The role of nitric oxide synthases in pemphigus vulgaris in a mouse model.

BACKGROUND Pemphigus vulgaris (PV) is a blistering autoimmune disease characterized by IgG autoantibodies against desmoglein 3. Nitric oxide synthases (NOS) may contribute to the increase of inflammation in tissues by the generation of nitrotyrosine residues (NTR). OBJECTIVES To investigate whether the production of NTR mediated by NOS may participate in the development of inflammation and acantholysis in PV. METHODS Mice were pretreated or not with NOS, tyrosine-kinase (TK) or nuclear factor (NF)-kappaB inhibitors, and then injected with PV-IgG. PV manifestations were examined in all mice. The expression of NTR, constitutive NOS (cNOS) [endothelial NOS (eNOS) and neuronal NOS (nNOS)], inducible NOS (iNOS) and NF-kappaB factor were studied in epidermis of mice using immunohistochemical techniques. RESULTS After PV-IgG injection, expressions of NTR, iNOS, eNOS and nNOS increased in acantholytic cells, as did nuclear translocation of NF-kappaB in the basal cells of the epidermis. Pretreatment of mice with inhibitors of TK, nNOS and nonselective NOS, completely prevented NTR expression and the clinical and histological findings of PV in mice. TK inhibitor genistein inhibited both nNOS and iNOS expression on the membrane of basal keratinocytes, and nuclear translocation of NF-kappaB. CONCLUSIONS Upregulation of cNOS and iNOS, NTR generation and nuclear translocation of NF-kappaB may contribute to increased inflammation and tissue damage in PV lesions. The absence of the clinical and histological findings of PV and NTR expression in mice injected with PV-IgG, through pretreatment with TK and nNOS inhibitors, provides compelling evidence that these signalling molecules should be considered as potential therapeutic targets in PV.