PM2.5 Induced the Expression of Fibrogenic Mediators via HMGB1-RAGE Signaling in Human Airway Epithelial Cells

Figure 2

PM2.5 induces HMGB1 secretion and upregulates RAGE expression in HBECs. HBECs were incubated with PM2.5 for 12, 24, and 48 h. (a) Based on the ELISA results, HMGB1 secretion was increased upon stimulation with PM2.5 (20 μg/ml) for 24 and 48 h; no significant changes were observed at 12 h. (b) ELISA results show that HMGB1 expression increases 48 h after PM2.5 exposure in a concentration-dependent manner. (c) Real-time quantitative PCR analysis showing an increase in the expression of the RAGE mRNA after 48 h of exposure to PM2.5 (20 μg/ml); no significant differences were observed in the levels of the TLR2 and TLR4 mRNAs. These data show 1.48-fold (RAGE), 1.14-fold (TLR2), and 1.12-fold (TLR4) increases compared with the untreated control, respectively, using the GAPDH mRNA for calibration. (d) Western blot analysis showing that PM2.5 (20 μg/ml) increases the levels of the RAGE protein, with no significant changes in the levels of the TLR2 and TLR4 proteins. (e) Immunofluorescence staining shows that PM2.5 (20 μg/ml) affects the levels of the RAGE protein. The RAGE/GAPDH ratio in control cells is set to 1. , compared with the control group. , compared with the PM2.5 group, n = 3.

(a)

(b)

(c)

(d)

(e)