Prognostic Significance of Dynamic Changes in Glomerular C3 Deposition in Membranous Nephropathy

Background: Membranous nephropathy (MN) is a primary cause of nephrotic syndrome in adults, with complement activation being a pivotal factor in its pathophysiology. Nevertheless, the prognostic significance of glomerular C3 deposition, particularly in subsequent biopsies, remains unclear. This study evaluates the influence of alterations in C3 deposition on the clinical prognosis of MN following intravenous methylprednisolone (MPD) treatment. Methods: This retrospective study examined 11 patients with histologically confirmed MN who achieved remission following intravenous MPD pulse therapy and subsequently underwent a follow-up kidney biopsy. The patients were categorized according to the presence or absence of glomerular C3 deposition in the follow-up biopsy. Comparative analysis of clinical, laboratory, and histopathological data was conducted between the groups to evaluate treatment response and long-term outcomes. Results: Eight patients exhibited resolution of C3 deposition on follow-up biopsy, whereas three showed persistent C3 deposition. Despite both groups experiencing a notable decrease in proteinuria, persistent C3 deposition was associated with higher recurrence rates and limited histological improvement. Patients with resolved C3 deposition maintained remission over an average follow-up period of 5.3 years, whereas all patients with persistent C3 deposition experienced relapse during follow-up. Conclusions: The intravenous MPD pulse therapy successfully induced remission of MN. Additionally, the disappearance of glomerular C3 deposition following therapy may serve as a prognostic indicator for long-term remission.