Blockade of tumour necrosis factor-α in experimental autoimmune encephalomyelitis reveals differential effects on the antigen-specific immune response and central nervous system histopathology.

In various autoimmune diseases, anti-tumour necrosis factor (TNF)-α treatment has been shown to reduce both clinical disease severity and T helper type 1 (Th1)1/Th17 responses. In experimental autoimmune encephalomyelitis (EAE), however, the role of TNF-α has remained unclear. Here, C57BL/6 mice were immunized with myelin oligodendrocyte glycoprotein (MOG) peptide 35-55 and treated with anti-TNF-α, control antibody or vehicle. The clinical disease course, incidence and severity were assessed. On day 20 after immunization the antigen-specific Th1/Th17 response was evaluated by enzyme-linked immunospot (ELISPOT) in spleen and central nervous system (CNS). Also, the extent of spinal cord histopathology was analysed on semi- and ultrathin sections. Our results demonstrate that anti-TNF-α treatment reduced the incidence and delayed the onset of EAE, but had no effect on disease severity once EAE had been established. Whereas anti-TNF-α treatment induced an increase in splenic Th1/Th17 responses, there was no effect on the number of antigen-specific Th1/Th17 cells in the spinal cord. Accordingly, the degree of CNS histopathology was comparable in control and anti-TNF-α-treated mice. In conclusion, while the anti-TNF-α treatment had neither immunosuppressive effects on the Th1/Th17 response in the CNS nor histoprotective properties in EAE, it enhanced the myelin-specific T cell response in the immune periphery.