The Mechanism Of Elabela(ELA) And Its Active Fragment ELA14 In Acute Renal Injury Induced By Contrast Medium

Background:With the popularity of coronary intervention,the unavoidable exposure of intravascular contrast media,which leads to acute renal injury caused by contrast media,will lead to increase the risk of interventional therapy.Elabela/Apela is the second ligand of angiotensin receptor type I related receptor protein(APJ).Previous studies suggested that exogenous and endogenous overexpressed ELA peptides can significantly inhibit the increase of DNA damage response,apoptosis and inflammation response(in the in vitro and in vivo model of renal hypoxia-reperfusion acute kidney injury),they also can inhibit DNA damage induced by Adriamycin.However,the role and mechanism of ELA peptides in CI-AKI are unclear.Objective:To analyze the evolution of ELA after human CM exposure,and to compare the role and possible mechanism of ELA32 and its active fragment ELA14 in CI-AKI cell model.To explore the role and possible mechanism of ELA32 in rat CI-AKI model.To explore the role of ELA and APJ in the pathogenesis of CI-AKI.Method:1.Observe the traditional renal function indexes such as serum creatinine(Scr),urea nitrogen(BUN),high sensitivity C-reactive protein and ELA levels on the day of preoperation,12 hours,24 hours and 48 hours after coronary artery detection and / or treatment.2.In vitro,the effects of ELA32 and its active fragment ELA14 on apoptosis,autophagy,inflammation,oxidative stress and DNA damage were observed by establishing CI-AKI model of NRK-52 E cells.3.In vivo,the rat CI-AKI model induced by IOP was established to observe the effects of ELA32 on apoptosis,autophagy,inflammatory oxidative stress,DNA damage,renal fibrosis and so on.4.In vitro,Apela and APJ receptor antagonist protamine were overexpressed by virus transfection to explore the role and possible mechanism of ELA and APJ in IOP-induced CI-AKI cell model.Results:1.Among the 22 patients included,there was no case of CI-AKI.ELA decreased and hsCRP increased in perioperative period,which reached statistical significance at 24 h and 48 h after operation(ELA:P=0.016,P=0.019;hsCRP:P=0.007,P=0.010).There was no difference in the evolution of Scr,BUN,eGFR and other indexes during the perioperative period.2.ELA32/ELA14 could reduce IOP/IOD-induced apoptosis,autophagy and mitochondrial ROS production in NRK-52 E cells in a dose-dependent manner.After IOP/IOD exposure,the mRNA expression of IL-6,TNFa,NRF2 and ICAM-1 was up-regulated,while the protein expression of p-ATR,p-CHK1,C-caspase3,LC3 II was up-regulated and p62 protein was down-regulated.However,the opposite expression of ELA32 and ELA14 appeared after the intervention.3.The rat CI-AKI model can be successfully established after dehydration induction.ELA32 can reduce the levels of Scr and BUN in rat CI-AKI model,and reduce renal tissue injury,apoptosis,collagen deposition and ?-SMA expression.After exposure to IOP,the mRNA expression of NRF2 and ICAM-1 was increased,the protein expression of p-ATR,p-CHK1,C-caspase3,LC3-? was up-regulated,and the protein of pERK1/2 and p62 was down-regulated.After adding ELA32,there were opposite changes.4.Compared to the control group,NRK-52 E cells overexpressing Apela reduced apoptosis,mitochondrial ROS production,decreased mRNA expression of NRF2 and ICAM-1,down-regulated proteins of p-ATR,p-CHK1,C-caspase3 and up-regulated pERK1/2 after exposure to CM,but the protective effect was significantly weakened or disappeared after blocking APJ.After blocking APJ,NRK-52 E cells treated with IOP showed decreased apoptosis,mitochondrial ROS production,decreased mRNA expression of NRF2 and ICAM-1,down-regulated proteins of p-ATR,p-CHK1,C-caspase3 and up-regulated pERK1/2.Conclusions:1.After CM coronary exposure,ELA was significantly down-regulated,which may be a new new sensitive index of renal function changes after CM exposure.2.Both IOD and IOP can induce apoptosis and autophagy of renal tubular epithelial cells through oxidative stress and mitochondrial damage.ELA32 and its active fragment ELA14 can reduce apoptosis and autophagy of renal tubular epithelial cells by inhibiting CM-induced oxidative stress,mitochondrial damage and reducing DNA damage,and their effects are similar.3.Dehydration plus diuretic pretreatment can establish an accurate and stable rat CI-AKI model.ELA32 can reduce apoptosis and excessive autophagy in rat CI-AKI by inhibiting oxidative stress induced by CM,reducing DNA damage and anti-renal fibrosis,and its mechanism may play a role by combining with APJ.Ela32 can alleviate renal injury in CI-AKI rats by anti-inflammatory,anti DNA damage,reducing apoptosis and autophagy,and anti-renal fibrosis.Its mechanism may play a role by combining with APJ.4.Endogenous ELA is similar to exogenous ELA and plays the protective role of CI-AKI in NRK52 E cells.IOP may induce cell injury partly by activating ERK1/2 pathway by binding to APJ.On the other hand,ELA32 may play the protective role of CI-AKI by competing with IOP and combining with APJ.