Zurich Open Repository and Archive University of Zurich Main Library Strickhofstrasse 39 CH-8057 Zurich www.zora.uzh.ch Year: 2016 T-cell brain infiltration and immature antigen-presenting cells in transgenic models of Alzheimer’s disease-like cerebral amyloidosis Ferretti, M T ; Merlini, M ; Späni, C ; Gericke, C ; Schweizer, N ; Enzmann, G ; Engelhardt, B ; Kulic, L ; Suter, T ; Nitsch, R M Abstract: Cerebral beta-amyloidosis, one of the pathological hallmarks of Alzheimer’s disease (AD), elicits a well-characterised, microglia-mediated local innate immune response. In contrast, it is not clear whether cells of the adaptive immune system, in particular T-cells, react to cerebral amyloidosis in AD. Even though parenchymal T-cells have been described in post-mortem brains of AD patients, it is not known whether infiltrating T-cells are specifically recruited to the extracellular deposits of beta-amyloid, and whether they are locally activated into proliferating, effector cells upon interaction with antigen- presenting cells (APCs). To address these issues we have analysed by confocal microscopy and flow- cytometry the localisation and activation status of both T-cells and APCs in transgenic (tg) mice models of AD-like cerebral amyloidosis. Increased numbers of infiltrating T-cells were found in amyloid-burdened brain regions of tg mice, with concomitant up-regulation of endothelial adhesion molecules ICAM-1 and VCAM-1, compared to non-tg littermates. The infiltrating T-cells in tg brains did not co-localise with amyloid plaques, produced less interferon-gamma than those in controls and did not proliferate locally. Bona-fide dendritic cells were virtually absent from the brain parenchyma of both non-tg andtgmice, and APCs from tg brains showed an immature phenotype, with accumulation of MHC-II in intracellular compartments. These results indicate that cerebral amyloidosis promotes T-cell infiltration but interferes with local antigen presentation and T-cell activation. The inability of the brain immune surveillance to orchestrate a protective immune response to amyloid-beta peptide might contribute to the accumulation of amyloid in the progression of the disease. DOI: https://doi.org/10.1016/j.bbi.2016.02.009 Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-130310 Journal Article Published Version The following work is licensed under a Creative Commons: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) License. Originally published at: Ferretti, M T; Merlini, M; Späni, C; Gericke, C; Schweizer, N; Enzmann, G; Engelhardt, B; Kulic, L; Suter, T; Nitsch, R M (2016). T-cell brain infiltration and immature antigen-presenting cells in transgenic models of Alzheimer’s disease-like cerebral amyloidosis. Brain, Behavior, and Immunity, 54:211-225. DOI: https://doi.org/10.1016/j.bbi.2016.02.009 2 Brain, Behavior, and Immunity 54 (2016) 211–225 Contents lists available at ScienceDirect Brain, Behavior, and Immunity journal homepage: www.elsevier.com/locate/ybrbi Full-length Article T-cell brain infiltration and immature antigen-presenting cells in transgenic models of Alzheimer’s disease-like cerebral amyloidosis ⇑ M.T. Ferretti a, , M. Merlini a, C. Späni a, C. Gericke a, N. Schweizer b, G. Enzmann c, B. Engelhardt c, L. Kulic a, T. Suter b, R.M. Nitsch a a Institute for Regenerative Medicine (IREM), University of Zurich, Schlieren, Wagistrasse 12, 8952, Switzerland b Neurology, Neuroimmunology and Multiple Sclerosis Research, University Hospital Zurich, Sternwartstrasse 14, 8006 Zurich, Switzerland c Theodor Kocher Institute, University of Bern, Freiestrasse 1, 3012 Bern, Switzerland article info abstract Article history: Cerebral beta-amyloidosis, one of the pathological hallmarks of Alzheimer’s disease (AD), elicits a well- Received 2 December 2015 characterised, microglia-mediated local innate immune response. In contrast, it is not clear whether cells Received in revised form 26 January 2016 of the adaptive immune system, in particular T-cells, react to cerebral amyloidosis in AD. Even though Accepted 9 February 2016 parenchymal T-cells have been described in post-mortem brains of AD patients, it is not known whether Available online 9 February 2016 infiltrating T-cells are specifically recruited to the extracellular deposits of beta-amyloid, and whether they are locally activated into proliferating, effector cells upon interaction with antigen-presenting cells Keywords: (APCs). To address these issues we have analysed by confocal microscopy and flow-cytometry the local- Alzheimer’s disease isation and activation status of both T-cells and APCs in transgenic (tg) mice models of AD-like cerebral Amyloid-beta peptide MHC-II amyloidosis. Increased numbers of infiltrating T-cells were found in amyloid-burdened brain regions of tg T-cell mice, with concomitant up-regulation of endothelial adhesion molecules ICAM-1 and VCAM-1, compared Interferon gamma to non-tg littermates. The infiltrating T-cells in tg brains did not co-localise with amyloid plaques, pro- duced less interferon-gamma than those in controls and did not proliferate locally. Bona-fide dendritic cells were virtually absent from the brain parenchyma of both non-tg and tg mice, and APCs from tg brains showed an immature phenotype, with accumulation of MHC-II in intracellular compartments. These results indicate that cerebral amyloidosis promotes T-cell infiltration but interferes with local anti- gen presentation and T-cell activation. The inability of the brain immune surveillance to orchestrate a protective immune response to amyloid-beta peptide might contribute to the accumulation of amyloid in the progression of the disease. Ó 2016 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). 1. Introduction cells and mature APCs found in the perivascular and meningeal spaces, and at the blood–cerebrospinal fluid (CSF) barrier of the T-cells constantly patrol body tissues as part of the physiologi- choroid plexus (CP) (Ransohoff et al., 2003; Ousman and Kubes, cal process of immune surveillance (von Andrian and Mackay, 2012). 2000). Upon recognition of their cognate antigen exposed on In contrast to CSF-associated patrolling T-cells, T-cells retained mature antigen-presenting cells (APCs), T-cells undergo activation, in the brain parenchyma often reflect an on-going pathology. In proliferate and exert effector functions, such as cytotoxicity in the autoimmune conditions such as multiple sclerosis, autoreactive case of CD8+ T-cells and activation of macrophages and antibody- T-cells play a causative role in fostering macrophage-mediated producing B cells in the case of CD4+ T-helper cells. In the CNS, demyelination (Ciccarelli et al., 2014). In Alzheimer’s disease physiological immune surveillance is mediated by patrolling T- (AD)-related neurodegeneration, characterised by the accumula- tion of intracellular aggregates of abnormally phosphorylated tau and extracellular deposition of aggregated amyloid-beta peptide Abbreviations: AD, Alzheimer’s disease; Ab, amyloid-beta peptide; APCs, (Ab)(Selkoe, 2011), the role of the immune system is less well antigen-presenting cells; CAA, cerebral amyloid angiopathy; CP, choroid plexus; CSF, cerebrospinal fluid; DCs, dendritic cells; FI, fluorescence intensity; IFN-c, understood (Town, 2010). + interferon gamma; MHC-I, MHC-II, major histocompatibility class I and II; tg, While several studies have demonstrated the presence of CD4 transgenic. and CD8+ T-cells in post-mortem brains of AD patients (Rogers et al., ⇑ Corresponding author. 1988; Togo et al., 2002; Itagaki et al., 1988), their significance is a E-mail address: [email protected] (M.T. Ferretti). http://dx.doi.org/10.1016/j.bbi.2016.02.009 0889-1591/Ó 2016 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). 212 M.T. Ferretti et al. / Brain, Behavior, and Immunity 54 (2016) 211–225 matter of debate. It is not clear whether T-cells are specifically 100 lg/ml collagenase–dispase and 50 lg/ml DNaseI for 20 min recruited to amyloid deposits in AD brains, and very little is known at RT, passed through a 100 lm Nylon mesh, processed with ACK on their activation status. Activated IFN-c producing-T-cells could lysis buffer, washed in HBSS and used for staining. Surface staining promote macrophage and microglia receptor-mediated phagocyto- – CNS-mononuclear cells and splenocytes were washed in FACS sis (Schroder et al., 2004), thus supporting beneficial clearance of buffer (HBSS, 2% FCS, 10 mM EDTA, 0.01% NaN3). After treatment extracellular amyloid. On the other hand, overt T-cell activation with an antibody against Fc receptor (anti-mouse CD16/32, TrueS- could result in direct cytotoxicity and macrophage-mediated tissue tain FcX TM, BioLegend, san Diego, CA, USA), the cells were stained damage, thereby contributing to neuronal demise (Aloisi et al., for 15 min at 4 °C with specific antibodies, washed and analysed. 2000b). Hence, the activation state of the infiltrating T-cells might Intracellular staining – Intracellular stainings were performed with be disease-relevant. the eBioscience kit (n.72-5775, San Diego, CA, USA) according to To elucidate this issue we have analysed T-cell numbers, local- manufacturer’s instructions. DC panels – In each experiment we isation and phenotype in transgenic (tg) mouse models of AD-like included at least eight non-tg and eight tg mice. For the ArcAb cerebral amyloidosis. We show that cerebral amyloidosis is associ- 24-month-old experiment, a total of nine non-tg and ten ArcAb ated with brain infiltration of T-cells, which do not co-localise with APP-tg animal were used; we analysed the cerebrum from nine amyloid deposits, do not proliferate locally and display low expres- tg and seven non-tg mice. Choroid plexuses were removed from sion of the effector cytokine IFN-c. nine non-tg and ten tg animals.