抄録
During the last one-half century we have witnessed a continuous evolution of the concept of microbial factors in the pathogenesis of IBD, an evolution that has never relinquished the involvement of such factors in gut inflammation, but has generated rather different views and variable degrees of enthusiasm for the importance of microbes in IBD. The failure to isolate classical or atypical microorganisms in CD or UC tissues made IBD investigators to look for answers in the field of immunology, looking for evidence of specific immune reactivity markers against bacterial antigens. The answers obtained were not satisfactory, and the search moved on to mycobacteria and viral agents with similar results. At the time that our understanding of mucosal immunity has already lead to the creation of the concept of “physiological” and pathological mucosal inflammation, genetic manipulations started to generate animals whose unexpected outcome was the development of colitis which is strictly dependent on the presence of an enteric flora. This fundamental observation was followed by the demonstration that in IBD there is a loss of immunological tolerance against the normal enteric flora and clinical trials showing that antibiotics and probiotics may be therapeutically beneficial in IBD patients, all of which ended up with the creation of the present view that the normal enteric flora is an essential component of IBD pathogenesis. This view still requires solidification through the definition of the relevant cellular and molecular pathways, and at the same time clinical studies must go on and explore how best modulate the gut flora and interfere with its proinflammatory potential in genetically susceptible individuals.
