Tumor necrosis factor-alpha (TNF-alpha) is a pleiotropic pro-inflammatory cytokine with potentially neurodestructive effects and plays a pivotal role in autoimmune demyelinating disease. To address the role of TNF-alpha in the pathogenesis of experimental autoimmune neuritis (EAN), the current study investigated the antigen-presenting capacity of Schwann cells (SCs) in EAN induced by P0 protein peptide 106-125 in TNF-alpha receptor 1 deficient (TNFR1(-/-)) mice. The antigen-presenting capacity of SCs was assessed by the expression of MHC class II (MHCII), CD40, CD80 and CD86 molecules on activated SCs as well as by induction of T cell proliferation in co-cultures of P0 protein peptide 106-125 specific T cells with activated SCs. In addition, the expression of inducible nitric oxide synthase (iNOS) was measured in activated SCs by flow cytometry. TNFR1(-/-) EAN mice developed significantly delayed and reduced clinical signs of EAN compared to wild type EAN mice. In parallel, the expression of MHCII, CD80 and iNOS on SCs were decreased in TNFR1(-/-) mice compared to wild type mice. Likewise, proliferation of P0 protein peptide 106-125 specific T cells simulated by activated SCs of TNFR1(-/-) EAN mice was lower than that of wild type EAN mice. Our data suggest that TNF-alpha may exert pro-inflammatory effects in EAN via TNFR1 by up-regulating the antigen-presenting function and iNOS production of SCs.
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