Nasal immune gene expression in response to azelastine and fluticasone propionate combination or monotherapy

Background: The combination of the antihistamine azelastine (AZE) with the corticosteroid fluticasone propionate (FP) in a single spray, has been reported to be significantly more effective at reducing allergic rhinitis (AR) symptoms than treatment with either corticosteroid or antihistamine monotherapy. However, the biological basis for enhanced symptom relief is not known. This study aimed to compare gene expression profiles (760 immune genes, performed with the NanoString nCounter) from peripheral blood and nasal brushing/lavage lysate samples in response to nasal spray treatment.

Methods: Moderate/severe persistent dust mite AR sufferers received either AZE (125 μg/spray) nasal spray (n = 16), FP (50 μg/spray) nasal spray (n = 14) or combination spray AZE/FP (125 μg AZE and 50 μg FP/spray) (n = 14) for 7 days, twice daily. Self-reported symptom questionnaires were completed daily for the study duration. Gene expression analysis (760 immune genes) was performed with the NanoString nCounter on purified RNA from peripheral blood and nasal brushing/lavage lysate samples.

Results: In nasal samples, 206 genes were significantly differentially expressed following FP treatment; 182 genes downregulated (-2.57 to -0.45 Log2 fold change [FC]), 24 genes upregulated (0.49-1.40 Log2 FC). In response to AZE/FP, only 16 genes were significantly differentially expressed; 10 genes downregulated (-1.53 to -0.58 Log2 FC), six genes upregulated (1.07-1.62 Log2 FC). Following AZE treatment only five genes were significantly differentially expressed; one gene downregulated (-1.68 Log2 FC), four genes upregulated (0.59-1.19 Log2 FC). Immune gene changes in peripheral blood samples following treatment were minimal. AR symptoms improved under all treatments, but improvements were less pronounced following AZE treatment.

Conclusion: AZE/FP, FP, and AZE had diverse effects on immune gene expression profiles in nasal mucosa samples. The moderate number of genes modulated by AZE/FP indicates alternative pathways in reducing AR symptoms whilst avoiding extensive local immune suppression.