The expression of dendritic cell subsets in severe chronic rhinosinusitis with nasal polyps is altered

Background: Chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized as a Th2-driven disease. Activated dendritic cells (DCs) are the main T-cell activators; their role in the chronic inflammatory process of nasal polyposis is still unclear. Methods: The regulation of DC subsets was analyzed in nasal polyp tissue from CRSwNP patients and compared to inferior turbinate tissue from healthy subjects. Tissue localization and expression of both plasmacytoid and myeloid DCs were assayed by means of immunohistochemistry and flow cytometry. Plasmacytoid DCs were also assayed by PCR, and tissue homogenates were assayed for various inflammatory markers. Results: The number of plasmacytoid (pDCs) and myeloid (mDCs) dendritic cells was significantly increased in nasal polyp tissue when compared to non-inflamed nasal mucosa. The number of pDCs, but not mDCs, was down-regulated in more severe cases (nasal polyps with asthma) and varied with the cytokine milieu. The amount of pDCs was significantly decreased in IL5+IFN gamma - nasal polyp tissue compared to tissues with high IFN gamma levels (IL5+IFN gamma+). Furthermore, levels of indoleamine 2,3-dioxygenase were increased in nasal polyp compared to inferior turbinate tissue and correlated negatively with the number of pDCs. Conclusions: There is an altered balance of pDC and mDC numbers in nasal polyp tissue. pDCs seem to be more susceptible to an inflammatory cytokine milieu and may play a crucial role in disease severity. (C) 2014 Elsevier GmbH. All rights reserved.