SHEP1 alleviates cardiac ischemia reperfusion injury via targeting G3BP1 to regulate macrophage infiltration and inflammation

Background: The macrophage-associated inflammation response plays an important role in myocardial ischemia-reperfusion injury (MIRI). During MIRI, the role and molecular mechanism of SHEP1 regulating macrophage remains unclear. Methods: By co-cultured with hypoxia reoxygenation cardiomyocytes in vitro, macrophages with SHEP1 knockout or overexpression were detected cell migration ability and related proinflammatory factors; and the molecular network regulated by SHEP1 was identified through transcriptome-wide analysis; then its target molecules were verified by co-immunoprecipitation method. In vivo, an ischemia-reperfusion heart model was established to observe the changes in cardiac function, cardiac tissue injury and inflammation of macrophage-specific deficiency of SHEP1 mice, and to analyze the improvement of cardiac function by administrating inhibitors for targeted molecules of SHEP1. Findings: The expression of SHEP1 was increased in macrophages co-cultured with hypoxia-reoxygenated cardiomyocytes and within ischemia-reperfusion injured myocardium at the early stage of injury. Cell migration and inflammation were also enhanced in SHEP1 knock-out macrophages and macrophage-specific deficiency of SHEP1 mice under MIRI, which further led to deteriorated cardiac injury and cardiac function in vivo. RNA-sequencing and co-immunoprecipitation mass spectrometry showed that macrophage-derived SHEP1 competitively bound to G3BP1 to suppress inflammation via the MAPK pathway. And administrating inhibitor of G3BP1 could improve cardiac function in macrophage-specific deficiency of SHEP1 mice under MIRI. Conclusions: SHEP1 targeted G3BP1 to antagonize cardiac ischemia-reperfusion injury by inhibiting infiltration and proinflammatory responses of macrophages, which provided a potential and clinically significant therapeutic target for MIRI.