Nitric oxide production in rheumatoid arthritis

Abstract

Nitric oxide (NO), originally found as endothelium-derived relaxing factor (EDRF), is a free radical synthesized by NO synthases (NOS). Two isoforms exist in NOS, i.e. constitutive NOS (cNOS) and inducible NOS (iNOS). Inflammatory cytokines such as interleukin-1, interferon-γ, tumor necrosis factor-α induce iNOS expression in various cells including macrophages. Enhanced NO production is observed in arthritic conditions both in rodent models and human. The onset of arthritis in rodent models is significantly inhibited by the NOS inhibitor, N ^G-monomethyl-l-arginine. These data suggest a possible involvement of NO in the induction and/or maintenance of rheumatoid arthritis.