Antrodia cinnamomea Extract Inhibits Th17 Cell Differentiation and Ameliorates Imiquimod-Induced Psoriasiform Skin Inflammation

Antrodia cinnamomea (A. cinnamomea) is a Chinese medicinal herb that possesses a broad range of bioactivities, including anti-inflammation. Given that the proinflammatory cytokine IL-17 plays a critical role in the pathogenesis of autoimmune diseases, we investigated whether A. cinnamomea could inhibit the development of Th17 cells, the main producer of IL-17, and exhibit therapeutic effects on an animal model of psoriasis. We found that A. cinnamomea extract (AC) inhibited the differentiation of Th17 cells as well as the production of IL-17A, IL-21, and IL-22 from these cells. This effect was associated with the inhibition of STAT3 phosphorylation and ROR gamma t expression. Notably, the oral administration of AC reduced psoriasis-like inflammation in imiquimod-mediated dermal damage, repressed the expression of IL-17A, IL-22, and TNF-alpha in skin lesions, and decreased the infiltration of CD4(+) T cells, CD8(+) T cells, and neutrophils into the dermis. Finally, serum levels of IL-17A were decreased in AC-treated mice with psoriasis-like skin inflammation. Taken together, these findings indicate that AC inhibits Th17 cell differentiation, suggesting a role for A. cinnamomea in the treatment of psoriasis and other Th17 cell-mediated inflammatory diseases.