Epithelial permeability alterations in an in vitro air-liquid interface model of allergic fungal rhinosinusitis.

Background: Chronic rhinosinusitis (CRS) is an inflammatory upper-airway disease with numerous etiologies. Patients with a characteristic subtype of CRS, allergic fungal rhinosinusitis (AFRS), display increased expression of T helper 2 (Th2) cytokines and antigen-specific immunoglobulin E (IgE). Various sinonasal inflammatory conditions are associated with alterations in epithelial barrier function. The aim of this study was to compare epithelial permeability and intercellular junctional protein expression among cultured primary sinonasal cells from AFRS patients vs noninflammatory controls.

Methods: Epithelial cells isolated from paranasal sinus mucosa of AFRS and noninflammatory control patients were grown to confluence on permeable supports and transitioned to air-liquid interface (ALI). Transepithelial resistance (TER) was measured with a horizontal Ussing chamber to characterize the functional permeability of each cell type. After TER recordings were complete, a panel of intercellular junctional proteins was assessed by Western blot and immunofluorescence labeling followed by confocal microscopy.

Results: After 12 samples were measured from each group, we observed a 41% mean decrease in TER in AFRS cells (296 ± 89 ohms × cm(2) ) compared to control (503 ± 134 ohms × cm(2) , p = 0.006). TER deficits observed in AFRS were associated with decreased expression of the tight junction proteins occludin and junctional adhesion molecule-A (JAM-A), and increased expression of a leaky tight junction protein claudin-2.

Conclusion: Cultured sinonasal epithelium from AFRS patients displayed increased epithelial permeability and altered expression of intercellular junctional proteins. Given that these cells were not incubated with inflammatory cytokines in vitro, the cultured AFRS epithelial alterations may represent a retained modification in protein expression from the in vivo phenotype.