Functional Genomics of Human Bronchial Epithelial Cells Directly Interacting with Conidia of Aspergillus Fumigatus

Background: Aspergillus fumigatus (A. fumigatus) is a ubiquitous fungus which reproduces asexually by releasingabundant airborne conidia (spores), which are easily respirable. In allergic and immunocompromised individuals A.fumigatus can cause a wide spectrum of diseases, including allergic bronchopulmonary aspergillosis, aspergilloma andinvasive aspergillosis. Previous studies have demonstrated that A. fumigatus conidia are internalized by macrophagesand lung epithelial cells; however the exact transcriptional responses of airway epithelial cells to conidia are currentlyunknown. Thus, the aim of this study was to determine the transcriptomic response of the human bronchial epithelialcell line (16HBE14o-) following interaction with A. fumigatus conidia. We used fluorescence-activated cell sorting (FACS)to separate 16HBE14o- cells having bound and/or internalized A. fumigatus conidia expressing green fluorescentprotein from cells without spores. Total RNA was then isolated and the transcriptome of 16HBE14o- cells was evaluatedusing Agilent Whole Human Genome microarrays.Results: Immunofluorescent staining and nystatin protection assays demonstrated that 16HBE14o- cells internalized30-50% of bound conidia within six hrs of co-incubation. After FAC-sorting of the same cell culture to separate cellsassociated with conidia from those without conidia, genome-wide analysis revealed a set of 889 genes showingdifferential expression in cells with conidia. Specifically, these 16HBE14o- cells had increased levels of transcripts fromgenes associated with repair and inflammatory processes (e.g., matrix metalloproteinases, chemokines, andglutathione S-transferase). In addition, the differentially expressed genes were significantly enriched for Gene Ontologyterms including: chromatin assembly, G-protein-coupled receptor binding, chemokine activity, and glutathionemetabolic process (up-regulated); cell cycle phase, mitosis, and intracellular organelle (down-regulated).Conclusions: We demonstrate a methodology using FACs for analyzing the transcriptome of infected and uninfectedcells from the same cell population that will provide a framework for future characterization of the specific interactionsbetween pathogens such as A. fumigatus with human cells derived from individuals with or without underlying diseasesusceptibility.