anti-PLA2R Antibodies Research Articles

Stability of important antibodies for kidney disease: pre-analytic methodological considerations.

BackgroundThe importance of circulating antibodies as biomarkers of kidney disease has recently been recognized. However, no study has systematically described the methodology of sample preparation and storage regarding antibodies as biomarkers of kidney disease. It remains unknown whether repetitive freeze-thaw cycles, physical disturbances, storage at different temperatures or for different periods of time, or haemolytic or turbid serum samples affect antibody measurements. The aim of this study was to investigate the stabilities of antibodies associated with kidney disease in serum samples under various relevant clinical and research conditions.MethodsWe stored serum samples in the following different conditions: repetitive freeze-thaw cycles (1, 6 or 12 times), long-term storage (7 or 12 months at −80 °C), physical disturbance (1 or 8 h), and storage at 4 °C (1, 3 or 6 weeks) and room temperature (1 or 7 days). The stabilities of the anti-phospholipase A2 receptor (anti-PLA2R), anti-glomerular basement membrane, anti-myeloperoxidase and anti-proteinase 3 antibodies were evaluated with enzyme-linked immunosorbent assays (ELISA).ResultsWe found that repetitive freeze-thaw cycles did not have a significant effect on the stabilities of the abovementioned antibodies in clear serum samples. The ELISA readings of haemolytic and turbid serum samples tended to increase and decrease, respectively. Neither long-term storage at −80 °C nor physical disturbance had a significant effect on anti-PLA2R antibody stability in sealed serum samples. The concentrations of most of these antibodies increased in unsealed serum samples that were stored at 4 °C for more than 6 weeks or at room temperature for more than 7 days.DiscussionOur findings revealed that the abovementioned circulating antibodies that are used as biomarkers for kidney disease had stable physicochemical properties, structures and immunoreactivities such that they were not influenced by repetitive freeze-thaw cycles, physical disturbances or long-term storage at −80 °C. However, the ELISA readings tended to change for haemolytic, turbid and unsealed serum samples.

Clinical and prognostic significance of glomerular C1q deposits in primary MN

BackgroundAlthough complement activation is believed to be important in mediating PMN, the pathways involved and clinical consequences remain controversial. Many cases of idiopathic or primary membranous nephropathy (PMN) present with subepithelial C1q deposits along with IgG and C3 on glomerular capillary walls but without deposits of IgA or IgM (“full house”) by immunofluorescence or any causes of secondary MN. We sought to define the clinical and pathological significance of these C1q deposits in PMN by comparing a variety of clinical parameters, outcomes and other serum and urine factors in patients with and without significant glomerular C1q deposits. MethodsTwo-hundred eighty-eight patients with biopsy-proven PMN were enrolled. We compared the clinical and pathological features, treatment responses and kidney outcomes, between patients with and without C1q deposition. Circulating anti-PLA2R antibodies and complement components in plasma and urine were detected by ELISA. ResultsGlomerular C1q deposition was detected on capillary walls by immunofluorescence in 66/288 (22.9%) patients. C1q-positive patients presented with lower concentrations of serum IgG (5.3 ± 3.1 vs. 6.6 ± 3.5 g/l, p = 0.008), a higher frequency of IgA (37.9% vs. 15.8%, p < 0.001), IgM (48.5% vs. 31.5%, p = 0.011) and C3c (100% vs. 88.3%, p = 0.004) deposits in glomeruli and more stage III of MN (24.2% vs. 11.7%, p < 0.001) by pathologic criteria. Other features, including gender, age, anti-PLA2R antibody positivity and concentrations, proteinuria, albumin and serum creatinine, were not different between the patients with and without C1q deposition (p > 0.05). The IgG subclasses of anti-PLA2R antibodies in circulation or in glomeruli showed no difference (p > 0.05). C1q deposition, and C1q concentrations in circulation and urine had no apparent effect on the treatment responses or kidney outcomes (p > 0.05). ConclusionThe classical pathway of complement is activated in some patients with PMN, but may not play an essential role in mediating the kidney injury seen in this disease.

Expression of phospholipase A2 receptor and IgG4 in patients with membranous nephropathy.

ObjectivesThe aims of this study were to detect the expression of M phospholipase A2 receptor (PLA2R) in the kidney tissue of patients with idiopathic membranous nephropathy (IMN), secondary membranous nephropathy (SMN), and the nonmembranous nephropathy (non-MN), to evaluate the value of PLA2R in the kidney tissue and serum anti-PLA2R antibody in the diagnosis of membranous nephropathy (MN), and to explore the relationship between PLA2R of the kidney tissue or serum anti-PLA2R antibody and clinical features of MN.MethodsThe kidney tissue was collected by kidney biopsy. Immunofluorescence assay was used to detect the level of PLA2R and IgG4 antigen in kidney tissue. Furthermore, the level of the PLA2R was detected using the enzyme-linked immunosorbent assay (ELISA). The positive and negative rates of PLA2R and IgG4 in different diseases and the sensitivity and specificity, were calculated using the statistical method. The specificity and coincidence rate of PLA2R or anti-PLA2R used in the differential diagnosis of IMN and SMN were evaluated.ResultsThe expression intensities of anti-PLA2R antibody and IgG4 were significantly higher in patients with IMN than in patients with SMN but are not non-MN. There was no significant difference in anti-PLA2R antibody and IgG4 in patients with SMN and non-MN. The coincidence rate of serum anti-PLA2R antibody and PLA2R in kidney tissue was 100%.ConclusionThe expression of PLA2R and IgG4 antibody had great significance in the pathological diagnosis of MN. The detection of the serum anti-PLA2R antibody had great diagnostic value in diagnosing MN.

Membranous nephropathy associated with pregnancy: an anti-phospholipase A2 receptor antibody-positive case report.

Pregnancy and membranous nephropathy (MN) can occur concurrently with nephrotic syndrome. However, the pathophysiology of MN associated with pregnancy remains unclear, including the involvement of anti-M-type phospholipase A2 receptor (PLA2R) antibody, the major antigen of idiopathic MN (iMN). A treatment for the condition is also not established. We present the case of a 43-year-old pregnant female with incidental proteinuria and hypoalbuminemia. We made a diagnosis of nephrotic syndrome at 11 week gestation. Renal biopsy revealed iMN using predominant granular staining of IgG4 along the glomerular basement membrane. No secondary cause was identified. Oral glucocorticoid therapy was started from 17 week gestation and induced complete remission at 28 week gestation. A healthy infant was born at 38 week gestation. Glucocorticoid therapy was stopped postpartum without MN relapse. Anti-PLA2R antibody was later found to be positive using serum reserved from before treatment. In conclusion, we presented the case of a pregnant woman with iMN and anti-PLA2R antibodies, whose nephrotic syndrome was successfully controlled with oral glucocorticoids to reach complete remission, even after tapering off the medication. Pregnancy per se might be associated with iMN onset.

The clinicopathological features of patients with membranous nephropathy.

BackgroundMembranous nephropathy (MN) represents a distinct glomerular disease which has been considered as a major cause of nephrotic syndrome (NS) in adults. Evidences show that the clinicopathological features of MN are various among MN cases. This study aimed to summarize and analyze the clinicopathological features of patients with MN.MethodsA total of 231 MN patients were recruited in this study. Their clinical and pathological features were collected and analyzed according to their age, gender, pathological stages, and anti-phospholipase A2 receptor (anti-PLA2R) antibodies tests.ResultsAmong the 231 MN cases, the ratio of male to female was 1.47 and the mean age was 47.43±14.32 years. Altogether, 163 (70.6%) cases were positive for NS. Their serum antiPLA2R, body mass index, total cholesterol, triglyceride, low density lipoprotein cholesterol, D2, IgA, and IgE were increased, but IgG was decreased. The majority of the patients were middle aged and old aged. In addition, the pathological stage was significantly correlated with gender (P=0.038), creatinine, (P=0.021) and IgE (P=0.003). A total of 74.9% MN patients were found to be positive for anti-PLA2R antibodies, and they were more likely to have abnormal serum indices.ConclusionThe major clinicopathological characteristics of MN patients are summarized in this study. Male and elder MN cases are likely to have rapid disease progression. Advanced pathological stages and being positive for anti-PLA2R antibodies may be potential indicators for disease activity of MN.

Phospholipase A2 receptor (PLA2R) related membranous nephropathy - not specific for idiopathic cases any more

Context: Membranous nephropathy is among the most common causes of nephrotic syndrome in adults. Evidence Acquisitions: PubMed, EBSCO, Web of Science, directory of open access journals (DOAJ), EMBASE, and Google Scholar with keywords of phospholipase A2 receptor, PLA2R, membranous nephropathy, nephrotic syndrome, idiopathic nephrotic syndrome and glomerulonephritis have been searched. Results: The recent finding that around 70%-80% of the idiopathic cases of membranous nephropathy express Phospholipase A2 receptor (PLA2R) in their kidney biopsies and antiPLA2R antibody in their serum was initially considered specific to the idiopathic cases. However, more recent studies have shown that while PLA2R glycoprotein expression, and anti-PLA2R antibodies, are specific to membranous nephropathy and are not seen in other glomerulonephritides, they can be as frequently expressed in certain secondary forms of membranous nephropathy. Conclusions: In this communication we intend to briefly review the new data regarding tissue and sero-positivity for PLA2R in different types of secondary membranous nephropathy, as well as pathologic and immunofluorescence features of them as compared to the idiopathic cases.

The significance of anti-PLA2R antibody for the diagnosis and treatment of idiopathic membranous nephropathy

Objective To observe the expression of serum anti-PLA2R antibody and analyze its clinical significance in patients with idiopathic membranous nephropathy (IMN). Methods A total of 36 patients with nephrotic syndrome were diagnosed as IMN by renal biopsy in our hospital from April 2015 to November 2016, and enrolled in the study. All these patients were treated with prednisone and cyclosporine A for 6 months. Creatinine clearance rate(Ccr), 24-hour total proteinuria(TUpro) and plasma albumin(Alb) were collected before and after treatment. Serum anti-PLA2R antibody was also assayed by enzyme-linked immuno sorbent assay (ELISA) at the same time. All the data were prepared for statistical analysis. Results Among the 36 patients with IMN, positive serum anti-PLA2R antibody in 28(77.7%) cases were found, and there were no significant differences in age, gender, prevalence of hypertension and type 2 diabetes mellitus between anti-PLA2R antibody positive and negative groups(P>0.05). The initial and post-therapeutic values of anti-PLA2R antibody was significantly correlated with corresponding values of both TUpro and serum albumin levels, respectively(P 0.05). In comparison with anti-PLA2R antibody negative group, there were significantly higher TUpro and lower Alb levels in anti-PLA2R antibody positive group (P 0.05). Twelve patients got anti-PLA2R antibody negative and 7 patients had complete remission in anti-PLA2R antibody positive group after treatment, all the 7 patients′ anti-PLA2R antibody became negative. Fore out of eight patients without anti-PLA2R antibody entered into complete remission, accounted for 50%. The prevalence of remission in anti-PLA2R antibody negative group was higher than that in anti-PLA2R antibody positive one, but there was no statistic significance(P>0.05). Conclusions The serum anti-PLA2R antibody by non-invasive technic is a specific biomarker for diagnosis of IMN. It is of tremendous significance for serum anti-PLA2R antibody to guide clinical diagnosis and predict prognosis in IMN patients. Key words: Glomerulonephritis, Membranous; Receptors, Phospholipase A2

Rituximab for non-responsive idiopathic membranous nephropathy in a Chinese cohort.

Rituximab had been shown to be effective in inducing remission of nephrotic syndrome in patients with idiopathic membranous nephropathy (iMN). This study applied rituximab therapy for 36 non-responsive iMN patients to investigate its effects and safety. Thirty-six iMN patients who were non-responsive to prior immunosuppression were enrolled. Rituximab was used for B-cell depletion in patients, with a goal of <5 B cells/mm3 in the circulation. After completing the study, patients were monitored for a median of 12.0 months [interquartile range (IQR) 9.0-19.3]. Fifteen of the 36 (41.7%) patients achieved partial (n = 13) or complete (n = 2) response to the rituximab treatment. The median time for achieving partial response was 4.0 months (IQR 3.0-6.0). The responders had relatively lower levels (118 ± 112 U/mL versus 345 ± 357 U/mL, P = 0.03) of anti-phospholipase 2 receptor (PLA2R) antibodies before the rituximab treatment, and all of them achieved antibody depletion or reduction. B-cell depletion was achieved in all patients. Renal function remained stable in the responders [estimated glomerular filtration rate (eGFR) 53.3 ± 40.5 versus 55.6 ± 33.2 mL/min/1.73m2, P = 0.67] but deteriorated in the non-responders (eGFR 57.5 ± 29.3 versus 45.3 ± 32.8 mL/min/1.73m2, P = 0.02) with two patients reaching end-stage kidney disease. Two of the 15 patients relapsed during the follow-up period with anti-PLA2R antibody reoccurrence and B-cell reconstitution. The second course of rituximab combined with tacrolimus induced a faster partial response again in one patient. Rituximab therapy could induce remission of proteinuria and stabilization of renal function in non-responsive iMN patients, even those with damaged renal function. Anti-PLA2R antibodies may be used as a marker for individualized rituximab dosage and treatment monitoring.

Serum anti-PLA2R antibody as a diagnostic biomarker of idiopathic membranous nephropathy: The optimal cut-off value for Chinese patients

BackgroundThe M-type phospholipase A2 receptor (PLA2R) is a specific target autoantigen identified in idiopathic membranous nephropathy (IMN). The autoantibody against PLA2R (anti-PLA2R) may be used to diagnose IMN. However, the appropriate diagnosis cut-off value for Chinese patients with IMN has not been established. MethodsIn total, 119 patients who underwent renal biopsy (57 patients with IMN and 62 patients with non-IMN glomerulonephritis) and 22 healthy individuals were recruited for our observation study from Qianfoshan Hospital between September 2011 and March 2016. The serum concentration of anti-PLA2R was measured using a quantitative enzyme-linked immunosorbent assay (ELISA). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and receiver operating characteristic (ROC) curve of anti-PLA2R in diagnosing IMN were analysed based on the ELISA detection. ResultsThe sensitivity, specificity, PPV, and NPV of anti-PLA2R in the diagnosis of IMN in the Chinese patients were 82.5, 75, 69.1, and 86.3% for the 2RU/ml cut-off value; 78.9, 91.7, 86.5, and 86.5% for the 2.6RU/ml cut-off value; 59.6, 95.2, 89.5, and 77.7% for the 14RU/ml cut-off value; 50.9, 96.4, 90.6, and 74.3% for the 20RU/ml cut-off value; and 47.4, 97.6, 93.1, and 73.2% for the 40RU/ml cut-off value, respectively. The area under the ROC curve was 0.879. ConclusionsThe cut-off value of 2.6RU/ml is recommended for the use of anti-PLA2R for the diagnosis of IMN in Chinese patients based on the ELISA.

Diagnostic specificity of autoantibodies to M-type phospholipase A2 receptor (PLA2R) in differentiating idiopathic membranous nephropathy (IMN) from secondary forms and other glomerular diseases.

Autoantibody against phospholipase A2 receptor (anti-PLA2R) is a sensitive and specific biomarker of idiopathic membranous nephropathy (iMN), being found in approximately 70% of iMN patients and only occasionally in other glomerular diseases. However, whereas its diagnostic specificity vs. normal controls and other glomerulonephritides (GN) has been firmly established, its specificity vs. membranous nephropathy associated with various diseases (sMN) has given inconsistent results. The aim of our study was to evaluate the prevalence of anti-PLA2R antibodies in iMN in comparison with various control groups, including sMN. A total of 252 consecutive iMN patients, 184 pathological and 43 healthy controls were tested for anti-PLA2R antibody using indirect immunofluorescence (PLA2R IIFT, Euroimmun). Anti-PLA2R autoantibodies were detectable in 178/252 iMN patients, 1/80 primary GN, 0/72 secondary GN, 9/32 sMN and 0/43 healthy controls, with a diagnostic sensitivity of 70.6%. The diagnostic specificity of anti-PLA2R antibody vs. normal and pathological controls was 100 and 94.6% respectively. However, when the diagnostic specificity was calculated only vs. secondary forms of MN, it decreased considerably to 71.9%. Interestingly enough, 9 out of 10 anti-PLA2R positive patients in the disease control groups had membranous nephropathy associated with various diseases (7 cancer, 1 Crohn's disease, 1 scleroderma). In conclusion, anti-PLA2R positivity in a patient with MN, should not be considered sufficient to abstain from seeking a secondary cause, especially in patients with risk factors for neoplasia. The causal relationship between tumors and anti-PLA2R-induced MN remains to be established, as well as the possible mechanisms through which malignancies provoke autoimmunity.

Circulating Antibodies against Thrombospondin Type-I Domain-Containing 7A in Chinese Patients with Idiopathic Membranous Nephropathy.

Thrombospondin type-I domain-containing 7A (THSD7A) was recently identified as the target antigen in about 10% of patients with M-type phospholipase A2 receptor (PLA2R)-negative membranous nephropathy in European and North American populations. The prevalence of THSD7A in other populations and their clinical associations deserve further clarification. Immunofluorescence assay was performed to investigate anti-THSD7A antibodies in 578 consecutive patients with biopsy-proven idiopathic membranous nephropathy, 114 patients with secondary membranous nephropathy, 64 disease controls, and 20 healthy controls. Glomerular expression of THSD7A antigen was examined by immunohistochemistry. Anti-PLA2R antibodies and glomerular PLA2R expression were also screened. Among the 578 patients with idiopathic membranous nephropathy, 12 (2%) patients were identified as THSD7A-positive: ten patients were THSD7A-positive alone, which accounted for 16% (ten of 64) of PLA2R-negative patients; two patients were dual-positive for both anti-THSD7A and anti-PLA2R antibodies and showed enhanced expression of both antigens colocalized in glomeruli. Among the 114 patients with secondary membranous nephropathy, one among 44 (2%) patients with cancer had anti-THSD7A antibodies, whereas 18 of 44 (41%) had anti-PLA2R antibodies. No anti-THSD7A antibody was detected in other disease controls or healthy individuals. Clinical features were comparable between the patients with and without THSD7A. During follow-up, two patients who achieved remission had a clearance of circulating antibodies against THSD7A, whereas antibodies increased in parallel with proteinuria in a patient with a relapse. THSD7A-associated membranous nephropathy has a low prevalence in Chinese patients. The double-positive patients suggest dual autoimmune responses.

Urine anti-PLA2R antibody is a novel biomarker of idiopathic membranous nephropathy.

Since urine samples more directly reflect kidney alterations and damage than blood samples, we investigated whether urine anti-PLA2R antibody (uPLA2R-Ab) could be utilized similarly to serum anti-PLA2R antibody (sPLA2R-Ab) as a noninvasive biomarker of idiopathic membranous nephropathy (IMN). In this study, we performed a qualitative analysis using an indirect immunofluorescence test (IIFT) and measured uPLA2R-Ab and sPLA2R-Ab concentrations using an enzyme-linked immunosorbent assay (ELISA) in 28 patients with biopsy-proven IMN and 12 patients with secondary membranous nephropathy (SMN). Overall, 64.3% (n=18) of patients with IMN had IIFT-positive sPLA2R-Ab, 67.9% (n=19) of patients with IMN had IIFT-positive uPLA2R-Ab, and none of the SMN patients had IIFT-positive sPLA2R-Ab or uPLA2R-Ab. The titers of the anti-PLA2R antibody from the IMN patients in the urine (10.72±22.24 RU/μmol, presented as uPLA2R-Ab/urine creatinine) and serum (107.36±140.93 RU/ml) were higher than those from the SMN patients (0.51±0.46 RU/μmol, 0.008±0.029 RU/ml, respectively, p<0.05). Statistical analyses indicated that there were positive correlations between uPLA2R-Ab and gPLA2R, sPLA2R-Ab or urinary protein and negative correlations between uPLA2R-Ab and serum albumin in patients with IMN. In conclusion, uPLA2R-Ab is a novel biomarker of IMN. sPLA2R-Ab combined with uPLA2R-Ab might be more helpful for diagnosis and activity in PLA2R associated MN.

Treatment of membranous nephropathy: time for a paradigm shift.

In patients with membranous nephropathy, alkylating agents (cyclophosphamide or chlorambucil) alone or in combination with steroids achieve remission of nephrotic syndrome more effectively than conservative treatment or steroids alone, but can cause myelotoxicity, infections, and cancer. Calcineurin inhibitors can improve proteinuria, but are nephrotoxic. Most patients relapse after treatment withdrawal and can become treatment dependent, which increases the risk of nephrotoxicity. The discovery of nephritogenic autoantibodies against podocyte M-type phospholipase A2 receptor (PLA2R) and thrombospondin type-1 domain- containing protein 7A (THSD7A) antigens provides a clear pathophysiological rationale for interventions that specifically target B-cell lineages to prevent antibody production and subepithelial deposition. The anti-CD20 monoclonal antibody rituximab is safe and achieves remission of proteinuria in approximately two-thirds of patients with membranous nephropathy. In those with PLA2R-related disease, remission can be predicted by anti-PLA2R antibody depletion and relapse by antibody re-emergence into the circulation. Thus, integrated evaluation of serology and proteinuria could guide identification of affected patients and treatment with individually tailored protocols. Nonspecific and toxic immunosuppressive regimens will fall out of use. B-cell modulation by rituximab and second-generation anti-CD20 antibodies (or plasma cell-targeted therapy in anti-CD20 resistant forms of disease) will lead to a novel therapeutic paradigm for patients with membranous nephropathy.

Diagnostic value of renal phospholipase A2 receptor and serum anti-phospholipase A2 receptor antibody in membranous nephropathy

To examine the expression of phospholipase A2 receptor (PLA2R) in renal tissues and the level of anti-PLA2R antibody in serum in patients with idiopathic membranous nephropathy (IMN) and secondary membranous nephropathy (SMN), and to evaluate their diagnostic value in IMN. Methods: A total of 73 patients, who were diagnosed between May, 2014 and February, 2015 in the Department of Nephrology of the Second Xiangya Hospital, Central South University, were divided into three groups: an IMN group (n=48), an SMN group (n=17) and a minimal change disease group (n=8) according to the renal biopsy. PLA2R expression in renal tissues and the level of anti-PLA2R antibody in serum were detected by indirect immunofluorescence technique. Results: The positive rate and fluorescence intensity for PLA2R in the renal tissues in the IMN group were higher than those in the SMN group (91.7% in the IMN group vs 29.4% in the SMN group, P<0.05), while the positive rate and serum level for anti-PLA2R antibody in the IMN group were higher than those in the SMN group (85.4% in the IMN group vs 29.4% in the SMN group, P<0.05); the expression of PLA2R in renal tissues and the serum level for anti-PLA2R antibody were not detected in the minimal change disease group. The serum level of anti-PLA2R antibody was positively correlated with 24 h urine protein (r=0.432, P<0.01) and negatively correlated with serum albumin (r=-0.307, P<0.05). Conclusion: The expression of PLA2R in renal tissues and the serum level of anti-PLA2R antibody might be potential markers for diagnosis of IMN.

Prognostic value of PLA2R autoimmunity detected by measurement of anti-PLA2R antibodies combined with detection of PLA2R antigen in membranous nephropathy: A single-centre study over 14 years.

IntroductionClinical course of membranous nephropathy (MN) is difficult to predict. Measurement of circulating anti-PLA2R autoantibodies (PLA2R-Ab) and detection in immune deposits of PLA2R antigen (PLA2R-Ag) are major advances in disease understanding. We evaluated the clinical significance of these biomarkers.MethodsIn this 14-year retrospective study, we collected data from 108 MN patients and assessed the relationship between clinical course, PLA2R-Ab and PLA2R-Ag. We also assessed THSD7A status.ResultsEighty-five patients suffered from primary MN (PMN) and 23 patients from a secondary form. The median follow-up was 30.4 months [interquartile range, 17.7;56.7]. Among the 77 patients with PMN and available serum and/or biopsy, 69 (89.6%) had PLA2R-related disease as shown by anti-PLA2R-Ab and/or PLA2R-Ag, while 8 patients (8/77, 10.4%) were negative for both. There was no significant difference between these two groups in age at diagnosis and outcome assessed by proteinuria, serum albumin level and eGFR. Two of the 8 negative patients were positive for THSD7A. In patients with PLA2R related PMN, younger age, lower proteinuria, higher eGFR, and lower PLA2R-Ab level at baseline and after 6 months were associated with remission of proteinuria. Initial PLA2R-Ab titer ≤ 97.6 RU/mL and complete depletion of PLA2R-Ab within 6-months were significantly associated with spontaneous remission at the end of follow-up. In rituximab treated patients, lower PLA2R-Ab titer at initiation of treatment, and absence of PLA2R-Ab and higher serum albumin level at 3 months were significantly associated with remission. Noticeably, 81.8% of the patients who achieved remission completely cleared PLA2R-Ab. Depletion of PLA2R-Ab and increase of serum albumin level preceded the decrease of proteinuria.ConclusionAssessment of PLA2R autoimmunity is essential for patient management. Combination of PLA2R-Ab and PLA2R-Ag increases diagnosis sensitivity. PLA2R-Ab titer is a biomarker of disease severity at initial assessment, and the kinetics of the antibody are significantly correlated to disease evolution.

Research progress of idiopathic membranous nephropathy associated antigen phospholipase A2 receptor and thrombospondin type-1 domain containing 7A

Idiopathic membranous nephropathy(IMN) is one of the main pathology of nephrotic syndrome, and has a rising trend year by year.In recent years that IMN is organ specific autoimmune disease.Phospholipase A2 receptor(PLA2R) and thrombospondin type-1 domain containing 7A(THSD7A) are the two main antigens of IMN, which could be used to distinguish the IMN and secondary membranous nephropathy.The anti-PLA2R antibody and anti-THSD7A antibody are associated with diagnosis, severity and activity of the disease.The antibody titer and its change could be used to help deciding the beginning of therapy and the therapitive courses. Key words: Idiopathic membranous nephropathy; Phospholipase A2 receptor; Thrombospondin Type-1 Domain containing 7A

Immunohistochemical Analysis of Anti-phospholipase A2 Receptor Antibody on Renal Biopsies: A Single Tertiary Care Center Study.

Membranous nephropathy (MN) is one of the common cause of nephrotic syndrome. The discrimination between primary MN (iMN) and secondary MN is essential because of treatment implications. Immunohistochemical (IHC) evaluation with the help of anti-phospholipase A2 receptor (PLA2R) antibody helps in tissue evaluation of iMN, which is an easy, cost-effective, and pathologist-friendly technique. The study included 82 cases of MN over a period of 3 years. IHC using PLA2R antibody was performed on iMN and secondary cases with adequate tissue. Cases of minimal change disease (MCD) were included as control. Granular staining along the basement membrane in the absence of staining of podocytes was considered positive. Medical records were verified for clinical information, baseline biochemical parameters, details of viral markers, connective tissue disease profile, and basic imaging workup. Of the 82 cases of MN, 51 were iMN and 31 secondary MN (sMN). Thirteen MCD cases were included as control. IHC with PLA2R antibody showed a sensitivity of 91.8% and specificity of 95.1%, positive predictive value of 95.7%, and negative predictive value of 90.7% in the diagnosis of iMN. The other parameters, either clinical or laboratory, did not show significant differences between iMN and sMN groups. The results of PLA2R staining by IHC were comparable with other studies and showed a higher sensitivity (91.8%) and specificity (95.1%). IHC with anti-PLA2R antibody can be considered as the standard diagnostic approach to identify iMN and offer scope for individualized treatment.

Two autoantibody tests for diagnosis of idiopathic membranous nephropathy—Urgent call to action

Over the past decade, with the rapid increase of the incidence of idiopathic membranous nephropathy (IMN) in our country, the diagnosis and treatment of IMN has been paid more and more attention. IMN is an autoimmune disease.Two important podocyte autoantigens, PLA2R and THSD7A, have been indentified sine 2009.Subsequently, serum anti-PLA2R antibody test and anti-THSD7A antibody test have also been used in clinical. Preliminary applications show that these two tests can not only help IMN diagnosis and differential diagnosis, but also help IMN prognosis.(Chin J Lab Med, 2016, 39: 873-875) Key words: Glomerulonephritis, membranous; Receptors, phospholipase A2

PLA2R antibodies and PLA2R glomerular deposits in psoriasis patients with membranous nephropathy.

BackgroundThe association between psoriasis and membranous nephropathy (MN) remains largely unclear. We examined the prevalence of serum PLA2R antibody and characterized the expression of PLA2R and THSD7A in glomeruli in patients with MN and psoriasis.MethodsA total of 24 patients with MN without evidence of a secondary cause except psoriasis were enrolled. The clinical and pathological features were retrospectively analyzed. Serum anti-PLA2R antibody was measured using IFA Mosaic. Renal tissue samples stored in the laboratory bio-bank were used for PLA2R staining under immunofluorescence microscopy and THSD7A immunohistochemical analysis.ResultsTwenty-four patients (21 male and 3 female) with a mean age of 43.6 ± 15.7 years old were enrolled. Serum anti-PLA2R antibody was positive in 7 patients, which was significantly lower than the positivity observed in idiopathic MN (29.2% vs. 81.7%, P < 0.001). Glomerular PLA2R staining was positive in 7 patients with positive serum anti-PLA2R antibody. THSD7A staining was negative in all 24 patients. During the follow-up visits, 13 patients with negative serum PLA2R antibody achieved CR. In contrast, CR was only achieved in 1 patient with positive serum PLA2R antibody, PR was achieved in 2 patients.ConclusionsThe prevalence of serum anti-PLA2R antibody and glomerular expression of PLA2R was significantly lower in patients with psoriasis and MN than in those with idiopathic MN, and THSD7A staining was negative, suggesting that MN is associated with psoriasis in the majority of patients. However, idiopathic MN might also accompany psoriasis in a minority of psoriatic patients with positive serum anti-PLA2R antibody.

MHC Class II Risk Alleles and Amino Acid Residues in Idiopathic Membranous Nephropathy.

Epitopes of phospholipase A2 receptor (PLA2R), the target antigen in idiopathic membranous nephropathy (iMN), must be presented by the HLA-encoded MHC class II molecules to stimulate autoantibody production. A genome-wide association study identified risk alleles at HLA and PLA2R loci, with the top variant rs2187668 within HLA-DQA1 showing a risk effect greater than that of the top variant rs4664308 within PLA2R1. How the HLA risk alleles affect epitope presentation by MHC class II molecules in iMN is unknown. Here, we genotyped 261 patients with iMN and 599 healthy controls at the HLA-DRB1, HLA-DQA1, HLA-DQB1, and HLA-DPB1 loci with four-digit resolution and extracted the encoded amino acid sequences from the IMGT/HLA database. We predicted T cell epitopes of PLA2R and constructed MHC-DR molecule-PLA2R peptide-T cell receptor structures using Modeler. We identified DRB1*1501 (odds ratio, 4.65; 95% confidence interval [95% CI], 3.39 to 6.41; P<0.001) and DRB1*0301 (odds ratio, 3.96; 95% CI, 2.61 to 6.05; P<0.001) as independent risk alleles for iMN and associated with circulating anti-PLA2R antibodies. Strong gene-gene interaction was noted between rs4664308(AA) and HLA-DRB1*1501/DRB1*0301. Amino acid positions 13 (P<0.001) and 71 (P<0.001) in the MHC-DRβ1 chain independently associated with iMN. Structural models showed that arginine13 and alanine71, encoded by DRB1*1501, and lysine71, encoded by DRB1*0301, facilitate interactions with T cell epitopes of PLA2R. In conclusion, we identified two risk alleles of HLA class II genes and three amino acid residues on positions 13 and 71 of the MHC-DRβ1 chain that may confer susceptibility to iMN by presenting T cell epitopes on PLA2R.