Chronic inflammatory bowel diseases
Although Clostridium difficile colitis is the only approved indication for the use of fecal microbiota transplant (FMT), all diseases for which the gut microbiota is believed to play a role have drawn the interest of scientists. Here is an overview of the current state of research on FMT, from gastrointestinal diseases to cancer, all the way to neurological disorders.
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Chronic inflammatory bowel diseases (CIBD)
are characterized by the inflammation of the gastrointestinal wall. In Crohn’s disease (CD), the damage can reach the entire gastrointestinal system, from mouth to anus, but it is usually more localized to the terminal part of the small intestine and the colon. In ulcerative colitis (UC) it is limited to the colon and rectum12.
CIBDs progress as inflammatory flareups of variable duration and frequency depending on the patient, alternating with periods of remission. They cause acute abdominal pain, severe diarrhea (between 5 and 10 bowel movements per day), associated with blood and pus in ulcerative colitis (UC); and in severe forms, other symptoms and complications can occur such as fever, tachycardia, nausea and vomiting, weight loss and dehydration. CIBDs also trigger extra-intestinal symptoms, especially articular pain, skin and mucosa lesions (skin ulcerations, mouth ulcers, glossitis, i.e. tongue inflammation...) as well as hepatic and ocular disorders13.
The gut microbiota analysis of patients with UC revealed they had a decreased diversity of microbial species14, especially a lower content of Firmicutes and Bacteroidetes. But it is mainly the low content of Faecalibacterium prausnitzii and the excessive content of Proteobacteria and Actinobacteria that are associated with these CIBDs. This imbalance causes a decrease in the production of short-chain fatty acids, beneficial substances which are food to colon cells and play an important role in the regulation of the immune system. That is why fecal microbiota transplant (FMT) has been considered to treat this disorder.
Moderate benefits in UC
Three of the four published clinical trials on UC concluded that this approach was beneficial. Overall, the beneficial effects were much more moderate than they were in the treatment of C. difficile colitis and depend on the donor–which is why donor selection is so important. And several results raise new questions: are only some microorganisms efficient? And if so, which ones? Should the patient receive an enema or an antibiotic therapy beforehand? Which administration route is preferable? Does the restoration of the gut microbiota work long-term or must transplants need to be repeated? These questions need to be answered before fecal microbiota transplant can be seriously considered as an alternative for the treatment of ulcerative colitis.
12 Pierre Desreumaux (Unité Inserm 995). Maladie inflammatoires chroniques de l’intestin. Inserm. 2016
13 Maladies inflammatoires chroniques de l’Intestin (MICI). Inserm. Fév. 2016