TMAO Aggravates Myocardial Ischemia-Reperfusion Injury by Sustaining PERK/eIF2α Activation and Impairing FDXR-Dependent Mitochondrial Function

Alleviating myocardial ischemia-reperfusion injury (MIRI) is pivotal for improving acute myocardial infarction (AMI) prognosis. Identifying risk factors exacerbating MIRI may provide novel mitigation strategies. Previous clinical studies demonstrate that individuals with elevated plasma trimethylamine N-oxide (TMAO) levels suffer worse myocardial injury following AMI. However, whether TMAO promotes MIRI remained undefined. This study addressed this question and demonstrated that exogenous TMAO administration exacerbated MIRI in both in vivo mouse ischemia-reperfusion (IR) models and in vitro primary cardiomyocyte hypoxia/reoxygenation (HR) models. RNA sequencing (RNA-Seq) and gene set enrichment analysis (GSEA) indicated that TMAO suppressed mitochondrial function-related pathways. Further in vitro and in vivo experiments confirmed TMAO aggravated mitochondrial dysfunction during IR, manifested as ultrastructural damage, reduced mitochondrial membrane potential (ΔΨm), elevated ROS overproduction, and profound energy metabolism impairment. Mechanistically, TMAO-induced mitochondrial dysfunction was mediated through FDXR suppression, as FDXR overexpression reversed TMAO-mediated injury. TMAO directly bound PERK and sustained PERK/eIF2α pathway activation during IR. Pharmacological inhibition of PERK/eIF2α signaling (using GSK2606414 and ISRIB) reversed TMAO-induced FDXR suppression, mitochondrial dysfunction, and MIRI exacerbation, establishing the dependence of these effects on PERK/eIF2α signaling. Taken together, TMAO exacerbates MIRI by maintaining PERK/eIF2α activation, thereby driving FDXR-dependent mitochondrial dysfunction. This identifies TMAO as a risk factor for MIRI and the PERK/eIF2α/FDXR axis as a therapeutic target for TMAO-mediated injury.