Sinonasal epithelial cell response to Staphylococcus aureus burden in chronic rhinosinusitis.

IMPORTANCE

Chronic rhinosinusitis (CRS) is an inflammatory disorder of the nose and paranasal sinuses. Staphylococcus aureus is increasingly linked with CRS exacerbations. Little is known about how bacteria activate inflammatory pathways that contribute to CRS.

OBJECTIVE

To develop an in vitro coculture system to explore how infection with S aureus stimulates innate immune responses of sinonasal epithelial cells (SNECs).

DESIGN, SETTING, AND PARTICIPANTS: Sinonasal epithelial cells were collected from 13 patients during endoscopic sinus surgery and grown in culture at the air-liquid interface from July 2014 through December 2014.

INTERVENTIONS

Differentiated SNECs from control individuals, patients with CRS with nasal polyps (CRSwNPs), and patients with CRS without nasal polyps (CRSsNPs) were infected with S aureus at 3 different concentrations for 24 hours.

MAIN OUTCOMES AND MEASURES

Growth of S aureus and viability of SNECs were measured. Expression of inflammatory markers and innate immune genes was measured by reverse transcription-polymerase chain reaction. Basal secretion of interleukin 8 was determined by enzyme-linked immunosorbent assay.

RESULTS

Cultured SNECs from patients with CRSsNPs demonstrated a significant increase (P < .05) in expression of interleukin 8 (23-fold to 82-fold) and tumor necrosis factor (11-fold to 61-fold) at all the tested concentrations of S aureus. Control or CRSwNP SNECs demonstrated a significant increase (P < .05) in expression of interleukin 8 (47-fold and 50-fold, respectively) and tumor necrosis factor (106-fold and 58-fold, respectively) at the higher inoculum of S aureus. Basal secretion of inflammatory markers correlated with expression changes. No significant changes in expression were observed for the helper T cell, subtype 2, inflammatory mediators tested.

CONCLUSIONS AND RELEVANCE

In this study, we developed a model to study early innate immune-mediated changes in SNECs cocultured at an air-liquid interface with bacteria. We also demonstrated that bacterial burden can be detected by SNECs in the absence of adaptive immune-mediated responses. The CRSsNP SNECs are more sensitive to S aureus burden than control or CRSwNP SNECs. Future studies will further develop this infection model and explore the SNEC innate immune response to bacteria.