Fig 2. Inflammatory response of normal and cystic fibrosis (CF) human bronchial epithelia (HBE) 24 h after exposure to seasonally sampled PM from either an urban roadside (Bern) or a rural alpine valley site (Magadino).

(a) Release of interleukin (IL)-6 and IL-8 into the basolateral compartment (dotted lines show interleukin release in incubator controls). The data are presented as mean values and error bars representing 1 standard deviation of three independent experiments (ANOVA, Dunnett’s multiple comparison) with triplicate cell cultures (total n = 9 cell cultures). (b) IL-6 and (c) IL-8 release vs. deposited particle dose associated with positive linear correlation using standard linear regression analysis. ** p-value < 0.01, *** p-value < 0.001 compared to filter blank. Abbreviations: LPS = lipopolysaccharide (10 μg/mL); L = low dose; H = high dose; R² = R-square linear coefficient of determination.