Ulcerative Colitis Is Characterized by a Decrease in Regulatory B Cells.

BACKGROUND AND AIMS: Ulcerative colitis (UC) is characterized by Th2-polarized, B cell responses. However, neither size, composition, nor activity of the Breg compartment in active UC has been evaluated.

METHODS

Peripheral blood of 25 patients with UC, 5 patients with Crohn's disease (CD) and 15 control subjects was examined for Bregs subsets by flow cytometry. Intestinal tissue of 5 patients with UC, 3 patients with CD and 5 control subjects was also examined for Bregs. The levels of serum interleukin (IL)-10, immunoglobulin (Ig), and C-reactive protein (CRP), and the erythrocyte sedimentation rate (ESR) in individual subjects were measured. Interleukin-10 production in B cells isolated from patients with UC was examined. Potential associations between the values of the different measures were analysed by the Spearman correlation test.

RESULTS

Compared with controls, the UC patients had significantly reduced frequencies of CD24(high)CD38(high) and CD5(+) Bregs in peripheral blood as well as in intestinal tissues, accompanied by lower serum IL-10 levels. Interleukin-10 production was significantly decreased in stimulated B cells from patients with UC, whereas patient IL-10(+) B cells were found to be enriched in CD24(high)CD38(high) and CD5(+) B cells. However, increased percentages of CD95(+)-exhausted Bregs were encountered in subsets. Furthermore, Mayo clinic scores, CRP, and ESR in UC patients was negatively correlated with the frequency of Bregs and the IL-10 concentration, whereas these parameters were positively correlated with the frequency of CD95(+)-exhausted Bregs and the IgG levels.

CONCLUSIONS

Active UC is characterized by exhaustion of regulatory control in the B cell compartment.