Medical management of retroperitoneal fibrosis

BACKGROUND

Small series and case reports suggest that a combination of mycophenolate mofetil and prednisone is an efficatious and safe treatment for patients with retroperitoneal fibrosis.

OBJECTIVE

To describe the outcomes of patients with retroperitoneal fibrosis treated with a combination of prednisone and mycophenolate mofetil.

DESIGN

Prospective, case series.

PATIENTS

31 patients with retroperitoneal fibrosis.

SETTING

Single-center tertiary care facility.

INTERVENTION

Prednisone 40 mg administered daily and tapered over 6 months and mycophenolate mofetil 1,000 mg given twice daily.

MEASUREMENT

Clinical course, laboratory assessment, measurement of periaortic mass.

RESULTS

Systemic symptoms resolved in all patients. Eighty-nine percent of patients had a 25% or greater reduction in periaortic mass. Eighteen patients had 32 obstructed ureters. Thirty of these ureters were free of obstruction after an average of 513 days of therapy. Laboratory abnormalities of elevated erythrocyte sedimentation rate and serum creatinine and decreased hemoglobin levels normalized in all patients. Recurrent disease occurred in 2 of 28 patients.

CONCLUSION

Combined prednisone and mycophenolate mofetil appears to be an effective therapeutic option for patients with retroperitoneal fibrosis.

Clinical course of grade I-III megaureters detected on prenatal ultrasound

AIM

Primary obstructive megaureter has always been considered a developmental defect. The aim of this study was evaluate the clinical course of grade I-III megaureter at a single Institution through a longitudinal observational study.

METHODS

Between April 2004 and April 2006 35 cases of megaureter were observed prenatally. Inclusion criteria were created. Conservative treatment was used for all patients and its efficacy was assessed with routine laboratory tests, ultrasounds and renal scintigraphy. Follow-up was at least three years for all patients.

RESULTS

Twenty patients were considered for the study. Single or relapsing infections (36% of patients had more than three urinary tract infections during follow-up) did not seem absolute indications for surgical treatment in these patients, although they are currently the first indication for surgery.

CONCLUSION

Clinical results of the study showed that conservative treatment is an effective treatment option. Single or relapsing infections are not a clear indication for surgery. Long-term follow-up for these patients is mandatory.

[Effect of losartan on renal expression of monocyte chemoattractant protein-1 and transforming growth factor-β(1) in rats after unilateral ureteral obstruction]

OBJECTIVE

To investigate the effect of losartan on the expression of monocyte chemoattractant protein-1 (MCP1) and transforming growth factor-β(1) (TGF-β(1)) in the kidney of rats with unilateral urethral obstruction (UUO) and evaluate protective effect of losartan against reanal interstitial fibrosis.

METHODS

Rat models of UUO were treated with losartan at the routine dose, high dose, and very high dose (50, 200, and 500 mg/kg daily, respectively), and saline was given to UUO model rats and rats with sham operation. At 7, 14, and 21 days, the tail cuff blood pressure (TCP), 24-h urine protein (Upro), serum Scr, BUN, K(+), percentage of renal damage and renal interstitial fibrosis (%INT) were measured in the rats. MCP1 protein in the renal tissues was detected using immunohistochemistry, and MCP1 and TGF-β(1) mRNA expressions were assayed using RT-PCR.

RESULTS

As the UUO prolonged, Upro, TCP, tubular damage, %INT, and MCP1 and TGF-β(1) mRNA expressions all increased significantly (P<0.05). High and very high doses of losartan, compared with the routine dose, obviously reversed these changes.

CONCLUSION

High-dose losartan can effectively control blood pressure, reduce renal damage and fibrosis, and inhibit MCP1 and TGF-β(1) expression in rats with UUO, and at a very high dose, losartan can more effectively reduce 24-h Upro than the high-dose group. High and very high doses of losartan offer better protective effect on the kidney in rats with UUO.

[Effects of bicyclol on renal PAI-1 expression in rats with uniliteral ureteral obstruction]

OBJECTIVE

To explore the protective effects of bicyclol against renal interstitial fibrosis and possible mechanisms of the protection.

METHODS

Eighty-one Sprague-Dawley (SD) rats were randomly assigned to a sham-operated group and UUO groups with and without bicyclol treatment. A rat model of renal interstitial fibrosis was prepared by unilateral ureteral obstruction (UUO). Renal tissues were examined by hematoxylin & eosin and Masson staining on 7, 14 and 21 days. Immunhistochemistry was used for determining plasminogen activator inhibitor-1(PAI-1) expression in the renal interstitium. PAI-1 mRNA expression in renal tissues was semi-quantitatively determined by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

The relative areas of renal interstitial fibrosis in the bicyclol-treated UUO group 7, 14 and 21 days after operation were (9.6 ± 0.6)%, (16.8 ± 0.8)% and (33.6 ± 1.6)% respectively, which were significantly lower than those in the untreated UUO group [13.0 ± 0.7)%, (25.8 ± 1.5)% and (53.2 ± 2.5)% respectively] (P<0.05). The levels of protein and mRNA expression of PAI-1 in the bicyclol-treated UUO group decreased significantly compared with those in the untreated UUO group 7, 14 and 21 days after operation (P<0.05).

CONCLUSIONS

Bicyclol can alleviate renal interstitial injury and renal interstitial fibrosis caused by UUO in rats, possibly through a downregulation of renal PAI-1 expression.

[Medical management of acute renal colic - there is more than hydration and Buscopan®...]

Renal colic is generated by hyperperistalsis of the obstructed ureter. Peristalsis is modulated by (among others) alpha-receptors (contraction), beta-receptors (relaxation) and prostaglandins (PG F2alpha: contraction, PG E1/E2: relaxation). Non-steroidal anti-inflammatory drugs (NSAID) are highly effective in pain relief and should always be given in the absence of contraindications. The same is true for metamizole, whereas Buscopan® is not superior to placebo. For most severe pain, opioids are indicated. alpha-blockers and calcium channel blockers dilate the distal ureter and increase the likelihood of spontaneous stone passage by up to 65%. Overhydration of patients has no advantage, but carries the risk of pelvic rupture with urine extravasation and infection. Stones of/above diameter 7 mm are unlikely to pass spontaneously and should be interventionally removed.

Omi/HtrA2 protease is associated with tubular cell apoptosis and fibrosis induced by unilateral ureteral obstruction

Kidney fibrosis, a typical characteristic of chronic renal disease, is associated with tubular epithelial cell apoptosis. The results of our recent studies have shown that Omi/HtrA2 (Omi), a proapoptotic mitochondrial serine protease, performs a crucial function in renal tubular epithelial apoptotic cell death in animal models of acute kidney injury, including cisplatin toxicity and ischemia-reperfusion insult. However, the role of Omi in tubulointerstitial disease-associated fibrosis in the kidney remains to be clearly defined. We evaluated the potential function and molecular mechanism of Omi in ureteral obstruction-induced kidney epithelial cell apoptosis and fibrosis. The mice were subjected to unilateral ureteral obstruction (UUO) via the ligation of the left ureter near the renal pelvis. UUO increased the protein level of Omi in the cytosolic fraction of the kidney, with a concomitant reduction in the mitochondrial fraction. UUO reduced the X-linked inhibitor of apoptosis protein (XIAP), a substrate of Omi, and pro-caspase-3, whereas it increased cleaved poly(ADP-ribose) polymerase (cleaved PARP) and the number of terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL)-positive cells. When mice were treated with ucf-101, an inhibitor of the proteolytic activity of Omi (6.19 microg/day ip), on a daily basis beginning 2 days before UUO and continuing until the end of the experiment, the Omi inhibitor protected XIAP cleavage after UUO and reduced the increment of PARP cleavage and the numbers of TUNEL-positive cells. Furthermore, the Omi inhibitor significantly attenuated UUO-induced increases in fibrotic characteristics in the kidney, including the atrophy and dilation of tubules, expansion of the interstitium, and increases in the expression of collagens, alpha-smooth muscle actin, and fibronectin. In conclusion, Omi/HtrA2 is associated with apoptotic signaling pathways in tubular epithelial cells activated by unilateral ureteral obstruction, thereby resulting in kidney fibrosis.

Renal colic in adults: NSAIDs and morphine are effective for pain relief

(1) Renal colic is an acute syndrome involving unilateral flank pain, linked to an obstruction in the upper urinary tract. The pain is often intense. After having considered other diagnoses and checked for signs of complication (fever, oligoanuria), the first step is to control the pain; (2) Which non-invasive treatments have a positive risk-benefit balance in relieving this type of pain? To answer this question, we reviewed the available evidence, based on the standard Prescrire methodology; (3) According to a meta-analysis of 20 trials, nonsteroidal antiinflammatory drugs (NSAIDs) and strong opioid analgesics have comparable efficacy. The most widely studied NSAID is diclofenac, given intramuscularly at a dose of 50 mg or 75 mg. Pethidine is the best-assessed strong opioid, given intramuscularly at a dose of 50 mg to 100 mg, which corresponds to about 5 mg to 10 mg of morphine. Morphine is given intravenously; subcutaneous administration is an alternative although it has not been evaluated in renal colic; (4) In clinical trials, NSAIDs were associated with fewer adverse effects than opioids, which cause vomiting in about 20% of patients (versus about 6% with an NSAID); (5) NSAIDs expose patients to a risk of functional renal impairment, especially in patients with heart failure, renal artery stenosis, dehydration, renal impairment or ongoing treatment with a nephrotoxic drug, and the very elderly. NSAIDs should never be used during pregnancy; (6) According to one trial in 130 patients, the analgesic effect of the morphine and NSAID combination was greater than either agent used alone, in about 10% of patients; (7) Paracetamol has not been evaluated in comparative trials of renal colic, even for moderate pain; (8) Scopolamine is the only antispasmodic to have been evaluated in a comparative trial. Adding scopolamine to morphine did not seem to provide additional efficacy; (9) Other drugs, which have not been adequately tested as of early 2009, have no documented benefit in the treatment of the pain associated with renal colic; tamsulosin, nifedipine, desmopressin; (10) Among the non-drug measures tested, local active warming, taking care to avoid burns, was effective against pain according to one trial; pain was reduced by at least 50% using a device delivering 42 degrees C to the abdomen or lower back; (11) In pregnant women, morphine carries a lower risk of adverse effects than NSAIDs; (12) In practice, the treatment of renal colic is mainly based on taking an NSAID, or morphine when the NSAID does not adequately control the pain or when it is better to avoid using NSAIDs.

[Dynamic observation of enalapril on the expression of TGF-beta1, CTGF, Smad7 and alpha-SMA in rats with unilateral ureteral obstruction]

OBJECTIVE

To dynamically observe the effect of enalapril on the expression of transforming growth factor beta1 (TGF-beta1), connective tissue growth factor (CTGF), alpha-smooth muscle actin (alpha-SMA), and Smad7 in the obstructed kidney after unilateral ureteral obstruction (UUO) in rats, and to investigate the effect of enalapril on transdifferentiation of renal tubular epithelial cells.

METHODS

The model rats were induced by ligating the left ureter. Male Sprague-Dawley (SD) rats were divided into a normal control (sham-surgery) group, a model group, and a treatment group (enalapril 10 mg/ (kg * d) by gastric gavage from 24 h before the obstruction day). Rats were sacrificed on day 3, 7, 14, 21 after UUO was initiated. Sections of the renal tissue were stained with hematoxylin and eosin stain, which were used for histological and morphometric studies of the pathological change of the obstructed kidney. Real-time PCR was performed to examine the expression of TGF-beta1 mRNA and CTGF mRNA, and Western blot was performed to examine the expression of Smad7, alpha-SMA, and CTGF in the obstructed kidney.

RESULTS

The score of renal interstitial lesion increased with the extension of obstruction. The expression of TGF-beta1 mRNA, CTGF mRNA, alpha-SMA and CTGF increased in the model group with the extension of obstruction; but Smad7 expression decreased. Compared with the UUO group,the degree of renal interstitial lesion and the expression of TGF-beta1 mRNA, CTGF mRNA, alpha-SMA and CTGF were decreased, but the expression of Smad7 increased in the treatment group. Enalapril could significantly decrease TGF-beta1 mRNA on day 3, 7, 14, 21 after UUO. Enalapril could significantly affect the expression of CTGF mRNA,alpha-SMA,CTGF and Smad7 on day 3, 7, 14 after UUO initiation.

CONCLUSION

Enalapril significantly alleviates renal interstitial fibrosis by suppressing the expression of TGF-beta1, CTGF and alpha-SMA, upregulating the expression of Smad7, and has better effect at early stage (within 14 days after the UUO).

A novel cell-permeable antioxidant peptide decreases renal tubular apoptosis and damage in unilateral ureteral obstruction

Unilateral ureteral obstruction (UUO) is characterized by decreases in renal function, increased interstitial fibrosis, tubular apoptosis, and cellular infiltration. It has been suggested that inhibition of tubular apoptosis may protect against renal damage in obstruction. We have recently developed a series of peptides which are concentrated in the inner mitochondrial membrane and prevent cell death. These peptides are also active in vivo, in myocardial infraction, ischemic brain injury, and amyotrophic lateral sclerosis models. We therefore used SS-31, a prototype of these peptides, and assessed its effects on renal damage and oxidative stress in a 14-day obstruction model. SS-31 (1 or 3 mg/kg) or saline was given 1 day before and throughout the 14 days of obstruction. Kidneys were harvested and assessed for apoptosis (terminal transferase-dUTP-nick-end labeling, caspase 3 expression), fibrosis (trichrome staining), macrophage infiltration, fibroblast expression (immunoperoxidase), and oxidative damage (8-OH deoxyguanosine and heme oxygenase-1 expression), cytokines, and signaling pathways (transforming growth factor-beta, CCR-1, p38-MAPK, NF-kappaB). SS-31 significantly attenuated the effects of obstruction on all aspects of renal damage which were examined, with both the 1 and 3 mg/kg doses showing efficacy. We noted increased oxidative stress in obstruction, which was also attenuated by SS-31 treatment. Signaling via NF-kappaB and p38 MAPK pathways were both affected by SS-31 treatment. This study provides a proof of concept that peptides which protect mitochondria in vitro can provide protection from renal damage in a UUO model. The mechanism by which protection is afforded requires further studies both in vitro and in vivo.

Comparison of the effects of captopril, tamoxifen and L-carnitine on renal structure and fibrosis after total unilateral ureteral obstruction in the rat

OBJECTIVE

To compare the effects of captopril, tamoxifen and L-carnitine on renal structure and the collagen content of the unilateral obstructed kidney in the rat using unbiased stereological methods.

MATERIAL AND METHODS

Rats (n=25) were assigned equally to one of five groups after ligation of the ureter: (i) normal controls (no hydronephrosis); (ii) positive controls (hydronephrotic rats without drug treatment); (iii) hydronephrotic rat with captopril treatment (CAP); (iv) hydronephrotic rats with L-carnitine treatment (L-CAR); and (v) hydronephrotic rats with tamoxifen treatment (TAM). Two weeks after unilateral ureteral obstruction the kidney was removed and histological sections were prepared. The kidney volume and the fractional volumes and absolute amounts of the cortex, medulla, tubules, renal corpuscles, vessels and fibrous tissue were determined using modern stereological techniques.

RESULTS

Kidney volume increased in the CAP group in comparison with the other groups. The absolute volume of the tubules was the same in the CAP group compared to the normal control group. However, in the other experimental groups, the amount of tubules decreased. The absolute volumes of the renal corpuscles and vessels did not show any significant differences between groups. The absolute volume of fibrous tissue showed significant increases in all groups in comparison with the normal controls. There were no differences in the absolute amounts of fibrous tissue between the positive control, CAP and L-CAR groups, but in the TAM group the collagen content was decreased.

CONCLUSIONS

Captopril preserved the amount of renal tubules and tamoxifen decreased fibrous tissue formation in unilateral obstructed kidneys but there were no differences in other hydronephrotic kidneys.

A combination of Chinese herbs, Astragalus membranaceus var. mongholicus and Angelica sinensis, enhanced nitric oxide production in obstructed rat kidney

BACKGROUND

The persistent renal hemodynamic maladjustment caused by imbalances between vasoactivators predisposes the kidney to tubulointerstitial injury and ultimate interstitial fibrosis. The decoction (A&A) of a combination of roots of two Chinese herbs, Astragalus membranaceus var. mongholicus and Angelica sinensis, has shown antifibrotic effects in rats with chronic kidney diseases and improvement of renal blood flow in rats with acute ischemic renal injury. In the present study, we investigated the effects and possible mechanisms of A&A on vasoactivators in the process of renal interstitial fibrosis.

METHODS

Male Wistar rats were randomly divided into sham, unilateral ureteral obstruction (UUO) and UAA (UUO plus A&A administration) groups. After oral administration of A&A (14 g/kg/d) for 3, 7 and 10 days, morphological changes were evaluated by HE, Masson and Sirius red staining technique. The levels of Ang-II, ET-1, and the activities of different nitric oxide synthases (NOSs) in renal homogenate were measured by radioimmunoassay. The nitrite concentration as nitric oxide (NO) production was measured using the Griess reagent. Western blot analysis and immunohistochemical staining were performed to determine the expressions of eNOS, nNOS, and iNOS in the kidney. The ability of scavenging reactive oxygen species (ROS) was evaluated by spectrophotometry.

RESULTS

Morphological analysis showed severe interstitial mononuclear cells infiltration, tubular atrophy, renal fibrosis and collagen expression in kidneys of UUO group, which reduced by A&A administration (p<0.05, UAA vs. UUO group). The levels of Ang-II and ET-I were increased in obstructed kidneys, but not significantly changed after A&A administration. NO production did not change in obstructed kidney at day 3 but increased in day 7 and day 10. Administering A&A progressively increased NO production by 2.2, 1.2, and 1.2 fold at days 3, 7 and 10, respectively. The activities of constitutive NOS and iNOS were comparable between UUO group and sham group. In contrast, the activity of constitutive NOS was much higher in UAA than that of UUO rats, which increased 78%, 68% and 78% at days 3, 7 and 10 respectively, although the protein expression of eNOS, nNOS and iNOS in renal tissue had no change in UAA rats. The activities of scavenging ROS in UUO group were not significantly different from the sham group at days 3 and 7, but increased at day 10 (24.1+/-15.0 vs. 10.1+/-0.8 U/min/mg protein, p<0.05). After A&A administration, the activities of scavenging ROS were significantly increased at days 3 and 7 (51.5+/-17.9 vs. 11.7+/-7.4 U/min/mg protein, p<0.05; and 16.1+/-5.6 vs. 7.7+/-1.4 U/min/mg protein, p<0.05) respectively, comparing with the UUO group.

CONCLUSION

The anti-fibrosis effects of A&A might be associated with enhancing NO production via eNOS activation and scavenging ROS, and in turn might improve ischemic microvasculature and attenuate interstitial fibrosis.

Sulfasalazine reduces inflammatory renal injury in unilateral ureteral obstruction

The purpose of this study was to test whether sulfasalazine has a protective action against interstitial inflammation and the development of renal fibrosis in obstructive nephropathy. Female rats were subjected to a sham (n = 10) or unilateral ureteral obstruction (UUO, n = 30). UUO was induced in rats by ligating the left ureter. Three days after operation, rats subjected to UUO were randomized to receive tretment with either sulfasalazine (100 mg/kg) or vehicle every day for the last 7 days of the experiment. At 10 days following UUO, the obstructed kidney exhibited tubulointerstitial injury and leukocyte infiltration (mainly monocytes) that were associated with high levels of reactive oxygen species, cytokines, transforming growth factor (TGF)-beta1, myeloperoxidase (MPO), and lipid peroxidation. Ten days after UUO, the obstructed kidney was also associated with increased nuclear factor kappa beta (NF-kappabeta) expression in saline-treated rats. Compared with sham-operated rats, UUO rat kidneys showed lower concentrations of antioxidant enzymes in the obstructed kidney tissue. All of these changes were significantly attenuated by treatment with sulfasalazine in the obstructed kidney. Sulfasalazine protected against the renal interstitial inflammation and tissue damage elicited by ureteral occlusion. Inhibition of the NF-kappabeta-dependent pathway and inflammatory response and oxidative stress inhibition is likely to be involved in the beneficial effects of sulfasalazine.

Cyclooxygenase-2 inhibitor ameliorates ureteric damage in rats with obstructed uropathy

To investigate the effect of cyclooxygenase-2 (COX-2) inhibitor on the tissue damage and fibrosis in obstructed ureters, 80 rats were studied. Celecoxib, a COX-2 inhibitor, was administered to 40 rats at the dose of 10 mg/kg per day 1 day before unilateral ligation of ureters and every day thereafter. The others, receiving unilateral ligation of ureters only, served as controls. Eight rats from each group were sacrificed for examination on days 7, 14, 21, 28 and 42 after ligation, respectively. The expressions of COX-2, prostaglandin E(2) (PGE(2)), transforming growth factor-beta(1) (TGFbeta(1)), alpha-smooth muscle actin (alpha-SMA), proliferation cell nuclear antigen (PCNA) and the apoptotic cells in the ureteric smooth muscle were examined. Hydroureter and fibrosis of the muscle layer became progressively aggravated during the period of obstruction in the ligated ureters of both groups. The severity of the hydroureter and fibrosis of muscle layer in the ligated ureters of the treated group was significantly milder than those of the control group. Expressions of COX-2 and PGE(2) were found in the smooth muscle layer of ligated ureters in the control group from day 14 after ureteric ligation, reached a peak on day 21, and then declined. Treatment with Celecoxib completely abolished the expression of COX-2 and PGE(2). The Celecoxib administration also decreased the expression of TGFbeta(1), alpha-SMA and the labeling index of apoptotic cells in the smooth muscle layer of ligated ureters in the treated group. In the contrast, treatment with Celecoxib significantly increased the expression of PCNA in the smooth muscle layer of ligated ureters in the treated group. We concluded that COX-2 inhibitor might ameliorate the damage of obstructed ureters, at least partly, via the inhibition of COX-2 and TGFbeta(1) expression.

[Retroperitoneal fibrosis]

Retroperitoneal fibrosis is a rare clinical entity characterised by the presence of patologic collagen tissue in a retroperitoneal space. The fibrous mass covers abdominal organs causing their disfunctions. RPF was described at the begining of XX century but its etiology is not clear yet. Usually it causes an ureter obstuction and hydronephrosis, that is why most commonly is diagnosed by urologists and nephrologists. However, retroperitoneal fibrosis can be multifacial disease. In some patients localisation of fibrosis is atypical and manifestationns can be varied. Gastrological symptoms like jaundice, bowel obstuction, ascites can occure. Besides, some early signs of RPF are nonspecific and can imitate alarming symptoms of neoplasma, e.g.: weight loss, anemia, malaise, anorexia, fever. This force us to initiate gastrological investigation. The awareness of this disease is important. The early diagnosis and treatment improves prognosis and alows to avoid heavy complications. In typical cases radiology is often enough for diagnosis. However, histological examination is needed in many cases, especialy when patological mass is located atypical. A treatment is made up of farmacology and surgery. The first one is based on steroids, immunossuppressant and tamoxifen. Surgery is needed to eliminate organs obstruction.

Effect of combination therapy with enalapril and the TGF-β antagonist 1D11 in unilateral ureteral obstruction

In unilateral ureteral obstruction (UUO), the kidney is characterized by increased fibrosis and apoptosis. Both transforming growth factor-β (TGF-β) and ANG II have been implicated, and ANG II may mediate its effects through TGF-β. Previous studies demonstrated amelioration of renal damage when either TGF-β or ANG II has been individually targeted. In this study, we sought to determine whether combining 1D11 (monoclonal antibody to TGF-β) and an ACE inhibitor, enalapril, would be more effective in UUO than either individual treatment, as has been shown in diabetic and glomerulonephritic models. Rats underwent UUO and were given either control monoclonal antibody, 1D11 or enalapril, or 1D11/enalapril combination, for 14 days. Kidneys were harvested and examined for fibrosis [trichrome; collagen (real-time PCR, Sircol assay) and fibroblast-specific protein expression (immunohistochemistry), apoptosis (TUNEL), macrophage infiltration (immunohistochemistry), and TGF-β expression (real-time PCR and tubular localization with immunohistochemistry)]. UUO was found to induce fibrosis, apoptosis, macrophage infiltration, and TGF-β expression in the obstructed kidney. Administration of either 1D11 or enalapril individually significantly decreased all these changes; when 1D11 and enalapril were combined, there was little additive effect, and the combination did not provide full protection against damage. The results demonstrate that, for the most part, combination therapy is not additive in UUO. This could be due to the continued presence of a physical obstruction or to biochemical differences between UUO and other renal disease models. Furthermore, it suggests that other targets may be amenable to pharmacological manipulation in UUO.

Complement C5 mediates experimental tubulointerstitial fibrosis

Renal fibrosis is the final common pathway of most progressive renal diseases. C5 was recently identified as a risk factor for liver fibrosis. This study investigated the role of C5 in the development of renal tubulointerstitial fibrosis by (1) induction of renal fibrosis in wild-type and C5(-/-) mice by unilateral ureteral ligation (UUO) and (2) investigation of the effects of a C5a receptor antagonist (C5aRA) in UUO. In C5(-/-) mice, when compared with wild-type controls, markers of renal fibrosis (Sirius Red, type I collagen, fibronectin, alpha-smooth muscle actin, vimentin, and infiltrating macrophages) were significantly reduced on day 5 of UUO. On day 10, fibronectin mRNA and protein expression were still reduced in the C5(-/-) mice. Cortical mRNA of all PDGF isoforms and of TGF-beta(1) (i.e., central mediators of renal disease) were significantly reduced in C5(-/-) mice when compared with controls. Renal tubular cell expression of the C5aR was sparse in normal cortex but markedly upregulated after UUO. Treatment of wild-type UUO mice with C5aRA also led to a significant reduction of cortical Sirius Red staining, fibronectin protein expression, and PDGF-B mRNA expression on day 5. Neither genetic C5 deficiency nor C5aRA treatment caused any histologic changes in the nonobstructed kidneys. In cultured murine cortical tubular cells, C5a stimulated production of TGF-beta(1), and this was inhibited by C5aRA. Using a combined genetic and pharmacologic approach, C5, in particular C5a, is identified as a novel profibrotic factor in renal disease and as a potential new therapeutic target.

Candesartan prevents long-term impairment of renal function in response to neonatal partial unilateral ureteral obstruction

Angiotensin II (ANG II) plays an important role in the development of obstructive nephropathy. Here, we examined the effects of the ANG II receptor type 1 (AT1R) blockade using candesartan on long-term renal molecular and functional changes in response to partial unilateral ureteral obstruction (PUUO). Newborn rats were subjected to severe PUUO or sham operation (Sham) within the first 48 h of life. Candesartan was provided in the drinking water (10 mg·kg−1·day−1) from day 21 of life until 10 wk of age. Renal blood flow (RBF) was evaluated by MRI, glomerular filtration rate (GFR) was measured using the renal clearance of51Cr-EDTA, and the renal expression of Na-K-ATPase and the collecting duct water channel aquaporin-2 (AQP2) was examined by immunoblotting and immunocytochemistry. At 10 wk of age, PUUO significantly reduced RBF (0.8 ± 0.1 vs. 1.6 ± 0.1 ml·min−1·100 g body wt−1; P < 0.05) and GFR (37 ± 16 vs. 448 ± 111 μl·min−1·100 g body wt−1; P < 0.05) compared with Sham. Candesartan prevented the RBF reduction (PUUO+CAN: 1.6 ± 0.2 vs. PUUO: 0.8 ± 0.1 ml·min−1·100 g body wt−1; P < 0.05) and attenuated the GFR reduction (PUUO+CAN: 265 ± 68 vs. PUUO: 37 ± 16 μl·min−1·100 g body wt−1; P < 0.05). PUUO was also associated with a significant downregulation in the expression of Na-K-ATPase (75 ± 12 vs. 100 ± 5%, P < 0.05) and AQP2 (52 ± 15 vs. 100 ± 4%, P < 0.05), which were also prevented by candesartan (Na-K-ATPase: 103 ± 8 vs. 100 ± 5% and AQP2: 74 ± 13 vs. 100 ± 4%). These findings were confirmed by immunocytochemistry. Consistent with this, candesartan treatment partly prevented the reduction in solute free water reabsorption and attenuated fractional sodium excretion in rats with PUUO. In conclusion, candesartan prevents or attenuates the reduction in RBF, GFR and dysregulation of AQP2 and Na-K-ATPase in response to congenital PUUO in rats, suggesting that AT1R blockade may protect the neonatally obstructed kidney against development of obstructive nephropathy.

Atorvastatin Preserves Renal Function in Chronic Complete Unilateral Ureteral Obstruction

PURPOSE

The pleiotropic effects of hMG-CoA (3-hydroxy-3-metylglutaryl coenzyme A) reductase inhibitors may provide renal protection in chronic kidney disease. We examined whether atorvastatin administration preserved renal function in rats with chronic unilateral ureteral obstruction.

MATERIALS AND METHODS

Renal clearance experiments were performed in sham operated rats and rats subjected to 3 or 12-day unilateral ureteral obstruction. Hemodynamics parameters and urinary microalbumin levels from the obstructed kidney were also measured. The rats were maintained on a regular diet or the same diet but supplemented with atorvastatin (50 mg/kg daily).

RESULTS

Atorvastatin administration did not alter plasma total cholesterol but it significantly decreased triglyceride levels. In sham operated and 3-day unilateral ureteral obstruction rats atorvastatin treatment did not have effects on the glomerular filtration rate or effective renal plasma flow and it also did not affect urinary microalbumin levels. In rats with 12-day unilateral ureteral obstruction the glomerular filtration rate but not effective renal plasma flow was significantly higher and urinary microalbumin was significantly lower in atorvastatin treated rats than in those without atorvastatin treatment.

CONCLUSIONS

Atorvastatin treatment decreased microalbuminuria and helped preserve filtration function in chronic unilateral ureteral obstruction without altering plasma cholesterol levels, suggesting that pleiotropic renal protection is offered by this statin.

Angiotensin II mediates downregulation of aquaporin water channels and key renal sodium transporters in response to urinary tract obstruction

The renin-angiotensin system is well known to be involved in the pathophysiological changes in renal function after obstruction of the ureter. Previously, we demonstrated that bilateral ureteral obstruction (BUO) is associated with dramatic changes in the expression of both renal sodium transporters and aquaporin water channels (AQPs). We now examined the effects of the AT1-receptor antagonist candesartan on the dysregulation of AQPs and key renal sodium transporters in rats subjected to 24-h BUO and followed 2 days after release of BUO (BUO-2R). Consistent with previous observations, BUO-2R resulted in a significantly decreased expression of AQP1, -2, and -3 compared with control rats. Concomitantly, the rats developed polyuria and reduced urine osmolality. Moreover, expression of the type 2 Na-phosphate cotransporter (NaPi-2) and type 1 bumetanide-sensitive Na-K-2Cl cotransporter (NKCC2) was markedly reduced, consistent with postobstructive natriuresis. Candesartan treatment from the onset of obstruction attenuated the reduction in GFR (3.1 ± 0.4 vs. 1.7 ± 0.3 ml·min−1·kg−1) and partially prevented the reduction in the expression of AQP2 (66 ± 21 vs. 13 ± 2%, n = 7; P < 0.05), NaPi-2 (84 ± 6 vs. 57 ± 10%, n = 7; P < 0.05), and NKCC2 (89 ± 12 vs. 46% ± 11, n = 7; P < 0.05). Consistent with this, candesartan treatment attenuated the increase in urine output (58 ± 4 vs. 97 ± 5 μl·min−1·kg−1, n = 7; P < 0.01) and the reduction in sodium reabsorption (433 ± 62 vs. 233 ± 45 μmol·min−1·kg−1, n = 7; P < 0.05) normally found in rats subjected to BUO. Moreover, candesartan treatment attenuated induction of cyclooxygenase 2 (COX-2) expression in the inner medulla, suggesting that COX-2 induction in response to obstruction is regulated by ANG II. In conclusion, candesartan prevents dysregulation of AQP2, sodium transporters, and development of polyuria seen in BUO. This strongly supports the view that candesartan protects kidney function in response to urinary tract obstruction.

COMP–Angiopoietin-1 Ameliorates Renal Fibrosis in a Unilateral Ureteral Obstruction Model

Injury to the renal microvasculature may be a major factor in the progression of renal disease; therefore, protection of endothelial cells (EC) in renal vasculature may have a therapeutic role in renal fibrosis. Recently, a soluble, stable, and potent angiopoietin-1 (Ang1) variant, cartilage oligomeric matrix protein (COMP)-Ang1, was developed. The contribution of COMP-Ang1 in renal interstitial fibrosis, however, remains to be clarified. This study investigated the effects of COMP-Ang1 on peritubular capillary EC in the renal cortex and the renal fibrogenic process that is triggered by unilateral ureteral obstruction. COMP-Ang1 preserved renal platelet-EC adhesion molecule-1-and Tie2-positive EC. Morphologic examination indicated less tubular injury and tubulointerstitial fibrosis in mice that received COMP-Ang1 than vehicle-treated mice. Interstitial type I collagen and myofibroblast accumulation were significantly suppressed by COMP-Ang1 treatment. COMP-Ang1 increased Tie2 and Akt phosphorylation in ureteral obstructed kidneys. Renal surface microvasculature and renal blood flow were higher after treatment with COMP-Ang1 than with vehicle. COMP-Ang1 treatment decreased monocyte/macrophage infiltration, tissue levels of TGF-beta1, and Smad 2/3 phosphorylation and increased Smad 7 in the obstructed kidney. These results demonstrate that COMP-Ang1 treatment can decrease the progression of renal fibrosis in unilateral ureteral obstruction. COMP-Ang1 may be an endothelium-specific therapeutic modality in fibrotic renal disease.

Idiopathic retroperitoneal fibrosis: the case for nonsurgical treatment

OBJECTIVE

To review a 10-year experience of medical treatment for idiopathic retroperitoneal fibrosis (RPF), a rare condition of unknown causes, which may obstruct the ureter and for which treatment includes ureterolysis and relief of obstruction, and medical treatment with steroids with or without immunosuppressive medication.

PATIENTS AND METHODS

Of 31 patients with RPF treated between 1996 and 2004, 28 had idiopathic disease. Ureteric stents were used to relieve the obstruction in all patients, 12 had previous nephrostomies, 16 were given steroids and only one was treated with ureterolysis.

RESULTS

In all, 28 patients were followed for a mean of 51.17 months; the symptoms were relieved in all cases. Renal function, where impaired, improved dramatically in all patients. Fifteen patients (54%) are free of stents and medication after a mean (range) follow-up of 60.9 (24-110) months.

CONCLUSION

Idiopathic RPF responds well to conservative management consisting of relief of urinary tract obstruction and steroids.

Effects of low molecular weight heparin in obstructed kidneys: decrease of collagen, fibronectin and TGF-β, and increase of chondroitin/dermatan sulfate proteoglycans and macrophage infiltration

BACKGROUND

Heparin exerts beneficial effects in different experimental models of nephropathy, as observed by the preservation of the structural morphology of the kidney after heparin therapy. Here we investigate molecular and cellular events involved in the protective effects of heparin in the progression of renal disease after unilateral ureteral obstruction.

METHODS

Thirty-six rats were divided into six groups: group C (control) was not subjected to any surgical manipulation; group S (sham) was subjected to surgical manipulation but without ureteral ligation; group UUO was subjected to ureteral obstruction and received no treatment; group UUO + S was subjected to ureteral obstruction and received saline subcutaneously (s.c.) once daily; group UUO + H was subjected to ureteral obstruction and received low molecular weight heparin (LMW-Hep; 4 mg/kg) s.c. once daily; and group C + H was not subjected to any surgical manipulation and received LMW-Hep (4 mg/kg) s.c. once daily. After 14 days, the content of collagen, fibronectin, total glycosaminoglycans (GAGS), chondroitin sulfate/dermatan sulfate proteoglycans (CS/DSPGs), transforming growth factor-beta (TGF-beta) and cellular infiltration were determined in the kidneys by immunohistochemical and biochemical techniques.

RESULTS

Collagen, fibronectin, total GAGS, CS/DSPGs, TGF-beta and cellular infiltration increased significantly in group UUO. LMW-Hep treatment reduced collagen, fibronectin and TGF-beta, but induced an increase in the content of total GAGS, CS/DSPGs and macrophage infiltration in group UUO + H when compared with group UUO.

CONCLUSIONS

LMW-Hep diminishes fibrosis in obstructed kidneys by downregulating the synthesis of collagen, fibronectin and TGF-beta. The mechanisms underlying the overproduction of CS/DSPGs and the increase in cellular infiltration upon LMW-Hep administration remain to be elucidated.