| Background: Renal interstitial fibrosis is the pathological manifestation of a variety of diseases,such as chronic kidney disease,renal tubular disease,interstitial nephritis,and so on.It will eventually lead to end-stage kidney disease.This study mainly explores the expression and the molecular mechanism of matrix metalloproteinase-9(MMP9)and vascular endothelial growth factor(VEGF)in the process of renal interstitial fibrosis(RIF),in order to provide a new approach for the treatment of renal interstitial fibrosis.Methods: Twenty-four male Sprague Dawley(SD)rats of 6-8 weeks old were randomly divided into normal control group and experimental group.Then we divided the normal control group as well as the experimental group randomly into two groups,respectively.The normal group was sacrificed at 2 weeks(2NC group)or 4 weeks(4NC group).We performed unilateral ureteral obstruction(UUO)on experimental models.Then,the rats were sacrificed at 2 weeks(2UUO group)and 4 weeks(4UUO group)after the operation.The kidney tissues of these rats were stained by HE staining and Masson staining.Immunohistochemistry was applied to detect the expression of MMP9,VEGF,fibronectin(FN),and type IV collagen(Col-IV).Western blot was applied to detect the expression of MMP9,VEGF,as well as transforming growth factor-β1(TGF-β1).Finally,we compared the results of the control group and the experimental group to clarify the expression of various indicators.Results: HE staining and Masson staining showed obvious fibrotic features such as tubular dilatation,luminal deformation,and fibrous cord hyperplasia in the experimental group.Masson staining showed that the degree of RIF in the experimental group was stronger in comparison with the matched group(P<0.05),and it increased by the experimental time(P<0.05).The results of immunohistochemistry and Western blot showed that the expression of MMP9 in the experimental group was reduced in comparison with the matched group(P<0.05),which was less in the 4UUO group in contrast with the 2UUO group(P<0.05).While the expression of VEGF expression in the experimental group was higher in comparison with the matched group(P<0.05),which is higher in 4UUO group than 2UUO group(P<0.05).Western blot revealed that the expression of TGF-β1 was remarkably increased in the 4UUO group in contrast with the 2UUO group,and both of them were more evident than the matched group(P<0.05).Immunohistochemical staining of FN and Col-IV respectively showed stronger expression in the 4UUO group in contrast with the 2UUO group(P<0.05).Both expressions were stronger in contrast with the matched group during the same period(P<0.05).In the correlation analysis,the results of immunohistochemical blotting showed that the expression of MMP9 in the UUO group has a negative correlation with the expression of VEGF,Col-IV,FN,and RIF index(r=-0.777,r=-0.536,r=-0.580,r=-0.681,all P<0.05).In the UUO group,the expression of VEGF has a positive correlation with the expression of Col-IV and FN(r=0.833,r=0.801,all P<0.05),and positively correlated with the RIF index(r=0.617,P<0.05).In the UUO group,the expression of Col-IV has a positive correlation with the expression of FN as well as RIF index(r=0.719,r=0.446,P<0.05).The results of Western blot showed that the expression of MMP9 had a negative correlation with the expression of VEGF and TGF-β1 in the UUO group(r=-0.930,r=-0.932,P<0.05),while the expression of VEGF was positively correlated with the expression of TGF-β1 in the UUO group(r=0.940,P<0.05).Conclusion: In the UUO model,the expression of MMP9 gradually decreases with the aggravation of RIF lesions,which trend is inconsistent with TGF-β1,FN,and Col-IV.As the degree of fibrosis deepens,the expression of VEGF gradually increases with the degree of fibrosis,which is the same with TGF-β1,FN,and Col-IV.Therefore,the decrease of MMP9 expression and the increase of VEGF expression may play a role in RIF,and whether there is a mutual inhibitory relationship between MMP9 and VEGF remains to be confirmed by further experiments. |
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