Session Type: Poster Session (Monday)
Session Time: 9:00AM-11:00AM
Background/Purpose: Loss of systemic self-tolerance leading to anti-nuclear autoantibody (ANAs) by B cells is a hallmark of SLE. However, up to 20% of healthy female individuals are also ANA+, and most will never develop clinical autoimmune disease. The B cell pathways involved in autoimmune progression and regulation of healthy ANA+ individuals is unknown.
Methods: Peripheral blood mononuclear cells (PBMCs) from African American ANA- (n=6), ANA+ healthy individuals (n=6) and SLE (n=6) subjects were sorted for CD3-CD19+ B cells by flow cytometry and RNA was isolated for next-generation sequencing. Differential gene expression, Weighted Gene Correlation Network Analysis and pathway analysis were used to identify differences in pathways and upstream regulators. scRNA-sequencing of B cells from PBMCs were used to determine frequencies and identify differential gene signatures in specific B cells subsets. Plasma soluble mediators were assessed by xMAP multiplex arrays and used for linear regression analyses.
Results: Pathway analysis of total B cells in ANA+ healthy individuals revealed unique pathway modules with elevated eigengene scores associated with p53 signaling (p=0.000275), TNFRII signaling (p=0.0000699), apoptosis (p=0.00399) and death receptor signaling (p=0.00902) compared to ANA- controls and SLE patients. Using scRNA-seq analysis, seven distinct B cell populations among all subjects were identified using a community detection algorithm and visualized using Uniform Manifold Approximation Projection. The proportion of total B cells within each cluster varied by disease status. A unique cluster of CD69low naïve B cells was more prevalent in ANA+ healthy subjects, memory B cells also trended higher in ANA+ healthy individuals, while SLE patients were characterized by higher frequencies of plasma cells and CD69high naïve B cells. Gene expression signatures of p53/TNFRII, apoptosis, and death receptor signaling were elevated in all B cell subsets of ANA+ healthy individuals (Figure 1A-B). In ANA+ healthy individuals, the elevated gene expression signatures in memory B cells correlated negatively with plasma IFNα (p=0.0027), IL-15 (p=0.011), IP-10 (p=0.027), IL-10 (0.025), TNFRII (p=0.029), and IL-23 (p=0.038) levels, and negatively in CD69low naïve B cells with IFNα (p=0.012) and TNFRII (p=0.045) levels (Figure 1C-F). SLE patients exhibited higher plasma levels of multiple cytokines including IFNα and associated mediators, TNFRII, IL-10, BLyS and Th1/2/17 associated mediators (p< 0.05).
Conclusion: ANA+ healthy individuals have enhanced gene expression in B cell pathways that drive apoptosis and cell cycle suppression, which may regulate autoreactive T cell activation, and proliferation, and subsequent clinical autoimmune pathogenesis. This provides clues into potential targets for prevention of clinical autoimmunity.
To cite this abstract in AMA style:Bylinska A, Slight-Webb S, Smith M, Macwana S, Dominguez N, Chakravarty E, Merrill J, James J, Guthridge J. Alterations of Memory and Naive B Cell Subsets Associate with Reduced IFNα and TNFRII in ANA+ Healthy Individuals [abstract]. Arthritis Rheumatol. 2019; 71 (suppl 10). https://acrabstracts.org/abstract/alterations-of-memory-and-naive-b-cell-subsets-associate-with-reduced-ifn%ce%b1-and-tnfrii-in-ana-healthy-individuals/. Accessed June 5, 2020.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/alterations-of-memory-and-naive-b-cell-subsets-associate-with-reduced-ifn%ce%b1-and-tnfrii-in-ana-healthy-individuals/