Lipopolysaccharide and cytokines induce nitric oxide synthase and produce nitric oxide in cultured normal human melanocytes.

The role of nitric oxide in normal and pathological conditions of human skin is still poorly understood. In this study we have demonstrated by immunobloting the expression of an inducible nitric oxide synthase isoform (iNOS) in cultured normal human melanocytes treated with bacterial lipopolysaccharide, tumor necrosis factor-alpha and interferon-gamma. Nitric oxide was also detected in the culture medium and its formation was abolished upon treatment with N(G)-mono-methyl-L-arginine(L-NMMA), a competitive inhibitor of nitric oxide synthase. These results suggest that nitric oxide could led to autodestruction of melanocytes causing skin depigmentation. The therapeutic relevance of nitric oxide synthase inhibitors in treatment of vitiligo was suggested.