YY1 lactylation mediates epithelial barrier dysfunction during acute lung injury.

Elevated lactate levels in lung tissue are a distinct hallmark of acute lung injury (ALI), but the biological functions of glycolytic reprogramming and lactate-derived protein modification in damaged alveolar epithelial cells remain poorly elucidated. In the present study, we validated markedly increased lactate abundance in peripheral samples and lung tissues of multiple ARDS patients and multiple ALI mouse models. Administration of glycolysis inhibitor 2-DG to deplete endogenous lactate effectively mitigated lung injury and alveolar epithelial barrier dysfunction, whereas exogenous lactate supplementation significantly worsened these pathological manifestations. Genetic silencing of pulmonary LDHA via intratracheal injection of AAV9-shLdha successfully reproduced the protective phenotypes conferred by 2-DG treatment. Mechanistically, accumulated lactate facilitated Tip60-dependent lactylation modification of YY1 at lysine 183. Biochemical assays confirmed that YY1 K183 lactylation inhibited the expression of PGC-1α at transcriptional level, further causing mitochondrial homeostasis disorder and destruction of alveolar epithelial barrier. In vivo rescue experiments using lactylation-deficient YY1-K183R mutant verified the essential pathogenic role of this site-specific lactylation in LPS-triggered ALI progression. Additionally, we established two feasible translational therapeutic strategies, including K183-targeted cell-penetrating peptide and glycyrrhizin screened from compound libraries. Both candidates efficiently suppressed YY1 K183 lactylation, restored PGC-1α expression and mitochondrial function, and relieved pulmonary edema, inflammatory infiltration and cell apoptosis. In summary, lactate-driven YY1 K183 lactylation disrupts PGC-1α-mediated mitochondrial quality control and epithelial barrier stability. Intervening this lactate-YY1 lactylation axis provides a reliable and promising therapeutic direction for clinical treatment of ALI and ARDS.