The Effect Of Renal Tubular Epithelial-myofibroblast Transdifferentiation In High Glucose And The Influence Of Rhein Intervention

Background and objectives:Diabetic nephropathy(DN)is one of blood capillary complications. Tubulointerstitial fibrosis is an essential pathological basis in the progression of diabetic nephropathy to end stage renal disease(ESRD), the basic pathological character of which is excessive extracellular matrix (ECM)accumulation in the renal interstitium.Currently,it is considered that the renal interstitial ECM is mainly secreted by the myofibroblast (MyoF).Researches have shown that tubular epithelial-myofibroblast transdifferentiation(TEMT)can occur to the renal tubular epithelial cells in pathological condition.During TEMT,renal tubular epithelial cells lose their original phenotypic characteristics:E-cadherin,then gain MyoF characteristics:α-smooth muscle actin(α-SMA),which is a principal source of renal interstitium MyoF.More and more concern is gradually focused on the role of TEMT in tubuinterstitial fibrosis.A considerable number of factors have been suggested as potential inductors of TEMT. However,it is still unknown whether the same TEMT process will take place with high glucose stimulation human proximal tubular epithelial cells(HK-2).A traditional Chinese medicine frequently appears in clinical prescription,Rhein is a prosoma component extracted from the rhubarb anthraquinone ramifications and is the primary active ingredient of rhubarb.Rhein has the effect of decreasing proteinuria and attenuating nephridial tissue process in Diabetic Nephropathy,few is reported that the mechanism is related to TEMT process.Rhein intervenes in HK-2 in high glucose in our experience,then we observe whether TEMT process is influenced by Rhein and try to explain the possibility mechanism in diabetic nephropathy through TEMT.From cell culture HK-2 in vitro,by imitation of high glucose and refering to indexes like fibronectin(FN),which is one of the ingredients of ECM,E-Cadherin andα-SMA,which respectively reflects the phenotypic characteristics of renal tubular epithelial cells and MyoF,the objective of this study is to illustrate the effect of high glucose on the phenotypic transformation of renal tubular epithelial cells,and to observe the influence of Rhein as an intervener in the above-mentioned processes,then initially probe the possibility of mechanism of rhein preventing and curing diabetic nephropathy.Methods:Human proximal tubular epithelial cells(HK-2)were divided into six groups:Group N,cultured with glucose(5.5mmol/l)DMEM;Group M,cultured with mammite(24.5mmol/l)and glucose(5.5mmol/L) DMEM;Group H,cultured with 30mmol/l glucose DMEM;Group H+25R,cultured with 30mmol/l glucose DMEM+Rhein 25ug/ml;Group H+50R,cultured with 30mmol/l glucose DMEM+Rhein 50ug/ml;Group H+100R,cultured with 30mmol/l glucose DMEM+Rhein 100ug/ml. Each group cells were collected at 48 hours when we observe cell morphology and the vary of protein expression of TEMT.The protein expression of E-Cadherin,α-SMA and FN were assessed by Western-blotting method.Results.Compared with group N,the protein expression of E-cadherin,α-SMA and FN in group M did not have distinct change(P＞0.05);the protein expression of E-cadherin in HK-2 cells decreased(P＜0.05);while the protein expression ofα-SMA and FN increased(P＜0.05)in high glucose environment(group H).The protein expression of E-cadherin increased(P＜0.05)while the protein expression ofα-SMA,FN decreased (P＜0.05)in Rhein treated group(group R)with dose-dependent manner, compared with group H(P＜0.05).Conclusion:1.With high glucose,the express of E-Cadherin protein decrease,while the express ofα-SMA and FN increase,indicating that high glucose can induce the phenotypic transformation of renal tubular epithelial cells into mesanchymal cells.2.Rhein can repress the phenotypic transformation of renal tubular epithelial cells into mesanchymal cells and attenuate the process of TEMT, this may be a function mechanism of Rhein as a prevention to DN.