MiR-15a-5p in neutrophil exosomes promotes macrophage apoptosis through targeted inhibition of BCL2L2

Objective:To explore the possible mechanism of neutrophil exosomes regulating macrophage apoptosis.Methods:neutrophils were induced by lipopolysaccharide,inflammatory factors were detected by ELISA,the morphology of exosomes was identified by electron microscope,and the expression of mir-15a-5p in exosomes was detected by RT-PCR;Raw267.4 macrophages was treated with neutrophil exosomes and mir-15a-5p mimic respectively,CCK8 to detect cell viability,flow cytometry to detect apoptosis;The binding sites of mir-15a-5p and BCL2L2 were predicted and verified by double luciferase experiment;RT-PCR and Western blot verified that mir-15a-5p regulate the expression of BCL2L2.Results:lipopolysaccharide induced neutrophil inflammatory factors IL-2,IL-6,IL-10 and TNF-α.The morphological characteristics of exosomes were observed by electron microscope.Mir-15a-5p was significantly overexpressed in neutrophil exosomes induced by lipopolysaccharide;Lipopolysaccharide-induced neutrophil exosomes and mir-15a-5p simulants can promote raw267.4 macrophage apoptosis and inhibit its cell viability;Targetscan database predicted that mir-15a-5p and BCL2L2 had binding sites.Double-luciferase experiment verified that mir-15a-5p and BCL2L2 bound through binding sites;Mir-15a-5p mimic was transfected into raw267.4 macrophages which inhibit the expression of BCL2L2 mRNA and protein.Conclusion:inflammatory neutrophils may promote raw267.4 by secreting exosomes containing mir-15a-5p and inhibiting BCL2L2 by targeting macrophage apoptosis.This may provide a theoretical basis for further understanding the molecular mechanism of inflammatory regulation of neutrophils and macrophages.