Acute Lung Injury In Patients With Ischemia/Reperfusion Kidney Injury And The Mechanism Of Exogenous EPO Intervention

Background : Acute kidney injury(AKI)is a common complication that the incidence is 30-50% in Intensive Care Unit(ICU).Acute lung injury(ALI)is one of the major impaired organs in critically ill patients with poor outcomes.Several studies found there was a relationship between AKI and ALI.Early intervention of ALI is scarce.Some researches showed that Erythropoietin(EPO)treatment was benifit for ALI.It was unclear the mechanism of EPO protection in ALI patients with AKI.Objective:To investigate the incidence and risk factors of ALI in AKI patients which were received liver transplantation operation and the relationship between EPO usage and ALI recovery.We also explored the mechanism of the protection of exogenous EPO on ALI in renal ischemia/reperfusion(I/R)injury mice.Methods:We reviewed living donor orthotopic liver transplantation(OLT)patients in Renji Hospital retrospectively and analyzed incidence of AKI and ALI at 48 h after operation.ALI(low oxygenation group)was definited as oxygenation fraction(Pa O2/Fi O2)?300mm Hg.The risk factors of AKI and ALI in OLT patients were evaluated by Logistic analysis.We also checked the relationship between the usage of EPO and ALI recovery in AKI patients.I/R kidney injury mice were developed and mice were divided into three groups(control,I/R and I/R+EPO).EPO 6000IU/kg were injected subcutaneously before operation.We examined renal function,renal and lung pathology.The renal and lung ultrastructure changes were investigated by electron microscopy.IL-1?,TNF-? and MCP-1 were detected by using ELISA.m RNA expression in lung tissues was estimated by q PCR.Lipopolysaccharide(LPS)was used to stimulate human umbilical vein endothelial cells(HUVEC)and some cells were pretreated with EPO.IL-1?,IL-6,MCP-1 and EPO receptor(EPO-R)gene expression and protein production were detected by q PCR and western blot.Akt and phosphorylated Akt(p-Akt)were tested by western blot.p-Akt and EPO receptor(EPO-R)expression were also examined by immunohistochemical staining in serial section.Results: A total of 301 patients,aged 50.35±10.29 years were enrolled.Of these patients,100 patients(33.2%)suffered ALI.Compared with the normal oxygenation group,body mass index(BMI)(24.48±3.53 versus 23.1±3.27 kg/m2,P=0.001),preoperative hemoglobin(115.79 ± 29.27 versus 111.52 ± 29.80 g/L,P=0.033),preoperative MELD(22.25±6.54 versus 20.24±5.74,P=0.008),and intraoperative urinary volume(1.25 [0.76,1.89] versus 2.04 [1.49,3.68] m L/kg/h,P=0.003)were higher in low oxygenation group.There were more cases of earlier AKIs that occurred after OLT in ALI patients than that in normal oxygenation group(47%versus 23.4%,P<0.001).Logistic analysis showed that the preoperative BMI(hazard ration [HR]=1.1,[95%CI:1.026,1.239],P=0.012)and early AKI after OLT(HR=2.1,[95%CI:1.107,3.808],P=0.023)were independent risk factors for postoperative low oxygenation.In 94 AKI patients,the incidence of ALI was 50.0%,which higher than that in non-AKI patients(25.6%).Logistic analysis showed that male,intraoperative low urine output and long anhepatic period were independent risk factors for AKI with ALI(HR=8.425[95%CI:1.155,61.450],P=0.036;HR=0.448[95%CI:0.241,0.987],P=0.046 and HR=1.096 [95%CI:1.021,1.177],P=0.012,respectively).Early EPO treatment after operation contributed to improvement of ALI at 72 hours after operation(OR:0.1[95%CI:0.02,0.44],P=0.020).In I/R kidney injury mice,lung histology showed grossly abnormal and characterized by septal edema,hemorrhage,and inflammation,as well as neutrophils and CD45 positive cell acumulation in the lung interstitium.Electron microscopy(EM)showed thicken,incomplete membrane,shrunken nuclei with chromatin condensed and abnormalities of mitochondria including form swelling and crest disappeared in alveolar epithelial type II cell(AECIIs)in I/R mice.EPO treatment improved lung histology and ultrastructure changes in I/R mice.Compared with the control group,I/R mice had higher lung histology injury score(0.17±0.09 vs 0.60±0.07,P<0.001),which were improved by EPO treatment(I/R+EPO group,0.28±0.12,compared with I/R group,P=0.002).Expression of IL-1? in lung tissue in I/R mice were increased 400.06±35.13% and 100.45±36.79% compared with control mice and I/R+EPO mice(P<0.05),and Expression of TNF-? in lung tissue in I/R mice were increased 200.12±40.19% and 184.17±26.91% compared with control mice and I/R+EPO mice(P<0.05).The expression of EPO-R was increasing 815.31±118.91% in I/R+EPO mice lung vessel endothelia cells compared with control group.In vitro,compared with control group,p-Akt was increased in EPO incubated HUVEC.EPO prevented LPS-induced IL-1? and MCP-1 expression in HUVEC and the effects were dose-dependently blocked by pretreatment with an Akt inhibitor.We also found that p-Akt and EPO-R were collocated at lung endothelial cells in I/R+EPO mice.Conclusion: The incidence of postoperative ALI after liver transplantation in adults was 33.2% and 50.0% OLT patients with AKI suffered ALI.BMI and early AKI after OLT were correlated with postoperative ALI in OLT patients.Male,intraoperative low urine output and long anhepatic period contributed to ALI in OLT patients with AKI.Early EPO therapy contributed to ALI recovery.Lung inflammation was found in I/R kidney injury mice.Exogenous EPO inhibited cytokine gene and protein production and alleviated inflammation in lung.EPO-R/Akt signaling pathway in lung endothelial cell might mediated EPO protection effects.