| Immunity is the inherent self-protection system of the human body,which can recognize,destroy and reject antigens entering the human body.It has the physiological function of maintaining the immune balance and healthy state of the human body.The fast pace of modern life,coupled with the rampant epidemic of the COVID-19,the disturbed daily routine and the sub-healthy state of the body are challenges to the immunity of the body.Improving immunity is one of the many demands of modern health products market.As raw materials,dietary fibres have the advantages of low cost,low toxic and less side effects,and previous studies have proved that polysaccharides have various physiological bioactivities.The market acceptance rate of plant polysaccharide health products has gradually increased.So it is a reliable and low-risk way to improve immunity by ingesting polysaccharide products in daily diet.In conclusion,it is of great social value to develop health food which can improve immunity with foodborne polysaccharide as raw material.Based on previous studies on the bioactivities of different polysaccharides,this study conducted in vitro cell experiments and animal experiments on immunocompromised mouse models induced by cyclophosphamide.The immunoregulatory activities of xanthan gum,apple gum,inulin,guar gum,arabinoglycan,carrageenan,barley polysaccharide,plantago polysaccharide,konjac polysaccharide,xylan and fucoidan were preliminatively studied and compared from the aspects of basic indexes,transcriptomics and metabolomics,and based on the research results,a slightly fermented polysaccharide drink was designed.The main research contents and results are as follows:(1)The immunosuppressed mouse model was built by intraperitoneal injection of cyclophosphamide,and the same dose of polysaccharide(160mg/kg BW/day)was intragastric.The results showed that the weight recovery of mice of apple gum,inulin and guar gum groups was great which almost reach the same level of the normal group.The number of spleen index of mice in the applepectin,inulin,guargum,arabinogalactan and carrageenan groups was significantly decreased compared with the model group,which alleviated the side effects of the drug to a certain extent.The thymus index of mice in applepectin,inulin,guargum,carrageenan and konjac polysaccharide groups increased significantly,which indicates potential recovery of immune function of thymus.(2)Spleen is an important organ of the immune system.Compared with the normal mice,the content of TNF-αcytokines in the spleen of immunocompromised mice was decreased.The content of TNF-αcytokines in the spleen of mice in the applepectin,inulin,guargum,arabinogalactan and carrageenan groups increased,but there was no significant difference.Combined with the analysis results of single gene expression,it was found that the ratio of the applepectin,inulin,guargum and carrageenan groups was increased due to T-bet expression,which was speculated to reduce the immunosuppressive response in the spleen of mice by restoring the expression of Th1 T cells to a certain extent.Among the experimental groups,inulin and guargum both decreased their overall ratio due to the increased Foxp3expression,suggesting that it could reduce the immunosuppressive response in the spleen of mice by enhancing the expression of Treg T cells,but there was no significant effect.In the analysis of lymphocyte subgroups in spleen tissue,it was found that applepectin,inulin and guargum not only increased the overall proportion of CD3~+cells,but also increased the proportion of CD3~+and CD4~+double-stained positive cells,strengthened the pivot of immune response,and improved the ability of immune monitoring and information transmission.In vitro experiments on the proliferation of primary splenic lymphocytes of mice,among the 11 kinds of polysaccharides,Xanthan gum,barley polysaccharide and konjac polysaccharide significantly enhanced their proliferation ability in the dose range of 0-160μg/m L polysaccharide dose.The auxiliary effects of xanthan gum and Konjac polysaccharide showed a certain dose dependence,and the higher the concentration of polysaccharide,the better the effect.(3)Blood is the intermediary between organs and the external environment,which can transport necessary nutrients,heat or hormones for the whole body to maintain the stability of the internal environment.At the same time,it can complete the exchange of substances,in which various metabolites exist.The humoral immunity of the immunosuppressed mice model was impaired,and the serum Ig M level in the normal group was significantly higher than that in the model group.Compared with model group,serum Ig M content in xanthan gum group,applepectin group,inulin group and guargum group increased,but there was no significant difference.Compared with model group,the serum Ig M content in other groups was lower,and Konjac polysaccharide group and xylan group had significant effects.(4)Compared with normal mice,a total of 91 metabolites levels in serum of immunosuppressed mice were significantly changed,and the concentrations of lysophosphatidylcholine and phospholipid were significantly higher than those of normal group,while the concentrations of triglyceride,oligopeptide,pyrimidine and carnitine were significantly lower than those of normal group.These differential metabolites are mainly involved in pyrimidine metabolism,glycerol phospholipid metabolism,cysteine and methionine metabolism,purine metabolism glutathione metabolism,glycine,serine and threonine metabolism,citric acid cycle pentose and glucuronic acid interconversion and other metabolic pathways.Compared with the model group,the xanthan gum group had the largest number of metabolites with significant changes,which reaches 71,followed by fucoidan group with the number of 60.Compared with model group,xanthan gum group and normal group had the most common metabolites(16 kinds),followed by inulin group with 15 kinds.11kinds of polysaccharide groups have 73 kinds of common metabolites compared with normal group.Compared with model group,the metabolism of arginine and proline,glycerol phospholipid,glyoxylic acid and dicarboxylic acid,citric acid cycle and glutathione in serum of immunocompromised mice were significantly changed by gavage of xanthan gum.Inulin administration significantly changed the metabolism of glycerophospholipids,the interconversion of pentose and glucuronic acid,and the metabolism of glutathione in serum of immunosuppressed mice.Intragastric administration of psyllium polysaccharide,konjac polysaccharide,xylan and fucoidan significantly changed the metabolism pathway of glycerol phospholipid in serum of immunocompromised mice.Meanwhile,xylan also significantly affected cysteine and methionine metabolism,and fucoidan also significantly affected purine metabolism.(5)Based on previous experimental results,inulin and applepectin were selected to design lactic acid bacteria mild fermented drink,and the fermentation effect of three commercial lactic acid bacteria on polysaccharide was compared,and Lactobacillus HN001 was selected as a single fermentation strain to determine the product formula and process,and the activity of the product was tested by animal experiments and compared with the active function of raw polysaccharides.The results showed that the raw polysaccharide groups and the product groups had a good recovery in each index,among which the weight change level of inulin group,inulin product group and applepectin groups were basically consistent with that of normal group.The recovery effect of the product group on the side effects of spleen enlargement in the immunocompromised mouse model was better than that of the product group.The raw polysaccharide groups and the product groups could improve the serum immunoglobulin G and immunoglobulin M levels of mice,the Ig G content of inulin group and applepectin group were significantly increased,the Ig M content of inulin product group was slightly higher and had a significant effect.The content of TNF-αin spleen tissue of some mice in inulin product group and applepectin group even exceeded the concentration level of normal group.There was no significant differences between raw polysaccharide groups and the product groups.The recovery level of inulin product group was slightly higher than that of inulin group,and individual recovery level of applepectin group was higher,showing that the overall recovery level of applepectin group was slightly higher than that of applepectin group.In summary,inulin and applepectin had the strongest recovery ability on related index of immunosuppressed mice at the same evaluation level,and the immune regulatory function of raw sugar was even partially exceeded to some extent through Lactobacillus slight fermentation. |
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