anti-PLA2R Antibodies Research Articles

SAT-009 Exploring novel biomarkers in Membranous Nephropathy using protein array platform

Membranous nephropathy (MN) is the leading cause of adult-onset nephrotic syndrome. Autoantibody biomarkers for MN include the landmark discovery of Anti-PLA2R antibody against phospholipase A2 receptor (PLA2R) with a prevalence of 50-70% followed by Thrombospondin Type-1 Domain-Containing 7A (THSD7A), with a prevalence of 2-3%. It is believed that yet undiscovered autoantibodies might be involved in the remaining 20-25% of MN patients. In this pilot study, we sought to identify a panel of candidate protein biomarkers in MN using the Sengenics™ Immunome protein array Single-center cohort study of 10 patients with biopsy proven MN (cases) and 10 individuals with biopsy proven minor glomerular abnormalities (controls), recruited at the Department of Renal Medicine of the Singapore General Hospital (SGH) between 1st January 2016 and 31st March 2017. Scientific Methods: After hybridizing the 20 serum samples on the Sengenics Immunome™ protein microarray slides, signals were detected using a microarray laser scanner at a 10μm resolution. The penetrance-based fold change (pFC) analysis method was implemented for the identification of antibodies against the proteins in each case sample, thus eliminating false positive signals from the data by setting a protein-specific threshold which was calculated on a per-protein basis via the mean +2 standard deviation intensity of the signal for each specific protein measured for the matched healthy control samples. Bioinformatics analyses were performed to identify and rank the biomarkers based on their sensitivity and specificity. Cases were 50% male, with 20% diabetic and 60% hypertensive, median age of 52.5years (IQR 48.5, 68.5), 90% Chinese, with median eGFR 76.5 (IQR 61.2, 111.7) and median proteinuria 5.61g (IQR 4.0, 7.4). Controls were race and gender matched with 50% male, 90% Chinese, with 40% diabetic and 80% hypertensive, median age of 53.5years (IQR 45.8, 59.8), median eGFR 74.3 (IQR 44.5, 100.8), median proteinuria 1.67g (IQR 0.6, 4.1). Both groups were comparable except for median proteinuria (p=0.035). A total of 328 biomarkers were identified and the top 15 are listed in Table 1. The top 5 biomarkers in our study show high differential expression in MN serum when compared to controls (see table 1). Mx1, a GTPase commonly involved downstream of the type I IFN pathway and associated with antiviral activity, has been found to be upregulated in lupus nephritis and its association with MN warrants further investigation. The presence of EEF1G in MN patients correlate to MN murine mice model studies that have shown differential expression of EEF1G, specifically subunit alpha, in MN kidney tissue when compared with normal kidneys. GSK3B, which has been found to be associated with diabetic nephropathy through microRNA and haplotype association studies, was prominently elevated in MN patients with diabetes versus diabetes alone and may be useful in the stratification between membranous nephropathy and diabetic nephropathy. From this pilot study, we have found a panel of potential candidate proteins that can be further studied in a larger scale protein profiling study which can eventually lead to the discovery of more specific biomarkers which can act as a management adjunct by accurately diagnosing, prognosticating and aid in treatment of MN.

Features of phospholipase A2 receptor and thrombospondin type-1 domain-containing 7A in malignancy-associated membranous nephropathy

AimsPhospholipase A2 receptor (PLA2R) and thrombospondin type-1 domain-containing 7A (THSD7A) were identified as pathogenic antigens in patients with membranous nephropathy (MN). Notably, PLA2R is detected in few patients with malignancy-associated...

Circulating antibodies against M-type phospholipase A2 receptor and thrombospondin type-1 domain-containing 7A in Chinese patients with membranous nephropathy.

M-type phospholipase A2 receptor (PLA2R) and thrombospondin type-1 domain-containing 7A (THSD7A) have recently been identified as target antigens for patients with idiopathic membranous nephropathy (IMN). The prevalence of PLA2R and THSD7A in the serum of MN patients deserves further investigation. Here, we studied the presence of anti-PLA2R and anti-THSD7A antibodies in patients with biopsy-proven IMN (n = 212), secondary membranous nephropathy (SMN, n = 118), and other kidney diseases (n = 84). The progress of 49 IMN patients [anti-PLA2R(+), n = 27; anti-THSD7A(+), n = 6; anti-PLA2R(-) and anti-THSD7A(-) dual negative, n = 16] who received immunosuppressive therapy was observed for 12months. Serum concentrations of antibodies against PLA2R and THSD7A were detected using an indirect immunofluorescent assay. One hundred fifty-two (71.7%) IMN patients and 11 (9.3%) SMN patients were identified as anti-PLA2R(+) anti-THSD7A(-). Five (2.4%) IMN patients and two (1.7%) SMN patients were identified as anti-THSD7A(+) anti-PLA2R(-). One of the IMN patients was identified as anti-PLA2R(+) and anti-THSD7A(+). The rate of partial remission was lower in anti-PLA2R(+) patients than in anti-PLA2R(-) patients 3months (P = 0.045) and 6months (P = 0.006) after immunosuppressive therapy. The rate of complete remission was lower in anti-PLA2R(+) patients than in anti-PLA2R(-) patients 12months (P = 0.037) after immunosuppressive therapy. The serum concentration of anti-PLA2R antibodies may be used as a sensitive and specific marker for diagnosing IMN. Immunosuppressive therapy is more effective for IMN patients who are anti-PLA2R(-) than for those who are anti-PLA2R(+).

Mercury-associated glomerulonephritis: a retrospective study of 35 cases in a single Chinese center

BackgroundLong-term exposure of mercury may induce glomerulonephritis. Clinical and pathological features of mercury-associated glomerulonephritis are not fully clear. This study retrospectively analyzed 35 cases of mercury-associated glomerulonephritis in a single Chinese center.MethodsThirty-five patients of mercury-associated glomerulonephritis were enrolled. Clinical data on diagnosis and during follow-up were collected. Plasma anti-phospholipase A2 receptor (PLA2R) antibody, glomerular PLA2R and glomerular IgG subclasses deposition were detected in the cases with membranous nephropathy (MN).ResultsMercury exposure was caused by skin lighting cream (20 patients), mercury-containing pills (9 patients), hair-dyeing agents (4 patients), and unidentified reasons (2 patients). All patients presented with proteinuria and normal renal function. The median of urinary protein was 4.6 (range 1.6~19.7) g/24 h. Twenty-two patients (62.9%) had nephrotic syndrome. Renal histopathology showed minimal change disease (MCD) in 21 patients (60.0%), MN in 13 (37.1%) and focal segmental glomerular sclerosis (FSGS) in 1 patient (2.9%). The proportion of MCD increased along with urinary mercury concentration (P = 0.024). In 13 cases of MN, all patients were negative for plasma anti-PLA2R antibody and glomerular PLA2R antigen. IgG1 (61.5%) and IgG4 (46.2%) deposits were noted along the glomerular capillary loops. Among the 16 patients received mercury detoxification monotherapy, 14 patients received 4.5 ± 2.8 (range 1~12) rounds of regimen and achieved complete remission in 4.5 (range 0.3~23.0) months, 2 patients stayed no remission.ConclusionsMCD was the most common pathological type of mercury-associated glomerulonephritis, followed by MN. The proportion of MCD increased along with the increase of urinary mercury concentration. Most patients could achieve complete remission after mercury detoxification.

Circulating anti-phospholipase A2 receptor antibodies as a diagnostic and prognostic marker in Greek patients with idiopathic membranous nephropathy - a retrospective cohort study.

Circulating autoantibodies against phospholipase A2 receptor (anti-PLA2R) are recognized as key elements in the pathogenesis of idiopathic membranous nephropathy. In current clinical practice, they are increasingly gaining attention as novel tools for diagnosis and disease monitoring. We investigated the diagnostic and prognostic utility of anti-PLA2R antibody measurements in Greek patients with biopsy-proven membranous nephropathy. Anti-PLA2R levels were measured in serum samples from 33 patients at diagnosis using ELISA and were associated with treatment outcome. Moreover, serial anti-PLA2R measurements were performed in 15 patients under different clinical conditions and level alterations were correlated with disease activity. Positive anti-PLA2R antibodies at diagnosis were found in 16 of 33 patients (48.5%). Anti-PLA2R levels were independently associated with the achievement of complete remission of nephrotic syndrome after immunosuppressive treatment compared to partial remission (p = 0.02, R2 = 0.265, 95%CI -0.019 to -0.0003). Higher detectable antibody levels at diagnosis were correlated with higher proteinuria levels (r = 0.813, p = 0.0001, 95%CI 0.532 to 0.933) and lower eGFR at the end of follow-up (r = -0.634, p = 0.0083, 95%CI -0.86 to -0.202). Serial antibody measurements during follow-up showed that anti-PLA2R titers were significantly reduced at the end of treatment after complete remission was achieved, remained low under sustained clinical remission, and increased during relapse. Our findings confirm the usefulness of anti-PLA2R measurements in the diagnosis of idiopathic membranous nephropathy. Low levels of anti-PLA2R antibodies at diagnosis are predictive of complete remission of nephrotic syndrome following immunosuppressive treatment. Serial anti-PLA2R measurements correlate well with clinical status throughout the follow-up period and could be used routinely for monitoring of disease activity and treatment planning.

FP224Differential gene expression between anti-PLA2R antibody positive and negative primary membranous nephropathy

FP224Differential gene expression between anti-PLA2R antibody positive and negative primary membranous nephropathy

Interaction between PLA2R1 and HLA-DQA1 variants contributes to the increased genetic susceptibility to membranous nephropathy in Western China.

Recent studies showed that single nucleotide polymorphisms (SNP) within the phospholipase A2 receptor (PLA2R1) and human leukocyte antigen complex class II HLA-DQα-chain 1 (HLA-DQA1) genes were associated with the susceptibility to patients with primary membranous nephropathy (PMN). However, the results of previous research have not been always consistent. We performed a case-control study including 314 patients with PMN and 354 healthy subjects in Western China. Eight SNP in PLA2R1 and one SNP in HLA -DQA1 were genotyped and association between PLA2R1 and HLA-DQA1 was investigated. One hundred and twenty patients were detected anti-PLA2R antibodies to analyze the association between genotype and anti-PLA2R antibody. We found A allele of rs2715918 (odds ratio (OR) = 1.66, corrected P values (Pc) = 7.9 × 10-3 ), A allele of rs4665143 (OR = 1.76, Pc = 2.7 × 10-6 ) and A allele of rs2187668 (OR = 3.29, Pc = 8.0 × 10-11 ) were associated with PMN. Susceptibility of PMN was significantly increased with rs2715918 in dominant model (OR = 1.624, Pc = 5.0 × 10-2 ), rs4665143 in recessive model (OR = 2.134, Pc = 1.4 × 10-4 ) and rs2187668 in dominant model (OR = 3.961, Pc = 4.1 × 10-11 ). The haplotype ATAC of rs2715918, rs6757188, rs4665143, rs3749119 was associated with the high risk of PMN (OR = 1.453, P = 3.0 × 10-4 ). Interaction of rs2715918 GA/AA, rs4665143 GA/AA and rs2187668 GA/AA could significantly increase the 10.61-fold higher risk for the development of PMN (OR = 10.61, P = 4.0 × 10-10 ). Patients who carried with risk genotypes for both HLA-DQA1 and PLA2R1 (87.8%) had antibodies positivity. However, patients who carried low-risk genotypes (41.6%) had antibodies positivity (P = 0.001). There are some differences in PLA2R1 distributions in PMN patients between previous literature and our study. Our results showed that interactions between PLA2R1 and HLA-DQA1 alleles increased genetic susceptibility to PMN in Western China.

The investigative burden of membranous nephropathy in the UK.

BackgroundMembranous nephropathy (MN) represents two distinct disease entities. Primary MN is now recognized as an autoimmune condition associated with the anti-PLA2R antibody and secondary MN occurs in tandem with malignancy, infection, drug therapy and other autoimmune conditions. Prior to the development of accessible enzyme-linked immunosorbent assays, the diagnosis of MN was one of exclusion. We studied whether the introduction of serum anti-PLA2R antibody testing leads to a reduction in the frequency of investigations in MN patients.MethodsPatients from three UK centres with a diagnosis of MN between 2009 and 2014 were identified. We compared patients who had a positive anti-PLA2R test within 6 months of biopsy with those who had no test or a negative test. Records were reviewed for investigations that took place 6 months prior to and 6 months following the biopsy date to see if these were normal or identified a secondary cause of MN.ResultsIn total, 184 patients were included: 80 had no test, 66 had a negative anti-PLA2R test and 38 had a positive test within 6 months of diagnosis. In 2012, 46.5% of patients had an anti-PLA2R test, increasing to 93.3% in 2014. From 2012 to 2014 the number of screening tests dropped from 10.03 to 4.29 and the costs from £497.92 to £132.94.ConclusionsSince its introduction, a progressively higher proportion of patients diagnosed with MN had an anti-PLA2R test. This has led to a reduction in the number of screening tests and in the cost of investigations carried out. The anti-PLA2R test has the potential to reduce this burden as its use becomes more widespread.

The relationship of anti-phospholipase A2 receptor antibody and C5a complement with disease activity and short-term outcome in idiopathic membranous nephropathy

The binding of anti-phospholipase A2 receptor (anti-PLA2R) antibody to podocyte and complement activation is the mechanisms of idiopathic membranous nephropathy (IMN). C5a, a complement activation end product, is a strong inflammatory cell stimulator and can influence the behavior of T cells and dendritic cells. This study examined the etiology-disease relationship and significance of auto-antibody and C5a with short-term remission. Plasma anti-PLA2R antibody and C5a were measured with the blood samples that were collected when patients were admitted for renal biopsy. The deposition of IgA, IgG, IgM, C1q and C3c in glomerulus was graded according to immunofluorescence staining. The relationship of anti-PLA2R antibody with C5a, glomerular immunoglobulin and complement deposition was examined. Antibody and C5a levels as predictors of short-term remission were also examined. In 72 IMN patients, 50 patients had positive plasma anti-PLA2R antibody. The antibody had positive correlation to proteinuria. Patients with high grade IgG or C3c, but not IgA/IgM/C1q, deposition had higher anti-PLA2R antibody titers. C5a was increased in IMN patients, but had no correlation with anti-PLA2R antibody or proteinuria. The analysis revealed that C5a, not initial anti-PLA2R antibody, was a predictor associated with 12-month remission in patients receiving immunosuppression with multivariate-adjusted OR 0.74 (95% CI, 0.58-0.94, P=0.01). This study provides indirect evidences of etiology-disease relationship of anti-PLA2R antibody in IMN patients. The role of C5a, a predictor of remission, in the disease course of MN and the influences on inflammatory cells in MN patients is worth to be clarified.

Clinical significance of autoantibodies in the assessment and treatment of idiopathic membranous nephropathy.

The present study aimed to explore the correlation between the dynamic serum levels of phospholipase A2 receptor (PLA2R), aldose reductase (AR) and superoxide dismutase 2(SOD2) antibodies with disease activity and treatment response in patients with idiopathic membranous nephropathy (IMN). The present study included 56 patients with IMN who were diagnosed through a renal biopsy and presenting with nephrotic syndrome. The patients were divided into two treatment groups: One treated with cyclophosphamide (CTX) and one with tacrolimus (FK506). Serum was collected prior to treatment, and at 1, 3, 6, 9 and 12 months after the start of the 12-month-long therapy. Samples were tested by ELISA to measure anti-PLA2R, anti-AR and anti-SOD2 antibody titers. In addition, urinary protein excretion, serum albumin (Alb) and other blood biochemical indexes were measured. Theanti-PLA2R antibody positivity rate was 71.43% in the patients prior to treatment. After 12 months of treatment, proteinuria and PLA2R antibody levels were decreased, whereas serum Alb was increased. There was no significant difference of remission rates between the CTX and FK506 groups. In conclusion, the results of the present study indicate that the anti-PLA2R antibody level is correlated with the severity of IMN, whereas anti-AR and anti-SOD2 antibody levels are not. In addition, there was no significant difference between the CTX and FK506 groups in regards to the remission rates of patients with IMN.

Analysis of predictive factors for immunosuppressive response in anti-phospholipase A2 receptor antibody positive membranous nephropathy

BackgroundSerum anti-phospholipase A2 receptor (PLA2R) antibody was correlated with disease activity of membranous nephropathy(MN). The predictive value of antibody titer changes on immunosuppressive response remains unknown. We investigated predictive value of dynamic change of anti-PLA2R antibody and 24-h urine protein (24hUP) for clinical response of MN.MethodsThis was a retrospective cohort study including 47 Chinese MN patients with positive anti-PLA2R antibody in a tertiary referral hospital between January 2012 and March 2014. Patients received cyclophosphamide (CTX, n = 23), or cyclosporine (CYA, n = 24) regimen, respectively. We monitored serum anti-PLA2R titer and 24hUP at one, three and six-month follow-up.ResultsAt baseline, total patients were 42 ± 14 years old with 29/18 male/female ratio. The median 24hUP was 5.80(3.56,9.41) g/d. The median baseline anti-PLA2R antibody titer was 66.4(31.9, 188.0) RU/mL. Baseline 24hUP and eGFR between subgroups were not significantly different. The differences of relative reduction between antibody titer and 24hUP at one month were statistically significant (CTX group 94.2% vs. 46.8%, P < 0.001; CYA group 54.6% vs. 4.6%, P = 0.04). Only in CTX group, the relative reduction of 24hUP at one month was correlated with composite remission at six-month(P = 0.03). Area under the curve of 24hUP relative reduction in CTX group at one-month for predicting composite remission at six months was 0.85(95%CI 0.65~1.05, P = 0.04). The cutoff value of one-month’s 24hUP relative reduction for predicting six-month’s composite remission in CTX group was 15.3%, with high sensitivity (83.3%) and specificity (100%).ConclusionsCompared with relative reduction of antibody titer, relative reduction of 24hUP at one-month follow-up in CTX group had a better predictive value for six-month’s composite remission.

Chronic Inflammatory Demyelinating Polyneuropathy With Concurrent Membranous Nephropathy: An Anti-paranode and Podocyte Protein Antibody Study and Literature Survey.

Background: Several case reports have described the concurrence of chronic inflammatory demyelinating polyneuropathy (CIDP) and membranous nephropathy (MN). The presence of autoantibodies against podocyte antigens phospholipase A2 receptor (PLA2R) and thrombospondin type 1 domain containing 7A (THSD7A) in MN suggests an autoimmune mechanism. Some CIDP patients also harbor autoantibodies against paranodal proteins such as neurofascin 155 (NF155) and contactin-1 (CNTN1). We investigated the relationship between CIDP and MN by assaying autoantibodies against paranodal and podocyte antigens in a CIDP patient with MN, and by a literature survey on the clinical features of CIDP with MN.Methods: Anti-CNTN1 and NF155 antibodies were measured by flow cytometry using HEK293 cell lines stably expressing human CNTN1 or NF155. Binding capacity of antibodies was validated by immunostaining mouse teased sciatic nerve fibers. Anti-PLA2R antibodies were measured by enzyme-linked sorbent assay and anti-THSD7A antibodies by indirect immunofluorescence assay. Clinical features between 14 CIDP with MN cases including two with anti-CNTN1 antibodies and 20 anti-CNTN1 antibody-positive CIDP cases were compared.Results: A patient whose ages was in the late 70 s complained of progressive weakness and superficial and deep sensory impairment in four extremities over 6 months. Nerve conduction studies showed prominent demyelination patterns. The patient presented with nephrotic syndrome. Renal biopsy disclosed basement membrane thickening with local subepithelial projections and glomerular deposits of IgG4, compatible with MN. Autoantibody assays revealed the presence of IgG4 and IgG1 anti-CNTN1 antibodies, but an absence of anti-NF155, anti-PLA2R, and anti-THSD7A antibodies. The patient's serum stained paranodes of teased sciatic nerves. CIDP with MN and anti-CNTN1 antibody-positive CIDP commonly showed male preponderance, relatively higher age of onset, acute to subacute onset in 35–50% of cases, distal dominant sensorimotor neuropathy, proprioceptive impairment leading to sensory ataxia, and very high cerebrospinal fluid protein levels. However, 11 of 13 CIDP patients with MN had a favorable response to mono- or combined immunotherapies whereas anti-CNTN1 antibody-positive CIDP was frequently refractory to corticosteroids and intravenous immunoglobulin administration.Conclusion: CIDP with MN and anti-CNTN1 antibody-positive CIDP show considerable overlap but are not identical. CIDP with MN is probably heterogeneous and some cases harbor anti-CNTN1 antibodies.

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.

Anti-phospholipase A2 receptor antibody as a prognostic marker in patients with primary membranous nephropathy.

BackgroundPhospholipase A2 receptor (PLA2R) has been identified as a major autoantigen in primary membranous nephropathy (MN). We evaluated the association between anti-PLA2R antibodies and clinical outcome in Korean patients with primary MN.MethodsA total of 66 patients with biopsy-proven MN were included. Serum level of anti-PLA2R antibodies was measured by enzyme-linked immunosorbent assay. Biochemical parameters were estimated initially and at follow-up.ResultsAnti-PLA2R antibodies were detected in 52.1% and 27.8% of patients with primary and secondary MN, respectively. Forty-eight patients with primary MN were grouped based on presence or absence of anti-PLA2R antibodies. Proteinuria was more severe in anti-PLA2R-positive patients than in anti-PLA2R-negative patients (urine protein/creatinine ratio 7.922 ± 3.985 g/g vs. 4.318 ± 3.304 g/g, P = 0.001), and anti-PLA2R antibody level was positively correlated with proteinuria. The incidence of chronic kidney disease stage ≥ 3 was higher in anti-PLA2R-positive patients compared with anti-PLA2R-negative patients (P = 0.004). The probabilities of spontaneous remission were higher in anti-PLA2R-negative patients compared with anti-PLA2R-positive patients (P < 0.001). Multivariate analysis demonstrated that anti-PLA2R antibodies are an independent risk factor for developing chronic kidney disease stage ≥ 3 and for not reaching spontaneous remission.ConclusionDetection of anti-PLA2R antibodies at diagnosis in patients with primary MN can predict prognosis and guide treatment decisions.

Clinical value of a serum anti-PLA2R antibody in the diagnosis and monitoring of primary membranous nephropathy in adults.

ObjectiveTo compare the positive rate of anti-PLA2R antibodies in patients with primary membranous nephropathy (PMN), secondary membranous nephropathy (SMN), and non-membrane nephropathy (non-MN); evaluate serum anti-PLA2R antibodies in the diagnosis of PMN; quantify the serum anti-PLA2R antibody levels during the treatment of PMN patients; and evaluate the clinical value of monitoring changes in serum anti-PLA2R antibody quantification levels.MethodsThe kidney tissue was collected by kidney biopsy. The expression of PLA2R in glomeruli was detected by immunofluorescence, and ELISA was used to quantify the serum anti-PLA2R antibody. The positive rate of PLA2R expression in renal tissue and positive rate of the anti-PLA2R antibody in the three groups were compared and calculated using a statistical method. The specificity and coincidence rate of anti-PLA2R used in the differential diagnosis of PMN and SMN were evaluated. The clinical value of monitoring changes in serum anti-PLA2R antibody quantification levels was evaluated.ResultThe serum levels of the anti-PLA2R antibody were significantly higher in patients with PMN than in patients with SMN and non-MN group. The difference was statistically significant (P<0.05). The serum anti-PLA2R antibody became negative in the complete remission group. The serum anti-PLA2R antibody levels were significantly lower than before treatment in the partial remission group, and the difference was statistically significant (P<0.05). However, in the non-remission group, the serum anti-PLA2R antibody levels remained high.ConclusionDetection of the serum anti-PLA2R antibody has a high specificity for diagnosing PMN. The change of the serum anti-PLA2R antibody level is closely related to the status of the PMN: if the anti-PLA2R antibody level has decreased, it indicates that the condition has improved; and if the serum anti-PLA2R antibody continues to show high levels of positive or quantitative increase, the condition is not in remission or has relapsed.

Clinical implications of pathological features of primary membranous nephropathy

BackgroundThe clinical outcome varies considerably in primary membranous nephropathy (pMN). Risk factors for kidney prognosis include ageing, male gender, persistent heavy proteinuria, decreased eGFR at presentation, persistent elevation of anti-PLA2R antibodies, no remission, and so on. It was controversial whether the histopathological features of pMN could predict treatment response and kidney outcome.MethodsA retrospective study was conducted in 371 patients with biopsy-proven pMN. Pathological parameters included immunofluorescence staining, membranous Churg’s stages, sclerosis, crescent, focal segmental sclerosis lesion, chronic and acute tubulointerstitial injury. The fluorescence intensity was determined: 0, negative; 1, weak; 2, moderate; 3, strong; 4, glaring. Chronic tubulointerstitial injury was graded by the involved area: 0, 0–5%; 1, 6–25%; 2, 26–50%; 3, > 50%.ResultsWe found that patients with higher intensity of C3 staining, advanced membranous stage, and more severe chronic tubulointerstitial injury presented with higher positivity rate of anti-PLA2R antibodies, higher levels of urinary protein excretion and serum creatinine, and lower level of serum albumin. Univariate Cox regression analysis showed that severe (grade = 3) chronic tubulointerstitial injury was a risk factor to the kidney outcome of ESKD (HR = 61.02, 95%CI, 7.75–480.57, P < 0.001) and over 50% reduction of eGFR (HR = 4.43, 95%CI, 1.26–15.6, P = 0.021). Multivariate analysis demonstrated it as an independent risk factor to ESKD (HR = 25.77, 95% CI, 1.27–523.91, P = 0.035). None of the pathological parameters exerted any influence on treatment response (P > 0.05).ConclusionsWe found the prognostic role of chronic tubulointerstitial injury to the kidney outcome of pMN. This study highlighted the value of kidney biopsy under the widespread usage of anti-PLA2R antibodies for diagnosis and prognosis.

Comparative analysis of membranous and other nephropathy subtypes and establishment of a diagnostic model

This study aimed to compare clinical features between membranous nephropathy (MN) and nonmembranous nephropathy (non-MN), to explore the clinically differential diagnosis of these two types, and to establish a diagnostic model of MN. After renal biopsy was obtained, 798 patients were divided into two groups based on their examination results: primary MN group (n = 248) and non-MN group (n = 550). Their data were statistically analyzed. Logistic regression analysis indicated that anti-PLA2R antibodies, IgG, and Cr were independently correlated with MN, and these three parameters were then used to establish the MN diagnostic model. A receiver operating characteristic (ROC) curve confirmed that our diagnostic model could distinguish between patients with and without MN, and their corresponding sensitivity, specificity, and AUC were 79.9%, 89.4%, and 0.917, respectively. The cutoff value for this combination in MN diagnosis was 0.34. The established diagnostic model that combined multiple factors shows a potential for broad clinical applications in differentiating primary MN from other kidney diseases and provides reliable evidence supporting the feasibility of noninvasive diagnosis of kidney diseases.

Anti-Phospholipase A2 Receptor Antibodies as Diagnostic Modality in Primary Idiopathic Membranous Nephropathy

Background Phospholipase A2 receptor (PLA2R), an IgG4 subclass antibody, is being extensively studied for diagnosis, monitoring and prognostication of cases of primary membranous nephropathy (MN). There is significant heterogeneity within the studies with most of the work targeted towards circulating PLA2R antibody. The present study evaluates PLA2R glomerular staining in primary MN as a diagnostic test in conjunction with the serology. Methods: Diagnostic study. We studied paraffin-embedded kidney biopsies of 60 patients with biopsy-proven MN, for the presence of PLA2R in glomerular immune deposits utilising immunohistochemistry. 60 cases of non MN cases along with autopsy renal tissue were used as controls. A subset of patients (n=40) were tested for circulating PLA2R antibody using quantitative sandwich enzyme immunoassay. Results: Positive PLA2R expression was present in 37/39 (94.8%) cases of primary MN, 5/21 (23.8% ) of secondary MN and 4/60 (6.6%) of non MN group. The expression was detected along glomerular basement membrane in granular pattern of varying intensities. Circulating anti-PLA2R antibodies were detected in 71.42% of primary MN cases, 8.3% of secondary MN cases and non MN group. PLA2R immunostaining exhibited higher sensitivity and modest specificity for differentiating primary from secondary MN (ROC-AUC :0.885 of IHC vs ROC-AUC: 0.776 of serology). The immunostaining however required precision and expertise to read the results. Conclusion: Tissue staining of PLA2R antibody in renal biopsies will be complementary to serology and two done in conjunction will be better discriminator between primary and secondary MN.

PLA2R: The Same Target Antigen of Idiopathic Membranous Nephropathy and Hashimoto's Thyroiditis?

Background: Autoimmune thyroid disease associated nephropathy was identified 40 years ago; however, the cause of the disease remains unknown. Methods: Phospholipase A2 receptor (PLA2R) antibodies was assayed quantitatively in the serum of patients with Graves' disease, Hashimoto's thyroiditis (HT), idiopathic membranous nephropathy (IMN) and normal controls by time-resolved fluoroimmunoassay. PLA2R antigens were immunohistochemically analyzed in the thyroid tissue with Graves' disease and HT, as well as the nephridial tissue with IMN. Findings: The concentration of phospholipase A2 receptor (PLA2R) antibodies in the serum of normal controls, patients with Nodular goiter, Graves' disease and HT, as well as patients with IMN was 1.13 ± 0.43 mg/L, 1.07 ± 0.22mg/L, 2.12 ± 2.11mg/L, 8.07 ± 4.74mg/L, and 15.91 ± 19.50mg/L, respectively. The concentration of PLA2R antibodies in the serum and its areas under the curve of ROC in HT and IMN cases increased significantly. The immunohistochemistry revealed that the tissues of the patients with HT were obviously stained, with a positive rate of 66.67%. Interpretation: PLA2R may be a pathogenic target antigen for HT, and the production of anti-PLA2R antibodies may cause autoimmune thyroid disease associated nephropathy. Funding Statement: Clinical Medical Science fund of Jiangsu Province (No. BL2014022), Jiangsu Maternal and Child Health Research Project (FRC201741), and Wuxi City Science and Education Project (ZDRC006) supported the study. Declaration of Interests: All Authors declare no competing financial interests. Ethics Approval Statement: Patients from Jiangsu Jiangyuan Hospital and the Wuxi People’s Hospital affiliated to Nanjing Medical University, were enrolled. The study protocol was approved by the medical ethics committee of Jiangsu Jiangyuan Hospital and Affiliated Wuxi People's Hospital of Nanjing Medical University.

Clinical and Histological Features of Phospholipase A2 Receptor-Associated and Thrombospondin Type-I Domain-containing 7A-Associated Idiopathic Membranous Nephropathy: A Single Center Retrospective Study from China

BackgroundM-type phospholipase A2 receptor (PLA2R) was identified as the major target antigen in idiopathic membranous nephropathy (IMN). Another target antigen, namely thrombospondin type-1 domain-containing 7A (THSD7A), was recently detected in approximately 10% of non-PLA2R-associated IMN. In this single center retrospective study, clinical and histological features of PLA2R-associated and THSD7A-associated IMN patients were evaluated.Material/MethodsA total of 192 IMN patients, who were receiving no glucocorticoids or immunosuppressant before renal biopsy, were enrolled in this study and followed for a median duration of 25.5 months. IMN with enhanced glomerular PLA2R and THSD7A staining by immunohistochemistry (IHC) were designated as PLA2R-associated IMN and THSD7A-associated IMN respectively. Serum anti-PLA2R and anti-THSD7A antibodies levels were assessed by enzyme linked immunosorbent assay and indirect immunofluorescence testing in PLA2R-associated and THSD7A-associated IMN.ResultsOf 192 IMN patients, 164 patients (85.4%) had PLA2R-associated IMN and 3 patients (1.6%) had THSD7A-associated IMN. Compared with non-PLA2R-associated IMN patients, the 24-hour urinary protein levels were significantly higher (P=0.008), whereas, the proteinuria remission rates were significantly lower (P=0.03) in PLA2R-associated IMN patients. No pathological differences were found between PLA2R-associated IMN and non-PLA2R-associated IMN. Among 3 THSD7A-associated IMN patients, 1 patient had elevated serum anti-THSD7A antibody levels, which was below detectable levels after achieving partial proteinuria remission with combined glucocorticoid and cyclosporine treatment.ConclusionsCompared with non-PLA2R-associated IMN patients in our cohort, PLA2R-associated IMN patients presented with more severe proteinuria and lower remission rates after treatment, with no distinct histological differences. Glomerular expression of PLA2R could be a useful marker to indicate the severity, treatment response, and prognosis of IMN.