Eosinophilic infiltration and Staphylococcus aureus colonization have both been associated with

chronic rhinosinusitis patients with polyps. However, the role and true significance of eosinophils

in upper airway inflammation is still poorly understood. Since their discovery and despite their role

in antibacterial defense, eosinophils have been considered as harmful cells responsible for tissue

damage. However, in the last decade there is a shift in this point of view, since more and more

additional, benign and regulating roles have been attributed to eosinophils.

Our previous work has shown that Staphylococcus aureus infection at the mucosal surface can

attract and trigger eosinophils to induce so called ‘xtracellular traps’to entrap the microorganism

in chronic rhinosinusitis patients with nasal polyps. In addition, preliminary data have

shown that eosinophilic products can interact with other immune cells. Therefore, the aim of the

proposed work is to gain further insight on the interactions of eosinophils and their products with

other immune cells and to understand the influence of S. aureus on these interactions. By the

study of these interactions and by identifying the key molecules in these processes we aim to

identify eosinophil phenotypes related to upper airway inflammation.