Redox imbalance in Crohn's disease intestinal smooth muscle cells causes NF-kappa B-mediated spontaneous interleukin-8 secretion

Interleukin-8 (IL-8), a chemokine secreted by cells at injury sites, has re cently been recognized as involved in the pathogenesis of Crohn's disease. However, the pathogenesis of enhanced spontaneous transcription of IL-8 by the bowel in patients with Crohn's disease is undefined. Although IL-8 is s ecreted primarily by neutrophils, macrophages, and endothelial and epitheli al cells, we observed the involvement of mesenchymal cells in the inflammat ory process. A smooth muscle cell line isolated from the ileum of a patient with Crohn's disease (CDISM) and maintained in culture exhibited spontaneo us transcription and secretion of IL-8 when compared with intestinal smooth muscle cells obtained from a normal subject (NHISM), Furthermore, IL-8 tra nscription from CDISM cells was associated with remarkable spontaneous acti vation of the oxidant-sensitive transcription factor NF-kappaB, as assessed by transient transfection assays with an IL-8 promoter reporter construct, Western blot analysis, and electrophoretic mobility shift assays (EMSA), F inally, we report here that CDISM cells exhibit significantly altered redox balance. The antioxidant pyrrolidine dithiocarbamate (PDTC) restored the r edox equilibrium by mechanisms that inhibit binding of NF-kappaB to its cog nate site on the IL-8 promoter. These findings suggest that restoration of the redox balance could hold promise for therapeutic intervention in Crohn' s disease.