Bioinformatics-based identification of potential microRNA biomarkers in frequent and non-frequent exacerbators of COPD

Xiao Liu,1,* Jingge Qu,2,* Weixiao Xue,1 Liangai He,1 Jun Wang,3 Xuejiao Xi,1 Xiaoxia Liu,1 Yunhong Yin,1 Yiqing Qu1 1Department of Respiratory Medicine, Qilu Hospital of Shandong University, Jinan, People’s Republic of China; 2Department of Rheumatology, Second Hospital of Harbin Medical University, Harbin, People’s Republic of China; 3Department of Respiratory Medicine, Second Hospital of Shandong Traditional Chinese Medicine University, Jinan, People’s Republic of China *These authors contributed equally to this work Objectives: MicroRNAs (miRNAs) play essential roles in the development of COPD. In this study, we aimed to identify and validate potential miRNA biomarkers in frequent and non-frequent exacerbators of COPD patients using bioinformatic analysis.Materials and methods: The candidate miRNA biomarkers in COPD were screened from Gene Expression Omnibus (GEO) dataset and identified using GEO2R online tool. Then, we performed bioinformatic analyses including target prediction, gene ontology (GO), pathway enrichment analysis and construction of protein–protein interaction (PPI) network. Furthermore, the expression of the identified miRNAs in peripheral blood monocular cells (PBMCs) of COPD patients was validated using quantitative real-time polymerase chain reaction (qRT-PCR).Results: MiR-23a, miR-25, miR-145 and miR-224 were identified to be significantly downregulated in COPD patients compared with healthy controls. GO analysis showed the four miRNAs involved in apoptotic, cell differentiation, cell proliferation and innate immune response. Pathway analysis showed that the targets of these miRNAs were associated with p53, TGF-β, Wnt, VEGF and MAPK signal pathway. In healthy controls, the miR-25 and miR-224 levels were significantly decreased in smokers compared with nonsmokers (P