Abnormal immune regulation and low-grade inflammation in IBS: does one size fit all?

Evidences suggest that there is low-grade inflammation in the colonic mucosa and/or a state of immune activation in patients with irritable bowel syndrome (IBS). Results from available studies are inconsistent mainly because of differences in measures, methodologies and study populations. In this issue, Chang et al. evaluated a comprehensive set of cytokines, immune markers and immune-related cells in patients with non post infectious IBS (non PI-IBS) and controls. The main finding was a lower expression of the mRNA of the anti-inflammatory IL-10 cytokine in the colonic mucosa of women with non PI-IBS without any differences in the cell counts. These results suggest that in non PI-IBS, there is altered immune regulation/activation without evidence of low-grade mucosal inflammation. Further, PI and non PI-IBS may be associated with different alterations in immune function/activation.