Effect of influenza A virus infection on pulmonary flora and chemokines CCL5 and CXCL10 in mice and intervention of Maxing Shigan Decoction / 中草药

ABSTRACT

Objective: To investigate the potential mechanism of Maxing Shigan Decoction (MSD) in the prevention and treatment of influenza virus infection by influencing pulmonary flora and expression of chemokines CCL5 and CXCL10 of mice. Method The infected mice model of influenza A virus was tested by intranasal inoculation. After 3 and 7 d of gavage or saline, the lung index and lung index inhibition rate were calculated. Pathological changes of lung tissue were detected by HE staining. The expression of CCL5 and CXCL10 in the lung tissue of mice was detected by immunohistochemistry and ELISA. The expression of CCL5 mRNA and CXCL10 mRNA in lung tissue of mice was detected by real-time fluorescence quantitative PCR (RT-PCR). The bacteria in lung tissue was sequenced by using the V3-V4 variable region of 16S rRNA, annotated and clustered. The alpha diversity, beta diversity and the species difference among groups were analyzed. The correlation of the expression of CCL5 and CXCL10 with the change of intestinal flora was also analyzed. Results: After 3 d of administration, the lung index of model group was significantly higher than normal group (P < 0.01) and drug group (P < 0.05, 0.01). Pulmonary inflammatory cell infiltration was obvious. The infiltration of pulmonary inflammatory cells in MSD group was significantly reduced, and the inhibition rate of lung index was similar to that in oseltamivir group. The value of IQA in lung injury was decreased significantly (P < 0.01). The expressions of CCL5 and CXCL10 in the lung tissue of the model control group were significantly higher than those of the normal control group (P < 0.01), and the expressions of CCL5 and CXCL10 in the oseltamivir group and the MSD were significantly lower than those in the model control group (P < 0.05, 0.01). The results of 16S rRNA gene sequencing showed the relative abundances of Bacteroides, Escherichia, and Proteus were increased, while that of Coprococcus was decreased in the model control group. In oseltamivir group and MSD group, the relative abundances of Bacteroides, Escherichia, and Proteus were significantly decreased, while the relative abundance of Coprococcus was increased. The results of alpha diversity showed that the ace index, Chao1 index, and Shannon index of each group were all higher than 0.05, and there was no difference in richness and diversity among groups. The results of beta diversity showed that there was no intersection of sample points among groups and difference in the composition of pulmonary flora among groups. Species among groups were significant differences. Spearman correlation analysis showed that the expression of CCL5 and CXCL10 was positively correlated with the abundance of Escherichia, Proteus, and Bacteroides, and negatively correlated with the abundance of Coprococcus. After 7 d of administration, there was no significant difference in the composition of pulmonary flora and the expression of CCL5 and CXCL10. Conclusion: MSD may improve the micro-ecological environment and immune microenvironment of the lung by promoting the growth of beneficial bacteria, and has a certain protective effect on the lung injury caused by influenza virus.