Effect of angiotensin II inhibition on the epithelial to mesenchymal transition in developing rat kidney

Purpose:To investigate the effects of angiotensin II inhibition on the epithelial to mesenchymal transition (EMT) in the developing kidney, we tested the expression of EMT markers and nestin in angiotensin converting enzyme (ACE) inhibitor-treated kidneys. Methods:Newborn rat pups were treated with enalapril (30 mg/kg/d) or a vehicle for 7 days. Immunohistochemistry for the expression of α-smooth muscle actin (SMA), E-cadherin, vimentin, and nestin were performed. The number of positively-stained cells was determined under 100 magnification in 10 random fields. Results:In the enalapril-treated group, αSMA-positive cells were strongly expressed in the dilated tubular epithelial cells. The number of αSMA-positive cells in the enalapril-treated group increased in both the renal cortex and medulla, compared to the control group (P<0.05). The expression of E-cadherin-positive cells was dramatically reduced in the cortical and medullary tubular epithelial cells in the enalapril-treated group (P<0.05). The number of vimentinand nestin-positive cells in the cortex was not different in comparisons between the two groups; however, their expression increased in the medullary tubulointerstitial cells in the enalapril-treated group (P<0.05). Conclusion:Our results show that ACE inhibition in the developing kidney increases the renal EMT by up-regulating αSMA and down-regulating E-cadherin. Enalapril treatment was associated with increased expression of vimentin and nestin in the renal medulla, suggesting that renal medullary changes during the EMT might be more prominent, and ACE inhibition might differentially modulate the expression of EMT markers in the developing rat kidney. (Korean J Pediatr 2009;52:944-952)