Comprehensive Gene Expression Signature Using RNA-Seq in Airways of Mouse Model of Severe Asthma with Fungal Sensitization

Abstract

<b><i>Introduction:</i></b> Inhalation of fungal allergens induces airway epithelial damage following airway inflammation and excessive mucus secretion, which can lead to severe asthma with fungal sensitization (SAFS). Comprehensive gene expression analysis in <i>Alternaria</i>-exposed mouse airways, a model of SAFS, has not been conducted. <b><i>Methods:</i></b> BALB/c mice received intranasal administration of <i>Alternaria</i> extract or phosphate-buffered saline twice a week for 6 weeks. Lung sections and bronchoalveolar lavage fluid were obtained to assess airway inflammation. RNA-Seq in the central airway was performed, and gene ontology (GO) analysis and gene set enrichment analysis (GSEA) were conducted for pathway analyses. An in vitro experiment using human airway epithelial cell 16HBE14o- was performed to validate the RNA-Seq findings. <b><i>Results:</i></b> Eosinophilic airway inflammation with mucus overproduction and airway remodeling was observed in mice exposed to <i>Alternaria</i>. RNA-Seq analysis revealed 403 upregulated and 108 downregulated genes in airways of <i>Alternaria-</i>exposed mice. In GO analysis, the functions of immunoglobulin (Ig) receptor binding, Ig production, inflammatory response, and T-cell activation were upregulated, while those of keratinization and defense response to other organisms were downregulated. GSEA revealed positive enrichment in T-cell receptor complex, immunological synapse, antigen binding, mast cell activation, and Ig receptor binding, and negative enrichment in keratinization and cornification in <i>Alternaria</i>-exposed mice relative to control. <i>Alternaria</i> exposure to 16HBE14o- cells validated the downregulation of epithelial keratinization-related genes, including <i>SPRR1A</i>, <i>SPRR1B</i>, and <i>KRT6B</i>. <b><i>Conclusion:</i></b> RNA-Seq analysis showed that <i>Alternaria</i> exposure induced inflammatory response and impaired defense mechanisms in mice airway epithelium, which might be therapeutic targets for SAFS.