A novel S100A-TLR3-IFIT3 signaling axis promotes cardiomyocyte apoptosis during myocardial infarction

Ischemic cardiomyopathy is associated with myocardial injury and increased mortality. During myocardial infarction (MI), necrotic cardiomyocytes release damage-associated molecular patterns (DAMPs) that trigger inflammatory responses, yet the specific cardiac alarmins and downstream mechanisms driving cardiomyocyte apoptosis remain unclear. In this study, we identified endogenous S100 protein isoforms as key cardiac alarmins released during myocardial ischemic injury and elucidated their role in activating IFIT3 overexpression through innate immune signaling pathways. Mining patient biopsy expression data and verifying a rat model of left anterior descending (LAD) artery occlusion, we validated IFIT3 overexpression in both human and rodent cardiac tissues during acute myocardial infarction (AMI). To investigate the functional role of IFIT3, we employed CRISPR-Cas9 gene-editing technology to knock out IFIT3 in AC-16 human cardiac cells and developed a continuous oxygen-glucose deprivation/reperfusion (OGD/R) model to mimic MI at the cellular level. IFIT3 knockout significantly inhibited apoptosis induced by OGD/R and carbonyl cyanide m-chlorophenyl hydrazone (CCCP), as detected by Annexin V-FITC/PI double staining. Mechanistically, we utilized Type I interferons, TLR agonists, and STING agonists to dissect the dominant DAMP signaling pathway, revealing that S100 proteins activate IFIT3 overexpression through the TLR3/TICAM1/IRF3 pathway, thereby promoting cardiomyocyte apoptosis. This research establishes a novel S100-TLR3-IFIT3 signaling axis in the pathophysiology of ischemic cardiomyopathy, providing new mechanistic insights and potential therapeutic targets for myocardial ischemic injury.