Coordinate upregulation of interleukin-8 and growth-related gene product-alpha is present in the colonic mucosa of inflammatory bowel.

Background: Although ãlpha-chemokines, such as interleukin (IL)-8 and epithelial neutrophil-activating peptide 78, are implicated in the pathogenesis of inflammatory bowel disease (IBD), little information is currently available on the expression and cellular source of growth-related gene product-alpha (GROalpha) and its functional relationship to other ãlpha-chemokines in the intestinal mucosa of patients with IBD.
Methods: The contents of IL-8 and GROalpha in organ cultures, the expression of IL-8 and GROalpha mRNA, and the modulatory effects of inflammatory mediators on IL-8 and GROalpha-producing cells were examined using colonic mucosal tissues. In vitro stimulatory effects of IL-8 and GROalpha on neutrophils were investigated in terms of chemotactic migration and superoxide anion generation.
Results: The contents of IL-8 and GROalpha in organ cultures were elevated in patients with IBD, especially in those with active ulcerative colitis (UC). Both IL-8 and GROalpha contents increased according to an increase in histological disease activity in patients with UC, but not in those with Crohn disease. In contrast, no significant correlation was found between the contents of these alpha-chemokines and clinical disease activity. In situ hybridization detected increased expression of IL-8 and GROalpha mRNA in macrophages, pericrypt myofibroblasts, and the epithelium of tissue specimens with active lesions of IBD. The secretion of IL-8 and GROalpha from macrophages and myofibroblasts obtained from control patients was upregulated by inflammatory cytokines and bacterial products. The concentrations of recombinant (r)-IL-8, which covered the levels of activity detected in individual organ cultures or cell cultures of fractionated mucosal cells, could induce chemotactic migration and superoxide anion generation in neutrophils in vitro, and r-GROalpha had synergistic effects on r-IL-8-induced neutrophil activation.
Conclusions: A coordinate upregulation of IL-8 and GROalpha may be involved in the tissue injury in patients with IBD through their stimulatory effects on neutrophils.