The interferon-λ (IFN-λ)-regulated innate immune responses in the airway expand our understanding toward antiviral strategies against influenza A virus (IAV). The application of IFN-λ as mucosal antiviral therapeutic is still challenging, and advanced research will be necessary to achieve more efficient delivery of recombinant IFN-λs to the damaged respiratory mucosa. In this study, we examine the capability of IFN-λ to stimulate the innate immune response, promoting the swift elimination of IAV in the lungs. Additionally, we develop IFN-λ-loaded nanoparticles incorporated into pulmonary surfactant for inhalation therapy aimed at treating lung infections caused by IAV. We found that inhaled delivery of IFNλ-PSNPs significantly restricted IAV replication in the lungs from 3 days after infection (dpi), and IAV-caused lung histopathologic findings were completely improved in response to IFNλ-PSNPs. More significant and rapid attenuation of viral RNA was observed in the lung of mice with inhaled delivery of IFNλ-PSNPs compared to mice with recombinant IFN-λs. Inhalation treatment of IFNλ-PSNPs to IAV-infected mice can result in the increase of monocyte frequency in concert with restoration of T and B cells composition. Furthermore, the transcriptional profiles of monocytes shifted toward heightened IFN responses following IFNλ-PSNP treatment. These results imply that IFN-λ could serve as a robust inducer of innate immunity in the lungs against IAV infection, and inhalation of IFN-λs encapsulated in PSNPs effectively resolves lung infections caused by IAV through rapid viral clearance. PSNPs facilitated improved delivery of IFN-λs to the lungs, triggering potent antiviral immune responses upon IAV infection onset.
Keywords: influenza A virus; inhalation therapy; interferon-λ; nanoparticle; pulmonary surfactant.