Gene silencing of TNF-alpha in a murine model of acute colitis using a modified cyclodextrin delivery system

Inflammatory bowel disease (IBD) is a chronic relapsing inflammation of the gastrointestinal tract. The cytokine TNF-alpha (TNF-alpha) plays a pivotal role in mediating this inflammatory response. RNA interference (RNAi) holds great promise for the specific and selective silencing of aberrantly expressed genes, such as TNF-alpha in IBD. The aim of this study was to investigate the efficacy of an amphiphilic cationic cyclodextrin (CD) vector for effective TNF-alpha siRNA delivery to macrophage cells and to mice with induced acute-colitis. The stability of CD. siRNA was examined by gel electrophoresis in biorelevant media reflecting colonic fluids. RAW264.7 cells were transfected with CD. TNF-alpha siRNA, stimulated with lipopolysaccharide (LPS) and TNF-alpha and IL-6 responses were measured by PCR and ELISA. Female C57BL/6 mice were exposed to dextran sodium sulphate (DSS) and treated by intrarectal administration with either CD. siRNA TNF-alpha or a control solution. In vitro, siRNA in CD nanocomplexes remained intact and stable in both fed and fasted simulated colonic fluids. RAW264.7 cells transfected with CD. TNF-alpha siRNA and stimulated with LPS displayed a significant reduction in both gene and protein levels of TNF-alpha and IL-6. CD. TNF-alpha siRNA-treated mice revealed a mild amelioration in clinical signs of colitis, but significant reductions in total colon weight and colonic mRNA expression of TNF-a and IL-6 compared to DSS-control mice were detected. This data indicates the clinical potential of a local CD-based TNF-alpha siRNA delivery system for the treatment of IBD. (C) 2013 Elsevier B.V. All rights reserved.