The Journal of Immunology Elevation of Sema4A Implicates Th Cell Skewing and the Efficacy of IFN-b Therapy in Multiple Sclerosis Yuji Nakatsuji,* ,1 Tatsusada Okuno,* ,†,1 Masayuki Moriya,* Tomoyuki Sugimoto, ‡ Makoto Kinoshita,* Hyota Takamatsu, † Satoshi Nojima, † Tetsuya Kimura, † Sujin Kang, † Daisuke Ito, † Yukinobu Nakagawa, † Toshihiko Toyofuku, † Kazushiro Takata,* Misa Nakano, x Masato Kubo, { Sinobu Suzuki, ‖ Akiko Matsui-Hasumi, {,‖ Ayako Uto-Konomi, {,‖ Atsushi Ogata, # Hideki Mochizuki,* Saburo Sakoda,** and Atsushi Kumanogoh †,# Multiple sclerosis (MS) is a demyelinating autoimmune disease of the CNS and a leading cause of lasting neurologic disabilities in young adults. Although the precise mechanism remains incompletely understood, Ag presentation and subsequent myelin-reactive CD4 + T cell activation/differentiation are essential for the pathogenesis of MS. Although semaphorins were initially identified as axon guidance cues during neural development, several semaphorins are crucially involved in various phases of immune responses. Sema4A is one of the membrane-type class IV semaphorins, which we originally identified from the cDNA library of dendritic cell (DC). Sema4A plays critical roles in T cell activation and Th1 differentiation during the course of experimental autoimmune encephalomyelitis, an animal model of MS; however, its pathological involvement in human MS has not been determined. In this study, we report that Sema4A is increased in the sera of patients with MS. The expression of Sema4A is increased on DCs in MS patients and shed from these cells in a metalloproteinase-dependent manner. DC-derived Sema4A is not only critical for Th1 but also for Th17 cell differentiation, and MS patients with high Sema4A levels exhibit Th17 skewing. Furthermore, patients with high Sema4A levels have more severe disabilities and are unresponsive to IFN-b treatment. Taken together, our results suggest that Sema4A is involved in the pathogenesis of MS by promoting Th17 skewing. The Journal of Immunology , 2012, 188: 4858–4865. M ultiple sclerosis (MS) is a demyelinating autoimmune disease that predominantly affects the white matter of the CNS and is a leading cause of lasting neurologic disabilities in young adults (1). Although the precise cause of MS is incompletely understood, MS is thought to occur in genetically predisposed individuals after they are exposed to an environmental trigger that stimulates myelin-specific T cells (2, 3). Indeed, genome-wide association studies have shown that the IL-2 receptor and HLA class II are associated with disease susceptibility (4–6). In addition, increasing evidence has shown that Th17 lymphocytes (7–9) and Th1 cells (10) play an important role in the pathology of MS. Thus, Ag presentation and subsequent CD4 + T cell activation/ differentiation are essential for the pathogenesis of MS. Although semaphorins were originally identified as axon guidance molecules during neural development, they are currently known to have diverse and important functions in other physio- logical processes (11), including heart morphogenesis (12), vas- cular growth (13), tumor progression (14, 15), and immune cell regulation (16, 17). Some semaphorins are crucially involved in immune responses, including Th differentiation (18, 19). Sema4A is a membrane-type class IV semaphorin that we originally iden- tified using a dendritic cell (DC) cDNA library. We previously reported that Sema4A plays critical roles in T cell activation and Th1 differentiation (18, 19). Indeed, the development of myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoim- mune encephalomyelitis (EAE) in wild-type mice can be improved *Department of Neurology, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan; † World Premier International Immunology Frontier Research Cen- ter, Osaka University, Osaka 565-0871, Japan; ‡ Department of Biomedical Statistics, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan; x Depart- ment of Neurology, Toyonaka Municipal Hospital, Osaka 560-0053, Japan; { Labo- ratory for Signal Network, Research Center for Allergy and Immunology, RIKEN Yokohama Institute, Kanagawa 230-0045, Japan; ‖ Department of Molecular and Cellular Biology, Kobe Pharma Research Institute, Nippon Boehringer Ingelheim, Hyogo 650-0047, Japan; # Department of Respiratory Medicine, Allergy and Rheu- matic Disease, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan; and **Department of Neurology, National Hospital Organization Toneyama National Hospital, Osaka 560-8552, Japan 1 Y. Nakatsuji and T.O. contributed equally to this work. Received for publication July 12, 2011. Accepted for publication March 6, 2012. This work was supported by research grants from the Ministry of Education, Culture, Sports, Science, and Technology of Japan, grants-in-aid from the Ministry of Health, Labor, and Welfare, the Promotion of Fundamental Studies in Health Sciences pro- gram of the National Institute of Biomedical Innovation (to A.K., Y. Nakatsuji, and S. Sakoda), Health and Labor Sciences Research Grants for Research on Intractable Diseases from the Ministry of Health, Labor, and Welfare (to Y. Nakatsuji and S. Sakoda), the Funding Program for Next Generation World-Leading Researchers (NEXT Program), and by Special Coordination Funds for Promoting Science and Technology (to A.K.). The sequences presented in this article have been submitted to the Gene Expression Omnibus (http://www.ncbi.nlm.nih.gov/geo/) under accession number GSE26484. Address correspondence and reprint requests to Prof. Atsushi Kumanogoh or Asso- ciate Prof. Yuji Nakatsuji, Department of Respiratory Medicine, Allergy and Rheu- matic Disease (A.K.) or Department of Neurology (Y.N.), Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan. E-mail addresses: kumanogo@imed3.med.osaka-u.ac.jp (A.K.) and yuji@neurol.med.osaka-u.ac.jp (Y.N.) The online version of this article contains supplemental material. Abbreviations used in this article: ANCOVA, analysis of covariance; BBB, blood– brain barrier; BMDC, bone marrow-derived dendritic cell; CIS, clinically isolated syndrome; DC, dendritic cell; EAE, experimental autoimmune encephalomyelitis; EDSS, expanded disability status scale; 2-ME, 2-mercaptoethanol; MOG, myelin oligodendrocyte glycoprotein; MS, multiple sclerosis; NMO, neuromyelitis optica; OND, other neurologic disease; RRMS, relapsing–remitting multiple sclerosis. 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