Fig. 10

levels of pro-inflammatory mediators after stimulation with LPS (20 μg/mL). Co-cultures were stimulated at the ALI or in submerged conditions in inserts with 20 μg/ml of LPS at the basal side for 21 h. Levels of IL-1β, IL-6, IL-8 and TNF-α were assessed in culture medium at basal side and in culture medium or washing liquid at the apical side for submerged and ALI exposures, respectively. The control for ALI exposures was cells exposed at the ALI to air for 3 h in the exposure system and kept at the ALI for 21 h with fresh medium in the incubator. The control for submerged exposure was cells kept in submerged condition with fresh medium for 21 h. IL-1β, IL-6, IL-8 and TNF-α secretions were measured by ELISA multiplex in the cell culture medium. Results were first expressed in concentrations (pg/mL), to assess whether cells secreted similar amounts of cytokines at the ALI and in submerged conditions in inserts, after stimulation (a). Because we observed more basal secretion at the ALI (secretion by non stimulated cells), the data was also expressed in cytokine levels compared to control (b), to compare ALI and submerged results more accurately. Data represent the mean ± SD of three independent experiments. A two-way Anova followed by a Bonferroni post-hoc test were performed to compare treated groups to their respective controls (*p < 0.05; **p < 0.01; ***p < 0.001) or to compare ALI and submerged exposures (^# p < 0.05; ^## p < 0.01; ^### p < 0.001)