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Keywords:

  • Epstein-Barr virus-induced gene 3;
  • Interleukin-12;
  • Ulcerative colitis;
  • Crohn's disease;
  • Real-time polymerase chain reaction;
  • 5-aminosalicylate

Abstract

Background

It has recently been suggested that Crohn's Disease (CD) is associated with an exaggerated T helper 1 cytokine response as manifest by increased production of interleukin-12 (IL-12) and interferon-γ (IFN-γ). Epstein-Barr virus-induced gene 3 (EBI3) encodes a 34-kDa glycoprotein that is 27% identical to the p40 unit of IL-12 and has recently been reported to be up-regulated in ulcerative colitis (UC). Aim To determine whether mucosal expression of IL-12 p40 or EBI3 correlates with inflammatory bowel disease (IBD). Patients/Methods mRNA expression in colonic mucosa from patients with UC, Crohn's disease (CD) and non-IBD controls was measured by reverse-transcribed real-time polymerase chain reaction (PCR).

Results

EBI3 was significantly increased in both involved and uninvolved colonic mucosa in patients with UC. Although IL-12 p40 was increased in some patients with CD relative to non-IBD controls, the increase was not statistically significant. However, 5-aminosalicylic acid (5-ASA) use was significantly correlated with reduced IL-12 p40 levels in the patients with CD, but not in UC cases. A similar reduction was not seen in 5-ASA-treated UC patients.

Conclusion

IL-12 p40 expression in CD is heterogeneous. In contrast, expression of the IL-12 p40 homologue, EBI3, is up-regulated in nearly all UC cases and in a subset of CD.