Gut 52:65-70 doi:10.1136/gut.52.1.65
  • Inflammatory bowel disease

Increased expression of interleukin 17 in inflammatory bowel disease

  1. S Fujino,
  2. A Andoh,
  3. S Bamba,
  4. A Ogawa,
  5. K Hata,
  6. Y Araki,
  7. T Bamba,
  8. Y Fujiyama
  1. Department of Internal Medicine, Shiga University of Medical Science, Seta-Tukinowa, Otsu 520-2192, Japan
  1. Correspondence to:
    Dr A Andoh, Department of Internal Medicine, Shiga University of Medical Science, Seta-Tukinowa, Otsu 520-2192, Japan;
  • Accepted 5 July 2002


Background and aim: Interleukin (IL) 17 is a cytokine which exerts strong proinflammatory activities. In this study we evaluated changes in IL-17 expression in the inflamed mucosa and in the serum of patients with inflammatory bowel disease (IBD).

Methods: Tissue samples were obtained endoscopically or surgically from patients with ulcerative colitis (UC) (n=20), Crohn’s disease (CD) (n=20), infectious colitis (n=5), ischaemic colitis (n=8), and normal colorectal tissues (n=15). IL-17 expression was evaluated by a standard immunohistochemical procedure. Serum IL-17 levels were determined by ELISA. IL-17 mRNA expression was analysed by reverse transcriptase-polymerase chain reaction.

Results: IL-17 expression was not detected in samples from normal colonic mucosa, infectious colitis, or ischaemic colitis. In the inflamed mucosa of active UC and CD patients, IL-17 expression was clearly detectable in CD3+ T cells or CD68+ monocytes/macrophages. The average number of IL-17+ cells was significantly increased in active UC and CD patients compared with inactive patients. IL-17 mRNA expression was not detected in normal mucosa but was detectable in the mucosa from active UC and CD patients. IL-17 was not detected in the sera from normal individuals, infectious colitis, or ischaemic colitis patients but IL-17 levels were significantly elevated in IBD patients.

Conclusions: IL-17 expression in the mucosa and serum was increased in IBD patients. It is likely that IL-17 expression in IBD may be associated with altered immune and inflammatory responses in the intestinal mucosa.