Study On Immune Regulating Activity Of Fuzhuan Tea Polysaccharide And Its Regulating Effect On Intestinal Health

Fuzhuan brick tea is called as "the life tea of the Northwest nationalities" in China.It has a variety of effective active substances,such as tea polysaccharide,tea polyphenols,tea pigment,amino acids and caffeine.The polysaccharide from Fuzhuan brick tea(FBTPS)is an important component of Fuzhuan brick tea.Studies show that tea polysaccharide has many functions,such as immune regulation,hypoglycemia,tumor inhibition and antioxidant,so it has received extensive attention.This study took the FBTPS as the research object,briefly analyzed its physical and chemical properties,and studied its functions of protecting intestinal barrier,regulating immunity and intestinal microflora.The main research results are as follows:1.Isolation and purification of FBTPS and its effect on intestinal barrierIn this chapter,the crude polysaccharide of Fuzhuan brick tea(CFBTPS)was extracted and purified by DEAE Sepharose Fast Flow column,and two purified components(FBTPS-2 and FBTPS-3)were obtained.Among them,FBTPS-3 is the component with the highest yield.The contents of natural carbohydrate in CFBTPS FBTPS-2 and FBTPS-3 were 40.05%,51.47% and 44.78%,respectively,and the contents of uronic acid were 28.91%,17.87% and 40.43%,respectively.Thermal decomposition of CFBTPS,FBTPS-2 and FBTPS-3 occurred at 514.78℃,451.22℃and 383.04℃,respectively.Next,lipopolysaccharide(LPS)was used to induce cell damage in Caco-2 cells,and the effects of CFBTPS and FBTPS-3 on the relative expression of tight junction(TJ)protein were studied.The results showed that FBTPS-3 had the best effect of upregulating Claudin-4 and could protect the intestinal barrier by upregulating the expression of TJ protein.2.Effects of FBTPS on immune function of miceIn this chapter,cyclophosphamide(Cy)was used to establish an immunosuppressed mouse model to explore the regulatory effects of CFBTPS and FBTPS-3 on the immune function of mice.The results showed that CFBTPS and FBTPS-3 could restore body weight and feed intake,protect immune organs including spleen and thymus,stimulate the production of cytokines TNF-α,IFN-γ and IL-1β in serum and immunoglobulin Ig A in mice.Meanwhile,it could also promote the production of short-chain fatty acids(SCFAs)in intestinal tract and up-regulate the m RNA levels of TNF-α,IFN-γ,IL-6,IL-10,GPR41 and GPR43 genes in colon tissue.These results suggested that CFBTPS and FBTPS-3 could regulate host immune function and could be used as an effective immune enhancer.3.Effects of FBTPS on intestinal health of miceIn this chapter,the regulation effects of CFBTPS and FBTPS-3 on intestinal barrier and gut microbiota mice with Cy-induced gut microbiota disturbance were studied.The results showed that FBTPS has a protective effect on the structure of the jejunum and colon.At the same time,it could protect the intestinal barrier by up-regulating the relative expression levels of MUC-2 and TJ proteins in the colon tissue.The analysis of gut microbiota showed that FBTPS could significantly restore the relative abundance of Muribaculaceae,Lachnospiraceae,Helicobacteraceae,Clostridaceae,Desulfovibrionaceae and Deferribacteraceae changed by Cy.Spearman correlation analysis showed that the relative abundance of Muribaculaceae＿unclassified and Lachnospiraceae＿NK4A136＿group were significantly positively correlated with the immune organ index,inflammatory factors,tight linkage protein in the intestine,and some indexes of SCFAs in the mice.The relative abundances of Muribaculum,Helicobacter,Millionella,Ruminiclostridium,Mucispirillum,Ruminiclostridium＿9and Intestinimonas were significantly negatively correlated with the above main immune indexes.KEGG pathway enrichment analysis showed that FBTPS significantly restored bacteria related to immune system,amino acid metabolism,enzyme family,digestive system,endocrine system and carbohydrate metabolism.KEGG pathway enrichment analysis showed that FBTPS significantly restored the expression of genes related to immune system,amino acid metabolism,enzyme family,digestive system,endocrine system and carbohydrate metabolism.At the same time,the expression of genes related to signal transduction,environmental adaptation,cellular circulatory system and membrane transport was inhibited.These results indicated that CFBTPS and FBTPS-3 can protect the intestinal barrier in mice and enhance the immune function of mice by regulating the gut microbiota.