No association between vitamin D and β-cell autoimmunity in Finnish and Estonian children.
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.
['Reinert-Hartwall|L|L|', 'Honkanen|J|J|', 'Härkönen|T|T|', 'Ilonen|J|J|', 'Simell|O|O|', 'Peet|A|A|', 'Tillmann|V|V|', 'Lamberg-Allardt|C|C|', 'Virtanen|S M|SM|', 'Knip|M|M|', 'Vaarala|O|O|', '|||']
D015652:25-Hydroxyvitamin D 2 D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase D015551:Autoimmunity D015496:CD4-Positive T-Lymphocytes D002112:Calcifediol D002648:Child D002664:Child Nutritional Physiological Phenomena D002675:Child, Preschool D003922:Diabetes Mellitus, Type 1 D004957:Estonia D005260:Female D005387:Finland D051858:Forkhead Transcription Factors D018507:Gene Expression Regulation, Developmental D056726:Genetic Association Studies D020022:Genetic Predisposition to Disease D006801:Humans D015994:Incidence D050417:Insulin-Secreting Cells D008297:Male D009752:Nutritional Status D014808:Vitamin D Deficiency
Vitamin D autoimmunity T cells beta-cell immunoregulation