Delayed Graft Function, Predictive Factors, and 7-Year Outcome of Deceased Donor Kidney Transplant Recipients With Different Immunologic Profiles

Seeking Standardized Definitions for HLA-incompatible Kidney Transplants: A Systematic Review

BACKGROUND

There is no standard definition for "HLA incompatible" transplants. For the first time, we systematically assessed how HLA incompatibility was defined in contemporary peer-reviewed publications and its prognostic implication to transplant outcomes.

METHODS

We combined 2 independent searches of MEDLINE, EMBASE, and the Cochrane Library from 2015 to 2019. Content-expert reviewers screened for original research on outcomes of HLA-incompatible transplants (defined as allele or molecular mismatch and solid-phase or cell-based assays). We ascertained the completeness of reporting on a predefined set of variables assessing HLA incompatibility, therapies, and outcomes. Given significant heterogeneity, we conducted narrative synthesis and assessed risk of bias in studies examining the association between death-censored graft failure and HLA incompatibility.

RESULTS

Of 6656 screened articles, 163 evaluated transplant outcomes by HLA incompatibility. Most articles reported on cytotoxic/flow T-cell crossmatches (n = 98). Molecular genotypes were reported for selected loci at the allele-group level. Sixteen articles reported on epitope compatibility. Pretransplant donor-specific HLA antibodies were often considered (n = 143); yet there was heterogeneity in sample handling, assay procedure, and incomplete reporting on donor-specific HLA antibodies assignment. Induction (n = 129) and maintenance immunosuppression (n = 140) were frequently mentioned but less so rejection treatment (n = 72) and desensitization (n = 70). Studies assessing death-censored graft failure risk by HLA incompatibility were vulnerable to bias in the participant, predictor, and analysis domains.

CONCLUSIONS

Optimization of transplant outcomes and personalized care depends on accurate HLA compatibility assessment. Reporting on a standard set of variables will help assess generalizability of research, allow knowledge synthesis, and facilitate international collaboration in clinical trials.

Delayed Graft Function Duration in Deceased Donor Kidney Transplants

BACKGROUND

Delayed graft function (DGF) is an important prognostic indicator after kidney transplantation. Depending on the severity of the ischemia-reperfusion injury, DGF can have several clinical presentations, with different renal function recovery times. Both the presence and duration of DGF can have an impact on kidney transplantation outcomes. However, the definition of the cutoff point, above which the outcomes are worse, varies widely in the literature.

METHODS

To investigate the impact of DGF and its duration on patient and graft survivals, a single-center retrospective study including all deceased donor kidney transplants was performed between November 2008 and December 2015 (n = 188). Through the analysis on the receiver operating characteristic curve, the cutoff point that determined the worst outcome was reached. DGF patients were then divided according to the duration of DGF (<8 days or ≥8 days).

RESULTS

The overall incidence of DGF was 62.2%. Higher HLA mismatches was an independent risk factor for prolonged DGF. DGF ≥8 days was associated with acute rejection and this one was associated with patient death in 3 years.

CONCLUSION

DGF with a duration of more than 8 days associated with higher HLA mismatches increases the risk of acute rejection, but graft loss and patient survival are not affected by DGF, regardless of its duration.

Comparative analysis of kidney transplant costs related to recovery of renal function after the procedure

Introduction:

The number of kidney transplants (KTx) is increasing in Brazil and, consequently, the costs of this procedure increase the country's health budget. We retrospectively evaluated the data of kidney transplant procedures until hospital discharge, according to kidney function recovery after the procedure.

Methods:

Retrospective analysis of the non-sensitized, 1st KTx from deceased donors performed between Jan/2010 to Dec/2017.

Results:

Out of the 1300 KTx from deceased donors performed in this period, 730 patients were studied and divided into 3 groups: Immediate Renal Function (IRF) - decrease in serum creatinine ≥ 10% on two consecutive days; Delayed Graft Function (DGF) - decrease in serum creatinine <10% on two consecutive days, without the need for dialysis, and Dialysis (D) - need for dialysis during the first week. Patients in group D stayed longer in the hospital compared to DGF and IRF (21, 11 and 8 days respectively, p < 0.001). More D patients (21%) were admitted to the ICU and performed a greater number of laboratory tests (p < 0.001) and renal biopsies (p < 0.001), in addition to receiving a higher amount of immunosuppressants. Total hospital costs were higher in group D and DGF compared to IRF (U$ 7.021,48; U$ 3.603,42 and U$ 2.642,37 respectively, p < 0.001).

Conclusion:

The costs of the transplant procedure is impacted by the recovery of kidney function after the transplant. The reimbursement for each of these different kidney function outcomes should be individualized in order to cover their real costs.

Effect of Delayed Graft Function on the Outcome and Allograft Survival of Kidney Transplanted Patients from a Deceased Donor

BACKGROUND

In kidney transplantation (KT), delayed graft function (DGF) is a significant early complication observed in the first week. The study aimed to investigate the impact of DGF on the outcome, allograft, and patient survival after KT with organs from deceased donors.

METHODS

This retrospective study was conducted using 304 KT patients who received an organ from deceased donors from 2008 to 2018. The patients were divided into 2 groups, DGF positive (DGF⁺) and DGF negative (DGF^-). The database containing the clinical, laboratory, and immunologic information of donors and recipients was statistically analyzed using the SSPS program.

RESULTS

In this study, 189 (62.17%) were DGF⁺ and 115 (37.83%) were DGF^-. Until 6 months after KT, the estimate glomerular filtration rate was better in group DGF^-, but it was similar between the groups during 10-year follow-up. Graft losses were higher in DGF⁺ group than in the DGF^- (P = .046). The serum creatinine level was persistently higher in DGF⁺ group until the sixth month (P ≤ .05). Allograft survival rates were better in patients who were DGF^- (P = .033). Those who had DGF for more than 15 days had a worse graft survival (P = .003), but in 10 year follow-up, patient survival rates were similar (P = .705).

CONCLUSION

DGF⁺ patients were associated with dialysis time before KT, ischemia time, and the donors' clinical status, such as age, organ quality, and serum creatinine. All these factors had a great impact on graft survival but not on patient survival.

Exploring the causes of the high incidence of delayed graft function after kidney transplantation in Brazil: a multicenter study

This retrospective multicenter (n = 18) cohort study evaluated the incidence, risk factors, and the impact of delayed graft function (DGF) on 1-year kidney transplant (KT) outcomes. Of 3992 deceased donor KT performed in 2014-2015, the incidence of DGF was 54%, ranging from 29.9% to 87.7% among centers. Risk factors (_{lower-bound-95%CI} OR _{upper-bound-95%CI} ) were male gender (_1.066 1.249_1.463 ), diabetic kidney disease (_1.053 1.296_1.595 ), time on dialysis (_1.005 1.007_1.009 ), retransplantation (_1.035 1.397_1.885 ), preformed anti-HLA antibodies (_1.011 1.383_1.892 ), HLA mismatches (_1.006 1.066_1.130 ), donor age (_1.011 1.017_1.023 ), donor final serum creatinine (sCr) (_1.239 1.317_1.399 ), cold ischemia time (CIT) (_1.031 1.043_1.056 ), machine perfusion (_0.401 0.542_0.733 ), and induction therapy with rabbit antithymocyte globulin (rATG) (_0.658 0.800_0.973 ). Duration of DGF > 4 days was associated with inferior renal function and DGF > 14 days with the higher incidences of acute rejection, graft loss, and death. In conclusion, the incidence and duration of DGF were high and associated with inferior graft outcomes. While late referral and poor donor maintenance account for the high overall incidence of DGF, variability in donor and recipient selection, organ preservation method, and type of induction agent may account for the wide variation observed among transplant centers.

The Impact of Hypothermic Pulsatile Machine Perfusion Versus Static Cold Storage: A Donor-Matched Paired Analysis in a Scenario of High Incidence of Delayed Kidney Graft Function

BACKGROUND The present study analyzed the impact of hypothermic pulsatile machine perfusion (MP) following a long period of static cold (SC) storage in the peculiar Brazilian scenario of high incidence of delayed graft function (DGF), despite good donor characteristics. MATERIAL AND METHODS A retrospective analysis, with a 1-year follow-up, of 206 recipients of donor-matched paired kidneys was performed. Of the 206 donor kidneys, 103 were maintained exclusively in static cold storage (SC group) and 103 were kept on machine perfusion after a period of SC preservation (MP group). All donors were brain dead. RESULTS Only 4.9% of the kidneys were from expanded-criteria donors. Static cold ischemia time (CIT) in the SC group was 20.8±4.1 hours vs. 15.8±6.2 hours in the MP group (P<0.001). Dynamic CIT in the MP group was 12.3±5.7 hours. MP significantly reduced DGF incidence (29.1% vs. 55.3%, P<0.001), and this effect was confirmed in multivariable analysis (OR, 1.115; 95% CI, 1.033-1.204, P=0.001). No differences were observed between the groups with regard to DGF duration, length of hospital stay, incidence of primary nonfunction and acute rejection, graft loss, death, or renal function. CONCLUSIONS In this Brazilian setting, MP following a long period of SC preservation was associated with reduced DGF incidence in comparison with SC storage without MP.

Persistent BK Polyomavirus Viruria is Associated with Accumulation of VP1 Mutations and Neutralization Escape

To investigate the relationship between neutralization escape and persistent high-level BK polyomavirus replication after kidney transplant (KTx), VP1 sequences were determined by Sanger and next-generation sequencing in longitudinal samples from KTx recipients with persistent high-level viruria (non-controllers) compared to patients who suppressed viruria (controllers). The infectivity and neutralization resistance of representative VP1 mutants were investigated using pseudotype viruses. In all patients, the virus population was initially dominated by wild-type VP1 sequences, then non-synonymous VP1 mutations accumulated over time in non-controllers. BC-loop mutations resulted in reduced infectivity in 293TT cells and conferred neutralization escape from cognate serum in five out of six non-controller patients studied. When taken as a group, non-controller sera were not more susceptible to neutralization escape than controller sera, so serological profiling cannot predict subsequent control of virus replication. However, at an individual level, in three non-controller patients the VP1 variants that emerged exploited specific “holes” in the patient’s humoral response. Persistent high-level BK polyomavirus replication in KTx recipients is therefore associated with the accumulation of VP1 mutations that can confer resistance to neutralization, implying that future BKPyV therapies involving IVIG or monoclonal antibodies may be more effective when used as preventive or pre-emptive, rather than curative, strategies.

Effect of Perioperative Optimization of Arterial Oxygen Content and Perfusion Pressure on the Function of the Transplanted Kidney in the Retrospective Study of Excretory Function and Assessment of New Markers of Kidney Damage: IL-18, Neutrophil Gelatinase-Associated Lipocalin, and Clusterin

INTRODUCTION

The concept of anesthesia, in which kidney perfusion is optimized, the use of nephrotoxic drugs is avoided, and general anesthesia with protective and preconditioning properties of the graft is applied, is a key element of the therapeutic strategy in kidney transplantation (KTx).

MATERIAL AND METHOD

A total of 86 patients (mean age: 49.4 ± 14.0 years, 66% men) with end-stage renal disease who underwent KTx between 2012 and 2015 were included in this retrospective study. Our aim was to assess the effect of oxygen content in arterial blood and selected hemodynamic parameters on the graft function and the occurrence of delayed graft failure.

RESULTS

No differences were found in baseline characteristics, indication for transplantation, and surgical technique used among study population. No correlation was found between oxygen delivery exponents and both standard markers of renal function and new biochemical markers (eg, IL-18, clusterin, and neutrophil gelatinase-associated lipocalin [NGAL]).

DISCUSSION

In our study, hemodynamic parameters measured at scheduled intervals did not exceed the physiological range, which might have been the reason for the lack of correlation between the function of graft and the described hemodynamic conditions. At the same time, in the observed ranges of perfusion pressure during optimization of the oxygen content, no correlations were found with the postoperative function of the transplanted kidney. That observation could be a valuable conclusion for reducing the tendency of maintaining high blood pressure with the abuse of catecholamines, especially vasoconstrictors, and volume therapy, whose negative effect on tissue perfusion is unequivocal.

Effect of Glomerulopathy Recurrence in the Outcome and Graft Survival of Kidney Transplanted Patients

BACKGROUND

Recurrent glomerulopathy (GP) after kidney transplantation is a complication of kidney transplantation that could negatively affect kidney function and graft survival. This study aimed to evaluate the outcome, graft survival, and GP recurrence and its predictive factors in kidney-transplanted patients.

METHODS

Patients were divided into 2 groups: G1 (with GP; n = 95) and G2 (with other causes of end-stage renal disease; n = 373). Graft survival analyses were performed using the Kaplan-Meier for living donor (LD) and deceased donor (DD). Cox proportional hazards regression were used to investigate the predictors for graft loss and for GP recurrence.

RESULTS

Disease recurrence was observed in 9 patients who received a kidney from an LD, of which 4 lost their grafts. In patients who received a kidney from a DD, recurrence was also observed in 9 patients, of which 3 lost their grafts. No statistically significant differences in graft survival between G1 and G2 in relation to LD and DD were noted (P = .299 and .434, respectively). However, differences in graft survival were found when GP subtypes and GP recurrence were analyzed. The predictors of graft loss were delayed graft function (hazard ratio [HR] = 2.226, P = .002), rejection episodes (HR = 1.904, P = .017), and recurrence or transplant GP (HR = 3.243, P = .006). The predictors of disease recurrence or transplant GP were age (HR = 0.945, P = .028) and cold ischemia time (HR = 1.117, P = .003).

CONCLUSION

Kidney transplantation could be a reasonable treatment for GP with end-stage renal disease. Despite the disease recurrence, which is a significant cause of graft loss in transplant recipients, graft survival remains satisfactory.

Effects of immunotherapy induction on outcome and graft survival of kidney-transplanted patients with different immunological risk of rejection

Background

In kidney transplantation, immunotherapy with thymoglobulin (rATG) has been used to down-regulate the patient immune system. rATG is a powerful immunobiologic drug used to deplete lymphocytes to prevent early acute rejection. The aim of this research was to evaluate the effects of immunotherapy by rATG on graft suvival during a 9-year period in kidney-transplanted patients with different immunological profiles.

Methods

A sample of 469 patients were allocated into four groups (G) based on immunological risk of rejection: G1, low risk, not sensitized recipients, solid-phase immunoassay with single antigen beads (SPI-SAB) < 10%; G2, medium risk I, sensitized recipients, SPI-SAB ≥ 10 < 50%; G3, medium risk II sensitized (SPI-SAB ≥50%); and G4, high risk, sensitized recipients, SPI-SAB- donor-specific antibody positive (DSA+). Only patients from G3 and G4 received immunotherapy.

Results

Of 255 patients who received a kidney from a living donor (LD), 42 (16.47%) from all groups (G) had T-cell–mediated rejection (TCMR) and four (G1) lost their grafts, 8 (3.14%) had antibody-mediated rejection (AMR), and two lost their graft in G1 and G4. Of 214 patients who received a kidney from deceased donors (DD), 37 (17.29%) had TCMR with one lost graft in G1. AMR was shown in 13 (6.07%) patients, with three losses observed in G2. Statistical differences between the groups in the 9-year graft survival rate were found only in the comparison of G1 versus G2 (P = 0.005) and G2 versus G4 (P = 0.047) for DD. For LD, no statistical differences were found.

Conclusion

This clinical retrospective study shows that immunotherapy induction was associated with improvement of outcomes, graft function, and survival in patients treated with immunotherapy in comparison with patients who did not received induction therapy. These findings strongly suggest that immunotherapy should be used for all patients transplanted with kidneys from deceased donors.

Critical Role of Macrophage FcγR Signaling and Reactive Oxygen Species in Alloantibody-Mediated Hepatocyte Rejection

Humoral alloimmunity negatively impacts both short- and long-term cell and solid organ transplant survival. We previously reported that alloantibody-mediated rejection of transplanted hepatocytes is critically dependent on host macrophages. However, the effector mechanism(s) of macrophage-mediated injury to allogeneic liver parenchymal cells is not known. We hypothesized that macrophage-mediated destruction of allogeneic hepatocytes occurs by cell-cell interactions requiring FcγRs. To examine this, alloantibody-dependent hepatocyte rejection in CD8-depleted wild-type (WT) and Fcγ-chain knockout (KO; lacking all functional FcγR) transplant recipients was evaluated. Alloantibody-mediated hepatocellular allograft rejection was abrogated in recipients lacking FcγR compared with WT recipients. We also investigated anti-FcγRI mAb, anti-FcγRIII mAb, and inhibitors of intracellular signaling (to block phagocytosis, cytokines, and reactive oxygen species [ROS]) in an in vitro alloantibody-dependent, macrophage-mediated hepatocytoxicity assay. Results showed that in vitro alloantibody-dependent, macrophage-mediated hepatocytotoxicity was critically dependent on FcγRs and ROS. The adoptive transfer of WT macrophages into CD8-depleted FcγR-deficient recipients was sufficient to induce alloantibody-mediated rejection, whereas adoptive transfer of macrophages from Fcγ-chain KO mice or ROS-deficient (p47 KO) macrophages was not. These results provide the first evidence, to our knowledge, that alloantibody-dependent hepatocellular allograft rejection is mediated by host macrophages through FcγR signaling and ROS cytotoxic effector mechanisms. These results support the investigation of novel immunotherapeutic strategies targeting macrophages, FcγRs, and/or downstream molecules, including ROS, to inhibit humoral immune damage of transplanted hepatocytes and perhaps other cell and solid organ transplants.