Nitric Oxide Synthase Expression and Apoptosis in Psoriasis

Youn, Tae Young; Jung, Seok Ki; Chang, Seung Ho

Abstract

BACKGROUND: Nitric oxide(NO) is generated from L-arginine by NO synthase(NOS). Three types of NOS are currently known:inducible(iNOS), neuronal(nNOS) and endothelial(eNOS). NO has been found to be important in a number of different physiological processes. Of particular relevance to the skin are the roles of NO in vasodilatation, inflammation, immunomodulation and in oxidative damage to cells and tissues. NO exhibits contradictory effects in the regulation of apoptosis. The proapoptotic effects seem to be linked to pathophysiological conditions, where high amounts of NO are produced by iNOS. In contrast, the continuous release of eNOS inhibits apoptosis. Psoriasis is a common chronic skin disease, but the cause of psoriasis is not definitely known until now. OBJECTIVE: To investigate the role of NO in psoriasis pathogenesis, such as inflammatory infiltration, dermal vessels dilatation, apoptosis, we performed this study. METHODS: Ten cases of psoriasis and 5 cases of normal skin for immunohistochemical with antibodies to iNOS, PCNA, bcl-2, p53 and TUNEL stainings, and 5 cases of psoriasis and 2 cases of normal skin for western blot with antibody to iNOS were investigated. RESULTS: The results were summarized as follows.1. Immunohistochemical staining with iNOS showed positive reactions in 9 cases(90 %) of psoriasis, 4 cases among them were strong positive staining, but all cases of normal skin were negative.2. Labelling index of PCNA staining was 24.4+2.5%, 2.4+0.7% in psoriasis, normal skin, respectively.3. All cases of psoriasis and normal skin were negative in p53 staining, but squamous cell carcinoma as positive control was positive.4. Bcl-2 staining showed focal positivity in 5(50%) cases of psoriasis, but diffuse positivity in epidermal basal layer of normal skin.5. TUNEL staining showed positivity in 7(70%) cases of psoriasis, but all of normal skin were negative.6. Western blot with anti-iNOS showed positive 130 kDa band in psoriatic, but not in normal skin tissues. CONCLUSION: The results suggested that NO was considered to play a role in psoriasis pathogenesis, including apoptosis, dermal vessels dilatation and inflammatory infiltration.