Long-term protective effect of UR-12670 after warm renal ischemia in uninephrectomized rats

BACKGROUND: The phospholipid platelet-activating factor (PAF) participates in the pathogenesis of renal ischemia/reperfusion injury, and in vitro, it induces synthesis of extracellular matrix proteins by mesangial and tubular epithelial cells. This study investigated the long-term effects of the potent orally active PAF antagonist UR-12670 in warm ischemic uninephrectomized rats, which was given according to different therapeutic schedules. METHODS: Uninephrectomized male Sprague-Dawley rats were divided into five groups and were followed for 52 weeks: rats without ischemia (SK); ischemic kidney for 60 minutes (SIK); ischemic kidney and UR-12670 from 0 to the 7th day (UR 0-7); ischemic kidney and UR-12670 from day 0 to 52 weeks (UR 0-E); and ischemic kidney and UR-12670 from day 8 to week 52 (UR 8-E). Two more groups (ischemic and UR treated) served to evaluate the UR-12670-protective effect on ischemic acute renal failure at one week. RESULTS: UR-12670 administration exerted functional and morphological protection against post-ischemic acute renal failure. The ischemic untreated (SIK) group developed progressive proteinuria from week 12. The onset of proteinuria in ischemic UR-12670-treated groups was delayed to the 24th week, and it was significantly lower than in SIK group throughout the study. Only SIK and ischemic-treated UR 0-7 rats presented with chronic renal failure, as shown by creatinine, creatinine clearance, glomerular filtration rate (GFR), and renal plasma flow (GFR 52 weeks: SK, 2525 +/- 267; SIK, 992 +/- 149; UR 0-7, 1551 +/- 385 microliter/min). Kidneys from the short-term treated group (UR 0-7) showed a reduction of glomerulosclerosis (SK, 14.4 +/- 3.7; SIK, 75.7 +/- 7.7; UR 0-7, 41. 5 +/- 8.5%) and vascular myointimal hyperplasia, but the tubulointerstitial damage (tubulointerstitial score: SK, 0.2 +/- 0. 2; SIK, 4.4 +/- 0.5; UR 0-7, 3.7 +/- 0.7) was similar to that in the ischemic untreated group. Long-term ischemic treated rats (UR 0-E, UR 8-E) did not develop chronic renal failure (GFR: UR 0-E, 2059 +/- 314; UR 8-E, 2410 +/- 208 microliter/min). In these groups, glomerulosclerosis (UR 0-E, 32.8 +/- 5.8; UR 8-E, 24.3 +/- 3.0%), tubulointerstitial damage (tubulointerstitial score: UR 0-E, 2.1 +/- 0.5; UR 8-E, 1.9 +/- 0.3) and vascular myointimal hyperplasia were significantly lower than in the ischemic untreated group. By in situ hybridization, an increase of transforming growth factor-beta1 mRNA expression in glomerular and tubular cells was observed in ischemic untreated and ischemic treated UR 0-7 rats. UR-12670 long-term treated rats showed a clear reduction of transforming growth factor-beta1 mRNA-positive glomerular cells. CONCLUSION: The chronic administration of the PAF antagonist UR-12670 attenuates the long-term effects of ischemia-reperfusion injury in uninephrectomized rats. The beneficial effect of this agent, even when given beyond the initial ischemia/reperfusion injury, suggests that PAF plays a role in the mechanisms of progression to late renal damage in this model.     

Cold ischemia in the absence of alloreactivity induces chronic transplant nephropathy through a process mediated by the platelet-activating factor

BACKGROUND: Ischemia-reperfusion injury is considered a risk factor for the development of chronic transplant nephropathy (CTN) although the mechanisms that mediate its effects have not been completely established. We have previously shown that treatment with a platelet-activating factor (PAF) receptor antagonist (UR12670) protected kidneys from the progression to chronic nephropathy induced by warm ischemia. Here we examine the contribution of cold ischemia to the development of late functional and structural kidney changes in rats subjected to syngeneic renal transplantation and the role of PAF in this chronic nephropathy. SUBJECTS AND METHODS: Lewis rats were used as kidney donors and recipients, which were transplanted either immediately or after a cold ischemia period of 5 hr. Contralateral nephrectomy was performed on the seventh day after transplantation. Cyclosporine was administered for 15 days after transplantation. Groups were as follows: Sy, immediate transplantation; SyI, transplantation after 5 hr of cold ischemia; SyIUr, transplantation after 5 hr of cold ischemia plus UR12670 from the transplantation day to the end of the study, at 24 weeks. Serum creatinine, creatinine clearance, and proteinuria were determined every 4 weeks. Urinary     

Prevention of cold ischaemia-reperfusion injury by an endothelin receptor antagonist in experimental renal transplantation.

BACKGROUND: Endothelin (ET) is known to play a role in the pathogenesis of warm ischaemic renal damage, however, little is known about its involvement in renal cold ischaemia. This study was designed to investigate the response of ET after kidney cold ischaemia, and to assess the potential protective effect of bosentan, a dual, non-selective ET(A)/ET(B) receptor antagonist, against cold ischaemia reperfusion injury in a rat model of syngeneic renal transplantation. METHODS: Kidneys from Lewis rats were transplanted, either immediately or after 5 h of cold preservation. After 48 h, contralateral nephrectomy was performed. Rats were organized into three groups: Tr-NoISC, no cold ischaemia; Tr-ISC, 5 h cold ischaemia; and Tr-BOS, 5 h cold ischaemia plus bosentan (100 mg/kg/day, from the day before transplantation until the seventh day post-transplantation). On day 7, plasma and tissue immunoreactive ET (irET), as well as ET mRNA tissue expression, were evaluated. Renal function was measured by means of serum creatinine on days 3, 4, 5 and 7, and by creatinine clearance on day 7. Conventional histology was performed. RESULTS: The ischaemic group had significantly higher plasma irET levels than the non-ischaemic group and significantly lower levels than the bosentan group. Tissue irET levels and ET mRNA expression were similar in the ischaemic and bosentan groups and were higher than in the non-ischaemic group. Throughout the follow-up, serum creatinine was significantly higher in the ischaemic group than in the bosentan group. Moreover, creatinine decreased rapidly in the bosentan group after nephrectomy, whereas it continued to increase for 48 h in the ischaemic group. Kidneys from the ischaemic group showed a higher degree of tubular-cell necrosis and epithelial-cell detachment than kidneys from the bosentan group. CONCLUSIONS: We conclude that cold ischaemia and preservation damage induces an increase in renal ET mRNA and irET expression in the reperfusion phase, contributing both to the deterioration of renal function and to tubular necrosis. Bosentan is effective in protecting kidneys from this cold ischaemia reperfusion damage. Non-selective ET(A)/ET(B) receptor antagonists might be potentially useful in clinical renal transplantation.     

Antibody-induced modulation of the leukocyte CD11b integrin prevents mild but not major renal ischaemic injury.

BACKGROUND: CD11/CD18 beta(2) integrins are involved in leukocyte adhesion to the activated endothelium, and therefore represent a possible therapeutic target in the prevention of ischaemic acute renal failure (ARF). METHODS: To assess the effect of an anti-CD11b monoclonal antibody (mAb) in ischaemic ARF, uninephrectomized Fischer rats were subjected to 45 or 60 min of warm renal ischaemia, then received 1 mg of anti-CD11b mAb 5 min before reperfusion. RESULTS: After 45 min of ischaemia, renal function tests at 24 and 48 h were less altered in mAb-treated than in control rats, but after 60 min of ischaemia the same level of renal insufficiency was observed in the two groups. In parallel, milder tubular necrosis and less leukocyte infiltration were observed in the treated group after 45 min of ischaemia, but no difference was seen after 60 min compared to the control group. The mAb was detected on blood neutrophils up to 48 h after infusion and a marked down-regulation of CD11b expression on neutrophil surfaces was documented by flow cytometry. CONCLUSION: These results indicate that anti-CD11b mAb administered prior to reperfusion decreases moderate ischaemic ARF but fails to prevent renal injury secondary to prolonged ischaemia in this model.     

Failure of verapamil to protect from ischaemic renal damage

To reassess the reported protective effects of verapamil in renal ischaemia, we perfused the left kidney of uninephrectomized female Wistar rats with verapamil (0.1 and 1.0 mg/kg) immediately prior to clamping the renal artery for 60 min. When compared to controls, both doses of verapamil failed to afford protection with respect to urine flow, plasma creatinine, creatinine clearance or histology 24 and 48 h after ischaemia, whereas the purine nucleotide inosine (200 mg/kg) was partially protective: mean plasma creatinine 48 h after ischaemia (+/- SEM) was 547 +/- 54 mumol/l in controls, 686 +/- 38 mumol/l with 0.1 mg/kg verapamil, 491 +/- 68 mumol/l with 1.0 mg/kg verapamil and 374 +/- 45 mumol/l with inosine (p less than 0.05 vs. controls). Using the same model, the effect of verapamil 1.0 mg/kg on renal blood flow, creatinine clearance, urine flow and arterial pressure was studied in the first 2 h after ischaemia. Although significant amounts of verapamil were present in the kidney during ischaemia as evidenced by decreases in systemic blood pressure and in renal vascular resistance after unclamping the renal artery, the early course of renal failure was not altered when compared to controls. In conclusion, we have been unable to confirm earlier reports of a protective effect of verapamil in this rat model of ischaemic renal failure. If there is such an effect, its demonstration appears to depend on very specific experimental circumstances. Based on the results of this and other studies, verapamil is unlikely to afford an impressive overall benefit in the clinical setting of ischaemic renal failure.     

The prediction of renal function 6 years after unilateral nephrectomy using preoperative risk factors

PURPOSE: Since middle-aged and elderly patients seem to have risk factors affecting renal function, it is important to predict postoperative renal function prior to unilateral nephrectomy (UNx). We evaluated preoperative factors for predicting postoperative renal function in middle-aged and elderly patients with renal cell carcinoma (RCC) treated with radical nephrectomy (RNx). MATERIALS AND METHODS: In 201 patients who underwent RNx preoperative records and postoperative serum creatinine (SCR) 6 years after nephrectomy were available. Postoperative renal insufficiency was defined as serum creatinine 1.4 mg/dl or greater. The relationship of each preoperative and postoperative factor was analyzed. Logistic regression analysis was performed to evaluate preoperative factors for predicting postoperative SCR 1.4 mg/dl or greater after 6 years. RESULTS: There was a significant difference in postoperative SCR between female and male patients, and between those with and without hypertension, diabetes and proteinuria (p <0.05). Age, hemoglobin, preoperative SCR, blood urea nitrogen, uric acid and K significantly correlated with postoperative SCR (p <0.05). The increase in SCR during 6 years after UNx was significantly higher in patients with hypertension, diabetes and proteinuria than in their respective counterparts (p <0.05). Multivariate stepwise logistic regression analysis demonstrated that preoperative serum creatinine, hypertension and proteinuria were significant independent factors predicting postoperative renal function 6 years after UNx in patients with RCC (p <0.05). CONCLUSIONS: Preoperative SCR, hypertension and proteinuria are useful factors for predicting postoperative renal function after RNx in patients with RCC.     

Effect of sevoflurane preconditioning on ischaemia/reperfusion injury in the rat kidney in vivo

BACKGROUND AND OBJECTIVE: Whereas the protective effect of anaesthetic and ischaemic preconditioning has been described for several organs, it is uncertain whether this mechanism is also effective in the kidney. We compared the effect of preconditioning with sevoflurane and preconditioning with short episodes of ischaemia on renal ischaemia/reperfusion injury in the rat in vivo. METHODS: Fourteen days after right-sided nephrectomy, anaesthetized male Wistar rats were randomly assigned to a sham-operated group (no arterial occlusion, n = 5) or underwent 45 min of left renal artery occlusion (control group, n = 9) followed by 3 days of reperfusion. Two further experimental groups of animals were preconditioned prior to ischaemia either by administering 1 MAC sevoflurane for 15 min followed by 10 min of washout (sevoflurane group, n = 10) or by subjecting the animals to three short episodes of renal ischaemia (ischaemia-preconditioned group, n = 8). Blood creatinine was measured during reperfusion and morphological damage was assessed by histological examination. RESULTS: Baseline creatinine values were similar in all four groups (0.7 +/- 0.2 mg dL-1; mean +/- SD) and remained unchanged in the sham-operated animals after 3 days (0.8 +/- 0.2 mg dL-1). Creatinine levels increased in the ischaemic preconditioning group (3.3 +/- 1.2 mg dL-1) and sevoflurane preconditioning group (4.0 +/- 1.1 mg dL-1) compared to the control group (1.6 +/- 0.6 mg dL-1). Morphological damage was less severe in the control group, i.e. in animals without preconditioning, than in both preconditioning groups. CONCLUSION: Neither sevoflurane nor ischaemic preconditioning preserves renal function or attenuates cell damage in the rat in vivo.     

Acute Ureteral Obstruction and Glomerulotubular Function in Rats

Urinary tract obstruction is a common cause of acute renal failure (ARF). During unilateral ureteral obstruction (UUO) arteriolar vasoconstriction, increase in tubular pressure, and ultrafiltrate retrodiffusion occur. We studied renal function of rats with surgical UUO for 24 hr. After this period of UUO, the contralateral kidney was removed and the right ureter was deobstructed. The control uninephrectomized group consisted of normal rats submitted to left uninephrectomy (UNx). Functional studies were performed 12 and 24 hr, and 7 days after deobstruction and UNx. We measured creatinine clearance, and fractional excretion of sodium and lithium. Using conventional formulas we calculated fractional proximal and distal sodium reabsorption. Initially we observed a reduction in glomerular filtration rate (GFR) after deobstruction (12 and 24 hr). However, after 7 days, the GFR was significantly higher in deobstructed rats than in controls (340.3 ± 18.3 vs. 286.4 ± 9.3 μL/min/100 g, p < 0.01). The dry kidney weight was also increased in these rats. The fractional sodium excretion was increased in deobstructed rats, mainly in early studies (12 and 24 hr). Whereas fractional proximal reabsorption was reduced in both groups, the fractional distal reabsorption was significantly decreased in the deobstructed group compared to UNX controls (93.9 ± 0.9 vs. 98.9 ± 0.1% after 24 hr, p < 0.01). Our data showed that UUO influenced both glomerular and tubular functions. A salient finding was the overcorrection of GFR 7 days after deobstruction. The renal release of hormones and growth factors could mediate these alterations in renal function through their vascular, tubular, and proliferative actions.     

Intrarenal renin-angiotensin system contributes to tubular acidification adaptation following uninephrectomy

BACKGROUND/AIMS: Reduction in renal mass by uninephrectomy induces a functional compensation in the remnant kidney. The activity of the angiotensin-converting enzyme (ACE) as well as renin mRNA in the proximal convoluted tubule (PCT) of uninephrectomized (UNx) rats increases. The aim of this work was to determine whether the increased activity of the local renin-angiotensin system (RAS) participates in the adaptation of renal function after uninephrectomy. METHOD: We utilized normal two-kidney (2K) and 3-week UNx rats to study the activity of the ACE in vesicles obtained from luminal membranes of proximal tubular cells and the acidification kinectics in PCTs using micropuncture techniques. RESULTS: The converting enzyme activity was significantly larger in UNx (5.87+/-0.69 nmol x min(-1) x mg protein(-1)) than in 2K rats (2.43+/-0.13 nmol x min(-1) x mg protein(-1); p<0.05). The acidification rate constant (kappa) in PCT of 2K rats was 0.18+/-0.02 s(-1) and in UNx rats 0.30+/-0.04 s(-1) (p<0.001). In UNx rats, microperfusion with 10(-5) M ramipril or 10(-5) M losartan decreased kappa to 0.19+/-0.02 and 0.18+/-0.02 s(-1), respectively, but had no effect on 2K rats. Luminal steady-state pH (pH(infinity)) was the same in 2K and UNx rats, and was not modified by addition of 10(-5) M ramipril or 10(-5) M losartan in both groups. The proximal H(+) flux (J(H(+))), calculated from pH(infinity) and kappa, was 1.12 nmol x cm(-2) x s(-1) in 2K rats and, 1.77 nmol. cm(-2). s(-1) in UNx rats (p<0.001). In 2K rats, this value was not changed by 10(-5) M ramipril or 10(-5) M losartan, but in UNx rats J(H(+)) decreased 25 and 30% with ramipril or losartan, respectively (p<0.001). CONCLUSIONS: These data suggest that the increase in the local RAS activity could be an adaptive change that contributes to maintain the homeostasis of body fluids after uninephrectomy.     

The impact of warm ischaemia on renal function after laparoscopic partial nephrectomy

Authors from Cleveland assessed the impact of warm ischaemia on renal function, using their large database of laparoscopic partial nephrectomies for tumour. While agreeing that renal hilar clamping is essential for precise excision of the tumour, and other elements of the operation, the authors indicate that warm ischaemia may potentially damage the kidney. However, they found that there were virtually no clinical sequelae from warm ischaemic of up to 30 min. They also found that advancing age and pre-existing renal damage increased the risk of postoperative renal damage. OBJECTIVE: To assess the effect of warm ischaemia on renal function after laparoscopic partial nephrectomy (LPN) for tumour, and to evaluate the influence of various risk factors on renal function. PATIENTS AND METHODS: Data were analysed from 179 patients undergoing LPN for renal tumour under warm ischaemic conditions, with clamping of the renal artery and vein. Renal function was primarily evaluated in two groups of patients: 15 with tumour in a solitary kidney, who were evaluated by serial serum creatinine measurements; and 12 with two functioning kidneys undergoing unilateral LPN, and evaluated by renal scintigraphy before and 1 month after LPN to quantify differential renal function. Also, in all 179 patients, mean serum creatinine data at baseline, 1 day after LPN, at hospital discharge, and at the last follow-up were provided as supportive evidence. Logistic regression analyses were used to assess the effect of various risk factors on renal function after LPN, i.e. patient age, baseline serum creatinine, tumour size, solitary kidney status, duration of warm ischaemia, pelvicalyceal suture repair, urine output and intravenous fluids during LPN. RESULTS: In the group of patients with a solitary kidney the mean warm ischaemia time was 29 min, kidney parenchyma excised 29%, and serum creatinine at baseline, discharge, the peak after LPN and at the last follow-up (mean 4.8 months) 1.3, 2.3, 2.8, and 1.8 mg/dL, respectively. One patient (6.6%) required temporary dialysis. In the second group, assessed by renal scintigraphy, the function of the operated kidney was reduced by a mean of 29%, commensurate with the amount of parenchyma excised. For all 179 patients, a combination of age > or = 70 years and a serum creatinine level after LPN of > or = 1.5 mg/dL correlated with a higher serum creatinine after LPN. On logistic regression, baseline serum creatinine and solitary kidney status were the only variables significant for serum creatinine status after LPN. CONCLUSIONS: The bloodless field provided by renal hilar clamping is important for precise tumour excision, pelvicalyceal suture repair and securing parenchymal haemostasis during LPN. However, renal hilar clamping causes warm ischaemia. These data indicate that the clinical sequelae of warm ischaemic renal injury of approximately 30 min are minimal. Advancing age and pre-existing azotaemia increase the risk of renal dysfunction after LPN, especially when the warm ischaemia exceeds 30 min.     

Dietary tryptophan supplementation prevents proteinuria in the seven-eighths nephrectomized rat

Surgical reduction of renal mass in the rat leads to proteinuria, hypertension, and progressive renal failure beyond that of the original physical destruction of renal mass. Both hypertension and proteinuria have been implicated in the process of progression of renal failure. The seven/eighths nephrectomized rats fed a diet supplemented with 4% tryptophan (UT) had a urinary albumin excretion rate of 0.055 +/- 0.056 mg/100 g body weight/hr compared to 0.02 +/- 0.029 mg/100 g body weight/hr in control rats, whereas the nephrectomized rats fed a regular diet (UR) excreted 1.12 +/- 0.730 mg/100 g body weight/hr (P less than 0.001). Hypertension was also prevented in the UT group but not in the UR group. Once hypertension and proteinuria were established during maintenance on a regular diet, they were not reversed by subsequent dietary tryptophan supplementation. If dietary tryptophan supplementation is continued, however, the progressive histopathology that develops after seven-eighths nephrectomy is not prevented despite avoidance of proteinuria and hypertension.     

IL-10 suppresses chemokines, inflammation, and fibrosis in a model of chronic renal disease

IL-10 is a pluripotent cytokine that plays a pivotal role in the regulation of immune and inflammatory responses. Whereas short-term administration of IL-10 has shown benefit in acute glomerulonephritis, no studies have addressed the potential benefits of IL-10 in chronic renal disease. Chronically elevated blood levels of IL-10 in rats were achieved by administration of a recombinant adeno-associated virus serotype 1 IL-10 (rAAV1-IL-10) vector. Control rats were given a similar dose of rAAV1-GFP. Four weeks after injection, IL-10 levels in serum were measured by ELISA, and chronic renal disease was induced by a 5/6 nephrectomy (n = 6 in each group). Eight weeks later, rats were killed and renal tissue was obtained for RNA, protein, and immunohistochemical analysis. Serum levels of IL-10 were 12-fold greater in the rAAV1-IL-10 group by 4 wk after rAAV1-IL-10 administration (345 +/- 169 versus 28 +/- 15 pg/ml; P = 0.001), and levels were maintained throughout the experiment. rAAV1-IL-10 treatment resulted in less proteinuria (P < 0.05), lower serum creatinine (P < 0.05), and higher creatinine clearances (P < 0.01) compared with rAAV1-GFP-treated rats. Renal interstitial infiltration was significantly attenuated by rAAV1-IL-10 administration as assessed by numbers of CD4+, CD8+, monocyte-macrophages (ED-1+) and dendritic (OX-62+) cells (P < 0.05), and this correlated with reductions in the renal expression of monocyte (renal monocyte chemoattractant protein-1 mRNA and protein) and T cell (RANTES mRNA) chemokines. rAAV1-IL-10 administration decreased mRNA levels of IFN-gamma and IL-2 in the kidney. The reduction in inflammatory cells was associated with a significant reduction in glomerulosclerosis and interstitial fibrosis. It is concluded that IL-10 blocks inflammation and improves renal function in this model of chronic renal disease. The feasibility of long-term overexpression of a gene using the AAV serotype 1 vector system in a model of renal disease is also demonstrated.     

Impact of renal transplantation on small vessel reactivity

BACKGROUND: The function of large arteries is altered after renal transplantation. Whether transplantation also induces agonist-dependent functional changes in small arterial renal and extrarenal vessels has not yet been studied. METHODS: Chronic rejection was induced by grafting Lewis rats with kidneys from Fischer rats (FL). Rats that underwent transplantation were bilaterally nephrectomized. Rats that underwent syngeneic transplantation, uninephrectomized rats, uninephrectomized rats with denervated kidneys or with kidneys made ischemic, and native rats served as controls. All animals were treated with cyclosporine for 10 days. Eighteen weeks after surgery, the reactivity of small arteries (220-270 microm) was tested by myography. RESULTS: Weight gain, glomerular filtration rate, and arterial pressure were similar in all groups, whereas proteinuria was elevated in FL. Only kidneys from FL showed glomerular lesions, tubular atrophy, and vasculopathy. Responsiveness of coronary, mesenteric, and femoral resistance vessels to both constrictor and dilator agonists was similar in transplanted and nontransplanted animals. Resistance vessels obtained from both allogeneically and syngeneically transplanted kidneys were more sensitive to norepinephrine, phenylephrine, angiotensin II, and vasopressin than renal vessels from weight-matched controls. Vasodilation in response to acetylcholine and sodium nitroprusside was mitigated in transplanted versus nontransplanted kidneys. CONCLUSIONS: In rat renal transplantation, renal resistance vessel responsiveness to constrictor or dilator stimuli is altered. Extrarenal small vessel function is not affected. The changes in function of renal resistance vessels are not explained by reduction of nephron mass, denervation, ischemia, or chronic rejection.     

Macrophages contribute to the development of renal fibrosis following ischaemia/reperfusion-induced acute kidney injury.

BACKGROUND: Ischaemia/reperfusion is a major cause of acute kidney injury and can result in poor long-term graft function. Although most of the patients with acute kidney injury recover their renal function, significant portion of patients suffer from progressive deterioration of renal function. A persistent inflammatory response might be associated with long-term changes following acute ischaemia/reperfusion. Macrophages are known to infiltrate into tubulointersitium in animal models of chronic kidney disease. However, the role of macrophages in long-term changes after ischaemia/reperfusion remains unknown. We aimed to investigate the role of macrophages on the development of tubulointerstitial fibrosis and functional impairment following acute ischaemia/reperfusion injury by depleting macrophages with liposome clodronate. METHODS: Male Sprague-Dawley rats underwent right nephrectomy and clamping of left renal vascular pedicle or sham operation. Liposome clodronate or phosphate buffered saline was administered for 8 weeks. Biochemical and histological renal damage and gene expression of various cytokines were assessed at 4 and 8 weeks after ischaemia/reperfusion. RESULTS: Ischaemic/reperfusion injury resulted in persistent inflammation and tubulointerstital fibrosis with decreased creatinine clearance and increased urinary albumin excretion at 4 and 8 weeks. Macrophage depletion attenuated those changes. This beneficial effect was accompanied with a decrease in gene expression of inflammatory and profibrotic cytokines. CONCLUSIONS: These results suggest that macrophages play an important role in mediating persistent inflammation and fibrosis after ischaemia/reperfusion leading to a development of chronic kidney disease. Strategies targeting macrophage infiltration or activation can be useful in the prevention of development of chronic kidney disease following ischaemic injury.     

Monoclonal antibody 1-22-3-induced glomerulonephritis in uninephrectomized rats as a model of progressive renal failure.

BACKGROUND: At present, there are few available animal models of progressive renal failure originating from mesangial proliferative glomerulonephritis (GN). In the current study, we examined the usefulness of anti-Thy-1 monoclonal antibody (mAb) 1-22-3-induced GN in uninephrectomized rats as a model of progressive renal failure by analysing the similarities to human disease. METHODS: GN was induced by intravenous injection of mAb 1-22-3 into uninephrectomized male Wistar rats. The natural course of the disease was analysed in this model for 47 weeks. The effect of treatment with the angiotensin-converting enzyme inhibitor, captopril, on renal functional outcome was also examined in this model for 23 weeks, beginning from 1 week after antibody injection. RESULTS: Injection of mAb 1-22-3 induced a persistent proteinuria during the entire study period. Animals showed a progressive decline in renal function and 63% died by week 47. Severe glomerular and tubulointerstitial lesions were consistently observed. Treatment with captopril significantly inhibited increases in proteinuria and blood pressure, and attenuated renal injury. Captopril also retarded the progression of renal failure, and decreased mortality. Finally, the level of proteinuria was significantly correlated with the rate of decline in renal function, and the reduction in proteinuria by captopril was accompanied by a slower progression of renal failure. CONCLUSIONS: The mAb 1-22-3-induced GN in a uninephrectomized rat model simulates the clinical manifestations of human disease, indicating that this model may be useful for studying progressive renal failure and for investigating new therapeutic strategies against renal failure.     

Interstitial Mononuclear Cell Infiltrates in Experimental Nephrosis: Effect of PAF Antagonist

Rats receiving a single injection of either aminonucleosideof puromycin (PAN, 10 mg/100 g) or Adriamycin (ADR, 7.5 mg/kg)develop heavy proteinuria and tubulointerstitial nephritis.Interstitial mononuclear cells were markedly more intense inPAN- than in ADR-treated rats. The composition of cell infiltrateswas characterised in frozen kidney sections using an immunoperoxidasestaining method and a panel of specific monoclonal antibodies.The severe mixed cellular lesions observed in the PAN modelon day 14 were dominated by ED1⁺ macrophages, OX6⁺ Ia-interstitialand OX8⁺ T-cytotoxic/suppressor cell surface markers. A similarbut more discrete ADR-interstitial cell accumulation was observedon day 11 of the experiment. A correlation existed in the PANmodel between the severity of interstitial nephritis and thedegree of proteinuria. In contrast, there was no such correlationin ADR nephrosis. Administration of PAF antagonist (BN 52021),started on the first day and continued throughout the 4 weeksof the experiment, induced in both ADR and PAN-treated ratsa partial reduction in the number of interstitial cell infiltrates.Glomeruli from normal control rats incubated with ³H acetate,substrate for lyso-PAF: acetyl-CoA acetyltransferase and ADRstimulated PAF generation. Although the precise mechanism ofinterstitial cell accumulation in these two models of nephrosisare still unknown, our results suggest that PAF could be animportant factor involved in interstitial cell recruitment.     

Platelet activating factor receptor blockade ameliorates murine systemic lupus erythematosus

Untreated 16-week-old MRL/MpJ-lpr/lpr (lpr) mice, when compared to congenic MRL/MpJ-+/+ (+/+) mice, are characterized by a systemic lupus erythematosus syndrome, including severe glomerulonephritis, proteinuria and reduction of renal function. We hypothesized that platelet activating factor (PAF), a potent chemotactic and proinflammatory phospholipid mediator synthesized and released by circulating cells, glomerular mesangial and renal medullary interstitial cells, may play a role in the development of renal injury in lupus mice. We assessed renal PAF synthesis in lpr as well as +/+ mice and the effect of treatment with a PAF receptor blocking agent. Treatment with the PAF receptor antagonist L659,989 for four weeks, starting at 12 weeks of age, significantly reduced acute glomerular infiltration and proliferation, and prevented chronic glomerular histological changes; proteinuria and serum creatinine levels were also significantly reduced in treated mice. Renal PAF production was increased in lpr when compared to +/+ mice, and treatment with L659,989 restored renal PAF synthesis to the control levels. Our results support the hypothesis that PAF can be one of the mediators of glomerular injury characteristic of murine lupus nephritis, and indicate the possible therapeutic utility of PAF receptor antagonists in immunologic renal diseases.     

Transplantation of a single kidney per se does not lead to late graft dysfunction

In unraveling the pathogenesis of chronic transplant dysfunction (CTD), non-alloantigen specific factors, as ischemia/reperfusion and renal mass have been suggested to play a role in the process. The aim of the present study was to investigate the effect of the transplantation procedure per se on the development of CTD in a syngeneic kidney transplant model in the rat. Kidney transplantation was performed with the BN rat as donor and recipient, the recipient kidneys having been removed. Unilaterally nephrectomized (UNx) and native BN rats served as controls. Renal function was determined monthly (proteinuria and glomerular filtration rate/100 g body weight; GFR). The follow-up period was until 52 weeks post-transplantation. Histomorphological analysis of CTD according to the BANFF criteria was carried out. Immunohistochemical staining was performed to identify infiltrating cells (CD4, CD8, and ED1) and the expression of MHC class II and ICAM-1. Isografts had a minor, constant proteinuria during follow-up, which did not differ from that of UNx: 27 +/- 10 vs. 29 +/- 2 mg/24 h at week 52. Unilateral nephrectomy led to a significant reduction of the GFR, which was about 80% of that of native rats. The GFR of isografts did not differ from that of UNx rats. Histomorphology of renal isografts was comparable to UNx and native kidneys; some glomerulopathy and tubular atrophy leading to a total BANFF-score of 2.6 +/- 0.5. In native BN kidneys, few CD4+ cells and ED-1+macrophages (mphi) were found; MHC class II was constitutively expressed on the proximal tubules and ICAM-1 on the glomeruli and peritubular capillaries. UNx-kidneys showed a similar pattern. Isografts had significantly more CD4+ cells and Mphi, mainly localized in the glomeruli, and a more intense ICAM-1 expression in the glomeruli and interstitium. Transplantation of one kidney in itself does not lead to CTD.     

Early renal post-ischaemic tissue damage and dysfunction with contribution of A1-adenosine receptor activation in rat

Aim:   This study investigated the effect of a selective A₁-adenosine receptor (A₁-AR) antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), on the renal dysfunction and histological damage induced by ischaemia/reperfusion at an early stage.
Methods:   Pentobarbital anaesthetised rats were prepared for measuring renal functional variables. Ischaemia was induced by bilateral renal artery clamping for 30 min followed by a 4 h reperfusion period. In DPCPX-treated rats, it was infused (i.v.) at 10 µg/kg per min before and after renal ischaemia. Both kidneys were examined using light and electron microscopy.
Results:   The renal ischaemic challenge resulted in major histological and ultrastructural damages, which were associated with decreased creatinine clearance, absolute potassium-excretion and effective free-water reabsorption, but increased fractional sodium-excretion and urine flow during reperfusion period. In DPCPX-treated rats, the histological and ultrastructural damage to the kidneys was improved along with the decrease in creatinine clearance and increase in fractional sodium-excretion being smaller, but the increase in urine flow being larger than those of the non-treated rats, while absolute potassium-excretion and effective free-water reabsorption were equal to those of the sham-operated rats.
Conclusion:   These findings suggest that endogenous activation of A₁-AR contributes to the early development of renal ischaemia/reperfusion injury.     

Effects of uninephrectomy and high protein feeding in cyclosporine nephropathy

Using a recently described rodent model of chronic cyclosporine nephropathy (CCN), the effects of uninephrectomy (UNx) and high protein feeding on the development of CCN were studied. After 28 days of i.p. cyclosporine (Cs; 25 mg/kg/day) in UNx and sham nephrectomized (SNx) rats, the single kidney GFR was higher in UNx animals (0.55 +/- 0.09 vs. 0.29 +/- 0.05 ml/min, P less than 0.04) as was RPF (3.05 +/- 0.46 vs. 1.45 +/- 0.37 ml/min, P less than 0.04). Morphometric evaluation of the chronic tubulointerstitial lesion (TI) demonstrated lower scores and relative protection in the UNx group (16.48 +/- 3.52 vs. 64.76 +/- 18.30, P less than 0.01). In separate groups of rats undergoing UNx or SNx and subsequent treatment with Cs, dry kidney weights confirmed that compensatory renal hypertrophy was present in UNx animals. The modulating effect of dietary protein on the lesion of CCN was studied in UNx rats fed a 5% or 60% protein diet during the period of Cs treatment. At the end of the study period animals fed the high protein diet demonstrated a higher RPF (3.19 +/- 0.58 vs. 1.58 +/- 0.29 ml/min, P less than 0.04), higher GFR (0.55 +/- 0.07 vs. 0.35 +/- 0.04 ml/min, P less than 0.05) and lower TI score (64.45 +/- 17.35 vs. 130.32 +/- 23.48, P less than 0.04) when compared with animals consuming a low protein diet. We conclude that the relative renal vasodilation induced by partial ablation of renal mass and high protein feeding affords some protection against the development of CCN.