Phenotypic changes of lymphocyte populations in psoriasiform dermatitis animal model.

Psoriasis is a T cell mediated, chronic inflammatory autoimmune skin disease that affects up to 2-3% of the global population and leads to a decrease in quality of life. Experimental data accumulated in recent years highlighted the important role played by the immune system in the pathogenesis of this disease. Non-human psoriasis models are an important research tool that attempts to reproduce the clinical features of the disease in order to explain the pathogenesis of psoriasis and to identify possible therapeutic targets. Imiquimod-based murine model of psoriatic dermatitis is an alternative to traditional models of experimental psoriasis in mice and the induced dermatitis closely mimics the pathologic changes in human psoriasis. In order to emphasize changes in immune cell populations involved in lesion pathogenesis, we performed a murine model of psoriasiform dermatitis model by topical IMQ application. The progress and the severity of IMQ-induced skin inflammation were clinically (PASI score) and histopathologically evaluated. The immunological changes induced by IMQ treatment in lymphocyte populations from peripheral blood and spleen were evaluated by flow cytometry. The main changes observed in peripheral blood were the significantly increased T-CD8a lymphocyte and NK1.1 cell percentages and the decreased T-CD4 and B lymphocyte percentages in IMQ-treated mice. In spleen samples, lymphocytes showed the same tendency of variation as in peripheral blood, but without statistical significance. A significant decrease of B cells percentages was observed in spleen suspensions. Data obtained in skin samples may suggest the involvement of CD3ε, CD4 and CD8a cells in the lesional process. This murine model was analyzed by performing a basic cellular profile at three levels: peripheral blood, spleen and skin. The evaluation aimed to establish the immune framework of this experimental model that could further be used for etipathogenic mechanism identification and/or for studies regarding targeted therapies.