Human CD9⁺ B cells express CD14 upon TLR9 stimulation and the frequency of CD9 expressing B cells is negatively correlated with SLE disease severity

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Presentation Time: 02:15 PM - 03:30 PM
Poster Board Number: B602
Abstract ID: 5523

Presenting Author:
Lance K Blevins , Assistant Professor at Michigan State Univ.

Abstract:

Systemic lupus erythematous (SLE) is a multifactorial disease affecting 1.5 million people in the US. While therapies exist to manage SLE disease symptoms, there is no cure and many SLE patients are treatment resistant or experience frequent disease flares. A major focus in SLE research is the role of Toll-like receptor 9 (TLR9) signaling in modulating tolerance of B cells to self-antigen, promoting immune activation and the production of auto-antibodies. Here we characterize a novel population of human B cells which respond to TLR9 stimulation by expressing cell surface CD14 and intracellular CXCL8, a chemokine positively associated with SLE severity. CD14⁺ B cells also express CD9, a tetraspanin, and aryl hydrocarbon receptor. To determine if CD14 and/or CD9 are associated with SLE disease, we characterized CD19⁺ B cells from PBMC isolated from SLE patients or controls. Despite equivalent frequencies of circulating B cells, SLE patients had a higher frequency of CD14 single positive B cells corresponding to a significant decrease in CD9⁺ B cells. When comparing SLE patients in an active flare to those not, we found that CD9 positivity was reduced in the active flare cohort. When the frequency of CD14⁺ or CD9⁺ B cells were correlated to the SLE disease activity index (SLEDAI), there was a strong association between loss of CD9 positivity and SLE disease severity suggesting CD9⁺ B cells may limit SLE disease and serve as a potential biomarker for SLE disease activity.