Protective Effect Of Bisdemethoxycurcumin On Renal Fibrosis And Cisplatin-induced Nephrotoxicity

Objectives: Renal fibrosis is a hallmark and common pathway of various progressive chronic kidney diseases(CKD).It is characterized by a large number of renal interstitial fibroblasts and excessive accumulation of extracellular matrix(ECM).According to the research statistics,the global incidence of CKD is 11.7-15.1%,and the incidence of this disease is on the rise with the increase of acute kidney injury(AKI)caused by drug treatment,diabetes,obesity and aging.Renal fibrosis not only causes physical pain to patients,but also causes a heavy economic burden.But so far,there are still serious deficiencies in the treatment of renal fibrosis.Therefore,the mechanism research of the occurrence and development of renal fibrosis and the search of effective intervention strategies have attracted more and more attention.It is also the focus and difficulty to overcome this disease at this stage.Bisdemethoxycurcumin(BDMC)is a natural chemical component extracted from the roots of plants in the ginger and araceae families.Our previous research found that BDMC can effectively induce fibroblasts apoptosis at the concentration around 20 ?M,but had no effect on renal tubular epithelial cells.At the same time,we also found that BDMC can relieve cisplatin-induced injury in renal tubular epithelial cells.On this basis,this article researched the protective effects of BDMC on renal fibrosis and cisplatin renal toxicity,and explored its protective mechanism.Methods:(1)Screening for natural compounds that specifically damage fibroblasts without affecting renal tubular epithelial cells using cell model.A series of natural compounds with the same concentration were treated to renal tubular epithelial cells(HK-2 cells)and fibroblasts(3T6 cells),respectively,and the cell proliferation was detected by SRB assay.(2)A method of unilateral ureteral occlusion(UUO)was used to construct a mice model of renal fibrosis,and 100 mg/kg or 200 mg/kg BDMC were administered intragastrically.Blood biochemical indicators,H&E staining,and sirius-red staining were used to evaluate the treatment of renal fibrosis by BDMC.(3)Intraperitoneal injection of 20 mg/kg cisplatin was used to construct a mice model of acute kidney injury.50 mg/kg,100 mg/kg or 200 mg/kg BDMC were administered daily starting two days before cisplatin injection and continued until the second day after cisplatin injection.Blood biochemical indicators,H&E staining,and immunohistochemistry were used to evaluate the treatment of BDMC on cisplatin nephrotoxicity.(4)PI/Annexin V double staining combined with flow cytometry was used to detect the apoptosis rates of HK-2 and 3T6 cells treated with BDMC and the protection of BDMC against cisplatin-induced apoptosis of HK-2 cells.(5)The changes of related proteins in vivo and in vitro were detected by western blot assay.Results:(1)In the screening of natural compounds extracted from plants using fibroblasts and renal tubular epithelial cells,it was found that BDMC can specifically induce fibroblasts damage around the concentration of 20 ?M;(2)In UUO mice experiment,blood biochemical indicators,visceral lesion degree,H&E staining and sirius red staining results showed that BDMC alleviated UUO-induced renal injury and renal fibrosis.;(3)PI/Annexin V double stain combined flow cytometry and western blot results showed that BDMC prevented the progression of renal fibrosis by specifically inducing fibroblasts apoptosis at the concentration of 20 ?M;(4)In screening tests of natural compounds,BDMC was found to inhibit cisplatin-induced apoptosis of renal tubular epithelial cells;(5)In cisplatin-induced acute injury experiment in mice,blood biochemical indicators,visceral lesion degree,and H&E staining results showed that BDMC alleviated cisplatin-induced kidney injury;(6)PI/Annexin V double staining combined with flow cytometry and western blot analysis results showed that BDMC inhibited cisplatin-induced p53 protein levels,thereby inhibiting cisplatin induction renal tubular epithelial cells apoptosis;(7)Western blot,immunohistochemistry,and cellular ROS test results show that BDMC inhibited cisplatin-induced down-regulation of Nrf2 and then alleviated cisplatin-induced renal oxidative stress response;(8)Western blot and immunohistochemical analysis results showed that BDMC alleviated cisplatin-induced renal inflammation by inhibiting NF-?B activation and down-regulating the expression of ICAM-1(intercellular cell adhesion molecule-1)and MCP-1(monocyte chemoattractant protein-1).Conclusion: In this study,we found that BDMC has the effect of protecting renal fibrosis and alleviating cisplatin-induced kidney injury in vivo and in vitro.The mechanism of BDMC protecting renal fibrosis is that it can specifically induce apoptosis of fibroblasts.And the mechanism of BDMC alleviating the cisplatin nephrotoxicity is that it can block the cisplatin-induced damage in kidney through several aspects: 1)BDMC inhibits cisplatin-induced renal tubular epithelium apoptosis by inhibiting the up-regulation of p53 induced by cisplatin;2)BDMC alleviates cisplatin-induced renal oxidative stress response by inhibiting cisplatin-induced down-regulation of Nrf2;3)BDMC alleviates cisplatin-induced renal inflammatory response by inhibiting NF-?B activation and down-regulating the expression of ICAM-1 and MCP-1.Our findings provide a new strategy and theoretical basis for the treatment of renal fibrosis.It also provides a new intervention for the renal toxicity induced by cisplatin.