Fig. 2
Time-dependent gene expression of IL-1α, IL-1β, TNF-α, CXCL8 and COX2 in HBEC3-KT cells after exposure to road tunnel PM. The cells were exposed to 100 µg/mL (10.4 µg/cm2) coarse PM (C), fine PM (F) and ultrafine PM (UF) from the Marienborg (white bars) and the Hell (grey bars) tunnels for 3, 6, 9 and 20 h. Gene expression of IL-1α (a), IL-1β (b), TNF-α (c), CXCL8 (d) and COX2 (e) 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