Banff 2013 meeting report: inclusion of c4d-negative antibody-mediated rejection and antibody-associated arterial lesions

Evaluation of Cumulative Effect of Standard Triple Immunosuppression on Prevention of De Novo Donor Specific Antibodies (dnDSA) Production in Children after Kidney Transplantation—A Retrospective and Prospective Study

De novo Donor Specific Antibodies (dnDSA) are associated with inferior graft outcomes. Standard immunosuppression is expected to prevent dnDSA production in low-risk patients. We have evaluated a cumulative effect of a triple immunosuppression (CNI/MMF/Pred), as well as TAC concentration and coefficient of variation on the incidence of dnDSA production. Overall, 67 transplanted patients were evaluated in retrospective (dnDSA for-cause; n = 29) and prospective (dnDSA by protocol; n = 38) groups. In the retrospective group, the eGFR value at first dnDSA detection (median interval—4.0 years post-transplant) was 41 mL/min/1.73 m²; 55% of patients presented biopsy-proven cAMR, and 41% lost the graft within next 2.4 years. Patients from the prospective group presented 97% graft survival and eGFR of 76 mL/min/1.73 m² at 2 years follow-up, an overall incidence of 21% of dnDSA and 18% of acute (T cell) rejection. None of the patients from the prospective group developed cAMR. Median value of Vasudev score within 2 years of follow-up was not significantly higher in dsDSA negative patients, while median value of TAC C₀ > 1–24 months post-transplant was 7.9 in dnDSA negative vs. 7.1 ng/mL in dnDSA positive patients (p = 0.008). Conclusion: dnDSA-negative patients presented a higher exposure to tacrolimus, while not to the combined immunosuppression.

Intimal Arteritis and Microvascular Inflammation Are Associated With Inferior Kidney Graft Outcome, Regardless of Donor-Specific Antibodies

Background: The prognostic role of intimal arteritis of kidney allografts in donor-specific antibody negative (DSA–) antibody-mediated rejection (ABMR) remains unclear.

Methods: Seventy-two out of 881 patients who had undergone kidney transplantation from 2014 to 2017 exhibited intimal arteritis in biopsies performed during the first 12 months. In 26 DSA negative cases, the intimal arteritis was accompanied by tubulointerstitial inflammation as part of T cell-mediated vascular rejection (TCMRV, N = 26); intimal arteritis along with microvascular inflammation occurred in 29 DSA negative (ABMRV/DSA–) and 19 DSA positive cases (ABMRV, DSA+, N = 17). In 60 (83%) patients with intimal arteritis, the surveillance biopsies after antirejection therapy were performed. Hundred and two patients with non-vascular ABMR with DSA (ABMR/DSA+, N = 55) and without DSA (ABMR/DSA–, N = 47) served as controls. Time to transplant glomerulopathy (TG) and graft failure were the study endpoints.

Results: Transplant glomerulopathy -free survival at 36 months was 100% in TCMRV, 85% in ABMR/DSA–, 65% in ABMRV/DSA-, 54% in ABMR/DSA+ and 31% in ABMRV/DSA+ (log rank p < 0.001). Death-censored graft survival at 36 months was 98% in ABMR/DSA-, 96% in TCMRV, 86% in ABMRV/DSA–, 79% in ABMR/DSA+, and 64% in ABMRV/DSA+ group (log rank p = 0.001). In surveillance biopsies, the resolution of rejection was found in 19 (90%) TCMRV, 14 (58%) ABMRV/DSA–, and only 4 (27%) ABMRV/DSA+ patients (p = 0.006). In the multivariable model, intimal arteritis as part of ABMR represented a significant risk for TG development (HR 2.1, 95% CI 1.2–3.8; p = 0.012) regardless of DSA status but not for graft failure at 36 months.

Conclusions: Intimal arteritis as part of ABMR represented a risk for early development of TG regardless of the presence or absence of DSA. Intimal arteritis in DSA positive ABMR represented the high-risk phenotype.

Spot Urine Protein Excretion in the First Year Following Kidney Transplantation Associates With Allograft Rejection Phenotype at 1-Year Surveillance Biopsies: An Observational National-Cohort Study

Introduction: Urine protein excretion is routinely measured to assess kidney allograft injury, but the diagnostic value of this measurement for kidney transplant pathology remains unclear. Here we investigated whether spot urine protein excretion in the first year following transplantation associates with allograft rejection phenotype at 1-year surveillance biopsies and de-novo occurrence of donor-specific antibodies (DSA). Patients and Methods: This prospective, observational national-cohort study included 139 non-sensitized patients who received a deceased donor kidney transplant between December 2014 and 2018. All patients received basiliximab induction and tacrolimus-based immunosuppression. Estimated protein excretion rate (ePER) was calculated monthly from spot urine protein-to-creatinine ratios. At 1-year, all recipients underwent surveillance graft biopsy and were screened for de-novo DSA. Screening-positive sera were subjected to single antigen bead (SAB) testing. The occurrence of de-novo DSA was determined based on SAB reactivity patterns using a mean fluorescence intensity threshold >1,000. Results: Among the 139 study patients, 27 patients (19%) had histologic evidence of T cell-mediated rejection (TCMR), and 9 patients (7%) had histologic evidence of antibody-mediated rejection (AMR) at 1-year surveillance biopsy. One year after transplant, 19 patients (14%) developed de-novo DSA. Compared with patients without rejection and no de-novo DSA, mixed-effects linear regression analysis showed a significant difference in slope of ePER during the first year in patients with AMR and de-novo DSA at 1-year (46, 95% CI 25-68 mg/day/1.73 m² per month and 34, 95% CI 20-49 mg/day/1.73 m² per month, respectively). Patients with vascular TCMR also showed a significant difference in ePER slope over time compared with patients with non-rejection findings (31, 95% CI 9-52 mg/day/1.73 m² per month). The discriminatory power of ePER for intragraft rejection processes was better in patients with AMR (AUC 0.95, 95% CI 0.90-0.99; P < 0.001) than in those with TCMR (AUC 0.68, 95% CI 0.59-0.79; P = 0.002), with 89% sensitivity and 93% specificity for proteinuria >550 mg/day/1.73m². Conclusions: An increase in ePER in the first year following kidney transplantation associates with AMR, vascular TCMR and de-novo DSA at 1-year and may be used as a non-invasive clinical marker of intragraft endothelial cell injury.

CRISPR/Cas9-Engineered HLA-Deleted Glomerular Endothelial Cells as a Tool to Predict Pathogenic Non-HLA Antibodies in Kidney Transplant Recipients

BACKGROUND

After kidney transplantation, donor-specific antibodies against human leukocyte antigen donor-specific antibodies (HLA-DSAs) drive antibody-mediated rejection (ABMR) and are associated with poor transplant outcomes. However, ABMR histology (ABMRh) is increasingly reported in kidney transplant recipients (KTRs) without HLA-DSAs, highlighting the emerging role of non-HLA antibodies (Abs).

METHODS

W e designed a non-HLA Ab detection immunoassay (NHADIA) using HLA class I and II-deficient glomerular endothelial cells (CiGEnCΔHLA) that had been previously generated through CRISPR/Cas9-induced B2M and CIITA gene disruption. Flow cytometry assessed the reactivity to non-HLA antigens of pretransplantation serum samples from 389 consecutive KTRs. The intensity of the signal observed with the NHADIA was associated with post-transplant graft histology assessed in 951 adequate biopsy specimens.

RESULTS

W e sequentially applied CRISPR/Cas9 to delete the B2M and CIITA genes to obtain a CiGEnCΔHLA clone. CiGEnCΔHLA cells remained indistinguishable from the parental cell line, CiGEnC, in terms of morphology and phenotype. Previous transplantation was the main determinant of the pretransplantation NHADIA result (P<0.001). Stratification of 3-month allograft biopsy specimens (n=298) according to pretransplantation NHADIA tertiles demonstrated that higher levels of non-HLA Abs positively correlated with increased glomerulitis (P=0.002), microvascular inflammation (P=0.003), and ABMRh (P=0.03). A pretransplantation NHADIA threshold of 1.87 strongly discriminated the KTRs with the highest risk of ABMRh (P=0.005, log-rank test). A multivariate Cox model confirmed that NHADIA status and HLA-DSAs were independent, yet synergistic, predictors of ABMRh.

CONCLUSION

The NHADIA identifies non-HLA Abs and strongly predicts graft endothelial injury independent of HLA-DSAs.

Solid-Phase C1q/C3d Fixing Readouts Correlate with High Median Fluorescence Intensity (MFI) De Novo Donor-Specific HLA Antibodies and C4d⁺ Antibody-Mediated Rejection in Kidney Transplant Recipients

BACKGROUND Solid-phase assays to investigate the complement-activating capacity of HLA antibodies have been utilized to optimize organ allocation and improve transplant outcomes. The clinical utility of C1q/C3d-binding characteristics of de novo donor-specific anti-HLA antibodies (dnDSA) associated with C4d-positive antibody-mediated rejection (C4d⁺ AMR) in kidney transplants (KTx) has not been defined. MATERIAL AND METHODS Sera from 120 KTx recipients that had dnDSA concurrent with protocol/cause biopsy (median 3.8 years after transplantation) were screened for C1q and C3d-binding dnDSA. The difference in the incidence of C4d⁺ AMR between recipients with and without C1q/C3d-binding dnDSA was assessed. RESULTS Over 86% of dnDSAs were class II antibodies. The immunodominant dnDSAs characterized by the highest median fluorescence intensity (MFI) in most recipients were HLA-DQ antibodies (67%). Most recipients (62%, n=74) had either C1q⁺ (56%), C3d⁺ (48%), or both C1q⁺C3d⁺ (41.2%) dnDSA, while the remaining 38% were negative for both C1q and C3d. Of those with C1q⁺/C3d⁺ dnDSA, 87% had high-MFI IgG (MFI=14144±5363 and 13932±5278, respectively), while 65% of C1q⁻C3d⁻ dnDSA had low-MFI IgG (MFI=5970±3347). The incidence of C4d+ AMR was significantly higher in recipients with C1q⁺ (66%), C3d+ (74%), and C1q⁺C3d⁺ (72%) dnDSA than in those with C1q⁻C3d⁻ dnDSA (30%) recipients. Recipients with C3d⁺/C1q⁺ dnDSA had higher C4d⁺ scores on biopsy. CONCLUSIONS C1q⁺/C3d⁺ dnDSA were associated with C4d⁺ AMR and high-IgG MFI. Our data call into question the predictive utility of C1q/C3d-binding assays in identifying KTx recipients at risk of allograft failure. In conclusion, IgG MFI is sufficient for clinical management, and the C1q/C3d-assays with added cost do not provide any additional information.

Initiation of dialysis for kidney graft failure: A retrospective single-center cohort study

Few studies have focused on the outcome of dialysis for kidney graft failure. We investigated the outcomes of dialysis for graft failure. We retrospectively studied 52 patients undergoing dialysis for graft failure at our facility from January 2004 to December 2018. The mean age at initiation of dialysis was 51.8 ± 13.5 years. The patient survival rates after initiation of dialysis at 1, 3, and 5 years were 96.0%, 93.8%, and 82.4%, respectively. The rate of unplanned initiation was 44.2%. In multivariate logistic analysis, lack of follow-up by nephrologists and pre-emptive kidney transplantation (PEKT) tended to be risk factors for unplanned initiation (P = 0.065 and P = 0.014, respectively). Our study suggests that the prognosis of patients with dialysis for graft failure is acceptable. Dialysis for graft failure, especially in patients with PEKT, tends to be unplanned, and for safe initiation, early involvement of nephrologists may be necessary.

Tacrolimus Intrapatient Variability After Switching From Immediate or Prolonged-Release to Extended-Release Formulation, After an Organ Transplantation

Background and Purpose: Several formulations of tacrolimus are available, but evidence of the benefit of changing to the most recent formulations is lacking. Tacrolimus intra-patient variability (tacrolimus IPV) is an emerging risk factor associated with poor graft outcomes after solid organ transplantations. Here, we examined the modifications of tacrolimus IPV after switching to a different formulation of tacrolimus. Experimental Approach: We identified 353 solid organ transplant recipients that were switched in our center from immediate-release (IR-tacrolimus) or prolonged-release tacrolimus (PR-tacrolimus) to extended-release, LCP-tacrolimus (LCP-tacrolimus). Among them, 54 patients underwent at least 3 available tacrolimus blood concentrations before and after the switch, allowing us to investigate tacrolimus IPV. Key Results: The switch was considered as a safe procedure since only four of the 353 patients presented a graft rejection after the switch, and no patient was hospitalized for tacrolimus overdose. The tacrolimus IPV estimated by the coefficient of variation (CV-IPV) was stable before and after the switch to LCP-tacrolimus (CV-IPV: 29.0% (IQR 25-75 (15.5; 38.5) before and 24.0% (15.8; 36.5) after the switch, p = 0.65). Conclusion and Implications: Switching from IR- or PR-tacrolimus to LCP-tacrolimus is a safe procedure. However, the CV-tacrolimus IPV was not impacted by the change of formulation.

Evaluation of severity of delayed graft function in kidney transplant recipients

BACKGROUND

The most common definition of delayed graft function (DGF) relies on dialysis during the first week post-transplant and does not consider DGF severity. The impact of DGF severity on long-term graft outcome remains controversial.

METHODS

We analyzed 627 deceased-donor kidney transplant recipients (KTR) transplanted 2005-2015 at our center for DGF-severity, associated risk factors and long-term consequences of DGF.

RESULTS

We found 349 (55.7%) KTR with DGF, which were classified into 4 groups according to DGF duration (0-1, 2-7, 8-14, >14 days) and were compared to KTR with no DGF. Increasing duration of DGF was associated with progressive worsening of 10-year death-censored graft survival (no DGF: 88.3% (95%CI: 82.4-94.2), 0-1 day: 81.3% (95%CI: 68.2-94.4), 2-7 days: 61.5% (95%CI: 43.1.1-79.9), 8-14 days: 66.6% (95%CI: 47.4-85.8), >14 days: 51.2% (95%CI: 33-69.4); p < 0.001). In kidneys with a Kidney Donor Profile Index (KDPI) ≥85% all DGF severity groups demonstrated reduced graft survival. However, in < 85%KDPI kidneys, only > 14 days DGF duration showed worse outcomes.

CONCLUSIONS

DGF had a duration-dependent effect on graft survival, which varied depending on KDPI. Of note, 0-1-day DGF showed comparable results to no DGF in the whole cohort.

Histopathologic Features of Antibody Mediated Rejection: The Banff Classification and Beyond

Antibody mediated rejection (ABMR) in the kidney can show a wide range of clinical presentations and histopathologic patterns. The Banff 2019 classification currently recognizes four diagnostic categories: 1. Active ABMR, 2. Chronic active ABMR, 3. Chronic (inactive) ABMR, and 4. C4d staining without evidence of rejection. This categorization is limited in that it does not adequately represent the spectrum of antibody associated injury in allograft, it is based on biopsy findings without incorporating clinical features (e.g., time post-transplant, de novo versus preformed DSA, protocol versus indication biopsy, complement inhibitor drugs), the scoring is not adequately reproducible, and the terminology is confusing. These limitations are particularly relevant in patients undergoing desensitization or positive crossmatch kidney transplantation. In this article, I discuss Banff criteria for these ABMR categories, with a focus on patients with pre-transplant DSA, and offer a framework for considering the continuum of allograft injury associated with donor specific antibody in these patients.

Safety and Efficacy of Sodium-glucose Cotransporter 2 Inhibitors in Kidney Transplant Recipients With Pretransplant Type 2 Diabetes Mellitus: A Retrospective, Single-center, Inverse Probability of Treatment Weighting Analysis of 85 Transplant Patients

Supplemental Digital Content is available in the text.

Whether sodium-glucose cotransporter 2 (SGLT2) inhibitors can be used effectively and safely in kidney transplant (KT) recipients with pretransplant type 2 diabetes as the primary cause of end-stage renal disease (ESRD) remains unclear. In this study, we retrospectively analyzed the efficacy and safety of SGLT2 inhibitors compared with other oral hypoglycemic agents (OHAs) in KT recipients with pretransplant type 2 diabetes as the primary cause of ESRD.

Caveolin-1 in Kidney Chronic Antibody-Mediated Rejection: An Integrated Immunohistochemical and Transcriptomic Analysis Based on the Banff Human Organ Transplant (B-HOT) Gene Panel

Caveolin-1 overexpression has previously been reported as a marker of endothelial injury in kidney chronic antibody-mediated rejection (c-ABMR), but conclusive evidence supporting its use for daily diagnostic practice is missing. This study aims to evaluate if Caveolin-1 can be considered an immunohistochemical surrogate marker of c-ABMR. Caveolin-1 expression was analyzed in a selected series of 22 c-ABMR samples and 11 controls. Caveolin-1 immunohistochemistry proved positive in peritubular and glomerular capillaries of c-ABMR specimens, irrespective of C4d status whereas all controls were negative. Multiplex gene expression profiling in c-ABMR cases confirmed Caveolin-1 overexpression and identified additional genes (n = 220) and pathways, including MHC Class II antigen presentation and Type II interferon signaling. No differences in terms of gene expression (including Caveolin-1 gene) were observed according to C4d status. Conversely, immune cell signatures showed a NK-cell prevalence in C4d-negative samples compared with a B-cell predominance in C4d-positive cases, a finding confirmed by immunohistochemical assessment. Finally, differentially expressed genes were observed between c-ABMR and controls in pathways associated with Caveolin-1 functions (angiogenesis, cell metabolism and cell–ECM interaction). Based on our findings, Caveolin-1 resulted as a key player in c-ABMR, supporting its role as a marker of this condition irrespective of C4d status.

Face transplantation: A longitudinal histological study focusing on chronic active and mucosal rejection in a series with long-term follow-up

The 2007 Banff working classification of skin-containing Tissue Allograft Pathology addressed only acute T cell-mediated rejection in skin. We report the longitudinal long-term histological follow-up of six face transplant recipients, focusing on chronic and mucosal rejection. We identified three patterns suggestive of chronic rejection (lichen planus-like, vitiligo-like and scleroderma-like). Four patients presented lichen planus-like and vitiligo-like chronic rejection at 52 ± 17 months posttransplant with severe concomitant acute T cell-mediated rejection. After lichen planus-like rejection, two patients developed scleroderma-like alterations. Graft vasculopathy with C4d deposits and de novo DSA led to subsequent graft loss in one patient. Chronic active rejection was frequent and similar patterns were noted in mucosae. Concordance between 124 paired skin and mucosal biopsies acute rejection grades was low (κ = 0.2, p = .005) but most grade 0/I mucosal rejections were associated with grade 0/I skin rejections. We defined discordant (grade≥II mucosal rejection and grade 0/I skin rejection) (n = 55 [70%]) and concordant (grade≥II rejection in both biopsies) groups. Mucosal biopsies of the discordant group displayed lower intra-epithelial GranzymeB/FoxP3 ratios suggesting a less aggressive phenotype (p = .08). The grading system for acute rejection in mucosa may require phenotyping. Whether discordant infiltrates reflect a latent allo-immune reaction leading to chronic rejection remains an open question.

Comparative Long-Term Renal Allograft Outcomes of Recurrent Immunoglobulin A with Severe Activity in Kidney Transplant Recipients with and without Rituximab: An Observational Cohort Study

Recurrent IgA nephropathy (IgAN) remains an important cause of allograft loss in renal transplantation. Due to the limited efficacy of corticosteroid in the treatment of recurrent glomerulonephritis, rituximab was used in kidney transplant (KT) recipients with severe recurrent IgAN. A retrospective cohort study was conducted between January 2015 and December 2020. Accordingly, there were 64 KT recipients with biopsy-proven recurrent IgAN with similar baseline characteristics that were treated with the conventional standard therapy alone (controls, n = 43) or together with rituximab (cases, n = 21). All of the recipients had glomerular endocapillary hypercellularity and proteinuria (>1 g/d) with creatinine clearance (CrCl) > 30 mL/min/1.73 m² and well-controlled blood pressure using renin–angiotensin–aldosterone blockers. The treatment outcomes were renal allograft survival rate, proteinuria, and post-treatment allograft pathology. During 3.8 years of follow-up, the rituximab-based regimen rapidly decreased proteinuria within 12 months after rituximab administration and maintained renal allograft function—the primary endpoint—for approximately 3 years. There were eight recipients in the case group (38%), and none in the control group reached a complete remission (proteinuria < 250 mg/d) at 12 months after treatment. Notably, renal allograft histopathology from patients with rituximab-based regimen showed the less severe endocapillary hypercellularity despite the remaining strong IgA deposition. In conclusion, adjunctive treatment with rituximab potentially demonstrated favorable outcomes for treatment of recurrent severe IgAN post-KT as demonstrated by proteinuria reduction and renal allograft function in our cohort. Further in-depth mechanistic studies with the longer follow-up periods are recommended.

Prediction of HLA-DQ in Deceased Donors and its Clinical Significance in Kidney Transplantation

Background

HLA-DQ typing in deceased donors is not mandatory in Korea. Therefore, when patients develop DQ antibodies after kidney transplantation (KT) from deceased donor, it is impossible to determine whether they are donor-specific antibodies (DSA). We developed DQ prediction programs for the HLA gene and evaluated their clinical utility.

Methods

Two HLA-DQ prediction programs were developed: one based on Lewontin's linkage disequilibrium (LD) and haplotype frequency and the other on an artificial neural network (ANN). Low-resolution HLA-A, -B, -DR, and -DQ typing data of 5,603 Korean patients were analyzed in terms of haplotype frequency and used to develop an ANN DQ prediction program. Predicted DQ (pDQ) genotype accuracy was analyzed using the typed DQ data of 403 patients. pDQ DSA agreement, sensitivity, specificity, and false-negative rate was evaluated using 1,970 single-antigen bead assays performed on 885 KT recipients. The clinical significance of DQ and pDQ DSA was evaluated in 411 KT recipients.

Results

pDQ genotype accuracies were 75.4% (LD algorithm) and 75.7% (ANN). When the second most likely pDQ (LD algorithm) was also considered, the genotype accuracy increased to 92.6%. pDQ DSA (LD algorithm) agreement, sensitivity, specificity, and false-negative rate were 97.5%, 97.3%, 98.6%, and 2.4%, respectively. The antibody-mediated rejection treatment frequency was significantly higher in DQ or pDQ DSA-positive patients than in DQ or pDQ DSA-negative patients (P<0.001).

Conclusions

Our DQ prediction programs showed good accuracy and could aid DQ DSA detection in patients who had undergone deceased donor KT without donor HLA-DQ typing.

Clinical Outcome of Kidney Transplant Patients on the Allograft Function, Loss, Effects of HLA-DQB1-DSA+, and Graft Survival

INTRODUCTION

Matching for HLA-DQB1 molecules and anti-DQ donor-specific antibodies (DSAs) has been less studied to allocate transplants from deceased donors in developed countries. The aim of this study was to evaluate the clinical outcome of 519 kidney transplant recipients on the allograft function, loss, and survival and with emphasis on effects of HLA-DQB1-DSA⁺ at minimum of 10 years' follow-up.

METHODS

Five hundred nineteen kidney transplant patients were allocated into 3 groups (G) by immunologic profiles, namely, G1 (SPI-SAB HLA-DQ negative [DQ^-]), G2 (SPI-SAB HLA-DQ positive DSA negative [DQ⁺/DSA^-]), and G3 (SPI-SAB HLA-DQ DSA positive [DQ⁺ DSA⁺]), and the outcomes were reported until 10 years after transplantation.

RESULTS

The proportion of rejection episodes was higher in G3 (25.0% and 26.32%, respectively) than in G1 (8.63% and 6.82%, respectively) and G2 (10.0% and 0%, respectively; P = .047 and P = .014, respectively). In G3, 3 patients lost their grafts by antibody-mediated rejection. Patients who received kidneys from deceased donors (G3) showed worse graft survival rates than those from G1 donors (P = .001). Patients from G3 had a 2.18-fold higher risk of graft loss than patients from G1 (P = .028).

CONCLUSION

Allograft function was worse in G3 than in G2 or G1, and graft losses were more frequent by T-cell-mediated rejection in G1, and graft losses by antibody-mediated rejection were similar in G1 and G3 due to HLA class I (A1, 11 and B 8, 52) and HLA class II by DR7 and DQ 2, 5, 9 DSA, respectively. Allograft survival decreased in patients with HLA-DQB1 DSA. The risk of graft loss was 1.75-fold that in patients who received transplants from living donors.

Impact of low-level pretransplant donor-specific antibodies on outcomes after kidney transplantation

Background

The effect of low‐level pretransplant donor‐specific antibody (DSA) on kidney transplant outcomes is not well described. The goal of this study was to compare outcomes among patients of varying immunologic risk, based on the level of pretransplant DSA.

Methods

We retrospectively reviewed all adult kidney transplant recipients who had undergone a transplant at our center between January 2013 and May 2017. Patients were grouped as negative DSA (mean fluorescence intensity, [MFI_SUM < 100]), low‐level DSA (MFI_SUM 100–1000), and positive DSA (MFI_SUM > 1000). Rejection, infection, graft, and patient survival were outcomes measured.

Results

Of 952 patients, 82.1% had negative DSA, 10.7% had low‐level DSA, and 7.1% had positive DSA. The positive DSA group had the highest rate of antibody‐mediated rejection (10.3%), followed by low‐level DSA (7.8%) and the negative DSA group (4.5%) (p = .034). The rate of BK viremia was highest in the positive DSA group (39.7%), followed by the low‐level group (30.4%) and the negative DSA group (25.6%), (p = .025). None of the other outcomes, including graft or patient survival, were different between the groups.

Conclusion

While low‐level DSA should not prevent proceeding with kidney transplantation, it should not be ignored. Future studies are needed to investigate the long‐term effects of varying levels of pre‐transplant DSA on outcomes.

Sensitization and Desensitization in Vascularized Composite Allotransplantation

Vascularized composite allotransplantation (VCA) is a field under research and has emerged as an alternative option for the repair of severe disfiguring defects that result from severe tissue loss in a selected group of patients. Lifelong immunosuppressive therapy, immunosuppression associated complications, and the effects of the host immune response in the graft are major concerns in this type of quality-of-life transplant. The initial management of extensive soft tissue injury can lead to the development of anti-HLA antibodies through injury-related factors, transfusion and cadaveric grafting. The role of antibody-mediated rejection, donor-specific antibody (DSA) formation and graft rejection in the context of VCA still remain poorly understood. The most common antigenic target of preexisting alloantibodies are MHC mismatches, though recognition of ABO incompatible antigens, minor histocompatibility complexes and endothelial cells has also been shown to contribute to rejection. Mechanistically, alloantibody-mediated tissue damage occurs primarily through complement fixation as well as through antibody-dependent cellular toxicity. If DSA exist, activation of complement and coagulation cascades can result in vascular thrombosis and infarction and thus rejection and graft loss. Both preexisting DSA but especially de-novo DSA are currently considered as main contributors to late allograft injury and graft failure. Desensitization protocols are currently being developed for VCA, mainly including removal of alloantibodies whereas treatment of established antibody-mediated rejection is achieved through high dose intravenous immunoglobulins. The long-term efficacy of such therapies in sensitized VCA recipients is currently unknown. The current evidence base for sensitizing events and outcomes in reconstructive transplantation is limited. However, current data show that VCA transplantation has been performed in the setting of HLA-sensitization.

Synergistic impact of pre-sensitization and delayed graft function on allograft rejection in deceased donor kidney transplantation

The aim of this study is to investigate whether or not delayed graft function (DGF) and pre-transplant sensitization have synergistic adverse effects on allograft outcome after deceased donor kidney transplantation (DDKT) using the Korean Organ Transplantation Registry (KOTRY) database, the nationwide prospective cohort. The study included 1359 cases between May 2014 and June 2019. The cases were divided into 4 subgroups according to pre-sensitization and the development of DGF post-transplant [non-pre-sensitized-DGF(−) (n = 1097), non-pre-sensitized-DGF(+) (n = 127), pre-sensitized-DGF(−) (n = 116), and pre-sensitized-DGF(+) (n = 19)]. We compared the incidence of biopsy-proven allograft rejection (BPAR), time-related change in allograft function, allograft or patient survival, and post-transplant complications across 4 subgroups. The incidence of acute antibody-mediated rejection (ABMR) was significantly higher in the pre-sensitized-DGF(+) subgroup than in other 3 subgroups. In addition, multivariable cox regression analysis demonstrated that pre-sensitization combined with DGF is an independent risk factor for the development of acute ABMR (hazard ratio 4.855, 95% confidence interval 1.499–15.727). Moreover, DGF and pre-sensitization showed significant interaction (p-value for interaction = 0.008). Pre-sensitization combined with DGF did not show significant impact on allograft function, and allograft or patient survival. In conclusion, the combination of pre-sensitization and DGF showed significant synergistic interaction on the development of allograft rejection after DDKT.

A Medication Adherence Promotion System to Reduce Late Kidney Allograft Rejection: A Quality Improvement Study

RATIONALE AND OBJECTIVE

Adolescent and young adult kidney transplant recipients have high risk of rejection related to suboptimal adherence. Multi-component interventions improve adherence in controlled trials, but clinical implementation is lacking. We describe an initiative to reduce allograft rejection using evidence-based adherence promotion clinical strategies.

STUDY DESIGN

Interrupted time series.

SETTING AND PARTICIPANTS

Kidney transplant recipients cared for at Cincinnati Children's Hospital ≥1 year post-transplant and taking ≥1 immunosuppressive medication from 2014 through 2017.

QUALITY IMPROVEMENT ACTIVITIES

The following interventions were implemented over 14 months: 1) adherence promotion training for clinical staff, 2) EHR-supported adherence risk screening, 3) systematic assessment of medication adherence barriers, 4) designation of specific staff to address adherence barriers, 5) shared decision-making with the patients to overcome adherence barriers, 6) follow-up to assess progress, 7) optional electronic medication monitoring.

OUTCOMES

Primary Outcome: Late acute rejection. Process measures: barriers assessments performed, barriers identified, number of interventions performed. Secondary outcomes/balancing measures: de novo DSA, biopsy rate, rejections per biopsy.

ANALYTICAL APPROACH

Time series analysis using statistical process control, evaluated patient-days between acute rejections as well as monthly rejections per 100 patient-months before and after implementation. To control for known rejection risk factors including changes in treatment and case mix, multivariable analyses were performed.

RESULTS

The monthly rejection rate fell from 1.61 rejections/100 patient-months in the 26-months pre-implementation to 0.88 rejections/100 patient-months in the 22-months post-implementation. In multivariable analysis, MAPS was associated with a 50% reduction in rejection incidence (IRR 0.50, 95% CI: 0.27-0.91, p=0.02). DSA and time since transplant were also associated with rejection incidence (IRR 2.27, p=0.02 and IRR 0.87, p=0.02, respectively) LIMITATIONS: A single center study. Potential confounding by unmeasured variables.

CONCLUSIONS

Clinical implementation of evidence-based adherence-promotion strategies was associated with a 50% reduction in acute rejection incidence over two years.

Predicting acute rejection in children, adolescents, and young adults with a kidney transplant by assessing barriers to taking medication

BACKGROUND

Nonadherence to immunosuppression is common among pediatric, adolescent, and young adult kidney transplant recipients and a leading cause of graft loss. Assessing barriers to medication adherence in clinical practice may identify patients at risk for rejection and provide therapeutic targets.

METHODS

Kidney transplant patients and/or their caregivers were assessed for 14 barriers to medication adherence using the barriers assessment tool. We compared rejection rates between patients with at least one reported adherence barrier to those without reported adherence barriers using a Kaplan-Meier estimator and Cox proportional hazard models to adjust for other mediators of acute rejection at 2 years following barriers assessment.

RESULTS

Ninety-eight patients were assessed for barriers to adherence. Over the 2-year observation period, 22 patients developed biopsy-proven acute rejection (BPAR). Kaplan-Meier estimates show that patients with an identified barrier to adherence were more likely to have BPAR (p = 0.02) than patients without an identified barrier in the 24 months following barriers assessment. The median time to rejection for patients who experienced acute rejection was 175.5 days (IQR 63-276 days) from the time of barriers assessment. An identified barrier to adherence remained the only statistically significant predictor of BPAR with Cox modeling (HR 2.6, p = 0.04), after accounting for age, sex, and race.

CONCLUSIONS

Pediatric and adolescent kidney transplant recipients with identified adherence barriers are at increased risk for acute rejection. Barriers to adherence provide a potentially modifiable therapeutic target that can be assessed in clinic to guide targeted interventions.

Acute rejection and growth outcomes in paediatric kidney allograft recipients treated with a corticosteroid minimisation immunosuppressive protocol

BACKGROUND

Corticosteroid minimisation immunosuppressive protocols (CMP) for children are an approach to safely reduce unwanted medication side effects associated with long-term exposure following kidney transplantation. Here, we provide data regarding the incidence of acute rejection and growth over an extended follow-up in children receiving the CMP used in our centre.

METHODS

We retrospectively analysed all children treated with a CMP who received a kidney transplant and had follow-up care in our centre between 2009 and 2019. Data were compared to 5 control groups from recent studies.

RESULTS

Ninety-nine kidney allograft recipients were included in the study (mean follow-up 4.4 years). There was no difference in the cumulative frequency of acute rejection in CMP-treated graft recipients compared to controls. Graft function at latest follow-up was significantly lower in graft recipients experiencing acute rejection compared to those without acute rejection (53.7 mL/min/1.73 m² vs. 66.8 mL/min/1.73 m², p = 0.021). Children experiencing >1 acute rejection episode had a greatly elevated risk of graft failure (p = 0.0009, OR 68.25). At latest follow-up, 64/90 (71.1%) graft recipients had a normal height, and younger graft recipients demonstrated greater catch up growth than older children. CMP-treated graft recipients showed a reduced rate of height deficit (28.9% vs. 55.1%, p = 0.0025), less obesity (12.2% vs. 23.9%, p = 0.031), and reduced rates of hypertension (35.4% vs. 68.2%, p< 0.0001).

CONCLUSIONS

Children treated with a CMP show greater height attainment, lower frequency of obesity, and reduced rates of hypertension, without an increased risk of acute rejection. Graphical abstract.

COVID-19 in pediatric kidney transplantation: The Improving Renal Outcomes Collaborative

There are limited data on the impact of COVID-19 in children with a kidney transplant (KT). We conducted a prospective cohort study through the Improving Renal Outcomes Collaborative (IROC) to collect clinical outcome data about COVID-19 in pediatric KT patients. Twenty-two IROC centers that care for 2732 patients submitted testing and outcomes data for 281 patients tested for SARS-CoV-2 by PCR. Testing indications included symptoms and/or potential exposures to COVID-19 (N = 134, 47.7%) and/or testing per hospital policy (N = 154, 54.8%). Overall, 24 (8.5%) patients tested positive, of which 15 (63%) were symptomatic. Of the COVID-19-positive patients, 16 were managed as outpatients, six received non-ICU inpatient care and two were admitted to the ICU. There were no episodes of respiratory failure, allograft loss, or death associated with COVID-19. To estimate incidence, subanalysis was performed for 13 centers that care for 1686 patients that submitted all negative and positive COVID-19 results. Of the 229 tested patients at these 13 centers, 10 (5 asymptomatic) patients tested positive, yielding an overall incidence of 0.6% and an incidence among tested patients of 4.4%. Pediatric KT patients in the United States had a low estimated incidence of COVID-19 disease and excellent short-term outcomes.

Multiplex gene analysis reveals T-cell and antibody-mediated rejection-specific upregulation of complement in renal transplants

In renal transplantation, complement is involved in ischemia reperfusion injury, graft rejection and dysfunction. However, it is still unclear how induction of complement and its activation are initiated. Using allograft biopsies of a well-characterized cohort of 28 renal transplant patients with no rejection (Ctrl), delayed graft function (DGF), acute T-cell-mediated (TCMR) or antibody-mediated rejection (ABMR) we analyzed differences in complement reaction. For that mRNA was isolated from FFPE sections, quantified with a multiplex gene expression panel and correlated with transplant conditions and follow-up of patients. Additionally, inflammatory cells were quantified by multiplex immunohistochemistry. In allograft biopsies with TCMR and ABMR gene expression of C1QB was 2-4 fold elevated compared to Ctrl. In TCMR biopsies, mRNA counts of several complement-related genes including C1S, C3, CFB and complement regulators CFH, CR1 and SERPING1 were significantly increased compared to Ctrl. Interestingly, expression levels of about 75% of the analyzed complement related genes correlated with cold ischemia time (CIT) and markers of inflammation. In conclusion, this study suggest an important role of complement in transplant pathology which seems to be at least in part triggered by CIT. Multiplex mRNA analysis might be a useful method to refine diagnosis and explore new pathways involved in rejection.

Impact of Early Pancreatic Graft Loss on Outcome after Simultaneous Pancreas-Kidney Transplantation (SPKT)-A Landmark Analysis

(1) Background: Simultaneous pancreas-kidney transplantation (SPKT) is a standard therapeutic option for patients with diabetes mellitus type I and kidney failure. Early pancreas allograft failure is a complication potentially associated with worse outcomes. (2) Methods: We performed a landmark analysis to assess the impact of early pancreas graft loss within 3 months on mortality and kidney graft survival over 10 years. This retrospective single-center study included 114 adult patients who underwent an SPKT between 2005 and 2018. (3) Results: Pancreas graft survival rate was 85.1% at 3 months. The main causes of early pancreas graft loss were thrombosis (6.1%), necrosis (2.6%), and pancreatitis (2.6%). Early pancreas graft loss was not associated with reduced patient survival (p = 0.168) or major adverse cerebral or cardiovascular events over 10 years (p = 0.741) compared to patients with functioning pancreas, after 3 months. Moreover, kidney graft function (p = 0.494) and survival (p = 0.461) were not significantly influenced by early pancreas graft loss. (4) Conclusion: In this study, using the landmark analysis technique, early pancreas graft loss within 3 months did not significantly impact patient or kidney graft survival over 10 years.

Suppression of Inflammation-Associated Kidney Damage Post-Transplant Using the New PrC-210 Free Radical Scavenger in Rats

Allograft kidney transplantation, which triggers host cellular- and antibody-mediated rejection of the kidney, is a major contributor to kidney damage during transplant. Here, we asked whether PrC-210 would suppress damage seen in allograft kidney transplant. Brown Norway (BN) rat kidneys were perfused in situ (UW Solution) with or without added 30 mM PrC-210, and then immediately transplanted into Lewis (LEW) rats. 20 h later, the transplanted BN kidneys and LEW rat plasma were analyzed. Kidney histology, and kidney/serum levels of several inflammation-associated cytokines, were measured to assess mismatch-related kidney pathology, and PrC-210 protective efficacy. Twenty hours after the allograft transplants: (i) significant histologic kidney tubule damage and mononuclear inflammatory cell infiltration were seen in allograft kidneys; (ii) kidney function metrics (creatinine and BUN) were significantly elevated; (iii) significant changes in key cytokines, i.e., TIMP-1, TNF-alpha and MIP-3A/CCL20, and kidney activated caspase levels were seen. In PrC-210-treated kidneys and recipient rats, (i) kidney histologic damage (Banff Scores) and mononuclear infiltration were reduced to untreated background levels; (ii) creatinine and BUN were significantly reduced; and (iii) activated caspase and cytokine changes were significantly reduced, some to background. In conclusion, the results suggest that PrC-210 could provide broadly applicable organ protection for many allograft transplantation conditions; it could protect transplanted kidneys during and after all stages of the transplantation process-from organ donation, through transportation, re-implantation and the post-operative inflammation-to minimize acute and chronic rejection.

HLA Antibody Incompatible Renal Transplantation: Long-term Outcomes Similar to Deceased Donor Transplantation

Background.

HLA incompatible renal transplantation still remains one of best therapeutic options for a subgroup of patients who are highly sensitized and difficult to match but not much is known about its long-term graft and patient survival.

Methods.

One hundred thirty-four HLA incompatible renal transplantation patients from 2003 to 2018 with a median follow of 6.93 y were analyzed retrospectively to estimate patient and graft survivals. Outcomes were compared with groups defined by baseline crossmatch status and the type and timings of rejection episodes.

Results.

The overall patient survival was 95%, 90%, and 81%; and graft survival was 95%, 85%, and 70% at 1, 5, and 10 y, respectively. This was similar to the first-time deceased donor transplant cohort. The graft survival for pretreatment cytotoxic-dependent crossmatch (CDC) positive crossmatch group was significantly low at 83%, 64%, and 40% at 1, 5, and 10 y, respectively, compared with other groups (Bead/CDC, P = 0.007; CDC/Flow, P = 0.001; and microbead assay/flow cytometry crossmatch, P = 0.837), although those with a low CDC titer (<1 in 2) have comparable outcomes to the CDC negative group. Female patients in general fared worse in both patient and graft survival outcomes in each of the 3 groups based on pretreatment crossmatch, although this did not reach statistical significance. Antibody-mediated rejection was the most frequent type of rejection with significant decline in graft survival by 10 y when compared with no rejection (P < 0.001). Rejection that occurred or continued to occur after the first 2 wk of transplantation caused a significant reduction in graft survivals (P < 0.001), whereas good outcomes were seen in those with a single early rejection episode.

Conclusions.

One-, 5-, and 10-y HLA incompatible graft and patient survival is comparable to deceased donor transplantation and can be further improved by excluding high-CDC titer cases. Antibody-positive female patients show worse long-term survival. Resolution of early rejection is associated with good long-term graft survival.

Transitional B cell cytokines predict renal allograft outcomes

Early immunological biomarkers that predict rejection and chronic allograft loss are needed to inform preemptive therapy and improve long-term outcomes. Here, we prospectively examined the ratio of interleukin-10 (IL-10) to tumor necrosis factor-α (TNFα) produced by transitional-1 B cells (T1B) 3 months after transplantation as a predictive biomarker for clinical and subclinical renal allograft rejection and subsequent clinical course. In both Training (n = 162) and Internal Validation (n = 82) Sets, the T1B IL-10/TNFα ratio 3 months after transplantation predicted both clinical and subclinical rejection anytime in the first year. The biomarker also predicted subsequent late rejection with a lead time averaging 8 months. Among biomarker high-risk patients, 60% had early rejection, of which 48% recurred later in the first posttransplant year. Among high-risk patients without early rejection, 74% developed rejection later in the first year. In contrast, only 5% of low-risk patients had early and 5% late rejection. The biomarker also predicted rejection in an External Validation Set (n = 95) and in key patient subgroups, confirming generalizability. Biomarker high-risk patients exhibited progressively worse renal function and decreased 5-year graft survival compared to low-risk patients. Treatment of B cells with anti-TNFα in vitro augmented the IL-10/TNFα ratio, restored regulatory activity, and inhibited plasmablast differentiation. To conclude, the T1B IL-10/TNFα ratio was validated as a strong predictive biomarker of renal allograft outcomes and provides a rationale for preemptive therapeutic intervention with TNF blockade.

Phosphorylated S6 ribosomal protein expression by immunohistochemistry correlates with de novo donor-specific HLA antibodies in lung allograft recipients

BACKGROUND

Per the ISHLT 2016 definition, a C4d-positive lung biopsy is required to meet criteria for definite antibody-mediated rejection (AMR). Unfortunately, C4d has poor sensitivity and specificity, and low inter-rater reliability. Phosphorylated S6 ribosomal protein (p-S6RP) expressed via the mTOR pathway has been shown to be a biomarker of AMR and correlates with donor-specific antibodies (DSA) in heart allografts. However, p-S6RP immunohistochemistry (IHC) in the setting of pulmonary AMR has yet to be evaluated. We sought to determine whether p-S6RP IHC performed on lung biopsies correlates with de novo DSA.

METHODS

IHC for p-S6RP performed on 26 biopsies from lung transplant recipients with de novo HLA DSA (DSA+) and 28 biopsies from patients with no DSA (DSA-) were evaluated by 3 pathologists who independently scored the degree of alveolar macrophage and pneumocyte staining. Staining in ≥50% of the biopsy as determined by at least 2 pathologists was considered positive.

RESULTS

Twenty-one (81%) DSA+ biopsies stained positive for p-S6RP in pneumocytes and 21 (81%) in macrophages. Six DSA- biopsies (21%) stained positive for p-S6RP in pneumocytes, 6 (21%) were positive in macrophages. Pneumocyte p-S6RP staining was 81% sensitive and 79% specific for DSA. Macrophage staining showed the same sensitivity and specificity but with lower inter-rater agreement (κ = 0.53 vs 0.68).

CONCLUSIONS

This study demonstrates a positive relationship between de novo DSA and p-S6RP expression in pneumocytes and macrophages using IHC. p-S6RP is relatively sensitive and specific, and has superior inter-rater reliability compared to C4d.

Recipient myeloperoxidase-producing cells regulate antibody-mediated acute versus chronic kidney allograft rejection

Antibody-mediated rejection (ABMR) continues to be a major problem undermining the success of kidney transplantation. Acute ABMR of kidney grafts is characterized by neutrophil and monocyte margination in the tubular capillaries and by graft transcripts indicating NK cell activation, but the myeloid cell mechanisms required for acute ABMR have remained unclear. Dysregulated donor-specific antibody (DSA) responses with high antibody titers are induced in B6.CCR5-/- mice transplanted with complete MHC-mismatched A/J kidneys and are required for rejection of the grafts. This study tested the role of recipient myeloid cell production of myeloperoxidase (MPO) in the cellular and molecular components of acute ABMR. Despite induction of equivalent DSA titers, B6.CCR5-/- recipients rejected A/J kidneys between days 18 and 25, with acute ABMR, whereas B6.CCR5-/-MPO-/- recipients rejected the grafts between days 46 and 54, with histopathological features of chronic graft injury. On day 15, myeloid cells infiltrating grafts from B6.CCR5-/- and B6.CCR5-/-MPO-/- recipients expressed marked phenotypic and functional transcript differences that correlated with the development of acute versus chronic allograft injury, respectively. Near the time of peak DSA titers, activation of NK cells to proliferate and express CD107a was decreased within allografts in B6.CCR5-/-MPO-/- recipients. Despite high titers of DSA, depletion of neutrophils reproduced the inhibition of NK cell activation and decreased macrophage infiltration but increased monocytes producing MPO. Overall, recipient myeloid cells producing MPO regulate graft-infiltrating monocyte/macrophage function and NK cell activation that are required for DSA-mediated acute kidney allograft injury, and their absence switches DSA-mediated acute pathology and graft outcomes to chronic ABMR.

Non-HLA Antibodies and Epitope Mismatches in Kidney Transplant Recipients With Histological Antibody-Mediated Rejection

Background

Correlation between antibody-mediated rejection (ABMR) and circulating HLA donor-specific antibodies (HLA-DSA) is strong but imperfect in kidney transplant (KT) recipients, raising the possibility of undetected HLA-DSA or non-HLA antibodies contributing to ABMR. Detailed evaluation of the degree of HLA matching together with the identification of non-HLA antibodies in KT may help to decipher the antibody involved.

Methods

We retrospectively assessed patients with transplant biopsies scored following Banff'15 classification. Pre- and post-transplant serum samples were checked for HLA and non-HLA antibodies [MICA-Ab, angiotensin-II type-1-receptor (AT1R)-Ab, endothelin-1 type-A-receptor (ETAR)-Ab and crossmatches with primary aortic endothelial cells (EC-XM)]. We also analyzed HLA epitope mismatches (HLA-EM) between donors and recipients to explore their role in ABMR histology (ABMRh) with and without HLA-DSA.

Results

One-hundred eighteen patients with normal histology (n = 19), ABMRh (n = 52) or IFTA (n = 47) were studied. ABMRh patients were HLA-DSApos (n = 38, 73%) or HLA-DSAneg (n = 14, 27%). Pre-transplant HLA-DSA and AT1R-Ab were more frequent in ABMRh compared with IFTA and normal histology cases (p = 0.006 and 0.003), without differences in other non-HLA antibodies. Only three ABMRhDSAneg cases showed non-HLA antibodies. ABMRhDSAneg and ABMRhDSApos cases showed similar biopsy changes and graft-survival. Both total class II and DRB1 HLA-EM were associated with ABMRhDSApos but not with ABMRhDSAneg. Multivariate analysis showed that pre-transplant HLA-DSA (OR: 3.69 [1.31-10.37], p = 0.013) and AT1R-Ab (OR: 5.47 [1.78-16.76], p = 0.003) were independent predictors of ABMRhDSApos.

Conclusions

In conclusion, pre-transplant AT1R-Ab is frequently found in ABMRhDSApos patients. However, AT1R-Ab, MICA-Ab, ETAR-Ab or EC-XM+ are rarely found among ABMRhDSAneg patients. Pre-transplant AT1R-Ab may act synergistically with preformed or de novo HLA-DSA to produce ABMRhDSApos but not ABMRhDSAneg. HLA epitope mismatch associates with ABMRhDSApos compared with ABMRhDSAneg, suggesting factors other than HLA are responsible for the damage.

Kidney transplantation outcomes in lupus nephritis: A 37-year single-center experience from Latin America

OBJECTIVE

We assessed patient and graft outcomes and prognostic factors in kidney transplantation in patients with end-stage kidney disease (ESKD) secondary to lupus nephritis (LN) undergoing kidney transplantation from August 1977 to December 2014 in a Latin American single center.

METHODS

The primary endpoint was patient survival, and the secondary endpoints were death-censored graft survival for the first renal transplant and the rate of recurrent LN (RLN). Kaplan-Meier method was used for survival analysis. Factors predicting patient and death-censored graft survivals were examined by Cox proportional-hazards regression analyses.

RESULTS

185 patients were retrospectively evaluated. Patient survival rates were 88% at one year, 82% at three years, 78% at five years, and 67% at ten years. Death-censored graft survival for the first renal transplant was 93% at one year, 89% at three years, 87% at five years, and 80% at ten years. RLN was diagnosed in 2 patients (1.08%), but no graft was lost because of RLN. Thirty-nine (21.1%) patients died, and 65 (35.1%) patients experienced graft loss during the follow-up. By multivariable analyses, older recipient age and 1-month posttransplantation eGFR <45 ml/min/1.73m² were associated with lower patient survival and an increased risk of graft loss, while induction immunosuppressive therapy exerted a protective effect on patients' survival. In the subgroup of patients in whom disease activity was measured at the time of transplantation, a higher SLEDAI score was also associated with lower patient survival and an increased risk of graft loss.

CONCLUSION

In a mostly Mestizo population, kidney transplantation is an excellent therapeutic alternative in LN patients with ESKD. Older recipient age, an eGFR <45 ml/min/1.73m² at one month posttransplantation, and disease activity at the time of transplantation are predictive of a lower patient and death-censored graft survival, while induction immunosuppressive therapy has a protective effect on patient survival. RLN is rare and does not influence the risk of graft loss.

Impact of CYP3A5 phenotype on tacrolimus time in therapeutic range and clinical outcomes in pediatric renal and heart transplant recipients

STUDY OBJECTIVE

This study investigated the effect of CYP3A5 phenotype on time in therapeutic range (TTR) of tacrolimus post-transplant in pediatric patients.

DESIGN AND DATA SOURCE

This retrospective study assessed medical records of pediatric kidney and heart recipients with available CYP3A5 genotype for tacrolimus dosing, troughs, and the clinical events (biopsy-proven acute rejection [BPAR] and de novo donor-specific antibodies [dnDSA]).

MEASUREMENTS AND MAIN RESULTS

The primary outcome, mean TTR in the first 90 days post-transplant, was 9.0% (95% CI: -16.1, -1.9) lower in CYP3A5 expressers (p = 0.014) when adjusting for time to therapeutic concentration and organ type. There was no difference between CYP3A5 phenotypes in time to the first clinical event using TTR during the first 90 days. When applying TTR over the first year, there was a significant difference in event-free survival (EFS) which was 50.0% for CYP3A5 expressers/TTR < 35%, 45.5% for expressers/TTR ≥ 35%, 38.1% for nonexpressers/TTR < 35%, and 72.9% for nonexpressers/TTR ≥ 35% (log-rank p = 0.03). A post hoc analysis of EFS identified CYP3A5 expressers had lower EFS compared to nonexpressers in patients with TTR ≥ 35% (p = 0.04) but no difference among patients with TTR < 35% (p = 0.6).

CONCLUSIONS

The relationship between TTR and CYP3A5 phenotype suggests that achieving a TTR ≥ 35% during the first year may be a modifiable factor to attenuate the risk of BPAR and dnDSA.

Revisiting the changes in the Banff classification for antibody-mediated rejection after kidney transplantation

The Banff classification for antibody-mediated rejection (ABMR) has undergone important changes, mainly by inclusion of C4d-negative ABMR in Banff'13 and elimination of suspicious ABMR (sABMR) with the use of C4d as surrogate for HLA-DSA in Banff'17. We aimed to evaluate the numerical and prognostic repercussions of these changes in a single-center cohort study of 949 single kidney transplantations, comprising 3662 biopsies that were classified according to the different versions of the Banff classification. Overall, the number of ABMR and sABMR cases increased from Banff'01 to Banff'13. In Banff'17, 248 of 292 sABMR biopsies were reclassified to No ABMR, and 44 of 292 to ABMR. However, reclassified sABMR biopsies had worse and better outcome than No ABMR and ABMR, which was mainly driven by the presence of microvascular inflammation and absence of HLA-DSA, respectively. Consequently, the discriminative performance for allograft failure was lowest in Banff'17, and highest in Banff'13. Our data suggest that the clinical and histological heterogeneity of ABMR is inadequately represented in a binary classification system. This study provides a framework to evaluate the updates of the Banff classification and assess the impact of proposed changes on the number of cases and risk stratification. Two alternative classifications introducing an intermediate category are explored.

A 2020 Banff Antibody-mediatedInjury Working Group examination of international practices for diagnosing antibody-mediated rejection in kidney transplantation - a cohort study

The Banff antibody-mediated rejection (ABMR) classification is vulnerable to misinterpretation, but the reasons are unclear. To better understand this vulnerability, we evaluated how ABMR is diagnosed in practice. To do this, the Banff Antibody-Mediated Injury Workgroup electronically surveyed an international cohort of nephrologists/surgeons (n = 133) and renal pathologists (n = 99). Most providers (97%) responded that they use the Banff ABMR classification at least sometimes, but DSA information is often not readily available. Only 41.1% (55/133) of nephrologists/surgeons and 19.2% (19/99) of pathologists reported that they always have DSA results when the biopsy is available. Additionally, only 19.6% (26/133) of nephrologists/surgeons responded that non-HLA antibody or molecular transcripts are obtained when ABMR histologic features are present but DSA is undetected. Several respondents agreed that histologic features concerning for ABMR in the absence of DSA and/or C4d are not well accounted for in the current classification [31.3% (31/99) pathologists and 37.6% (50/133) nephrologist/surgeons]. The Banff ABMR classification appears widely accepted, but efforts to improve the accessibility of DSA information for the multidisciplinary care team are needed. Further clarity is also needed in Banff ABMR nomenclature to account for the spectrum of ABMR and for histologic features suspicious for ABMR when DSA is absent.

Renal allograft DARCness in subclinical acute and chronic active ABMR

Gene expression profiling of renal allograft biopsies revealed the Duffy antigen receptor for chemokines (DARC) as being strikingly upregulated in antibody‐mediated rejection (ABMR). DARC has previously been shown to be associated with endothelial injury. This study aimed at assessing the value of DARC immunohistochemistry as diagnostic marker in ABMR. The study was performed on 82 prospectively collected biopsies of a clinically well‐defined population (BORTEJECT trial, NCT01873157) of DSA‐positive patients with gene expression data available for all biopsies. Diagnostic histologic assessment of biopsies was performed according to the Banff diagnostic scheme. DARC expression was focally accentuated, on peritubular capillaries (PTC) mostly in areas of interstitial fibrosis and/or inflammation. DARC positivity was associated with diagnosis of ABMR and correlated with DARC gene expression levels detected by microarray analysis. Still, as previously described, a substantial number of biopsies without signs of rejection showed DARC‐positive PTC. We did not observe significantly reduced graft survival in cases showing histologic signs of ABMR and being DARC‐positive, as compared to DARC‐negative ABMR. In summary, the upregulation of DARC, detected by immunohistochemistry, is associated with but not specific for ABMR. We did not observe reduced graft survival in DARC‐positive patients.

Role of the IL-33/ST2 pathway in renal allograft rejection

The interleukin-33 (IL-33)/suppression of tumorigenicity 2 (ST2) pathway modulates immune response and inflammation, associated with allograft dysfunction and rejection. We hypothesized that IL-33/ST2 is a marker of renal allograft rejection and IL-33/ST2 expression may differ according to rejection type. IL-33/ST2 expression was measured in sera and kidney tissues from recipients with acute antibody-mediated rejection (AAMR), acute cell-mediated rejection (ACMR), chronic antibody-mediated rejection (CAMR), and healthy controls. The soluble ST2 and IL-33/ST2 expression levels were higher in participants with all three rejection types than in controls. Although the expression levels in recipients with AAMR and ACMR were significantly higher than those with CAMR, there was no significant difference between the expression levels in AAMR and ACMR. Although IL-33, IL-8, and fibronectin expression were significantly increased after the addition of the recipients' serum in primary cultured human renal proximal tubular epithelial cells, the levels decreased after treatment with an anti-ST2 antibody. Furthermore, the anti-ST2 antibody specifically suppressed the upregulation of the mixed lymphocyte reaction. Boyden chamber assays demonstrated that anti-ST2 antibody abrogated chemotaxis induced by recombinant IL-33. Thus, IL-33 and ST2 are potent mediators of rejection. Treatment with an anti-ST2 antibody ameliorates rejection and could be a potential therapeutic strategy for renal allograft rejection.

The Continuing Need for Electron Microscopy in Examination of Medical Renal Biopsies: Examples in Practice

Background

For the better part of the past 6 decades, transmission electron microscopy (EM), together with routine light microscopy and immunofluorescence and/or immunohistochemistry (IHC), has been an essential component of the diagnostic workup of medical renal biopsies, particularly native renal biopsies, with increasing frequency in renal allograft biopsies as well. Studies performed prior to the year 2000 have indeed shown that a substantial fraction of renal biopsies cannot be accurately diagnosed without EM. Still, EM remains costly and labor-intensive, and with increasing pressure to reduce healthcare costs, some centers are de-emphasizing diagnostic EM. This trend has been coupled with advances in IHC and other methods in renal biopsy diagnosis over the past 2-3 decades.

Summary

Nonetheless, it has been our experience that the diagnostic value of EM in the comprehensive evaluation of renal biopsies remains similar to what it was 20-30 years ago. In this review, we provide several key examples from our practice where EM was essential in making the correct renal biopsy diagnosis, ranging from relatively common glomerular lesions to rare diseases.

Key Messages

EM remains an important component of the diagnostic evaluation of medical renal biopsies. Failure to perform EM in certain cases will result in an incorrect diagnosis, with possible clinical consequences. We strongly recommend that tissue for EM be taken and stored in an appropriate fixative and ultrastructural studies be performed for all native renal biopsies, as well as appropriate renal allograft biopsies as recommended by the Banff consortium.

Integrative Analyses of Circulating Small RNAs and Kidney Graft Transcriptome in Transplant Glomerulopathy

Transplant glomerulopathy develops through multiple mechanisms, including donor-specific antibodies, T cells and innate immunity. This study investigates circulating small RNA profiles in serum samples of kidney transplant recipients with biopsy-proven transplant glomerulopathy. Among total small RNA population, miRNAs were the most abundant species in the serum of kidney transplant patients. In addition, fragments arising from mature tRNA and rRNA were detected. Most of the tRNA fragments were generated from 5′ ends of mature tRNA and mainly from two parental tRNAs: tRNA-Gly and tRNA-Glu. Moreover, transplant patients with transplant glomerulopathy displayed a novel tRNA fragments signature. Gene expression analysis from allograft tissues demonstrated changes in canonical pathways related to immune activation such as iCos-iCosL signaling pathway in T helper cells, Th1 and Th2 activation pathway, and dendritic cell maturation. mRNA targets of down-regulated miRNAs such as miR-1224-5p, miR-4508, miR-320, miR-378a from serum were globally upregulated in tissue. Integration of serum miRNA profiles with tissue gene expression showed that changes in serum miRNAs support the role of T-cell mediated mechanisms in ongoing allograft injury.

Impact of Subclinical and Clinical Kidney Allograft Rejection Within 1 Year Posttransplantation Among Compatible Transplant With Steroid Withdrawal Protocol

Early acute kidney rejection remains an important clinical issue.

Methods

The current study included 552 recipients who had 1-2 surveillance or indication biopsy within the 1 y posttransplant. We evaluated the impact of type of allograft inflammation on allograft outcome. They were divided into 5 groups: no inflammation (NI: 95), subclinical inflammation (SCI: 244), subclinical T cell-mediated rejection (TCMR) (SC-TCMR: 110), clinical TCMR (C-TCMR: 83), and antibody-mediated rejection (AMR: 20). Estimated glomerular filtration rate (eGFR) over time using linear mixed model, cumulative chronic allograft scores/interstitial fibrosis and tubular atrophy (IFTA) ≥2 at 12 mo, and survival estimates were compared between groups.

Results

The common types of rejections were C-TCMR (15%), SC-TCMR (19.9%), and AMR (3.6%) of patients. Eighteen of 20 patients with AMR had mixed rejection with TCMR. Key findings were as follows: (i) posttransplant renal function: eGFR was lower for patients with C-TCMR and AMR (P < 0.0001) compared with NI, SCI, and SC-TCMR groups. There was an increase in delta-creatinine from 3 to 12 mo and cumulative allograft chronicity scores at 12 mo (P < 0.001) according to the type of allograft inflammation. (ii) Allograft histology: the odds of IFTA ≥2 was higher for SC-TCMR (3.7 [1.3-10.4]; P = 0.04) but was not significant for C-TCMR (3.1 [1.0-9.4]; P = 0.26), and AMR (2.5 [0.5-12.8]; P = 0.84) compared with NI group, and (iii) graft loss: C-TCMR accounted for the largest number of graft losses and impending graft losses on long-term follow-up. Graft loss among patient with AMR was numerically higher but was not statistically significant.

Conclusions

The type of kidney allograft inflammation predicted posttransplant eGFR, cumulative chronic allograft score/IFTA ≥2 at 12 mo, and graft loss.

Early recognition of chronic rejection in a face allotransplant patient with alopecia

The features of chronic rejection (CR) in full-face vascularized composite allotransplantation (VCA) are not well-known. Herein, we report a full-face transplant patient that experienced two episodes of acute rejection (AR) and three episodes of AR/CR over the course of 6-years. The patient noticed a small, round patch of hair loss in his beard 9 months after the second AR episode, which occurred 21 months post-transplantation. Biopsy of the alopecic patch showed lichen-planopilaris-like features, which was suggestive of early CR. Despite an increase in immunosuppressive dosages, the alopecia progressed. Following the second and third AR/CR episodes, the alopecia became more pronounced, with the addition of hyperpigmentation as well as sclerosis and telangiectasia. The findings of multiple biopsies showed CR. Based on these findings we think that alopecia with lichen-planopilaris-like histopathological features similar to grade III AR features, particularly in hair follicles appears to be an early finding of CR in the presented patient. The findings further indicate that follicular involvement may be a significant feature of CR in VCA patients and that it can present prior to sclerosis, vasculopathy, or loss of adnexa. The present case is uniquely important because of the distinctive presentation of CR, with hair follicles clinically and histopathologically affected, leading to progressive and irreversible alopecia with lichen-planopilaris-like histopathology.

Measuring the Impact of Targeting FcRn-Mediated IgG Recycling on Donor-Specific Alloantibodies in a Sensitized NHP Model

Background

In transplantation, plasmapheresis and IVIg provide the mainstay of treatment directed at reducing or removing circulating donor-specific antibody (DSA), yet both have limitations. We sought to test the efficacy of targeting the IgG recycling mechanism of the neonatal Fc receptor (FcRn) using anti-FcRn mAb therapy in a sensitized non-human primate (NHP) model, as a pharmacological means of lowering DSA.

Methods

Six (6) rhesus macaque monkeys, previously sensitized by skin transplantation, received a single dose of 30mg/kg anti-RhFcRn IV, and effects on total IgG, as well as DSA IgG, were measured, in addition to IgM and protective immunity. Subsequently, 60mg/kg IV was given in the setting of kidney transplantation from skin graft donors. Kidney transplant recipients received RhATG, and tacrolimus, MMF, and steroid for maintenance immunosuppression.

Results

Circulating total IgG was reduced from a baseline 100% on D0 to 32.0% (mean, SD ± 10.6) on d4 post infusion (p<0.05), while using a DSA assay. T-cell flow cross match (TFXM) was reduced to 40.6±12.5% of baseline, and B-cell FXCM to 52.2±19.3%. Circulating total IgM and DSA IgM were unaffected by treatment. Pathogen-specific antibodies (anti-gB and anti-tetanus toxin IgG) were significantly reduced for 14d post infusion. Post-transplant, circulating IgG responded to anti-FcRn mAb treatment, but DSA increased rapidly.

Conclusion

Targeting the FcRn-mediated recycling of IgG is an effective means of lowering circulating donor-specific IgG in the sensitized recipient, although in the setting of organ transplantation mechanisms of rapid antibody rise post-transplant remains unaffected.

Correlation of Donor-Derived Cell-free DNA with Histology and Molecular Diagnoses of Kidney Transplant Biopsies

BACKGROUND

Circulating donor-derived cell free DNA (cfDNA), a minimally invasive diagnostic tool for kidney transplant rejection, was validated using traditional histology. The Molecular Microscope (MMDx) tissue gene expression platform may provide increased precision to traditional histology.

METHODS

In this single-center prospective study of 208 biopsies (median=5.8 months) post-transplant, we report on the calibration of cfDNA with simultaneous biopsy assessments using MMDx and histology by Area under the curve (AUC) analyses for optimal criterion, as well as for, previously published cfDNA cut-offs ≤0.21% to 'rule-out' rejection and ≥1% to 'rule-in' rejection.

RESULTS

There were significant discrepancies between histology and MMDx, with MMDx identifying more antibody-mediated rejection (65; 31%) than histology (43; 21%); the opposite was true for T-cell mediated rejection [TCMR; histology: 27 (13%) vs MMDx: 13 (6%)]. Most of the TCMR discrepancies were seen for histologic borderline/1A TCMR. AUC Curves for cfDNA and prediction of rejection were slightly better with MMDx (AUC=0.80; 95%CI: 0.74-0.86) vs. histology (AUC=0.75; 95%CI: 0.69-0.81). A cfDNA≤0.21% had similar sensitivity (~91%) to 'rule-out' rejection by histology and MMDx. Specificity was slightly higher with MMDx (92%) compared with histology (85%) to 'rule-in' rejection using cfDNA criterion≥1%. Strong positive quantitative correlations were observed between cfDNA scores and molecular acute kidney injury (AKI) for both 'rejection' and 'nonrejection' biopsies.

CONCLUSIONS

Molecular diagnostics using tissue gene expression and blood-based donor-derived cell-free DNA may add precision to some cases of traditional histology. The positive correlation of cfDNA with molecular AKI suggests a dose-dependent association with tissue injury irrespective of rejection characteristics.

Antibody-Mediated Rejection and Lung Transplantation

Antibody-mediated rejection (AMR) is now a widely recognized form of lung allograft rejection, with mounting evidence for AMR as an important risk factor for the development of chronic lung allograft dysfunction and markedly decreased long-term survival. Despite the recent development of the consensus diagnostic criteria, it remains a challenging diagnosis of exclusion. Furthermore, even after diagnosis, treatment directed at pulmonary AMR has been nearly exclusively derived from practices with other solid-organ transplants and other areas of medicine, such that there is a significant lack of data regarding the efficacy for these in pulmonary AMR. Lastly, outcomes after AMR remain quite poor despite aggressive treatment. In this review, we revisit the history of AMR in lung transplantation, describe our current understanding of its pathophysiology, discuss the use and limitations of the consensus diagnostic criteria, review current treatment strategies, and summarize long-term outcomes. We conclude with a synopsis of our most pressing gaps in knowledge, introduce recommendations for future directions, and highlight promising areas of active research.

Chronic Lung Allograft Dysfunction: Evolving Concepts and Therapies

The primary factor that limits long-term survival after lung transplantation is chronic lung allograft dysfunction (CLAD). CLAD also impairs quality of life and increases the costs of medical care. Our understanding of CLAD continues to evolve. Consensus definitions of CLAD and the major CLAD phenotypes were recently updated and clarified, but it remains to be seen whether the current definitions will lead to advances in management or impact care. Understanding the potential differences in pathogenesis for each CLAD phenotype may lead to novel therapeutic strategies, including precision medicine. Recognition of CLAD risk factors may lead to earlier interventions to mitigate risk, or to avoid risk factors all together, to prevent the development of CLAD. Unfortunately, currently available therapies for CLAD are usually not effective. However, novel therapeutics aimed at both prevention and treatment are currently under investigation. We provide an overview of the updates to CLAD-related terminology, clinical phenotypes and their diagnosis, natural history, pathogenesis, and potential strategies to treat and prevent CLAD.

First and second morning spot urine protein measurements for the assessment of proteinuria: a diagnostic accuracy study in kidney transplant recipients

BACKGROUND

Quantification of proteinuria in kidney transplant recipients is important for diagnostic and prognostic purposes. Apart from correlation tests, there have been few evaluations of spot urine protein measurements in kidney transplantation.

METHODS

In this cross-sectional study involving 151 transplanted patients, we investigated measures of agreement (bias and accuracy) between the estimated protein excretion rate (ePER), determined from the protein-to-creatinine ratio in the first and second morning urine, and 24-h proteinuria and studied their performance at different levels of proteinuria. Measures of agreement were reanalyzed in relation to allograft histology in 76 patients with kidney biopsies performed for cause before enrolment in the study.

RESULTS

For ePER in the first morning urine, percent bias ranged from 1 to 28% and accuracy (within 30% of 24-h collection) ranged from 56 to 73%. For the second morning urine, percent bias ranged from 2 to 11%, and accuracy ranged from 71 to 78%. The accuracy of ePER (within 30%) in first and second morning urine progressively increased from 56 and 71% for low-grade proteinuria (150-299 mg/day) to 60 and 74% for moderate proteinuria (300-999 mg/day), and to 73 and 78% for high-grade proteinuria (≥1000 mg/day). Measures of agreement were similar across histologic phenotypes of allograft injury.

CONCLUSIONS

The ability of ePER to accurately predict 24-h proteinuria in kidney transplant recipients is modest. However, accuracy improves with an increase in proteinuria. Given the similar accuracy of ePER measurements in first and second morning urine, second morning urine can be used to monitor protein excretion.

An Integrated Transcriptomic Approach to Identify Molecular Markers of Calcineurin Inhibitor Nephrotoxicity in Pediatric Kidney Transplant Recipients

Calcineurin inhibitors are highly efficacious immunosuppressive agents used in pediatric kidney transplantation. However, calcineurin inhibitor nephrotoxicity (CNIT) has been associated with the development of chronic renal allograft dysfunction and decreased graft survival. This study evaluated 37 formalin-fixed paraffin-embedded biopsies from pediatric kidney transplant recipients using gene expression profiling. Normal allograft samples (n = 12) served as negative controls and were compared to biopsies exhibiting CNIT (n = 11). The remaining samples served as positive controls to validate CNIT marker specificity and were characterized by other common causes of graft failure such as acute rejection (n = 7) and interstitial fibrosis/tubular atrophy (n = 7). MiRNA profiles served as the platform for data integration. Oxidative phosphorylation and mitochondrial dysfunction were the top molecular pathways associated with overexpressed genes in CNIT samples. Decreased ATP synthesis was identified as a significant biological function in CNIT, while key toxicology pathways included NRF2-mediated oxidative stress response and increased permeability transition of mitochondria. An integrative analysis demonstrated a panel of 13 significant miRNAs and their 33 CNIT-specific gene targets involved with mitochondrial activity and function. We also identified a candidate panel of miRNAs/genes, which may serve as future molecular markers for CNIT diagnosis as well as potential therapeutic targets.

The role of non-HLA antibodies in solid organ transplantation: a complex deliberation

PURPOSE OF REVIEW

There is tremendous interest in understanding when, if, and how non-HLA antibodies contribute to allograft injury. Numerous non-HLA target antigens have been identified and sensitization to these targets have been associated with delayed allograft function, rejection, and allograft failure. This review focuses on the clinical utility of HLA antibody testing, highlighting the strengths and limitations of current clinical studies, and the need for defining characteristics to inform non-HLA antibody pathogenicity.

RECENT FINDINGS

Clinical studies continue to show associations between non-HLA antibodies and rejection and reduced allograft survival across multiple transplanted organ types. The worst clinical outcomes continue to be observed among recipients testing positive for both non-HLA and donor-specific HLA antibodies. Mechanistic insights from both animal and clinical studies support a model in which tissue injury accompanied by an inflammatory environment influence non-HLA antibody formation and pathogenicity.

SUMMARY

Immune triggers that lead to non-HLA antibody formation and pathogenicity are complex and poorly understood. The ability of non-HLA antibodies to mediate allograft injury may depend upon their affinity and strength (titer), target specificity, density of the target antigen, and synergy with donor-specific HLA antibodies.