This is an extract of our Crohn's Disease document, which we sell as part of our Gastrointestinal (GI) System Notes collection written by the top tier of Bristol University students.
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Lecture 24 Crohn's Disease
What is Crohn's disease?
o Chronic inflammatory disease, effects anywhere from mouth-anus (UC is only colon) o Characterised by patchy inflammation with ulceration (unlike UC, which is confluent) o Symptoms determined by site of disease and severity of inflammation & the complications of inflammation Symptoms o Pain: Constant or in waves (inflammatory stricture of bowel) o Diarrhoea: Loose/severe, may be bloody o Weight loss: Due to disease, poor absorption & loss of appetite o Fatigue: Partly anaemia, but hard to treat Who gets it?
o Getting more common o Bimodal=young adults & middle aged o 1 in 500 o Can run in families; Developed nations o More common in smokers (opposite of UC) Site of disease o Enterocolitis (small & large bowel) 50%
o Enteritis (small bowel) 29%
o Colitis (large bowel) 19%
o Other sites (e.g. cutaneous) 2%
What causes Crohn's disease?
o BACTERIA (abnormal)
? Bacterial flora change (is it because of CD or does it cause CD?)
? In general, reduced diversity of Firmicutes & Bacterioides
? Increased mucosa-associated E. coli in Crohn's disease
* Adherent Invasive E. Coli (AIEC)- able to penetrate gut wall, difficult to kill once there and sit in macs causing inflammation
* Loss of some Firmicutes & Bacterioides
* Role of (AIEC)
* BUT- Crohn's disease not transmittable, & what about familial risk?
o Mucus (defective)
? Too much mucin (opposite of UC)
? Mutation of MUC 19 gene in CD o Bowel wall (leaky)
? Abnormal permeability
* In CD patients and relatives
* Tight junction defects
* May be secondary to inflammation BUT o MYO9B gene mutation associated with UC o Gene in CD disputed
? Abnormal defence
* Defective mucus layer and epithelial barrier MAY permit invasion of gut wall by bacteria
Recognition (abnormal); Inflammation (dysregulated); Enhanced recruitment of inflammatory cells
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