Regulation of murine sinonasal cilia function by microbial secreted factors

Background: Chronic rhinosinusitis is a multifactorial disease resulting in impaired mucociliary clearance. Recent literature suggests that different bacterial species are associated with varied disease severity. We examined the immediate effect of microbial secreted factors on sinonasal ciliary function. Methods: Murine primary sinonasal cultures were established in an air-liquid interface (ALI). Bacterial supernatants were isolated from H. influenza, S. pneumoniae, S. aureus, and P. aeruginosa cultures, as well as co-cultures of H. influenza/S. pneumoniae and S. aureus/P. aeruginosa. Controlling for pH and osmolarity, supernatants were administered at 50% concentration to the apical surface of the ALI culture. Basal ciliary beat frequency (CBF) was recorded for 20 minutes, at 5-minute intervals. Control groupswere treated with culture broth. At minimum, experiments were performed in triplicate. Stimulated CBF was recorded after mechanical stimulation via short bursts of pressurized air (55 mmHg). Results: All supernatants reduced basal CBF. S. pneumoniae and P. aeruginosa caused significant reduction in CBF at all time points, with the largest decrease of -46.3 ± 1.6% (p < 0.001) for S. pneumoniae and -27.1 ± 2.8% (p < 0.001) for P. aeruginosa. S. aureus caused the basal CBF to decline by-33.0 ± 2.8%(p<0.001)at5minutes, whichreversed by 20 minutes.Overall, H. influenza yielded the least change in CBF (-20.0 ± 2.8%, p < 0.002). Co-cultures (H. influenza/S. pneumoniae and S. aureus/P. aeruginosa) resulted in delayed CBF reduction compared with monocultures. P. aeruginosa also blunted stimulated CBF (p < 0.02). Conclusion: Results demonstrated acute decreases in murine sinonasal CBF after exposure to bacterial supernatants. Moreover, P. aeruginosa resulted in diminished ciliary stimulation capacity.