• A Froidure, C Shen, D Gras, J Van Snick, P Chanez, and C Pilette.
• Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain and Walloon Institute for Excellence in Lifesciences and Biotechnology (WELBIO), Brussels, Belgium; Cliniques Universitaires Saint-Luc, service de Pneumologie, Brussels, Belgium.
• Allergy. 2014 Aug 1; 69 (8): 1068-76.

BackgroundType 1 myeloid dendritic cells (mDCs) contribute to inception of allergic asthma (AA) and are regulated by epithelial-derived cytokines.ObjectivesTo evaluate whether mDCs from AA patients are primed for thymic stromal lymphopoietin (TSLP)-driven responses.MethodsmDCs from 18 AA patients and 15 controls were purified using immunomagnetic sorting. Cells were pulsed with TSLP or Dermatophagoides pteronyssinus (Der p) allergen, before FACS phenotyping and co-culture with allogeneic CD4+ T cells. Bronchial biopsies from 15 AA patients and four controls were immunostained for CD1c and TSLP receptor (TSLPR).ResultsAllergic asthma patients had a higher proportion of TSLPR+ mDCs, in blood and bronchial mucosa. When compared to mDCs from controls, both TSLP- and Der p-pulsed blood mDCs from AA patients induced increased polarization of CD4+ T cells into Th2 cells (IL-5, IL-13, and GATA3+), while only TSLP-mDCs promoted Th9 cells (IL-9 and PU.1+ /IRF4+). In addition, OX40L was induced upon TSLP stimulation and was required for the induction of Th2, but not Th9, cells. In contrast, development of Th9 cells in this model depended on TGF-β1.ConclusionsOur data indicate overlapping but partially distinct effects of TSLP and Der p allergen pathways, showing that DCs are primed in human asthma for TSLP-driven induction of both Th2 and Th9 cells. This novel TSLP/mDC/Th9 axis operates through a distinct, OX40L-independent pathway. These data further highlight the TSLP pathway as a relevant target in human asthma.© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

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