RESUMO
Objective To investigate the possible role and mechanism of activation of pyroptosis classical pathway and alterations in cell adhesion in calcium-containing kidney stones after the action of high concentration of Ca2+ on HK-2 cells.Methods HK-2 cells were cultured in the presence of different concentrations of CaCl2(0,0.1,0.5,1.0,2.0,4.0 and 8.0 g/L)for 24 hours,and cell counting Kit-8(CCK-8)and flow cytometry were used to determine the optimal treatment concentration.Subsequently,the ultrastructure of renal tubular epithelial cells under high Ca2+ condition was observed by transmission electron microscopy after Ca2+ treatment.DCFH-DA staining was used to detect intracellular reactive oxygen species production,and quantitative real-time polymerase chain reaction(qRT-PCR)and Western blot analysis were performed to examine the expression of pyroptosis-related proteins NLRP3,Caspase-1,gasdermin D(GSDMD),adhesive molecules osteopontin(OPN)and CD44 at mRNA and protein levels after high concentration Ca2+ treatment.The expression levels of pyroptosis-related inflammatory factors interleukin(IL)-1β,IL-18 and adhesive molecule monocyte chemotactic protein-1(MCP-1)were detected by enzyme-linked immunosorbent assay(ELISA)after high Ca2+ stimulation.Results Ca2+ showed cytotoxicity for HK-2 cell growth and can promote apoptosis.The higher the Ca2+ concentration,the more toxicity and apoptosis rate for HK-2 cell growth.High concentration of Ca2+ can promote pyroptosis-like morphological changes in HK-2 cells,including loss of cell membrane integrity,release of contents and numerous intracellular vacuoles.Compared with the control group,the expression levels of ROS were sequentially increased in the 1.0 g/L CaCl2 group and the 2.0 g/L CaCl2 group,and the expression levels of pyroptosis-related genes NLRP3,Caspase-1,GSDMD,and the pyroptosis-associated inflammatory factors IL-1β and IL-18,as well as the adhesion molecules OPN,CD44 and MCP-1 were significantly increased(P＜0.05).Conclusion High Ca2+ treatment can cause oxidative stress damage in HK-2 cells to produce ROS,which activates NLRP3 inflammasome,leads to the activation of the classical pathway of pyroptosis and increase the adhesion of cells,and ultimately leads to the formation of kidney stones.