Human immature myeloid dendritic cells trigger a TH2-polarizing program via Jagged-1/Notch interaction.

Autor: Liotta, Francesco, Frosali, Francesca, Querci, Valentina, Mantei, Andrej, Filì, Lucia, Maggi, Laura, Mazzinghi, Benedetta, Angeli, Roberta, Ronconi, Elisa, Santarlasci, Veronica, Biagioli, Tiziana, Lasagni, Laura, Ballerini, Clara, Parronchi, Paola, Scheffold, Alexander, Cosmi, Lorenzo, Maggi, Enrico, Romagnani, Sergio, Annunziato, Francesco
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Zdroj: Journal of Allergy & Clinical Immunology; Apr2008, Vol. 121 Issue 4, p1000-1005, 6p
Abstrakt: Background: The mechanisms by which human dendritic cells (DCs) activate a TH1-polarizing or TH2-polarizing program are still partially unclear. Objective: Study of the mechanisms responsible for the TH1/TH2-polarizing activity of human circulating myeloid DCs before and after ligation of their Toll-like receptors (TLRs). Methods: IL-4 and IFN-γ production by CD4+ T cells was assessed in cocultures with myeloid DCs before or after TLR triggering. Expression of Jagged-1 and Delta-4 Notch ligands and of GATA-3 and T-box expressed in T cells transcription factors was evaluated by real-time quantitative PCR. Signal transducer and activator of transcription 4 and 6 phosphorylation was assessed by flow cytometry. Knockdown of Jagged-1 or Delta-4 was performed by transfection of DCs with appropriate silencing mRNAs. Results: Myeloid immature DCs constitutively expressed Jagged-1, which induces in CD4+ T cells a TH2 polarization, as shown by Jagged-1 gene silencing. The TH2 polarization associated with high GATA-3/T-box expressed in T cells ratio and was at least partially dependent on the early induction of IL-4. Maturation of DCs by TLR ligation resulted in the reduction of Jagged-1 and upregulation of Delta-4, which was at least in part responsible for the polarization of CD4+ T cells to the TH1 phenotype. Conclusion: CD4+ T-cell responses are usually characterized by a prevalent TH2 phenotype unless TLRs are triggered on DCs by microbial components. [Copyright &y& Elsevier]
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