title: No association between vitamin D and β-cell autoimmunity in Finnish and Estonian children.
abstract: BACKGROUND
  Vitamin D has immunomodulatory properties, such as regulation of FOXP3 expression and regulatory T-cell activity. Our aim was to investigate whether plasma 25-hydroxyvitamin D [25(OH)D] concentrations associate with the development of β-cell autoimmunity and the transcriptional activity of FOXP3 or vitamin D3 convertase gene (CYP27B1) in CD4+ memory T cells.
  
  
  METHODS
  We studied 83 Finnish and 32 Estonian children participating in the DIABIMMUNE and DIPP studies. Twenty-nine Finnish and six Estonian children tested positive for at least one diabetes-associated autoantibody. The plasma concentrations of 25(OH)D and 1,25(OH)₂D were analysed with an enzyme immunoassay. Gene expression of FOXP3 and CYP27B1 in the isolated CD4+ memory T cells was studied with reverse transcription quantitative polymerase chain reaction.
  
  
  RESULTS
  Vitamin D status did not differ between subjects positive and negative for β-cell autoantibodies. Finnish children had higher vitamin D status than Estonian children (p < 0.001). FOXP3 expression was higher in Estonian CD4+ memory T-cell samples than in Finnish samples (p < 0.01) even when including in both groups only children with serum 25(OH)D concentrations in the range of 50-80 nmol/L (p < 0.001).
  
  
  CONCLUSIONS
  These findings do not support a crucial role of circulating 25(OH)D as a regulator of β-cell autoimmunity or FOXP3 expression.
authors.affiliation: Department of Vaccination and Immune Protection, National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: L
authors.initials: L
authors.lastname: Reinert-Hartwall
authors.forename: J
authors.initials: J
authors.lastname: Honkanen
authors.forename: T
authors.initials: T
authors.lastname: Härkönen
authors.forename: J
authors.initials: J
authors.lastname: Ilonen
authors.forename: O
authors.initials: O
authors.lastname: Simell
authors.forename: A
authors.initials: A
authors.lastname: Peet
authors.forename: V
authors.initials: V
authors.lastname: Tillmann
authors.forename: C
authors.initials: C
authors.lastname: Lamberg-Allardt
authors.forename: S M
authors.initials: SM
authors.lastname: Virtanen
authors.forename: M
authors.initials: M
authors.lastname: Knip
authors.forename: O
authors.initials: O
authors.lastname: Vaarala
mesh_terms: D015652:25-Hydroxyvitamin D 2 / Q000097:blood*; D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase / Q000097:blood / Q000235:genetics / Q000378:metabolism; D015551:Autoimmunity; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D002112:Calcifediol / Q000097:blood*; D002648:Child; D002664:Child Nutritional Physiological Phenomena; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000209:etiology* / Q000235:genetics / Q000276:immunology; D004957:Estonia / Q000453:epidemiology; D005260:Female; D005387:Finland / Q000453:epidemiology; D051858:Forkhead Transcription Factors / Q000097:blood / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D056726:Genetic Association Studies; D020022:Genetic Predisposition to Disease; D006801:Humans; D015994:Incidence; D050417:Insulin-Secreting Cells / Q000276:immunology*; D008297:Male; D009752:Nutritional Status; D014808:Vitamin D Deficiency / Q000503:physiopathology*
chemical_list: C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D015652:25-Hydroxyvitamin D 2; D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase; D002112:Calcifediol
keywords: T cells; Vitamin D; autoimmunity; beta-cell; immunoregulation