title: Smoking in inflammatory bowel disease: impact on disease course and insights into the aetiology of its effect.
abstract: The chronic intestinal inflammation that characterises Crohn's disease and ulcerative colitis arises from a complex interplay between host genotype, the immune system, and the intestinal microbiota. In addition, environmental factors such as smoking impact on disease onset and progression. Individuals who smoke are more likely to develop Crohn's disease, and smoking is associated with recurrence after surgery and a poor response to medical therapy. Conversely, smoking appears protective against ulcerative colitis and smokers are less likely to require colectomy. The mechanism by which smoking exerts its impact on disease and the rational for the dichotomous effect in patients with Crohn's disease and ulcerative colitis is not clear. Recent evidence suggests that smoking induces alterations to both the innate and acquired immune system. In addition, smoking is associated with a distinct alteration in the intestinal microbiota both in patients with active Crohn's disease and healthy subjects.
authors.affiliation: Digestive Disease Clinical Academic Unit, Barts Health NHS Trust, London, United Kingdom. Electronic address: gareth.parkes@bartshealth.nhs.uk.
authors.forename: Gareth C
authors.initials: GC
authors.lastname: Parkes
authors.affiliation: King's College London, School of Medicine, Diabetes and Nutritional Sciences Division, London, United Kingdom. Electronic address: kevin.whelan@kcl.ac.uk.
authors.forename: Kevin
authors.initials: K
authors.lastname: Whelan
authors.affiliation: Digestive Disease Clinical Academic Unit, Barts Health NHS Trust, London, United Kingdom; Centre for Digestive Diseases, Blizard Institute of Cell and Molecular Science, Queen Mary University of London, London, United Kingdom. Electronic address: james.lindsay@bartshealth.nhs.uk.
authors.forename: James O
authors.initials: JO
authors.lastname: Lindsay
mesh_terms: D003093:Colitis, Ulcerative / Q000209:etiology; D003424:Crohn Disease / Q000209:etiology; D018450:Disease Progression; D005260:Female; D006801:Humans; D007109:Immunity / Q000187:drug effects; D015212:Inflammatory Bowel Diseases / Q000209:etiology*; D007422:Intestines / Q000187:drug effects / Q000382:microbiology; D008297:Male; D064307:Microbiota / Q000187:drug effects; D012723:Sex; D012907:Smoking / Q000009:adverse effects*; D014028:Tobacco Smoke Pollution / Q000009:adverse effects
chemical_list: D014028:Tobacco Smoke Pollution
keywords: Crohn's disease; Microbiota; Smoking; Ulcerative colitis