NLRX1 alleviates sepsis-induced acute lung injury by activating mitophagy and suppressing NLRP3 inflammasome activation

Background: Sepsis-induced acute lung injury (ALI) is a life-threatening condition with limited therapeutic options. The mitochondrial protein NOD-like receptor X1 (NLRX1) has emerged as a potential immunometabolic modulator, but its functional role and mechanism in septic ALI remain poorly defined. Methods: Bioinformatic analysis was performed on the GSE4607 sepsis dataset. A murine model of sepsis-induced ALI was established using cecal ligation and puncture (CLP), with NLRX1 overexpression achieved through adeno-associated virus serotype 9 (AAV9)-mediated gene delivery. Histopathological evaluation, TUNEL staining, and transmission electron microscopy, ELISA were employed to assess lung injury. Mouse lung epithelial cells (MLE-12) were stimulated with lipopolysaccharide (LPS), combined with NLRX1 overexpression and Mdivi-1-mediated mitophagy inhibition to explore the key mechanism by which NLRX1 improves ALI. Results: NLRX1 was significantly downregulated in septic patients and mouse lungs, correlating with mitochondrial damage and NOD-like receptor protein 3 (NLRP3) inflammasome activation. NLRX1 overexpression in CLP mice attenuated pulmonary injury, edema, inflammation, and systemic cytokine release by enhancing mitophagy and suppressing apoptosis. Mechanistically, NLRX1 directly interacted with LC3B to promote mitophagy, thereby preserving mitochondrial membrane potential, reducing superoxide production and mtDNA release, and maintaining ATP levels. By improving mitochondrial homeostasis, NLRX1 overexpression indirectly suppressed NLRP3 inflammasome activation and pyroptosis. Crucially, the mitochondrial fission and mitophagy inhibitor Mdivi-1 abolished all beneficial effects of NLRX1, underscoring the essential role of comprehensive mitochondrial quality control. Conclusion: Our findings identify NLRX1 as a critical protective regulator of mitochondrial integrity that alleviates septic ALI by orchestrating mitophagy and mitochondrial quality control to restrain NLRP3-driven inflammation, presenting a promising therapeutic target.