Cx43 Regulates The Barrier Function Of Alveolar Type Ⅱ Epithelial Cells In Acute Lung Injury Through Ser373 Mediated By PKA

Objective:To observe the relationship between connexin43(Cx43)expressed by alveolar type Ⅱ epithelial cells in sepsis acute lung injury and the permeability of the alveolar air-blood barrier,and to verify how Cx43 regulates septic acute lung injury through the PKA signaling pathway.Methods:Cell level: Divided into four groups: control group,sepsis(LPS)group,LPS+PKA inhibitor(H89)group,and PKA activator(8-Bromo-c AMP)group.First,Westernbloting was used to detect the expression levels of p-Ser373,PKA and p-PKA in A549 cells.Secondly,A549 cells were cultured on a transwell plate.After they were cultured into a single layer of cells,they were divided into the top four groups again.In each group,the same concentration of drugs was added again,and finally FITC-labeled dextran was passed through,and the fluorescence value was read through the FITC channel with a microplate reader to illustrate the permeability of A549 monolayer cells.Results:Compared with the control group,the expression levels of p-Ser373,PKA and p-PKA in the sepsis group were significantly increased(P<0.05),and the permeability of A549 cells in the sepsis group was increased(P < 0.05);Compared with the sepsis group,the expression of p-Ser373 in the LPS+PKA inhibitor(H89)group was reduced(P<0.05),The expression of p-PKA increased(P<0.05),the expression of PKA decreased(P<0.05),and the permeability of A549 cells was significantly reduced(P < 0.05);Compared with the sepsis group,the expression of p-Ser373 in the PKA activator(8-Bromo-c AMP)group was reduced(P<0.05),and the expression of p-PKA was reduced(P<0.05),The expression of PKA was significantly increased(P < 0.05),and the permeability of A549 cells was significantly increased(P<0.05).Conclusion:The expression levels of p-Ser373,PKA and p-PKA expressed by alveolar type Ⅱepithelial cells in sepsis acute lung injury increased significantly,and the permeability of the alveolar air-blood barrier increased.The application of PKA inhibitor(H89)can reduce the phosphorylation level of Cx43 and at the same time reduce the destruction of sepsis on the alveolar epithelial barrier.It also proves that acute lung injury in sepsis can induce the expression of p-Ser373 through the PKA pathway,further improve the mechanism of acute lung injury in sepsis.