title: MicroRNA expression in response to controlled exposure to diesel exhaust: attenuation by the antioxidant N-acetylcysteine in a randomized crossover study.
abstract: BACKGROUND
  Adverse health effects associated with diesel exhaust (DE) are thought to be mediated in part by oxidative stress, but the detailed mechanisms are largely unknown. MicroRNAs (miRNAs) regulate gene expression post-transcriptionally and may respond to exposures such as DE.
  
  
  OBJECTIVE
  We profiled peripheral blood cellular miRNAs in participants with mild asthma who were exposed to controlled DE with and without antioxidant supplementation.
  
  
  METHODS
  Thirteen participants with asthma underwent controlled inhalation of filtered air and DE in a double-blinded, randomized crossover study of three conditions: a) DE plus placebo (DEP), b) filtered air plus placebo (FAP), or c) DE with N-acetylcysteine supplementation (DEN). Total cellular RNA was extracted from blood drawn before exposure and 6 hr after exposure for miRNA profiling by the NanoString nCounter assay. MiRNAs significantly associated with DEP exposure and a predicted target [nuclear factor (erythroid-derived 2)-like 2 (NRF2)] as well as antioxidant enzyme genes were assessed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) for validation, and we also assessed the ability of N-acetylcysteine supplementation to block the effect of DE on these specific miRNAs. 8-hydroxy-2'-deoxyguanosine (8-OHdG) was measured in plasma as a systemic oxidative stress marker.
  
  
  RESULTS
  Expression of miR-21, miR-30e, miR-215, and miR-144 was significantly associated with DEP. The change in miR-144 was validated by RT-qPCR. NRF2 and its downstream antioxidant genes [glutamate cysteine ligase catalytic subunit (GCLC) and NAD(P)H:quinone oxidoreductase 1 (NQO1)] were negatively associated with miR-144 levels. Increases in miR-144 and miR-21 were associated with plasma 8-hydroxydeoxyguanosine 8-OHdG level and were blunted by antioxidant (i.e, DEN).
  
  
  CONCLUSIONS
  Systemic miRNAs with plausible biological function are altered by acute moderate-dose DE exposure. Oxidative stress appears to mediate DE-associated changes in miR-144.
authors.affiliation: Department of Medicine, Division of Respiratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Masatsugu
authors.initials: M
authors.lastname: Yamamoto
authors.forename: Amrit
authors.initials: A
authors.lastname: Singh
authors.forename: Francesco
authors.initials: F
authors.lastname: Sava
authors.forename: Mandy
authors.initials: M
authors.lastname: Pui
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Tebbutt
authors.forename: Christopher
authors.initials: C
authors.lastname: Carlsten
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology*; D000328:Adult; D000975:Antioxidants / Q000494:pharmacology*; D017252:CD3 Complex / Q000032:analysis; D018592:Cross-Over Studies; D004311:Double-Blind Method; D006801:Humans; D035683:MicroRNAs / Q000032:analysis*; D051267:NF-E2-Related Factor 2 / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D001335:Vehicle Emissions / Q000633:toxicity*
chemical_list: D000975:Antioxidants; D017252:CD3 Complex; C554293:MIRN144 microRNA, human; D035683:MicroRNAs; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D001335:Vehicle Emissions; D000111:Acetylcysteine