Lactate/AARS1-mediated H3K18la in the modulation of ACSL4 transcription to trigger ferroptosis in myocardial ischemia reperfusion

OBJECTIVE: Hypertension serves as a pivotal risk factor for myocardial ischemia reperfusion injury (MIRI). Reciprocally, MIRI exacerbates hypertension by inducing oxidative stress, inflammatory responses, cardiomyocyte death, fibrosis-associated myocardial remodeling, and RAAS system disruption, forming a vicious feedback cycle. This study aimed to investigate the regulatory role and underlying molecular mechanism of the lactate-related signaling axis in cardiomyocyte ferroptosis during MIRI, and to identify novel potential therapeutic targets for interrupting this detrimental feedback loop. METHODS: cardiomyocyte oxygen‒glucose deprivation/reoxygenation (OGD/R) models, and spontaneously hypertensive rat (SHR) models were successfully established. Oxaloacetate and β-alanine were administered to inhibit lactate production and protein lactylation, respectively. Hematoxylin‒eosin (HE) and Masson staining were performed to evaluate myocardial histopathological damage and fibrosis. Immunohistochemistry (IHC) and Western blotting were used to detect the protein expression levels of lysine lactylation (Kla), H3K18la, alanyl-tRNA synthetase 1 (AARS1), and acyl-CoA synthetase long-chain family member 4 (ACSL4). An enzyme-linked immunosorbent assay (ELISA) was adopted to quantify the lactate content and ferroptosis-related marker levels. Transmission electron microscopy (TEM), immunofluorescence staining, and chromatin immunoprecipitation (ChIP) assays were separately utilized to observe the mitochondrial ultrastructure, assess cellular lipid peroxidation, and verify gene promoter enrichment. RESULTS: Lactate, Kla, and H3K18la levels were markedly elevated in the MIRI and OGD/R models, accompanied by severe myocardial injury, fibrosis, and excessive cardiomyocyte ferroptosis. Inhibition of lactate production effectively reduced lactylation levels and mitigated ferroptosis as well as myocardial structural damage. Mechanistically, H3K18la was enriched in the promoter region of ACSL4 to facilitate its transcriptional activation, and knockdown of ACSL4 markedly reversed OGD/R-triggered cardiomyocyte ferroptosis. AARS1 overexpression strengthened lactylation and ACSL4 expression to promote ferroptosis, while its mutant did not. Notably, hypertension aggravated MIRI, promotes further increases in the level of histone lactylation mediated by AARS1, and exacerbates ferroptosis. Pharmacological intervention with β-alanine blocked the lactate/AARS1/H3K18la/ACSL4 axis and attenuated MIRI-induced myocardial damage. CONCLUSION: Abnormal lactate accumulation facilitates H3K18la modification via AARS1-dependent regulation, which transcriptionally activates ACSL4 and modulates cardiomyocyte ferroptosis, ultimately contributing to the pathological progression of MIRI. Targeting the lactate/AARS1/H3K18la/ACSL4 regulatory axis is a promising and viable therapeutic strategy for MIRI intervention.