Specific antigen-based stratification of membranous nephropathy in patients after haematopoietic stem cell allotransplantation - a case series and literature review.

BACKGROUND: Nephrotic syndrome (NS) is a rare complication that can occur after haematopoietic stem cell transplantation (HSCT). In patients with membranous nephropathy (MN) who have undergone allogeneic HSCT, a new antigen called protocadherin FAT1 has been identified. Our objective is to present a case series of MN patients after HSCT with a novel antigen-based stratification. CASE PRESENTATIONS: Patients who developed full-blown NS due to MN after an HSCT were enrolled in the University Hospital Centre Zagreb study. The first two patients were treated with an HSCT for acute myeloid leukaemia, and both developed NS after cessation of graft versus host disease (GVHD) prophylaxis. The first patient had reduced kidney function, while the second had completely preserved function. Kidney biopsy showed MN with only subepithelial deposits. A thorough examination revealed that there was no secondary cause of the disease. The patients achieved complete remission after undergoing immunosuppression treatment. The third patient underwent HSCT for acute lymphoblastic leukaemia. He developed both acute and chronic GVHD and also experienced avascular hip necrosis. After sixteen years, the patient developed NS with preserved kidney function. The kidney specimen showed membranous nephropathy (MN) with mesangial and subepithelial deposits. Extensive research was conducted, but no secondary cause for the MN was detected. All three cases tested negative for anti-PLA2R antibodies. Biopsy tissue samples were analysed using laser microdissection and tandem mass spectrometry of glomeruli for the detection of different specific antigens. Patients one and two tested positive for FAT1, whereas patient three tested positive for PCSK6. CONCLUSIONS: MN can develop at various time intervals after HSCT. Specific antigen testing can help establish the relationship between MN and HSCT. In the future, serum testing for anti-FAT1 antibodies in HSCT patients could be significant in diagnosing FAT1-associated MN, similar to how anti-PLA2R antibodies are significant in diagnosing PLA2R-associated MN.

Expansion of T follicular helper cells is associated with disease progression in rat experimental membranous nephropathy model.

BACKGROUND: T follicular helper (Tfh) cells drive humoral immunity by facilitating B cell responses, but the functional role of Tfh cells in the pathogenesis of idiopathic membranous nephropathy (IMN) remains unclear. OBJECTIVES: This study aimed to establish a rat experimental membranous nephropathy model, investigate the phenotypic characteristics of Tfh cells, and analyze a clinically significant correlation between Tfh cells. MATERIAL AND METHODS: Passive Heymann nephritis (PHN) rats were induced by immunizing Sprague Dawley rats with anti-Fx1A serum. The frequency of Tfh and B cell subsets was analyzed with flow cytometry (FC). The serum concentration of interleukin-21 (IL-21), the relative mRNA expression levels of IL-21 and B cell lymphoma 6 (Bcl-6) in spleen mononuclear cells (MNCs), and the kidney infiltration of CD4+ T cells and IL-21 were assessed. The potential correlations among these measures were analyzed. RESULTS: In comparison with the control group, significantly increased percentages of Tfh cells, inducible T cell co-stimulator-positive (ICOS+) Tfh cells, and mRNA expression of Bcl-6 were detected in the spleen of PHN rats. Elevated IL-21 expression was detected in the serum and kidneys. Remarkably, the percentage of splenic ICOS+ Tfh cells was positively correlated with 24 h urine protein concentrations (r = 0.676, p = 0.011) in PHN rats. CONCLUSION: These data indicate that ICOS+ Tfh cells contribute to development of IMN, and they might be potential therapeutic targets for IMN.

The fate of immune complexes in membranous nephropathy.

The most characteristic feature of membranous nephropathy (MN) is the presence of subepithelial electron dense deposits and the consequential thickening of the glomerular basement membrane. There have been great advances in the understanding of the destiny of immune complexes in MN by the benefit of experimental models represented by Heymann nephritis. Subepithelial immune complexes are formed in situ by autoantibodies targeting native autoantigens or exogenous planted antigens such as the phospholipase A2 receptor (PLA2R) and cationic BSA respectively. The nascent immune complexes would not be pathogenic until they develop into immune deposits. Podocytes are the major source of autoantigens in idiopathic membranous nephropathy. They also participate in the modulation and removal of the immune complexes to a large extent. The balance between deposition and clearance is regulated by a wide range of factors such as the composition and physicochemical properties of the immune complexes and the complement system. Complement components such as C3 and C1q have been reported to be precipitated with the deposits whereas a complement regulatory protein CR1 expressed by podocytes is involved in the phagocytosis of immune complexes by podocytes. Podocytes regulate the dynamic change of immune complexes which is disturbed in membranous nephropathy. To elucidate the precise fate of the immune complexes is essential for developing more rational and novel therapies for membranous nephropathy.

B cell dysregulation and depletion therapy in primary membranous nephropathy: Prospects and potential challenges.

B cells are crucial to the humoral immune response, originating in the bone marrow and maturing in the spleen and lymph nodes. They primarily function to protect against a wide range of infections through the secretion of antibodies. The role of B cells in primary membranous nephropathy (PMN) has gained significant attention, especially following the discovery of various autoantibodies that target podocyte antigens and the observed positive outcomes from B cell depletion therapy. Increasing evidence points to the presence of abnormal B cell subsets and functions in MN. B cells have varied roles during the different stages of disease onset, progression, and relapse. Initially, B cells facilitate self-antigen presentation, activate effector T cells, and initiate cellular immunity. Subsequently, the disruption of both central and peripheral immune tolerance results in the emergence of autoreactive B cells, with strong germinal center responses as a major source of MN autoantibodies. Additionally, critical B cell subsets, including Bregs, memory B cells, and plasma cells, play roles in the immune dysregulation observed in MN, assisting in predicting disease recurrence and guiding management strategies for MN. This review offers a detailed overview of research advancements on B cells and elucidates their pathological roles in MN.

Angiotensin II Type 2 Receptor Antibodies in Glomerular Diseases.

We evaluated the concentration of AT2R antibodies in 136 patients with primary and secondary glomerular diseases: membranous nephropathy (n = 18), focal and segmental glomerulosclerosis (n = 25), systemic lupus erythematosus (n = 17), immunoglobulin A (IgA) nephropathy (n = 14), mesangial (non-IgA) proliferative nephropathy (n = 6), c-ANCA vasculitis (n = 40), perinuclear anti-neutrophil cytoplasmic antibodies (p-ANCA) vasculitis (n = 16), and compared it with a healthy control group (22 patients). Serum creatinine levels, proteinuria, serum albumin, and total protein concentrations were prospectively recorded for 2 years. The mean levels of AT2R antibodies in the lupus nephropathy group were significantly higher compared to the control group, 64.12 ± 26.95 units/mL and 9.72 ± 11.88 units/mL, respectively. There was no association between this level and the clinical course of the disease. The AT2R levels in other kinds of glomerular disease were no different from the control group. We found significant correlations between AT1R and AT2R in patients with membranous nephropathy (r = 0.66), IgA nephropathy (r = 0.61), and c-ANCA vasculitis (r = 0.63). Levels of AT2R antibodies in systemic lupus erythematosus are higher compared to other types of glomerulonephritis, vasculitis, and a healthy control group. Levels of AT2R antibodies correlate with AT1R antibodies in the groups of patients with membranous nephropathy, IgA nephropathy, and c-ANCA vasculitis. These kinds of AT2R antibodies have a stimulative effect on AT2R, but we have not found the influence of these antibodies on the clinical course of glomerular diseases.

Novel approaches to primary membranous nephropathy: Beyond the KDIGO guidelines.

Primary membranous nephropathy (PMN) is an immune-mediated glomerular disease. Rituximab (RTX) is recommended as a first-line immunosuppressive therapy and shows high clinical efficacy, but the optimal doses remain controversial. Approximately 20%-40% of PMN patients experience RTX resistance and failure. Reduced bioavailability, RTX internalization and attack, anti-RTX antibody production, autoreactive B-cell reservoirs and chronic and irreversible renal damage may contribute to this problem. Therefore, new treatment modalities are needed to compensate for this deficit. New interventions and new dose combinations are being proposed. Multiple drug combination therapies show comparable clinical efficacy to conventional treatments by blocking the production of disease-causing antibodies in multiple directions, and can reduce single-agent doses without increasing adverse effects. New therapies that directly target B cells, plasma cells, and antibody production have shown encouraging results. In addition, new techniques for sweeping antibodies and chimeric antigen receptor T-cell therapy also may be promising strategies for PMN. Immunoadsorption could be used as an auxiliary choice for severe cases. This article explores new treatments for PMN and highlights possible mechanisms for potential new technologies that offer new ideas for treatment.

The effectiveness of ruxolitinib and cyclophosphamide combination on T helper 17 and regulatory T cells in rat experimental membranous glomerulonephritis.

The progression and pathogenesis of membranous glomerulonephritis (MGN) are inextricably linked to chronic inflammation. Despite improving clinical remission rates due to the application of cyclophosphamide (CYC), treatment of MGN still requires further exploration. Ruxolitinib (Ruxo) negatively affects the signaling pathways participating in the production of pro-inflammatory cytokines. Hence, we investigated whether the combination of CYC and Ruxo can modulate inflammation through influencing T helper 17 (Th17) lineages and regulatory T cells (Tregs). Passive Heymann nephritis (PHN), an experimental model of MGN, was induced in a population of rats. Then, the animals were divided into five groups: PHN, CYC-receiving, Ruxo-receiving, CYC-Ruxo-receiving PHN rats, and healthy controls. After 28 days of treatment, biochemistry analysis was performed and splenocytes were isolated for flowcytometry investigation of Th17 cells and Tregs. The correlative transcription factors of the cells, alongside their downstream cytokine gene expressions, were also assessed using real-time PCR. Furthermore, serum cytokine signatures for the lymphocytes were determined through ELISA. The combination of CYC and Ruxo significantly reduced the serum values of urea in rats versus the PHN group (24.62 ± 7.970 vs. 40.60 ± 10.81 mg/dL). In contrast to Treg's activities, the functionality of Th17 cells noticeably increased not only in PHN rats but also in CYC or Ruxo-receiving PHN animals when compared with the control (10.60 ± 2.236, 8.800 ± 1.465, 8.680 ± 1.314 vs. 4.420 ± 1.551 %). However, in comparison to the PHN group, the incidence of Th17 cells notably fell in rats receiving CYC and Ruxo (10.60 ± 2.236 vs. 6.000 ± 1.373 %) in favor of the Treg's percentage (5.020 ± 1.761 vs. 8.980 ± 1.178 %), which was verified by the gene expressions and cytokine productions correlative to these lymphocytes. The combination of CYC and Ruxo was able to decline Th17 cells in favor of Tregs improvement in PHN rats, suggesting an innovative combination therapy in MGN treatment approaches.

The correlation between anti-phospholipase A2 receptor antibodies and hypercoagulability in patients with idiopathic membranous nephropathy.

BACKGROUND: Patients with idiopathic membranous nephropathy (IMN) are more likely to be complicated by venous thromboembolism (VTE). The aim of the study was to investigate the potential association between anti-phospholipase A2 receptor (PLA2R) antibodies and hypercoagulability in patients with IMN. METHODS: A total of 168 patients with biopsy-proven IMN and 36 patients with biopsy-proven minimal change disease (MCD) were enrolled in this study. The clinical data, serum anti-PLA2R antibodies and coagulation-related indices of the patients were retrospectively analyzed. RESULTS: Patients with IMN were categorized into glomerular PLA2R staining-positive (GAg+) IMN group and glomerular PLA2R staining-negative (GAg-) IMN group in the study. Patients with IMN who were GAg + had lower PT, APTT and R time than patients with IMN who were GAg-, while the CI value was higher in patients with IMN who were GAg+. Patients with IMN who were GAg + were divided into the SAb+/GAg + group and the SAb-/GAg + group. Patients with IMN who were SAb+/GAg + had higher Fib and MA values than patients with IMN who were SAb-/GAg+. Correlation analysis showed that serum anti-PLA2R antibodies were positively correlated with fibrinogen, D-dimer, K time, CI value, α-angle, and MA value. Multiple linear regression analysis indicated that anti-PLA2R antibodies were independently correlated with fibrinogen and MA value. CONCLUSION: Our study provides a new perspective on the underlying mechanisms of hypercoagulability in patients with IMN. Anti-PLA2R antibodies are associated with hypercoagulability in patients with IMN and may affect coagulation in patients with IMN by affecting platelet aggregation function and fibrinogen counts.

Membranous Nephropathy: Updates on Management.

Membranous nephropathy is a major etiology of nephrotic syndrome in adults and less frequently in children. Circulating antibodies to intrinsic podocyte antigens, such as M-type phospholipase A2 receptor, or to extrinsic proteins accumulate beneath the podocyte to cause damage via complement activation and/or other mechanisms. The availability of clinical testing for autoantibodies to M-type phospholipase A2 receptor has allowed noninvasive diagnosis of this form of membranous nephropathy and a means to monitor immunologic activity to guide immunosuppressive therapy. Treatment of membranous nephropathy includes optimal supportive care with renin-angiotensin-system blockers, lipid-lowering agents, diuretics, lifestyle changes, and additional immunosuppressive therapy in patients with an increased risk of progression to kidney failure. Rituximab has been recognized as a first-line immunosuppressive therapy for most membranous nephropathy patients with an increased risk of progressive disease, except those with life-threatening nephrotic syndrome or rapidly deteriorating kidney function from membranous nephropathy. This article discusses the major and minor antigens described in membranous nephropathy, the natural history of the disease, and guidelines for clinical management and immunosuppressive treatment.

RACGAP1 is a pivotal gene in lung adenocarcinoma-associated membranous nephropathy: Based on comprehensive bioinformatics analysis and machine learning.

BACKGROUND: This study performs a detailed bioinformatics and machine learning analysis to investigate the genetic foundations of membranous nephropathy (MN) in lung adenocarcinoma (LUAD). METHODS: In this study, the gene expression profiles of MN microarray datasets (GSE99339) and LUAD dataset (GSE43767) were downloaded from the Gene Expression Omnibus database, common differentially expressed genes (DEGs) were obtained using the limma R package. The biological functions were analyzed with R Cluster Profiler package according to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Machine learning algorithms, including LASSO regression, support vector machine (SVM), Random Forest, and Boruta analysis, were applied to identify hubgenes linked to LUAD-associated MN. These genes' prognostic values were evaluated in the TCGA-LUAD cohort and validated through immunohistochemistry on renal biopsy specimens. RESULTS: A total of 36 DEGs in common were identified for downstream analyses. Functional enrichment analysis highlighted the involvement of the Toll-like receptor 4 pathway and several immune recognition pathways in LUAD-associated MN. COL3A1, PSENEN, RACGAP1, and TNFRSF10B were identified as hub genes in LUAD-associated MN using machine learning algorithms. ROC analysis demonstrated their effective discrimination of MN with high accuracy. Survival analysis showed that lung adenocarcinoma patients with higher expression of these genes had significantly reduced overall survival. In patients with lung adenocarcinoma-associated MN, RACGAP1, COL3A1, PSENEN, and TNFRSF10B were higher expressed in the glomerular, especially RACGAP1, indicating an important role in the pathogenesis of LUAD-associated membranous nephropathy. CONCLUSIONS: Our study underscores the critical role of RACGAP1, COL3A1, PSENEN, and TNFRSF10B in the development of LUAD-associated MN, providing important insights for future research and the development of potential therapeutic strategies.

Low risk of hepatitis B virus reactivation in membranous nephropathy patients with resolved infection undergoing rituximab-based regimens without antiviral prophylaxis.

INTRODUCTION: Patients with resolved hepatitis B virus infection undergoing rituximab are at risk of hepatitis B virus reactivation without antiviral prophylaxis. However, the risk in such patients treated with rituximab-based regimens for membranous nephropathy is not clear. We evaluated the risk of hepatitis B virus reactivation in membranous nephropathy patients with resolved infection undergoing rituximab-based regimens without antiviral prophylaxis. METHODS: Clinical data of 51 membranous nephropathy patients with resolved hepatitis B virus infection undergoing rituximab-based regimens without antiviral prophylaxis were retrospectively analyzed. Among these, 21 patients were followed for more than 1 year after rituximab discontinuation. The clinical data collected aimed to assess patients' responses and the risk of hepatitis B virus reactivation during and after rituximab treatment. RESULTS: 30/51 (58.8 %) patients reached complete or partial remission at 12 months. None of the patients experienced HBsAg seroreversion during rituximab treatment. Alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transpeptidase and total bilirubin levels, as well as the numbers of patients who exceeded the upper limits of normal for alkaline phosphatase and prothrombin time, did not show any statistically significant difference during rituximab-based therapy. Neither did the anti-HBs level, the number of patients with protective anti-HBs titers exceeding 10 U/L, nor the levels of CD19+ B cells, CD4+ T cells, CD8+ T cells, and natural killer cells. Among the 21 patients followed for 12 (ranging from 12 to 19) months after rituximab discontinuation, no hepatitis B virus reactivation was observed. The mean anti-HBs level and the number of patients with anti-HBs titers over 10 U/L did not show any statistically significant difference during the extended follow-up of 33 patient-years. Neither did the CD4+ T cell, CD8+ T cell, nor the natural killer cell counts. One patient presented with an ALT level that exceeded the baseline value by three times and reached above 100 U/L, accompanied by elevations in AST, GGT, and ALP levels. Meanwhile, the anti-HBs titer was 816.09 U/L, and HBsAg was negative. CONCLUSION: The administration of rituximab-based regimens in membranous nephropathy patients with hepatitis B virus resolved infection leads to a low risk of hepatitis B virus reactivation without antiviral prophylaxis. Patient's immune status, drug combination, rituximab strategy should be fully evaluated when considering antiviral prophylaxis therapy.

Mannose-Binding Lectin Deposition in Membranous Nephropathy and Differentiation of Primary from Secondary Forms.

The differentiation between primary and secondary forms of membranous nephropathy (MN) is a cornerstone that is necessary for adequate decision making regarding the treatment options and behavior of each specific case. Kidney biopsy and antibody results can be controversial, and a unique biomarker has still not been found. BACKGROUND AND OBJECTIVES: We investigated the lack of mannose-binding lectin (MBL) deposition in patients with secondary MNs (sMNs) with the presence of IgG4 deposition in relation to the presence of MBL deposition in patients with primary MNs (pMNs). We also established a connection between the stage of MN and MBL deposition. MATERIALS AND METHODS: Materials from 72 renal biopsies with proven MN were used for immunohistochemistry staining (IHC) for the phospholipase A2 receptor (PLA2R), immunoglobulin subtype IgG4, and MBL. Patients were separated into one of the following three groups: primary MN (pMN), idiopathic MN (iMN), and secondary MN (sMN). Serum antibodies for PLA2R and thrombospondin type-I-domain-containing 7A (THSD7A) were also used for the precise evaluation of the type of MN, as well as for detecting positivity for PLA2R using IHC. Which stage of MN was present in relation to the deposition of MBL was evaluated. RESULTS: In total, 50 patients were positive for IgG4, 34 with pMN, 12 with iMN, and 4 with sMN. A total of 20 patients were positive for MBL, 14 with pMN and 6 with iMN; no MBL deposits were found in patients with sMN. MBL positivity was predominantly present in the first two stages of MN, with a gradual reduction in the later stages. CONCLUSIONS: The activation of the lectin-complement pathway occurs in the early stages of the disease and is associated with the deposition of IgG4; IgG4 deposition is present in sMN, but there is no MBL deposition. IgG4 cannot be used for the differentiation of primary from secondary MNs, but the lack of MBL can be used as a marker for sMN in the early stages of the disease.

A review of progress on complement and primary membranous nephropathy.

Primary membranous nephropathy (PMN) is a predominant cause of adult nephrotic syndrome, with its incidence witnessing a progressive surge over time. Approximately 35% to 47% of patients progress to renal failure within 10 years, causing a huge social burden. Within China, the proportion of PMN in primary glomerular disease exhibits a gradual ascension. Recent studies have shown that the 3 activation pathways of complement: the classical pathway, mannose-binding lectin pathway, and alternative pathway, are all involved in the pathogenesis of PMN. Despite historical limitations in detecting C1q deposits on the glomeruli of PMN in the past, recent studies have confirmed the classical pathway is implicated in patients with PMN. Considering the dysregulation of the complement system has been observed in PMN, complement inhibitors become increasingly promising. Several clinical trials are presently underway to evaluate the efficacy of complement inhibitors, such as MASP2 antagonists (OMS721), C3 and C3b antagonists (APL2), FD inhibitors (BCX9930), C3aR antagonists (SB290157 and JR14a), FB inhibitors (LNP023). This article reviews the recent research progress on the role of the complement pathway in the pathogenesis of PMN, and underscores the importance of continued research into the complement pathway and its inhibitors, which may pave the way for groundbreaking advancements in the management of PMN.

Overlap of membranous nephropathy and IgA nephropathy in a patient with Kimura's disease: a case report and literature review.

Introduction: Kimura's disease (KD) is a rare chronic inflammatory disorder characterized by subcutaneous lymphoid hyperplasia with peripheral eosinophilia. Kidney involvement is reported in 15%-18% of adult patients with KD, in many cases as nephrotic syndrome. We present a case of overlapping membranous nephropathy and IgA nephropathy associated with KD. Case report: A 27-year-old man was admitted with a history of bilateral leg edema for the last 2 months and concomitant progressive increase of cervical mass and fever. Laboratory findings were as follows: peripheral leukocyte count, 10,080/mm³; eosinophils, 3,200/mm³ (31.7%); serum creatinine, 0.83 mg/dL; and eGFR: 140 mL/min per 1.73 m2. Urinalysis revealed the presence of hematuria and proteinuria and the following results: 24-h proteinuria, 12.9 g; serum albumin, 1.3 g/dL; and elevated IgE level, 750 kU/L. Serologies for hepatitis B, hepatitis C, HIV, and VDRL were all negative. Complement C3 and C4 levels were normal. No monoclonal protein was detected in blood and urine. Parasite infestation was discarded. A biopsy of the cervical lymph node revealed eosinophilic lymphoid hyperplasia, suggesting KD. A kidney biopsy revealed findings consistent with the overlapping of membranous nephropathy with IgA nephropathy. The patient was treated for KD with prednisone 1 mg/kg/d with progressive dose tapering and posterior association of methotrexate 15 mg/week. A renin-angiotensin system inhibitor was prescribed for nephrotic syndrome. The cervical mass regressed, and proteinuria achieved partial remission, with an increase in serum albumin level and normalization of eosinophils and IgE levels. Conclusion: Although uncommon, kidney involvement must be considered in patients with KD. Glomerular diseases are the most frequent form of kidney injury.

Identification and validation of biomarkers in membranous nephropathy and pan-cancer analysis.

Background: Membranous nephropathy (MN) is an autoimmune disease and represents the most prevalent type of renal pathology in adult patients afflicted with nephrotic syndrome. Despite substantial evidence suggesting a possible link between MN and cancer, the precise underlying mechanisms remain elusive. Methods: In this study, we acquired and integrated two MN datasets (comprising a single-cell dataset and a bulk RNA-seq dataset) from the Gene Expression Omnibus database for differential expression gene (DEG) analysis, hub genes were obtained by LASSO and random forest algorithms, the diagnostic ability of hub genes was assessed using ROC curves, and the degree of immune cell infiltration was evaluated using the ssGSEA function. Concurrently, we gathered pan-cancer-related genes from the TCGA and GTEx databases, to analyze the expression, mutation status, drug sensitivity and prognosis of hub genes in pan-cancer. Results: We conducted intersections between the set of 318 senescence-related genes and the 366 DEGs, resulting in the identification of 13 senescence-related DEGs. Afterwards, we meticulously analyzed these genes using the LASSO and random forest algorithms, which ultimately led to the discovery of six hub genes through intersection (PIK3R1, CCND1, TERF2IP, SLC25A4, CAPN2, and TXN). ROC curves suggest that these hub genes have good recognition of MN. After performing correlation analysis, examining immune infiltration, and conducting a comprehensive pan-cancer investigation, we validated these six hub genes through immunohistochemical analysis using human renal biopsy tissues. The pan-cancer analysis notably accentuates the robust association between these hub genes and the prognoses of individuals afflicted by diverse cancer types, further underscoring the importance of mutations within these hub genes across various cancers. Conclusion: This evidence indicates that these genes could potentially play a pivotal role as a critical link connecting MN and cancer. As a result, they may hold promise as valuable targets for intervention in cases of both MN and cancer.

Diagnosis of membranous nephropathy with Anti-GBM glomerulonephritis: a case series report.

BACKGROUND: The concomitant occurrence of membranous nephropathy and anti-glomerular basement (anti-GBM) disease has been previously described but is extremely rare. However, delayed recognition or misdiagnosis leads to delayed treatment, resulting in worse renal and patient outcomes. CASE PRESENTATION: We present 3 patients with rapidly progressive glomerulonephritis (RPGN), anti-GBM and serum-positive M-type phospholipase A2 receptor (anti-PLA2R) antibody. Renal biopsies revealed PLA2R-associated membranous nephropathy with anti-GBM glomerulonephritis. We analyzed the clinical and pathological characteristics and discussed that the correct diagnosis of membranous nephropathy with anti-GBM should rely on a combination of renal biopsy findings and serological testing. Despite aggressive treatment, one patient received maintenance hemodialysis, one patient progressed to CKD 3 stage, and the other patient died of cerebral infarction. CONCLUSION: The simultaneous occurrence of membranous nephropathy and anti-GBM disease is extremely rare. The correct diagnosis of membranous nephropathy with anti-GBM relies on a combination of renal biopsy findings and serological testing. Early diagnosis is needed to improve the renal dysfunction.

[Diagnostic significance of C4d in membranous nephropathy]. / Importancia diagnóstica del C4d en la nefropatía membranosa.

INTRODUCTION: Membranous nephropathy (MN) is the most common cause of primary nephrotic syndrome in adults (20-30%). Light microscopy shows thickening of glomerular basement membrane with appearance of spikes. These histological findings are not evident in early forms, in which case the granular deposition pattern of IgG and/or C3 in the basement membrane by immunofluorescence (IF) constitutes the diagnostic tool that allows to differentiate it from minimal change disease (MCD). Complement system plays a key role in the pathophysiology of MN. C4d is a degradation product and a marker of the complement system activation. C4d labelling by immunohistochemical (HI) technique can help in the differential diagnosis between both glomerulopathies NM and MCD when the material for IF is insufficient and light microscopy is normal. Our objective was to explore the discrimination power of C4d to differentiate between MN and MCD in renal biopsy material. METHODS: Paraffin-embedded samples were recovered from renal biopsies with a diagnosis of MN and MCD performed between 1/1/2008 and 4/1/2019. IH staining was performed by immunoperoxidase technique using a rabbit anti-human C4d polyclonal antibody. RESULTS: In all cases with MN (n = 27, 15 males) with a median age of 63 (range: 18-87) years, C4d deposits were detected. In 21 cases with MCD (12 males) with a median age of 51 (range: 18-87) years, the C4d marking was negative in every samples. CONCLUSION: The results indicate that the marking of the renal biopsy with C4d is a useful tool for the differential diagnosis between NM and MCD.

Introducción: La nefropatía membranosa (NM) es la causa más frecuente de síndrome nefrótico primario en adultos (20-30%). En la microscopia óptica se observa engrosamiento de membrana basal glomerular con aparición de espigas. Estos hallazgos histológicos no son evidentes en formas tempranas, en cuyo caso el patrón de depósito granular de IgG y/o C3 en la membrana basal por inmunofluorescencia (IF) permite diferenciarla de enfermedad por cambios mínimos (ECM). El sistema del complemento juega un papel central en la fisiopatología de la NM. C4d es producto de degradación y un marcador de la activación del complemento. La marcación con C4d en muestras de biopsias renales, por técnica de inmunohistoquímica (IH) puede colaborar en el diagnóstico diferencial entre ambas glomerulopatías. Nuestro objetivo fue explorar el poder de discriminación del C4d para diferenciar NM de ECM en material de biopsias renales. Métodos: Se recuperaron muestras en parafina de biopsias renales con diagnóstico de NM y ECM realizados entre 1/1/2008 y 1/4/2019. Se realizaron tinciones de IH por técnica de inmunoperoxidasa con C4d usando un anticuerpo policlonal antihumano de conejo. Resultados: En todos los casos con NM (n = 27, 15 hombres) con mediana de edad de 63 (rango: 18-86) años se detectaron depósitos de C4d. En los 21 casos con ECM (12 hombres) con mediana de edad de 51 (rango: 18-87) años la marcación de C4d fue negativa. Conclusión: Los resultados indican que la marcación de la biopsia renal con C4d es una herramienta útil para el diagnóstico diferencial entre NM y ECM.

Macrocarpal B blocks the binding between the phospholipase A2 receptor and its antibodies.

The pathogenic role of anti-phospholipase A2 receptor (PLA2R) antibodies in primary membranous nephropathy (MN) has been well-established. This study aimed to identify potential small-molecule inhibitors against the PLA2R-antibody interaction, offering potential therapeutic benefits. A comprehensive screening of over 4000 small-molecule compounds was conducted by ELISA to assess their inhibitory effects on the binding between the immobilized full-length extracellular PLA2R and its antibodies. The affinity of anti-PLA2R IgG from MN patients and the inhibitory efficacy of each compound were evaluated via surface plasmon resonance (SPR). Human podocyte injuries were analyzed using CCK-8 assay, wound healing assay, western blot analysis, and immunofluorescence, after exposure to MN plasma +/- blocking compound. Fifteen compounds were identified as potential inhibitors, demonstrating inhibition rates >20 % for the PLA2R-antibody interaction. Anti-PLA2R IgG exhibited a consistent affinity among patients (KD = 10-8 M). Macrocarpal B emerged as the most potent inhibitor, reducing the antigen-antibody interaction by nearly 30 % in a dose-dependent manner, comparable to the performance of the 31-mer peptide from the CysR domain. Macrocarpal B bound to the immobilized PLA2R with an affinity of 1.47 × 10-6 M, while showing no binding to anti-PLA2R IgG. Human podocytes exposed to MN plasma showed decreased podocin expression, impaired migration function, and reduced cell viability. Macrocarpal B inhibited the binding of anti-PLA2R IgG to podocytes and reduced the cellular injuries.

Can we effectively manage chronic kidney disease with a precision-based pharmacotherapy plan? Where are we?

INTRODUCTION: In recent years, thanks to significant advances in basic science and biotechnologies, nephrology has witnessed a deeper understanding of the mechanisms leading to various conditions associated with or causing kidney disease, opening new perspectives for developing specific treatments. These new possibilities have brought increased challenges to physicians, who face with a new complexity in disease characterization and selection the right treatment for individual patients. AREAS COVERED: We chose four therapeutic situations: anaemia in chronic kidney disease (CKD), heart failure in CKD, IgA nephropathy (IgAN) and membranous nephropathy (MN). The literature search was made through PubMed. EXPERT OPINION: Anaemia management remains challenging in CKD; a personalized therapeutic approach is often needed. Identifying patients who could benefit from a specific therapy is also an important goal for patients with CKD and heart failure with reduced ejection fraction. Several new treatments are under clinical development for IgAN; interestingly, they target specifically the pathogenetic mechanisms of the disease. The understanding of MN pathogenesis as an autoimmune disease and the discovery of several autoantibodies allows a better characterization of patients. High-sensible techniques for lymphocyte counting open the possibility of more personalized use of anti CD20 therapies.

Serum Phospholipase A2 Receptor Antibody Is Associated with Thrombogenesis in Patients with Idiopathic Membranous Nephropathy.

INTRODUCTION: Patients with idiopathic membranous nephropathy (IMN) are particularly susceptible to thromboembolism (TE). The phospholipase A2 receptor (PLA2R) antibody (Ab) has been indicated to work as an independent risk predictor for venous TE in IMN. This study aimed to further explore the predictive value of PLA2R Ab for both venous and arterial TE in IMN patients. METHODS: A total of 91 IMN patients were retrospectively selected and divided into anti-PLA2R-positive or anti-PLA2R-negative groups according to the anti-PLA2R Ab titer (cutoff: 20 RU/mL). Serum PLA2R Abs were estimated using ELISA. Anti-PLA2R-positive IMN patients were further assigned into two groups based on the presence or absence of TE. RESULTS: Twelve (18.18%) IMN patients with anti-PLA2R positivity had TE, including both venous and arterial TE. No TE occurred in the anti-PLA2R-negative group. IMN patients in the anti-PLA2R-positive group had significantly higher levels of total cholesterol and low-density lipoprotein than those in the anti-PLA2R-negative group. No significant difference was observed in the anti-PLA2R Ab titer between patients with and without TE. Patients with TE were significantly older than those without TE. CONCLUSION: This study demonstrates that the positive status of anti-PLA2R Abs contributes to thrombosis formation in IMN.