Partial unilateral ureteral obstruction in rats

Urinary Cytochrome C and Caspase-3 as Novel Biomarker of Renal Function Impairment in Unilateral Ureteropelvic Junction Obstruction Model of Wistar Rats

Introduction

Prolonged obstruction in UPJO would lead to kidney destruction. It is important to find a non-invasive biomarker for early detection of renal impairment before definitive treatment for UPJO. In this study, we aim to evaluate the role of urinary cytochrome c and caspase-3 as a novel biomarker to predict renal function impairment in a UPJO model in Wistar rats.

Methods

Twenty-five male Wistar rats were separated into 3 groups. Group I consists of 5 rats without any treatment or model, group II consists of 5 rats (sham group), and group III consists of 15 rats with the unilateral partial ureteral obstruction model. After 4, 15, and 21 days of observation, the urine was collected and rats were sacrificed to collect the glomerular count in the kidney. Measurement of cytochrome c and caspase-3 was done using the ELISA method, while the glomerular count was done using a light microscope. Data were analyzed using factorial repeated measures ANOVA test and correlation test with Pearson and processed using SPSS version 20.0.

Results

The UPJO group has a significant increase in cytochrome c concentration and caspase-3 concentration compared to the control group and sham group (p<0.05). There was a significant decrease in the normal glomerulus count of the UPJO group (p<0.05). There was a significant relationship between the decrease in glomerulus count with the concentration of cytochrome c and caspase-3 in the UPJO group.

Conclusion

There was a significant relationship between the decrease in glomerulus count with the increase in the concentration of cytochrome c and caspase-3 in the UPJO group.

Protection of tubular epithelial cells during renal injury via post-transcriptional control of BMP7

Severe injury of renal tubular epithelial cells may cause acute renal failure, the progression of which results in renal fibrosis, and obstructive nephropathy. Transforming growth factor β 1 and bone morphogenic protein 7 (BMP7) play contradicting roles in and coordinate the process of epithelial-to-mesenchymal transition of renal tubular epithelial cells, but the molecular regulation of BMP7 remains ill-defined. Here, we addressed this question. We found that after induction of unilateral ureteral obstruction (UUO) in mice, the increases in BMP7 mRNA were much more pronounced than BMP7 protein in kidney, suggesting the presence of post-transcriptional control of BMP7. Moreover, significant increases in a BMP7-targeting microRNA, miR-384-5p, were detected in the mouse kidney post UUO. Overexpression of miR-384-5p significantly decreased BMP7 protein, while depletion of miR-384-5p significantly increased BMP7 protein in renal epithelial cells. Bioinformatics study showed that miR-384-5p appeared to suppress BMP7 protein translation, through its direct binding to the 3'-UTR of BMP7 mRNA. Furthermore, suppression of miR-384-5p in vivo attenuated severity of renal injury by UUO. Together, our study sheds light on miR-384-5p as a crucial factor that regulates the fibrosis-related pathogenesis after renal injury, and points to miR-384-5p as a promising innovative therapeutic target for prevention of renal fibrosis.

A porcine model of relief of unilateral ureteral obstruction: study on self-repairing capability over multiple time points

It is still controversial whether renal tubular interstitial fibrosis (TIF) is a reversible process. Although previous studies examining TIF have been carried out in rodents, their kidney size and physiological character differ with humans, and the difference among diverse individuals before and after damage was obvious. Thus an experimental animal model to simulate human kidney disease was urged to be established. In order to clarify whether TIF is reversible, and the exact time points that the kidney has the capacity to be repaired, a porcine relief of unilateral ureteral obstruction (R-UUO) model was developed. Kidney damage and reparation were observed dynamically in vivo over various time points. Pigs were randomized divided into three groups (n = 6): UUO 5 days group, UUO 7 days, and UUO 10 days group. Each porcine in that groups underwent UUO and subsequent R-UUO for three time points. Renal function, histological structure, and protein expressions of α-smooth muscle actin (α-SMA), vimentin and E-cadherin were evaluated at different time points. Following R-UUO after 5 and 7 days of UUO, compared to UUO, serum creatinine levels were significantly decreased. Renal pathological tissue damage was repaired. The expressions of α-SMA and vimentin were decreased and E-cadherin expression was increased (P < 0.05). However, during R-UUO 14, 28, and 56 days after 10 days of UUO, serum creatinine was not decreased significantly. The expressions of α-SMA and vimentin consistently remained at high levels. Renal damage was unable to be restored and resulted in chronic lesions. Kidney damage induced by UUO can be reversed in early stages. However, longer time of UUO with significant levels of TIF showed limited reversibility. The porcine R-UUO model provides an ideal animal model for the investigation of kidney injury and repair as well as for the evaluation of the effect of drug treatment.

IGF-1 protects tubular epithelial cells during injury via activation of ERK/MAPK signaling pathway

Injury of renal tubular epithelial cells can induce acute renal failure and obstructive nephropathy. Previous studies have shown that administration of insulin-like growth factor-1 (IGF-1) ameliorates the renal injury in a mouse unilateral ureteral obstruction (UUO) model, whereas the underlying mechanisms are not completely understood. Here, we addressed this question. We found that the administration of IGF-1 significantly reduced the severity of the renal fibrosis in UUO. By analyzing purified renal epithelial cells, we found that IGF-1 significantly reduced the apoptotic cell death of renal epithelial cells, seemingly through upregulation of anti-apoptotic protein Bcl-2, at protein but not mRNA level. Bioinformatics analyses and luciferase-reporter assay showed that miR-429 targeted the 3'-UTR of Bcl-2 mRNA to inhibit its protein translation in renal epithelial cells. Moreover, IGF-1 suppressed miR-429 to increase Bcl-2 in renal epithelial cells to improve survival after UUO. Furthermore, inhibition of ERK/MAPK signaling pathway in renal epithelial cells abolished the suppressive effects of IGF-1 on miR-429 activation, and then the enhanced effects on Bcl-2 in UUO. Thus, our data suggest that IGF-1 may protect renal tubular epithelial cells via activation of ERK/MAPK signaling pathway during renal injury.

Oxidative Damage and Mitochondrial Injuries Are Induced by Various Irrigation Pressures in Rabbit Models of Mild and Severe Hydronephrosis

OBJECTIVE

We aimed to study whether tolerance to irrigation pressure could be modified by evaluating the oxidative damage of obstructed kidneys based on rabbit models experiencing different degrees of hydronephrosis.

METHODS

A total of 66 rabbits were randomly divided into two experimental groups and a control group. In the experimental groups, the rabbits underwent a surgical procedure inducing mild (group M, n=24) or severe (group S, n=24) hydronephrosis. In each experimental group, the rabbits were then randomly divided into 4 subgroups (M0-M3 and S0-S3) consisting of 6 rabbits each. Group 0 received no perfusion. Groups 1 through 3 were perfused with 20, 60 and 100 mmHg fluid, respectively. For the control group, after a sham operation was performed, the rabbits were divided into 4 subgroups and were perfused with fluid at 0, 20, 60 or 100 mmHg of pressure. Kidney injuries was evaluated by neutrophil gelatinase associated lipocalin (NGAL). Oxidative damage was assessed by analyzing superoxide dismutase (Mn-SOD) activity, malondialdehyde (MDA) levels, glutathione reductase (GR), catalase (CAT) and peroxide (H2O2) levels, mitochondrial injuries was assessed by mitochondrial membrane potential (MMP), the mitochondrial ultrastructure and tubular cell apoptosis.

RESULTS

In the experimental groups, all results were similar for groups 0 and 1. In group 2, abnormalities were observed in the S group only, and the kidneys of rabbits in group 3 suffered oxidative damage and mitochondrial injuries with increased NGAL, decreased Mn-SOD, GR and CAT,increased MDA and H2O2, lower levels of MMP, mitochondrial vacuolization and an increased apoptotic index.

CONCLUSION

In rabbits, severely obstructed kidneys were more susceptible to oxidative damage and mitochondrial injury than mildly obstructed kidneys when subjected to higher degrees of kidney perfusion pressure.

Augmenter of liver regeneration ameliorates renal fibrosis in rats with obstructive nephropathy

Renal fibrosis is a hallmark in CKD (chronic kidney disease) and is strongly correlated to the deterioration of renal function that is characterized by tubulointerstitial fibrosis, tubular atrophy, glomerulosclerosis and disruption of the normal architecture of the kidney. ALR (augmenter of liver regeneration) is a growth factor with biological functions similar to those of HGF (hepatocyte growth factor). In this study, our results indicate that endogenous ALR is involved in the pathological progression of renal fibrosis in UUO (unilateral ureteral obstruction) rat model. Moreover, we find that administration of rhALR (recombinant human ALR) significantly alleviates renal interstitial fibrosis and reduces renal-fibrosis-related proteins in UUO rats. Further investigation reveals that rhALR suppresses the up-regulated expression of TGF-β1 (transforming growth factor β1) induced by UUO operation in the obstructed kidney, and inhibits Smad2 and Smad3 phosphorylation activated by the UUO-induced injury in the animal model. Therefore we suggest that ALR is involved in the progression of renal fibrosis and administration of rhALR protects the kidney against renal fibrosis by inhibition of TGF-β/Smad activity.

Effect of stem cells on renal recovery in rat model of partial unilateral upper ureteric obstruction

BACKGROUND

Untreated obstructive uropathy produces irreversible renal damage and is an important cause of pediatric renal insufficiency. This study was designed to evaluate the effects of stem cell injection on morphological and pathological changes in the rat kidneys with partial unilateral upper ureteric obstruction (PUUUO).

METHODS

Wistar rats (n = 30) were operated upon to create a PUUUO by the psoas hitch method and were randomized into Group I (control, n = 15) and Group II (stem cell, n = 15); at day 5, 10 and 15, a subgroup of rats (n = 5) from each group was killed and the kidneys harvested. Pathological and morphological changes in the harvested kidneys were studied and compared between the two groups.

RESULTS

Morphologically, at day 15, Group II had significantly (p = 0.04) greater cortical thickness (0.48 ± 0.17 vs. 0.38 ± 0.09 mm). Histologically, at day 5, Group II had significantly (p = 0.032) lower peri-pelvic fibrosis. Group II group showed greater peri-pelvic inflammation as compared to Group I (p = 0.05). At day 10, lower grades of peri-pelvic fibrosis (p = 0.08), interstitial fibrosis (p = 0.037) and tubular atrophy (p = 0.05) were seen in the Group II. At day 15, Group II demonstrated significantly lower parenchymal loss (p = 0.037), glomerulosclerosis (p = 0.08), interstitial fibrosis (p = 0.08), tubular atrophy (p = 0.08) and peri-pelvic fibrosis (p = 0.08).

CONCLUSIONS

In a rat model of PUUUO, stem cell injection prevented detrimental changes in renal pathology and preserved renal parenchymal mass.

Effect of beraprost sodium (BPS) in a new rat partial unilateral ureteral obstruction model

Unilateral ureteral obstruction (UUO) is a representative model for investigating the common mechanism of decreasing renal function in chronic renal failure. In this study, we present a new partial UUO model in adult rats and evaluated the effect of beraprost sodium (BPS: stable prostaglandin I(2) (PGI(2)) analog). We could make reproductive and uniform partial UUO by ligating the left ureter together with a 0.5 mm diameter stainless steel wire with nylon thread, and withdrawing the stainless wire. One week later, the ureteral obstruction was released. After 3 weeks from the release of UUO, all animals of control group, without BPS administration, developed basophilic degeneration of tubular epithelium, tubular dilatation and interstitial fibrosis. The areas of tubular degeneration and fibrosis were significantly reduced in the BPS group, orally administered BPS 300 microg/kg twice a day from the next day of the release of obstruction, than in control group. In conclusion, we can established the adult rat partial UUO-release model and revealed that BPS can inhibit renal tubular damage and tubulointerstitial fibrosis.

Verapamil prevents the apoptotic and hemodynamic changes in response to unilateral ureteral obstruction

INTRODUCTION

Obstruction of the urinary tract has marked effects on renal blood flow, glomerular filtration rate (GFR), and tubular function. Moreover, ureteral obstruction results in an injury response that can progress to irreversible renal fibrosis and tubular atrophy by apoptosis.

METHODS

We examined the effect of a calcium channel blocker (verapamil) on renal functions and the abundance of apoptotic (p53, Fas, proliferating cell nuclear antigen [PCNA]) markers 1 week after Unilateral Ureteral Obstruction (UUO).

RESULTS

Immunohistochemistry studies revealed that UUO was markedly associated with up-regulation in the expression of p53 (1550 +/- 82 vs 100 +/- 23%), Fas (657 +/- 48 vs 100 +/- 31%), and proliferating cell nuclear antigen (945 +/- 70 vs 100 +/- 17% of sham levels). Administration of verapamil normalized the up-regulation of apoptotic markers p53 (724 +/- 116 vs 1550 +/- 82%); Fas (162 +/- 38 vs 657 +/- 48%) and PCNA (353 +/- 54 vs 945 +/- 70%). Furthermore, tubular diameter, as an important marker for detecting tubular atrophy was significantly decreased compared to those in UUO rabbits. The percent area of interstitial fibrosis in UUO kidneys was significantly greater than that in Verapamil-treated kidneys. Importantly, Verapamil reduced the development of interstitial fibrosis in UUO rabbits. We measured the GFR and renal blood flow in UUO. Short-term Verapamil challenge partially prevented the decrease in GFR (non-treated UUO: 62 +/- 14; Verapamil + UUO: 119 +/- 7; Sham: 127 +/- 23 microL x min(-1) x kg body wt(-1), P < 0.05) and renal blood flow (non-treated UUO: 1.1 +/- 0.4; Verapamil + UUO: 5.0 +/- 0.2; sham: 6.3 +/- 0.2 mL x min(-1) x kg body wt(-1), P < 0.05).

CONCLUSION

Verapamil significantly prevents impairment in renal function and also prevents the up-regulation of p53, Fas, and PCNA during UUO, demonstrating a marked renoprotective effect of Verapamil treatment in conditions with urinary tract obstruction.

The effect of partial unilateral ureteral obstruction release and allopurinol on the renal malondialdehyde and glutathione levels

PURPOSE

The aim of the present study was to evaluate whether relief of partial unilateral ureteral obstruction (PUUO) with or without antioxidant drug affect renal tissue malonedialdehyde (MDA) and glutathion (GSH) levels.

MATERIALS AND METHODS

A total of 25 rats were used in this PUUO study. Partial unilateral ureteral obstruction was created by the burial of the upper one-third of the left ureter in the psoas muscle. The rats were sacrificed on 28th day following PUUO. Relief of the obstruction was performed twenty minutes before sacrifice by cutting the proximal ureter in reperfusion group. 50 mg/kg intraperitoneal allopurinol was administered 20 minutes before relief of obstruction in the antioxidant group. Renal tissue MDA and GSH levels were measured in both kidneys.

RESULTS

At the end of the study 5, 7 and 7 rats could only be interpreted in sham, reperfusion and antioxidant groups, respectively. While the mean left and right renal MDA and GSH levels were statistically different from each other in reperfusion group (P < 0.001), there were no significant differences in the sham (P > 0.05) and antioxidant (P > 0.05) group. Both the mean sham group left and right renal tissue MDA or GSH levels were significantly different from reperfusion group, but only the mean sham group left renal tissue MDA and right renal tissue GSH levels were not statistically different from antioxidant group (P < 0.05). The mean left or right renal MDA and GSH tissue levels of the antioxidant group were statistically different from reperfusion group (P < 0.05) except for the right renal tissue GSH level (P > 0.05).

CONCLUSION

Partial unilateral ureteral obstruction leads to oxidative injury by relief of obstruction in both kidneys. The antioxidant allopurinol has a beneficial effect on renal MDA and GSH levels in both kidneys.

Voie excrétrice supérieure : physiologie, physiopathologie des obstructions et explorations fonctionnelles

The urine is transported from the renal papilla to the bladder through the upper urinary tract which allows this transport to be safe and comfortable, i.e., without any risk or pain for the kidney. This active transport depends on the smooth muscle contractile properties. The upper urinary tract is totally autonomous; this feature allows the preservation of its function after renal transplantation. However, despite its accessory role, the autonomous nervous system can modulate its activity. Upper urinary tract obstruction involves adaptative mechanisms which are different depending on the type (acute, chronic, acquired or congenital) of obstruction. Functional evaluations of the upper urinary tract are aimed at identify the urine transport conditions and the relationship between obstruction and clinical conditions such as hydronephrosis, pain or impaired renal function.

Functional sodium magnetic resonance imaging of the intact rat kidney

BACKGROUND

Renal fluid homeostasis depends to a large extent on the sodium concentration gradient along the corticomedullary axis. The spatial distribution and extent of this gradient were previously determined by invasive methods, which yielded a range of results. We demonstrate here the capacity of sodium magnetic resonance imaging (MRI) to quantify non-invasively renal sodium distribution in the intact kidney.

METHODS

Sodium MRI was applied to study normal, diuretic, and obstructed rat kidneys in vivo. The images were recorded at 4.7 Tesla using a 3-dimensional gradient echo sequence, with high spatial and temporal resolution. The tissue sodium concentration (TSC) was obtained by taking into account the measured nuclear relaxation rates and MRI visibility relative to a reference saline solution.

RESULTS

The corticomedullary sodium gradient increased linearly from the cortex to the inner medulla by approximately 31 mmol/L/mm, from a TSC of approximately 60 mmol/L to approximately 360 mmol/L. Furosemide induced a 50% reduction in the inner-medulla sodium and a 25% increase in the cortical sodium. The kinetics of these changes was related to the specific site and mechanism of the loop diuretic. Distinct profiles of the sodium gradient were observed in acute obstructed kidneys, as well as spontaneously obstructed kidneys. The changes in the sodium gradient correlated with the extent of damage and the residual function of the kidneys.

CONCLUSION

Quantitative assessment of the renal corticomedullary sodium gradient by high resolution sodium MRI may help verify new aspects of the kidney concentrating mechanism and serve as a non-invasive diagnostic method of renal function.

Ureteropelvic junction obstruction causes histologic alterations in contralateral kidney

BACKGROUND/PURPOSE

Ureteropelvic junction (UPJ) obstruction causes histologic alterations both in ipsilateral and contralateral kidney. Because these alterations directly affect the fate of renal damage, definition of these alterations is of utmost importance from the clinical point of view. Thus, an experimental study is designed to determine the alterations of renal histology in response to partial and complete UPJ obstruction.

METHODS

Fifteen adult female New Zealand rabbits were assigned randomly into 3 groups (each containing 5 rabbits) according to the degree of unilateral UPJ obstruction as group I, sham operation was performed and served as the control group; group II, partial UPJ obstruction was made; group III, complete UPJ obstruction was made. The animals in group I and II were killed after 3 weeks, and animals in group III were killed after 2 weeks. Tissue samples were prepared and processed according to routine light microscopic tissue processing.

RESULTS

UPJ obstruction led to glomerulosclerosis, dilatation of proximal and distal tubules of loops of Henle, and dilatation of collecting tubes consistent with necrotic and apoptotic changes in ipsilateral kidneys. Severity of these degenerative changes depended on degree of obstruction. UPJ obstruction also led to histologic alterations on the contralateral kidneys such as glomerular edema, congested blood vessels, dilated tubuli, and necrotic and apoptotic changes in epithelia, which were more prominent in group III than group II.

CONCLUSIONS

It is well known that compensating changes including increased blood flow and parenchymal hypertrophy occurs in contralateral kidney as a response to unilateral UPJ obstruction. However histologic findings of this study confirmed progression of parenchymal damage and presence of apoptosis in contralateral kidney for the first time.