Baicalin Inhibits Influenza A Virus Infection via Promotion of M1 Macrophage Polarization
Ping Geng, Haiyan Zhu, Wei Zhou, Chang Su, Mingcang Chen, Chenggang Huang, Chengjie Xia, Hai Huang, Yiou Cao, Xunlong Shi
Abstract
Background and Aims: The natural compound Baicalin (BA) possesses potential anti-influenza virus activity. However, whether or not macrophage is involved in baicalin’s anti-viral effects and the underlying mechanisms remain unclear, which would be investigated in this study. Methods: In H1N1 A virus-infected mice and cells, macrophage recruitment, functional phenotype (M1/M2), and cell metabolism were carried out by flow cytometry, qRT-PCR, immune-fluorescence, Transwell system, and GC-MS based metabolomics Results: BA reduced approximately 90% recruitment of macrophage (CD11b+/F480+), meanwhile increased the proportion of M1 polarized macrophages in the bronchoalveolar lavage fluid (BALF) of infected mice. BA-stimulated macrophage M1 phenotype shift was further verified by detecting the macrophage M1 polarization signals (CD86 positive, iNOS positive, TNF-α, and iNOS/Arg-1 bias) in vitro cell systems (Ana-1 and primary peritoneal macrophage cells). Meanwhile, the activated IFN signals (upregulated IFN-β and IRF-3), apparent IL-1β cleavage, inhibited influenza virus replication (M gene), and discriminative cellular metabolic responses occurred in BA-treated cells. Conclusion: Baicalin triggered macrophage M1 polarization, IFN signals, and other cellular reactions, which were beneficial for fighting against H1N1 A virus infection.