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N Lloberas

Publications and source records attributed to N Lloberas.

16 recordsLinked to original sources
PubMed2006

HGF gene therapy attenuates renal allograft scarring by preventing the profibrotic inflammatory-induced mechanisms.

Inflammatory processes and tissue scarring are characteristic features of chronic allograft nephropathy. Hepatocyte growth factor (HGF) has beneficial effects on renal fibrosis and it also ameliorates renal interstitial inflammation as it has been recently described. Contrarily to protein administration, intramuscular gene electrotransfer allows sustained release of HGF. So, here we hypothesized that gene therapy with human HGF would diminish the characteristic scarring of chronic allograft nephropathy either by antagonizing tissue fibrosis mechanisms or by reducing inflammation. Lewis rats transplanted with cold preserved Fischer kidneys received vehicle (NoHGF) or intramuscular plasmid DNA encoding HGF plus electroporation either before transplantation (IniHGF, early post-transplant cytoprotection of tubular cells) or 8/10 weeks after transplantation (DelHGF, delayed prevention of chronic mechanisms). Serum creatinine and proteinuria were measured every 4 weeks for 24 weeks. Grafts at 12 or 24 weeks were evaluated for glomerulosclerosis, fibrosis inflammatory cells and mediators, cell regeneration and tubulo-interstitial damage. Nontreated animals developed renal insufficiency, progressive proteinuria and fibrosis among other characteristic histological features of chronic allograft nephropathy. Treatment with human HGF, especially when delayed until the onset of fibrogenic mechanisms, reduced renal failure and mortality, diminished tubule-interstitial damage, induced cell regeneration, decreased inflammation, NF-kappaB activation, and profibrotic markers at 12 weeks and prevented late interstitial fibrosis and glomerulosclerosis. The effectiveness of HGF-gene therapy in the prevention of renal allograft scarring is related with the halt of profibrotic inflammatory-induced mechanisms.

Animals↗
PubMed2005

Role of cold ischemia in acute rejection: characterization of a humoral-like acute rejection in experimental renal transplantation.

The aim of the study was to characterize the role of cold ischemia in the process of acute rejection using an experimental renal transplant model. Syngeneic renal transplants were performed between Wistar Agouti rats and allogeneic grafts using Wistar-Agouti rats as recipients of Brown-Norway kidneys. For cold ischemia (CI), kidneys were preserved in Euro-Collins (4 degrees C/ 2.5 hours). Rats were bilaterally nephrectomized at the moment of renal transplant and did not receive any immunosuppressant. The groups were NoAR (n = 6): immediate syngeneic transplant; CI-NoAR (n = 6): syngeneic transplant with CI; AR (n = 13): immediate allogeneic graft; CI-AR (n = 6): allogeneic graft with CI. Allogeneic rats were followed for the survival study. Syngeneic rats, with mean survival time beyond 6 months, were sacrificed on the day 7 to compare grafts with those in the allogeneic groups. H&E- and PAS-stained grafts were evaluated using the Banff criteria. Tissue INF-gamma and TNF-alpha were quantified by RT-real time-PCR on the kidney grafts. Renal insufficiency did not appear in the NoAR group, but it did from the posttransplant day 5 in both acute rejection groups. While NoAR kidneys showed well-conserved renal architecture, then AR group displayed variable degrees of tubular necrosis with scarce cellular infiltration, interstitial hemorrhage, vascular damage with fibrinoid necrosis, perivascular edema, and nuclear disruption. Cold ischemia in rejecting animals increased the mortality rate due to renal insufficiency and accelerated acute rejection. Independently of CI, the proinflammatory cytokines TNF-alpha and INF-gamma were increased in both rejection groups. In conclusion, addition of CI overactivates the acute rejection process via a humoral component.

Acute Disease↗
PubMed2005

Direct electrotransfer of hHGF gene into kidney ameliorates ischemic acute renal failure.

In the early phase of kidney transplantation, the transplanted kidney is exposed to insults like ischemia/reperfusion, which is a leading cause of acute renal failure (ARF). ARF in the context of renal transplantation predisposes the graft to developing chronic damage and to long-term graft loss. Hepatocyte growth factor (HGF) has been suggested to support the intrinsic ability of the kidney to regenerate in response to injury by its morphogenic, mitogenic, motogenic and antiapoptotic activities. In the present paper, we examine whether human HGF (hHGF) gene electrotransfer helps in the recovery from ARF in a model of rat renal warm ischemia. We also assess the advantages of this form of gene therapy by direct electroporation of the kidney, given that transplantation offers the possibility of manipulating the organ in vivo. We have compared the therapeutic efficiency of two electroporation methodologies in a rat ARF model. Although they both targeted the same organ, the two methods were applied to different parts of the animal: muscle and kidney. Kidney direct electrotransfer was shown to be more efficient not only in pharmacokinetic but also in therapeutic terms, so it may become a clinically practical alternative in renal transplantation.

Acute Kidney Injury↗
PubMed2001

The enhancement of endogenous cAMP with pituitary adenylate cyclase-activating polypeptide protects rat kidney against ischemia through the modulation of inflammatory response.

BACKGROUND: Cyclic nucleotide analogue administration improves ischemia-reperfusion damage in several organs. The neuropeptide pituitary adenylate cyclase-activating polypeptide, PACAP-38, is a potent stimulus to enhance cellular cAMP levels. This study tested the protective effect of enhancing endogenous cAMP levels by PACAP-38 in a model of warm renal ischemia. METHODS: Sprague-Dawley rats underwent 40 min of bilateral warm renal ischemia. PACAP-38 continuous infusion began either before ischemia or at 6 hr or 18 hr after ischemia. A mini-osmotic pump infused PACAP-38 throughout 7 days of follow-up. Groups were constructed with sham, ischemic control, and dibutyryl cAMP treated animals, and four PACAP-38 treatment groups, using 16 pmol/hr or 160 pmol/hr of the compound, or delaying its administration by 6 hr or 18 hr after ischemia. Renal function was assessed by means of serum creatinine levels on days 1, 2, 3, and 7 after ischemia. Conventional histology was performed on day 7. Renal myeloperoxidase (MPO) activity, infiltrating CD45+ cells, plasma and tissue cAMP, and serum IL-6 were measured. RESULTS: Continuous administration of the high concentration of PACAP-38 ameliorated renal function and morphologic abnormalities induced by warm ischemia. Treatment with dibutyryl cAMP produced morphologic protection but only partial functional effect on the ischemic kidney. A 6-hour delay in the administration of the compound after ischemia offered similar protective effect, whereas an 18-hr delay did not. The neuropeptide clearly increased circulating cAMP after ischemia but not cAMP in renal tissue. PACAP-38 increased circulating IL-6, and minimized renal inflammatory cell infiltration induced by ischemia-reperfusion injury, as evidenced by a reduction of MPO activity and the number of CD45+ cells in ischemic renal tissue. CONCLUSIONS: Enhancement of endogenous circulating cAMP with PACAP-38 modulates postischemic inflammatory response and strongly protects from ischemic acute renal failure, even when administration is delayed for 6 hr after injury.

Acute Kidney Injury↗
PubMed2001

Protective effect of UR-12670 on chronic nephropathy induced by warm ischaemia in ageing uninephrectomized rats.

BACKGROUND: In young animals, renal ischaemia/reperfusion injury and mass reduction are associated with chronic lesions that mimic those found in chronic rejection. We have shown that the phospholipid platelet-activating factor (PAF) participates in young animals in such chronic nephropathy. Here we examine the long-term effects of the orally active PAF antagonist, UR-12670 in ageing uninephrectomized rats exposed to prolonged warm ischaemia. METHODS: Fifteen- to eighteen-month-old uninephrectomized male Sprague-Dawley rats were allocated into three groups and followed for 16 weeks: UNx, rats without ischaemia; UNxISC, ischaemic kidney (60 min), and UNxISC+UR, ischaemic kidney and UR-12670 from day 0 to the 16th week. Serum creatinine and proteinuria were monitored every 4 weeks. At the end of the study, conventional histology was performed and monocyte-macrophages were identified with the specific monoclonal antibody ED-1. RESULTS: The UNxISC group had severe acute renal failure with a high mortality rate, which was associated with incomplete restoration of renal function. Renal insufficiency in this group was sustained throughout the follow-up. Both UNx and UNxISC groups developed progressive proteinuria from the 12th week. Though UNxISC+UR group showed similar acute renal failure and mortality rate to the ischaemic non-treated group, serum creatinine decreased to levels similar to UNx group, which were maintained until the end of the study. Treatment of ischaemic kidneys with UR-12670 produced a slight decrease in 24-h proteinuria and a reduction in glomerulosclerosis, the mean tubulointerstitial score and number of monocyte-macrophages to values similar to UNx group. CONCLUSIONS: The chronic administration of the PAF antagonist UR-12670 attenuates the long-term effects of ischaemia-reperfusion injury in uninephrectomized ageing rats. The beneficial effect of this agent suggests that PAF contributes to the progression to late renal damage in this model.

Administration, Oral↗
PubMed2000

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

Animals↗
PubMed2000

Influence of nephron mass in development of chronic renal failure after prolonged warm renal ischemia.

The present study examined the long-term consequences of warm renal ischemia (WRI) with or without renal ablation. Male Sprague-Dawley rats (250-300 g) were subjected to 60 min of complete WRI by pedicle clamping and then followed for 52 wk. Animals were organized into four groups: rats in which both kidneys were subjected to warm ischemia (2WIK); rats with left WRI and right nephrectomy (1WIK); uninephrectomized rats with a left nonischemic kidney (1NK); and sham-operated rats (2NK). Additional animals were studied at 24 h, 7 days, and 16 and 32 wk. In the first week after WRI, rats from the 2WIK and 1WIK groups displayed a similar degree of acute renal damage. After recovering from acute renal failure, 1WIK rats developed progressive and severe proteinuria, whereas it was mild in the 2WIK group, as well as in the 1NK and 2NK groups. Only animals from the 1WIK group developed severe chronic renal failure, glomerulosclerosis, interstitial fibrosis, and upregulation of transforming growth factor-beta(1) (TGF-beta(1)) gene, which was associated with increased TGF-beta(1) protein expression in tubular epithelial cells, arterioles, and in areas of mononuclear interstitial cell infiltrate. On the contrary, long-term renal TGF-beta(1) expression, function, and histology were similar in 2WIK and 2NK rats. The present study shows that prolonged bilateral WRI, when both kidneys are retained in place, induces very mild long-term renal lesions as opposed to the severe renal scarring observed when WRI is combined with contralateral nephrectomy.

Acute Kidney Injury↗
PubMed1999

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.

Acute Kidney Injury↗
PubMed1999

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.

Animals↗
PubMed1998

Effect of a platelet-activating factor (PAF) receptor antagonist on hyperacute xenograft rejection; evaluation in a pig kidney-human blood xenoperfusion model.

In pig to human discordant xenotransplantation, PAF may contribute to the pathogenesis of hyperacute xenograft rejection (HXR). We examined the release of PAF and the effect of a PAF receptor antagonist (BN 52021) on HXR in a pig kidney-human blood xenoperfusion model. Pig kidneys were perfused with porcine blood (AUTO group, n = 5), human blood (HETER group, n = 6) or human blood plus BN 52021 (BN group, n = 4), respectively. In contrast to HETER kidneys that never produced urine and were rejected in 15-30 min, the administration of BN 52021 induced a partial recovery of glomerular filtration rate and allowed kidneys to function until the end of the study. The release of PAF and soluble P-selectin, as well as endothelial P-selectin expression and tissue myeloperoxidase (MPO), were much higher in the HETER than in the AUTO group. HETER and BN kidneys displayed similar natural xenoantibody titres, CH50, PAF, soluble P-selectin as well as renal immunoglobulin (IgM, IgG, IgA) and complement (C3, C1q) deposition. However, HETER kidneys displayed a full histologic picture of HXR (mainly interstitial haemorrhage and vascular microthrombi) and BN kidneys had only endothelial cell swelling. Also, BN 52021 administration attenuated glomerular and vascular P-selectin expression and renal tissue MPO activity. We conclude that in the pig kidney-human blood xenoperfusion model, PAF is produced in higher amounts than in the pig kidney-pig blood autologous combination. The administration of BN 52021 exerts a protective effect by means of attenuating the acute inflammatory response and blocking vascular microthrombi formation.

Animals↗
PubMedDate not supplied

Effect of human natural xenoantibody depletion and complement inactivation on early pig kidney function.

Preformed xenoreactive natural antibodies (XNA) and complement mediate hyperacute xenograft rejection (HXR) in pig-to-human discordant xenotransplantation. In a pig kidney-human blood xenoperfusion model, we investigated whether XNA depletion and/or human complement inactivation preserved early pig kidney function. Pig kidneys were perfused for 180 min with pig blood (AUTO group, n = 8), human blood (HETER group, n = 6), complement-inactivated human blood (COMi group, n = 5), XNA-depleted human blood (ABd group, n = 5) or complement-inactivated and XNA-depleted human blood (ABd&COMi group, n = 5). HETER kidneys were rejected after 15-30 min and showed vascular microthrombi and interstitial hemorrhages. XNA depletion and/or complement inactivation prevented HXR. The glomerular filtration rate in ABd, COMi and ABd&COMi groups was significantly lower than in the AUTO group. Also, beyond 60 min, the COMi group showed a significantly lower glomerular filtration rate than that observed in ABd and ABd&COMi groups. Kidneys from ABd, COMi and ABd&COMi groups displayed endothelial cell edema, as well as higher soluble P-selectin levels and a higher renal myeloperoxidase content than the AUTO group kidneys. COMi and ABd&COMi groups had a significantly lower renal myeloperoxidase level than the HETER group. Also, in contrast to HETER and ABd groups, these complement-inactivated groups failed to show a positive correlation between P-selectin and renal myeloperoxidase. We also investigated platelet-activating factor (PAF) as possible mediator for these functional and pathologic changes. We found that blood PAF levels were similar in HETER, ABd, COMi and ABd&COMi groups and significantly higher than in the AUTO group. Also, when PAF was added to porcine endothelial cell monolayers, morphological changes due to cytoskeleton contraction were observed, and these changes were prevented by preincubation with a PAF receptor antagonist. In conclusion, although depletion of XNA and/or complement inactivation prevent HXR, the pig kidney function is not preserved at the level of the autologous combination. The PAF overproduction observed in the xenogenic combination, which is independent of the presence of XNA and complement, may be, at least in part, responsible for early endothelial cell morphological changes still present when HXR is prevented.

Animals↗