MicroRNA-206 Influences Permeability Of Alveolar Type ? Epithelial Cells With LPS Stimulation By Inhibiting Expression Of Connexin 43

Objective:To investigate the relationship between connexin43(Cx43)expressed in alveolar type ? epithelial cells(AT?)and the permeability of alveolar air-blood barrier,and the effect of microRNA-206(miR-206)on the expression of Cx43 in sepsis-induced acute lung injury.Methods:The animal experiments were divided into sham group,CLP group,CLP + Cx43 inhibitor(Cx43-In)group and CLP + miR-206 agomir(miR-206-Mi)group.The method of cecal ligation and puncture(CLP)was used to prepare an acute lung injury model of sepsis.Six hours after successful modeling,the lung tissues were taken for HE staining,wet to dry weight ratio(W/D)and the protein content in bronchoalveolar lavage fluid(BALF)was measured.The content of Cx43 in the lung tissues was determined by immunohistochemistry and Western blot.Additionally,the expression of microRNA-206 and Cx43 mRNA in the lung tissues was detected by RT-qPCR).The rat alveolar type II epithelial cells were cultured on transwell plates for establishing the cell monolayer.The cell monolayer was pretreated with Cx43 mRNA inhibitor and microRNA-206 analogs,and then treated with lipopolysaccharide(LPS).The fluorescence intensity of fluorescein-labeled dextran(FITCdextran)was used to judge the permeability of the monolayer cells.The dual luciferase reporter gene assay was used to investigate whether microRNA-206 targeted the 3 ? noncoding region of Cx43 mRNA to regulate Cx43 expression,thereby regulating the permeability of the alveolar air-blood barrier.Results:Compared with sham group,HE staining revealed that damage of alveolar structure,thickening of alveolar wall,hyperemia and hemorrhage in pulmonary interstitial,infiltration of inflammatory cells,edema in pulmonary interstitial and alveolar space,exudation of neutrophilic and pink edema fluid in alveolar cavities.W/D ratio and the protein concentration in BALF were increased(P<0.05),and the expression of Cx43 at mRNA and protein levels was also increased significantly(P<0.05),and expression of microRNA-206 was decreased(P<0.05).Compared with CLP group,the inflammatory responses in the lung tissues were alleviated,and W/D ratio and protein concentration in BALF were decreased in Cx43-In group and miR-206-Mi group(P<0.05),and the expression of Cx43 at mRNA and protein levels was also decreased significantly(P<0.05).Conclusion:The increase of Cx43 expression in alveolar type II epithelial cells with LPS stimulation leads to an increase in the permeability of the alveolar air-blood barrier.MicoRNA-206 targets Cx43 mRNA 3?UTR to down-regulate the expression of Cx43,which further improves the permeability of the alveolar air-blood barrier.