title: Repression of Toll-like receptor-4 by microRNA-149-3p is associated with smoking-related COPD.
abstract: BACKGROUND
  Smoking is the leading cause of COPD. Exploring molecular markers and understanding the pathogenic mechanisms of smoking-related COPD are helpful for early clinical diagnosis and treatment of the disease. This study aims to identify specific circulating microRNAs (miRNAs) from the blood of COPD patients with a long history of smoking.
  
  
  METHODS
  Blood samples from four different groups were collected, and miRNA microarray was performed. Differential expression of miRNAs was verified by quantitative polymerase chain reaction. In vitro, THP-1 cells were cultured and stimulated with cigarette smoke extract (CSE) or transfected with miR-149-3p inhibitor/mimics. Protein levels of Toll-like receptor 4 (TLR-4) and nuclear factor κB (NF-κB) were detected using Western blot and immunofluorescence. Interleukin (IL)-1β and tumor necrosis factor (TNF)-α levels were determined by an enzyme-linked immunosorbent assay.
  
  
  RESULTS
  miRNA profiling revealed that the expression of 56 miRNAs was changed between the four groups. Expression of miR-149-3p in group C (non-smoker non-COPD) was higher than in group S (smoker non-COPD), S-COPD (smoker with stable COPD) and AE-COPD (smoker with acute exacerbation COPD). CSE stimulation down-regulated the expression of miR-149-3p and up-regulated the TLR-4 and NF-κB levels in THP-1 cells. Transfecting miR-149-3p inhibitors in THP-1 cells also increased the expression of its target genes. Furthermore, overexpression of miR-149-3p inhibited the TLR-4/NF-κB signaling pathways and reduced the secretion of IL-1β and TNF-α.
  
  
  CONCLUSIONS
  This study found that smoking can induce differential expression of circulating miR-NAs, such as down-regulation of miR-149-3p. Reducing miR-149-3p may increase the inflammatory response in COPD patients through the regulation of the TLR-4/NF-κB signaling pathway.
authors.affiliation: Department of Respiratory Medicine.
authors.forename: Wen
authors.initials: W
authors.lastname: Shen
authors.affiliation: Department of Experimental Zoology, The Second Affiliated Hospital of Kunming Medical University.
authors.forename: Jia
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Respiratory Medicine.
authors.forename: Guohou
authors.initials: G
authors.lastname: Zhao
authors.affiliation: Department of Respiratory Medicine.
authors.forename: Minjuan
authors.initials: M
authors.lastname: Fan
authors.affiliation: School of Pharmaceutical Science, Kunming Medical University.
authors.forename: Gao
authors.initials: G
authors.lastname: Song
authors.affiliation: Department of Respiratory Medicine.
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: School of Pharmaceutical Science, Kunming Medical University.
authors.forename: Zhiying
authors.initials: Z
authors.lastname: Weng
authors.affiliation: Department of Hematology, The Second Affiliated Hospital of Kunming Medical University, Kunming, Yunnan Province, People's Republic of China.
authors.forename: You
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D016022:Case-Control Studies; D045744:Cell Line, Tumor; D015536:Down-Regulation; D020869:Gene Expression Profiling; D006801:Humans; D053583:Interleukin-1beta / Q000378:metabolism; D035683:MicroRNAs / Q000097:blood / Q000235:genetics*; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood / Q000175:diagnosis / Q000235:genetics*; D012906:Smoke / Q000009:adverse effects*; D012907:Smoking / Q000009:adverse effects* / Q000097:blood / Q000235:genetics; D051197:Toll-Like Receptor 4 / Q000235:genetics* / Q000378:metabolism; D051996:Transcription Factor RelA / Q000378:metabolism; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: C508585:IL1B protein, human; D053583:Interleukin-1beta; C551557:MIRN149 microRNA, human; D035683:MicroRNAs; C498143:RELA protein, human; D012906:Smoke; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha
keywords: COPD; Toll-like receptor 4; microRNA-149-3p; nuclear factor κB; smoking