Chaiqin Qingning Capsule Inhibits Influenza Virus Infection and Inflammation In Vitro and In Vivo

BACKGROUND: Chaiqin Qingning Capsule (CQ-C) is a traditional Chinese medicine (TCM) formula commonly used to treat respiratory infectious diseases in China. The aim of this study was to detect the effect and mechanism of CQ-C treated with influenza virus in vitro and vivo. METHODS: The cytotoxicity and antiviral activity of CQ-C in vitro was determined by methyl thiazolyl tetrazolium (MTT) assay. The regulation of CQ-C on cytokine/chemokine expression was evaluated using RT-qPCR. In addition, the effect of CQ-C on the pathway protein, NF-κB, and its phosphorylation level was verified by western blotting. After virus inoculation, BALB/c mice were administered with CQ-C of different concentrations for 7 days. Body weight, viral titer, lung pathology, and mortality of the mice were measured, and the level of inflammatory cytokines was also examined using real-time RT-qPCR. RESULTS: CQ-C inhibited the proliferation of influenza virus of various strains in vitro, with the 50% inhibitory concentration (IC50) ranging from 49 to 59 µg/mL. CQ-C downregulated virus-induced gene expression of IL-6, TNF-α, CXCL8, CXCL10, CCL5, and COX-2 in a dose-dependent manner in A549 cells. Also, CQ-C inhibited the expression of NF-κB protein of the signaling pathway. Moreover, a decrease of the lung index and mortality of mice was observed in the CQ-C (1 g/kg/d) group. The related cytokine/chemokine expression was also decreased in the early stages of infection in the mRNA level. CONCLUSION: As a clinically applied Chinese prescription, our study shows that CQ-C has a wide range of effects on several influenza viruses. Moreover, CQ-C could play an important role in anti-influenza activity and anti-inflammation in vitro and in vivo. Thus, CQ-C may be a promising treatment option for influenza.