N-Acetyl cysteine rescues neonatal lethality caused by HRas/NRas deficiency by improving lung maturation and decreasing oxidative stress

We reported previously that HRas/NRas double knockout (DKO) mice die at birth time (P0) due to respiratory failure caused by lung maturation delays that affect the alveolar cell lineage. Interestingly, antenatal glucocorticoid treatment improved alveolar lung maturation but failed to abrogate neonatal lethality (Fuentes-Mateos et al. 2019). More recently, we observed that the lungs of P0 DKO mice show signs of mitochondrial alterations including significantly elevated levels of reactive oxygen species (ROS), and worsened mitochondrial respiration as assessed with Seahorse MitoStress tests in lung tissue slices. We administered an antenatal N-acetyl cysteine (NAC) treatment that significantly improved not only lung maturation, but also mitigated the ROS production and ameliorated the lethal phenotype, resulting in about 53% of the DKO surviving until adulthood. To get mechanistic clues of the epithelial-mesenchymal signalling in our mice, we isolated primary lung fibroblasts (LFs) from P0 animals. We have detected higher levels of ROS in the DKO LFs, as well as a significant increment in the expression of superoxide dismutase 3 (SOD3), Glutathione S-transferase m2 (GSTm2) and a decrease in Glutathione S-reductase (GSR). Furthermore, a significant increment in Fgf7, Fgf10, Wnt2 and Hox5C expression was also observed. Additionally, we have detected higher expression of Fgfr2b, Wnt7 and Nkx2.1 in the DKO lung epithelium. Our data suggest that antenatal NAC administration improves lung maturation and function in our HRas;NRas DKO mice, at least in part, through its antioxidant effect. In addition, our analysis of primary DKO LFs, together with epithelial analysis, suggest that the signalling between mesenchyme and epithelium is affected.