BRD4 and chronic obstructive pulmonary disease: Furthermore, the upregulated miR-223 (Leuenberger et al., 2016) and downregulated miR-149-3p (Shen et al., 2017), miR-145-5p (Dang et al., 2019), and miR-29b (Li et al., 2019b) acted on histone deacetylase 2 (HDAC2), CCAAT/enhancer-binding protein beta (C/EBP-β), transforming growth factor beta1 (TGF-β1), Toll-like receptor 4 (TLR-4)/nuclear transcription factor-kappa B (NF-κB), kruppel-like factor 5 (KLF5), and bromodomain-containing protein 4 (BRD4), respectively, thereby regulating the inflammatory response in COPD patients.