Background: Allergic respiratory conditions have been associated with increased susceptibility to viral infection due to impaired interferon (IFN)-related immune responses, but the mechanisms for reinforcement of mucosal immunity against viral infection in allergic diseases are largely unknown.
Objectives: To determine whether IFN induction would be impaired in allergic nasal mucosa and to identify whether higher loads of influenza A virus (IAV) in allergic nasal mucosa could be controlled with IFN treatment.
Methods: Influenza A virus mRNA, viral titres and IFN expression were compared in IAV-infected normal human nasal epithelial (NHNE, N = 10) and allergic rhinitis nasal epithelial (ARNE, N = 10) cells. We used in vivo model of allergic rhinitis (BALB/c mice, N = 10) and human nasal mucosa from healthy volunteers (N = 72) and allergic rhinitis patients (N = 29) to assess the induction of IFNs after IAV infection.
Results: Influenza A virus mRNA levels and viral titres were significantly higher in ARNE compared with NHNE cells. IFN-β and IFN-λs were induced in NHNE and ARNE cells up to 3 days after IAV infection. Interestingly, induction of IFN-λs mRNA levels and the amount of secreted proteins were considerably lower in ARNE cells. The mean IFN-λs mRNA level was also significantly lower in the nasal mucosa of AR patients, and we found that recombinant IFN-λ treatment attenuated viral mRNA levels and viral titres in IAV-infected ARNE cells. In vivoAR mouse exhibited higher viral load after IAV infection, but intranasal inoculation of IFN-λ completely decreased IAV protein expression and viral titre in nasal mucosa of IAV-infected AR mouse.
Conclusion: Higher susceptibility of the allergic nasal mucosa to IAV may depend on impairment of type III IFN induction, and type III IFN is a key mechanistic link between higher viral loads and control of IAV infection in allergic nasal mucosa.
Keywords: allergic rhinitis; influenza A virus; nasal mucosa; type III interferon.
© 2017 John Wiley & Sons Ltd.