Amelioration of murine dextran sulfate sodium-induced colitis by ex vivo extracellular superoxide dismutase gene transfer

Abstract

BACKGROUND: Although the etiology of inflammatory bowel disease has not been fully clarified, reactive oxygen species is speculated to be involved. Extracellular superoxide dismutase (EC-SOD), an isozyme of SODs, is known to function mainly in body fluids. We investigated the efficacy of an ex vivo EC-SOD gene transfer into dextran sulfate sodium (DSS)-induced colitis mice. MATERIALS AND METHODS: Experimental colitis was induced by providing Balb/c mice with DSS in sterile distilled water provided as desired. The syngenic fibroblasts were obtained from Balb/c mice embryos and retrovirally transduced with the hEC-SOD gene. These engineered cells were confirmed to secrete EC-SOD in culture medium by enzyme-linked immunosorbent assay and were inoculated subcutaneously in the backs of DSS-treated mice. Mucosal injury of the colon was evaluated by the disease activity index (DAI: body weight, rectal bleeding, and stool consistency), grading of histologic disease severity, and levels of cytokine (tumor necrosis factor-α, interleukin-1β) production. 8-Hydroxydeoxyguanosine (8-OHdG) levels in the mucosal tissue were assessed by immunohistochemical staining. Malondialdehyde (MDA) was measured using a colorimetric assay. RESULTS: A significant improvement was observed in DAI score and histologic severity as well as in mucosal tissue levels of inflammatory cytokines, 8-OHdG, and MDA of mice treated with the EC-SOD gene as compared with those without gene therapy, not only in a mild colitis model but also in a severe colitis model. Survival of treated mice in these models was significantly prolonged. CONCLUSIONS: Ex vivo transfer of the EC-SOD gene was feasible for treatment of DSS-induced colitis. Copyright © 2006 by Lippincott Williams & Wilkins.