Aberrant frequency of IL-10-producing B cells and its association with the balance of Treg/Th17 in children with inflammatory bowel disease

Regulatory B cells (Breg) are a distinct B cell subset, which contribute to the pathogenesis of autoimmune disorders. Interleukin-10 (IL-10) plays a pivotal function to Breg. It is well described in adults but little is known in a pediatric population. This study was to investigate the role of IL-10-producing B cell (B10) and its association with Treg and Th17 subsets in the children with inflammatory bowel diseases (IBD). Peripheral blood mononuclear cells from IBD children patients and controls were stimulated with PMA, ionomycin, and brefeldin A. The frequencies of CD19+IL-10+ B cells, CD3+CD4+IL-17+Th17 cells, and CD4+ CD25(hi)Foxp3+ Treg cells were analyzed by flow cytometry. The mRNA expression of Foxp3, IL-17a and RORγt was detected by real-time quantitative PCR. The number of B10 cells was elevated in IBD children patients. There was a positive correlation between B10 cells and Tregs in IBD. The ratio of Treg/Th17 decreased in IBD, and it strongly correlated with B10 cells. The frequency of B10 cells is elevated in IBD and it correlates with both the Tregs counts and the Treg/Th17 ratio. B10 cells to regulate functional T cell subsets might be impaired in paediatric patients with IBD.