Development of an Oral Drug Delivery System Targeting Immune-Regulating Cells in Experimental Inflammatory Bowel Disease: A New Therapeutic Strategy1

Several studies have indicated the involvement of macro-phages and dendritic cells in active inflammatory bowel disease (IBD). Manipulation of these cells is considered a very important therapeutic strategy for patients with IBD. We evaluated the effect of a new drug delivery system targeting microfold cells and macrophages with poly(DL-lactic acid) microspheres con-taining dexamethasone (Dx). Colitis was induced in BALB/c mice by 5 % dextran sodium sulfate. Dx microspheres (n 5 10) and only Dx (n 5 10) were orally administered to dextran sodium sulfate-treated mice. Thereafter, serum levels and tis-sue distributions of Dx were investigated. To estimate the effi-cacy of this drug delivery system, we measured the histological score, myeloperoxidase activity and nitric oxide production, and gene expressions of tumor necrosis factor-a, interleukin