Serum secretory phospholipase A2 group IB correlates with the severity of membranous nephropathy

Background: Serum secretory phospholipase A2 group IB (sPLA2-IB) is involved in the pathological processes of membranous nephropathy (MN). To date, there is no large-scale study validating the usefulness of circulating sPLA2-IB in the follow-up of patients with MN. This study investigated the role of circulating sPLA2-IB in the evaluation of severity of MN. Methods: A total of 158 patients with primary membranous nephropathy (pMN), 34 with secondary membranous nephropathy (sMN) and 53 healthy controls were enrolled. Histological staging was made for all MN patients. 36 of the pMN patients accepted immunosuppressive therapy and 11 sMN patients who received treatment of primary disease were followed up for 6 months. Serum group IB secretory phospholipase A2 (sPLA2-IB), M-type phospholipase A2 receptor antibody (PLA2R-Ab), blood urea nitrogen, creatinine, total protein, albumin, cholesterol, triglyceride and 24-hour urine protein were measured at the time of diagnosis. SPLA2-IB and 24-hour urine protein were measured at the end of follow-up. Results: Circulating sPLA2-IB levels were significantly higher in pMN and sMN patients compared to controls and negatively correlated with TP and albumin, whereas positively correlated with 24-hour urine protein. PLA2-IB was found increased with the severity of proteinuria when divided MN patiens into three groups according to degree of proteinuria. Through the 6-month follow-up, sPLA2-IB and 24 h-urine protein levels were found significantly decreased when patients with pMN or sMN reached remission. By ROC analysis, PLA2R-Ab was demonstrated to be most significant in the differential diagnosis of pMN and sMN compared with 24-hour urinary protein and serum sPLA2-IB. Conclusion: Despite the limited significance to differentiate pMN from sMN, sPLA2-IB was correlated with the level of proteinuria in MN patients suggesting to be a potential biomarker for monitoring disease severity and therapeutic effects of both pMN and sMN.