Regulatory T Cells and Vitamin D Status in Children with Chronic Autoimmune Thyroiditis

OBJECTIVE: It is suggested that vitamin D is one of the factors that can regulate the function of Treg cells. In this study, the relationships between Treg cells and vitamin D levels was investigated in pediatric chronic autoimmune thyroiditis (CAT) patients. METHODS: Thirty-two children with CAT and 24 healthy subjects were studied. FOXP3 expressing CD4+CD25+high Foxp3+T cells were identified as Treg cells. At diagnosis, 25-hydroxycholecalciferol (25OHD3) levels were determined in all patients. FOXP3 expression was measured before and after vitamin D replacement therapy in patients having low levels of 25OHD3. RESULTS: In the CAT patients, Treg cell levels did not differ from the control group, while the frequency of vitamin D deficiency was higher and FOXP3 molecule expression was lower. FOXP3 molecule expression significantly increased in CAT patients having vitamin D deficiency who were given vitamin D replacement. CONCLUSION: FOXP3 expression is decreased in pediatric CAT patients. This reduction seems to be associated with vitamin D levels. Vitamin D can play a role in enhancing natural Treg cell functions.