Developed from Shegan Mahuang decoction, Xiaoning liquid can be used to treat asthmatic children which have their own physiological and pathological characteristics. Additionally, Xiaoning liquid plays a dual role in restoring the imbalanced gut microbiota. In this study, we investigated the relationship between intestinal flora and asthma with a TCM, Xiaoning liquid. Our results suggested that Xiaoning liquid can reduce the species and numbers of pathogenic bacteria and restored the intestinal microecology of asthmatic mice.
It has been found that the gut microbiota can guard the intra-gastrointestinal environment from foreign pathogens. The microbiota interacts with the host to dynamically regulate the gut physiology. As a disease invades the host, the gut microbiota is geared and immediately involved in sorts of biological processes that are intricately intertwined. According to the interpretation of TCM, a person’s lung and large intestine cooperate closely, which may explain the modern ‘lung-gut axis’ theory to some extent. Since the alveolar and intestinal epithelium arise from the endoderm, the airway and the intestine may present a functional similarity [31]. Many studies have verified the interaction between pulmonary and intestinal immunity [32–34].
According to Fig. 1, the microbiota in the control group, budesonide group and XN groups was more diverse than that in HC group, suggesting that the intestinal microbial diversity and distribution uniformity of asthma mice were increased after treatment, especially in the control group. Venn, PCA, PCoA and NMDS analysis showed that the numbers and sepecies of gut microbiota in asthmatic mice were different from those in HC group, and the changes in the control group were more obvious than those in the other three groups. Hierarchical clustering analysis and Unifrac clustering analysis showed an overlap between XN group and HC group.
Compared with HC group, taxonomic analysis showed that Staphylococci in asthmatic mice decreased and some Ruminococcacea increased significantly, which may be associated with the immune response of asthmatic mice. The pulmonary inflammation may disturb the immune system of intestinal mucosa, resulting in intestinal barrier dysfunction, microbiota imbalance, inherent bacterial reduction, and mass reproduction of opportunistic bacteria, foreign bacteria and passing bacteria. Relevant literature shows that Staphylococcus is vulnerable to changes in the micro-ecological environment [35]. Therefore, the asthma-disrupted intestinal microecology may inhibit the growth of normal staphylococcus in the present study. It has been found that mucin in the intestinal tract can be used as the binding site and nutrient source [36]. Inflammatory changes in the body can affect the immune response in intestinal mucosa. So the asthma-induced rise of mucus level may provide an ideal environment for the proliferation of bacteria in the present study. Besides, after modeling, the Bacteroidetes were the most abundant in the gut, followed by Firmicutes, Proteobacteria and Deferribacteres, which agrees with previous research results [37]. Shannon and Simpson (Table 1) detected that the microbial diversity in the budesonide and XN groups was greater than that in HC group. The present study also showed that the abundance and uniformity of intestinal flora increased, so did the ratio of Bacteroidetes to Firmicutes, all indicating that the opportunistic pathogens may arise from intestinal Bacteroidetes in the case of asthma.
Table 1
Diversity indices of the various groups
| Reads | OTU | ace | chao | coverage | shannon | simpson |
HC | 328614 | 583 | 599 (591,615) | 603 (591,629) | 0.999900 | 4.23 (4.23,4.24) | 0.0363 (0.036,0.0366) |
C | 278058 | 620 | 628 (623,639) | 631 (624,651) | 0.999928 | 4.64 (4.62,4.65) | 0.019 (0.0189,0.0191) |
B | 328614 | 594 | 602 (597,615) | 617 (602,659) | 0.999933 | 4.69 (4.69,4.7) | 0.0195 (0.0194,0.0196) |
X | 328614 | 602 | 612 (606,625) | 610 (605,625) | 0.999936 | 4.7 (4.7,4.71) | 0.0212 (0.021,0.0213) |
HC: healthy control group, C: control group, B: budesonide group, X: Xiaoning group |
We also found that after drug treatment, the diversity of gut microbiota in asthmatic mice decreased. The results of characteristic group analysis showed more pathogenic bacteria in the intestinal tract of asthmatic mice, especially in the control group. In budesonide group and XN group, a few pathogenic bacteria were found, but the gut flora was still dominated by normal. Staphylococcus, Escherichia-Shigella of XN group decreased significantly compared with HC group. Mucispirillum, abundant in the intestinal mucus layer, can regulate the expression of intestinal immunity-related genes in the case of inflammatory diseases, and its large-scale proliferation may trigger intestinal diseases [38]. Compared to the other three groups, Mucispirillum decreased significantly, suggesting that Xiaoning liquid could reduce the pathogenic and revive the probiotic bacteria in the gut, both supporting an intestinal micro-ecological balance.
In the present study, we did not detect the microflora in the mouse lung, so the interaction on the bacterial level between the lungs and the gut remains unclear, which should be resolved by more research.
In conclusion, Xiaoning liquid can reduce the species and numbers of pathogenic bacteria and restored the intestinal microecology of asthmatic mice. Xiaoning liquid has a positive effect on the function of gut microbiota.