Session Type: ACR Poster Session C
Session Time: 9:00AM-11:00AM
Background/Purpose: Upregulation of interferon-β (IFNβ) is an important step in promoting maturation and survival of B cells. Secretion and autocrine action of IFNβ requires assembly of the IFNβ enhanceosome, including IRF3, IRF7 and NF-ĸB. Interestingly, TLR7 stimulation has been found to induce IRF7 in transitional B cells from SLE patients. The purpose of this study is to determine if IFNβ is upregulated in transitional B cells of SLE patients and if autocrine activity of IFNβ promotes B cell survival.
Methods: Peripheral blood samples were obtained from consented SLE patients with active disease (SLEDAI > 6) during visits to a Lupus Clinic. FACS analysis was carried out using surface staining antibodies IgD, CD24, CD38, CD27 and CD19. Intracellular IFNβ was detected using and antihuman IFNβ (PBL, clone MMHB3). Autoreactive B cells were detected using 9G4. Transitional and mature 9G4+and 9G4B cell subsets were FACS sorted. qRT-PCR was carried using validated primers. Purified B cells were stimulated with TLR7 (CL264, 5 μg/ml) and a goat polyclonal antihuman IgM+IgG (5 μg/ml). IFNβ and IFNα/βR blocking was carried out using a polyclonal anti-IFNβ (500 IU/ml, PBL) and an IFNα/βR blocking Ab (anifrolumab, 5 μg/ml, Creative BioLabs), respectively.
Results: There was a significant increase in intracellular IFNβ determined by both FACS analysis and by RT-PCR in IgD+CD24+CD38+CD27– transitional B cells of SLE patients compared to control subjects (p<0.01). IFNβ was upregulated in both the 9G4+ and 9G4– subpopulations of B cells. The expression of Ifnb in transitional cells further positively correlated with the expression of IFNα genes (Ifna1, Ifna2, and Ifna4) and IFN response genes (Mx1 and Ifit4) (p<0.05). TLR7 plus BCR stimulation upregulated IFNβ and resulted in a significant upregulation of CD69 and CD86 at 4 hrs by both transitional and mature B cells, and increase in survival at 60 hrs in B cells from SLE patients. Importantly, IFNβ neutralization inhibited these responses. The inhibition was equivalent to the blockade of IFNα/βR, indicating that although both IFNα and IFNβ were expressed, these early responses required the release and autocrine activity of intracellular IFNβ.
Conclusion: The present results suggest that, in SLE, induction of type I IFN production by early transitional B cells is a 2-step process. IFNβ acts in an autocrine fashion to promote B cell survival and upregulation of IFNa. IFNa does not play an essential autocrine role but may act on other cells. B cell therapies directed at neutralizing IFNβ may be useful, especially in early-stage SLE prior to IFNβ enhanced development of IFNα producing B cells. Inhibition of IFNβ enhanceosome component(s) that are required for IFNβ production, may serve as a novel target for SLE. *(Supported by NIH R01-AI-071110, R01-AI-083705, P30-AR-048311, T32 AI007051, VA Merit Review grant 1I01BX000600, Lupus Research Institute, Lupus Foundation of America.)
To cite this abstract in AMA style:Hamilton J, Wu Q, Yang P, Luo B, Liu S, Li J, Sanz I, Chatham WW, Hsu HC, Mountz JD. SLE Subjects Express High Levels of Intracellular Interferon-β That Acts in an Autocrine Fashion to Promote Survival of Transitional Stage B Cells [abstract]. Arthritis Rheumatol. 2016; 68 (suppl 10). https://acrabstracts.org/abstract/sle-subjects-express-high-levels-of-intracellular-interferon-%ce%b2-that-acts-in-an-autocrine-fashion-to-promote-survival-of-transitional-stage-b-cells/. Accessed September 21, 2019.
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