Effects of different principles of Traditional Chinese Medicine treatment on TLR7/NF-κB signaling pathway in influenza virus infected mice.

Background: Influenza virus is a single-stranded RNA virus that causes influenza in humans and animals. About 600 million people around the world suffer from influenza every year. Upon recognizing viral RNA molecules, TLR7 (Toll-like receptor) initiates corresponding immune responses. Traditional Chinese Medicines (TCMs), including Yinqiao powder, Xinjiaxiangruyin and Guizhi-and-Mahuang decoction, have been extensively applied in clinical treatment of influenza. Although the therapeutic efficacy of TCMs against influenza virus in vivo was reported previously, its underlying mechanisms are not clearly understood. This study aimed to investigate the immunological mechanisms in the treatment of influenza virus infected mice with three Chinese herbal compounds as well as the effect on TLR7/NF-κB signaling pathway during recovery.

Methods: Wild type and TLR7 KO C57BL/6 mice were infected with influenza virus FM1 and then treated with three TCMs. The physical parameters of mice (body weight and lung index) and the expression levels of components in TLR7/NF-κB signaling pathway were evaluated.

Results: After viral infection, Guizhi-and-Mahuang decoction and Yinqiao powder showed better anti-viral effect under normal condition. Compared to the viral control group, expression levels of TLR7, MyD88, IRAK4 and NF-κB were significantly reduced in all treatment groups. Furthermore, the three TCM treatment groups showed poor therapeutic efficacy and no difference in viral load compared to the viral control group in TLR7 KO mice.

Conclusion: Our study indicated that Guizhi-and-Mahuang decoction and Yinqiao powder might play a crucial role of anti-influenza virus by regulating TLR7/NF-κB signal pathway.