Phospholipase A2 Receptor Antigen Research Articles

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.

The Role of Renal PLA2R Staining Combined with Serum PLA2R Antibody in Membranous Nephropathy Risk Stratification.

This study aimed to examine the clinicopathological profiles and prognosis of membranous nephropathy in different subtypes classified by serum PLA2R antibody (SAb) and glomerular PLA2R antigen staining (GAg). A total of 372 biopsy-proven membranous nephropathy (MN) cases, unrelated to lupus, with urine protein > 2 g/24 h and eGFR > 25 mL/min/1.73 m2 were included and categorized into four groups according to the presence or absence of PLA2R antibody and glomerular PLA2R antigen staining. Clinical profiles were compared among four subtypes. Treatment response and renal outcomes were compared among four groups with primary MN. Cox and logistic regression models were used to examine the association between time-to-renal progression and early remission within 6 months in the four subgroups with primary MN. MN patients who were SAb-/GAg+ presented with a more severe disease onset, whereas those who were SAb-/GAg- had a mild clinical manifestation with a higher prevalence of MN-associated secondary causes. During a median follow-up of 79.2 months (IQR: 48.70-97.40), SAb+/GAg- was identified as an independent risk factor for renal progression [HR: 9.17, 95% CI: 2.26-37.16, p < 0.01] and early remission [OR: 0.06, 95% CI: 0.01-0.56, p = 0.01] in primary MN. Additionally, SAb-/GAg- with primary MN showed an independent association with spontaneous remission after adjusting for age, sex, baseline proteinuria, and eGFR (Before adjustment: OR: 8.33, 95% CI: 1.89-36.76, p = 0.0; after adjustment: OR: 12.25, 95% CI: 2.48-60.53, p < 0.01). Our findings indicated that SAb+/GAg-MN patients exhibited a more severe disease onset and had a poorer prognosis, necessitating an aggressive treatment approach. On the other hand, in the SAb-/GAg- group, the elimination of secondary causes should be considered, and a watchful waiting approach may be appropriate.

IgG4-Related Disease with IgG1-Dominant Membranous Nephropathy: A Rare Case Report

ABSTRACT Immunoglobulin G4-related disease (IgG4-RD) is an immune-mediated fibroinflammatory disorder affecting various organs and tissues. Kidney involvement in IgG4-RD commonly manifests as IgG4-related tubulointerstitial nephritis or IgG4-related membranous nephropathy, with the latter occurring less frequently. The identification of the phospholipase A2 receptor (PLA2R) antigen has improved our understanding of primary membranous nephropathy. Here, we present the case of a 60-year-old Chinese man initially diagnosed with IgG4-related pancreatitis, who achieved clinical remission with glucocorticoid therapy followed by low-dose glucocorticoid maintenance therapy. Two years later, the patient developed nephrotic syndrome. A kidney biopsy revealed membranous nephropathy characterized by glomerular subepithelial deposition of IgG1 and positive PLA2R staining. Rituximab (RTX) treatment resulted in complete clinical remission of nephrotic syndrome, and no recurrence was observed during the 24-month follow-up period. IgG4-RD complicated by membranous nephropathy is a rare pathological feature characterized by glomerular subepithelial IgG1 deposition and positive PLA2R antigen staining. In the present case, RTX treatment was effective in achieving clinical remission. These findings contribute to the evolving understanding of the relationship between IgG4-RD and membranous nephropathy.

THSD7A as a Promising Biomarker for Membranous Nephrosis.

Membranous nephropathy (MN) is an autoimmune disease of the kidney glomerulus and one of the leading causes of nephrotic syndrome. The disease exhibits heterogeneous outcomes with approximately 30% of cases progressing to end-stage renal disease. Traditionally, the standard approach of diagnosing MN involves performing a kidney biopsy. Nevertheless, kidney biopsy is an invasive procedure that poses risks for the patient including bleeding and pain, and bears greater costs for the health system. The clinical management of MN has steadily advanced owing to the identification of autoantibodies to the phospholipase A2 receptor (PLA2R) in 2009 and thrombospondin domain-containing 7A (THSD7A) in 2014 on the podocyte surface. At present, serum anti-PLA2R antibody detection and glomerular PLA2R antigen staining have been used for clinical diagnosis and prognosis, but the related detection of THSD7A has not been widely used in clinical practice. Here, we summarized the emerging knowledge regarding the roles THSD7A plays in MN and its clinical implications as diagnostic, prognostic, and therapeutic response as well as Methods for detecting serum THSD7A antibodies.

Measurement of urinary exosomal phospholipase A2 receptor is a sensitive method for diagnosis of PLA2R-associated membranous nephropathy.

The discovery of phospholipase A2 receptor (PLA2R) and its antibody (aPLA2Rab) has paved the way for diagnosing PLA2R-associated membranous nephropathy (PLA2R-MN) with a high specificity of 98%. However, the sensitivity was only 40% to 83.9%, and there is ongoing discussion around determining the optimal threshold for diagnosis. Recent advancements in the use of exosomes, a novel form of "liquid biopsy," have shown great promise in identifying markers for various medical conditions. Protein mass spectrometry and western blot were applied to verify the existence of PLA2R antigen in the urine exosome. We then evaluated the efficacy of urinary exosomal PLA2R antigen alone or combined with serum aPLA2Rab level to diagnose PLA2R-MN. The urinary exosomes contained a high abundance of PLA2R antigen as evidenced by protein mass spectrometry and western blot in 85 PLA2R-MN patients vs the disease controls (14 secondary MN patients, 22 non-MN patients and 4 PLA2R-negative MN patients) and 20 healthy controls. Of note, urinary exosomal PLA2R antigen abundance also had a good consistency with the PLA2R antigen level in the renal specimens of PLA2R-MN patients. The sensitivity of urinary exosomal PLA2R for diagnosing PLA2R-MN reached 95.4%, whereas the specificity was 63.3%. Combining detection of the urinary exosomal PLA2R and serum aPLA2Rab could develop a more sensitive diagnostic method for PLA2R-MN, especially for patients with serum aPLA2Rab ranging from 2 to 20 RU/mL. Measurement of urinary exosomal PLA2R could be a sensitive method for the diagnosis of PLA2R-MN.

The value of PLA2R antigen and IgG subclass staining relative to anti-PLA2R seropositivity in the differential diagnosis of membranous nephropathy

BackgroundThe diagnostic performance of PLA2R and IgG subclass staining of kidney biopsies relative to anti-PLA2R seropositivity in the differentiation of primary and secondary membranous nephropathy (pMN, sMN) was examined. Besides PLA2R staining – which has a lower specificity than anti-PLA2R antibody serology – there is insufficient knowledge to decide which IgG1-4 subtype immunohistological patterns (IgG4-dominance, IgG4-dominance/IgG1-IgG4-codominance or IgG4-dominance/IgG4-codominance with any IgG subtype) could be used to distinguish between pMN and sMN.Methods87 consecutive Hungarian patients (84 Caucasians, 3 Romas) with the biopsy diagnosis of MN were classified clinically as pMN (n = 63) or sMN (n = 24). The PLA2R and IgG subclass staining was part of the diagnostic protocol. Anti-PLA2R antibodies were determined by an indirect immunofluorescence test in 74 patients with disease activity.ResultsFor pMN, the sensitivity of anti-PLA2R seropositivity was 61.1%, and the specificity was 90.0%; and similar values for PLA2R staining were 81.0%, and 66.7%, respectively. In all stages of pMN, IgG4-dominance was the dominant subclass pattern, while the second most frequent was IgG3/IgG4-codominance. The sensitivity and specificity scores were: IgG4-dominance 52.2% and 91.7%, IgG4-dominance/IgG3-IgG4-codominance 76.2% and 87.5%, IgG4-dominance/IgG1-IgG4-codominance 64.2% and 75%, and IgG4-dominance/codominance with any IgG subclass 92.1% and 70.8%, respectively. Anti-PLA2R seropositivity, glomerular PLA2R, and IgG4-dominance/codominance significantly correlated with each other. The IgG4 subclass was rarely encountered in sMN.ConclusionIn our series, IgG4-dominance had the highest specificity in the differentiation of MN, just as high as that for anti-PLA2R seropositivity. The specificity values of PLA2R staining and IgG4-dominance/codominance with any IgG subclass or IgG4-dominance/IgG1-IgG4 codominance were ≤ 75%. Apart from IgG4 dominance, IgG4-dominance/IgG3-IgG4-codominance also had good statistical value in differentiating pMN from sMN. As IgG subclass switching during the progression of pMN was not the feature of our cohort, pMN in Hungarian patients is presumed to be an IgG4-related disorder right from the start. Although anti-PLA2R seropositivity has become the cornerstone for diagnosing pMN, if a kidney biopsy evaluation is conducted, besides the staining of PLA2R antigen, the evaluation of IgG subclasses provides relevant information for a differential diagnosis. Even in cases with IgG4-dominance, however, malignancy should be thoroughly checked.

Primary membranous nephropathy in two siblings with one combined with anti-glomerular basement membrane disease: a case report

BackgroundThe phospholipase A2 receptor (PLA2R) associated with membranous nephropathy (MN) is an organ-specific autoimmune disease associated with PLA2R and human leukocyte antigen (HLA) genes. Familial PLA2R-related MN is rarely reported. The combination of anti-GBM disease and MN has been well documented, though the mechanism behind it remains unclear.Case presentationWe describe two siblings diagnosed with pathology-confirmed PLA2R-related MN 1 year apart. And one of the two siblings developed an anti-GBM disease. The high-resolution HLA typing showed identical alleles in both siblings, specifically heterozygotes of DRB1*15:01/*03:01.ConclusionWe describe a familial case of PLA2R-related MN supporting the role of genetic factors that HLA-DRB1*15:01 and DRB1*03:01 predispose patients in the development of PLA2R-related MN in the Han Chinese population. The combination of MN and anti-GBM disease may also partially be associated with the same susceptible HLA allele DRB1*15:01.

#6905 PREVALENCE OF ANTIPLA2R ANTIBODIES IN EGYPTIAN PATIENTS WITH NEPHROTIC SYNDROME

Abstract Background and Aims Primary membranous nephropathy (PMN), a common form of the nephrotic syndrome, is an antibody-mediated autoimmune glomerular disease. Autoimmunity is driven by circulating autoantibodies that bind to one or more antigens on the surface of glomerular podocytes. PLA2R antigen is the most common and prevalent one among these antigens. Anti-PLA2R antibodies are measured in serum and detected within biopsies of primary membranous nephropathy patients. Up to the moment, no clear data about the prevalence of AntiPLA2R antibodies associated PMN in Egyptian patients. The aim of this work was to study the prevalence of antiPLA2R antibodies in Egyptian patients with nephrotic syndrome underwent renal biopsy. Method In this cross-sectional study we recruited 70 adult patients presented with nephrotic range proteinuria to Ain-shams university hospital and a private nephrology center in Cairo during a period of 20 months (from March 2020 to October 2021). All patients first presentation for whom laboratory investigations including serum anti-PLA2R antibodies titer by indirect immunofluorescence and kidney biopsy were done. Anti-PLA2R antibodies were measured in serum, checked in biopsies and correlated with biopsy findings. Results Membranous nephropathy (primary and secondary) was found by biopsy finding in 25 of 70 patients (35.7%) presenting with nephrotic range proteinuria. 21 patients (84%) of the cases of membranous nephropathy had been diagnosed with primary membranous nephropathy and 4 (16%) had been diagnosed with secondary membranous nephropathy. Circulating anti-PLA2R antibodies were detected within serum in 9 (42.85%) of primary MN cases while detection of anti-PLA2R antibodies within the glomerular extracts of primary MN cases was much higher; 17 patients (80.95%). There was positive correlation between serum AntiPLA2R Antibodies titer and U PCR (r = 0.839, P = 0.005) (Fig. 1). Conclusion A we may conclude that, most patients with primary membranous nephropathy have anti-PLA2R antibodies. Detection of anti-PLA2R antibodies within the biopsy has higher sensitivity than serum (80.95% versus 42.85%). Specificity of PLA2R to primary membranous nephropathy is 100%. Patients with high anti-PLA2R titer had higher baseline proteinuria than patients with lower anti-PLA2R titer.

Clinicopathological features and outcome in elderly patients with idiopathic membranous nephropathy

Background Idiopathic membranous nephropathy (IMN) is the leading cause of nephrotic syndrome in the elderly. The treatment of idiopathic membranous nephropathy is quite challenging due to the particularity of elderly patients. This study intends to investigate the clinicopathological characteristics and initial therapeutic effect of idiopathic membranous nephropathy among elderly patients. Methods A retrospective study of 67 elderly patients (58.2% male, median age 69.0 years, range, 65–83 years) with biopsy-proven membranous nephropathy was conducted at Guangdong Provincial People’s Hospital from 2016 to 2020. Data on clinicopathological characteristics and initial therapeutic effects were analyzed. Results Of the 67 patients, the mean eGFR of overall patients was 66.49 mL/min/1.73m2 while the median urine protein-to-creatinine ratio (uPCR) and urine albumin-to-creatinine ratio (uACR) was 5676.73 mg/g and 2951.56 mg/g, respectively. Pathological data revealed that the membranous Churg’s stage II was the most frequent (71.64%). Moreover, glomerular PLA2R antigen fluorescence intensity of (+) and IgG4 antigen fluorescence intensity of (++) were detected in 63.6% and 86.4% of all patients, respectively. Overall, 44 patients, accounting for 65.7%, achieved remission including complete remission and partial remission within 1 year after renal biopsy. Compared with a non-remission group, the levels of uPCR (6274.6 vs. 3235.6 mg/g, p = 0.007) and uACR (3433.6 vs. 1773.2 mg/g, p = 0.017) were significantly higher in remission group. The proportion of immunosuppressive therapy in the remission group was also higher (86.4% vs. 30.4%, p < 0.01). Compared with conservative treatment, patients with combined treatment with glucocorticoid and cyclophosphamide (CTX) or glucocorticoid and calcineurin inhibitor (CNIs) achieved higher remission rate (glucocorticoid plus cyclophosphamide vs. conservative treatment, 84.6% vs. 27.3%, p = 0.001; glucocorticoid plus calcineurin inhibitor vs. conservative treatment, 88.0% vs. 27.3%, p < 0.001). Further analysis showed that compared with patients who underwent conservative treatment, the proportion of males, the levels of uPCR, uACR, BUN, Scr, CysC and PLA2R antigen-positive staining rate in kidney biopsy were higher in those who underwent combined treatment with glucocorticoid and CTX, while the levels of eGFR, TP and ALB were lower (p < 0.05). In addition, patients who received combined treatment with glucocorticoid and CNIs had higher levels of uPCR, uACR, TC and lower levels of TP, ALB than those who received conservative treatment (p < 0.05). Moreover, there were no statistically significant differences in the 1-year progression rate in eGFR between the immunosuppressive treatment group and conservative treatment group (3.3 vs. 0.2 ml/min/1.73m2, p = 0.852). Conclusions Most elderly patients diagnosed with IMN had multiple comorbidities, and the membranous Churg’s stage II was most common. The glomerular PLA2R and IgG4 antigen deposition were frequently detected accompanied by glomerulosclerosis and severe tubulointerstitial injury. For high-risk elderly patients with severe proteinuria, early initial immunosuppressive therapy could achieve a higher urinary protein remission rate. Therefore, it is crucial for clinicians to balance the risks and benefits of immunosuppressive therapy based on clinical and pathological characteristics and develop individualized treatment regimens for elderly patients with IMN.

Analysis of glomerular PLA2R efficacy in evaluating the prognosis of idiopathic membranous nephropathy in the background of different serum anti-PLA2R levels

Objective To verify glomerular PLA2R antigen and serum PLA2R antibody expression in membranous nephropathy as well as to explore glomerular PLA2R efficacy in evaluating the prognosis of idiopathic membranous nephropathy (IMN) in the background of different serum anti-PLA2R levels. Methods We retrospectively analyzed 155 patients who were diagnosed with IMN by kidney biopsy. Patients were divided into six groups according to their serum PLA2R antibody or glomerular PLA2R antigen positiveness and the level of serum anti-PLA2R titer. Both clinical features and pathological characteristics were recorded, and the remission time was compared among groups. Correlation between clinical figures and the anti-PLA2R titer or semi-quantity of glomerular PLA2R antigen was detected. Results A positive correlation between time to partial remission and serum anti-PLA2R titer was found. Among patients with serum anti-PLA2R titer <150 RU/ml, there were shorter remission time in negative glomerular PLA2R antigen group compared with positive glomerular PLA2R antigen, and a positive correlation between time to complete remission and semi-quantity of glomerular PLA2R antigen was found. Conclusion Both glomerular PLA2R antigen and serum anti-PLA2R play a role in disease presentation and prognosis in primary membranous nephropathy. Glomerular PLA2R antigen has a major role on disease prognosis when serum anti-PLA2R titer is less than 150RU/ml, while serum anti-PLA2R has predominant role in IMN prognosis when serum anti-PLA2R titer is above 150RU/ml.

Clinicopathological Characteristics and Outcomes of PLA2R-Associated Membranous Nephropathy in Seropositive Patients Without PLA2R Staining on Kidney Biopsy

Phospholipase A2 receptor (PLA2R)-associated membranous nephropathy (MN) with circulating serum autoantibodies to PLA2R (SAb+) but no deposits of PLA2R antigen in glomerular tissue by immunofluorescence (GAg-) has been reported. However, little is known about the clinicopathological characteristics or prognosis of this subtype of MN. Retrospective cohort study. 130 SAb+ patients in China with biopsy-proven MN who had follow-up data and received immunosuppressive therapy. The median follow-up was 16 (IQR, 9-25) months. PLA2R antigen detection by immunofluorescence staining of kidney biopsy specimens. Complete remission (CR) was defined as proteinuria levels<0.3 g/d and a >50% decreasecompared with a previously established baseline. Partial remission (PR) was defined as proteinuria levels<3.5 g/d and a >50% decrease compared with a previously established baseline. The kidney function outcome was defined as a >40% decrease in estimated glomerular filtration rate (eGFR) at the end of the study compared with baseline. Kaplan-Meier analysis of PR and CR comparing SAb+/GAg+ and SAb+/GAg- patients. Cox proportional hazards models to examine these associations were adjusted for confounders. Among 130 SAb+ patients with PLA2R-associated MN, 18 were GAg-. Compared with SAb+/GAg+ patients, those who were SAb+/GAg- presented with more severe kidney injury as evidenced by higher SAb titer, greater proteinuria, lower serum albumin concentrations, lower eGFR (all P< 0.05), and more severe disease with higher chronicity scores (P< 0.001) on kidney biopsies. SAb+/GAg- patients exhibited a significantly lower probability of PR (P< 0.001) and CR (P= 0.03) and were more likely to experience a >40% decrease in eGFR (P= 0.008) than patients who were SAb+/GAg+. After adjusting for clinical and pathologic variables available at the time of biopsy, compared with SAb+/GAg+ patients, SAb+/GAg- patients had a lower rate of experiencing remission (hazard ratio, 0.32 [95% CI, 0.15-0.68]; P= 0.003) and a higher rate of the >40% eGFR decrease outcome (hazard ratio, 7.66 [95% CI, 1.54-38.08]; P= 0.01). Retrospective study, small sample size, and lack of a uniform approach to treatment. Seropositive PLA2R-associated MN without PLA2R staining on kidney biopsy may represent a distinct clinical subtype with more severe disease and a worse prognosis. GAg- is independently associated with poor response to treatment and >40% eGFR decrease in seropositive PLA2R-associated MN.

Analysis of Glomerular IgG Subclasses Switch in Idiopathic Membranous Nephropathy Classified by Glomerular Phospholipase A2 Receptor Antigen and Serum Antibody.

Background The role of IgG subclass in idiopathic membranous nephropathy (IMN) was unclarified. Recent study found IgG subtype switches from IgG1 to IgG4 in the early pathological stage in IMN. The profile of IgG subclass in phospholipase A2 receptor- (PLA2R-) related and PLA2R-unrelated IMN was unrevealed. Our study is aimed at testifying whether IgG subclass switch existed in PLA2R-related and PLA2R-unrelated IMN, respectively. Methods Our study retrospectively enrolled 157 Chinese patients with biopsy-confirmed IMN between September 2017 and November 2019. We measured glomerular PLA2R antigen and serum anti-PLA2R antibody to classify the patients into PLA2R-related (n = 132) and PLA2R-unrelated (n = 25) subgroup. We evaluated glomerular IgG subclass by immunofluorescence (IF) predominance. Our study defined IgG subclass deposition as predominant if the IF score was higher than the other three and ≥1 +, or as codominant if the IF intensity was equal to any other and ≥1 +. We explored the relationship between IF predominance of glomerular IgG subtype and electron microscopic (EM) stages of IMN. Results We did not find statistical difference of predominant or codominant rate (pre/co-rate) among EM stages in any subclass (P > 0.05). Pre/co-rate of IgG3 linearly associated with EM stage in total and PLA2R-related subgroup (P = 0.044, P = 0.013). PLA2R-related subgroup showed higher IgG4 intensity (2.1 ± 0.6 vs. 1.6 ± 0.7, P = 0.001) and pre/co-rate of IgG4 in stage 1 (97% vs. 57%, P = 0.015) than PLA2R-unrelated group. We found no difference of IgG subclass pre/co-rate in different EM stages or linear association between pre/co-rate of IgG1, IgG2, IgG4, and EM stages (P > 0.05). Conclusions Pre/co-rate of IgG3 declined with EM stage in total and PLA2R-related subgroup. We did not find IgG subclass switches from IgG1 to IgG4 in either IMN patients or subgroups.

POS-149 PREVALENCE OF ANTI-PLA2R ANTIBODIES AND ITS CLINICAL UTILITY IN PATIENTS OF MEMBRANOUS NEPHROPATHY- INDIAN EXPERIENCE

Membranous Nephropathy (MN), the most common cause of nephrotic syndrome in non diabetic adults is a potential cause of end stage renal disease if not treated in time. Our aim was to study prevalence of anti Phospholipase A2 receptor (PLA2R) antibodies in serum, PLA2R antigen in biopsy & correlation of PLA2R antibody titer with disease outcome in Indian cohort of MN patients.

PLA2R Immunohistochemistry Staining in Membranous Glomerulopathy: A Challenging Stain to Interpret But a Potentially Useful Diagnostic Tool.

Circulating autoantibodies to phospholipase A2 receptor (PLA2R-Ab) are detected in >70% of patients with primary membranous glomerulonephritis (MGN). Detection of PLA2R antigen in renal tissue, with immunohistochemistry (PLA2R IHC), strongly correlates with serum PLA2R-Ab, although it is more sensitive. As PLA2R IHC in literature has no univocal interpretation, we suggest reliable criteria for a standard approach for the assessment of immunostaining for differential diagnosis between primary and secondary MGN. We analyzed PLA2R IHC expression in 40 biopsies of patients with MGN and serum PLA2R-Ab titer at the time of biopsy. We carefully evaluated, at high magnification, the immunostaining pattern and distribution, regardless of intensity, in capillary loops, mesangium, and podocytes of all glomeruli.We defined, adopting this approach, positive stain when a granular pattern, coarse and/or fine, diffuse or focal, and global or segmental were observed. Negative stain was defined by mesangial staining, when there was a dirty pattern, or a peripheral staining of capillary loops with a smoky linear pattern. Podocytes showed homogenous cytoplasmatic stain both in positive and negative cases and in external negative controls. We found PLA2R IHC and serum PLA2R-Ab positivity in early-middle stage MGN compared with advanced stage more frequently. Correct stratification of patients with MGN needs PLA2R-Ab detection in serum and renal tissue. PLA2R IHC test, although a challenging stain, can be an easy diagnostic tool but requires reliable interpretation keys for a standard approach to the assessment of immunostaining.

Seropositive PLA2R-associated membranous nephropathy but biopsy-negative PLA2R staining.

Serum phospholipase A2 receptor (PLA2R) antibody (SAb) and glomerular deposits of PLA2R antigen (GAg) have been tested widely in idiopathic membranous nephropathy (MN). Recently, we noticed a special form of PLA2R-associated MN with positive circulating PLA2R antibody but negative PLA2R deposits in the glomeruli by immunofluorescence on frozen tissue (IF-F). The significance of this form of PLA2R-associated MN is yet to be elucidated. This study aimed to explore the clinicopathological features of these PLA2R-associated MN patients. This study enrolled 229 biopsy-proven PLA2R-associated MN patients with SAb+. SAb was measured by enzyme-linked immunosorbent assay, and GAg was detected by IF-F. These patients were divided into SAb+/GAg+ and SAb+/GAg- groups. Clinicopathological characteristics of SAb+/GAg+ and SAb+/GAg- PLA2R-associated MN patients were compared. PLA2R antigens of 19 SAb+/GAg- PLA2R-associated MN patients were verified by immunohistochemistry on paraffin tissue (IHC-P). Among 229 SAb+ PLA2R-associated MN patients, 210 (91.70%) were GAg+ and 19 (8.3%) were GAg-. These 19 SAb+/GAg- PLA2R-associated MN patients presented positive PLA2R deposits by IHC-P. Compared with SAb+/GAg+ PLA2R-associated MN patients, SAb+/GAg- PLA2R-associated MN patients had higher levels of serum PLA2R antibody (P = 0.004), increased proteinuria (P = 0.008), lower serum albumin (P = 0.019), more prominent chronic pathological lesions in terms of glomerulosclerosis score (P = 0.025), interstitial fibrosis score (P = 0.016), tubular atrophy score (P = 0.010) and total renal chronicity score (P = 0.010), and were more likely to be accompanied by focal segmental glomerulosclerosis (P = 0.014). Higher SAb level was associated with the total renal chronicity score (odds ratio per 100 RU/mL, 1.16; 95% confidence interval 1.01-1.33; P = 0.033). PLA2R-associated MN patients with seropositive PLA2R antibody but negative PLA2R deposits in the glomeruli by IF-F have higher levels of SAb and worse clinicopathological manifestations compared with their double-positive counterparts. IHC-P can be an alternative technique to reveal PLA2R glomerular deposits.

Membranous nephropathy in patients with HIV: a report of 11 cases

BackgroundMembranous nephropathy (MN) has been recognized to occur in patients with human immunodeficiency virus (HIV) infection since the beginning of the HIV epidemic. The prevalence of phospholipase A2 receptor (PLA2R)-associated MN in this group has not been well studied.MethodsWe conducted a retrospective review of electronic pathology databases at three institutions to identify patients with MN and known HIV at the time of renal biopsy. Patients with comorbidities and coinfections known to be independently associated with MN were excluded.ResultsWe identified 11 HIV-positive patients with biopsy-confirmed MN meeting inclusion and exclusion criteria. Patient ages ranged from 39 to 66 years old, and 10 of 11 patients (91%) were male. The majority of patients presented with nephrotic-range proteinuria, were on anti-retroviral therapy at the time of biopsy and had low or undetectable HIV viral loads. Biopsies from 5 of 10 (50%) patients demonstrated capillary wall staining for PLA2R. Measurement of serum anti-PLA2R antibodies was performed in three patients, one of whom had positive anti-PLA2R antibody titers. Follow-up data was available on 10 of 11 patients (median length of follow-up: 44 months; range: 4–145 months). All patients were maintained on anti-retroviral therapy (ARV) and 5 patients (52%) received concomitant immunosuppressive regimens. Three patients developed end-stage renal disease (ESRD) during the follow-up period.ConclusionsMN in the setting of HIV is often identified in the setting of an undetectable viral loads, and similar to other chronic viral infection-associated MNs, ~ 50% of cases demonstrate tissue reactivity with PLA2R antigen, which may be seen without corresponding anti-PLA2R serum antibodies.

Kidney Biopsy Is Required for Nephrotic Syndrome with PLA2R+ and Normal Kidney Function: Commentary.

Almost seven decades have elapsed since the paradigm-shifting description of percutaneous aspiration kidney biopsy was first published by Iversen and Brun (1,2). There is no doubt that this procedure has profoundly affected our understanding of kidney disease in general, and it has contributed greatly to improving medical care specifically in the field of glomerular diseases. But like all such advances, over time, new findings can alter the way in which the procedure is used and viewed. The concept of a potential “liquid biopsy” has emerged as an alternative to “tissue biopsy” with the development of sophisticated urinary proteomics and serum biomarkers of specific disease entities (3,4). Nevertheless, kidney biopsy continues to be the gold standard for diagnosis of underlying conditions when the clinical features are insufficiently distinct to provide a diagnosis and when additional information is needed to better guide prognosis and management. Although percutaneous kidney biopsy is generally regarded as safe when performed under ideal conditions by an experienced operator, major but usually nonlife-threatening complications can ensue in a small percentage of cases (5). Thus, the decision to pursue a strategy of kidney biopsy is governed by the risk of the procedure compared to the likelihood that the tissue will provide information that cannot otherwise be obtained noninvasively and that will make a difference in the management of the patient going forward. When the tissue is examined thoroughly by light, immunofluorescence, and electron microscopy, including special staining methods, kidney biopsies can often deliver a specific diagnosis and useful therapeutic guidance. These considerations form the crux of the proposition advanced in this debate, highlighted by the pro (6) and con (7) responses. Essentially, the debate asks whether positive results of testing for serum autoantibodies to PLA2R antigen in a well defined subset of adult patients presenting …

Clinical significance of M-type phospholipase A2 receptor and thrombospondin Type 1 domain-containing 7A in primary membranous nephropathy.

To evaluate the value of thrombospond in Type I domain-containing 7A (THSD7A) and M-type phospholipase A2 receptor (PLA2R) in primary membranous nephropathy (PMN) and to explore the relationship between their antibody levels and prognosis. Renal tissues in 128 patients with membranous nephropathy in the Second Xiangya Hospital of Central South University were collected from February 2015 to August 2017, including 108 patients with primary membranous nephropathy (PMN group) and 20 patients with secondary membranous nephropathy (SMN) (SMN group). Indirect immunofluorescence method was used to detect the expression of PLA2R antigen in kidney tissues,and the glomerular expression of THSD7A antigen was examined by immunohistochemistry and indirect immunofluorescence. The serum levels of anti-PLA2R antibodies and THSD7A antibodies were also detected by ELISA. According to the results of PMN examination,the patients were also divided into a PLA2R-related membranous nephropathy group and a THSD7A-related membranous nephropathy group. The positive rate of PLA2R in the renal tissues in the PMN group was higher than that in the SMN group (78% in the PMN group, 35% in the SMN group, P<0.01),while the positive rate of anti-PLA2R antibody in the PMN group was also higher than that in the SMN group (50% in the PMN group, 25% in the SMN group, P<0.05).The serum level of anti-PLA2R antibody was positively correlated with 24 h urine protein (r=0.254, P<0.05) and negatively correlated with serum albumin (r=-0.236, P<0.05). The expression of THSD7A was positive in glomeruli in 7 cases of the PMN group (6%) by immuno-histochemistry, and which was positive in 1case of the SMN group (5%).The serum levels of anti-THSD7A antibody in the PMN group were higher than those in the SMN group [(0.49±0.26) pg/mL in the PMN group,(0.34±0.27) pg/mL in the SMN group, P<0.05]. There was no difference in the clinical characteristics between the PLA2R-related membranous nephropathy group and the THSD7A-related membranous nephropathy group. PLA2R and THSD7A are the target antigen of PMN, and the associated autoantibodies are helpful for the differential diagnosis of PMN. The anti-PLA2R antibody levels can reflect the severity of the disease and evaluate the effect of treatment. The incidence of THSD7A membranous nephropathy is low, and monitoring the serum anti-THSD7A antibody levels can assess patients' condition and predict disease outcome.

Serum Antibody and Glomerular Antigen of Antiphospholipase A2 Receptor in Chinese Patients with Idiopathic Membranous Nephropathy.

Background M-type phospholipase A2 receptor (PLA2R) is the first autoantigen responsible for idiopathic membranous nephropathy (IMN). However, serum PLA2R antibody (PLA2R-Ab) can be inaccurate in distinguishing between IMN and secondary membranous nephropathy, while renal PLA2R antigen (PLA2R-Ag) emerges as an ancillary diagnostic. The present study is aimed at examining the associations between PLA2R-Ab in sera and PLA2R-Ag in kidneys in IMN patients. Methods A total of 93 patients with IMN were retrospectively identified. Their serum PLA2R-Ab and renal PLA2R-Ag expression levels were determined, and the clinical correlations between these parameters and clinical features were examined. Results The sensitivities of serum PLA2R-Ab and renal PLA2R-Ag for diagnosing IMN were 74.2% and 88.2%, respectively (P < 0.001), with poor consistency. Higher serum PLA2R-Ab levels were correlated to stronger renal PLA2R-Ag expression (P = 0.048). Patients with positive PLA2R-Ab significantly differed from those with negative levels, in terms of proteinuric levels over 24 hours (4.54 vs. 3.46 g/day, P = 0.015) and serum albumin (23.28 vs. 27.95 g/L, P = 0.038). Among patients with positive renal PLA2R-Ag, patients with positive PLA2R-Ab had significantly higher 24-hour proteinuria, when compared to patients with negative PLA2R-Ab (4.57 vs. 3.08 g/day, P = 0.005). Among those with positive PLA2R-Ab in sera, their PLA2R-Ab levels were correlated with the estimated glomerular filtration and serum creatinine. Conclusion Serum PLA2R-Ab exhibits a closer correlation with proteinuric severity and renal function, when compared to renal PLA2R-Ag.

Retrospective study: clinicopathological features and prognosis of idiopathic membranous nephropathy with seronegative anti-phospholipase A2 receptor antibody.

BackgroundTo discuss the clinicopathological features and prognosis of patients with idiopathic membranous nephropathy (IMN) who are serum-negative for the anti-PLA2R antibody.MethodOverall, 229 IMN patients were retrospectively collected in this study and classified into anti-PLA2R antibody-negative (PLA2R−, 59 cases) and antibody-positive (PLA2R+, 170 cases) groups. The clinical and pathological features of the PLA2R− group were analyzed; 162 patients in both groups were followed up, and the PLA2R antigen was detected in renal biopsies from the PLA2R− group. Kaplan-Meier and survival analyses were used to compare differences in prognosis.ResultsSerum albumin levels were higher and 24-hour urine protein, creatinine, and beta 2-microglobulin (BMG) levels were lower in the PLA2R− group than in the PLA2R+ group; the proportion of acute and chronic tubular lesions was also significantly lower in the PLA2R− group than in in the PLA2R+ group. After treatment, the remission rate was significantly higher in the negative group than in the positive group (93.02% vs 74.78%,), especially the rate of complete remission (51.16% vs 23.47%). Furthermore, the PLA2R antigen-positive staining rate of 43 patients in the PLA2R− group was 62.79%. Although not significant, the survival rate was higher in the PLA2R− group than in the PLA2R+ group. BMG, 24-hour urine protein and acute and chronic tubular lesions were risk factors for kidney death, and 24-hour urine protein was an independent risk factor for kidney death.ConclusionsCompared with the PLA2R+ group, the PLA2R− group had mild clinical manifestations and pathological damage and a higher clinical treatment remission rate. Renal tissue PLA2R antigen testing can be considered for patients with seronegative IMN to increase the diagnostic rate.