Expression and significance of M-type phospholipase A2 receptor and thrombospondin type-1 domain-containing 7A in adult idiopathic membranous nephropathy

Abstract

Objective To detect the M-type phospholipase A2 receptor (PLA2R), and thrombospondin type-1 domain-containing 7A (THSD7A) expression in renal tissue and the levels of their antibodies in adult idiopathic membranous nephropathy (IMN). Also to determine the value of the two markers in the diagnosis of IMN. Methods One hundred and sixteen patients with biopsy-proven MN at the Second Hospital of Hebei Medical University from December 2014 to August 2015 were enrolled, including 86 patients with IMN, 10 patients with HBV-MN and 10 patients with stage V lupus nephritis (LN-V). Twenty patients with minimal change disease (MCD) were regarded as control group. We conducted immunohistochemical analysis of the presence of THSD7A and PLA2R the Paraffin section and enzyme linked immunosorbent assay (ELISA) detecting serum PLA2R-AB and THSD7A-AB concentration to investigate whether there was a correlation between them and clinical indicators. Results Compared with the SMN and MCD groups, the positive rates of PLA2R and PLA2R-AB were significantly higher in IMN groups. Expression PLA2R was detected in 88.4%, 47.4%, 10% and 0% and PLA2R-AB in 82.6%, 15%, 10%, 0%, respectively, of the patients with IMN, HBV-MN, LN-V and MCD. Expression THSD7A was detected in 2.3% of the patients with IMN while not detected in SMN and MCD. THSD7A-AB antibody was negative in all patients. Compared with serum PLA2R-Ab negative individuals, patients with serum PLA2R-Ab positive had lower serum albumin (P <0.001), higher urine protein excretion (P=0.01). The sensitivity of PLA2R-AB, PLA2R, THSD7A and PLA2R+THSD7A in the diagnosis of IMN were 82.6%, 88.4%, 2.3%, 88.6%, and the specificity was 92%, 66.7%, 100%, 66.7%, respectively. Conclusions PLA2R in renal tissue and serum PLA2R-AB are specific markers for the diagnosis of IMN, which are closely related with the severity of IMN. Expression of THSD7A is only positive in some of IMN patients with negative PLA2R, which can be used as a supplementary examination of IMN patients with negative PLA2R. Key words: Receptors, phospholipase A2; Glomerulonephritis, membranous; Diagnosis, differential; Thrombospondin type-1 domain-containing; Idiopathic membranous nephropathy