Long-term Death-censored Graft Survival Research Articles

#4443 INNATE IMMUNE MEMORY DETERMINES LONG-TERM KIDNEY ALLOGRAFT SURVIVAL

Abstract Background and Aims Historically, transplant medicine has focused primarily on the adaptive immune system, while the role of innate immune cells in the complex graft-reactive immune response has been understudied. The recently emerging concept of “trained immunity” is of particular interest in this regard. Trained immunity is a phenomenon in which innate immune cells develop a long-lasting memory in response to an initial stimulus, thereby reprogramming cells for a stronger inflammatory response to future stimuli. We hypothesized that damage-associated molecular patterns (DAMPs), released during ischemia-reperfusion injury, and immunosuppressive medication can affect trained immunity, and investigated in a cohort of kidney transplant patients if trained immunity is associated with long-term allograft survival. Method An established in vitro trained immunity assay was used in which human peripheral blood mononuclear cells (PBMCs) were stimulated. After five days of rest, cells were restimulated with lipopolysaccharide (LPS), and IL-6 and TNF were measured in the supernatant as a readout of the trained immunity response (Fig. 1A). We tested a library of DAMPs, and immunosuppressive drugs commonly used in kidney transplantation, to determine their effect on trained immunity. Of 96 kidney transplant recipients, with a follow-up for graft survival >8 years, serum was obtained before- and one week after transplantation. Patient sera were used to stimulate healthy PBMCs in the trained immunity assay. The relationship between serum induced trained immunity and long-term allograft survival was analyzed by Kaplan-Meier and Cox regression analysis. Results We found that DAMPs can affect trained immunity, causing either an enhanced (HMGB1, histones, IL-1β) or suppressed (vimentin, ATP, and C1q) cytokine response after LPS restimulation (Fig. 1B). Prednisone and tacrolimus potently suppressed trained immunity (Fig. 1C). In the kidney transplant patient cohort, cells stimulated with patients’ serum showed considerable heterogeneity in the IL-6 and TNF production after LPS restimulation. The IL-6 and TNF response of cells stimulated with serum obtained one week post-transplantation was lower compared to cells stimulated with serum obtained before transplantation (Difference of 463 ± 428 pg/mL, p<0.001 for IL-6; 1215 ± 1078 pg/mL, p<0.001 for TNF). The trained immunity response to post-transplant obtained serum was strongly associated with long-term death-censored graft survival (p = 0.005 for IL-6 tertials, and p = 0.037 for TNF tertials in a Kaplan-Meier analysis), and remained significant after adjusting for potential confounders. Conclusion Trained immunity can be affected by stimulation with DAMPs, which are released during ischemia-reperfusion injury during transplantation, and by immunosuppressive drugs used in kidney transplantation. The net effect of patients' serum taken one week after transplantation, containing a mixture of DAMPs and immunosuppressive drugs, has a suppressive effect on trained immunity compared with patients' pre-transplant serum. Interestingly, the trained immunity response to post-transplant serum is strongly associated with long-term allograft survival. Thereby we have identified trained immunity as a novel and relevant immunological mechanism in organ transplantation.

Deletion of the Natural Killer Cell Receptor NKG2C Encoding KLR2C Gene and Kidney Transplant Outcome.

Natural killer (NK) cells may contribute to antibody-mediated rejection (ABMR) of renal allografts. The role of distinct NK cell subsets in this specific context, such as NK cells expressing the activating receptor NKG2C, is unknown. Our aim was to investigate whether KLRC2 gene deletion variants which determine NKG2C expression affect the pathogenicity of donor-specific antibodies (DSA) and, if so, influence long-term graft survival. We genotyped the KLRC2 wt/del variants for two distinct kidney transplant cohorts, (i) a cross-sectional cohort of 86 recipients who, on the basis of a positive post-transplant DSA result, all underwent allograft biopsies, and (ii) 1,860 recipients of a deceased donor renal allograft randomly selected from the Collaborative Transplant Study (CTS) database. In the DSA+ patient cohort, KLRC2 wt/wt (80%) was associated with antibody-mediated rejection (ABMR; 65% versus 29% among KLRC2 wt/del subjects; P=0.012), microvascular inflammation [MVI; median g+ptc score: 2 (interquartile range: 0-4) versus 0 (0-1), P=0.002], a molecular classifier of ABMR [0.41 (0.14-0.72) versus 0.10 (0.07-0.27), P=0.001], and elevated NK cell-related transcripts (P=0.017). In combined analyses of KLRC2 variants and a functional polymorphism in the Fc gamma receptor IIIA gene (FCGR3A-V/F158), ABMR rates and activity gradually increased with the number of risk genotypes. In DSA+ and CTS cohorts, however, the KLRC2 wt/wt variant did not impact long-term death-censored graft survival, also when combined with the FCGR3A-V158 risk variant. KLRC2 wt/wt may be associated with DSA-triggered MVI and ABMR-associated gene expression patterns, but the findings observed in a highly selected cohort of DSA+ patients did not translate into meaningful graft survival differences in a large multicenter kidney transplant cohort not selected for HLA sensitization.

De novo donor-specific HLA antibodies reduce graft survival rates and increase the risk of kidney transplant rejection: A single-center retrospective study

BackgroundWe investigated the impact of de novo donor-specific anti-human leukocyte antigen antibodies (dnDSAs) on long-term death-censored graft survival and renal allograft rejection in kidney transplant recipients. MethodsThe sample for this retrospective cohort study comprised 121 recipients of kidney transplants with negative complement-dependent cytotoxicity crossmatches to their deceased donors. Recipients were divided into two groups: dnDSAs+ (n = 31) and dnDSAs- (n = 90). We evaluated rejection and long-term graft survival rates in the recipients along with pathologic changes in the transplanted kidneys. ResultsDnDSAs were identified in 31/121 patients (25.6%). The graft survival rate in the dnDSAs+ group was 87.1% (27/31) and that of the dnDSAs- group was 97.8% (88/90). The dnDSAs+ group had lower graft survival rates than patients without dnDSAs (p = 0.007). There was no difference in the graft survival rates between patients with high DSA mean fluorescence intensity (≥4000) and those with low intensity (<4000) (p = 0.669). There was also no difference in the graft survival rates of patients with HLA class I, II, and I + II dnDSAs (p = 0.571). The presence of dnDSA in serum was associated with a higher incidence of antibody- and T-cell–mediated rejection (p < 0.0001). Banff scores for arterial fibrointimal and arteriolar hyalin, thickening as well as C4d deposition differed for the dnDSAs+ and dnDSAs- groups (p < 0.05). ConclusionDnDSAs were found to be associated with decreased long-term graft survival rates and increased rejection rates, often accompanied by C4d deposition.

Safety and effectiveness of kidney transplantation using a donation after\xa0brain death donor with acute kidney injury: a retrospective cohort study

The use of kidneys from donation after brain death (DBD) donors with acute kidney injury (AKI) is a strategy to expand the donor pool. The aim of this study was to evaluate how kidney transplantation (KT) from a donor with AKI affects long-term graft survival in various situations. All patients who underwent KT from DBD donors between June 2003 and April 2016 were retrospectively reviewed. The KDIGO (Kidney Disease: Improving Global Outcomes) criteria were used to classify donor AKI. The cohort included 376 donors (no AKI group, n = 117 [31.1%]; AKI group n = 259 [68.9%]). Death-censored graft survival was similar according to the presence of AKI, AKI severity, and the AKI trend (p = 0.929, p = 0.077, and p = 0.658, respectively). Patients whose donors had AKI who received using low dose (1.5 mg/kg for three days) rabbit anti-thymocyte globulin (r-ATG) as the induction agent had significantly superior death-censored graft survival compared with patients in that group who received basiliximab (p = 0.039). AKI in DBD donors did not affect long-term death-censored graft survival. Low-dose r-ATG may be considered as an induction immunosuppression in recipients receiving kidneys with AKI because it showed better graft survival than basiliximab.

Impact of persistent preformed and de novo donor-specific antibodies detected at 1 year after kidney transplantation on long-term graft survival in Japan: a retrospective study

We evaluated the impact of persistent preformed donor-specific antibody (DSA) and de novo DSA (dnDSA) detected at 1year posttransplantation on long-term death-censored graft survival. One hundred and sixty adult patients who received living kidney allograft with pretransplant-negative T-cell complement-dependent cytotoxicity crossmatch (CDCXM), and without periodic screening for DSA, were eligible for this study. All enrolled patients were retrospectively tested for DSA using the Luminex assay. The presence of DSA was analyzed in stored serum samples collected at 1year posttransplantation. If the recipients had DSA, it was analyzed in the pretransplant serum sample. The detection of DSA solely in the 1year posttransplant sample was defined as dnDSA, and DSA detection in both pretransplant and 1year posttransplant samples was defined as persistent preformed DSA. DSAs were identified in 14 (8.8%) of the 160 patients. Seven patients had persistent preformed DSA, 6 had dnDSA, and 1 had both persistent preformed and dnDSA at 1year posttransplantation. Death-censored allograft survival rates of patients with DSA versus those without DSA at 7 and 11years were 77.9 vs. 97.8% and 60.6 vs. 89.2%, respectively. The graft survival rate was lower in patients with persistent preformed DSA and/or dnDSA. Each case of preformed DSA and dnDSA was associated with long-term graft survival. The presence of persistent preformed DSA or dnDSA at 1year posttransplantation may be a predictor of long-term graft survival. Further study is needed to evaluate whether periodic screening for DSA improves long-term graft survival.

Long-term follow-up of the DeKAF cross-sectional cohort study.

The DeKAF study was developed to better understand the causes of late allograft loss. Preliminary findings from the DeKAF cross-sectional cohort (with follow-up < 20months) have been published. Herein, we present long-term outcomes in those recipients (mean follow-up ± SD, 6.6± 0.7years). Eligibility included being transplanted prior to October 1, 2005; serum creatinine ≤ 2.0mg/dL on January 1, 2006; and subsequently developing new-onset graft dysfunction leading to a biopsy. Mean time from transplant to biopsy was 7.5±6.1years. Histologic findings and DSA were studied in relation to postbiopsy outcomes. Long-term follow-up confirms and expands the preliminary results of each of 3 studies: (1) increasing inflammation in area of atrophy (irrespective of inflammation in nonscarred areas [Banff i]) was associated with increasingly worse postbiopsy death-censored graft survival; (2) hierarchical analysis based on Banff scores defined clusters (entities) that differed in long-term death-censored graft survival; and (3) C4d-/DSA- recipients had significantly better (and C4d+/DSA+ worse) death-censored graft survival than other groups. C4d+/DSA- and C4d-/DSA+ had similar intermediate death-censored graft survival. Clinical and histologic findings at the time of new-onset graft dysfunction define high- vs low-risk groups for long-term death-censored graft survival, even years posttransplant. These findings can help differentiate groups for potential intervention studies.

Can Regulatory T Cells Help Us as a Biomarker of Long-Term Kidney Graft Survival?

IDIVAL. Background Immunosuppression regimens effectively control acute rejection and decrease graft loss in the first year after transplantation; but long-term graft attrition rates remain stable beyond this point, due to a combination of drug toxicities and the emergence of chronic alloimmune responses. It is known that regulatory T cells (Tregs) play a role in limiting kidney transplant rejection and can potentially promote transplant tolerance. Despite this, there are a few prospective studies that prove the role of peripheral Tregs on long-term graft outcome.The aim of our study was to analyze the influence of 1-year peripheral blood Tregs on long-term death censored graft survival. Methods and Materials Prospectively monitored peripheral blood Tregs by flow cytometry in Kidney Transplant Recipient (KTR) between 2005 and 2011. A total of 133 KTR were included in the study and followed up to 4 years after transplantation. Death censored graft survival was determined retrospectively in January-2017. Results Follow-up was 7.4 ± 2.9 years and 24.1% patients suffered death censored graft loss (DCGL). One-year peripheral Tregs were 17.4 ± 16.9 cells/mm3. Patients with high Tregs above the median value (14.57 cells/mm3) showed better death-censored graft survival (5-year 92.5% vs. 81.4%, Log-rank p = 0.030). One-year Tregs showed AUC-ROC of 63.1% (95%CI 52.9-73.2%, p = 0.026) for predicting DCGL. After multivariate Cox’s regression analysis, a high number of peripheral blood Tregs was a protective factor for DCGL (HR 0.961, 95%CI 0.924-0.998, p = 0.041) irrespectively of 1-year proteinuria and renal function. Conclusion A high number of peripheral blood Tregs at 1-year after kidney transplantation relates to a better long-term graft outcome. This relationship was independent of other significant 1-year variables. In this sense, peripheral blood Tregs can be useful as a biomarker to predict graft outcomes and to tailor immunosuppression.

The DESCARTES-Nantes survey of kidney transplant recipients displaying clinical operational tolerance identifies 35 new tolerant patients and 34 almost tolerant patients.

Kidney recipients maintaining a prolonged allograft survival in the absence of immunosuppressive drugs and without evidence of rejection are supposed to be exceptional. The ERA-EDTA-DESCARTES working group together with Nantes University launched a European-wide survey to identify new patients, describe them and estimate their frequency for the first time. Seventeen coordinators distributed a questionnaire in 256 transplant centres and 28 countries in order to report as many 'operationally tolerant' patients (TOL; defined as having a serum creatinine <1.7 mg/dL and proteinuria <1 g/day or g/g creatinine despite at least 1 year without any immunosuppressive drug) and 'almost tolerant' patients (minimally immunosuppressed patients (MIS) receiving low-dose steroids) as possible. We reported their number and the total number of kidney transplants performed at each centre to calculate their frequency. One hundred and forty-seven questionnaires were returned and we identified 66 TOL (61 with complete data) and 34 MIS patients. Of the 61 TOL patients, 26 were previously described by the Nantes group and 35 new patients are presented here. Most of them were noncompliant patients. At data collection, 31/35 patients were alive and 22/31 still operationally tolerant. For the remaining 9/31, 2 were restarted on immunosuppressive drugs and 7 had rising creatinine of whom 3 resumed dialysis. Considering all patients, 10-year death-censored graft survival post-immunosuppression weaning reached 85% in TOL patients and 100% in MIS patients. With 218 913 kidney recipients surveyed, cumulative incidences of operational tolerance and almost tolerance were estimated at 3 and 1.5 per 10 000 kidney recipients, respectively. In kidney transplantation, operational tolerance and almost tolerance are infrequent findings associated with excellent long-term death-censored graft survival.

Changing Kidney Allograft Histology Early Posttransplant: Prognostic Implications of 1-Year Protocol Biopsies

Allograft histology 1 year posttransplant is an independent correlate to long-term death-censored graft survival. We assessed prognostic implications of changes in histology first 2 years posttransplant in 938 first kidney recipients, transplanted 1999-2010, followed for 93.4 ± 37.7 months. Compared to implantation biopsies, histology changed posttransplant showing at 1 year that 72.6% of grafts had minor abnormalities (favorable histology), 20.2% unfavorable histology, and 7.2% glomerulonephritis. Compared to favorable, graft survival was reduced in recipients with unfavorable histology (hazards ratio [HR] = 4.79 [3.27-7.00], p < 0.0001) or glomerulonephritis (HR = 5.91 [3.17-11.0], p < 0.0001). Compared to unfavorable, in grafts with favorable histology, failure was most commonly due to death (42% vs. 70%, p < 0.0001) and less commonly due to alloimmune causes (27% vs. 10%, p < 0.0001). In 80% of cases, favorable histology persisted at 2 years. However, de novo 2-year unfavorable histology (15.3%) or glomerulonephritis (4.7%) related to reduced survival. The proportion of favorable grafts increased during this period (odds ratio = 0.920 [0.871-0.972], p = 0.003, per year) related to fewer DGF, rejections, polyoma-associated nephropathy (PVAN), and better function. Graft survival also improved (HR = 0.718 [0.550-0.937], p = 0.015) related to better histology and function. Evolution of graft histologic early posttransplant relate to long-term survival. Avoiding risk factors associated with unfavorable histology relates to improved histology and graft survival.

Solid phase detection of C4d-fixing HLA antibodies to predict rejection in high immunological risk kidney transplant recipients

Protocols for recipient desensitization may allow for successful kidney transplantation across major immunological barriers. Desensitized recipients, however, still face a considerable risk of antibody-mediated rejection (AMR), which underscores the need for risk stratification tools to individually tailor treatment. Here, we investigated whether solid phase detection of complement-fixing donor-specific antibodies (DSA) has the potential to improve AMR prediction in high-risk transplants. The study included 68 sensitized recipients of deceased donor kidney allografts who underwent peritransplant immunoadsorption for alloantibody depletion (median cytotoxic panel reactivity: 73%; crossmatch conversion: n=21). Pre and post-transplant sera were subjected to detection of DSA-triggered C4d deposition ([C4d]DSA) applying single-antigen bead (SAB) technology. While standard crossmatch and [IgG]SAB testing failed to predict outcomes in our desensitized patients, detection of preformed [C4d]DSA (n=44) was tightly associated with C4d-positive AMR [36% vs. 8%, P=0.01; binary logistic regression: odds ratio: 10.1 (95% confidence interval: 1.6-64.2), P=0.01]. Moreover, long-term death-censored graft survival tended to be worse among [C4d]DSA-positive recipients (P=0.07). There were no associations with C4d-negative AMR or cellular rejection. [C4d]DSA detected 6months post-transplantation were not related to clinical outcomes. Our data suggest that pretransplant SAB-based detection of complement-fixing DSA may be a valuable tool for risk stratification.

Recipients of Kidneys from Expanded Criteria Donors Whose eGFR Does not Drop &gt;30% Between 1-12 Months after Transplantation Have Excellent Long-Term Graft Survival

Purpose: To determine the impact of eGFR drop lower or greater than 30% during the first yr post-kidney transplantation (KTx) on long-term death censored graft survival (DCGS). Methods: We studied 471 KTx recipients of deceased donor kidneys between 1/1990 and 12/2006. 253 pts (53.7%, 82 women, 171 men, 49±12 yrs) received standard criteria donor (SCD) kidneys, and 218 pts (46.3%, 73 women, 145 men, 52±13 yrs) received ECD kidneys. Immunosuppression consisted of ATG induction, CNI and an antimetabolite. CIT was 15.4±8.4 hr. We analyzed an eGFR drop lower or greater than 30% between 1-3, 1-12 and 3-12 months in recipients of SCD and ECD kidneys, with immediate (IGF, Scr decreased ≥20% within 24 hrs post-KTx), slow (SGF, Scr decreased < 20% within 24 hrs post-KTx and no need for dialysis) or delayed graft function (DGF, need for dialysis during the first week post-KTx), on long-term DCGS in pts whose graft survived >1 yr post-KTx. 55 recipients of SCD and 34 recipients of ECD were excluded because of graft loss, death or loss to follow-up during the first yr. Results: The impact of eGFR drop on long-term DCGS is depicted in Figures 1 and 2. There was no difference in pts with SGF. eGFR (mL/min/1.73m2) at 1, 5 and 10 yrs was 71±22, 66±22 and 57±22 respectively, in recipients of SCD and 56±18, 49±23 and 41±20 respectively, in recipients of ECD (P=0.001). An eGFR drop between 1-12 months was associated with lower DCGS (HR 2.16, P=0.02).Figure: [*P=0.002 and **P=0.01 vs. ECD Drop >30%]Figure: [P<0.0001 and **P=0.0003 vs. ECD Drop >30%]Conclusion: Recipients of ECD kidneys without an eGFR drop >30% between 1-12 months post-KTx have excellent long-term DCGS, equivalent to recipients of SCD kidneys.

Recipients of Kidneys from Expanded Criteria Donors Whose eGFR Does not Drop >30% Between 1-12 Months after Transplantation Have Excellent Long-Term Graft Survival

Purpose: To determine the impact of eGFR drop lower or greater than 30% during the first yr post-kidney transplantation (KTx) on long-term death censored graft survival (DCGS). Methods: We studied 471 KTx recipients of deceased donor kidneys between 1/1990 and 12/2006. 253 pts (53.7%, 82 women, 171 men, 49±12 yrs) received standard criteria donor (SCD) kidneys, and 218 pts (46.3%, 73 women, 145 men, 52±13 yrs) received ECD kidneys. Immunosuppression consisted of ATG induction, CNI and an antimetabolite. CIT was 15.4±8.4 hr. We analyzed an eGFR drop lower or greater than 30% between 1-3, 1-12 and 3-12 months in recipients of SCD and ECD kidneys, with immediate (IGF, Scr decreased ≥20% within 24 hrs post-KTx), slow (SGF, Scr decreased < 20% within 24 hrs post-KTx and no need for dialysis) or delayed graft function (DGF, need for dialysis during the first week post-KTx), on long-term DCGS in pts whose graft survived >1 yr post-KTx. 55 recipients of SCD and 34 recipients of ECD were excluded because of graft loss, death or loss to follow-up during the first yr. Results: The impact of eGFR drop on long-term DCGS is depicted in Figures 1 and 2. There was no difference in pts with SGF. eGFR (mL/min/1.73m2) at 1, 5 and 10 yrs was 71±22, 66±22 and 57±22 respectively, in recipients of SCD and 56±18, 49±23 and 41±20 respectively, in recipients of ECD (P=0.001). An eGFR drop between 1-12 months was associated with lower DCGS (HR 2.16, P=0.02).Figure: [*P=0.002 and **P=0.01 vs. ECD Drop >30%]Figure: [*P<0.0001 and **P=0.0003 vs. ECD Drop >30%]Conclusion: Recipients of ECD kidneys without an eGFR drop >30% between 1-12 months post-KTx have excellent long-term DCGS, equivalent to recipients of SCD kidneys.

Factors affecting kidney‐transplant outcome in recipients with lupus nephritis

Factors associated with outcome in renal transplant recipients with lupus nephritis have not been studied. Using the data from the United States Renal Data System of patients transplanted between January 1, 1995 through December 31, 2002 (and followed through December 31, 2003) (n = 2882), we performed a retrospective analysis of factors associated with long-term death-censored graft survival and recipient survival. The number of pretransplant pregnancies incrementally increased the risk of graft failure [hazard ratio (HR) 1.54, p < 0.05] in the entire subgroup of females and in the subgroup of recipients aged 25-35 yr. Recipient and donor age had an association with both the risk of graft failure (HR 0.96, p < 0.001; HR 1.01, p < 0.005) and recipient death (HR 1.04, p < 0.001; HR 1.01, p < 0.05). Greater graft-failure risk accompanied increased recipient weight (HR 1.01, p < 0.001); African Americans compared with whites (HR 1.55, p < 0.001); greater Charlson comorbidity index (HR 1.17, p < 0.05); and greater panel reactive antibody (PRA) levels (HR 1.06, p < 0.001). Pretransplant peritoneal dialysis as the predominant modality had an association with decreased risk of graft failure (HR 0.49, p < 0.001), while prior transplantation was associated with greater risk of graft failure and recipient death (HR 2.29, p < 0.001; HR 3.59, p < 0.001, respectively) compared with hemodialysis (HD). The number of matched human leukocyte antigens (HLA) antigens and living donors (HR 0.92, p < 0.05; HR 0.64, p < 0.001, respectively) was associated with decreased risk of graft failure. Increased risk of graft failure and recipient death was associated with nonuse of calcineurin inhibitors (HR 1.89, p < 0.005; HR 1.80, p < 0.005) and mycophenolic acid (MPA) (including mycophenolate mofetil and MPA) or azathioprine (HR 1.41, p < 0.05; HR 1.66, p < 0.01). Using both cyclosporine and tacrolimus was associated with increased risk of graft failure (HR 2.09, p < 0.05). Using MPA is associated with greater risk of recipient death compared with azathioprine (HR 1.47, p < 0.05). In renal transplant recipients with lupus nephritis, multiple pregnancies, multiple blood transfusions, greater comorbidity index, higher body weight, age and African American race of the donor or recipient, prior history of transplantation, greater PRA levels, lower level of HLA matching, deceased donors, and HD in pretransplant period have an association with increased risk of graft failure. Similarly, higher recipient and donor age, prior transplantations, and higher rate of pretransplant transfusions are associated with greater risk of recipient mortality. Using neither cyclosporine nor tacrolimus or using both (compared with tacrolimus) and neither MPA nor azathioprine (compared with azathioprine) was associated with increased risk of graft failure and recipient death. Using MPA is associated with greater risk of recipient death compared with azathioprine. Testing these results in a prospective study might provide important information for clinical practice.