Effects Of Inulin On Gut Microbiota And Immune Function Of Macrophages

Probiotics play a vital role in improving human immunity and host health.Inulin,as the most deeply studied probiotics,plays an important role in regulating intestinal flora,anti-inflammation and improving immunity.Inulin can directly or indirectly regulate the composition and balance of intestinal microbes,promote the production of bioactive metabolites,such as short chain fatty acids,amino acids,peptides and sulfur compounds,act on intestinal epithelial cells and participate in the regulation of immune cells and cytokines,inhibit the spread of pathogens,and enhance the host immune response.he structure of inulin,especially its degree of polymerization(DP),can significantly affect its biological activity.The biological activity of inulin with different degree of polymerization,such as inulin with low degree of polymerization,has better solubility.At the same time,the regulation of inulin with high degree of polymerization is more prominent.However,there are few studies on the phagocytosis of intestinal flora and macrophages by inulin.therefore,this topic takes inulin of DP?23 as the research object,using in vitro anaerobic fermentation model and cell model to reveal the effect of inulin on human intestinal microecology and macrophage immune function.to provide further scientific basis for elucidating the probiotic nature of inulin.In the first part,the effect of inulin on the abundance and structure of intestinal flora was studied by anaerobic fermentation model in vitro.Therefore,the first part of the experiment,in vitro intestinal anaerobic fermentation model to explore the effect of inulin intervention on the composition and diversity of human intestinal flora,collect healthy human fecal samples for in vitro anaerobic fermentation,collect samples at different time points,extract dna,and carry out 16 S r DNA V3-V4 sequencing.The second part,many studies have shown that inulin can enhance the immune function of natural killer cells(NK cells)or T cells,but there are few studies on the immune function of macrophages.Macrophages have phagocytosis,sterilization,antigen transmission and immunomodulation.to elucidate the effect of inulin used in this experiment on macrophage immune function,a classical in vitro inflammatory model was established based on mouse mononuclear macrophage leukemia cells Raw264.7,and macrophages were infected with mycobacterium pubis.the effects of inulin on the gene expression levels of proinflammatory factors,anti-inflammatory factors,inflammatory mediators and macrophage phagocytosis of macrophages in inflammatory models were investigated to evaluate the regulatory effects of different doses of inulin on macrophage immune response and phagocytosis.Results.In vitro intestinal anaerobic fermentation model was used to study the effect of inulin on intestinal flora.The results showed that inulin intervention could up-regulate the relative abundance of beneficial bacteria such as Actinomycetes and Bifidobacterium,and down-regulate the relative abundance of Enterobacter.It is helpful to maintain the dynamic balance of intestinal flora.In addition,inulin intervention can lead to the decline of intestinal flora diversity,which may be due to the probiotic function of inulin.From the structural analysis,inulin has obvious regulatory effect on the composition of species.PCA the analysis of experimental results,the composition of inulin is located in different quadrants and the structure of intestinal flora changes.These are positive signs for the human body.According to this experiment,the inulin intervention of DP?23 can change the composition of intestinal flora and produce probiotic effect in healthy people,and it is proved that in vitro intestinal anaerobic fermentation model can be used as a method to study the interaction between functional food and intestinal microbes.The low,medium and high inulin doses were determined to be 0.25mg/m L ?0.5mg/m L and 0.75 mg/m L.in cell model pre-experiment the low,medium and high concentrations of inulin were found to affect the gene expression level of IL-6?IL-10?IL-1??TNF-??COX-2?i NOS in vitro induced inflammatory model experiments of lipopolysaccharide(LPS),indicating that inulin can regulate the immune response of the body.The phagocytosis efficiency,cytokines and secretion level of inflammatory mediators of the same infection complex number(MOI)of macrophages were detected without dose of inulin pretreatment.When the dose of inulin was 0.25 mg/m L?0.5mg/m L,the phagocytosis efficiency of macrophages was significantly improved,and the phagocytosis efficiency was the largest at 0.5 mg/ml.furthermore,0.25 mg/m L ? 0.5mg/m L ?0.75mg/m L inulin pretreatment can significantly improve the relative expression of anti-inflammatory factor genes and reduce the relative expression of pro-inflammatory factor and inflammatory mediator genes,but the dose effect is not significant,which needs further study.Conclusion: high degree of inulin of DP?23 can effectively regulate the diversity,abundance and structure of intestinal flora in healthy people.inulin pretreatment can improve the anti-inflammatory ability of macrophages and significantly improve the phagocytosis efficiency of mycobacterium pubis,but the specific mechanism of action needs further exploration.