Chronic rhinosinusitis (CRS) is a common chronic respiratory condition, frequently associated with asthma and affecting the majority of cystic fibrosis (CF) patients. Pseudomonas aeruginosa infections and biofilms have been implicated in recalcitrant CRS. One of the mechanisms of action for bacteria in CRS and CF is mucosal barrier disruption by secreted products that contributes to the inflammation. However, the role of biofilm and planktonic forms of P. aeruginosa in this process is not known. The aim is to determine the effect of P. aeruginosa exoproteins isolated from CF and non-CF CRS patients on the mucosal barrier.
Exoproteins from 40 P. aeruginosa isolates were collected in planktonic and biofilm form and applied to air-liquid interface (ALI) cultures of primary human nasal epithelial cells (HNECs). Mucosal barrier integrity was evaluated by transepithelial electrical resistance (TEER), passage of FITC-dextrans, and immunofluorescence of tight junction proteins. Cytotoxicity assays were performed to measure cell viability and IL-6 ELISA was carried out to evaluate pro-inflammatory effects.
Planktonic exoproteins from 20/40 (50%) clinical isolates had a significant detrimental effect on the barrier and significantly increased IL-6 production. Barrier disruption was characterised by a reduced TEER, increased permeability of FITC-dextrans and discontinuous immunolocalisation of tight junction proteins and was significantly more prevalent in isolates harvested from patients with comorbid asthma (p<0.05).
Exoproteins from planktonic P. aeruginosa clinical isolates from asthmatic CRS patients have detrimental effects on the mucosal barrier and induce IL-6 production potentially contributing to the mucosal inflammation in CRS patients.

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