Transplant Glomerulopathy Research Articles

P1691URINARY CXCL10 AT SIX AND TWELVE MONTH PREDICTS SUBCLINICAL ANTIBODY MEDIATED REJECTION AT 1 YEAR

Abstract Background and Aims Despite the improvement in renal transplant results, the rate of graft loss from the first year has improved poorly, antibody-mediated rejection (AbMR) being the first cause of renal graft loss. Renal transplantation is usually monitored by measuring creatinine, proteinuria, immunosuppressive blood levels and, recently, donor specific antibodies and polyomavirus load. However, currently the only way to detect the alloimmune graft damage is to perform a surveillance o by indication renal biopsy. Non-invasive monitoring of the alloimmune response could contribute to improving renal transplant results. Previous studies have shown that urinary CXCL10 relates to both clinical and subclinical allograft rejection and graft loss. Our aim was to analyze the relationship between urinary CXCL10 and the biopsy findings of 1-year surveillance biopsies. Method From Dec/2013 to Nov/2017 90 surveillance biopsies were performed in our center at 1 year after kidney transplantation. Urine were prospectively collected at 6 and 12 month and urine samples were frozen at -70º. CXCL10 was measured by using human CXCL10/IP-10 DuoSet ELISA kits (R&D Systems) according to the protocols recommended by the company. Biopsies were classified according to Banff criteria. Results Median values of CXCL10 were 51.2 pg/ml (IQR 38.5 – 98.9 pg/ml) at 6 month and 62.8 pg/ml (IQR 42.7 – 99.4 pg/ml) at 12 month after transplantation. Both values were statistically related (r = 0.400, p = 0.012), and there were no significant statistical differences between both (Wilcoxon`s test p = 0.063). CXCL10 did not relate to serum creatinine, glomerular filtration rate, albuminuria, tacrolimus blood levels or prednisone dose at 1 year. Some 16.7% allograft biopsies showed subclinical cellular rejection, 26.7% showed antibody mediated rejection and 20.0% transplant glomerulopathy. Patients with antibody mediated rejection (AbMR) had higher levels of 1-year urinary CXCL10 [55.4 pg/ml (IQR 39.3) vs. 97.4 pg/ml (IQR 103.9), p = 0.021], lower GFR [68.0 ml/min/1.73m2 (IQR 33.5) vs. 43.5 ml/min/1.73m2 (IQR 22.8), p < 0.001] and similar albuminuria (p = 0.079). According to ROC curve, 1-year urinary CXCL10 could discriminate patients with subclinical AbMR (AUC-ROC 0.660, 95%CI 0.511-0.809, p = 0.021). After adjusting by GFR and albuminuria, 1-year urinary CXCL10 in a logarithmic scale was able to predict subclinical AbMR (OR 2.254, 95%CI 1.012-5.021, p = 0.047) by logistic regression analysis. Similarly, patients with subclinical AbMR at 1 year had higher levels of 6-month urinary CXCL10 [45.9 pg/ml (IQR 41.4) vs. 102.3 pg/ml (IQR 1935), p = 0.026]. Moreover, 6-month urinary CXCL10 could discriminate those patients who were going to show subclinical AbMR at 1-year (see figure; AUC-ROC 0.731, 95%CI 0.545-0.916, p = 0.027). After logistic regression, each tertil of 6-month urinary CXCL10 increased the risk of suffering subclinical AbMR more than thrice (OR 3.346, 95%CI 1.184-9.456, p = 0.023). Conclusion Both 6- and 12-month urinary CXCL10 relate to the diagnosis of subclinical AbMR by 1-year surveillance biopsies independently of other variables such as renal function and albuminuria. Of interest, by a non-invasive monitoring of urinary CXCL10 as early as at 6 months we can predict some subclinical histologic findings at 1 year, such as AbMR, that can have a strong impact on the transplant outcome.

P1626LIQUID BIOPSY IN RENAL TRANSPLANT: THE ROLE OF DONOR-DERIVED CELL-FREE DNA TO DETECT REJECTION

Abstract Background and Aims Circulating donor-derived cell-free DNA (dd-cfDNA) has recently been proposed as an early non-invasive marker for renal allograft rejection (Bloom et al, J. Am. Soc. Nephrol. 2017;28, 2221–2232). Recent studies demonstrated its potential role in the detection of any kind of rejection with better performance in detecting antibody-mediated rejection (ABMR) (Huang et al, Am J Transplant. 2019;19:1663–1670). However, at the current cutoff value for a positive test, the test seems to be affected by low sensitivity for T-cell mediated rejection (TCMR) and false positive results in the setting of non-rejection related damage. In the present study, the performance of dd-cfDNA is assessed on a retrospective series of transplant renal biopsies. Method Sixty-three renal biopsies from 52 allograft recipients with available dd-cfDNA results, evaluated between November 2017 and December 2019 at Vanderbilt University Medical Center, Nashville, Tennessee, were reviewed. Clinical and histological features along with the final diagnosis were recorded. Renal allograft rejection was classified following Banff 2013 criteria. Pearson’s chi-squared test was used to compare cases positive and negative for dd-cfDNA. Receiving operator curve (ROC) analysis was used to assess the performance of the test in detecting any rejection and ABMR. A p-value of <0.05 was considered statistically significant. Results The patients were 53±12.5 years old, 43% were men, 51% and 49% were Caucasian and African-American, respectively. The median value of dd-cfDNA was 2.6% for ABMR and 2.4% for any kind of rejection, statistically different from the group without rejection (0.56%, p = 0.002 and 0.0003, respectively). TCMR failed to demonstrate a statistically significant difference in dd-cfDNA levels vs controls (1.8% vs 0.56%, p = 0.627). The comparison of groups with positive and negative dd-cfDNA test is reported in Figure (panel A). Positive patients demonstrated a higher rate of findings associated with ABMR such as DSA positivity, moderate microcirculation inflammation, and transplant glomerulopathy, in addition to diagnostic ABMR and chronic/active ABMR. Moreover, a significant difference was found between the two groups in the rate of any kind of rejection. ROC analysis for any ABMR (Figure, panel B) demonstrated an AUC of 0.76 (95% CI 0.61-0.91) with a sensitivity (Sn) of 92.3%, a specificity (Sp) of 60%, a positive predictive value (PPV) of 37.5% and a negative predictive value (NPP) of 96.8%. ROC analysis for any kind of rejection (Figure, panel C) demonstrated an AUC of 0.84 (95% CI 0.74-0.94) with a Sn of 94.1%, a Sp of 65.2%, a PPV of 50% and a NPP of 96.8%. Among the patients with positive dd-cfDNA and without rejection (n=16, 51%), allograft biopsy demonstrated borderline TCMR in 4, acute tubular injury in 8, chronic pyelonephritis in 1, mild interstitial fibrosis in 1, and 2 with minimal histological abnormalities. Notably, none of the cases with a positive test were diagnosed with polyomavirus nephropathy. Conclusion Similar to previous studies, dd-cfDNA represents a sensitive test for detection of ABMR, with high performance in any rejection setting with the Banff 2013 criteria. However, the high rate of false positive results and the presence of undetected T-cell mediated events (e.g. borderline cases) at the current recommended cut-off value for positivity limits its employment as a surrogate for the renal biopsy.

SO030HISTOLOGICAL CHARACTERIZATION OF RENAL BIOPSIES FROM HCV-INFECTED DONORS: A VALUABLE SOURCE OF KIDNEY ALLOGRAFTS

Abstract Background and Aims The introduction of effective direct-acting antiviral agents (DAAs) has allowed safe transplantation of kidneys from HCV positive (HCV+) donors into HCV negative (HCV-) recipients. Some studies demonstrated an increased risk for rejection as well as polyomavirus infection in these situations (Molnar et al, Am J Transplant. 2019 Nov;19(11):3046-3057), possibly due to the development of an inflammatory milieu in the setting of HCV seroconversion and persistent viremia (Durand et al, Am J Transplant. 2019 Nov;19(11):2969-2970). With this concern for HCV-associated renal injury and increased risk for rejection, this retrospective study explores the histologic findings of allograft biopsies from HCV+ donors. Method Fifty renal allograft biopsies from 28 recipients of HCV+ donors evaluated at Vanderbilt University Medical Center between September 2018 and December 2019 were retrospectively reviewed with recording of clinical and histological features, and final diagnoses. All recipients were transplanted under a clinical protocol and were treated with DAA therapy. In the same period of time, 30 renal allograft biopsies from 24 recipients of HCV- donors were selected having the same post-transplant interval as the study cohort. Categorical variables are expressed in percentage and compared using Pearson’s chi-squared test. Continuous variables are expressed as mean±SD and compared used Student t-test. A p-value of <0.05 was considered as statistically significant. Results The complete results of the comparison between the two groups (HCV+ and HCV- donors) are demonstrated in Figure. The differences reaching statistical significance include higher frequency of males and tubulointerstitial fibrosis (IFTA) in the HCV+ group (p = 0.038 and 0.044, respectively) and the higher incidence of DSA positivity and acute tubular injury in the control group (p = 0.001 and 0.029). Notably, no significant differences were noted in terms of antibody-mediated events (microcirculation inflammation, transplant glomerulopathy, C4d positivity, or diagnostic ABMR), or T-cell mediated events including borderline or diagnostic T-cell mediated rejection (Banff 2013). The two groups also demonstrated the same incidence of polyomavirus nephropathy and de novo/recurrent glomerulonephritis. Interestingly, two of the HCV+ cases showed mesangial IgA deposits on immunofluorescence and electron microscopy on the first biopsy, of which one showed persistence of deposits, 18 and 44 days after transplant respectively. Once case demonstrated a de novo focal proliferative IgM-dominant glomerulonephritis on the 7th biopsy, 266 days after transplantation. Conclusion Kidneys from HCV+ donors represent a valuable resource in the era of DAA therapy. This reported experience demonstrates similar frequency of rejection and viral infection affecting allografts from HCV positive and negative donors. The presence of immune complex deposits and glomerulonephritis in some of these cases could represent either a donor-derived injury or an acquired post-seroconversion feature. In conclusion, HCV+ donors appear to be a safe resource for transplantation. Further studies with post-transplant intervals will provide additional characterization of their impact.

P1755EFFICACY AND SAFETY ECULIZUMAB FOR THE TREATMENT OF ANTIBODY MEDIATED REJECTION FOLLOWING RENAL TRANSPLANTATION

Abstract Background and Aims : We evaluated the efficacy and safety of eculizumab in comparison with plasmapheresis (PP) and intravenous immunoglobulin (IVIG) therapy in renal transplant recipients diagnosed with antibody-mediated rejection (AMR). Methods This was a multi-center, open-label, prospective, randomized analysis. The patients were randomized as to therapy type (eculizumab infusions or standard of care, SOC: PP/IVIG). The patients (eculizumab arm: 7 patients, SOC arm: 4 patient) were evaluated for the continuing presence of donor-specific antibodies (DSAs) and C4d (staining on biopsy), as well as histological evidence, using repeat renal biopsies after treatment. Results The allograft biopsies revealed that eculizumab did not prevent the progression to transplant glomerulopathy. Only 2 patients in the SOC arm experienced rejection reversal, and no graft losses occurred in either group. Following AMR treatment, the DSA titers generally decreased compared to titers taken at the time of AMR diagnosis. There were no serious adverse effects in the eculizumab arm. Conclusion Eculizumab alone is not sufficient to treat AMR and does not prevent acute AMR from progressing to chronic AMR or to transplant glomerulopathy. However, it should be considered as a potential alternative therapy because it may be associated with decreased DSA levels.

MO010TREATMENT STRATEGIES OF ANTIBODY MEDIATED REJECTION IN KIDNEY TRANSPLANTATION: A SYSTEMATIC REVIEW AND META-ANALYSIS

Abstract Background and Aims Antibody mediated rejection (AMR) remains accountable for the majority of death-censored graft failure following the first year of kidney transplantation. Despite significant advances in transplant immunology and immunosuppressive agents, long-term graft survival has not improved significantly. The objective of this systematic review and meta-analysis is to determine the optimal treatment strategy for AMR by investigating the effect on kidney function, proteinuria, donor specific antibody (DSA), histopathology, graft survival, adverse events and patient survival. Method MEDLINE (PubMed), Scopus, Cochrane Central Register of Controlled Trials and ClinicalTrials.gov databases were systematically searched following the PRISMA guidelines. Any kidney transplant study conducted between 1997-2018, which investigated treatment strategies for biopsy-proven AMR, and reported at least one of the following outcomes; serum creatinine, glomerular filtration rate (GFR), proteinuria, DSA, histopathology scores, graft survival, adverse events and/or patient survival were eligible for inclusion. Risk of bias was evaluated using the Cochrane Risk of Bias Tool for randomised controlled trials (RCTs) and the ROBINS-I tool for non-randomised controlled studies. Results Our analysis identified a total of 27 studies consisting of 6 RCTs and 21 non-randomised controlled studies. Together these studies included 1,237 transplant recipients; 748 patients with acute AMR (AAMR) and 489 with chronic AMR (CAMR). Meta-analysis identified significantly better 1-year graft survival in patients with AAMR when treated with Rituximab in addition to plasmapheresis and intravenous immunoglobulin (IVIG) compared to plasmapheresis and IVIG alone [risk ratio (RR): 0.48, 95% confidence interval (CI): 0.27-0.86, Z=2.46, P=0.01, I2=0%] (Fig-1A). Pooled analysis of GFR in the AAMR group was not possible due to insufficient data. There was no significant difference in the GFR at 6-12 months after treatment of CAMR with IVIG plus Rituximab compared to no treatment [mean difference: 0.36, 95% CI: -11.80-12.52, Z=0.06, P=0.95, I2=89%] (Fig-1B). Similarly, there was no significant difference in the 1-year graft survival after treatment of CAMR with IVIG plus Rituximab compared to no treatment [RR: 0.77, 95% CI: 0.42-1.40, Z=0.86, P=0.39, I2=9%] (Fig-1C). Late diagnosis of AMR and established transplant glomerulopathy seem associated with graft dysfunction and poor prognosis. Additionally, declining GFR and proteinuria seem to impact considerably on the overall outcome of the graft. Pooled analysis of proteinuria, DSA titres, and histopathology scores was not possible due to insufficient data. Similarly, pooled analysis of adverse events was not possible; however, these therapeutic strategies were generally well tolerated and associated with excellent patient survival throughout the included studies. Novel therapeutic approaches seem promising, but currently there is insufficient evidence for their routine use in AMR. The risk of bias ranged between low-risk to high-risk throughout the included RCTs and between moderate-risk to critical-risk amongst the non-randomised controlled studies. Conclusion This systematic review and meta-analysis outlines the treatment of AMR in kidney transplantation using the current best available evidence. We identified low-quality evidence in favour of treatment with combined plasmapheresis, IVIG and Rituximab in AAMR. Treatment of established CAMR does not seem advantageous in terms of graft function and survival. Additionally, the treatment of AMR is particularly heterogeneous between transplant centres, reflecting the lack of good quality evidence to guide practice. RCTs conducted via multicentre collaboration are urgently required to establish the optimal therapeutic strategies and validate models for predicting therapeutic response in AMR.

Association between transplant glomerulopathy and graft outcomes following kidney transplantation: A meta-analysis.

Transplant glomerulopathy (TG), a morphological lesion associated with confluent mechanisms of endothelial injury of renal allografts, may provide a viable predictor of graft failure. This systematic literature review and meta-analysis were performed according to the PRISMA statement to examine evidence describing the association between TG and graft loss or failure and time to these events. The literature review was conducted using the Scopus, EBSCO, and Cochrane Library search engines. Hazard ratios, median survival times, and 95% confidence intervals (CIs) were estimated to evaluate graft survival in the total population and prespecified subgroups. Meta-regression analysis assessed heterogeneity. Twenty-one publications comprising 6,783 patients were eligible for data extraction and inclusion in the meta-analysis. Studies were highly heterogeneous (I2 = 67.3%). The combined hazard ratio of graft loss or failure from random-effects meta-analysis was 3.11 (95% CI 2.44–3.96) in patients with TG compared with those without. Median graft survival in patients with TG was 3.25 (95% CI 0.94–11.21) years—15 years shorter than in those without TG (18.82 [95% CI 10.03–35.32] years). The effect of time from transplantation to biopsy on graft outcomes did not reach statistical significance (p = 0.116). TG was associated with a threefold increase in the risk of graft loss or failure and a 15-year loss in graft survival, indicating viability as a surrogate measure for both clinical practice and studies designed to prevent or reverse antibody-mediated rejection.

Validation of Prognostic Index for Allograft Outcome in Kidney Transplant Recipients With Transplant Glomerulopathy

Validation of Prognostic Index for Allograft Outcome in Kidney Transplant Recipients With Transplant Glomerulopathy

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

BackgroundRecurrent glomerulopathy (GP) after kidney transplantation is a complication of kidney transplantation that could negatively affect kidney function and graft survival. This study aimed to evaluate the outcome, graft survival, and GP recurrence and its predictive factors in kidney-transplanted patients. MethodsPatients were divided into 2 groups: G1 (with GP; n = 95) and G2 (with other causes of end-stage renal disease; n = 373). Graft survival analyses were performed using the Kaplan-Meier for living donor (LD) and deceased donor (DD). Cox proportional hazards regression were used to investigate the predictors for graft loss and for GP recurrence. ResultsDisease recurrence was observed in 9 patients who received a kidney from an LD, of which 4 lost their grafts. In patients who received a kidney from a DD, recurrence was also observed in 9 patients, of which 3 lost their grafts. No statistically significant differences in graft survival between G1 and G2 in relation to LD and DD were noted (P = .299 and .434, respectively). However, differences in graft survival were found when GP subtypes and GP recurrence were analyzed. The predictors of graft loss were delayed graft function (hazard ratio [HR] = 2.226, P = .002), rejection episodes (HR = 1.904, P = .017), and recurrence or transplant GP (HR = 3.243, P = .006). The predictors of disease recurrence or transplant GP were age (HR = 0.945, P = .028) and cold ischemia time (HR = 1.117, P = .003). ConclusionKidney transplantation could be a reasonable treatment for GP with end-stage renal disease. Despite the disease recurrence, which is a significant cause of graft loss in transplant recipients, graft survival remains satisfactory.

Plasma Cell-Rich Acute Rejection in Renal Transplantation: A Case Report

Plasma cell-rich acute rejection (PCAR) is a rare type of allograft rejection in renal transplantation. It is characterized by the presence of mature plasma cells that compromise more than 10% of inflammatory cells infiltrating the renal graft. The pathogenesis of PCAR is unknown, appears late, and has been related mainly to insufficient immunosuppression or infections. The treatment is not clearly defined, and the graft survival is poor.Here, we report a case series of 3 Spanish patients diagnosed with PCAR accompanied by donor-specific antibodies (DSA) after kidney transplantation. Mean to diagnosis was 2-12 years post-transplantation, and they began with abrupt deterioration of renal function. All patients were women and had preceding viral infection. In addition, two of the three patients recognize a doubtful adherence to immunosuppression.About treatment, 2 of the 3 patients, because the biopsy of the renal graft showed signs suggestive of incipient antibody-mediated rejection (ABMR) (glomerulitis, capilaritis, transplant glomerulopathy), were started with corticosteroids, anti-thymoglobulin, plasmapheresis, and intravenous immunoglobulins. The last patient, who only showed PCAR at biopsy, was treated with corticosteroids and anti-thymoglobulin.After treatment, graft function improved in all of them, but one patient developed an ABMR and another required a dialysis program, all of which indicates the difficulty in management and treatment of PCAR.

Response to treatment in kidney transplant recipients with acute antibody-mediated rejection: A follow-up biopsy study .

The aim of this study is to evaluate the efficacy of a treatment protocol for the management of acute antibody-mediated rejection (AAMR) and mixed-type rejection (MTR), both histopathologically and clinically. Of the 362 cases undergoing kidney transplantation from January 2010 to January 2018, patients with AAMR or MTR in the first 3 months after transplantation were included. All patients had follow-up biopsy (Bx) after treatment. 33 (9.1%) patients had diagnosis of AMR. Mean follow-up was 35 ± 20 months. 28.5% of patients had poor clinical progression at the last follow-up. Of the 25 patients with functional grafts, the mean serum creatinine was 1.6 ± 0.6 mg/dL for live and 2.1 ± 1.0 mg/dL for deceased transplant recipients. In diagnostic biopsies, there were 61% MTR. In follow-up Bx, after treatment, both C4d positivity and the severity of rejection had decreased while the mean chronic allograft damage index (CADI) score and transplant glomerulopathy showed an increase. With effective antibody mediated rejection (AMR) therapy, renal function parameters were significantly improved. Histologically, improvement in tubulointerstitial inflammation may be responsible for this process. However, progressive chronic changes, particularly in the glomeruli, are noteworthy.

Discrepancy analysis comparing molecular and histology diagnoses in kidney transplant biopsies.

Discrepancy analysis comparing two diagnostic platforms offers potential insights into both without assuming either is always correct. Having optimized the Molecular Microscope Diagnostic System (MMDx) in renal transplant biopsies, we studied discrepancies within MMDx (reports and sign-out comments) and between MMDx and histology. Interpathologist discrepancies have been documented previously and were not assessed. Discrepancy cases were classified as "clear" (eg, antibody-mediated rejection [ABMR] vs T cell-mediated rejection [TCMR]), "boundary" (eg, ABMR vs possible ABMR), or "mixed" (eg, Mixed vs ABMR). MMDx report scores showed 99% correlations; sign-out interpretations showed 7% variation between observers, all located around boundaries. Histology disagreed with MMDx in 37% of biopsies, including 315 clear discrepancies, all with implications for therapy. Discrepancies were distributed widely in all histology diagnoses but increased in some scenarios; for example, histology TCMR contained 14% MMDx ABMR and 20% MMDx no rejection. MMDx usually gave unambiguous diagnoses in cases with ambiguous histology, for example, borderline and transplant glomerulopathy. Histology lesions or features associated with more frequent discrepancies (eg, tubulitis, arteritis, and polyomavirus nephropathy) were not associated with increased MMDx uncertainty, indicating that MMDx can clarify biopsies with histologic ambiguity. The patterns of histology-MMDx discrepancies highlight specific histology diagnoses in which MMDx assessment should be considered for guiding therapy.

An in vitro model of antibody-mediated injury to glomerular endothelial cells: Upregulation of MHC class II and adhesion molecules

Chronic active antibody-mediated rejection is a major cause of allograft failure in kidney transplantation. Microvascular inflammation and transplant glomerulopathy are defining pathologic features of chronic active antibody-mediated rejection and are associated with allograft failure. However, the mechanisms of leukocyte infiltration and glomerular endothelial cell injury remain unclear. We hypothesized MHC class II ligation on glomerular endothelial cells (GEnC) would result in upregulation of adhesion molecules and production of chemoattractants. A model of endothelial cell activation in the presence of antibodies to MHC classes I and II was used to determine the expression of adhesion molecules and chemokines. Murine GEnC were activated with IFNγ, which upregulated gene expression of β2-microglobulin (MHC class I), ICAM1, VCAM1, CCL2, CCL5, and IL-6. IFNγ stimulation of GEnC increased surface expression of MHC class I, MHC class II, ICAM1, and VCAM1. Incubation with antibodies directed at MHC class I or class II did not further enhance adhesion molecule expression. Multispectral imaging flow cytometry and confocal microscopy demonstrated MHC molecules co-localized with the adhesion molecules ICAM1 and VCAM1 on the GEnC surface. GEnC secretion of chemoattractants, CCL2 and CCL5, was increased by IFNγ stimulation. CCL2 production was further enhanced by incubation with sensitized plasma. Endothelial activation induces de novo expression of MHC class II molecules and increases surface expression of MHC class I, ICAM1 and VCAM1, which are all co-localized together. Maintaining the integrity and functionality of the glomerular endothelium is necessary to ensure survival of the allograft. IFNγ stimulation of GEnC propagates an inflammatory response with production of chemokines and co-localization of MHC and adhesion molecules on the GEnC surface, contributing to endothelial cell function as antigen presenting cells and an active player in allograft injury.

Epitopes as characterized by antibody-verified eplet mismatches determine risk of kidney transplant loss

To optimize strategies that mitigate the risk of graft loss associated with HLA incompatibility, we evaluated whether sequence defined HLA targets (eplets) that result in donor-specific antibodies are associated with transplant outcomes. To define this, we fit multivariable Cox proportional hazard models in a cohort of 118 382 United States first kidney transplant recipients to assess risk of death-censored graft failure by increments of ten antibody-verified eplet mismatches. To verify robustness of our findings, we conducted sensitivity analysis in this United States cohort and assessed the role of antibody-verified eplet mismatches as autonomous predictors of transplant glomerulopathy in an independent Canadian cohort. Antibody-verified eplet mismatches were found to be independent predictors of death-censored graft failure with hazard ratios of 1.231 [95% confidence interval 1.195, 1. 268], 1.268 [1.231, 1.305] and 1.411 [1.331, 1.495] for Class I (HLA-A, B, and C), -DRB1 and -DQB1 loci, respectively. To address linkage disequilibrium between HLA-DRB1 and -DQB1, we fit models in a subcohort without HLA-DQB1 eplet mismatches and found hazard ratios for death-censored graft failure of 1.384 [1.293, 1.480] for each additional antibody-verified HLA-DRB1 eplet mismatch. In a subcohort without HLA-DRB1 mismatches, the hazard ratio was 1.384 [1.072, 1.791] for each additional HLA-DQB1 mismatch. In the Canadian cohort, antibody-verified eplet mismatches were independent predictors of transplant glomerulopathy with hazard ratios of 5.511 [1.442, 21.080] for HLA-DRB1 and 3.640 [1.574, 8.416] for -DRB1/3/4/5. Thus, donor-recipient matching for specific HLA eplets appears to be a feasible and clinically justifiable strategy to mitigate risk of graft loss.

Histopathological characteristics and causes of kidney graft failure in the current era of immunosuppression.

BACKGROUNDThe histopathological findings on the failing kidney allograft in the modern era is not well studied. In this study, we present our experience working with kidney transplant recipients with graft failure within one year of the biopsy.AIMTo report the histopathological characteristics of failed kidney allografts in the current era of immunosuppression based on the time after transplant, cause of the end-stage renal disease and induction immunosuppressive medications.METHODSIn a single-center observational study, we characterized the histopathological findings of allograft biopsies in kidney transplant recipients with graft failure within one year after the biopsy.RESULTSWe identified 329 patients with graft failure that met the selection criteria between January 1, 2006 and December 31, 2016. The three most common biopsy findings were interstitial fibrosis and tubular atrophy (IFTA, 53%), acute rejection (AR, 43%) and transplant glomerulopathy (TG, 33%). Similarly, the three most common causes of graft failure based on the primary diagnosis were AR (40%), TG (17%), and IFTA (13%). Most grafts failed within two years of post-transplant (36%). Subsequently, approximately 10%-15% of grafts failed every two years: > 2-4 years (16%), > 4-6 years (13%), > 6-8 years (11%), > 8-10 years (9%) and > 10 years (16%). AR was the most common cause of graft failure in the first six years (48%), whereas TG was the most prevalent cause of graft failure after 6 years (32%) of transplant.CONCLUSIONIn the current era of immunosuppression, AR is still the most common cause of early graft failure, while TG is the most prevalent cause of late graft failure.

Combination of Glomerular C4d and Morphologic Glomerular Lesions as a Possible Indicator in the Diagnosis of Acute or Chronic Active Antibody-Mediated Rejection

BackgroundLinear C4d staining in the peritubular capillaries is considered a sensitive and useful marker of active or chronic active antibody-mediated rejection (ABMR) in transplanted kidneys. However, the diagnostic significance of glomerular C4d deposits (gC4d) is still undetermined. The aim of this study is to evaluate the association of gC4d with clinicopathologic features and to assess its diagnostic value. MethodsFrom 2013 to 2018, a total of 158 cases of allograft kidney biopsy specimens were obtained from the Korea University Anam Hospital. The histologic features were evaluated according to the Banff classification. The gC4d were determined through immunohistochemical analyses and classified based on scores of 0 to 3 according to the extent of gC4d. ResultsA total of 73 cases (46.2%) showed gC4d, and 37 cases (23.4%), 23 cases (14.6%), and 13 cases (8.2%) were classified with a score of 1+, 2+, and 3+, respectively. The gC4d showed a significant correlation with antibody-associated histologic lesions, including peritubular capillaritis, glomerulitis, and transplant glomerulopathy (P < .001). However, gC4d showed no significant association with cell-mediated injuries such as tubulitis, interstitial inflammation, acute tubular necrosis, and thrombotic microangiopathy. Although positive gC4d alone was associated with nonspecific findings without ABMR, most cases of gC4d combined with glomerulitis or transplant glomerulopathy showed typical histologic features of ABMR, clinically with higher antibody titers and severe functional deterioration. ConclusionsGlomerular C4d deposits may be an alternate useful marker in the diagnosis of active or chronic active ABMR when combined with histologic features of glomerular lesions.

Development and validation of a peripheral blood mRNA assay for the assessment of antibody-mediated kidney allograft rejection: A multicentre, prospective study

BackgroundAntibody-mediated rejection, a leading cause of renal allograft graft failure, is diagnosed by histological assessment of invasive allograft biopsies. Accurate non-invasive biomarkers are not available. MethodsIn the multicentre, prospective BIOMARGIN study, blood samples were prospectively collected at time of renal allograft biopsies between June 2011 and August 2016 and analyzed in three phases. The discovery and derivation phases of the study (N = 117 and N = 183 respectively) followed a case-control design and included whole genome transcriptomics and targeted mRNA expression analysis to construct and lock a multigene model. The primary end point was the diagnostic accuracy of the locked multigene assay for antibody-mediated rejection in a third validation cohort of serially collected blood samples (N = 387). This trial is registered with ClinicalTrials.gov, number NCT02832661. FindingsWe identified and locked an 8-gene assay (CXCL10, FCGR1A, FCGR1B, GBP1, GBP4, IL15, KLRC1, TIMP1) in blood samples from the discovery and derivation phases for discrimination between cases with (N = 49) and without (N = 134) antibody-mediated rejection. In the validation cohort, this 8-gene assay discriminated between cases with (N = 41) and without antibody-mediated rejection (N = 346) with good diagnostic accuracy (ROC AUC 79·9%; 95% CI 72·6 to 87·2, p < 0·0001). The diagnostic accuracy of the 8-gene assay was retained both at time of stable graft function and of graft dysfunction, within the first year and also later after transplantation. The 8-gene assay is correlated with microvascular inflammation and transplant glomerulopathy, but not with the histological lesions of T-cell mediated rejection. InterpretationWe identified and validated a novel 8-gene expression assay that can be used for non-invasive diagnosis of antibody-mediated rejection. FundingThe Seventh Framework Programme (FP7) of the European Commission.

P114 Diffuse peritubular capillaritis in low-grade microvascular inflammation is associated with transplant glomerulopathy and graft loss

P114 Diffuse peritubular capillaritis in low-grade microvascular inflammation is associated with transplant glomerulopathy and graft loss

MON-164 CLINICAL AND PATHOLOGICAL ANALYSES IN CASES OF TRANSPLANT GLOMERULOPATHY AFTER KIDNEY TRANSPLANTATION IN MONGOLIA

Transplant glomerulopathy (TG) is included as one of the criteria of chronic active antibody-mediated rejection (c-AMR) in Banff 09 classification. TG is a morphologic lesion of renal allografts that is characterized histologically by duplication and/or multilayering of the glomerular basement membrane (GBM). TG is well documented to be associated with the presence of donor-specific antibodies (DSAs), most notably against HLA class II antigens, and in the majority of cases is felt to represent a morphologic manifestation of chronic antibody-mediated rejection (ABMR). The First Central Hospital of Mongolia is the only hospital that perform Kidney transplantation (KT) in Mongolia. We perform 20 KT per year and currently we performed total of 164 KT in end stage kidney disease patients in our hospital. In addition, we follow-up nearly 400 kidney transplanted patients in our clinic (including patients had transplantation in overseas). In this report, we discuss the clinical and pathological analyses of cases of TG after renal transplantation. TG was diagnosed in 10 renal allograft biopsy specimens (BS) obtained from transplant patients who was under follow up at our clinic between 2017 and 2018. We checked DSA and stained the specimens with H&E, masson's trichrome, PAS, silver staining and used Banff 09 classification. Immunofluorescence and C4d stainings were also done. Among the 10 patients,20% had a history of acute rejection (AR); of these,10% had acute antibody-mediated rejection (a-AMR).Among the 86 BS of TG,the TG was mild in 35 cases (cg1),moderate in 28 cases (cg2) and severe in 23 cases (cg3).Peritubular capillaritis was present in 74 bs (86%), transplant glomerulitis in 65 (76%),interstitial fibrosis and tubular atrophy (if/ta) in 71 (83%),thickening of the peritubular capillary (ptc) basement membrane in 72 (84%), and interstitial inflammation in 40 (47%).C4d deposition in the ptc was present in 49 bs (57%); 39 of these 49 bs showed diffuse c4d deposits in the ptc (c4d3),while the remaining 10 bs showed focal deposits (c4d2).Diffuse c4d deposition in the glomerular capillaries (GC) was seen in 70 bs (81%), while focal c4d deposition in the GC was seen in 9 (11%). In the assay using plastic beads coated with HLA antigen performed in 67 serum samples obtained in the peri-biopsy period, circulating ant-HLA alloantibody was detected in 55 (82%); in 33 of the 55 (49%) samples, donor-specific antibodies (DSA) were detected. Among our study, the findings in 22 bs (26%) fully met the criteria for c-AMR in banff '09 classification, including TG, c4d deposition in the ptc and presence of DSA, while those in 27 BS were suspicious of c-AMR. Deterioration of the renal allograft function after the biopsies was seen in 31 patients (62%). We suggest that histopathological changes of transplant glomerulopathy might be accompanied by inflammation of the microvasculature, such as transplant glomerulitis and peritubular capillaritis, thickening of the peritubular capillary basement membrane, and circulating anti-HLA antibodies. C4d deposition in the ptc is not always present in biopsy specimens of TG. Anti-HLA antibody class II, particularly when the antibody was DSA class II, appeared to be associated with the development of TG. The prognosis of grafts exhibiting TG was poor even under the currently used standard triple immunosuppressive regimen.

Transplant nephrectomy; pathological features of 124 consecutive cases in a single center study over 10 years

Background: Transplant nephrectomy (TN) is not commonly performed but it may be essential for several indications. Objectives: This study details an in-depth evaluation of the histological changes present in TN specimens. Patients and Methods: We identified 124 consecutive TN cases between 2004 and 2014. The indication for TN was divided into four groups: acute graft loss without significant blood flow (AGL group- 47 cases); suspected ongoing rejection or graft intolerance syndrome (Rej/GIS group44 cases); infection (INF group- 24 cases); and miscellaneous reasons (MIS group- 9 cases). We examined the histological changes, including the main renal artery (MRA), intrarenal arteries, the renal vein and the ureter. Results: In AGL group, most cases showed no tubulointerstitial inflammation, interstitial fibrosis and tubular atrophy, but 74.5% had necrosis. All cases in Rej/GIS group showed severe interstitial fibrosis and tubular atrophy, since 40.9% showed severe tubulointerstitial inflammation. Glomerulitis was observed in 52.3% and transplant glomerulopathy (TG) was detected in 75.0%. Arteritis of intrarenal arteries and the MRA were detected in 70.5% and 59.1%. In INF group, 66.7% had tubulitis and 79.2% had interstitial inflammation with lymphocytes, and severe interstitial fibrosis while, tubular atrophy were detected in 66.7%. TG was detected in 62.5%. In MIS group, the histological changes were minor. Conclusions: This study provides a detailed description of the morphological characteristics associated with various indications for TN. TN will occasionally reveal unexpected and significant findings that may require specific forms of treatment to manage the patient appropriately.

Association of c4d deposition in renal allograft biopsy with morphologic features in Banff diagnosis

Association of c4d deposition in renal allograft biopsy with morphologic features in Banff diagnosis - IJPO- Print ISSN No: - 2394-6784 Online ISSN No:- 2394-6792 Article DOI No:- 10.18231/j.ijpo.2019.033, Indian Journal of Pathology and Oncology-Indian J Pathol Oncol