Protease-activated receptor 2 activation of myeloid dendritic cells regulates allergic airway inflammationReport as inadecuate

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Respiratory Research

, 12:122

First Online: 01 December 2011Received: 16 June 2011Accepted: 21 September 2011


BackgroundA common characteristic of allergens is that they contain proteases that can activate protease-activated receptor PAR-2; however the mechanism by which PAR-2 regulates allergic airway inflammation is unclear.

MethodsMice wild type and PAR-2-deficient were sensitized using German cockroach GC feces frass, the isolated protease from GC frass, or through adoptive transfer of GC frass-treated bone marrow-derived dendritic cells BMDC and measurements of airway inflammation cellular infiltration, cytokine expression, and mucin production, serum IgE levels and airway hyperresponsiveness AHR were assessed. BMDC were cultured, treated with GC frass and assessed for cytokine production. PAR-2 expression on pulmonary mDCs was determined by flow cytometry.

ResultsExposure to GC frass induced AHR and airway inflammation in wild type mice; however PAR-2-deficient mice had significantly attenuated responses. To directly investigate the role of the protease, we isolated the protease from GC frass and administered the endotoxin-free protease into the airways of mice in the presence of OVA. GC frass proteases were sufficient to promote the development of AHR, serum IgE, and Th2 cytokine production. PAR-2 expression on mDC was upregulated following GC frass exposure, but the presence of a functional PAR-2 did not alter antigen uptake. To determine if PAR-2 activation led to differential cytokine production, we cultured BMDC in the presence of GM-CSF and treated these cells ex vivo with GC frass. PAR-2-deficient BMDC released significantly less IL-6, IL-23 and TNFα compared to BMDC from wild type mice, suggesting PAR-2 activation was important in Th2-Th17 skewing cytokine production. To determine the role for PAR-2 on mDCs on the initiation of allergic airway inflammation, BMDCs from wild type and PAR-2-deficient mice were treated in the presence or absence of GC frass and then adoptively transferred into the airway of wild type mice. Importantly, GC frass-stimulated wild type BMDCs were sufficient to induce AHR and allergic airway inflammation, while GC frass-stimulated PAR-2-deficient BMDC had attenuated responses.

ConclusionsTogether these data suggest an important role for allergen activation of PAR-2 on mDCs in mediating Th2-Th17 cytokine production and allergic airway responses.

List of abbreviationsAHRairway hyperresponsiveness

BMDCbone marrow-derived DC

ConAconcanavalin A

DCdendritic cell

GCGerman cockroach



MFImean fluorescent intensity


PARProtease activated receptor.

Electronic supplementary materialThe online version of this article doi:10.1186-1465-9921-12-122 contains supplementary material, which is available to authorized users.

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Author: Ian P Lewkowich - Scottie B Day - John R Ledford - Ping Zhou - Krista Dienger - Marsha Wills-Karp - Kristen Page


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