Proteomic analysis of the airway surface liquid: modulation by proinflammatory cytokines

Abstract

The airway surface is covered by a fluid, the airway surface liquid, interposed between the mucous layer and the epithelium. The airway surface liquid contains proteins, secreted by different cell types, that may have pro-/anti-inflammatory or bactericidal functions or have a role in the mucociliary clearance. We have used a proteomics approach to identify the proteins secreted by an isolated in vitro model of human airway epithelium, at resting and under proinflammatory conditions, as a strategy to define the factors involved in epithelial barrier function. To this aim, we have analyzed the airway surface liquid from human bronchial epithelial cells grown as polarized monolayers in the presence and absence of inflammatory stimuli such as IL-4, IL-1β, TNF-α, and IFN-γ. Two-dimensional electrophoresis followed by mass spectrometry analysis has allowed the identification of ∼175 secreted protein spots, among which are immune-related proteins, structural proteins, an actin severer, some protease inhibitors, and a metalloproteinase. Comparisons between treated and untreated conditions have shown that the expression of several proteins was significantly modified by the different cytokines. Our results indicate that the surface epithelium is an active player in the epithelial barrier function and that inflammatory conditions may modulate protein secretion.

Lung Proteomics in Intensive Care

“…Proteomic analysis of airway surface liquid in a cytokine-stimulated human bronchial epithelial cell monolayer model yielded many candidate biomarkers among which gelsolin was considered the most promising [28].…”

Capillary electrophoresis analysis of biofluids with a focus on less commonly analyzed matrices

“…This approach can yield ASF proteins in hundreds of microgram quantities, e.g. for proteomic studies [39]. However, there are limitations to in vitro studies and so it is also necessary to sample ASF in vivo.…”

Localization and Functional Characterization of Pulmonary Bovine Odorant-Binding Protein

“…A diverse array of proteins and small peptides accumulate in this fluid and function to maintain homeostasis. 5,20,30 We investigated the expression and function of OBP, confirming pulmonary expression and demonstrating a potential anti-inflammatory role by blocking macrophage-induced neutrophil migration.…”