ACR Meeting Abstracts

ACR Meeting Abstracts

Abstract Number: 832

Single Cell Analysis Reveals Heterogeneity of Type I IFN Gene Expression in Developing Autoreactive B Cells

Jennie Hamilton1, PingAr Yang2, Qi Wu3, Bao Luo4, Shanrun Liu5, Jun Li6, Mark Walter7, Eleanor Fish8, Hui-Chen Hsu3 and John D. Mountz9, 1Medicine/Division of Clinical Immunology and Rhematology, University of Alabama at Birmingham, Birmingham, AL, 2Department of Medicine, Clinical Immunology & Rheumatology, University of Alabama at Birmingham, Birmingham, AL, 3Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, 4Division of Clinical Immunology and Rheumatology, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, 5Biochemistry & Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL, 6Medicine, University of Alabama at Birmingham, Birmingham, AL, 7Microbiology, University of Alabama at Birmingham, Birmingham, AL, 8University Health Network & Department of Immunology, University of Toronto, Toronto General Research Institute, Toronto, ON, Canada, 9University of Alabama at Birmingham, Department of Medicine, Birmingham, AL

Meeting: 2017 ACR/ARHP Annual Meeting

Date of first publication: September 18, 2017

Keywords: , , ,

Session Information

Date: Sunday, November 5, 2017

Title: B Cell Biology and Targets in Autoimmune Disease

Session Type: ACR Concurrent Abstract Session

Session Time: 2:30PM-4:00PM

Background/Purpose: B cell development involves passage through a formative transitional B cell stage in the spleen. In SLE, self-nucleic acid reactive B cells fail to be deleted at the transitional B cell stage but the factors promoting specific expansion of these autoreactive cells are unknown. Transitional B cells have been shown to exhibit dysregulated type I interferon (IFN) in SLE, and a sub-population of transitional and naïve B cells from SLE patients were recently shown to express high levels of IFNα. The purpose of these studies was to investigate if B cell endogenous type I IFN can act in an autocrine manner to promote survival and development of autoreactive transitional B cells.

Methods: Wild type C57BL/6 (B6), B6-CD45.1, CD45.2 B6-Rag1–/–, and BXD2 were obtained from Jackson Lab. B6-IFNβ-/- mice were provided by Dr. Fish. A 1:1 ratio of bone-marrow cells was used to reconstitution. Type1 interferon-α or IFNβ stimulation or blockade was carried out using validated sources. Single-cell QRT-PCR was carried out using a Fluidigm-BioMark system on FACS-sorted T1 B cells. Hierarchical clustering was carried out using ClustVis.

Results: Examination of all B cells subsets in B6 and BXD2 mouse spleen revealed that transitional stage 1 (T1) B cells expressed high levels of type I IFNα genes and IFNβ in both strains. T1 B cells from BXD2 lupus-prone mice overexpressed IFNβ relative to B6 mice, and intriguingly, T1 B cells expressed IFNβ at levels comparable to pDCs. T1 B cells from both B6 and BXD2 mice also exhibited higher expression of IFNαR1 and expressed CD86 and CD69 upon IFNβ stimulation. TLR7 responses following stimulation with CL264 was highly dependent upon this endogenous IFN-β in T1 B cells, but not in other B cell subpopulations. Single-cell examination of Ifnb-/- vs. Ifnb+/+ T1 B cells revealed heterogeneous expression of IFNβ in WT T1 B cells and distinct gene expression signatures that required endogenous IFNβ. IFNβ-/- T1 B cells exhibited significantly lower expression of CD86, TLR7, and PKR, and type I IFN genes. Single cell analysis of autoimmune BXD2 T1 B cells that overexpressed IFNβ revealed that IFNβ is expressed in early T1 B cell development with subsequent upregulation of TLR7 and IFNαs. Functional analysis of Ifnb+/+ and Ifnb-/- B cells derived from double chimeric mice revealed that IFNβ was required for development of germinal center, autoreactive, and IgG class switched anti-DNA, anti-La and anti-Histone autoAb producing B cells.

Conclusion: Together, these data highlight the role of IFNβ in shaping T1 B cell responses in the mouse spleen, including their survival and responses to TLR7. Notably, they indicate that these effects are mediated through the endogenous expression of IFNβ in T1 B cells. This mechanism suggests that endogenous IFNβ-expressing T1 B cells are initially autonomous and that their expression of IFNβ plays a key role in regulating their responsiveness to external factors, including externally-derived type 1 IFNs and TLR7. In lupus, overexpression of IFNβ in T1 B cells may promote the development of autoreactive mature B cells leading to the generation of polyreactive self-antigen-reactive mature B cells.

Disclosure: J. Hamilton, None; P. Yang, None; Q. Wu, None; B. Luo, None; S. Liu, None; J. Li, None; M. Walter, None; E. Fish, None; H. C. Hsu, None; J. D. Mountz, None.

To cite this abstract in AMA style:

Hamilton J, Yang P, Wu Q, Luo B, Liu S, Li J, Walter M, Fish E, Hsu HC, Mountz JD. Single Cell Analysis Reveals Heterogeneity of Type I IFN Gene Expression in Developing Autoreactive B Cells [abstract]. Arthritis Rheumatol. 2017; 69 (suppl 10). https://acrabstracts.org/abstract/single-cell-analysis-reveals-heterogeneity-of-type-i-ifn-gene-expression-in-developing-autoreactive-b-cells/. Accessed .

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