Real-time quantitative PCR analyses of HDFs treated with IL-17A (100 ng/ml)/TNF-α (10 ng/ml), UVB (30 mJ/cm2), and TGF-β1 (2 ng/ml) for 24 h. (A) IL-17A/TNF-α-stimulated HDFs increase expression of IL-6, IL-8, and CXCL-1 mRNA, which are also seen in 30 mJ/cm2 UVB-irradiated HDFs. But UVB irradiation inhibits IL-17A/TNF-α-induced IL-6, IL-8, and CXCL-1 mRNA expression of HDFs. IL-17A/TNF-α stimulation induce the expression of TNFR-2, IL-17RA, and IL-17RC mRNA. UVB irradiation upregulates the expression of TNFR-1 and TNFR-2 mRNA but downregulates IL-17RA and IL-17RC expression, and inhibits IL-17A/TNF-α-induced IL-17RA and IL-17RC mRNA expression. IL-17A/TNF-α and UVB treatment do not induce significant expression of TGF-β1 mRNA 24 h after culture, but Smad3 mRNA is upregulated in both UVB irradiation and IL-17A/TNF-α + UVB groups. (B) TGF-β1 significantly induces the Smad3 mRNA expression and downregulates the IL-17RA and IL-17RC expression in HDFs. The data (fold change) are from one representative experiment performed in triplicate, repeated three times with similar results. UVB, ultraviolet B; HDFs, human dermal fibroblasts. Statistical significance indicated: *P < 0.05, **P < 0.01, ***P < 0.001.