Study On The Mechanism Of The Water Extract Of Elephantopus Scaber Linn.on Systemic Inflammation In Heat-stressed Mice Based On The Gut Microbiota

Hot weather occurs frequently everywhere,and the health problems induced by heat stress are increasing year by year.However,its pathogenesis has not been fully studied.There is no clear and efficient prevention and control plan.Correlational studies have shown that systemic inflammation can trigger a series of adverse reactions for heat stress.The gut microbiota plays an important role in systemic inflammation.However,its specific mechanism is not completely clear.Elephantopus scaber Linn is a kind of Chinese herbal medicine.In daily life,it is widely consumed as a remarkable soup supplement to relieve heat.However,relevant studies in heat stress for systemic inflammation have been limited.In this study,the water extract of Elephantopus scaber Linn(ESL)was used as the material.To explore the intervention effect of low(0.5 g/kg BW),medium(1.0 g/kg BW),and high(1.5 g/kg BW)doses of ESL are used on systemic inflammation in heat-stressed mice.The development of functional foods against heat stress lays the theoretical foundation.The main research contents and results are as follows:1.Using the mouse model of heat stress induced by a high temperature and high humidity environment.To study the effect of the water extract of Elephantopus scaber Linn on systemic inflammation by ELISA,limulus reagent chromogenic matrix,HE staining and Western blot.The result shows:(1)ESL can restore the food intake,promote weight gain and significantly reduce the temperature of the tail root of the heat-stressed model mice,and relieve the fear,tremor,spontaneous activity dim and frizzy hair etc physiological reactions of the mice during the heat stress period.It indicate that ESL can alleviate the adverse effects of heat stress.(2)ESL can increase the regularity of the jejunum,the ratio of villus height to crypt depth and the number of goblet cells in heat stress model mice,and can also promote the expression of colonic tight junction proteins Claudin-1 and Occludin.At the same time,it can protect the integrity of the intestinal barrier.Low,medium,and high doses of ESL can reduce the inflammatory marker TNF-? in the serum of heat stress model mice by 54.5%,51.8% and 44.6%,respectively,and the inflammatory factor LPS by 61.5% and 54.5%,and 75%,respectively,basically restored to the level of the blank control group.It shows that ESL can protect the integrity of the intestinal barrier structure of heat stress model mice,reduce the large amount of LPS into the blood circulation,and play a role in alleviating the systemic inflammation induced by heat stress.2.Using 16 Sr DNA high-throughput sequencing and bioinformatics technology to study the effect of ESL on the structure and function of the gut microbiota in heatstressed mice.The results show:(1)The low-dose ESL can significantly increase the species richness and diversity of the gut microbiota reduced by heat stress,which is beneficial to the structure and function of the gut microbiota in heat-stressed mice(2)The low-dose ESL can significantly increase the abundance of the intestinal barrier protection bacteria : Akkermansia and Lactobacillus(P<0.05)which directly enhance the integrity of the intestinal barrier;increase the SCFAs-producing bacteria(Allobaculum,Oscillospira and Faecalibacterium,etc.)which increase the level of metabolites SCFAs and indirectly maintain the stability of the intestinal microecology;and directly reduce LPS by inhibiting the abundance of Stenotrophomonas,Acinetobacter and Achromobacter and other gram-negative bacteria and harmful bacteria which directly reduce the LPS content,thereby alleviating the systemic inflammatory response caused by heat stress.(3)Based on the analysis of the third-level KEGG metabolic pathways of the gut microbiota,ESL can reduce genes related lipopolysaccharide biosynthesis and increase the biosynthesis of SCFAs and tryptophan metabolism in heat stress model mice,alleviating systemic inflammation caused by heat stress.3.Using the GC-MS method to study the effect of ESL on the short-chain fatty acids in heat stress model mice and its correlation with the gut microbiota and inflammatory level.The results show:(1)ESL can significantly increase the content of acetic acid,propionic acid,Nbutyric acid and isobutyric acid in heat stress model mice,and reduce the content of Nvaleric acid.It indicats that ESL has an intervening effect on short-chain fatty acids.(2)There is a significant correlation between the gut microbiota and short-chain fatty acids,as well as between short-chain fatty acids and inflammatory levels.It is mainly manifested in the significant positive correlation between N-butyric acid and SCFAs-producing bacteria:Allobaculum,Oscillospira,Faecalibacterium.However,Nvaleric acid was significantly negatively correlated with Oscillospira and Clostridium.Acetic acid,propionic acid,N-butyric acid and isobutyric acid were significantly negatively correlated with TNF-?,while N-valeric acid was significantly positively correlated with IL-1?.It shows that ESL can affect the metabolism of short-chain fatty acids in heat stress model mice,which is related to the changes of the gut microbiota,thereby intervening systemic inflammation.4.Using the LC-MS method to study the effect of ESL on the neurotransmitter in heat stress model mice and its association with the gut microbiota.The results show:(1)ESL can significantly increase the content of the neurotransmitters:?-aminobutyric acid,5-HT and epinephrine produced by the metabolism of the gut microbiota,and reduce the content of glutamate.It indicates that ESL has an intervening effec on neurotransmitters.(2)There is a significant correlation between the gut microbiota and neurotransmitters,as well as between neurotransmitters and inflammatory levels.It is mainly manifested in the significant positive correlation between 5-HT and Bacteroides and Oscillospira(P<0.05);?-aminobutyric acid was significantly positively correlated with Lactobacillus and Allobaculum(P<0.05);Glutamic acid was significantly positively correlated with Achromobacter(P<0.05);5-HT was negatively correlated with TNF-? and LPS,while positively correlated with IL-10.;?-aminobutyric acid was significantly negatively correlated with TNF-? and LPS;and glutamate was significantly negatively correlated with IL-10.It shows that ESL can affect the neurotransmitter metabolism in heat stress model mice,which is related to the changes of the gut microbiota,thereby alleviating the physiological behavior and systemic inflammation level in heat stress model mice.