title: Intraindividual variation of microRNA expression levels in plasma and peripheral blood mononuclear cells and the associations of these levels with the pathogenesis of autoimmune thyroid diseases.
abstract: BACKGROUND
  microRNAs (miRNAs) circulate in the blood and negatively regulate the expression of mRNAs. Some miRNAs are associated with the development of autoimmune thyroid diseases (AITD); however, there are few reports on the association between miRNA expression and the pathogenesis of AITD or the physiological variations of circulating miRNAs, which are important to examine as biomarkers.
  
  
  METHODS
  We examined the circadian and day-to-day variations in the expression levels of 5 miRNAs (miR-125a, miR-146a, miR-155, let-7e and miR-106a) in plasma and peripheral blood mononuclear cells (PBMC). We also analysed the expression levels of two of these miRNAs (miR-146a and miR-155) in 20 healthy controls, 60 Graves' disease (GD) patients and 50 Hashimoto's disease (HD) patients.
  
  
  RESULTS
  For each miRNA, we observed wide intraindividual variation [coefficient of variation value (CV): 70%-100%] compared to measurement error (CV: 20%-40%). In patients with AITD, HD, GD in remission and mild HD, the expression levels of miR-146a in PBMC were increased 296%, 328%, 348% and 464% above the levels in healthy controls, respectively (p=0.0443 and p=0.0273, p=0.0267 and p=0.0052, respectively). In severe HD, the expression level of miR-155 in plasma was increased to 347% of that in healthy controls (p=0.0256).
  
  
  CONCLUSIONS
  The expression levels of miRNAs in plasma and PBMC showed wide intraindividual variation. In addition, miR-146a may be associated with the development of AITD.
authors.affiliation: Department of Biomedical Informatics, Division of Health Sciences, Osaka University Graduate School of Medicine, Osaka.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Otsu
authors.affiliation: Department of Biomedical Informatics, Division of Health Sciences, Osaka University Graduate School of Medicine, Osaka.
authors.forename: Mikio
authors.initials: M
authors.lastname: Watanabe
authors.affiliation: Department of Biomedical Informatics, Division of Health Sciences, Osaka University Graduate School of Medicine, Osaka.
authors.forename: Naoya
authors.initials: N
authors.lastname: Inoue
authors.affiliation: Department of Biomedical Informatics, Division of Health Sciences, Osaka University Graduate School of Medicine, Osaka.
authors.forename: Ryota
authors.initials: R
authors.lastname: Masutani
authors.affiliation: Department of Biomedical Informatics, Division of Health Sciences, Osaka University Graduate School of Medicine, Yamadaoka 1-7 Suita, Osaka 565-0871.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Iwatani
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002940:Circadian Rhythm; D005260:Female; D020869:Gene Expression Profiling; D006111:Graves Disease / Q000097:blood* / Q000235:genetics* / Q000503:physiopathology; D050031:Hashimoto Disease / Q000097:blood* / Q000235:genetics* / Q000503:physiopathology; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D008297:Male; D035683:MicroRNAs / Q000097:blood / Q000235:genetics*; D008875:Middle Aged; D055815:Young Adult
chemical_list: D035683:MicroRNAs
keywords: autoimmune thyroid diseases; intractability; intraindividual variation; microRNA; severity