Abstract: FR-PO0698
NELL-1-Positive Membranous Nephropathy Secondary to Borrelia burgdorferi Infection
Session Information
- Glomerular Diseases: Membranous Nephropathy, FSGS, and Podocytopathies
October 23, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Renfrow, Amanda Joy Cox, WVU Medicine, Morgantown, West Virginia, United States
- Fahim, Bishoy, WVU Medicine, Morgantown, West Virginia, United States
- Dzedzik, Siarhei, WVU Medicine, Morgantown, West Virginia, United States
- Howell, David Michael, WVU Medicine, Morgantown, West Virginia, United States
- Kaur, Tripta, WVU Medicine, Morgantown, West Virginia, United States
Introduction
Neural epidermal growth factor-like 1 Protein (NELL1) is a target antigen for membranous nephropathy (MN) linked to malignancy, drugs, infections, autoimmune diseases, and graft vs host disease. Lyme disease has been associated with nephritic syndrome; however, only one case each of Lyme-associated MN and minimal change disease has been reported. We present the first known case of NELL1-positive secondary MN associated with Lyme disease.
Case Description
A 71-year-old male with hypertension (on RAAS blockade) and serofast syphilis presented with nephrotic-range proteinuria (6.1 g/day), creatinine 1.13 mg/dL, and a target rash 1 month after tick exposure. Lyme disease serology was positive for IgG and IgM. Workup showed elevated C3, normal C4, and negative PLA2R, ANA, anti-dsDNA, ANCA, anti-GBM, HBV, HCV, and HIV. RPR titer was 1:2. Kidney Biopsy (Figure 1) showed minimal glomerular capillary wall thickening with segmental subepithelial “fuzzing” on light microscopy. Immunofluorescence demonstrated glomerular capillary wall staining with 3+ IgG, moderate kappa/lambda, and trace C3, without significant IgM, IgA, C1q or fibrinogen. Electron microscopy showed global stage I subepithelial electron dense deposits without significant glomerular basement membrane reaction. Mass spectrometry and Immunofluorescence were positive for NELL1 and negative for PLA2R, THSD7A, and NDNF. Secondary MN due to Lyme disease was suspected, and treatment with doxycycline and empagliflozin reduced proteinuria from 6.1 g to 0.7 g over 4 months.
Discussion
Syphilis was an important competing diagnosis; however, the rise in syphilis titers from 1:2 to 1:4 after treatment and negative NDNF staining made syphilis an unlikely cause of the nephrotic-range proteinuria. To our knowledge, this is the first reported case of NELL1-positive membranous nephropathy attributable to Borrelia burgdorferi. The only prior report of Lyme disease-associated MN predates the identification NELL1. This case expands the spectrum of NELL1-associated disease and supports its emerging role as a biomarker of secondary membranous nephropathy, analogous to PLA2R and THSD7A in primary MN.