JOURNAL OF & RESEARCH REVIEWS Volume 30, Number 12, 2010 ª Mary Ann Liebert, Inc. DOI: 10.1089/jir.2010.0035

Targeting the Subunit to Control Pain and Inflammation

Jalal A. Jazayeri,1 Aradhana Upadhyay,1 Ann B. Vernallis,2 and Graeme J. Carroll 3

The glycoprotein 130 (gp130) is a shared signal-transducing-membrane-associated receptor for several hema- topoietic . Its activation is implicated in pain and in a variety of diseases via signaling of proin- flammatory cytokines. These include -6 (IL-6) subfamily cytokines, many of which play important roles in the pathogenesis of diseases such as rheumatoid arthritis, Castleman’s disease, and Kaposi’s sarcoma. Several strategies have been developed to block gp130-receptor-mediated signaling. These include the appli- cation of monoclonal , the creation of mutant form(s) of the gp130 with increased binding affinity for such ligands as IL-6/sIL-6R complex, and the generation of antagonists by selective mutagenesis of the specific cytokine/gp130 receptor binding site(s). Other strategies include targeting gp130-mediated signaling pathways such as that involving signal transducer and activator of transcription-3. This review provides a summary of the latest research pertaining to the role of gp130 in the pathogenesis of inflammatory and other diseases in which the gp130 receptor is implicated. An overview of antagonists targeting the gp130 receptor is included with particular emphasis on their mechanism of action and their limitations and potential for therapeutic application.

Introduction dratsch and others 2009). Andratsch and others (2009) found that gp130 expression on the membrane of nociceptive pri- lycoprotein 130 receptor (also known as gp130) is mary afferent nerves is required for the development of Ga transmembrane that can transduce signals pathological pain and hyperalgesia in inflammatory condi- from many different ligands that have diverse biological tions and cancers. They showed that cytokines contribute to functions. These include cytokines such as interleukin-6 pain hypersensitivity via the gp130-Gab1/Gab2-PI3K-PKC- (IL-6, 26 kDa), leukemia inhibitory factor (LIF, 23 kDa), d-TRPV1 pathway in peripheral sensory neurons. Importantly, (OSM, 28 kDa), ciliary neurotrophic factor IL-6 was shown to play a major part in the activation of this (CNTF, 24 kDa), IL-11, (23 kDa), Cardiotrophin-like cytokine pathway. (22.5 kDa), cardiotrophin-1 (21.5 kDa), and IL-27 (26.6 kDa) Accordingly, strategies to counteract the action of gp130, (Kishimoto and others 1995). Binding of IL-6 to its receptor by targeting gp130 itself, its ligands, or the genes or (IL-6R) induces the homodimerization of gp130, which associated with its pathway, have be- in turn results in the activation of Janus kinases (JAKs). come an important focus of research, both from an im- of gp130 activates protein munopharmacological standpoint and also in the quest for phosphatase-2 (SHP-2) and signal transducer and activator development of pharmaceuticals to control pain and in- of transcription-3 (STAT-3) among other pathways. flammation. Gp130 activation is implicated in a variety of diseases. In particular, the recognition of shared molecular subunits These include rheumatoid arthritis (RA), Castleman’s dis- (gp130) in the receptors for IL-6 cytokines has made it pos- ease, Crohn’s disease, multiple myeloma, psoriasis, amyo- sible to use components of these receptors, either alone or in trophic lateral sclerosis, several cancers, diabetes, asthma, combination, as antagonists or as research tools. Most of the and obesity (Table 1). Further, gp130 has also been shown to antagonists targeting IL-6 family cytokines, which have been amplify pain, not only indirectly via the induction of proin- developed so far, are based on the shared use of the gp130 flammatory cytokines, but also through a direct action on receptor system. One approach has been to block the for- neurons in response to painful stimuli (nociceptors) (An- mation of IL-6/IL-6R/gp130. This strategy has been used to

1Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), Melbourne, Australia. 2School of Life and Health Sciences, Aston University Birmingham, Birmingham, United Kingdom. 3Department of Rheumatology, Fremantle Hospital, University of Notre Dame, Australia (Fremantle) and University of Western Australia, Fremantle Hospital, Perth, Western Australia.

865 866 JAZAYERI ET AL.

Table 1. Glycoprotein 130 Cytokine Binding Sites

IL-6 IL-11 LIF OSM CNTF

Site 1 IL-6Ra IL-11Ra – – CNTFR Site 2 gp130 gp130 gp130 gp130 gp130 Site 3 gp130 gp130 LIF-R LIF-R/OSM-R LIF-R

IL, interleukin; LIF, leukemia inhibitory factor; OSM, oncostatin M; CNTF, ciliary neurotrophic factor; gp130, glycoprotein 130. improve the symptoms in patients with RA, multiple mye- and gastrointestinal ulceration. Such studies highlight the loma, and Castleman’s disease (Rebouissou and others 1998; potential importance of defects in gp130 signaling in the Nishimoto and others 2000). pathogenesis of arthritis. Interestingly, capsaicin, the pungent ingredient of hot peppers, has been found to inhibit the IL-6/STAT-3 pathway Gp130R and IL-6 subfamily cytokines by depleting intracellular gp130 pools through endoplasmic reticulum stress (Lee and others 2009) Other antagonists that The binding of cytokine(s) to gp130 receptor takes place at include those targeting the IL-6/gp130 complex have now different sites (Table 1). In general, the IL-6 subfamily cyto- been approved by the FDA for patients who have failed anti- kines share and activate the gp130 receptor in different ways. (TNF) therapy (Emery and others 2008; In one scenario the cytokine binds to its own specific receptor Genovese and others 2008). Examples include , with high affinity before heterodimerization with gp130. For which is a humanized monoclonal (mAb) with example, LIF binds to LIF-R and LIF-R/gp130 hetero- specificity for IL-6R. Its therapeutic efficacy in RA has been dimerizes (Hudson and others 1996), and in the other, the extensively tested and proven in clinical trials (Nishimoto cytokine binds to gp130 receptor with high affinity after it and others 2004). In addition, ALD518, which is a human- has first bound to another receptor; eg, IL-6 first binds to ized mAb directed against IL-6, has progressed to a phase II either membrane-bound IL-6R or soluble (circulating free) clinical trial for advanced cancer and to a phase IIa study for IL-6R (sIL-6R) and the complex then binds gp130 with high RA (Clarke and others 2009). affinity causing it to homodimerize. Similarly IL-11 binds to sIL-11R. CNTF, in addition to binding to LIF-R, binds sCNTF Gp130 Receptor (Taga and others 1989) (Fig. 1).

Gp130 receptor is a transmembrane protein, so called be- Methods Used to Block Gp130 Signaling cause of its molecular weight of 130 kDa. It is expressed widely in different organs, including brain, lung, , A number of strategies have been developed to block the , heart, kidney, and placenta (Hibi and others 1990). gp130 activation, stimulated by the IL-6 subfamily cytokines. Signals from IL-6 subfamily members (IL-6, IL-11, LIF, and These are detailed below. OSM) depend on gp130 (Ohtani and others 2000). While IL-6 and IL-11 binding leads to homodimerization of gp130, LIF- Monoclonal antibodies R and OSM-R heterodimerizes with gp130, forming gp130/ mAbs directed against gp130 have been shown to inhibit LIF-R or gp130/OSM-R, which in turn leads to signal the biological activities of those cytokines that use gp130 transduction (Fig. 1). receptor systems, eg, IL-6 subfamily cytokines. Gu and oth- Gp130 is a member of the cytokine-receptor superfamily. It is ers (1996), for example, used human plasmacytoma cells, an envisaged to consist of 6 parts in its extracellular domain, IL-6 subfamily cytokine-dependent cell line, and generated numbered from distal to membrane-proximal—D1–D6. The anti-gp130 mAbs that specifically inhibited CNTF, but second and third parts comprise the cytokine-binding compo- without affecting the biological activity of the other members nent highlighted by 4 conserved cysteines and a WSXWS motif of the IL-6 cytokine subfamily. Such antibodies, some of (Pflanz and others 2000). Gp130 itself has no intrinsic tyrosine which are patented, have applications not only as research kinase activity, but it is phosphorylated on tyrosine residues tools, to design anti-IL-6 cytokine inhibitors, but also in after complex formation with any of the IL-6 subfamily cyto- medicinal products and diagnostic reagents. kines. This leads to its association with JAK/Tyk tyrosine ki- nases and STAT protein transcription factors, specifically Soluble forms of gp130 STAT-3, which when phosphorylated leads to the activation of a number of downstream genes (Heinrich and others 1998). As a means of blocking IL-6/gp130 activation, Jostock and Mutational analysis has shed some on the role of others (1999) created recombinant soluble forms of gp130 gp130. Homozygous mice deficient in gp130 activation (sgp130) proteins that were capable of binding to IL-6, in have shown many defects such as impaired develop- complex with sIL-6R, and blocked IL-6/sIL-6R-induced ment of the ventricular myocardium. Ernst and colleagues proliferation of gp130-expressing BAF/3 cells in vitro (at (Ernst and others 2001) generated gp130 knock-in mice concentrations ranging from 10 to 100 ng/mL). Further, they (gp130DSTAT/DSTAT), in which all STAT-binding sites were showed that sgp130 partly inhibited LIF- and OSM-induced deleted from the gene encoding gp130, but the binding sites proliferation when used at higher concentrations (1,000 ng/ for both JAKs and protein tyrosine phosphatase-2 (SHP-2) mL). However, due to the bipartite nature of IL-6Ra, block- were preserved. They found that this mutant mouse devel- ing IL-6 action using soluble receptors has, in general, been oped severe joint disease with features strongly resembling very challenging. This is because IL-6 alone does not bind to those found in RA, as well as a blastocyst implantation defect gp130, but it must first bind sIL-6Ra before it can be neu- GP130 AND ITS ANTAGONISTS 867

FIG. 1. Gp130 signaling pathways. Gp130 receptor essentially signals through JAK/STAT and/or MAPK transduction pathways. The cytoplasmic component of gp130 is noncovalently associated with JAK molecules, which become activated upon binding. The JAKs then phosphorylate the specific receptors and gp130 on certain highly conserved tyrosine residues in the membrane-distal cytoplasmic part, which in turn binds to adaptor protein molecules containing an Src- homology-2 (SH2). Depending on the tyrosine residue activated, the adaptor molecules can either be of the signal trans- ducers of transcription (STAT) family triggering the JAK/STAT signaling pathway or SHP-2 (SH2 domain containing tyrosine phosphatase, binding to Tyr759 of gp130 and Tyr974 of LIF-R) and Shc (SH2 and collagen homology domain containing protein, binding to the Tyr861 of OSM-R), which are found to be crucial for the activation of the Ras/Raf/MAPK pathway. In the JAK/STAT signaling pathway, the phosphotyrosine–SH2 interaction paves the way for subsequent tyrosine- phosphorylation and homo/hetero-dimerization of the STAT molecules. Dimerized STATs are then translocated to the nucleus where they initiate relevant gene transcription and subsequent translation. Gp130, glycoprotein 130; JAK, ; STAT, signal transducer and activator of transcription; MAPK, mitogen-activated protein kinase. tralized by sgp130. The gp130/sIL-6Ra complex thus formed which the release of sIL-6R by one cell type renders other can neutralize the agonistic complex of IL-6/sIL-6Ra. For cells that only express gp130 responsive to IL-6, Rabe and this reason Jostock and others created a recombinant sgp130 others (2008) generated transgenic mice that overexpress that was capable of specifically blocking IL-6 responses de- sgp130. They showed that sgp130 specifically blocks all IL-6 pendent on sIL-6Ra, whereas membrane-bound IL-6R re- responses mediated by the soluble IL-6R but that it does not mained unaffected. affect IL-6 responses via the membrane-bound IL-6R. sgp130 Muller-Newen and others (1998) showed that when cells has also been detected in human serum at high concentra- lacking membrane-bound IL-6R were stimulated with IL-6/ tions (in the order of *200 ng/mL) and has been correlated sIL-6R complexes, sgp130 was a more effective antagonist with blood pressure in stroke patients (Inta and others 2009). than on IL-6R-positive cells stimulated with IL-6 alone. This Sgp130 mutants. To generate sgp130 mutant proteins is not surprising given the low affinity of gp130 for IL-6 in (muteins), Tenhumberg and others (2008) analyzed the 3- the absence of IL-6R. They also argued that the sIL-6R, found dimensional structure of gp130 complexed with IL-6/sIL-6R in human plasma, could well be regarded as an antagonistic and identified specific side chains in gp130 that molecule that would possibly enhance the inhibitory activity interact with sIL-6R. These were then used as targets to of sgp130. To block IL-6 trans-signaling in vivo, a scenario in produce mutants with increased binding affinity for the 868 JAZAYERI ET AL.

IL-6/sIL-6R complex. The mutants generated were tested for avidity for multivalent ligands due to the resulting bivalency binding to the IL-6/sIL-6R complex as well as for inhibition of dimeric fusion proteins. of IL-6/sIL-6R-induced cell proliferation. Several mutants The sgp130:Fc thus constructed was found to be 10 times demonstrated marked increases in binding affinity of human more active compared to monomeric sgp130. In addition, the sgp130 toward human IL-6/sIL-6R. In addition, some mu- dimerized soluble form of sgp130 was shown to suppress the tations showed an additive effect, improving the binding action of the soluble IL-6/IL-6R complex in vitro and in vivo affinity of human sgp130, and its more stable Fc fusion (Jostock and others 2001a) without affecting the activity of counterpart sgp130:Fc, toward IL-6/sIL-6R. They also showed the membrane-bound IL-6R. Jostock and others (2001b) that one mutated form of sgp130:Fc, with 3 amino acid sub- constructed an sgp130 his, by replacing the Fc portion in the stitutions very effectively blocked IL-6/sIL-6R-mediated bio- sgp130:Fc with 6 histidine residues; however, this construct logical responses both in vitro and in vivo (using an animal was not as potent as sgp130:Fc. One possible reason for this model of arthritis driven by IL-6/IL-6R). The effect of sgp130 lack of potency is its monomeric structure. Recently, mutated muteins on membrane-bound IL-6R was not examined in this forms of sgp130:Fc have been generated and shown to have study. Examples of glycoprotein 130 derivatives and their higher potencies for blocking biological responses mediated cytokine specificity and pharmacological attributes are shown by IL-6/sIL-6R complex in vitro and in vivo (Tenhumberg in Table 2. and others 2008). Sgp130:Fc and sgp130his. To increase its potency, sgp130 Fusion of Sgp130 sIL-6R. Recognition of the important role has been fused with the Fc portion of human IgG1 creating of sIL-6R together with sgp130 led to the idea of construction sgp130:Fc. Fusion constructs of this type are commonly cre- of an sIL-6R and sgp130 fusion complex. This was constructed ated to enhance the serum half-life of therapeutic molecules mainly because, in cells expressing membrane-bound IL-6R, because the Fc protein is expressed as a disulphide-linked when treated with IL-6 alone, sgp130 was found to be a weak dimer (Jazayeri and Carroll 2008). In general, cytokines, in antagonist and sgp130 alone was inadequate to inhibit the IL- their monomeric form, have relatively small molecular size 6 response. To overcome this, Ancey and others (2003) fused and short serum half-lives (5–50 min), and are not only the 2 receptor subunit fragments creating an sIL-6R/sgp130 rapidly cleared from the kidneys but also subject to degra- fusion complex. To achieve this, the ligand-binding domains dation by proteolytic enzymes. This necessitates frequent of sgp130 (D1-D2-D3) and sIL-6R (D2-D3) were connected administration and thus limits their clinical utility. In addi- using 3 different linkers. Biological activity assays showed tion, since there is an inverse relationship between the size of that the construct was capable of inhibiting IL-6 activity. It these molecules and the rate at which they diffuse through abrogated IL-6-induced phosphorylation of STAT-3, and in- mucus, Fc fusion constructs potentially have a lower rate of hibited the proliferation of transfected Ba/F3 cells expressing

diffusion. Further, such constructs can also increase the gp130 and IL-6R. These investigations also showed that the

Table 2. Glycoprotein 130 Derivatives, Their Cytokine Specificity and Pharmacological Attributes

Antagonist Specificity Reference sgp130 In its recombinant form, sgp130 is shown to Narazaki and others (1993); Jostock and block sIL-6R trans-signaling others (2001a) sgp130/sIL-6R A fusion of the sgp130 and sIL-6Ra ligand- Ancey and others (2003) binding domains to bind to IL-6 Sgp130 Sgp130:Fc Fusion of sgp130 with the Fc portion of Jostock and others (2001a); Jazayeri and human IgG. Created to enhance the serum Carroll (2008) half-life of therapeutic molecules PEG-sgp130-dimers Fusion of sgp130 with PEG. The potency of Patent this construct is reported to be *2-fold higher than that of the sgp130:Fc Gp130-RAPS The gp130 of the RA antigenic -bear- Inta and others (2009) ing soluble form (gp130-RAPS). It has also been isolated as a disease-associated auto- antigen in RA. Gp130-ELP A biologically active form of sgp130 variant Tenhumberg and others (2008) produced in transgenic tobacco plants as an ELP-fusion protein. This construct con- sists of the first 3 domains of gp130 fused to 100 repeats of ELP Gp130 anti-sense GP130-specific anti-sense oligonucleotides Varga and others (2001) oligonucleotides that inhibit anti-sense IL-6 signal Gp130Dcyt Acts as a dominant-negative protein that Selander and others (2004) inhibits constitutive STAT-3 activation in breast cancer cells in which both gp130 and epidermal receptor have been implicated

sgp130, soluble form of gp130; gp130, glycoprotein 130; IL, interleukin; RA, rheumatoid arthritis; PEG, polyethylene glycol; ELP, elastin- like peptide; STAT, signal transducer and activator of transcription. GP130 AND ITS ANTAGONISTS 869 construct was much more effective than the separately ex- proach is the possibility that such mutants may be anti- pressed soluble receptor proteins. genic and provoke the elaboration of neutralizing Polyethylene glycolylated sgp130-dimers. To increase the antibodies that may in turn limit or completely abrogate serum half-life of sgp130 even further, the molecule was efficacy or cause other toxicity. polyethylene glycol(PEG)ylated creating sgp130:PEG (patent Creation of mutations in the gp130 cytokines that increase application). The potency of this construct was found to be their affinities for the gp130 receptor. This is the opposite *2-fold higher than that of the sgp130:Fc molecule. Further, of the strategy outlined above. Examples of this approach it was postulated that the same results, as those achieved include (i) the creation of a mutant form of human LIF that with sgp130:Fc, would be possible with a lower dose of binds to human LIF-R with over 1,000-fold higher affinity sgp130:PEG. This construct has several advantages, which than wild-type human LIF, but that does not bind gp130 as include lower drug exposure for the patient, reduced appli- required for productive signaling, thereby blocking LIF- cation frequency, and lower therapeutic costs. induced gp130 activation and (ii) the creation of IL-6 mu- tant antagonists with enhanced affinity for gp130 (Savino Gp130-RAPS and others 1994; Fischer and others 1997). Exchanging biological specificities within the cytokine Gp130 of the RA antigenic peptide-bearing soluble form family. In yet another approach, the site III epitope of IL-6 (gp130-RAPS) has been isolated as a disease-associated auto- was exchanged with its CNTF counterpart. This hybrid antigen in RA. This soluble truncated form of gp130 has a molecule acquired a requirement for LIF-R to activate unique sequence and has been identified as an auto-antigen in signaling (Grotzinger and others 1999). RA (Tanaka and others 2000). Antibodies against gp130-RAPS have been shown to neutralize gp130-RAPS activity. Gp130- Antagonists targeting STAT-3 signaling RAPS have also been shown to inhibit IL-6 activity and to be neutralized by anti-gp130-RAPS antibodies derived from pa- As outlined earlier, gp130 receptor essentially signals tients with RA. In addition, the concentrations of these anti- through JAK/STAT and/or mitogen-activated protein kinase bodies in the serum of RA patients have been found to correlate transduction pathways (Fig. 1). Such pathways have also been positively with (i) serum C-reactive protein concentrations, (ii) targeted to inhibit gp130 signaling. For example, in a study erythrocyte sedimentation rate, (iii) platelet counts, and (iv) conducted by Sobota and others (2000), it has been shown that serum IL-6 concentrations. Thus, it is hypothesized that auto- parthenolide, a sesquiterpene lactone found in many medici- antibodies to gp130-RAPS could play an important role in the nal plants, inhibits IL-6-type cytokine-induced gene expres- pathogenesis of RA by stimulating IL-6 activity. Further, it is sion by blocking STAT-3 phosphorylation on Tyr705. They possible that auto-antibodies to gp130-RAPS may become showed that parthenolide prevents STAT-3 dimerization, clinically useful as a marker for disease activity in RA. which is required for its nuclear translocation and gene ex- pression. In addition, based on the fact that prostate cancer Gp130-elastin-like peptide cells have high levels of IL-6 (82% of prostate cancer patients), inhibition of STAT-3 may have therapeutic potential in Lin and others (2006) constructed a biologically active patients with prostate cancer (Weerasinghe and others 2008). form of sgp130 variant that was produced in transgenic to- IL-6 also activates androgen-receptor-dependent gene ex- bacco plants as an elastin-like peptide (ELP) fusion protein. pression in prostate cancer cells in the absence of androgen. The construct consisted of the first 3 domains of gp130 fused Although the role of STAT-3 in prostate cancer is not clearly to 100 repeats of ELP. Expression of mini-gp130-ELP did not established, activated STAT-3 is considered to be an important affect the growth rate or morphology of the transgenic signaling molecule that plays a critical role in progression of plants, and purification was achieved using inverse transi- both androgen-dependent and androgen-independent pros- tion cycling. With this approach Lin and others (2006) pro- tate cancers (Nishimoto and Kishimoto 2008). Lee and others m duced 141 g of purified protein per gram of fresh leaf (2004) have used siRNA specific for STAT-3 and showed that weight. The purified protein inhibited sIL-6R-mediated inhibition of STAT-3 activation suppressed the growth of trans-signaling as demonstrated by 3 features: (i) bind to the human prostate cancer cells and STAT-3-mediated gene ex- IL-6–sIL-6R complex, (ii) its inhibition of proliferation in pression, which also induced apoptotic cell death. human hepatoma cells and murine pre-B-cells, and (iii) by its Further, it has been shown that G-quartet oligonucleotide, capacity to block sIL-6R-mediated activation of STAT-3 T40214, is a potent inhibitor of STAT-3 binding to DNA. At phosphorylation. present, variations of this compound are being tested to determine if human tumors in nude mice are suppressed. Cytokine-based antagonists targeting gp130 The goal is to use such a compound to treat patients with metastatic prostate cancer. In addition, in a study conducted In addition to the application of mAb against sgp130, by Selander and others (2004), using an orthotopic nude other approaches to blocking gp130 activation have been mouse model, it was shown that inhibition of gp130 signal- investigated and developed. These include ing in breast cancer blocks constitutive activation of STAT-3 Creation of mutations in the gp130-dependent cytokines and inhibits the development of malignancy. that render them defective in respect to their capacity to Targeting STAT-3 blockade with gene therapy. Several gene- bind specific sites within the gp130 receptor. For example, therapy-based approaches have also been taken toward ac- LIF mutants have been generated that can still bind to LIF- tivating/de-activating STAT-3-mediated signaling and R with high affinity, but that lack the ability to efficiently thereby regulating gp130-associated signal transduction. Yu bind to gp130 and in turn initiate its activation (Vernallis and others in 2009 patented many gene-delivery-based and others 1997). One potential disadvantage of this ap- therapeutic strategies that have potential for prevention or 870 JAZAYERI ET AL.

Table 3. Diseases Associated with Glycoprotein 130 and Its Associated Ligands

Disease Etiology Target/therapy Ref

Rheumatoid arthritis Elevated levels of IL-6 subfamily Tocilizumab and ALD518, Nishimoto and others (2004); cytokines are detected in the both humanized anti- Yokota and others (2008) synovial fluids of RA patients, human IL-6R mAb all sharing gp130 Castleman’s disease Excess amount of IL-6 Anti IL-6Ra therapy and m produced in hyperplastic anti IL-6 mAb lymph nodes Multiple myeloma (MM) IL-6 induces proliferation of Biochemical mediators of Rebouissou and others (1998) MM cells through different IL-6 induce signaling signaling pathways. pathways such as MAPK, JAK1/STAT-3, and JAK2/ STAT-3. Cardiac myxoma Elevated serum levels of IL-6 IL-6, IL-11, anti IL-6Ra Mochizuki and others (1998) are associated with cardiac myxomas, and have a direct correlation with the primary tumor size. Crohn’s diseases Mediated by an inappropriate Anti IL-6Ra, anti-IL-6, anti- Auernhammer and others response to resident microbes, gp130, and IL-11 mAbs (2005) leading to excessive release of IL-1b, TNF-a, IL-23, and IL-6 Psoriasis Increased LIF and OSM OSM and IL-11 Goodman and others (2009) production in short-term organ cultures of lesional skin. Also, T cells derived from both lesional psoriatic and atopic dermatitis skin samples secrete high levels of OSM. Asthma Increased secretion of IL-6 IL-6 and IL-11 Doganci and others (2005) from alveolar macrophages of asthmatic patients after an allergic attack.IL-11 induces nonspecific bronchial hyperresponsiveness in mice and leads to a T cell inflammatory response with local accumulation of fibroblasts and airways obstruction. Amyotrophic lateral Serum level of CNTF is Anti-LIF, and CNTF Laaksovirta and others (2008) sclerosis elevated in patients with amyotrophic lateral sclerosis and correlates with the site of disease onset. Peripheral sensory Gp130 is expressed in peripheral Anti-gp130 Andratsch and others (2009) nerves pain sensing neurons in the pathophysiology of major clinical pain disorders. It may enhance pain through a direct action on nociceptors. AIDS-associated The soluble form of the IL-6 Blocking signaling through Borsellino and others (1999) Kaposi Sarcoma receptor (sIL-6R_) is a potent the gp130-R chain by IL-6 growth factor for AIDS- and OSM associated Kaposi’s sarcoma (KS) cells. The sgp130 is an antagonist for sIL-6R_-induced AIDS-KS cell growth. Diabetes IL-6 affects glucose homeostasis IL-6 Kristiansen and Mandrup- and metabolism directly and Poulsen (2005) indirectly by action on skeletal muscle cells, adipocytes, hepatocytes, pancreatic b-cells, and neuroendocrine cells. (continued) GP130 AND ITS ANTAGONISTS 871

Table 3. (Continued)

Disease Etiology Target/therapy Ref

Atherosclerosis IL-6 is produced in atheroscle- IL-6 and IL-11 Dubinski and Zdrojewicz rotic lesions in humans, hy- (2007) percholesterolemic rabbits, and apoE-deficient mice. IL-11 has been found to induce a shift change from a Th1 to a Th2 phenotype of CD4þ lympho- cytes, thereby providing scope for an immunomodulatory treatment. Prostate cancer Serum levels of IL-6 correlate IL-6 Smith and others (2001) with prostate tumor burden and patient morbidity. IL-6 and IL-6 receptor are also ex- pressed in prostate carcinoma and activate the androgen re- ceptor (AR). Systemic lupus IL-6 levels are elevated in both Anti-IL-6R mAb Tackey and others (2004) Erythematosus human and murine lupus, and blocking IL-6 or its receptor has been shown to have a beneficial effect in all models of lupus tested to date. Recent studies also demonstrate the clinical efficacy of Tocilizumab in SLE. Obesity IL-6 family member, CNTF, acts CNTF acts as an anti-obeso- Febbraio (2007) both centrally and peripherally genic and -sensitiz- and mimics the biologic ac- ing agent. tions of the appetite control hormone , but unlike leptin, CNTF appears to be effective in obesity and as such may have therapeutic potential, Postmenopausal IL-6 levels increase due to estro- IL-6 Nonpeptide antagonist to osteoporosis gen deficiency during and after gp130 selectively inhibits menopause, which stimulates gp130. osteoclastogenesis. It has also been shown that IL-6 knockout mice do not exhibit bone loss after ovariectomy.

IL, interleukin; RA, rheumatoid arthritis; gp130, glycoprotein 130; TNF, tumor necrosis factor; JAK, Janus kinase; STAT, signal transducer and activator of transcription; LIF, leukemia inhibitory factor; OSM, oncostatin M; CNTF, ciliary neurotrophic factor; mAb, monoclonal antibody; MAPK, mitogen-activated protein kinase. treatment in ischemic disorders, proliferative angiopathies IL-6 blockade, for which some antagonists have been de- with neovascularization, such as diabetic microangiopathy, veloped, could also be applicable in this respect. The logic to and for regulating immune responses before the advent of inhibiting gp130 is that it will inhibit signaling dependent on any disease. all cytokines using the pathway. This may be beneficial in systems in which multiple ligands are present, eg, in RA in Applications and Conclusions which IL-6, LIF, and OSM play a main role in the disease pathogenesis. The potential for targeting gp130 to favorably influence Treatment strategies for targeting gp130 include the use the activity and course of diseases in which the gp130 sig- of mAbs, sgp130, and cytokine-based receptor antagonists naling system is implicated is summarized in Table 3. Tar- against cytokines sharing gp130 and compounds targeting IL- geting either gp130 itself or cytokines that depend on it for 6. Some of these are in advanced stages of development, but signaling, such as the IL-6 subfamily cytokines, constitutes a no gp130 inhibitor is ready yet for clinical application. One novel class of anti-inflammatory and anti-neoplastic drugs. reason for this is that there are still concerns about safety. Further, recent studies demonstrating the role of gp130 in Blocking transmembrane receptors such as gp130, without sensory neuron function has opened up new possibilities for affecting innate or acquired immune responses, remains a novel therapeutics that may be useful in pain management. complex and challenging task. These and other safety issues 872 JAZAYERI ET AL. will need to be carefully considered before gp130 antago- tients with advanced cancer. J Clin Oncol (Meeting Abstracts) nists can be used in clinical practice. If, however, the aim of 27(15S):3025. anti-gp130 therapy is only to attenuate signaling, there may be Doganci A, Sauer K, Karwot R, Finotto S. 2005. Pathological role a therapeutic window. Here it will be important to monitor of IL-6 in the experimental allergic bronchial asthma in mice. residual gp130 signaling in a variety of tissues. Clin Rev Allergy Immunol 28(3):257–270. There are numerous studies of tissue-specific gp130/ Dubinski A, Zdrojewicz Z. 2007. [The role of interleukin-6 in mice that demonstrate that a complete lack of gp130 com- development and progression of atherosclerosis]. Pol Merkur promises the animal’s response to injury (gut, cardiac, neu- Lekarski 22(130):291–294. ronal, and immune) (Ernst and others 2001). Given the Emery P, Keystone E, Tony HP, Cantagrel A, van Vollenhoven implicit role of the IL-6 cytokine subfamily in the innate R, Sanchez A, Alecock E, Lee J, Kremer J. 2008. IL-6 receptor inhibition with tocilizumab improves treatment outcomes in , the possibility of facilitating infections, patients with rheumatoid arthritis refractory to anti-TNF bi- provoking autoimmune phenomena, and compromising ologics: results from a 24-week multicentre randomised pla- immune surveillance all need to be considered. Whether cebo controlled trial. Ann Rheum Dis 67(11):1516–1523. granulomas may be destabilized by gp130 signal blockade is Ernst M, Inglese M, Waring P, Campbell I, Bao S, Clay F, unclear, but this would need to be kept in mind in view of Alexander W, Wicks I, Tarlinton D, Novak U, Heath J, Dunn the experience with TNF antagonists, where treatment has A. 2001. Defective gp130-mediated signal transducer and ac- resulted in the reactivation of latent tuberculosis as a con- tivator of transcription (STAT) signaling results in degenera- sequence thereof. Autoimmune disorders, including lupus tive joint disease, gastrointestinal ulceration, and failure of and psoriasis, may be promoted, and skin, lymphoid, other uterine implantation. J Exp Med 194(2):189–203. bone marrow lineage, or solid organ malignancies may be Febbraio MA. 2007. gp130 receptor ligands as potential thera- induced or accelerated. Further, there will be a need for peutic targets for obesity. 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