Brevilin A Ameliorates Imiquimod-Induced Psoriasis-like Dermatitis and Reduces Th17 Differentiation in Psoriasis Patients.

Psoriasis is a predominantly Th17 cell-driven chronic autoinflammatory skin disorder. Brevilin A, a natural sesquiterpene lactone extracted from , has been used as a traditional oriental medicine for allergic diseases for centuries. However, the effects of brevilin A on psoriasis have yet to be established. In this study, we investigated brevilin A to elucidate its potential effects on T cell activities in psoriasis, in animal models and patients. An imiquimod (IMQ)-induced psoriasis-like dermatitis murine model was utilized. Experimental mice were administered different doses of brevilin A (5, 10, 20 mg/kg respectively) for a duration of 5 days. Cutaneous manifestations were measured daily. Under hematoxylin and eosin (H&E) stain and immunohistochemistry (IHC), acanthosis and proinflammatory cytokine expression in the dorsal skin of mice were detected. Enzyme-linked immunosorbent assay (ELISA) was used for the measurement of IL-17A levels in serum samples. Naïve CD4+ T cells, isolated from mice spleen and lymph nodes and from peripheral blood mononuclear cells (PBMCs) of psoriatic patients, were used to evaluate the effects of brevilin A on Th17 differentiation. In brevilin A-treated mice, brevilin A significantly reduced skin redness and scaling; acanthosis as well as IL-6, IL-17A, and ki-67 expressions were downregulated in the dorsal skin, and serum levels of IL-17A were lowered. Brevilin A also inhibited Th17 differentiation. In conclusion, brevilin A demonstrated significant capability in ameliorating skin inflammation in IMQ-induced psoriasis-like dermatitis and could modulate Th17 differentiation. Therefore, brevilin A is potentially pharmacologically effective in the treatment of psoriasis.