Characterization of cytokine expression in the rectal mucosa of ulcerative colitis: correlation with disease activity

Mucosal inflammation in ulcerative colitis (UC) is presumed to be regulated by Th2-like cytokines. The aim of this study was to characterize local expression of various cytokines mRNA.

Total RNA was extracted from rectal biopsy specimens in 61 patients with UC, 18 inflammatory controls, and 16 noninflammatory controls. Reverse-transcription polymerase chain reaction (RT-PCR) was used to determine mRNA expression of interleukin (IL)-2, interferon (IFN)-gamma, IL-4, IL-10, IL-13, and IL-15.

Expression of IL-10 was more frequent in UC (75.4%) than in noninflammatory controls (37.5%, p < 0.01). IL-4 was more frequently positive in UC (41%) than in inflammatory controls (5.6%, p < 0.01) and in noninflammatory controls (6.3%, p < 0.01). Positive expressions of IL-4 (66.7% vs 20.6%, p < 0.01) and IL-13 (63.0% vs 29.4%, p < 0.01) were higher in active UC than in inactive UC. The positive rate of IL-2, interferon (IFN)-gamma, and IL-15 expression showed no difference among the groups divided by clinical, endoscopic, and histological grade of inflammation.

These findings suggest that in active UC, IL-4 is pivotal, in combination with other Th2-like cytokines. In contrast, Th1-like cytokines and IL-15 bear no definite relation to local inflammation of UC.