Background: Impaired cardiac microvascular function has been implied in the pathophysiology of diabetic cardiovascular disease. However, the specific mechanism remains to be determined. Pyroptosis is a type of cell death that differs from apoptosis and autophagy. It is caused by the formation of plasma membrane pores through amino-terminal fragments of Gasdermin D (GSDMD), leading to the secretion of IL-1β and IL-18. Recent studies have shown that irisin, a myokine cleaved by the extracellular domain of FNDC5, plays a protective role in cardiovascular diseases. Here, we investigated the potential role of pyroptosis on the cardiac microvascular endothelial cells (CMECs) injury induced by high glucose (HG) and further determined the protective effect of irisin on pyroptosis.
Methods: CMECs were cultured with normal glucose (control group, 5.5 mM) and high glucose (25 mM) medium for 12, 24, and 48 h respectively. The pyroptosis of CMECs was measured by immunofluorescence staining, ELISA, and Western blot assays. Moreover, the apoptosis level was determined by flow cytometry and TUNEL staining.
Results: Our results showed that HG promoted apoptosis and pyroptosis. However, irisin reversed the increased apoptosis and pyroptosis. To investigate the underlying mechanism, we overexpressed the NLRP3 protein. We found the protective effect of irisin on apoptosis and pyroptosis was abolished by NLRP3 over-expression.
Conclusions: Our data suggest that irisin protects CMECs against apoptosis and pyroptosis, at least in part, by inhibiting NLRP3 inflammasome.