Heme oxygenase-1 protects against endotoxin-induced acute lung injury depends on NAD(+)-mediated mitonuclear communication through PGC1α/PPARγ signaling pathway

Endotoxin-induced acute lung injury (ALI) is a challenging life-threatening disease for which no specific therapy exists. Mitochondrial dysfunction is corroborated as hallmarks in sepsis which commonly disrupt mitochondria-centered cellular communication networks, especially mitonuclear crosstalk, where the ubiquitous cofactor nicotinamide adenine dinucleotide (NAD(+)) is essential for mitonuclear communication. Heme oxygenase-1 (HO-1) is critical for maintaining mitochondrial dynamic equilibrium and regulating endoplasmic reticulum (ER) and Golgi stress to alleviating acute lung injury. However, it is unclear whether HO-1 regulates NAD(+)-mediated mitonuclear communication to exert the endogenous protection during endotoxin-induced ALI. In this study, we observed HO-1 attenuated endotoxin-induced ALI by regulated NAD(+) levels and NAD(+) affected the mitonuclear communication, including mitonuclear protein imbalance and UPR(mt) to alleviate lung damage. We also found the protective effect of HO-1 depended on NAD(+) and NAD(+)-mediated mitonuclear communication. Furtherly, the inhibition of the PGC1α/PPARγ signaling exacerbates the septic lung injury by reducing NAD(+) levels and repressing the mitonuclear protein imbalance and UPR(mt). Altogether, our study certified that HO-1 ameliorated endotoxin-induced acute lung injury by regulating NAD(+) and NAD(+)-mediated mitonuclear communications through PGC1α/PPARγ pathway. The present study provided complementary evidence for the cytoprotective effect of HO-1 as a potential target for preventing and attenuating of endotoxin-induced ALI.