RESUMO
During influenza A virus (IAV) infection, it is unclear whether type I interferons (IFNs) have defensive antiviral effects or contribute to immunopathology in smokers. We treated nonsmoking (NS) and cigarette smoke (CS)-exposed mice intranasally with early (prophylactic) or late (therapeutic) IFN-ß. We compared the mortality and innate immune responses of the treated mice following challenge with IAV. In NS mice, both early and late IFN-ß administration decreased the survival rate in mice infected with IAV, with late IFN-ß administration having the greatest effect on survival. In contrast, in CS-exposed mice, early IFN-ß administration significantly increased survival during IAV infection while late IFN-ß administration did not alter mortality. With regards to inflammation, in NS mice, IFN-ß administration, especially late administration, significantly increased IAV-induced inflammation and lung injury. Early IFN-ß administration to CS-exposed mice did not increase IAV-induced inflammation and lung injury as occurred in NS mice. Our results demonstrate, although IFN-ß administration worsens the susceptibility of NS mice to influenza infection with increased immunopathology, early IFN-ß administration to CS-exposed mice, which have suppression of the intrinsic IFN response, improved outcomes during influenza infection.
