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Background: Antibody‐mediated rejection (AMR) often leads to chronic kidney allograft damage and is a critical cause of allograft failure. The Banff classification, used to diagnose AMR, has become complex and challenging for clinicians. A Banff‐based histologic chronicity index (CI) was recently proposed as a simplified prognostic indicator. Its reliability and reproducibility have not been externally validated. Methods: This study investigated 71 kidney allograft biopsies diagnosed with AMR. Interobserver reproducibility of the recently proposed CI and its components (cg, cv, ct, and ci) were assessed. The association between CI and allograft failure was analyzed, and CI cut‐off values were evaluated by Cox proportional hazards regression and Kaplan–Meier estimator with log‐rank test. Results: The study confirmed the association of CI with allograft failure, but also revealed that the assessment of CI varied between pathologists, impacting its reproducibility as a prognostic tool. Only 49 (69.0%) of the biopsies showed complete agreement on the proposed cut‐off value of CI < 4 or CI ≥ 4. Furthermore, this cut‐off did not reliably stratify allograft failure. Notably, the cg score, which carries significant weight in the CI calculation, had the lowest agreement between observers (kappa =.281). Conclusions: While a simplified prognostic indicator for AMR is needed, this study highlights the limitations of CI, particularly its poor interobserver reproducibility. Our findings suggest that clinicians should interpret CI cautiously and consider establishing their own cut‐off values. This study underscores the need to address interobserver reproducibility before CI can be widely adopted for AMR management. [ABSTRACT FROM AUTHOR]

Prolonged survival in preclinical renal xenotransplantation demonstrates that early antibody mediated rejection (AMR) can be overcome. It is now critical to evaluate and understand the pathobiology of late graft failure and devise new means to improve post xenograft outcomes. In renal allotransplantation the most common cause of late renal graft failure is transplant glomerulopathy—largely due to anti‐donor MHC antibodies, particularly anti‐HLA DQ antibodies. We evaluated the pig renal xenograft pathology of four long‐surviving (>300 days) rhesus monkeys. We also evaluated the terminal serum for the presence of anti‐SLA class I and specifically anti‐SLA DQ antibodies. All four recipients had transplant glomerulopathy and expressed anti‐SLA DQ antibodies. In one recipient tested for anti‐SLA I antibodies, the recipient had antibodies specifically reacting with two of three SLA I alleles tested. These results suggest that similar to allotransplantation, anti‐MHC antibodies, particularly anti‐SLA DQ, may be a barrier to improved long‐term xenograft outcomes. [ABSTRACT FROM AUTHOR]

Chronic antibody‐mediated rejection of kidney transplantation is a major cause of late‐stage graft loss. Donor‐specific antibodies are the main cause of antibody‐mediated rejection; in particular, de novo donor‐specific antibodies are a risk factor for chronic active antibody‐mediated rejection. The level of de novo donor‐specific antibodies tends to increase with time throughout long‐term graft survival. Donor‐specific antibodies induce humoral rejection through complement activation, which results in tissue injury and coagulation. Additionally, complement activation promotes the migration of inflammatory cells through the innate immune response, causing endothelial injury. This inflammatory response may cause persistent glomerulitis and peritubular capillaritis, leading to fixed pathological lesions that impair graft function. No treatment has been established for chronic antibody‐mediated rejection, a condition in which antibody‐mediated rejection becomes irreversible. Thus, antibody‐mediated rejection must be detected and treated while it is still reversible. In this review, we discuss the development of de novo donor‐specific antibodies and the mechanisms leading to chronic antibody‐mediated rejection and summarize the current treatment options and the latest biomarkers for detecting chronic antibody‐mediated rejection at an earlier stage. [ABSTRACT FROM AUTHOR]

BackgroundTransplant glomerulopathy (TG) may indicate different disease entities including chronic AMR (antibody-mediated rejection). However, AMR criteria have been frequently changed, and long-term outcomes of allografts with AMR and TG according to Banff 2017 have rarely been investigated.Methods282 kidney allograft recipients with biopsy-proven TG were retrospectively investigated and diagnosed according to Banff'17 criteria: chronic AMR (cAMR, n = 72), chronic active AMR (cAAMR, n = 76) and isolated TG (iTG, n = 134). Of which 25/72 (34.7%) patients of cAMR group and 46/76 (60.5%) of cAAMR group were treated with antihumoral therapy (AHT).ResultsUp to 5 years after indication biopsy, no statistically significant differences were detected among iTG, cAMR and cAAMR groups in annual eGFR decline (−3.0 vs. −2.0 vs. −2.8 ml/min/1.73 m2 per year), 5-year median eGFR (21.5 vs. 16.0 vs. 20.0 ml/min/1.73 m2), 5-year graft survival rates (34.1 vs. 40.6 vs. 31.8%) as well as urinary protein excretion during follow-up. In addition, cAMR and cAAMR patients treated with AHT had similar graft and patient survival rates in comparison with those free of AHT, and similar comparing with iTG group. The TG scores were not associated with 5-year postbiopsy graft failure; whereas the patients with higher scores of chronic allograft scarring (by mm-, ci- and ct-lesions) had significantly lower graft survival rates than those with mild scores. The logistic-regression analysis demonstrated that Banff mm-, ah-, t-, ci-, ct-lesions and the eGFR level at biopsy were associated with 5-year graft failure.ConclusionsThe occurrence of TG is closely associated with graft failure independent of disease categories and TG score, and the long-term clinical outcomes were not influenced by AHT. The Banff lesions indicating progressive scarring might be better suited to predict an unfavorable outcome.

Antibody-mediated rejection (ABMR) is the leading cause of allograft failure in kidney transplantation. Its histological hallmark is represented by lesions of glomerulitis i.e., inflammatory cells within glomeruli. Current therapies for ABMR fail to prevent chronic allograft damage i.e., transplant glomerulopathy, leading to allograft loss. We used laser microdissection of glomeruli from formalin-fixed allograft biopsies combined with mass spectrometry-based proteomics to describe the proteome modification of 11 active and 10 chronic active ABMR cases compared to 8 stable graft controls. Of 1335 detected proteins, 77 were deregulated in glomerulitis compared to stable grafts, particularly involved in cellular stress mediated by interferons type I and II, leukocyte activation and microcirculation remodeling. Three proteins extracted from this protein profile, TYMP, WARS1 and GBP1, showed a consistent overexpression by immunohistochemistry in glomerular endothelial cells that may represent relevant markers of endothelial stress during active ABMR. In transplant glomerulopathy, 137 proteins were deregulated, which favor a complement-mediated mechanism, wound healing processes through coagulation activation and ultimately a remodeling of the glomerular extracellular matrix, as observed by light microscopy. This study brings novel information on glomerular proteomics of ABMR in kidney transplantation, and highlights potential targets of diagnostic and therapeutic interest. [ABSTRACT FROM AUTHOR]

Background: Many kidney allografts fail due to the occurrence of antibody-mediated rejection (ABMR), related to donor-specific anti-HLA antibodies (HLA-DSA). However, the histology of ABMR can also be observed in patients without HLA-DSA. While some non-HLA antibodies have been related to the histology of ABMR, it is not well known to what extent they contribute to kidney allograft injury. Here we aimed to investigate the role of 82 different non-HLA antibodies in the occurrence of histology of ABMR after kidney transplantation. Methods: We included all patients who underwent kidney transplantation between 2004-2013 in a single center and had biobanked serum. Pre- and post-transplant sera (n=2870) were retrospectively tested for the presence of 82 different non-HLA antibodies using a prototype bead assay on Luminex (Immucor, Inc). A ratio was calculated between the measured MFI value and the cut-off MFI defined by the vendor for each non-HLA target. Results: 874 patients had available pretransplant sera and were included in this analysis. Of them, 133 (15.2%) received a repeat kidney allograft, and 100 (11.4%) had pretransplant HLA-DSA. In total, 204 (23.3%) patients developed histology of ABMR after kidney transplantation. In 79 patients (38.7%) the histology of ABMR was explained by pretransplant or de novo HLA-DSA. The multivariable Cox analysis revealed that only the broadly non-HLA sensitized (number of positive non-HLA antibodies) patients and those with the highest total strength of the non-HLA antibodies (total ratios of the positive non-HLA antibodies) were independently associated with increased rates of histology of ABMR after transplantation. Additionally, independent associations were found for antibodies against TUBB (HR=2.40; 95% CI 1.37 – 4.21, p=0.002), Collagen III (HR=1.67; 95% CI 1.08 – 2.58, p=0.02), VCL (HR=2.04; 95% CI 1.12 – 3.71, p=0.02) and STAT6 (HR=1.47; 95% CI 1.01 – 2.15, p=0.04). The overall posttransplant non-HLA autoreactivity was not associated with increased rates of ABMRh. Conclusions: This study shows that patients highly and broadly sensitized against non-HLA targets are associated with an increased risk of ABMR histology after kidney transplantations in the absence of HLA-DSA. Also, some pretransplant non‐HLA autoantibodies are individually associated with increased rates of ABMR histology. However, whether these associations are clinically relevant and represent causality, warrants further studies. [ABSTRACT FROM AUTHOR]

Introduction: Transplant glomerulopathy (TG) is a morphological lesion resulting from chronic glomerular endothelium injury, and it is strongly associated with poor graft survival. TG coexisting with focal segmental glomerulosclerosis (FSGS) can be found in renal allograft biopsies, but few related studies are available.Methods: Consecutive kidney transplant recipients with biopsy-proven TG were studied retrospectively. Patients concomitant with FSGS were identified and compared with those without FSGS. The influence of FSGS on allograft outcomes was assessed using univariate and multivariate Cox regression models.Results: Of the 66 patients with TG, 40 (60.6%) had concomitant FSGS. TG patients with FSGS had higher proteinuria (median, 2.6 vs. 0.8 g/24 h, p < 0.001) and serum creatinine levels (median, 2.5 vs. 2.1 mg/dL, p = 0.04), lower serum albumin levels, higher chronic glomerulopathy (cg) score, larger glomerular tuft area, lower number of podocytes, and higher incidences of podocyte hyperplasia, pseudotubule formation, and diffuse foot process effacement than those without FSGS (all p < 0.05). The kidney allograft loss rate of patients with FSGS was higher than that of patients without FSGS (65.7% vs. 37.5%, p = 0.03). The presence of FSGS was independently associated with allograft loss in TG (hazard ratio (HR) = 3.42, 95% confidence interval (CI): 1.30-8.98, p = 0.01). Other independent predictors were proteinuria (HR = 1.18, 95% CI: 1.02-1.37, p = 0.02), estimated glomerular filtration rate (HR = 0.94, 95% CI: 0.91-0.97, p < 0.001), and panel reactive antibody (HR = 3.99, 95% CI: 1.14-13.99, p = 0.03). Moreover, FSGS (odds ratio (OR) = 4.39, 95% CI: 1.29-14.92, p = 0.02) and cg (OR = 5.36, 95% CI: 1.56-18.40, p = 0.01) were independent risk factors for proteinuria.Conclusion: In this cohort of patients with TG, the presence of FSGS was strongly associated with more severe clinicopathological features and worse allograft survival. [ABSTRACT FROM AUTHOR]

With the development of organ transplantation in clinical practice, allograft pathology has been constantly developing and advancing. The convening of Banff conference on allograft pathology and the establishment of Banff classification on allograft pathology (Banff classification) are pivotal milestones in the development of international allograft pathology. Since then, Banff classification on pathological diagnosis of various transplant organs have been continually updated and improved. Ultrastructural pathological observation by electron microscope plays an irreplaceable role in the early diagnosis of antibody-mediated rejection, recurrent disease and de novo disease of renal allograft. Early detection and rational treatment help to maintain the long-term survival of renal allograft and reduce the failure of renal allograft. In this article, the basic definition of electron microscope and the ultrastructural pathological diagnosis, the research history and main progress on electron microscope diagnosis on Banff classification for renal allograft pathology were introduced, and typical pathological changes, specific terminology and diagnostic criteria of electron microscope diagnosis on renal allograft biopsy were summarized, aiming to provide reference for clinical and basic research of organ transplantation. [ABSTRACT FROM AUTHOR]

Introduction: Chronic antibody-mediated rejection (CAMR) has now emerged as one of the most common causes of chronic graft failure. In this study, we tried to study the clinical details, morphological features, risk factors, and outcome of biopsy-proven CAMR. Materials and Methods: This was a retrospective study including 14 patients' with biopsy-proven CAMR. The clinical details, posttransplantation duration, risk factors, histomorphological features, immunohistochemical features, treatment protocol, and graft outcome of all the patients were studied. Results: There were 11 male and 3 female patients and the mean age at biopsy was 33 ± 10 years. The mean transplant duration to the diagnosis of CAMR was 61 months. The mean serum creatinine levels and 24-h proteinuria at the time of biopsy were 5.3 ± 4.5 mg/dl and 3.4 ± 0.9 g/24 h, respectively. Four patients had a previous episode of rejection and three patients had a concurrent hepatitis C virus (HCV) infection. Transplant glomerulopathy (TG) was seen in all 14 biopsies and all were positive for C4D in the peritubular capillaries. Twelve of these progressed to graft failure. Conclusion: CAMR is an important cause of chronic graft rejection, with a majority of cases progressing to graft failure. TG is the most commonly observed histomorphological pattern and the severity of TG seems to be associated with poor graft survival. An associated HCV infection further hinders the graft survival.

There have been recent significant advances in short‐term outcomes in renal transplantation, however, long‐term allograft survival remains a challenge. With reported incidences as high of 74.5% of chronic graft loss in patients with biopsies showing transplant glomerulopathy (TG), this syndrome represents an important factor for chronic allograft complications. In this review we show an overview of the novel mechanistic insights into pathogenesis of TG, as well as a brief description of the pathology, diagnosis and newer prognostic indices within TG diagnosis. These data raise intriguing roles for cell‐mediated immunity and podocyte stress in TG as well as reinforce previous associations of TG with ABMR. We also delve into management strategies for TG and report the paucity of existing clinical trial data for this prevalent condition in renal transplants. [ABSTRACT FROM AUTHOR]

Summary: Proteinuria and transplant glomerulopathy (TG) are common in kidney transplantation. To date, there is limited knowledge regarding proteinuria in different types of TG and its relationship to allograft survival. A retrospective cohort analysis of TG patients from indication biopsies was performed to investigate the relationship of proteinuria, histology, and graft survival. One hundred and seven (57.5%) out of 186 TG patients lost their grafts with a median survival of 14 [95% confidence interval (CI) 10–22] months after diagnosis. Proteinuria ≥1 g/24 h at the time of biopsy was detected in 87 patients (46.8%) and the median of proteinuria was 0.89 (range 0.05–6.90) g/24 h. TG patients with proteinuria ≥1 g/24 h had worse 5‐year graft survival (29.9% vs. 53.5%, P = 0.001) compared with proteinuria <1 g/24 h. Proteinuria was associated with graft loss in univariable Cox regression [hazard ratio (HR) 1.25, 95% CI, 1.11–1.41, P < 0.001], and in multivariable analysis (adjusted HR 1.26, 95% CI 1.11–1.42, P < 0.001) independent of other risk factors including creatinine at biopsy, positive C4d, history of rejection, and Banff lesion score mesangial matrix expansion. In this cohort of TG patients, proteinuria at indication biopsy is common and associated with a higher proportion of graft loss. [ABSTRACT FROM AUTHOR]

Kidney transplant (KTx) biopsies showing transplant glomerulopathy (TG) (glomerular basement membrane double contours (cg) > 0) and microvascular inflammation (MVI) in the absence of C4d staining and donor-specific antibodies (DSAs) do not fulfill the criteria for chronic active antibody-mediated rejection (CA-AMR) diagnosis and do not fit into any other Banff category. To investigate this, we initiated a multicenter intercontinental study encompassing 36 cases, comparing the immunomic and transcriptomic profiles of 14 KTx biopsies classified as cg+MVI DSA - /C4d - with 22 classified as CA-AMR DSA + /C4d + through novel transcriptomic analysis using the NanoString Banff-Human Organ Transplant (B-HOT) panel and subsequent orthogonal subset analysis using two innovative 5-marker multiplex immunofluorescent panels. Nineteen genes were differentially expressed between the two study groups. Samples diagnosed with CA-AMR DSA + /C4d + showed a higher glomerular abundance of natural killer cells and higher transcriptomic cell type scores for macrophages in an environment characterized by increased expression of complement-related genes (i.e., C5AR1) and higher activity of angiogenesis, interstitial fibrosis tubular atrophy, CA-AMR, and DSA-related pathways when compared to samples diagnosed with cg+MVI DSA - /C4d - . Samples diagnosed with cg+MVI DSA - /C4d - displayed a higher glomerular abundance and activity of T cells (CD3 + , CD3 + CD8 + , and CD3 + CD8 - ). Thus, we show that using novel multiomic techniques, KTx biopsies with cg+MVI DSA - /C4d - have a prominent T-cell presence and activity, putting forward the possibility that these represent a more T-cell dominant phenotype., (Copyright © 2023 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.)

Antibody-mediated rejection (ABMR) is the leading cause of allograft failure in kidney transplantation. Its histological hallmark is represented by lesions of glomerulitis i.e., inflammatory cells within glomeruli. Current therapies for ABMR fail to prevent chronic allograft damage i.e., transplant glomerulopathy, leading to allograft loss. We used laser microdissection of glomeruli from formalin-fixed allograft biopsies combined with mass spectrometry-based proteomics to describe the proteome modification of 11 active and 10 chronic active ABMR cases compared to 8 stable graft controls. Of 1335 detected proteins, 77 were deregulated in glomerulitis compared to stable grafts, particularly involved in cellular stress mediated by interferons type I and II, leukocyte activation and microcirculation remodeling. Three proteins extracted from this protein profile, TYMP, WARS1 and GBP1, showed a consistent overexpression by immunohistochemistry in glomerular endothelial cells that may represent relevant markers of endothelial stress during active ABMR. In transplant glomerulopathy, 137 proteins were deregulated, which favor a complement-mediated mechanism, wound healing processes through coagulation activation and ultimately a remodeling of the glomerular extracellular matrix, as observed by light microscopy. This study brings novel information on glomerular proteomics of ABMR in kidney transplantation, and highlights potential targets of diagnostic and therapeutic interest.

Background/Aims: We aimed to explore the associations between clinical parameters and long-term allograft outcomes in transplant glomerulopathy (TG) in a large retrospective cohort with long follow-up. Methods: Clinical and laboratory data at biopsy from 180 cases of TG with an estimated glomerular filtration rate (eGFR)> 15ml/min/1.73m2 from January 2004 to December 2016 at our center were retrospectively analyzed. The main outcome of this study was initiation of replacement therapy or an eGFR declined to < 15 ml/min/1.73m2. Results: During a median follow-up of 5 years (interquartile range 2.6-8.2 years), 117 cases (65.0%) achieved the combined event. Kaplan-Meier method yielded the 1-year and 5-year cumulative renal allograft survival rates after a histopathologic diagnosis of TG were 84% (95% confidence interval [CI] 81-87%) and 33% (95% CI 27–39%) respectively. In univariate analysis, allograft outcome differed significantly by eGFR, proteinuria, blood hemoglobin level, urinary retinol-binding protein (urRBP) and urinary N-acetyl-β-D-glucosaminidase (urNAG) level at the time of biopsy. Multivariate Cox analysis revealed that a higher level of eGFR was the most powerful predictor of allograft survival. Compared with those with eGFR≥60, the hazard ratio (HR) increased from 4.50 (95% CI: 1.03-19.71, p=0.0462) for patients with eGFR between 30 and 59 ml/min/1.73m2 to 9.14 (95% CI 1.97-42.45, P=0.0047) when eGFR decreased to 15 to 29 ml/min/1.73m2. Additionally, proteinuria and higher urRBP values (≥2.85mg/dl) were found to confer much worse survival rates for TG patients in multivariate Cox analysis. Male sex (HR 0.48, P=0.02) and HCV infection (HR 1.78, P=0.0499) were also found to be independent risk factors for worse allograft survival. Conclusion: Five clinical features—impaired renal function, higher proteinuria, higher urRBP level, male sex and HCV infection—are independent predictors of an unfavorable renal allograft outcome. urRBP is a simple and useful parameter that can add invaluable information for the clinical follow-up of patients with TG.

Abstract Background Chronic active antibody-mediated rejection (c-aABMR) is an important cause of allograft failure and graft loss in long-term kidney transplants. Methods To determine the efficacy and safety of combined therapy with rituximab, plasma exchange (PE) and intravenous immunoglobulins (IVIG), a cohort of patients with transplant glomerulopathy (TG) that met criteria of active cABMR, according to BANFF’17 classification, was identified. Results We identified 62 patients with active c-aABMR and TG (cg ≥ 1). Twenty-three patients were treated with the combination therapy and, 39 patients did not receive treatment and were considered the control group. There were no significant differences in the graft survival between the two groups. The number of graft losses at 12 and 24 months and the decline of eGFR were not different and independent of the treatment. A decrease of eGFR≥13 ml/min between 6 months before and c-aABMR diagnosis, was an independent risk factor for graft loss at 24 months (OR = 5; P = 0.01). Infections that required hospitalization during the first year after c-aABMR diagnosis were significantly more frequent in treated patients (OR = 4.22; P = 0.013), with a ratio infection/patient-year of 0.65 and 0.20 respectively. Conclusions Treatment with rituximab, PE, and IVIG in kidney transplants with c-aABMR did not improve graft survival and was associated with a significant increase in severe infectious complications. Trial registration Agencia Española de Medicametos y Productos Sanitarios (AEMPS): 14566/RG 24161. Study code: UTR-INM-2017-01.

Introduction: Chronic active antibody‐mediated rejection (cAMR) is a major determinant of late allograft failure. Rituximab/immunoglobulins (IVIg) + plasma exchange (PLEX) showed controversial results in cAMR treatment. Tocilizumab (TCZ), a humanized anti‐interleukin 6 receptor antibody, has been recently used as rescue therapy in patients non‐responsive to rituximab/IVIg/PLEX with favorable outcomes. Whether TCZ acts "per se" or requires a priming effect from previous treatments is currently unknown. Methods: Fifteen patients with cAMR were treated with TCZ as a first‐line therapy and followed for a median time of 20.7 months. Results: Despite the majority of patients experiencing advanced transplant glomerulopathy (TG) at diagnosis (60% with cg3), glomerular filtration rate and proteinuria stabilized during the follow‐up, with a significant reduction in donor‐specific antibodies. Protocol biopsies after 6 months demonstrated significant amelioration of microvascular inflammation and no TG, C4d deposition, or IF/TA progression. Gene‐expression and immunofluorescence analysis showed upregulation of three genes (TJP‐1, AKR1C3, and CASK) involved in podocyte, mesangial, and tubular restoration. Conclusion: Tocilizumab adopted as a first‐line approach in cAMR was associated with early serological and histological improvements and functional stabilization even in advanced TG, suggesting a role for the use of TCZ alone with the avoidance of unnecessary previous immunosuppressants. [ABSTRACT FROM AUTHOR]

Background: Transplant glomerulopathy (TG) represents a major cause of long-term allograft failure and is the leading cause of overall post-transplant proteinuria. The extent to which histopathologic features predicts prognostication is uncertain.Methods: A single-center retrospective cohort with biopsy-proven TG was investigated. Renal biopsies were scored according to Banff 2017. The primary outcome was death-censored graft failure defined as return to dialysis or estimated glomerular filtration rate (eGFR) decreased to <15 mL/min/1.73 m2. The prognostic significance of clinical and histopathologic parameters was determined using Cox proportional hazards models.Results: Data from 180 cases were available for analysis with a median follow-up of 5.0 (2.6-8.2) years. In multivariable models, ci + ct score (HR 3.1; 95% CI 2.0-4.9), cg score (HR 1.7; 95% CI 1.1-2.8), eGFR (HR 2.1; 95% CI 1.4-3.2) and proteinuria (HR 2.4; 95% CI 1.6-3.7) were independent predictors of the primary outcome. Mesangial Immunoglobulin A deposition did not significantly affect allograft survival. The only significant pathologic factors for the severity of proteinuria were cg and g + ptc (adjusted R2 = 0.46) as determined by multivariable stepwise linear regression analysis.Conclusions: Severe ci + ct and cg at biopsy were predictors of unfavorable allograft prognosis in TG patients even after taking into consideration clinical characteristics. Histologic severity of cg and g + ptc was significantly associated with clinical proteinuria. [ABSTRACT FROM AUTHOR]

Background Peritubular capillaritis (ptc), reported by the ptc score, is a major feature of kidney allograft rejection and microvascular inflammation (MVI). MVI sum scores (ptc + glomerulitis score ≥2) are accepted diagnostic surrogates of human leucocyte antigen (HLA)–antibody interaction. However, low-grade inflammation is common and ptc scores (number of leucocytes/capillary) may not mirror all aspects of ptc morphology. Recently we observed a relationship of the diffuse extent of ptc (inflammation of >50% of the renal cortex) with graft loss and significantly higher donor-specific antibody levels, suggesting potential inclusion of diffuse ptc as an additional surrogate of antibody–antigen interaction. Methods We sought to assess how a combination of ptc score and extent in low-grade inflammation (ptc1) affects transplant glomerulopathy (TG) and graft loss risk. Patients (n  = 616) were assessed for MVI in first indication biopsies. Cases with a ptc score of 1 but diffuse extent (ptc1diffuse, g-score = 0, n  = 26) were considered additional surrogates of HLA–antibody interaction and compared with MVI ≥2 and MVI <2. Results The ptc1diffuse and MVI score ≥2 subjects had worse graft survival (42% and 59%) compared with an MVI score <2 (70%) (P = 0.002). The incorporation of ptc1diffuse in the MVI score ≥2 increased the receiver operating characteristics curve for TG [area under the curve (AUC) 0.602; P = 0.008] compared with a Banff MVI score ≥2 (AUC 0.56; P = 0.12); cases with baseline TG were excluded. In multivariate analysis, ptc1diffuse remained independently related to TG (odds ratio 3.89; P = 0.008) and graft loss (hazard ratio 2.64; P = 0.001) even after inclusion of all rejection episodes. Conclusion An integrated view of ptc morphology including diffuse ptc in MVI is superior for TG and graft loss risk assessment. [ABSTRACT FROM AUTHOR]

Introduction: Chronic antibody-mediated rejection (CAMR) has now emerged as one of the most common causes of chronic graft failure. In this study, we tried to study the clinical details, morphological features, risk factors, and outcome of biopsy-proven CAMR. Materials and Methods: This was a retrospective study including 14 patients' with biopsy-proven CAMR. The clinical details, posttransplantation duration, risk factors, histomorphological features, immunohistochemical features, treatment protocol, and graft outcome of all the patients were studied. Results: There were 11 male and 3 female patients and the mean age at biopsy was 33 ± 10 years. The mean transplant duration to the diagnosis of CAMR was 61 months. The mean serum creatinine levels and 24-h proteinuria at the time of biopsy were 5.3 ± 4.5 mg/dl and 3.4 ± 0.9 g/24 h, respectively. Four patients had a previous episode of rejection and three patients had a concurrent hepatitis C virus (HCV) infection. Transplant glomerulopathy (TG) was seen in all 14 biopsies and all were positive for C4D in the peritubular capillaries. Twelve of these progressed to graft failure. Conclusion: CAMR is an important cause of chronic graft rejection, with a majority of cases progressing to graft failure. TG is the most commonly observed histomorphological pattern and the severity of TG seems to be associated with poor graft survival. An associated HCV infection further hinders the graft survival. [ABSTRACT FROM AUTHOR]

Aim: to analyze the relationship between circulating anti-HLA antibodies (class-I and class-II), renal pathology and C4d deposition in cases of late acute and chronic antibody-mediated renal allograft rejection according to the method of antibodies detection (ELISA and LUMINEX). Materials and methods. Th e study included 192 patients with indicative graft biopsies (with C4d-staining) and screening detection of anti-HLA antibodies (109 patients by ELISA, 58 patients by LUMINEX, 25 patients – both methods). Patients were divided into 3 groups based on pathology fi ndings: 85 patients with chronic graft rejection, 39 patients with acute antibodymediated rejection (AMR), 68 patients of control group had no signs of AMR. Results. Anti-HLA antibodies (predominantly class-II anti-HLA) were identifi ed in 84.7% of patients with chronic graft rejection, in 84.6% of patients with acute AMR and 33.8% of control group (р < 0.001). Close correlation between the levels of antiHLA antibodies detected by different methods was revealed for both classes of antibodies (r² class-I anti-HLA = 0.773, r² class-II anti-HLA = 0.379, р < 0.01). LUMINEX proved to be more sensitive in anti-HLA antibodies detection in all groups. It was especially signifi cant for the diagnosis of C4d-negative acute AMR whose frequencies were 22.2% and 4.8% in detection by LUMINEX and ELISA, respectively (р < 0.01). On the other hand, anti-HLA antibodies being detected by LUMINEX in 55% of patients of the control group more often required determination of donor specifi city. Conclusion. Screening of anti-HLA antibodies (by ELISA and LUMINEX) along with specifi c renal pathology and C4d deposition is suffi cient for the diagnosis of acute and chronic AMR in most cases. Being more sensitive LUMINEX method is preferable for the revealing of C4d-negative AMR, but it requires specifi c DSA detection in many cases.

Background/Aims: We aimed to explore the associations between clinical parameters and long-term allograft outcomes in transplant glomerulopathy (TG) in a large retrospective cohort with long follow-up. Methods: Clinical and laboratory data at biopsy from 180 cases of TG with an estimated glomerular filtration rate (eGFR)> 15ml/min/1.73m2 from January 2004 to December 2016 at our center were retrospectively analyzed. The main outcome of this study was initiation of replacement therapy or an eGFR declined to < 15 ml/min/1.73m2. Results: During a median follow-up of 5 years (interquartile range 2.6-8.2 years), 117 cases (65.0%) achieved the combined event. Kaplan-Meier method yielded the 1-year and 5-year cumulative renal allograft survival rates after a histopathologic diagnosis of TG were 84% (95% confidence interval [CI] 81-87%) and 33% (95% CI 27–39%) respectively. In univariate analysis, allograft outcome differed significantly by eGFR, proteinuria, blood hemoglobin level, urinary retinol-binding protein (urRBP) and urinary N-acetyl-β-D-glucosaminidase (urNAG) level at the time of biopsy. Multivariate Cox analysis revealed that a higher level of eGFR was the most powerful predictor of allograft survival. Compared with those with eGFR≥60, the hazard ratio (HR) increased from 4.50 (95% CI: 1.03-19.71, p=0.0462) for patients with eGFR between 30 and 59 ml/min/1.73m2 to 9.14 (95% CI 1.97-42.45, P=0.0047) when eGFR decreased to 15 to 29 ml/min/1.73m2. Additionally, proteinuria and higher urRBP values (≥2.85mg/dl) were found to confer much worse survival rates for TG patients in multivariate Cox analysis. Male sex (HR 0.48, P=0.02) and HCV infection (HR 1.78, P=0.0499) were also found to be independent risk factors for worse allograft survival. Conclusion: Five clinical features—impaired renal function, higher proteinuria, higher urRBP level, male sex and HCV infection—are independent predictors of an unfavorable renal allograft outcome. urRBP is a simple and useful parameter that can add invaluable information for the clinical follow-up of patients with TG. [ABSTRACT FROM AUTHOR]

Chronic-active antibody-mediated rejection (CAABMR) is associated with poor kidney graft survival and has no clear effective treatment. Forty-one cases of CAABMR were detected in indication graft biopsies and evaluated according to current Banff classification. We investigated the impact of concurrent donor-specific antibodies (DSA) and their characteristics, together with non-adherence regarding immunosuppression on CAABMR histopathological phenotypes and prognosis. Twenty-four (59%) patients had detectable DSA at biopsy, with 15 of them being considered non-adherent. Graft function at biopsy was similar in DSA (+) and (−) patients. DSA (+) patients had significantly higher tubulointerstitial inflammation (i and ti) and acute humoral (g+ptc+v+C4d) composite score than DSA (−). DSA (+)/non-adherent cases presented additionally with increased microvascular inflammation (ptc and v), besides having a distinctively lower ah score. C1q DSA strength was higher ( P  = .046) in non-adherent patients and correlated closely with C4d score ( P  = .002). Lower graft function and ah score, higher proteinuria and ci + ct score, and, separately per each model, DSA (+) (HR = 2.446, P  = .034), DSA (+)/non-adherent (HR = 3.657, P  = .005) and DSA (+)/C1q (+) (HR = 4.831, P  = .003) status were independent predictors of graft failure. CAABMR with concomitant DSA pose a higher risk of graft failure. Adherence should be evaluated, and histopathological phenotyping and DSA characterization may add critical information. [ABSTRACT FROM AUTHOR]

Proteinuria is common after renal transplantation and affects between 35%-45% of patients during the same year as their transplant. We report a case of dual pathology in the renal allograft as a cause of severe proteinuria. A 38-year-old male presented with end-stage renal disease. He underwent live related renal allograft transplant. His immediate post-transplant period was unremarkable. He developed rise in serum creatinine (2.1 mg/dl) 6 months after transplant and was biopsied. He was diagnosed as a case of acute cellular rejection type Ib with suspicion for antibody mediated rejection. He was treated with methylprednisolone to which he showed a good response with return of serum creatinine to 1.6 mg/dl. Subsequently, he developed a nephrotic range proteinuria 6 months after this episode of rejection. Repeat biopsy was performed. He was diagnosed as a case of immune complex mediated glomerulonephritis (GN) (morphologically consistent with pattern of membranoproliferative glomerulonephritis) with chronic humoral rejection in the form of transplant glomerulopathy (TG). IHC for C4d and immunofluorescence studies were instrumental making the diagnosis. He was treated with steroids and rituximab to which he showed a good response with remission of proteinuria. This case highlights the importance of picking up dual pathology in an allograft biopsy to ensure appropriate therapy. The role of C4d and its correct interpretation is further highlighted, especially with regard to pattern (granular versus linear) and location (glomerular capillaries versus peritubular capillaries).

Background Immune responses to tissue-restricted self-antigens are thought to play a role in chronic rejection after solid organ transplantation. De novo development of antibodies (Abs) to vimentin have been reported to be associated with interstitial fibrosis/tubular atrophy after kidney transplant, and it has been suggested that immunoglobulin isotype switching of Abs to vimentin may occur during this process. We aimed to determine the correlation between immunoglobulin isotype switching of Abs to vimentin and development of transplant glomerulopathy (TG) after kidney transplant, and to determine whether citrullinated modification of vimentin is required for de novo anti-vimentin development. Methods Sera were collected from 24 patients with TG (diagnosed on biopsy), 24 matched stable kidney transplant recipients (KTxRs) and 22 normal healthy subjects who did not undergo transplant. Serum vimentin Abs concentrations were measured using enzyme-linked immunosorbent assay (ELISA). Immunoglobulin isotypes of anti-vimentin were determined using isotype-specific Abs conjugated with horseradish peroxidase. Samples were considered positive to vimentin Abs if the values were above mean + 2 × standard deviations of the levels in the healthy control subjects. Specificities of anti-vimentin for mutated citrullinated vimentin and anti-mutated citrullinated vimentin were measured by ELISA. Results In this retrospective analysis of 24 KTxRs with TG, 16/24 (67%) patients with biopsy-proven TG developed Abs to vimentin (645 ± 427 ng/ml). In contrast, only 4/24 (17%) stable KTxRs had detectable Abs to vimentin (275 ± 293 ng/ml; p = 0.001). Of the patients with TG, 15/24 (63%) developed Abs to vimentin of IgG isotype (572 ± 276 ng/ml), whereas only 6/24 (25%) stable KTxRs (310 ± 288 ng/ml) had anti-vimentin of IgG isotype (p = 0.002). However, no significant difference was noted in the concentration of IgM isotype anti-vimentin between KTxRs with TG (9/24 [38%], 407 ± 401 ng/ml) and stable KTxRs (5/24 [21%], 348 ± 439 ng/ml; p = 0.631). The serum concentration of Abs specific for the mutated form of citrullinated vimentin was not significantly different between KTxRs with TG and stable KTxRs. Conclusions Patients with biopsy-proven TG demonstrated significantly increased levels of anti-vimentin Abs of the IgG isotype compared with stable KTxRs. Anti-vimentin in stable KTxRs was primarily of IgM isotype. Therefore, the observed isotype switching of anti-vimentin from IgM to IgG isotype strongly suggests ongoing immune responses to vimentin in KTxRs diagnosed with TG. Furthermore, as opposed to patients with rheumatoid arthritis (who develop immune responses primarily to citrullinated vimentin), KTxRs diagnosed with TG developed immune responses to non-citrullinated vimentin, suggesting that modification of vimentin protein via citrullination is not required for the de novo anti-vimentin response seen in patients with TG. [ABSTRACT FROM AUTHOR]

Pediatric renal transplant recipient survival continues to improve, but ABMR remains a significant contributor to graft loss. ABMR prognostic factors to guide treatment are lacking. C4d staining on biopsies, diagnostic of ABMR, is associated with graft failure. Persistent C4d+ on follow-up biopsies has unknown significance, but could be associated with worse outcomes. We evaluated a retrospective cohort of 17 pediatric renal transplant patients diagnosed with ABMR. Primary outcome at 12 months was a composite of ≥50% reduction in eGFR, transplant glomerulopathy, or graft failure. Secondary outcome was the UPCR at 12 months. We used logistic and linear regression modeling to determine whether persistent C4d+ on follow-up biopsy was associated with the outcomes. Forty-one percent reached the primary outcome at 12 months. Persistent C4d+ on follow-up biopsy occurred in 41% and was not significantly associated with the primary outcome, but was significantly associated with the secondary outcome (estimate 0.22, 95% CI 0.19-0.25, P < .001), after controlling for confounding factors. Persistent C4d+ on follow-up biopsies was associated with a higher UPCR at 12 months. Patients who remain C4d+ on follow-up biopsy may benefit from more aggressive or prolonged ABMR treatment. [ABSTRACT FROM AUTHOR]

Peritubular capillary C4d (ptc-C4d) usually marks active antibody-mediated rejection, while pseudolinear glomerular capillary C4d ( GBM-C4d) is of undetermined diagnostic significance, especially when seen in isolation without concurrent ptc-C4d. We correlated GBM-C4d with structural GBM abnormalities and active antibody-mediated rejection in 319 renal transplant and 35 control native kidney biopsies. In kidney transplants, ptc-C4d was associated with GBM-C4d in 97% by immunofluorescence microscopy ( IF) and 61% by immunohistochemistry ( IHC; P < 0.001). Transplant glomerulopathy correlated with GBM-C4d ( P < 0.001) and presented with isolated GBM-C4d lacking ptc-C4d in 69% by IF and 40% by IHC. Strong isolated GBM-C4d was found post year-1 in repeat biopsies with transplant glomerulopathy. GBM-C4d staining intensity correlated with Banff cg scores (rs = 0.45, P < 0.001). Stepwise exclusion and multivariate logistic regression corrected for active antibody-mediated rejection showed significant correlations between GBM duplication and GBM-C4d ( P = 0.001). Native control biopsies with thrombotic microangiopathies demonstrated GBM-C4d in 92% ( IF, P < 0.001) and 35% ( IHC). In conclusion, pseudolinear GBM-C4d staining can reflect two phenomena: (i) structural GBM changes with duplication in native and transplant kidneys or (ii) active antibody-mediated rejection typically accompanied by ptc-C4d. While ptc-C4d is a dynamic 'etiologic' marker for active antibody-mediated rejection, isolated strong GBM-C4d can highlight architectural glomerular remodelling. [ABSTRACT FROM AUTHOR]

Transplant glomerulopathy is mainly due to chronic antibody-mediated rejection and actually represents a major cause of long-term allograft failure. The lack of effective treatment remains a serious problem in transplantation. A retrospective and uni-center study was performed in 48 kidney allograft recipients with transplant glomerulopathy between January 2010 and December 2015. Median time for diagnosis was 7.1 (3.6-11.8) years post-transplant. Light microscopy showed severity of transplant glomerulopathy in the majority of patients (cg1=10.4%; cg2=20.8%; cg3=68.8%). Moderate microvascular inflammation was present in 56.3% (g+ptc≥2), and almost half of recipients (51.1%) were C4d positive in immunofluorescence. Female gender ( P=.001), age ( P=.043), renal dysfunction ( P=.002), acute rejection episodes ( P=.026), and anti- HLA class II antibodies ( P=.004) were associated with kidney allograft failure. Treatment of transplant glomerulopathy was performed in 67.6% of patients. The histologic and laboratory features that led to a therapeutic intervention were score ptc ( P=.021), C4d ( P=.03), and the presence of anti- HLA antibodies ( P=.029), whereas score ah ( P=.005) was associated with conservative measure. The overall cumulative kidney allograft survival at 10 years was 75%. Treatment of transplant glomerulopathy was ineffective to improve long-term kidney allograft survival. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Chronic antibody mediated rejection (CAMR) is a major therapeutic challenge for achieving long-term graft survival; treatment options are limited to several anti-humoral interventions. MATERIAL and METHODS: Efficacy of rituximab combination therapy was retrospectively investigated by comparison with a historical control group for allograft function at six month and overall graft survival/dysfunction. The inclusion criterion was biopsy proven chronic AMR according to the Banff 2007 classification. Nineteen patients found eligible, rituximab group had nine patients (rituximab, plasmapheresis and low dose IVIG); control group had ten recipients. Predictive factors for graft failure also investigated according to Banff scores and renal functions. RESULTS: None of the outcomes were exposed significant efficacy of rituximab, although better treatment response at sixth month (55% vs. 40%, p=0.51), fewer overall graft failures (33% vs. 60%, p=0.25) and dysfunctions (66% vs. 80%, p=0.52). Overall, 47% of patients suffered graft failure. Advanced transplant glomerulopathy was found in 90% of biopsies (all scored ≥2). Peritubular capillaritis score (1.67±0.87 vs. 0.70±0.94, p=0.04) and interstitial inflammation score (1.78±0.44 vs. 1.00±0.47, p=0.004) were significantly higher in recipients who suffered graft failure. CONCLUSION: Rituximab could not sufficiently prevent further deterioration of allograft and failed to improve allograft survival in CAMR, especially after settlement of the irreversible transplant glomerulopathy. [ABSTRACT FROM AUTHOR]

Electron microscopy is a technology which was at one time widely used for renal as well as non-renal benign and malignant diseases, but its use has been rapidly declining as hospitals all over the world cut down on expenses. This leaves the renal pathologist with only light microscopy and immunofl uorescence at his disposal to diagnose diseases. Few studies have stated the importance of electron microscopy in routine renal biopsy reporting. We look at different cases where electron microscopy has been helpful in diagnosis and review the literature to assess the role this investigative modality still has to play in modern renal pathology. Journal of Pathology of Nepal (2013) Vol. 3, No.1, Issue 5, 411-415 DOI: http://dx.doi.org/10.3126/jpn.v3i5.7871

Interstitial fibrosis and tubular atrophy (IF/TA) are the most common cause of renal graft failure. Chronic transplant glomerulopathy (CTG) is present in approximately 1.5-3.0% of all renal grafts. We retrospectively studied the contribution of CTG and recurrent post-transplant glomerulopathies (RGN) to graft loss. We analyzed 123 patients with chronic renal allograft dysfunction and divided them into three groups: CTG (N = 37), RGN (N = 21), and IF/TA (N = 65). Demographic data were analyzed and the variables related to graft function identified by statistical methods. CTG had a significantly lower allograft survival than IF/TA. In a multivariate analysis, protective factors for allograft outcomes were: use of angiotensin-converting enzyme inhibitor (ACEI; hazard ratio (HR) = 0.12, P = 0.001), mycophenolate mofetil (MMF; HR = 0.17, P = 0.026), hepatitis C virus (HR = 7.29, P = 0.003), delayed graft function (HR = 5.32, P = 0.016), serum creatinine ≥1.5 mg/dL at the 1st year post-transplant (HR = 0.20, P = 0.011), and proteinuria ≥0.5 g/24 h at the 1st year post-transplant (HR = 0.14, P = 0.004). The presence of glomerular damage is a risk factor for allograft loss (HR = 4.55, P = 0.015). The presence of some degree of chronic glomerular damage in addition to the diagnosis of IF/TA was the most important risk factor associated with allograft loss since it could indicate chronic active antibody-mediated rejection. ACEI and MMF were associated with better outcomes, indicating that they might improve graft survival.

Desensitization with intravenous immunoglobulin (IVIG) and rituximab can improve transplantation rates in broadly sensitized kidney transplant recipients. However, long-term outcomes are lacking. Here we analyze long-term outcomes in living donor kidney transplant recipients desensitized with this regimen and compare them to low-risk recipients. Living donor kidney transplants that took place between July 2006 and December 2010 were considered retrospectively. The primary end point of the study was death-censored allograft survival at last follow-up. Secondary end points included patient survival, incidence of rejection, glomerular filtration rate (GFR), and proteinuria. There were 66 sensitized and 111 lowrisk patients included. Average follow-up was 68 months. There was no difference in long-term patient or graft survival. The rate of rejection was similar in the groups with more early rejection in the sensitized group and more late rejection in the low-risk group. There was more antibodymediated rejection in the sensitized group. Estimated GFR was similar during the follow-up period. Risk factors for rejection included a positive cross-match (HR: 2.4 CI: 1.35-4.40) and age (HR: 0.97 CI: 0.95-0.99). Desensitization with IVIG and rituximab has good long-term results with graft outcomes similar to non-HLA-sensitized patients despite higher immunologic risk. [ABSTRACT FROM AUTHOR]

The low sensitivity of C4d immunoreactivity in peritubular capillaries ( PTCs) hinders its use in the diagnosis of chronic active antibody-mediated rejection ( CAAMR). C4d-negative CAAMR was defined in the 2013 Banff classification, which included the expression of endothelial-associated transcripts ( ENDATs). We previously showed that the ENDAT caveolin-1 ( CAV-1) is a distinct feature of CAAMR. In this study, we investigated the prognostic value of CAV-1 immunoreactivity in PTCs in kidney transplant patients. Ninety-eight kidney transplant recipients were included in this study. The prognostic value of CAV-1 immunoreactivity in PTCs was evaluated by double immunostaining for CAV-1 and pathologische Anatomie Leiden endothelium ( PAL-E, a PTC marker) in the PTCs of kidney allograft biopsy samples. The patients were divided into two groups: CAV-1/ PAL-E<50% and CAV-1/ PAL-E≥50%. Kaplan-Meier curves showed that CAV-1/ PAL-E≥50% patients had a significantly worse prognosis than that of CAV-1/ PAL-E<50% patients (log-rank; P<.001). C4d staining of PTCs was not associated with the development of graft failure (log-rank; P=.345), whereas in a multivariate Cox regression analysis, CAV-1 immunoreactivity in PTCs was independently associated with graft failure (hazard ratio: 11.1; P=.0324). CAV-1 immunoreactivity in PTCs may serve as a prognostic marker for kidney allograft survival. [ABSTRACT FROM AUTHOR]