Impact of oxidative stress on epithelial repair and alveolar oedema, within in vitro model of lung injury

Abstract

Repair of lung injury is a complex process including epithelial growth, alveolar clearance and down‐regulation of inflammatory response. The impacts of oxidative stress in this process are still unknown. To study this question, we developed an in vitro model of lung injury to characterise the molecular and cellular mechanisms of distal lung epithelial repair. Alveolar epithelial cells in primary culture were submitted to oxidative stress with bleomycin (B : 12,5–150mU/ml) or DMNQ (D : 2,5–15μM). Bleomycin and DMNQ inhibit the epithelial repair (24–48h) following a mechanical injury in a time and concentration dependent manner (p<0,0001). These agents also decrease by 60% and 80% respectively the cell migration in Boyden's chamber (p<0,0001) and decrease cell proliferation measured as thymidine 3H incorporation by 95% and 70% (p<0,0001). These results show that oxidative stress has an impact on alveolar epithelial cell repair by inhibiting the cell migration and proliferation processes. The impact of bleomycin on the ionic transport was studied in Ussing chamber. The treatment decreases by 37% the total as well as amiloride‐sensitive transepithelial current (p<0,05). Basolateral permeabilisation in presence of a Na gradient shows that the epithelial Na channel (ENaC) is not involved in this decrease. The oxidative stress therefore in addition to inhibiting epithelial repair also decreases the Na transport involved in lung liquid clearance.Supported by RSR‐FRSQ, CCFF, CIHR.