title: Vitamin D supplementation and regulatory T cells in apparently healthy subjects: vitamin D treatment for autoimmune diseases?
abstract: BACKGROUND
  Epidemiological data show significant associations of vitamin D deficiency and autoimmune diseases. Vitamin D may prevent autoimmunity by stimulating naturally occurring regulatory T cells.
  
  
  OBJECTIVE
  To elucidate whether vitamin D supplementation increases Tregs frequency (%Tregs) within circulating CD4+ T cells.
  
  
  METHODS
  We performed an uncontrolled vitamin D supplementation trial among 50 apparently healthy subjects including supplementation of 140,000 IU at baseline and after 4 weeks (visit 1). The final follow-up visit was performed 8 weeks after the baseline examination (visit 2). Blood was drawn at each study visit to determine 25-hydroxyvitamin D levels and %Tregs. Tregs were characterized as CD4+CD25++ T cells with expression of the transcription factor forkhead box P3 and low or absent expression of CD127.
  
  
  RESULTS
  Forty-six study participants (65% females, mean age +/- SD 31 +/- 8 years) completed the trial. 25(OH)D levels increased from 23.9 +/- 12.9 ng/ml at baseline to 45.9 +/- 14.0 ng/ml at visit 1 and 58.0 +/- 15.1 ng/ml at visit 2. %Tregs at baseline were 4.8 +/- 1.4. Compared to baseline levels we noticed a significant increase of %Tregs at study visit 1 (5.9 +/- 1.7, P < 0.001) and 2 (5.6 +/- 1.6, P < 0.001).
  
  
  CONCLUSIONS
  Vitamin D supplementation was associated with significantly increased %Tregs in apparently healthy individuals. This immunomodulatory effect of vitamin D might underlie the associations of vitamin D deficiency and autoimmune diseases. Hence, our finding provides a rationale for further studies to investigate vitamin D effects on autoimmunological processes.
authors.affiliation: Division of Endocrinology and Nuclear Medicine, Medical University of Graz, Austria.
authors.forename: Barbara
authors.initials: B
authors.lastname: Prietl
authors.forename: Stefan
authors.initials: S
authors.lastname: Pilz
authors.forename: Michael
authors.initials: M
authors.lastname: Wolf
authors.forename: Andreas
authors.initials: A
authors.lastname: Tomaschitz
authors.forename: Barbara
authors.initials: B
authors.lastname: Obermayer-Pietsch
authors.forename: Winfried
authors.initials: W
authors.lastname: Graninger
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Pieber
mesh_terms: D000328:Adult; D002097:C-Reactive Protein / Q000032:analysis; D018791:CD4 Lymphocyte Count; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology; D002118:Calcium / Q000097:blood; D019587:Dietary Supplements; D005260:Female; D005500:Follow-Up Studies; D051858:Forkhead Transcription Factors / Q000032:analysis; D006801:Humans; D007155:Immunologic Factors / Q000494:pharmacology; D053645:Interleukin-2 Receptor alpha Subunit / Q000032:analysis; D053699:Interleukin-7 Receptor alpha Subunit / Q000032:analysis; D008297:Male; D010865:Pilot Projects; D050378:T-Lymphocytes, Regulatory / Q000145:classification / Q000187:drug effects*; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood / Q000494:pharmacology*; D014815:Vitamins / Q000494:pharmacology*
chemical_list: C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; C508017:IL2RA protein, human; D007155:Immunologic Factors; D053645:Interleukin-2 Receptor alpha Subunit; D053699:Interleukin-7 Receptor alpha Subunit; D014815:Vitamins; D014807:Vitamin D; D002097:C-Reactive Protein; C104450:25-hydroxyvitamin D; D002118:Calcium