FIG 6.

Effect of endogenous and exogenous IL-22 in local and systemic bacterial loads in the context of influenza. (A) Role of endogenous IL-22 on secondary bacterial infection postinfluenza. Wild type (WT) or Il22^−/− mice were infected with 500 PFU of the H1N1 pandemic IAV strain. Seven days later, IAV-infected mice were challenged with S. pneumoniae (1 × 10³ CFU). (B) Effect of IL-22 supplementation on bacterial superinfection postinfluenza. At day 7 post-IAV infection, mice were i.n. inoculated with 5 μg of IL-22-Fc or an isotype control. After 16 h, mice were challenged with S. pneumoniae. (A and B) Doubly infected mice were sacrificed 30 h after S. pneumoniae challenge, and the number of CFU was determined in the lungs and spleens. Total CFU counts in each tissue are represented. The solid line corresponds to the median values. Results from a pool of two independent experiments (n = 10 to 12 mice) (A) or three independent experiments (n = 20 to 23 mice) (B) are shown. *, P < 0.05 (Mann-Whitney t test).