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Kidney Week

Abstract: TH-OR24

Anti-Nephrin Antibody as a Potential Etiology in Primary Focal Segmental Sclerosis (FSGS)

Session Information

Category: Glomerular Diseases

  • 1402 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Avillach, Claire, Boston Medical Center, Boston, Massachusetts, United States
  • Wang, Qiyu, Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Watts, Andrew James baxter, Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Weins, Astrid, Brigham and Women's Hospital, Boston, Massachusetts, United States
Background

Minimal change disease (MCD) and primary FSGS have long been pondered to have shared pathogenesis representing a spectrum of different stages of podocyte injury and repair. Recent discovery of anti-nephrin antibodies (Ab) in MCD led us to hypothesize that anti-nephrin Ab may also be present in primary FSGS.

Methods

We retrospectively reviewed all native kidney biopsies performed at BWH from 1/2018-4/2022. We identified 52 cases of primary FSGS (diffuse podocytopathy+segmental sclerosis). We compared the pathological and clinical features between patients (pts) who have punctate IgG deposition on biopsies (+IgG) and those without (-IgG). Anti-nephrin Ab was tested in select pts with +IgG.

Results

Among the 52 cases, 14 had +IgG on IF (27%).There was no difference in the presence of collapsing lesion (36% vs. 45%, P=0.6), percentage of segmental sclerosis (7% vs. 8%, P=0.6) and IFTA (18% vs. 20%, P=0.7) between +IgG and -IgG groups. There was a trend towards enrichment of tip lesions in the +IgG group (21% vs. 11%, P=0.3). Among the 40 pts with available clinical data at biopsy, median proteinuria was significantly higher in the +IgG compared to -IgG group (13 vs 8 g/g, P=0.01). Five pts with +IgG had anti-nephrin Ab tested during active disease and all were positive (Table 1); all 5 biopsies showed colocalization of the punctate IgG with nephrin (Figure 1).

Conclusion

Punctate IgG deposition that colocalizes with nephrin is also observed in patients with primary FSGS and correlates with circulating anti-nephrin Ab. This suggests that anti-nephrin Ab-mediated podocyte dysfunction may be a shared disease mechanism between MCD and primary FSGS.