Nanoparticle delivery of microRNA-146a regulates mechanotransduction in lung macrophages and mitigates injury during mechanical ventilation

Mechanical ventilation generates injurious forces that exacerbate lung injury. These forces disrupt lung barrier integrity, trigger proinflammatory mediator release, and differentially regulate genes and non-coding oligonucleotides including microRNAs. In this study, we identify miR-146a as a mechanosensitive microRNA in alveolar macrophages that has therapeutic potential to mitigate lung injury during mechanical ventilation. We use humanized in-vitro systems, mouse models, and biospecimens from patients to elucidate the expression dynamics of miR-146a needed to decrease lung injury during mechanical ventilation. We find that the endogenous increase in miR-146a following injurious ventilation is not sufficient to prevent lung injury. However, when miR-146a is highly overexpressed using a nanoparticle delivery platform it is sufficient to prevent injury. These data indicate that the endogenous increase in microRNA-146a during mechanical ventilation is a compensatory response that partially limits injury and that nanoparticle delivery of miR-146a is an effective strategy for mitigating lung injury during mechanical ventilation.


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October 2018

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All studies must disclose on these points even when the disclosure is negative. Experimental sample size was determined by performing a pilot experiment with 6 animals and the sample mean and standard deviation estimates were used to calculate the final sample size with power of 0.8 and ! = .05. Sample size calculations were not performed in vitro studies and sample sizes were estimated based on prior experiments in our laboratory and previously published data.
Outlier testing was performed to identify statistical outliers using non-linear regression via the ROUT method with a Q threshold of 1% for all experiments. Outlier testing was performed prior to statistical testing for differences between groups and outliers were excluded from statistical testing for differences between groups. Outliers was detected in Figures 3B, 3C The nanoparticle encapsulation experiment requested by reviewers was only performed once (Supplemental Figure 6D). All other in vitro experiments were replicated and attempts at replication were successful. Animal studies were not replicated given that sample sizes were determined a priori based on power calculations.
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