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

Evaluation of Oxidative Stress and Metabolic Profile in a Preclinical Kidney Transplantation Model According to Different Preservation Modalities

This study addresses a joint nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectroscopy approach to provide a platform for dynamic assessment of kidney viability and metabolism. On porcine kidney models, ROS production, oxidative damage kinetics, and metabolic changes occurring both during the period between organ retrieval and implantation and after kidney graft were examined. The 1H-NMR metabolic profile—valine, alanine, acetate, trimetylamine-N-oxide, glutathione, lactate, and the EPR oxidative stress—resulting from ischemia/reperfusion injury after preservation (8 h) by static cold storage (SCS) and ex vivo machine perfusion (HMP) methods were monitored. The functional recovery after transplantation (14 days) was evaluated by serum creatinine (SCr), oxidative stress (ROS), and damage (thiobarbituric-acid-reactive substances and protein carbonyl enzymatic) assessments. At 8 h of preservation storage, a significantly (p < 0.0001) higher ROS production was measured in the SCS vs. HMP group. Significantly higher concentration data (p < 0.05−0.0001) in HMP vs. SCS for all the monitored metabolites were found as well. The HMP group showed a better function recovery. The comparison of the areas under the SCr curves (AUC) returned a significantly smaller (−12.5 %) AUC in the HMP vs. SCS. EPR-ROS concentration (μmol·g−1) from bioptic kidney tissue samples were significantly lower in HMP vs. SCS. The same result was found for the NMR monitored metabolites: lactate: −59.76%, alanine: −43.17%; valine: −58.56%; and TMAO: −77.96%. No changes were observed in either group under light microscopy. In conclusion, a better and more rapid normalization of oxidative stress and functional recovery after transplantation were observed by HMP utilization.

Role of Fractalkine-CX3CR1 Axis in Acute Rejection of Mouse Heart Allografts Subjected to Ischemia Reperfusion Injury

Transplantation outcomes are affected by the increase in rejection associated with ischemia reperfusion injury (IRI). Fractalkine (FKN), a chemokine for recruitment of CX3CR1⁺ leukocytes, contributes to the pathogenesis of various inflammatory diseases. Herein, we evaluated the importance of the FKN-CX3CR1 axis during IRI-related rejections using a mouse heterotopic heart transplantation model. FKN expression and graft survival was compared between wild-type C57BL/6 recipients transplanted with BALB/c hearts preserved for 8 (WT-IRI) and 0.5 h (WT-control) at 4°C. Graft survival of WT-IRI was shorter than that of WT-control. FKN was expressed on the vascular endothelium in WT-IRI allografts, but minimally in WT-control. The role of the FKN-CX3CR1 axis in IRI-related rejection was directly investigated using the transplant model with CX3CR1-deficient recipients (CX3CR1 KO-IRI) or treatment with anti-mouse FKN monoclonal antibodies. Graft survival of CX3CR1 KO-IRI was longer than that of WT-IRI; antibody treatment prolonged graft survival. The contribution of CX3CR1⁺ monocytes to IRI-related rejection was evaluated by adoptive transfer to CX3CR1 KO-IRI. Adoptive transfer of CX3CR1⁺ monocytes attenuated the effect of prolonged graft survival in CX3CR1 KO-IRI. Overall, the FKN-CX3CR1 axis plays a major role during IRI-related rejection; its blockade has the potential to improve the outcomes of deceased donor transplantation.

Association of endothelial dysfunction with sarcopenia and muscle function in a relatively young cohort of kidney transplant recipients

Background

Sarcopenia and endothelial dysfunction are both common among kidney transplant (KT) recipients. We aimed to evaluate the association between endothelial dysfunction and sarcopenia, as well as its individual components.

Methods

Vascular reactivity index (VRI), skeletal muscle index (SMI = skeletal muscle mass/height²), handgrip strength (HGS), and 6-meter usual gait speed (GS) were measured in 95 KT recipients. Low SMI was defined as SMI less than 10% of the sex-specific reference values from Chinese adults; low HGS as HGS < 28 kg for men and < 18 kg for women; slow GS as GS below 1.0 m/s. Sarcopenia was diagnosed based on the presence of low SMI as an essential criterion, accompanied by either low HGS or slow GS. Vascular reactivity was classified as being indicative of poor (VRI < 1.0), intermediate (1.0 ≤ VRI < 2.0), or good (VRI ≥ 2.0) vascular reactivity.

Results

Of the 95 patients, aged 45.2 ± 10.9 years, 11.6% had sarcopenia and 13.7% had poor vascular reactivity. Patients with sarcopenia were lower in body mass index (p = 0.001) and VRI (p = 0.041), and have a higher proportion of low muscle mass (p < 0.001), low HGS (p < 0.001), and slow GS (p = 0.001). Patients with poor vascular reactivity have a higher proportion of sarcopenia (p = 0.005), low HGS (p = 0.006), and slow GS (p = 0.029). Multivariate logistic regression analysis showed that patients in the poor VRI group were significantly associated with sarcopenia (odds ratio, OR = 6.17; 95% confidence interval [1.06-36.04]; p = 0.043), comparing to those with good VRI. We further analysed the effects of VRI on individual components of sarcopenia and found that VRI predicted slow GS significantly (OR = 0.41; 95% CI = [0.21-0.79]; p = 0.007), but not low SMI (OR = 1.15; 95% CI [0.53-2.49]; p = 0.718) and HGS (OR = 0.59; 95% CI [0.31-1.16]; p = 0.125).

Conclusions

We concluded that endothelial dysfunction is a key determinant of sarcopenia in KT recipients. Furthermore, endothelial dysfunction is more closely related to gait speed than muscle mass and strength.

Mitochondrial DNA may act as a biomarker to predict donor-kidney quality

Kidney transplantation is the best therapy for end-stage renal disease. Demand for kidney transplantation rises year-on-year, and the gap between kidney supply and demand remains large. To meet this clinical need, a gradual expansion in the supply of donors is required. However, clinics lack appropriate tools capable of quickly and accurately predicting post-transplant renal allograft function, and thus assess donor-kidney quality before transplantation. Mitochondrial DNA (mtDNA) is a key component of damage-associated molecular patterns (DAMPs) and plays an important part in ischemia-reperfusion injury (IRI), accelerating the progression of IRI by inducing inflammation and type I interferon responses. mtDNA is known to be closely involved in delayed graft function (DGF) and acute kidney injury (AKI) after transplantation. Thus, mtDNA is a potential biomarker able to predict post-transplant renal allograft function. This review summarizes mtDNA biology, the role mtDNA plays in renal transplantation, outlines advances in detecting mtDNA, and details mtDNA's able to predict post-transplant renal allograft function. We aim to elucidate the potential value of mtDNA as a biomarker in the prediction of IRI, and eventually provide help for predicting donor-kidney quality.

Preservation of pancreas in the University of Wisconsin solution supplemented with AP39 reduces reactive oxygen species production and improves islet graft function

Ischemia-reperfusion injury (IRI) results in increased rates of delayed graft function and early graft loss. It has recently been reported that hydrogen sulfide (H₂ S) protects organ grafts against prolonged IRI. Here, we investigated whether the preservation of pancreas in University of Wisconsin (UW) solution supplemented with AP39, which is a mitochondrial-targeted H₂ S donor, protected pancreatic islets against IRI and improved islet function. Porcine pancreata were preserved in the UW solution with AP39 (UW + AP39) or the vehicle (UW) for 18 h, followed by islet isolation. The islet yields before and after purification were significantly higher in the UW + AP39 group than in the UW group. The islets isolated from the pancreas preserved in UW + AP39 exhibited significantly decreased levels of reactive oxygen species (ROS) production and a significantly increased mitochondrial membrane potential as compared to the islets isolated from the pancreas preserved in the vehicle. We found that the pancreas preserved in UW + AP39 improved the outcome of islet transplantation in streptozotocin-induced diabetic mice. These results suggest that the preservation of pancreas in UW + AP39 protects the islet grafts against IRI and could thus serve as a novel clinical strategy for improving islet transplantation outcomes.

Indocyanine Green Angiography for Quality Assessment of the Kidney During Transplantation: An Outcome Predictor Prospective Study

BACKGROUND

Microvascular damage is the main cause of delayed graft function (DGF) after kidney transplant. Assessing its extent may be helpful in predicting DGF to achieve better postoperative management, especially in terms of an immunosuppressive regimen. Our aim was to explore the capability of intraoperative indocyanine green (ICG) angiography to examine the microvasculature of the kidney.

METHODS

We conducted a prospective cohort study on 37 kidney transplant recipients in a high-volume kidney transplant center. During surgery, after graft implant, an ICG angiography was performed through a high-definition Storz camera system (Karl Storz GmbH, Tuttlingen, Germany) with successive quantitative assessment of fluorescence using Icy bioimage analysis.

RESULTS

All transplanted kidneys that showed immediate recovery of their function had a fluorescent intensity ≥49.953 with a mean of 96.930 ± 21. The fluorescence intensity for kidneys that showed a delayed recovery of their function never exceeded 55.648, and the mean was 37.718 ± 13. The difference between the 2 groups was statistically significant with a P value < .001. The only kidney that never recovered showed a fluorescence intensity consistently <25.220, the lowest detected.

CONCLUSIONS

This study demonstrates that intraoperative ICG angiography may be used to assess the microvasculature of the graft. A statistically significant difference in terms of fluorescent intensity can be highlighted between kidneys that immediately recover their function and those with delayed recovery. Further larger studies are needed to confirm the capability of the technique to predict DGF to optimize the transplanted patients' management.

Early Transplant Arteriopathy in Kidney Transplantation

BACKGROUND

Early dysfunction of renal allografts may be associated with vascular injury, which raises the specter of active rejection processes that require medical intervention. In our practice, we have encountered patients who present with delayed graft function and demonstrate a unique pattern of endothelial cell injury that raises concern for rejection in their biopsy. Therefore, we sought to systematically determine the biopsy characteristics and outcome of these patients.

METHODS

During a 17-year period at the University of Washington in Seattle, United States, we identified 24 cases of a distinct arterial vasculopathy presenting in the first year posttransplantation. This early transplant arteriopathy (ETA) is characterized by endothelial cell swelling and intimal edema but without the intimal arteritis that defines vascular rejection.

RESULTS

Approximately 1% of transplant biopsies during the study period showed ETA, almost all of which were in deceased donor organs (96%), and most presented with delayed graft function (54%) or increased serum creatinine (38%) soon after transplantation (median 13 days; range, 5-139). In this study, 77% of patients were managed expectantly, with only 2 patients (7.6%) subsequently developing acute vascular rejection. Except for 1 patient who died, all patients had functioning allografts at 1 year follow-up.

CONCLUSION

Recognizing ETA and distinguishing it from vascular rejection is important to prevent over-treatment because most patients appear to recover allograft function rapidly with expectant management.

Oral Administration of Si-Based Agent Attenuates Oxidative Stress and Ischemia-Reperfusion Injury in a Rat Model: A Novel Hydrogen Administration Method

Organ ischemia-reperfusion injury (IRI), which is unavoidable in kidney transplantation, induces the formation of reactive oxygen species and causes organ damage. Although the efficacy of molecular hydrogen (H₂) in IRI has been reported, oral intake of H₂-rich water and inhalation of H₂ gas are still not widely used in clinical settings because of the lack of efficiency and difficulty in handling. We successfully generated large quantities of H₂ molecules by crushing silicon (Si) to nano-sized Si particles (nano-Si) which were allowed to react with water. The nano-Si or relatively large-sized Si particles (large-Si) were orally administered to rats with renal IRI. Animals were divided into four groups: sham, IRI, IRI + nano-Si, and IRI + large-Si. The levels of serum creatinine and urine protein were significantly decreased 72 h following IRI in rats that were administered nano-Si. The levels of oxidative stress marker, urinary 8-hydroxydeoxyguanosine were also significantly decreased with the nano-Si treatment. Transcriptome and gene ontology enrichment analyses showed that the oral nano-Si intake downregulated the biological processes related to oxidative stress, such as immune response, cytokine production, and extrinsic apoptotic signaling pathway. Alterations in the regulation of a subset of genes in the altered pathways were validated by quantitative polymerase chain reaction. Furthermore, immunohistochemical analysis demonstrated that the nano-Si treatment alleviated interstitial macrophage infiltration and tubular apoptosis, implicating the anti-inflammatory and anti-apoptotic effects of nano-Si. In conclusion, renal IRI was attenuated by the oral administration of nano-Si, which should be considered as a novel H₂ administration method.

CD47 limits autophagy to promote acute kidney injury

Acute kidney injury (AKI) initiates a complex pathophysiological cascade leading to epithelial cell death. Recent studies identify autophagy, a key intracellular process that degrades cytoplasmic constituents, as protective against AKI. We have previously reported that the protein thrombospondin-1 and its receptor CD47 are induced in AKI; however, the mechanism underlying their regulation of injury is unknown. Here, we investigated whether CD47 signaling affects autophagy to regulate AKI. Wild-type (WT) and CD47^-/- mice were challenged with renal ischemia-reperfusion injury. All animals underwent analysis of renal function and biomolecular phenotyping. CD47^-/- mice were resistant to AKI, with decreased serum creatinine and ameliorated histologic changes compared with WT animals. These mice also displayed increased abundance of key autophagy genes, including autophagy-related gene (Atg)5, Atg7, beclin-1, and microtubule-associated proteins 1A/1B light chain 3 (LC3) at baseline and post-AKI, which were significantly reduced in WT mice. Changes in protein expression correlated with increased autophagosome and autolysosome formation in renal tubular epithelial cells (RTECs). In mouse kidney transplantation, treatment with a CD47-blocking antibody that improved function was associated with increased autophagy compared with control mice. Primary isolated RTECs from CD47^-/- mice demonstrated increased basal expression of several autophagy components that was preserved under hypoxic stress. These data suggest that activated CD47 promotes AKI through inhibition of autophagy and point to CD47 as a target to preserve renal function following injury.-El-Rashid, M., Ghimire, K., Sanganeria, B., Lu, B., Rogers, N. M. CD47 limits autophagy to promote acute kidney injury.

Predicting urine output after kidney transplantation: development and internal validation of a nomogram for clinical use

Purpose:

To analyze pre-transplantation and early postoperative factors affecting post-transplantation urine output and develop a predictive nomogram.

Patients and Methods:

Retrospective analysis of non-preemptive first transplanted adult patients between 2001-2016. The outcomes were hourly diuresis in mL/Kg in the 1^st (UO₁) and 8^th (UO₈) postoperative days (POD). Predictors for both UO₁ and UO₈ were cold ischemia time (CIT), patient and donor age and sex, HLA I and II compatibility, pre-transplantation duration of renal replacement therapy (RRT), cause of ESRD (ESRD) and immunosuppressive regimen. UO₈ predictors also included UO₁, 1^st/0^th POD plasma creatinine concentration ratio (Cr_1/0), and occurrence of acute cellular rejection (AR). Multivariable linear regression was employed to produce nomograms for UO₁ and UO₈.

Results:

Four hundred and seventy-three patients were included, mostly deceased donor kidneys’ recipients (361, 70.4%). CIT inversely correlated with UO₁ and UO₈ (Spearman's p=-0.43 and −0.37). CR_1/0 inversely correlated with UO₈ (p=-0.47). On multivariable analysis UO₁ was mainly influenced by CIT, with additional influences of donor age and sex, HLA II matching and ESRD. UO₁ was the strongest predictor of UO₈, with significant influences of AR and ESRD.

Conclusions:

The predominant influence of CIT on UO₁ rapidly wanes and is replaced by indicators of functional recovery (mainly UO₁) and allograft's immunologic acceptance (AR absence). Mean absolute errors for nomograms were 0.08 mL/Kg h (UO₁) and 0.05 mL/Kg h (UO₈).

Pure versus hand-assisted retroperitoneoscopic live donor nephrectomy: a retrospective cohort study of 1508 transplants from two centers

BACKGROUND

Although minimally invasive procedures have been established as the standard for a donor nephrectomy, there are many different surgical techniques described in the literature. The aim of this study is to compare the outcomes of kidney transplant procedures using the pure retroperitoneoscopic donor nephrectomy (PRDN) and hand-assisted retroperitoneoscopic donor nephrectomy (HARDN) techniques.

METHODS

A retrospective study involving 1508 transplant procedures was conducted; 874 were PRDN procedures; and 634 were HARDN. We reviewed the outcomes of the PRDN and HARDN groups, which were performed at two different centers over an identical time period.

RESULTS

Donors in the PRDN group had a longer operation time (P < 0.0001), reduced estimated blood loss (P < 0.0001), less open conversion (P = 0.0002), lower postoperative serum C-reactive protein levels (P < 0.0001), and a shorter postoperative hospital stay (P < 0.0001) than the HARDN group. Recipients in the PRDN group had lower serum creatinine levels at postoperative day 1-6 and the decreased incidence of slow graft function (P = 0.0017) than the HARDN group. The HARDN procedure was an independent risk factor for the incidence of acute rejection (P = 0.0211) and graft loss (P = 0.0193).

CONCLUSIONS

Our study suggests that the PRDN procedure is less invasive for donors as it results in reduced blood loss, lower postoperative serum CRP levels, and a shorter postoperative stay than the HARDN procedure. Additionally, PRDN provides a better outcome for recipients as it lowers the incidence of acute rejection and improves graft survival compared to HARDN.

The renoprotective effects of naringin and trimetazidine on renal ischemia/reperfusion injury in rats through inhibition of apoptosis and downregulation of micoRNA-10a

Renal Ischemia-Reperfusion (IR) injury occurs due to circulatory shock and renal transplantation, leading to mortality and morbidity worldwide. The primary purpose of the current study was to evaluate the renoprotective effects of the naringin (NAR) and trimetazidine (TMZ) on IR injury, renal hemodynamics, antioxidant capacity, microRNA-10a, and expression of apoptosis factors. Forty rats were divided into five groups randomly: Sham, IR injury, (TMZ, 5 mg/kg), (NAR pretreatment, 100 mg/kg), and TMZ plus NAR. The sham group underwent the identical surgical procedure as the other groups, except for the application of clamps. After anesthesia, IR injury was induced by 45 min of ischemia, followed by reperfusion for 4 h. Tissue and blood samples were collected for evaluation of renal function, antioxidant activity and, biochemical and molecular parameters. Administration of the NAR, TMZ, and their combination decreased the plasma level of microRNA-10a, caspase-3, and Bcl-2 associated x protein (Bax) mRNA expression, but increased the B- cell lymphoma 2 (Bcl-2) mRNA expression in the kidney tissue. In addition, antioxidant activity, renal blood flow, creatinine clearance (C_Cr), and fractional excretion of sodium (FE_Na) were improved. The NAR, TMZ, and their combination can prevent renal I/R injury through promotion of the level of antioxidant enzymes, as well as decrease of microRNA-10a and anti-apoptosis properties. Our data also suggest that NAR, TMZ, or their combination might be beneficial as potent therapeutic factors against renal IR injury.

The influence of clinical, environmental, and socioeconomic factors on five-year patient survival after kidney transplantation

INTRODUCTION

The risk of death after kidney transplant is associated with the age of the recipient, presence of comorbidities, socioeconomic status, local environmental characteristics and access to health care.

OBJECTIVE

To investigate the causes and risk factors associated with death during the first 5 years after kidney transplantation.

METHODS

This was a single-center, retrospective, matched case-control study.

RESULTS

Using a consecutive cohort of 1,873 kidney transplant recipients from January 1st 2007 to December 31st 2009, there were 162 deaths (case group), corresponding to 5-year patient survival of 91.4%. Of these deaths, 25% occurred during the first 3 months after transplant. The most prevalent cause of death was infectious (53%) followed by cardiovascular (24%). Risk factors associated with death were history of diabetes, dialysis type and time, unemployment, delayed graft function, number of visits to center, number of hospitalizations, and duration of hospital stay. After multivariate analysis, only time on dialysis, number of visits to center, and days in hospital were still associated with death. Patients who died had a non-significant higher number of treated acute rejection episodes (38% vs. 29%, p = 0.078), higher mean number of adverse events per patient (5.1 ± 3.8 vs. 3.8 ± 2.9, p = 0.194), and lower mean eGFR at 3 months (50.8 ± 25.1 vs. 56.7 ± 20.7, p = 0.137) and 48 months (45.9 ± 23.8 vs. 58.5 ± 20.2, p = 0.368).

CONCLUSION

This analysis confirmed that in this population, infection is the leading cause of mortality over the first 5 years after kidney transplantation. Several demographic and socioeconomic risk factors were associated with death, most of which are not readily modifiable.

Proteins in Preservation Fluid as Predictors of Delayed Graft Function in Kidneys from Donors after Circulatory Death

BACKGROUND AND OBJECTIVES

Kidney transplantation is the preferred treatment for ESRD, and donor kidney shortage urges proper donor-recipient matching. Zero-hour biopsies provide predictive values for short- and long-term transplantation outcomes, but are invasive and may not reflect the entire organ. Alternative, more representative methods to predict transplantation outcome are required. We hypothesized that proteins accumulating in preservation fluid during cold ischemic storage can serve as biomarkers to predict post-transplantation graft function.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Levels of 158 proteins were measured in preservation fluids from kidneys donated after circulatory death (Maastricht category III) collected in two Dutch centers (University Medical Center Utrecht and Erasmus Medical Center Rotterdam) between 2013 and 2015. Five candidate biomarkers identified in a discovery set of eight kidneys with immediate function (IF) versus eight with delayed graft function (DGF) were subsequently analyzed in a verification set of 40 additional preservation fluids to establish a prediction model.

RESULTS

Variables tested for their contribution to a prediction model included five proteins (leptin, periostin, GM-CSF, plasminogen activator inhibitor-1, and osteopontin) and two clinical parameters (recipient body mass index [BMI] and dialysis duration) that distinguished between IF and DGF in the discovery set. Stepwise multivariable logistic regression provided a prediction model on the basis of leptin and GM-CSF. Receiver operating characteristic analysis showed an area under the curve (AUC) of 0.87, and addition of recipient BMI generated a model with an AUC of 0.89, outperforming the Kidney Donor Risk Index and the DGF risk calculator, showing AUCs of 0.55 and 0.59, respectively.

CONCLUSIONS

We demonstrate that donor kidney preservation fluid harbors biomarkers that, together with information on recipient BMI, predict short-term post-transplantation kidney function. Our approach is safe, easy, and performs better than current prediction algorithms, which are only on the basis of clinical parameters.

Preconditioning of primary human renal proximal tubular epithelial cells without tryptophan increases survival under hypoxia by inducing autophagy

PURPOSE

Hypoxia plays a significant role in the pathogenesis of acute kidney injury (AKI). Autophagy protects from AKI. Amino acid deprivation induces autophagy. The effect of L-tryptophan depletion on survival and autophagy in cultures of renal proximal tubular epithelial cells (RPTECs) under hypoxia was evaluated.

METHODS

RPTECs were preconditioned in a medium containing or not tryptophan, following culture under hypoxia and treatment with or without the autophagy inhibitor chloroquine. Cell survival was assessed by cell imaging, the level of certain proteins by western blotting and cellular ATP fluorometrically.

RESULTS

Preconditioning of RPTECs in a medium without tryptophan activated general control nonderepressible 2 kinase and induced changes that favored autophagy and cell survival under hypoxic conditions. Additionally, it increased cellular ATP, while it inhibited apoptosis. Inhibition of autophagy nullified the induced increase in cellular ATP and cell survival by the absence of tryptophan. The absence of tryptophan increased p53, although its effect on p53's transcriptional targets was heterogeneous. In accordance with the decreased apoptosis, expression of p21 increased, while expression of Bax decreased. The expression of BNIP3L, which may be pro-apoptotic or pro-autophagic, increased. Considering the decreased apoptosis, it is likely that tryptophan depletion enhances autophagy through a p53-mediated increase of BNIP3L.

CONCLUSION

Preconditioning of primary human RPTECs in a medium without tryptophan increases their survival under hypoxia by inducing autophagy. Identifying new molecular mechanisms that protect renal tissue from hypoxia could be proved clinically important in the prevention of AKI.

Hydrogen Sulfide Protects Renal Grafts Against Prolonged Cold Ischemia-Reperfusion Injury via Specific Mitochondrial Actions

Ischemia-reperfusion injury is unavoidably caused by loss and subsequent restoration of blood flow during organ procurement, and prolonged ischemia-reperfusion injury IRI results in increased rates of delayed graft function and early graft loss. The endogenously produced gasotransmitter, hydrogen sulfide (H₂ S), is a novel molecule that mitigates hypoxic tissue injury. The current study investigates the protective mitochondrial effects of H₂ S during in vivo cold storage and subsequent renal transplantation (RTx) and in vitro cold hypoxic renal injury. Donor allografts from Brown Norway rats treated with University of Wisconsin (UW) solution + H₂ S (150 μM NaSH) during prolonged (24-h) cold (4°C) storage exhibited significantly (p < 0.05) decreased acute necrotic/apoptotic injury and significantly (p < 0.05) improved function and recipient Lewis rat survival compared to UW solution alone. Treatment of rat kidney epithelial cells (NRK-52E) with the mitochondrial-targeted H₂ S donor, AP39, during in vitro cold hypoxic injury improved the protective capacity of H₂ S >1000-fold compared to similar levels of the nonspecific H₂ S donor, GYY4137 and also improved syngraft function and survival following prolonged cold storage compared to UW solution. H₂ S treatment mitigates cold IRI-associated renal injury via mitochondrial actions and could represent a novel therapeutic strategy to minimize the detrimental clinical outcomes of prolonged cold IRI during RTx.

Consequences of Recipient Obesity on Postoperative Outcomes in a Renal Transplant: A Systematic Review and Meta-Analysis

OBJECTIVES

The prevalence of obesity is increasing rapidly and globally, yet systemic reviews on this topic are scarce. Our meta-analysis and systemic review aimed to assess how obesity affects 5 postoperative outcomes: biopsy-proven acute rejection, patient death, allograft loss, type 2 diabetes mellitus after transplant, and delayed graft function.

MATERIALS AND METHODS

We evaluated peer-reviewed literature from 22 medical databases. Studies were included if they were conducted in accordance with the Meta-analysis of Observational Studies in Epidemiology criteria, only examined postoperative outcomes in adult patients, only examined the relation between recipient obesity at time of transplant and our 5 postoperative outcomes, and had a minimum score of > 5 stars on the Newcastle-Ottawa scale for nonrandomized studies. Reliable conclusions were ensured by having our studies examined against 2 internationally known scoring systems. Obesity was defined in accordance with the World Health Organization as having a body mass index of > 30 kg/m(2). All obese recipients were compared versus "healthy" recipients (body mass index of 18.5-24.9 kg/m(2)). Hazard ratios were calculated for biopsy-proven acute rejection, patient death, allograft loss, and type 2 diabetes mellitus after transplant. An odds ratio was calculated for delayed graft function.

RESULTS

We assessed 21 retrospective observational studies in our meta-analysis (N = 241 381 patients). In obese transplant recipients, hazard ratios were 1.51 (95% confidence interval, 1.24-1.78) for presence of biopsy-proven acute rejection, 1.19 (95% confidence interval, 1.10-1.31) for patient death, 1.54 (95% confidence interval, 1.38-1.68) for allograft loss, and 1.01 (95% confidence interval, 0.98-1.07) for development of type 2 diabetes mellitus. The odds ratio for delayed graft function was 1.81 (95% confidence interval, 1.51-2.13).

CONCLUSIONS

Our meta-analysis clearly demonstrated greater risks for obese renal transplant recipients and poorer postoperative outcomes with obesity. We confidently recommend renal transplant candidates seek medically supervised weight loss before transplant.

Mycophenolate mofetil attenuates uterine ischaemia/reperfusion injury in a rat model

This study evaluated the effect of mycophenolate mofetil (MMF) on uterine tissue preservation following ischaemia/reperfusion (I/R) injury. Uterine I/R injury was induced in rats by clamping the lower abdominal aorta and ovarian arteries for 30 min. Group I/R + V (n = 7) received vehicle alone while Group I/R + M (n = 7) received 20 mg/kg/day MMF. Control groups underwent sham surgery and received vehicle (Group C) or 20 mg/kg/day MMF (Group M) (n = 7 for both). Four hours after detorsion, uterine tissue 8-hydroxy-2'-deoxyguanosine (8-OHdG), glutathione, malondialdehyde (MDA), myeloperoxidase (MPO), superoxide dismutase (SOD) and serum ischaemia modified albumin (IMA) concentrations were measured. Histopathological analyses were performed. The I/R + M group showed significant reduction in serum IMA and uterine tissue 8-OHdG, MDA and MPO and significant increase in SOD concentrations compared with the I/R + V group, indicating a protective effect against I/R oxidative damage (P = 0.009, P = 0.006, P = 0.002, P = 0.003 and P = 0.009, respectively). Histopathological evaluation revealed MMF treatment resulted in significantly less tissue and cellular damage and apoptosis compared with the I/R + V group. These results indicate MMF is effective in attenuating uterine tissue damage and preventing apoptosis following uterine I/R injury, probably via anti-inflammatory and anti-oxidative action.

Heyman S, Lupo A, Vlodavsky I, Abassi Z. Heparanase: A Potential New Factor Involved in the Renal Epithelial Mesenchymal Transition (EMT) Induced by Ischemia/Reperfusion (I/R) Injury

BACKGROUND

Ischemia/reperfusion (I/R) is an important cause of acute renal failure and delayed graft function, and it may induce chronic renal damage by activating epithelial to mesenchymal transition (EMT) of renal tubular cells. Heparanase (HPSE), an endoglycosidase that regulates FGF-2 and TGFβ-induced EMT, may have an important role. Therefore, aim of this study was to evaluate its role in the I/R-induced renal pro-fibrotic machinery by employing in vitro and in vivo models.

METHODS

Wild type (WT) and HPSE-silenced renal tubular cells were subjected to hypoxia and reoxygenation in the presence or absence of SST0001, an inhibitor of HPSE. In vivo, I/R injury was induced by bilateral clamping of renal arteries for 30 min in transgenic mice over-expressing HPSE (HPA-tg) and in their WT littermates. Mice were sacrificed 48 and 72 h after I/R. Gene and protein EMT markers (α-SMA, VIM and FN) were evaluated by bio-molecular and histological methodologies.

RESULTS

In vitro: hypoxia/reoxygenation (H/R) significantly increased the expression of EMT-markers in WT, but not in HPSE-silenced tubular cells. Notably, EMT was prevented in WT cells by SST0001 treatment. In vivo: I/R induced a remarkable up-regulation of EMT markers in HPA-tg mice after 48-72 h. Noteworthy, these effects were absent in WT animals.

CONCLUSIONS

In conclusion, our results add new insights towards understanding the renal biological mechanisms activated by I/R and they demonstrate, for the first time, that HPSE is a pivotal factor involved in the onset and development of I/R-induced EMT. It is plausible that in future the inhibition of this endoglycosidase may represent a new therapeutic approach to minimize/prevent fibrosis and slow down chronic renal disease progression in native and transplanted kidneys.

Impact of a quality improvement project on deceased organ donor management

CONTEXT

Donors showed poor glucose control in the period between declaration of brain death and organ recovery. The level of hyperglycemia in the donors was associated with a decline in terminal renal function.

OBJECTIVE

To determine whether implementation of a quality improvement project improved glucose control and preserved renal function in deceased organ donors.

METHODS

Data collected retrospectively included demographics, medical history, mechanism of death, laboratory values, and data from the United Network for Organ Sharing.

RESULTS

After implementation of the quality improvement project, deceased donors had significantly lower mean glucose concentrations (mean [SD], 162 [44] vs 212 [42] mg/dL; P<.001) and prerecovery glucose concentration (143 [66] vs 241 [69] mg/dL; P<.001). When the donor cohorts from before and after the quality improvement project were analyzed together, mean glucose concentration remained a significant predictor of terminal creatinine level (P<.001). Multivariate analysis of delayed graft function in kidney recipients matched to donors indicated that higher terminal creatinine level was associated with delayed graft function in recipients (P<.001).

CONCLUSION

The quality improvement project improved donor glucose homeostasis, and the data confirm that poor glucose homeostasis is associated with worsening terminal renal function.

Transforming growth factor-β1 regulates human renal proximal tubular epithelial cell susceptibility to natural killer cells via modulation of the NKG2D ligands

Transforming growth factor-β (TGF-β) has a significant role in the response to injury and tissue repair, and it has been detected in various cell types. However, the mechanism by which it regulates the response to ischemia‑reperfusion injury (IRI) and manipulates natural killer (NK) cells is not well understood. In the present study, TGF‑β modulated NK cell function, thereby promoting recovery from renal IRI. Human renal proximal tubular epithelial cells (HK‑2) treated with TGF‑β exhibited increased surface and intracellular expression of the NK group 2 member D (NKG2D) ligand MICA. This increased surface expression of MICA inhibited NK cell cytotoxicity to the HK‑2 cells. In addition, an enzyme‑linked immunosorbent assay revealed that TGF‑β treatment evidently increased the amount of soluble MICA released into the culture supernatant from HK‑2 cells. Taken together, these findings suggest that TGF‑β‑induced release of soluble MICA leads to downregulation of NKG2D, thereby preventing NK cell‑mediated cytotoxicity toward renal proximal tubular epithelial cells in renal IRI, which in turn improves the survival of these cells.

Center-level variation in the development of delayed graft function after deceased donor kidney transplantation

BACKGROUND

Patient-level risk factors for delayed graft function (DGF) have been well described. However, the Organ Procurement and Transplantation Network definition of DGF is based on dialysis in the first week, which is subject to center-level practice patterns. It remains unclear if there are center-level differences in DGF and if measurable center characteristics can explain these differences.

METHODS

Using the 2003 to 2012 Scientific Registry of Transplant Recipients data, we developed a hierarchical (multilevel) model to determine the association between center characteristics and DGF incidence after adjusting for known patient risk factors and to quantify residual variability across centers after adjustment for these factors.

RESULTS

Of 82,143 deceased donor kidney transplant recipients, 27.0% developed DGF, with a range across centers of 3.2% to 63.3%. A center's proportion of preemptive transplants (odds ratio [OR], 0.83; per 5% increment; 95% confidence interval [95% CI], 0.74-;0.93; P = 0.001) and kidneys with longer than 30 hr of cold ischemia time (CIT) (OR, 0.95; per 5% increment; 95% CI, 0.92-;0.98; P = 0.001) were associated with less DGF. A center's proportion of donation after cardiac death donors (OR, 1.12; per 5% increment; 95% CI, 1.03-;1.17; P < 0.001) and imported kidneys (OR, 1.06; per 5% increment; 95% CI, 1.03-;1.10; P < 0.001) were associated with more DGF. After patient-level and center-level adjustments, only 41.8% of centers had DGF incidences consistent with the national median and 28.2% had incidences above the national median.

CONCLUSION

Significant heterogeneity in DGF incidences across centers, even after adjusting for patient-level and center-level characteristics, calls into question the generalizability and validity of the current DGF definition. Enhanced understanding of center-level variability and improving the definition of DGF accordingly may improve DGF's utility in clinical care and as a surrogate endpoint in clinical trials.

Delayed graft function and the risk of acute rejection in the modern era of kidney transplantation

Delayed graft function (DGF) is commonly considered a risk factor for acute rejection, although this finding has not been uniformly observed across all studies. The link between DGF and acute rejection may have changed over time due to advances in immunosuppression and medical management. Here we conducted a cohort study of 645 patients over 12 years to evaluate the association of DGF and biopsy-proven acute rejection (BPAR) in a modern cohort of kidney transplant recipients. DGF was defined as the need for at least one dialysis session in the first week after kidney transplantation. The 1-, 3-, and 5-year cumulative probabilities of BPAR were 16.0, 21.8, and 22.6% in the DGF group, significantly different from the 10.1, 12.4, and 15.7% in the non-DGF group. In multivariable Cox proportional hazards model, the adjusted relative hazard for BPAR in DGF (vs. no DGF) was 1.55 (95% confidence interval (CI): 1.03, 2.32). This association was generally robust to different definitions of DGF. The relative hazard was also similarly elevated for T-cell- or antibody-mediated BPAR (1.52 (0.92, 2.51) and 1.54 (0.85, 2.77), respectively). Finally, the association was consistent across clinically relevant subgroups. Thus DGF remains an important risk factor for BPAR in a contemporary cohort of kidney transplant recipients. Interventions to reduce the risk of DGF and/or its aftereffects remain of paramount importance to improve kidney transplant outcomes.

Transdisciplinary approach to restore pancreatic islet function

The focus of our research is on islet immunobiology. We are exploring novel strategies that could be of assistance in the treatment and prevention of type 1 diabetes, as well as in the restoration of metabolic control via transplantation of insulin producing cells (i.e., islet cells). The multiple facets of diabetes and β-cell replacement encompass different complementary disciplines, such as immunology, cell biology, pharmacology, and bioengineering, among others. Through their interaction and integration, a transdisciplinary dimension is needed in order to address and overcome all aspects of the complex puzzle toward a successful clinical translation of a biological cure for diabetes.

Glycyrrhizic acid ameliorates HMGB1-mediated cell death and inflammation after renal ischemia reperfusion injury

BACKGROUND

Renal ischemia reperfusion injury (IRI) leads to acute kidney injury (AKI) and the death of tubular epithelial cells (TEC). The release of high-mobility group box-1 (HMGB1) and other damage-associated molecular pattern moieties from dying cells may promote organ dysfunction and inflammation by effects on TEC. Glycyrrhizic acid (GZA) is a functional inhibitor of HMGB1, but its ability to attenuate the HMGB1-mediated injury of TEC has not been tested.

METHODS/RESULTS

In vitro, hypoxia and cytokine treatment killed TEC and resulted in the progressive release of HMGB1 into the supernatant. GZA reduced the hypoxia-induced TEC death as measured by annexin-V and propidium iodide. Hypoxia increased the expression of MCP-1 and CXCL1 in TEC, which was reduced by GZA in a dose-dependent manner. Similarly, the HMGB1 activation of effector NK cells was inhibited by GZA. To test the effect of HMGB1 neutralization by GZA in vivo, mice were subjected to renal IRI. HMGB1 protein expression increased progressively in kidneys from 4 to 24 h after ischemia and was detected in tubular cells by 4 h using immunohistochemistry. GZA preserved renal function after IRI and reduced tubular necrosis and neutrophil infiltration by histological analyses and ethidium homodimer staining.

CONCLUSIONS

Importantly, these data demonstrate for the first time that AKI following hypoxia and renal IRI may be promoted by HMGB1 release, which can reduce the survival of TEC and augment inflammation. Inhibition of the interaction of HMGB1 with TEC through GZA may represent a therapeutic strategy for the attenuation of renal injury following IRI and transplantation.

Memory T Cells in Transplantation

Following infections and environmental exposures, memory T cells are generated that provide long-term protective immunity. Compared to their naïve T cell counterparts, memory T cells possess unique characteristics that endow them with the ability to quickly and robustly respond to foreign antigens. While such memory T cells are beneficial in protecting their hosts from recurrent infection, memory cells reactive to donor antigens pose a major barrier to successful transplantation and tolerance induction. Significant progress has been made over the past several decades contributing to our understanding of memory T cell generation, their distinct biology, and their detrimental impact in clinical and animal models of transplantation. This review focuses on the unique features which make memory T cells relevant to the transplant community and discusses potential therapies targeting memory T cells which may ameliorate allograft rejection.

Glutathione S-transferase iso-enzymes in perfusate from pumped kidneys are associated with delayed graft function

Accurate and reliable assessment tools are needed in transplantation. The objective of this prospective, multi-center study was to determine the associations of the alpha and pi iso-enzymes of glutathione S-transferase (GST), measured from perfusate solution at the start and end (base and post) of kidney allograft machine perfusion, with subsequent delayed graft function (DGF). We also compared GST iso-enzyme perfusate levels from discarded versus transplanted kidneys. A total of 428 kidneys were linked to outcomes as recorded by the United Network of Organ Sharing. DGF, defined as any dialysis in the first week of transplant, occurred in 141 recipients (32%). Alpha- and pi-GST levels significantly increased during machine perfusion. The adjusted relative risks (95% confidence interval) of DGF with each log-unit increase in base and post pi-GST were 1.14 (1.0-1.3) and 1.36 (1.1-1.8), respectively. Alpha-GST was not independently associated with DGF. There were no significant differences in GST values between discarded and transplanted kidneys, though renal resistance was significantly higher in discarded kidneys. We found pi-GST at the end of machine perfusion to be independently associated with DGF. Further studies should elucidate the utility of GST for identifying injured kidneys with regard to organ allocation, discard and recipient management decisions.

Karyopherins: potential biological elements involved in the delayed graft function in renal transplant recipients

Background

Immediately after renal transplantation, patients experience rapid and significant improvement of their clinical conditions and undergo considerable systemic and cellular modifications. However, some patients present a slow recovery of the renal function commonly defined as delayed graft function (DGF). Although clinically well characterized, the molecular mechanisms underlying this condition are not totally defined, thus, we are currently missing specific clinical markers to predict and to make early diagnosis of this event.

Methods

We investigated, using a pathway analysis approach, the transcriptomic profile of peripheral blood mononuclear cells (PBMC) from renal transplant recipients with DGF and with early graft function (EGF), before (T0) and 24 hours (T24) after transplantation.

Results

Bioinformatics/statistical analysis showed that 15 pathways (8 up-regulated and 7 down-regulated) and 11 pathways (5 up-regulated and 6 down-regulated) were able to identify DGF patients at T0 and T24, respectively. Interestingly, the most up-regulated pathway at both time points was NLS-bearing substrate import into nucleus, which includes genes encoding for several subtypes of karyopherins, a group of proteins involved in nucleocytoplasmic transport. Signal transducers and activators of transcription (STAT) utilize karyopherins-alpha (KPNA) for their passage from cytoplasm into the nucleus. In vitro functional analysis demonstrated that in PBMCs of DGF patients, there was a significant KPNA-mediated nuclear translocation of the phosphorylated form of STAT3 (pSTAT3) after short-time stimulation (2 and 5 minutes) with interleukin-6.

Conclusions

Our study suggests the involvement, immediately before transplantation, of karyopherin-mediated nuclear transport in the onset and development of DGF. Additionally, it reveals that karyopherins could be good candidates as potential DGF predictive clinical biomarkers and targets for pharmacological interventions in renal transplantation. However, because of the low number of patients analyzed and some methodological limitations, additional studies are needed to validate and to better address these points.

Endogenous memory CD8 T cells directly mediate cardiac allograft rejection

Differences in levels of environmentally induced memory T cells that cross-react with donor MHC molecules are postulated to account for the efficacy of allograft tolerance-inducing strategies in rodents versus their failure in nonhuman primates and human transplant patients. Strategies to study the impact of donor-reactive memory T cells on allografts in rodents have relied on the pretransplant induction of memory T cells cross-reactive with donor allogeneic MHC molecules through recipient viral infection, priming directly with donor antigen or adoptive transfer of donor antigen primed memory T cells. Each approach accelerates allograft rejection and confers resistance to tolerance induction, but also biases the T cell repertoire to strong donor reactivity. The ability of endogenous memory T cells within unprimed mice to directly reject an allograft is unknown. Here, we show a direct association between increased duration of cold ischemic allograft storage and numbers and enhanced functions of early graft infiltrating endogenous CD8 memory T cells. These T cells directly mediate rejection of allografts subjected to prolonged ischemia and this rejection is resistant to costimulatory blockade. These findings recapitulate the clinically significant impact of endogenous memory T cells with donor reactivity in a mouse transplant model in the absence of prior recipient priming.

Cell injury after ischemia and reperfusion in the porcine kidney evaluated by radiolabelled microspheres, sestamibi, and lactadherin

Background

The purpose of the present study was to quantify renal cell injury after ischemia and reperfusion in a pig model using ^99mTc-lactadherin as a marker of apoptosis and ^99mTc-sestamibi as a marker of mitochondrial dysfunction.

Methods

Thirty-four pigs were randomized into unilateral renal warm ischemia of 120 (WI₁₂₀) or 240 min (WI₂₄₀). The glomerular filtration rate (GFR) was calculated by renal clearance of ⁵¹Cr-ethylenediaminetetraacetic acid, and apoptosis was quantified by immunohistochemical detection of caspase-3. After 240 min of reperfusion, intravenous ^99mTc-lactadherin or ^99mTc-sestamibi was injected simultaneously with ¹⁵³Gd microspheres into the aorta. Ex-vivo static planar images of the kidneys were acquired for determination of the differential renal function of tracer distribution using a gamma camera.

Results

In WI₁₂₀, there was no significant difference in the uptake of microspheres in the ischemic and contralateral normal kidney indicating adequate perfusion (uptake in ischemic kidney relative to the sum of uptake in both kidneys; 46% ± 12% and 51% ± 5%). In WI₂₄₀, the uptake of microspheres was severely reduced in both groups (17% ± 11% and 27% ± 17%). GFR was severely reduced in the post ischemic kidney in both groups.

In both groups, the uptake of lactadherin was reduced (41% ± 8%, 17% ± 13%) but not different from the uptake of ¹⁵³Gd microspheres. Caspase-3-positive cell profiles were increased in the post-ischemic kidneys (p < 0.001) and increased as the length of ischemia increased (p = 0.003). In both WI₁₂₀ and WI₂₄₀, the amount of ^99mTc-sestamibi in the ischemic kidney was significantly lower than the amount of ¹⁵³Gd microspheres (40 ± 5 versus 51 ± 5 and 20 ± 11 versus 27 ± 17; p < 0.05).

Conclusions

In an established pig model with unilateral renal warm ischemia, we found significantly reduced ^99mTc-sestamibi uptake relative to perfusion in the kidneys exposed to ischemia indicating a potential ability to detect renal ischemic and reperfusion injuries. However, apoptosis was not detected using ^99mTc-lactadherin in the post-ischemic kidneys despite increased number of caspase-3-positive cell profiles.

Trial registration

This study is approved by the Danish Inspectorate of Animal Experiments (2010/561-1837).

Antithymocyte globulin induction and rapid steroid taper leads to excellent results in kidney transplantation with donation after cardiac death donors: importance of rejection and delayed graft function

Recipients of primary transplants from donation after cardiac death (DCD) donors (n = 40) performed from January 2005 to December 2009 were retrospectively reviewed and compared with recipients of primary transplants from donation after brain death (DBD) donors (n = 142). Patients received rabbit antithymocyte globulin induction and rapid steroid taper (RST; steroids stopped 5 days after surgery). Maintenance immunosuppression included tacrolimus and mycophenolate mofetil. Protocol kidney biopsies, creatinine (Cr), and measured glomerular filtration rate (mGFR; determined by cold iothalamate or 24-h creatinine clearance) were obtained at 1, 4, 12, and 24 months. Kidney biopsies for cause were conducted for unexplained elevated Cr, decline in mGFR, or new proteinuria. Biopsies were graded for rejection according to the Banff criteria. Graft survival at 3 years was 90.0% for DCD recipients and 86.6% for DBD recipients (P = NS). Rejection of any grade diagnosed on any biopsy through the first 2 years occurred in 18 DCD (45%) and 50 DBD (35%) recipients. Rejection of a grade more than Banff borderline occurred in 12.5% DCD and 12.7% DBD recipients. At 2 years, the mean ± SEM Cr and mGFR for DCD recipients with rejection were 1.8 ± 0.29 mg/dL and 59.2 ± 8.5 mL/min versus 1.3 ± 0.11 mg/dL and 67.0 ± 7.8 ml/min for those without rejection. For DBD recipients with rejection, Cr and mGFR at 2 years were 1.7 ± 0.12 mg/dL and 54.0 ± 4.4 mL/min versus 1.4 ± 0.11 mg/dL and 66.6 ± 3.3 ml/min for those without rejection (P = NS). Comparing DCD to DBD, there was no statistical difference in mean Cr or mGFR outcomes. Regardless of group, grafts with delayed graft function had lower 3-year survival. DCD primary kidney transplant recipients treated with rabbit antithymocyte induction and RST have short-term graft survival and function equivalent to DBD recipients. RST appears to be acceptable immunosuppression for DCD recipients.

An experimental porcine model of heterotopic renal autotransplantation

OBJECTIVE

The aim of the present study was to validate an experimental model of heterotopic renal allotransplantation. Such a model, more relevant to the human situation, has never been previously described.

MATERIALS AND METHODS

Pietrin pigs (40 to 50 kg) were used in the study. Through a midline incision, the left kidney was removed, washed, and preserved in a standard preservation solution (Celsior, Genzyme, France) for 20 hours at 4 °C. Heterotopic autotransplantation was performed into the right iliac fossa onto the external iliac vessels with an end-to-side anastomosis and a nonstented uretero-ureteral anastomosis was performed.

RESULTS

Twenty-five renal allotransplantations were performed over a 5-month time period. Mean operating time progressively decreased and stabilized after 15 procedures (mean ± SD: 78.2 ± 19 minutes and 187.4 ± 18 minutes for left nephrectomy and transplantation, respectively) as morbidity decreased concomitantly. Suturing times for end-to-side anastomosis of the renal artery and vein onto the external iliac artery and vein were 21.9 ± 7 minutes and 34 ± 8 minutes (mean ± SD), respectively. Ten pigs died before the end of the experiment.

CONCLUSIONS

We have developed and validated the first nonrodent animal model of heterotopic renal autotransplantation relevant to the human anatomy and physiology. The procedure was easy to learn and safe. This model could be used to teach junior surgeons renal transplantation techniques and could also be used as a model to study ischemia-reperfusion injury in renal transplantation.

Selection of induction therapy in kidney transplantation

Currently available immunosuppressive agents can be classified into three categories: induction agents, maintenance therapy, and treatment for rejection. This review article will focus on induction immunosuppression. There are three antibodies which are used for induction therapy: the lymphocyte-depleting agents - anti-thymocyte globulin and alemtuzumab, and basiliximab which is nondepleting. Historically, immunosuppressant selection was solely based on efficacy for prevention of rejection. In the current era of transplantation, it is now common practice in the transplant community to select induction therapy on the basis of risk-benefit considerations for each patient. This article will focus on the efficacy of available induction agents and the selection of induction agent based on donor and recipient risk factors.

Rationale of mesenchymal stem cell therapy in kidney injury

Numerous preclinical and clinical studies suggest that mesenchymal stem cells, also known as multipotent mesenchymal stromal cells (MSCs), may improve pathologic conditions involving different organs. These beneficial effects initially were ascribed to the differentiation of MSCs into organ parenchymal cells. However, at least in the kidney, this is a very rare event and the kidney-protective effects of MSCs have been attributed mainly to paracrine mechanisms. MSCs release a number of trophic, anti-inflammatory, and immune-modulatory factors that may limit kidney injury and favor recovery. In this article, we provide an overview of the biologic activities of MSCs that may be relevant for the treatment of kidney injury in the context of a case vignette concerning a patient at high immunologic risk who underwent a second kidney transplantation followed by the development of ischemia-reperfusion injury and acute allograft rejection. We discuss the possible beneficial effect of MSC treatment in the light of preclinical and clinical data supporting the regenerative and immunomodulatory potential of MSCs.

Amelioration of renal ischaemia-reperfusion injury by liposomal delivery of curcumin to renal tubular epithelial and antigen-presenting cells

BACKGROUND AND PURPOSE

Renal ischaemia-reperfusion (IR) injury is an inevitable consequence of renal transplantation, causing significant graft injury, increasing the risk of rejection and contributing to poor long-term graft outcome. Renal injury is mediated by cytokine and chemokine synthesis, inflammation and oxidative stress resulting from activation of the NF-κB pathway.

EXPERIMENTAL APPROACH

We utilized liposomal incorporation of a potent inhibitor of the NF-κB pathway, curcumin, to target delivery to renal tubular epithelial and antigen-presenting cells. Liposomes containing curcumin were administered before bilateral renal ischaemia in C57/B6 mice, with subsequent reperfusion. Renal function was assessed from plasma levels of urea and creatinine, 4 and 24 h after reperfusion. Renal tissue was examined for NF-κB activity and oxidative stress (histology, immunostaining) and for apoptosis (TUNEL). Cytokines and chemokines were measured by RT-PCR and Western blotting.

KEY RESULTS

Liposomal curcumin significantly improved serum creatinine, reduced histological injury and cellular apoptosis and lowered Toll-like receptor-4, heat shock protein-70 and TNF-α mRNA expression. Liposomal curcumin also reduced neutrophil infiltration and diminished inflammatory chemokine expression. Curcumin liposomes reduced intracellular superoxide generation and increased superoxide dismutase levels, decreased inducible NOS mRNA expression and 3-nitrotyrosine staining consistent with limitations in nitrosative stress and inhibited renal tubular mRNA and protein expression of thioredoxin-interacting protein. These actions of curcumin were mediated by inhibition of NF-κB, MAPK and phospho-S6 ribosomal protein.

CONCLUSIONS AND IMPLICATIONS

Liposomal delivery of curcumin promoted effective, targeted delivery of this non-toxic compound that provided cytoprotection via anti-inflammatory and multiple antioxidant mechanisms following renal IR injury.

Activation of parenchymal CD47 promotes renal ischemia-reperfusion injury

Ischemia-reperfusion injury (IRI) contributes to decreased allograft function and allograft rejection in transplanted kidneys. Thrombospondin-1 is a stress protein typically secreted in response to hypoxia and the ligand activator for the ubiquitously expressed receptor CD47. The function of activated CD47 in IRI remains completely unknown. Here, we found that both CD47 and its ligand thrombospondin-1 were upregulated after renal IRI in mice. CD47-knockout mice were protected against renal dysfunction and tubular damage, suggesting that the development of IRI requires intact CD47 signaling. Chimeric CD47-knockout mice engrafted with wild-type hematopoietic cells had significantly lower serum creatinine and less tubular damage than wild-type controls after IRI, suggesting that CD47 signaling in parenchymal cells predominantly mediates renal damage. Treatment with a CD47-blocking antibody protected mice from renal dysfunction and tubular damage compared with an isotype control. Taken together, these data imply that CD47 on parenchymal cells promotes injury after renal ischemia and reperfusion. Therefore, CD47 blockade may have therapeutic potential to prevent or suppress ischemia-reperfusion-mediated damage.

Deceased-donor kidney perfusate and urine biomarkers for kidney allograft outcomes: a systematic review

BACKGROUND

Accurate and reliable assessment of kidney quality before transplantation is needed to predict recipient outcomes and to optimize management and allocation of the allograft. The aim of this study was to systematically review the published literature on biomarkers in two mediums (the perfusate from deceased-donor kidneys receiving machine perfusion and deceased-donor urine) that were evaluated for their possible association with outcomes after kidney transplantation.

METHODS

We searched the Ovid Medline and Scopus databases using broad keywords related to deceased-donor biomarkers in kidney transplantation (limited to humans and the English language). Studies were included if they involved deceased-donor kidneys, measured perfusate or urine biomarkers and studied a possible relationship between biomarker concentrations and kidney allograft outcomes. Each included article was assessed for methodological quality.

RESULTS

Of 1430 abstracts screened, 29 studies met the inclusion criteria. Of these, 23 were studies of perfusate (16 biomarkers examined) and 6 were studies of urine (18 biomarkers examined). Only 3 studies (two perfusate) met the criteria of 'good' quality and only 12 were published since 2000. Perfusate lactate dehydrogenase, glutathione-S-transferase (GST) and aspartate transaminase were all found to be significantly associated with delayed graft function in a majority of their respective studies (6/9, 4/6 and 2/2 studies, respectively). Urine neutrophil gelatinase-associated lipocalin, GST, Trolox-equivalent antioxidant capacity and kidney injury molecule-1 were found to be significantly associated with allograft outcomes in single studies that examined diverse end points.

CONCLUSION

Higher quality studies are needed to investigate modern kidney injury biomarkers, to validate novel biomarkers in larger donor populations and to determine the incremental predictive value of biomarkers over traditional clinical variables.

Receptor binding mode and pharmacological characterization of a potent and selective dual CXCR1/CXCR2 non-competitive allosteric inhibitor

BACKGROUND AND PURPOSE

DF 2156A is a new dual inhibitor of IL-8 receptors CXCR1 and CXCR2 with an optimal pharmacokinetic profile. We characterized its binding mode, molecular mechanism of action and selectivity, and evaluated its therapeutic potential.

EXPERIMENTAL APPROACH

The binding mode, molecular mechanism of action and selectivity were investigated using chemotaxis of L1.2 transfectants and human leucocytes, in addition to radioligand and [(35) S]-GTPγS binding approaches. The therapeutic potential of DF 2156A was evaluated in acute (liver ischaemia and reperfusion) and chronic (sponge-induced angiogenesis) experimental models of inflammation.

KEY RESULTS

A network of polar interactions stabilized by a direct ionic bond between DF 2156A and Lys(99) on CXCR1 and the non-conserved residue Asp(293) on CXCR2 are the key determinants of DF 2156A binding. DF 2156A acted as a non-competitive allosteric inhibitor blocking the signal transduction leading to chemotaxis without altering the binding affinity of natural ligands. DF 2156A effectively and selectively inhibited CXCR1/CXCR2-mediated chemotaxis of L1.2 transfectants and leucocytes. In a murine model of sponge-induced angiogenesis, DF 2156A reduced leucocyte influx, TNF-α production and neovessel formation. In vitro, DF 2156A prevented proliferation, migration and capillary-like organization of HUVECs in response to human IL-8. In a rat model of liver ischaemia and reperfusion (I/R) injury, DF 2156A decreased PMN and monocyte-macrophage infiltration and associated hepatocellular injury.

CONCLUSION AND IMPLICATIONS

DF 2156A is a non-competitive allosteric inhibitor of both IL-8 receptors CXCR1 and CXCR2. It prevented experimental angiogenesis and hepatic I/R injury in vivo and, therefore, has therapeutic potential for acute and chronic inflammatory diseases.

Preconditioning donor with a combination of tacrolimus and rapamacyn to decrease ischaemia-reperfusion injury in a rat syngenic kidney transplantation model

Reperfusion injury remains one of the major problems in transplantation. Repair from ischaemic acute renal failure (ARF) involves stimulation of tubular epithelial cell proliferation. The aim of this exploratory study was to evaluate the effects of preconditioning donor animals with rapamycin and tacrolimus to prevent ischaemia-reperfusion (I/R) injury. Twelve hours before nephrectomy, the donor animals received immunosuppressive drugs. The animals were divided into four groups, as follows: group 1 control: no treatment; group 2: rapamycin (2 mg/kg); group 3 FK506 (0, 3 mg/kg); and group 4: FK506 (0, 3 mg/kg) plus rapamycin (2 mg/kg). The left kidney was removed and after 3 h of cold ischaemia, the graft was transplanted. Twenty-four hours after transplant, the kidney was recovered for histological analysis and cytokine expression. Preconditioning treatment with rapamycin or tacrolimus significantly reduced blood urea nitrogen and creatinine compared with control [blood urea nitrogen (BUN): P < 0·001 versus control and creatinine: P < 0·001 versus control]. A further decrease was observed when rapamycin was combined with tacrolimus. Acute tubular necrosis was decreased significantly in donors treated with immunosuppressants compared with the control group (P < 0·001 versus control). Moreover, the number of apoptotic nuclei in the control group was higher compared with the treated groups (P < 0·001 versus control). Surprisingly, only rapamycin preconditioning treatment increased anti-apoptotic Bcl2 levels (P < 0·001). Finally, inflammatory cytokines, such as tumour necrosis factor (TNF)-α and interleukin (IL)-6, showed lower levels in the graft of those animals that had been pretreated with rapamycin or tacrolimus. This exploratory study demonstrates that preconditioning donor animals with rapamycin or tacrolimus improves clinical outcomes and reduce necrosis and apoptosis in kidney I/R injury.

Delayed graft function in the kidney transplant

Acute kidney injury occurs with kidney transplantation and too frequently progresses to the clinical diagnosis of delayed graft function (DGF). Poor kidney function in the first week of graft life is detrimental to the longevity of the allograft. Challenges to understand the root cause of DGF include several pathologic contributors derived from the donor (ischemic injury, inflammatory signaling) and recipient (reperfusion injury, the innate immune response and the adaptive immune response). Progressive demand for renal allografts has generated new organ categories that continue to carry high risk for DGF for deceased donor organ transplantation. New therapies seek to subdue the inflammatory response in organs with high likelihood to benefit from intervention. Future success in suppressing the development of DGF will require a concerted effort to anticipate and treat tissue injury throughout the arc of the transplantation process.

[Is there a safe cold ischemia time interval for the renal graft?]

OBJECTIVE

It is aimed to characterize the true relationship of the cold ischemia time (CIT) with graft survival and with the principal post-transplantation events.

MATERIAL AND METHODS

We analyzed 378 kidney transplants, studying the relationship of the CIT with graft survival using a univariate analysis according to the COX model and seeking the optimum cutoff according to the Kaplan-Meier method and log-rank test. The relationship between CIT and the principal events of the post-transplant was studied using the binary logistic regression.

RESULTS

The mean follow-up of all the group was 77.8 months (± 51 SD) and the mean CIT was 14.8 hours (± 5.1 SD). The univariate analysis revealed that the CIT was not related with the graft survival as a continuous variable (OR=1.04; 95% CI: 0.9-1.08; p>0.05). On establishing the cutoff at 18 hours, we found differences in the actuarial survival. Survival at 5 years was 91% with CIT < 18 h versus 84% with CIT >18 h. Each hour of cold ischemia increased risk of delay in the graft function by 10% (OR=1.1; 95% CI: 1.05-1.15; p<0.001) and also conditioned a greater incidence of acute rejection (41.5% vs. 55.3%; p=0.02) and less time to the first rejection episode (72.6 days±137 vs. 272.2 days±614.8; p=0.023) after 18 hours. The CIT did not seem to be related (p<0.05) with the rest of the post-transplantation events, such as surgical complications or hospital admissions.

CONCLUSIONS

In our experience, cold ischemia under 18 hours does not seem to negatively affect graft survival.

Bβ(15-42) attenuates the effect of ischemia-reperfusion injury in renal transplantation

Renal ischemia-reperfusion contributes to reduced renal allograft survival. The peptide Bβ(15-42), a breakdown product of fibrin, attenuates inflammation induced by ischemia-reperfusion in the heart by competitively blocking the binding of leukocytes to endothelial VE-cadherin, but whether it could improve outcomes in renal transplantation is unknown. Here, we tested the ability of Bβ(15-42) to ameliorate the effects of renal ischemic injury during allogenic kidney transplantation in mice. In our renal transplantation model (C57BL/6 into BALB/c mice), treatment with Bβ(15-42) at the time of allograft reperfusion resulted in significantly improved survival of recipients during the 28-day follow-up (60% versus 10%). Bβ(15-42) treatment decreased leukocyte infiltration, expression of endothelial adhesion molecules, and proinflammatory cytokines. Treatment significantly attenuated allogenic T cell activation and reduced cellular rejection. Moreover, Bβ(15-42) significantly reduced tubular epithelial damage and apoptosis, which we reproduced in vitro. These data suggest that Bβ(15-42) may have therapeutic potential in transplant surgery by protecting grafts from ischemia-reperfusion injury.