Oxysterols direct B-cell migration through EBI2

Abstract

EBI2 (also called GPR183) is an orphan G-protein-coupled receptor that is highly expressed in spleen and upregulated upon Epstein-Barr-virus infection. Recent studies indicated that this receptor controls follicular B-cell migration and T-cell-dependent antibody production. Oxysterols elicit profound effects on immune and inflammatory responses as well as on cholesterol metabolism. The biological effects of oxysterols have largely been credited to the activation of nuclear hormone receptors. Here we isolate oxysterols from porcine spleen extracts and show that they are endogenous ligands for EBI2. The most potent ligand and activator is 7α,25-dihydroxycholesterol (OHC), with a dissociation constant of 450 pM for EBI2. In vitro, 7α,25-OHC stimulated the migration of EBI2-expressing mouse B and T cells with half-maximum effective concentration values around 500 pM, but had no effect on EBI2-deficient cells. In vivo, EBI2-deficient B cells or normal B cells desensitized by 7α,25-OHC pre-treatment showed reduced homing to follicular areas of the spleen. Blocking the synthesis of 7α,25-OHC in vivo with clotrimazole, a CYP7B1 inhibitor, reduced the content of 7α,25-OHC in the mouse spleen and promoted the migration of adoptively transferred pre-activated B cells to the T/B boundary (the boundary between the T-zone and B-zone in the spleen follicle), mimicking the phenotype of pre-activated B cells from EBI2-deficient mice. Our results show an unexpected causal link between EBI2, an orphan G-protein-coupled receptor controlling B-cell migration, and the known immunological effects of certain oxysterols, thus uncovering a previously unknown role for this class of molecules.

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

“…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.…”

“…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.…”

Naive B-cell trafficking is shaped by local chemokine availability and LFA-1–independent stromal interactions

“…Male and female 8-to 12-week-old CXCR5 2/2 mice, 4,5,8 plt/plt mice, 6,7,18 CCR7 2/2 mice, [8][9][10]19 and ICAM-1-deficient mice [11][12][13][14]20 on the C57BL/6 background were bred at our animal facility (Bern, Switzerland); Ebi2 2/2 mice (C57BL/6 strain) and CH25H 2/2 mice 3,21 on the C57BL/6 background were bred at Novartis (Basel, Switzerland). Sex-and age-matched C57BL/6 mice (Harlan, the Netherlands) were used as wild-type lymphocyte donor or recipient mice.…”

“…[8][9][10] Naive B cells also express moderate levels of Ebi2 (ie, GPR183), a GPCR binding 7a,25-dihydroxycholesterol (7a,25-OHC) produced by the cholesterol 25-hydroxylase (CH25H) and that mediates accumulation of B cells to the outer rim of B-cell follicles. [11][12][13][14] Despite these insights, there are remarkably few data that describe how chemokine receptors control active B-cell motility within lymphoid tissue. Since naive B cells express chemokine receptors for both the T-cell area and B-cell follicles, an attractive hypothesis is that the balanced responsiveness to CCR7 ligands of the T-cell area and CXCL13 in B-cell follicles shapes dynamic B-cell motility and restrains entry of CXCR5 2/2 B cells into follicles.…”

B-lymphocyte lineage cells and the respiratory system

“…[29][30][31] Recently, a novel ligand for EBI2 was identified as 7α,25-dihydroxycholesterol, and was shown to be critical for the migration of EBI2 + cells to extrafollicular sites. 32,33 Differential expression of specific transcription factors also regulates this fate decision. Whereas high expression of Blimp-1 and IRF4 (interferon regulatory factor 4) are required for plasma cell development, high expression of Bcl-6 is required for GC differentiation, and Blimp-1 and Bcl-6 repress each other (see below).…”