TY - JOUR T1 - Co-culture of naïve CD4+ T cells and vitamin D modulate – Th17 cells in young asthmatic children JF - European Respiratory Journal JO - Eur Respir J VL - 44 IS - Suppl 58 SP - 3232 AU - Besma Hamdi AU - Wajih Kaabachi AU - Berraies Anissa AU - Ammar Jamel AU - Kamel Hamzaoui AU - Agnes Hamzaoui Y1 - 2014/09/01 UR - http://erj.ersjournals.com/content/44/Suppl_58/3232.abstract N2 - 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 ± 83.59pg/ml v.s. 452.0 ± 116.0 pg/ml; P = 0.0022] and decreased the percentage of CD4+IL-17+ [4.35% ± 1.12% v.s. 5.91% ± 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. ER -