In vivo targeting of miRNAs in allergic airways disease — University of Technology
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In vivo targeting of miRNAs in allergic airways disease (14244)

Maximilian W Plank 1 , Hock L Tay 1 , Steven Maltby 1 , Joerg Mattes 2 , Phil Hansbro 1 , Paul S Foster 1
  1. Centre for Asthma and Respiratory Diseases, University of Newcastle and Hunter Medical Research Institute, Newcastle, NSW, Australia
  2. Immunology and Respiratory Research Group, University of Newcastle and Hunter Medical Research Institute, Newcastle, NSW, Australia

Background: MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression, with emerging roles in immune cell regulation. Their contribution to the development of many diseases is now well-established. However, the role of miRNAs in the development of allergic asthma remains to be investigated and novel methods to target miRNAs in vivo may open up new strategies for the treatment of asthma.

Aims: We hypothesize that miRNAs are altered in allergic airways disease and may serve as novel targets for the treatment of disease. Aim 1: Identify altered miRNAs in allergic airways disease. Aim 2: Assess the impact of targeting miRNA function in vivo using antagomirs.

Methods: We performed miRNA profiling on lungs from naïve and allergic mice and compared these profiles to glucocorticoid (dexamethasone) treatment, using miRNA microarray analysis and real-time PCR. To assess for a functional role in disease development, we inhibited two highly upregulated miRNAs using specific antagomirs in vivo. Antagomirs are modified RNA molecules with complementary sequence to a miRNA of interest and cause efficient, long-lasting target inhibition. The uptake of fluorescently-labelled antagomir into lung cell populations was assessed and miRNA knockdown efficiency in total lung and differential cell populations was analyzed. Further, the impact of antagomir targeting on airways hyperreactivity and inflammation was assessed.
Results: We identified distinctive miRNA signatures in allergic mouse lungs and identified 29 miRNAs that were significantly altered, compared to naïve lung samples. Analysis of predicted miRNA targets revealed novel target genes with altered mRNA expression (confirmed by qRT-PCR) and demonstrated synergistic miRNA regulation in allergic lungs. Using antagomirs, we inhibited the function of two specific miRNAs and investigated the effect of this treatment on hallmark features of allergic airway disease. The inhibition of these miRNAs failed to induce alterations to disease phenotype. While antagomir administration successfully reduced target miRNAs levels in total lung samples, it failed to target all cell types of the lung effectively. This correlated with high levels of fluorescently-labelled antagomir uptake in granulocytes.

Conclusions: MiRNA signatures in the lungs are altered following allergen challenge. Characterization of the miRNA regulation in asthma unveils a new level of regulation in disease, which could serve as novel targets for treatment. Targeting miRNAs in the lung with antagomirs is effective, however limited to granulocytes. As such, we propose that the cellular source of altered miRNA expression in the lung must be considered when designing antagomir-based treatments.
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