Polyethylenimine-based antisense oligodeoxynucleotides of IL-4 suppress the production of IL-4 in a murine model of airway inflammation

Background Interleukin‐4 (IL‐4) plays a crucial role as an inflammatory mediator in allergic asthma via inducing Th2 inflammation and IgE synthesis. To develop an effective therapeutic agent which specifically inhibits production of IL‐4, antisense oligodeoxynucleotides (AS‐ODNs) against murine IL‐4 mRNA were generated and complexed with polyethylenimine (PEI) to improve intracellular delivery. Methods AS‐ODNs were generated against the translation initiation region of murine IL‐4 mRNA, and complexed with linear PEI. In vitro efficacy of AS‐ODNs/PEI complexes was tested by measuring IL‐4 production in the D10.G4.1 cell line, and cytotoxicity was tested by XTT assay. Physicochemical properties of polyplexes were examined using atomic force microscopy (AFM) and DNase I protection assay. In vivo effects of IL‐4 AS‐ODNs/PEI complexes were tested in a murine model of airway inflammation. IL‐4 concentrations in the bronchoalveolar lavage (BAL) fluid and circulating IgE levels were measured by ELISA, and histological analysis of lung tissues was performed. Results IL‐4 AS‐ODNs/PEI complexes were spheres with an average diameter of 98 nm and resistant to DNase I‐mediated degradation. IL‐4 AS‐ODNs/PEI complexes showed up to 35% inhibition of IL‐4 production in D10.G4.1 cells without causing any toxicity, while naked ODNs gave less than 1% reduction. Furthermore, IL‐4 AS‐ODNs/PEI complexes were effective in suppressing secretion of IL‐4 (up to 30% reduction) in the BAL fluid in an ovalbumin‐sensitized murine model of airway inflammation. Circulating IgE levels were decreased, and airway inflammation was alleviated by treatment with IL‐4 AS‐ODNs polyplexes. Conclusions These data demonstrate that complexation of IL‐4 AS‐ODNs with PEI provides a potential therapeutic tool in controlling inflammation associated with allergic asthma, and further presents an opportunity to the development of clinical therapy based on combination of multiple AS‐ODNs of cytokines and/or signaling effectors involved in Th2 inflammation and eosinophilia. Copyright © 2005 John Wiley & Sons, Ltd.