CPT1A overexpression alleviates sepsis-induced acute lung injury by inhibiting ferroptosis through the enhancement of ACSL4 succinylation: evidence from clinical samples, mouse models, and alveolar epithelial cells

Sepsis-induced acute lung injury (SI-ALI) is strongly influenced by ferroptosis, a regulated cell death pathway. Carnitine palmitoyltransferase 1A (CPT1A), known for its lysine succinyltransferase activity, regulates succinylation but its function in ferroptosis and SI-ALI remains to be elucidated. This study aim to determine the influence of CPT1A on ferroptotic processes in SI-ALI and to reveal the key regulatory mechanisms involved. The SI-ALI model was generated in C57BL/6 mice via cecal ligation and puncture (CLP), while alveolar epithelial cells MLE-12 were treated with lipopolysaccharides (LPS) to mimic SI-ALI in vitro. Quantitative PCR and Western blotting were employed to evaluate CPT1A levels in peripheral venous blood samples from SI-ALI patients, as well as in both the mouse and cellular models of SI-ALI. Ferroptosis was evaluated by measuring malondialdehyde, glutathione, Fe 2+ levels, and reactive oxygen species fluorescence intensity. To elucidate the underlying mechanisms, co-immunoprecipitation (co-IP) and standard IP techniques were utilized. Our findings indicated that CPT1A was downregulated in SI-ALI. Overexpression of CPT1A inhibited ferroptosis in the in vitro SI-ALI model by enhancing ACSL4 succinylation, thereby reducing ACSL4 expression. Notably, overexpression of ACSL4 counteracted CPT1A-mediated ferroptosis suppression in vitro. Moreover, CPT1A overexpression ameliorated pulmonary pathology and suppressed ferroptosis activation in the lungs of SI-ALI mice. Collectively, the results indicate that CPT1A alleviated SI-ALI through the inhibition of ferroptosis by promoting ACSL4 succinylation, providing a novel theoretical foundation and potential therapeutic target for SI-ALI treatment.