Are biofilms associated with an inflammatory response in chronic rhinosinusitis?

Abstract

Background: Bacterial biofilms have been identified on the sinonasal mucosa of patients with chronic rhinosinusitis (CRS) but also on control samples. Their role in the disease pathogenesis is unproven. The objective of this study was to further evaluate the role of biofilms in CRS by assessing whether they are associated with an inflammatory response. Methods: Mucosal samples were collected from 18 patients with CRS and 7 normal subjects. Bacteria on the mucosal surface were identified by Gram stain. Immune cells were identified by Giemsa stain and immunohistochemistry (IHC). The number of local immune cells was recorded beneath areas of the mucosal surface both colonized with and free from bacteria. Results: In CRS patients, biofilms that were directly opposed to a disrupted epithelial layer were associated with more T lymphocytes (p = 0.01), and more macrophages (p = 0.003) than areas of mucosa without bacteria present. Biofilms associated with but not directly opposed to the epithelium were not associated with raised numbers of immune cells. Conclusion: Not all surface bacterial colonies are associated with a particular inflammatory response in CRS. Biofilms adherent to a disrupted epithelial layer are associated with higher numbers of immune cells and therefore appear to have a role in the pathogenesis of CRS.