Serum IL-6, IL-23 profile and Treg/Th17 peripheral cell populations in pediatric patients with inflammatory bowel disease.

IL-6 and IL-23 are both pleiotropic cytokines involved in the regulation of the immune response, inflammation, and hematopoeisis. They also could mediate effector cells and tolerance mediated by cells with regulatory function. Inflammatory bowel disease (IBD) is associated with a reduced ratio of Treg cells ato Th17 effector cells in peripheral blood and is characterised by a pro-inflammatory cytokine microenvironment which supports the continued generation of Th17 cells. It is well described in adults but little is known in a pediatric population. This study was aimed to investigate the role of IL-6, IL-23 and its association with Treg and Th17 subsets in pediatric IBD patients. Peripheral blood mononuclear cells from patients and controls were stimulated with PMA, ionomycin, and brefeldin A. The frequencies of CD4(+)Foxp3(+) cells, and CD4(+)IL17a(+) cells were analyzed by flow cytometry. The serum level of IL-6 and IL-23 was determined by Elise kit. The mRNA expression of Foxp3, IL-17a, IL-6 and IL-23 was detected by real-time quantitative PCR. The ratio of Treg/Th17 decreased in pediatric IBD patients, and it strongly correlated with IL-6 and IL-23. The present study provides a quantitative analysis regarding the Th17/Treg cell balance in peripheral blood of children with IBD and its association with serum IL-6 and IL-23 level.