The Role Of Tyrosine Kinase Receptor DDR2 In The Progression Of Renal Interstitial Fibrosis In Mice

【Background】Epidemiological studies show that the prevalence of chronic kidney disease in adults worldwide is over 10%,and that about 1% of patients with chronic kidney disease develop to end-stage renal disease.Not only seriously affect the quality of life of patients,but also consuming a lot of medical resources.Renal interstitial fibrosis is a common pathway of chronic kidney disease to end-stage renal disease,which is closely related to renal function.The main pathological feature of renal interstitial fibrosis is the accumulation of large amounts of extracellular matrix,especially collagen,in the renal interstitium.The domestic and foreign literature reports: DDRs plays an important role in myocardial fibrosis,pulmonary fibrosis and other organ fibrosis,inhibiting the expression of DDRs can significantly relieve the degree of fibrosis,but most of the literatures are about DDR1,about DDR2 is rare,especially the research on DDR2 and renal fibrosis has not been reported.DDR2 is a major signal between cells and extracellular matrix.DDR2 can be combined and activated by collagen,and DDR2 is high expression in renal tissue of mice,so we speculate that DDR2 may play an important role in the occurrence and development of renal interstitial fibrosis in mice.There is no ideal drug for the treatment of renal interstitial fibrosis.Calcium dobesilate is mainly used in the treatment of improving microcirculation,and the pathological characteristics of renal interstitial fibrosis is large accumulation of extracellular matrix,which may effect renal microcirculation and renal function.Therefore,we hypothesized that calcium dobesilate might have some therapeutic effects on renal interstitial fibers,and relevant experimental design and research were carried out.【Objectives】 1.To establish the mouse model of renal interstitial fibrosis.2.To explore the role of DDR2 in mouse renal interstitial fibrosis.3.To study the effect of calcium dobesilate on expression of mouse kidney DDR2 and the therapeutic effect of renal interstitial fibrosis in mice.【Methods】 1.Make the models of unilateral ureteral obstruction and unilateral renal ischemia reperfusion in mice,and in different time points obtaining kidney tissue after operation,then using Masson and HE staining,real-time PCR,hydroxyproline content determination technique to observe the mouse kidney tissue morphology and the expression changes of α-SMA,Fibronectin and COL1A1 molecules.2.Renal histologic analysis,real-time PCR analyses and hydroxyproline assay were performed in DDR2-deficient mice and wild-type mice after unilateral ureteral obstruction.3.C57 mice were randomly divided into Sham group,UUO group and CDT group;preparation of renal interstitial fibrosis in mice with unilateral ureteral obstruction,CDT group was given calcium dobesilate gavage,Sham group and UUO group were given double distilled water;then the expression of DDR2 and the renal fibrosis of renal tissues were observed by HE staining,Masson staining,immunohistochemistry,real-time quantitative PCR and Western blotting 14 day after operation.【Results】 1.HE staining: The structure of renal tubules were severely damaged and the renal interstitium was infiltrated by inflammatory cell after operation in mice;Masson staining: The renal interstitial collagen was increased significantly after operation in mice;Realtime PCR: The expression of renal interstitial fibrosis related molecules COL1A1,Fibronectin α-SMA were significantly increased after operation in mice;Hydroxyproline assay:The content of hydroxyproline in renal tissue was increased significantly after operation in mice,presenting a rising trend.2.HE staining: The interstitial inflammatory cell infiltration of DDR2 deficient mice was significantly reduced compared with wild type mice;Masson staining: The renal interstitial collagen fibers of DDR2 deficient mice were significantly decreased compared with wild type mice;Realtime PCR: The expression of DDR2 gene was gradually increased after 0,7,14 days of UUO and IRI in wild type mice.Fibrosis associated COL1A1,fibronectin and α-SMA gene expression,DDR2-deficient mice kidney are all decreased compared with the wild-type mice;Hydroxyproline assay: the content of hydroxyproline in kidneys,DDR2-deficient mice were decreased significantly compared with wild-type mice 14 days after UUO.3.HE staining: The pathological changes of CDT group were significantly reduced compared with UUO group;Masson staining: The renal interstitial collagen fibers of CDT group were significantly reduced compared with UUO group;Immunohistochemistry: The expression of COL1A1 in renal interstitial of CDT group was significantly reduce compared with UUO group;Western blot: The expression of fibrosis related protein COL1A1 of CDT group was significantly reduced compared with UUO group.【Conclusions】 1.Unilateral ureteral obstruction and unilateral renal ischemia reperfusion model in mice could induce renal interstitial fibrosis.2.The expression of DDR2 increased gradually in the progression of renal interstitial fibrosis in mice,and the renal interstitial fibrosis of DDR2-deficient mice alleviated significantly than that in wild-type mice.3.Calcium dobesilate can effect the expression of DDR2 and improve the renal interstitial fibrosis in mice.