IBD is a group of conditions in which the colon and/or the small intestine becomes inflamed. Crohn's disease and ulcerative diseases are the two main types of Inflammatory Bowel Disease. In Crohn's disease both small and large intestine are affected, and in some rare cases even the mouth, oesophagus and the stomach. In ulcerative colitis only the large intestine and the rectum are affected.
IBD is a chronic disease with two different states, a high active state of the disease called active inflammation and an inactive state called remission. In the active state the inflammation is accompanied by unpaired barrier function, so the defense mechanism is not properly working.
Are there any ways for our body to keep the intestinal barrier function as good as possible? First, a layer of epithelial cells connected by tight junctions, covered with a mucus layer to protect the mucosal surface from harmful bacteria and molecules. Second, on top of this layer, we got the gut microbiota that is covering the mucus layer with the good, inoffensive microbes.
IBD is emerging as a worldwide epidemic, especially in the high income countries, making researchers to think that all these diseases are mainly caused by the environment. The lifestyle in developed countries might impair the microbial colonization. There are multiple factors involver: birth at hospital, with or without caesarean delivery, decreased family sizes, decreased contact with soil organisms, increased antibiotic use, body washing with antibacterial soap and shower gel, increased use of processed foods. The gut microbiota plays a big role in priming and regulating the immune system. In IBD the microbiota changes in composition, being an essential factor driving the inflammation. Markers of IBD can be found in the microbiota, such as reduction of microbial diversity and increase in gammaproteobacteria (this group holds many potential pathogens).
Gammaproteobacteria
Adherent-invasive microbes like E.Coli and Fusiobacterium can be found, combined with a decrease of beneficial ones (Bifidobacterium, Lactobacillus and F. prausnitzii). All these signs can be used to diagnose the disease. These changes can affect the microbiota as a whole, decreasing the short chain fatty acids like Butyrate, increasing the oxidative stress, causing imbalance between reactive oxygen species and antioxidant defences, causing tissue damage.
Attempts to restore microbiota composition using microbiota based therapies showed positive and promising results, causing remission in IBD, but each patient response is different, and faecal microbiota transplant methods are not superior to the current therapies. But microbiota based therapies can be used in the future to treat and diagnose IBD.
Next post will be the last post of the microbiota series, and it iwll be about the medical therapy.
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