@article {Hamdi3232, author = {Besma Hamdi and Wajih Kaabachi and Berraies Anissa and Ammar Jamel and Kamel Hamzaoui and Agnes Hamzaoui}, title = {Co-culture of na{\"\i}ve CD4+ T cells and vitamin D modulate {\textendash} Th17 cells in young asthmatic children}, volume = {44}, number = {Suppl 58}, elocation-id = {3232}, year = {2014}, publisher = {European Respiratory Society}, abstract = {1,25-Dihydroxyvitamin D3 (Vit D) deficiency has been associated with childhood asthma inflammatory pathways, however data are still lacking about the effect of vitamin D supplementation on immune regulation in asthmatic children. In this study, we investigated Vit D inhibitory effect on the immune response in young asthmatic patients and the possible mechanisms involved.Peripheral blood CD4+ T cells from 10 asthmatic patients with hypovitaminosis D and 10 healthy controls were cultured under Th17 polarizing conditions in the presence or absence of Vit D, and IL-17cytokines production was determined by ELISA and flow cytometry. mRNA expression of several factors related to Th17 cell function were determined by real-time PCR. The effect of Vit D-treated dendritic cells (DCs) on CD4+ T cell response was determined by ELISA and flow cytometry.Stimulation of naive CD4+ T cells under Th17 polarizing conditions showed a higher Th17 cell differentiation in asthmatic patients than healthy controls. The addition of Vit D significantly inhibited Th17 cell differentiation both in patients[P \< 0.0004] and in normal controls [P = 0.0001] in dose dependent way. Vit D was able to inhibit the gene expression of RORC, IL-17, IL-23R, and CCR6 differenciation. Vit D-treated DCs significantly inhibited IL-17 level [291.0 {\textpm} 83.59pg/ml v.s. 452.0 {\textpm} 116.0 pg/ml; P = 0.0022] and decreased the percentage of CD4+IL-17+ [4.35\% {\textpm} 1.12\% v.s. 5.91\% {\textpm} 1.17\%;P = 0.0072] in young asthmatics.The findings suggest that the inhibitory effect of VitD on the Th17 response was mediated via both T cells and DCs. DCs pathway is involved in the direct inhibition of VitD on Th17 cell differentiation in young asthmatics.}, issn = {0903-1936}, URL = {https://erj.ersjournals.com/content/44/Suppl_58/3232}, eprint = {https://erj.ersjournals.com/content}, journal = {European Respiratory Journal} }