mRNA and miRNA Regulatory Networks Reflective of Multi-Walled Carbon Nanotube-Induced Lung Inflammatory and Fibrotic Pathologies in Mice

Multi-walled carbon nanotubes (MWCNTs) are known for their transient inflammatory and progressive fibrotic pulmonary effects; however, the mechanisms underlying these pathologies are unknown. In this study, we used time-series microarray data of global lung mRNA and miRNA expression isolated from C57BL/6J mice exposed by pharyngeal aspiration to vehicle or 10, 20, 40, or 80 µg MWCNT at 1, 7, 28, or 56 days post-exposure to determine miRNA and mRNA regulatory networks that are potentially involved in MWCNT-induced inflammatory and fibrotic lung etiology. Using a non-negative matrix factorization method, we determined mRNAs and miRNAs with expression profiles associated with pathology patterns of MWCNT-induced inflammation (based on bronchoalveolar lavage score) and fibrosis (based on Sirius Red staining measured with quantitative morphometric analysis). Potential binding targets between pathology-related mRNAs and miRNAs were identified using Ingenuity Pathway Analysis and the miRTarBase, miRecords, and TargetScan databases. Using these experimentally validated and predicted binding targets, we were able to build molecular signaling networks that are potentially reflective of and play a role in MWCNT-induced lung inflammatory and fibrotic pathology. As understanding the regulatory networks between mRNAs and miRNAs in different disease states would be beneficial for understanding the complex mechanisms of pathogenesis, these identified genes and pathways may be useful for determining biomarkers of MWCNT-induced lung inflammation and fibrosis for early detection of disease.