GSDMD-Mediated Cardiomyocyte Pyroptosis Promotes Myocardial I/R Injury.

Rationale: Pyroptosis is a morphologically and mechanistically distinct form of cell death and is characterized by gasdermin D (GSDMD) or gasdermin E (GSDME)-mediated necrosis with excessive inflammatory factor release. Cardiomyocyte necrosis and inflammation play key roles in the pathophysiology of myocardial ischemia/reperfusion (I/R) injury. However, whether cardiomyocytes undergo pyroptosis and the underlying mechanism in myocardial I/R injury remain unclear. Objective: We aimed to investigate the role of pyroptosis in myocardial I/R injury. Methods and Results: In vivo and in vitro experiments were used to investigate pyroptosis of cardiomyocyte and the associated mechanisms during I/R injury. Wild-type (WT), Myh6-Cre and cardiomyocyte-specific GSDMD-deficient (GSDMD-CKO) male mice were subjected to I/R. Human peripheral blood samples were collected from STEMI (acute ST-segment-elevation myocardial infarction) patients or control patients at 0, 1 and 24 h after PCI (percutaneous coronary intervention) in our department. The serum levels of GSDMD were measured by ELISA. H/R (hypoxia/reoxygenation) induced cardiomyocyte pyroptosis and the release of mature IL-18 but not IL-1β, which mechanistically resulted from GSDMD cleavage by caspase-11 in cardiomyocytes. Furthermore, GSDMD gene deletion blocked H/R-induced cardiomyocyte pyroptosis and IL-18 release. GSDMD and its pyroptosis-inducing N-terminal fragment (GSDMD-N) were upregulated in myocardial tissues after I/R injury. Immunofluorescence analysis showed that GSDMD was mainly localized in cardiomyocytes. GSDMD deficiency in cardiomyocytes significantly reduced the I/R-induced myocardial infarct size. Moreover, increased GSDMD serum levels were detected in patients exhibiting I/R injury 1 h after PCI for STEMI. Conclusions: Our results show that GSDMD-mediated cardiomyocyte pyroptosis is a key event during myocardial I/R injury and that the caspase-11/GSDMD pathway may be essential to this process. Additionally, GSDMD inhibition significantly reduces cardiomyocyte pyroptosis and I/R-induced myocardial injury.