Delayed graft function: current status and future directions

Severe ischemia-reperfusion injury induces epigenetic inactivation of LHX1 in kidney progenitor cells after kidney transplantation

Severe ischemia-reperfusion injury (IRI) causes acute and chronic kidney allograft damage. As therapeutic interventions to reduce damage are limited yet, research on how to promote kidney repair has gained significant interest. To address this question, we performed genome-wide transcriptome and epigenome profiling in progenitor cells isolated from the urine of deceased (severe IRI) and living (mild IRI) donor human kidney transplants and identified LIM homeobox-1 (LHX1) as an epigenetically regulated gene whose expression depends on the IRI severity. Using a mouse model of IRI, we observed a relationship between IRI severity, LHX1 promoter hypermethylation, and LHX1 gene expression. Using functional studies, we confirmed that LHX1 expression is involved in the proliferation of epithelial tubular cells and podocyte differentiation from kidney progenitor cells. Our results provide evidence that severe IRI may reduce intrinsic mechanisms of kidney repair through epigenetic signaling.

Assessing donor kidney function: the role of CIRBP in predicting delayed graft function post-transplant

Introduction

Delayed graft function (DGF) shortens the survival time of transplanted kidneys and increases the risk of rejection. Current methods are inadequate in predicting DGF. More precise tools are required to assess kidney suitability for transplantation. Cold-inducible RNA-binding protein (CIRBP) expression has been linked to acute kidney injury, suggesting its potential as a new biomarker for transplanted kidney function.

Methods

We included deceased donors and recipients who had undergone successful kidney transplantation between 2016 and 2019. Recipients and their paired donors are assigned to either the DGF or immediate graft function (IGF) group, based on the recipient's recovery of graft renal function. Donor plasma CIRBP levels were measured using an enzyme-linked immunosorbent assay kit to assess their relationships with DGF.

Results

Donor plasma CIRBP concentrations in the DGF group were approximately twice as high as those in the IGF group (6.82 vs. 3.44; P<0.001). DGF occurred in all cases where CIRBP concentrations exceeded 7.92 ng/mL. Furthermore, univariate and multivariate analyses (odds ratio [OR]=1.660; P<0.001) confirmed that donor plasma CIRBP level was an independent risk factor for DGF. Additionally, higher CIRBP levels were associated with increased plasma creatinine at 6 months (R²=0.08; P<0.001), and survival analysis showed shorter kidney survival in recipients with DGF (P=0.002).

Conclusions

This study demonstrated that donor plasma CIRBP levels can effectively predict the occurrence of DGF. CIRBP is a potential novel biomarker for evaluating transplanted kidney function.

Clinical trial registration

https://clinicaltrials.gov, identifier NCT06641622.

Assessing Pharmacokinetics and Safety of Therapeutic Alpha-1-Microglobulin in First-in-Human Kidney Transplantation: A Noncomparative Open-Label Multiple-Dose Phase 1b Study

Background

RMC-035 is a modified version of alpha-1-microglobulin, an endogenous protein developed as a renoprotective agent. Its intended use is to reduce the risk of irreversible loss of kidney function in cardiac surgery patients and to reduce delayed graft function in kidney transplant recipients. This first-in-human study aimed to evaluate the pharmacokinetics and safety of RMC-035 in kidney transplant recipients.

Methods

Eight living-donor kidney transplant recipients were included in 2 dose cohorts. The study drug RMC-035 was administered starting with the first dose during transplantation. Four additional doses were administered once daily following transplantation. In the first cohort, all 5 doses of RMC-035 were equal, whereas in the second cohort, the last 3 doses were doubled. Safety monitoring, laboratory tests, and pharmacokinetic measurements were performed according to protocol for 4 d post-transplantation and during the 90-d follow-up period.

Results

All 5 administrations of the study drug were completed in 5 out of 8 treated participants. Pharmacokinetic concentrations were approximately dose proportional, and AUC0-24h decreased between the first and fifth doses, reflecting improved kidney function and RMC-035 renal clearance over time. No accumulation was observed between the administrations. No clinically significant changes were observed in the hematological or biochemical laboratory parameters, electrocardiogram findings, or vital signs. A total of 22 treatment-emergent adverse events (AEs) were reported in 6 subjects. Mild and transient AEs suggestive of infusion-related reactions, such as chills, were reported in 5 patients. There was a clinically significant reduction in serum creatinine levels, reflecting post-transplant improvement in kidney function.

Conclusions

Based on the safety data obtained from 8 subjects in the 2 dose cohorts treated with RMC-035, the drug was considered safe. Safety and AE profiles were in line with expectations of the target population, and infusion-related reactions were short-lived and manageable. Dose-limiting toxicity signals were not observed.

Histopathological Features and Role of Allograft Kidney Biopsy Among Recipients With Prolonged Delayed Graft Function: A Review

Delayed graft function (DGF) is an early posttransplant complication predictive of adverse outcomes. This "acute kidney injury of transplantation" is often defined as allograft dysfunction requiring renal replacement within 7 d posttransplantation. DGF is an important area of study because it is emerging with efforts to expand the donor pool and address the supply-demand gap in kidney transplantation. DGF is often caused by severe kidney injury mechanisms because of multiple donors, recipients, and immunologic factors. The role of kidney biopsy, particularly in prolonged DGF, is an ongoing area of research and inquiry for clinicians and researchers alike to better define, manage, and predict outcomes of this early posttransplant event. This review aims to provide an in-depth, comprehensive summary of the literature to date on the histopathology of DGF and the role of kidney transplant biopsies in prolonged DGF.

Intraoperative Mean Arterial Pressure and Postoperative Delayed Graft Function in Kidney Transplantation: Evaluating Three Commonly Used Thresholds

BACKGROUND

Delayed graft function (DGF) is a common early complication after kidney transplantation (KT) and is associated with various long-term adverse outcomes. Despite numerous studies on hemodynamic management, the optimal hemodynamic goals during KT remain unclear. In this retrospective study, we aimed to investigate if three mean artery pressure (MAP) thresholds (≤75, 80, and 85 mmHg) that were commonly used in clinical practice were associated with DGF in adult patients undergoing KT.

METHODS

We extracted de-identified data on adult patients who underwent deceased donor KT from our Discovery Data Repository. DGF was defined as the requirement for dialysis within the first 7 days after transplantation. Three MAP thresholds (≤75, 80, and 85 mmHg) and the duration of pressure below the three thresholds were recorded. Multivariable logistic analysis was used to identify risk factors for DGF.

RESULTS

We included 2301 adult KT patients. The mean age was 52.5±12.9 years and 59% were male. DGF occurred in 1066 patients (46.3%). Patients frequently experienced MAP ≤75, 80, and 85 mmHg (approximately 70%, 80%, and 90% of patients experienced 10 min of MAP ≤75, 80, and 85 mmHg, respectively). Patients with DGF spent significantly longer durations below the three MAP thresholds during surgery compared with those without DGF. Further analysis revealed that the minimal time spent on MAP ≤75, 80, and 85 mmHg that were significantly associated with DGF were 6, 23, and 37 min, respectively. After adjusting for non-hemodynamic risk factors (age, basiliximab administration, and urine output), prolonged exposure to the three MAP thresholds remained significant predictors for DGF (for MAP ≤75 mmHg, OR 1.257, 95% CI 1.017-1.554, p = 0.034; MAP ≤80 mmHg, OR 1.220, 95% CI 1.018-1.463, p = 0.031; MAP ≤85 mmHg, OR 1.253, 95% CI 1.048-1.498, p = 0.013).

CONCLUSION

Prolonged exposure to the three common MAP thresholds (≤75, 80, and 85 mmHg) occurred frequently during adult deceased donor KT and was associated with DGF.

Case report: Bruton tyrosine kinase inhibitor as therapy for chronic lymphocytic leukemia infiltrating a kidney allograft

The burden of chronic lymphocytic leukemia (CLL) in the prognosis of solid organ transplant (SOT) recipients seems non-negligible. Whether transplanting a patient with previous CLL is safe or what is the optimal monitoring and treatment management after transplantation is still unclear and only based on few case series and reports. Therefore, we aimed to contribute to this understanding by reporting the first documented case of a clinically significant CLL with biopsy-proven infiltration of the kidney allograft and its successful management with a Bruton tyrosine kinase inhibitor (BTKi). We then reviewed the related literature, with a focus on CLL and kidney transplantation. Our main message is that BTKi may represent a safe and effective intervention to prevent the hazardous patient and graft outcomes of CLL in SOT patients.

Deceased Kidney Donor Biomarkers: Relationship between Delayed Kidney Function and Graft Function Three Years after Transplantation

With an increasing number of marginal donors, additional methods for the evaluation of cadaveric kidney quality are required. This study aimed to evaluate pretransplant deceased donor serum (s) and urine (u) biomarkers, including neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), interleukin-18, and C-X-C motif chemokine 10 (CXCL10) for predicting early and late graft function. In total, 43 deceased kidney donors and 76 corresponding recipients were enrolled. Delayed graft function (DGF) occurred in 27.6% of cases. sIL-18, sKIM-1, uNGAL, and uKIM-1 were predictors of DGF. A model incorporating sIL-18, uKIM-1, and clinical factors was developed to predict DGF (AUROC 0.863). Univariate analysis showed a negative association between uKIM and graft eGFR at 6, 12, 24, and 36 months, but this was not confirmed in the multivariate analysis. In conclusion, we report a superior performance of donor biomarkers for predicting DGF and later graft function over serum creatinine. Higher levels of donor sIL-18 and uKIM in conjunction with expanded-criteria donors and longer cold ischemia times predicted DGF. With no renal tubular damage in zero-time donor biopsies, higher pretransplant urine and serum NGAL levels were associated with better allograft function one year after transplantation, and sNGAL with graft function three years after transplantation.

Prevention of Delayed Graft Function in Kidney Transplant Recipients through a Continuous Infusion of the Prostaglandin Analogue Iloprost: A Single-Center Prospective Study

BACKGROUND

Delayed graft function (DGF) is common after kidney transplantation from deceased donors and may significantly affect post-transplant outcomes. This study aimed to evaluate whether an innovative approach, based on the administration of the intravenous prostaglandin analogue iloprost, could be beneficial in reducing the incidence of DGF occurring after kidney transplantation from deceased donors.

METHODS

This prospective, randomized (1:1), placebo-controlled study enrolled all consecutive patients who received a kidney transplant from a deceased donor from January 2000 to December 2012 and who were treated in the peri-transplant period with the prostaglandin analogue iloprost at 0.27 μg/min through an elastomeric pump (treatment group) or with a placebo (control group).

RESULTS

A total of 476 patients were included: DGF was reported in 172 (36.1%) patients in the entire cohort. The multivariate analysis showed that the donor's age > 70 years (OR 2.50, 95% confidence interval (CI): 1.40-3.05, p < 0.001), cold ischemia time > 24 h (OR 2.60, 95% CI: 1.50-4.51, p < 0.001), the donor's acute kidney injury (OR 2.71, 95% CI: 1.61-4.52, p = 0.021) and, above all, the recipient's arterial hypotension (OR 5.06, 95% CI: 2.52-10.1, p < 0.0001) were the strongest risk factors for developing post-transplant DGF. The incidence of DGF was 21.4% in the treatment group and 50.9% in the control group (p < 0.001). Interestingly, among patients who developed DGF, those who received iloprost had a shorter duration of post-transplant DGF (10.5 ± 8.3 vs. 13.4 ± 6.7, days, p = 0.016).

CONCLUSIONS

This study showed that the use of a continuous infusion of iloprost could safely and effectively reduce the incidence of DGF in recipients of deceased-donor kidneys, allowing a better graft functionality as well as a better graft survival.

Impact of T Lymphocytes Isolated from Liver Perfusate of Deceased Brain Donors on Kidney Transplantation: Preliminary Evidence and Future Directions

BACKGROUND

Ischemia/reperfusion injury (IRI), acute rejection (AR), and delayed graft function (DGF) might occur as major complications following kidney transplantation. Thus, the identification of biomarkers for the IRI, AR, and/or DGF development becomes crucial as it may help to guide post-transplant management. Natural killer (NK) cells, hepatic interstitial T-lymphocytes (T-Li), and NK-T cells are crucial in both innate and adaptive immunity after abdominal solid organ transplantation. Hence, the aim of this study was to evaluate the impact of the immune system after graft reperfusion during KT in adults in order to identify predictive biomarkers.

METHODS

The NK, T-Li, and NK-T phenotypes and concentrations were retrospectively analyzed in a consecutive series of liver perfusates obtained after organ procurement flushing the abdominal cavity recovered from deceased brain donors (DBDs). Their percentage was compared with the renal transplant recipients' characteristics with kidneys taken from the same DCDs. The hepatic perfusate cells were purified by density gradient centrifugation. Flow cytometric investigation was used to determine their phenotype with the following immunological markers in order to determine the relative percentage of T-Li, NK-T, and NK cells: CD3, CD4, CD8, and CD56.

RESULTS

42 DBDs' liver perfusates were analyzed. The related clinical outcomes of kidney transplant recipients from 2010 to 2020 performed at our Institute were evaluated. Time in days of delayed functional recovery of transplanted kidneys (DGF) (p = 0.02) and the onset of secondary infection from a cytomegalovirus (p = 0.03) were significantly associated with the T-Li percentage. An increased relative risk (HR) of organ survival was significantly associated with the percent cell concentration of T-Li and time to DGF, on COX analysis, were (HR = 1.038, p = 0.04; and HR = 1.029, p = 0.01, respectively). None relevant clinical outcomes in kidney transplant patients were associated with the specificity of the NK and NK-T cell proportions.

CONCLUSIONS

A new potential role of T-Li cells was detected in the context of hepatic perfusate from DBDs. It could detect potential impacts in organ allocation, surgical procuring techniques, and in the analysis of IRI pathophysiological events.