Date: Monday, October 22, 2018
Session Type: ACR Poster Session B
Session Time: 9:00AM-11:00AM
Background/Purpose: Increased type I interferon (IFN) has been shown to affect survival and activation of B cells in SLE. This study investigated novel mechanisms of endogenous production and autocrine activity of IFNβ in SLE B cells at the single-cell level.
Methods: IFNβ in B cells from SLE patients was analyzed using t-SNE platform based high dimensional flow cytometry. Intracellular IFNβ expression was visualized and analyzed by super-resolution confocal imaging and ImageStream analysis. Single cell gene expression analysis was carried out using the Fluidigm/BioMark system for targeted expression of low abundance genes, and the 10x Chromium platform for unbiased transcriptome analysis of up to 4,000 B cells per subject. Functional production of type I IFNs by B cells was analyzed using a human type I IFNs SEAP reporter HEK293 cell line.
Results: High dimension flow cytometry analysis identified intracellular IFNβ expression in pDCs, B cells, and CD4 T cells. There was increased expression of IFNβ in B cells from PBMCs of African American SLE patients compared to European SLE patients and healthy controls. B-cell intracellular IFNβ was associated with serum positivity of ANA and renal disease. Using a Fluidigm targeted-gene approach, B cells could be divided into three subpopulations, namely IFNB+, IFNA+, and ISG+ subpopulations, suggesting B cells not only respond to type I IFNs but also express type I IFNs including IFNB and different IFNA genes. TLR7 and TLR3 were mainly expressed by IFNB+ and IFNA+ cells, respectively. The production of functional IFNβ and IFNα protein by single B cells from SLE subjects and was verified using a novel AP live staining of HEK-blue reporter cells. There was enhanced IFNAR signaling by reporter cells in direct contact with SLE B cells which was blocked by anti-IFNβ and anti-IFNα. Unbiased single cells transcriptome analysis of SLE B cells using the 5’ 10X Chromium platform and Loupe™ V(D)J Browser indicated that gene clusters in type I IFN expressing or responding SLE B cells exhibited unique heavy- and light-chain gene expression repertoires.
Conclusion: (i) B cells are an important source of type I IFNs in modulating TLR and BCR responses in SLE; (ii) well-orchestrated and distinct programs in type I expression and responses genes in subsets of B cells, and (iii) distinct pathways of B cell survival and activation based on combined signaling through TLR, BCR and IFNAR with a distinct BCR heavy- and light-chain repertoire.
This work was supported by grants from R01-AI-071110, R01 AI134023, I01BX004049, 1I01BX000600 and Lupus Research Alliance Distinguished Innovator Award to J.D.M, R01-AI-083705 and the LRA Novel Research Award to H-C.H., and the P30-AR-048311 and the P30-AI-027767 to support flow cytometry analysis.
To cite this abstract in AMA style:Mountz JD, Liu S, Yang P, Wu Q, Luo B, Chatham WW, Hsu HC. Endogenous Ifnβ Production Is Required for Efficient BCR Crosslinking and Survival of SLE B Cells [abstract]. Arthritis Rheumatol. 2018; 70 (suppl 10). https://acrabstracts.org/abstract/endogenous-ifn%ce%b2-production-is-required-for-efficient-bcr-crosslinking-and-survival-of-sle-b-cells/. Accessed August 12, 2020.
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