Gene expression analysis of airway epithelial cells exposed to flagellin via microarray

Airway epithelial cells (AEC) are critical components of the inflammatory and immune response during exposure to pathogens. AECs in monolayer culture and differentiated epithelial cells in air-liquid interface (ALI) represent two distinct and commonly used in vitro models, yet differences in their response to pathogens have not been investigated. In this study, we compared the transcriptional effects of flagellin on AECs in monolayer culture versus ALI culture using exon microarrays and RNAsequencing. We found that AECs cultured in monolayer and ALI have strikingly different transcriptional states at baseline. When challenged with flagellin, monolayer AEC cultures greatly increased transcription of numerous genes mapping to wounding response, immunity and inflammatory response. In contrast, AECs in ALI culture had an unexpectedly muted response to flagellin, both in number of genes expressed and relative enrichment of inflammatory and immune pathways. In conclusion, In vitro culturing methods have a dramatic effect on the transcriptional profile of AECs at baseline and after stimulation with flagellin. These differences suggest that epithelial responses to pathogen challenges are distinctly different in culture models of intact and injured epithelium. A total of ten independent microarray experiments were performed. Four micorarray experiments (n = 2 unstimulated, n = 2 stimulated with flagellin) were conducted using AECs grown in monolayer. Six microarray experiments (n =3 unstimulated, n = 3 stimulated with flagellin) were perfomerd using AECs grown in ALI cultures.