Irritable bowel syndrome immune hypothesis. Part two: the role of cytokines.

OBJECTIVE To review the available evidence on the role of interleukins in the etiopathogenesis of Irritable Bowel Syndrome. METHODS Bibliographic retrieval on PubMed including the MeSH terms "Irritable Bowel Syndrome, "Immune System", "Cytokines" and "Interleukins". RESULTS Sixteen case-control studies and one randomised controlled trial were retrieved. The blood appears to have a high concentration of pro-inflammatory cytokines (TNF- á , IL-1 â , IL-6, IL-8) and lower concentration of IL-10, an anti-inflammatory cytokine, even though the findings are disparate and heterogeneous. As many as 33 genes were found, each with different expressions, and a diminished expression of cytokines in the colon mucosa of patients with IBS, which have not been previously described in any other pathology. CONCLUSIONS In patients with IBS, a clear profile of cytokine levels in the blood does not appear to exist, although an imbalance between them can be observed. Moreover, there are indications that give reason to believe that the different subsets of patients with IBS could present cytokine profiles in different blood. On the other hand, in the intestine, high cytokine secretion levels are not detected, contrary to what would be expected. Further studies are required to substantiate these findings.