Diagnosis and trerapeutic value of anti-phospholipath A2 receptor (anti-PLA2R) antibody in idiopathic membrane glomeruronophritis

Introduction: Membranous glomerulonephritis (MGN) is the most common primary glomerular disease causing nephrotic syndrome in adults. In 2009, Beck et al. demonstrated the presence of auto-antibodies (anti-PLA2R) against M-type phospholipase A2 receptor in 70% of the patients diagnosed with adult idiopathic membranous glomerulonephritis (IMN). Our study is a cross-sectional study that aims to evaluate the presence and levels of PLA2R antibodies in healthy volunteers and IMN patients and to assess the relationship between these levels and clinical parameters. Method: Seventy-one patients who were admitted to the Nephrology Polyclinic of the Department of Nephrology's Gaziantep University Medical Faculty and who were diagnosed with IMN by renal biopsy, and 48 healthy volunteers, were included in our cross-sectional study after providing informed consent forms. Patients between the ages of 18-65 who were pathologically diagnosed with IMN, had serum creatinine levels of <2mg/dl, and who had not had any treatment changes during the last month were included in the study after excluding secondary causes. Blood and urine samples were obtained from all participants for laboratory analyses. The complete blood count, urea, creatinine, total protein, albumin, low density lipoprotein (LDL), triglyceride, high density lipoprotein (HDL), total cholesterol, C-reactive protein (CRP) and sedimentation values were obtained from hospital recordings.. Protein levels were measured using 24-hour urine samples and spot complete urinalysis was requested. Additionally, serum samples were collected from patient and control groups during the polyclinic visit and stored at -80°C until anti-PLA2R antibody measurements were carried out. Serum anti-PLA2R antibody levels were measured using the ELISA (Enzyme-Linked ImmunoSorbent Assay) method. The Mann Whitney U Test was used in order to compare the differences between the two groups. Relationships between numeric variables that did not have a normal distribution were tested using the Spearman correlation coefficient. SPSS 22.0 package software was used for the analyses. The P value <0.05 was accepted as statistically significant. Results: No significant differences were identified between patient and control groups in terms of demographic and laboratory values, including age, gender, CRP, HDL, AST, ALT, mean corpuscular volume (MCV) and platelet (PLT) values (p>0.05). Of the values compared between the two groups, the urea, creatinine (CRE), modified diet renal disease (MDRD) were similar, total protein, albumin, LDL, TG, total cholesterol, HDL, and complete urinalysis protein values were statistically significantly high in the patient group, as expected in nephrotic syndrome (p<0.01). The anti-PLA2R antibody levels measured using ELISA in patient and control groups were found to be negative, and the results of the samples from both groups were below the reference values of the test. Moreover, as the detected values were below 0.5ng/ml, which is the minimum sensitivity value of the test, and the values measured from the samples were also below this value, all values were assessed as negative. Conclusion: There is a need to conduct more sensitive studies with a higher number of patients in order to distinguish between primary and secondary nature and to investigate the presence of anti-PLA2R in MN patients, which constitute the majority of nephrotic syndromes in adults. In the light of currently available information, there is no specific bio-marker to evaluate the diagnosis and treatment of IMN patients, and therefore, the importance of the anti-PLA2R antibody level has been emphasized in many case series since 2009. In our study, antibody titer levels were observed to be low and it was revealed that the measurement range of the antibody kit used in the study should be more sensitive and that the study should be supported with more patients. Keywords: membranous nephropathy, idiopathic membranous glomerulonephritis anti M-type phospholipase A2 receptor (anti-PLA2R).