Tobacco smoke is related to Th17 generation with clinical implications for psoriasis patients.

Environmental factors contribute to the increased prevalence of autoimmune diseases via T helper type-17 cell (Th17) activation. Tobacco smoking increases the risk of psoriasis, but the mechanisms are not clear. We evaluated the percentage of circulating Th17 among CD3(+) cells in peripheral blood mononuclear cells (PBMC) obtained from 27 healthy volunteers (2.58±0.80%), 33 smoker (3.55±1.33%) and 21 non-smoker (3.10±1.14%) patients with psoriasis to elucidate the relation between smoking and psoriasis. More smokers (19/33) than non-smokers (6/21) had high Th17 levels (Th17/CD3>3.38%, mean+1 SD of healthy volunteers). Tobacco smoke extract (TSE, 7μl/ml) induced Th17 generation from central memory T cells in vitro. TSE increased interleukin 17 and 22 expression. These findings demonstrate the relation between tobacco smoke and IL-17 and IL-22, which exacerbate psoriasis.