The study found that the tiny protein MOTS‑c, which the body makes in mitochondria, can protect lung blood vessels from damage caused by cutting off and then restoring blood flow. In mice, giving MOTS‑c worked just like a special pre‑conditioning trick (RIPC) that doctors sometimes use before surgery, and it helped keep the lung’s tiny blood‑vessel walls intact by boosting a protective factor called Nrf2.

Remote ischemic preconditioning (RIPC) induces the expression of unidentified protective cytokines that mitigate lung ischemia-reperfusion injury (LIRI). This study hypothesizes that MOTS-c, a mitokine with potent protective effects against mitochondrial damage, contributes to RIPC-mediated protection by alleviating endothelial barrier dysfunction. In human lung transplantation patients, serum levels of MOTS-c significantly decreased following IR injury but were markedly increased when RIPC was performed prior to transplantation. Similarly, in a mouse model of LIRI, RIPC restored serum MOTS-c levels and improved lung injury outcomes. Intravenous administration of MOTS-c in mice replicated the protective effects observed with RIPC. Mechanistic studies demonstrated that repeated hypoxia in human primary skeletal muscle immortalized cells (HPSMIC) led to the secretion of conditioned media that protected HUVECs from OGD/R-induced injury; silencing MOTS-c abolished these protective effects. Further investigations using nuclear factor erythroid 2-related factor 2 (Nrf2) knockout mice and the Nrf2 inhibitor ML385 revealed that MOTS-c exerts its protective function by increasing Nrf2 protein levels, thereby maintaining endothelial barrier integrity. In conclusion, this study identifies MOTS-c as a novel mediator of RIPC's protective effects against LIRI and highlights its potential as a therapeutic alternative for preventing lung injury and preserving vascular endothelial function.