Nanoparticles divert monocytes away from the lungs to improve outcomes after influenza virus infection in aged mice

Older people exhibit dysregulated innate immunity to respiratory viral infections, including influenza and SARS-CoV-2, to increase morbidity and mortality. Nanoparticles are a potential practical therapeutic that could divert exaggerated innate immune responses away from the lungs during viral infection. However, such therapeutics have not been examined for effectiveness during respiratory viral infection, particular in aged hosts. Here, we employed a highly lethal model of influenza viral infection in vulnerable aged mice to examine the ability of biodegradable, cargo-free nanoparticles, designated ONP-302, to resolve innate immune dysfunction and improve outcomes during infection. We administered ONP-302 via intravenous injection to aged mice at day 3 post-infection when the hyperinflammatory innate immune response is already established. We found that ONP-302 treatment diverted tissue-damaging inflammatory monocytes from the lungs to the spleen without impacting viral clearance or reducing chemo-attractive signals in the infected lung. Importantly, cargo-free nanoparticles reduced lung damage and histological lung inflammation and improved gas exchange and, ultimately, the clinical outcomes in influenza-infected aged mice. ONP-302 improves outcomes in influenza-infected, vulnerable, aged mice. Thus, our study provides vital fundamental information concerning a practical therapeutic which, if translated clinically, could improve disease outcomes for vulnerable older patients suffering from respiratory viral infections. Supported by COUR Pharmaceuticals