Interstitial Fibrosis In Rats Research Articles

The Expression and Molecular Mechanisms of Matrix Metalloproteinase-9 and Vascular Endothelial Growth Factor in Renal Interstitial Fibrosis in Rats

Abstract: To explore a new approach for the treatment of renal interstitial fibrosis (RIF), we detected the expression of matrix metalloproteinase-9 (MMP9) and vascular endothelial growth factor (VEGF). Twenty-four male Sprague Dawley (SD) rats were randomly divided into 2-week normal control (2NC) group, 4-week NC (4NC) group, 2- week unilateral ureteral obstruction (2UUO) group, and 4-week UUO (4UUO) group. We performed left ureteral ligation on UUO groups. Then, we sacrificed the rats of the 2NC group and 2UUO group at 2 weeks and the other groups at 4 weeks after the surgery. Immunohistochemistry and western blot were applied to detect the expression of MMP9, VEGF, fibronectin (FN), type IV collagen (Col-IV), and transforming growth factor-β1 (TGF-β1). MMP9 levels reduced after UUO surgery. Its expression was less in the 4UUO group than in the 2UUO group (P<0.05). The expression of VEGF, TGF- β1, FN, and Col-IV was higher in UUO groups than in NC groups (P<0.05). The expression of these indicators was higher in the 4UUO group than in the 2UUO group (P<0.05). In the correlation analysis, MMP9 levels in UUO groups had a negative correlation with the expression of TGF-β1, VEGF, Col-IV, FN, and RIF index (all P<0.05). In UUO groups, VEGF levels had a positive correlation with the expression of TGF-β1, Col-IV, FN, and RIF index (all P<0.05). In conclusion, with the aggravation of RIF lesions, MMP9 levels decreased, and VEGF levels increased. Whether there is a mutual inhibition relationship between them remains to be confirmed by further experiments.

Improvement on renal interstitial fibrosis in rats with renal failure via TLR4/NF-κB signaling pathway by means of panax notoginseng saponins

Panax notoginseng saponins (PNS) have excellent effects on treating cardiovascular and cerebrovascular diseases, tumors and organ interstitial diseases. This study assessed the effect of PNS on renal interstitial fibrosis (RIF). Four groups of models were firstly created, which included; renal failure model, healthy group, model group, PNS group, and then established TLR4 inhibitor group (TAK-242 group), TLR4 activator group (LPS group), combined PNS and TLR4 inhibitor group (PNS+ TAK-242 group) and combined PNS and TLR4 agonist (PNS+LPS group). TLR4/NF-κB signaling pathway and regulatory mechanism for PNS were observed along with analysis of TGF-β1, α-SMA, Collagen I and FN expressions in kidney tissues. The PNS significantly inhibited changes of renal interstitial fibrosis in rats with renal failure, and this process was related to decreased expressions of TLR4 and NF-κB. The PNS also inhibited the expression of TLR4, and expressions of TGF-β1, α-SMA, Collagen I and FN were down-regulated in kidney cells after using TAK-242, especially in the PNS+TAK-242 group. The PNS can thus significantly inhibit the process of renal fibrosis, and this process is due to the fact that, PNS inhibits the activity of TLR4/NF-κB signaling pathway to down-regulate the expressions of fibrosis-related factors TGF-β1, α-SMA, etc., in exerting its effects.

Retracted: Exploring the Effect of Dapagliflozin on Alcoholic Kidney Injury and Renal Interstitial Fibrosis in Rats Based on TIMP-1/MMP-24 Pathway.

[This retracts the article DOI: 10.1155/2021/6538189.].

Inhibitory Effects of Rhein on Renal Interstitial Fibrosis via the SHH-Gli1 Signal Pathway.

Background Rhein is the main extract of Rheum palmatum L., which has been proved to improve the renal function of chronic kidney disease, but its mechanism is not clear. Therefore, this experiment explored the potential pharmacological effect of rhein on renal interstitial fibrosis rats. Methods This study explores the potential pharmacological action of rhein. In this work, we investigate the potential pharmacological action of rhein in unilateral urethral obstruction (UUO) rats. Thirty Sprague Dawley rats were randomly divided into three groups: sham, UUO, and rhein (rhein-treated UUO rats) groups. The left ureters of the UUO group rats were exposed and bluntly dissected. The rhein group rats were administered an intragastric gavage of rhein (2 mg·kg−1·d−1) for 14 d. Kidney function-related indicators were monitored in these rats, while indexes of pathologic aspects were determined histologically. The expression of α-SMA, TGF-β1, SHH, Gli1, and Snail was quantified using real-time polymerase chain reaction and western blotting. The NRK-49F cells were incubated with and without SHH (100 ng·ml−1) for 48 hours. The SHH-activated NRK-49F cells were incubated with cyclopamine (CNP, 20 umol L−1) or rhein (1 ng·ml−1). The Gli1 and Snail mRNA and protein level were detected. Results In the in vivo experiment, the results exhibited that UUO caused renal pathological damages. However, these changes could be significantly reversed by the administration of rhein. Compared with the untreated UUO group, the rhein group showed reduced kidney tubular atrophy and necrosis, interstitial fibrosis, hyperplasia, and abnormal deposition of extracellular matrix. Rhein reduced the RNA and protein expression of SHH, Gli1, and Snail of the UUO rats. In the in vitro experiment, CNP or rhein treatment decreased the expression of Gli1 and Snail on mRNA and protein levels in SHH-induced NRK-49F cells, suggesting that CNP or rhein suppresses SHH-induced NRK-49F activation. Taken together, these results demonstrated that rhein suppresses SHH-Gli1-Snail signal pathway activation, with potential implications for the treatment of renal fibrosis. Conclusions Treatment with rhein remarkably ameliorated renal interstitial fibrosis in UUO rats by regulating the SHH-Gli1-Snail signal pathway.

Morphological pattern of kidneys in rats with infravesical urinary obstruction following administration of biologically active compositions containing neurotrophic factors

Abstract. The research aimed to study the morphological characteristics of kidneys after intraperitoneal administration of biologically active compositions (BACs) in rats with infravesical obstruction (IVO).
 Methods. IVO was reproduced by surgical ligation. BACs were injected intraperitoneally for 10 days. The morphometric parameters of the kidneys were determined by examining their structure (the areas of renal corpuscle, glomerulus, the cavity of the glomerular capsule, outer and inner diameters of the tubules, the tubular index, the outer diameter and area of the vascular lumen). The experimental animals were divided into the following groups: Group 1 was saved as an intact control group, Group 2 received “Cortexin”, Group 3 was given CMCNMG, Group 4 received BCM, and Group 5 was not treated (U).
 Results. BACs obtained from a culture of native mantle gliocytes (MG) and BCM were involved in the remodeling of the kidneys’ structure being changed during IVO. The renal corpuscle area was found to be increased in groups 2, 4, and 5 by 42.3%, 193.9%, and 72.3%, respectively, compared with the control group. At the same time, the extent of renal corpuscle hypertrophy in group 3 was minimal and approached the control values. The glomerulus area expanded by 35.4%, 181.1%, and 34% in animals of groups 3, 4, and 5, respectively, compared with the control group. However, the difference in the index between group 5 and BAC-treated animals was not significant, except for group 4. The Bowman's capsule area increased by 117.6%, 235.8%, and 186%, in groups 2, 4 and 5, respectively, compared with the control group. Interestingly, the values in groups 1 and 3 were in agreement but differed from group 5. The lowest values of outer and inner diameters of renal tubules were determined in group 3, which were close to those in the control group but significantly different from those of other groups. An increased tubular index (by 1.35 and 1.4 times) was revealed in groups 3 and 4, compared with other groups. The lowest values were found in groups 2 and 5. The maximum values of the average diameter and area of the vessel lumen were determined in groups 3 and 4, and the minimum values were obtained in group 5. It is noteworthy that the indices of these groups were significantly different from those of group 5.
 Conclusions. The research results suggest that the phenomena of glomerulosclerosis, tubular atrophy, and renal interstitial fibrosis in rats can be alleviated, as well as the morphological structure of rat kidneys can be partially restored against the background of IVO after administration of CMCNMG and, to a lesser extent, BCM due to the multidirectional action of neurotrophic factors.

Effect of Bushen Qudu Decoction on TGF-β1/Smads signal transduction pathway in rats with chronic renal failure

Purpose: To study the impact of Bushen Qudu Decoction on renal function, renal tissue morphology and TGF-β1/Smads signal transduction pathway in adenine-induced chronic renal failure rats.Methods: 76 rats were assigned to normal group, model group, uremic clearance group, benazepil group, Bushen Qudu decoction gunshan A group and Bushen Qudu decoction Guiza group. Renal failure was induced in rats using intragastric administration of adenine for 30 days. The expressions of TGF-β1, Smad2, Smad3 and Smad6 were determined with immunohistochemistry. Real-time quantitative PCR was employed to assay the mRNA expression of TGF-β1 in each group, while protein expressions of Smad2, Smad3 and Smad6 were determined with western blot. The scores of glomerular and tubulointerstitial lesions in each group were obtained by histopathological examination.Results: Bushen Qudu decoction significantly reduced BUN and creatinine in rats with chronic renal failure; furthermore, it also lowered the protein expressions of TGF-β1 and SMAD2/3, but Smad6 protein, relative to control (p < 0.05). The TGF-β1mRNA expression was down-regulated (p < 0.05), relative to control group.Conclusion: Bushen Qudu decoction reduces renal interstitial fibrosis in rats and delays the progression of chronic renal failure by regulating TGF-β1/Smads signaling pathway. These findings provide some insight that should facilitate the development of new drugs that would delay the onset of chronic renal failure.

Adefovir accumulation in the renal interstitium triggers mast cell degranulation and promotes renal interstitial fibrosis

Organic anion transporters 1 (OAT1) and OAT3 are responsible for transporting adefovir (ADV) into renal tubular epithelial cells. Our previous research found that ADV accumulated in the renal interstitium and caused renal interstitial fibrosis when Oat1/3 were inhibited by OATs inhibitor probenecid for long-term. Mast cells (MCs) in the interstitial space are considered to be key drivers of renal fibrosis. The current work investigated the effect of ADV on MCs in vitro and during the development of interstitial fibrosis in rats. Results indicate that ADV triggers chymase release from cultured RBL-2H3 mast cells in a time-and concentration-dependent manner. Angiotensin II (Ang II) in renal interstitium is generated mainly by chymase, renin and other products released from MCs, and has a direct effect on fibrosis through the angiotensin receptor. The concentrations of Ang II and fibrosis was significantly increased after administration of ADV alone or with probenecid for 4 weeks. The MCs membrane stabilizer sodium cromoglycate (SCG) and the angiotensin receptor antagonist Valsartan (VAL) could ameliorate ADV-induced nephrotoxicity. Additionally, SCG or VAL could reduce the accumulation of ADV in the renal interstitium by upregulating the expression of Oat1/3 and multidrug resistance-associated protein 4. Therefore, ADV accumulation in the renal interstitium could promote the degranulation of interstitial MCs and drive the development of renal fibrosis. SCG or VAL could ameliorate ADV-associated fibrosis by decreasing degranulation of MCs and accelerating renal clearance of ADV.

The mTOR inhibitor everolimus attenuates tacrolimus-induced renal interstitial fibrosis in rats

AimsTacrolimus—a widely used immunosuppressant to prevent allograft rejection after organ transplantation—is nephrotoxic, increasing the risk of kidney injury accompanied by kidney fibrosis. The mammalian target of rapamycin (mTOR) inhibitor, everolimus, is an immunosuppressant used together with tacrolimus. Although mTOR signaling inhibition has been demonstrated to exhibit antifibrotic effects, the efficacy of everolimus against tacrolimus-induced kidney fibrosis has not been explored. Therefore, we evaluated the protective effects of everolimus against tacrolimus-induced kidney fibrosis. Main methodsTo assess antifibrotic effect of everolimus against tacrolimus-induced kidney fibrosis, male Wistar rats were subcutaneously administered vehicle or tacrolimus (5 mg/kg per day) and/or everolimus (0.2 mg/kg per day) for 2 weeks after bilateral renal ischemia for 45 min. The antifibrotic effect of everolimus was also assessed using rat kidney fibroblast cell line (NRK-49F). Key findingsTacrolimus administration increased predominant profibrotic cytokine transforming growth factor-β (TGF-β) and fibroblast activation marker α-smooth muscle actin (α-SMA) expression and promoted the infiltration of macrophages in the kidney cortex, resulting in renal interstitial fibrosis in rats. Tacrolimus increased serum creatinine, blood urea nitrogen, kidney injury molecule-1 (KIM-1), and kidney injuries, such as tubular dilation, vacuolization, and glomerular atrophy. Everolimus administration attenuated tacrolimus-induced kidney fibrosis and the associated abnormalities. Everolimus strongly suppressed TGF-β-induced kidney fibroblast activation and extracellular matrix protein expression by the mTOR signaling inhibition. SignificanceWe demonstrated that everolimus attenuates tacrolimus-induced renal interstitial fibrosis in rats. Owing to its protective effect against tacrolimus-induced kidney fibrosis, everolimus may be useful when used concomitantly with tacrolimus.

Exploring the Effect of Dapagliflozin on Alcoholic Kidney Injury and Renal Interstitial Fibrosis in Rats Based on TIMP-1/MMP-24 Pathway.

Objective To establish a rat model of alcoholic kidney injury and detect the expression of TIMP-1/MMP-24 in the kidneys of rats with alcoholic kidney injury at the molecular pathological level, so as to explore the mechanism of alcohol abuse leading to kidney injury and renal interstitial fibrosis as well as the alleviation of alcohol-induced kidney injury and inhibition of renal interstitial fibrosis by dapagliflozin. Methods 48 male rats were randomly divided into 4 groups: control group, alcohol group, alcohol + dapagliflozin group, and alcohol + losartan group, each with 12 rats. Different drugs were administered by gavage for modeling and treatment. Six days later, the rats were sacrificed, blood was collected from the heart to separate the serum, and the blood creatinine (Scr) and urea nitrogen (BUN) contents were detected biochemically. After blood collection, the kidney tissue was taken and fixed in10% neutral formalin. The expression of renal tissue inflammatory factors (CRP, IL-6, and TNF-α) and renal fibrosis indexes (LN, HA, and TGF-β1) were detected; MMP-24 and TIMP-1 in the kidney tissue of rats in different treatment groups were detected, and Smad3 expression was also detected. Results After treatment, the general condition of the alcohol + dapagliflozin group and the alcohol + losartan group improved to different degrees. The weight first decreased and then gradually increased over time. There was no statistical difference in the weight change between the two groups; Compared with the control group, the Scr level, BUN content, renal index, inflammatory factors, and renal fibrosis indexes in the alcohol group were significantly increased (P < 0.05); after 6 weeks of treatment, in the alcohol + dapagliflozin group and alcohol + losartan group, Scr level, BUN content, kidney index, inflammatory factors, and renal fibrosis indexes were significantly decreased (P < 0.05); the expression of MMP-24 in the kidney tissue of the control group was upregulated, and the expression of TIMP-1 and Smad3 was downregulated; MMP-24 expression was downregulated, and TIMP-1 and Smad3 expression was significantly upregulated (P < 0.05) in the rats of the alcohol group. After dapagliflozin and losartan treatment, MMP-24 expression gradually increased and TIMP-1 and Smad3 expression gradually decreased (P < 0.05). Conclusion Long-term large-scale alcohol intake can cause kidney tissue damage and fibrotic lesions. The expression of fibrotic cytokines such as TIMP-1 and Smad3 will increase, and the expression of MMP-24 will be decreased. However, dapagliflozin and losartan have certain therapeutic effects on the abovementioned lesions. The mechanism may be downregulating TIMP-1 and Smad3 and upregulating the expression of MMP-24 and other cytokines in the kidney.

FC 044THE LONG-TERM EFFECTS OF ACUTE KIDNEY INJURY ON INTESTINAL OXALATE-DEGRADING BACTERIA IN RATS

Abstract Background and Aims Gut microbiota is considered an important factor affecting oxalate handling in the intestine. It has been demonstrated that intestinal oxalate secretion provides a complementary route of excretion, and it becomes more evident when kidney function declines. A diversity of gut oxalate-degrading bacteria (ODB) has been hypothesized to play a role in this process. However, there is a general lack of research on the long-term effects of acute kidney injury (AKI) on ODB and their total oxalate-degrading activity (ODA) in fecal microbiota. In this study, we evaluated whether renal dysfunction could affect intestinal ODB and their total ODA in a rat model of glycerol-induced AKI. Method The Male Wistar rats (200-300 g, n=20) on oxalate-free diet were randomly divided into 2 groups. After 24-h of water deprivation, Group 1 (n=10) received an intramuscular injection of 50% glycerol (10 ml/kg of body weight), and Group 2 (n=10) served as control. The numbers of ODB (incubated in a highly selective Oxalate Medium and determined using culture method) and total fecal ODA were measured after injection on days 7 and 70. The method of redoximetric titration with a KMnO4 solution was adopted to evaluate total ODA in fecal microbiota; the results were expressed as % of oxalate degradation per 0.01 g of feces. Renal injury was assessed by histopathological examination, serum creatinine and daily proteinuria levels after removing the animals from the experiment on day 70. Cortical interstitial fibrosis was measured by computerized image analysis on sections stained with picrosirius red. The median (Me) and the interquartile ranges (Q25; Q75) were calculated and compared using the nonparametric Mann-Whitney test. The Spearman correlation coefficient was used to evaluate association between the examined parameters. Results The obtained results demonstrated: 1) after glycerol injection on day 7, no differences were found in the numbers of ODB and total fecal ODA between the experimental and control groups: 5.9 (5.4-6.0) vs 6.0 (5.4-6.4) CFU/g, p=0.65 and 2.0 (0.1-5.0) vs 2.5 (2.0-9.0) %/0.01g, p=0.24, respectively; 2) after AKI initiation on day 70, the numbers of ODB and total fecal ODA were significantly lower in Group I compared with control Group II (Fig. 1); 3) the higher percentage of renal interstitial fibrosis was, the higher total fecal ODA occurred in the experimental rats (Fig. 2). In addition, the number of ODB in feces in Group 1 had an inverse association with serum creatinine (r=-0.52, p=0.006) and 24-h proteinuria levels (r=-0.86, p&amp;lt;0.0001). Conclusion AKI had the long-term negative effects on the quantitative and qualitative characteristics of ODB in fecal microbiota in rats. Moreover, the results of our study confirmed an increasing trend in total fecal ODA according to the aggravation of renal interstitial fibrosis in rats.

Infrasound exposure promotes development of atrial fibrosis in rats

Introduction Recent data has shown a significant association between noise exposure and atrial fibrillation (AF) in a large cohort [1] but the pathophysiology remains unclear. The acoustic spectrum of industrial environments is particularly rich in high-intensity infrasound (IFS), which we have previously found to induce coronary perivascular fibrosis in rat hearts [2–4]. The role of atrial fibrosis in AF is well documented and remains the cornerstone of atrial pathology in patients with this arrhythmia [5]. The aim of this study was to evaluate and measure the atrial interstitial fibrosis in rats exposed to high-intensity IFS. Material and methods Twelve Wistar rats exposed to high-intensity IFS (110 dB, <20Hz) during a period of 6 weeks and 12 age-matched controls were studied. All the handling and care of the experimental animals was performed by authorised researchers and was done in accordance with the EU Commission on Animal Protection for Experimental and Scientific Purposes (2010/63/EU). Hearts were transversely sectioned and the atrial fragment was selected for analysis. Chromotrope-aniline blue staining was used for histological observation and the images were obtained with an optical microscope using 400× magnifications. For each atrium, three optical fields containing more prominent fibrotic development in the absence of any arterial vessel were selected. The measurement of fibrosis was performed using Image J software. Mann–Whitney test was used to compare the groups. Results The mean values of atrial interstitial fibrosis were 8.96 ± 4.08 and 4.91 ± 1.46, respectively, in IFS-exposed rats and controls. IFS-exposed rats exhibited a significant increase in atrial interstitial fibrosis (p = .005). Discussion and conclusion High-intensity IFS induces atrial interstitial fibrosis in rats. This finding reinforces the need for further experimental and clinical studies concerning the effects of IFS on the heart.

Ginaton injection alleviates cisplatin-induced renal interstitial fibrosis in rats via inhibition of apoptosis through regulation of the p38MAPK/TGF-β1 and p38MAPK/HIF-1α pathways.

Ginaton injection (Ginkgo biloba extract; GBE) has been reported to protect against cisplatin-induced acute renal failure in rats. In the present study, the effects and molecular mechanisms of GBE on cisplatin-induced renal interstitial fibrosis were evaluated using a rat model. The rats were intraperitoneally injected with cisplatin once on the first day and a subset of rats were treated with GBE or SB203580 (SB; a specific p38 MAPK inhibitor) daily from days 22 to 40. The levels of N-acetyl-β-D-Glucosaminidase (NAG) in the urine, and of urea nitrogen (BUN) and creatinine (Scr) in the blood were assessed. The damage and fibrosis of renal tissues were evaluated using hematoxylin and eosin staining, as well as Masson's trichrome staining, respectively. Apoptosis in renal tissues was detected using a TUNEL assay. The protein expression levels of α-smooth muscle actin (SMA), collagen 1 (Col I), Bax, Bcl-2, caspase-3/cleaved caspase-3, hypoxia-inducible factor-1α (HIF-1α), TGF-β1 and p38MAPK, as well as the mRNA levels of p38MAPK in renal tissues were investigated. The results showed that GBE markedly reduced the levels of urinary NAG, Scr and BUN, and renal expression of α-SMA and Col I levels were also reduced. Furthermore, GBE significantly reduced renal tissue injury and the relative area of renal interstitial fibrosis induced by cisplatin. GBE effectively reduced the apoptotic rate of renal tissues, the protein expression levels of Bax, cleaved caspase-3, phospho-p38MAPK, TGF-β1 and HIF-1α, as well as the mRNA expression levels of p38MAPK in renal tissues induced by cisplatin, whereas GBE significantly increased Bcl-2 protein expression. SB exhibited similar effects to GBE, although it was not as effective. In summary, the present study is the first to show that GBE significantly alleviated renal interstitial fibrosis following cisplatin-induced acute renal injury. The mechanisms by which GBE exhibited its effects were associated with the inhibition of apoptosis via downregulation of the p38MAPK/TGF-β1 and p38MAPK/HIF-1α signaling pathways.

All-trans retinoic acid regulating angiopoietins-1 and alleviating extracellular matrix accumulation in interstitial fibrosis rats

All-trans retinoic acid (ATRA) is one of essentially active metabolite of vitamin A, and plays an important role in diverse physiological processes, such as cellular growth and function. Renal interstitial fibrosis (RIF) is a common pathological characteristic of chronic renal disease causing end-stage renal disease currently lacking effective treatment. Low level of Angiopoietins-1 (Angpt-1) is associated with extracellular matrix accumulation and fibrosis diseases. This study was performed to assess the association of ATRA with Angpt-1 in RIF disease. Rats were divided into three groups: group of sham (SHO group), group of unilateral ureteral obstruction group (UUO group), UUO mice administrated daily at the dose of ATRA (ATRA group). Masson-staining was used to detect the histologic lesion. Immunohistochemistry and Western-blot were applied to determine the targeted proteins. RIF score was significantly increased in UUO rats when compared with that of SHO group, and the fibrosis score was notably reduced in ATRA group. Transforming growth factor-β1 (TGF-β1), collagen IV (Col-IV) and fibronectin (FN) expressions in UUO group were significantly up-regulated, whereas Angpt-1 expression was significantly down-regulated compared with the SHO group. ATRA treatment reduced TGF-β1, Col-IV and FN expressions and improved Angpt-1 expression compared with the UUO group. The protein expression of Angpt-1 in kidney tissue of UUO group was negatively correlated with RIF index and protein expressions of Col-IV, FN and TGF-β1. In conclusion, low expression of Angpt-1 was associated with the RIF disease and ATRA treatment can increase the Angpt-1 and alleviate the RIF lesion in UUO rats.

Rhubarb and Astragalus Capsule Attenuates Renal Interstitial Fibrosis in Rats with Unilateral Ureteral Obstruction by Alleviating Apoptosis through Regulating Transforming Growth Factor beta1 (TGF-β1)/p38 Mitogen-Activated Protein Kinases (p38 MAPK) Pathway.

BackgroundRhubarb and astragalus capsule (RAC) has been used in the clinical treatment of chronic kidney disease for decades. However, the mechanism of RAC has not been fully elucidated. This study aimed to investigate the protective effect and mechanisms of RAC on unilateral ureteral obstruction (UUO)-induced renal interstitial fibrosis.Material/MethodsThe main components of RAC are detected by high-performance liquid phase (HPLC). A rat model of UUO was established, and a subset of rats underwent treatment with RAC. Renal function and renal pathology were examined at 14 days and 21 days after the UUO operation. Renal cell apoptosis was detected by TUNEL staining. The levels of Bcl-2 and Bax in the kidney were examined by western blotting, and the levels of collagen I, α-SMA, transforming growth factor (TGF)-β1, and p38 MAPK in the kidneys were detected by immunohistochemistry.ResultsHigh-performance liquid phase chromatography showed that RAC contained 1.12 mg/g aloe-emodin, 2.25 mg/g rhein, 1.75 mg/g emodin, and 4.50 mg/g chrysophanol. Administration of RAC significantly decreased the levels of urinary N-acetyl-β-D-glucosaminidase (NAG), serum blood urea nitrogen (BUN), and creatinine (Scr) and also reduced renal tissue damages and interstitial fibrosis induced by UUO in rats. Moreover, the increased levels of collagen I, α-SMA, TGF-β1, p38 MAPK, and the Bax/Bcl-2 ratio, as well as cell apoptosis in the kidney, were induced by UUO, and were all found deceased by RAC treatment.ConclusionsRAC can improve the renal interstitial fibrosis induced by UUO, and the mechanism may be related to inhibition of renal tubular cell apoptosis via TGF-β1/p38 MAPK pathway.

Effect of enalapril on apoptosis of renal tubular epithelial cells in renal interstitial fibrosis in rats

To observe the effect of enalapril on the apoptosis of renal tubular epithelial cells in renal interstitial fibrosis rats and to explore the mechanism of enalapril on renal interstitial fibrosis. Methods: Twenty-four SD male rats were randomly divided into a sham operation group, a model group and an enalapril group (n=8 in each group). The rats in the model group and the enalapril group underwent the operation of left urethral obstruction to establish the animal model of unilateral urethral obstruction (UUO). Fourteen days later after the operation, all rats were sacrificed and their obstructed kidneys were collected for HE and Masson staining to observe the pathological change of renal tissues. Terminal deoxynucleotidyl transferase-mediated (dUTP) nick end-labeling (TUNEL) staining was used to detect the apoptosis of renal tubular epithelial cells. Immunohistochemistry and Western blotting were used to detect the protein expression of Fas-associated death domain (FADD), apoptotic protease activating factor-1 (APAF-1) and C/EBP homologous protein (CHOP). Results: Compared with the sham operation group, the renal interstitial injury index and renal interstitial fibrosis index were significantly increased in the model group (P<0.05). Compared with the model group, the renal interstitial injury index and renal interstitial fibrosis index were both significantly decreased in the enalapril group (P<0.05). Compared with the sham group, the apoptosis rate of renal tubular epithelial cells was increased in the model group (P<0.05); compared with the model group, the apoptosis rate of renal tubular epithelial cells was significantly reduced in the enalapril group (P<0.05). The protein levels of FADD, APAF-1 and CHOP in the model group were significantly elevated than those in the sham group (all P<0.05), which were reversed in presence of enalapril (all P<0.05). Conclusion: Enalapril can alleviate renal interstitial fibrosis through inhibiting apoptosis of renal tubular epithelial cells in UUO rats.

The mechanism of overexpression of retinoic acid receptor alpha in attenuating renal interstitial fibrosis in rats

Objective To study the mechanism of overexpression of retinoic acid receptor alpha (RARα) in attenuating renal interstitial fibrosis (RIF) in rats. Methods Forty 6-week-old male SD rats were randomly divided into 4 groups: sham operation group, model group, negative control group and transfection group, with 10 rats in each group.Rats in model group were separated and double ligated with left ureter; rats in sham operation group were not ligated with ureter; rats in transfection group and negative control group were transfected with adeno-associated virus and negative control virus carrying RARα gene on the basis of model group, respectively.All rats were sacrificed 2 weeks later.Left kidney tissues were taken for pathological examination and RIF index was calculated.The expression of collagen Ⅳ (Col-Ⅳ) and fibronectin (FN) in renal tissue was detected by using immunohistochemistry.The expressions of RARα, prohibitin (PHB) and transforming growth factor-beta 1 (TGF-β1) in renal tissue were detected by using real-time fluorescence quantitative polymerase chain reaction(RT-qPCR) and Western blot. Results (1)Compared with sham operation group, the RIF index was significantly increased in model group (22.81±2.43 vs.2.34±0.55, q=24.94, P 0.05), however it significantly decreased in transfection group (14.06±2.99 vs.22.81±2.43, q=10.66, P 0.05); compared with model group, the mRNA and protein expression of RARα, PHB mRNA and protein expression significantly increased, but the TGF-β1 mRNA and protein, Col-Ⅳ and FN protein expression significantly decreased in transfected group (mRNA: 0.86±0.07 vs.0.43±0.17, 0.89±0.11 vs.0.34±0.08, 1.65±0.28 vs.2.97±0.54, all P<0.05; protein: 0.40±0.07 vs.0.25±0.10, 0.45±0.10 vs.0.24±0.07, 0.43±0.08 vs.0.59±0.09, 11.57±0.33 vs.16.01±0.87, 11.67±0.53 vs.14.64±0.32, all P<0.05). (3)Correlation analysis revealed that RARα protein expression was negatively correlated with RIF index, Col-Ⅳ, FN, TGF-β1 (r=-0.78, -0.78, -0.76, -0.76, all P<0.05); PHB protein expression was negatively correlated with RIF index, Col-Ⅳ, FN, TGF-β1 (r=-0.87, -0.87, -0.88, -0.75, all P<0.05); RARα protein was positively correlated with PHB (r=0.85, P<0.05). Conclusion Overexpression of RARα could attenuate RIF by enhancing PHB expression in rats subjected to unilateral ureteral obstruction. Key words: Retinoic acid receptor alpha; Prohibitin; Renal interstitial fibrosis; Transfection

Fluorofenidone inhibits apoptosis of renal tubular epithelial cells in rats with renal interstitial fibrosis

This study aimed to investigate the mechanism of fluorofenidone (AKF-PD) in treating renal interstitial fibrosis in rats with unilateral urinary obstruction (UUO). Thirty-two male Sprague-Dawley rats were randomly divided into sham, UUO, UUO + enalapril, and UUO + AKF-PD groups. All rats, except sham, underwent left urethral obstruction surgery to establish the animal model. Rats were sacrificed 14 days after surgery, and serum was collected for renal function examination. Kidneys were collected to observe pathological changes. Immunohistochemistry was performed to assess collagen I (Col I) protein expression, and terminal deoxynucleotidyl transferase-mediated nick end-labeling staining to observe the apoptosis of renal tubular epithelial cells. The expression of Fas-associated death domain (FADD), apoptotic protease activating factor-1 (Apaf-1), and C/EBP homologous protein (CHOP) proteins was evaluated by immunohistochemistry and western blot analysis. AKF-PD showed no significant effect on renal function in UUO rats. The pathological changes were alleviated significantly after enalapril or AKF-PD treatment, but with no significant differences between the two groups. Col I protein was overexpressed in the UUO group, which was inhibited by both enalapril and AKF-PD. The number of apoptotic renal tubular epithelial cells was much higher in the UUO group, and AKF-PD significantly inhibited epithelial cells apoptosis. The expression of FADD, Apaf-1, and CHOP proteins was significantly upregulated in the UUO group and downregulated by enalapril and AKF-PD. In conclusion, AKF-PD improved renal interstitial fibrosis by inhibiting apoptosis of renal tubular epithelial cells in rats with UUO.

Sodium bicarbonate loading limits tubular cast formation independent of glomerular injury and proteinuria in Dahl salt-sensitive rats.

Sodium bicarbonate (NaHCO3) slows the decline in kidney function in patients with chronic kidney disease (CKD), yet the mechanisms mediating this effect remain unclear. The Dahl salt-sensitive (SS) rat develops hypertension and progressive renal injury when fed a high salt diet; however, the effect of alkali loading on kidney injury has never been investigated in this model. We hypothesized that NaHCO3 protects from the development of renal injury in Dahl salt-sensitive rats via luminal alkalization which limits the formation of tubular casts, which are a prominent pathological feature in this model. To examine this hypothesis, we determined blood pressure and renal injury responses in Dahl SS rats drinking vehicle (0.1 M NaCl) or NaHCO3 (0.1 M) solutions as well as in Dahl SS rats lacking the voltage-gated proton channel (Hv1). We found that oral NaHCO3 reduced tubular NH4+ production, tubular cast formation, and interstitial fibrosis in rats fed a high salt diet for 2 weeks. This effect was independent of changes in blood pressure, glomerular injury, or proteinuria and did not associate with changes in renal inflammatory status. We found that null mutation of Hv1 also limited cast formation in Dahl SS rats independent of proteinuria or glomerular injury. As Hv1 is localized to the luminal membrane of TAL, our data suggest that alkalization of the luminal fluid within this segment limits cast formation in this model. Reduced cast formation, secondary to luminal alkalization within TAL segments may mediate some of the protective effects of alkali loading observed in CKD patients.

Effect of fluorofenidone on renal interstitial fibrosis in rats with unilateral ureteral obstruction

To investigate the effect of fluorofenidone on renal interstitial fibrosis in rats with unilateral ureteral obstruction (UUO) and to observe the effect of fluorofenidone on the expressions of collagen type I (Col I), collagen type III (Col III), α-smooth muscle actin (α-SMA), connective tissue growth factor (CTGF), platelet derived growth factor (PDGF) in the renal tissues of UUO rats. Methods: Male Sprague-Dawley (SD) rats were randomly divided into a sham-operated group, a UUO group, and a flurofenidone group (n=5). UUO model was induced by ligating the left ureter in rats. The rats were treated with 125 mg/(kg.d) fluorofenidone by gastric gavage in the fluorofenidone group at 24 h before the operation, and the rats were treated with the identical dose of 0.5% sodium carboxyl methyl cellulose (CMC-Na) in the other 2 groups. The rats were sacrificed at 14 days after UUO. Pathological changes of the renal tissue were observed by HE and Masson staining, the mRNA expressions of Col I, Col III, α-SMA, PDGF and CTGF were detected by real-time PCR, and the protein expressions of Col I, Col III, PDGF and CTGF were detected by immunohistochemical staining. Results: The renal interstitial damage index, relative collagen area and mRNA and protein expressions of Col I and Col III in the renal tissues of the rats in the UUO group significantly increased (P<0.05), and fluorofenidone could reduce these indexes (P<0.05). Compared with the sham-operated group, the protein expressions of α-SMA, PDGF, CTGF and the mRNA expressions of PDGF and CTGF in the renal tissues of the rats in the UUO group were increased, but fluorofenidone could decrease the protein expressions of α-SMA, PDGF, CTGF and the mRNA expressions of PDGF and CTGF (P<0.05). Conclusion: Fluorofenidone (125 mg/kg.d) could attenuate renal interstitial fibrosis through inhibition of fibroblast proliferation, myofibroblastic activation, PDGF and CTGF expression.

Ulinastatin inhibits renal tubular epithelial apoptosis and interstitial fibrosis in rats with unilateral ureteral obstruction.

The effect of ulinastatin (UTI) on renal tubular epithelial apoptosis and interstitial fibrosis in rats with unilateral ureteral obstruction (UUO) was investigated. A total of 18 male Wistar rats were randomly divided into the following 3 groups: The Sham group (n=6), the UUO group (n=6), and the UTI group (n=6). In the UUO and UTI groups, the left ureter was ligated to establish a UUO model. Starting from day 1 after surgery, an intervention treatment was performed using normal saline (1 ml/kg/d) and UTI (40,000 unit/kg/d). On day 7 after surgery, 6 rats from each group were sacrificed. In the Sham group, the left ureter was only freed, not ligated; after 7 days of abdominal closure, all of the rats were sacrificed. Blood samples were collected prior to sacrificing the animals to measure the blood urea nitrogen (BUN) and serum creatinine (Scr). The incidence of renal interstitial lesions on the obstruction side was observed by hematoxylin and eosin, and Masson staining. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, and immunohistochemical detection of apoptosis regulator Bax (Bax), apoptosis regulator Bcl-2 (Bcl-2) and caspase-3 were performed to observe the presence of renal tubular epithelial cell apoptosis. The UTI did not have a significant influence on the mouse BUN and Scr levels in any of the groups (P>0.05). Compared with that in the Sham group, renal tissue injury in the UUO group was significantly aggravated with renal tubular dilation, epithelial cell atrophy, renal interstitial inflammatory cell infiltration and fibrous tissue hyperplasia (P<0.01). Furthermore, the renal tubular epithelial TUNEL+ cell number and Bax and caspase-3 levels were increased, and the expression of Bcl-2 was decreased (P<0.01). Following the UTI treatment, the renal interstitial injury at the obstruction side was significantly attenuated (P<0.05), the renal tubular epithelial TUNEL+ cell number, and Bax and caspase-3 levels significantly decreased, and the expression of Bcl-2 was restored (P<0.05). UTI inhibited renal tubular epithelial apoptosis and interstitial fibrosis in UUO rats.