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Cytokines May Provide Marker for Irritable Bowel SyndromeCytokines May Provide Marker for Irritable Bowel Syndrome NEW YORK (Reuters Health) Mar 03 - Patients with irritable bowel syndrome (IBS) have an overactivation of the hypothalamic-pituitary-adrenal axis and an increase of proinflammatory cytokines, according to researchers."Irritable bowel syndrome is a functional disorder with an etiology that has been linked to both psychological stress and infection," Dr. Timothy G. Dinan, of University College Cork, Ireland, and colleagues write in the February issue of Gastroenterology.The researchers hypothesized that IBS is "an inflammatory disorder sustained by the hypothalamic-pituitary-adrenal axis." Of 151 subjects included in their study, 76 had IBS and 75 served as controls.Cytokine levels were measured in 49 patients and 48 controls. A subset of 21 patients and 21 controls also underwent a corticotropin-releasing hormone stimulation test and measurement of adrenocorticotropic hormone and cortisol levels. A dexamethasone challenge was performed in the remaining 27 patients and 27 controls.All IBS subgroups (diarrhea predominant, constipated, and alternators) had elevated levels of cortisol (p < 0.05) and the proinflammatory cytokines interleukin (IL)-6 and IL-8 (p < 0.001). The most marked elevation was observed in the constipated subgroup. No significant alterations in IL-10 were found.IBS patients experienced an exaggerated release of both adrenocorticotropic hormone and cortisol after corticotropin-releasing hormone infusion. The adrenocorticotropic hormone response (delta-ACTH) significantly (p < 0.05) correlated with the IL-6 levels. Patients and controls exhibited a similar suppression of cortisol after a dexamethasone challenge."The elevation in proinflammatory cytokines may be centrally driven, as in the case of other biopsychosocial disorders," Dr. Dinan and colleagues note. They conclude that "the cytokine alterations described are worthy of exploration as a potential biomarker, and future studies should focus on the factors that drive the elevation."Gastroenterology 2006;130:304-311.