TLR4 inhibition suppresses UVA-induced MMP-1 and IL-8 production in UVA-irradiated senescent HDFs.

(A) Senescent HDFs were treated overnight with different concentrations of TAK242 (TLR4 inhibitor) and irradiated with UVA (1 J/cm2). Cells were cultured for 4 h and protein levels of phosphorylated/total ERK were analyzed by western blotting. Anti-β-tubulin monoclonal antibody was used as a loading control. The images shown are representative of three independent experiments. (B) Total cellular ROS levels were determined by measuring DCF-DA levels using a spectrofluorometer. % ROS production in response to UVA is shown in the graph. Data are presented as percentage compared to the control (DMSO-treated cells). *p < 0.05, **p < 0.01, ***p < 0.001 vs. control cells. (C) MMP-1 and (D) IL-8 secretion levels in the culture supernatant were measured by ELISA. The values are mean ± SEM of three different experiments. *p < 0.05, **p < 0.01, ***p < 0.001 vs. control cells.