Impact of primary influenza infection on the immune response to secondary bacterial infection in aged mice

摘要

Background: Increased susceptibility of older populations to secondary bacterial pneumonia-like infections following influenza infection has been well documented.1 Recent evidence in mouse models suggests that this increased risk from secondary bacterial infection occurs through a desen-sitization of the innate immune response.2 This recent finding, however, does not account for potential differences in immune responsiveness due to age. Materials and methods: To address this parameter, we used three age groups (aged, adult, and young mice) to evaluate the role of age in influenza-mediated vulnerability to secondary bacterial challenge with Pseudomonas aeruginosa. All mice were evaluated for multiple parameters including: (i) survival; (ii) lung bacterial load; (iii) total lung protein content; (iv) immune cell infiltration; (v) cytokine/chemokine expression; and (vi) toll-like receptor (TLR) RNA expression profiles.