Osteopontin is critical to determine symptom severity of influenza through the regulation of NK cell population

Osteopontin (OPN) is involved in exacerbating various inflammatory diseases. A severe pulmonary inflammation is frequently found in lethal influenza A virus (IAV) infection. However, the function of OPN against the infection was poorly understood. Here, we demonstrate an importance of OPN on immune response and disease severity after IAV infection. We found that the expression level of OPN was increased in mice infected with IAV. The OPN knockout (KO) mice exhibited a severe pathological phenotype and the survival rate decreased after the lethal IAV infection, compared to the wild type mice, while the survival rate increased in OPN transgenic (Tg) mice. The population of natural killer (NK) cells significantly decreased in OPN KO mice at day 5 after the infection, whereas, it increased in OPN Tg mice. These results suggest that OPN plays an important role in host defense against IAV infection through the regulation of NK cell population.

► Osteopontin (OPN) is involved in the exacerbation of various inflammatory diseases.
► OPN KO mice exhibit severe phenotype against a lethal influenza A virus challenge.
► OPN Tg mice survive for long periods against a lethal influenza A virus challenge.
► OPN upregulates NK cell population after influenza A virus infection.
► OPN is crucial to activate early immune responses to influenza A virus infection.