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Kidney Week

Abstract: TH-PO659

Clinical and Outcomes Correlations with Exostosin 1 Positivity Lupus Nephritis

Session Information

Category: Glomerular Diseases

  • 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics

Authors

  • Assis, Luiza Liza de, Universidade de Sao Paulo, Sao Paulo, Brazil
  • Yu, Luis, Universidade de Sao Paulo, Sao Paulo, Brazil
  • Malheiros, Denise M., Universidade de Sao Paulo, Sao Paulo, Brazil
Background

Recently, exostosin 1 (EXT1) and exostosin 2 (EXT2), were identified in patients with lupus membranous nephropathy (LMN). Immunohistochemical studies revealed positivity rates from 32.6% to 46%, and these patients present lower chronicity indexes and reduced chronic kidney disease (CKD) progression but are more likely to disclose massive proteinuria at diagnosis. Follow-up results are conflicting, but patients with positive EXT1/EXT2 LMN had a lower incidence of end-stage kidney disease (ESKD) compared to those with negative EXT1/EXT2 LMN. The aim of this study was to assess the prevalence of EXT1/EXT2 in renal biopsies of patients with LMN (class V) and LMN with proliferative component (class III/IV + V), comparing clinicopathologic features at diagnosis and outcomes in patients followed for at least 2 years.

Methods

A retrospective cohort study of patients with membranous lupus nephritis was performed and EXT 1 immunohistochemistry studies on the kidney biopsy specimens were evaluated. (Picture 1). Clinicopathologic features and outcomes of EXT1 positive versus EXT1 negative patients were compared.

Results

Our cohort included 94 patients, of which 34 (36%) were EXT1 positive. According to histological classification, 13 out of 31 (41.94%) patients with LMN were EXT1 positive and 21 out of 63 (33%) patients with LNM associated with proliferation were EXT 1 positive (Picture 2). There were not significant differences between EXT 1 positive and negative groups at the time of renal biopsy, regarding proteinuria and serum creatinine levels, and also activity or chronicity indices on kidney biopsy. A total of 85 patients were followed for a median of 50 months. Patients with EXT1 positive showed significantly higher rates of complete or partial treatment response (p=0.035) and negative anti-DNA antibodies (p=0.01).

Conclusion

The prevalence of EXT1 positivity in LMN was 36% in our cohort. No differences were observed at diagnosis presentation, however, patients with positive EXT1 had better treatment response rates and lower anti-DNA antibodies levels, suggesting a more favorable prognosis for these patients.