Human Regulatory B Cells Combine Phenotypic and Genetic Hallmarks with a Distinct Differentiation Fate

Abstract

Regulatory B cells (B-reg) produce IL-10 and suppress inflammation in both mice and humans, but limited data on the phenotype and function of these cells have precluded detailed assessment of their contribution to host immunity. In this article, we report that human B-reg cannot be defined based on a phenotype composed of conventional B cell markers, and that IL-10 production can be elicited in both the CD27+ memory population and naive B cell subset after only a brief stimulation in vitro. We therefore sought to obtain a better definition of IL-10–producing human B-regs using a multiparameter analysis of B cell phenotype, function, and gene expression profile. Exposure to CpG and anti-Ig are the most potent stimuli for IL-10 secretion in human B cells, but microarray analysis revealed that human B cells cotreated with these reagents resulted in only ∼0.7% of genes being differentially expressed between IL-10+ and IL-10− cells. Instead, connectivity map analysis revealed that IL-10–secreting B cells are those undergoing specific differentiation toward a germinal center fate, and we identified a CD11c+ B cell subset that was not capable of producing IL-10 even under optimal conditions. Our findings will assist in the identification of a broader range of human pro–B-reg populations that may represent novel targets for immunotherapy.

Regulatory B Cells with a Partial Defect in CD40 Signaling and Overexpressing Granzyme B Transfer Allograft Tolerance in Rodents

“…2) (33). Note that these B cells, however, expressed a higher level of Irf4 transcripts following stimulation, a gene recently identified as one of the most significantly upregulated in IL-10 + -producing B cells (12). These differences were lost by the addition of CpG (data not shown), suggesting that CpG may induce a too strong stimulation or that the effects observed were specific to CD40 stimulation.…”

“…Regulatory B cells may be composed of cells with a heterogeneous phenotype and present at various steps of differentiation. Indeed, it has been suggested that regulatory B cells acquired their fully suppressive phenotype following reencounter with the specific Ags at the plasmablast/ plasma cell differentiation step by acting through the secretion of a high level of immunosuppressive cytokine such as IL-10 or IL-35 (9,12,38,39). We observed in a mouse skin graft model that LF15-0195 immunosuppressor induced during treatment a strong drop in the new T1 emigrants B cells in blood that were then restored following treatment cessation (E. Chiffoleau, unpublished results).…”

“…Therefore, characterization has relied exclusively on assessing their suppressive activity. Although several regulatory B cell subsets have been described in humans and mice, most of them share the ability to express the anti-inflammatory cytokine IL-10 and can be identified in the transitional immature, naive, CD27 + memory as well as the plasmablast/plasma B cell subpopulations (6)(7)(8)(9) (10)(11)(12)(13). We previously demonstrated a model of cardiac allograft tolerance in the rat induced by a short-term treatment with the immunosuppressor LF15-0195, a deoxyspergualin analog (14,15).…”

Bregs in Chronic HBV: Is It Time for Bragging Rights?

“…, a fair characterization given the current knowledge of the Breg phenotype. In fact, several phenotypes have been reported to define Bregs in mice and humans, raising the possibility that distinct subsets of Breg exist in different tissues and compartments in vivo [7,11].…”

“…Recently, a connectivity map analysis revealed that IL-10? B cells are those specifically undergoing differentiation toward a germinal center B cell fate [11]. These cells were identified as CD11c-negative B cells, had suppressive activity, and were unable to efficiently differentiate into plasma cells.…”