Frontiers in Bioscience-Landmark (FBL) is published by IMR Press from Volume 26 Issue 5 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Frontiers in Bioscience.
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Multiple sclerosis (MS) is the most frequent demyelinating disease of the central nervous system. Peptidases like dipeptidyl peptidase IV (DP IV, CD26) and aminopeptidase N (APN, CD13) play a regulatory role in T cell activation and represent potential targets for the treatment of inflammatory disorders. Synthetic inhibitors of DP IV and/or APN enzymatic activity induce production of the immunosuppressive cytokine TGF-beta1 and subsequently suppress DNA synthesis and Th1 cytokine production of activated human T cells. Compelling evidence has demonstrated that IL-17-producing CD4 cells (Th17) are a major contributor to the pathogenesis of autoimmune inflammation. Here, we report that inhibitors of DP IV-like activity as well as of APN activity inhibit IL-17 production in activated human and mouse T cells. Combining inhibitors of DP IV and APN increases the suppressive effect on T cell specific IL-17 production in vitro compared to a single peptidase inhibitor. In the following, we summarize the evidence for the role of both ectoenzymes in T cell activation in vitro and in vivo and provide a rationale for the use of combined or dual ectopeptidase inhibitors to treat autoimmune diseases like MS.