RBP4 induces pyroptosis in cardiomyocytes via activating NLRP3/Caspase-1/GSDMD pathway in acute myocardial infarction

Aims Myocardial infarction (MI) is the most common cause of cardiac morbidity and mortality worldwide. Pyroptosis is a novel form of inflammatory cell death that could be driven by the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation following MI. Retinol binding protein 4 (RBP4) is an pro-inflammatory adipokine with adverse effects on cardiovascular system. We investigated the role and underlying mechanism of RBP4 in inducing pyroptosis in cardiomyocytes in acute MI. Methods and results We established a mice MI model which ligated with the left anterior descending coronary artery and a cardiomyocytes injury model treated by oxygen-glucose deprivation (OGD). Western blot showed that RBP4 expression was exclusively increased in the heart following MI, as RBP4 expression remains unchanged in adipose tissues and liver. Cardicac pyroptosis was induced in MI mice as evidenced by increased expression of pyroptosis-related proteins, including NLRP3, Caspase-1, gasdermin D (GSDMD), IL-1β and IL-18. Moreover, increased cardiac RBP4 level was positively correlated with serum IL-1β and IL-18 levels in MI mice. Immunofluorescence identified that RBP4 was expressed in cardiomyocytes and was up-regulated along with increased pyroptosis-related proteins after treatment with OGD. Transfection of RBP4 adenovirus promoted pyroptosis while inhibition of RBP4 ameliorated OGD-induced pyroptosis in cardiomyocytes. Mechanically, transfection of NLRP3 siRNA or GSDMD siRNA along with RBP4 adenovirus could attenuate RBP4-induced pyroptosis in cardiomyocytes. Furthermore, in situ injection of adenovirus containing RBP4 siRNA could also attenuate pyroptosis and cardiac inflammation following MI in mice. Conclusion RBP4 is presented in cardiomyocytes and induces cardiac pyroptosis via activating NLRP3/Caspase-1/GSDMD pathway in acute MI Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): National Nature Science Foundation of China