Abstract
Anecdotal reports suggest that smoking may be beneficial for patients with inflammatory
bowel disease (IBD) as nicotine may act through inflammatory mediators within the
colonic mucosa. Furthermore, there is increasing evidence that cytokines play a
pathologic role in IBD. Our aim was to determine the effects of cigarette smoking on
cytokine levels in the colonic mucosa of patients with and without IBD. Mucosal
biopsies were obtained from 10 patients with Crohn's disease (CD), 10 with ulcerative
colitis (UC), and 10 healthy controls. Five of 10 patients in each of the three groups
were smokers and five were nonsmokers. Concentrations of interleukin (IL)-1beta,
IL-2, IL-6, and IL-8 were determined using enzyme-linked immunosorbent assay (ELISA).
Cytokine levels of smokers were compared with nonsmokers in each group and with
controls. Results were analyzed using the Mann-Whitney test; significance was set
at p<0.05. The concentration of IL-8 was significantly higher in healthy controls
who smoke compared with nonsmokers and significantly reduced in smokers with CD
compared with nonsmokers with CD. Moreover, concentrations of IL-1beta and IL-8 were
significantly reduced in smokers with UC compared with nonsmokers with UC. Smokers
had significantly elevated levels of IL-8 in the colonic mucosa. Smokers with IBD had
a significant reduction in cytokine levels; specifically, IL-1beta and IL-8 for
patients with UC and IL-8 for patients with CD. Further studies are warranted to
determine if this reduction in cytokine levels is histologically and clinically significant.