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

Abstract

OBJECTIVES: Interleukin-8 (IL-8) as an α-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-α) is a new chemokine that is chemotactic to neutrophils. The aims of this study were to assess the relative expression of SDF1-α and IL-8 mRNA in different colonic regions and patients with inflammatory bowel disease with varied degrees of inflammation in the colon. METHODS: 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-α 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. RESULTS: IL-8 mRNA expression was significantly correlated with SDF1-α 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-α) 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-α 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-α expression in UC patients. CONCLUSIONS: IL-8 but not SDF1-α 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-α.