MUC5AC and colitis: The data indicate that the influenza virus markedly decreased the expression of Muc2, while QFYD restored the expression of Muc2. Muc2 mucin plays a key role in protecting the gut barrier, maintaining microbiota homeostasis (Liu et al., 2020), and preventing colitis (Van der Sluis et al., 2006; Leon-Coria et al., 2021).