ABSTRACT
AIM: Irbesartan, a new antagonist of the type 1 angiotensin II receptor, has been proven to be renal protective in both diabetic and non-diabetic nephropathy, but its exact mechanism is still uncertain. Here we investigated the influence of irbesartan on the expression of the integrin-linked kinase (ILK) and its relationship with epithelial-mesenchymal transition (EMT) in mice with unilateral ureteral obstruction (UUO). METHODS: The mice were randomly divided into 3 groups: sham operation (C, n=20), UUO (n=40), and UUO with irbesartan treatment (UUO+irbesartan, n=40). Irbesartan was given at a dose of 50 mg/kg body weight per day by gavage. The experimental animals in the control group received the same volume of vehicle (0.9% saline solution). The animals were sacrificed at d 1, 3, 7, and 14, respectively, after the surgery. RESULTS: The expression of the ILK at mRNA and protein levels were significantly increased in the UUO group 1 d after the surgery, which was significantly decreased by treatment with irbesartan (P<0.01, respectively). The expression of alpha-smooth muscle actin (alpha-SMA) was significantly increased, while E-cadherin was decreased in mice with UUO at d 3 after the surgery. Treatment with irbesartan significantly abrogated such effects (P<0.01). The immunohistochemistry analysis indicated that the protein expression of the ILK was positively correlated with alpha-SMA, but negatively with E-cadherin. CONCLUSION: These results suggested that irbesartan attenuated renal tubulointerstitial fibrosis in UUO mice, which may be related to the inhibition of ILK expression, subsequently preventing the tubular EMT.
Subject(s)
Angiotensin II Type 1 Receptor Blockers/pharmacology , Biphenyl Compounds/pharmacology , Cell Transdifferentiation/drug effects , Fibrosis/prevention & control , Kidney/drug effects , Kidney/metabolism , Protein Serine-Threonine Kinases/antagonists & inhibitors , Protein Serine-Threonine Kinases/metabolism , Tetrazoles/pharmacology , Ureteral Obstruction/metabolism , Ureteral Obstruction/pathology , Actins/metabolism , Animals , Cadherins/metabolism , Down-Regulation , Epithelial Cells , Irbesartan , Kidney/pathology , Male , Mice , Nephritis, Interstitial/prevention & control , RNA, Messenger/metabolism , Random AllocationABSTRACT
OBJECTIVE: To investigate the expression of integrin-linked kinase (ILK) in kidneys of mice with unilateral ureteral obstruction and its relevance with the epithelial-mesenchymal transition. METHODS: Mice were randomly divided into two groups, sham operation (C, n = 20) and unilateral ureteral obstruction (UUO, n = 40). The animals were sacrificed at day 1, 3, 7 and 14 respectively after the surgery. Tubulointerstitial fibrosis (TIF) was graded according to Masson staining. The protein level of ILK was examined by Western blot. Tissue/cytological expression for ILK, alpha-SMA and E-cadherin were investigated by immunohistochemistry. The mRNA levels of ILK, alpha-SMA and E-cadherin were analyzed by quantitative real-time PCR. RESULTS: In the control animals (group C), weak staining for ILK was detected mainly in the podocytes. Significant increase of staining for ILK in the experimental mice (UUO group) was detected from day 1 onward (t = 16.5, P < 0.01), reaching the peak at day 7. The protein expression of E-cadherin was continuously down-regulated from day 3 onward after surgery (t = 21.0, P < 0.01), while expression for alpha-SMA was up-regulated. From day 1 to day 7, the protein expression of ILK was positively correlated with alpha-SMA (R = 0.88, P < 0.01), but negatively correlated with E-cadherin (R = -0.87, P < 0.01). The mRNA expression of ILK and alpha-SMA analyzed by real-time PCR increased from postoperative day 1 and 3 respectively, but the mRNA expression of E-cadherin decreased from day 3 onward. CONCLUSION: Increasing expression of ILK occurs in the early phase of UUO mouse and may play an important role in the process of TIF through mediating the epithelial-mesenchymal transition.
