title: [Modulation of TLR-4/MyD88 signaling cascade by miR-21 is involved in airway immunologic dysfunction induced by cold air exposure].
abstract: OBJECTIVE
  To investigate the role of miR-21 in airway immunologic dysfunction induced by cold air irritation.
  
  
  METHODS
  Immortalized human airway epithelial cell lines BEAS-2B and 16HBE cells were cultured in air-liquid phases. The differential expressions of endogenous miR-21, miR-164, and miR-155 in the cells induced by cold air exposure for different time were detected by real-time PCR. The reporter plasmid containing wild-type or mutated 3'UTR of TLR-4 were constructed and co-transfected into BEAS-2B cells or 16HBE cells together with miR-21 mimic, miR-21 mimic control, miR-21 inhibitor, or miR-21 inhibitor control. Following the transfection, dual luciferase reporter assay was performed to verify the action of miR-21 on TLR-4. miR-21 mimic, miR-21 mimic control, miR-21 inhibitor, and miR-21 inhibitor control were transfected via lipofectamine 2000 in BEAS-2B or 16HBE cells that were subsequently exposed to a temperature at 37 degrees celsius; or cold irritation (30 degrees celsius;), and the protein levels of TLR-4/MyD88 were detected by Western blotting.
  
  
  RESULTS
  Cold irritation caused a time- dependent up-regulation of miR-21 in both BEAS-2B and 16HBE cells (P<0.05) without obviously affecting the expressions of miR-164 and miR-155. Dual luciferase reporter assay demonstrated a direct combination of miR-21 and its target protein TLR-4. The synthesis levels of TLR-4/MyD88 protein were decreased in miR-21 mimic group even at a routine culture temperature (P<0.05), as also seen in cells with cold irritation (P<0.05). Treatment with the miR-21 inhibitor partially attenuated cold irritation-induced down-regulation of TLR-4/MyD88 protein (P<0.05).
  
  
  CONCLUSIONS
  Cold air irritation-induced airway immunologic dysfunction is probably associated with TLR-4/MyD88 down-regulation by an increased endogenic miR-21.
authors.affiliation: Department of Respiratory Medicine, Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, China.E-mail: chongyixurui@163.com.
authors.forename: Rui
authors.initials: R
authors.lastname: Xu
authors.forename: Huaping
authors.initials: H
authors.lastname: Huang
authors.forename: Zhong
authors.initials: Z
authors.lastname: Han
authors.forename: Minchao
authors.initials: M
authors.lastname: Li
authors.forename: Xiangdong
authors.initials: X
authors.lastname: Zhou
mesh_terms: D020413:3' Untranslated Regions; D015153:Blotting, Western; D002460:Cell Line; D003080:Cold Temperature; D015536:Down-Regulation; D004847:Epithelial Cells / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D008156:Luciferases; D035683:MicroRNAs / Q000378:metabolism*; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction; D051197:Toll-Like Receptor 4 / Q000378:metabolism*; D014162:Transfection; D015854:Up-Regulation
chemical_list: D020413:3' Untranslated Regions; C524940:MIRN21 microRNA, human; C507779:MYD88 protein, human; D035683:MicroRNAs; D053594:Myeloid Differentiation Factor 88; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D008156:Luciferases