128. The NLRP3 inflammasome, IL-1 and IL-18 in experimental anti-MPO glomerulonephritis
Creators: name: Hutton1, Holly
name: Alikhan1, Maliha
name: Richard A. Kitching1, 2
Publisher: name: Zenodo
Year: 2022
Subjects: Vasculitis
ANCA
Abstracts
Giant Cell Arthritis
MPA
GPA
EGPA
Takayasu
IgA vasculitis

description: <strong>Background:</strong> The NLRP3 inflammasome responds to cellular stress by activating the pro-inflammatory cytokines IL-1β and IL-18. MCC950 is a specific NLRP3 inflammasome inhibitor. Neutrophil proteases are the dominant activators of IL-1β in passive anti-MPO antibody transfer models, but the role of the NLRP3 inflammasome in active and T cell autoimmunity in MPO-AAV is not known. These studies aimed to determine the therapeutic potential of NLRP3 inflammasome inhibition and assess the role of its targets. IL-1β and IL-18 in experimental anti-MPO glomerulonephritis. <strong>Methods:</strong> To assess anti-MPO autoimmunity, mice were injected with 20ug rMPO in FCA and studied at 10 days. For anti-MPO GN, mice were immunised with 20ug rMPO in FCA day 0 and 20ug rMPO in FIA on day 7. On day 16, low dose of sheep anti-mouse anti-basement membrane globulin was administered to transiently recruit neutrophils to glomeruli. Experiments ended on day 19. Experiments used <em>Nlrp3</em>-/- mice, WT mice treated with MCC950 (20mg/kg daily), IL-1RA (anakinra) or a neutralizing anti-IL-18 antibody, and <em>Il18</em>-/- mice. Renal and immunological (ELISPOT, flow cytometry) endpoints were studied. Glomerular neutrophil recruitment was assessed after 4 hours by administering 10μg LPS, then 1mg of the mouse anti-mouse anti-MPO monoclonal antibody clone 1D1. <strong>Results:</strong> After immunization, <em>Nlrp3</em>-/- mice had fewer activated CD4+T cells and decreased Th1 responses. Compared to WT mice. <em>Nlrp3</em>-/- mice developed less 24-hour albuminuria and glomerular and interstitial histological injury, with fewer macrophages and neutrophils. Compared with saline treated mice, mice with anti-MPO GN that were treated with MCC950, from day 0 (first immunisation) developed less histological injury and albuminuria with lower proportions of activated T cells and lesser Th1 and Th17 responses. MCC950 reduced MPO-stimulated IFN-γ production (ELISPOT) and T cell activation, with fewer CD62L<sub>¯</sub>CD44hi cells. When treatment was commenced at day 9 (after autoimmunity had been established), albuminuria was limited but glomerular histological changes were not significantly reduced, and treatment from day 16 (at the time of anti-basement membrane antibody administration) did not significantly reduce glomerular histology or albuminuria. Acute anti-MPO antibody or anti-basement membrane globulin induced acute neutrophil recruitment was similar in MCC950 treated and control mice. Anti-MPO antibody induced acute neutrophil recruitment was not affected by IL-1RA (anakinra) or by anti-IL-18 antibody treatment. Anakinra treatment limited disease at day 19 of the active model of anti-MPO GN, but <em>Il18</em>-/- mice and WT mice treated with anti-IL-18 antibodies were not protected from nephritis. <strong>Conclusions:</strong> The NLRP3 inflammasome promotes T cell responses and disease in experimental anti-MPO GN. In this active model, endogenous IL-1 but not endogenous IL-18 promotes disease. <strong>Disclosures:</strong> None.