Fig. 6
Saharan dust but not DQ12 quartz dust induced cytokine gene expression and release. Air-liquid interface co-cultures were exposed to DQ12 and Saharan dust (SD) at doses in the range of 0–31 µg/cm² for 24 h or 250 ± 60 ng/cm² LPS for 21 h. The relative gene expressions of IL1B (A), IL6 (B), IL8 (C), TNFA (D), and IL18 (E) as well as basolateral cytokine releases of IL-1β (F), IL-6 (G), IL-8 (H), TNFα (J), and IL-18 (K) were assessed by qRT-PCR and ELISA, respectively. The gene expression results were normalized to control ALI cultures as well as to the reference genes ACTB and GAPDH. Fold changes were derived from the means of ΔΔCT values and standard deviations of ΔCT values. Depicted are mean values with standard deviations. Mixed-effects models with Šidák’s post hoc test were calculated based on the ΔCT values and absolute cytokine concentrations for qRT-PCR and ELISA data, respectively. N = 4 independent experiments were performed (N = 3 for IL-18 release; Controls and LPS: one or two biological replicates; DQ12 and SD: duplicates per concentration; *p ≤ 0.05; **p ≤ 0.01). n.d.: not detected