Antiproliferative effect of pentoxifylline on psoriatic and normal epidermis. In vitro and in vivo studies

Psoriasis is characterized by abnormal cell proliferation, inflammation and increased biosynthesis of various cytokines. The inhibitory effect of pentoxifylline on some cell functions has been reported widely. This property of pentoxifylline prompted an investigation of its possible role in controlling psoriasis. In the in vitro study normal human keratinocytes proliferation was determined and formation of cornified envelopes was assayed following treatment with pentoxifylline. The in vivo experiment consisted of nude mice grafted with psoriatic or normal skin treated with tetradecanyl phorbol 13 acetate. At the end of the treatment period, the grafts were excised and assessed for acanthosis and labelling index. The in vitro study showed that continuous exposure of normal human keratinocyte cultures to pentoxifylline resulted in a significant dose-dependent inhibition of proliferation, and in induction of cornified envelope formation. The in vivo experiments showed a significant reduction of epidermal thickness and of labelling index in psoriatic and tetradecanyl phorbol 13 acetate-treated normal skin, as compared to the initial values.