Commentary: the effects of probiotics on barrier function and mucosal pouch microbiota during maintenance treatment for severe pouchitis in patients with ulcerative colitis

Abstract

Epithelial barrier function is likely to be critical in the initiation and persistence of intestinal inflammation. Impaired barrier function is present in Crohn’s, ulcerative colitis (UC) and pouchitis during active disease and remission. Strategies targeting restitution of barrier function are required for the treatment of inflammatory bowel diseases (IBD). Persborn et al. report the effects of the probiotic mixture Ecologic 825 on barrier function during maintenance treatment of pouchitis. Evidence for probiotics in the treatment, prevention and maintenance of remission of pouchitis is established. However, their mechanisms of action are as yet unknown. Probiotics increase bacterial diversity and alter innate and adaptive immune responses. In vitro and in animal models probiotics alter epithelial barrier function and the expression and distribution of epithelial tight junctions. In the study by Persborn et al., UC patients with pouchitis entering remission following 4 weeks of combination antibiotic therapy were treated with Ecologic 825 for 8 weeks. They demonstrated that probiotics may restore mucosal barrier function and that bacterial diversity correlates with barrier function. However, the probiotic supplement did not influence the composition of the mucosal pouch microbiota and, in the absence of a control or placebo group, these findings may represent consequences of mucosal healing following induction of remission with antibiotics. Larger studies are needed to assess whether, and by what mechanisms, probiotics affect epithelial barrier function in the maintenance of pouchitis and other types of IBD and whether this mechanism of action is linked to prevention of relapse. However, this study raises important issues regarding the use of probiotics in the treatment of IBD. It is essential to consider whether the probiotic is intended to affect a particular immunotherapeutic target, or to alter the mucosal or the luminal composition of the microbiota. It is also important to consider the phase of disease in which probiotic therapy may be most efficacious, perhaps depending on the intended therapeutic target.