ACR Meeting Abstracts

ACR Meeting Abstracts

Abstract Number: 1094

Endogenous Ifnβ Production Is Required for Efficient BCR Crosslinking and Survival of SLE B Cells

John D. Mountz1, Shanrun Liu2, PingAr Yang3, Qi Wu4, Bao Luo5, W. Winn Chatham6 and Hui-Chen Hsu4, 1University of Alabama at Birmingham and Birmingham VA Medical center, Birmingham, AL, 2Biochemistry & Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL, 3Department of Medicine, Clinical Immunology & Rheumatology, University of Alabama at Birmingham, Birmingham, AL, 4Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, 5Division of Clinical Immunology and Rheumatology, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, 6Medcine/Clinical Immunology and Rheumatology, University of Alabama at Birmingham, Birmingham, AL

Meeting: 2018 ACR/ARHP Annual Meeting

Keywords: , , ,

Session Information

Date: Monday, October 22, 2018

Title: Systemic Lupus Erythematosus – Etiology and Pathogenesis Poster II

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.

Disclosure: J. D. Mountz, None; S. Liu, None; P. Yang, None; Q. Wu, None; B. Luo, None; W. W. Chatham, None; H. C. Hsu, None.

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 9). https://acrabstracts.org/abstract/endogenous-ifn%ce%b2-production-is-required-for-efficient-bcr-crosslinking-and-survival-of-sle-b-cells/. Accessed .

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