Abstract: PO1511
A Rare Case of Concurrent Glomerulonephritis and Autoimmunity
Session Information
- Glomerular Diseases: The Excitement of Clinical Cases
November 04, 2021 | Location: On-Demand, Virtual Only
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1202 Glomerular Diseases: Immunology and Inflammation
Authors
- Sabescumar, Janany Jansy, University of Rochester, Rochester, New York, United States
- Grewal, Rickinder, University of Rochester, Rochester, New York, United States
- Choung, Hae Yoon Grace, University of Rochester, Rochester, New York, United States
Introduction
We report a rare case of necrotizing and crescentic glomerulonephritis in the setting of Streptococcus mitis bacteremia.
Case Description
A sixty-one year old man with a history of hypertension, hyperlipidemia, and non-insulin-dependent diabetes presented to the emergency room with progressive lower extremity edema and dyspnea with tea-colored frothy urine. Initial workup revealed bilateral pulmonary edema and acute kidney injury with a serum creatinine of 1.84 mg/dL (0.8 mg/dL 6 months prior) with 9.18 grams proteinuria and an active urine sediment. He was initially diuresed for decompensated heart failure but further workup revealed hypocomplementemia and positive ANCA/proteinase-3 (PR3) antibody. A kidney biopsy revealed membranous glomerulonephritis (MGN) with focal endocapillary proliferative features and focal crescents with fibrinoid necrosis with positive PLA2R immunostaining and serum PLA2R IgG antibody testing revealing a titer of 1:2560. An echocardiogram revealed reduced left ventricular ejection fraction with a mobile aortic valve vegetation. Blood cultures obtained on admission ultimately grew Streptococcus mitis and he underwent aortic valve repair. Despite completion of a full antibiotic course, his creatinine remained impaired with nephrotic-range proteinuria and elevated serum PLA2R titers. Repeat renal biopsy revealed membranous glomerulonephritis and he was started on immunosuppression for treatment of PLA2R-associated MGN.
Discussion
Peri-infectious PLA2R-associated MGN and ANCA-associated glomerulonephritis appears to be a rare. While his proliferative ANCA-mediated glomerulonephritis was likely related to the infectious endocarditis, the relationship to the PLA2R-positive MGN remains unclear. We hypothesize that host immune response to infectious agents lead to an autoimmune process resulting in glomerulonephritis. It is possible that in addition to a genetic predisposition (“first hit”), a “second hit” which begins with activation of the innate immune response by an infectious agent leading to autoimmunity through various mechanisms including defective immune regulation, molecular mimicry, epitope spreading, and autoantigen complementarity.