Melatonin prevents endothelial cell pyroptosis via regulation of long noncoding RNA MEG3/miR-223/NLRP3 axis

OBJECTIVE Atherosclerosis(AS) is an inflammatory disease linked to endothelial dysfunction.Melatonin is reported to possess substantial anti-inflammatory properties, which has proven to be effective in AS. Emerging literature suggests that pyroptosis plays a critical role during AS progression. However, whether pyroptosis contributes to endothelial dysfunction and the underlying molecular mechanisms remained unexploited.This study was designed to investigate the antipyroptotic effects of melatonin in atherosclerotic endothelium and to elucidate the potential mechanisms. METHODS ApoE-/-mice were fed a high-fat diet to establish an atherosclerotic model, then divided into normal diet(ND) group, normal diet+melatonin(ND+melatonin) group, high fat diet(HFD)group and high fat diet+melatonin(HFD+melatonin) group.After 12 weeks, HE and oil Red O staining were used to detect the formation of atherosclerosis; qRT-RCR and Western blotting were used to detect the expression of NLRP3, ASC, IL-1β, IL-18, GSDMD, NF-κB, miR-223 and MEG3 in aortic endothelium; The luciferase assay was used to detect the binding of mi R-223 to MEG3. Human aortic endothelial cells(HAECs) were pretreated with ox-LDL. After melatonin treatment, qRT-RCR was used to detect the expression of mi R-223 and MEG3. Western blotting was used to detect NLRP3, ASC, c-caspase1,p-caspase1, GSDMD expression. In addition, after overexpressing MEG3 and knocking out mi R-223, the pyroptosis of HAECs was also detected. RESULTS We found intragastric administration of melatonin for 12 weeks markedly reduced the atherosclerotic plaque in aorta.Meanwhile, melatonin also attenuated the expression of pyroptosis-related genes, including NLRP3, ASC,cleaved caspase1, NF-κB/GSDMD, GSDMD N-termini,IL-1β, and IL-18 in aortic endothelium of melatonin-treated animals. Consistent antipyroptotic effects were also observed in ox-LDL-treated human aortic endothelial cells(HAECs). We found that lnc RNA MEG3 enhanced pyroptosis in HAECs. Moreover, MEG3 acted as an endogenous sponge by sequence complementarity to suppress the function of mi R-223 and to increase NLRP3 expression and enhance endothelial cel pyroptosis. Furthermore, knockdown of mi R-223 blocked the antipyroptotic actions of melatonin in ox-LDL-treated HAECs. CONCLUSION Our results suggest that melatonin prevents endothelial cell pyroptosis via MEG3/mi R-223/NLRP3 axis in atherosclerosis, and therefore, melatonin replacement might be considered a new strategy for protecting endothelium against pyroptosis, thereby for the treatment of atherosclerosis associated with pyroptosis.