CCR6 is transiently upregulated on B cells after activation and modulates the germinal center reaction in the mouse

Abstract

The CC-chemokine receptor 6 (CCR6) is expressed constitutively at an intermediate level on naı¨ve B cells and is upregulated after activation on pregerminal center (GC) B cells. We hypothesized that it could be involved in the events leading to GC reaction and high-affinity antibody production, and therefore investigated the potential role of CCR6 in B-cell differentiation in vivo. After antigenic challenge of CCR6 À/ À mice with the T-cell-dependent antigen nitrophenyl-keyhole limpet hemocyanin (NP-KLH), GC B-cell development was found to be accelerated and the number of GC had increased significantly compared with control mice, but the antibodies produced by CCR6 À/ À B cells were on average of lower affinity. We conclude from these data that the CCR6/CCL20 axis has an important role in regulating the kinetics and efficiency of the GC reaction. Navigation of B cells in secondary lymphoid organs is driven by differential expression of the G protein-coupled chemokine receptors and their chemokine ligands. 1-3 After contact with antigen, B cells move to the T-B-cell border directed by the CC-chemokine receptor 7 (CCR7) 4 in order to receive T-cell help. [5][6][7] This cognate interaction between T and B cells results in the formation of T-B conjugates that last for extended periods of time. 5-7 Subsequently, B-cells move to the follicle 4,8 guided by CXCR5, where they undergo a burst of proliferation and form germinal centres (GC) 9-11 that facilitate somatic hypermutation and affinity maturation. CC-chemokine receptor 6 (CCR6) can be detected at a high level on activated B cells that receive T-cell help at the T-B intersection, and subsequently enter the follicle. 7 We addressed the specific role of CCR6 on B cells and found that in its absence, the generation of GC was faster and the number increased. RESULTSTo elucidate the timing of CCR6 upregulation in the context of B-cell activation and T-B cell interaction, we transferred splenocytes, which had been isolated from transgenic mice carrying a nitrophenyl (NP)-specific B-cell receptor (B1-8 low , 3Â 10 7 splenocytes/transfer) into congenic CD45.1 þ recipient mice, and immunized them with NP-keyhole limpet hemocyanin (NP-KLH). After 5 days, using CCR6 and CD45 expression, three populations of donor B cells were distinguishable (Figure 1a). These populations, termed here A, B and C, were analyzed for their expression of GL7 and CD38 (Figure 1b). Population A and C represented naïve and GC B cells, respectively. Population B was CCR6 hi and CD38 þ and was transient between naïve and GC B cells (Figure 1b). The percentage of naïve B cells decreased with time, whereas the percentage of GC B cells increased. The size of the transient population proved to be variable in individual mice, possibly due to small changes in the individual kinetic of the B-cell response (Figure 1c). To determine whether the CCR6 hi B-cell population corresponded to activated blasts or memory B cells, we analyzed their forward scatter/side scatter characteristics, and found that the forwar...

Mycophenolate mofetil reduces STAT3 phosphorylation in systemic lupus erythematosus patients

“…Although MMF+ patients had no observed differences in naive, memory, or double-negative B cell numbers compared with MMF-patients (Supplemental Tables 1 and 2), the expression of CD38, CD86, and CCR6 on naive B cells and CD86 on memory B cells was at significantly lower frequencies on peripheral blood cells of MMF+ patients compared with MMF-patients ( Figure 3, A-E). Plasmablasts, which were decreased systemically in MMF+ patients by t-SNE analysis, also had lower expression of CCR6, a chemokine receptor upregulated after activation in B cells and important for the recall response to antigen (16,17) (Figure 3, D and F). Despite differences in memory B cells, IgD -CD27double-negative B cells, also known as nonconventional memory B cells, only trended lower in CCR6, CD38, and CD86 expression ( Figure 3, G-I).…”

CCR6-Dependent Positioning of Memory B Cells Is Essential for Their Ability To Mount a Recall Response to Antigen

“…The data shows that a high frequency of B mem cells express CCR6 and have a heightened chemotactic response to CCL20 compared to naïve B cells. It is known that there is broad CCR6 expression across B cell subsets in the mouse and CCR6 is expressed at higher levels transiently during cognate activation of B cells (26, 27). CCR6-deficient mice have a faster GC response compared with littermate controls, resulting in an increase of low affinity antigen-specific plasmablasts (26).…”

“…It is known that there is broad CCR6 expression across B cell subsets in the mouse and CCR6 is expressed at higher levels transiently during cognate activation of B cells (26, 27). CCR6-deficient mice have a faster GC response compared with littermate controls, resulting in an increase of low affinity antigen-specific plasmablasts (26). Interestingly though, like in this report, prior authors showed that there was heightened histological accumulation of activated B cells in the GC/follicle in the CCR6 −/− mice.…”

CCR6 Deficiency Impairs IgA Production and Dysregulates Antimicrobial Peptide Production, Altering the Intestinal Flora

“…Interestingly, the critical role for CCR6 in GC responses does not seem to be restricted to mucosal lymphoid tissues, as recent studies have shown abnormal GC responses in spleens and diminished high-affinity, antigen-specific IgG production in CCR6 −/− mice upon antigen challenge (66, 67). Our study, along with these previous studies, implies that in addition to CXCR5, which is known to be important for GC reactions and antibody production, CCR6 expression on B cells is also crucial for GC reactions and TD antibody production.…”