Diesel Exhaust Particles-induced Dysfunctional Responses in Lung Epithelial Progenitors is mediated by oxidative stress

Background: Air pollution has been linked to COPD development; however, the precise mechanisms involved are unclear. We hypothesized diesel exhaust particles (DEP) may reduce the functionality of lung epithelial progenitors, whereas anti-oxidants may protect against the influence from DEP. Methods: Murine lung organoids were set up by co-culturing epithelial cells (EpCAM+/CD45-/CD31-) with CCL206 fibroblasts in Matrigel. Organoids were exposed to DEP (50-, 100-, 200 µg/ml) and/or NAC (1mM)/MitoQ (1μM). Results: The total organoid number was decreased by 200 μg/mL DEP by day7, yet increased by 50 and 100 μg/mL DEP. Subclassifying the organoids into airway/alveolar organoids revealed that airway organoid number was increased by 50 and 100 μg/mL DEP, and decreased by 200 μg/mL DEP by day14. Alveolar organoid number was decreased by 200 μg/mL DEP. Immunofluorescence studies confirmed that 200 μg/mL DEP decreased the number of acetylated-α tubulin+ and pro-SPC+ organoids. The size of alveolar organoids was also reduced by 200 μg/mL DEP. In line with these findings, the gene expression of FGF2, FGF7, FGF10 and HGF was decreased in fibroblasts by 200 μg/mL DEP. Interestingly, NAC (1mM) or MitoQ (1μM) rescued the number of alveolar organoids after exposure to 200 μg/mL DEP, but had no influence on airway organoids. NAC and MitoQ had no influence on organoid size. Conclusion: DEP functionally inhibit lung organoid formation by epithelial progenitors, which may contribute to defective alveolar repair in COPD. NAC and MitoQ protect against the damage from DEP in alveolar epithelial progenitors.