[Retracted] Exosomal miR‐27b‐3p Derived from Hypoxic Cardiac Microvascular Endothelial Cells Alleviates Rat Myocardial Ischemia/Reperfusion Injury through Inhibiting Oxidative Stress‐Induced Pyroptosis via Foxo1/GSDMD Signaling

Abstract

Background . Exosomes derived from cardiac microvascular endothelial cells (CMECs) under hypoxia can mediate cardiac repair functions and alleviate pyroptosis and oxidative stress during ischemia‐reperfusion (I/R) injury. This study is aimed at investigating the effect and mechanism of miR‐27b‐3p underlying hypoxic CMECs‐derived exosomes against I/R injury. Methods . CMECs were isolated from the left ventricle of Sprague‐Dawley rats, followed by culturing under hypoxic conditions or pretreatment with the miR‐27b‐3p inhibitor. CMECs‐derived exosomes were added into H9C2 cells before hypoxia/reoxygenation (H/R) or injected into the rat heart before I/R injury. An in vivo I/R injury model was established by ligating and releasing the left anterior descending coronary artery. Expression of pyroptosis‐related factors was detected using Western blot, and heart infarcted size was determined by the 2,3,5‐triphenyl‐2H‐tetrazpinolium chloride staining method. Dual‐Luciferase Reporter assays were performed to analyze the interactions of nmiR‐27b‐3p‐forkhead box O1 (Foxo1) and Gasdermin D‐ (GSDMD‐) Foxo1. Chromatin‐immunoprecipitation (ChIP) assays were performed to validate the interactions between forkhead box O1 (Foxo1) and Gasdermin D (GSDMD) and Foxo1‐mediated histone acetylation of GSDMD. Results . CMECs were successfully identified from left ventricle of Sprague‐Dawley rats. The expressions of Foxo1 and pyroptosis‐related proteins (GSDMD, NLPR3, cleaved caspase 1, IL‐1 β, and IL‐18) were upregulated in the rat heart after I/R injury. Treatment of CMEC‐derived exosomes, especially that under hypoxic conditions, significantly reduced pyroptosis in the rat heart. miR‐27b‐3p was significantly upregulated in CMEC‐derived exosomes under hypoxic conditions, and miR‐27b‐3p inhibition in exosomes alleviated its cytoprotection and inhibited oxidative stress in H9C2 cells. Treatment with Foxo1 overexpression plasmids aggravated in vitro H/R and in vivo I/R injury by upregulating pyroptosis‐related proteins. Further experiments validated that miR‐27b‐3p negatively targeted Foxo1, which bound to the promoter region of GSDMD. Conclusions . These results demonstrated a great therapeutic efficacy of miR‐27b‐3p overexpression in hypoxic CMEC‐derived exosomes in preventing the development of myocardial damage post I/R injury through inhibiting Foxo1/GSDMD signaling‐induced oxidative stress and pyroptosis.