C. Zgheib1, S. A. Hilton1, L. C. Dewberry1, J. Hu1, J. Xu1, S. Seal3, L. Hernandez-Lagunas2, E. Nozik-Grayck2, K. W. Liechty1 1Laboratory for Fetal and Regenerative Biology, Department of Surgery, University of Colorado Denver School of Medicine and Children’s Hospital Colorado,Aurora, CO, USA 2Developmental Lung Biology and Cardiovascular Pulmonary Research Laboratories, University of Colorado,Aurora, CO, USA 3Department of Material Science Engineering, AMPAC, Nanoscience Technology Center, College of Medicine, University of Central Florida,Orlando, FL, USA
Introduction:
Acute lung injury is characterized by an initial inflammatory response accompanied by acute respiratory distress and surfactant deficiency, which can progress to chronic pulmonary fibrosis. Following lung injury, the respiratory epithelium releases pro-inflammatory mediators which promote the recruitment of neutrophils and subsequently macrophages into the injury sites, further increasing cytokine production and modulation of the extracellular matrix, including collagen. We have previously shown that following injury, delivery of miR146a – an anti-inflammatory microRNA – via conjugation with cerium oxide nanoparticles (CNP), significantly reduced inflammation and promoted healing of impaired diabetic wounds. Thus, we hypothesized that intra-tracheal delivery of CNP-miR146a at the time of bleomycin injury may reduce pulmonary inflammation and subsequent fibrosis.
Methods:
Using an established murine model, juvenile (10 week) male C57BL/6 mice, underwent intra-tracheal instillation of bleomycin (3 units/kg), PBS (n = 5), or bleomycin (n = 6) and a single dose of CNP-miR146a (100 ng, n = 6). Animals were euthanized 14 days post-injury for lung inflation and tissue harvest. Tissue was homogenized and total RNA was extracted. QPCR analysis was used to measure the gene expression of the following inflammatory markers IL-6, IL-1b, and TNFα.
Results:
Our data revealed that bleomycin-induced lung injury in mice resulted in significant upregulation of pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-α), IL-6, and IL-1β, compared to PBS treated controls. Interestingly, intra-tracheal instillation of CNP-miR146a at the time of bleomycin injury showed decreased expression of these pro-inflammatory markers. This data is in agreement with our previous findings that demonstrated less mucosal sloughing/hemorrhage, decreased CD45+inflammatory cells, and markedly decreased lung fibrosis in the CNP-miR146a-treated bleomycin group compared to the bleomycin treatment alone.
Conclusions:
This study results’ indicate that CNP-miR146a decreases the inflammation associated with the bleomycin induced lung injury. CNP-miR146a is a promising therapeutic that could limit the consequences of acute lung injury and warrants further evaluation.