[The pathogenic role of inflammation in multiple sclerosis].

INTRODUCTION: Multiple sclerosis (MS) is characterized by the presence in the central nervous system (CNS) of perivascular inflammatory infiltrates containing auto-reactive T and B cells and activated macrophages thus indicating that MS is a T cell-mediated CNS-confined chronic inflammatory demyelinating disease in which the ultimate effector cell is the activated macrophage. DEVELOPMENT: The inflammatory process, leading to patchy demyelination and axonal loss, is mainly sustained by pro-inflammatory cytokines that modulate at different levels the pathogenic process underlying MS. Cytokines can 1. Sustain the 'putative' CNS-confined inflammatory process leading to the development of myelin-specific T cells; 2. Activate circulating myelin-specific T cells and shape their repertoire (Th1 versus Th2 pattern); 3. Induce the CNS recruitment of non antigen specific T cells and myelinotoxic effector cells (monocyte/macrophages) from the periphery, and 4. Cause direct oligodendrotoxicity (TNF alpha) or induce the secretion of myelinotoxic substances. The present chapter will focus on the mechanisms sustaining the activity of pro-inflammatory cytokines in MS pathogenesis.