Complex Immunomodulatory Effects of Interferon-b in Multiple Sclerosis Include the Upregulation of T Helper 1-Associated Marker Genes Klaus-Peter Wandinger, MD, 1 Claus-Steffen Stu¨rzebecher, MD, 1 Bibiana Bielekova, MD, 1 Greg Detore, 1 Andreas Rosenwald, MD, 2 Louis M. Staudt, MD, PhD, 2 Henry F. McFarland, MD, 1 and Roland Martin, MD 1 Multiple sclerosis (MS) is considered an autoimmune disease that is mediated by proinflammatory T helper-1 lympho- cytes. The putative mechanism of interferon-b (IFN-b), an approved treatment for MS, includes the inhibition of T-cell proliferation, blocking of blood-brain-barrier opening and T-cell transmigration into the brain via interference with cell adhesion, and the upregulation of anti-inflammatory cytokines. In the present study, a gene expression analysis of IFN-b-treated peripheral blood mononuclear cells by cDNA microarray documents the broad effects of IFN-b that are not purely anti-inflammatory. Specifically, we addressed the effect of IFN-b on T helper-1 differentiation- or lineage markers such as the IL-12 receptor b 2 chain and the chemokine receptor CCR5 that have been implicated in the pathogenesis of MS. Both markers were significantly upregulated in vitro and in vivo under IFN-b therapy, supporting that this cytokine exerts complex effects on the immune system. The combination of cDNA microarray and quantitative PCR will expand our knowledge of the immunological effects of such pleiotropic agents as IFN-b, may provide a key to why certain patients fail to respond, and eventually may influence our view of the disease pathogenesis. Ann Neurol 2001;50:349 –357 Interferon-b (IFN-b) is the first approved drug for the treatment of multiple sclerosis (MS), an inflammatory, demyelinating disorder of the central nervous system (CNS). 1 In Phase III clinical trials, IFN-b has de- creased relapse rate and severity, progression of disabil- ity, and development of new brain lesions as detected by magnetic resonance imaging (MRI) in relapsing- remitting and secondary progressive MS patients. 2–5 However, while a number of activities are thought to contribute to its efficacy, much has yet to be learned about its mechanism of action. The cause of MS remains unknown, but its patho- genesis is ascribed in part to a T-cell-mediated autoim- mune response against myelin components. 1 Based on animal and in vitro studies in MS patients, the activa- tion of proinflammatory TH1 cells in the systemic cir- culation and their recruitment into the CNS plays a crucial role in the pathogenesis of MS. 6 –11 Given the immunoregulatory functions of IFN-b, it has been postulated that skewing of a TH1 bias in peripheral blood mononuclear cells (PBMC) toward TH2 ac- counts for some of its beneficial effects in MS. 12 This notion is supported by the enhancement of interleukin (IL)-10 expression by IFN-b treatment in MS. 13 How- ever, IFN-b, at least transiently, also increases the number of IFN-g secreting cells, 14 indicating that IFN-b stimulates the expression of anti-inflammatory TH2 cytokines but also upregulates a prototypic, proinflammatory TH1 molecule. Though this appears contradictory with respect to its efficacy in MS, its proinflammatory activity is also in agreement with re- cent experimental data that show Type I IFN as a ma- jor factor leading to TH1 development in human but not mouse CD41 T cells. 15,16 In order to assess the complex actions of IFN-b on the immune system, we examined IFN-b treated PBMC by cDNA microarrays to identify genes that are positively or negatively regu- lated by IFN-b. Furthermore, to understand more clearly the immunoregulatory functions of IFN-b in MS, we examined its effects on two critical markers of TH1 differentiation—the IL-12 receptor b 2 chain (IL- 12Rb 2 ) and the chemokine receptor CCR5. The IL-12Rb 2 chain is the binding and signaling component of the IL-12R, selectively expressed on From the 1 Neuroimmunology Branch, National Institute of Neuro- logical Disorders and Stroke; and 2 Metabolism Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD. Received Oct 9, 2000, and in revised form Mar 21, 2001. Accepted for publication Apr 23, 2001. Published online Jun 27, 2001; DOI: 10.1002/ana.1096 Address correspondence to Dr Martin, Neuroimmunology Branch, NINDS, National Institutes of Health, Building 10 Room 5B-16, 10 Center Drive, MSC 1400, Bethesda, MD 20892-1400. E-mail: martinr@ninds.nih.gov This article is a US Government work and, as such, is in the public do- main of the United States of America. Published 2001 Wiley-Liss, Inc. 349