Delayed graft function in renal transplantation: etiology, management and long-term significance

Consequences of transplant quality on chronic allograft nephropathy

Using kidneys from expanded-criteria donors to alleviate organ shortage has raised concern on reduced transplant outcomes. In this paper, we review how critical donor-related factors such as donor age, brain death, and consequences of ischemia-reperfusion injury (IRI) determine graft quality and impact chronic allograft nephropathy. We propose that combinatorial effects of organ-intrinsic features associated with increasing age and unspecific injuries related to brain death and IRI will impact innate and adaptive immune responses. Future research will need to explore avenues to optimize donor management, organ preservation, adapted immunosuppressive strategies, as well as modifications of the allocation of suboptimal allografts.

Does timing of post-renal transplant diuresis affect graft survival in live-donor renal transplants?

OBJECTIVE

To study the effect of timing of diuresis on short and long term graft survival in live-donor (LD) renal transplants.

METHODS

Between 1976 and 2005, 1747 consecutive LD renal transplants were performed in a single institution. Patients were classified according to timing of diuresis after vascular de-clamping; group 1 included patients with diuresis within 10 min; group 2 started diuresis between 10 and 60 min after de-clamping; group 3 started diuresis between 1 and 24 h after de-clamping; and group 4 started diuresis > 24 h after de-clamping. Patients' data were stored on an electronic database and were reviewed for risk factors and clinical relevance of timing of diuresis.

RESULTS

Groups 1-4 comprised 1598 (91.5%), 87 (5%), 44 (2.5%) and 18 (1%) patients, respectively. By multivariate analysis, vascular thrombosis was the significant risk factor for delayed diuresis. Delayed diuresis was significantly associated with the occurrence of acute tubular necrosis (ATN), and acute and chronic rejection. Graft and patient survival rates were significantly affected by the timing of diuresis. The 1-year graft survival rates were 93.8, 83.0, 83.6 and 55.6%, and the 5-year graft survival rates were 77.4, 59.4, 69.4 and 35.7% in groups 1, 2, 3 and 4, respectively (P < 0.001). The 1-year patient survival rates were 96.5, 84.4, 90.7 and 61.1% and the 5-year patient survival rates were 87.1, 72.0, 78.1 and 52.4% in groups 1, 2, 3 and 4, respectively (P < 0.001).

CONCLUSION

Delayed diuresis is a rare event after LD renal transplantation, which has an adverse effect on short- and long-term graft and patient survival.

Rb1 postconditioning attenuates liver warm ischemia-reperfusion injury through ROS-NO-HIF pathway

AIMS

Ginsenoside Rb1 could prevent ischemic neuronal death and focal cerebral ischemia, but its roles to liver warm I/R injury remain to be defined. We determined if Rb1 would attenuate warm I/R injury in mice.

MAIN METHODS

Mice were divided into sham, I/R, Rb1+I/R (Rb1 postconditioning, 20mg/kg, i.p. after ischemia), sham+L-NAME, I/R+L-NAME, and Rb1+I/R+L-NAME groups using 60min of the liver median and left lateral lobes ischemia. Serum levels of alanine aminotransferase (ALT) were measured and morphology changes of livers were evaluated. Contents of nitric oxide (NO) and nitric oxide synthase (NOS), malondialdehye (MDA) and activity of superoxide dismutase (SOD) were measured. Expressions of Akt, p-Akt, iNOS, HIF-1alpha, tumor necrosis factor-a (TNF-α) and intercellular adhesion molecule-1 (ICAM-1) were also determined by western blot or immunohistochemistry.

KEY FINDINGS

Rb1 postconditioning attenuated the dramatically functional and morphological injuries. The levels of ALT were significantly reduced in Rb1 group (p<0.05). Rb1 upregulated the concentrations of NO, iNOS in serum, iNOS, and activity of SOD in hepatic tissues (p<0.05), while it dramatically reduced the concentration of MDA (p<0.05). Protein expressions of p-Akt, iNOS and HIF-1alpha were markedly enhanced in Rb1 group. Protein and mRNA expressions of TNF-α and ICAM-1 were markedly suppressed by Rb1 (p<0.05).

SIGNIFICANCE

We found that Rb1 postconditioning could protect liver from I/R injury by upregulating the content of NO and NOS, and also HIF-1alpha protein expression. These protective effects could be abolished by L-NAME. These findings suggested Rb1 may have the therapeutic potential through ROS-NO-HIF pathway for management of liver warm I/R injury.

Epigallocatechin-3-gallate protects kidneys from ischemia reperfusion injury by HO-1 upregulation and inhibition of macrophage infiltration

Epigallocatechin-3-gallate (EGCG) shows diverse chemical and biological activities. We investigated the effects of EGCG in a rat renal ischemia reperfusion (I/R) injury model. Sprague-Dawley rats received intraperitoneal injection of 50 mg/kg EGCG 48 h, 24 h, and 30 min prior to I/R injury. The animals were subjected to left renal occlusion for 45 min. EGCG treatment suppressed the peak in serum creatinine. EGCG-treated kidneys showed significantly less tubular damage and a decreased number of apoptotic cells. The I/R-induced elevation in the renal MDA level was significantly decreased in the EGCG group. Reverse-transcriptase polymerase chain reaction showed that EGCG significantly decreased the expression of MHC class II, TLR2, TLR4, MCP-1, IL-18, TGF-β1, procollagen Ia1, TIMP-1, and Kim-1. ED-1 staining showed reduced macrophage infiltration and α-SMA staining revealed less interstitial expression. Heme oxygenase-1 (HO-1) expression in I/R kidneys was upregulated in the EGCG group based on the results of both RT-PCR and Western blotting analysis. Blockade of HO-1 gene induction by SnPP increased renal tubular damage and macrophage infiltration. These findings suggest that EGCG protects the kidneys against I/R injury by reducing macrophage infiltration and decreasing renal fibrosis. These beneficial effects may be mediated, in part, by augmentation of the HO-1 gene.

Assessment of kidney organ quality and prediction of outcome at time of transplantation

The critical importance of donor organ quality, i.e., number of surviving nephrons, ability to withstand injury, and capacity for repair in determining short- and long-term outcomes is becoming increasingly clear. This review provides an overview of studies to assess donor kidney quality and subsequent transplant outcomes based on clinical pathology and transcriptome-based variables available at time of transplantation. Prediction scores using clinical variables function when applied to large data sets but perform poorly for the individual patient. Histopathology findings in pre-implantation or post-reperfusion biopsies help to assess structural integrity of the donor kidney, provide information on pre-existing donor disease, and can serve as a baseline for tracking changes over time. However, more validated approaches of analysis and prospective studies are needed to reduce the number of discarded organs, improve allocation, and allow prediction of outcomes. Molecular profiling detects changes not seen by morphology or captured by clinical markers. In particular, molecular profiles provide a quantitative measurement of inflammatory burden or immune activation and reflect coordinated changes in pathways associated with injury and repair. However, description of transcriptome patterns is not an end in itself. The identification of predictive gene sets and the application to an individualized patient management needs the integration of clinical and pathology-based variables, as well as more objective reference markers of transplant function, post-transplant events, and long-term outcomes.

Osteopontin Expressed in Tubular Epithelial Cells Regulates NK Cell-Mediated Kidney Ischemia Reperfusion Injury

Renal ischemia reperfusion injury (IRI) occurs after reduced renal blood flow and is a major cause of acute injury in both native and transplanted kidneys. Studies have shown diverse cell types in both the innate and the adaptive immune systems participate in kidney IRI as dendritic cells, macrophages, neutrophils, B cells, CD4+ NK+ cells, and CD4+ T cells all contribute to this form of injury. Recently, we have found that NK cells induce apoptosis in tubular epithelial cells (TECs) and also contribute to renal IRI. However, the mechanism of NK cell migration and activation during kidney IRI remains unknown. In this study, we have identified that kidney TECs express a high level of osteopontin (OPN) in vitro and in vivo. C57BL/6 OPN-deficient mice have reduced NK cell infiltration with less tissue damage compared with wild-type C57BL/6 mice after ischemia. OPN can directly activate NK cells to mediate TEC apoptotic death and can also regulate chemotaxis of NK cells to TECs. Taken together, our study’s results indicate that OPN expression by TECs is an important factor in initial inflammatory responses that involves NK cells activity in kidney IRI. Inhibiting OPN expression at an early stage of IRI may be protective and preserve kidney function after transplantation.

Effects of pretreatment with Yisheng injection on renal warm ischemia/reperfusion injury in mice

INTRODUCTION

Due to the organ supply shortage, the donor pool has been expanded to include non-heart-beating donors, where renal warm ischemia/reperfusion (I/R) injury is inevitable. This study was undertaken to determine whether Yisheng injection (YM) could attenuate renal warm I/R injury in mice.

MATERIALS AND METHODS

Male C57BL/6 mice were divided into sham, ischemic, and YM-treated groups using 50 minutes of left kidney ischemia. Mice were humanely killed at 4 or 24 hours postreperfusion. We assayed the effects of YM on liver functional injury, neutrophil recruitment, and proinflammatory mediators after renal I/R injury.

RESULTS

Renal I/R produced dramatic injuries in mouse kidneys. Administration of YM reduced liver function (urea nitrogen of untreated vs treated, 4.7 +/- 0.6 vs 26.6 +/- 1.5 mmol/L; P < .01) and histological injury (histological scores of untreated vs treated, 4.12 +/- 0.14 vs 0.98 +/- 0.07; P < .01). YM at doses of 5, 15, or 25 mg/kg reduced the serum levels of tumor necrosis factor-alpha (TNF-alpha) by about 32.9%, 55.1%, and 74.5%, respectively. Moreover, YM also suppressed the increase in messenger RNA (mRNA) and protein expressions of TNF-alpha and intercellular adhesion molecule-1 (ICAM-1), as well as abrogated neutrophil recruitment in a dose-dependent manner.

CONCLUSION

YM protects murine kidneys from warm I/R injury, probably via decreasing functional injury, reducing neutrophil infiltration, and suppressing the overexpression of proinflammatory mediators and adhesion molecules.

Ex vivo application of carbon monoxide in UW solution prevents transplant-induced renal ischemia/reperfusion injury in pigs

I/R injury is a major deleterious factor of successful kidney transplantation (KTx). Carbon monoxide (CO) is an endogenous gaseous regulatory molecule, and exogenously delivered CO in low concentrations provides potent cytoprotection. This study evaluated efficacies of CO exposure to excised kidney grafts to inhibit I/R injury in the pig KTx model. Porcine kidneys were stored for 48 h in control UW or UW supplemented with CO (CO-UW) and autotransplanted in a 14-day follow-up study. In the control UW group, animal survival was 80% (4/5) with peak serum creatinine levels of 12.0 +/- 5.1 mg/dL. CO-UW showed potent protection, and peak creatinine levels were reduced to 6.9 +/- 1.4 mg/dL with 100% (5/5) survival without any noticeable adverse event or abnormal COHb value. Control grafts at 14 days showed significant tubular damages, focal fibrotic changes and numerous infiltrates. The CO-UW group showed significantly less severe histopathological changes with less TGF-beta and p-Smad3 expression. Grafts in CO-UW also showed significantly lower early mRNA levels for proinflammatory cytokines and less lipid peroxidation. CO in UW provides significant protection against renal I/R injury in the porcine KTx model. Ex vivo exposure of kidney grafts to CO during cold storage may therefore be a safe strategy to reduce I/R injury.

N-octanoyl dopamine, a non-hemodyanic dopamine derivative, for cell protection during hypothermic organ preservation

Background

Although donor dopamine treatment reduces the requirement for post transplantation dialysis in renal transplant recipients, implementation of dopamine in donor management is hampered by its hemodynamic side-effects. Therefore novel dopamine derivatives lacking any hemodynamic actions and yet are more efficacious in protecting tissue from cold preservation injury are warranted. We hypothesized that variation of the molecular structure would yield more efficacious compounds avoid of any hemodynamic effects.

Methodology/Principal Findings

To this end, we assessed protection against cold preservation injury in HUVEC by the attenuation of lactate dehydrogenase (LDH) release. Modification of dopamine by an alkanoyl group increased cellular uptake and significantly improved efficacy of protection. Further variation revealed that only compounds bearing two hydroxy groups in ortho or para position at the benzene nucleus, i.e. strong reductants, were protective. However, other reducing agents like N-acetyl cysteine and ascorbate, or NADPH oxidase inhibition did not prevent cellular injury following cold storage. Unlike dopamine, a prototypic novel compound caused no hemodynamic side-effects.

Conclusions/Significance

In conclusion, we demonstrate that protection against cold preservation injury by catecholamines is exclusively governed by strong reducing capacity and sufficient lipophilicity. The novel dopamine derivatives might be of clinical relevance in donor pre-conditioning as they are completely devoid of hemodynamic action, their increased cellular uptake would reduce time of treatment and therefore also may have a potential use for non-heart beating donors.

Effects of metalloproteinase inhibition in a murine model of renal ischemia-reperfusion injury

Ischemia-reperfusion injury (IRI) is a leading cause of acute tubular necrosis (ATN) and delayed graft function in transplanted organs. Up-regulation of matrix metalloproteinases (MMPs) propagates the microinflammatory response that drives IRI. This study sought to determine the specific effects of Marimastat (Vernalis, BB-2516), a broad spectrum MMP and TNF-alpha-converting enzyme inhibitor, on IRI-induced ATN. Mice were pretreated with Marimastat or methylcellulose vehicle for 4 d before surgery. Renal pedicles were bilaterally occluded for 30 min and allowed to reperfuse for 24 h. Baseline creatinine levels were consistent between experimental groups; however, post-IRI creatinine levels were 4-fold higher in control mice (p < 0.0001). The mean difference between the post-IRI histology grades of Marimastat-treated and control kidneys was 1.57 (p = 0.003), demonstrating more severe damage to control kidneys. Post-IRI mean (+/-SEM) MMP-2 activity rose from baseline levels in control mice (3.62 +/- 0.99); however, pretreated mice presented only a slight increase in mean MMP-2 activity (1.57 +/- 0.72) (p < 0.001). In conclusion, these data demonstrate that MMP inhibition is associated with a reduction of IRI in a murine model.

Plasma and urine leukocyte elastase-alpha1protease inhibitor complex as a marker of early and long-term kidney graft function

BACKGROUND

Neutrophils are mediators of ischaemia/reperfusion (I/R) injury following kidney transplantation (kTx). Leukocyte elastase (LE) complex with alpha(1)protease inhibitor (LE-alpha(1)PI) is a marker of neutrophil degranulation. The aim of this study was to evaluate LE-alpha(1)PI as a marker of I/R kidney damage and to search for correlations between leukocyte activation and post-transplant complications.

METHODS

Plasma and urine LE-alpha(1)PI were estimated in 55 deceased-donor kidney graft recipients on postoperative days (POD) 1, 3 and 7, as well as in the late post-transplant period.

RESULTS

The plasma LE-alpha(1)PI level peaked on POD 1 after kTx, and the urine LE-alpha(1)PI peaked on POD 3. On POD 1 and POD 3, the urine LE-alpha(1)PI levels were higher in delayed graft function (DGF) patients than in patients with immediate graft function (IGF: P < 0.001 and P < 0.003, respectively). Urine LE-alpha(1)PI excretion on POD 1 was significantly higher in patients with longer cold ischaemia time (CIT) than in patients with shorter CIT, P < 0.002. Multivariate regression model revealed two factors influencing the occurrence of early acute rejection-urine LE-alpha(1)PI complex on POD 3 and human leukocyte antigen (HLA) mismatches. There was a significant association between the plasma LE-alpha(1)PI on POD 3 and serum creatinine level 6 and 12 months after kTx (r(2) 0.24; P < 0.005 and 0.19; P < 0.005, respectively).

CONCLUSIONS

This study is the first presentation of a simple, non-invasive measurement of neutrophil activation after kTx. It also demonstrates a strong correlation between the early post-transplant LE-alpha(1)PI complex level and kidney graft function.

Incidence and factors associated with delayed graft function in renal transplantation at Carlos Van Buren Hospital, January 2000 to June 2008

Delayed graft function (DGF) is defined as the need for dialysis within the first week after renal transplantation, and slow graft function as persistence of serum creatinine concentration of at least 3 mg/dL on day 5 after the procedure. In the present study, we analyzed the incidence and risk factors for DGF at our center. This retrospective study included 106 patients who underwent renal transplantation between January 2000 and June 2008. Of these, 11 patients were excluded. Two of the remaining 95 patients received organs from living donors, and 93 received cadaver organs. Variables analyzed included donor age, cause of death, cause of chronic renal failure, recipient age, method and time of long-term renal replacement therapy, residual diuresis, panel of reactive antibodies (PRA), HLA mismatch, sex compatibility, cold and warm ischemia times, biopsy-confirmed episodes of acute rejection, urine output in the operating room and in the first 24 hours after the procedure, and intraoperative induction therapy. Data were analyzed using the chi(2) and Fisher exact tests and analysis of variance, and are given as mean (SD) and frequency. Variables associated with DGF at univariate analysis (P < .05) were divided between risk factors and predictors of DGF for inclusion in logistic regression models. The incidence of DGF was 32.6%; slow graft function, 16.8%; and immediate graft function, 50.5%. Cold ischemia time longer than 20 hours (P = .02) and donor age (P = .008) were directly associated with DGF. Twenty-four-hour urine output was a strong predictor of DGF. Patients with DGF demonstrated a 25% incidence of an episode of acute rejection before discharge from the hospital. No difference in DGF was observed for use of intraoperative induction therapy.

Necrotic cells trigger a sterile inflammatory response through the Nlrp3 inflammasome

Dying cells are capable of activating the innate immune system and inducing a sterile inflammatory response. Here, we show that necrotic cells are sensed by the Nlrp3 inflammasome resulting in the subsequent release of the proinflammatory cytokine IL-1beta. Necrotic cells produced by pressure disruption, hypoxic injury, or complement-mediated damage were capable of activating the Nlrp3 inflammasome. Nlrp3 inflammasome activation was triggered in part through ATP produced by mitochondria released from damaged cells. Neutrophilic influx into the peritoneum in response to necrotic cells in vivo was also markedly diminished in the absence of Nlrp3. Nlrp3-deficiency moreover protected animals against mortality, renal dysfunction, and neutrophil influx in an in vivo renal ischemic acute tubular necrosis model. These findings suggest that the inhibition of Nlrp3 inflammasome activity can diminish the acute inflammation and damage associated with tissue injury.

Histidine-tryptophan-ketoglutarate (HTK) is associated with reduced graft survival of deceased donor kidney transplants

Single-center studies have reported equivalent outcomes of kidney allografts recovered with histidine-tryptophan-ketoglutarate (HTK) or University of Wisconsin (UW) solution. However, these studies were likely underpowered and often unadjusted, and multicenter studies have suggested HTK preservation might increase delayed graft function (DGF) and reduce graft survival of renal allografts. To further inform clinical practice, we analyzed the United Network for Organ Sharing (UNOS) database of deceased donor kidney transplants performed from July 2004 to February 2008 to determine if HTK (n = 5728) versus UW (n = 15 898) preservation impacted DGF or death-censored graft survival. On adjusted analyses, HTK preservation had no effect on DGF (odds ratio [OR] 0.99, p = 0.7) but was associated with an increased risk of death-censored graft loss (hazard ratio [HR] 1.20, p = 0.008). The detrimental effect of HTK was a relatively late one, with a strong association between HTK and subsequent graft loss in those surviving beyond 12 months (HR 1.43, p = 0.007). Interestingly, a much stronger effect was seen in African-American recipients (HR 1.55, p = 0.024) than in Caucasian recipients (HR 1.18, p = 0.5). Given recent studies that also demonstrate that HTK preservation reduces liver and pancreas allograft survival, we suggest that the use of HTK for abdominal organ recovery should be reconsidered.

Increased primary non-function in transplanted deceased-donor kidneys flushed with histidine-tryptophan-ketoglutarate solution

Histidine-Tryptophan-Ketoglutarate (HTK) solution is increasingly used to flush and preserve organ donor kidneys, with efficacy claimed equivalent to University of Wisconsin (UW) solution. We observed and reported increased graft pancreatitis in pancreata flushed with HTK solution, which prompted this review of transplanting HTK-flushed kidneys. We analyzed outcomes of deceased-donor kidneys flushed with HTK and UW solutions with a minimum of 12 months follow-up, excluding pediatric and multi-organ recipients. We evaluated patient and graft survival and rejection rates, variables that might constitute hazards to graft survival and renal function. Two-year patient survival, rejection, renal function and graft survival were not different, but early graft loss (<6 months) was worse in HTK-flushed kidneys (p < 0.03). A Cox analysis of donor grade, cold ischemic time, panel reactive antibodies (PRA), donor race, first vs. repeat transplant, rejection and flush solution showed that only HTK use predicted early graft loss (p < 0.04; relative risk = 3.24), almost exclusively attributable to primary non-function (HTK, n = 5 (6.30%); UW, n = 1 (0.65%); p = 0.02). Delayed graft function and early graft loss with HTK occurred only in lesser grade kidneys, suggesting it should be used with caution in marginal donors.

Chemokine-directed strategies to attenuate allograft rejection

A key event during T cell-mediated rejection of allografts is the trafficking of donor antigen-primed effector T cells from the lymphoid tissue to the graft. This trafficking is mediated in part by chemokine produced in the graftengaging receptors on the T cells and other graftinfiltrating leukocytes. The presence of specific sets of chemokines and chemokine receptors is detectable in rejecting allografts. In animal models, allograft rejection is delayed when chemokine-chemokine receptor function is absent or antagonized but cellular infiltration and graft survival eventually occur, suggesting that T cells and other leukocytes use several trafficking mechanisms during rejection. The use of chemokines as footprints of rejection may be of considerable value as noninvasive biomarkers in transplantation.

NK cells induce apoptosis in tubular epithelial cells and contribute to renal ischemia-reperfusion injury

Renal ischemia-reperfusion injury (IRI) can result in acute renal failure with mortality rates of 50% in severe cases. NK cells are important participants in early-stage innate immune responses. However, their role in renal tubular epithelial cell (TEC) injury in IRI is currently unknown. Our data indicate that NK cells can kill syngeneic TEC in vitro. Apoptotic death of TEC in vitro is associated with TEC expression of the NK cell ligand Rae-1, as well as NKG2D on NK cells. In vivo following IRI, there was increased expression of Rae-1 on TEC. FACS analyses of kidney cell preparations indicated a quantitative increase in NKG2D-bearing NK cells within the kidney following IRI. NK cell depletion in wild-type C57BL/6 mice was protective, while adoptive transfer of NK cells worsened injury in NK, T, and B cell-null Rag2(-/-)gamma(c)(-/-) mice with IRI. NK cell-mediated kidney injury was perforin (PFN)-dependent as PFN(-/-) NK cells had minimal capacity to kill TEC in vitro compared with NK cells from wild-type, FasL-deficient (gld), or IFN-gamma(-/-) mice. Taken together, these results demonstrate for the first time that NK cells can directly kill TEC and that NK cells contribute substantially to kidney IRI. NK cell killing may represent an important underrecognized mechanism of kidney injury in diverse forms of inflammation, including transplantation.

[Delayed graft function]

Delayed return to kidney function after transplantation is characterized essentially by acute ischemic tubular necrosis. It remains frequent and has no curative treatment. However, an induction treatment of antilymphocyte serum may reduce the delay in recuperation. In patients with delayed function, the maintenance immunosuppressive treatment should take into account the excessive risk of acute rejection over the short term and the more rapid deterioration of renal function over the long term. This means that biopsies to screen for acute rejection should be done systematically before the end of the 3rd month and anticalcineurin toxicity-sparing treatment should be considered, replacing anticalcineurins immediately with belatacept or after the 3-month acute period with proliferation signal inhibitors, if the kidney histology tests permit. In all cases, the classical measures of kidney protection remain indispensable.

The A20 gene protects kidneys from ischaemia/reperfusion injury by suppressing pro-inflammatory activation

Ischaemia followed by reperfusion (I/R) can induce inflammation and injury and is a risk factor for delayed graft function and rejection of transplanted kidneys. Inflammation is regulated by NF-kappaB transcription factors which induce pro-inflammatory molecules in endothelial cells (EC). We examined whether A20, a negative regulator of NF-kappaB, can protect kidneys from I/R injury. To mimic the fluctuations in endothelial oxygenation that occur during I/R we exposed cultured human umbilical vein EC (HUVEC) to hypoxia (1% O(2) for 4 h) followed by re-oxygenation (21% O(2) for 1 h-24 h). We observed transient expression of pro-inflammatory molecules (E-selectin, VCAM-1 and IL-8) and sustained expression of A20 in HUVEC exposed to hypoxia/re-oxygenation. The effect of A20 on endothelial responses to hypoxia/re-oxygenation was assessed. We observed that pre-treatment of HUVEC with an adenovirus containing A20 (Ad-A20) suppressed activation of NF-kappaB and induction of pro-inflammatory molecules by hypoxia/re-oxygenation, whereas a control adenovirus had little or no effect. Thus the induction of A20 may form a negative feedback loop in pro-inflammatory signalling in cells exposed to hypoxia/re-oxygenation. To validate our cell culture experiments we examined the role of A20 in renal responses to I/R. We observed that A20 was induced in rat kidneys exposed to I/R. Moreover, pre-treatment of animals with Ad-A20 significantly reduced acute tubular necrosis, renal expression of VCAM-1 and NF-kappaB activation in response to I/R, whereas pre-treatment with control adenovirus did not. Our observations suggest that A20 maintains physiological homeostasis in kidneys exposed to I/R by protecting them from inflammation and injury.

Potential influence of tacrolimus and steroid avoidance on early graft function in pediatric renal transplantation

With the increasing adoption of steroid-sparing immunosuppression protocols in renal transplantation, it is important to evaluate any adverse effects of steroid avoidance on graft function. Early graft function, measured by CrCl was retrospectively studied in 158 consecutive pediatric renal transplant recipients from 1996 to 2005, receiving either steroid-free or steroid-based immunosuppression. Patients receiving steroid-free immunosuppression vs. steroid-based immunosuppression had no difference change in CrCl (DeltaCrCl) in the first week post-transplantation (p = 0.12). When stratified by corticosteroid usage, patients with higher tacrolimus trough levels (> or =14 ng/mL) had slower graft function recovery in the first week post-transplantation than those with lower tacrolimus trough levels (p = 0.008) in the steroid-free group only. Despite initial slower graft function recovery in this subgroup, there was no negative impact on graft function in the steroid-free group; in fact steroid-free patients trended towards better CrCl at six months (p = 0.047) and 12 months (p < 0.001) post-transplant than the steroid-based group. With the improved immunological outcomes with steroid avoidance, close surveillance should be performed of tacrolimus levels to avoid levels >14 ng/mL. In patients with slow recovery of early graft function, short-term perioperative steroids may be considered.

Risk factors and consequences of delayed graft function in deceased donor renal transplant patients receiving antithymocyte globulin induction

BACKGROUND

Induction rabbit antithymocyte globulin (rATG) is largely used in renal allograft recipients at risk for delayed graft function (DGF) and immunologic rejection. The purpose of our study was to characterize risk factors and outcomes associated with DGF when it occurs in recipients undergoing routine rATG induction.

METHODS

We retrospectively reviewed our experience in a predominantly high-risk population receiving modern immunosuppressive regimens.

RESULTS

Of 231 deceased-donor transplants, high-risk characteristics included African American race (68%), retransplants (12%), peak panel reactive antibody of atleast 20% (19%), expanded criteria donor kidney (15%), and cold ischemia time exceeding 24 hr (27%). DGF occurred in 29% of patients. rATG was continued to a dose of 7.3 mg/kg in DGF patients and 5 mg/kg in non-DGF patients (P<0.0001). Risk factors for DGF were recipient body mass index greater than 30 kg/m(2) (odds ratio [OR]=1.5, P=0.02), female donor/male recipient pairings (OR=1.5, P=0.033), sirolimus use (OR=1.7, P=0.003), and donor creatinine more than 1.5 mg/dL (OR=1.6, P=0.016). One-year patient survival (99% non-DGF, 91% DGF; P=0.001) and acute rejection incidence through 36 months (11% non-DGF, 22.4% DGF; P=0.025) differed between groups. DGF patients experienced a higher rejection rate during the second and third years posttransplant. Death-censored graft survival was similar throughout 36 months.

CONCLUSION

In kidney transplantation with routine rATG induction, DGF was related to size and gender, donor creatinine, and immunosuppressive protocol. Despite low first-year rejection rates, DGF was associated with inferior patient survival. Importantly, patients with DGF continued to be at risk for rejection beyond the first year. Donor and recipient selection impacts short-term outcomes, and induction alone may not confer a long-term advantage without further modification of baseline therapy.

Acute tubular injury in protocol biopsies of renal grafts: prevalence, associated factors and effect on long-term function

Acute tubular injury (ATI) is commonly observed in renal allografts, especially early after transplantation. This study analyzes prevalence and associated clinical conditions of ATI in serial protocol biopsies (pBx) and indication biopsies (iBx), and its impact on long-term graft function. 612 pBx from 204 patients taken at 6 weeks, 3 and 6 months, and 151 iBx performed within the first year of transplantation were evaluated. Prevalence of ATI in pBx was 40% (6 weeks), 34% (3 months) and 37% (6 months), and 46% in iBx. ATI was associated with delayed graft function and prolonged cold ischemia time in pBx, and with acute rejections in iBx. The GFR at 1 and 2 years after transplantation correlated inversely with the frequency of ATI in both pBx and iBx (p < 0.001). Prevalence of chronic changes at 6 months was not significantly related to ATI (patients without ATI: 36%, patients with multiple ATI findings: 54%). ATI is linked to inferior long-term graft function. While this suggests lack of recovery from ATI with permanent allograft damage, the underlying molecular mechanisms need yet to be uncovered. Prevention of the potential pathogenetic factors identified in this study might be the key point to attain good long-term graft function.

A review of sonographic evaluation of renal transplant complications

In this article, we present an overview of renal transplantation with its complications and discuss the abilities and limitations of ultrasound in evaluating these complications. We included renal transplants performed at our institution between 1993 and 2006 and gathered data on more than 1,000 patients who developed graft dysfunction. We analyzed the ultrasound findings in different posttransplant complications and compared our findings with those in published literature. We present this review article that elaborates and categorizes various transplant complications from an ultrasound perspective. Based on imaging evaluation, the complications of renal transplantation can be divided into four major categories: peri-renal, renal parenchymal, renal collecting system, and renal vascular complications. Common complications included acute tubular necrosis, graft rejection, drug nephrotoxicity, hematoma, lymphocele, urinoma, hydronephrosis, and vascular complications. Ultrasound has a key role in identification and management of most of these complications. However, some parenchymal complications may only be diagnosed on renal biopsy. Ultrasound is a very powerful screening tool to assess renal transplant dysfunction and has a primary role in early diagnosis and management of structural and vascular complications, which may need surgical intervention to save the graft.

Systemic gene therapy with interleukin-13 attenuates renal ischemia-reperfusion injury

Ischemia-reperfusion injury is a leading cause of acute renal failure and a major determinant in the outcome of kidney transplantation. Here we explored systemic gene therapy with a modified adenovirus expressing Interleukin (IL)-13, a cytokine with strong anti-inflammatory and cytoprotective properties. When ischemia was induced we found that the IL-13 receptor is expressed in both the normal and experimental kidneys. Prior to the induction of ischemia, rats received adenovirus-IL-13, control adenovirus or saline. IL-13 plasma levels increased more than 50-fold in adenovirus-IL-13 treated animals, confirming successful IL-13 gene delivery. Histological analysis showed decreased tubular epithelial cell damage with adenovirus-IL-13 therapy, accompanied by reduced kidney injury molecule-1 expression. Interstitial infiltration by neutrophils and macrophages was reduced by half as was interstitial fibrosis and expression of alpha-smooth muscle actin. IL-13 treatment significantly diminished the expression of E-selectin, IL-8, MIP-2, TNF-alpha and MCP-1 mRNA. These results suggest that the use of systemic IL-13 gene therapy may be useful in reducing renal tubulointerstitial damage and inflammation caused by ischemia-reperfusion.

Comparison of Vasosol and University of Wisconsin solutions on early kidney function after 24 hours of cold ischemia in a canine autotransplantation model

INTRODUCTION

Ischemia/reperfusion (I/R) injury is a significant cause of graft dysfunction in donor kidney transplantation. It has been suggested that improvements in organ preservation solutions can ameliorate some of deleterious effects of I/R on the transplanted graft. We evaluated herein the influence of Vasosol (VAS), a solution that is designed to target specific pathways of I/R injury, and University of Wisconsin (UW) solution on early graft status of donor kidneys in a canine autotransplant model.

MATERIALS AND METHODS

Left kidneys were recovered from 12 dogs, exsanguinated with either VAS or UW and cooled to 4 degrees C for 24 h. Kidneys were autotransplanted and the right kidneys were nephrectomized. Indices of post-transplant renal function were measured serially for seven days. All animals were euthanized at postoperative day 7. Kidney biopsies were taken at 1, 4, and 24 h postreperfusion for evaluation of tissue myeloperoxidase concentration.

RESULTS

All dogs survived the transplant surgery. Post-transplant serum creatinine (mg/dL) and blood urea nitrogen (mg/dL) were significantly elevated in the UW group compared with the VAS group in each of the postoperative days. Moreover, myeloperoxidase tissue levels were significantly elevated in the UW-treated group compared with the VAS-treated group.

CONCLUSIONS

Our data suggest that a cold storage preserving solution designed to target several modes of I/R injury can improve the function of the autotransplanted canine kidney compared with the current gold standard solution.

Participation of autophagy in renal ischemia/reperfusion injury

Renal ischemia-reperfusion (I/R) injury is inevitable in transplantation, and it results in renal tubular epithelial cells undergoing cell death. We observed an increase in autophagosomes in the tubular epithelial cells of I/R-injured mouse models, and in biopsy specimens from human transplanted kidney. However, it remains unclear whether autophagy functions as a protective pathway, or contributes to I/R-induced cell death. Here, we employed the human renal proximal tubular epithelial cell line HK-2 in order to explore the role of autophagy under hypoxia (1% O(2)) or activation of reactive oxygen species (500 microM H(2)O(2)). When compared to normoxic conditions, 48h of hypoxia slightly increased LC3-labeled autophagic vacuoles and markedly increased LAMP2-labeled lysosomes. We observed similar changes in the mouse IR-injury model. We then assessed autophagic generation and degradation by inhibiting the downstream lysosomal degradation of autophagic vacuoles using lysosomal protease inhibitor. We found that autophagosomes increased markedly under hypoxia in the presence of lysosomal protease inhibitors, thus suggesting that hypoxia induces high turnover of autophagic generation and degradation. Furthermore, inhibition of autophagy significantly inhibited H(2)O(2)-induced cell death. In conclusion, high turnover of autophagy may lead to autophagic cell death during I/R injury.

HGF–MSP chimera protects kidneys from ischemia–reperfusion injury

Renal ischemia-reperfusion (I/R) injury is inevitable in transplantation and is related to long-term graft function. MF-1, a bifunctional hepatocyte growth factor (HGF)-macrophage-stimulating protein (MSP) (HGF-MSP) chimera was recently reported to prevent apoptosis. We therefore hypothesized that treatment with MF-1 would protect kidneys from I/R injury by inhibiting tubular epithelial apoptosis. MF-1 directly guarded cultured proximal tubular epithelial cells from hypoxia-induced necrosis and apoptosis in vitro. In addition, the therapeutic effects of MF-1 were evaluated using a rat I/R injury model in vivo. Saline-treated kidneys had increased creatinine and BUN, and exhibited tubular epithelial apoptosis with activated caspase 3 expression. In contrast, MF-1 treatment up-regulated Akt phosphorylation, and inhibited caspase 3 activation and tubular apoptosis, thereby ameliorating renal dysfunction. Of particular interest is that macrophage infiltration was suppressed in the MF-1-treated kidney. In conclusion, we identified a novel therapeutic approach using MF-1 to protect kidneys from I/R injury.

Atorvastatin Donor Pretreatment Prevents Ischemia/Reperfusion Injury in Renal Transplantation in Rats: Possible Role for Aldose-Reductase Inhibition

BACKGROUND

The aim of the present study was to evaluate the effect of donor pretreatment with atorvastatin on ischemia/reperfusion (I/R) injury in renal transplantation in rats.

METHODS

Donor rats were pretreated orally with atorvastatin or vehicle 2 days prior to explantation. Kidneys were stored for 24 hr at 4 degrees C in University of Wisconsin solution and transplanted into isogeneic or allogeneic recipients.

RESULTS

Donor treatment with atorvastatin improved initial graft function, reduced renal inflammation, and the number of TUNEL-positive cells in renal tissue after prolonged cold storage and isogeneic transplantation. In the allogeneic transplantation model, donor treatment with atorvastatin reduced renal inflammation in grafts harvested after 5 days, but no improvement of long-term graft survival (24 weeks) could be observed. A genome wide gene expression profile of donor kidneys from atorvastatin treated or vehicle treated rats revealed a fivefold downregulation of aldose reductase in all atorvastatin treated animals (P<0.01). Donor treatment with an aldose-reductase inhibitor improved kidney function and reduced renal inflammation after prolonged cold storage and isogeneic transplantation.

CONCLUSION

Our data suggest that downregulation of aldose reductase in renal tissue might underlie the protective effect of donor atorvastatin treatment. Donor pretreatment with a statin or an aldose reductase inhibitor could offer a new treatment strategy to prevent transplantation associated tissue injury.

Novel pharmacological approaches to the treatment of renal ischemia-reperfusion injury: a comprehensive review

Renal ischemia-reperfusion (I-R) contributes to the development of ischemic acute renal failure (ARF). Multi-factorial processes are involved in the development and progression of renal I-R injury with the generation of reactive oxygen species, nitric oxide and peroxynitrite, and the decline of antioxidant protection playing major roles, leading to dysfunction, injury, and death of the cells of the kidney. Renal inflammation, involving cytokine/adhesion molecule cascades with recruitment, activation, and diapedesis of circulating leukocytes is also implicated. Clinically, renal I-R occurs in a variety of medical and surgical settings and is responsible for the development of acute tubular necrosis (a characteristic feature of ischemic ARF), e.g., in renal transplantation where I-R of the kidney directly influences graft and patient survival. The cellular mechanisms involved in the development of renal I-R injury have been targeted by several pharmacological interventions. However, although showing promise in experimental models of renal I-R injury and ischemic ARF, they have not proved successful in the clinical setting (e.g., atrial natriuretic peptide, low-dose dopamine). This review highlights recent pharmacological developments, which have shown particular promise against experimental renal I-R injury and ischemic ARF, including novel antioxidants and antioxidant enzyme mimetics, nitric oxide and nitric oxide synthase inhibitors, erythropoietin, peroxisome-proliferator-activated receptor agonists, inhibitors of poly(ADP-ribose) polymerase, carbon monoxide-releasing molecules, statins, and adenosine. Novel approaches such as recent research involving combination therapies and the potential of non-pharmacological strategies are also considered.

Erythropoietin protects the kidneys against ischemia reperfusion injury by activating hypoxia inducible factor-1alpha

BACKGROUND

Ischemia/reperfusion (I/R) injury is closely associated with tissue damage in various organs, as well as in kidney transplants. Erythropoietin (EPO) has been shown to have a cytoprotective effect against hypoxia. We examined the effect of EPO against renal I/R injury and the underlying mechanism.

METHODS

Human umbilical vein endothelial cells and human renal proximal tubular epithelial cells were cultured under hypoxic conditions with various EPO concentrations at 37 degrees C and examined the mechanism of cell proliferation by EPO. Moreover, to demonstrate the renoprotective effect in vivo, we treated Sprague-Dawley rats with 100 IU/kg EPO every 2 days for 2 weeks (a total of 6 doses). One day after the last injection, the operations to produce renal I/R injury (bilateral renal occlusion for 60 min) were done, and rats were killed at the end of the reperfusion period (24 hr and 72 hr after reperfusion began).

RESULTS

First, we demonstrated in vitro that EPO increased hypoxia inducible factor-1alpha (HIF-1alpha) expression and stimulated proliferation of both cells under hypoxic conditions. Next, we demonstrated in vivo that EPO treatment increased the number of HIF-1alpha-positive cells, and markedly induced the expression of vascular endothelial growth factor messenger RNA. Using pimonidazole, a molecular probe that detects hypoxia, we found that EPO markedly attenuated tubular hypoxia, and reduced the number of terminal transferase dUTP nick end labeling-positive apoptotic cells and alpha-smooth muscle actin-positive interstitial cells.

CONCLUSIONS

We suggested a novel HIF-1alpha induction pathway by EPO under hypoxic conditions. Thus, EPO may protect the kidneys against ischemia reperfusion injury by activating HIF-1alpha.

Renal function with delayed or immediate cyclosporine microemulsion in combination with enteric-coated mycophenolate sodium and steroids: results of follow up to 30 months post-transplant

BACKGROUND

In the multicenter, open-label Myriade study, renal transplant patients were randomized to early cyclosporine microemulsion (CsA-ME, day 0) or delayed CsA-ME (day 6) with enteric-coated mycophenolate sodium (EC-MPS), steroids and interleukin-2 receptor induction. One-yr results have been published previously. We now report the results of an extension study in which patients were followed up for a period of three yr post-transplant.

METHODS

All patients completing the one-yr core study on-treatment were eligible to enter the extension study.

RESULTS

Of the 203 patients, 153 completed the core trial on-treatment; 144 (94%) entered the extension study with a minimum follow-up of one yr (73 early CsA-ME, 71 delayed CsA-ME). In 75% of patients receiving EC-MPS during the extension, the recommended dose was administered (1440 mg/d). Median creatinine clearance remained constant (57 mL/min) at 12, 24 and 30 months post-transplant and was similar in the early and delayed CsA-ME groups as well as in subpopulations with or without delayed graft function. One patient in the early CsA-ME group died. No grafts were lost. The incidence of BPAR from time of transplant to the end of the extension study was 17% (24/139). Seven patients (5%) discontinued the extension study prematurely because of adverse events.

CONCLUSION

These results suggest that a regimen of CsA-ME, EC-MPS and steroids results in excellent survival rates with stable renal function over a mean follow-up of 30 months. Immediate introduction of CsA-ME has no deleterious effect on long-term renal function, even among patients with delayed graft function.

A role for HO-1 in renal function impairment in animals subjected to ischemic and reperfusion injury and treated with immunosuppressive drugs

INTRODUCTION

Ischemia/reperfusion injury (IRI) represents the single major antigen-independent factor implicated in pathogenesis of chronic graft dysfunction. Tacrolimus is a calcineurin inhibitor, which has been suggested to be helpful in cyclosporine-related chronic toxicity. Rapamycin has antiproliferative properties that may impair renal regeneration after IRI. Therefore, immunosuppressive drugs might impair renal graft outcome in those organs suffering IRI.

MATERIAL AND METHODS

C57B1/6 male mice subjected to 45 minutes of renal pedicle ligation were reperfused for 24 hours. Mice were treated with rapamycin, cyclosporine, or tacrolimus. Blood and renal tissue samples were collected at 24 hours after IRI. Urea levels were measured. Heme Oxygenase 1 (HO-1) gene transcript was amplified by a real-time polymerase chain reaction technique.

RESULTS

Animals treated with cyclosporine and subjected to IRI showed impaired renal function that peaked at 24 hours. Additional pretreatment with rapamycin produced even more impairment of renal function, when compared with controls. However, tacrolimus pretreatment was associated with a better renal outcome. HO-1 expression was upregulated after IRI by 2.6 arbitrary units at 24 hours. Rapamycin showed worse impairment of renal function.

CONCLUSION

Tacrolimus was not associated with worsening renal function when compared with animals just subjected to IRI. Upregulation of HO-1 may be an attractive approach to limit graft injury.

Multicenter analysis of kidney preservation

BACKGROUND

Kidney preservation is an integral part of clinical kidney transplantation. Changes in the use of preservation methods and storage solutions, ischemic preservation times, and the relationship between ischemia time and human leukocyte antigen (HLA) match have not been extensively studied in recent years.

METHODS

The Collaborative Transplant Study database was used to analyze effects of kidney preservation methods and times. Graft survival and death-censored functional survival were used as endpoints. In all, 91,674 transplants from deceased donors were analyzed using univariate and multivariate methods.

RESULTS

Cold storage accounted for more than 95% of kidney preservations from 1990-2005. Increasing ischemia up to 18 hr was not detrimental for graft outcome, whereas the risk of graft failure rose with ischemia 19-24 hr to relative risk (RR) 1.09, 25-36 hr to RR 1.16, and >36 hr to RR 1.30 (P<0.001). As compared to other preservation solutions, University of Wisconsin (UW) solution was associated with significantly better outcome when ischemia exceeded 24 hr. Short ischemia did not eliminate the effect of HLA matching. Kidneys from young or old donors were affected by prolonged ischemia to similar degrees. Pulsatile machine perfusion was not superior to cold storage.

CONCLUSION

Kidneys from deceased donors should ideally be transplanted within 18 hr. Within the 18-hr window, the time of ischemia has no significant influence on graft survival. UW solution should be used if preservation for longer periods is envisioned. HLA matching improves graft survival regardless of length of ischemia.

Intraoperative Blood Flow Measurements in Organ Allografts Can Predict Postoperative Function

A reliable method to recognize the extent of ischemia/reperfusion injury in transplantation is needed in order to tailor the immunosuppressive scheme to the needs of a damaged organ. This study sought to assess the correlation between the total and the parenchymal blood flow into a transplanted kidney (n = 71) or liver (n = 15) shortly after revascularization with the early function of the organ after transplantation. The total blood flow in the renal artery in kidney recipients or in the hepatic artery and portal vein in liver recipients was measured by an electromagnetic flowmeter. The parenchymal blood flow (in several parts of the transplanted organ) was assessed using a laser-Doppler flowmeter. Two measurements were always taken after revascularization (5 to 60 minutes apart). Vascular resistance (VR) as calculated by the difference between the mean arterial pressure (MAP) and the central venous pressure (CVP) was correlated with immediate kidney or liver function parameters. Neither total renal blood flow (RBF) nor VR was different between the immediate function (IF) and delayed graft function (DGF) groups of kidney transplant patients. However, the cortical (parenchymal) blood flow was significantly greater in the IF than the DGF group at 5 minutes: 29.98 +/- 6.13 mL/min/100 g vs 23.56 +/- 6.46 mL/min/100 g (P < .001). The difference was even more significant at 35 minutes: 33.94 +/- 7.47 mL/min/100 g vs 15.47 +/- 3.34 mL/min/100 g (P < .0001). Among liver transplant patients, the results suggested a correlation between hepatic arterial blood flow and early graft viability and function. The most reliable predictor of early graft function was the portal blood flow, which correlated with the volume of secreted bile as well as the bilirubin, and transaminase levels and coagulation profile. Further studies must confirm the value of measurements of total and parenchymal blood flow in organ transplant recipients.

The Role of Immunosuppressive Drugs in Aggravating Renal Ischemia and Reperfusion Injury

Renal ischemia followed by reperfusion leads to acute renal failure in both native kidneys and renal allografts. Cyclosporine has known nephrotoxic effects. Thus, cyclosporine therapy subsequent to ischemia/reperfusion (I/R) injury may further exacerbate graft dysfunction. Rapamycin is a newer agent that suppresses the immune system by a different mechanism. In the present study, the effects of Cyclosporine and rapamycin at low and higher concentrations were investigated in an I/R-induced injury model.

METHODS

Cyclosporine (100 mg/kg or 50 mg/kg), rapamycin (3 mg/kg per day or 1.5 mg/kg), or both were administered to mice before being subjected to 45 minutes of ischemia. Blood and kidney samples were collected at 24, 48, and 120 hours after surgery. We quantified acute tubular necrosis and tubular regeneration.

RESULTS

Animals subjected to I/R showed impaired renal function that peaked at 24 hours (2.05 +/- 0.23 mg/dL), decreasing thereafter. Treatment with higher concentrations of cyclosporine or rapamycin caused even more renal dysfunction at 48 hours, which was sustained up to 120 hours after reperfusion (1.53 +/- 0.6 mg/dL), when compared to the low concentrations of cyclosporine or rapamycin (1.08 +/- 0.19 mg/dL; 0.99 +/- 0.14 mg/dL, P < .05, respectively). Cyclosporine delayed tubular regeneration, which was higher in controls at day 5 (67.0% vs 37.6%, P < .05).

CONCLUSIONS

These results demonstrated that cyclosporine or rapamycin might further aggravate ischemically injured organs, negatively affecting posttransplantation recovery in a concentration-dependent fashion.

Glutamine donor pretreatment in rat kidney transplants with severe preservation reperfusion injury

BACKGROUND

Glutamine (GLN) has been shown to confer cytoprotection by enhancing endogenous heat shock protein (HSP) expression. We hypothesized that GLN donor pretreatment protects rat renal grafts against severe preservation reperfusion injury (PRI).

MATERIALS AND METHODS

GLN (0.75 g/kg) or saline was administered i.p. to male donor rats 24 h and 6 h before donor nephrectomy. Kidneys (n = 6/group) were cold-stored in UW solution for 40 h and transplanted into bilaterally nephrectomized syngeneic recipients. Grafts were removed after 24 h. Renal HSP 70 expression was determined by Western blotting. Graft function was assessed by serum creatinine. Renal cross sections were microscopically examined for acute tubular necrosis, apoptosis, tubular proliferation, and macrophage infiltration.

RESULTS

GLN donor pretreatment significantly increased intragraft HSP 70 expression. Serum creatinine was not different between groups: 2.6 +/- 0.2 mg/dL (saline) versus 2.7 +/- 0.5 mg/dL (GLN). Both treatment groups showed severe tubular damage with significantly less papillary necrosis in the GLN group (P < 0.05). GLN significantly reduced the number of apoptotic tubular cells in the cortex, medulla, and papilla (P < 0.001 versus saline). Postinjury tubular proliferation, measured by PCNA antigen expression, and intragraft macrophage infiltration was not influenced by GLN.

CONCLUSIONS

In rat renal grafts suffering severe PRI pharmacological preconditioning with GLN attenuates early structural damage, especially tubular cell apoptosis. Stimulation of renal HSP 70 expression could be an important mechanism of GLN-induced cytoprotection. Our findings may have implications for the treatment of delayed graft function in recipients of marginal donor kidneys.

Rabbit antithymocyte globulin induction therapy in adult renal transplantation

Rabbit antithymocyte globulin (rATG) and horse antithymocyte globulin (horse ATG) are the polyclonal antithymocyte agents available for use in solid organ transplantation in the United States. Horse ATG is indicated for induction immunosuppression and for treatment of acute rejection episodes after kidney transplantation; rATG is indicated for treatment of acute rejection only. However, rATG is commonly used in clinical practice as an induction immunosuppressive agent, instigating many questions regarding appropriate dosing, tolerability, safety, and efficacy. Available evidence supports the use of rATG as an induction agent in adult renal transplant recipients. The use of this product for induction therapy has been studied in conjunction with a full-dose, triple-therapy maintenance regimen (sequential quadruple immunosuppression) consisting of a calcineurin inhibitor, an antimetabolite, and corticosteroids. Rabbit ATG has a proven safety and efficacy profile both as treatment of acute rejection and as induction therapy in patients undergoing kidney transplantation. The most common adverse events associated with rATG are cytokine release syndrome, thrombocytopenia, and lymphopenia. Results of early studies showed an increased rate of cytomegalovirus disease associated with rATG treatment, but recent studies indicate that routine administration of modern antiviral prophylaxis can reduce this risk. Current practice with rATG is evolving to minimize lifelong exposure to calcineurin inhibitors and corticosteroids.

Heme oxygenase 1 and renal ischemia and reperfusion injury: The impact of immunosuppressive drug

This study was undertaken to investigate the involvement of cyclooxygenase-2 (COX-2) in allergic nasal inflammation in actively sensitized rats. An allergic rhinitis model was developed by the repeated topical application of antigen into the nasal cavities in the sensitized rats. The severity of allergic rhinitis was studied by measuring the nasal behavior, as well as electroencephalogram (EEG) activity by antigen challenge. The electrodes were implanted chronically into the bilateral olfactory bulb of the rats and the EEG was measured monopolarly with an electroencephalograph (EEG, Nohon Kohden, Japan). The intranasal application of antigen caused the increase of nasal allergic signs as well as an EEG spike in a dose-dependent fashion, and at a dose of 50 microg/site, it showed a significant effect. The responses induced by the antigen were evaluated with certain drugs, etodolac (a selective COX-2 inhibitor), indomethacin (a non-selective COX inhibitor), ramatroban (a thromboxane A2 receptor antagonist) and zafirlukast (a cys-leukotriene receptor antagonist). Etodolac showed the inhibition of nasal behavior and EEG spike in a dose-related fashion, and at doses of 3 and 10 mg/kg, it showed a significant effect. Moreover, ramatroban also caused the dose-related inhibition of nasal behavior and EEG spike induced by antigen. On the other hand, both indomethacin and zafirlukast had no effects on the responses induced by antigen, even at a higher dose. Therefore, it can be concluded that cyclooxygenase-2 actively participates in the allergic nasal inflammation in actively sensitized rats.

Rabbit antithymocyte globulin versus basiliximab in renal transplantation

BACKGROUND

Induction therapy reduces the frequency of acute rejection and delayed graft function after transplantation. A rabbit antithymocyte polyclonal antibody or basiliximab, an interleukin-2 receptor monoclonal antibody, is most commonly used for induction.

METHODS

In this prospective, randomized, international study, we compared short courses of antithymocyte globulin and basiliximab in patients at high risk for acute rejection or delayed graft function who received a renal transplant from a deceased donor. Patients taking cyclosporine, mycophenolate mofetil, and prednisone were randomly assigned to receive either rabbit antithymocyte globulin (1.5 mg per kilogram of body weight daily, 141 patients) during transplantation (day 0) and on days 1 through 4 or basiliximab (20 mg, 137 patients) on days 0 and 4. The primary end point was a composite of acute rejection, delayed graft function, graft loss, and death.

RESULTS

At 12 months, the incidence of the composite end point was similar in the two groups (P=0.34). The antithymocyte globulin group, as compared with the basiliximab group, had lower incidences of acute rejection (15.6% vs. 25.5%, P=0.02) and of acute rejection that required treatment with antibody (1.4% vs. 8.0%, P=0.005). The antithymocyte globulin group and the basiliximab group had similar incidences of graft loss (9.2% and 10.2%, respectively), delayed graft function (40.4% and 44.5%), and death (4.3% and 4.4%). Though the incidences of all adverse events, serious adverse events, and cancers were also similar between the two groups, patients receiving antithymocyte globulin had a greater incidence of infection (85.8% vs. 75.2%, P=0.03) but a lower incidence of cytomegalovirus disease (7.8% vs. 17.5%, P=0.02).

CONCLUSIONS

Among patients at high risk for acute rejection or delayed graft function who received a renal transplant from a deceased donor, induction therapy consisting of a 5-day course of antithymocyte globulin, as compared with basiliximab, reduced the incidence and severity of acute rejection but not the incidence of delayed graft function. Patient and graft survival were similar in the two groups. (ClinicalTrials.gov number, NCT00235300 [ClinicalTrials.gov].).

The role of heme oxygenase 1 in rapamycin-induced renal dysfunction after ischemia and reperfusion injury

Ischemia and reperfusion injury (IRI) is the main etiology of acute renal failure in native and transplanted kidneys. In the transplantation field, immunosuppressive drugs may play an additional role in acute graft dysfunction. Rapamycin may impair renal regeneration post IRI. Heme oxygenase 1 (HO-1) is a protective gene with anti-inflammatory and anti-apoptotic actions. We investigated whether HO-1 played a role in rapamycin-induced renal dysfunction in an established model of IRI. Rapamycin (3 mg/kg) was administered to mice before being subjected to 45 min of ischemia. Animals subjected to IRI presented with impaired renal function that peaked at 24 h (2.05+/-0.23 mg/dl), decreasing thereafter. Treatment with rapamycin caused even more renal dysfunctions (2.30+/-0.33 mg/dl), sustained up to 120 h after reperfusion (1.54+/-0.4 mg/dl), when compared to the control (0.63+/-0.09 mg/dl, P<0.05). Rapamycin delayed tubular regeneration that was normally higher in the control group at day 5 (68.53+/-2.30 vs 43.63+/-3.11%, P<0.05). HO-1 was markedly upregulated after IRI and its expression was even enhanced by rapamycin (1.32-fold). However, prior induction of HO-1 by cobalt protoporphyrin improved the renal dysfunction imposed by rapamycin, mostly at later time points. These results demonstrated that rapamycin used in ischemic-injured organs could also negatively affect post-transplantation recovery. Modulation of HO-1 expression may represent a feasible approach to limit rapamycin acute toxicity.

Renal ischemia-reperfusion injury: new implications of dendritic cell-endothelial cell interactions

In renal ischemia/reperfusion (I/R) injury endothelial cells are a main target. The disturbance of endothelial cell physiology leads to endothelial swelling and narrowing of the blood vessel lumen. We attribute this effect to impairment of endothelial cell nitric oxide synthase (NOS). NO is significantly reduced in the course of hypoxia causing dysfunction of the vascular smooth muscle tone. Subsequently to an I/R injury, the inflammatory response results in endothelial activation with enhanced dendritic cell (DC) adhesion and migration. Thus, alloreactive leukocytes are recruited to the inflammatory site. Finally, dendritic cell-endothelial cell interactions may play a crucial role in antigen-specific allograft rejection in I/R renal injury. DCs, which activate naïve alloreactive T cells, play a central role in the establishment of alloantigen-specific immunity. In the course of hypoxia rejection is initiated at the activated layer of foreign endothelial cells (EC), which forms an immunogenic barrier for migrating DCs and T cells. Host DCs that bind to postischemic activated ECs invade the allografted tissues, or remain stationary in the subendothelial layer, or transmigrate into lymphoid vessels and secondary lymphoid organs, where they present alloantigens to naïve host T cells. Organ rejection is mediated by host alloreactive T cells, which are activated by donor DCs (direct activation) or host DCs (indirect activation). We hypothesized that DC-EC binding and migration is the first step in the renal I/R injury that mediates allotransplant rejection. We sought to better understand the downstream events of a renal I/R injury by understanding DC binding and migration, thereby seeking new strategies for more specific immunomodulatory interventions. Herein we developed a new allotransplant-rejection model after renal I/R injury.