Session Type: ACR Abstract Session
Session Time: 4:30PM-6:00PM
Background/Purpose: Studies to date have primarily focused on stimulators that are overexpressed and activate B cells in SLE subjects. Factors that can maintain B cells in a resting state and may be under-expressed in SLE are largely unknown. We utilized a combined single-cell B cell transcriptome and high dimensional flow cytometry analysis approach for a coordinated understanding of factors that are both over- and under-expressed in B-cell developmental checkpoints in SLE.
Methods: The expression of IL-4R and interferon beta (IFNβ) in subsets of B cells was analyzed using high dimensional flow cytometry analysis (n=47 patients who met the ACR classification criteria for SLE). Total B cells from 3 autoantibody (anti-DNA,,anti-Sm, and anti-histone)+ African American (AA) SLE patients, 1 autoAb(−) Europeran American (EA) SLE patient and 1 AA healthy control were purified using the StemCell Human B cell isolation kit. A high-throughput scRNA-seq was carried out using a droplet-based 10x Chromium approach. The effects of IL-4 on IFNβ-induced IRF7 as well as on IFNɣ + a defined stimulatory media (DSM)(anti-Ig+BAFF+IL-21+TLR7+IL-2)-induced double negative 2 (DN2: CD21−CD27−IgD−CD11c+T-bet+) B cells were analyzed using an in vitro culture approach.
Results: At the protein level, within naïve (IgD+CD27−) B cells, higher expression of IFNβ and lower expression of IL-4R correlated with the percent of activated naïve CD21loIgD+ and CD21loIgD− DN B cells. There was higher percent of IFNβ+IL-4Rlo naïve B cells in AA compared to EA SLE patients. However, in EA, but not AA, patients, higher percent of IFNβ+IL-4Rlo naïve B cells was found in anti-Sm+ and renal disease+ patients. scRNA-seq analysis shows that the molecular signature of B cells from autoAb(+) patients is type I IFN stimulated genes (ISGs), including IRF7, ISG15, ISG20, MX1, and STAT1. The molecular signature of B cells from autoAb(-) patients is IL4R, BACH2, S1PR1, and FCER2. The high ISG and low IL4R was evident during the early transitional stage 1 B cells and persisted in pre-switched IGHD+ B cells. Stimulation of B cells with DSM+IFNɣ promoted DN2 development whereas addition of IL-4 inhibited DN2 and preserved B cells at the resting naïve stage (IgD+CD11c−T-bet−). IL-4 also inhibited IFNβ-induced IRF7.
Conclusion: Down-regulation of IL-4R in naïve B cells is a major dysregulation in SLE since it may predispose SLE B cells to both type I IFN and type II IFN stimulation. Further, lower IL-4R together with upregulation of endogenous IFNβ in naïve B cells was an important signature for activated naïve B cells. Such signature was associated with development of DN2 B cells and, in EA patients, development of anti-Sm autoantibody. Modulation of IL-4R signaling may be developed into a novel therapy for SLE.
To cite this abstract in AMA style:Mountz J, Gao M, Wu Q, Yang P, Essman A, Ojo O, Liu S, Chen J, Sanz I, Chatham W, Hsu H. Lower IL-4R in IgD+ Naïve B Cells Is a Pre-disposing Factor for Development of T-bet+ DN2 B Cells in Systemic Lupus Erythematosus [abstract]. Arthritis Rheumatol. 2019; 71 (suppl 10). https://acrabstracts.org/abstract/lower-il-4r-in-igd-naive-b-cells-is-a-pre-disposing-factor-for-development-of-t-bet-dn2-b-cells-in-systemic-lupus-erythematosus/. Accessed March 8, 2021.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/lower-il-4r-in-igd-naive-b-cells-is-a-pre-disposing-factor-for-development-of-t-bet-dn2-b-cells-in-systemic-lupus-erythematosus/