[Probiotics and inflammatory bowel disease] (original) (raw)

2002, Gastroenterologia y hepatologia

The aetiology of inflammatory bowel disease (IBD) remains obscure, currently thought to be associated with a genetic predisposition, dysregulation of the mucosal immune system, and a loss of antigen tolerance to enteric microflora, further influenced by a range of other environmental factors. In many cases, disease activity can be unremitting and refractory to treatment, with an unpredictable response to conventional therapy. To this end, new treatment strategies are being pursued on the basis of our understanding of IBD pathogenesis, and there is increasing evidence that at least some components of the enteric flora are primary contributors. Restoring the balance of the colonic microbiota to a less-pathogenic state is therefore a desirable strategy. Probiotics are currently defined as live non-pathogenic microorganisms that, when ingested, exert a positive influence on host health beyond basic nutrition. On this basis, probiotics hold the potential to restore normal intestinal homeostasis. Despite more than a century of anecdotal reports of probiotic efficacy in gastrointestinal disease, only relatively recently have well-controlled, scientific studies and clinical trials, been conducted. Whilst reliable in vitro predictors of potential in vivo efficacy of putative probiotics await development, well-characterised animal model systems are proving valuable for the methodical, pre-clinical development of probiotics. Although early probiotic applications focussed largely on lactic acid bacteria (lactobacilli) and bifidobacteria, the range of candidate probiotics has now expanded significantly. Successful clinical application of the probiotic formulation, VSL#3, for treatment of the pouchitis variant of IBD, has instilled new excitement into the applicability of probiotics to IBD treatment, and the potential importance of probiotic combinations. The availability of new recombinant methodologies to develop 'designer' probiotics, capable of synthesizing and secreting specific factors, ranging from vitamins through to antibodies, further broadens the scope for probiotic application in IBD. Indeed, there are encouraging reports that probiotics may not need to be viable, or even intact, to exert their beneficial effects, with reports of therapeutic benefit from bacterial components such as DNA. In addition to the development of rigorous predictive systems to ascertain probiotic efficacy, challenges for the future will include determining the 3 optimal probiotic, or probiotic combination, and its timing of administration during phases of IBD relapse and remission. At present, our understanding of the intestinal microflora, and the importance of its composition and variability between individuals, is limited. However, once this understanding has been attained, strategically-designed probiotic formulations could ultimately be 'tailored' to suit individual IBD patients.