Hyperbilirubinemia Aggravates Renal Ischemia Reperfusion Injury And The Potential Mechanism

Object:Extracorporeal membrane oxygenation(ECMO)has been used increasingly in critically ill patients with severe cardiopulmonary failure.However,acute renal failure(ARF)is a severe complication during ECMO support.The aim of this retrospective,single-center study was to investigate risk factors of ARF during ECMO in order to provide theoretical basis for preventing ARF.Method:We analyzed 89 adults requiring ECMO support between December 2010 and October 2015 at Fuwai hospital.All patients were divided into ARF group and Non-ARF group.ARF was defined as>300%rise in serum creatinine concentration from baseline or application of dialysis.Demographics,clinical parameters before ECMO,worst parameters during ECMO and outcomes were collected.Result:The total incidence of ARF was 55.1%.The indication of post heart transplant was higher in ARF group than Non ARF group(P=0.007).The worst parameters during ECMO including TBIL(P=0.002),DBIL(P=0.007),AST(P=0.016),ALT(P=0.004),SCr(P<0.001)and FHB(P<0.001)were higher in ARF group.The maximum vasoactive-inotropic score(VIS,P=0.001),peak epinephrine dose(P=0.003)and peak dopamine dose(P=0.008)were higher in ARF group than these in Non-ARF group.As the result of Logistic analyses FHB(P=0.003)and VIS(P=0.029)were risk factors of ARF during ECMO support.There was a linear correlation between maximum SCr and maximum FHB(Spearman's r =0.215,P=0.042).Logarithmic transformation was performed for FHB at first 3 days after initiating ECMO.Repeated measurement analysis of variance revealed that the main effect for the non-ARF group and ARF group in lg(FHB+1)(P<0.001)was significant and that a significant main effect for time points(P<0.001)was obtained.The main effect for the two groups in TBIL(P=0.005)was significant and a significant main effect for time points(P<0.001)was obtained.The time x group interaction(P=0.004)in TBIL was obtained.Conclusion:ARF is a common complication during ECMO support.FHB and VIS are risk factors of ARF during ECMO support.TBIL during ECMO is higher in ARF group,which is needed further research.Object:We investigated whether high concentrations of bilirubin had a pro-apoptotic effect on renal tubular epithelial cell(HK-2),and examined the potential mechanism.Method:0.6mg bilirubin was dissolved in 84?l dimethyl sulfoxide(DMSO)to obtain a 12mM stock solution.The bilirubin working solutions were prepared in various concentrations:160?M,80?M,40?M,20?M,0?M.The renal tubular epithelial cells(HK-2)were challenged with a gradient concentration of bilirubin.Apoptosis and cytotoxicity were assessed by flow cytometry and MTT.Western Blot was used to examine active caspase3 and phospho-p38 level.Results:The apoptosis rate in B160 group was highest(61.36±3.75%,B160 group vs.BO group,P<0.001).The comparison of apoptosis in other groups:BO group vs.B20group,P=0.022;B20 group vs.B40 group,P=0.026;B40 group vs.B80 group,P<0.001;B80 group vs.B160 group,P=0.002.MTT showed that the survival rate decreased as the bilirubin concentrations increased.Western blot indicated active caspase3 and phospho-p38 level expressed high in B20-B160 groups.Conclusions:Bilirubin induces the apoptotic of renal tubular epithelial cell and the inhibition of cell proliferation as the bilirubin concentrations increased.p38 signal path may participate in the apoptotic of renal tubular epithelial cell induced by bilirubin.Purpose:Acute kidney injury is a serious and common complication in cardiac perioperative period.Bilirubin,an end-product of heme catabolism,is eliminated by liver.Hyperbilirubinemia appears because of liver disorders or elevated bilirubin.The incidence of hyperbilirubinemia is high in cardiac perioperative period.The high concentration of bilirubin induces cell apoptosis.The aim of the study was to investigate whether hyperbilirubinemia aggravated renal ischemia reperfusion injury and to examine the potential mechanism.Methods:Male SD rats were randomly divided into four groups(n=6):negative control group(NC),laparotomy without bile duct ligation or without clamping renal pedicle;common bile duct ligation group(CBDL),common bile duct ligation for 48h;renal ischemia reperfusion injury group(Sham+RIRI),clamping renal pedicle for 45min and then loosening,blood and renal was collected after 24h;common bile duct ligation +renal ischemia reperfusion injury group(CBDL+RIRI),clamping renal pedicle for 45min and then loosening after 24h of common bile duct ligation,blood and renal was collected after another 24h.Results:The level of total bilirubin,creatinine and urea nitrogen were higher in CBDL+RIRI group than that in Sham+RIRI group.There was no difference in creatinine and urea nitrogen between CBDL group and NC group.HE stain and PAS stain showed that the injury of renal tubules was more serious in CBDL+RIRI group(P<0.05):necrotized tubules;dilated tubules;loss of brush border.TUNEL assay indicated the rate of apoptosis was higer in CBDL+RIRI group than that in Sham+RIRI group(P<0.001).CBDL+RIRI group expressed more phospho-p38 which expressing in renal tubule epithelia cell nucleus as demonstrated by immunohistochemistry(P<0.001).Western blotindicated active caspase3(P<0.01)and phospho-p38 level(P<0.001)expressed higher in CBDL+RIRI groups than that in Sham+RIRI.Conclusion:Hyperbilirubinemia aggravated renal tubule epithelia cell apoptosis and renal ischemia reperfusion injury.p38 signal path may participate in the renal ischemia reperfusion injury aggravated by bilirubin.