Expression of connective tissue growth factor in renal interstitial fibrosis after unilateral ureteral obstruction in rats

AIM:To observe the expression of connective tissue growth factor(CTGF)in unilateral ureteral obstruction(UUO)rats,and to explore its pathogenic role in renal tubulointerstitial fibrosis.METHODS:48 Wistar rats were randomly divided into sham-operated and UUO group.The rats were sacrificed at day 1,3,7,and 14.The degree of tubulointerstitial damage was scored according to the Masson staining.The mRNA and protein levels of CTGF,transforming growth factor-β1(TGF-β1),collagen Ⅰ(Col Ⅰ),and plasminogen activator inhibitor-1(PAI-1)were detected by reverse transcriptional-polymerase chain reaction(RT-PCR)and immunohistochemistry,respectively.Expression of CTGF protein in the kidney was also assessed using Western blotting.RESULTS:TGF-β1 mRNA level began to increase as early as 1 day after UUO.This increase was followed by the elevation of CTGF mRNA level,which began to increase at third days after UUO(P0.01).7 days after UUO,the protein level of CTGF was positively related to the index of tubulointerstitial damage(r=0.62,P0.01),the expression of TGF-β1(r=0.85,P0.01),Col Ⅰ(r=0.78,P0.01),and PAI-1(r=0.76,P0.01),as determined by immunohistochemistry.CTGF protein level appeared to increase progressively throughout the time course.CONCLUSION:As a downstream mediator of TGF-β1,CTGF may play a crucial role in the progression of tubulointerstitial fibrosis.