Formin mDia1 contributes to migration and epithelial-mesenchymal transition of tubular epithelial cells exposed to TGF-ß1.

Renal tubular epithelial cells may undergo epithelial-mesenchymal transition (EMT) in response to stimuli, such as transforming growth factor (TGF)-ß1, leading to myofibroblast activation and renal fibrosis. The formin mDia1 is required for nucleation and polymerization of actin and the microtubule cytoskeleton. The present study sought to explore the role of mDia1 in EMT of tubular epithelial cells. A rat model of unilateral ureteral obstruction (UUO) was established. The expression of TGF-ß1, collagen I, collagen III, and mDia1 in the kidneys was examined at day 7 after surgery. The effect of mDia1 on EMT was explored in NRK-52E cells by exposing them to TGF-ß1. Increased expression of TGF-ß1, collagen I, collagen III, and mDia1 was found in obstructive kidneys of UUO model rats. Exposing rat tubular epithelial cells to TGF-ß1 promoted collagen I and collagen III expression but had no effect on mDia1 expression. Silencing mDia1 expression impeded epithelial cell migration as well as reduced TGF-ß1, collagen, and Profilin1 expression, whereas mDia1 overexpression exerted an opposite effect. Furthermore, mDia1 regulated the expression of vimentin, α-smooth muscle actin, and E-cadherin and focal adhesion-kinase (FAK)/Src activation through Profilin1. Inhibition of the mDia1 activator RhoA by fasudil reversed EMT, and FAK/Src activation induced by mDia1. In conclusion, mDia1 regulated tubular epithelial cell migration, collagen expression, and EMT in NRK-52E cells exposed to TGF-ß1. Thus, suppression of mDia1 activation might be a strategy to counteract renal fibrosis.

Ulinastatin attenuates renal interstitial inflammation and inhibits fibrosis progression in rats under unilateral ureteral obstruction.

The aim of the present study was to examine the protective effects of the urinary trypsin inhibitor ulinastatin (UTI) on renal interstitial inflammation and fibrosis in rats subjected to unilateral ureteral obstruction (UUO). A total of 24 male Wistar rats were randomly divided into the three groups; the sham operation (SOR) group (n=8), the UUO group (n=8) and the UUO+UTI group (post­UUO UTI treatment, n=8). UUO was performed with complete ligation of the left ureter. As a medical intervention, saline (4 ml kg­1 d­1) and UTI (40000 units kg­1 d­1) were injected, respectively, into the animals of the corresponding groups on day one following surgery. The rats in all three groups were euthanized on day seven post surgery. Blood samples were harvested for blood urea nitrogen (BUN) and serum creatinine (Scr) content measurements. The degree of interstitial pathological changes in the tissues from the obstructed kidneys were observed through hematoxylin and eosin (H&E) and Masson staining. The CD68+ macrophage amount, tumor necrosis factor­α (TNF­α), interleukin 1ß (IL­1ß), nuclear factor­κB (NF­κB), transforming growth factor­ß1 (TGF­ß1) and type I collagen (Col­I) levels were examined immunohistochemically. The protein expression levels of NF­κB were examined using western blot analysis. Total superoxide dismutase (SOD) activity and malondialdehyde (MDA) content of homogenates were measured spectrophotometrically. The results revealed that ulinastatin had no statistically significant effect on the BUN and Scr levels (P>0.05). However, in comparison with the SOR group, the UUO group exhibited significantly more severe renal interstitial pathological injury in terms of tubular dilation, epithelial atrophy, renal interstitial inflammatory cell infiltration and proliferation of fibrous tissues, as well as significantly elevated levels of interstitial CD68+ macrophages, IL­1ß, TNF­α, NF­κB, TGF­ß1 and Col­I (P<0.01). UTI treatment significantly reduced UUO­induced renal interstitial damage with reduced levels of interstitial CD68+ macrophages, IL­1ß, TNF­α, NF­κB, TGF­ß1 and Col­I and MDA (P<0.05), and increased SOD levels (P<0.05). In conclusion, the present study indicated that UTI is able to effectively inhibit UUO­side renal interstitial inflammatory reaction and fibrosis in UUO­inflicted rats.