Staphylococcus aureus internalization in mast cells in nasal polyps: characterization of interactions and potential mechanisms

Hayes, Stephen M, Biggs, Timothy C, Goldie, Simon P, Harries, Philip G, Walls, Andrew F, Allan, Raymond N, Pender, Sylvia L F and Salib, Rami J (2019) Staphylococcus aureus internalization in mast cells in nasal polyps: characterization of interactions and potential mechanisms. The Journal of Allergy and Clinical Immunology, 145 (1), 147-159. (doi:10.1016/j.jaci.2019.06.013).

Abstract

BACKGROUND: Chronic rhinosinusitis (CRS) with nasal polyps is a common chronic condition. The exact cause of nasal polyps remains unknown. Recently, we made the novel observation of intracellular localization of Staphylococcus aureus within mast cells in nasal polyps.

OBJECTIVE: This follow-up study aimed to further characterize interactions between S aureus and mast cells in this setting and elucidate potential internalization mechanisms with particular emphasis on the role of staphylococcal enterotoxin B (SEB).

METHODS: A prospective study was performed using an explant tissue model with ex vivo inferior turbinate mucosa obtained from patients with chronic rhinosinusitis with nasal polyps (n = 7) and patients without CRS (n = 5). Immunohistochemistry was used to characterize S aureus uptake into mast cells and investigate the effects of SEB on this process. An in vitro cell-culture model was used to investigate mast cell-S aureus interactions by using a combination of fluorescent in situ hybridization, confocal laser scanning microscopy, scanning electron microscopy, transmission electron microscopy, and proliferation assays.

RESULTS: S aureus was captured by extracellular traps and entered mast cells through phagocytosis. Proliferating intracellular S aureus led to the expansion and eventual rupture of mast cells, resulting in release of viable S aureus into the extracellular space. The presence of SEB appeared to promote internalization of S aureus into mast cells.

CONCLUSION: This study provides new insights into the interactions between S aureus and mast cells, including the internalization process, and demonstrates a prominent role for SEB in promoting uptake of the bacteria into these cells.

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Contributors

Author: Simon P Goldie

Author: Andrew F Walls

Author: Sylvia L F Pender

Author: Rami J Salib

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