The Mechanism Of HE4 In Hypoxia-induced Tubular Epithelial Cell ECM And Renal Fibrosis

IntroductionRenal fibrosis is the common pathway of chronic kidney dieaseas.Hypoxia plays an important role in the development of renal fibrosis of CKD patients.Hypoxia could promote the progression of renal fibrosis by upregulating the expression of HIF、EMT of renal tubular cells、inflammatory cell infiltrate、inducing the cell apoptosis and so on.Human epididymis secretory protein 4(HE4)is a two-domain member of‘four-disulfide core’ protein family.HE4 has been used as a serum biomarker in epithelial ovarian cancer.It has been reported that the upregulation of HE4 could be detected at the early stage of chronic kidney disease(CKD).HE4 expression in the serum of patients of CKD was inversely correlated with eGFR and positively correlated with the SCr in the serum of patients of CKD.In 2013,Valerie S.LeBleu found the significantly high expreesion of HE4 in myofibroblasts by using a novel genetic mouse model to track and isolate myofibroblasts,which could promote fibrosis by inhibiting the activities of matrix metalloproteinases MMPs.Meanwhile,mice treated with HE4 neutralizing antibodies showed improvement in renal fibrosisdevelopment.These observations have reflected the HE4 was involved in the progression of renal fibrosis.However,what is the role of hypoxiae to in the renal fibrosis?What is the regulatory mechanism of HE4 upregulation in renal tubular cells in the renal fibrosis ? It is still unkown so far.Objective(1)To investigate the role of HE4 in renal fibrosis and the relationship between HE4 and hypoxia.(2)To detect the expression of HE4 in patients of CKD and analyse the relationship between HE4 and clinic indicator of CKD.Methods(1).Using western blot、qRT-PCR、Cell immunofluorescence and immumohistochemistry to confirm the expression of HE4 induced by hypoxia and the level of HE4 in UUO models.(2).Using siRNA and pcDNA3.1-HE4 to explore how HE4 regulates the fibrosis factors.(3).Using dual-luciferase reporter gene 、 ChIP and the pcDNA3.1-HIF-1α to explore the mechanism of hypoxia to regulate HE4.(4).Using the inhibitor of NF-κB to verify the downstream targets of HE4.(5).Using HE4 lentivirus to confirm the inversion of progression of renal fibrosis by inhibition o the expression of HE4.(6).Fasting blood samples and tissue samples of CKD patients to explore the expression of HE4 in patients of CKD.Results:(1).Hypoxia can induce the upregulation of HE4.(2).HE4 participates in hypoxia-induced renal fibrosis in tubular epithelial cells.(3).Hif-1α can directly induce the high expression of HE4 by binding to the promoter of HE4.(4).HE4 could induce the fibrosis in tubular epithelial cells via NF-kb signal pathway.(5).C57 mice treated with Lv-HE4 after UUO treatment can reverse the fibrosisin vivo.(6).HE4 is considerably increased in renal tissue samples and serum from chronic kidney disease patients.Conclusion:In our study,we found HIF-1αcould bind to the promoter of HE4 to transcriptional regulation of HE4.The upregulation of HE4 could inhibit MMP2 through NF-κB signal pathway to decrease the degaration of ECM to promote renal fibrosis.Meanwhile,C57 mice treated with LV-HE4 could reverse renal fibrosis after UUO in vivo.From chronic kidney disease patients HE4 is considerably increased in renal tissue samples and serum.