Recurrent Membranous Nephropathy After Kidney Transplantation: Treatment and Long-Term Implications. Transplantation. 2015; Epub ahead of print. [PMID: 26720301 DOI: 10.1097/tp.0000000000001056]

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.

Proliferative glomerulonephritis with monoclonal immunoglobulin G deposits is associated with high rate of early recurrence in the allograft

The characteristics of allograft proliferative glomerulonephritis with monoclonal immunoglobulin G deposits (PGNMID) are not well defined. To better characterize this disease we retrospectively identified 26 patients with allograft PGNMID, including 16 followed with early protocol biopsies. PGNMID was found to be a recurrent disease in most (89%) patients. A diagnostic biopsy was done for proteinuria and/or increased creatinine in most patients. Median time from transplant to diagnostic biopsy was 5.5 months, with detection within three to four months post-transplant in 86% of patients. Mesangial proliferative glomerulonephritis was the most common pattern on the diagnostic biopsy with 89% of cases showing immunoglobulin G3 subtype restriction. A detectable serum paraprotein was present in 20% of patients. During a mean follow up of 87 months from implantation, 11 of 25 patients lost their allograft largely due to PGNMID within a mean of 36 months from diagnosis. Median graft survival was 92 months. Independent predictors of graft loss were a higher degree of peak proteinuria and longer time from implantation to diagnosis. Sixteen patients were treated with immunosuppressive therapy which resulted in over 50% reduction in proteinuria in 60%, and improvement of glomerular pathology in nine of 13 patients. However, 44% of responders subsequently relapsed. Thus, PGNMID has a high recurrence rate in renal allografts occurring early with detection enhanced by protocol biopsies. Graft outcome is guarded as nearly half of patients lose their graft within three years from diagnosis. Hence, there is a need for better treatment strategies for this disease.

The clinicopathological features of patients with membranous nephropathy

Background

Membranous nephropathy (MN) represents a distinct glomerular disease which has been considered as a major cause of nephrotic syndrome (NS) in adults. Evidences show that the clinicopathological features of MN are various among MN cases. This study aimed to summarize and analyze the clinicopathological features of patients with MN.

Methods

A total of 231 MN patients were recruited in this study. Their clinical and pathological features were collected and analyzed according to their age, gender, pathological stages, and anti-phospholipase A2 receptor (anti-PLA2R) antibodies tests.

Results

Among the 231 MN cases, the ratio of male to female was 1.47 and the mean age was 47.43±14.32 years. Altogether, 163 (70.6%) cases were positive for NS. Their serum antiPLA2R, body mass index, total cholesterol, triglyceride, low density lipoprotein cholesterol, D2, IgA, and IgE were increased, but IgG was decreased. The majority of the patients were middle aged and old aged. In addition, the pathological stage was significantly correlated with gender (P=0.038), creatinine, (P=0.021) and IgE (P=0.003). A total of 74.9% MN patients were found to be positive for anti-PLA2R antibodies, and they were more likely to have abnormal serum indices.

Conclusion

The major clinicopathological characteristics of MN patients are summarized in this study. Male and elder MN cases are likely to have rapid disease progression. Advanced pathological stages and being positive for anti-PLA2R antibodies may be potential indicators for disease activity of MN.

Membranous Nephropathy and Anti-Podocytes Antibodies: Implications for the Diagnostic Workup and Disease Management

The discovery of circulating antibodies specific for native podocyte antigens has transformed the diagnostic workup and greatly improved management of idiopathic membranous nephropathy (iMN). In addition, their identification has clearly characterized iMN as a largely autoimmune disorder. Anti-PLA2R1 antibodies are detected in approximately 70% to 80% and anti-THSD7A antibodies in only 2% of adult patients with iMN. The presence of anti-THSD7A antibodies is associated with increased risk of malignancy. The assessment of PLA2R1 and THSD7A antigen expression in glomerular immune deposits has a better sensitivity than measurement of the corresponding autoantibodies. Therefore, in the presence of circulating anti-podocytes autoantibodies and/or enhanced expression of PLA2R1 and THSD7A antigens MN should be considered as primary MN (pMN). Anti-PLA2R1 or anti-THSD7A autoantibodies have been proposed as biomarkers of autoimmune disease activity and their blood levels should be regularly monitored in pMN to evaluate disease activity and predict outcomes. We propose a revised clinical workup flow for patients with MN that recommends assessment of kidney biopsy for PLA2R1 and THSD7A antigen expression, screening for circulating anti-podocytes antibodies, and assessment for secondary causes, especially cancer, in patients with THSD7A antibodies. Persistence of anti-podocyte antibodies for 6 months or their increase in association with nephrotic proteinuria should lead to the introduction of immunosuppressive therapies. Recent data have reported the efficacy and safety of new specific therapies targeting B cells (anti-CD20 antibodies, inhibitors of proteasome) in pMN which should lead to an update of currently outdated treatment guidelines.

Recurrence of primary glomerulonephritis: Review of the current evidence

In view of the availability of new immunosuppression strategies, the recurrence of allograft glomerulonephritis (GN) are reported to be increasing with time post transplantation. Recent advances in understanding the pathogenesis of the GN recurrent disease provided a better chance to develop new strategies to deal with the GN recurrence. Recurrent GN diseases manifest with a variable course, stubborn behavior, and poor response to therapy. Some types of GN lead to rapid decline of kidney function resulting in a frustrating return to maintenance dialysis. This subgroup of aggressive diseases actually requires intensive efforts to ascertain their pathogenesis so that strategy could be implemented for better allograft survival. Epidemiology of native glomerulonephritis as the cause of end-stage renal failure and subsequent recurrence of individual glomerulonephritis after renal transplantation was evaluated using data from various registries, and pathogenesis of individual glomerulonephritis is discussed. The following review is aimed to define current protocols of the recurrent primary glomerulonephritis therapy.

The utility of phospholipase A2 receptor autoantibody in membranous nephropathy after kidney transplantation

Membranous nephropathy (MN) is estimated to cause end-stage renal disease in ∼ 5% of patients, in whom renal transplantation is the therapy of choice. Among patients receiving a transplant for MN, the disease will recur in the graft in 30–50%; among these, graft loss will occur in 50% within 10 years. Several studies have suggested that phospholipase A2 receptor autoantibody (aPLA2R) levels before transplantation might be useful in predicting recurrence, and their titration after transplantation is clinically relevant to assess the risk of recurrence and progression, to guide treatment indications and to monitor treatment response. In this review we describe the evolving role of aPLA2R as a biomarker in primary MN and its current usefulness in predicting recurrence of this autoimmune podocytopathy after renal transplantation.

Pre- and Posttransplant Refractory Idiopathic Membranous Glomerulonephritis: The Forgotten Potential Culprit

Idiopathic membranous nephropathy has been recently recognized as an autoimmune disease that may recur or develop de novo posttransplant, whereby specific auto- or alloantibodies are directed against recently recognized podocyte structures such as the phospholipase receptor PLAR2 and the thrombospondin receptor THSD7A. The observed inconsistencies in therapeutic responses with all presently recognized therapies irrespective of immunosuppressive regimen used and the superiority of complete and sustained remission rates in recurrent disease after kidney transplant compared with native disease imply the existence of different immunopathogenic signatures that may be operational, either isolated or combined, in the pathogenesis of membranous nephropathy. These pathogenic mechanisms involve primarily B-cell-mediated pathways with a T-cell help component and distinct auto- and alloantibody-secreting mechanisms involving different B cells. These pathways are present in separate compartments such as in CD20+-activated B cells found in spleen and lymph nodes, CD19+/CD20- plasmablasts and short-lived plasma cells in the blood, and CD19-/CD20-/CD38+/CD138+ long-lived memory plasma cells niched naturally in the bone marrow and ectopically in the native or grafted inflamed kidney. These latter nonproliferating plasma cells lacking CD19 and CD20 markers would be resistant to in vivo B-cell depletion by anti-CD20 monoclonal therapies. They produce considerable amounts of immunoglobulin G (IgG) autoantibodies and alloantibodies and provide the basis for humoral memory and refractory autoimmune diseases. This may explain the limited rate of sustained complete remission, which, as observed in most studies, does not exceed a rate of 20% in all rituximab-treated patients despite total B-cell eradication. There is an important need for the development of new biomarkers to help identify and predict therapeutic responses. Potential new therapeutic targets against plasma cells such as proteasome inhibitors, anti-CD38 monoclonal antibodies, and autoreactive pathogenic B-cell-specific depleting regimens, as well as new anti-CD20 monoclonal antibodies, may help tailor therapy to the individual need for optimal outcome.

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.

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.