Transcriptional profiling of nasal epithelium during natural colds in asthmatic subjects

Abstract

Rationale Although cold viruses precipitate most asthma exacerbations, the mechanisms leading to exacerbations rather than just colds are poorly understood. Transcriptional profiling of nasal mucosa may help identify genes related to exacerbations. Methods To determine the feasibility of measuring expression of a large number of genes in nasal epithelium, we scraped the nasal mucosa with Rhinoprobe during acute colds and at least 6 weeks later (baseline) in 25 episodes of colds (21 subjects, 17 with asthma). RNA was extracted using RNeasy kit and expression of 384 genes measured by two-step multiplex real-time RT-PCR. Gene expression levels were normalized to several housekeeping genes and analyzed using SAM (Significance Analysis of Microarrays) software. False discovery rate (FDR) was set at 5% or less, and magnitude of expression change was set to 2-fold or greater. Results Median FDR was 2.75%. We found 25 genes expressed more during acute colds than at baseline including ICAM-1, GM-CSF, G-CSF, IL-10, IL-10R, CCR1, CCR2, CCR5, eotaxin, and GRO1-3. The gene most significantly increased was endothelial cell-specific molecule-1 (ESM-1), a proteoglycan secreted by endothelial cells that inhibits LFA-1/ICAM-1 binding and may regulate lymphocyte migration. In addition, we found increase in genes related to generation of reactive oxygen species (NADPH oxidase p91 subunit, and glutaredoxin), co-stimulatory molecules (CD80 and ICOS), and ion channels (CLCA3 and SLC8A1, a Ca/Na exchanger). Conclusion Transcriptional signatures for a large number of genes in nasal mucosal samples can be used to monitor disease progression and to identify new genes related to virus-induced nasal inflammation and possibly asthma exacerbations.