Delayed graft function in kidney transplantation

Targeted donor complement blockade after brain death prevents delayed graft function in a nonhuman primate model of kidney transplantation

Delayed graft function (DGF) in renal transplant is associated with reduced graft survival and increased immunogenicity. The complement-driven inflammatory response after brain death (BD) and posttransplant reperfusion injury play significant roles in the pathogenesis of DGF. In a nonhuman primate model, we tested complement-blockade in BD donors to prevent DGF and improve graft survival. BD donors were maintained for 20 hours; kidneys were procured and stored at 4°C for 43-48 hours prior to implantation into ABO-compatible, nonsensitized, MHC-mismatched recipients. Animals were divided into 3 donor-treatment groups: G1 - vehicle, G2 - rhC1INH+heparin, and G3 - heparin. G2 donors showed significant reduction in classical complement pathway activation and decreased levels of tumor necrosis factor α and monocyte chemoattractant protein 1. DGF was diagnosed in 4/6 (67%) G1 recipients, 3/3 (100%) G3 recipients, and 0/6 (0%) G2 recipients (P = .008). In addition, G2 recipients showed superior renal function, reduced sC5b-9, and reduced urinary neutrophil gelatinase-associated lipocalin in the first week posttransplant. We observed no differences in incidence or severity of graft rejection between groups. Collectively, the data indicate that donor-management targeting complement activation prevents the development of DGF. Our results suggest a pivotal role for complement activation in BD-induced renal injury and postulate complement blockade as a promising strategy for the prevention of DGF after transplantation.

Heme-Oxygenase and Kidney Transplantation: A Potential for Target Therapy?

Kidney transplantation is a well-established therapy for patients with end-stage renal disease. While a significant improvement of short-term results has been achieved in the short-term, similar results were not reported in the long-term. Heme-oxygenase (HO) is the rate-limiting enzyme in heme catabolism, converting heme to iron, carbon monoxide, and biliverdin. Heme-oxygenase overexpression may be observed in all phases of transplant processes, including brain death, recipient management, and acute and chronic rejection. HO induction has been proved to provide a significant reduction of inflammatory response and a reduction of ischemia and reperfusion injury in organ transplantation, as well as providing a reduction of incidence of acute rejection. In this review, we will summarize data on HO and kidney transplantation, suggesting possible clinical applications in the near future to improve the long-term outcomes.

Robot-Assisted versus Laparoscopic Donor Nephrectomy: A Comparison of 250 Cases

Living kidney donation is the best treatment for end-stage renal disease, however, the best surgical approach for minimally-invasive donor nephrectomy (DN) is still a matter of debate. This bi-centric study aimed to retrospectively compare perioperative outcomes and postoperative kidney function after 257 transperitoneal DNs including 52 robot-assisted (RDN) and 205 laparoscopic DNs (LDN). As primary outcomes, the intraoperative (operating time, warm ischemia time (WIT), major complications) and postoperative (length of stay, complications) results were compared. As secondary outcomes, postoperative kidney and graft function were analyzed including delayed graft function (DGF) rates, and the impact of the surgical approach was assessed. Overall, the type of minimally-invasive donor nephrectomy (RDN vs. LDN) did not affect primary outcomes, especially not operating time and WIT; and major complication and DGF rates were low in both groups. A history of smoking and preoperative kidney function, but not the surgical approach, were predictive for postoperative serum creatinine of the donor and recipient. To conclude, RDN and LDN have equivalent perioperative results in experienced centers. For this reason, not the surgical approach, but rather the graft- (preoperative kidney function) and patient-specific (history of smoking) aspects impacted postoperative kidney function.

Optimizing Intraoperative Blood Pressure to Improve Outcomes in Living Donor Renal Transplantation

BACKGROUND

Adequate renal perfusion at the time of unclamping is important because it has been known to affect outcomes in renal transplantation. Nevertheless, the ideal intraoperative systolic arterial pressure (SAP) has not been well defined.

METHODS

We performed a retrospective analysis of 106 living donor renal transplants performed at our center from June 2010 to May 2019. We divided the cohort into 2 groups according to our center's goal SAP of ≥150 mm Hg: 57 patients had SAP ≥150 mm Hg and 49 patients had SAP <150 mm Hg. We analyzed pretransplant characteristics, intraoperative measurements, and postoperative laboratory values to validate our center's target SAP at the time of reperfusion. This study strictly complied with the Helsinki Congress and the Istanbul Declaration regarding donor sources.

RESULTS

Patients with SAP ≥150 mm Hg had been on dialysis for a significantly shorter duration before transplant compared with those who had SAP <150 mm Hg. In the SAP ≥150 mm Hg group, urinary sodium excretion normalized earlier, and they had a significantly smaller stroke volume variation, higher cardiac output and cardiac index, earlier initial urination, and higher intraoperative urine output. There were no differences in intraoperative volume repletion, central venous pressure, or postoperative estimated glomerular filtration rate.

CONCLUSION

Achieving SAP ≥150 mm Hg at the time of reperfusion may be associated with early stabilization of graft function. Nevertheless, our data suggested that recipients with a prolonged dialysis history are less likely to achieve SAP ≥150 mm Hg at the time of unclamping in living donor renal transplantation.

The Role of Hormones and Trophic Factors as Components of Preservation Solutions in Protection of Renal Function before Transplantation: A Review of the Literature

Transplantation is currently a routine method for treating end-stage organ failure. In recent years, there has been some progress in the development of an optimal composition of organ preservation solutions, improving the vital functions of the organ and allowing to extend its storage period until implantation into the recipient. Optimizations are mostly based on commercial solutions, routinely used to store grafts intended for transplantation. The paper reviews hormones with a potential nephroprotective effect, which were used to modify the composition of renal perfusion and preservation solutions. Their effectiveness as ingredients of preservation solutions was analysed based on a literature review. Hormones and trophic factors are innovative preservation solution supplements. They have a pleiotropic effect and affect normal renal function. The expression of receptors for melatonin, prolactin, thyrotropin, corticotropin, prostaglandin E1 and trophic factors was confirmed in the kidneys, which suggests that they are a promising therapeutic target for renal IR (ischemia-reperfusion) injury. They can have anti-inflammatory, antioxidant and anti-apoptotic effects, limiting IR injury.

Changes in redox state of albumin before and after kidney transplantation in patients with end-stage renal disease

OBJECTIVES

Cardiovascular disease is one of the major causes of death in patients with end-stage kidney disease who have undergone kidney transplantation. Since the complication of cardiovascular disease in patients with chronic kidney disease is strongly linked to oxidative stress, understanding the oxidative stress condition after kidney transplantation would be of great importance for the prevention of cardiovascular disease. This study examined whether improvement of renal function after kidney transplantation has an impact on the redox state of the Cys34 residue of albumin that reflects the level of oxidative stress in blood.

DESIGN & METHODS

We enrolled 23 patients with end-stage renal failure who received kidney transplantation. All patients were followed for 180 days after transplantation. The fractions of albumin isoforms were determined by the electrospray ionization time-of-flight mass spectrometry (ESI-TOFMS) method.

RESULTS

Serum creatinine decreased significantly immediately after kidney transplantation, suggesting successful transplantations. The ESI-TOFMS method identified three albumin isoforms cysteinylated at the Cys34 residue (Cys-Cys34-albumin) and the three corresponding albumin isoforms without Cys34 cysteinylation. The fraction of total Cys-Cys34-albumin decreased transiently after kidney transplantation, and was followed by an elevation at day 7 and gradual decrease thereafter until day 180. Meanwhile, reduced albumin concentration did not change until day 14 after kidney transplantation, then showed a significant increase compared to pre-transplant level at day 30 and remained stably elevated until day 180.

CONCLUSIONS

Actual reduced albumin levels were found to exceed pre-transplant levels on or after day 30 following kidney transplantation unlike immediate restoration of renal function. Renal function was recovered immediately following kidney transplantation, but reduced albumen concentration increased above the pre-transplant levels only from day 30 after transplantation.

Comparing the effect of induction therapy with or without antithymocyte globulin on renal allograft outcomes in live-donor kidney transplant recipients

Background: This study aimed to investigate the effectiveness of antithymocyte globulin (ATG) in low-risk live-donor kidney transplant recipients (LDKTRs).

Methods: In this cohort study, 114 LDKTRs were analyzed in 2 groups of ATG induction therapy (n=77) and control (n=37). In this study, 500 mg pulse therapy with methylprednisolone was provided for both groups for 3 days. In addition, one mg/kg of daily ATG was prescribed for 4 days in ATG induction group. Serum creatinine (Cr) was measured at 3, 7, 30, 90, and 180 days after surgery and discharge day. Acute rejection (AR) was confirmed based on biopsy or rise in serum Cr by three-tenths from baseline if other causes had been ruled out. Survival analysis was used by Stata14 and p < 0.05 was considered significant.

Results: Cr changes were not significantly different between ATG induction therapy and control group in all follow-up periods (2.26 and 1.07 in ATG vs 2.26 and 1.03 in control group from the third day; (p=0.999) to the sixth month (p=0.735)). There was no significant difference between the 2 study groups in AR incidence (11.7% in ATG vs 10.8% in control group, P = 0.890) and its time (9.6 in ATG vs 9.8 in control group, p=0.695). Recipients factors were baseline Cr >10 mg/dL (p=0.055), blood group AB (p=0.007), no postoperative pulse therapy with methylprednisolone (PM) (p=0.005); and donors’ factors were age ≤ 30 years (p=0.022) and blood group AB (p=0.006). Also, based on the log rank analysis, recipient-donor weight difference of 0 to 5 kg (p=0.047) had a significant association with earlier AR. Exploring these effects simultaneously by Cox regression analysis showed only significant results for recipients' baseline Cr (p=0.040) and postoperative therapy with PM (p=0.014).

Conclusion: Both strategies of induction therapy had the same good results based on Cr decrease. Recipients' baseline Cr and postoperative therapy with PM were the predictors of survival time of the kidney (AR).

Long-Term Function of Kidneys From an Acute Renal Failure Donor on Continuous Venovenous Hemofiltration: A Case Report

The organ shortage has induced many transplant centers to use suboptimal grafts, such as those from expanded criteria donors and donors after cardiac death. Acute renal failure donors, sometimes present in intensive therapy units, have been used in a very low number of cases due to the fear of primary nonfunction of this type of graft. There are few published studies about the utilization of donors with severe acute renal failure and there is no general consensus identifying unequivocal criteria for their use by different transplant centers. We transplanted 2 kidneys from a 67-year-old donor who suffered from acute renal failure as a consequence of extracorporeal circulation in cardiac surgery and died of a massive cerebral edema with cistern obliteration. The kidneys were discarded by other transplant centers due to the patient's acute renal failure, treated by continuous venovenous hemofiltration. Both transplants were successful and both grafts showed very good renal function after 6 months. One recipient suffered from delayed graft function and renal drug toxicity, which resolved 1 month post transplant. The long-term graft function at 10 years is acceptable, with very low proteinuria. As a growing gap between the inadequate supply and constantly high demand for kidney transplantation has led doctors to explore novel policies to increase the number of available organs over the last 2 decades, acute renal failure treated by continuous venovenous hemofiltration does not seem to be a contraindication for the utilization of grafts.

Pathology of the kidney allograft

The kidney biopsy still represents the best approach to diagnose renal transplant complications. It is considered the gold standard in the diagnosis of rejection and non-rejection complications. Although invasive, it is a safe procedure with a very low complication rate. With adequate sampling, changes related to antibody-mediated rejection (ABMR) and T-cell mediated rejection (TCMR) can be identified. However, the pathologist needs to be aware of the many other complications, not related to rejection, that can affect the allograft function. Examples include viral infections, drug toxicity, systemic diseases such as hypertension and diabetes, and recurrent or de novo glomerulopathy, among others. In this article, we review the recent classification of pathology of the kidney allograft, with reference to recent consensus reached at the most recent Banff renal allograft classification meetings, and also highlight common non-rejection complications of the kidney transplant.

Identification of Factors Associated With Acute Tubular Necrosis Following Kidney Transplant in Northern Mexico: Increased Risk With Cold Ischemia After 8 Hours

AIM

To identify potential risk factors associated with the incidence of acute tubular necrosis (ATN) following kidney transplant in a sample of patients from northern Mexico.

METHODS

Secondary analysis of data extracted from clinical files of patients who underwent a kidney transplant between 2000 and 2017 at Christus Muguerza Hospital in the city of Chihuahua. The final sample with complete data included 485 patients. ATN was diagnosed in 13.2% of patients using pathologic, clinical, and laboratory criteria. Adjusted odds ratio (ORs) with 95% CIs from multivariate binary logistic regression were used to identify predictors of ATN.

RESULTS

Only 4 of 21 variables analyzed remained statistically significant in the final adjusted model. Cold and warm ischemia followed time-trend patterns with higher odds with longer ischemia times. For cold ischemia, compared with 0 to 240 minutes, ORs were 1.32 (95% CI, 0.49-3.51) for 241-480 minutes, 4.87 (95% CI, 2.29-10.3) for 481-960 minutes, and 10.0 (95% CI, 2.86-35.0) for > 960 minutes; for warm ischemia, compared with 40 to 59 minutes, these were 6.27 (95% CI, 1.95-20.8) for 60-70 minutes and 10.32 (95% CI, 1.95-54.4) for 71-110 minutes. Hypotension during surgery was associated with a higher chance of ATN (OR, 15.9; 95% CI, 4.97-50.9). When the recipients' age was 30 years or older, the probability also increased significantly (OR, 2.88; 95% CI, 1.09-7.57). The final model fitted well and explained 27% of the probability to develop ATN after a kidney transplant.

CONCLUSION

Shortening the duration of ischemia and avoiding hypotension during surgery is essential to prevent ATN following a kidney transplant.

Effects of Delayed Hypothermic Machine Perfusion on Kidney Grafts with a Preliminary Period of Static Cold Storage and a Total Cold Ischemia Time of Over 24 Hours

Background

Hypothermic machine perfusion (HMP) appears to exert a reconditioning effect on the ischemic damage of kidney grafts. However, some concerns still remain about its real effectiveness when it is delayed after a preliminary period of static cold storage (SCS) or with prolonged overall cold ischemia time (CIT).

Material/Methods

The effect of HMP on hemodynamic, metabolic, histological and ultrastructural features of grafts was investigated in 21 single-kidney grafts treated with a delayed HMP after SCS and with a total CIT of over 24 h.

Results

The mean CIT, SCS, and HMP times were 29 h, 12 h, and 18 h, respectively. Longer SCS was associated with higher vascular resistance and lower arterial flow. In the pre- vs. post-HMP comparison, a significant decrease in arterial resistances and increase of flow were recorded. The hemodynamic improvement was independent of HMP duration. The perfused grafts retained some metabolic activity, with a statistically significant decrease of pH, pO2, and glucose levels, and increase of lactates in the perfusion liquid, by the end of HMP. Longer SCS was associated with higher pH and greater pO2 decrease during HMP. Light microscopy and transmission electronic microscopy revealed no significant variations in nuclear, cytoplasmic, or ultrastructural damage. SCS, HMP, and CIT were not identified as risk factor for delayed graft function or rejection.

Conclusions

A delayed and extended HMP can recover the graft hemodynamic function, maintain some metabolic activity, and stabilize the accumulated ischemic damage due to a preliminary SCS.

Elucidating the molecular pathways and immune system transcriptome during ischemia-reperfusion injury in renal transplantation

Ischemia reperfusion injury (IRI) is a major challenge for renal transplantation. This study was performed to explore the mechanisms and potential molecular targets involved in renal IRI. In this study, the gene datasets GSE43974 and GSE126805 from the Gene Expression Omnibus database, which include ischemic and reperfused renal specimens, were analyzed to determine differentially expressed genes (DEGs). Gene ontology annotations, Kyoto Encyclopedia of Genes and Genomes analysis, and gene set enrichment analysis were performed to determine the pathways that are significantly enriched during ischemia and reperfusion. We also determined the microenvironment cell types xCell and performed correlation analyses to reveal the relationship between the molecular pathways and microenvironment cell infiltration. We found 77 DEGs (76 up- and 1 downregulated) and 323 DEGs (312 up- and 11 downregulated) in the GSE43974 and GSE126805 datasets, respectively. Similar signaling pathway enrichment patterns were observed between the two datasets. The combined analyses demonstrate that the NOD-like receptor signaling pathway and its two downstream signaling pathways, MAPK and NF-kβ, are the major significantly enriched pathways. The xCell analysis identified immune cells that are significantly changed after reperfusion, including hematopoietic stem cells, M2 macrophages, monocytes, Treg cells, conventional dendritic cells, and pro B-cells. Enrichment scores of the NOD-like receptor signaling pathway and its downstream pathways during IRI was significantly correlated with the change levels in class-switched memory B-cell and hematopoietic stem cells in both datasets. These data reveal the important role of the NOD-like receptor signaling pathway during IRI, and the close relationship between this pathway and infiltration of specific immune cell types. Our data provide compelling insights into the pathogenesis and potential therapeutic targets for renal IRI.

Edaravone Ameliorates Renal Warm Ischemia-Reperfusion Injury by Downregulating Endoplasmic Reticulum Stress in a Rat Resuscitation Model

Background

This study was conducted to explore whether the effect of edaravone (5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol3-one, EDR) can ameliorate renal warm ischemia-reperfusion injury (IRI) by modulating endoplasmic reticulum stress (ERS) and its downstream effector after cardiac arrest (CA) and cardiopulmonary resuscitation (CPR) in a rat model.

Methods

The rats (n=10) experienced anaesthesia and intubation followed by no CA inducement were defined as the Sham group. Transoesophageal alternating current stimulation was employed to establish 8 min of CA followed by conventional CPR for a resuscitation model. The rats with successful restoration of spontaneous circulation (ROSC) randomly received EDR (3 mg/kg, EDR group, n=10) or equal volume normal saline solution (the NS group, n=10). At 24 hr after ROSC, serum creatinine (SCR), blood urea nitrogen (BUN) levels, and cystatin-C (Cys-C) levels were determined and the protein level of glucose-regulated protein (GRP78), C/EBP homologous protein (CHOP), extracellular signal-regulated kinase (ERK), phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2), Bax/Bcl-2, and caspase-3 were detected by Western blot method.

Results

At 24 hrs after ROSC, SCR, BUN and Cys-C were obviously increased and the proteins expression, including GRP78, CHOP and p-ERK1/2, cleaved-caspase 3 Bax/Bcl-2 ratio, were significantly upregulated in the NS group compared with the Sham group (p<0.05). The remarkable improvement of these adverse outcomes was observed in the EDR group (p<0.05).

Conclusion

In conclusion, we found that EDR ameliorates renal warm IRI by downregulating ERS and its downstream effectors in a rat AKI model evoked by CA/CPR. These data may provide evidence for future therapeutic benefits of EDR against AKI induced by CA/CPR.

Remote ischaemic conditioning and early changes in plasma creatinine as markers of one year kidney graft function-A follow-up of the CONTEXT study

BACKGROUND

Ischaemia-reperfusion injury in kidney transplantation leads to delayed graft function (DGF), which is associated with reduced long term graft function. Remote ischaemic conditioning (RIC) improved early kidney graft function in a porcine model of donation after brain death and was associated with improved long-term cardiac outcome after myocardial ischaemia. This randomised, double-blinded trial evaluated the effect of RIC on kidney graft outcome in the first year, and examined the predictive value of a new measure of initial kidney graft function, i.e. the estimated time to a 50% reduction in plasma creatinine post-transplantation (tCr50).

METHODS

A total of 225 patients undergoing deceased donor kidney transplantation were randomised to RIC or a sham procedure performed prior to kidney reperfusion. Up to four repetitive cycles of five minutes of leg ischaemia and five minutes of reperfusion were given. GFR, plasma creatinine, cystatin C and neutrophil gelatinase associated lipocalin (NGAL) were measured at three and twelve months and estimated GFR was calculated using four different equations. Other secondary outcomes were identified from patient files.

RESULTS

RIC did not affect GFR or other outcomes when compared to the sham procedure at three or twelve months. tCr50 correlated with one year graft function (p<0.0001 for both mGFR and eGFR estimates). In contrast, DGF i.e. "need of dialysis the first week" did not correlate significantly with one year GFR.

CONCLUSION

RIC during deceased donor kidney transplantation did not improve one year outcome. However, tCr50 may be a relevant marker for studies aiming to improve graft onset.

TRIAL REGISTRATION

www.ClinicalTrials.gov Identifier: NCT01395719.

Early Steroid Withdrawal in Deceased-Donor Kidney Transplant Recipients with Delayed Graft Function

BACKGROUND

Early steroid withdrawal (ESW) is associated with acceptable outcomes in kidney transplant (KT) recipients. Recipients with delayed graft function (DGF), however, often have a suboptimal allograft milieu, which may alter the risk/benefit equation for ESW. This may contribute to varying practices across transplant centers.

METHODS

Using the Scientific Registry of Transplant Recipients, we studied 110,019 adult deceased-donor KT recipients between 2005 and 2017. We characterized the association of DGF with the use of ESW versus continued steroid maintenance across KT centers, and quantified the association of ESW with acute rejection, graft failure, and mortality using multivariable logistic and Cox regression with DGF-ESW interaction terms.

RESULTS

Overall 29.2% of KT recipients underwent ESW. Recipients with DGF had lower odds of ESW (aOR=_0.600.67_0.75). The strength of this association varied across 261 KT centers, with center-specific aOR of <0.5 at 31 (11.9%) and >1.0 at 22 (8.4%) centers. ESW was associated with benefits and harms among recipients with immediate graft function (IGF), but only with harms among recipients with DGF. ESW was associated with increased acute rejection (aOR=_1.091.16_1.23), slightly increased graft failure (aHR=_1.011.06_1.12), but decreased mortality (aHR=_0.860.89_0.93) among recipients with IGF. Among recipients with DGF, ESW was associated with a similar increase in rejection (aOR=1.12; 95% CI, 1.02 to 1.23), a more pronounced increase in graft failure (aHR=1.16; 95% CI, 1.08 to 1.26), and no improvement in mortality (aHR=1.00; 95% CI, 0.94 to 1.07). DGF-ESW interaction was statistically significant for graft failure (P=0.04) and mortality (P=0.003), but not for rejection (P=0.6).

CONCLUSIONS

KT centers in the United States use ESW inconsistently in recipients with DGF. Our findings suggest ESW may lead to worse KT outcomes in recipients with DGF.

The First Case of Ischemia-Free Kidney Transplantation in Humans

Background: Ischemia-reperfusion injury (IRI) has been considered an inevitable event in organ transplantation since the first successful kidney transplant was performed in 1954. To avoid IRI, we have established a novel procedure called ischemia-free organ transplantation. Here, we describe the first case of ischemia-free kidney transplantation (IFKT). Materials and Methods: The kidney graft was donated by a 19-year-old brain-dead donor. The recipient was a 47-year-old man with end-stage diabetic nephropathy. The graft was procured, preserved, and implanted without cessation of blood supply using normothermic machine perfusion. Results: The graft appearance, perfusion flow, and urine production suggested that the kidney was functioning well-during the whole procedure. The creatinine dropped rapidly to normal range within 3 days post-transplantation. The levels of serum renal injury markers were low post-transplantation. No rejection or vascular or infectious complications occurred. The patient had an uneventful recovery. Conclusion: This paper marks the first case of IFKT in humans. This innovation may offer a unique solution to optimizing transplant outcomes in kidney transplantation.

Association of polymorphisms in leptin and adiponectin genes with long-term outcomes in renal transplant recipients

The effect of polymorphims in leptin and adiponectin genes on long-term outcomes of renal transplantation is unknown. In 349 renal transplant recipients (RTR), we aimed to determine associations between five SNPs in the leptin receptor (LEPR) and adiponectin (ADIPOQ) genes and these outcomes. Follow-up time ranged from 2 to 25 years (mean 10.29 ± 5.16 years). Two SNPs showed associations with long-term outcomes and their statistical significance greatly increased after 39 RTR with a history of cardiovascular events prior to transplantation were removed from the analysis. Adjusted odds ratios (OR) for LEPR rs1805094 and ADIPOQ rs1501299 and risk of graft loss were 0.35 (0.16-0.74) p = 0.006 and 2.37 (1.28-4.37) p = 0.006, respectively. The assessment of risk for global mortality revealed OR values of 0.20 (0.06-0.62), p = 0.005, and 2.43 (1.08-5.44), p = 0.031 for LEPR rs1805094 and ADIPOQ rs1501299, respectively. Our results show that polymorphism in genes involved in leptin and adiponectin function modify long-term outcomes in renal transplantation.

Antibodies against ARHGDIB are associated with long-term kidney graft loss

The clinical significance of non-HLA antibodies on renal allograft survival is a matter of debate, due to differences in reported results and lack of large-scale studies incorporating analysis of multiple non-HLA antibodies simultaneously. We developed a multiplex non-HLA antibody assay against 14 proteins highly expressed in the kidney. In this study, the presence of pretransplant non-HLA antibodies was correlated to renal allograft survival in a nationwide cohort of 4770 recipients transplanted between 1995 and 2006. Autoantibodies against Rho GDP-dissociation inhibitor 2 (ARHGDIB) were significantly associated with graft loss in recipients transplanted with a deceased-donor kidney (N = 3276) but not in recipients of a living-donor kidney (N = 1496). At 10 years after deceased-donor transplantation, recipients with anti-ARHGDIB antibodies (94/3276 = 2.9%) had a 13% lower death-censored covariate-adjusted graft survival compared to the anti-ARHGDIB-negative (3182/3276 = 97.1%) population (hazard ratio 1.82; 95% confidence interval, 1.32-2.53; P = .0003). These antibodies occur independently from donor-specific anti-HLA antibodies (DSA) or other non-HLA antibodies investigated. No significant relations with graft loss were found for the other 13 non-HLA antibodies. We suggest that pretransplant risk assessment can be improved by measuring anti-ARHGDIB antibodies in all patients awaiting deceased-donor transplantation.

l-Fucose prevention of renal ischaemia/reperfusion injury in Mice

In a recent study, we identified a fucosylated damage‐associated ligand exposed by ischemia on renal tubule epithelial cells, which after recognition by collectin‐11 (CL‐11 or collectin kidney 1 (CL‐K1)), initiates complement activation and acute kidney injury. We exploited the ability to increase the local tissue concentration of free l‐fucose following systemic administration, in order to block ligand binding by local CL‐11 and prevent complement activation. We achieved a thirty‐five‐fold increase in the intrarenal concentration of l‐fucose following an IP bolus given before the ischemia induction procedure ‐ a concentration found to significantly block in vitro binding of CL‐11 on hypoxia‐stressed renal tubule cells. At this l‐fucose dose, complement activation and acute post‐ischemic kidney injury are prevented, with additional protection achieved by a second bolus after the induction procedure. CL‐11^−/− mice gained no additional protection from l‐fucose administration, indicating that the mechanism of l‐fucose therapy was largely CL‐11‐dependent. The hypothesis is that a high dose of l‐fucose delivered to the kidney obstructs the carbohydrate recognition site on CL‐11 thereby reducing complement‐mediated damage following ischemic insult. Further work will examine the utility in preventing post‐ischemic injury during renal transplantation, where acute kidney injury is known to correlate with poor graft survival.

Polymorphisms in vasoactive eicosanoid genes of kidney donors affect biopsy scores and clinical outcomes in renal transplantation

Cytochrome P450 (CYP) enzymes metabolize arachidonic acid to vasoactive eicosanoids such as epoxyeicosatrienoic acids (EETs) and 20-Hydroxyeicosatetraenoic acid (20-HETE), whilst soluble epoxide hydrolase, encoded by the EPHX2 gene, is in charge of EETs degradation. We aimed to analyze the influence of common, functional polymorphisms in four genes of the donor on the renal biopsy scores independently assigned by pathologists. Additionally, we examined whether this score or the presence of these SNPs were independent risk factors of clinical outcomes in the first year after grafting. A cohort of 119 recipients and their corresponding 85 deceased donors were included in the study. Donors were genotyped for the CYP4F2 V433M, CYP2C8*3, CYP2J2*7, EPHX2 3’UTR A>G, EPHX2 K55R and EPHX2 R287Q polymorphisms. The association of the donors’ SNPs with the biopsy scores and clinical outcomes was retrospectively evaluated by multivariate regression analysis. The CYP2C8*3 polymorphism in the donor was significantly associated with higher scores assigned to pretransplant biopsies [OR = 3.35 (1.03–10.93), p = 0.045]. In turn, higher scores were related to an increased risk of acute rejection [OR = 5.28 (1.32–21.13), p = 0.019] and worse glomerular filtration rate (eGFR) (45.68±16.05 vs. 53.04±16.93 ml/min in patients whose grafts had lower scores, p = 0.010) one year after transplant. Patients whose donors carried the CYP4F2 433M variant showed lower eGFR values (48.96±16.89 vs. 55.94±18.62 ml/min in non-carriers, p = 0.038) and higher risk of acute rejection [OR = 6.18 (1.03–37.21), p = 0.047]. The CYP2J2*7 SNP in the donor was associated with elevated risk of delayed graft function [OR = 25.68 (1.52–43.53), p = 0.025]. Our results taken together suggest that donor genetic variability may be used as a predictor of tissue damage in the graft as well as to predict clinical outcomes and graft function in the recipient.

Effects of cyclosporine on ischemia-reperfusion injuries in rat kidneys. An experimental model

Purpose

To assess Cyclosporine A (CsA) therapy at an intraperitoneal dose of 15 mg.kg ^-1 in a rodent model of non-septic renal ischemia.

Methods

Twenty male Wistar rats were randomized to receive CsA therapy or none therapy before undergoing 30 minutes of renal ischemia followed by reperfusion. Additionally, 10 rats were randomized to undergo the same surgical procedure of the aforementioned animals with neither ischemia nor CsA therapy. Twelve hours after kidney ischemia, the left kidneys were evaluated for histological injury according to Park’s criteria. Serum creatinine (Cr), urea nitrogen (Ur) and sodium levels were obtained at different times of the experimental protocol.

Results

Rodents in the CsA group showed negative results (p<0.05) in serum variables (Cr: 0.41±0.05mg/dL vs . 4.17±1.25mg/dL; Ur: 40.90±3.98mg/dL vs . 187.70±22.93mg/dL) even the non CsA or control group (Cr: 0.35±0.07mg/dL vs . 3.80±1.20mg/dL; Ur: 40.10±4.70mg/dL vs . 184.50±49.80mg/dL). The negative results were also verified in histological evaluation, CsA group had 50% in the very severe grade of lesion, 10% in the severe and 40% in the moderate to severe whereas the control group had 90% in the very severe grade.

Conclusion

CsA was incapable of preventing the deleterious effects of ischemia-reperfusion injury in rat kidneys.

Intraoperative Fluid Restriction is Associated with Functional Delayed Graft Function in Living Donor Kidney Transplantation: A Retrospective Cohort Analysis

Background: In 2016 we observed a marked increase in functional delayed graft function (fDGF) in our living donor kidney transplantation (LDKT) recipients from 8.5% in 2014 and 8.8% in 2015 to 23.0% in 2016. This increase coincided with the introduction of a goal-directed fluid therapy (GDFT) protocol in our kidney transplant recipients. Hereupon, we changed our intraoperative fluid regimen to a fixed amount of 50 mL/kg body weight (BW) and questioned whether the intraoperative fluid regimen was related to this increase in fDGF. Methods: a retrospective cohort analysis of all donors and recipients in our LDKT program between January 2014–February 2017 (n = 275 pairs). Results: Univariate analysis detected various risk factors for fDGF. Dialysis dependent recipients were more likely to develop fDGF compared to pre-emptively transplanted patients (p < 0.001). Recipients developing fDGF received less intraoperative fluid (36 (25.9–50.0) mL/kg BW vs. 47 (37.3–55.6) mL/kg BW (p = 0.007)). The GDFT protocol resulted in a reduction of intraoperative fluid administration on average by 850 mL in total volume and 21% in mL/kg BW compared to our old protocol (p < 0.001). In the unadjusted analysis, a higher intraoperative fluid volume in mL/kg BW was associated with a lower risk for the developing fDGF (OR 0.967, CI (0.941–0.993)). After adjustment for the confounders, prior dialysis and the use of intraoperative noradrenaline, the relationship of fDGF with fluid volume was still apparent (OR 0.970, CI (0.943–0.998)). Conclusion: Implementation of a GDFT protocol led to reduced intraoperative fluid administration in the LDKT recipients. This intraoperative fluid restriction was associated with the development of fDGF.

The Impact of CYP3A4*22 on Tacrolimus Pharmacokinetics and Outcome in Clinical Practice at a Single Kidney Transplant Center

Background: Although there is evidence that the CYP3A4*22 variant should be considered in tacrolimus dosing in renal transplantation, its impact beyond tacrolimus dose requirements remains controversial. Methods: In a cohort of 121 kidney transplant recipients, we analyzed the CYP3A4*1B, CYP3A4*22, and CYP3A5*3 alleles and the ABCB1 variants 1236C>T, 2677G>T/A, and 3435C>T for their impact on exposure and dose requirement. Relevant clinical outcome measures such as acute rejection within the first year after transplantation, delayed graft function, and renal function at discharge (estimated glomerular filtration rate) were evaluated. Results: Extensive metabolizer (n = 17, CYP3A4*1/*1 carriers with at least one CYP3A5*1 allele) showed significantly higher tacrolimus dose requirement (P = 0.004) compared with both intermediate metabolizer (IM, n = 93, CYP3A5*3/*3 plus CYP3A4*1/*1 or CYP3A4*22 carriers plus one CYP3A5*1 allele), and poor metabolizer (n = 11, CYP3A4*22 allele in combination with CYP3A5*3/*3) after onset of therapy. Significantly higher dose requirement was observed in CYP3A5 expressers (P = 0.046) compared with non-expressers again at onset of therapy. Using the log additive genetic model, the area under the curve for the total observation period up to 16 days was significantly associated with the CYP3A5*3 genotype (P = 3.34 × 10-4) as well as with the IM or extensive metabolizer phenotype (P = 1.54 × 10-4), even after adjustment for multiple testing. Heterozygous carriers for CYP3A4*22 showed significantly higher areas under the curve than the CYP3A4*1/*1 genotype in the second week post-transplantation (adjusted P = 0.016). Regarding clinical outcomes, acute rejection was significantly associated with human leukocyte antigen mismatch (≥3 alleles; OR = 12.14, 95% CI 1.76, 525.21, P = 0.019 after correction for multiple testing). Graft recipients from deceased donors showed higher incidende of delayed graft function (OR 7.15, 95% CI 2.23, 30.46, adjusted P = 0.0008) and a lower estimated glomerular filtration rate at discharge (P = 0.0001). Tested CYP3A4 or CYP3A5 variants did not show any effects on clinical outcome parameters. ABCB1 variants did neither impact on pharmacokinetics nor on clinical endpoints. Conclusion: At our transplantation center, both CYP3A5*3 and, to a lesser extent, CYP3A4*22 affect tacrolimus pharmacokinetics early after onset of therapy with consequences for steady-state treatment in routine clinical practice.

Hesperidin Shows Protective Effects on Renal Function in Ischemia-induced Acute Kidney Injury (Sprague-Dawley Rats)

OBJECTIVE

Hesperidin is a well-known flavanone glycoside copiously found in sweet orange and lemon, which was recently reported to possess significant anti-inflammatory, analgesic, antifungal, antiviral, antioxidant, and anticancer activities. Ischemia-reperfusion (I/R) injury is a major problem after renal transplantation. Furthermore, inflammatory responses to I/R exacerbate the resultant renal injury. In the present study, we investigated whether hesperidin exhibits renoprotective effects against I/R-induced acute kidney injury in a rat model.

METHODS

We fed Sprague-Dawley rats either hesperidin (100 mg/kg/d) or saline. One week later, ischemia was induced by bilateral renal pedicle occlusion for 30 minutes followed by reperfusion. The rats were randomly divided into 3 groups, which were treated as follows: 1. the sham operated group; 2. the I/R group; 3. the I/R-hesperidin group RESULTS: Compared to the sham group, the I/R group had higher expression of blood urea nitrogen and serum creatinine and lower expression of catalase, superoxide dismutase, glutathione peroxidase, antioxidants, and nitric oxide. Compared to the I/R group, the I/R-hesperidin group had higher expression of catalase, superoxide dismutase, glutathione peroxidase, antioxidant, and nitric oxide and lower expression of blood urea nitrogen and serum creatinine.

CONCLUSIONS

Hesperidin improved acute renal I/R injury through its antioxidant effects. These findings suggest that hesperidin is a potential therapeutic agent for acute ischemia-induced renal damage.

Predictors of Acute Kidney Injury in Deceased Kidney Donors After Brain Death

BACKGROUND

Donors with acute kidney injury (AKI) are generally accepted as a valuable source of kidneys for transplant. The aim of this study was to assess the risk of developing AKI based on deceased kidney donor parameters.

MATERIALS AND METHODS

The data of 162 kidneys procured from deceased donors after brain death were collected. These included clinical characteristics of donors and histologic assessment in organ biopsy specimens. The donors' kidney terminal function was classified according to the Acute Kidney Injury Network criteria. All biopsies were performed with the use of a 16G automatic needle, and the 20-mm tissue specimen was available in all cases. Biopsy specimens were secured and prepared in a routine way with hematoxylin and eosin. The presence of chronic changes was analyzed according to the Banff 2009 classification by 1 experienced nephropathologist. The logistic regression model was used to assess the risk of AKI regarding donor characteristics and histologic findings.

RESULTS

There were 50 kidneys (30.9%) with AKI identified. The risk of AKI increased with donor age (P = .002; odds ratio [OR], 1.02; 95% CI, 1.01-1.03), body mass index (P = .003; OR, 1.05; 95% CI, 1.01-1.09), and male sex (P = .001; OR, 1.79; 95% CI, 1.31-2.27). Regarding the histologic findings, the interstitial fibrosis presence was a risk factor of AKI (P = .004; OR, 1.04; 95% CI, 1.01-1.06).

CONCLUSIONS

Older donor age, male sex, higher body mass index, and presence of interstitial fibrosis in kidney graft biopsy specimen are risk factors of AKI.

Effectiveness of Thymoglobulin Induction Therapy in Kidney Transplant From Deceased Donor With Mild to Moderate Acute Kidney Injury

BACKGROUND

The clinical benefit of rabbit antithymocyte globulin (Thymoglobulin) compared with basiliximab for induction therapy in kidney transplant (KT) resulting from acute kidney injury (AKI) donors remains controversial. In cases of severe AKI, the degree of kidney injury is too great to reveal influence of different induction therapies on clinical outcomes. We aimed to compare clinical outcomes of Thymoglobulin and basiliximab induction therapy in KTs from deceased donors (DDs) with mild to moderate AKI.

METHODS

We retrospectively studied 147 patients who received KTs from DDs between 2009 and 2017 in our center; 91 patients received kidneys from AKI donors. The AKI severity was classified based on the Acute Kidney Injury Network (AKIN) staging, and patients with AKIN stage 3 (43 patients) were excluded. Clinical outcomes were compared according to the type of induction therapy.

RESULTS

Thymoglobulin and basiliximab induction groups showed no significant differences in demographic and baseline characteristics except donor age and follow-up period. The Thymoglobulin group had lower incidences of acute rejection and a trend toward a lower incidence of delayed graft function and better graft survival than the basiliximab group. There was no significant difference in BK infection rate; however, cytomegalovirus infection rate showed a trend toward a lower incidence in the basiliximab group.

CONCLUSIONS

In cases of KT from AKIN stage 1 and 2 donors, Thymoglobulin showed better clinical outcomes than basiliximab, although it had a somewhat high rate of cytomegalovirus infection. It seems beneficial to use Thymoglobulin induction therapy in KTs from DDs with mild to moderate AKI.

Preservation Solutions for Kidney Transplantation: History, Advances and Mechanisms

Solid organ transplantation was one of the greatest medical advances during the past few decades. Organ preservation solutions have been applied to diminish ischemic/hypoxic injury during cold storage and improve graft survival. In this article, we provide a general review of the history and advances of preservation solutions for kidney transplantation. Key components of commonly used solutions are listed, and effective supplementations for current available preservation solutions are discussed. At cellular and molecular levels, further insights were provided into the pathophysiological mechanisms of effective ingredients against ischemic/hypoxic renal injury during cold storage. We pay special attention to the cellular and molecular events during transplantation, including ATP depletion, acidosis, mitochondrial dysfunction, oxidative stress, inflammation, and other intracellular mechanisms.

Effect of Seed of Cassia tora Extract in the Prevention of Remote Renal Reperfusion Injury

OBJECTIVE

Renal ischemia/reperfusion (I/R) injury is characterized by the acute deterioration of renal function during ischemia and renal inflammation. Cassia tora has various effects, including antioxidant, antidiabetic, and hypolipidemic properties. In the present study, we investigated whether C tora has a renoprotective effect on I/R-induced acute kidney injury in rats.

METHODS

We fed Sprague-Dawley rats either C tora (100 mg/kg/d) or saline. One week later, ischemia was induced by bilateral renal pedicle occlusion for 30 minutes, followed by reperfusion. Rats were randomized into 3 major groups, which were treated as follows: 1. the sham operation group; 2. the I/R group; and 3. the I/R-C tora group.

RESULTS

Compared to the sham group, the I/R group had higher levels of blood urea nitrogen and serum creatinine in serum and lower expression of catalase, superoxide dismutase, glutathione peroxidase, antioxidant, and nitric oxide. Compared to the I/R group, the I/R-C tora group had higher expression of catalase, superoxide dismutase, glutathione peroxidase, antioxidant, and nitric oxide, as well as lower levels of blood urea nitrogen and creatinine in serum.

CONCLUSIONS

These results suggest that C tora has significant therapeutic effects in ischemic renal injury.

Opioids Preconditioning Upon Renal Function and Ischemia-Reperfusion Injury: A Narrative Review

Kidneys have an important role in regulating water volume, blood pressure, secretion of hormones and acid-base and electrolyte balance. Kidney dysfunction derived from acute injury can, under certain conditions, progress to chronic kidney disease. In the late stages of kidney disease, treatment is limited to replacement therapy: Dialysis and transplantation. After renal transplant, grafts suffer from activation of immune cells and generation of oxidant molecules. Anesthetic preconditioning has emerged as a promising strategy to ameliorate ischemia reperfusion injury. This review compiles some significant aspects of renal physiology and discusses current understanding of the effects of anesthetic preconditioning upon renal function and ischemia reperfusion injury, focusing on opioids and its properties ameliorating renal injury. According to the available evidence, opioid preconditioning appears to reduce inflammation and reactive oxygen species generation after ischemia reperfusion. Therefore, opioid preconditioning represents a promising strategy to reduce renal ischemia reperfusion injury and, its application on current clinical practice could be beneficial in events such as acute renal injury and kidney transplantation.

Perfusion of Porcine Kidneys With Macromolecular Heparin Reduces Early Ischemia Reperfusion Injury

BACKGROUND

Previously, we have been able to demonstrate the possibility of coating the inner surface of the renal arteries in porcine kidneys with a heparin conjugate during hypothermic machine perfusion (HMP). The purpose of this study was to assess the efficacy of this treatment in reducing early ischemia-reperfusion injury.

METHOD

Brain death was induced in male landrace pigs by stepwise volume expansion of an epidural balloon catheter until negative cerebral perfusion pressure (CPP) was obtained. Both kidneys (matched pairs; n = 6 + 6) were preserved for 20 hours by HMP during which 50 mg heparin conjugate was added to one of the HMP systems (treated group). A customized ex vivo normothermic oxygenated perfusion (NP) system with added exogenous creatinine was used to evaluate early kidney function. Blood, urine and histological samples were collected during the subsequent 3 hours of NP.

RESULTS

Kidney weight was lower at the end of NP (P = 0.017) in the treated group compared with control kidneys. The rate of decline in creatinine level was faster (P = 0.024), total urinary volume was higher (P = 0.031), and the level of urine neutrophil gelatinase-associated lipocalin (NGAL) was lower (P = 0.031) in the treated group. Histologically, less tubular changes were seen (P = 0.046). During NP intrarenal resistance remained lower (P < 0.0001) in the treated group.

CONCLUSIONS

Perfusion of porcine kidneys with heparin conjugate during HMP reduces preservation injury and improves organ function shortly after reperfusion. No increased risk of bleeding was seen in this setup. This protective strategy may potentially improve the quality of transplanted kidneys in the clinical setting.

Limited clinical value of two consecutive post-transplant renal scintigraphy procedures

Objectives

Duration of delayed graft function (DGF) and length of hospital stay (LOS) are outcomes of interest in an era that warrants increased efficacy of transplant care whereas renal allografts originate increasingly from marginal donors. While earlier studies investigate the predictive capability of a single renal scintigraphy, this study focuses on the value for both DGF duration and LOS of consecutively performed scintigraphies.

Methods

From 2011 to 2014, renal transplant recipients referred for a Tc-99m MAG3 renal scintigraphy were included in a single-center retrospective study. Primary endpoints were DGF duration and LOS. Both the first (≤ 3 days) and second scintigraphies (3–7 days after transplantation) were analyzed using a 4-grade qualitative scale and quantitative indices (TFS, cTER, MUC10, average upslope).

Results

We evaluated 200 first and 108 (54%) consecutively performed scintigraphies. The Kaplan-Meier curves for DGF duration and qualitative grading of the first and second scintigraphy showed significant differences between the grades (p < 0.01). The Kaplan-Meier curve for the delta grades between these procedures (lower, equal, or higher grade) did not show significant differences (p = 0.18). Multivariate analysis showed a significant association between the qualitative grades, from the first and second scintigraphy, and DGF duration, HR 1.8 (1.4–2.2, p < 0.01) and 2.8 (1.8–4.3, p < 0.01), respectively.

Conclusions

Qualitative grades of single renal scintigraphies, performed within 7 days after transplantation, can be used to make a reliable image-guided decision on the need for dialysis and to predict LOS. A consecutive renal scintigraphy, however, did not show an additional value in the assessment of DGF.

Key Points

• Post-transplant renal scintigraphy procedures provide information to predict delayed graft function duration and length of hospital stay.

• Performing two consecutive renal scintigraphy procedures within 1 week after transplantation does not strengthen the prediction of delayed graft function duration and length of hospital stay.

• Single renal scintigraphy procedures can be used to provide clinicians and patients with a reliable indication of the need for dialysis after transplantation and the expected duration of hospitalization.

Electronic supplementary material

The online version of this article (10.1007/s00330-019-06334-1) contains supplementary material, which is available to authorized users.

Pretransplant Biopsy of Marginal Kidneys: Is It Necessary?

INTRODUCTION

Pretransplant kidney biopsy from marginal donors is used to guide the decision of whether to accept or discard organs for transplantation; however, there is controversy about this procedure, and the need for a pretransplant biopsy is still a debate. We sought to determine if histologic evaluation before implantation of marginal kidneys would influence the outcome.

METHODS

A retrospective observational cohort study of marginal donor transplants at Centro Hospitalar e Universitário de Coimbra was done. From 2009 to 2016, 650 marginal kidney transplants were analyzed. We evaluated long-term graft survival in a cohort of patients who received marginal kidneys. The recipients were divided into 2 groups based on whether a pretransplant donor biopsy was performed. Continuous variables were summarized by mean and standard deviation or median and range, as applicable. Categorical variables were summarized by relative and absolute frequencies. The survival analysis was obtained and plotted using the Kaplan-Meier method and compared with the log-rank test.

RESULTS

The median age of recipients and donors were statistically different between both groups (P < .001), with the donors and the recipients being younger in the group without a pretransplant biopsy. The median cold ischemia time was higher in the biopsy group (P = .01). The survival analysis showed that graft survival didn't differ between the groups (P = .2).

CONCLUSIONS

Selection of kidneys based on histological findings may not influence the graft survival and implies a higher cold ischemia time. More data are necessary to provide insight into which clinical, histologic, and biochemical parameters are necessary for decision making on kidney acceptance.

Crosstalk Between Connexin32 and Mitochondrial Apoptotic Signaling Pathway Plays a Pivotal Role in Renal Ischemia Reperfusion-Induced Acute Kidney Injury

Aims: Perioperative acute kidney injury (AKI) resulting from renal ischemia reperfusion (IR) is not conducive to the postoperative surgical recovery. Our previous study demonstrated that reactive oxygen species (ROS) transmitted by gap junction (GJ) composed of connexin32 (Cx32) contributed to AKI. However, the precise underlying pathophysiologic mechanisms were largely unknown. This study focuses on the underlying mechanisms related to ROS transmitted by Cx32 responsible for AKI aggravation. Results: In a set of in vivo studies, renal IR was found to cause severe impairment in renal tissues with massive ROS generation, which occurred contemporaneously with activation of NF-κB/p53/p53 upregulated modulator of apoptosis (PUMA)-mediated mitochondrial apoptosis pathways. Cx32 deficiency alleviated renal IR-induced AKI, and simultaneously attenuated ROS generation and distribution in renal tissues, which further inhibited NF-κB/p53/PUMA-mediated mitochondrial apoptotic pathways. Correspondingly, in a set of in vitro studies, hypoxia reoxygenation (HR)-induced cellular injury, and cell apoptosis in both human kidney tubular epithelial cells (HK-2s) and rat kidney tubular epithelial cells (NRK52Es) were significantly attenuated by Cx32 inhibitors or Cx32 gene knockdown. More importantly, Cx32 inhibition not only decreased ROS generation and distribution in human or rat kidney tubular epithelial cells but also inhibited its downstream NF-κB/p53/PUMA-mediated mitochondrial apoptotic pathway activation. Innovation and Conclusion: This is the first identification of the underlying mechanisms of IR-induced renal injury integrally which demonstrates the critical role played by Cx32 in IR-induced AKI. Moreover, GJ composed of Cx32 manipulates ROS generation and distribution between neighboring cells, and alters activation of NF-κB/p53/PUMA-mediated mitochondrial apoptotic pathways. Both inhibiting Cx32 function and scavenging ROS effectively reduce mitochondrial apoptosis and subsequently attenuate AKI, providing effective strategies for kidney protection.

Successful transplantation of kidneys from deceased donors with terminal acute kidney injury

BACKGROUND

There are many doubts with regards to accepting deceased kidneys with acute kidney injury (AKI) for transplantation.

PURPOSE

The aim of this study was to present the 5-years outcome of kidney transplantation cases where deceased donors developed AKI before organ procurement.

METHODS

Two hundred twenty-six deceased renal transplants were analyzed. Data regarding donors and recipients were collected. Terminal AKI was defined as terminal serum creatinine concentration higher than 1.99 mg/dL and 66 such cases were diagnosed. All kidney transplant recipients were followed for 60 months.

RESULTS

AKI group presented more episodes of delayed graft function (DGF) compared to the non-AKI group (56% vs 35%, p < .05). No differences were observed between the groups in the rate of acute rejection episodes, kidney function as well as patient and graft survival.

CONCLUSIONS

Transplants with AKI present more often DGF and comparable graft survival to transplants without AKI. Kidneys with AKI can be a valuable source of organs provided attentive selection and appropriate care of deceased donors.

Caspase Inhibition During Cold Storage Improves Graft Function and Histology in a Murine Kidney Transplant Model

BACKGROUND

Prolonged cold ischemia is a risk factor for delayed graft function of kidney transplants, and is associated with caspase-3-mediated apoptotic tubular cell death. We hypothesized that treatment of tubular cells and donor kidneys during cold storage with a caspase inhibitor before transplant would reduce tubular cell apoptosis and improve kidney function after transplant.

METHODS

Mouse tubular cells were incubated with either dimethyl sulfoxide (DMSO) or Q-VD-OPh during cold storage in saline followed by rewarming in normal media. For in vivo studies, donor kidneys from C57BL/6 mice were perfused with cold saline, DMSO (vehicle), or QVD-OPh. Donor kidneys were then recovered, stored at 4°C for 60 minutes, and transplanted into syngeneic C57BL/6 recipients.

RESULTS

Tubular cells treated with a caspase inhibitor had significantly reduced capsase-3 protein expression, caspase-3 activity, and apoptotic cell death compared with saline or DMSO (vehicle) in a dose-dependent manner. Treatment of donor kidneys with a caspase inhibitor significantly reduced serum creatinine and resulted in significantly less tubular cell apoptosis, BBI, tubular injury, cast formation, and tubule lumen dilation compared with DMSO and saline-treated kidneys.

CONCLUSIONS

Caspase inhibition resulted in decreased tubular cell apoptosis and improved renal function after transplantation. Caspase inhibition may be a useful strategy to prevent cold ischemic injury of donor renal grafts.

Lower rate of delayed graft function is observed when epidural analgesia for living donor nephrectomy is administered

Background

The beneficial effects of epidural analgesia (EDA) in terms of pain control and postoperative convalescence are widely known and led to a frequent use for patients who underwent living donor kidney nephrectomy. The objective of this study was to determine whether general anesthesia (GA) plus EDA compared to GA only, administered for living donor nephrectomy has effects on postoperative graft function in recipients.

Methods

In this monocentric, retrospective cohort analysis we analyzed the closed files of all consecutive donor- recipient pairs who underwent living donor kidney transplantations from 2008 to 2017. The outcome variable was delayed graft function (DGF), defined as at least one hemodialysis within seven days postoperatively, once hyperacute rejection, vascular or urinary tract complications were ruled out. Statistical analyses of continuous variables were calculated using the two-tail Student’s t test and Fisher exact test for categorical variables with a significance level of p < 0.05, respectively.

Results

The study enclosed 291 consecutive living donor kidney transplantations. 99 kidney donors received epidural analgesia whereas 192 had no epidural analgesia. The groups showed balanced pretransplantational characteristics and comparable donors´ and recipients’ risk factors. 9 out of all 291 recipients needed renal replacement therapy (RRT) during the first 7 days due to delayed graft function; none of these donors received EDA. The observed rate of DGF in recipients whose kidney donors received epidural analgesia was significantly lower (0% vs. 4.6%; p = 0.031).

Conclusions

In our cohort we observed a significantly lower rate of DGF when epidural analgesia for donor nephrectomy was administered. Due to restrictions of the study design this observation needs further confirmation by prospective studies.

Regulated necrosis in kidney ischemia-reperfusion injury

Ischemia-reperfusion injury (IRI) is the outcome of an inflammatory process that is triggered when an organ undergoes a transient reduction or cessation of blood flow, followed by re-establishment of perfusion. In the clinical setting, IRI contributes to significant acute kidney injury, patient morbidity and mortality, and adverse outcomes in transplantation. Tubular cell death by necrosis and apoptosis is a central feature of renal IRI. Recent research has challenged traditional views of cell death by identifying new pathways in which cells die in a regulated manner but with the morphologic features of necrosis. This regulated necrosis (RN) takes several forms, with necroptosis and ferroptosis being the best described. The precise mechanisms and relationships between the RN pathways in renal IRI are currently the subject of active research. The common endpoint of RN is cell membrane rupture, resulting in the release of cytosolic components with subsequent inflammation and activation of the immune system. We review the evidence and mechanisms of RN in the kidney following renal IRI, and discuss the use of small molecule inhibitors and genetically modified mice to better understand this process and guide potentially novel therapeutic interventions.

A urinary microRNA panel that is an early predictive biomarker of delayed graft function following kidney transplantation

Predicting immediate and subsequent graft function is important in clinical decision-making around kidney transplantation, but is difficult using available approaches. Here we have evaluated urinary microRNAs as biomarkers in this context. Profiling of 377 microRNAs in the first urine passed post-transplantation identified 6 microRNAs, confirmed to be upregulated by RT-qPCR in an expanded cohort (miR-9, -10a, -21, -29a, -221, and -429, n = 33, P < 0.05 for each). Receiver operating characteristic analysis showed Area Under the Curve 0.94 for this panel. To establish whether this early signal was sustained, miR-21 was measured daily for 5 days post-transplant, and was consistently elevated in those developing Delayed Graft Function (n = 165 samples from 33 patients, p < 0.05). The biomarker panel was then evaluated in an independent cohort, sampled at varying times in the first week post-transplantation in a separate transplant center. When considered individually, all miRs in the panel showed a trend to increase or a significant increase in those developing delayed Graft Function (miR-9: P = 0.068, mIR-10a: P = 0.397, miR-21: P = 0.003, miR-29a: P = 0.019, miR-221: P = 0.1, and miR-429: P = 0.013, n = 47) with Area Under the Curve 0.75 for the panel. In conclusion, combined measurement of six microRNAs had predictive value for delayed graft function following kidney transplantation.

Enhanced immunosuppression improves early allograft function in a porcine kidney transplant model of donation after circulatory death

It remains controversial whether renal allografts from donation after circulatory death (DCD) have a higher risk of acute rejection (AR). In the porcine large animal kidney transplant model, we investigated the AR and function of DCD renal allografts compared to the non-DCD renal allografts and the effects of increased immunosuppression. We found that the AR was significantly increased along with elevated MHC-I expression in the DCD transplants receiving low-dose immunosuppression; however, AR and renal function were significantly improved when given high-dose immunosuppressive therapy postoperatively. Also, high-dose immunosuppression remarkably decreased the mRNA levels of ifn-g, il-6, tgf-b, il-4, and tnf-a in the allograft at day 5 and decreased serum cytokines levels of IFN-g and IL-17 at day 4 and day 5 after operation. Furthermore, Western blot analysis showed that higher immunosuppression decreased phosphorylation of signal transducer and activator of transcription 3 and nuclear factor kappa-light-chain-enhancer of activated B cells-p65, increased phosphorylation of extracellular-signal-regulated kinase, and reduced the expression of Bcl-2-associated X protein and caspase-3 in the renal allografts. These results suggest that the DCD renal allograft seems to be more vulnerable to AR; enhanced immunosuppression reduces DCD-associated AR and improves early allograft function in a preclinical large animal model.

Variability in the leptin receptor gene and other risk factors for post-transplant diabetes mellitus in renal transplant recipients

Aim: Post-transplant diabetes mellitus (PTDM) is one of the main complications after kidney transplantation. It is known that leptin plays an important role in glucose metabolism and mutations in the leptin receptor gene (LEPR) are responsible for different complications in renal transplant recipients. We aimed to analyse the association of polymorphisms in LEPR with the development of PTDM in these patients. Methods: A total of 315 renal transplant recipients were genotyped for the Lys109Arg, Gln223Arg and Lys656Asn polymorphisms. The impact of these genetic variables together with other clinical and demographic parameters on PTDM risk was evaluated in a multivariate regression analysis. Results: The 223Arg variant showed a significant association with PTDM risk [OR = 3.26 (1.35-7.85), p = 0.009] after correcting for multiple testing. Carriers of this variant also showed higher BMI values (26.95 ± 4.23) than non-carriers (25.67 ± 4.43, p = 0.025). In addition, it was BMI at transplant and not the BMI increment in the first year after grafting that was associated with PTDM (p > 0.00001). Haplotype analyses did not reveal significant associations. Conclusions: Our result show, for the first time to our knowledge, that genetic variability in the LEPR may contribute significantly to the risk for PTDM in renal transplant recipients. KEY MESSAGES The LEPR Gln223Arg polymorphism significantly contributes to the development of PTDM in renal transplant recipients. The effect of the 223Arg variant on PTDM is strongly modulated by the age of the recipient. The 223Arg variant in the leptin receptor is related to higher BMI in renal transplant recipients.

P-NGAL Day 1 predicts early but not one year graft function following deceased donor kidney transplantation - The CONTEXT study

BACKGROUND

Early markers to predict delayed kidney graft function (DGF) may support clinical management. We studied the ability of four biomarkers (neutrophil gelatinase associated lipocalin (NGAL), liver-type fatty acid-binding protein (L-FABP), cystatin C, and YKL-40) to predict DGF after deceased donor transplantation, and their association with early graft function and GFR at three and twelve months.

METHODS

225 deceased donor kidney transplant recipients were included. Biomarkers were measured using automated assays or ELISA. We calculated their ability to predict the need for dialysis post-transplant and correlated with the estimated time to a 50% reduction in plasma creatinine (tCr50), measured glomerular filtration rate (mGFR) and estimated GFR (eGFR).

RESULTS

All biomarkers measured at Day 1, except urinary L-FABP, significantly correlated with tCr50 and mGFR at Day 5. Plasma NGAL at Day 1 and a timed urine output predicted DGF (AUC = 0.91 and AUC 0.98). Nil or only weak correlations were identified between early biomarker levels and mGFR or eGFR at three or twelve months.

CONCLUSION

High plasma NGAL at Day 1 predicts DGF and is associated with initial graft function, but may not prove better than P-creatinine or a timed urine output. Early biomarker levels do not correlate with one-year graft function.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01395719.

Beneficial Effect of Moderately Increasing Hypothermic Machine Perfusion Pressure on Donor after Cardiac Death Renal Transplantation

Background:

Vascular resistance and flow rate during hypothermic machine perfusion (HMP) of kidneys is correlated with graft function. We aimed to determine the effects of increasing HMP pressure versus maintaining the initial pressure on kidney transplantation outcomes.

Methods:

We retrospectively reviewed the data of 76 primary transplantation patients who received HMP-preserved kidneys from 48 donors after cardiac death between September 1, 2013, and August 31, 2015. HMP pressure was increased from 30 to 40 mmHg (1 mmHg = 0.133 kPa) in kidneys with poor flow and/or vascular resistance (increased pressure [IP] group; 36 patients); otherwise, the initial pressure was maintained (constant pressure group; 40 patients). Finally, the clinical characteristics and transplantation outcomes in both groups were assessed.

Results:

Delayed graft function (DGF) incidence, 1-year allograft, patient survival, kidney function recovery time, and serum creatinine level on day 30 were similar in both groups, with improved flow and resistance in the IP group. Among patients with DGF, kidney function recovery time and DGF duration were ameliorated in the IP group. Multivariate logistic regression analysis revealed that donor hypertension (odds ratio [OR]: 1.43, 95% confidence interval [CI]: 1.02–2.06, P = 0.035), donor terminal serum creatinine (OR: 1.27, 95% CI: 1.06–1.62, P = 0.023), warm ischemic time (OR: 3.45, 95% CI: 1.97–6.37, P = 0.002), and terminal resistance (OR: 3.12, 95% CI: 1.76–6.09, P = 0.012) were independent predictors of DGF. Cox proportional hazards analysis showed that terminal resistance (hazard ratio: 2.06, 95% CI: 1.32–5.16, P = 0.032) significantly affected graft survival.

Conclusion:

Increased HMP pressure improves graft perfusion but does not affect DGF incidence or 1-year graft survival.

Increased soluble fms-like tyrosine kinase 1 after ischemia reperfusion contributes to adverse clinical outcomes following kidney transplantation

Renal ischemia reperfusion injury (IRI) adversely affects clinical outcomes following kidney transplantation. Understanding the cellular mechanisms and the changes in gene/protein expression following IRI may help to improve these outcomes. Serum soluble fms-like tyrosine kinase 1 (sFlt-1), a circulating antiangiogenic protein, is increased in the first week following kidney transplantation. We evaluated the casual relationship of elevated sFlt-1 levels with renal microvascular dysfunction following IRI in a longitudinal study of 93 kidney transplant recipients and in several animal models. Transplant recipients with higher sFlt-1 levels had higher odds of delayed graft function, graft rejection, impaired graft function, and death. In a subgroup of 25 participants who underwent kidney biopsy within 4 months of kidney transplantation, peritubular capillary area was lower in those with elevated serum sFtl-1 levels. The administration of recombinant sFlt-1 into rodents resulted in significant structural and functional changes of the renal microvasculature, including reduced peritubular capillary density and intracapillary blood volume, and lead to increased expression of inflammatory genes and increased fibrosis. In a murine model of IRI, the kidney was a site of sFlt-1 production, and systemic neutralization of sFlt-1 preserved peritubular capillary density and alleviated renal fibrosis. Our data indicate that high sFlt-1 levels after IRI play an important role in the pathogenesis of microvascular dysfunction, thereby contributing to adverse clinical outcomes following kidney transplantation.