Abstract 14803: Treatment of Endotoxin-Induced Acute Lung Injury in Mice by Aptamer-Mediated Inhibition of Angiopoietin-2
Introduction: Acute lung injury (ALI), and the resulting acute respiratory distress syndrome (ARDS), are life-threatening conditions of the lung for which there are currently no specific treatments. Endothelial cell (EC) activation contributes to pulmonary vascular inflammation and increased permeability in ALI/ARDS, which leads to alveolar flooding and impaired gas exchange. Angiopoietin-2 (Angpt-2) is a natural antagonist of the EC selective receptor tyrosine kinase, Tie2, and plays a pivotal role in potentiating vascular inflammation by neutralizing the homeostatic influence of Angpt-1, a Tie2 agonist. Therefore, we hypothesized that inhibition of Angpt-2 activity will be therapeutic in a murine model of ALI.
Methods: A nuclease-resistant anti-Angpt-2 RNA aptamer has previously been reported to selectively inhibit Angpt-2 protein activity. This RNA aptamer was chemically synthesized and its efficacy was evaluated in vivo in a mouse model of ALI induced by the bacterial endotoxin, lipopolysaccharide (LPS). A single injection of the aptamer (0.2 or 1 mg/kg in 100 μl PBS) was administered via the right jugular vein in female C57Bl/6J mice 30 minutes after intratracheal instillation of LPS (100 μg in 50 μL saline). Mice were sacrificed 2 days after LPS-induced injury, and the bronchoalveolar lavage (BAL) fluid was collected to assess total cell infiltrate.
Results: Mice that received LPS and PBS as a vehicle control exhibited a ∼100 fold increase in the total BAL cell count relative to naïve mice. A dose-dependent decrease in BAL total cell count (P<0.05, n=6) was observed in aptamer-treated mice (60% at 1 mg/kg) relative to the PBS vehicle control group, while a non-significant decrease was also observed in mice treated with an equivalent dose of a scrambled-sequence control RNA oligonucleotide (n=6). Similarly, BAL total protein concentrations were significantly reduced with the 1 mg/kg aptamer dose.
Conclusions: An RNA aptamer designed to selectively bind and inhibit Angpt-2 protein activity exhibited beneficial effects on mice with endotoxin-induced ALI. These results provide new evidence to support a significant role for Angpt-2 in the development of ALI/ARDS, and suggest a novel molecular strategy for a specific therapeutic intervention.
- © 2010 by American Heart Association, Inc.