Recurrent idiopathic membranous nephropathy after kidney transplantation: a surveillance biopsy study

Similar incidence of graft glomerulonephritis in recipients with definitively diagnosed glomerulonephritis and those with unknown etiology: a retrospective observational study

OBJECTIVE

In China, most of the patients who underwent kidney transplants have unknown causes of end-stage renal disease (uESRD). However, little is known regarding the incidence of graft glomerulonephritis (GN) and graft survival in kidney transplant recipients (KTRs) with uESRD.

METHODS

In this retrospective cohort study, 473 of the 565 KTRs who underwent kidney transplantation (KTx) from 2015 to 2020 were included. We mainly observed the occurrence of graft GN between uESRD group and definitively diagnosed GN group, and repeatedly compared after propensity score matching (PSM).

RESULTS

The median follow-up was 50 months in 473 KTRs, and about 75% of KTRs of native kidney disease of unknown etiology. The total cumulative incidence of graft GN was 17%, and no difference was observed between the definitively diagnosed GN group and the uESRD group (p = 0.76). Further, PSM analysis also showed no difference in the incidence of graft GN between the 2 groups. Multivariable analysis disclosed males (p = 0.001), younger age (p = 0.03), and anti-endothelial cell anti-body (AECA) positive pre-KTx (p = 0.001) were independent risk factors for graft GN.

CONCLUSIONS

The incidence of graft GN was similar between uESRD and definitively diagnosed GN group. The allograft survival was also similar between two groups.

Ten tips on immunosuppression in primary membranous nephropathy

Membranous nephropathy (MN) management poses challenges, particularly in selecting appropriate immunosuppressive treatments (IST) and monitoring disease progression and complications. This article highlights 10 key tips for the management of primary MN based on current evidence and clinical experience. First, we advise against prescribing IST to patients without nephrotic syndrome (NS), emphasizing the need for close monitoring of disease progression. Second, we recommend initiating IST in patients with persistent NS or declining kidney function. Third, we suggest prescribing rituximab (RTX) or RTX combined with calcineurin inhibitors in medium-risk patients. Fourth, we propose cyclophosphamide-based immunosuppression for high-risk patients. Fifth, we discourage the use of glucocorticoid monotherapy or mycophenolate mofetil as initial treatments. Sixth, we underscore the importance of preventing infectious complications in patients receiving IST. Seventh, we emphasize the need for personalized monitoring of IST by closely measuring kidney function, proteinuria, serum albumin and anti-M-type phospholipase A2 receptor levels. Eighth, we recommend a stepwise approach in the treatment of resistant disease. Ninth, we advise adjusting treatment for relapses based on individual risk profiles. Finally, we caution about the potential recurrence of MN after kidney transplantation and suggest appropriate monitoring and treatment strategies for post-transplantation MN. These tips provide comprehensive guidance for clinicians managing MN, aiming to optimize patient outcomes and minimize complications.

Recurrence of membranous nephropathy after kidney transplantation: A multicenter retrospective cohort study

Membranous nephropathy (MN) is a leading cause of kidney failure worldwide and frequently recurs after transplant. Available data originated from small retrospective cohort studies or registry analyses; therefore, uncertainties remain on risk factors for MN recurrence and response to therapy. Within the Post-Transplant Glomerular Disease Consortium, we conducted a retrospective multicenter cohort study examining the MN recurrence rate, risk factors, and response to treatment. This study screened 22,921 patients across 3 continents and included 194 patients who underwent a kidney transplant due to biopsy-proven MN. The cumulative incidence of MN recurrence was 31% at 10 years posttransplant. Patients with a faster progression toward end-stage kidney disease were at higher risk of developing recurrent MN (hazard ratio [HR], 0.55 per decade; 95% confidence interval [CI], 0.35-0.88). Moreover, elevated pretransplant levels of anti-phospholipase A2 receptor (PLA2R) antibodies were strongly associated with recurrence (HR, 18.58; 95% CI, 5.37-64.27). Patients receiving rituximab for MN recurrence had a higher likelihood of achieving remission than patients receiving renin-angiotensin-aldosterone system inhibition alone. In sum, MN recurs in one-third of patients posttransplant, and measurement of serum anti-PLA2R antibody levels shortly before transplant could aid in risk-stratifying patients for MN recurrence. Moreover, patients receiving rituximab had a higher rate of treatment response.

Recurrence of Glomerulonephritis After Kidney Transplantation - Experience of One Center from 2020 to 2023

BACKGROUND

Glomerulonephritis (GN) after kidney transplantation is a common problem. Many of them are recurrences of the primary disease in the transplanted kidney. The course and prognosis of individual types of glomerulonephritis (GN) are very different and their appearance may worsen the graft survival. World statistics show significant discrepancies regarding the incidence of GN recurrence depending on the adopted protocol (protocolar biopsy or due to symptoms). We analyzed the transplanted kidney biopsy results that are performed only in symptomatic patients.

METHODS

A group of 125 patients transplanted and treated in one medical center were observed. In this group, in 32 patients, the primary kidney disease was GN, confirmed by kidney biopsy before transplantation. Twenty three kidney biopsies were performed; in 8, cases the primary disease was GN. The indication for biopsy were hematuria and/or proteinuria and/or graft failure.

RESULTS

We diagnosed 5 cases of GN, including 4 cases of GN recurrence (12.5% in whole GN group, 50% in symptomatic GN group). In the relapse group, there was 1 case of IgA nephropathy (the earliest recurrence 1 month after transplantation), 1 case of focal segmental glomerulosclerosis, 1 case of membranous nephropathy, and 1 case of lupus nephritis (the latest recurrence 1 year and 4 months after transplantation).

CONCLUSIONS

Our observation showed a high percentage of GN recurrences in symptomatic patients. This indicates the need to specify data regarding the diagnosis of recurrence depending on the adopted research method (protocolar or due to symptoms biopsy) to know which patients should be treated.

Recurrence of Idiopathic Membranous Nephropathy in the Kidney Allograft: A Systematic Review

INTRODUCTION

The recurrence of idiopathic membranous nephropathy (iMN) after kidney transplantation is common, although its exact clinical significance remains unclear. This systematic review aims to elucidate the effects of iMN recurrence on graft survival.

MATERIALS AND METHODS

A literature search was performed by systematically searching Medline, Scopus, Web of Science, and Google Scholar from inception. Cohort studies examining iMN recurrence after kidney transplantation were deemed eligible. Meta-analysis was performed by fitting random-effects models.

RESULTS

Twelve (12) articles published from 1995 to 2016 reporting on 139 transplant patients with recurrent iMN were included. The median time of the diagnosis of recurrent iMN was 18 months during follow-up from 35 to 120 months. Risk factors for iMN recurrence in the renal allograft are a positive serum test for anti-PLA2R antibodies pretransplant, female sex, younger age, high proteinuria pretransplant, the longest interval from initial disease to end-stage chronic kidney disease, and the combination of alleles HLA DQA1 05:01 and HLA DQB1 02:01. In the pretransplant period, 37 (26.61%) patients had a positive serum test and 18 (12.94%) patients had a positive biopsy stain for anti-PLA2R antibodies. The sensitivity of the pretransplant positive serum test for these antibodies ranges from 57% to 85.30% and the specificity is 85.10-100%. A total of 81.80% of patients who received rituximab as treatment for iMN recurrence achieved complete and partial remission, while 18.20% had no response to treatment. iMN recurrence was not associated with significantly different rates of graft loss (odds ratio = 1.03, 95% CI: 0.52-2.04, p = 0.524, I2 = 0.00%). Recurrence of iMN was not associated with increased risk of graft loss independently of whether patients were treated with rituximab (OR: 0.98, 95% CI: 0.39-2.50, I2: 0%) or not (OR: 1.22, 95% CI: 0.58-2.59, I2: 3.8%). Patients with iMN recurrence who achieved remission had significantly reduced risk of graft loss (OR: 0.14, 95% CI: 0.03 to 0.73).

CONCLUSION

The main outcome from this systematic review is that there is no statistically significant difference in graft survival in patients with iMN recurrence compared to those without recurrence in long-term follow-up. The achievement of remission is associated with significantly reduced risk of graft loss.

THSD7A-positive membranous nephropathy after kidney transplantation: A case report

Membranous nephropathy (MN) is a common cause of nephrotic syndrome after kidney transplantation (KT); however, scarce is known regarding post-KT thrombospondin type-1 domain-containing 7A (THSD7A)-positive MN. Herein, we report on a 72-year-old woman with end-stage kidney disease due to chronic interstitial nephritis (1996). In February 2020, she received a second deceased-donor KT, achieving optimal kidney function but presenting early post-KT proteinuria, reaching up to 1800mg/24h six months after transplantation, controlled with renin-angiotensin-aldosterone system (RAAS) blockade. In July 2021, a kidney allograft biopsy revealed features consistent with MN. Immunohistochemical stains showed diffuse and granular THSD7A and C4d deposition in glomerular capillary walls and negative PLA2R and IgG4 staining. No anti-THSD7A antibodies were detected in the serum. The pre-implantation biopsy showed no MN-associated lesions and negative THSD7A staining. Secondary triggers such as malignancy were discarded. The present report illustrates a THSD7A-positive MN in a KT recipient. Despite lacking native kidney biopsy and early presentation, a recurrent MN seemed unprovable due to documented native kidney disease and a long time span between native kidney disease and MN diagnosis. We, therefore, presumed primary de novo disease. Two years after KT, kidney function remains stable, and the patient has reached complete remission of proteinuria.

How to Choose the Right Treatment for Membranous Nephropathy

Membranous nephropathy is an autoimmune disease affecting the glomeruli and is one of the most common causes of nephrotic syndrome. In the absence of any therapy, 35% of patients develop end-stage renal disease. The discovery of autoantibodies such as phospholipase A2 receptor 1, antithrombospondin and neural epidermal growth factor-like 1 protein has greatly helped us to understand the pathogenesis and enable the diagnosis of this disease and to guide its treatment. Depending on the complications of nephrotic syndrome, patients with this disease receive supportive treatment with diuretics, ACE inhibitors or angiotensin-receptor blockers, lipid-lowering agents and anticoagulants. After assessing the risk of progression of end-stage renal disease, patients receive immunosuppressive therapy with various drugs such as cyclophosphamide, steroids, calcineurin inhibitors or rituximab. Since immunosuppressive drugs can cause life-threatening side effects and up to 30% of patients do not respond to therapy, new therapeutic approaches with drugs such as adrenocorticotropic hormone, belimumab, anti-plasma cell antibodies or complement-guided drugs are currently being tested. However, special attention needs to be paid to the choice of therapy in secondary forms or in specific clinical contexts such as membranous disease in children, pregnant women and patients undergoing kidney transplantation.

High exposure to tacrolimus is associated with spontaneous remission of recurrent membranous nephropathy after kidney transplantation

Introduction

We aimed to characterize the incidence and clinical presentation of membranous nephropathy (MN) after kidney transplantation (KT), and to assess allograft outcomes according to proteinuria rates and immunosuppression management.

Methods

Multicenter retrospective cohort study including patients from six Spanish centers who received a KT between 1991-2019. Demographic, clinical, and histological data were collected from recipients with biopsy-proven MN as primary kidney disease (n = 71) or MN diagnosed de novo after KT (n = 4).

Results

Up to 25.4% of patients with biopsy-proven MN as primary kidney disease recurred after a median time of 18.1 months posttransplant, without a clear impact on graft survival. Proteinuria at 3-months post-KT was a predictor for MN recurrence (rMN, HR 4.28; P = 0.008). Patients who lost their grafts had higher proteinuria during follow-up [1.0 (0.5-2.5) vs 0.3 (0.1-0.5) g/24 h], but only eGFR after recurrence treatment predicted poorer graft survival (eGFR < 30 ml/min: RR = 6.8). We did not observe an association between maintenance immunosuppression and recurrence diagnosis. Spontaneous remission after rMN was associated with a higher exposure to tacrolimus before recurrence (trough concentration/dose ratio: 2.86 vs 1.18; P = 0.028). Up to 94.4% of KT recipients received one or several treatments after recurrence onset: 22.2% rituximab, 38.9% increased corticosteroid dose, and 66.7% ACEi/ARBs. Only 21 patients had proper antiPLA2R immunological monitoring.

Conclusions

One-fourth of patients with biopsy-proven MN as primary kidney disease recurred after KT, without a clear impact on graft survival. Spontaneous remission after rMN was associated with a higher exposure to tacrolimus before recurrence.

Membranous nephropathy

Membranous nephropathy is a glomerulopathy, which main affected target is the podocyte, and has consequences on the glomerular basement membrane. It is more common in adults, especially over 50 years of age. The clinical presentation is nephrotic syndrome, but many cases can evolve with asymptomatic non-nephrotic proteinuria. The mechanism consists of the deposition of immune complexes in the subepithelial space of the glomerular capillary loop with subsequent activation of the complement system. Great advances in the identification of potential target antigens have occurred in the last twenty years, and the main one is the protein "M-type phospholipase-A2 receptor" (PLA2R) with the circulating anti-PLA2R antibody, which makes it possible to evaluate the activity and prognosis of this nephropathy. This route of injury corresponds to approximately 70% to 80% of cases of membranous nephropathy characterized as primary. In the last 10 years, several other potential target antigens have been identified. This review proposes to present clinical, etiopathogenic and therapeutic aspects of membranous nephropathy in a didactic manner, including cases that occur during kidney transplantation.

Rapid diagnosis of membranous nephropathy based on serum and urine Raman spectroscopy combined with deep learning methods

Membranous nephropathy is the main cause of nephrotic syndrome, which has an insidious onset and may progress to end-stage renal disease with a high mortality rate, such as renal failure and uremia. At present, the diagnosis of membranous nephropathy mainly relies on the clinical manifestations of patients and pathological examination of kidney biopsy, which are expensive, time-consuming, and have certain chance and other disadvantages. Therefore, there is an urgent need to find a rapid, accurate and non-invasive diagnostic technique for the diagnosis of membranous nephropathy. In this study, Raman spectra of serum and urine were combined with deep learning methods to diagnose membranous nephropathy. After baseline correction and smoothing of the data, Gaussian white noise of different decibels was added to the training set for data amplification, and the amplified data were imported into ResNet, AlexNet and GoogleNet models to obtain the evaluation results of the models for membranous nephropathy. The experimental results showed that the three deep learning models achieved an accuracy of 1 for the classification of serum data of patients with membranous nephropathy and control group, and the discrimination of urine data was above 0.85, among which AlexNet was the best classification model for both samples. The above experimental results illustrate the great potential of serum- and urine-based Raman spectroscopy combined with deep learning methods for rapid and accurate identification of patients with membranous nephropathy.

Membranous nephropathy: Clearer pathology and mechanisms identify potential strategies for treatment

Primary membranous nephropathy (PMN) is one of the common causes of adult-onset nephrotic syndrome and is characterized by autoantibodies against podocyte antigens causing in situ immune complex deposition. Much of our understanding of the disease mechanisms underpinning this kidney-limited autoimmune disease originally came from studies of Heymann nephritis, a rat model of PMN, where autoantibodies against megalin produced a similar disease phenotype though megalin is not implicated in human disease. In PMN, the major target antigen was identified to be M-type phospholipase A2 receptor 1 (PLA2R) in 2009. Further utilization of mass spectrometry on immunoprecipitated glomerular extracts and laser micro dissected glomeruli has allowed the rapid discovery of other antigens (thrombospondin type-1 domain-containing protein 7A, neural epidermal growth factor-like 1 protein, semaphorin 3B, protocadherin 7, high temperature requirement A serine peptidase 1, netrin G1) targeted by autoantibodies in PMN. Despite these major advances in our understanding of the pathophysiology of PMN, treatments remain non-specific, often ineffective, or toxic. In this review, we summarize our current understanding of the immune mechanisms driving PMN from animal models and clinical studies, and the implications on the development of future targeted therapeutic strategies.

Predictive Models for Recurrent Membranous Nephropathy After Kidney Transplantation

Recurrent membranous nephropathy (MN) posttransplantation affects 35% to 50% of kidney transplant recipients (KTRs) and accounts for 50% allograft loss 5 y after diagnosis. Predictive factors for recurrent MN may include HLA-D risk alleles, but other factors have not been explored with certainty.

Glomerular Diseases of the Kidney Allograft: Toward a Precision Medicine Approach

The continual development of potent immunosuppressive regimens has led to a decreased incidence of acute rejection and improvement of short-term kidney allograft survival. In contrast to acute rejection, glomerular diseases of the kidney allograft are being encountered more frequently and are emerging as leading causes of late kidney allograft failure. Although data on the pathogeneses of glomerular diseases in the kidney allograft are sparse, cumulative evidence suggests that post-transplant glomerular diseases may be the result of inherited predispositions and immunologic triggers. Although studying immunologic signals and performing genome-wide association studies are ideal approaches to tackle glomerular diseases in the kidney allograft, such studies are challenging because of the lack of adequately powered cohorts. In this review, we focus on the most commonly encountered recurrent and de novo glomerular diseases in the kidney allograft. We address the important advances made in understanding the immunopathology and genetic susceptibility of glomerular diseases in the native kidney and how to benefit from such knowledge to further our knowledge of post-transplant glomerular diseases. Defining genomic and immune predictors for glomerular diseases in the kidney allograft would support novel donor-recipient matching strategies and development of targeted therapies to ultimately improve long-term kidney allograft survival.

Recurrent Glomerular Disease after Kidney Transplantation: Diagnostic and Management Dilemmas

Recurrent glomerular disease after kidney transplant remains an important cause of allograft failure. Many of the different entities post-transplant still suffer from incomplete knowledge on pathophysiology, and therefore lack targeted and effective therapies. In this review, we focus on specific clinical dilemmas encountered by physicians in managing recurrent glomerular disease by highlighting new insights into the understanding and treatment of post-transplant focal segmental glomerulosclerosis, membranous nephropathy, atypical hemolytic uremic syndrome, C3 glomerulopathy, amyloid light-chain (AL) amyloidosis, and IgA nephropathy.

A conceptual framework linking immunology, pathology, and clinical features in primary membranous nephropathy

Primary membranous nephropathy is a leading cause of adult nephrotic syndrome. The field took a major step forward with the identification of phospholipase A2 receptor (PLA2R) as a target antigen in the majority of cases and with the ability to measure circulating autoantibodies to PLA2R. Since then, the existence of additional target antigens such as thrombospondin type-1 domain-containing 7A, exostosin 1 and 2, neural EGFL like 1, and semaphorin 3B has been demonstrated. The ability to detect and monitor levels of circulating autoantibodies has opened a new window onto the humoral aspect of primary membranous nephropathy. Clinicians now rely on clinical parameters such as proteinuria, as well as levels of circulating autoantibodies against PLA2R and the results of immunofluorescence staining for PLA2R within kidney biopsy tissue, to guide the management of this disease. The relationship between immunologic and clinical disease course is consistent, but not necessarily intuitive. In addition, kidney biopsy provides only a single snapshot of disease that needs to be interpreted in light of changing clinical and serological findings. A clear understanding of these dynamic parameters is essential for staging, treatment, and management of this disease. This review aims to shed light on current knowledge regarding the development and time course of changes in the serum levels of autoantibodies against PLA2R, proteinuria, and histological findings that underlie the pathophysiology of primary membranous nephropathy.

Primary membranous nephropathy in the era of autoantibodies and biological therapies

Primary membranous nephropathy is an autoimmune kidney disease and the most common cause of nephrotic syndrome in adults. About 70%-80% of cases are caused by anti-PLA2R antibodies. Its association with anti-THSD7A antibodies and other autoantibodies has also been described. Recent pilot studies and clinical trials have shown that several biological agents targeting autoantibody-producing cells are effective in controlling the disease with an acceptable safety profile. In this narrative review, we update key concepts about the pathogenesis, autoantibody-based diagnosis, and kidney biopsy findings in primary membranous nephropathy. In addition, we propose a diagnostic and therapeutic algorithm, including guidance on monitoring the response to therapy. We compare the efficacy and safety of currently available treatments, including rituximab and new biological agents, and identify unmet clinical needs.

KDIGO Clinical Practice Guideline on the Evaluation and Management of Candidates for Kidney Transplantation

The 2020 Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline on the Evaluation and Management of Candidates for Kidney Transplantation is intended to assist health care professionals worldwide who evaluate and manage potential candidates for deceased or living donor kidney transplantation. This guideline addresses general candidacy issues such as access to transplantation, patient demographic and health status factors, and immunological and psychosocial assessment. The roles of various risk factors and comorbid conditions governing an individual's suitability for transplantation such as adherence, tobacco use, diabetes, obesity, perioperative issues, causes of kidney failure, infections, malignancy, pulmonary disease, cardiac and peripheral arterial disease, neurologic disease, gastrointestinal and liver disease, hematologic disease, and bone and mineral disorder are also addressed. This guideline provides recommendations for evaluation of individual aspects of a candidate's profile such that each risk factor and comorbidity are considered separately. The goal is to assist the clinical team to assimilate all data relevant to an individual, consider this within their local health context, and make an overall judgment on candidacy for transplantation. The guideline development process followed the Grades of Recommendation Assessment, Development, and Evaluation (GRADE) approach. Guideline recommendations are primarily based on systematic reviews of relevant studies and our assessment of the quality of that evidence, and the strengths of recommendations are provided. Limitations of the evidence are discussed with differences from previous guidelines noted and suggestions for future research are also provided.

Recurrent Glomerulonephritis in the Kidney Allograft

Renal transplantation is the preferred form of renal replacement therapy in patients who develop end-stage kidney disease (ESKD). Among the diverse etiologies of ESKD, glomerulonephritis is the third most common cause, behind hypertensive and diabetic kidney disease. Although efforts to prolong graft survival have improved over time with the advent of novel immunosuppression, recurrent glomerulonephritis remains a major threat to renal allograft survival despite concomitant immunosuppression. As a result, clinical expertise, early diagnosis and intervention will help identify recurrent disease and facilitate prompt treatment, thus minimizing graft loss, resulting in improved outcomes. In this review, we highlight the clinicopathologcal characteristics of certain glomerular diseases that recur in the renal allograft.

Kidney transplantation for primary glomerulonephritis: Recurrence risk and graft outcomes with related versus unrelated donors

Primary glomerulonephritis can recur after kidney transplantation and may jeopardize the survival of the renal allograft. The risks of living-related kidney transplantation remain controversial in this group of patients. Living related transplantation offers potentially better HLA matching, therefore improve the long-term graft survival. However, the concern for increased rates of recurrence of the primary glomerulonephritis in the transplanted kidney from living related donors complicates the selection of donors. With the recent dramatic rise in the use of paired kidney exchange, there is now often the option of having a living related donor donate through a paired exchange. This raises the question of whether patients with primary glomerulonephritis should receive living donor kidneys through paired kidney exchange programs to obtain the benefits of a living donor kidney transplant while also reducing the risk of recurrent glomerulonephritis. Our review of the literature suggests that although the recurrence of primary glomerulonephritis occurs more often when donation occurs from a living related donor as compared to an unrelated donor, the graft survival advantage of living related donation is generally maintained despite the recurrence. We suggest that despite the increased risk of recurrence, living related donation should not be avoided in patients with primary glomerulonephritis as the cause of their end-stage renal disease.

Recurrent Glomerulonephritis after Renal Transplantation: The Clinical Problem

Glomerulonephritis (GN) continues to be one of the main causes of end-stage kidney disease (ESKD) with an incidence rating from 10.5% to 38.2%. Therefore, recurrent GN, previously considered to be a minor contributor to graft loss, is the third most common cause of graft failure 10 years after renal transplantation. However, the incidence, pathogenesis, and natural course of recurrences are still not completely understood. This review focuses on the most frequent diseases that recur after renal transplantation, analyzing rate of recurrence, epidemiology and risk factors, pathogenesis and bimolecular mechanisms, clinical presentation, diagnosis, and therapy, taking into consideration the limited data available in the literature. First of all, the risk for recurrence depends on the type of glomerulonephritis. For example, recipient patients with anti-glomerular basement membrane (GBM) disease present recurrence rarely, but often exhibit rapid graft loss. On the other hand, recipient patients with C3 glomerulonephritis present recurrence in more than 50% of cases, although the disease is generally slowly progressive. It should not be forgotten that every condition that can lead to chronic graft dysfunction should be considered in the differential diagnosis of recurrence. Therefore, a complete workup of renal biopsy, including light, immunofluorescence and electron microscopy study, is essential to provide the diagnosis, excluding alternative diagnosis that may require different treatment. We will examine in detail the biomolecular mechanisms of both native and transplanted kidney diseases, monitoring the risk of recurrence and optimizing the available treatment options.

The association of anti-PLA2R with clinical manifestations and outcomes in idiopathic membranous nephropathy: a meta-analysis

PURPOSE

The meta-analysis aims to investigate the relationship between anti-phospholipase A2 receptor autoantibody (anti-PLA2R) and clinical characteristics and adverse outcomes of idiopathic membranous nephropathy (IMN).

METHODS

Related studies published before February 2020 were systematically retrieved from foreign and domestic databases, RevMan5.3 software was used for meta-analysis and subgroup analysis, and STATA 15.0 statistical software was used for its heterogeneity and testing publication bias.

RESULTS

Twenty studies were included, involving 2224 patients with IMN. Our results showed that a significant correlation existed between the expression of serum anti-PLA2R and age (MD = 2.91, 95% CI = 2.15-3.67, P < 0.00001), total serum cholesterol (MD = 35.52, 95% CI = 9.52-61.52, P = 0.007), urine protein by creatinine ratio (UPCR) (MD = 2.15, 95% CI = 1.86-2.44, P<0.00001), serum albumin (MD = -0.40, 95% CI = -0.56 to -0.23, P < 0.00001), eGFR (MD = -10.44, 95% CI = -12.19 to -8.68, P < 0.00001), unremission rate (RR = 1.76, 95% CI = 1.37-2.27, P < 0.0001). In addition, the high titer in seropositive group was closely correlated with serum albumin (MD = -0.40, 95% CI = -0.74 to -0.05, P = 0.03), eGFR (MD = -12.40, 95% CI = -16.29 to -8.52, P < 0.00001) and unremission rate (RR = 2.52, 95% CI = 1.79-3.55, P < 0.00001). No significant correlation was found between glomerular anti-PLA2R and clinical manifestations except for serum cholesterol (MD = 0.81, 95% CI = 0.21-1.41, P = 0.008). However, in terms of prognosis, glomerular anti-PLA2R showed a significant relevance to recurrence rate (RR = 2.25, 95% CI = 1.07-4.72, P = 0.03).

CONCLUSION

Compared with glomerular anti-PLA2R, serum anti-PLA2R may better reflect the activities of IMN disease, while the glomerular anti-PLA2R might be connected with the recurrence of the disease.

Membranous Nephropathy Posttransplantation: An Update of the Pathophysiology and Management

Membranous nephropathy (MN) is a common cause of nephrotic syndrome after transplantation and is associated with an increased risk of allograft loss. MN may occur either as a recurrent or as a de novo disease. As in native kidneys, the pathophysiology of the MN recurrence is in most cases associated with antiphospholipid A2 receptor antibodies. However, the posttransplant course has some distinct features when compared with primary MN, including a lower chance of spontaneous remission and a greater requirement for adjuvant immunosuppressive therapy to induce complete remission. Although the efficacy of rituximab in primary MN is now well established, no randomized studies have assessed its effectiveness in MN after transplant, and there are no specific recommendations for the management of these patients. This review aims to synthesize and update the pathophysiology of posttransplant MN, as well as to address unsolved issues specific to transplantation, including the prognostic value of antiphospholipid A2 receptor, the risk of living-related donation, the link between de novo MN and rejection, and different therapeutic strategies so far deployed in posttransplant MN. Lastly, we propose a management algorithm for patients with MN who are planning to receive a kidney transplant, including pretransplant considerations, posttransplant monitoring, and the clinical approach after the diagnosis of recurrence.

Membranous Nephropathy (MN) Recurrence After Renal Transplantation

Primary membranous nephropathy (MN) is a frequent cause of NS in adults. In native kidneys the disease may progress to ESRD in the long term, in some 40–50% of untreated patients. The identification of the pathogenic role of anti-podocyte autoantibodies and the development of new therapeutic options has achieved an amelioration in the prognosis of this disease. MN may also develop in renal allograft as a recurrent or a de novo disease. Since the de novo MN may have some different pathogenetic and morphologic features compared to recurrent MN, in the present paper we will deal only with the recurrent disease. The true incidence of the recurrent form is difficult to assess. This is mainly due to the variable graft biopsy policies in kidney transplantation, among the different transplant centers. Anti-phospholipase A2 receptor (PLA2R) autoantibodies are detected in 70–80% of patients. The knowledge of anti-PLA2R status before transplant is useful in predicting the risk of recurrence. In addition, the serial survey of the anti-PLA2R titers is important to assess the rate of disease progression and the response to treatment. Currently, there are no established guidelines for prevention and treatment of recurrent MN. Symptomatic therapy may help to reduce the signs and symptoms related to the nephrotic syndrome. Anecdotal cases of response to cyclical therapy with steroids and cyclophosphamide have been published. Promising results have been reported with rituximab in both prophylaxis and treatment of recurrence. However, these results are based on observational data, and prospective controlled trials are still missing.

Recurrent Membranous Nephropathy After Kidney Transplantation Associated With Phospholipase A2 Receptor and Successfully Treated With Rituximab: A Case Report

Primary membranous nephropathy (MN) is an organ-specific autoimmune disease mainly caused by autoantibodies acting against the podocyte antigen M-type phospholipase A2 receptor 1 (PLA2R). Herein we present the clinical and histologic findings, including PLA2R staining, of early recurrent MN after kidney transplantation that was successfully treated with rituximab. A 60-year-old Japanese man had end-stage renal failure due to steroid-resistant primary MN and underwent ABO-incompatible living donor kidney transplantation. At 1 month after transplantation, a protocol biopsy revealed positive granular staining of IgG, C4d, and PLA2R on glomerular capillaries (GCs) without any abnormalities on light microscopy (LM). Although the patient had low-level proteinuria, recurrent MN was suspected based on the positive PLA2R staining; he was treated with an angiotensin receptor blocker and a single dose of 200 mg rituximab. However, proteinuria gradually increased to 877 mg/d. At 21 months after transplantation, a graft biopsy revealed spikes along the outer aspects of GC on LM, with stronger staining for PLA2R than that at 1 month after transplantation. A single dose of 500 mg rituximab was added, which effectively reduced proteinuria, and clinical remission continued until 3 years after transplantation. The latest graft biopsy showed reduced staining of PLA2R. The disease activity and therapeutic effect were well-reflected in the intensity of PLA2R staining. An approach intending an early diagnosis by protocol biopsy using PLA2R immunostaining is made and early treatment with rituximab will help reduce the risk of kidney graft loss due to recurrent primary MN.

Abnormalities in Protocol Graft Kidney Biopsy 6 Months Posttransplantation in a Tertiary Care Center Hospital of Nepal

BACKGROUND

Increasing graft survival is the prime focus of every transplantation program. Detection of subclinical abnormalities with the help of protocol renal graft biopsies performed at predetermined intervals after transplantation has been one of the approaches. The objective was to study the abnormalities in protocol renal graft biopsy specimens at 6 months posttransplantation.

METHODS

This was a hospital-based observational descriptive study. It included the recipients who underwent kidney transplantation between October 2014 and September 2015. The recipients were followed up postoperatively on an outpatient basis, as per the institution protocol. At 6 months posttransplantation, protocol graft biopsy was performed in all patients with normal functioning allograft without proteinuria after obtaining informed written consent.

RESULTS

A total of 57 patients with chronic kidney disease underwent renal transplantation during the study period. Protocol biopsy was performed in 47 recipients. Subclinical rejection was found in 4 (8.5%) recipients. Two recipients had significant tubulitis and interstitial inflammation. One of them showed features of Banff Type IA cellular rejection (t2, i2) and another showed Banff Type IB cellular rejection (t3, i2). Biopsy specimen of 1 recipient showed significant glomerulitis and peritubular capillaritis (g3, ptc1). Another recipient showed significant peritubular capillaritis (ptc2) with C4d positivity. IgA nephropathy was present in 6 (12.8%) recipients. BK virus nephropathy was found in 2 (4.3%) recipients.

CONCLUSION

This study demonstrates that abnormal histologic findings occur in protocol graft biopsy specimens at 6 months post renal transplantation in patients without any clinical or laboratory abnormalities.

Clinical Presentation, Outcomes, and Treatment of Membranous Nephropathy after Transplantation

There are scarce data about clinical presentation and outcomes of posttransplant membranous nephropathy (MN), and few reports include a large number of patients. This was a retrospective cohort including adult patients with posttransplant MN transplanted between 1983 and 2015 in a single center (n=41). Only patients with histological diagnosis of MN in kidney grafts were included. Clinical and laboratory presentation, histological findings, treatment, and outcomes were detailed. Patients were predominantly male (58.5%), with a mean age of 49.4 ± 13.2 years; 15 were considered as recurrent primary MN; 3 were class V lupus nephritis; 14 were considered as de novo cases, 7 secondary and 7 primary MN; and 9 cases were considered primary but it was not possible to distinguish between de novo MN and recurrence. Main clinical presentations were proteinuria (75.6%) and graft dysfunction (34.1%). Most patients with primary recurrent and de novo primary MN were submitted to changes in maintenance immunosuppressive regimen, but no standard strategy was identified; 31 patients presented partial or complete remission, and glomerulopathy appeared not to impact graft and patient survival.

Recurrent membranous nephropathy and acute cellular rejection in a patient treated with direct anti-HCV therapy (ledipasvir/sofosbuvir)

Direct-acting antiviral agents (DAAs) are very effective therapy for chronic hepatitis C infection, and have revolutionized the treatment of hepatitis C in kidney allograft recipients. Although well tolerated in general, rare renal complications have been reported. We describe a case of recurrent membranous nephropathy and acute cellular rejection in a kidney allograft recipient after DAA (ledipasvir/sofosbuvir) therapy, whose allograft function had been stable for more than 30 years. The patient was presented with nephrotic range proteinuria with stable creatinine. The kidney allograft biopsy revealed recurrent membranous nephropathy with fine granular deposits of IgG1/IgG4 codominance and positive phospholipase A2 receptor (PLA2R) staining. The patient was treated with pulse steroid and rituximab, leading to a decrease in proteinuria. As DAAs are more frequently used, physicians should be aware of immune-related renal complications.

[Membranous nephropathy: Pathophysiology and natural history]

Membranous nephropathy is a major cause of nephrotic syndrome in adults, with various etiologies and outcomes. One third of patients enter spontaneous remission with blockade of the renin-angiotensin system, one third develop a persistent nephrotic syndrome, while another third of patients develop end-stage kidney disease and 40% of them relapse after kidney transplantation. Treatment of membranous nephropathy remains controversial. Immunosuppressive therapy is only recommended in case of renal function deterioration or persistent nephrotic syndrome after 6months of renin-angiotensin system blockade. Therefore, delayed immunosuppressive treatments may lead to significant and potentially irreversible complications. For long, no biological markers could predict clinical outcome and guide therapy. The discovery of autoantibodies to the phospholipase A2 receptor (PLA2R1) in 2009, and to the thrombospondin type 1 domain containing 7A (THSD7A) in 2014 in respectively 70 and 5% of patients with membranous nephropathy were major breakthroughs. The passive infusion of human anti-THSD7A antibodies in mouse induces proteinuria and membranous nephropathy. The identification of these antigens has allowed developing diagnostic and prognostic tests. High anti-PLA2R1 titers at time of diagnosis predict a poor renal outcome. Anti-PLA2R1 antibodies can bind at least three different domains of PLA2R1. Epitope spreading with binding of two or three of these antigenic domains is associated with active membranous nephropathy and poor renal survival. These new tools could help us to monitor disease severity and to predict renal prognosis for a better selection of patients that should benefit of early immunosuppressive therapy.

Recurrent glomerular disease after kidney transplantation

PURPOSE OF REVIEW

With improving short-term kidney transplant outcomes, recurrent glomerular disease is being increasingly recognized as an important cause of chronic allograft failure. Further understanding of the risks and pathogenesis of recurrent glomerular disease enable informed transplant decisions, along with the development of preventive and treatment strategies.

RECENT FINDINGS

Multiple observational studies have highlighted differences in rates and outcomes for various recurrent glomerular diseases, although these rates have not markedly improved over the last decade. Emerging evidence supports use of rituximab to treat recurrent primary membranous nephropathy and possibly focal segmental glomerulosclerosis (FSGS), whereas eculizumab is effective in glomerular diseases associated with complement dysregulation [C3 glomerulopathy (C3G) and atypical hemolytic uremic syndrome (aHUS)].

SUMMARY

Despite the potential for recurrence in the allograft, transplant remains the optimal therapy for patients with advanced chronic kidney disease (CKD) secondary to primary glomerular disease. Biomarkers and therapeutic options necessitate accurate pretransplant diagnoses with opportunities for improved surveillance and treatment of recurrent glomerular disease posttransplant.

[Current insights about recurrence of glomerular diseases after renal transplantation]

Recurrence of glomerular disease after renal transplantation is a frequent cause of graft loss. Incidence, risk factors and outcome of recurrence are widely due to the underlying glomerular disease. Graft biopsy analysis is required to confirm the definitive diagnosis of recurrence and to start an appropriate therapy that, in some cases, remains challenging to prevent graft failure. Increased use of protocol biopsy and recent advances in our understanding of the pathogenesis of some glomerular diseases with the identification of some relevant biomarkers provide a unique opportunity to initiate kidney-protective therapy at early stages of recurrence on the graft. This review summarizes our current knowledge on the management of many recurrent primary and secondary glomerulonephritis after kidney transplantation.

Kidney Transplant Recipients With Primary Membranous Glomerulonephritis Have a Higher Risk of Acute Rejection Compared With Other Primary Glomerulonephritides

BACKGROUND

Despite being the leading cause of graft failure, there is a lack of published data about the rates of rejection in kidney transplant patients with glomerulonephritis as the cause of end-stage renal disease.

METHODS

We examined all consecutive adult (>18 years) renal transplant recipients with biopsy-proven native renal glomerular disease who underwent kidney transplant between 1994 and 2013. Glomerulonephritis groups included were IgA nephropathy (IgAN) (N = 306), focal segmental glomerulosclerosis (FSGS) (N = 298), membranous nephropathy (MN) (N = 81), and lupus nephritis (LN) (N = 177).

RESULTS

In the total cohort of 862 patients, 363 patients had an episode of acute rejection during the follow-up period of 19 years (incidence rate of 7.2% per year). Forty-five of 81 patients with MN had an episode of acute rejection during the follow-up period. Patients with MN had significantly higher incidence of acute rejection (12.1 per 100 person years, P < 0.05) in comparison to IgAN (7.2 per 100 person years), FSGS (7.4 per 100 person years), and LN (7.9 per 100 person years). Patients with MN had 1.9 times higher risk of developing acute rejection after transplant in comparison to IgAN (P < 0.005). In patients with MN, 33 of 45 (73.3%) rejection events were acute cellular rejection, 8 (17.8%) of 45 were acute antibody-mediated rejection and 6 of 45 (13.3%) were combined cellular and antibody-mediated acute rejection. Despite higher rates of acute rejection, 10-year allograft survival was similar in all subgroups.

CONCLUSIONS

Patients with MN have higher incidence of acute rejection after kidney transplant but have similar 10-year allograft survival in comparison to the other glomerular diseases like IgAN, FSGS, and LN.

Treatment of membranous nephropathy: time for a paradigm shift

In patients with membranous nephropathy, alkylating agents (cyclophosphamide or chlorambucil) alone or in combination with steroids achieve remission of nephrotic syndrome more effectively than conservative treatment or steroids alone, but can cause myelotoxicity, infections, and cancer. Calcineurin inhibitors can improve proteinuria, but are nephrotoxic. Most patients relapse after treatment withdrawal and can become treatment dependent, which increases the risk of nephrotoxicity. The discovery of nephritogenic autoantibodies against podocyte M-type phospholipase A2 receptor (PLA₂R) and thrombospondin type-1 domain- containing protein 7A (THSD7A) antigens provides a clear pathophysiological rationale for interventions that specifically target B-cell lineages to prevent antibody production and subepithelial deposition. The anti-CD20 monoclonal antibody rituximab is safe and achieves remission of proteinuria in approximately two-thirds of patients with membranous nephropathy. In those with PLA₂R-related disease, remission can be predicted by anti-PLA₂R antibody depletion and relapse by antibody re-emergence into the circulation. Thus, integrated evaluation of serology and proteinuria could guide identification of affected patients and treatment with individually tailored protocols. Nonspecific and toxic immunosuppressive regimens will fall out of use. B-cell modulation by rituximab and second-generation anti-CD20 antibodies (or plasma cell-targeted therapy in anti-CD20 resistant forms of disease) will lead to a novel therapeutic paradigm for patients with membranous nephropathy.

Primary Membranous Nephropathy

Membranous nephropathy (MN) is a unique glomerular lesion that is the most common cause of idiopathic nephrotic syndrome in nondiabetic white adults. About 80% of cases are renal limited (primary MN, PMN) and 20% are associated with other systemic diseases or exposures (secondary MN). This review focuses only on PMN. Most cases of PMN have circulating IgG4 autoantibody to the podocyte membrane antigen PLA2R (70%), biopsy evidence PLA2R staining indicating recent immunologic disease activity despite negative serum antibody levels (15%), or serum anti-THSD7A (3%-5%). The remaining 10% without demonstrable anti-PLA2R/THSd7A antibody or antigen likely have PMN probably secondary to a different, still unidentified, anti-podocyte antibody. Considerable clinical and experimental data now suggests these antibodies are pathogenic. Clinically, 80% of patients with PMN present with nephrotic syndrome and 20% with non-nephrotic proteinuria. Untreated, about one third undergo spontaneous remission, especially those with absent or low anti-PLA2R levels, one-third progress to ESRD over 10 years, and the remainder develop nonprogressive CKD. Proteinuria can persist for months after circulating anti-PLA2R/THSD7A antibody is no longer detectable (immunologic remission). All patients with PMN should be treated with supportive care from the time of diagnosis to minimize protein excretion. Patients with elevated anti-PLA2R/THSD7A levels and proteinuria >3.5 g/d at diagnosis, and those who fail to reduce proteinuria to <3.5 g after 6 months of supportive care or have complications of nephrotic syndrome, should be considered for immunosuppressive therapy. Accepted regimens include steroids/cyclophosphamide, calcineurin inhibitors, and B cell depletion. With proper management, only 10% or less will develop ESRD over the subsequent 10 years.

Bortezomib as a Novel Approach to Early Recurrent Membranous Glomerulonephritis After Kidney Transplant Refractory to Combined Conventional Rituximab Therapy

We report a case of early recurrent membranous glomerulonephritis after kidney transplant from a deceased donor. The patient received induction therapy and was discharged with a serum creatinine level of 0.78 mg/dL on triple maintenance immunosuppressive therapy, which included tacrolimus, mycophenolate mofetil, and prednisone. At 7 months after transplant, a graft biopsy for new-onset isolated proteinuria (2.7 g/day) revealed stage 2 recurrent membranous glomerulonephritis. In the face of persistent proteinuria despite combined conservative rituximab therapy over several months and the total eradication of CD20-positive cells, bortezomib was introduced. This resulted in a substantial decline in proteinuria within 2 months and its subsequent disappearance several months later. This was paralleled by a considerable drop in plasma CD34-positive and CD138-positive cell counts. These preliminary observations indicate that recurrent posttransplant membranous glomerulonephritis is associated in part with a B-cell- mediated immunologic process that may involve both CD20-positive and plasma cells. Rituximab-resistant or partially responsive recurrent posttransplant membranous glomerulonephritis may benefit from a proteasome inhibitor-based therapy.

A Proposal for a Serology-Based Approach to Membranous Nephropathy

Primary membranous nephropathy (MN) is an autoimmune disease mainly caused by autoantibodies against the recently discovered podocyte antigens: the M-type phospholipase A2 receptor 1 (PLA2R) and thrombospondin type 1 domain-containing 7A (THSD7A). Assays for quantitative assessment of anti-PLA2R antibodies are commercially available, but a semiquantitative test to detect anti-THSD7A antibodies has been only recently developed. The presence or absence of anti-PLA2R and anti-THSD7A antibodies adds important information to clinical and immunopathologic data in discriminating between primary and secondary MN. Levels of anti-PLA2R antibodies and possibly, anti-THSD7A antibodies tightly correlate with disease activity. Low baseline and decreasing anti-PLA2R antibody levels strongly predict spontaneous remission, thus favoring conservative therapy. Conversely, high baseline or increasing anti-PLA2R antibody levels associate with nephrotic syndrome and progressive loss of kidney function, thereby encouraging prompt initiation of immunosuppressive therapy. Serum anti-PLA2R antibody profiles reliably predict response to therapy, and levels at completion of therapy may forecast long-term outcome. Re-emergence of or increase in antibody titers precedes a clinical relapse. Persistence or reappearance of anti-PLA2R antibodies after kidney transplant predicts development of recurrent disease. We propose that an individualized serology-based approach to MN, used to complement and refine the traditional proteinuria-driven approach, will improve the outcome in this disease.

Recent advances in our understanding of recurrent primary glomerulonephritis after kidney transplantation

Recurrent glomerulonephritis (GN) is an important cause of kidney allograft failure, particularly in younger recipients. Approximately 15% of death-censored graft failures are due to recurrent GN, but this incidence is likely an underestimation of the magnitude of the problem. Overall, 18% to 22% of kidney allografts are lost due to GN, either recurrent or presumed de novo. The impact of recurrent GN on allograft survival was recognized from the earliest times in kidney transplantation. However, progress in this area has been slow, and our understanding of GN recurrence remains limited, in large part due to incomplete understanding of the pathogenesis of these diseases. This review focuses on recent advances in our general understanding of the pathophysiology of primary GN, the risk of recurrence in the allograft, and the consequences for kidney graft survival. We focus specifically on the most common forms of primary GN, including focal segmental glomerulosclerosis, membranous nephropathy, membranoproliferative glomerulonephritis, and IgA nephropathy. New understanding of the pathogenesis of these diseases has had direct clinical implications for transplantation, allowing better identification of candidates at high risk of recurrence and earlier diagnoses, and it is expected to lead to significance improvements in the therapy and perhaps even prevention of GN recurrence. More than ever, it is essential to fully characterize GN before transplantation as this information will direct our management posttransplantation. Further, the relative rarity of recurrent GN dictates the need for multicenter studies in order to evaluate, test, and validate recent advances and therapies.

HLA-DR, and not PLA2R, is expressed on the podocytes in kidney allografts in de novo membranous nephropathy

Idiopathic membranous nephropathy (IMN) is known to be associated with antibodies acting on the M-type phospholipase A2 receptor (PLA2R) of the podocyte. However, the mechanism underlying de novo membranous nephropathy (dn MN) posttransplantation remains unclear. In this study, we aimed to elucidate the mechanism underlying dn MN.We selected 8 cases with dn MN and compared them to 20 IMN cases. Fifteen cases of stable grafts were selected as controls.Several differences between the dn MN group and the IMN group were detected. IgG4 showed negligible positive staining in patients with dn MN, while it was predominant in the IMN group (1/8 vs 20/20, P < 0.001). Serum anti-PLA2R antibodies and anti-PLA2R antibodies of the podocyte were very few in the dn MN patients; however, these antibodies were detected in most of the IMN patients (serum anti-PLA2R antibodies: 1/8 vs 16/20, P = 0.002, anti-PLA2R antibodies of the podocyte: 0/8 vs 17/20, P < 0.001). The dn MN patients also showed higher ratio of interstitial inflammation, peritubular capillaritis, and peritubular capillary C4d deposition. Importantly, human leukocyte antigens (HLA)-DR expression was detected on the podocytes in most of the dn MN patients, but none of the IMN patients and stable graft patients showed HLA-DR expression.These data suggested that the PLA2R pathway, which is known to play a role in IMN, was not involved in the mechanism underlying dn MN. On the contrary, dn MN might be associated with the alloimmune response directed against the podocyte.

Membranous Nephropathy: A Journey From Bench to Bedside

Lessons from an animal model that faithfully resembles human membranous nephropathy (MN) have informed our understanding of the pathogenesis of this organ-specific autoimmune disease and common cause of nephrotic syndrome. After it was established that the subepithelial immune deposits that characterize experimental MN form in situ when circulating antibodies bind to an intrinsic podocyte antigen, it was merely a matter of time before the human antigen was identified. The M-type phospholipase A2 receptor 1 (PLA2R) represents the major target antigen in primary MN, and thrombospondin type 1 domain-containing 7A (THSD7A) was more recently identified as a minor antigen. Serologic tests for anti-PLA2R and kidney biopsy specimen staining for PLA2R show >90% specificity and 70% to 80% sensitivity for the diagnosis of primary MN in most populations. The assays distinguish most cases of primary MN from MN associated with other systemic diseases, and sequential anti-PLA2R titers are useful to monitor treatment response. A positive pretransplantation test result for anti-PLA2R is also helpful for predicting the risk for posttransplantation recurrence. Identification of target epitopes within PLA2R and the genetic association of primary MN with class II major histocompatibility and PLA2R1 variants are 2 additional examples of our evolving understanding of this disease.

Pre-transplant phospholipase A2 receptor autoantibody concentration is associated with clinically significant recurrence of membranous nephropathy post-kidney transplantation

Previous studies that have assessed the association of pre-transplant antiphospholipase A2 receptor autoantibody (PLA2R-Ab) concentration with a recurrence of membranous nephropathy (rMN) post-kidney transplant have yielded variable results. We tested 16 consecutive transplant patients with a history of iMN for pre-transplant PLA2R-Ab. Enzyme-linked immunosorbent assay titers (Euroimmun, NJ, USA) >14 RU/mL were considered positive. A receiver operating characteristic (ROC) analysis was performed after combining data from Quintana et al. (n = 21; Transplantation February 2015) to determine a PLA2R-Ab concentration which could predict rMN. Six of 16 (37%) patients had biopsy-proven rMN at a median of 3.2 yr post-transplant. Of these, five of six (83%) had a positive PLA2R-Ab pre-transplant with a median of 82 RU/mL (range = 31-1500). The only patient who had rMN with negative PLA2R-Ab was later diagnosed with B-cell lymphoma. One hundred percent (n = 10) of patients with no evidence of rMN (median follow-up = five yr) had negative pre-transplant PLA2R-Ab. In a combined ROC analysis (n = 37), a pre-transplant PLA2R-Ab > 29 RU/mL predicted rMN with a sensitivity of 85% and a specificity of 92%. Pre-transplant PLA2R-Ab could be a useful tool for the prediction of rMN. Patients with rMN in the absence of PLA2R-Ab should be screened for occult malignancy and/or alternate antigens.

Frequency of the Original Kidney Disease and Its Effect on the Outcome of Kidney Transplant in the Urology-Nephrology Center Mansoura University

OBJECTIVES

Renal allograft function and graft survival depends on many factors, including the source of the graft, immunologic matching between donor and recipient, incidence of acute rejection, and recurrence of the original kidney disease. This work aimed to evaluate the effects of the original kidney disease on patient and graft survival.

MATERIALS AND METHODS

This was a retrospective, single-center study that included 2189 kidney transplant recipients who were transplanted at The Urology and Nephrology Centre, Mansoura University, between 1976 and 2010. Of 2189 recipients, 1350 patients with unknown original kidney disease were excluded, with the remaining 839 patients divided into 4 groups according to their original kidney disease.

RESULTS

We found pretransplant dialysis and blood transfusion to be statistically significant among the 4 groups. Regarding induction immunosuppressive therapy, a statistical significance was found between the 4 groups regarding the presence and type of induction therapy, with no statistical significance regarding the type of maintenance immunosuppression. There was no statistical significance between the 4 groups regarding the incidence of acute and chronic rejection. We also found recurrence of original kidney disease to be statistically significant in the 4 groups, particularly in the group that included patients with glomerular disease, where the highest rate of recurrence was reported in patients with focal segmental glomerulosclerosis and membranoproliferative glomerulonephritis, and patient and graft survival was also statistically significant.

CONCLUSIONS

The original kidney disease has an effect on renal allograft function and graft and patient survival.

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

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

Recurrent Membranous Nephropathy After Kidney Transplantation: Treatment and Long-Term Implications

BACKGROUND

Membranous nephropathy (MN) can recur in kidney allografts leading to graft dysfunction and failure. The aims of these analyses were to assess MN recurrence, clinical and histologic progression, and response to anti-CD20 therapy.

METHODS

Included were 63 kidney allograft recipients with biopsy proven primary MN followed up for 77.0 (39-113) months (median, interquartile range). Disease recurrence was diagnosed by biopsy (protocol or clinical), and follow-up was monitored by laboratory parameters and protocol biopsies.

RESULTS

Thirty of 63 patients (48%) had histologic recurrence often during the first year. In 53% of the cases, recurrence was diagnosed by protocol biopsy. Recurrence risk was higher in patients with higher proteinuria pretransplant [hazard ratio = 1.869 (95% confidence interval, 1.164-3.001) per gram, P = 0.010] and those with anti-phospholipase A2 receptor antibodies [hazard ratio = 3.761 (1.635-8.652), P = 0.002]. Thirteen patients with recurrence had no clinical progression, and in 2, MN resolved histologically. Seventeen of 63 patients (27%) had progressive proteinuria and were treated with anti-CD20 antibodies, resulting in complete response in 9 (53%), partial response in 5 (29%), and no response in 3 (18%). Posttreatment biopsies were obtained in 15 patients and showed histologic resolution in 6 (40%). Disease recurrence did not correlate with graft survival. However, 5 of 11 (45.4%) graft losses were due to recurrent MN. Death-censored graft survival in MN did not differ from that of 273 control recipients with autosomal dominant polycystic kidney disease.

CONCLUSIONS

Membranous nephropathy recurs in 48% of cases threatening the allograft. Treatment of early but progressive recurrence with anti-CD20 antibodies is quite effective achieving clinical remission and histologic resolution of MN.

Anti-phospholipase A₂ receptor antibodies in recurrent membranous nephropathy

About 70% of patients with primary membranous nephropathy (MN) have circulating anti-phospholipase A2 receptor (PLA2R) antibodies that correlate with disease activity, but their predictive value in post-transplant (Tx) recurrent MN is uncertain. We evaluated 26 patients, 18 with recurrent MN and 8 without recurrence, with serial post-Tx serum samples and renal biopsies to determine if patients with pre-Tx anti-PLA2R are at increased risk of recurrence as compared to seronegative patients and to determine if post-Tx changes in anti-PLA2R correspond to the clinical course. In the recurrent group, 10/17 patients had anti-PLA2R at the time of Tx versus 2/7 patients in the nonrecurrent group. The positive predictive value of pre-Tx anti-PLA2R for recurrence was 83%, while the negative predictive value was 42%. Persistence or reappearance of post-Tx anti-PLA2R was associated with increasing proteinuria and resistant disease in 6/18 cases; little or no proteinuria occurred in cases with pre-Tx anti-PLA2R and biopsy evidence of recurrence in which the antibodies resolved with standard immunosuppression. Some cases with positive pre-Tx anti-PLA2R were seronegative at the time of recurrence. In conclusion, patients with positive pre-Tx anti-PLA2R should be monitored closely for recurrent MN. Persistence or reappearance of antibody post-Tx may indicate a more resistant disease.

Prediction of membranous nephropathy recurrence after transplantation by monitoring of anti-PLA2R1 (M-type phospholipase A2 receptor) autoantibodies: a case series of 15 patients

BACKGROUND

The predictive value of anti-M-type phospholipase A2 receptor (PLA2R1) autoantibodies for membranous nephropathy (MN) recurrence after renal transplantation remains controversial.

METHODS

Our aim was to monitor anti-PLA2R1 IgG4 activity using a sensitive enzyme-linked immunosorbent assay in 15 kidney transplant recipients with MN, and to test the correlation between antibody titres and MN recurrence.

RESULTS

Five patients never exhibited anti-PLA2R1 antibodies, and one of them relapsed. Ten patients (67%) had IgG4 anti-PLA2R1 antibodies at the time of transplantation and during follow-up. The presence of IgG4 anti-PLA2R1 antibodies at the time of kidney transplantation does not imply MN recurrence (P = 0.600, n = 15). However, a positive IgG4 anti-PLA2R1 activity during follow-up (>Month 6) was a significant risk factor for MN relapse (P = 0.0048, n = 10). Indeed, four patients had persistent IgG4 anti-PLA2R1 activity after transplantation and relapsed. Among them, one was successfully treated with rituximab. Another had persistently high IgG4 anti-PLA2R1 activity and exhibited a histological relapse but no proteinuria while on treatment with renin-angiotensin system inhibitors. In contrast, the six other patients who did not relapse exhibited a decrease of their IgG4 anti-PLA2R1 activity following transplant immunosuppression, including two with proteinuria due to biopsy-proven differential diagnoses. A weak transplant immunosuppressive regimen was also a risk factor of MN recurrence (P = 0.0048, n = 10). Indeed, the six patients who received both an induction therapy and a combined treatment with calcineurin inhibitors/mycophenolate exhibited a decrease of IgG4 anti-PLA2R1 activity and did not relapse, while the four patients who did not receive this strong immunosuppressive treatment association had persistently high IgG4 anti-PLA2R1 activity and relapsed.

CONCLUSION

The monitoring of IgG4 anti-PLA2R1 titres during follow-up helps to predict MN recurrence, and a strong immunosuppressive treatment of anti-PLA2R1 positive patients may prevent recurrence.

Membranous nephropathy: from models to man

As recently as 2002, most cases of primary membranous nephropathy (MN), a relatively common cause of nephrotic syndrome in adults, were considered idiopathic. We now recognize that MN is an organ-specific autoimmune disease in which circulating autoantibodies bind to an intrinsic antigen on glomerular podocytes and form deposits of immune complexes in situ in the glomerular capillary walls. Here we define the clinical and pathological features of MN and describe the experimental models that enabled the discovery of the major target antigen, the M-type phospholipase A2 receptor 1 (PLA2R). We review the pathophysiology of experimental MN and compare and contrast it with the human disease. We discuss the diagnostic value of serological testing for anti-PLA2R and tissue staining for the redistributed antigen, and their utility for differentiating between primary and secondary MN, and between recurrent MN after kidney transplant and de novo MN. We end with consideration of how knowledge of the antigen might direct future therapeutic strategies.

Immunopathogenesis of membranous nephropathy: an update

Membranous nephropathy (MN) is a non-inflammatory organ-specific autoimmune disease which affects the kidney glomerulus, resulting in the formation of immune deposits on the outer aspect of the glomerular basement membrane, complement-mediated proteinuria, and severe renal failure in 30% of patients. In the last 10 years, substantial advances have been made in the understanding of the molecular bases of MN, with the identification of several antigens and predisposing genes in children and adults. These ground-breaking findings already have a major impact on diagnosis and monitoring and to some extent on therapies. However, there is evidence that the disease is more complex and involves a variety of antigen-antibody systems and genes involved in immune response, progression, recovery, and protective mechanisms. We herein review these recent findings which open new perspectives of research. Understanding the complex pathogenesis of MN will offer many opportunities for future therapeutic interventions and will hopefully have a major impact on patient care. New insights into the molecular mechanisms of MN may also enlighten the pathogenesis of organ-specific autoimmune diseases.