EBI2 mediates B cell segregation between the outer and centre follicle

Abstract

B cell follicles are specialized microenvironments that support events necessary for humoral immunity 1, 2, 3. Following antigen encounter, activated B cells initially seek T cell help at the follicle-T zone boundary and then move to interfollicular and T-zone distal (outer) regions of the follicle 4, 5, 6, 7, 8, 9, 10. Subsequently, some cells move to the follicle center, become germinal center (GC) B cells and undergo antibody affinity maturation 1, 2, 11. Although germinal ‘centers’ within follicles were described in 1885 12, the molecular cues mediating segregation of B cells between outer and center follicle have remained undefined. Here we establish a role for the orphan G-protein coupled receptor, Epstein Barr Virus-induced molecule-2 (EBI2) 13, in this process. EBI2 is expressed in mature B cells and increases in expression early after activation before being down-regulated in GC B cells. EBI2 deficiency led to a reduction in the early antibody response to a T-dependent antigen. EBI2-deficient B cells failed to move to the outer follicle at day 2 of activation and instead were found in the follicle center, whereas EBI2 over-expression was sufficient to promote B cell localization to the outer follicle. In mixed bone marrow chimeras, EBI2-deficient B cells phenocopied GC B cells in preferentially localizing to the follicle center. When down-regulation of EBI2 in wild-type B cells was antagonized, participation in the GC reaction was impaired. These studies identify an important role for EBI2 in promoting B cell localization in the outer follicle, and show that differential expression of this receptor helps position B cells appropriately for mounting T-dependent antibody responses.

Redemption of autoantibodies on anergic B cells by variable-region glycosylation and mutation away from self-reactivity

“…2G). The bias toward GC differentiation in self-reactive B cells may result from decreased BCR signaling to NF-κB and consequent poor induction of Ebi2 and Irf4 in anergic B cells (37), because induction of these genes favors plasma cell differentiation and disfavors GC differentiation (38)(39)(40).…”

Oxysterols and EBI2 promote osteoclast precursor migration to bone surfaces and regulate bone mass homeostasis

“…EBI2 is a chemoattractant receptor of the GPCR family with no known roles other than controlling cell migration and/or positioning. Specifically, EBI2 promotes the positioning of dendritic cells and activated B lymphocytes to specialized outer and interfollicular niches in secondary lymphoid organs and plays important roles in primary antibody responses (Gatto et al, 2009(Gatto et al, , 2013Pereira et al, 2009bPereira et al, , 2010aYi et al, 2012;Yi and Cyster, 2013). Thus, the phenotypic similarity between EBI2-and CH25H-deficient mice favor a model in which oxysterols sensed by EBI2 expressed in OCPs regulate bone mass homeostasis predominantly by promoting OCP cell movement and positioning, which facilitates cell fusion and enhances the development of large OCs.…”

“…However, systemic RANKL administration has been shown to increase OCP homing back to BM and to promote local OC differentiation (Kotani et al, 2013). These studies suggest that OCP movement in and out of BM tissue is highly regulated and that balanced responsiveness to B lymphocyte migration in secondary lymphoid organs (Gatto et al, 2009(Gatto et al, , 2013Pereira et al, 2009b;Hannedouche et al, 2011;Kelly et al, 2011;Liu et al, 2011;Yi and Cyster, 2013), in controlling monocyte and OCP movement and positioning within BM. We show that EBI2 is highly expressed in OCPs and mature OCs and promotes OCP motility in vitro and in various chemoattractants regulates OCP movement and differentiation.…”

“…C57BL/6 mice were obtained from The Jackson Laboratory. The generation of Ebi2 GFP/GFP mice was described previously (Pereira et al, 2009b Kikuta et al, 2013). TRA-P Red mice were intercrossed with Ebi2 GFP/GFP and with Ch25h / mice to generate TRAP Red Ebi2 GFP/GFP and TRAP Red Ch25h / and littermate control mice.…”

“…EBI2 and its oxysterol ligands control immune cell migration (Gatto et al, 2009;Pereira et al, 2009bPereira et al, , 2010aHannedouche et al, 2011;Liu et al, 2011). We hypothesized that EBI2 promotes BMDM and OCP migration, thereby influencing cell-cell interaction and cell fusion.…”