IL17A and influenza: coli and Enterococcus faecium [54]. Type I IFNs circulate via the bloodstream from the respiratory tract to the gut during influenza infection, and high levels of type I IFNs trigger IL-17 production leading to the production of several proinflammatory cytokines and chemokines [43]. These sequential events may allow opportunistic microorganisms to gain a foothold and even thrive in mucosal tissues [43].