Distribution and efficacy of a GATA-3-specific DNAzyme in experimental allergic asthma models

Allergic bronchial asthma is a chronic inflammatory disease of the airways. T helper 2 (Th2) cells and their master transcription factor GATA-3 that controls differentiation and effector function of these cells, have been shown to play a central role in the pathology of the disease. Except Th2 cells, GATA-3 is also involved in the regulation of other cells contributing to disease development including mast cells, eosinophils and epithelial cells. We developed GATA-3-specific DNAzyme termed hgd40 that combines the high specificity of antisense molecules with an inherent RNA- cleaving enzymatic activity.

Intranasal administration of hgd40 in several experimental murine models of asthma significantly prevented typical features of allergic airway inflammation such as eosinophilia, mucus hyperproduction and development of airway hyperresponsiveness to methacholine. We furthermore demonstrated that the DNAzyme was evenly distributed in inflamed mouse lungs and hgd40 could be intracellularly detected in T cells, Goblet cells, alveolar epithelial type 1 cells and macrophages 2h after single intranasal application. Generally, significant amounts of hgd40 were only detectable in the lungs and in the urine, but not in other organs. In the blood, only low DNAzyme levels were observed 5min post application (p.a) that decreased over time to non-detectable levels at 2h p.a. Altough the amount of hgd40 in lungs decreased over time, small amounts were still detectable in lungs up to 7d p.a. There was no significant plasma accumulation of hgd40 after multiple inhalations in rats and dogs. Moreover, no off-target effects were observed both in vitro and in vivo.

Our results indicate that local hgd40 DNAzyme admimistration can target different lung cells expressing GATA-3 and thus effectively modulate Th2-driven inflammatory responses. Low concentrations in blood and lack of accumulation in non-target organs make this DNAzyme a promising novel approach for the treatment of allergic bronchial asthma.