Electroacupuncture Preconditioning Attenuates Acute Myocardial Ischemia Injury Through Inhibiting NLRP3 Inflammasome Activation And Macrophages Polarization In Mice

Objective:Electroacupuncture preconditioning(EAP)effectively reduces myocardial ischemia(MI)injury,but its mechanism has not been fully elucidated.There was increasing evidence that the inflammatory response directly affected the remodeling of ventricular function after infarction,in which activation of inflammasome and macrophage polarization played an important role in this process.Therefore,this study intends to explore the possible mechanism of electroacupuncture preconditioning to reduce MI damage from the perspective of regulating activation of NLRP3 inflammasome and macrophage polarization.Methods:C57BL/6 mice were randomly divided into 4 groups:normal group(Ctrl),normal electroacupuncture preconditioning group(EA+Ctrl),myocardial ischemia model group(MI),and myocardial ischemia after electroacupuncture preconditioning group(EA+MI).A model of acute myocardial ischemia was established by ligating the left anterior descending coronary artery(LAD)of the mouse;the pretreatment method was electroacupuncture at "Neiguan" acupoints,electroacupuncture frequency was set at 2 Hz/15 Hz with sparse and dense wave,intensity level was selected by 2 mA for 20 min daily for 3 days.Echocardiography and TTC staining were used to evaluate the cardiac function and myocardial infarction area in MI mice after 24 hours of ischemia;HE staining and immunohistochemistry were used to observe the inflammation level in the cardiac infarction area of mice,and western blot was used to detect the activation of NLRP3 inflammation;flow cytometry was used to detect the macrophage polarization and neutrophil infiltration.Results:(1)The proportion of myocardial infarction area and cardiac function in MI group were decreased compared with the Ctrl group;the proportion of myocardial infarction area and cardiac function in EA+MI group were increased compared with the MI group;the degree of inflammatory infiltration in the infarct area of the EA+MI group was decreased compared with the MI group;(2)The protein levels of NLRP3,cleaved caspase-1 and IL-1β in MI group were significantly increased compared with the Ctrl group;the protein levels of NLRP3,cleaved caspase-1 and IL-1β in EA+ MI group were significantly decreased compared with the MI group;(3)Compared with the Ctrl group,the heart and spleen macrophages,neutrophils and M1 macrophages in the MI group were significantly increased,and the M2 macrophages were significantly decreased;compared with the MI group,the heart and spleen macrophages,neutrophils and M1 macrophages in the EA+MI group were significantly decreased,and the M2 macrophages were significantly increasedConclusion:EAP inhibits the activation of NLRP3 inflammasome,promotes M2 polarization of macrophages and reduces the recruitment of neutrophils,thereby decreases the infarct size and improves the cardiac function.