Smoking Exacerbates Extraintestinal Manifestations in Crohn's Disease and Alters Immune Response in IBD


Smoking may be especially harmful to patients with irritable bowel disease.

Smoking may be especially harmful to patients with irritable bowel disease.

Smoking is known to have many harmful effects on diverse body systems. In a novel finding, on September 14, 2014, Ott et al published a paper in the World Journal of Gastroenterology identifying a relationship between smoking and poorer outcomes with regard to extraintestinal manifestations of Crohn's disease.1

Of 257 patients with newly diagnosed irritable bowel disease (IBD), including 161 patients with Crohn's disease and 96 patients with ulcerative colitis, the median follow-up duration was 50 months. A total of 63.4% of patients involved in the study had extraintestinal manifestations of Crohn's disease. Of these patients with extraintestinal manifestations, those with Crohn's disease accounted for the largest proportion of patients.1

Current smokers with Crohn's disease were 96% more likely to have an extraintestinal manifestation of disease compared with nonsmoking patients (P = .046).1

Previous research identified changes in blood mononuclear cells among smokers with Crohn's disease and ulcerative colitis. Researchers Bergeron et al exposed blood mononuclear cells from patients with a flare of IBD and measured in vitro response of these cells to a cigarette smoke extract.2

The extract, applied to cells of patients who were smokers and had Crohn’s disease, induced lower levels of cytokine and chemokine secretion than the same extracts applied to the cells of nonsmokers, and smokers with ulcerative colitis. These data suggest that the oxidative stress induced by cigarette smoke exposure changes the immune system activity of smokers with Crohn’s disease.2

According to researchers, smoking reduces cell response to anti-inflammatory or antioxidant effects of medications used to treat IBD. This change may be mediated by a specific effect of smoking: a reduction in levels of a cytoprotective enzyme known as Hsp70.2

Current guidelines from the World Gastroenterology Organization recommend smoking cessation for reducing disease activity in patients with Crohn’s disease and as a general health preventive measure for patients with ulcerative colitis.3

Not only does smoking induce immune changes in patients with IBD, but smoking appears to increase the risk of extraintestinal harm in patients with Crohn’s disease.1,2


  • Ott C, Takses A, Obermeier F, Schnoy E, Müller M. Smoking increases the risk of extraintestinal manifestations in Crohn's disease. World J Gastroenterol. 2014;20(34):12269-12276.
  • Bergeron V, Grondin V, Rajca S, et al. Current smoking differentially affects blood mononuclear cells from patients with Crohn's disease and ulcerative colitis: relevance to its adverse role in the disease.Inflamm Bowel Dis. 2012;18(6):1101-1111.
  • Bernstein CN, Fried M, Krabshuis JH, et al. World Gastroenterology Organization Practice Guidelines for the diagnosis and management of IBD in 2010. Inflamm Bowel Dis. 2010;16(1):112-124.

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