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Increased expression of interleukin 17 in inflammatory bowel disease


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.

  • inflammatory bowel disease
  • cytokines
  • T cell
  • monocytes/macrophages
  • interleukin 17
  • IBD, inflammatory bowel disease
  • UC, ulcerative colitis
  • CD Crohn’s disease
  • IL, interleukin
  • TNF, tumour necrosis factor
  • FITC, fluorescein isothiocyanate
  • ELISA, enzyme linked immunosorbent assay
  • RT-PCR, reverse transcription-polymerase chain reaction
  • AGPC, acid guanidium thiocyanate-phenol-chloroform
  • PBS, phosphate buffered saline

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