Summary: Background  Intestinal microbiota manipulation, one of the pathogenetic components of inflammatory bowel disease (IBD), has become an attractive therapy for ulcerative colitis (UC).Aim  To assess in children with active distal UC the effectiveness of Lactobacillus (L) reuteri ATCC 55730 enema on inflammation and cytokine expression of rectal mucosa.Methods  A total of 40 patients (median age: 7.2 years range 6–18) with mild to moderate UC were enrolled in a prospective, randomised, placebo‐controlled study. They received an enema solution containing 10¹⁰ CFU of L. reuteri ATCC 55730 or placebo for 8 weeks, in addition to oral mesalazine. Clinical endoscopic and histological scores as well as rectal mucosal expression levels of IL‐10, IL‐1β, TNFα and IL‐8 were evaluated at the beginning and at the end of the trial.Results  Thirty‐one patients accomplished the trial (17 males, median age 13 year, range 7–18). Mayo score (including clinical and endoscopic features) decreased significantly in the L. reuteri group (3.2 ± 1.3 vs. 8.6 ± 0.8, P < 0.01) compared with placebo (7.1 ± 1.1 vs. 8.7 ± 0.7, NS); furthermore, histological score significantly decrease only in the L. reuteri group (0.6 ± 0.5 vs. 4.5 ± 0.6, P < 0.01) (placebo: 2.9 ± 0.8 vs. 4.6 ± 0.6, NS). At the post‐trial evaluation of cytokine mucosal expression levels, IL‐10 significantly increased (P < 0.01) whereas IL‐1β, TNFα and IL‐8 significantly decreased (P < 0.01) only in the L. reuteri group.Conclusions  In children with active distal ulcerative colitis, rectal infusion of L. reuteri is effective in improving mucosal inflammation and changing mucosal expression levels of some cytokines involved in the mechanisms of inflammatory bowel disease.

The American Journal of Gastroenterology is published by Nature Publishing Group (NPG) on behalf of the American College of Gastroenterology (ACG). Ranked the #1 clinical journal covering gastroenterology and hepatology*, The American Journal of Gastroenterology (AJG) provides practical and professional support for clinicians dealing with the gastroenterological disorders seen most often in patients. Published with practicing clinicians in mind, the journal aims to be easily accessible, organizing its content by topic, both online and in print. www.amjgastro.com, *2007 Journal Citation Report (Thomson Reuters, 2008)