Extracellular eosinophilic traps in association with Staphylococcus aureus at the site of epithelial barrier defects in severe airway inflammation

Publication date: Available online 17 February 2017
Source:Journal of Allergy and Clinical Immunology
Author(s): Elien Gevaert, Nan Zhang, Olga Krysko, Feng Lan, Gabriële Holtappels, Natalie De Ruyck, Hans Nauwynck, Shida Yousefi, Hans-Uwe Simon, Claus Bachert
BackgroundChronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by a Th2-biased eosinophilic inflammation. Eosinophils have been shown to generate so-called extracellular eosinophilic traps (EETs) under similar pathological conditions.ObjectiveOur aim was to investigate a possible link between EET formation and the presence of Staphylococcus aureus, an organism frequently colonizing the upper airways, at the human mucosal site of the disease.MethodsTissue slides were investigated for the presence of EETs and S. aureus, using immunofluorescent staining and PNA-fish assay respectively. An ex vivo human mucosal disease tissue model was used for artificial infection with S. aureus. Cell markers were analyzed using immunohistochemistry, luminex Multiplex assay, ELISA, PCR, immunobloting and linked to the presence of EETs.ResultsAbout 8.8 ± 4.8 % of the infiltrating eosinophils exhibited EETs in patient's nasal polyp tissues. The formation of EETs was associated with increased IL-5 (p < 0.05) and periostin (p < 0.05) tissue levels, and colonization with S. aureus (p < 0.05). Using an ex vivo human mucosal disease tissue model, EET formation was induced (4.2 ± 0.9 fold) upon exposure to S. aureus, but not to S. epidermidis. Eosinophils were shown to migrate (p < 0.01) towards S. aureus and entrap the bacteria both inside and outside the mucosal tissue. Blocking NAPDH oxidase activity, led to a complete inhibition (p < 0.05) of EET formation by S. aureus.ConclusionEosinophils are likely to be specifically recruited to and form EETs at sites of airway epithelial damage to protect the host from infections with S. aureus and possibly other microorganisms in CRSwNP.

Teaser

Eosinophils in nasal polyp tissue are likely to be recruited to sites of airway epithelial damage to protect the host against S. aureus infections by forming EETs.


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