Uric Acid Induces Inflammatory Injury In HK-2 Cells Via PI3K/AKT/NF-κB Signaling Pathway

BackgroundUric acid is a direct damage factor of renal tubular epithelial cells.Uric acid is an independent risk factor for the progression of renal function and an important indicator for predicting new chronic kidney disease in chronic kidney disease patients.The main mechanism of inflammatory damage in hyperuricemic nephropathy is that free uric acid and uric acid crystals activate the complement system and inflammatory pathways,cause inflammatory cell infiltration,develop renal interstitial inflammation and renal fibrosis,which leading to chronic kidney disease.In the development of hyperuricemic nephropathy,NLRP3 inflammasome,transforming growth factorβ/Smads pathway,p38 mitogen-activated protein kinase pathway,phosphatidylinositol 3-kinase(PI3K)/protein kinase B(AKT)/nuclear factor κB(NF-κB)pathway are involved.The PI3K/AKT/NF-κB pathway plays an important role in inflammatory disease,participates in the differentiation,proliferation,apoptosis and migration in the body.Protein kinase-activated receptor 2(PAR2)is a member of the protein kinase-activated receptor family,and is a target upstream of the PI3K/AKT/NF-κB pathway.In this study,we established a cell model of hyperuricemic nephropathy in vitro and detected the PI3K/AKT/NF-κB pathway expression level.To investigate the effects and underlying mechanisms of PI3K/AKT/NF-κB signaling pathway in human kidney-2(HK-2)cells of hyperuricemic nephropathy.MethodsHK-2 cells were randomly divided into the control and experimental groups in vitro.The experimental group was induced by high uric acid(720 μmol/L)immersion for 48 h to establish a cell model of hyperuricemic nephropathy in vitro and subsequently divided into the hyperuricemic group,overexpressed protease-activated receptor 2(PAR2)and knockdown PAR2 group.The expression of PAR2,PI3K,AKT,NF-κB mRNA were detected by real-time PCR.The expression of PAR2,PI3K,AKT and NF-κB protein were detected by Western blotting.The expression of tumour necrosis factor-α(TNF-α),monocyte chemotactic protein-1(MCP-1),interleukin-6(IL-6),pro-interleukin-1β(pro-IL-1β),interleukin-1β(IL-1β)and transforming growth factor-β1(TGF-β1)were detected by enzyme-linked immunosorbent assay(ELISA).ResultsIn the process of renal tubular epithelial cell hyperuric acid injury,compared with the control group,the expression of PAR2,PI3K,AKT and NF-κB mRNA and protein in the hyperuricemic group were significantly increased(all P<0.05),the production of TNF-α,MCP-1,IL-6,pro-IL-1β,IL-1β and TGF-β1 in the supernatant in the hyperuricemic group were significantly increased(all P<0.01).(2)In the process of renal tubular epithelial cell hyperuric acid injury,compared with the hyperuricemic group,the expressions of PAR2,PI3K,AKT and NF-κB mRNA and protein in the overexpressed PAR2 group were significantly increased(all P<0.05),the production of TNF-α,MCP-1,IL-6,IL-1β and TGF-β1 in the supernatant were significantly increased(all P<0.05),there is no significant difference in pro-IL-1β(P>0.05).(3)In the process of renal tubular epithelial cell hyperuric acid injury,compared with the hyperuricemic group,the expression of PAR2,PI3K,AKT and NF-κB mRNA and protein in the knockdown PAR2 group were significantly decreased(all P<0.05),the production of IL-6,pro-IL-1β IL-1β and TGF-β1 in the supernatant were significantly decreased(all P<0.05),there is no significant difference in TNF-α and MCP-1(P>0.05).ConclusionsIn the process of uric acid-induced HK-2 cell damage,uric acid significantly up-regulates the expression of PI3K/AKT/NF-κB pathway by activating PAR2,leading to a marked increase in inflammatory cytokines.Knocking down PAR2 inhibits the expression of PI3K/AKT/NF-κB pathway,which can effectively reduce the inflammatory damage of HK-2 cells.