Cytokines in Crohnʹs colitis

Background Increasing evidence points to a pathologic role for cytokines in Crohnʹs colitis. Levels of cytokines are increased in diseased segments of colon in Crohnʹs colitis, but no one has studied the concentration of cytokines in clinically and histologically nondiseased segments. Methods Mucosal biopsies were obtained from 7 patients with active segmental Crohnʹs colitis and from 7 controls without inflammatory bowel disease. The concentration of Interleukin (IL)-lβ, IL-2, IL-6, and IL-8 in patients and controls were determined using enzyme linked immunosorbent assay and compared. Histologic sections were also performed to confirm diseased and nondiseased segments of colon. Results The concentrations of IL-1β, IL-6, and IL-8 were significantly higher in the involved segments of colon (10.3 ± 4.1, 3.7 ±1.0, 34.4 ± 6.9 picograms [pg] per mg) when compared to controls (1.8 ± 0.5, 1.1 ± 0.5, 5.3 ±1.0 pg/mg). The concentrations of IL-1β, IL-2, and IL-8 (8.5 ± 2.9, 5.3 ± 1.2, 26.3 ± 8.8 pg/mg) in normal appearing segments of colon of patients with Crohnʹs colitis were also significantly higher than in controls, whose IL-2 level was 2.0 ± 0.5 pg/mg. IL-lβ and IL-8 were significantly more concentrated in both the involved and uninvolved colonic segments of patients with Crohnʹs colitis compared to controls. IL-2 and IL-6 were also more concentrated in Crohnʹs patients than in controls, but not significantly. The differences in interleukin concentrations between involved and uninvolved segments of colon in patients with segmental Crohnʹs colitis were not significant. Conclusions Although Crohnʹs colitis is often a segmental disease, concentrations of IL-lβ and IL-8 are increased throughout the entire colon. These observations reinforce the hypothesis that Crohnʹs colitis involves the whole colon even when this is not apparent clinically or histologie ally.