(A, B)
Left panel: CXCL8 gene expression was enhanced in smokers and mild-to-moderate COPD in early and short-term ALI cultures, respectively, but no striking difference was observed in later time periods or in (very) severe COPD. Right panel: no difference was observed in IL6 gene expression in smokers and COPD-derived ALI-AE as compared with non-smokers. (C) IL-8/CXCL-8 production by the reconstituted ALI-AE is increased in early, short-term, and mid-term ALI-AE from COPD patients, but disappears afterwards, although a non-significant upward trend persists. (D) IL-6 production by the reconstituted ALI-AE is increased in Smo and COPD and persists in long-term cultures. * indicates a P-value of less than 0.05, whereas **** indicates P-values of less than 0.0001. Bars indicate mean ± SD (A [left], B) and median ± interquartile range (A [right], C). AE, airway epithelium; ALI, air-liquid interface; COPD, chronic obstructive pulmonary disease; IL, interleukin; NS, non-smokers; ns, not significant; SD, standard deviation; SEM, standard error of the mean; Smo, smokers; w, weeks.