Effects of Xinjiaxiangruyin on the TLR7 pathway in influenza virus-infected lungs of mice housed in a hygrothermal environment

Abstract

Background: To investigate the effects and immunological mechanisms of the traditional Chinese medicine Xinjiaxiangruyin on controlling influenza virus (FM1 strain) infection in mice housed in a hygrothermal environment. Methods: Mice were housed in normal and hygrothermal environments, and intranasally infected with influenza virus (FM1). A high-performance liquid chromatography fingerprint of Xinjiaxiangruyin was used to provide an analytical method for quality control. Real-time quantitative polymerase chain reaction (RT-qPCR) was used to measure messenger RNA expression of Toll-like receptor 7 (TLR7), myeloid differentiation primary response 88 (MyD88), and nuclear factor-kappa B (NF-κB) p65 in the TLR7 signaling pathway and virus replication in the lungs. Western blotting was used to measure the expression levels of TLR7, MyD88, and NF-κB p65 proteins. Flow cytometry was used to detect the proportion of Th17/T-regulatory cells. Results: Xinjiaxiangruyin effectively alleviated lung inflammation in C57BL/6 mice in hot and humid environments. Guizhimahuanggebantang significantly reduced lung inflammation in C57BL/6 mice. The expression of TLR7, MyD88, and NF-κB p65 mRNA in lung tissue of WT mice in the normal environment, GZMHGBT group was significantly lower than that in the model group (P < 0.05). In WT mice exposed to the hot and humid environment, the expression levels of TLR7, MyD88, and NF-κB p65 mRNA in the XJXRY group were significantly different from those in the virus group. The expression levels of TLR7, MyD88, and NF-κB p65 protein in lung tissue of WT mice exposed to the normal environment, GZMHGBT group was significantly lower than those in the model group. In WT mice exposed to hot and humid environments, the expression levels of TLR7, MyD88, and NF-κB p65 protein in XJXRY group were significantly different from those in the virus group. Conclusion: Guizhimahuanggebantang demonstrated a satisfactory therapeutic effect on mice infected with the influenza A virus (FM1 strain) in a normal environment, and Xinjiaxiangruyin demonstrated a clear therapeutic effect in damp and hot environments and may play a protective role against influenza through downregulation of the TLR7 signal pathway.