Explore the associated MiRNAs with emphysema severity of chronic obstructive pulmonary disease

MicroRNAs (MiRNA) are small non-coding RNAs that regulate gene expression. Up to date, seventy miRNAs have been found differentially expressed in lung whole tissue between smoking patients affected by Chronic Obstructive Pulmonary Disease (COPD) and smokers. The aim of this study was to explore the associated miRNAs with emphysema severity of COPD. Firstly, we identified miRNAs differentially expressed between mild and moderately emphysematous lung. Secondly, we used a new mutual information estimation method to construct the miRNA-miRNA interaction network based on these differentially expressed miRNAs. Then we performed the network structure analysis and extracted the COPD-related hub miRNAs. Finally, we compared the classification accuracy of the identified hub miRNAs and the differentially expressed miRNAs. As a result, we identified 4 hub miRNAs: miR-200b, miR-92b, miR-511 and miR-449b. miR-200b and miR-92b are up-regulated in mild emphysema patients whereas miR-511 and miR-449b are down-regulated in mild emphysema patients. In addition, as the predictors to classify samples, the results also showed that the classification accuracy rate of 4 identified hub miRNAs was higher than 156 differentially expressed miRNAs.