Role For Wnt/?-catenin Signaling Pathway And Sfrp1 In Obstructive Renal Interstitial Fibrosis

Objective: By building the models of the unilateral ureteral obstruction(UUO)mice, simulated interstitial fibrosis induced by obstruction. To observe the expression of Sfrp1, Wnt1 and ?-catenin in renal tissues of rats following unilateral uretral obstuction(UUO). Discussion on:expression and significance of Sfrp1, Wnt1 and ?-catenin in the development of renal interstitial fibrosis. So we want to find some markers to predict renal organizational structure damage of hydronephrosis early. It is to provide the clinical doctors reference on treating renal fibrosis.Methods: 48 health male Wistar rats weighing 180-200 g were randomly divided into 2 groups,model group(UUO, n=24), sham-operated group(SOR, n=24). The rats in each group were fed with appropriate temperature and humidity. Model group and sham-operated group rats were anesthetized by 2% nembutal(0.3ml/100 g body wt,i.p) and fixed. To establish the unilateral ureteral obstructive rat model, the rats were cutted the skin and muscle. Separated the right ureter, ureteral ligation 2cm below the UPJ. The right ureter was ligated by silk at two points and cut between the ligatures. Shamoperation group rats, only free on the right ureter, but not ligated. Eight rats of each group were killed on days 3, day 6 and day 9 after surgery, and their right kidneys were promptly taken out. Accroding to coronary palce kidneys were promptly taken longitudinal shape and quarter of them were fetched and were routinely fitted in 4% phosphate-buffered paraformaldehyde and paraff in embedded. Tissue sections at 4?m were obtained. Under the light microscope, renal tissue pathological change were observed by HE staining. The kidneys were obtained to observe the renal tissue histolgical changes and to evaluate the degree of renal interstitial fibrosis through Masson staining. Immunohistochemical method was performed to detected the protein expression of Sfrp1 Wnt1 and ?-catenin in tubulointerstitial areas. The results were analyzed semi-quantitatively by the pathological image analysis system. The measuring data were detected by expression of?(?±S),all the data were analysed by SPSS 13.0 statistics software. According to the results of the experimental groups for the correlation analysis.Results: Gross observation: the kidneys in group SOR were normal like bean from the appearance. The obstructed kidneys became bigger as time went on in group UUO. The renal pelvis became expanded. The renal cortex became thin.HE results showed that there was no abnormal changes in the renal tissue of group SOR. At the 3rd day after the obstructive operation in group UUO, the interstitial area was widened. There were a small number of monocyte/ macrophage and lymphocyte inflammatory infiltration, the renal tubles slightly expanded. At the 6th day, the interstitial area increased in width. There were more monocyte/macrophage and lymphocyte inflammatory infiltration,the renal tubles expanded. A part of renal tubular were shrinked, swelling and even necresis were seen in epthelial cells. At the 9th day,the interstitial area obviously widened. There were a lot of monocyte/macrophage and lymphocyte inflammatory infiltration. The renal tubles obviously expanded. Most tubules showed serious damage. The tubule basement membrance appeared diffuse thicken and even collapsed. A large number of fibroblasts and collagen fibrosis.Renal interstitial fibrosis evaluation by Masson: in SOR group, the evaluation had no apparently changes during the whole experiment. The degree of renal interstitial fibrosis evaluation in UUO group increased in time-dependent manner(P<0.05). And the degree was higher in UUO group than that of SOR group at each time point respectively(P<0.05).Results of immunohistochemistry in group SOR indicated that, there was only a little expression of Wnt1, ?-catenin in renal interstitium. Without significant differences at each time point respectively(P>0.05). There was high expression of Sfrp1 in renal interstitium. Without significant differences at each time point respectively(P>0.05). As obstructed time went, the expression of Wnt1 and ?-catenin protein in renal interstitium were increased remarkably in UUO(P<0.05). And the expression levels in UUO were higher than that in SOR at each time point respectively(P<0.05). As obstructed time went, the expression of Sfrp1 protein in renal interstitium were decreased remarkably in UUO(P<0.05). And the positive degree was still lower in UUO group than that of SOR group at each time point respectively(P<0.05).Conclusion:1 The high expression of Wnt1 and ?-catenin is an important mechanism in renal interstitial fibrosis. Wnt/?-catenin signal pathway plays an important role in the formation of fibrosis.2 The reduced expression of Sfrp1, reduce the inhibitory effect of Wnt1, cause Wnt/?-catenin pathway activation. The reduced expression of Sfrp1 may be starting and promoting fibrosis factors.