M-type Phospholipase A2 Receptor Research Articles

Fibrinogen-albumin ratio predicts treatment response in phospholipase A2 receptor-associated membranous nephropathy with nephrotic syndrome

Background The M-type phospholipase A2 receptor (PLA2R)-associated primary membranous nephropathy (PMN) is an immune-related disease in adults with increasing morbidity and variable treatment response, in which inflammation may contribute to the multifactorial immunopathogenesis. The relationship between fibrinogen-albumin ratio (FAR), serving as a novel inflammatory biomarker, and PMN is still unclear. Therefore, this study aims to clarify the association between FAR and disease activity and therapy response of PMN. Methods 110 biopsy-proven phospholipase A2 receptor (PLA2R) -associated PMN participants with nephrotic syndrome from January 2017 to December 2021 were recruited in the First Affiliated Hospital of Nanjing Medical University. The independent risk factors of non-remission (NR) and the predictive ability of FAR were explored by Cox regression and receiver-operating characteristic (ROC) curve analysis. According to the optimal cutoff value, study patients were categorized into the low-FAR group (≤the cutoff value) and the high-FAR group (>the cutoff value). Spearman’s correlations were used to examine the associations between FAR and baseline clinicopathological characteristics. Kaplan-Meier method was used to assess the effects of FAR on remission. Results In the entire study cohort, 78 (70.9%) patients reached complete or partial remission (CR or PR). The optimal cutoff value of FAR for predicting the remission outcome (CR + PR) was 0.233. The Kaplan-Meier survival analysis demonstrated that the high-FAR group (>0.233) had a significantly lower probability to achieve CR or PR compared to the low-FAR group (≤0.233) (Log Rank test, p = 0.021). Higher levels of FAR were identified as an independent risk factor for NR, and the high-FAR group was associated with a 2.27 times higher likelihood of NR than the low-FAR group (HR 2.27, 95% CI 1.01, 5.13, p = 0.048). These relationships remained robust with further analysis among calcineurin inhibitors (CNIs)-receivers. In the multivariate Cox regression model, the incidence of NR was 4.00 times higher in the high-FAR group than in the low-FAR group (HR 4.00, 95% CI 1.41, 11.31, p = 0.009). Moreover, ROC analysis revealed the predictive value of FAR for CR or PR with a 0.738 area under curve (AUC), and the AUC of anti-PLA2R Ab was 0.675. When combining FAR and anti-PLA2R Ab, the AUC was boosted to 0.766. Conclusions FAR was significantly correlated with proteinuria and anti-PLA2R Ab in PMN. As an independent risk factor for NR, FAR might serve as a potential inflammation-based prognostic tool for identifying cases with poor treatment response, and the best predictive cutoff value for outcomes was 0.233.

Predictive value of the domain specific PLA2R antibodies for clinical remission in patients with primary membranous nephropathy: A retrospective study.

M-type phospholipase A2 receptor (PLA2R) is a major auto-antigen of primary membranous nephropathy(PMN). Anti-PLA2R antibody levels are closely associated with disease severity and therapeutic effectiveness. Analysis of PLA2R antigen epitope reactivity may have a greater predictive value for remission compared with total PLA2R-antibody level. This study aims to elucidate the relationship between domain-specific antibody levels and clinical outcomes of PMN. This retrospective analysis included 87 patients with PLA2R-associated PMN. Among them, 40 and 47 were treated with rituximab (RTX) and cyclophosphamide (CTX) regimen, respectively. The quantitative detection of -immunoglobulin G (IgG)/-IgG4 targeting PLA2R and its epitope levels in the serum of patients with PMN were obtained through time-resolved fluorescence immunoassays and served as biomarkers in evaluating the treatment effectiveness. A predictive PMN remission possibility nomogram was developed using multivariate logistic regression analysis. Discrimination in the prediction model was assessed using the area under the receiver operating characteristic curve (AUC-ROC).Bootstrap ROC was used to evaluate the performance of the prediction model. After a 6-month treatment period, the remission rates of proteinuria, including complete remission and partial remission in the RTX and CTX groups, were 70% and 70.21% (P = 0.983), respectively. However, there was a significant difference in immunological remission in the PLA2R-IgG4 between the RTX and CTX groups (21.43% vs. 61.90%, P = 0.019). Furthermore, we found differences in PLA2R-CysR-IgG4(P = 0.030), PLA2R-CTLD1-IgG4(P = 0.005), PLA2R-CTLD678-IgG4(P = 0.003), and epitope spreading (P = 0.023) between responders and non-responders in the CTX group. Multivariate logistic analysis showed that higher levels of urinary protein (odds ratio [OR], 0.49; 95% confidence interval [CI], 0.26-0.95; P = 0.035) and higher levels of PLA2R-CTLD1-IgG4 (OR, 0.79; 95%CI,0.62-0.99; P = 0.041) were independent risk factors for early remission. A multivariate model for estimating the possibility of early remission in patients with PMN is presented as a nomogram. The AUC-ROC of our model was 0.721 (95%CI, 0.601-0.840), in consistency with the results obtained with internal validation, for which the AUC-ROC was 0.711 (95%CI, 0.587-0.824), thus, demonstrating robustness. Cyclophosphamide can induce immunological remission earlier than rituximab at the span of 6 months. The PLA2R-CTLD1-IgG4 has a better predict value than total PLA2R-IgG for remission of proteinuria at the 6th month.

Traditional Chinese medicine for idiopathic membranous nephropathy: A systematic review and meta-analysis

BackgroundIdiopathic membranous nephropathy (IMN) is a rare autoimmune disorder that causes nephrotic syndromes in adults. Conventional immunosuppressive therapies often exhibit limited efficacy in achieving remission and may result in notable adverse reactions, warranting the exploration of novel therapeutic approaches for IMN treatment. Traditional Chinese medicine (TCM), which is extensively used for kidney disease management, is a promising alternative. ObjectiveThis study aimed to examine the safety and efficacy of TCM alone or in combination with Western medicine for the management of patients diagnosed with IMN. MethodsThis study employed a systematic search of English and Chinese electronic databases to identify randomized controlled trials (RCTs) that examined the application of TCM in the treatment of IMN. RCTs that met the predetermined inclusion and exclusion criteria and assessed the safety and efficacy of TCM alone or in combination with Western medicine in patients with IMN were included in the analysis. The methodological quality of the included studies was evaluated by using a risk-of-bias tool. All statistical analyses were performed using the RevMan software (version 5.4.2). The evidence was evaluated on the https://www.gradepro.org/website. ResultsThis study included 29 randomized controlled trials (RCTs) involving 1982 patients with moderate methodological quality that met the inclusion criteria. The results showed that, compared to Western medicine alone therapy, the use of TCM alone or in combination with Western medicine significantly improved total remission (TR) rate (risk ratios [RR] 1.38, 95% confidence interval [CI] 1.29–1.46, I2 = 0%, P < 0.00001), complete remission (CR) rate (RR 1.78, 95% CI 1.48–2.15, I2 = 0, P < 0.00001), partial remission (PR) rate (RR 1.27, 95% CI 1.161.40, I2 = 0%, P < 0.00001), and serum albumin (ALB) levels (MD: 4.05, 95% CI: 3.02–5.09, I2 = 91%, P < 0.00001). TCM alone or in combination with Western medicine also reduced proteinuria levels (mean difference [MD]: 1.05, 95% CI: 1.30 to −0.79, I2 = 95%, P < 0.00001), serum creatinine (SCr) levels (MD: 7.47, 95% CI: 13.70 to −1.24, I2 = 97%, P = 0.02), and serum antibodies against M-type phospholipase A2 receptor levels (aPLA2Rab) (MD: 19.24, 95% CI: 33.56 to −4.93, I2 = 87%, P = 0.008). Moreover, the efficacy of combined TCM and Western medicine is superior to that of Western medicine alone in reducing the incidence of infection, hepatotoxicity, and thrombosis. Although the primary and secondary outcomes were consistent, the evidence was generally moderate. ConclusionThe results of this study suggest that TCM alone or in combination with Western medicine may be a feasible alternative therapeutic approach for the treatment of IMN. Nevertheless, additional, rigorously designed, high-quality, and extensive clinical trials are imperative to provide substantial evidence regarding the effectiveness of TCM in managing IMN.

Quantitative detection and prognostic value of antibodies against M-type phospholipase A2 receptor and its cysteine-rich ricin domain and C-type lectin domains 1 and 6-7-8 in patients with idiopathic membranous nephropathy.

M-type phospholipase A2 receptor (PLA2R) is the major autoantigen in adult idiopathic membranous nephropathy (IMN). Although reactive epitopes in the PLA2R domains have been identified, the clinical value of these domains recognized by anti-PLA2R antibodies remains controversial. Accordingly, this study aimed to quantitatively detect changes in the concentrations of different antibodies against epitopes of PLA2R in patients with IMN before and after treatment to evaluate the clinical value of epitope spreading. Highly sensitive time-resolved fluorescence immunoassay was used to quantitatively analyze the concentrations of specific IgG and IgG4 antibodies against PLA2R and its epitopes (CysR, CTLD1, CTLD6-7-8) in a cohort of 25 patients with PLA2R-associated membranous nephropathy (13 and 12 in the remission and non-remission groups, respectively) before and after treatment, and the results were analyzed in conjunction with clinical biochemical indicators. The concentration of specific IgG (IgG4) antibodies against PLA2R and its epitopes (CysR, CTLD1 and CTLD6-7-8) in non-remission group was higher than that in remission group. The multipliers of elevation of IgG (IgG4) antibody were 5.6(6.2) fold, 3.0(24.3) fold, 1.6(9.0) fold, and 4.2(2.6) fold in the non-remission/remission group, respectively. However, the difference in antibody concentrations between the two groups at the end of follow-up was 5.6 (85.2), 1.7 (13.1), 1.0 (5.1), and 1.5 (22.3) times higher, respectively. When detecting concentrations of specific IgG antibodies against PLA2R and its different epitopes, the remission rate was 66.67% for only one epitope at M0 and 36.36% for three epitopes at M0. When detecting concentrations of specific IgG4 antibodies against PLA2R and its different epitopes, the remission rate was 100.00% for only one epitope at M0 and 50.00% for three epitopes at M0. A trivariate logistic regression model for the combined detection of eGFR, anti-CTLD678 IgG4, and urinary protein had an AUC of 100.00%. Low concentrations of anti-CysR-IgG4, anti-CTLD1-IgG4, and anti-CTLD6-7-8-IgG4 at initial diagnosis predict rapid remission after treatment. The use of specific IgG4 against PLA2R and its different epitopes combined with eGFR and urinary protein provides a better assessment of the prognostic outcome of IMN.

Clinical significance of exostosin 1 in confirmed and suspected lupus membranous nephropathy

ObjectiveThis study aimed to investigate the clinical significance of exostosin 1 (EXT1) in confirmed and suspected lupus membranous nephropathy (LMN).MethodsEXT1 was detected in 67 renal tissues of M-type phospholipase A2...

Association of M-Type Phospholipase A2 Receptor Deposition in Kidney Tissue with Treatment Outcomes in Patients with Idiopathic Membranous Nephropathy.

The purpose of this study was to investigate the correlation between the deposition of M-type phospholipase A2 receptor (PLA2R) in the kidney tissues of patients with idiopathic membranous nephropathy (IMN). We enrolled a total of 61 patients diagnosed with IMN in the past 8 years who were admitted at the Jinjiang Municipal Hospital and the 2nd Affiliated Hospital of Fujian Medical University. PLA2R immunofluorescence was used to stain kidney tissues, and all patients were treated with steroid combined with immunosuppressive agents or conservative regimens. The duration of follow-up was more than 48 weeks. Based on the deposition of PLA2R in kidney tissues, we divided the patients into the PLA2R Positive group and the PLA2R Negative group. Further, patients with PLA2R-positive kidney tissues were divided into "1+", "2+", and "3+" groups based on the extent of their PLA2R deposition, and we compared the therapeutic outcomes of the various groups. At week 12 of follow-up, the partial remission rate of kidney tissues in the PLA2R Negative group was significantly higher than that in the Positive group (P = 0.004). Among the various deposition groups with PLA2R-positive kidney tissues, the complete remission rate of the "2+" group was higher than that of the "3+" group at weeks 24, 36, and 48 of follow-up (P < 0.05). In IMN patients treated with a combination regimen of steroid and tacrolimus, the complete remission rate in kidney tissues of the PLA2R Negative group was higher than that of the Positive group at weeks 24 and 48 of follow-up (P < 0.05). The overall effective rate of treatment in kidney tissues of PLA2R-negative patients was higher than that in the kidney tissues of PLA2R-positive patients. The varied levels of PLA2R deposition in kidney tissues were related to the treatment outcomes of IMN, and those with lower PLA2R deposition levels had better outcomes.

Клиническое значение антител к рецептору фосфолипазы А2 М-типа у пациентов с первичной мембранозной нефропатией

To evaluate the significance of circulating antibodies to the M-type phospholipase A2 receptor (anti-PLA2R) in the diagnosis of primary membranous nephropathy (MN) and the determination of the clinical features of the disease.

The application of podocyte antigen PLA2R and anti-PLA2R antibody in the diagnosis and treatment of membranous nephropathy

Background The application of podocyte antigen M-type phospholipase A2 receptor (PLA2R, GAg) and serum anti-PLA2R antibody (SAb) in predicting the prognosis of membrane nephropathy (MN) was controversial. Method 328 biopsy-proven MN patients were divided into three phenotypes, 182 MN patients with GAg+/SAb+, 118 MN patients with GAg+/SAb-, and 28 MN patients with GAg-/SAb-. The baseline clinicopathological characteristics, therapy response, and prognosis were compared among the three groups. Cox regression analysis was performed to assess predictors of remission. Anti-PLA2R antibody was analyzed by receiver operating characteristic curve to find the optimal titer for MN diagnosis. Result Lower eGFR (p = 0.009), higher UPCR (p < 0.001), and lower serum albumin (p < 0.001) were observed in GAg+/SAb+ MN patients, compared to GAg+/SAb- MN patients. More GAg+/SAb+ MN patients received cyclophosphamide (CTX) combined with glucocorticoids and calcineurin inhibitors (CNI) based therapy than the other two groups (p = 0.015 and p = 0.023, respectively). No significant difference was observed among the three groups in terms of complete remission, relapse, and developing ESRD. SAb+ status was an independent predictor for no remission (hazard ratio 1.378, 95% confidence interval 1.023 to 1.855; p = 0.035). The optimal cutoff value for anti-PLA2R antibody to predict MN was 2.055 RU/mL (sensibility 0.802, specificity 0.970). Conclusion GAg+/SAb+ MN patients were related to more severe clinical manifestations and more requisition of immunosuppressive treatment. Positive anti-PLA2R antibody was an independent predictor for no remission. An anti-PLA2R antibody above 2.055 RU/mL can be a suggestive indicator of MN diagnosis in patients with proteinuria.

Diagnostic Usefulness of Antibodies Against M-type Phospholipase A2 Receptor (aPLA2R) in Primary Membranous Nephropathy in the Mexican Population.

This study aimed to determine the frequency and diagnostic performance of antibodies against M-type phospholipase A2 receptors (aPLA2R) in subjects with idiopathic membranous nephropathy (IMN). A diagnostic test study was conducted in a cohort of 160 patients from the nephrology outpatient clinic over a period of eight years. Serum samples were taken and analyzed from patients with a histological diagnosis of IMN with proteinuria greater than and less than 1 g in 24 hours and other glomerular diseases other than IMN with aPLA2R measurement by enzyme-linked immunosorbent assay (ELISA) (Euroimmun, Luebeck, Germany). In 22 of 160 patients, an aPLA2R concentration >9 RU/mL was found, and all these cases had IMN. The prevalence of seropositivity in cases with active IMN was 78% (21/27). All these correlations were statistically significant with a p<0.001. The area under the receiver operating characteristic (ROC) curve (AB-ROC) of aPLA2R was 0.87 (95%, CI: 78-0.96). The aPLA2R has adequate diagnostic usefulness to diagnose IMN in the selected population, especially in subjects with proteinuria greater than 1 gr/day, with a sensitivity of 78% and a specificity of 99%.

#4851 MOLECULAR FEATURES OF CIRCULATORY B CELLS AND RENAL CELLS AT THE SINGLE-CELL LEVEL IN AUTOANTIBODY-NEGATIVE PRIMARY MEMBRANOUS NEPHROPATHY PATIENTS

Abstract Background and Aims Primary membranous nephropathy (PMN) is an organ-specific autoimmune disease that is the most common cause of idiopathic nephrotic syndrome in adults. Furthermore, the incidence of PMN is increasing, especially in young adults and children. The landmark discovery of nephritogenic autoantibodies against podocyte antigens such as M-type phospholipase A2 receptor (PLA2R) and thrombospondin type-1 domain-containing protein 7A (THSD7A) has provided a paradigm shift in diagnosis and treatment of PMN. However, there are still few patients with negative serum and renal tissue autoantibodies. This study aims to explore the molecular features of antibody-negative PMN. Method We sorted CD19+ cells from the peripheral blood of a pediatric patient with seven nephritogenic autoantibodies-negative PMN (NEG) by flow cytometry and performed single-cell transcriptome sequencing (scRNA-seq) and single-cell B cell receptor sequencing (scBCR-seq). Meanwhile, scRNA-seq was performed on renal biopsy tissues from the same patient. In addition, we included the scRNA-seq data of renal from anti-PLA2R antibody positive patients (POS) and healthy controls (CTRL), and the scBCR-seq data of B cell from CTRL for integrative analysis. Results The NEG patient showed typical nephrotic syndrome and was diagnosed as stage Ⅲ membranous nephropathy by renal biopsy. There was no evidence of anti-PLA2R or anti-THSD7A antibodies in peripheral blood and seven nephritogenic autoantibodies such as anti-PLA2R antibodies in renal tissue. After excluding secondary factors, the patient was diagnosed with PMN. Through scRNA-seq of CD19+ cells, we found that the number, characteristic gene, function and clonotype of naÏve B cells and memory B cells in NEG were significantly changed. Expanded CD38+ naÏve B cells in NEG had the molecular characteristics of CD19+CD24+CD27-CD38+, defined as transitional B cells. This group of cells had distinct function features of cell activation, and its up-regulated genes were involved in multiple aspects of the BCR signaling pathway. Pseudotime trajectory analysis suggested CD38+ naÏve B cells were highly enriched in the beginning of B cell differentiation. There was a preference in the use of VJ gene segments of B cells between NEG and CTRL, especially an increase of the IGHV3-23 and IGLV2-14 in NEG. The stronger pairing frequencies, IGLV2-14/IGLJ3 and IGKV2D-29/IGKJ2, were indicated in NEG. We identified 14 distinct kidney cell types by marker genes. Through re-clustering of glomerular parietal epithelial cells (PECs), the patients were clearly distinct from their control counterparts, indicating a major shift in gene expression for this cell type. PECs in NEG showed significant up-regulation of cellular communication network factor-related genes (CCN1, CCN2), phospholipase A and acyltransferase-related genes (PLAAT4, PLAAT3), and septin protein-related genes (SEPTIN2, SEPTIN7), accompanied by significant down-regulation of podocyte-related genes. In addition, there are clearly distinct cellular functions and pseudotime trajectory in PECs from NEG and POS, and genes such as CCN2, PLAAT4, SEPTIN2 might drive the special trajectory of PECs in NEG. For the podocytes, the genes related with extracellular matrix and cell adhesion were significantly enhanced in NEG, which consistented with the functional enrichment analysis of the differentially expressed genes and gene set-based scores. We calculated the gene set-based scores including genes encoding lumen-to-blood sodium transporters. Results indicated the enhanced expression of sodium transporters in distal nephrons of MN patients. More surprisingly, a group of proximal tubule epithelial cells showed significantly higher expression levels of sodium transporters. Among them, the expression of SLC5A12 encoding SMCT2 increased significantly. Conclusion We have systematic revealed the cell-type specific molecular features of PMN patients from circulation to renal tissue. Our research provides valuable evidence for the molecular diagnosis of PMN in children and insights into pathogenic mechanism of classical nephritogenic autoantibody-negative PMN.

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.

Heterogeneity of Target Antigens in Sarcoidosis-Associated Membranous Nephropathy

Membranous nephropathy (MN) is the most common glomerular disease associated with sarcoidosis. The target antigen M-type phospholipase A2 receptor 1 (PLA2R) has been identified in a subset of sarcoidosis-associated MN. The target antigen is not known in the remaining sarcoidosis-associated MN. Data of patients with history of sarcoidosis and biopsy-proven MN were retrieved and analyzed. Mass spectrometry (MS/MS) was performed on all kidney biopsies of sarcoidosis-associated MN to detect the target antigens. Immunohistochemistry (IHC) studies were performed to confirm and localize the target antigens along the glomerular basement membrane (GBM). Eighteen patients with history of sarcoidosis and biopsy-proven MN were identified, of whom 3 were known to be PLA2R-negative, and in the remaining patients the target antigen was unknown. Thirteen (72%) patients were males; the median age at MN diagnosis was 54.5 years. The median proteinuria at presentation was proteinuria 9.8 g/24 h. Eight patients (44.4%) had concurrent sarcoidosis. Using MS/MS, we detected PLA2R and neural epidermal growth factor-like-1 protein (NELL1) in 7 (46.6%) and 4 (22.2%) patients, respectively. In addition, 1 case each (5.5%) was positive for thrombospondin type 1 domain-containing 7A (THSD7A), protocadherin-7 (PCDH7), and putative antigen Serpin B12. No known target antigen was detected in the remaining 4 patients (22.2%). Patients with sarcoidosis and MN exhibit heterogeneous target antigens. We identified, along with PLA2R, the presence of previously unreported antigens, including NELL1, PCDH7, and THSD7A. The incidence of the target antigens in sarcoidosis appears to mirror the overall incidence of target antigens in MN. MN in sarcoidosis may be the result of a heightened immune response and is not associated with a single target antigen.

Update on theApplication of Monoclonal Antibody Therapy in Primary Membranous Nephropathy.

When first introduced, rituximab (RTX), a chimeric anti-CD20 monoclonal antibody, brought about an alternative therapeutic paradigm for primary membranous nephropathy (PMN). Rituximab was shown to be effective and safe in PMN patients with kidney dysfunction, with. patients receiving second-line rituximab therapy achievingremission as effectively as those patients who had not previously received immunotherapy. No safety issues were reported. TheB cell-driven protocol seems to be as efficient asthe 375 mg/m2 × 4 regimen or 1 g × 2 regimen in achieving B cell depletion and remission, but patients with high M-type phospholipase A2 receptor(PLA2R) antibody levels may benefit from a higher dose of rituximab. While rituximab added another therapeutic option to the treatment regimen, it does have limitations as 20 to 40% of patients do not respond. Not all patients respond to RTX therapy for lymphoproliferative disorders either, therefore further novel anti-CD20 monoclonal antibodies have been developed and these may provide alternative therapeutic options for PMN. Ofatumumab, a fully human monoclonal antibody, specifically recognizes an epitope encompassing both the small and large extracellular loops of the CD20 molecule, resulting in increased complement-dependent cytotoxic activity. Ocrelizumab binds an alternative but overlapping epitope region to rituximab and displays enhanced antibody-dependent cellular cytotoxic (ADCC) activities. Obinutuzumab is designed to have a modified elbow-hinge amino acid sequence, leading to increased direct cell death induction and ADCC activities. In PMN clinical studies, ocrelizumab and obinutuzumab showed promising results, while ofatumumab displayed mixed results. However, there is a lack of randomized controlled trials with large samples, especially direct head-to-head comparisons. Alternative molecular mechanisms have been suggested in this context to explore novel therapeutic strategies. B cell activator-targeted, plasma cell-targeted and complement-directed treatments may lead to novel therapy paradigms for PMN. Exploratory strategies for the use of drugs with different mechanisms, such as a combinationof rituximab and cyclophosphamide and a steroid, a combination of rituximab anda calcineurin inhibitor, may provide more rapid and efficient remission, but the combination of standard immunosuppression with rituximab could increase infection risk.

Preliminary study on the efficacy of rituximab in the treatment of idiopathic membranous nephropathy: A single-centre experience.

To investigate the efficacy of rituximab in the treatment of idiopathic membranous nephropathy (IMN). A total of 77 patients with IMN diagnosed in both our hospital and other hospitals were included in this study; the patients were divided into two groups: a treatment-naïve group (n = 19) and a refractory/relapsed group (n = 58). The clinical data of the patients, including urine examination, blood test, safety evaluation and efficacy evaluation results, were analysed retrospectively. The changes in clinical biochemical indexes and adverse reactions were compared between the two groups before and after treatment, and the clinical efficacy of rituximab (RTX) in the treatment of primary IMN and refractory recurrent membranous nephropathy was evaluated. Of the 77 patients included in this study, the average age was 48 years, and there was a male-to-female ratio of 61:16. There were 19 cases in the initial treatment group and 58 cases in the refractory/relapse group. The 24-hour urine protein quantification, cholesterol, B cell count and M-type phospholipase A2 receptor (PLA2R) results in the 77 patients with IMN after treatment were all lower than those before treatment, and the differences were statistically significant (P < 0.05). Serum albumin was higher than before treatment, and the difference was statistically significant (P < 0.05). The total remission rate in the initial and refractory/relapsed treatment groups was 84.21% and 82.76%, respectively. There was no statistical difference in the total remission rate between the two groups (P > 0.05). During treatment, nine patients (11.69%) experienced infusion-related adverse reactions, which were relieved rapidly after symptomatic treatment. The anti-PLA2R antibody titre of the refractory/relapsed group was significantly negatively correlated with serum creatinine (r = -0.187, P = 0.045) and significantly correlated with 24-hour urine protein (r = -0.490, P < 0.001). There was a positive correlation and a significant negative correlation with serum albumin (r = -0.558, P < 0.001). Regardless of whether RTX is used as an initial therapy or refractory/relapsed membranous nephropathy, most patients with IMN have complete or partial remission after RTX treatment, with mild adverse reactions.

HBx-induced PLA2R overexpression mediates podocyte pyroptosis through the ROS-NLRP3 signaling pathway

Introduction Hepatitis B virus-associated glomerulonephritis (HBV-GN) is one of the main types of secondary glomerular diseases, and podocyte injury is an important pathogenic mechanism of HBV-GN, participating in the occurrence and development of HBV-GN. However, the specific mechanism of podocyte injury remains to be studied. Methods Human renal podocytes cultured in vitro were divided into six groups. The podocyte morphology was observed under a transmission electron microscope, and the expression of M-type phospholipase A2 receptor (M-PLA2R) on the podocyte membrane was observed by indirect immunofluorescence staining under a fluorescence microscope. The pyroptosis rate and reactive oxygen species (ROS) of podocytes were assessed by FLICA/PI double staining and flow cytometry. Western blot (WB) and quantitative real-time PCR (qPCR) were used to determine the expression of PLA2R, nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3), apoptosis-associated speck-like protein containing card (ASC), caspase-1, IL-1β, and IL-18. Results Hepatitis B virus X (HBx) transfected into human renal podocytes in vitro induced the overexpression of PLA2R. Moreover, the overexpressed PLA2R combined with secretory phospholipase A2 group IB (sPLA2-IB) aggravated podocyte injury and increased the pyroptosis rate. In addition, the expression of ROS, the NLRP3 inflammasome and downstream inflammatory factors was increased. In contrast, after inhibiting the expression of PLA2R and ROS, podocyte damage was alleviated, and the pyroptosis rate and the expression of genes related to the ROS-NLRP3 signaling pathway were decreased. Conclusion HBx-induced PLA2R overexpression on the podocyte membrane can significantly upregulate the ROS-NLRP3 signaling pathway, thereby mediating podocyte pyroptosis.

Phospholipase A2 Receptor Antibodies and Clinical Prognosis in Patients with Idiopathic Membranous Nephropathy: An Updated Systematic Review and Meta-Analysis

Background: Idiopathic membranous nephropathy (IMN) is the most common form of primary nephrotic syndrome in adults. Antibodies against the M-type phospholipase A2 receptor (PLA2R-ab) are considered as diagnostic biomarkers of IMN. Objective: Here, we performed an updated meta-analysis to assess the diagnostic value of PLA2R-ab for clinical remission in IMN patients. Method: PubMed, Embase, and Cochrane databases were searched for relevant studies published before September 2022. Odds ratios and corresponding 95% confidence intervals were determined using a fixed or random effects model. The heterogeneity among studies was explored by subgroup analysis. Results: Sixteen studies involving 1,761 IMN participants were included. There were significant differences between PLA2R-ab (+) and PLA2R-ab (−) patients in terms of complete remission (CR) and spontaneous remission. The rates of partial remission (PR) and relapse were similar between the two groups. Patients with PLA2R-ab (−) were at a higher CR rate when treated with a calcineurin inhibitor or a treatment course for 3 months and 6 months, while the spontaneous remission rate was higher in PLA2R-ab seronegative patients from Asia. However, the CR and spontaneous remission rate only significantly declined in IMN patients with the highest titer, but not a middle titer, when compared to those with the lowest titer. Conclusion: In contrast with previous meta-analyses, our results verified that PLA2R-ab can likely predict CR and spontaneous remission in IMN patients, instead of PR and relapse. Race, immunosuppressive agents, and duration of treatment may affect the prognostic value of PLA2R-ab. Considering that the remission rate of IMN patients with a middle level of PLA2R-ab was not different from that of patients with the lowest level, a proper cut-off value of PLA2R-ab for prognosis should be clarified.

Utility of serum anti-phospholipase A2 receptor antibody as a biomarker in membranous nephropathy: An experience from a tertiary care center of Eastern India

Membranous nephropathy (MN) is a pattern of glomerular injury. Exact categorization into primary membranous nephropathy (PMN) or secondary membranous nephropathy (SMN) is essential for treatment. An endogenous podocyte antigen, M-type phospholipase A2 receptor (PLA2R) has been discovered to be involved in the pathogenesis of PMN. In this article, we aimed to analyze renal tissue PLA2R and serum anti-PLA2R antibodies in MN cases and determined the diagnostic utility. The study was of prospective type carried out from March 2019 to August 2020. Analysis of cases of MN was performed with PLA2R paraffin immunoflourescence and serum anti-PLA2R antibody ELISA. Overall sensitivity, specificity, PPV, and NPV of serum anti-PLA2R ELISA for PMN was 91.3%, 80%, 75%, and 93.3%, respectively, and of tissue PLA2R staining for PMN was 91.67%, 81.08%, 75.86%, and 93.75%, respectively. There was strong concordance between two methods. In the patients that were followed up, we found baseline serum anti-PLA2R antibody was less in complete remission group than that in non-remission group and the reduction in serum anti-PLA2R antibody was more in complete remission group than that in non-remission group. Routine light and immunofluorescence examination are incapable of giving exact categorical opinion regarding PMN and SMN. Serum anti-PLA2R antibody detection and renal tissue PLA2R analysis are sensitive and specific in detecting PMN. Baseline serum anti-PLA2R antibody and anti-PLA2R antibody quantification trends are related to prognosis of PMN. So they can be incorporated as additional biomarker.

Segmental Membranous Glomerulopathy in Adults

Introduction: The clinicopathological features of segmental membranous glomerulopathy (SMGN) have not been well characterized. The aim of this study was to investigate the prevalence and clinicopathological features of SMGN in adults. Methods: Adult patients with biopsy-confirmed SMGN in the native kidney at our center between January 2017 to September 2020 were identified. The clinicopathological features of SMGN were collected. The glomerular deposition of IgG subclasses, M-type phospholipase A2 receptor 1 (PLA2R), thrombospondin type 1 domain-containing 7A (THSD7A), and neural epidermal growth factor-like 1 protein (NELL1) were tested. Clinical and pathologic features were comparable between NELL1-positive and NELL1-negative SMGN. Results: A total of 167 patients with biopsy-proven SMGN were enrolled. During the same period, 32,640 (33.0%) out of 98,939 renal biopsies were diagnosed with membranous nephropathy (MN) in adults. SMGN accounted for 0.17% of total kidney biopsies and 0.51% of MN in adults. One hundred and fifty (89.8%) cases were isolated SMGN, and 17 (10.2%) cases were complicated with other kidney disease. Clinically, the median age of isolated SMGN patients was 41.5 years, with female (74%) predominance, and 33.1% had full nephrotic syndrome. Pathologically, IgG1 was the dominant subclass (92.5%), followed by IgG4 (45.0%). PLA2R and THSD7A staining were done in 142 and 136 isolated SMGN cases, respectively, in which, all the cases showed negative. NELL1 staining was done in 135 isolated SMGN cases; 58 cases (43.0%) showed positive. Fifty-eight patients (41.1%) had diffuse (≥90%) foot process effacement, and 119 patients (83.8%) had either stage I (38.0%) or stage II (45.8%) membranous alterations in patients with SMGN. Most patients with NELL1-positive SMGN were female. Patients with NELL1-positive SMGN were more likely with lower prevalence of full nephrotic syndrome than NELL1-negative SMGN. Conclusions: SMGN is a relatively rare pathological type. Majority of patients with isolated SMGN were female, with a median age of 41.5 years, 33.1% had full nephrotic syndrome, absence of PLA2R and THSD7A, 43.0% with NELL1-positive, and mainly stage I or II MN (83.8%). NELL1 is the major target antigen of SMGN in adults.

Disease-Specific Treatment For Primary Membranous Nephropathy: The Role of Monoclonal Antibodies

Primary Membranous Nephropathy is an autoimmune disease caused by the deposition of Immunoglobulin G and complement components on the subepithelial layer of the glomerular capillary wall. It affects 5-10 patients per million population and is the second cause of nephrotic syndrome in adults after diabetic kidney disease. For decades steroids and non-specific immunosuppressive medications have been advocated as a therapeutic option for patients with membranous nephropathy at increased risk of kidney failure because of persistent nephrotic syndrome. These medications, however, have major and potentially fatal adverse effects that offset their potential benefits and should be abandoned. The discovery of nephritogenic autoantibodies against podocyte M-type phospholipase A2 receptor (PLA2R) and thrombospondin type-1 domain-containing protein 7A (THSD7A) antigens provided a clear pathophysiological rationale for interventions specifically targeting B cell lineages to prevent antibody production and subepithelial deposition. The first-in-class anti-CD20 monoclonal antibody rituximab is safe and achieves remission in approximately two-thirds of patients with nephrotic membranous nephropathy. In PLA2R-related disease, remission is invariably preceded by depletion of anti PLA2R autoantibodies and relapse by their re-emergence into the circulation. Because of its superior risk/benefit profile as compared to non-specific immunosuppressive therapy, rituximab is now first-line therapy for patients with membranous nephropathy at risk of kidney failure. Novel monoclonal antibodies targeting CD20 cells (such as ofatumumab and obinutuzumab) and their differentiation (belimumab) or targeting long-living antibody producing CD38 memory cells (daratumumab, felzartamab) along with proteasome inhibitors such as bortezomib are being evaluated for the treatment of nephrotic patients with membranous nephropathy who are resistant or intolerant to rituximab. Complement inhibitor therapy might serve to stop the glomerular inflammatory process until the benefits of these medications become effective. Thus, major advances in the understanding of the mechanisms of membranous nephropathy have led to novel treatment perspectives. The integrated evaluation of serum autoantibody titer and proteinuria, together with serum albumin levels in patients with overt nephrotic syndrome, could guide diagnosis of membranous nephropathy and individually tailored treatment protocols. The introduction of monoclonal antibodies targeting disease-specific mechanisms will pave the way for a novel therapeutic paradigm based on the principle of precision medicine and personalized therapy.

M-Type Phospholipase A2 Receptor Autoantibody Measured by ELISA has Diagnostic Value in Patients with Idiopathic Membranous Nephropathy.

This study investigated the diagnosis value of phospholipase A2 receptor autoantibodies (PLA2R-AB) for idiopathic membranous nephropathy (IMN). Patients with IMN, lupus nephritis, hepatitis B virus-associated nephropathy and IgA nephropathy and healthy participants were included. Receiver operating characteristics (ROC) curve was plotted for PLA2R-AB to diagnose IMN. The level of serum PLA2R-AB was significantly higher in patients with IMN than with other MN, and was positively correlated to urine albumin-creatinine ratio and proteinuria in patients with IMN. The area under the ROC curve displaying the performance of PLA2R-AB to diagnose IMN was 0.907 with a sensitivity and specificity of 94.3% and 82.1%, respectively. PLA2R-AB is a reliable biomarker to diagnose Chinese patients with IMN.