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IBD

Inflammatory bowel diseases (IBDs) include Crohn’s disease and ulcerative colitis. These diseases don’t have an effect on life expectancy, but they do significantly alter quality of life. Treatment plans are starting to target microbiota.

IBDs, Crohn’s disease and ulcerative colitis (UC), are characterized by inflammation in the wall of part of the digestive tract, which is related to hyperactivity of the digestive immune system. During IBD flares, the most common symptoms are abdominal pain and diarrhea, which can sometimes be hemorrhagic. These diseases can also present signs in systems outside the digestive tract, including joints and the ophthalmic, cutaneous, and hepatic systems. 

IBDs affect 1 person in every 1000 in Western Europe and most often appear between 20 and 40 years of age. These illnesses follow intermittent courses, with alternating periods of flares and remission. In Crohn’s disease, this inflammation can be localized at all stages of the digestive system, from the mouth to the anus, although it is most often found in the intestine. Ulcerative colitis is localized in the rectum and colon.

Multifactorial disorders

The causes of IBDs include genetic predisposition, environmental factors like pollution and diet, the immune system, and intestinal microbiota. IBDs may also be caused by a lack of exposure to microorganisms during childhood due to an excessive hygiene, for example.

Modified intestinal content

Intestinal microbiota seems to play an important yet still poorly understood role in the characteristic inflammation of IBDs. Numerous studies have observed dysbiosis in these patients, i.e. a change in the microbiota equilibrium, linked to genetic and environmental factors. Anti-inflammatory bacteria in particular are weakened. This imbalance changes the content of the intestine and can lead to chronic inflammation.

Hope for treatment

There is no curative therapy, but anti-inflammatories can limit painful flares. Treatment currently includes corticosteroid therapy, treatments called “immunomodulators” that can reduce the immune system’s reactions, like anti-TNFα, and surgery in 80% of Crohn’s cases and 20% of UC. It rarely provides a definitive cure. Researchers are currently trying to target the role of microbiota in IBDs, trying to reduce the presence of pathogens and boost the growth of good microorganisms. 

 

Sources:

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Hugot JP et al. Association of NOD2 leucine-rich repeat variants with susceptibility to Crohn’s disease. Nature 2001; 411: 599-603.

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Gent AE et al. Inflammatory bowel disease and domestic hygiene in infancy. Lancet 1994; 343: 766-7.

Manichanh C et al. Reduced diversity of faecal microbiota in Crohn’s disease revealed by a metagenomic approach. Gut 2006; 55: 205-11.

Frank DN et al. Molecular-phylogenetic characterization of microbial community imbalances in human inflammatory bowel diseases. PNAS USA 2007; 104 : 13780-5.

Dossier Inserm MICI http://www.inserm.fr/thematiques/physiopathologie-metabolisme-nutrition/dossiers-d-information/maladies-inflammatoires-chroniques-de-l-intestin-mici

Bejaoui M et al. Targeting the microbiome in inflammatory bowel disease: critical evaluation of current concepts and moving to new horizons. Dig Dis 2015 ; 33 : 105-12.