Figure 8.

Inflammatory markers in HBECs exposed to PG e-cig aerosols. Exposure of HBECs to e-cig aerosols of PG significantly increased the expression of MMP9 (A) and IL1B (B) mRNAs after 7 days. IL6 (C), IL8 (D), and TGFB1 (E) mRNA expressions are statistically unchanged in HBECs after 7 days of PG exposure compared with air controls. n ≥ 8 lungs. Data are presented as means ± SE. *P < 0.05. Data were analyzed by two-tailed t test (A) or two-tailed Wilcoxon test (B–E) after assessing normality by Shapiro–Wilk. HBECs, human bronchial epithelial cells; ns, not significant; PG, propylene glycol.