• colitis
• probiotics
• inflammatory bowel disease
• dendritic cells

There is considerable public, media, and scientific interest in “natural” products, including probiotics, in modulating intestinal inflammation and health.¹ Intestinal microflora are intimately involved in the generation of immunocompetent cells and tuning the balance between T helper 1 (Th₁) and Th₂ immunity during the development of the gut associated immune system. It is now generally accepted that the intestinal bacterial flora contributes significantly to the pathogenesis of inflammatory bowel disease (IBD) along with mucosal immune dysregulation and genetic susceptibility. Considerable research is focused on modifying the intestinal flora with probiotic bacteria to attenuate inflammatory activity and prevent relapses in ulcerative colitis, Crohn’s disease, and pouchitis. Although both Lactobacillus species and Bifidobacterium species are frequently used, the optimum use of probiotics in IBD requires greater understanding of their effects on the immune system.

A rationale for the use of probiotics in IBD stems from reports of dysbiosis in the intestinal flora in ulcerative colitis, Crohn’s disease, and pouchitis, either by conventional anaerobic culture or by analysis using molecular probes. It is however unclear whether such alterations in intestinal flora drives the inflammation or is a consequence of it. The practical application of probiotic strategy has been especially encouraged by the positive results of a trial in its use for the prevention and treatment of pouchitis.^2,3 The multispecies probiotics used pose special challenges in identifying precise mechanism of action, although alterations in faecal flora have been demonstrated.⁴ Despite some positive trials, generalisation from pouchitis to their use for all forms of IBD appears somewhat premature, however, as for example, a trial of administration of Lactobacillus GG after surgical resection for Crohn’s disease proved ineffective in preventing relapse.⁵ Further studies are therefore …