Distribution spectrum and clinical significance of glomerular exostosin (EXT1) deposits in PLA2R-positive membranous nephropathy.

The discovery of antigen phospholipase A2 receptor (PLA2R) in 2009 ushered in the antigen-based study of membranous nephropathy. The further putative antigen exostosin 1/2 (EXT1/2) was described in 2019. However, the distribution spectrum of glomerular EXT1 deposits in membranous nephropathy has not been fully elucidated. We conducted a retrospective cohort study of biopsy-proven membranous nephropathy patients. Patients with complete baseline data and adequate tissue specimens were included in this study. Tests for glomerular expression of PLA2R and EXT1 and circulating anti-PLA2R antibodies were performed. Clinicopathological and outcome data were reviewed. We included 626 patients, namely, 487 (77.8%) PLA2R-positive patients and 54 (8.6%) EXT1-positive patients; 32 (5.1%) patients were dual-positive for PLA2R and EXT1 (PLA2R + /EXT1 +). A higher percentage of dual-positive patients had low C3 levels (P < 0.001) and were more likely to have autoimmune diseases (P = 0.013) than PLA2R-positive and EXT1-negative (PLA2R + /EXT1-) patients. Kidney biopsy findings revealed that there was a higher percentage of glomerular IgG1, IgG2, IgA, C4, and C1q deposits (P < 0.05), "full-house" staining (P < 0.001), and stronger intensity of C1q staining (P = 0.002) in PLA2R + /EXT1 + patients. Based on Kaplan-Meier analysis, a higher percentage of PLA2R + /EXT1 + patients exhibited partial or complete remission of proteinuria. Furthermore, EXT1-positive expression was a favourable predictor for proteinuria remission, whereas interstitial fibrosis/tubular atrophy was an unfavourable predictor. A complement C3 level  < 0.79 g/L was independently associated with EXT1 positivity in PLA2R-positive membranous nephropathy. We describe a subgroup of PLA2R and EXT1 dual-positive patients. Patients in this subset exhibited more signs of autoimmunity and more frequent clinical remission. In PLA2R-positive membranous nephropathy, a complement C3 level  < 0.79 g/L was independently associated with EXT1 positivity, which was a favourable predictor for proteinuria remission. © 2023. The Author(s) under exclusive licence to Italian Society of Nephrology.

Citation

Zezhou Liu, Cheng Wan, Yiling Cao, Saiji Liu, Ziyu Xu, Chun Zhang, Hua Su. Distribution spectrum and clinical significance of glomerular exostosin (EXT1) deposits in PLA2R-positive membranous nephropathy. Journal of nephrology. 2024 Jan;37(1):149-158

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PMID: 37882962

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