But B5 had no significant effect on the production of IL-22, which was different from our previous study [27], and this may be related to the difference in pathogenic bacteria; moreover, K. pneumoniae promoted IL-22 secretion, while APP inhibited IL-22 production in the lungs at 6 h after challenge, and B5 exhibited different immunomodulatory activities in different bacterial pneumonia. Here, IL22 is linked to bacterial pneumonia.