Rat Model Of Unilateral Ureteral Obstruction Research Articles

Quantification and Comparison of Anti-Fibrotic Therapies by Polarized SRM and SHG-Based Morphometry in Rat UUO Model

Renal interstitial fibrosis (IF) is an important pathologic manifestation of disease progression in a variety of chronic kidney diseases (CKD). However, the quantitative and reproducible analysis of IF remains a challenge, especially in experimental animal models of progressive IF. In this study, we compare traditional polarized Sirius Red morphometry (SRM) to novel Second Harmonic Generation (SHG)-based morphometry of unstained tissues for quantitative analysis of IF in the rat 5 day unilateral ureteral obstruction (UUO) model. To validate the specificity of SHG for detecting fibrillar collagen components in IF, co-localization studies for collagens type I, III, and IV were performed using IHC. In addition, we examined the correlation, dynamic range, sensitivity, and ability of polarized SRM and SHG-based morphometry to detect an anti-fibrotic effect of three different treatment regimens. Comparisons were made across three separate studies in which animals were treated with three mechanistically distinct pharmacologic agents: enalapril (ENA, 15, 30, 60 mg/kg), mycophenolate mofetil (MMF, 2, 20 mg/kg) or the connective tissue growth factor (CTGF) neutralizing antibody, EX75606 (1, 3, 10 mg/kg). Our results demonstrate a strong co-localization of the SHG signal with fibrillar collagens I and III but not non-fibrillar collagen IV. Quantitative IF, calculated as percent cortical area of fibrosis, demonstrated similar response profile for both polarized SRM and SHG-based morphometry. The two methodologies exhibited a strong correlation across all three pharmacology studies (r2 = 0.89–0.96). However, compared with polarized SRM, SHG-based morphometry delivered a greater dynamic range and absolute magnitude of reduction of IF after treatment. In summary, we demonstrate that SHG-based morphometry in unstained kidney tissues is comparable to polarized SRM for quantitation of fibrillar collagens, but with an enhanced sensitivity to detect treatment-induced reductions in IF. Thus, performing SHG-based morphometry on unstained kidney tissue is a reliable alternative to traditional polarized SRM for quantitative analysis of IF.

Elsholtzia ciliata (Thunb.) Hylander attenuates renal inflammation and interstitial fibrosis via regulation of TGF-ß and Smad3 expression on unilateral ureteral obstruction rat model

BackgroundRenal interstitial fibrosis is characterized by excessive accumulation of extracellular matrix, which leads to end-stage renal failure. PurposeThe aim of this study was to explore the effect of Elsholtzia ciliata (Thunb.) Hylander ethanol extract (ECE) on renal interstitial fibrosis induced by unilateral ureteral obstruction (UUO). Study designAfter quantitative analysis of ECE using the high performance liquid chromatography-photodiode array (HPLC-PDA) method, an in vitro study was performed to assess the anti-inflammatory and anti-fibrotic effects of ECE, using lipopolysaccharide (LPS) and transforming growth factor-ß (TGF-ß), respectively. MethodsFor in vivo study, all male Sprague Dawley (SD) rats (n=10/group), except for those in the control group, underwent UUO. The rats were orally treated with water (control), captopril (positive control, 200mg/kg), and ECE (300 and 500mg/kg) for 14 days. ResultsIn ECE, luteolin and rosmarinic acid were relatively abundant among the other flavonoids and phenolic acids. ECE treatment ameliorated LPS-induced overexpression of nuclear factor-κB, tumor necrosis factor (TNF-α), and interleukin-6 and improved oxidative stress in RAW 264.7 cells. Furthermore, ECE treatment suppressed TGF-ß-induced α-smooth muscle actin and matrix metalloproteinase 9 expression in human renal mesangial cells. In the UUO model, 14 consecutive days of ECE treatment improved UUO-induced renal damage and attenuated histopathological alterations and interstitial fibrosis. Moreover, the renal expression of TNF-α, TGF-ß, and Smad 3 were inhibited by ECE treatment. ConclusionTaken together, the effects of ECE may be mediated by blocking the activation of TGF-ß and inflammatory cytokines, leading subsequently to degradation of the ECM accumulation pathway. Based on these findings, ECE might serve as an improved treatment strategy for renal fibrotic disease.

Artesunate attenuates unilateral ureteral obstruction-induced renal fibrosis by regulating the expressions of bone morphogenetic protein-7 and uterine sensitization-associated gene-1 in rats.

Kidney fibrosis is the most common final stage of progressive renal disease. Bone morphogenetic protein-7 (BMP-7) has been shown to be important in both preservation of kidney function and resistance to injury. Recently, it has been realized that uterine sensitization-associated gene-1 (USAG-1) functions as a kidney-specific BMP antagonist. Because of the reported anti-fibrotic effects of artesunate (Art), this study was designed to investigate the effects of Art on renal fibrosis in unilateral ureteral obstruction (UUO) rats and to explore the underlying mechanisms. Thirty male Sprague-Dawley rats were randomly divided into five groups: Sham group, UUO group, low-dose Art-treated (Art-L), middle-dose Art-treated (Art-M), and high-dose Art-treated (Art-H) groups. The UUO rat model was established by ligating the left ureter. Fourteen days later, interstitial collagen deposition, expression of USAG-1, BMP-7, E-cadherin, α-smooth muscle actin (α-SMA), fibronectin (FN), collagen I, as well as the inflammatory infiltration levels in the kidneys were assessed. Art treatment significantly attenuated the deposition of interstitial collagens in the UUO rats' kidneys and exhibited the ability to improve renal function, followed by the up-regulated expression of BMP-7 and E-cadherin and the down-regulated expression of USAG-1 and α-SMA. In addition, increased macrophages infiltration in the kidneys of the UUO rats were also attenuated by the administration of Art. These results indicate that Art is able to improve the renal function decline and renal fibrosis induced by UUO, which may be associated with the up-regulation of BMP-7 and down-regulation of USAG-1. Accordingly, Art may become a potential preventive or therapeutic agent for chronic kidney diseases.

Mefunidone attenuates tubulointerstitial fibrosis in a rat model of unilateral ureteral obstruction.

BackgroundInflammation has a crucial role in renal interstitial fibrosis, which is the common pathway of chronic kidney diseases. Mefunidone (MFD) is a new compound which could effectively inhibit the proliferation of renal fibroblasts in vitro. However, the overall effect of Mefunidone in renal fibrosis remains unknown.MethodsSprague-Dawley rats were randomly divided intro 6 groups: sham operation, unilateral ureteral obstruction (UUO), UUO/Mefunidone (25, 50, 100mg/kg/day) and UUO/PFD (500mg/kg/day). The rats were sacrificed respectively on days 3, 7, and 14 after the operation. Tubulointerstitial injury index, interstitial collagen deposition, expression of fibronectin (FN), α-smooth muscle actin (α-SMA), type I and III collagen and the number of CD3+ and CD68+ cells were determined. The expressions of proinflammatory cytokines, p-ERK, p-IκB, and p-STAT3 were measured in human renal proximal tubular epithelial cells of HK-2 or macrophages.ResultsMefunidone treatment significantly attenuated tubulointerstitial injury, interstitial collagen deposition, expression of FN, α-SMA, type I and III collagen in the obstructive kidneys, which correlated with significantly reduced the number of T cells and macrophages in the obstructive kidneys. Mechanistically, Mefunidone significantly inhibited tumor necrosis factor-α (TNF-α-) or lipopolysaccharide (LPS)-induced production of proinflammatory cytokines. This effect is possibly due to the inhibition of phosphorylation of ERK, IκB, and STAT3.ConclusionMefunidone treatment attenuated tubulointerstitial fibrosis in a rat model of UUO, at least in part, through inhibition of inflammation.

Urinary Candidate Biomarker Discovery in a Rat Unilateral Ureteral Obstruction Model

Urine has the potential to become a better source of biomarkers. Urinary proteins are affected by many factors; therefore, differentiating between the variables associated with any particular pathophysiological condition in clinical samples is challenging. To circumvent these problems, simpler systems such as animal models should be used to establish a direct relationship between disease progression and urine changes. Obstructive nephropathy is one of the most significant causes of chronic kidney disease, and its predominant end‐stage change is irreversible interstitial fibrosis. To better detect a set of obstructive nephropathy candidate urinary biomarkers, a unilateral ureteral obstruction (UUO) model was used to observe tubular injury and the eventual development of renal fibrosis, as well as to identify differential urinary proteins in this process. In this study, urine samples were collected from the residuary ureter linked to the kidney 1 and 3 weeks after UUO to mimic urine from patients with obstructive nephropathy. Compared with the sham operation group, 7 and 19 significantly changed proteins were identified by LC‐MS/MS in the UUO 1 and 3 week groups, respectively. These proteins identified in rat models of UUO may serve as candidate biomarkers of renal tubular injury and interstitial fibrosis in obstructive nephropathy.

Urinary candidate biomarker discovery in a rat unilateral ureteral obstruction model.

Urine has the potential to become a better source of biomarkers. Urinary proteins are affected by many factors; therefore, differentiating between the variables associated with any particular pathophysiological condition in clinical samples is challenging. To circumvent these problems, simpler systems, such as animal models, should be used to establish a direct relationship between disease progression and urine changes. In this study, a unilateral ureteral obstruction (UUO) model was used to observe tubular injury and the eventual development of renal fibrosis, as well as to identify differential urinary proteins in this process. Urine samples were collected from the residuary ureter linked to the kidney at 1 and 3 weeks after UUO. Five hundred proteins were identified and quantified by LC-MS/MS, out of which 7 and 19 significantly changed in the UUO 1- and 3-week groups, respectively, compared with the sham-operation group. Validation by western blot showed increased levels of Alpha-actinin-1 and Moesin in the UUO 1-week group, indicating that they may serve as candidate biomarkers of renal tubular injury, and significantly increased levels of Vimentin, Annexin A1 and Clusterin in the UUO 3-week group, indicating that they may serve as candidate biomarkers of interstitial fibrosis.

Role of moesin in renal fibrosis.

BackgroundRenal fibrosis is the final common pathway of chronic kidney disease (CKD). Moesin is a member of Ezrin/Radixin/Moesin (ERM) protein family but its role in renal fibrosis is not clear.MethodHuman proximal tubular cells (HK-2) were stimulated with or without TGF-β1. Moesin and downstream target genes were examined by real-time PCR and western blot. Phosphorylation of moesin and related signaling pathway was investigated as well. Rat model of unilateral ureteral obstruction (UUO) was established and renal moesin was examined by immunohistochemistry. Moesin in HK-2 cells were knocked down by siRNA and change of downstream genes in transfected HK-2 cells was studied. All animal experiments were reviewed and approved by the Ethics Committee for animal care of Ruijin Hospital.ResultHK-2 cells stimulated with TGF-β1 showed up-regulated level of α-SMA and down-regulated level of E-Cadherin as well as elevated mRNA and protein level of moesin. In rat model of UUO, renal moesin expression increased in accordance with severity of tubulointerestital fibrosis in the kidneys with ureteral ligation while the contralateral kidneys were normal. Further study showed that TGF-β1 could induce phosphorylation of moesin which depended on Erk signaling pathway and Erk inhibitor PD98059 could block moesin phosphorylation. Effects of TGF-β1 on moesin phosphorylation was prior to its activation to total moesin. RNA silencing studies showed that knocking down of moesin could attenuate decrease of E-Cadherin induced by TGF-β1.ConclusionWe find that moesin might be involved in renal fibrosis and its effects could be related to interacting with E-Cadherin.

Berberine ameliorates renal interstitial fibrosis induced by unilateral ureteral obstruction in rats.

To investigate the potential effects of berberine on renal interstitial fibrosis (RIF) of obstructed kidneys in a unilateral ureteral obstruction (UUO) rat model. Forty-eight rats were randomly divided into three groups: sham-operated, vehicle-treated UUO, and berberine-treated UUO. Rats were gavaged with berberine (200 mg/kg per day) or vehicle. Eight randomly chosen rats in each group were kiled and specimens were collected at day 14 after UUO. Physiological parameters and histological changes were assessed, RIF was evaluated using Masson's trichrome and Sirius red staining, oxidative stress and inflammation markers were determined, transforming growth factor β1 (TGF-β1), phosphorylated Smad3 (pSmad3) and α-smooth muscle actin (α-SMA) were measured using immunohistochemistry or western blotting analysis. The obstruction was relieved at day 14 by percutaneous nephrostomy in the remaining UUO rats. The resistive index of left kidneys was undertaken by coloured Doppler flow imaging at day 14 before nephrostomy and day 7 after the relief. Berberine treatment significantly attenuated RIF induced by UUO. The UUO-induced reduction in kidney superoxide dismutase and catalase activities increased, whereas elevated kidney malondialdehyde level markedly decreased. Berberine treatment significantly ameliorated UUO-induced inflammation, and decreased TGF-β1, pSmad3 and α-SMA expression of UUO kidneys. Moreover, berberine treatment significantly suppressed the increase of resistive index compared with UUO group at day 14 after UUO as well as day 7 after the relief of obstruction. Berberine treatment ameliorates RIF in a UUO rat model by inhibition of oxidative stress, inflammatory responses, and TGF-β1/pSmad3 signalling.

Losartan attenuates renal interstitial fibrosis and tubular cell apoptosis in a rat model of obstructive nephropathy.

Ureteral obstruction leads to renal injury and progresses to irreversible renal fibrosis, with tubular cell atrophy and apoptosis. There is conflicting evidence concerning whether losartan (an angiotensinII typeI receptor antagonist) mitigates renal interstitial fibrosis and renal tubular epithelial cell apoptosis following unilateral ureteral obstruction (UUO) in animal models. The aim of this study was to investigate the effect and mechanism of losartan on renal tubular cell apoptosis and renal fibrosis in a rat model of UUO. The rats were subjected to UUO by ureteral ligation and were treated with dimethyl sulfoxide (control) or losartan. The controls underwent sham surgery. The renal tissues were collected3, 5, 7 and 14days after surgery for measurement of various indicators of renal fibrosis. UUO increased the expression levels of α‑smooth muscle actin and collagenI, and the extent of renal tubular fibrosis and apoptosis in a time‑dependent manner. Losartan treatment partially attenuated these responses. Progression of renal interstitial fibrosis was accompanied by phosphorylation of signal transducer and activator of transcription3 (STAT3) and altered the expression levels of two apoptosis‑related proteins (Bax and Bcl2). Losartan treatment also partially attenuated these responses. The results indicated that losartan attenuated renal fibrosis and renal tubular cell apoptosis in a rat model of UUO. This effect appeared to be mediated by partial blockage of STAT3 phosphorylation.

HSP47 regulates ECM accumulation in renal proximal tubular cells induced by TGF-β1through ERK1/2 and JNK MAPK pathways

Heat shock protein (HSP)47 is a collagen-specific molecular chaperone that is essential for the biosynthesis of collagen molecules. It is likely that increased levels of HSP47 contribute to the assembly of procollagen and thereby cause an excessive accumulation of collagens in disease processes associated with fibrosis. Although HSP47 promotes renal fibrosis, the underlying mechanism and associated signaling events have not been clearly delineated. We examined the role of HSP47 in renal fibrosis using a rat unilateral ureteral obstruction model and transforming growth factor (TGF)-β(1)-treated human proximal tubular epithelial (HK-2) cells. An upregulation of HSP47 in both in vivo and in vitro models was observed, which correlated with the increased synthesis of extracellular matrix (ECM) proteins and expression of tissue-type plasminogen activator inhibitor (PAI)-1. Blockade of HSP47 by short interfering RNA suppressed the expression of ECM proteins and PAI-1. In addition, TGF-β(1)-induced HSP47 expression in HK-2 cells was attenuated by ERK1/2 and JNK MAPK inhibitors. These data suggest that ERK1/2 and JNK signaling events are involved in modulating the expression of HSP47, the chaperoning effect of which on TGF-β(1) would ultimately contribute to renal fibrosis by enhancing the synthesis and deposition of ECM proteins.

Transforming growth factor-β induces vascular endothelial growth factor-C expression leading to lymphangiogenesis in rat unilateral ureteral obstruction

Inflammation is recognized as an important contributor to lymphangiogenesis; however, in tubulointerstitial lesions in human chronic kidney diseases, this process is better correlated with the presence of myofibroblasts rather than macrophages. As little is known about the interaction between lymphangiogenesis and renal fibrosis, we utilized the rat unilateral ureteral obstruction model to analyze inflammation, fibrosis, lymphangiogenesis, and growth factor expression. Additionally, we determined the relationship between vascular endothelial growth factor-C (VEGF-C), an inducer of lymphangiogenesis, and the profibrotic factor, transforming growth factor-β1 (TGF-β1). The expression of both TGF-β1 and VEGF-C was detected in tubular epithelial and mononuclear cells, and gradually increased, peaking 14 days after ureteral obstruction. The kinetics and localization of VEGF-C were similar to those of TGF-β1, and the expression of these growth factors and lymphangiogenesis were linked with the progression of fibrosis. VEGF-C expression was upregulated by TGF-β1 in cultured proximal tubular epithelial cells, collecting duct cells, and macrophages. Both in vitro and in vivo, the induction of VEGF-C along with the overall appearance of lymphatics in vivo was specifically suppressed by the TGF-β type I receptor inhibitor LY364947. Thus, TGF-β1 induces VEGF-C expression, which leads to lymphangiogenesis.

The role of autophagy in unilateral ureteral obstruction rat model

Autophagy is a cellular process of degradation of damaged cytoplasmic components and regulates cell death or proliferation. Unilateral ureteral obstruction (UUO) is a model of progressive renal fibrosis in the obstructed kidney. And UUO is followed by compensatory cellular proliferation in the contralateral kidney. We investigate the role of autophagy in the obstructed kidney and contralateral kidney after UUO. To obtain the evidence and the patterns of autophagy during UUO, the rats were sacrificed 3, 7 and 14 days after UUO. To examine the efficacy of the autophagy inhibitors, 3-methyladenine (3-MA), the rats were treated daily with intraperitoneal injection of 3-MA (30 mg/kg per day) for 7 days. After UUO, autophagy was induced in the obstructed kidney in a time-dependent manner. Inhibition of autophagy by 3-MA enhanced tubular cell apoptosis and tubulointerstitial fibrosis in the obstructed kidney after UUO. In the contralateral kidney, autophagy was also induced and prolonged during UUO. Inhibition of autophagy by 3-MA increased the protein expression of proliferating cell nuclear antigen significantly in the contralateral kidney after UUO. The Akt-mammalian target of rapamycin (mTOR) signalling pathway was involved in the induction of autophagy after UUO in both kidneys. Our present results support that autophagy induced by UUO has a renoprotective role in the obstructed kidney and regulatory role of compensatory cellular proliferation in the contralateral kidney through Akt-mTOR signalling pathway.

Triptolide attenuates renal interstitial fibrosis in rats with unilateral ureteral obstruction

Extracts of Tripterygium wilfordii Hook F. have been used to treat glomerulonephritis for more than 30 years in China. Most of the anti-inflammatory and immunosuppressive activities of these extracts can be attributed to triptolide (Trip). The present study was to investigate the effect of Trip on renal interstitial fibrosis in a model of unilateral ureteral obstruction (UUO). UUO or sham-operated rats were randomly assigned to receive mycophenolate mofetil (MMF), Trip or vehicle and were killed on days 7 and 14 after UUO or sham operation. Kidney specimens were fixed for immunohistochemistry for myofibroblasts (α-smooth muscle actin, α-SMA), macrophages (ED-1), monocyte chemoattractant protein-1 (MCP-1) and osteopontin. Interstitial collagen deposition and amounts of transforming growth factor-β1 (TGF-β1) were determined by Sirius red staining and enzyme-linked immunosorbent assay, respectively. The mRNA expression of TGF-β1, connective tissue growth factor (CTGF), MCP-1 and osteopontin were measured by real-time polymerase chain reaction analysis. The scores for the density of α-SMA- and ED-1-positive cells, the staining of MCP-1 and osteopontin, interstitial collagen deposition and amounts of TGF-β1 were significantly reduced by MMF or Trip. MMF or Trip significantly reduced the mRNA expression of TGF-β1, CTGF, MCP-1 and osteopontin. Trip significantly attenuated tubulointerstitial fibrosis in a rat UUO model and the effect of Trip on renal fibrosis was similar to that of MMF. Trip may be useful as a potential candidate in the treatment of renal fibrosis.

Effects of proteasome inhibitors on rat renal fibrosis in vitro and in vivo

Transforming growth factor-β (TGF-β) is involved in renal tubulointerstitial fibrosis. Recently, the ubiquitin proteasome system was shown to participate in the TGF-β signalling pathway. The aim of this study was to examine the effects of proteasome inhibitors on TGF-β-induced transformation of renal fibroblasts and tubular epithelial cells in vitro and on unilateral ureteral obstruction (UUO) in vivo. Rat renal fibroblasts NRK-49F cells and tubular epithelial cells, NRK-52E, were treated with TGF-β in the presence or absence of a proteasome inhibitor, MG132 or lactacystin. Rats were subjected to UUO and received MG132 i.p. for 7 days. In cultured renal cells, both MG132 and lactacystin inhibited TGF-β-induced α-smooth muscle actin (α-SMA) protein expression according to both western blotting and immunofluorescent study results. MG132 also suppressed TGF-β-induced mRNA expression of α-SMA and upregulation of Smad-response element reporter activity. However, MG132 did not inhibit TGF-β-induced phosphorylation and nuclear translocation of Smad2. In contrast, MG132 increased the protein level of Smad co-repressor SnoN, demonstrating that SnoN is one of the target molecules by which MG132 blocks the TGF-β signalling pathway. Although the proteasome inhibitor suppressed TGF-β-induced transformation of cultured fibroblasts and tubular epithelial cells, MG132 treatment did not ameliorate tubulointerstitial fibrosis in the rat UUO model. Proteasome inhibitors attenuate TGF-β signalling by blocking Smad signal transduction in vitro, but do not inhibit renal interstitial fibrosis in vivo.

N-acetyl-seryl-aspartyl-lysyl-proline attenuates renal inflammation and tubulointerstitial fibrosis in rats

It has been reported that N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) attenuates renal and cardiac inflammation as well as fibrosis in hypertensive rats. In this study, we investigated these effects using a unilateral ureteral obstruction (UUO) model. Eighteen male Wistar rats were randomly divided into three groups: control, UUO/vehicle and UUO/Ac-SDKP groups. Animal models of renal inflammation and tubulointerstitial fibrosis were established with unilateral ureteral ligation in rats. Ac-SDKP and vehicle were infused subcutaneously by using osmotic mini pumps for two weeks. On the 14th day post-injection, kidney histological changes of each group were observed by hematoxylin-eosin and Masson's stain. Renal macrophage infiltration, together with protein expression and localization of monocyte chemoattractant protein-1 (MCP-1), nuclear factor-kappa B (NF-κB), α-smooth muscle actin (α-SMA) and transforming growth factor-β1 (TGF-β1) in renal tissue was assessed by immunohistochemical staining. Gene expression of MCP-1 and TGF-β1 was analyzed with reverse transcription-polymerase chain reaction. Ac-SDKP-treated animals demonstrated less severe renal inflammation and tubulointerstitial fibrosis. Interstitial fibrosis was significantly attenuated with Ac-SDKP. ED-1 was expressed in the interstitium of the UUO/vehicle group kidneys and decreased with Ac-SDKP treatment. MCP-1, NF-κB, α-SMA and TGF-β1 were increased in the renal interstitium and tubular epithelial cells of the UUO/vehicle group. Ac-SDKP significantly reduced their expressions. Gene expressions of MCP-1 and TGF-β1 were upregulated in the UUO/vehicle group kidneys and were significantly inhibited by Ac-SDKP. In conclusion, in the rat UUO model Ac-SDKP administration protected against renal inflammation and tubulointerstitial fibrosis. The inhibitory effect of Ac-SDKP was mediated by the reduction in the expression of MCP-1, NF-κB, α-SMA and TGF-β1.

Low-dose paclitaxel ameliorates renal fibrosis in rat UUO model by inhibition of TGF-β/Smad activity

Transforming growth factor-β (TGF-β) has a pivotal function in the progression of renal fibrosis in a wide variety of renal diseases. Smad proteins have been identified to have an important function in regulating the expression of extracellular matrix (ECM) proteins through TGF-β signaling pathway. Aberrant TGF-β/Smad signaling can be modulated by stabilization of microtubules with paclitaxel. In this study, we investigated if paclitaxel can attenuate tubulointerstitial fibrosis in a rat model of unilateral ureteral obstruction (UUO). Rats in groups of six were subjected to UUO and received low-dose intraperitoneal injection of paclitaxel (0.3 mg/kg) twice a week. They were killed at day 7 and 14 after UUO or Sham operation. TGF-β signaling cascade and status of various ECM proteins were evaluated by RT–PCR, western blotting and immunohistochemical or immunofluorescence staining. The paclitaxel treatment markedly suppressed Smad2 and Smad3 phosphorylation. This was associated with attenuated expression of integrin-linked kinase, collagens I and III, fibronectin (FN) and α-smooth muscle actin, and a substantial decrease in renal fibrosis in animals that underwent UUO and received paclitaxel. These data indicate that the low-dose paclitaxel ameliorates renal tubulointerstitial fibrosis by modulating TGF-β signaling, and thus, the paclitaxel may have some therapeutic value in humans.

Erythropoietin Attenuates Renal Injury in an Experimental Model of Rat Unilateral Ureteral Obstruction via Anti-Inflammatory and Anti-Apoptotic Effects

Erythropoietin was recently shown to exert important cytoprotective and anti-apoptotic effects in injury models of the brain, heart and kidney. We examined whether erythropoietin also attenuates renal injury in a rat model of unilateral ureteral obstruction via anti-apoptotic and anti-inflammatory actions. We divided Sprague-Dawley rats (Korea Research Institute of Bioscience and Biotechnology, Daejeon, Korea) into 4 groups, including 1-vehicle treated with sham operation, 2-vehicle treated with unilateral ureteral obstruction for 3 days, 3-erythropoietin treatment with sham operation and 4-erythropoietin treatment for unilateral ureteral obstruction for 3 days. The erythropoietin treatment dose was 3,000 IU/kg per day intraperitoneally, administered daily. We compared competitive reverse transcriptase-polymerase chain reaction data on transforming growth factor-beta, tumor necrosis factor-alpha, monocyte chemoattractant protein-1, osteopontin, Fas and Bcl-2. Furthermore, we examined Western blots for caspase-3 and light microscopy findings with hematoxylin and eosin staining. We applied immunohistochemistry for transforming growth factor-beta, ED-1 and caspase-3, and TUNEL in each group. Transforming growth factor-beta, tumor necrosis factor-alpha, monocyte chemoattractant protein-1, osteopontin and Fas mRNA levels in the erythropoietin treated, unilateral ureteral obstruction group were significantly lower than in the obstruction only group. The Bcl-2 mRNA level in the erythropoietin treated obstruction group was significantly higher than in the obstruction only group. Caspase-3 activity in the erythropoietin treated obstruction group was significantly lower than in the obstruction only group. On light microscopy interstitially infiltrated inflammatory cells were significantly decreased in the erythropoietin treated obstruction group compared to the obstruction only group. On immunohistochemistry the erythropoietin treated obstruction group showed significantly fewer reactions for transforming growth factor-beta, ED-1 and caspase-3 compared to the obstruction only group. Erythropoietin treatment in rats with unilateral ureteral obstruction significantly decreased the number of TUNEL positive cells. Erythropoietin exerts renoprotective effects in an experimental unilateral ureteral obstruction rat model via anti-apoptotic and anti-inflammatory actions.

Nonerythropoietic derivative of erythropoietin protects against tubulointerstitial injury in a unilateral ureteral obstruction model

Erythropoietin (EPO), a member of the cytokine type I superfamily, acts to increase circulating erythrocytes primarily by preventing apoptosis of erythroid progenitors, is known to protect tissues and can raise haemoglobin (Hb) concentrations. Recently, a second receptor for EPO comprising the EPO receptor and beta-common receptor has been reported to mediate EPO-induced tissue protection. EPO modified by carbamylation (CEPO) only signals through this second receptor. Accordingly, we hypothesized that treatment with CEPO, which would not increase Hb concentrations, would protect against tubular damage and thereby inhibit tubulointerstitial injuries. We evaluated therapeutic effects of CEPO using a rat unilateral ureteral obstruction model. CEPO decreased tubular apoptosis and alpha-smooth muscle actin (alphaSMA) expression in the absence of polycythaemia, while the untreated obstructed kidneys exhibited increased tubular apoptosis with expanded (alphaSMA) expression. While EPO treatment similarly inhibited tubular apoptosis and alphaSMA expression, EPO treatment increased Hb concentrations and induced a wedge-shaped infarction. We established a therapeutic approach using CEPO to protect against tubulointerstitial injury. The therapeutic value of this approach warrants further attention and preclinical studies.

Inhibition of renal fibrosis by gene transfer of inducible Smad7 using ultrasound-microbubble system in rat UUO model.

TGF-beta is a key mediator in renal fibrosis. Kidney-targeted gene therapy with anti-TGF-beta strategies is expected to have therapeutic potential, but this has been hampered by concerns over the safety and practicability of viral vectors and the inefficiency of nonviral transfection techniques. The present study explored the potential role of TGF-beta/Smad signaling in renal fibrosis in vivo and developed a safe and effective gene therapy to specifically block TGF-beta signaling and renal fibrosis in a rat unilateral ureteral obstruction (UUO) model by transferring a doxycycline-regulated Smad7 gene or control empty vectors using an ultrasound-microbubble (Optison)-mediated system. The Smad7 transgene expression was tightly controlled by addition of doxycycline in the daily drinking water. Groups of six rats were sacrificed at day 7, and the transfection rate, Smad7 transgene expression, and tubulointerstitial fibrosis including alpha-smooth muscle actin and collagen matrix mRNA and protein expression were determined. Compared with the non-ultrasound treatment, the combination of ultrasound with Optison largely increased the transfection rate of FITC-ODN and Smad7 transgene expression up to a 1000-fold, and this was found in all kidney tissues. Compared with normal rats, Smad7 expression within the UUO kidney was significantly reduced, and this was associated with up to a sixfold increase in Smad2 and Smad3 activation and severe tubulointerstitial fibrosis. In contrast, treatment with inducible Smad7 resulted in a fivefold increase in Smad7 expression with complete inhibition of Smad2 and Smad3 activation and tubulointerstitial fibrosis in terms of tubulointerstitial myofibroblast accumulation (85% downward arrow ) and collagen I and III mRNA and protein expression (60 to 70% downward arrow ). In conclusion, the ultrasound-mediated inducible Smad7 gene transfer is a safe, effective, and controllable gene therapy. TGF-beta-mediated renal fibrosis is regulated positively by Smad2/3, but negatively by Smad7. Target blockade of TGF-beta/Smad signaling by expression of Smad7 may provide a new therapeutic potential for renal fibrosis.

PDGF receptor kinase blocker AG1295 attenuates interstitial fibrosis in rat kidney after unilateral obstruction.

The current study was designed to investigate possible effects of the platelet-derived growth factor (PDGF) receptor kinase blocker AG1295 on the development of interstitial fibrosis in rats with unilateral ureteral obstruction (UUO), monitored by ED-A+ fibronectin expression, the number of macrophages, and the presence of myofibroblasts as visualized by immunohistochemistry with monoclonal antibodies (mAb) IST9, mAb ED1, and mAb 1A4, respectively; interstitial fibrosis was quantified by Sirius-Red staining and computer-aided image analysis. Without AG1295 treatment, the Sirius-Red stained area of the control kidneys comprised 6.8 +/- 1.3% of the totally inspected area and increased to 19.0 +/- 1.9% in animals by 14 days and to 23.4 +/- 1.7% by 21 days after UUO. The number of macrophages increased from 4.3 +/- 1.1 in controls to 16.6 +/- 2.6 in animals at 14 days and to 23.2 +/- 4.4 at 21 days after UUO. This was accompanied by an increase in both ED-A+ fibronectin deposition and alpha-smooth muscle actin expression. Treatment with AG1295 (12 mg/kg body weight, daily i.p.) significantly reduced interstitial fibrosis as verified by a smaller Sirius-Red stained area (15.7 +/- 1.9% in animals at 14 days and 17.0 +/- 0.7% at 21 days after UUO) and also by a reduced number of macrophages (12.8 +/- 1.4 in animals at 14 days and 15.5 +/- 3.8 at 21 days after UUO), and by the ED-A+ fibronectin deposition and the number of cells positive for alpha-smooth muscle actin. The study indicates that the PDGF receptor kinase blocker AG1295 is able to decrease interstitial fibrosis in the rat UUO model significantly. The diminution of early fibrosis mediators, i.e., macrophages, ED-A+ fibronectin, and myofibroblast phenotype, points to a modulated fibrosis process via a blockade of PDGF actions.