Lipopolysaccharide Mediates the Destruction of Intercellular Tight Junction among Renal Tubular Epithelial Cells via RhoT1/SMAD-4/JAM-3 Pathway

Abstract

Background: The morbidity of sepsis induced acute kidney injury remains unacceptable high and the mechanisms of that disease remains unclear. For urine backleak and intercellular tight junction among tubular epithelial cells (TECs) destruction often occur during sepsis induced acute kidney injury, we examined whether lipopolysaccharide could damage intercellular tight junction among TECs and associated mechanisms in our present study. Methods: HK-2 cells were cultured, transfected with different SiRNAs and stimulated with LPS and PYR-41. Transepithelial Permeability Assay and Transepithelial Electrical Resistance Assay were used to evaluate intercellular tight junction destruction and Western Blot and Immunofluorescence were used to evaluate proteins expression. Results: Transepithelial Permeability increased significantly (P<0.05) and Transepithelial Electrical Resistance reduced remarkably (P<0.05) of the monolayer TECs stimulated with LPS. The expression of JAM-3 and RhoT1 decreased significantly (P<0.05) in TECs stimulated with LPS, while the level of SMAD-4 increased significantly (P<0.05). Downregulation of the expression of SMAD-4 with RNA interference could increase the expression of JAM-3 in LPS treated TECs. Moreover, upregulation of RhoT1 level by decreased the degradation of RhoT1 could decrease the expression of SMAD-4 and increase the JAM-3 level in TECs treated with LPS, while downregulation of RhoT1 level with RNA interference had the opposite effects. Conclusion: LPS mediates intercellular tight junction destruction among TECs and RhoT1/SMAD-4/JAM-3 is a pivotal pathway to mediate the phenomenon.