URINARY AND SERUM NITRATES AND NITRITES AS SURROGATES OF NITRIC OXIDE IN CHILDHOOD RHEUMATIC DISEASES

Abstract

I NO is an important signaling molecule that plays a key role in host defense against microbes, tumor cells and also I antigens (Grabowski et al, 1996). The inducible isoform of NOS is highly expressed during cell mediated immune responses and after exposure to inflammatory cytokines, endotoxins and oxidants. NO has a potent proinflammatory activity and thus it induces self-destructive processes I (Gilkeson et al, 1999).

Therefore, this study was conducted on 22 patients with JRA, 18 with SLE and 16 healthy children as controls to evaluate surrogates of NO namely S.N03, S.N02, S.N03/N02 and U.N03/Cr as markers of disease activity, and the effect of different modalities of treatment. I Statistical analysis of the results revealed higher mean values of NO surrogates in SLE as compared to controls. A significant drop in their levels was noticed with disease quiescence (judged by clinical picture and ESR), however the levels remained significantly higher than those of controls. Furthermore, patients with severe forms of the disease namely lupus nephritis had higher levels than patients with arthritis or vasculitic rash. These findings could be the result of increased NO production in response to inflammatory cytokines. I Similar results were obtained with JRA, in whom the levels were higher than in controls both during activity and remission states, and in-patients with polyarticular JRA than in those with the pauciarticular type. Worth mentioning is that U.N03/Cr correlated positively with ESR in JRA. These data could be explained by the generation of NO in the inflamed joints by many cells including chondrocytes and the generated NO has been accused of contributing to bone loss in JRA.