Tectorigenin reprograms macrophages through targeting OXCT1-mediated ketone metabolism to suppress IFN-I signaling and ameliorate myocardial ischemia-reperfusion injury

Myocardial ischemia/reperfusion (I/R) injury persists as a pivotal unresolved bottleneck in treating acute myocardial infarction. Post-reperfusion inflammation, driven by macrophage metabolic and functional reprogramming, exacerbates this injury. Tectorigenin (TEC), an active component of Belamcanda chinensis , exerts marked cardioprotection against myocardial I/R injury by targeting macrophage-mediated inflammation. TEC significantly improved cardiac function, reduced infarct size, and suppressed cardiomyocyte apoptosis. RNA sequencing (RNA-seq) identified the type I interferon (IFN-I) signaling pathway as a key target. Mechanistically, TEC reduced macrophage reactive oxygen species (ROS) levels and upregulated the transcriptional repressor basic helix-loop-helix family member e41 (BHLHE41). BHLHE41 subsequently suppressed expression of the cytosolic RNA sensor melanoma differentiation-associated protein 5 (MDA5), encoded by IFN induced with helicase C domain 1 ( Ifih1 )), thereby blocking downstream activation of TANK-binding kinase 1 (TBK1) and IFN regulatory factor 3 (IRF3) to reduce IFN-β production. Moreover, multiple orthogonal assays identified 3-oxoacid CoA-transferase 1 (OXCT1), a crucial enzyme involved in ketone body metabolism, as a direct target of TEC, with TRP413 serving as the critical binding residue. This interaction promotes lysosomal degradation of OXCT1 and elevates intracellular ketone body levels, which enhance Bhlhe41 messenger RNA (mRNA) stability and inhibit MDA5-dependent IFN-I signaling. Exogenous ketone body supplementation mimicked these effects, while genetic knockdown of Oxct1 or Bhlhe41 confirmed their pivotal roles in regulating macrophage activation. Collectively, this study identifies a novel macrophage OXCT1-BHLHE41-MDA5 axis modulating IFN-I-driven inflammation during I/R injury, establishes TEC as a promising therapeutic agent, and highlights ketone metabolism as a potential cardioprotective target.