engleski

Different cytolytic mechanisms are involved in the pathogenesis of psoriasis

Background and objective: Psoriasis is a chronic inflammatory skin diseases mediated by T-cells. Recent studies suggest an involvement of various cytolytic mechanisms in the development of this chronic systemic disease. In the present study, we analysed the distribution of perforin, FasL, T and NK cell subsets in psoriatic skin by immunohistochemistry. Methods: Skin biopsy specimens from lesional and non-lesional skin of 11 patients with chronic plaque psoriasis and 8 healthy persons were analysed by immunohistochemistry using biotin- streptavidin-peroxidase method. Results: Significant increases in the whole T-cell population were observed in the lesional epidermis compared with nonlesional and healthy skin. The incidence of CD4+ cells was significantly higher in lesions than in either nonlesional or healthy skin (p<0.001). Similar results were obtained for epidermal CD8+ cells when compared with nonlesional and healthy epidermis (p<0.01). The expression of perforin-positive cells was significantly higher in lesions than in either nonlesional or healthy control (p<0.01). The expression of perforin-positive cells was almost three times higher in the epidermis than in the dermis of psoriatic lesions. Perforin- expressing cells were found suprabasally particularly at sites of spongiosis in the epidermis in close contact with damaged keratinocytes, The expression of FasL was also significantly higher in the lesional compared with non-lesional epidermis (p<0.01). Moreover, FasL expresion was almost two times higher in epidermis than in dermis of psoriatic lesions. Conclusion: Our results clearly show the upregulation of T cells along with perforin and FasL cytolytic mechanisms and therefore suggest an important role of these immunological pathways in the pathogenesis of psoriasis.

Psoriasis; Perforin; FasL; NK cells

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