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.
