; categorised as of hypoventilation herpes simplex encephalitis; unknown aetiology Guillan-Barré syndrome Anti-Ta (Ma2, testis tumour); PEM = paraneoplastic Limbic encephalitis and Personality changes, disorientation, anti-Tr (morbus Hodgkin); memory loss, anxiety, OCD encephalomyelitis more anti-LGI1, and many others Broad spectrum of autoimmune Dyskinesias: tics (motor, vocal), chorea encephalitis: PANDAS, (usually affecting limbs), facial PANS, CANS, Sydenham grimacing; motoric hyperactivity, Autoimmune post- obsessive compulsive disorder (OCD); chorea, Tourette Anti-lyso-GM1, anti-D1, anti-D2, streptococcal neurological fear, anxiety; epilepsy (including syndrome, basal ganglia anti-Tubulin, CamKII syndrome multifocal myoclonus); slowed encephalitis, encephalitis cognition; hypotonia, multifocal lethargica, acute or myokymia; gait ataxia; anorexia, relapsing encephalitis? bulimia; sleep disorders

Usually (93%) follows an ADEM: acute infection of some kind: Confusion, drowsiness, and even coma; unsteadiness and falling; trouble disseminated viral or bacterial; Anti-MOG swallowing; weakness of arms or legs; encephalomyelitis occasionally, a visual blurring or double vision vaccination Optic neuritis, transverse myelitis, or CNS anti-AQP4 both; episodic cerebral symptoms (encephalopathy, ophthalmoparesis, Anti-AQP4 autoimmunity in children ataxia, seizures, intractable vomiting, or hiccups) Anti-alpha-Enolase 1; Disorientation, psychosis, concentration Hashimoto’s anti-Thyreoglobulin; Hashimoto ‘s thyroiditis and memory problems, tremors, jerks in anti-Thyroid Peroxidase; encephalopathy the muscles (epilepsy) anti-TSH receptor Ataxia, chorea, myclonus, palatal Gluten associated ataxia, tremor, Anti-TG6 encephalitis Anti-TG6 (IgG, IgA) coelic disease partial complex seizures, polyneuropathy Unknown, since a previous report Mental deterioration, seizures, loss of Rasmussen’s encephalitis of anti-GluR3 as a feature cannot motor skills and speech, hemiparesis be reproduced

Proposed diagnostic strategy - autoantibodies

Autoimmune encephalitis: autoantibodies Autoimmunity directed at Pathogenic mechanisms Alias extracellular structures Anti-NMDAR (NR1) GRIN1 Anti-AMPAR (1) GluR1, GRIA1 Anti-AMPAR (2) GluR2, GRIA2 Anti-LGI1 Anti-CASPR2 CNTNAP2 Anti-GABA(B)R1 GABBR1 Idiopathic - not paraneoplastic Anti-GABA(A)R3 GABRB3 Post-infectious Anti-AQP4 (M23, M1) Paraneoplastic Anti-GlyR alpha1 GLRA1 Anti-lyso-GM1 Anti-D1 Anti-D2 Anti-DPPX DPP6, Kv4.2 Anti-mGluR1 GRM1 Anti-mGluR5 GRM5 Anti-IGLON5 Demyelinating Anti-MOG

Autoimmune encephalitis: autoantibodies Autoimmunity directed at Pathogenic mechanisms Alias intracellular structures Post-infectious Anti-beta-Tubulin Stiff-person syndrome and Anti-GAD65 more Anti-GAD67 Hashimoto encephalitis Anti-ENO1 Gluten-sensitivity Anti-TG6 TGM6 Anti-Hu ANNA1 Anti-Yo PCA1 Anti-Ri ANNA2 Anti-Amphiphysin1 Anti-CV2 CRMP5 Strictly paraneoplastic Anti-Ta Ma2, PNMA2 Anti-Tr PCA-Tr, PCA2 Anti-SOX1 AGNA Anti-Recoverin Anti-ZIC4 Anti-Gephyrin

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Since in many cases the clinical features are similar, consider more rapid diagnostics by requesting one or more panel(s) rather than single analyses – and if this first step does not provide any positive results, then one or more supplemental analyses may be relevant.

Paraneoplastic panel Anti-Hu "Synaptic panel" Anti-Yo Post-streptococcal panel Anti-NMDAR1(NR1) Anti-Ri CamKII percentage Anti-AMPAR 1+2 Anti-Amphiphysin1 Anti-lyso-GM1 Anti-LGI1 Anti-CV2 Anti-D1 Anti-CASPR2 Anti-Ta Anti-D2 Anti-GABA(B)R1 Anti-Tr Anti-beta-Tubulin Anti-GAD65 Anti-ZIC4 Anti-SOX1 Anti-Recoverin

Supplemental extracellular Anti-AQP4 Anti-GlyR alpha1 Supplemental thyroiditis AntiDPPX Supplemental panel intracellular Anti-MOG Anti-TPO Anti-TG6 Anti-mGluR1 Anti-TG Anti-ENO1 Anti-mGluR5 Anti-TSH Anti-Gephyrin Anti-IGLON5 Anti-GABA(A)R3

General comments

Short summary The finding of neurologic specific autoantibodies  A cornerstone in new classifications of autoimmune encephalitides  Enables a rational basis of categorization into various groups & subgroups  Enables a more rational therapeutic strategy Evaluation of autoantibodies – serum & cerebrospinal fluid (CSF) Please note that in some cases, specific autoantibodies are not a feature of serum Accordingly and if expected autoantibodies are not found in a serum sample, always include examination of CSF in the diagnostic procedures Intrathecal synthesis of specific autoantibodies can be a feature of some autoimmune encephalitides These disorders may be with or without association to a neoplasm Paraneoplastic autoantibodies are always markers of neoplasia under development, although not necessarily markers of a neurological disorder – since this takes associated such symptoms to evolve as well, even though typically, this happens weeks or months before an associated tumour is diagnosed Rapid diagnostic procedures and commencement of therapy can be of major significance

Prompt recognition of all the disorders associated with antibodies against cell surface antigens is important  They may also affect children and young adults (typical of anti-NMDAR encephalitis) o If anti-NMDAR (NR1) seronegative, then consider including testing the cerebrospinal fluid  They are responsive to immunotherapy and/or oncological remedies when appropriate  Unfortunately, it appears that anti-GAD associated encephalomyelitis is less treatment-responsive

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Algorithmic approach to diagnosis and treatment of encephalitis with antibodies to intracellular or cell surface neuronal antigens

From: Lancaster E, Martinez-Hernandez E, Dalmau J. Encephalitis and antibodies to synaptic and neuronal cell surface proteins. Neurology 2011; 77 (2): 179-89.

Various specific disorders: autoimmune encephalitis directed at extracellular structures, including synaptic, presynaptic and other related ones

Characteristics of anti-NMDAR (NR1) - glutamate receptor subunit zeta-1 – GluN1 - encephalitis The N368/G369 region of GluN1 amino terminal domain is crucial for the creation of immunoreactivity J Neurosci 2012; 32 (32): 11082-94

Definition of anti-NMDAR encephalitis 1. A specific syndrome characterized by anti-NMDAR of IgG type and directed at the NR1 subunit. Attributable to intrathecal synthesis of these autoantibodies, this is a feature of the cerebrospinal fluid in all cases (100 %), while seropositivity is estimated to be up to 90 %. There is no evidence to suggest that psychosis as part of the symptomatology may progress into schizophrenia fulfilling the ICD-10 criteria. 2. As a non-specific syndrome, anti-NMDAR (NR1) of IgA or IgM type has been associated with both cognitive dysfunctions and schizophrenia. Pooling all types together (IgG, IgA and IgM), anti- NMDAR (NR1) has been reported in about 10.5 % of healthy sera and similar to the frequency in a large population of schizophrenics or other psychiatric disorders (Hammer C et al. Molecular Psychiatry September 2013). Moreover, such seropositivity may depend on expression of both NR1 and NR2 subunits, as opposed to results of assays using monomeric NR1. High prevalence of NMDA receptor IgA/IgM antibodies has been reported in a significant number of dementia patients, and in particular in those of unclassified type (Doss S, Wandinger KP, Hyman BT, et al. Ann Clin Transl Neurol 2014; 1 (10): 822-32). In cases with IgA/IgM seropositivity only, consider testing again at a later point in time to discover if this finding was either temporary or has evolved into IgG seropositivity. 3. Anti-NMDAR directed at the NR2 subunit has been reported (NR2A, NR2B) in association with various autoimmune disorders, e.g. LED and neurolupus and not as specific syndromes.

Investigations  CSF o Anti-NMDAR (NR1, IgG, IgA) o Herpes simplex (polymerase chain reaction) o Oligoclonal banding o Hypocretin-1 level  Serum o Anti-NMDAR (NR1, IgG, IgA)  In most cases, the anti-NMDAR NR1() antibodies are of IgG-type. Anti-NMDA (NR1 IgA) has been reported in association with schizophenia-like psychosis, cognitive dysfunctions, epilepsy, narcolepsy-catatonia and more o Mycoplasma pneumoniae antibodies o Herpes simplex (polymerase chain reaction o Other neuro-infection?  Consider throat swap, mucus from airways o PCR amplification to test for mycoplasma pneumoniae genes 30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

 MRI More or less asymmetrical medial temporal lobe hyperintense signal. Note: MRI findings may be minimal or normal. Therefore, do consider repeated investigations later-on, if unrevealing at first examination

 PET and including translocator protein (TSPO) imaging may reveal neuroinflammation (microglia)

Neoplasm  Males: only few teratomas have been reported (such neoplasm are rare in the testis, accounting for only 3-5 % of germ cell tumours)

 Females Female patients Age group, years Frequency of teratomas Older than 18 56 % 14.1 – 18 31 % Up to 14 9 % Treatment . Immunotherapy Intravenous high-dose IgG, steroids, Rituximab, Alemtuzumab, intrathecal Methotrexate Cyclophosphamide . Oncologic (paraneoplastic type)

Anti-NMDAR encephalitis MRI scan of the patient at symptom presentation and follow- up

(A) MRI fluid-attenuated inversion recovery (FLAIR) obtained at symptom presentation demonstrates bilateral medial temporal lobe hyperintense signal, predominantly involving the left hippocampus (arrows).

(B) Follow-up MRI obtained during recovery, 4 months after the initial MRI, shows considerable improvement of the FLAIR hyperintensity

Case series of anti-NMDAR patients (n=100) and info from various other sources Types of autoimmune anti-NMDAR encephalitis Epidemiology Of unknown cause Median age of patients: 23 years (range 5—76 years) Post-infectious Anti-NMDAR encephalitis is increasingly recognized in Paraneoplastic children and appears to account for a major percentage of As a manifestation of SLE. It has been reported that up to 25 encephalitides cases, previously categorized as of unknown % of SLE patents may have anti-NMDAR (NR2) in their sera. cause in such infants Susceptibility to SLE has an associated gene map locus: 12p12 (GRIN2B), being the gene of MNDA glutamate receptor NR2B. Anti-NMDAR seropositivity In an individual patient, these autoantibodies may be to NMDAR (NR1), NMDAR (NR2) or both. Therefore, an appropriate assay testing for anti-NMDAR must cover both, although possibly, anti-NMDAR (NR2) may be more relevant in a context of SLE and neurolupus Studies have established the cellular mechanisms through which antibodies of patients with anti-NMDAR encephalitis cause a specific, titer-dependent, and reversible loss of NMDARs (J Neurosci 2010; 30 (17): 5866–5875) Complement-mediated mechanisms do not appear to play a substantial pathogenic role in anti-NMDAR encephalitis. In contrast, there are copious infiltrates of antibody-secreting cells (plasma cells/plasmablasts) in the CNS of these patients. The demonstration of these cells provides an explanation for the intrathecal synthesis of antibodies and has implications for treatment. (Neurology 2011; 77 (6): 589-93) Moreover, anti-NMDA receptor encephalitis antibody binding appears to be dependent on amino acid identity of a small region within the GluN1 amino terminal domain. (J Neurosci 2012; 32 (32): 11082-94.) In addition to anti-NMDAR (IgG) positive cases, also anti-NMDAR of IgA type and without co-existing IgG-type has been reported: (Neurology 2012; 78 (22): 1743-53.) A paraneoplastic (teratoma) origin has been reported (Annals of Neurology 2007; 61 (1); The Lancet Neurology 2008; 7 (12): 1091-98.) Onset of anti-NMDAR encephalitis may occur during an acute mycoplasma infection (Eur J Clin Microbiol Infect Dis 2009; 28 (12): 1421-9.) NMDAR antibodies of the immunoglobulin (Ig) subtypes IgA, IgG, or IgM have been reported in 13 of 44 patients (30%) in the course of herpes simplex encephalitis, suggesting secondary autoimmune mechanisms. (Ann Neurol 2012; 72(6): 902-11.) Case history: A Young Man with Anti-NMDAR Encephalitis following Guillain-Barré Syndrome. Karger case reports in neurology 2011. IgA-type NMDAR (NR1) may be a feature of schizophrenia. (BMC Psychiatry 2012; 12: 37; JAMA Psychiatry 2013; 70 (3): 271-8.) IgA NMDA receptor antibodies are reported as markers of synaptic immunity in slow cognitive impairment. (Neurology 2012; 78 (22): 1743-53.) Relapses in anti-NMDAR encephalitis appear to be common (24 % Neurology 2011; 77 (6): 589-93). Co-existence of anti-AQP4 and anti-MOG with anti-NMDAR (NR1) has been reported (Ann Neurol. 2014; 75 (3): 411-28.) Currently, the significances of anti-NMDAR of IgM type and maybe of IgA are unclear. In such cases, consider testing again at a later point in time to discover if this finding was either temporary or has evolved into IgG seropositivity. Neuropsychiatric features (80 – 90 %) Behavioural or personality change, psychosis Cognitive dysfunctions, loss of memory Dyskinesias, dystonia, or stereotyped movements, catatonia, ataxia Speech reduction Seizures, status epilepticus Sleep dysfunction, e.g. excessive daytime sleepiness (associated with decreased level of hypocretin) Autonomic instability, decreased consciousness, hypoventilation (about 25%) Rarer presenting features may include hyperacusis and deafness Reference: Dalmau J, Gleichmann AJ, Hughes EG, et al. Lancet Neurology 2008; 7: 1091-1098

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Incubation with anti-NMDAR positive serum Cell based assay (CBA): HEK293 cells transfected with Various CNS tissues and CBA recombinant NMDA receptor

Selected references (additional and chronological refs. at the end of this compendium ) 1. Dalmau J, Gleichman AJ, Hughes EG, et al. Anti-NMDA-receptor encephalitis: case series and analysis of the effects of antibodies. Lancet Neurol 2008; 7: 1091-1098. Summary | Full Text 2. Pruss H, Dalmau J, Harms L, et al. Retrospective analysis of NMDA receptor antibodies in encephalitis of unknown origin. Neurology 2010; 75: 1735-1739.| PubMed 3. Dalmau J, Lancaster E, Martinez-Hernandez E, Rosenfeld MR, Balice-Gordon R. Clinical experience and laboratory investigations in patients with anti-NMDAR encephalitis [review]. Lancet Neurol 2011; 10 (1): 63-74. 4. Zandi MS, Irani SR, Lang B, et al. Disease-relevant autoantibodies in first episode schizophrenia. J Neurol 2011; 258: 686-688. PubMed; Full Text 5. Rhoads J, Guirgis H, McKnight C, Duchemin AM. Lack of anti-NMDA receptor autoantibodies in the serum of subjects with schizophrenia. Schizophr Res 2011; 129: 213-214. | PubMed 6. Martinez-Hernandez E, Horvath J, Shiloh-Malawsky Y, Sangha N, Martinez-Lage M, Dalmau J. Analysis of complement and plasma cells in the brain of patients with anti-NMDAR encephalitis. Neurology 2011; 77: 589- 593. | PubMed 7. Gleichman AJ, Spruce LA, Dalmau J, Seeholzer SH, Lynch DR. Anti-NMDA receptor encephalitis antibody binding is dependent on amino acid identity of a small region within the GluN1 amino terminal domain. J Neurosci 2012; 32 (32): 11082-94 8. Masdeu JC, Gonzalez-Pinto A, Matute C, et al. Serum IgG antibodies against the NR1 subunit of the NMDA receptor not detected in schizophrenia. Am J Psychiatry 2012; 169: 1120-1121. | PubMed 9. Pruss H, Finke C, Holtje M, et al. N-methyl-D-aspartate receptor antibodies in herpes simplex encephalitis. Ann Neurol 2012; 72: 902-911. | PubMed 10. Pruss H, Holtje M, Maier N, et al. IgA NMDA receptor antibodies are markers of synaptic immunity in slow cognitive impairment. Neurology 2012; 78: 1743-1753. | PubMed 11. Armangue T, Titulaer MJ, Malaga I, et al. Pediatric Anti-N-methyl-D-Aspartate receptor encephalitis—clinical analysis and novel findings in a series of 20 patients. J Pediatr 2013; 162 (4): 850-856. PubMed 12. Leypoldt F, Gelderblom M, Schottle D, Hoffmann S, Wandinger KP. Recovery from severe frontotemporal dysfunction at 3 years after N-methyl-d-aspartic acid (NMDA) receptor antibody encephalitis. J Clin Neurosci 2013; 4: 611-613. PubMed 13. Steiner J, Walter M, Glanz W, et al. Increased prevalence of diverse N-Methyl-D-Aspartate glutamate receptor antibodies in patients with an initial diagnosis of schizophrenia: specific relevance of IgG NR1a antibodies for distinction from N -Methyl-D-Aspartate glutamate receptor encephalitis. JAMA Psychiatry 2013; 70: 271-278. PubMed 14. Titulaer MJ, McCracken L, Gabilondo I, et al. Treatment and prognostic factors for long-term outcome in patients with anti-NMDA receptor encephalitis: an observational cohort study. Lancet Neurol 2013; 12: 157-165.

15. Panzer JA, Lynch DR. Neuroimmunology: treatment of anti-NMDA receptor encephalitis-time to be bold?. Nat Rev Neurol 2013; 9 (4): 187-187. PubMed 16. Hammer C, Stepniak B , Schneider A, et al. Neuropsychiatric disease relevance of circulating anti-NMDA receptor autoantibodies depends on blood–brain barrier integrity. Molecular Psychiatry advance online publication 3 September 2013 17. Titulaer MJ, Höftberger R, Iizuka T, Leypoldt F, McCracken L, Cellucci T, Benson LA, Shu H, Irioka T, Hirano M, Singh G, Calvo AC, Kaida K, Morales PS, Wirtz PW, Yamamoto T, Reindl M, Rosenfeld MR, Graus F, Saiz A, Dalmau J. Overlapping demyelinating syndromes and anti–N-methyl-D-aspartate receptor encephalitis. Ann Neurol. 2014; 75 (3): 411-28. 18. Steiner J, Teegen B, Schiltz K, Bernstein H, Stoecker W, Bogerts B. Prevalence of N-Methyl-D-Aspartate Receptor Autoantibodies in the Peripheral Blood: Healthy Control Samples Revisited. JAMA Psychiatry 2014; 71 (7): 838- 839. 19. Doss S, Wandinger KP, Hyman BT, et al. High prevalence of NMDA receptor IgA/IgM antibodies in different dementia types. Ann Clin Transl Neurol 2014; 1 (10): 822-32. 20. Prüss H, Leubner J, Wenke NK, Czirják CA, Szentiks CA, Greenwood AD. Anti-NMDA Receptor Encephalitis in the Polar Bear (Ursus maritimus) Knut. Sci Rep. 2015; 5: 12805. 21. Würdemann T, Kersten M, Tokay T, Guli X, Kober M, Rohde M, Porath K, Sellmann T, Bien CG, Köhling R, Kirschstein T. Stereotactic injection of cerebrospinal fluid from anti-NMDA receptor encephalitis into rat dentate gyrus impairs NMDA receptor function. Brain Res. 2016;1 633: 10-8.

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Characteristics of anti-AMPAR (GluR1, GluR2) encephalitis Distinguishing feature: various types of nystagmus, dysdiadochokinesis, gait ataxia

Clinical features, CSF, EEG, and MRI findings (patients n = 10, females 90 %, age range: 38 – 87 years) From:. Lai M, Hughes EG, Peng X, et al. Ann Neurol 2009; 65(4): 424–434 Associated neoplasms: thymus, non-SCLC, SCLC, breast No neoplasm: 30% Frequent relapses after treatment (60 Findings of additional antibodies: ANA, anti-dsDNA, anti-Cardiolipin, %) anti-GAD, anti-CV2 (CRMP5), anti-VGCC, AGNA (anti-SOX1) Brain MRI Initial EEG Symptom presentation Anti- GluR1/2 Cerebrospinal fluid Not available: 20% (FLAIR) (main antigen) (various combinations) Normal: 20% Not available: 10% Normal: 10% WBC Diffuse theta 6 – 75 (normal <4/μl ) activity or only in  Behavioural change posterior temporal  Confusion, confabulation, Elevated regions All seropositive Mild increased signal agitation, combativeness, protein 70 % in medial temporal (normal 16-46 Slow activity in the (GluR1: 30 % perseveration, psychosis lobes mg/dl) right temporal GluR2: 70 % )  Short-term memory loss region or more  Various types of nystagmus: Or increased signal in Oligoclonal diffuse Such antibodies down or right beating > 30 % the right medial and bands alter the number lateral temporal  Epilepsy: focal motor seizures, Episodes of and localization lobe, right frontal, generalized tonic-clonic seizures Intrathecal epileptic activity in of AMPARs in left insular and left  Dysdiadochokinesis, gait ataxia synthesis of > 30% left temporal lobe live neurons anti-AMPAR occipital regions  Insomnia, lethargy  Decreased level of consciousness Bilateral sharp Glucose levels normal waves in temporal lobes

Immunolabeling of rat brain by patients antibodies Sagittal section of rat brain incubated with the CSF of a patient with limbic encephalitis and novel antibodies.

Note the intense reactivity of the patient's antibodies with the neuropil of hippocampus (Hip), subiculum (S), molecular layer of the cerebellum and Purkinje cells (CB), caudate-putamen (CPu), and cerebral cortex (Ctx).

Other regions of the brain (e.g., corpus callosum (cc) and brainstem (B)) do not show significant immunolabeling. The areas boxed in A correspond to hippocampus and cerebellum and are shown at high magnification in B and D.

The box in B is located at the dentate gyrus and is shown amplified in C. In panels B-D the nuclei of the cells is demonstrated with 4',6- diamidino-2-phenylindole (DAPI).

Immunofluorescent technique, A × 2.5; B and D × 200; C × 400

Treatment . Immunotherapy at presentation and relapses o Steroids, plasmapheresis, intravenous high-dose IgG, Rituximab, . Consider chronic treatment with azathioprine, cyclophosphamide or related drugs . Oncologic (paraneoplastic type)

Selected references 1. Lai M, Hughes EG, Peng X, Zhou L, Gleichman AJ, Shu H, Matà S, Kremens D, Vitaliani R, Geschwind MD, Bataller L, Kalb RG, Davis R, Graus F, Lynch DR, Balice-Gordon R, Dalmau J. AMPA receptor antibodies in limbic encephalitis alter synaptic receptor location. Ann Neurol 2009; 65 (4): 424-34. 2. Graus F, Boronat A, et. al. The expanding clinical profile of anti-AMPA receptor encephalitis. Neurology 2010; 24: 857-59

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Characteristics of anti-LGI1, anti-CASPR2, DPPX - accessory proteins and subunit of VGKCs - encephalitis

Characteristics of anti-LGI1 (leucine-rich, glioma inactivated 1) encephalitis It has been somewhat puzzling how these antibodies could cause a wide range of different clinical presentations: cognitve dysfunctions / failing memory; unexplained subacute onset of epilepsy; psychosis; hyperexcitability syndromes of peripheral nerve.

However, it appears that the majority of “VGKC-antibodies” of high titre are not directed towards the Kv subunits themselves but to accessory proteins, LGI1 (leucine-rich, glioma inactivated 1) and CASPR2 (contactin associated protein-like 2), both being the true targets. LGI1 and CASPR2 are closely associated with VGKCs in brain and other tissues.

The classical RIA for detection of anti-VGKC is using radiolabelled dendrotoxin and 2% digitonin extracts of VGKCs also containing complexed LGI1 and CASPR2, explaining the long-standing misenterpretation of such results as anti-VGKC.

LGI1, CASPR2 and Contactin2 form part of trans-synaptic complexes and neuronal cell adhesion molecules involved in fine-tuning synaptic transmission and nerve excitability.

 LGI1 antibodies are found almost exclusively in patients with limbic encephalitis or epilepsy, 89% without and 11% with tumours, respectively [Lancet Neurol 2010; 9(8):776-85]  CASPR2 antibodies are found in patients with limbic encephalitis, Morvan’s syndrome or neuromyotonia, often co-existent with thymomas [J Thorac Oncol 2010; 5(10 Suppl 4): S277-80]. CASPR2 mediates cell–cell interactions and has a critical role in concentrating VGKCs located at juxtaparanodal regions of myelinated axons and in the hippocampus and cerebellum. The immunomodulatory effect of anti- CASPR2 causes a reduced number and decreased density of such potassium channels which is detrimental to transmission. Accordingly, the associated autoimmune disorders, acquired neuromyotonia or Isaacs’s syndrome and limbic encephalitis, respectively, are explicable by such mechanisms. -- An analogue mechanism is known in anti-MuSK myasthenia gravis, since MuSK is a molecular device for the aggregation of AChRs.  Contactin2 antibodies appear to be uncommon and often coexist with CASPR2 antibodies [Irani et al., Brain 2010; 133 (9): 2734-2748].

As related to autoimune encephalitis, the clinical observations also match the genetic diseases associated with LGI1 and CASPR2 mutations. LGI1 mutations produce a lateral temporal lobe epilepsy syndrome without peripheral nervous system involvement [Kalachikov et al., Nat Genet 2002; 30 (3): 335-41; Morante-Redolat et al., Hum Mol Genet 2002; 11 (9): 1119-1128]. CASPR2 mutations have been found in a family with cognitive impairment, epilepsy, and areflexia, emphasizing its functional importance in peripheral and central neurons [Strauss et al., N Engl J Med 2006; 354:1370-1377].

LGI1 is the main target autoantigen of the limbic encephalitis previously attributed to anti-VGKC The interaction of voltage-gated potassium (Kv) channels with proteins like LGI1, calmodulin, ZIP, or PSD-95 can have dramatic effects on gating, cellular localization, and turnover of such channels

LGI1: Leucine-rich, glioma inactivated 1 Chromosome: 10q24 1. LGI1 homo sapiens - Gene result 2. LGI1 Gene - GeneCards | LGI1 Protein | LGI1 Antibody

 Secreted synaptic protein  Associates with VGKCs and AMPA receptors via the ADAM proteins  LGI1-null mice have seizures and early death Human mutations associate with “autosomal dominant lateral temporal lobe epilepsy” with auditory features (ADPEAF)

 LGI1 is a ligand for ADAM22 that positively regulates synaptic transmission mediated by AMPA-type glutamate receptors (by similarity). The molecular function of ADAM22 is as a receptor, and it is highly expressed in the brain  ADAM23 can bind to LGI1, and is highly expressed in the brain, prominently in the amygdala, caudate nucleus, hypothalamus, thalamus, cerebral cortex and occipital pole  Regulates voltage-gated potassium channels assembled from KCNA1, KCNA4 and KCNAB1  Slows down channel inactivation by precluding channel closure mediated by the KCNAB1 subunit  Plays a role in suppressing the production of MMP1/3 through the phosphatidylinositol 3-kinase/ERK pathway  LGI1 down-regulates glutamatergic synapses during postnatal life

Accessory proteins to vgKCs: LGI1, CASPR2 and contactin2 – and tightly associated with such channels

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Distinguishing features of anti-LGI1 encephalitis: faciobrachial tonic seizures; similar fits also affecting the lower extremities (slightly slower than typical myoclonus) & hyponatriaemia

The following table summarizes a variety of features (patients n=57) Anti-LGI1 encephalitis Demographics MRI Men 65 % Increased T2 signal involving medial temporal lobe 84 % Age (years) 60 (30-80) Paraneoplastic background 11 % EEG Tumours present n = n = 57 (6) Any abnormality 76 % Thyroid 2 4 % (33 %) Seizures 32 % Lung 1 2 % (17 %) Epileptiform discharges 12 % Thymoma 1 2 % (17 %) Diffuse or focal slowing 32 % Ovarian teratoma 1 2 % (17 %) Renal cell 1 2 % (17 %) Modalities of treatment Relapsing course 18 % Steroids 84 % Clinical features Intravenous IgG 62 % Limbic encephalitis 100 % Plasma exchange 6 % Memory loss < 100 % Others (rituximab, azathioprine, or cyclosporine) 12 % Seizures including generalized ones 82 % Any treatment 96 % Faciobrachial tonic seizures 40 % Confusion, personality change or < 100 % Clinical outcomes psychosis Hyponatriaemia 60 % Full recovery 24% Serum sodium (mM) 128 (118-132) Mild disability 54% Cerebrospinal fluid Moderate disability 16% Any abnormality 41 % Death 6% Elevated protein 28 % Lymphocytic pleocytosis 17 % Hyponatriaemia (60%) may be attributed to the expression of LGI1 in the hypothalamus and the kidney. From: Lai M, Huijbers MG, Lancaster E, et al. Lancet Neurol 2010; 9(8):776-85 & Irani SR, Alexander S, Waters P, et al.Brain 2010; 133 (9): 2734-2748

Differential diagnoses – various autoantibodies The concept of anti-vgKC–complex associated encephalitis  Anti-LGI1 encephalitis  Anti-CASPR2 encephalitis (please see below)  Anti-Contactin2 encephalitis  Anti-DPPX (DPP6, Kv4.2), please see specfic section of this compendium  About 20 % are reported to be seropositive only using the classical RIA with dendrotoxin  Currently unknown other specificities of autoantibodies

Other differential diagnoses: 1. Anti-GAD65 encephalitis 2. Anti-GlyR alpha 1 encephalitis

Other differential diagnoses in cases with milder symptomatology 1. Morvan’s fibrillary chorea is a rare autoimmune synaptic encephalopathy characterized by muscle twitching (myotonia), chorea, neuropathy, salivation & perspiration - and sometimes combined with other features, such as confusional episodes with spatial and temporal disorientation, visual and auditory hallucinations, complex behaviour during sleep and progressive nocturnal insomnia associated with diurnal drowsiness. Wen left alone, the subject would slowly lapse into a stuporous state with dreamlike

episodes characterized by complex and quasi-purposeful gestures and movements (enacted dreams). Moreover, there may be severe constipation and urinary incontinence. This disorder is associated with anti-CASPR2 or anti-LGI1. 2. The milder cramp-fasciculation syndrome is neuromyotonia without fibrillations. There is also an overlap to Morvan’s syndrome. 3. Peripheral nerve hyper-excitability (acquired neuromyotonia - Isaacs' syndrome): an intermittent or continuous widespread involuntary muscle contractions and autoantibodies directed to contactin- associated protein-2 (CASPR2) - the true target and being an accessory protein and integrated at vg-KC complexes. The typical feature of this syndrome is continuous and quite pronounced muscle fibre activity, which is also present during sleep. The underlying mechanism is a severe instability of the terminal arborisations of motor nerves attributable to impaired function of the delayed rectifier K+ channels that are ordinarily responsible for neuronal repolarisation following action potential firing.

A patient's serum reacts with soluble LGI1 bound to ADAM22 or ADAM23 LGI1-containing media was applied to HEK293 cells expressing ADAM22 (first column) or ADAM23 (second column). Patient's antibodies recognised LGI1 bound to ADAM22 or ADAM23, but not HEK293 cells without either receptor (third row)

Characteristics of anti-CASPR2 (contactin-associated protein-like 2) encephalitis Anti-CASPR2 (CNTNAP2) encephalitis and or neuromyotonia 8 patients with Caspr2 autoantibodies 7 with encephalopathy or seizures 5 with neuromyotonia or peripheral nerve hyperexcitability 5 with myasthenia gravis 0 with active cancer (anyhow, look out for a thymoma) 7 responded to immunotherapy and were healthy or only mildly disabled at last follow-up (median, 8 months; range, 6–84 months). Lancaster et al. Ann Neurol 2011; 69(2): 303–311. 30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Characteristics of anti-DPPX (DPP6, a subunit of Kv4.2 potassium channels) encephalitis DPPX, DPP6 - dipeptidyl-peptidase-like protein-6

Distinguishing feature: hyperexcitability (agitation, tremor, myoclonus, seizures), diarrhoea

Genetics: 7q36.2 – please also see OMIM 126141

This gene encodes a single-pass type II membrane protein that is a member of the S9B family in clan SC of the serine proteases. This protein has no detectable protease activity, most likely due to the absence of the conserved serine residue normally present in the catalytic domain of serine proteases. However, it does bind specific voltage-gated potassium channels and alters their expression and biophysical properties. Alternate transcriptional splice variants, encoding different isoforms, have been characterized. In short: important for the regulation of the voltage-gated ion channel Kv4.2.

Encephalitis and antibodies to dipeptidyl-peptidase-like protein-6, a subunit of Kv4.2 potassium channels (n=4). Ann Neurol 2013; 73 (1): 120-128. Symptomatology Inflammatory CSF profile . Memory deficit Mild pleocytosis . Horizontal nystagmus, orofacial movements, coarse resting tremor resting tremor, hyperreflexia , exaggerated startle response, unsteady gait . Anxiety, depression, agitation, aggression, visual hallucinations, paranoid delusions, psychosis . Recurrent generalized seizures, episodes of status epilepticus, myoclonus Intrathecal immunoglobulin G synthesis . Decreased speech , mutism . Insomnia, parasomnias . Decreased level of consciousness, able to track, but not follow commands, orofacialdyskinesias. Suspected seizures . Abdominal pain, diarrhea, weight loss

. Single stranded DNA antibodies; no antibodies to dsDNA

Series of progressive encephalomyelitis with rigidity and myoclonus. A new variant with DPPX antibodies (n=3) - Neurology 2014; 82 (17): 1521-28. Symptomatology Inflammatory CSF profile . Hyperekplexia Mild pleocytosis . Prominent cerebellar ataxia with marked eye movement disorder . Trunk stiffness of variable intensity Intrathecal immunoglobulin G synthesis . Allodynia . Neurogenic pruritus . Gastrointestinal symptoms

Expression of DPPX in myenteric plexus

Transverse section of small bowel of rat showing the longitudinal muscular layer (LM), circular muscular layer (CM), submucosal layer (SM), and glans (G). The myenteric plexus (Plex) is revealed as clusters of large neurons between the two muscular layers. In the 3 panels (A–C) the nuclei of the neurons (red) was labeled with anti-Hu (a highly specific neuronal marker). Panel A, shows in green the DPPX immunostaining using a rabbit polyclonal antibody (1:1000, developed by BD) Panel B shows the DPPX reactivity of serum from one of the patients with encephalitis, Panel C shows the lack of reactivity of serum from a healthy subject. Note that DPPX is predominantly expressed in the cytoplasm-membrane of the large clustered neurons of the myenteric plexus, and is also detected in a fine longitudinal pattern in CM and SM where the submucosal plexus is located. Bar = 20μm. Ann Neurol 2013; 73 (1): 120-128.

Selected references 1. Buckley C, Oger J, Clover L, Tüzün E, Carpenter K, Jackson M, Vincent A. Potassium channel antibodies in two patients with reversible limbic encephalitis. Annals of Neurology 2001; 50 (1): 73–78. 2. Kin Y, Misumi Y, Ikehara Y. Biosynthesis and characterization of the brain-specific membrane protein DPPX, a dipeptidyl peptidase IV-related protein. J Biochem 2001; 129 (2): 289-295. 3. Nadal MS, Ozaita A, Amarillo Y, Vega-Saenz de Miera E, Ma Y, Mo W, Goldberg EM, MisumiY, Ikehara Y, Neubert TA, Rudy B. The CD26-related dipeptidyl aminopeptidase-like protein DPPX is a critical component of neuronal A- type K+ channels. Neuron 2003; 37 (3): 449-461. 4. Vincent A, Buckley C, Schott JM, Baker I, Dewar B-K, Detert N, Clover L, Parkinson A, Bien CG, Omer S, Lang B, Rossor MN, Palace J. Potassium channel antibody-associated encephalopathy: a potentially immunotherapyresponsive form of limbic encephalitis. Brain 2004: 127: 701-12. 5. Strop P, Bankovich AJ, Hansen KC, Garcia KC, Brunger AT. Structure of a human A-type potassium channel interacting protein DPPX, a member of the dipeptidyl aminopeptidase family. J Mol Biol 2005; 343 (4): 1055- 1065. 6. Radicke S, Cotella D, Graf EM, Ravens U, Wettwer E. Expression and function of dipeptidyl-aminopeptidase-like protein 6 as a putative beta-subunit of human cardiac transient outward current encoded by Kv4.3. J Physiol 2005; 565 (Pt 3): 751-756 7. Nadal MS, Amarillo Y, Vega-Saenz de Miera E, Rudy B. Differential characterization of three alternative spliced isoforms of DPPX. Brain Res 2006; 1094 (1): 1-12. 8. Colinas O , Pérez-Carretero FD , López-López JR , Pérez-García MT. A role for DPPX modulating external TEA sensitivity of Kv4 channels. J Gen Physiol 2008; 131 (5): 455-471. 30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

9. Kim J, Nadal MS, Clemens AM, Baron M, Jung SC, Misumi Y, Rudy B, Hoffman DA. Kv4 accessory protein DPPX (DPP6) is a critical regulator of membrane excitability in hippocampal CA1 pyramidal neurons. J Neurophysiol 2008; 100 (4): 1835-1847. 10. Seikel E, Trimmer JS. Convergent modulation of Kv4.2 channel alpha subunits by structurally distinct DPPX and KChIP auxiliary subunits. Biochemistry 2009; 48 (24): 5721- 5730. 11. Lai M, Huijbers MGM, Lancaster E, Graus F, Bataller L, Balice-Gordon R, Cowell JK, Dalmau J. Investigation of LGI1 as the antigen in limbic encephalitis previously attributed to potassium channels: a case series. The Lancet Neurology 2010; 9 (8): 776 – 785 12. Irani SR, Alexander S, Waters P, Kleopa KA, Pettingill P, Zuliani L, Peles E, Buckley C, Lang B, Vincent A. Antibodies to Kv1 potassium channel-complex proteins leucine-rich, glioma inactivated 1 protein and contactin-associated protein-2 in limbic encephalitis, Morvan’s syndrome and acquired neuromyotonia. Brain 2010; 133 (9): 2734– 2748. 13. Lancaster E, Huijbers MGM, Bar V, Boronat A, Wong A, Martinez-Hernandez E, Wilson C, Jacobs D, Lai M, Walker RW, Graus F, Bataller L, Illa I, Markx S, Strauss KA, Peles E, Scherer SS, Dalmau J. Investigations of Caspr2, an autoantigen of encephalitis and neuromyotonia. Ann Neurol 2011; 69(2): 303–311. 14. Ohkawa T, Fukata Y, Yamasaki M, Miyazaki T, Yokoi N, Takashima H, Watanabe M, Watanabe O, Fukata M. Autoantibodies to epilepsy-related LGI1 in limbic encephalitis neutralize LGI1-ADAM22 interaction and reduce synaptic AMPA receptors. J Neurosci 2013; 33 (46): 18161-74. 15. Dalmau J, Rosenfeld MR. Autoimmune encephalitis update. Neuro Oncol 2014: 16 (6): 771-78. 16. Boronat A, Gelfand JM, Gresa-Arribas N, Jeong HY, Walsh M, Roberts K, Martinez-Hernandez E, Rosenfeld MR, Balice-Gordon R, Graus F, Rudy B, Dalmau J. Encephalitis and antibodies to dipeptidyl-peptidase-like protein-6, a subunit of Kv4.2 potassium channels. Ann Neurol 2013; 73 (1): 120-128. 17. Balint B, Jarius S, Nagel S, Haberkorn U, Probst C, Blöcker IM, Bahtz R, Komorowski L, Stöcker W, Kastrup A, Kuthe M, Meinck H-M. Progressive encephalomyelitis with rigidity and myoclonus. A new variant with DPPX antibodies. Neurology 2014; 82 (17): 1521-28. 18. Dalmau J, Rosenfeld MR. Autoimmune encephalitis update. Neuro Oncol 2014: 16 (6): 771-78.

Characteristics of anti-GABABR1 - gamma-aminobutyric acid type B receptor subunit 1 - encephalitis GABA-receptors are probably the most common kind in the mammalian nervous system. It is estimated that close to 40% of the synapses in the human brainwork with GABA and therefore have GABA-receptors.

Distinguishing features: gustatory and/or visual hallucinations, orolingual movements, fluent aphasia, total insomnia (agrypnia) Clinical features, CSF, and MRI findings (patients n = 15, 7 females (47 %); 8 males; age range:24 – 75 years) From: Lancaster E, Lai M, Peng X, et al. Antibodies to the GABAB receptor in limbic encephalitis with seizures: case series and characterisation of the antigen. Lancet Neurol 2010; 9: 67-76. Associated neoplasms: SCLC, mediastinal adenopathy, neuroendocrine tumour of the lung, benign ovarian mass No neoplasm: 47% (five of these patients were young (median age 30 years, range 24–45), were non-smokers, and had negative cancer screening including CT/fluorodeoxyglucose-PET, and two of these patients had long-term follow-up (41 and 72 months), making the presence of cancer unlikely) Findings of additional antibodies: anti-VGCC (N-type), anti-GAD, AGNA (anti-SOX1, lung cancer), anti-TPO Symptom presentation Cerebrospinal fluid Brain MRI (FLAIR) increased signal (typically, subacute onset of Not available: 33 % Anti-GABABR Normal: 27 % (n=4) various combinations) Abnormal: 90 %  Memory impairment 6 – 95  Behavioural problems WBC (95 %)  Confusion, disorientation, (normal <4/μl ) confabulation, agitation  Paranoia, gustatory and/or visual hallucinations, psychosis Left medial temporal lobe Elevated  Sleeping disorder (agrypnia) [see protein Seropositive: 75 % 90 % also ref. 1] (normal 16-46 Left medial temporal lobe and  Abnormal orolingual movements, mg/dl) insula Else positive CSF fluent aphasia antibody titre

 Epilepsy: complex partial seizures, Medial temporal lobes

partial motor and generalised, generalised tonic-clonic seizures, Small area of corpus callosum status epilepticus Oligoclonal  Requiring intubation and > 45 % bands ventilation  Decline in mental status leading to coma Clinical features, CSF, and MRI findings (patients n = 11, 2 females; 9 males (65 %); age range: 47 – 70 year) From: Boronat A, Sabater L, Saiz A, Dalmau J, Graus F. GABAB receptor antibodies in limbic encephalitis and anti-GAD– associated neurologic disorders. Neurology 2011; 76: 795-800 Associated neoplasms: SCLC, carcinoid of thymus - No neoplasm: 18% Findings of additional antibodies: anti-VGCC, anti-GAD, AGNA (anti-SOX1, lung cancer), anti-BRSK2 Symptom Pleocytosis in Brain MRI (FLAIR) Normal: 36 % (n=4) Anti-GABABR cerebrospinal fluid antibody positive At presentation Overall Not available: 1 (9 %) Temporal lesions

Seizures 82 % Seropositive: 100 % Not present n= 6 (60%) Memory impairment 55 % LE 91% Bilateral: n= 5 (45 %)

Changed behaviour 36 % CA 9% # CSF-positive: only 5 Present: n= 4 (40 %) Epilepsy 82 % samples available (6 Confusion 36 % Left side: n= 2 (18 %) Ataxia 9 % missing) 100 % LE = limbic encephalitis; CA = cerebellar ataxia # The patient with cerebellar ataxia was also anti-GAD seropositive 30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Treatment . Immunotherapy: steroids, plasmapheresis, intravenous high-dose IgG, mycophenylate mofetil, or related drugs . Oncologic (paraneoplastic type)

MRI of a patient with GABAB receptor antibodies and limbic encephalitis

Axial fluid-attenuated inversion recovery (FLAIR) MRI from patient 1 at presentation (A) showed increased signal in the medial temporal lobes, which was more pronounced on the left.

Repeat study at 1 month (B) showed improvement of the FLAIR signal that remained stable at 3 months and 9 months (C, D), with development of mild generalised atrophy (the patient received standard whole-brain radiation therapy as prophylaxis for small-cell lung cancer metastases).

Detection of antibodies to the GABAB1 subunit using a HEK293 cell-based assay

HEK293 cells transfected with the GABAB1 receptor subunit show reactivity with CSF from a patient with limbic encephalitis (A) and a polyclonal antibody against the B1 subunit of the GABAB receptor (B); both reactivities are merged in C. Similarly transfected cells do not react with CSF from a control individual (D) but do show reactivity with a polyclonal antibody against the B1 subunit of the GABAB receptor (E); reactivities merged in F. Immunofluorescent method.

Culture of rat hippocampal neurons incubated (live, non-permeabilised) with CSF of a patient with anti-GABABR and limbic encephalitis versus a control individual Note the intense punctate reactivity of patient's antibodies with cell surface antigens (A) and the absence of reactivity in the control (B); nuclei of neurons stained with 4',6-diamidino-2-phenylindole (DAPI).

The surface antigens were precipitated using the antibodies within the patient's serum, and then electrophoretically separated and visualised with EZBlue (C).

Patient's antibodies (P) precipitated two main protein bands at about 105 kDa and 90 kDa; these bands are not seen in the precipitate using serum from a control individual (N).

Sequencing of the 105 kDa band by use of mass spectrometry showed it contained the B1 and B2 subunits of the GABAB receptor. The 90 kDa and other smaller bands were proteolytic fragments and patient's IgG products. Subsequent transfer of the gel to nitrocellulose and immunoblotting with antibodies specific for each of the GABAB (D) subunits confirmed that patient's antibodies precipitated the B1 and B2 subunits (105 kDa) and that the 90 kDa band was a proteolytic fragment of B1. From: Lancaster E, Lai M, Peng X, et al. Antibodies to the GABAB receptor in limbic encephalitis with seizures: case series and characterisation of the antigen. Lancet Neurol 2010; 9: 67-76.

Selected references 1. Frisullo G, Marca GD, Mirabella M, et al. A human anti-neuronal autoantibody against GABAB receptor induces experimental autoimmune agrypnia. Experimental Neurology 2007; 204 (2): 808-18. 2. Lancaster E, Lai M. Antibodies to the GABAB receptor in limbic encephalitis with seizures: case series and characterisation of the antigen. Lancet Neurol 2010; 9: 67-76 3. Boronat A, Sabater L, Saiz A, Dalmau J, Graus F. GABAB receptor antibodies in limbic encephalitis and anti-GAD– associated neurologic disorders. Neurology 2010; 9 (1): 67–76. 4. Kim T-J, Lee S-T, Shin J-W, et al. Clinical manifestations and outcomes of the treatment of patients with GABAB encephalitis. J Neuroimmunol 2014; 270 (1): 45-50.

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Characteristics of anti-GABAAR - α1/β3 subunits - encephalitis

Gamma-aminobutyric acid type A receptor subunits α1/β3

Distinguishing features: epilepsy, status epilepticus, epilepsia partialis continua Similar to anti-GABABR1 encephalitis

Clinical features, MRI findings High titres: (patients n = 6; age range: 3 – 63 year, median 22 years) The Lancet Neurology 2014; 13 (3): 276 - 286 Low titres: (patients n = 12; age range: 7 – 74 year, median 27 years) The Lancet Neurology 2014; 13 (3): 276 - 286 High tires cases: MRI Extensive cortical-subcortical abnormalities Low titre cases and 42 % of them o Seizures (n=6) also anti-GAD-65 – broader  Status epilepticus needing pharmacologically induced coma (n=1) spectrum of symptoms  Epilepsia partialis continua n=1) o Stiff-person syndrome (one with seizures and limbic involvement) (n=4) o Opsoclonus-myoclonus (n=2)

Selected references 1. Petit-Pedrol M, Armangue T, Peng X, Bataller L, Cellucci T, Davis R, McCracken L, Martinez-Hernandez E, Mason WP, Kruer MC, Ritaccoi DG, Grisold W, Meaney BF, Alcalá C, Sillevis-Smith P, Titulaer MJ, Balice-Gordonc RB, Graus F, Dalmau J. Encephalitis with refractory seizures, status epilepticus, and antibodies to the GABAA receptor: a case series, characterisation of the antigen, and analysis of the effects of antibodies. The Lancet Neurology 2014; 13 (3): 276 - 286 2. Dalmau J, Rosenfeld MR. Autoimmune encephalitis update. Neuro Oncol 2014: 16 (6): 771-78.

Characteristics of anti-mGluR1 and of anti-HOMER3 encephalitis (cerebellitis) Distinguishing feature: ataxia (truncal and gait), intention tremor

Onset and course: sub acute cerebellar ataxia

Cerebellar degeneration associated with various autoantibodies Diffential diagnoses

Antibodies predominantly associated with Predominant syndrome Associated cancer paraneoplastic cerecellar degeneratikon (PCD)

Breast, small-cell lung (SCLC), Anti-Yo (PCA-1) antibodies PCD ovarian, prostatic

PCD (+occasionally: limbic encephalitis, Anti-Tr antibodies Hodgkin's lymphoma optic neuritis)

Anti-mGluR1 antibodies PCD Hodgkin's lymphoma, ovarian

Anti-ZIC4 antibodies PCD SCLC , lung adenocarcinoma

Anti-HOMER3 antibodies Ataxia, headache, nausea, confusion None

Sometimes associated with PCD Ataxia and other findings

PCD, encephalomyelitis, sensory SCLC, lung adenocarcinoma, Anti-Hu (ANNA-1) antibodies neuronopathy other cancers

PCD, brain-stem encephalitis, Anti-Ri (ANNA-2) antibodies Breast, SCLC, gynaecologic paraneoplastic opsoclonus-myoclonus

PCD, encephalomyelitis, chorea, Anti-CV2/CRMP5 antibodies SCLC, thymoma, other cancers peripheral neuropathy, uveitis

Anti-PCA2 PCD, encephalomyelitis SCLC

Limbic, hypothalamic, brain-stem Breast, lung adenocarcinoma, Anti-Ma1 protein antibodies encephalitis, infrequently PCD testis, other cancers

PCD, stiff-person syndrome, Anti-Amphiphysin antibodies Breast, SCLC encephalomyelitis

Anti-VGCC antibodies Eaton-Lambert syndrome, PCD SCLC, lymphoma

Homer proteins are a family of scaffolding proteins of the postsynaptic density. Homer-3 colocalizes and modulates the activity of group I metabotropic glutamate receptors (mGluR1 and mGluR5).

Selected references 1. Marignier R, Chenevier F, Rogemond V, Sillevis Smitt P, Renoux C, Cavillon G, Androdias G, Vukusic S, Graus F, Honnorat J, Confavreux C. Metabotropic glutamate receptor type 1 autoantibody-associated cerebellitis: a primary autoimmune disease? Arch Neurol 2010; 67 (5): 627-30. 2. Höftberger R, Sabater L, Ortega A, Dalmau J, Graus F. Patient with homer-3 antibodies and cerebellitis. JAMA Neurol 2013; 70 (4): 506-9.

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Characteristics of anti-mGluR5 encephalitis (Ophelia syndrome) Distinguishing feature: Ophelia syndrome, Hodgkin’s disease

In short, the “Ophelia Syndrome” is classified as one person being too dependent on another, while the other person simply tells them what to do. In some ways, it sounds a lot like co-dependency: a vicious cycle that two people are sucked into, only then discovering how hard it is to break free.

Other features CSF with pleiocytosis and MRI with T2/FLAIR hyper intensities (medial temporal lobe or also parietal and occipital regions)

Definition of the Ophelia syndrome A health disorder where - if you are reciving abuse - you cant help to forgive that person for what he or she has done. A relationship in which one person is too dependent on another and the other person tells them what to do. The other term for this word is co-dependency.

The solution to the “Ophelia Syndrome” is not easily found. Teachers can try to make students think on their own by showing them two ends of a puzzle and not letting them know the missing link. Nevertheless, many people will not know what to do; they will simply flounder in confusion until someone tells them the way to go. Therefore, in the end, the difference is in us, individually. We must decide we no longer desire to be spoon-fed. This desire, implemented in every person, is the greatest permanent cure to the “Ophelia Syndrome.”

Selected references: 1. Lancaster E, Martinez-Hernandez E, Titulaer MJ, Boulos M, Weaver S, Antoine JC, Liebers E, Kornblum C, Bien CG, Honnorat J, Wong S, Xu J, Contractor A, Balice-Gordon R, Dalmau J. Antibodies to metabotropic glutamate receptor 5 in the Ophelia syndrome. Neurology 2011; 77 (18): 1698-701. 2. Mat A, Adler H, MerwickA, Chadwick G, Gullo G, Dalmau JO, Tubridy N. Ophelia syndrome with metabotropic glutamate receptor 5 antibodies in CSF. Neurology, 2013; 80(14): 1349–1350. 3. Carr I. The Ophelia syndrome: memory loss in Hodgkin's disease. Lancet 1982; 1 (8276): 844-5.

Characteristics of anti-IgLON5 - cell adhesion molecule IgLON5 - encephalitis

Distinguishing features: prominent sleep dysfunction

IGLON5 IgLON family member 5 [ Homo sapiens (human): Gene location 19q13.41

IgLON proteins are GPI anchored adhesion molecules that control neurite outgrowth. In particular, Negr1 down-regulation negatively influences neuronal arborisation in vitro and in vivo.

IgLON5 belongs to the immunoglobulin superfamily and contains three Ig-like C2-type (immunoglobulin-like) domains. The IgLON family of cell adhesion molecules, comprising OPCML, HNT, LSAMP, and NEGR1, has recently been linked to cancer, through two of its members being proposed as tumor suppressors. OPCML, LSAMP and NEGR1 exhibited reduced expression in the tumor samples relative to the normal samples, whereas HNT expression was elevated.

Statistically significant changes is reported to be specific to histologic type. The expression levels of individual IgLONs appears to be correlated, the most significant finding being a positive correlation between LSAMP and NEGR1. LSAMP expression is reported to be negatively correlated with overall survival and was found to be a negative predictor of outcome.

Features of anti-IgLON5 encephalitis High titres: (patients n = 8; age range: 52 – 76 year, median 59 years) Lancet Neurol 2014; 13 (6): 575-86 Sleep disorder – and often the initial and most prominent feature (n=4) o Video polysomnography (n=5): all showed features of obstructive sleep apnoea, stridor, and abnormal sleep architecture. The pattern of sleep starts out as undifferentiated and with non-REM cycles, and may become more normal at the end of the night Gait instability followed by dysarthria, dysphagia, ataxia, or chorea (n=2) Rapid progression with disequilibrium, dysarthria, dysphagia, and central hypoventilation (n=2) Chronic progression (n=6), frequently a fatal disorder due to respiratory failure. Neuropathology (n=2) showed neuronal loss and extensive deposits of hyperphosphorylated tau mainly involving the tegmentum of the brainstem and hypothalamus

Differential diagnosis: autoimmune agrypnia with anti-GABABR1

Selected references 1. Sabater L, Gaig C, Gelpi E, Bataller L, Lewerenz J, Torres-Vega E, Contreras A, Giometto B, Compta Y, Embid C, Vilaseca I, Iranzo A, Santamaría J, Dalmau J, Graus F. A novel non-rapid-eye movement and rapid-eye-movement parasomnia with sleep breathing disorder associated with antibodies to IgLON5: a case series, characterisation of the antigen, and post-mortem study. Lancet Neurol 2014; 13 (6): 575-86 2. Gaig C, Sabater L, Gelpi E, Luis Bataller, Lewerenz J, Torres-Vega E, Contreras A, Giometto B, Compta Y, Embid C, Vilaseca I, Iranzo A, Santamaria J, Dalmau J, Graus F. Antibodies Against The Cell Adhesion Molecule IgLON5 Identify A Novel Tauopathy With NREM/REM Parasomnia And Sleep Breathing Disorder. Neurology 2014; 82 (10): supplement S9.005

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Stiff-person spectrum of symptoms (SPS) Characteristics of anti-Glutamate decarboxylase 2 (anti-GAD65) encephalitis – a spectrum of disorders Expression of GAD: GAD65 presynaptic; GAD67 intracellular

There is an expression of both GAD65 In mammals, glutamate decarboxylase (GAD) exists in two isoforms and GAD67 in the brain. GAD65 is also encoded by two different genes a feature of pancreas. Gene Molecular weight Expression Exclusively, GAD67 is an enzyme of Gad-I (GAD67, Gene card 2q31) 67 CNS neurons. Gad-II (GAD65, Gene card 10p11.23) 65 CNS, pancreas The amino acid sequence of both is with about 65 % homology (primarily in middle and C-terminal regions). The central region, which contains the decarboxylase catalytic domain, appears to be highly immunoreactive.

GAD65 and GAD67 synthesize GABA at different locations in the cell, at different developmental times, and for functionally different purposes. GAD67 is spread evenly throughout the cell while GAD65 is localized to nerve terminals. This difference is thought to reflect a functional difference; GAD67 synthesizes GABA for neuron activity unrelated to neurotransmission, such as synaptogenesis and protection from neural injury. This function requires widespread, ubiquitous presence of GABA. GAD65, however, synthesizes GABA for neurotransmission, and therefore is only necessary at nerve terminals and synapses.

Synthesis from gamma-amino butter acid and degradation of GABA

The role of γ-aminobutyric acid (GABA) and GABA receptors  It is the major inhibitory neurotransmitter in the mammalian CNS, and mediates its effects through different classes of receptor termed GABAA, GABAB and GABAC  It plays a role in regulating neuronal excitability throughout the nervous system  In humans, GABA is also directly responsible for the regulation of muscle tone  GABA is classified as an inhibitory neurotransmitter, as opposed to excitatory neurotransmitters, such as glutamate, which augment the nerve impulses in the neuron

 GABA-receptors mainly allow negatively charged chloride neurons to enter the neuron, thus reducing its excitability

Anti-Glutamate decarboxylase 2 (GAD65) is associated with  Encephalomyelitis or limbic encephalitis with or without associated neoplasm  Refractory seizures  Paraneoplastic cerebellar ataxia (PCD)  Stiff person syndrome (SPS) and variants  SPS including variants such as progressive encephalomyelitis with rigidity and myoclonus (PERM)  Kleine-Levin syndrome - (J Neuropsychiat Clin Neurosci 2014; 26: E49-E51.  Differential diagnoses: anti-GlyR alpha1 encephalitis and anti-DPPX encephalitis (please see elsewhere). Do also consider anti-Gephyrin-, anti-Amphiphysin1-associated encephalitis  Anti-GAD is also associated with diabetes mellitus, although with much lower titres and probably binding to different autoantigens than those of anti-GAD encephalitis

A finding of anti-GAD is sometimes associated with one of the following neoplasms: SCLC, breast, thymoma, pancreas, multiple myelomas, colon (rectum), and renal cell carcinoma.

It appears that there are close links between autoimmunity directed against components of inhibitory synapses and neurological conditions characterized by chronic rigidity and spasms.  Anti-Glycine receptor may be a feature of some cases with PERM [Neurology 2008; 71: 1291-1292], please see below  SPS is also associated also with autoantibodies to GABAA-receptor-associated protein (anti-GABARAP) (Brain 2006; 129 (Pt 12): 3270-6.)  Moreover, high-titer autoantibodies directed against gephyrin may be a feature [Neuron. 2000 May; 26(2): 307-12]  Some of these patients are also anti-GABABR1-seropositive (please see anti-GABABR1 encephalitis)

Clinical features, CSF, treatment and outcome of anti-GAD limbic encephalis (LE) with epilepsy: patients n = 9 From: Malter MP, Helmstaedter C, Urbach H, et al. Antibodies to glutamic acid decarboxylase define a form of limbic encephalitis. Ann Neurol. 2010; 67(4): 470-8 Compared to non anti-GAD seropositive LE, these patients were younger: median age 23 years, range: 17 – 66 years None had tumours Features Cerebrospinal fluid Therapy, course (CSF) High-titer GAD antibodies define a . Following monthly intravenous form of non-paraneoplastic LE methylprednisolone pulses, GAD antibodies  Appears to be a chronic, non- Frequent features remained highly elevated in all patients remitting disorder o oligoclonal bands . Despite more intense anticonvulsive  Should be included in the o intrathecal treatment, none of these patients became differential diagnosis of secretion of anti- seizure free patients with temporal lobe GAD . Therapeutic trials of other epilepsy and mediotemporal immunotherapies should be encephalitis undertaken

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Clinical features of anti-GAD limbic encephalitis  This disorder may be gradually and slowly developing and with uncharacteristic cognitive symptoms – suggesting a psychosomatic nature. Unfortunately, cases may not be properly diagnosed until onset of epilepsy.  On the other hand, the disorder may be an encephalomyelitis with a more rapidly progressing symptomatology including fluctuating disorientation, delusions, and memory deficits. Respiratory failure may occur  Intrathecal synthesis of anti-GAD is a significant feature, so always include both serum and cerebrospinal fluid in the examinations [Neurology 2001; 57: 780-784]

Short summary  The targets of anti-GAD are located at GAD65 of GABA-ergic nerve terminals, which co-localizes with Amphiphysin and CV2 (CRMP5), or at GAD67 of evenly dispersed intracellular enzyme sites  GAD65 and Amphiphysin are non-intrinsic membrane proteins that are concentrated in nerve terminals, where a pool of both proteins is associated with the cytoplasmic surface of synaptic vesicles  GAD 65 and Amphiphysin are the only two known targets of CNS autoimmunity with this distribution  The central region of GAD65 containing the decarboxylase catalytic domain is reported to be highly immunoreactive [Biochem Biophys Res Commun 2008; 366 (1): 1–7.]  Anti-GAD from neurological patients is reported to recognize epitopes that are different from those related to type 1 DM o In an animal model using rats [Orphanet J Rare Dis. 2011; 6: 3], it has been reported that intra- cerebellar administration of anti-GAD65 from a stiff-person syndrome patient impaired the NMDA-mediated turnover of glutamate, but had no effect on NMDA-mediated turnover of glycerol. By contrast, anti-GAD65 from a patient with cerebellar ataxia markedly decreased the NMDA-mediated turnover of glycerol. Both of these GAD65 autoantibodies increased the excitability of the spinal cord, as assessed by the F wave/M wave ratios o In type1 diabetes, it appears that a minor fraction anti-GAD65 sera are reactive with a cross- reactive epitope found also on GAD67 [PLoS One. 2011 Apr 8; 6 (4): e18411]. o Upon incubation of nerve cells with anti-GAD serum or cerebrospinal fluid (CSF) from paraneoplastic patients, there is inhibition of the synthesis of GABA, and even in a dose- dependent manner, whereas this does not happen with serum or CSF from diabetics

 In the paraneoplastic syndromes, the anti-GAD titre is much higher than that in diabetes mellitus (DM)

Anti-GAD seropositive patient with epilepsy and cerebellar ataxia Indirect immunofluorescence using anti-GAD patient serum and primate cerebellar granular cells Indirect immunofluorescence was carried out using the patient's serum diluted to 1:10. The serum reacted positively up to a dilution of 1:8000.

(bars measure 20 μm)

(A) Cytoplasmic reactivity

(B) Anti‐nuclear fluorescence was obtained with a reference anti‐Hu serum (titre 1/320), diluted to 1:20. This shows the different reactivity of the patient's serum compared with anti‐Hu autoantibodies.

(C) Immunoblot confirming the glutamic acid decarboxylase (GAD) reactivity. From left to right: control reaction, GAD67, GAD65, cut‐off. Positivity is indicated by intensities of blue (appearing as dark rose).

The test is clearly positive for GAD65, but only weakly positive for GAD67 (reproduced by the permission of Professor J Honnorat).

Selected references 1. Burn DJ, Ball J, Lees AJ, Behan PO, Morgan-Hughes JA. A case of progressive encephalomyelitis with rigidity and positive antiglutamic acid decarboxylase antibodies [corrected]. J Neurol Neurosurg Psychiatry 1991; 54 (5): 449–451. 2. Dalakas MC, Fujii M, Li M, Jacobowitz D. Stiff person syndrome. Quantification, specificity and intrathecal synthesis of GAD65 antibodies. Neurology 2001; 57: 780-784 3. McHugh JC, Murray B, Renganathan R, Connolly S, Lynch T. GAD Antibody Positive Paraneoplastic Stiff Person Syndrome in a Patient with Renal Cell Carcinoma. Movement Disorders 2007; 22 (9): 1343-1346. 4. Hutchinson M, Waters P, McHugh J, Gorman G, O’Riordan S, Connolly S, Hager H, Yu C, Becker CM, Vincent A. Progressive Encephalomyelitis, rigidity, and myoclonus: a novel glycine receptor antibody. Neurology 2008; 71: 1291-1292. 5. Burbelo PD, Sandra Groot S, Dalakas MC, Iadarola MJ. High Definition Profiling of Autoantibodies to Glutamic Acid Decarboxylases GAD65/GAD67 in Stiff-Person Syndrome. Biochem Biophys Res Commun 2008; 366 (1): 1–7. 6. Malter MP, Helmstaedter C, Urbach H, et al. Antibodies to glutamic acid decarboxylase define a form of limbic encephalitis. Ann Neurol. 2010; 67(4): 470-8 7. Boronat A, Sabater L, Saiz A, Dalmau J, Graus F. GABAB receptor antibodies in limbic encephalitis and anti-GAD–associated neurologic disorders. Neurology 2011; 76: 795-800. 8. Manto MU, Hampe CS, Rogemond V, Honnorat J. Respective implications of glutamate decarboxylase antibodies in stiff person syndrome and cerebellar ataxia. Orphanet J Rare Dis 2011; 6: 3. 9. Damásio J, Leite I, Coutinho E, Waters P, Woodhall M, Santos MA, Carrilho I, Vincent A. Progressive Encephalomyelitis With Rigidity and Myoclonus. The First Pediatric Case With Glycine Receptor Antibodies. JAMA Neurol 2013; 70 (4): 498-501 10. Balint B, Jarius S, Nagel S, Haberkorn U, Probst C, Blöcker IM, Bahtz R, Komorowski L, Stöcker W, Kastrup A, Kuthe M, Meinck H-M. Progressive encephalomyelitis with rigidity and myoclonus. A new variant with DPPX antibodies. Neurology 2014; 82 (17): 1521-28. 11. Ujjwal K. Rout UK, Michener MS, Dirk M. Dhossche DM. GAD65 Autoantibodies in Kleine-Levin Syndrome. J Neuropsychiat Clin Neurosci 2014; 26: E49-E51 12. Widman G, Golombeck K, Hautzel H, er al. Treating a GAD65 Antibody-Associated Limbic Encephalitis with Basiliximab: A Case Study. Front Neurol 2015; 6: 167.

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Characteristics of anti-GlyR-alpha1 encephalomyelitis – a spectrum of disorders

Glycine receptor Glycine receptors (GlyR) The GlyR is the receptor for the amino acid neurotransmitter glycine. It is among the most widely distributed inhibitory receptors in the central nervous system. GlyRs are primarily expressed in spinal cord, brain stem, caudal brain, and retina. In adult neurons, the inhibitory chloride influx upon glycine receptor activation stabilizes the resting potential of the cell, rendering them electrically quiescent. High local concentrations of glycine receptors (GlyRs) at inhibitory postsynaptic sites are achieved through their binding to the scaffold protein gephyrin. Anti-GlyR1 appears to be a finding in about 10 % of SPS spectrum of symptoms (with or without anti-GAD). Testing: Cell based assay (CBA) with HEK cells expressing the alpha 1 subunit of the glycine receptor. The CBA must be on living transfected cells, or else the result may be false negative. Extracting such cells in Triton-X100, an immunoprecipitation assay is also an option.

Glycine receptors grouped by specificity Subunit Gene Chromosome Genetic disorders Acquired autoimmune disorders o Autosomal dominant hyperekplexia, o Atypical stiff-person or stiff-limb o Autosomal recessive hyperekplexia syndrome (without or with anti- o 5q32 Hyperekplexia and spastic paraparesis GAD) α1 GLRA1 o Congenital stiff-man syndrome o Progressive encephalomyelitis o Limbic encephalitis with rigidity and myoclonus Alpha (PERM) o Autoimmune hyperekplexia α2 GLRA2 Xp22.1-p21.3 o Rett syndrome α3 GLRA3 4q33-q34 α4 GLRA4 Xq22.2 Beta β GLRB 4q31.3 o Autosomal recessive hyperekplexia

Anti-GlyR encephalitis – a spectrum of disorders Stiff-person syndrome Progressive encephalopathy with rigidity and reflex myoclonus (PERM) Limbic encephalitis Cerebellar degeneration Optic neuritis

Clinical features of 18 anti-GlyR sporadic cases, studied so far: n (%) First presentation At max severity Spasms / Stiffness / Rigidity (neck, trunk or limb muscles) 9 (50) 16 (89) Excessive startle (spontaneous or triggered by noise or touch) 4 (22) 14 (78) Limb or gait cerebellar ataxia 0 5 (28) Limb paresis / Pyramidal signs 6 (33) 13 (72) Walking difficulties / falls (mostly related to stiffness / rigidity / spams) 6 (33) Sensory symptoms/Pain 5 (28) 12 (67) Oculomotor disturbance: nerve or gaze palsy (eyelid ptosis, diplopia, 6 (33) 9 (50) nystagmus, slow / jerky movements) Trigeminal, facial and bulbar motor disturbance (dysphagia, dysarthria, 6 (33) 11 (61) difficulty chewing, facial numbness, trismus) Cognitive impairment /encephalopathy /seizures /sleep disorders 4 (22) 9 (50) Autonomic disturbances (hyper / hypohidrosis, dry mouth, brady- or tachycardia, hypo / hyper blood pressure, bladder, bowel or sexual 2 (11) 9 (50) dysfunction) Respiratory failure (admission in ICU / ventilation) 0 6 (33) Sudden death 0 3 (17) Epidemiology Gender 5 F; 13 M Median age at onset (years) 51 (28-72) Cerebrospinal fluid Pleocytosis (5 - 45 lymph) 6/14 (43 %) Elevated protein (>1g/L) 2/14 (14 %) Oligoclonal banding (OCB) or elevated IgG 4/13 (21 %) Any abnormality 8/14 (57 %) MRI Brain: only with small vessel disease 2/17 (12 %) Spinal cord: with short inflammatory lesions 2/11 (18 %) Course of disease Monophasic 3/12 (25 %) Recurrent/relapsing 7/12 (58 %) Chronic progressive 2/12 (17 %) Follow-up too short or unknown 6/18 (33 %) Past medical history Tumours 1 lymphoma, 2 thymoma Consider supplemental analyses: anti-GAD, anti-Gephyrin, anti-Amphiphysin1

Selected references 1. Mas N, Saiz A, Leite MI, Waters P, Baron M, Castaño D, Sabater L, Vincent A, Graus F. Antiglycine-receptor encephalomyelitis with rigidity. J Neurol Neurosurg Psychiatry 2011; 82 (12): 1399-401 2. Stern WM, Howard R, Chalmers RM, Woodhall MR, Waters P, Vincent A, Wickremaratchi MM. Glycine receptor antibody mediated Progressive Encephalomyelitis with Rigidity and Myoclonus (PERM): a rare but treatable neurological syndrome. Pract Neurol doi:10.1136/practneurol-2013-000511 3. McKeon A, Martinez-Hernandez E, Lancaster E, Matsumoto JY, Harvey RJ, McEvoy KM, Pittock SJ, Lennon VA, Dalmau J. Glycine receptor autoimmune spectrum with stiff-man syndrome phenotype. JAMA Neurol. 2013; 70 (1): 44-50. 4. Alexopoulos H, Akrivou S, Dalakas M. Search for Anti-Glycine Receptor Antibodies in Stiff-Person Syndrome (SPS) (P03.057). Neurology February 12, 2013; 80 (Meeting Abstracts 1): P03.057 5. Damásio J, Leite I, Coutinho E, Waters P, Woodhall M, Santos MA, Carrilho I, Vincent A. Progressive Encephalomyelitis With Rigidity and Myoclonus.The First Pediatric Case With Glycine Receptor Antibodies. JAMA Neurol 2013; 70 (4): 498-501.

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Characteristics of neuromyelitis optica spectrum of disorders

Schematic depiction of water movement through the Aqp4 narrow selectivity filter of the aquaporin channel  Gene: 18q11.2-q12.1 Water passes through each pore in a single file.  Two isotypes: Estimated high water permeability: 109 o M1 (mw 34 kDa) molecules/subunit/sec

o M23 (mw 30 kDa)  A member of the aquaporin family of intrinsic membrane proteins that function as water- selective channels in the plasma membranes of many cells  The encoded AQP4 protein is the predominant aquaporin found in brain  Anti-AQP4 is diagnostic for NMO (NMO = neuromyelitis optica)

Aquaporin4 (AQP4), general aspects Tissue expression  In the CNS, AQP4-channels are wide-spread and partly co-localise with laminin  They are expressed in astrocyte foot processes at the blood-brain barrier  They are anchored at the perivascular and subpial membranes by their C terminus to alpha-syntrophin  These channels outline CNS micro vessels, pia, subpia, and Virchow-Robin space Immunofluorescence micrographs of mouse cortex probed with primary antibodies against AQP4 (green) and GFAP (red) with DAPI-labeled nuclei (blue) for orientation.

The AQP4 immunofluorescence signal is absent in Aqp4−/− mice (right panel). (Scale bar: 25 μm)

Insets display perivascular AQP4 and GFAP labeling at higher magnification. (Scale bar: Inset, 5 μm.)  They are also expressed in the inner ear (organ of Corti), in the retina and the optic nerve Associated disorders 1. AQP4s are targeted by autoantibodies in neuromyelitis optica (NMO) 2. AQP4s are upregulated by direct insult to the central nervous system. This may result in vasogenic brain oedema 3. Cytotoxic brain oedema may be an important mechanism in “idiopathic” intracranial hypertension and hepatic encephalopathy

The astrocyte water channel aquaporin-4 (AQP4) is expressed as heterotetramers of M1 and M23 isoforms in which the presence of M23-AQP4 promotes formation of large macromolecular aggregates termed orthogonal arrays (J Cell Biol 2014; 204 (4): 559-73). o Individually expressed M1-AQP4 are freely mobile in the plasma membrane and could diffuse into rapidly extending lamellipodial regions to support cell migration.

47 o In contrast, M23-AQP4s form large arrays that do not diffuse rapidly enough to enter lamellipodia and instead stably bind adhesion complexes and polarize to astrocyte end-feet in vivo. o Co-expressed M1- and M23-AQP4s form aggregates of variable size that segregate due to diffusional sieving of small, mobile M1-AQP4-enriched arrays into lamellipodia and preferential interaction of large M23-AQP4-enriched arrays with the extracellular matrix. o Anti-AQP4 seropositivity is also associated with a reduction of the EAATS (the high affinity glutamate transporter) o An important pathological mechanism is complement-dependent cytotoxicity (J Biol Chem 2012; 287 (17): 13829-39). The disorder is characterized by medullary lesions with necrosis – rendering a prompt diagnosis a prerequisite for satisfactory treatment. o Unfortunately, relapses may occur as well – and irreversible medullary damage may be the outcome

Clinical features of anti-AQP4 seropositivity: a spectrum of disorders NMO (Devic’s syndrome), LETM, recurrent optic neuritis Astrocytic AQP4 is expressed at nodes of Ranvier. Thereby anti-AQP4 could initiate demyelination In children also episodic cerebral symptoms: Encehpalopathy Neurology Ophthalmoparesis Ataxia Seizures Intractable vomiting, or hiccups Uncontrollable vomiting and hiccups, are now recognized as relatively “specific” symptoms of NMO that are due to brainstem involvement Ophtalmology Müller cells are optic fibres of the retina expressing AQP4s and which control the composition of the extracellular space fluid. So anti-AQP4 could add to the optic neuritis features Placenta Miscarriage Skeletal muscles Autoimmune myopathy with episodic myalgia International consensus diagnostic criteria for neuromyelitis optica spectrum disorders. Neurology 2015; published ahead of print

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

International consensus diagnostic criteria for neuromyelitis optica spectrum disorders Neurology 2015; 85 (2): 177-89.

Anti-AQP4’s appear to favour symptoms at sites where the AQP4s are most accessible AQP4 immunoreactivity in the NMO, optic neuritis LETM Infarction due to posterior part of the optic nerve (A- longitudinally E) and in the optic nerve head (F) embolus extensive transverse Spinal cord MRI myelitis visualizes expansion of a lesion from C2 to C5 levels

In about 47 % of NMO patients, there is reported serological evidence of recent viral infection when such a screening is performed during the acute phase of the neurologic illness (Koga M, Takahashi T, Kawai M, Fujihara K, Kanda T. A serological analysis of viral and bacterial infections associated with neuromyelitis optica. Journal of the Neurological Sciences 2011; 300 (1): 19-22)

Diagnostics o Currently, the golden standard of anti-AQP4 testing is using CBAs with transfected cells expressing either the M1 or the M23 isoform. This is explainable, since most such sera are double seropositive (anti- M1 and anti-M23). o However, the sensitivity has been reported as follows: anti-M23 (97 %) and anti-M1 (70 %) for AQP4 IgG assays in cases of for NMO, and with a specificity of 100% compared to the controls. The conformational epitopes of M23 AQP4 may be the primary targets of NMO-IgG antibodies, whereas anti-M1 AQP4 appears to be more prevalent with increasing disease duration and number of relapses (Mader et al. 2010). This is in contrast to a systematic testing of 77 sera, reporting similar specificities and sensitivities of both assays: above 95 % (Journal of Neuroinflammation 2014, 11:129). o The results of a multicentre comparison of European diagnostic AQP4 antibody assays are now available (Waters PJ et al. Neurology 2012; 78:665–671; Clinical and Experimental Neuroimmunology 2014; 3: 290- 303). Live (unfixed) cell-based assays were the most specific (mean 99.8 %, range 99.4-100.2 %), followed by fixed cell-based assays (92.4-93.9 %). AQP4 antibody sensitivity ranged from 71.6-81.8 % (mean 76.7 %). Signal/noise differences may be an issue comparing current assays for such testing. o There are no publications taking the duration of the disorder from onset to the date of a serum sample into account. Currently therefore, it is not known if anti-AQP4 (M23) seropositivity may be a feature prior to the occurrence of anti-AQP4 (M1) – thus enabling more rapid diagnostics by an anti-AQP4 (M23) assay. o Anti-MOG is also a finding in some anti-AQP4 positive sera – please also see anti-MOG associated encephalomyelitis.

Selected references 1. Agre P, Preston GM, Smith BL, Jung JS, Raina S, Moon C, Guggino WB, Nielsen S. Aquaporin CHIP: the archetypal molecular water channel. Am J Physio 1993; 265 (4 Pt 2): F463–76 2. Tajkhorshid E, Nollert P, Jensen MØ, Miercke LJ, O'Connell J, Stroud RM, Schulten K. Control of the selectivity of the aquaporin water channel family by global orientational tuning. Science 2002; 296 (5567): 525–30. 3. Amiry-Moghaddam M, Otsuka T, Hurn PD, Traystman RJ, Haug FM, Froehner SC, Adams ME, Neely JD, Agre P, Ottersen OP, Bhardwaj A. An alpha-syntrophin-dependent pool of AQP4 in astroglial end-feet confers bidirectional water flow between blood and brain. Proc Natl Acad Sci 2003; 100 (4): 2106-11 4. Agre P, Kozono D. Aquaporin water channels: molecular mechanisms for human diseases. FEBS Lett 2003; 555 (1): 72–8. 5. de Groot BL, Grubmüller H. The dynamics and energetics of water permeation and proton exclusion in aquaporins. Curr Opin Struct Biol 2005; 15 (2): 176–83 6. Lennon VA, Kryzer TJ, Pittock SJ, Verkman AS, Hinson SR. IgG marker of optic-spinal multiple sclerosis binds to the aquaporin-4 water channel. J Exp Med 2005; 202 (4): 473–7. 7. Agre P. The aquaporin water channels. Proc Am Thorac Soc 2006; 3 (1): 5–13. 8. Kruse E, Uehlein N, Kaldenhoff R. The aquaporins. Genome Biol 2006; 7 (2): 206. 9. Schrier RW. Aquaporin-related disorders of water homeostasis. Drug News Perspect 2007; 20 (7): 447–53 10. Fu D, Lu M. The structural basis of water permeation and proton exclusion in aquaporins. Mol Membr Biol 2007; 24 (5-6): 366–74. 11. McKeon A, Lennon VA, Lotze T, Tenenbaum S, Ness JM, Rensel M, Kuntz NL, Fryer JP, Homburger H, Hunter J, Weinshenker BG, Krecke K, Lucchinetti CF, Pittock SJ. CNS aquaporin-4 autoimmunity in children. Neurology 2008; 71: 93 -100. 12. Li W, Minohara M, Piao H, Matsushita T, Masaki K, Matsuoka T, Isobe N, Su JJ, Ohyagi Y, Kira J. Association of anti- Helicobacter pylori neutrophil-activating protein antibody response with anti-aquaporin-4 autoimmunity in Japanese patients with multiple sclerosis and neuromyelitis optica. Multiple Sclerosis 2009; 15 (12): 1411-1421. 13. Jarius S, Wildemann B. AQP4 Antibodies in Neuromyelitis Optica: Diagnostic and Pathogenetic Relevance. Nature Reviews Neurology 2010; 6: 383-392. 14. Phuan PW, Ratelade J, Rossi A, Tradtrantip L, Verkman AS. Complement-dependent cytotoxicity in neuromyelitis optica requires aquaporin-4 protein assembly in orthogonal arrays. J Biol Chem 2012; 287 (17): 13829-39. 30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

15. Hinson SR, Roemer SF, Lucchinetti CF, Fryer JP, Kryzer TJ, Chamberlain JL, Howe CL, Pittock SJ, Lennon VA. Aquaporin-4-binding autoantibodies in patients with neuromyelitis optica impair glutamate transport by down- regulating EAAT2. J Exp Med 2008; 205 (11): 2473-81. 16. P Waters, M I Leite, B Gray, A Vincent, Y Jiang, J Palace. PAW33 Aquaporin-4 M 23 isoform provides a more sensitive assay for aquaporin-4 antibodies. J Neurol Neurosurg Psychiatry 2010; 81 17. Crane JM, Lam C, Rossi A, Gupta T, Bennett JL, Verkman AS. Binding Affinity and Specificity of Neuromyelitis Optica Autoantibodies to Aquaporin-4 M1/M23 Isoforms and Orthogonal Arrays. J Biol Chem 2011; 286, 16516-16524. 18. Mader S, Di Pauli F, Kuenz B, Schanda K, Boul-Enein F, Khalil M, Storch KM, Jarius S, Kristoferitsch W, Berger T, Reindl M. Patterns of Antibody Binding to Aquaporin-4 Isoforms in Neuromyelitis Optica. PLOS 2010 May; 19. Hinson SR, Romero MF, Popescuc BFGH, Lucchinettic CF, Fryera HP, Wolburgd H, Fallier-Beckerd P, Noelle S, Lennon VA. Molecular outcomes of neuromyelitis optica (NMO)-IgG binding to aquaporin-4 in astrocytes. PNAS 2012; 109 (4): 1245–1250. 20. Waters PJ, McKeon A, Leite MI et al. Serologic diagnosis of NMO. A multicenter comparison of aquaporin-4 assays. Neurology 2012; 78; 665-671 21. Marios C, Papadopoulos MC, Verkman AS. Aquaporin water channels in the nervous system. Nature Reviews Neuroscience 2013; 14: 265-77. 22. Kremer L, Mealy M, Jacob A, Nakashima I, Cabre P, Bigi S, Paul F, Jarius S, Aktas O, Elsone L, Mutch K, Levy M, Takai Y, Collongues N, Banwell B, Fujihara K, de Seze J. Brainstem manifestations in neuromyelitis optica: a multicenter study of 258 patients. Mult Scler 2013; 13524585113507822 23. Takai Y, Misu T, Takahashi T, Nakashima I, Fujihara K. [NMO spectrum disorders and anti AQP4 antibody]. [Article in Japanese]. Brain Nerve 2013; 65 (4): 333-43. 24. Jacob A, McKeon A, Nakashima I, Sato DK, Elsone L, Fujihara K, de Seze J. Current concept of neuromyelitis optica (NMO) and NMO spectrum disorders. J Neurol Neurosurg Psychiat 2013; 84 (8): 933-30. 25. Waschbisch, C. Schaub, T. Derfuss, S. Schwab, D.H. Lee, M. Müller, R.A. Linke. Aquaporin-4 antibody negative recurrent isolated optic neuritis: Clinical evidence for disease heterogeneity. J Neurol Sci 2013; 332 (1-2): 72-5. 26. Marignier R, Bernard-Valnet R, Giraudon P, Collongues N, Papeix C, Zéphir H, Cavillon G, Rogemond V, Casey R, Frangoulis B, De Sèze J, Vukusic S, Honnorat J, Confavreux C; NOMADMUS Study Group. Aquaporin-4 antibody- negative neuromyelitis optica: distinct assay sensitivity-dependent entity. Neurology 2013; 80 (24): 2194-200. 27. Pisani F, Sparaneo A, Tortorella C, Mola MG, Nicchia GP, Frigeri S. Aquaporin-4 Autoantibodies in Neuromyelitis Optica: AQP4 Isoform-Dependent Sensitivity and Specificity. PlusOne 2013 November. 28. Levy M, Wildemann B, Jarius S, Orellano B, Sasidharan S, Weber MS, Stuve O. Immunopathogenesis of neuromyelitis optica. Adv Immunol 2014; 121: 213-42. 29. Sven Jarius, Friedemann Paul, Kai Fechner, Klemens Ruprecht, Ingo Kleiter, Diego Franciotta, Marius Ringelstein, Florence Pache, Orhan Aktas and Brigitte Wildemann. DNA-transfected cells with leaky scanning versus M23- AQP4-DNA-transfected cells as antigenic substrate. Journal of Neuroinflammation 2014, 11:129 30. Smith AJ, Jin BJ, Ratelade J, Verkman AS. Aggregation state determines the localization and function of M1- and M23-aquaporin-4 in astrocytes. J Cell Biol 2014; 204 (4): 559-73. 31. Waters PJ, PIttock SJ, Bennett jl et al. Evaluation of aquaporin-4 antibody assays [Review]. Clinical and Experimental Neuroimmunology 2014; 3: 290-303 32. Wingerchuk et al. International consensus diagnostic criteria for neuromyelitis optica spectrum disorders. Neurology 2015; 85 (2): 177-89.

Anti-MOG associated encephalomyelitis

Myelin Oligodendrocyte Glycoprotein (MOG) is a glycoprotein believed to be important in the process of myelinization of nerves in the central nervous system (CNS). In humans, the MOG gene (6p22.1) encodes this protein - and it speculated to serve as a necessary “adhesion molecule” to provide structural integrity to the myelin sheath. It is also known to develop late on the oligodendrocyte.

Molecular function While the primary molecular function of MOG is not yet known, its likely role with the myelin sheath is either in sheath “completion and/or maintenance”. More specifically, MOG is speculated to be “necessary” as an "adhesion molecule" on the myelin sheath of the CNS to provide the structural integrity of the myelin sheath.

MOG’s cDNA coding region in humans have been shown to be “highly homologous” to rats, mice, and bovine, and hence highly conserved. This suggests “an important biological role for this protein”.

Structure The MOG gene is forming at least nine isoforms. Developmentally, MOG is formed "very late on oligodendrocytes and the myelin sheath".

MOG - myelin oligodendrocyt glycoprotein Clinical features

 ADEM (about 40 %)

 Clinically isolated syndrome (CIS)

 Recurrent opticus neuritis

 Transverse myelitis including longitudinal extensive (LETM)

The preferred method of anti-MOG detection is by CBA using transfected live cells. o Consider longitudinal monitoring of anti-MOG, since a rapid decline of titres is associated with a more favourable prognosis o Up to 50 % of patients with an isolated first episode of LETM are seronegative for NMO-IgG/AQP4. It has been reported that about 23 % of such cases are MOG-IgG positive o Anti-AQP4 is also a finding in some anti-MOG positive sera – please see anti-AQP4 spectrum of disorders as well

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Algorithm: anti-AQP4, anti-MOG and anti-CV2(CRMP5) Autoantibody A feature of the following diagnoses Anti-AQP4 (M1) Anti-MOG Anti-CV2 (CRMP5) Positive Positive Negative NMO, LETM, transverse myelitis, neuritis optica Positive Negative Negative NMO, LETM, transverse myelitis, neuritis optica Negative Positive Negative CIS, MS, ADEM Negative Negative Negative CIS, MS, ADEM Negative Negative Positive LETM, transverse myelitis, neuritis optica Abbreviations: ADEM – acute disseminated encephalomyelitis; CIS – clinically isolated syndrome; LETM - longitudinal extensive myelitis; MS – multiple sclerosis; NMO – neuromyelitis optica

Selected list of references to MOG 1. Brilot F, Dale RC, Selter RC, Grummel V, Kalluri SR, Aslam M, Busch V, Zhou D, Cepok S, Hemmer B. Antibodies to native myelin oligodendrocyte glycoprotein in children with inflammatory demyelinating central nervous system disease. Ann Neurol. 2009; 66(6): 833-42. 2. Brilot F, Grummel V, Kraus V, Cepok S, Dale RC, Hemmer B. Antibody responses to EBV and native MOG in pediatric inflammatory demyelinating CNS diseases. Neurology 2010; 74 (21): 1711-1715 3. Mader S, Gredler V, Schanda K, et. Al. Complement activating antibodies to myelin oligodendrocyte glycoprotein in neuromyelitis optica and related disorders. Journal of Neuroinflammation 2011, 8: 184 doi: 10.1186/1742-2094- 8-184 4. Pröbstel AK, Dornmair K, Bittner R et al. Antibodies to MOG are transient in childhood acute disseminated encephalomyelitis. Neurology. 2011 Aug 9; 77 (6): 580-8. 5. Rostasy K, Mader S, Schanda K, Huppke P, Gärtner J, Kraus V, Karenfort M, Tibussek D, Blaschek A, Bajer-Kornek B, Leitz S, Schimmel M, Di Pauli F, Berger T, Reindl M. Anti-myelin oligodendrocyte glycoprotein antibodies in pediatric patients with optic neuritis. Arch Neurol 2012; 69 (6): 752-6. 6. Ryusaku Matsuda, Takeshi Kezuka, Akihiko Umazume, Yoko Okunuki, Hiroshi Goto, Keiko Tanaka. Clinical Profile of Anti-Myelin Oligodendrocyte Glycoprotein Antibody Seropositive Cases of Optic Neuritis. Neuro-Ophthalmology 2015, 39 (5): 213-219

Anti-Dopamine receptor (basal ganglia - post-streptococcal) spectrum of encephalitis A somewhat complex autoimmune disorder with combined pre- and post-synaptic pathological mechanisms.

Symptomatology The severity is variable from quite mild (tics in schoolchildren during the winter semester) to extremely severe with complex and pronounced neuro-psychiatric features.

Originating from the basal ganglia, these are choreiform movements, tics, dystonia and Parkinsonism.

In addition, prominent psychiatric symptoms of attention deficit disorder, emotional lability, OCD and psychosis. Distinguishing features: movement disorders, tics, chorea, multifocal myoclonic jerks; neuro-psychiatric features such as OCD with restricted food intake (weight loss) Usually, this disorder sets in suddenly (“overnight”) Onset: reported from 3-4 years and above, and more rarely after teenage Course: frequently a relapsing or slowly progressive disorder

Typically, the clinical picture is limited to only a few of the associated symptoms  Movement disorders: tics (motor, vocal), facial grimacing, chorea (usually affecting limbs; maybe unilateral), dystonia, parkinsonism, dysgraphia, motor hyperactivity  Obsessive-compulsive disorder (OCD) and / or severely restricted food intake  Emotional lability, anxiety (e.g. separation), episodes of unmotivated fear  Unmotivated aggression, social withdrawal, behavioural (developmental) regression  Psychosis (hearing voices – hallucinations)  Epilepsy: multifocal myoclonus (spasms), multifocal myokymia, maybe series of hiccups (jerks of the diaphragm, oesophagus) – probably of thalamic origin  Slowed cognition, memory dysfunction (sudden decline of performance in school)  Enuresis, increased urinary frequency – not related to urinary infections  Dysaesthesia with painful touches of the skin distally at upper or lower limbs (probably of thalamic origin (ventral posterior nucleus) and not polyneuropathy)  Sleep disorders, including sleep inversion

It appears that the clinical manifestations vary by geographical locations, and which may be attributed to exposure to different and local subsets of streptococcal serotypes. In Denmark for example, we have only observed a few cases of so-called PANDAS and many more cases with a complex neuropsychiatric symptomatology. Moreover, some cases only with dystonia - or with multifocal myoclonus including hiccups. In particular, in adults, this may be limited to multifocal myokymias. When treated with intravenous high- dose immunoglobulin (same protocol as for Guillain-Barré syndrome), also these cases appear to respond very well.

For details about diagnostic criteria of PANS vs. PANDAS please see: Pediatr Therapeut 2012; 2 (2) Exclusively, these criteria comprise childhood and paediatric onset cases. In Denmark however, we have diagnosed patients with onsets from 8 months to 65 years of age, although and in most cases, these are also 30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

within the paediatric range. Moreover, it appears that the symptomatology is more diverse than what is covered by these criteria.

Epidemiology and clinical features

Post-streptococcal neurology in Denmark Annual incidence rates per 100,000 population 2010 2011 2012 2013 0.07 0.15 0.24 0.78 Most likely, the increasing rates are attributable to underdiagnosis

DK patients n=79 Age Group by Onset 20% 18% 16% 14% 12% 10% 8% 6% 4% 2% 0%

This epidemiology proposes: early- and late-onset cases - and a dichotomy at age groups < 27-30 years

Post-infectious spectrum of neurological disorders associated with dopaminergic and serotonergic pathways Tics Motor symptoms, more or less mono Chorea, or chorea-like Dystonia symptomatic – anti-D2 related Multifocal myoclonic fits Multifocal myokymias Motor symptoms, various combinations of above – simultaneously or over time – anti-D2 Combined motor related Neuro-psychiatric features with or without More complex symptomatology – anti-D1, sleeping disorder anti-D2 & serotonergic pathways related  With motor symptoms  Without motor symptoms

CNS locations of this disorder  Motor and sensory symptoms  Basal ganglia (including thalamus)  Major parts are motor signal relays  Ventral posterier nucleus is a sensory relay  OCD  Orbital-frontal cortex  Other features – more areas of the CNS

Dopamine receptor antibodies in patients with elevated CamKII percentage (n=76) Location of some dopamine receptors: D1 - widely expressed throughout the brain D2 - primarily in the basal ganglia 70% 60% 50% 40% 30% 20% 10% 0% Anti-D1+, D2+ Anti-D1+, D2 - Anti-D1-, D2+

DK patients: clinical subtype by decreasing order of frequency Neuropsychiatric without motor symptoms Neuropsychiatric with motor symptoms Chorea, also as hemichorea Tics only Multifocal myoclonic fits, hiccups Dystonia Multifocal myokymia Combined motor over time

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Proposed diagnostic strategy in presumed post-streptococcal autoimmunity 1. Diagnose a current GAS-infection or other infection Throat swap Culture to show the presence of GAS  Anti-Streptolysin O (AST) Monitor at least two samples over time (e.g. with an Serum samples  Anti-Streptococcal DNAse B (ASDB) interval of 2-3 weeks) to document increasing/decreasing  Consider tests for other infectious triggers titres – as opposed to steady state 2. At later occurrence of neurological symptoms Lumbar puncture  Total protein (hyperproteinorachia?), IgG level  Oligoclonal bands  Pleiocytosis Serum samples,  Anti-Lyso-GM1 (IgG) CSF samples?  CamKII activity in culture of neuroblastoma cells incubated with such serum / CSF Monitor consecutive samples over time to  Anti-Dopamine-receptor 1 (D1) document increasing / decreasing titres  Anti-Dopamine-receptor 2 (D2)  Anti-β-Tubulin (IgG) Please note that the measurement of CamKII is an estimation of an activated enzyme as a percentage of normal activity, and not an estimate of an autoantibody titre. Thereby, elevated CamKII % signifies pathological biochemistry in neurons because of excessive downstream activation. Furthermore, the sensitivity of the CamKII assay is much higher than that of any of the autoantibodies assays.

A finding of anti-Streptococcal antibodies is quite common in children (AST, ASDB) – with a frequency of about 90 % being typical. Moreover, variation of such titers in an individual patient is associated with an ongoing infection and detectable long time thereafter. This is an expected feature and serves to cure the infection – and is not a biomarker of autoimmunity including in the central nervous system.

Figure to the right (first time onset): individuals with streptococcal infections and a subsequent neurological disorder may have an increased percentage of activated CamKII and elevated or normal titres of one or more of these antibodies, which in the presence of associated symptoms suggests a post-streptococcal neurological disorder.

Most frequently, one or more titres of these autoantibodies are above the reference and more rarely, all titres are elevated along with an increased concentration of CaMKII. An isolated elevated percentage of CaMKII can also be found, although sometimes together with borderline values of one or more of these autoantibodies.

Animal models suggest that these autoantibodies play a role in the disease, but they can also be biomarkers. There are of course other types of tics and OCD, which are associated with other infections, and are not streptococcal related.

Once autoimmunity has been triggered – it may be difficult or impossible to make it stop, so thereafter, the course may be relapsing-remitting, waxing-waning and/or slowly progressive. The autoimmunity is provoked outside the central nervous system and is passively transferred into the CNS through a defect blood-brain barrier (BBB). Once the BBB is repaired, the disorder may remit.

However and since the autoimmune factors are circulating in the blood stream, a relapse may occur upon any consecutive BBB defect due to new infections - or after a new provoked autoimmunity.

Typical occurrence over time

Relaps Trend

Diagnostic algorithm

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Treatment Prophylaxis  Primary – V-penicillin as soon as possible on symptoms consistent with a streptococcal infection, e.g. a sore throat – over seven to ten days. Alternatively, Azithromycin on three consecutive days.  Secondary – long-term treatment with various penicillins or azithromycin on risk of repeated infections with short intervals. This modality of treatment is established for rheumatic fever (RF) and Sydenham chorea (WHO criteria and guidelines: Cilliers AM. Rheumatic fever and its management. BMJ 2006 ; 333(7579): 1153–1156). Most probably however and if RF is not a feature, this treatment should only be considered in more exceptional cases Antibiotics have no effect on the neurological symptoms and are therefore given preventive or to shorten an on-going GAS-infection as much as possible. In short, antibiotics may cure an infection, whereas presumed effect on the neurological features is explicable in terms of spontaneous recovery. Moreover and due to variable compliance and other factors, a new GAS infection may set in anyway - and thereafter recurrence of neurological symptoms.

 Moreover and as to the benefit of tonsillectomy, conflicting results have been reported

On neurological symptoms of a non-tolerable severity  Intravenous immunoglobulin (IVIG) or plasma exchange  IVIG in combination with steroid in cases with more severe features or prolonged symptoms

When such autoimmunity has been provoked, it is difficult or maybe not possible to stop it. Therefore, this disorder may become chronic and with overlapping relapses. Unfortunately, the effect of IVIG is short lasting and eventually in such cases, the symptomatology is likely to return to its previous state.

Chronic relapsing-remitting course: there are several options for treatment

 Maintenance therapy with IVIG given with three to four months’ interval. There are several draw backs to such a choice: IVIG does not result in any cure, and the effect over time is likely to be less and less evident  A better remedy may be a combination of steroid and Azathioprine. Both drugs are immunosuppressive - and steroids anti-inflammatory. This combination treatment is given daily and over years. Due to Azathioprine, a lower maintenance dose of steroid is administered and thereby with a prospect of no or only tolerable adverse effects. This treatment is following the same principle as that of myasthenia gravis  On no effect of suggestions above, consider Rituximab

Scientific documentation

Streptococcal post-infectious autoimmune encephalitis

MRI of the brain in a somnolent patient with bradykinesia and rigidity, showing inflammatory lesions (arrows) in the (a) midbrain and periaqueductal grey matter, (b) Right putamen and (c) Bilaterally in thalami and midbrain. (d) Convalescent imaging showing resolution of the inflammatory changes in the thalami and midbrain

Presumably and in many cases, MRI is “disappointingly” unrevealing - at least at the onset and during the initial course Encephalitis lethargica syndrome: 20 new cases and evidence of basal ganglia autoimmunity

Please also see - Kumar et al. - Evaluation of Basal Ganglia and Thalamic Inflammation in Children With Pediatric Autoimmune Neuropsychiatric Disorders Associated With Streptococcal Infection and Tourette Syndrome: A Positron Emission Tomographic (PET) study Using 11C-[R]-PK11195. J Child Neurol August 12, 2014

For details about PET, please see Kumar et al. - Evaluation of Basal Ganglia and Thalamic Inflammation in Children With Pediatric Autoimmune Neuropsychiatric Disorders Associated With Streptococcal Infection and Tourette Syndrome: A Positron Emission Tomographic (PET) study Using 11C-[R]-PK11195. Child Neurol 2015; 30 (6): 749-756

Significant scientific advances suggesting explanations for some initial steps of the pathogenic mechanisms - brief overview:

In streptococcal induced rheumatic fever, autoantibodies against intracellular biomarker antigens have been identified: cardiac myosin, tubulin (brain) and keratin (skin). Moreover and subsequent to a streptococcal infection, autoantibodies targeting extracellular epitopes within the CNS have been reported: anti-lyso-GM1, anti-Dopamine receptor D1 & D2, and anti-Neuroleukin. Sera from both Sydenham chorea and PANDAS have been reported to induce inhibitory signaling of D2 receptors on transfected cells (Cox et al. J Immunol 2013; 191 (11): 5524-41).

Antineuronal antibody may bind to receptors or other structures on neuronal cells and trigger the signaling cascade of CaMKII. In addition, other factors may gain intracellullar accces and trigger biochemical mechanisms.

Class III β-tubulin (gene symbol TUBB3: 16q24.3) is a microtubule element expressed exclusively in neurons, and is a popular identifier specific for neurons in nervous tissue. It has been reported that monoclonal chorea antibodies label both intra- and extracellular antigens of a neuronal cell line providing evidence suggesting mimicry between intracellular brain protein tubulin and extracellular lysoganglioside.

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Functions of calcium/calmodulin-dependent protein kinase II (CamKII) Due to its ability for autophosphorylation, CaMKII activity can outlast the intracellular calcium transient that is needed to activate it. In neurons, this property is important for the induction of synaptic plasticity. Pharmacological inhibition of CaMKII blocks the induction of long-term potentiation. Upon activation, CaMKII phosphorylates postsynaptic glutamate receptors and thus changes the electrical properties of the synapse. The figure provides an overview of some effects of this multifunctional kinase. Within a context of post-streptococcal pathology, synthesis and release of neurotransmitters (dopamine and serotonin) and synaptic plasticity may be the most significant ones. Lyso-GM1, a compound of neural cell membranes, stabilizes the level of intracellular Ca++. Antibody binding to lyso-GM1 may cause an increased level of intracellular Ca++ and thereby downstream activation of CamKII. However, other mechanisms of CamKII activation may also be operative as related to this type of autoimmune encephalitis. Boosting synaptic sensitivity: CaMKII triggers nearby synapses to attract more receptors for the neurotransmitter glutamate: red arrows point to CamKII

Increasing levels of CamKII

Synapses

Glutamate abnormalities contribute to the pathogenesis of OCD Lemieux M, Labrecque S et al. The Journal of Cell Biology 2012; 198 (6): 1055-1073

Activation of CamKII also causes an increased level of neurotransmitters, whereby DOPAMINE abnormalities appear to contribute to the pathogenesis of movement disorders associated with post-streptococcal neurology.

These features have been confirmed by a new animal model in Lewis rats as well as in a cell model using a culture of nerve cells; please see below.

Immunohistochemistry: neurons in culture

a - acute PANDAS serum b - acute Sydenham serum c - normal serum

Kirvan CA, Swedo SE, Snider LA, Cunningham MW. Antibody-mediated neuronal cell signaling in behavior and movement disorders. Journal of neuroimmunology 2006; 179 (1-2): 173-179.

Animal and cell models Behavioral, pharmacological, and immunological abnormalities after streptococcal exposure: A novel rat model of Sydenham chorea and related neuropsychiatric disorders Brimberg L, Benhar I, Mascaro-Blanco A, Alvarez K, Winter C, Klein J, Moses AE, Somnier FE, Leckman JF, Swedo SE, Cunningham MW. Neuropsychopharmacology 2012; 37: 2076–2087.  In streptococcal immunized rats, there were antibody deposition in the striatum, thalamus, and frontal cortex, and concomitant alterations in dopamine and glutamate # levels in cortex and basal ganglia  Autoantibodies (IgG) of GAS rats caused elevated calcium/calmodulin-dependent protein kinase II signaling in SK-N-SH neuronal cells  Discovery of autoantibodies targeted against dopamine D1 and D2 receptors  Such immunized rats exhibited motor symptoms (impaired food manipulation and beam walking) and compulsive behavior (increased induced-grooming) #Treatment with Ketamine (a potent noncompetitive antagonist of the N-methyl-D-aspartate (NMDA) glutamate receptor) appears to be efficient in otherwise therapy-resistant OCD. Biol Psychiatry. 2012 Dec 1; 72(11): 964-70

Behavioral and neural effects of intra-striatal infusion of anti- streptococcal antibodies in rats Lotan D, Benhar I, Alvarez K, Mascaro-Blanco A, Brimberg L, Frenkel D, Cunningham MW, Joel D. Brain Behav Immun 2014; 38: 249-62 1. Passive transfer of purified antibodies from GAS-exposed rats into naïve rats Immunoglobulin G (IgG) purified from the sera of GAS-exposed rats was infused directly into the striatum of naïve rats over a 21-day period 2. Passive transfer of IgG purified from adjuvant-exposed rats as well as of naïve rats into naïve rats The behavior in the induced-grooming, marble burying, food manipulation and beam walking assays was compared in the three groups The pattern of in vivo antibody deposition in rat brain was evaluated using immunofluorescence and co-localization  IgG deposits in the striatum of infused rats co-localized with specific brain proteins such as dopamine receptors, the serotonin transporter and other neuronal proteins  Infusion of IgG from GAS-exposed rats to naïve rats led to behavioral and motor alterations partially mimicking those seen in GAS-exposed rats  These results demonstrate the potential pathogenic role of autoantibodies produced following exposure to GAS in the induction of behavioral and motor alterations, and support a causal role for autoantibodies in GAS-related neuropsychiatric disorders

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

The Figure is a summary of reported findings after in vitro incubation of neuroblastoma cells with sera containing anti-lyso-GM1 (and maybe additional and currently unknown factors) or monoclonals with the same specificity. CamKII activates tyrosine & tryptophan hydroxylase and synapsin-1 controlling release of these two neurotransmitters. Binding of the autoantibodies causes a reduction of the inhibitory effect of lysoganglioside GM1 on CaMKII, whereby more neurotransmitters (dopamine & serotonin) are synthesised and released (synapsin 1). Please see flow chart below. Note that both dopaminergic and serotonergic pathways are affected Molecular mimicry GlcNAc N-acetylglucosamine Epitope on group A streptococci and also a part of lyso-GM1. Synapsin I and synapsin II do also contain terminal GlcNAc

Molecular mimicry - Wikipedia, the free encyclopedia; Molecular Mimicry, Bystander Activation, or Viral Persistence: Infections and Autoimmune Disease

A combined pre- and post-synaptic autoimmune disorder

In summary:

Incubation with serum The normal inhibition of Increased or monoclonal IgG More phosphorylation of CaMKII by lyso-GM1 of the tyrosine- & tryptophan- against dominant GAS CSF membrane is reduced CaMKII hydroxylase epitope activity

Increased synthesis More of these CamKII also regulates Increased synthesis of l-dopa and neurotransmitters are synapsin I located at released into synaptic spaces presyntic terminals of serotonin thereby of dopamine

Increased CaMKII activity triggers Glutamate nearby synapses to attract more Boosting synaptic abnormalities receptors for the neurotransmitter sensitivity contribute to the

glutamate pathogenesis of OCD

Selected list of references to post-streptococcal topics (chronological listing by year of publication)

1. Kirvan CA, Swedo SE, Heuser JS et al. Mimicry and autoantibody-mediated neuronal cell signaling in Sydenham chorea. Nat Med 2003; 9: 914-20. 2. Dale RC, Church AJ, Surtees RAH, Lees AJ, Adcock JE, Harding B, Neville BGR, Giovannoni G. "Encephalitis lethargica syndrome: 20 new cases and evidence of basal ganglia autoimmunity". Brain 2004; 127 (Pt 1): 21– 33. http://www.ncbi.nlm.nih.gov/pubmed/14570817 3. Vincent A. Editorial - Encephalitis lethargica: part of a spectrum of poststreptococcal autoimmune diseases? Brain 2004; 127: 2-3 4. Tumpey TM, Basler CF, Aguilar PV. Characterization of the reconstructed 1918 Spanish influenza pandemic virus. Science 2005; 310: 77–80 5. Walker KG, Lawrenson J, Wilmshurst JM. Neuropsychiatric movement disorders following streptococcal infection. Dev Med Child Neurol 2005; 47: 771-5 6. Candler PM, Dale RC, Griffin S, Church AJ, Wait R, Chapman MD, Keir G, Giovannoni G, Rees JH. Post-streptococcal opsoclonus-myoclonus syndrome associated with anti-neuroleukin antibodies. J Neurol Neurosurg Psychiatry 2006; 77 (4): 507–512 7. Kirvan CA, Swedo SE, Kurahara D et al. Streptococcal mimicry and antibody-mediated cell signaling in the pathogenesis of Sydenham's chorea. Autoimmunity 2006; 39: 21-9 8. Kirvan CA, Swedo SE, Snider LA et al. Antibody-mediated neuronal cell signalling in behavior and movement disorders. J Neuroimmunol 2006; 179: 173-9 9. Li Y, Heuser JS, Kosanke SD, M.W. Cunningham MW. 2006. Mimicry and antibody-mediated cell signaling in autoimmune myocarditis. J Immunol 2006; 177: 8234-8240 10. Kirvan CA, Cox CJ, Swedo SE, Cunningham MW. Tubulin Is a Neuronal Target of Autoantibodies in Sydenham’s chorea. J Immunol 2007; 178: 7412-7421 11. McNamara, C, Zinkernagel AS, Macheboeuf P, Cunningham MW, V. Nizet V, O. Ghosh O. Coiled-coil irregularities and instabilities in group A streptococcal M1 are required for virulence functions. Science 2008; 319: 1405-1408 12. Brimberg L, Benhar I, Mascaro-Blanco A, Alvarez K, Lotan D, Winter C, Klein J, Moses AE, Somnier FE, Leckman JF, Swedo SE, Cunningham MW, Daphna Joel D. Behavioral, Pharmacological, and Immunological Abnormalities after 30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Streptococcal Exposure: A Novel Rat Model of Sydenham Chorea and Related Neuropsychiatric Disorders. Neuropsychopharmacology (2012) 37, 2076–2087 13. Dale RC, Merheb V, Pillai S, Wang D, Cantrill L, Murphy TK, Ben-Pazi H, Varadkar S, Aumann TD, Horne MK, Church AJ, Fath T, Brilot F. Antibodies to surface dopamine-2 receptor in autoimmune movement and psychiatric disorders. Brain 2012; 135 (Pt 11): 3453-68Swedo SE, Leckman JF, Rose NR. From Research Subgroup to Clinical Syndrome: Modifying the PANDAS Criteria to Describe PANS (Pediatric Acute-onset Neuropsychiatric Syndrome). Pediatr Therapeut 2012; 2 (2) 14. Cox CJ, Sharma M, Leckman JF, Zuccolo J, Zuccolo A, Kovoor A, Swedo SE, Cunningham MW. Brain human monoclonal autoantibody from sydenham chorea targets dopaminergic neurons in transgenic mice and signals dopamine d2 receptor: implications in human disease. J Immunol 2013; 191 (11): 5524-41 16. Hilla Ben-Paz H, Stoner, JA, Cunningham MW. Dopamine Receptor Autoantibodies Correlate with Symptoms in Sydenham's Chorea . PlusOne 2013; 8 (9) 17. Lotan D, Benhar I, Alvarez K, Mascaro-Blanco A, Brimberg L, Frenkel D, Cunningham MW, Joel D. Behavioral and neural effects of intra-striatal infusion of anti-streptococcal antibodies in rats. Brain Behav Immun 2014; 38: 249- 62. 18. Kumar A, Williams M, Shygani H. Evaluation of Basal Ganglia and Thalamic Inflammation in Children With Pediatric Autoimmune Neuropsychiatric Disorders Associated With Streptococcal Infection and Tourette Syndrome: A Positron Emission Tomographic (PET) study Using 11C-[R]-PK11195. Child Neurol 2015; 30 (6): 749-756 19. Rush CM, Govan BL, Sikder S, Williams NL, Ketheesan N. Animal Models to Investigate the Pathogenesis of Rheumatic Heart Disease. Frontiers in Pediatrics 2014; 2: 116 20. Pavone P, Rapisarda V, Serra A, Nicita F, Spalice A, Parano E, Rizzo R, Maiolino L, Di Mauro P, Vitaliti G, Coco A, Falsaperla A, Trifiletti RR, Cocuzza S. Pediatric autoimmune neuropsychiatric disorder associated with group a streptococcal infection: the role of surgical treatment. Int J Immunopathol Pharmacol 2014; 27 (3): 371-8. 21. Demesh D, Virbalas JM, Bent JP. The role of tonsillectomy in the treatment of pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS). JAMA Otolaryngol Head Neck Surg 2015; 141 (3): 272-5. 22. Simone Macrì S, Ceci C, Onori MP, Invernizzi RW, Bartolini E, Altabella L, Canese R, Imperi M, Orefici G, Creti R, Margarit I, Magliozzi R, Laviola G. Mice repeatedly exposed to Group-A β-Haemolytic Streptococcus show perseverative behaviors, impaired sensorimotor gating, and immune activation in rostral diencephalon. Nature.com/Scientific Reports 2015; 5: 13257.

Autoimmune encephalitis directed at other structures

Gluten associated autoimmune encephalitis Distinguishing features: ataxia, partial seizures, palatal tremor, polyneuropathy, chorea, gastrointestinal symptoms

Anti-TG6 (alias TGM6, TGY, IgG, IgA); neuronal transglutaminase; transglutaminase 6, glutamine gamma- glutamyltransferase 6

Genetics and more Neuronal Transglutaminase; TG6; TGM6; TRANSGLUTAMINASE Y; TGY HGNC Approved Gene Symbol: TGM6 TG6, TGY, SCA35 Cytogenetic location: 20p13 Genomic coordinates (GRCh37): 20:2,361,553 - 2,413,398

Overview: transglutaminases Approved Previous Mutational or autoimmune (¤) Approved name Synonyms Chromosome symbol symbols disorders TGM1 transglutaminase 1 ICR2 TGASE, TGK, LI, LI1 14q11.2 Ichthyosis TGM2 transglutaminase 2 TGC 20q12 Cardiomyopathy

TGM3 transglutaminase 3 TGE 20q11.2 ¤ Dermatitis herpetiformis

TGM4 transglutaminase 4 TGP 3p22-p21.33

TGM5 transglutaminase 5 TGX 15q15 Peeling skin syndrome Spinocerebellar ataxia type 35

TGM6 transglutaminase 6 TGM3L dJ734P14.3, TGY, SCA35 20p13 ¤ Gluten associated autoimmune encephalitis

TGM7 transglutaminase 7 TGMZ 15q15.2

¤ explaining why skin symptoms rather than intestinal symptoms appear in a proportion of patients with gluten-sensitive disease

Transglutaminases (TG) form a family of enzymes that catalyse various post-translational modifications of glutamine residues in proteins and peptides including intra- and intermolecular isopeptide bond formation, esterification and deamidation.

TG6 is expressed in a human carcinoma cell line with neuronal characteristics and in mouse brain. Besides full-length protein, alternative splicing results in a short variant lacking the second β-barrel domain in man and a variant with truncated β-sandwich domain in mouse. Biochemical data show that TG6 is allosterically regulated by Ca(2+) and guanine nucleotides. Molecular modelling indicates that TG6 could have Ca(2+) and GDP-binding sites related to those of TG3 and TG2, respectively. Localization of mRNA and protein in the mouse identified abundant expression of TG6 in the central nervous system. Analysis of its temporal and spatial pattern of induction in mouse development indicates an association with neurogenesis. Neuronal expression of TG6 hasd been confirmed by double-labelling of mouse forebrain cells with cell type-specific markers. Induction of differentiation in mouse Neuro 2a cells with NGF or dibutyryl cAMP is associated with an upregulation of TG6 expression. Familial ataxia has recently been linked to mutations in the TGM6 gene. 30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Autoantibodies to TG6 were identified in immune-mediated ataxia in patients with gluten sensitivity. These findings suggest a critical role for TG6 in cortical and cerebellar neurons.

About 10 % of patients with gluten sensitivity, also known as celiac disease, develop neurologic involvement, which can take the form of cerebellar involvement (termed 'gluten ataxia.') or peripheral neuropathy.

Gluten associated ataxia may also occur in the absence of enteropathy, and is associated with circulating antibodies to gliadin. Hadjivassiliou et al. (2008) found about 45 % of 20 patients with gluten-sensitive enteropathy had autoantibodies against TGM6, as well as autoantibodies against the more common antigen TGM2. The frequency of positive TGM6 IgA antibodies was similar among those with gluten ataxia with enteropathy (6 of 15, 40 %) and among those with gluten ataxia without enteropathy (9 of 19, 47 %). The overall prevalence of anti-TGM6 IgA and/or IgG antibodies was 62 % in patients with gluten ataxia compared to 45 % in celiac disease. Postmortem examination of a patient with gluten ataxia without enteropathy showed cerebellar IgA deposits that contained TGM6. Taken together, the findings suggested that TGM6 may be a prevalent autoantigen in gluten ataxia.

Prevalence of anti-transglutaminase antibodies in patients with gluten associated and sporadic ataxia

DGP: deamidated gliadin protein; Cambridge University Press 2014 (page 62)

Neurological presentations of 424 patients with gluten sensitivity, who presented with neurological dysfunction and were seen in the gluten sensitivity/neurology clinic, in Sheffield, UK, from 1994 to 2009 Appearances n Ataxia (6 patients with myoclonus, 2 with palatal tremor) 184 (67) Peripheral neuropathy 174 (46) Sensorimotor axonal neuropathy 125 Mononeuropathy multiplex 19 Sensory neuronopathy 14 Small fibre neuropathy 8 Motor neuropathy 8 Encephalopathy 62 (36) Myopathy 18 (10) Myelopathy 6 (2) Stiff-man syndrome 6 (2) Chorea (often with ataxia) 3 (2) Neuromyotonia 1 (1) Epilepsy and occipital calcifications 1 (0) The number of patients from each group that had enteropathy on biopsy is shown in brackets. Some patients had more than one type of neurological presentation

Cerebellar atrophy – occipital calcificatons

Brain 2003; 126 (Pt 3): 685-91 Developmental Medicine & Child Neurology 2013: 55: 90-93 Cambridge University Press 2014

Selected list of references

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16. Peters SL, Biesiekierski JR, Yelland GW, Muir JG, Gibson PR. Randomised clinical trial: gluten may cause depression in subjects with non-coeliac gluten sensitivity - an exploratory randomised clinical study. Aliment Pharmacol Ther 2014; 39: 1104–12. 17. Movement Disorders in Neurologic and Systemic Disease (page 60 onwards), ed. Werner Poewe and Joseph Jankovic. Cambridge University Press 2014.

Hashimoto’s encephalitis and autoimmune thyroiditis

The encephalitis is associated with anti-Alpha-enolase (ENO1), the target being the N-terminal region (amino terminal) of alpha-enolase. The co-existent struma is associated with the following autoantibodies: anti- thyroglobulin, anti-thyroid peroxidase antibodies, anti-TSH receptor, and anti-M. Anti-ENO1 is also a feature of paraneoplastic retinitis.

The following table summarizes a variety of findings Demographics Clinical manifestations Prevalence 2.1 / 100,000 Tremor 84 % Median age at onset (years) 44, range 9-78 Transient aphasia 73 % Paediatric presentation (<18 years) 22 % Seizures 66 % Gender (female) 81 % Status epilepticus 12 % Relapsing / remitting type 60 % Myoclonus 38 % Hypersomnolence 63 % Gait ataxia 63 % Psychosis (paranoid, visual hallucinations) 36 % Stroke-like episodes 27 % Thyroid status Anti-thyroid antibodies Goitre 62 % Elevated anti-TPO 100 % Subclinical hyperthyroidism 35 % Elevated anti-M 95 % Euthyroid 30 % Elevated anti-TG 73 % Overt hypothyroidism 20 % Hyperthyroidism 7 % Cerebrospinal fluid Non-specific abnormalities Elevated protein (range 33-228 mg) 78 % Elevated ANA, ESR, CRP, and liver enzymes 16 % 0-3 nucleated cells / mm3 76 % > 100 nucleated cells / mm3 4 % Oligoclonal bands 27 %

Some of the most common symptoms of Hashimoto's encephalopathy include  Concentration and memory problems Sometimes, patients are mistakenly diagnosed as having  Disorientation had a stroke, or having Alzheimer's disease. Because most  Psychosis patients respond to steroids or immunosuppressant treatment, this condition is also referred to as "steroid-  Tremors responsive" encephalopathy. In some cases, the condition  Seizures, myoclonus may also be called "non-vasculitis autoimmune  Lack of coordination meningoencephalitis" (NAIM), which can include not only  Headaches autoimmune thyroid problems, but also other autoimmune disorders such as Sjögren’s syndrome and  Partial paralysis on the right side systemic lupus erythematosus–associated  Speech problems meningoencephalitis Treatment: immunotherapy o Steroids, plasmapheresis, intravenous high-dose IgG

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Function of ENO1 A multifunctional enzyme plays a part in various processes such as growth control, hypoxia tolerance and allergic responses. This enzyme also stimulates immunoglobulin production. Moreover, it may also function in the intravascular and pericellular fibrinolytic system due to its ability to serve as a receptor and activator of plasminogen on the cell surface of several cell-types such as leukocytes and neurons.

ENO1-protein

Structure of ENO1/MBP-1 protein - N and C termini, and amino acid (aa) positions are labelled.

Expression Alpha-Enolase is widely expressed in variety of tissues including brain, thyroid, liver, kidney, spleen, as well as adipose. In comparison with gamma-type subunit found only in neurons, type alpha subunit was also detected in astrocytes, ependymal cells, capillary endothelial cells, Schwann cells and arachnoidal endothelial cells. Localisation Alpha-Enolase is most abundantly found on the cell surface and also in cytoplasm

General references (chronological listing by year of publication)

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30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Paraneoplastic neurological and muscular syndromes – please see separate compendium

Paraneoplastic neurological and muscular syndromes

Short compendium Version 4.0, September 2014

By Finn E. Somnier, M.D., D.Sc. (Med.), copyright ® Department of Clinical Biochemistry, Immunology & Genetics Statens Serum Institut, Copenhagen, Denmark

Channelopathies, receptor and solute carriers disorders in neurology, please see separate compendium Channelopathies receptor and solute carrier disorders in neurology Autoantibodies and biomarkers of neurological disorders

Version 4.0, eptember 2014

By Finn E. Somnier, M.D., D.Sc. (Med.), copyright ®

Department of Clinical Biochemistry, Immunology & Genetics Statens Serum Institut, Copenhagen, Denmark

30/01/2016, copyright, Finn E. Somnier, MD., D.S. (Med.)

Department of Clinical Biochemistry, Immunology and Genetics

STATENS SERUM INSTITUT

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