Interleukin-8 and SDF1-alpha mRNA expression in colonic biopsies from patients with inflammatory bowel disease

Interleukin-8 (IL-8) as an alpha-chemokine recruits and activates neutrophils, which are abundant in the intestinal lesions of ulcerative colitis (UC) and Crohn's disease (CD). Stromal cell-derived factor 1 (SDF1-alpha) is a new chemokine that is chemotactic to neutrophils. The aims of this study were to assess the relative expression of SDF1-alpha and IL-8 mRNA in different colonic regions and patients with inflammatory bowel disease with varied degrees of inflammation in the colon.

Colon biopsy samples were obtained from 19 patients with UC, 12 with CD, and 5 with irritable bowel syndrome (IBS) who underwent colonoscopy. Levels of IL-8 and SDF1-alpha mRNA expression were measured semiquantitatively by reverse-transcription and polymerase chain reaction amplification. The cytokine mRNA levels were corrected for glyceraldelyde-3-phosphate dehydrogenase mRNA expression.

IL-8 mRNA expression was significantly correlated with SDF1-alpha expression in normal biopsies from IBS patients (r = 0.58, p < 0.01). There was no significant difference in cytokine mRNA expression (IL-8 or SDF1-alpha) across different regions of the colon or rectum in uninflamed normal biopsies. The IL-8 mRNA expression ratios in UC (mean +/- SD, 1.03 +/- 0.52) and CD (0.90 +/- 0.38) patients were significantly higher than in IBS (0.52 +/- 0.17) (p < 0.01, p < 0.05, respectively). The SDF1-alpha mRNA expression ratio in UC (0.30 +/- 0.52) was higher than in both CD (0.21 +/- 0.10) and IBS patients (0.22 +/- 0.11) (p < 0.01, <0.05, respectively). A statistically significant correlation was found between the IL-8 mRNA expression and the colonic inflammation in UC patients (r = 0.44, p < 0.05) but not for SDF1-alpha expression in UC patients.

IL-8 but not SDF1-alpha mRNA expression was associated with inflammation in UC. This suggests that IL-8 may play a more important role in inflammatory bowel disease than does SDF1-alpha.