Abstract:

Objective To discuss the effect of Compound Rehmannia Granules on intestinal flora of the pneumonia model rats induced by Streptococcus pneumoniae （Spn） through 16s rRNA sequencing technology， and to clarify its potential mechanism. Methods A total of 30 rats were randomly divided into control group （normal rats）， model group （Spn-induced pneumonia rat models）， low dose of Compound Rehmannia Granules group （pneumonia rat models administered 1.75 g·kg^-1 Compound Rehmannia Granules by gavage）， medium dose of Compound Rehmannia Granules group （pneumonia rat models administered 3.50 g·kg^-1 Compound Rehmannia Granules by gavage）， and high dose of Compound Rehmannia Granules group （pneumonia rat model administered 7.00 g·kg^-1 Compound Rehmannia Granules by gavage）， with 6 rats in each group. The wet/dry weight （W/D） ratio of lung tissue and blood gas indexes were measured； HE staining was used to observe the pathomorphology and the degree of lung injury in lung tissue of the rats in various groups were assessed； kit assay was used to detect the bacterial load level and the levels of interleukin （IL）-6， IL-8， and IL-10 in bronchoalveolar lavage fluid （BALF） of the rats in various groups； 16s rRNA intestinal flora sequencing analysis was performed. Results Compared with control group， the arterial partial pressure of carbon dioxide （PaCO₂） of the rats in model group was significantly increased （P<0.05）， and the arterial partial pressure of oxygen （PaO₂） and oxygen saturation （SaO₂） were significantly decreased （P<0.05）； compared with model group， the PaCO₂ of the rats in low， medium， and high doses of Compound Rehmannia Granules groups was significantly decreased （P<0.05）， and the PaO? and SaO? were significantly increased （P<0.05）， showing a dose-dependent manner. The HE staining results showed no significant injury in lung tissue of the rats in control group； the cells in lung tissue of the rats in model group were arranged disorderly with massive inflammatory cell infiltration， and the alveolar wall capillaries were significantly dilated； compared with model group， the morphological damage of lung tissue of the rats in low， medium， and high doses of Compound Rehmannia Granules groups was improved. Compared with control group， the W/D value and pathological score of lung tissue of the rats in model group were significantly increased （P<0.05）； compared with model group， the W/D value and pathological scores of lung tissue of the rats in low， medium， and high doses of Compound Rehmannia Granules groups were significantly decreased （P<0.05）， showing a dose-dependent manner. Compared with control group， the bacterial load level in BALF of the rats in model group was significantly increased （P<0.05）； compared with model group， the bacterial load level in BALF of the rats in low， medium， and high doses of Compound Rehmannia Granules groups was significantly decreased （P<0.05）， showing a dose-dependent manner. Compared with control group， the levels of IL-6 and IL-8 in BALF of the rats in model group were significantly increased （P<0.05）， and the IL-10 level was significantly decreased （P<0.05）； compared with model group， the levels of IL-6 and IL-8 in BALF of the rats in low， medium， and high doses of Compound Rehmannia Granules groups were significantly decreased （P<0.05）， and the IL-10 level was significantly increased （P<0.05）， showing a dose-dependent manner. Compared with control group， the microbial abundance indicator（Chao1）， microbial diversity and evenness indicator（Shannon）， microbial dominance indicator （Simpson）， and observed species indicator （observed_species） of the rats in model group were significantly decreased （P<0.05）； compared with model group， the Chao1， Shannon， Simpson， and （observed_species） indices of the rats in low， medium， and high doses of Compound Rehmannia Granules groups were significantly increased （P<0.05）， showing a dose-dependent manner. Compared with control group， the relative abundance of Bacteroidetes in model group was decreased， the relative abundance of Firmicutes was increased， and the Firmicutes/Bacteroidetes ratio was significantly increased （P<0.05）； compared with model group， the relative abundances of Bacteroidetes in low， medium， and high doses of Compound Rehmannia Granules groups were increased， the relative abundance of Firmicutes was decreased， and the Firmicutes/Bacteroidetes ratio was significantly decreased （P<0.05）， showing a dose-dependent manner. At the family level， compared with control group， the relative abundances of Corynebacteriaceae， Staphylococcaceae， and Moraxellaceae in model group were significantly increased， while the relative abundances of Lactobacillaceae， Lachnospiraceae， and Akkermansiaceae were significantly decreased； compared with model group， the relative abundances of Corynebacteriaceae， Staphylococcaceae， and Moraxellaceae in low， medium， and high doses of Compound Rehmannia Granules groups were significantly decreased， and the relative abundances of Lactobacillaceae， Lachnospiraceae， and Akkermansiaceae were significantly increased. At the genus level， compared with control group， the relative abundances of Desulfovibrio and Facklamia in model group were significantly increased， and the relative abundances of Bifidobacterium and Ruminococcaceae were significantly decreased； compared with model group， the relative abundances of Desulfovibrio and Facklamia in low， medium， and high doses of Compound Rehmannia Granules groups were significantly decreased， and the relative abundances of Bifidobacterium and Ruminococcaceae were significantly increased. Conclusion Compound Rehmannia Granules can alleviate inflammation and lung injury in Spn-induced pneumonia rats， which may be related to the increase in the abundance and diversity of intestinal flora.

Key words: Pneumonia, 16s rRNA sequencing technology, Compound Rehmannia Granules, Streptococcus pneumoniae, Intestinal flora