Diagnosis Of Primary Membranous Nephropathy Research Articles

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 thickness of glomerular basement membrane predicts complete remission in primary membranous nephropathy

Objective Glomerular basement membrane (GBM) thickening is a typical and essential histopathological characteristic for the diagnosis of primary membranous nephropathy (PMN). The present study aimed to explore the relationship between GBM thickness and treatment response in PMN patients. Methods A total of 128 patients with nephrotic syndrome concurrent with PMN were studied. The highest GBM thickness was measured from at least five glomerular capillary loops using an electron microscope, and the mean value was obtained. Patients were categorized into three groups according to the tertiles of GBM thickness as follows: Group 1 (GBM thickness ≤ 1100 nm, n = 48), Group 2 (1100 nm < GBM thickness ≤ 1300 nm, n = 40), Group 3 (GBM thickness >1300 nm, n = 40). Clinicopathological features and treatment response were compared among the three groups. The associations of GBM thickness with complete remission (CR) were assessed by Cox proportional hazard analyses and a cubic spline curve. Results During a median follow-up period of 25.80 months, 69 (53.9%) patients achieved CR. Kaplan–Meier analysis showed that the non-CR probability was significantly higher in the highest tertile of GBM thickness (p˂0.001). Univariate Cox proportional hazard analysis indicated that GBM thickness was associated with CR (HR per SD 0.617, 95% CI [0.471–0.809], p˂0.001). After adjusting for age, duration of PMN, estimated glomerular filtration rate (eGFR), urinary protein excretion, grade of C3 deposition, and titer of serum anti-phospholipase A2 receptor (PLA2R) antibody, GBM thickness remained an independent predictor of CR (HR per SD 0.580, 95% CI [0.436–0.772], p˂0.001). Further multivariable-adjusted restricted cubic spline analysis confirmed a significant reverse linear association between GBM thickness and CR (p for nonlinear = 0.1261). Conclusions GBM thickness is an independent risk factor of CR. PMN patients with an increased level of GBM thickening at diagnosis have a lower probability of achieving CR.

Can use of the serum anti-PLA2R antibody negate the need for a renal biopsy in primary membranous nephropathy?

Since the emergence of the anti-PLA2R antibody (PLA2R-Ab) test, nephrology practice has not changed dramatically, with most nephrologists still relying on a kidney biopsy to diagnose membranous nephropathy. In this study, we examined the clinical accuracy of the anti-PLA2R antibody test using ELISA in routine clinical care. We conducted a retrospective analysis of PLA2R-Ab testing in 187 consecutive patients seen at a single UK centre between 2003 and 2020. We compared the kidney biopsy findings with the PLA2R-ab antibody test. Patients' demography, urine protein creatinine ratios, serum albumin, and treatment characteristics including supportive and immunosuppressive treatment were recorded. The clinical accuracy of the test (e.g. sensitivity and specificity, positive [PPV] and negative [NPV] predictive values) was calculated using the kidney biopsy findings as the diagnostic reference. Mean levels of PLA2R-Ab titre in primary membranous nephropathy were 217RU/ml in comparison to 3RU/ml for both secondary membranous nephropathy and other diagnoses. Most patients with a positive PLA2R-Ab test had a confirmed renal biopsy diagnosis of primary membranous nephropathy with: PPV of 97.3%, sensitivity 75.5%, NPV was 79.8% and specificity was 97.8% at a cut-off threshold of >20 RU/ml. The anti-PLA2R antibody test is a highly specific test for diagnosing membranous nephropathy, and the test has the potential to allow for the diagnosis and treatment in up to 75% of PMN cases without the need for a renal biopsy. Nevertheless, patients with negative PLA2R-Ab tests will still require a biopsy to confirm their diagnosis.

Computer-aided diagnosis of primary membranous nephropathy using expert system

BackgroundThe diagnosis of primary membranous nephropathy (PMN) often depends on invasive renal biopsy, and the diagnosis based on clinical manifestations and target antigens may not be completely reliable as it could be affected by uncertain factors. Moreover, different experts could even have different diagnosis results due to their different experiences, which could further impact the reliability of the diagnosis. Therefore, how to properly integrate the knowledge of different experts to provide more reliable and comprehensive PMN diagnosis has become an urgent issue.MethodsThis paper develops a belief rule-based system for PMN diagnosis. The belief rule base is constructed based on the knowledge of the experts, with 9 biochemical indicators selected as the input variables. The belief rule-based system is developed of three layers: (1) input layer; (2) belief rule base layer; and (3) output layer, where 9 biochemical indicators are selected as the input variables and the diagnosis result is provided as the conclusion. The belief rule base layer is constructed based on the knowledge of the experts. The final validation was held with gold pattern clinical cases, i.e., with known and clinically confirmed diagnoses.Results134 patients are used in this study, and the proposed method is defined by its sensitivity, specificity, accuracy and area under curve (AUC), which are 98.0%, 96.9%, 97.8% and 0.93, respectively. The results of this study present a novel and effective way for PMN diagnosis without the requirement of renal biopsy.ConclusionsThrough analysis of the diagnosis results and comparisons with other methods, it can be concluded that the developed system could help diagnose PMN based on biochemical indicators with relatively high accuracy.Graphical

W020 Performance evaluation and diagnostic accuracy of anti phospholipase A2 receptor (PLA2R) IGG for the diagnosis of primary membranous nephropathy – Experience from a clinical laboratory in Pakistan

W020 Performance evaluation and diagnostic accuracy of anti phospholipase A2 receptor (PLA2R) IGG for the diagnosis of primary membranous nephropathy – Experience from a clinical laboratory in Pakistan

The role of serum levels of anti-phospholipase A2 receptor antibodies in the diagnosis of primary membranous nephropathy.

Primary membranous nephropathy (PMN) is one of the most common causes of nephrotic syndrome in adults. The disease process is probably initiated by the binding of circulating autoantibodies to target podocyte antigens. In 2009, Beck et al. found that phospholipase A2 receptor (PLA2R1) was expressed on human podocytes in patients with PMN. Recent evidence suggests that PLA2R1 autoantibodies play an important role in the diagnosis of PMN. The aim of the present study was to compare the serum levels of anti-PLA2R1 in patients with PMN, second MN (SMN), other nephropathies (ON), and healthy controls (HC). The study included 52 patients with PMN, 12 patients with SMN, 49 patients with ON, and 50 healthy controls. The serum concentration of anti-PLA2R1 was determined with ELISA kit (Anti-PLA2R ELISA, IgG, EUROIMMUN, Lübeck, Germany) using MR-96A microplate Reader (MINDRAY). Statistical analysis was performed with SPSS v.22.0. There was significant difference in the serum anti-PLA2R1 concentrations between patient groups and HC (p<0.0001). Compared to HC, the median anti-PLA2R1 level in the PMN group was significantly higher (4.8 RU/ml vs. 34.9 RU/ml, p=0.001), in the ON group it was lower (2.1 RU/ml, p=0.002) and did not differ in patients with SMN (2.9 RU/ml, p=0.193). The anti-PLA2R1 serum levels were significantly higher in the PMN group than in the SMN (p=0.015) and ON (p<0.001) groups. Our results showed that anti-PLA2R1 is significantly increased in patients with PMN. We can conclude that the anti-PLA2R1 serum concentration may be used as a beneficial biomarker for distinguishing PMN from other membranous nephropathies.

MO432COMPARATIVE ANALYSIS OF INDIRECT IMMUNOFLUORESCENCE AND ENZYME-LINKED IMMUNOSORBENT ASSAYS FOR ANTI-PLA2R ASSESMENT IN PATIENTS WITH PRIMARY MEMBRANOUS NEPHROPATHY

Abstract Background and Aims Antibodies to M-type phospholipase A2 receptor (PLA2R-Ab) are considered to be a promising biomarker for laboratory diagnosis of primary membranous nephropathy (PMN) and may be useful in the evaluation of the response to therapy and CKD prognosis. The aim of the study was to compare two immunoassay methods – indirect immunofluorescence (IIF) and enzyme immunoassay (ELISA) for the determination of circulating PLA2R-Ab in patients with PMN. Method The study included 54 patients aged 55 (40-63) yrs. (M: F [33:21]) with PMN before treatment (n=16) and treated with immunosuppressive therapy (IST) (n=38), and apparently healthy individuals of the corresponding gender and age (n=10). Proteinuria and estimated glomerular filtration rate (eGFR) were determined in all participants. The levels of PLA2R-Ab were determined by IIF and quantitative/ semi-quantitative ELISA (EURUIMMUN AG test, Germany). In 16 PMN patients without treatment and 28 PMN patients treated with IST the level of PLA2R-Ab was measured one time and in 10 PMN patients treated IST – in dynamic, from 2 to 5 times. Statistical comparisons among groups were performed using Mann–Whitney U-test and Kruskal-Wallis H tests. The association between variables was estimated using Spearman’s coefficient. Sensitivity and specificity of the methods were calculated. Results The correlation coefficient between IIF and ELISA was 0.82 (p &amp;lt;0.005). There were more PLA2R-Ab-positive cases detected by ELISA, both before treatment (ELISA - 80%, IIF - 67%) and among patients treated with IST (ELISA - 63%, IIF - 50%). In control group, ELISA showed no positive results for PLA2R-Ab (specificity was 100%). The levels of proteinuria and eGFR were associated with autoantibodies determined by ELISA, both quantitative and semi-quantitative (proteinuria: r = 0.69, p = 0.001; eGFR: r = -0.38, p = 0.035) but not by IIF (proteinuria: r=0.33, p=0.061; eGFR: r=-0.26, p=0.082). The levels of PLA2R-Ab measured by ELISA correlated with the course of disease in patients treated with IST, while IIF did not show any dynamics is some cases. Conclusion Both quantitative and semi-quantitative ELISA were considered to be more preferable methods since the obtained results correlate with renal dysfunction and allow to assess the concentration of PLA2R-Ab in the course of disease more accurately, that may contribute to timely correction of treatment and improvement of outcome.

Diagnostic performance of glomerular PLA2R and THSD7A antibodies in biopsy confirmed primary membranous nephropathy in South Africans

Background:Serum and tissue-based tests using phospholipase A2 receptor 1 (PLA2R) and thrombospondin type-1 domain containing 7A (THSD7A) are established immune biomarkers for the diagnosis of primary membranous nephropathy (PMN). This study assessed the diagnostic performance of these biomarkers in the diagnosis of PMN in South Africans.MethodsThis was a cross-sectional analysis from a single centre in Cape Town, South Africa. Relevant biodata was collected from all patients. Histology, including slides for PLA2R and THSD7A were processed and assessed by typical microscopic and immunohistochemical features. Biopsy tissues of patients with membranous lupus nephritis (LN-V) and diabetic nephropathy (DN) were used as controls. The diagnostic accuracy for diagnosis of PMN using positive PLA2R and THSD7A were evaluated.ResultsOf the 88 patients included, 41 had PMN with a mean age of 44.5 ± 17.5 years and 61.0% were female. Histologically, PLA2R and THSD7A were only positive in the PMN group (51.2% and 4.9%, respectively) but negative in both control groups. The sensitivity of PLA2R and THSD7A for identifying PMN was 51.2% and 4.9%, respectively. The sensitivity of both tests together was 53.7% while the specificity and positive predictive values (PPV) for any of the tests (alone or in combination) was 100%. There was no difference in the sensitivity and specificity when using PLA2R alone compared to combining the two tests (p=0.32).ConclusionGlomerular staining of PLA2R and THSD7A could have potential diagnostic values in South Africans. This has implications on how immunotherapies can be initiated and used in these settings.

Autoantibodies against phospholipase A2 receptor in Brazilian patients with glomerular diseases

Recently, great progress has been made in understanding the pathogenesis of membranous nephropathy (MN) with the discovery of autoantibodies (Abs) to M-type phospholipase A2 receptor (PLA2R) in serum and in immunocomplexes deposited in glomerulus in most adult patients with primary MN. To evaluate the diagnostic performance of anti-PLA2R in Brazilian patients with MN, as well as to verify the possible association of anti-PLA2R serum levels with disease activity. 117 patients with glomerular diseases confirmed by renal biopsy underwent routinely clinical and laboratory evaluation (serum creatinine and albumin, 24-h proteinuria, urinalysis, tests for etiological investigation) and determination of serum anti-PLA2R by ELISA. 67.5% of the patients had MN, 9.4% focal segmental glomerulosclerosis, 7.7% lupus nephritis class V and 15.4%, other proteinuric glomerular diseases. The mean level of glomerular filtration rate (estimated by the CKD-EPI formula) was 79.43mL/min (12.00-151.20mL/min), 24h proteinuria of 2.89g (0-14.90g), serum albumin of 3.79g/dL (1.20-4.80g/dL). Anti-PLA2R was detected in 27 patients, all with active MN, being 26 primary and 1 secondary MN. Sensitivity and specificity rates for the test were 60.5-94.7%, and positive (PPV) and negative (NPV) predictive values were 92.9 and 67.9%, respectively. Anti-PLA2R showed high specificity and PPV for the diagnosis of primary MN in Brazilian patients. There was a strong correlation between disease activity and positive anti-PLA2R. This biomarker represents an important diagnostic tool for primary MN and may contribute to the monitoring of disease activity in such patients.

Noninvasive Diagnosis of Primary Membranous Nephropathy Using Anti-Phospholipase A2 Receptor (PLA2R) Antibodies: A Validation Study

Noninvasive Diagnosis of Primary Membranous Nephropathy Using Anti-Phospholipase A2 Receptor (PLA2R) Antibodies: A Validation Study

Histological grading in primary membranous nephropathy is essential for clinical management and predicts outcome of patients.

AimsDiagnosis of primary membranous nephropathy (PMN) is mainly based on immunofluorescence/immunohistochemistry findings. However, assessment of specific features on optical microscopy can help to estimate the severity of the disease, guide treatment and predict the response. The aim of this study was to identify, classify and grade the precise histological findings in PMN to predict renal function outcome and guide treatment.Methods and resultsHistological parameters, including focal segmental sclerosis (FSGS), tubular atrophy (TA), interstitial fibrosis (IF) and vascular hyalinosis (VH), were re‐evaluated in 752 patients with PMN. Their predictive value was estimated separately, and also in a combination score (FSTIV) graded from 0 to 4. Finally, the impact of histology was assessed in the response to immunosuppressive treatment. Mean age of patients was 53.3 (15–85) years and most presented with nephrotic syndrome. FSGS was present in 32% and VH in 51% of the patients, while TA and IF were graded as stage ≥1 in 52% and 51.4%, respectively. The follow‐up period was 122.3 (112–376) months. FSGS, TA and IF and VH were associated with impaired renal function at diagnosis (P = 0.02, P < 0.0001, P = 0.001 and P = 0.02, respectively) and at the end of follow‐up (P = 0.004, P < 0.0001, P < 0.0001 and P = 0.04, respectively). In multiple regression and binary logistic analysis, the presence of FSGS and degree of TA were the most significant parameters predicting renal function outcome, defined either by eGFR (end), FSGS (r = 0.6, P < 0.0001) and TA (r = 0.6, P < 0.0001), or by the endpoint of >50% eGFR reduction, FSGS (P = 0.001) and TA (P = 0.02). Also, patients presented with FSGS, IF, VH and/or with FSTIV > 1 could benefit from immunosuppression, regardless of clinical presentation.ConclusionsThe presence and degree of four histological indices, FSGS, VH, TA and IF, assessed separately or in combination, and FSTIV score not only predict renal function outcome after long‐term follow‐up, but can also help in the choice of appropriate treatment. Decisions concerning immunosuppressive treatment can be guided by pathology regardless of clinical findings.

Antibodies against M-Type Phospholipase A2 Receptor May Predict Treatment Response and Outcome in Membranous Nephropathy

Background: Anti-phospholipase A₂ receptor (PLA2R) antibodies are specific to the diagnosis of primary membranous nephropathy (pMN). The prevalence of positive antibodies varies among different cohorts. Still there is discrepancy in regard to the association between antibody levels and clinical courses, and the prognostic value of antibodies to treatment responses and kidney outcomes. Methods: Three hundred fifty-nine consecutive kidney biopsy-proven pMN patients were enrolled. Anti-PLA2R antibodies were detected by immunofluorescence assay (IFA) and enzyme-linked immunosorbent assay (ELISA). Results: The positive rate of anti-PLA2R antibodies in pMN was 65.2% (234/359) by IFA and 56.3% (202/359) by ELISA. The antibody level presented positive correlation with urinary protein excretion (r = 0.164, p = 0.002). Detectable antibodies and a higher level of proteinuria were independent risk factors to no-remission after treatments (OR 3.15, p = 0.004; OR 1.11, p = 0.006) and were independent risk factors to no-spontaneous remission (OR 2.20, p = 0.011; OR 1.36, p < 0.001). A higher level of antibodies (hazard ratio 1.002, p = 0.019) was the independent risk factor to kidney dysfunction during follow-up. The antibodies turned negative in 42 out of 52 (80.8%) patients who achieved clinical remission, while they remained positive in all patients of the no-response category (p < 0.001). Conclusion: We documented correlations between anti-PLA2R antibody levels and clinical severity in this large Chinese pMN cohort. Antibody positivity and higher antibody level might predict treatment responses and kidney outcomes of pMN.

Immunohistochemical Glomerular Expression of Phospholipase A2 Receptor in Primary and Secondary Membranous Nephropathy: A Retrospective Study in an Indian Cohort with Clinicopathological Correlations

Background: Limited published literature exists on the utility and standardization of anti-phospholipase A2 receptor (anti-PLA2R) immunohistochemistry (IHC) for the diagnosis of primary membranous nephropathy (MN). The study aimed to validate anti-PLA2R IHC for the diagnosis of primary MN and clinicopathological correlations in an Indian cohort. Methods: Subjects included patients with primary and secondary MN diagnosed between January 2012 and August 2014 with an adequate renal biopsy and at least 1 year of clinical follow-up. Anti-PLA2R IHC was performed in all cases with miscellaneous renal lesions as controls. Electron microscopy was performed in selected cases. Sensitivity and specificity of anti-PLA2R IHC to identify primary MN was evaluated. Histopathological analyses of primary and secondary MN were done with clinicopathological correlations including serum creatinine, eGFR, chronic kidney disease stage, 24-h urine protein, serum cholesterol, serum albumin, and hypertension at presentation and follow-up, using the Kruskal-Wallis test and Spearman rank correlation. A p value of ≤0.05 was considered statistically significant. Results: In 153 MN patients (99 primary, 54 secondary) and 37 miscellaneous controls, anti-PLA2R IHC differentiated primary from secondary MN with a sensitivity of 70.2% and a specificity of 96.6%. Secondary MN had increased mesangial matrix expansion compared to primary MN (p = 0.001). Severe nephrotic syndrome, impaired renal function, and hypertension were all more common in primary than in secondary MN. Conclusion: Anti-PLA2R IHC is a specific marker to distinguish primary MN from secondary MN.

Clinicopathological characteristics of M-type phospholipase A2 receptor (PLA2R)-related membranous nephropathy in Japanese

Recent studies have suggested that assessments of serum antibodies against M-type phospholipase A2 receptor (PLA2R) and the glomerular expression of PLA2R antigen in biopsy specimens are useful for the diagnosis of primary membranous nephropathy (MN). In this study, we assessed both of them and investigated the clinicopathological characteristics of PLA2R-related Japanese MN. We retrospectively enrolled 22 primary and 3 secondary Japanese patients whose serum samples and renal specimens were collected before treatment. According to the findings of serum antibodies and antigen in glomeruli, the primary MN patients were classified into PLA2R-related or -unrelated MN. We compared their clinicopathological findings, including IgG subclass staining, and electron microscopic findings, and evaluated the predictors of proteinuria remission. In primary MN, 16 patients (73 %) were classified into the PLA2R-related group, and 6 patients into the PLA2R-unrelated group. There was no significant difference in baseline laboratory data and electron microscopic findings, except for eGFR and serum IgG levels. IgG4-dominant deposition was more common in the related group (63 vs. 0 %). The 10 PLA2R-related patients with dominant IgG4 deposition had a lower rate and prolonged time in remission compared with the 6 PLA2R-related patients with non-dominant IgG4 (log-rank, p = 0.032). Furthermore, dominant IgG4 deposition was an unfavorable predictor of remission by multivariable Cox proportional hazard analysis. Assessments of both serum PLA2R antibodies and PLA2R antigen in glomeruli were more sensitive for the diagnosis of PLA2R-related MN, and among affected Japanese patients, those with dominant IgG4 deposition had worse clinical outcomes.