Immunity & infection
Regulatory B cells (Bregs) have been described in mice and humans for their ability to regulate inflammation through a variety of mechanisms in different pathological situations. Up to date, no consensual and common Breg phenotype has been described, and whether there is a Breg lineage commitment or if they acquire their function under certain environmental conditions remains unknown. To address these points, we performed a sample size weighted meta-analysis of publicly available transcriptomic data from 4 different Bregs studies in humans and 6 Bregs studies in mice. In humans, 1265 genes were differentially expressed with a false discovery rate <5%. This pattern was cross-validated to highlight a core Breg signature of 61 unique genes. A similar analysis in mice revealed a core signature of 174 differentially expressed genes with a false discovery rate <5%. The comparison between humans and mice datasets identified a unique common signature of 11 genes. While we observed high levels of expected genes, such as IL10, in Bregs, we also highlighted additional genes related to regulatory function in humans and mice, including GZMB and CD9. This transcriptional profile is under validation within different Breg populations by qPCR and flow-cytometry. Identification of a unique and common transcriptional Breg signature as well as extracellular markers will allow identifying, characterizing and sorting Breg cells and will offer new options for future cell therapy.