Author Of 1 Presentation
P0973 - Impact of Epstein-Barr virus infection on CXCR3+ B-cell development: lessons learned from immunotherapies in MS (ID 751)
Abstract
Background
Epstein-Barr virus (EBV) infection of B cells is strongly associated with the onset of several chronic inflammatory and autoimmune diseases such as multiple sclerosis (MS). In MS, a subset of memory B cells infiltrates the central nervous system (CNS) and further differentiates into antibody-secreting cells to mediate local pathology.
Objectives
Here, we aimed to decipher whether and how EBV impacts the development of such CNS-homing memory B cells in MS patients.
Methods
Chemokine receptor profiles were analyzed for ex vivo B cells in single-cell suspensions obtained from paired CNS compartments of 10 MS patients (NBB) using multicolor flow cytometry. The CNS infiltration capacity of memory B-cell subsets was confirmed using confluent brain endothelial monolayers. Similar analyses were performed for distinct memory subsets in the blood from 16 untreated, 32 natalizumab-treated and 9 bone-marrow transplant (BMT)-treated MS patients as well as matched healthy controls. An IL-21-/CD40L-based germinal center-like culture system was used to compare naive and memory B-cell differentiation. EBV copy numbers were determined in total and memory B cells using a multiplex BALF5-related qPCR assay.
Results
CXCR3-expressing B cells were selectively enriched in paired CSF, meningeal and brain tissues versus blood of MS patients. Treatment of patients with natalizumab resulted in an accumulation of CXCR3high IgG+ B cells in the blood, corresponding to their increased ability to cross CNS barriers in vitro. Naive B cells developed into plasmablasts under IFN-γ-mediated germinal center-like conditions and required additional TLR9 signaling for differentiation into CXCR3+ switched memory cells. In 3-7 months post- vs pre-BMT blood samples, EBV DNA load was elevated and positively correlated to the frequency of CXCR3+, and not CXCR4+ or CXCR5+, switched memory B cells. High EBV load in memory B cells from natalizumab-treated MS patients corresponded to an increased potential to develop into anti-EBNA1 IgG-producing CXCR3+ plasma cells (CD38++CD27++CD138+) during IFN-γ-mediated germinal center-like cultures.
Conclusions
This study implicates that persistent viral infections such as EBV potentiate brain-homing and antibody-producing CXCR3(T-bet)+ B cells in MS patients. These findings may mechanistically link EBV infection to anti-EBNA1 IgG production as being a predictor of disease onset and to the massive B-cell influx into the CNS after natalizumab discontinuation in MS.