Fig. 3
Time-dependent gene expression of CYP1A1, CYP1B1, PAI-2 and HO-1 in HBEC3-KT cells after exposure to road tunnel PM. The cells were exposed to 100 µg/mL (10.4 µg/cm2) coarse (C), fine (F) and ultrafine (UF) PM from the Marienborg (white bars) and Hell (grey bars) tunnels for 3, 6, 9 and 20 h. Gene expression of CYP1A1 (a), CYP1B1 (b), PAI-2 (c) and HO-1 (d) was analysed by qPCR. Results are presented as gene-expression (mean ± SEM) relative to the respective control (n = 4 independent experiments). *Significant increase compared to control at each time point. Brackets, significant differences between PM sizes. ¤Significantly different between tunnels at the same PM size and time-point. The statistical analysis was performed by 2-way ANOVA with Tukey’s multiple comparison test on normalized CT values