CsA Nephrotoxicity Research Articles

Mycophenolate Mofetil Is Associated with Altered Expression of Chronic Renal Transplant Histology

Mycophenolate mofetil (MMF) reduces acute rejection in controlled trials of kidney transplantation and is associated with better registry graft survival. Recent experimental studies have demonstrated additional antifibrotic properties of MMF, however, human histological data are lacking. We evaluated sequential prospective protocol kidney biopsies from two historical cohorts treated with cyclosporine (CSA)-based triple therapy including prednisolone and either MMF (n = 25) or azathioprine (AZA, n = 25). Biopsies (n = 360) were taken from euglycemic kidney-pancreas transplant recipients. Histology was independently assessed by the Banff schema and electron microscopic morphometry. MMF reduced acute rejection and OKT3 use (p < 0.05) compared with AZA. MMF therapy was associated with limited chronic interstitial fibrosis, striped fibrosis and periglomerular fibrosis (p < 0.05-0.001), mesangial matrix accumulation (p < 0.01), chronic glomerulopathy scores (p < 0.05) and glomerulosclerosis (p < 0.05). MMF was associated with delayed expression of CSA nephrotoxicity, reduced arteriolar hyalinosis, striped fibrosis and tubular microcalcification (p < 0.05-0.001). The beneficial effects of MMF remained in recipients without acute rejection. Retrospective analysis shows that MMF therapy was associated with substantially reduced fibrosis in the glomerular, microvascular and interstitial compartments, and a delayed expression of CSA nephrotoxicity. These outcomes may be due to a limitation of immune-mediated injury and suggest a direct effect of reduced fibrogenesis.

Activation of Intrarenal Complement System in Mouse Model for Chronic Cyclosporine Nephrotoxicity

PurposeLocal activation of the complement system plays a role in target organ damage. The aim of our study was to investigate the influence of cyclosporine (CsA)- induced renal injury on the complement system in the kidney.Materials and MethodsMice fed a low salt (0.01%) diet were treated with vehicle (VH, olive oil, 1mL/kg/day) or CsA (30mg/kg/day) for one or four weeks. Induction of chronic CsA nephrotoxicity was evaluated with renal function and histomorphology. Activation of the complement system was assessed through analysis of the expression of C3, C4d, and membrane attack complex (MAC), and the regulatory proteins, CD46 and CD55. CsA treatment induced renal dysfunction and typical morphology (tubulointerstitial inflammation and fibrosis) at four weeks.ResultsCsA-induced renal injury was associated with increased the expression of C3, C4d, and MAC (C9 and upregulation of complement regulatory proteins (CD 46 and CD55). Immunohistochemistry revealed that the activated complement components were mainly confined to the injured tubulointerstitium.ConclusionCsA-induced renal injury is associated with activation of the intrarenal complement system.

Dual Response of Animals With Chronic Cyclosporine Nephrotoxicity to an Acute Ischemic Injury

Normal kidneys regenerate after acute injury with little development of chronic fibrosis. However, the long-term effects of an acute injury in kidneys with established chronic toxicity induced by cyclosporine (CsA) are not entirely clear. To study the consequences of an ischemia and reperfusion (IR) injury in long-term CsA-treated rats, male Wistar rats (250–300 g) were treated daily with CsA (10 mg/kg) or vehicle (olive oil 1 mL/kg) for 28 days. On day 21, ischemia was performed by clamping the renal vessel for 1 hour. Blood samples were collected on days 0 and 21 (before IR) as well as days 22 and 28. On day 28, the kidneys were collected to examine the mRNA expression of MCP-1 by real-time PCR. For renal function, serum creatinine levels were measured. Twenty-four hours after reperfusion, long-term CsA-treated animals showed better renal function compared with the control group, as demonstrated by serum creatinine levels: 2.2 ± 0.13 mg/dL vs 2.9 ± 0.18 mg/dL, respectively ( P < .05). However, 1 week after IR, the renal function was worse among the long-term CsA-treated group than the controls: 1.16 ± 0.08 mg/dL vs 0.8 ± 0.09 mg/dL, respectively ( P < .05). Interestingly, CsA treatment was associated with lower MCP-1 mRNA expression than that in the control group: mean MCP-1 mRNA expression 0.58 ± 0.13 vs 1.02 ± 0.12, respectively ( P < .05). In conclusion, animals with chronic CsA nephrotoxicity were protected from an acute renal injury, possibly through decreased chemokine production, although at later time points, renal function was clearly impaired, probably by the acceleration of vasculopathy caused by nephrotoxicity.

Kidney Volume Increases During Long-Term Ciclosporin A Treatment

Purpose Previously, we have for the first time reported enlargement of the pig kidney during long-term ciclosporin (CsA) treatment. In this paper, we summarize our findings of renal enlargement during long-term protocols with various dosages and durations of CsA administration as well as discuss possible pathogenetic mechanisms. Materials and methods Twenty-two adolescent Gottingen minipigs were allocated into four groups: group A ( n = 6) served as controls for 6 months; group B ( n = 5) were treated with CsA (10 mg/kg per day) for 6 months, group C ( n = 4), with CsA (20 mg/kg per day) for 6 months, and group D ( n = 7) with CsA (10 mg/kg per day) orally for 12 months. At regular intervals, renal length and total volume were measured using magnetic resonance imaging; renal biopsies were performed for histological examination. Results A significant increase in kidney volume occurred in all CsA-treated pigs (groups B, C, and D); whereas the volume remained stable in the control animals (group A). A small but significant rise in kidney length was observed in groups A, B, and C, probably due to the normal growth of the animals. Histological examination was normal after treatment with CsA doses of 10 and 20 mg/kg per day for 6 months but showed definite interstitial fibrosis and glomerulosclerosis after treatment with 10 mg/kg per day CsA for 12 months. Conclusion Long-term CsA treatment produced renal enlargement in pigs before the development of histological changes in the kidney. Thus, renal enlargement may represent an early stage of chronic CsA nephrotoxicity.

Mineralocorticoid receptor blockade confers renoprotection in preexisting chronic cyclosporine nephrotoxicity

Recent studies from our laboratory have shown that the mineralocorticoid receptor (MR) blockade with spironolactone (Sp) prevented renal dysfunction and reduced renal injury in both acute and chronic cyclosporine (CsA) nephrotoxicity. This study was designed to evaluate whether Sp administration reduces functional and structural renal damage associated in the setting of preexisting chronic CsA nephrotoxicity. Twenty eight male Wistar rats were fed a low-sodium diet. Fourteen received vehicle (V) and the others were treated with CsA (15 mg/kg sc). After 18 days one half of each group received Sp (20 mg/kg po) for the subsequent 18 days. Creatinine clearance, arteriolopathy, tubulointerstitial fibrosis, arteriolar thickening, glomerular diameter, apoptosis index and TGF-beta, procaspase-3, and kidney injury molecule 1 (Kim-1) mRNA levels as well as Kim-1 shedding in urine were evaluated. Sp reduced the progression of renal dysfunction and tubulointerstitial fibrosis in preexisting chronic CsA nephrotoxicity. There was a significant reduction of arteriolar thickening in the CsA+Sp group that was associated with greater glomerular diameter and reduction of apoptosis index. These renoprotective effects were associated with reduction of TGF-beta, procaspase-3, and Kim-1 mRNA levels as well as Kim-1 shedding into the urine. In conclusion, MR blockade with Sp prevented the progression of renal injury in preexisting chronic CsA nephropathy. These results suggest that Sp may reduce CsA-induced established nephrotoxicity in patients.

Long-term cardiovascular risk in transplantation—insights from the use of everolimus in heart transplantation

Everolimus is a potent immunosuppressive agent that has anti-proliferative activity. The benefits of everolimus vs azathioprine in de novo heart transplant recipients were assessed in a randomized, double-blind study. Patients (n = 634) were randomized to receive everolimus (1.5 mg/day or 3.0 mg/day) or azathioprine; all patients received steroids and full-dose ciclosporin (CsA). The primary endpoint was the incidence of efficacy failure [biopsy-proven acute rejection (BPAR), graft loss, death or loss to follow-up]. The incidence of cardiac allograft vasculopathy (CAV) was assessed by intravascular ultrasound. The incidence and hospitalization costs of major adverse cardiac events (MACE) were assessed after 4 years. The incidence of efficacy failure was significantly reduced with everolimus compared with azathioprine at 12, 24 and 48 months (P < 0.05), largely because of a lower incidence of BPAR. An increase in serum creatinine levels was seen with everolimus compared with azathioprine, likely attributed to CsA nephrotoxicity. There was a significantly larger increase in vascular intimal thickness with azathioprine than with everolimus (P <or= 0.01), which was accompanied by a significantly lower incidence of CAV in the everolimus groups. After 4 years, the incidence of MACE was higher with azathioprine than with either dose of everolimus. MACE-related treatment costs were estimated at 431,428 dollars for azathioprine, 136,664 dollars for everolimus 1.5 mg/day (68% saving) and 191,957 dollars for everolimus 3.0 mg/day (56% saving). Everolimus is significantly more effective than azathioprine in preventing efficacy failure in de novo heart transplant recipients and is also associated with reduced incidence and severity of CAV and MACE at 4 years post-transplant. The reduced 4-year incidence of MACE is likely to lead to substantially reduced hospitalization costs. Since cardiovascular morbidity and mortality are important factors in the long-term survival of renal transplant recipients, applying lessons from the use of everolimus in heart transplantation may further improve the understanding of managing cardiovascular risk in renal transplantation.

TGF-β1 mRNA upregulation influences chronic renal allograft dysfunction

Acute rejection (AR) is a dominant risk factor for developing chronic allograft nephropathy (CAN) after kidney transplantation. CAN is characterized by progressive interstitial fibrosis. It has been associated with increased transforming growth factor (TGF)-beta1 expression, however, kinetic studies are absent. We investigated whether intragraft TGF-beta1 expression in various causes of early graft dysfunction may influence late renal allograft dysfunction. A total of 174 human renal biopsies were quantified for TGF-beta1 mRNA expression using real-time reverse transcriptase-polymerase chain reaction. Expression levels were correlated with the Banff histopathological grades, TGF-beta1 immunohistology, and clinical follow-up. TGF-beta1 was most markedly upregulated in AR, CAN, and acute tubular necrosis - delayed graft function compared to non-rejecting controls (P < 0.001). TGF-beta1 expression was heightened in borderline changes (P < 0.01), recurrence of glomerulonephritis, and cyclosporine toxicity (P < 0.05). There was no correlation between intragraft TGF-beta1 expression during AR and short-term outcome of a rejection episode. TGF-beta1 gene overexpression during CAN has been shown to be associated with the increased risk for renal allograft dysfunction 18 months after biopsy (odds ratios 9.9 vs 3.2, respectively). Intragraft TGF-beta1 mRNA expression is significantly upregulated in both AR and CAN. Thus, our results support the hypothesis that TGF-beta1 might play a key role in chronic allograft dysfunction.

Role of lipoic acid in reducing the oxidative stress induced by cyclosporine A

Background Cyclosporine A (CsA) is the first choice immunosuppresant universally used for the prevention of allograft rejection in solid organ transplantation and immune-mediated diseases. However, with increasing use, evidence has accumulated that CsA therapy is associated with a variety of side effects, the most important being nephrotoxicity. We investigated the potential role of dl-α lipoic acid (LA), a universal antioxidant in combating the oxidative stress induced by CsA. Methods Adult male albino Wistar rats were divided into 4 treatment groups. Two groups received CsA (25 mg/kg body weight, orally for 21 days) to induce nephrotoxicity. One of these groups received LA treatment (20 mg/kg body weight, orally) for 21 days concurrently during CsA administration. A vehicle treated control group and a LA drug control were also included. Results CsA-induced nephrotoxicity was assessed in terms of increased activities of serum marker enzymes; alkaline phosphatase, acid phosphatase and lactate dehydrogenase. An apparent rise in the activities of N-acetyl-β- d-glucosaminidase, β-glucuronidase and cathepsin D were seen in the renal tissue of CsA given rats, which were reversed upon treatment with LA. CsA administration induced significant elevation in lipid peroxidation along with abnormal levels of enzymic (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione- S-transferase and glucose-6-phosphate dehydrogenase) and non-enzymic antioxidants (glutathione, vitamins C and E) in the rat kidney. LA administration improved renal function, by bringing about a significant decrease in peroxidative levels and increase in antioxidant status. Conclusion These results indicate that LA has a protective action against CsA nephrotoxicity and suggest that the LA may find clinical application against a variety of toxins where cellular damage is a consequence of reactive oxygen species.

Exploring cyclosporine A-side effects and the protective role-played by antioxidants: the morphological and immunohistochemical studies.

Cyclosporine A (CsA) is the immunosuppressor most frequently used in transplant surgery and in the treatment of autoimmune diseases, because of its specific inhibiting effect on the signal transduction pathways of cell T receptor. It has been shown that CsA is able to generate reactive oxygen species and lipid peroxidation, which are directly involved in the CsA nephrotoxicity, hepatotoxicity and cardiotoxicity. So, the use of antioxidants seems to be a useful tool in attempting to reduce CsA adverse effects. The aim of this review is to summarise the general aspect of CsA, the classification of antioxidants, their mechanism of action and their administration for improving CsA side effects. The protective role of different antioxidants has been evaluated on CsA-induced nephrotoxicity. It has been shown that the antioxidants, improved the morphological renal cytoarchitecture, increased the antioxidant enzyme content, decreased lipid peroxidation and reactive species oxygen (ROS). The protective role of antioxidants was also found in CsA hepatotoxicity and was related to the increase in antioxidant capacity of hepatic tissue, which was responsible for ameliorating hepatic morphology. Recently, it has been demonstrated that CsA induces side effects on the heart but the data to this purpose are very few and also the number of results on the protective role played by antioxidants it is very limited. In conclusion, not only do these observations provide insight into the intricate mechanism of CsA adverse effects, but they also present novel opportunities for the design and development of more effective therapeutic strategies against negative effects.

Spironolactone (Sp) reduces renal dysfunction and structural damage in established chronic cyclosporine (CsA) nephrotoxicity.

Recent studies from our laboratory showed that the mineralocorticoid receptor blockade with Sp reduced renal injury and reestablished renal dysfunction in both, acute and chronic CsA nephrotoxicity. This study was design to evaluate if spironolactone administration reduces or prevents functional and structural renal damage in established chronic CsA nephrotoxicity. Wistar male rats were fed whit low sodium diet, twenty received vehicle (V) and twenty were treated with CsA (15mg/K sc), after 18 days one half of each group received Sp (20 mg/K p.o.) by 18 days more. Creatinine clearance, arteriolopathy, tubulo-interstitial fibrosis, TGFβ and kidney injury molecule 1 (KIM-1) mRNA levels, as well as KIM-1 in urine were evaluated. Sp reduced renal dysfunction progression and renal structural damage. These effects were associated with reduction of TGFβ and KIM-1 mRNA levels as well as urinary KIM-1. All our findings together showed that the early Sp administration confers greater renoprotection that when it is administrated once the nephropathy is established. These results also pointed out to spironolactone as a potential treatment to prevent or reduce CsA nephrotoxicity in transplant patients.

Ultrastructural Examination of Glomerular and Tubular Changes in Renal Allografts with Cyclosporine Toxicity

The introduction of cyclosporine (CsA) has improved the clinical results of renal transplantation significantly; however, these improvements were closely associated with an increased incidence of renal dysfunction. The present study sought to examine the ultrastructural changes in renal allografts with CsA nephrotoxicity. Nine patients who underwent renal transplantation at the Baskent University Faculty of Medicine between 2001 and 2002 were examined; 26 biopsies of these nine patients who had received their first renal allograft were included in this study. All patients with CsA toxicity showed some form of glomerular endothelial cell injury. The swelling of mitochondria was present in three of nine renal allografts with CsA toxicity, and podocyte changes were found significantly more frequently among patients with CsA toxicity. In addition, focal segmental thickening and the duplication of glomerular basement membrane were observed statistically more frequently. In conclusion, these findings could help differentiate CsA toxicity from other conditions and develop better treatment strategies.

Immunosuppressive treatment and progression of histologic lesions in kidney allografts

Renal transplantation is the best therapeutic option for patients with end-stage renal disease. Although short-term results are excellent, long-term graft survival has not improved substantially in recent times. Chronic allograft nephropathy (CAN) and death with a functioning graft are the most important causes of graft loss. Recent evidence shows that nephrotoxicity of calcineurin inhibitors contributes to CAN, and the introduction of non-nephrotoxic drugs such as mycophenolate mofetil (MMF) and mammalian target of rapamycin inhibitors may provide new immunosuppressive strategies to improve long-term results after renal transplantation. MMF decreases the risk of developing chronic allograft failure and is useful for treating established CAN, because it has a beneficial effect on allograft fibrosis. Treatment with sirolimus (SRL), a basic immunosuppressive drug given in association with MMF, may offer better renal function, decrease the prevalence of CAN, and downregulate expression of genes responsible for the progression of CAN than treatment with cyclosporine A (CsA). SRL also permits an early elimination of CsA from SRL-CsA-steroid regimens and shows better renal function and improved renal histology without risk of rejection. Notably, this approach improves graft survival at 4 years. Further multicenter studies are needed to determine whether both approaches produce similar results by comparing immunosuppression caused by SRL-based and tacrolimus (TAC)-based treatments. Because TAC is the most commonly used anticalcineurin drug, it is important to compare the effects of steroid-TAC-SRL treatment with and without elimination of TAC. Finally, although caution is needed, the use of non-nephrotoxic immunosuppressive treatment may change the natural history of CAN.

HGF gene transfer increases kidney graft survival

The introduction of cyclosporine (CsA) into clinical practice has resulted in marked improvement in the short-term outcome of organ transplantation, and 1-year survival of renal allografts has improved significantly. However, the annual rate of kidney graft loss caused by chronic allograft nephropathy (CAN) has remained stable over last decade. CAN may result from perioperative ischemia at the time of transplantation. Furthermore, chronic CsA nephrotoxicity may progress to an irreversible renal lesion characterized by tubular atrophy, striped interstitial fibrosis, hyalinosis of the afferent arteriole, and progressive renal impairment. Recent report demonstrated the therapeutic effects of hepatocyte growth factor (HGF) in preventing CAN using a well-established rat CAN model. They showed that HGF treatment during the initial 4 weeks after engraftment prevented onset of CAN and associated death and provided longlasting benefit in terms of graft survival. Exogenous HGF is very unstable in the blood circulation due to the rapid clearance by the liver. To circumvent this problem, we developed a new gene transfer system by electroporation in vivo. Therefore, this gene transfer approach represents a useful technique to investigate the therapeutic potential of HGF gene transfer for long-term survival of kidney allograft. The goal of the present study was to assess the renoprotective potential and safety of HGF gene transfer using a porcine kidney transplant warm ischemia injury model or CsA nephrotoxicity model. In the first set of experiments, following left porcine kidney removal, 10 minutes of warm ischemic injury was intentionally induced. Next, the HGF expression vector or vehicle was infused into the renal artery with the renal vein clamped ex vivo, and electric pulses were discharged using bathtub-type electrodes. Kidney grafts were then transplanted after removing the right kidney. Histopathologic examination of vehicle-transfected kidney transplant revealed initial tubular injury followed by tubulointerstitial fibrosis. In contrast, HGF-transfected kidneys showed no initial tubular damage and no interstitial fibrosis at 6 months posttransplant. In the next set of experiments, CsA was subcutaneously administered daily under low sodium diet, and HGF gene was transferred into skeletal muscle by electroporation on days 7 and 14. We also examined the antiapoptotic mechanism of HGF using human proximal tubular epithelial cells. HGF gene transfer rescued CsA-induced initial tubular injury, and suppressed interstitial infiltration of endothelium-1 (ED-1)-positive macrophages in CsA nephrotoxicity. In addition, HGF significantly inhibited tubular cell apoptosis, and increased the number of proliferating tubular epithelial cells. In vitro studies suggest that HGF executes the antiapoptotic function by enhancing the phosphorylation of Akt and Bcl-2. Northern blot analysis demonstrated that HGF gene transfer suppressed cortical mRNA levels of transforming growth factor-β (TGF-β). Consequently, HGF gene transfer significantly reduced a striped interstitial phenotypic alteration and fibrosis. We conclude that electroporation-mediated HGF gene transfection protects the kidney against graft injury.

Curcumin, a diferuloylmethane, attenuates cyclosporine-induced renal dysfunction and oxidative stress in rat kidneys

BackgroundIn India, Curcumin (CMN) is popularly known as "Haldi", and has been well studied due to its economic importance. Traditional Indian medicine claims the use of its powder against biliary disorders, anorexia, coryza, cough, diabetic wounds, hepatic disorder, rheumatism and sinusitis. This study was designed to examine the possible beneficial effect of CMN in preventing the acute renal failure and related oxidative stress caused by chronic administration of cyclosporine (CsA) in rats. CMN was administered concurrently with CsA (20 mg/kg/day s.c) for 21 days. Oxidative stress in kidney tissue homogenates was estimated using thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH) content, superoxide dismutase (SOD), and Catalase (CAT). Nitrite levels were estimated in serum and tissue homogenates.ResultsCsA administration for 21 days produced elevated levels of TBARS and marked depletion of renal endogenous antioxidant enzymes and deteriorated the renal function as assessed by increased serum creatinine, Blood Urea Nitrogen (BUN) and decreased creatinine and urea clearance as compared to vehicle treated rats. CMN markedly reduced elevated levels of TBARS, significantly attenuated renal dysfunction increased the levels of antioxidant enzymes in CsA treated rats and normalized the altered renal morphology.ConclusionIn conclusion our study showed that CMN through its antioxidant activity effectively salvaged CsA nephrotoxicity.

C1-C2 point monitoring of low-dose cyclosporin A given as a single daily dose in children with steroid-dependent relapsing nephrotic syndrome

It has been reported that the pharmacokinetics of cyclosporin A (CsA) in children is different from that in adults. It appears that, in general, pediatric patients metabolize CsA more rapidly than adult patients, necessitating the use of higher dose of the drug in pediatric transplant recipients. In this context, we speculated that single-dose daily administration of low-dose CsA may be associated with a higher peak blood level without associated trough blood level elevation, and thereby yield better results and allow safer use of the drug than the conventional twice daily administration dosing used for the treatment of childhood idiopathic nephrotic syndrome (INS). A total of 10 children with steroid-dependent relapsing INS (9 with biopsy-proven minimal-change disease) who showed steroid toxicity were enrolled in the study. The initial daily dose of CsA (Neoral) used was around 2.0 mg/kg, given as a single daily dose before breakfast. The dose was subsequently adjusted to achieve a C1-C2 point blood level between 600 - 800 ng/ml. The dose of the concomitantly administered prednisolone was tapered following the commencement of CsA. The mean daily CsA dosage, the mean C1-C2 point blood level and the mean trough blood level in the subjects were 2.2 +/- 0.8 mg/kg, 754.0 +/- 71.9 ng/ml and 42.7 +/- 29.2 ng/ml, respectively. At the latest observation, after a mean duration of 17 months (6 - 24 months) of CsA therapy, the minimum dose of prednisolone required for maintenance of clinical remission and the calculated relapse rate were significantly decreased as compared to the respective pretreatment values (0.52 +/- 0.46 mg/kg on alternate days, vs. 0.97 +/- 0.63 mg/kg on alternate days, and 0.28 +/- 0.32 times per six months, vs. 1.06 +/- 0.41 times per six months, respectively, p = 0.005). No significant change was observed in the mean estimated GFR value as compared to the pretreatment value (183.1 +/- 35.4 ml/min/1.73 m2vs. 185.4 +/- 39.3 ml/min/1.73 m2). No evidence of CsA nephrotoxicity was observed in a repeat renal biopsy performed around 12 months after the commencement of CsA therapy in two patients. Despite the limitations of the study, our results suggest that administration of low-dose CsA as a single daily dose with C1-C2 point blood level monitoring might be an equally effective and safe and, therefore, more cost-beneficial, protocol for the treatment of steroid-dependent cases of relapsing INS, as conventional twice-daily administration of CsA with trough blood level monitoring. Further studies to confirm the long-term efficacy and safety of this CsA treatment protocol in larger numbers of patients are, however, needed.

Benefits of Early Biopsy on the Outcome of Kidney Transplantation

Introduction Delayed graft function has been associated with worse long-term kidney allograft survival. Adequate diagnosis of the etiology of dysfunction is crucial, often requiring routine early biopsies. The aim of this article was to report the results and safety of early kidney allograft biopsies and how they influenced its management. Method Between September 1994 and July 2004, 134 renal transplant recipients were prescribed cyclosporine (CsA; Neoral, Novartis, Chile), steroids, and a third agent (azathioprine in 92% of the graft recipients). Thirty-four patients (26%) had a kidney biopsy performed within the first week because of allograft dysfunction. Results The main diagnosis was acute tubular necrosis (ATN) in 22 patients (65%), whereas 6 (18%) were diagnosed with an acute rejection episode (ARE), allowing prompt initiation of therapy with reversal of rejection in 4 of them. Two patients (6%) showed signs of thrombotic microangiopathy (TMA) induced by CsA, which subsided following a switch from CsA to tacrolimus (Prograf Pharmainvesti, Chile). In 2 patients, the biopsy specimen showed signs of CsA nephrotoxicity that reverted following dose reduction. Finally, in 2 patients, the biopsy specimen showed chronic nephropathy of donor origin, which had not been previously recognized, resulting in graft loss. There was only one major complication related to the biopsy, intraperitoneal bleeding that required surgical treatment. Conclusions Early allograft biopsy is safe and, in a significant number of cases (30%), it detects important allograft pathology (ARE, TMA, and drug toxicity), which when adequately and promptly treated may rescue the graft.

Investigating the protective effects of aged garlic extract on cyclosporin‐induced nephrotoxicity in rats

Cyclosporin A (CsA) nephrotoxicity has been described in solid organ recipients and in the patients who were treated for autoimmune diseases. Reactive oxygen species-induced oxidative stress and lipid peroxidations are implicated in the pathophysiology of CsA-induced renal injury. Aged garlic extract (AGE) has been reported to exhibit potent antioxidative and free radical scavenging abilities in various disease conditions. The present study was designed to investigate whether AGE could possibly have a protective effect against nephrotoxicity induced by CsA. Male Wistar rats were treated orally with CsA (50 mg/kg/day), CsA + AGE (0.25, 0.5, 1, and 2 g/kg/day started 3 days before the first dose of CsA), or the vehicle of CsA for a period of 10 days. Blood urea nitrogen, serum creatinine, creatinine clearance, and renal histopathological changes were evaluated after 24 h of the last treatment. CsA caused an increase in blood urea nitrogen and serum creatinine by 117 and 100%, respectively, whereas it decreased creatinine clearance by 78% compared with the vehicle-treated rats (all P < 0.001). AGE treatment (0.5, 1 and 2 g/kg) significantly protected animals against CsA-induced biochemical changes, albeit blood urea nitrogen and creatinine clearance in the 0.5 g/kg AGE treated-animals were only partially restored. Kidney sections taken from CsA-treated rats showed severe vacuolations and tubular necrosis. These histopathological changes were markedly improved by pretreatment of rats with AGE at the dose of 0.5--2 g/kg. The results indicate that AGE ameliorates renal dysfunction and morphological changes induced by CsA, and imply that it could be a beneficial remedy for attenuating the CsA nephrotoxicity.

Protective Effect of Oral L-arginine Supplementation on Cyclosporine Induced Nephropathy in Rats

One of the major adverse effects of long term cyclosporine A (CyA) administration is chronic nephrotoxicity. Several studies have suggested that alterations of the L-arginine (L-Arg) nitric oxide (NO) pathway may be involved in the pathogenesis of CyA-induced kidney damage. We postulated that in vivo activation of L-Arg-NO pathway might have a beneficial effect on CyA-induced renal damage. Conditions of chronic NO enhancement was established with L-Arg supplementation and chronic NO blockade with N-nitro-L-Arg methyl ester (L-NAME). We tested the hypothesis that, if CyA administration alters intrarenal NO synthesis, then exogenous L-Arg supplementation could limit renal injury, on the contrary, L-NAME, a potent competitive inhibitor of NO synthesis, could enhance CyA nephrotoxicity. Harmful effect of NO blockade indirectly supports the beneficial effect of NO in a model of CyA nephrotoxicity. Rats were administered vehicle (VH), CyA (7.5 mg/kg/day), CyA + L-Arg (2g/kg/day), CyA + L-NAME (5 mg/100 ml/day), CyA + L-Arg + L-NAME, VH + L-Arg, VH + L-NAME and were sacrificed at the end of the experiment. Body weight, serum creatinine, blood urea nitrogen (BUN) and NO levels were determined. Tubular injury and interstitial fibrosis were evaluated semiquantitatively using scoring systems on paraffin sections stained with hematoxylin/eosin (H/E), Masson's trichromic and periodic acid-Schiff (PAS). The CyA group developed marked renal injury, characterized by a significant increase in serum creatinine and BUN, and histopathological alterations including tubular dilatation, vacuolization, necrosis, interstitial cell infiltration and tubulointerstitial fibrosis. CyA reduced serum NO level. L-Arg treatment significantly enhanced NO biosynthesis and protected animals from CyA-induced kidney damage. In contrast L-NAME strikingly reduced serum NO level, and worsened biochemical and histopathological alterations. Chronic CyA nephrotoxicity can be aggravated by NO blockade and ameliorated by NO enhancement suggesting that L-Arg supplementation may be protective in CyA nephrotoxicity.

Renocortical mRNA expression of vasoactive factors during spironolactone protective effect in chronic cyclosporine nephrotoxicity

We showed that spironolactone reduced structural damage and prevented renal dysfunction in chronic cyclosporine (CsA) nephrotoxicity. These findings evidenced an aldosterone renal vascular effect under this condition. To investigate aldosterone's role in modulating renal vascular tone, renocortical vasoactive pathways mRNA levels in chronic CsA nephrotoxicity as well as spironolactone's effect on renal function in acute CsA nephrotoxicity were evaluated. Two experimental sets were designed. For chronic nephrotoxicity, rats fed with low-sodium diet were divided into groups receiving vehicle, spironolactone (Sp), CsA, and CsA+Sp, for 21 days. Creatinine clearance, survival percentage, and renocortical mRNA levels of pro-renin, angiotensinogen (Ang), angiotensin receptors (AT(1A), AT(1B), and AT(2)), preproendothelin, endothelin receptors (ET(A), ET(B)), cyclooxygenase-2 (COX-2), and adenosine receptors (Ad(1), Ad(2A), Ad(2B), and Ad(3)) were analyzed. For acute nephrotoxicity, similar groups fed with a standard chow diet for 7 days were included. Serum potassium and sodium, glomerular filtration rate (GFR), and renal blood flow (RBF) were determined. In chronic model, CsA produced pro-renin and ET upregulation, altered adenosine receptors expression, and reduced Ang, AT(1A), AT(1B), ET(B), and COX-2 mRNA levels. Spironolactone protective effect in chronic nephrotoxicity was associated with prevention of pro-renin upregulation and increased AT(2), together with ET(B) reduction. In acute nephrotoxicity, spironolactone completely prevented GFR and RBF reduction induced by CsA. Our results suggest that aldosterone contributes to renal vasoconstriction observed in CsA nephrotoxicity and that renoprotection conferred by spironolactone was related to modification of renocortical vasoactive pathways expression, in which pro-renin normalization was the most evident change in chronic nephropathy. Finally, our data point to spironolactone as a potential treatment to reduce CsA nephrotoxicity in transplant patients.

Differential expression of tissue factor (TF) in calcineurin inhibitor-induced nephrotoxicity and rejection—implications for development of a possible diagnostic marker

Deposition of fibrin in the form of fibrinoid necrosis is a common feature of severe acute renal allograft rejection. The role of the coagulation system and its initiator tissue factor (TF) during this process is, however, still poorly understood. In this study, we analyzed the expression of TF in 88 renal transplants afflicted with different forms of rejection and calcineurin inhibitor-induced nephrotoxicity, to see whether there was differential expression of this protein. TF immunoreactivity was evaluated semiquantitatively in six different renal structures: the podocytes, Bowman epithelium, the endothelium of the glomeruli, the brush border of tubular cells, the thin ascending loop of Henle, and small arteries/arterioles. The TF expression of normal renal tissue ( n = 6) was restricted to the glomerular podocytes and Bowman epithelium, and to some extent the ascending loop of Henle. Renal allografts undergoing acute rejection (AR) of grades I–III, ( n = 13, n = 17 and n = 12, respectively) did not show any altered TF expression in the glomeruli or vascular endothelium. In the ascending loop of Henle, a reduced expression could be seen (ARI, p = 0.015; and ARII, p = 0.043). TF staining of the brush border of renal transplants undergoing acute cyclosporin A (CsA) nephrotoxicity ( n = 18) was significantly higher than in normal kidneys ( p = 0.0003), as well as in transplants undergoing various degrees of acute rejection (ARI, p = 0.027; ARII, p = 0.0012; and ARIII, p = 0.0001). Tubular brush border-expressed TF was also evident in 10 of 15 allografts suffering from chronic CsA nephrotoxicity, compared to 4 out of 13 cases with chronic allograft vasculopathy (CAV), but the increase was not statistically significant relative to normal kidneys. The majority of the grafts afflicted with either of the two chronic conditions displayed a TF-positive arterial endothelium (CAV, p = 0.0034; and chronic CsA nephrotoxicity, p = 0.0026) relative to controls. In conclusion, these results indicate that vascular TF expression is not altered during acute rejection, but may be of importance in chronic allograft nephropathy. Furthermore, TF immunoreactivity in the tubular brush border may be specific to acute CsA nephrotoxicity and might be used as a biomarker for this condition. Further studies are required to evaluate the possible role of brush border-expressed TF in the pathogenesis of CsA nephrotoxicity.