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.