Lamina propria and circulating interleukin-8 in newly and previously diagnosed pediatric inflammatory bowel disease patients

Abstract

Dysregulation of interleukin-8 (IL-8) production has been proposed to contribute to intestinal inflammation in inflammatory bowel disease (IBD) patients. Previous studies, which evaluate adult patients with long-standing or steroid-modulated disease, have reported conflicting results regarding the role of IL-8 in IBD pathogenesis. The present study evaluates IL-8 in colonic organ cultures and sera of newly and previously diagnosed pediatric IBD patients with various degrees of histopathologic activity. Colon and terminal ileum biopsies were obtained from 26 patients with Crohn's disease, 12 with ulcerative colitis, 4 with indeterminate colitis, and 12 age-matched normal controls. IBD patients were additionally characterized as newly or previously diagnosed. Supernatants from organ-cultured lamina propria biopsies and sera were evaluated by ELISA for IL-8 protein. IL-8 increased with degree of histologic inflammation regardless of diagnosis (no pathologic diagnosis, 62.6 ng/ml, interquartile range [IQR] 30.4-94.6 ng/ml; mild, 92.0 ng/ml, IQR 21.9-170.0 ng/ml; moderate, 676.2 ng/ml, IQR 46.4-2967.7 ng/ml; severe, 585.6 ng/ml, IQR 149.7-1602.2 ng/ml; P < 0.01). Lamina propria IL-8 was significantly elevated in moderately and severely inflamed tissue segments (603.26 ng/ml; IQR, 72.15-2240.4 ng/ml) compared to noninflamed and mildly inflamed segments (67.70 ng/ml; IQR, 30.38-124.1 ng/ml; P = 0.0009). There was no significant trend in IL-8 concentration when compared by clinical diagnosis. No significant difference was found in IL-8 concentrations in organ cultures from newly diagnosed patients versus those from previously diagnosed patients. There was no significant correlation between serum IL-8 concentration and organ culture IL-8 concentration. We conclude that higher concentrations of IL-8 are found in more histologically inflamed tissue segments from pediatric IBD patients. IL-8 does not appear to be associated with clinical IBD subtype. IL-8 appears to be an integral part of both early and established mucosal inflammation in pediatric IBD patients. These findings suggest that IL-8-specific therapies may universally modify inflammatory activity in IBD patients.