The Effect And Mechanism Of PXR In Aristolochic Acid Induced Acute Kidney Injury

BackgroundAcute Kidney injury is a severe clinical syndrome charactered by rapidly decrease renal function and extensive renal tubular injury,finally resulting in multiple organ injury and high mortality.AKI mainly caused by nephrotoxins,sepsis,and renal ischemia-reperfusion.Proximal tubular epithelial cells(PTECs)are the main target of AKI,presenting significant changes in metabolic pathways,cell signaling and cell cycle.Pregnancy X receptor(PXR)is a key regulator of drug metabolism,participating in the regulation of apoptosis,cell proliferation,cell migration,inflammatory response and glucose and lipid metabolism,and is involved in a variety of diseases.Studies have found that PXR plays an important role in kidney disease,but the specific role and mechanism of PXR in AKI are still not fully understood.This study will explore the role and mechanism of PXR in aristolocholic acid induced acute kidney injury through in vivo and in vitro experiments.Objective:To investigate the role and possible mechanism of PXR in aristolochic acid-induced acute kidney injury,which may provide a new therapeutic target for acute kidney injury.Methods:1.AKI model: Proximal tubular cells(The Boston University mouse Tubular cell line,BUMPT cells)were treated with aristolochic acid(AA)(20ug/ m L)for 24 h,then were collected to detecte the expression of PXR.AA(10mg/kg)was injected intraperitoneally once to male C57BL/6 mice to establish AKI model.After four days,the mice were sacrificed to collect kidney and detect the expression of PXR.2.Role of PXR in vitro: PXR overexpression cell lines were constructed and treated with AA(20ug/ m L)for 24 h,then were collected to detect apoptosis.3.Role of PXR in vivo: 1)Effects of PCN(mouse PXR specific agonist)on AKI.The mice were divided into three groups: a.Control group;b.AA group;c.AA + PCN group.Mice were pretreated via oral gavage daily with PCN(50 mg/kg)for 4 days.A single dose of AA(10mg/kg)was administrated intraperitoneally(i.p.)to mice on Day 4,and then the daily PCN treatment was continued for 3 days.Mice were sacrificed 4 days after AA injection.the kidney and serum were collected to detecte the apoptosis,histopathological injury and serum creatinine.2)Effects of ketoconazole(KTZ,mouse PXR inhibitor)on AKI.The mice were divided into three groups: a.Control group;b.AA group;c.AA+KTZ group.Mice were pretreated via oral gavage daily with KTZ(50 mg/kg)for 2 days.A single dose of AA(10 mg/kg)was administrated intraperitoneally(i.p.)to mice on Day 2,and then the daily KTZ treatment was continued for 2 days.Mice were sacrificed 3 days after AA injection,the kidney and serum of mice were collected to detect the apoptosis,histopathological injury and serum creatinine.4.Mechanism: The binding of PXR and p53 was detected through immunoprecipitation(CO-IP)in BUMPT cells.In AA-induced AKI,the effect of PXR on p53 expression was detected.Results:1.The expression of PXR decreased after AA treatment in BUMPT cells and kidney tissues of mice.2.Overexpression of PXR in BUMPT cells alleviated AA-induced apoptosis.3.PCN attenuated AA-induced AKI,while KTZ exacerbated AA-induced AKI.4.In BUMPT cells,PXR interacted with p53 and overexpression of PXR inhibited AA-induced up-regulation of p53.In mice,PCN also suppressed the up-regulation of p53.Conclusion:PXR protects aganist aristolocholic acid-induced acute kidney injury through supression of p53.