Diesel Exhaust Particles-Induced Dysfunctional Responses in Lung Epithelial Progenitors Is Mediated by Oxidative Stress

Abstract

Background: COPD is characterized by irreversible airflow limitation. Though studies indicate a causal role of air pollution in provoking the development of COPD through oxidative stress, the precise impact of these factors on lung progenitors is unclear. Targeting oxidative stress by antioxidants, such as N-Acetyl-L cysteine (NAC) and MitoQ might be a promising beneficial therapeutic approach in COPD treatment. We hypothesized therefore that diesel exhaust particles (DEP) may reduce the functionality of lung epithelial progenitors, whereas the antioxidants NAC/MitoQ 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 different concentrations of DEP (0-, 50-, 100-, 200 µg/ml) and/or NAC (1mM)/MitoQ (1µM) throughout 14 days culture period. Results: The total number of organoids observed on day7 was significantly decreased by 200 µg/mL DEP, yet increased by 50 and 100 µg/mL DEP. Subclassifying these organoids into airway or alveolar organoids revealed that airway type organoids were significantly increased by 50 and 100 µg/mL DEP, and decreased by 200 µg/mL DEP by day14. Furthermore, the number of alveolar type organoids was also significantly decreased by 200 µg/mL DEP. Immunofluorescence studies confirmed that the number of acetylated-α tubulin + and pro-SPC + organoids were significantly decreased by 200 µg/mL DEP. The size of alveolar type organoids by day14 was significantly reduced by 200 µg/mL DEP. In line with these findings, the gene expression of FGF2, FGF7, FGF10 and HGF was significantly decreased in fibroblasts treated 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.