| In my country,lotus root is widely cultivated and is an extremely rich edible and medicinal plant resource.Lotus root residues were leftovers from lotus root processing,most of which were discarded,resulted in a waste of resources.Lotus root residue polysaccharide(LRP)is one of the main active components in lotus root residue.Previous studies have shown that it has biological activities such as antioxidant,hypoglycemic,hemostasis,antiviral and immune regulation.In this paper,16 S r DNA high-throughput technology and other related molecular biology methods were used to systematically study the in vitro and in vivo immune activity of LRP.The effects of dietary treatment of LRP on the intestinal flora of immunocompromised mice were revealed,which can provide references for the development,application and in-depth research of related products:(1)Human saliva,simulated artificial gastric juice and simulated small intestinal juice were collected to digestion of LRP,and fresh human feces as the inoculation source were used,LRP was fermented by in vitro fermentation,the fermentation characteristics of LRP and its effected on human gut microbiota was studied.The simulated digestion results show that only a small part of LRP was digested,and most of it could successfully reached the large intestine.The fermentation results showed that LRP was degraded into SCFAs by gut microbiota,and the intestinal p H was reduced.16 S r DNA sequencing analysis showed that LRP decreased the ratio of Firmicutes/Bacteroidetes in the gut,increased the relative abundance of Bifidobacterium,and modulated the composition of gut microbiota.(2)Peritoneal macrophages from BALB/c mice was taked as experimental objects,the cells were treated with LRP at different time points and the signaling pathway of LRP-stimulated peritoneal macrophages to produce immune responses was explored.The results showed that LRP had no toxic effect on macrophages within the 200 μg/m L concentration.NO concentration increased with increasing LRP treatment concentration/treatment time.It is found that LRP was binded to TLR4 and TLR2 receptors and the expression of cytokines was promoted.And the expression of nuclear proteins c-Jun and p65 was promoted,ERK1/2,JNK,p38 proteins and their phosphorylation levels was increased.Therefore,LRP enhanced the immune response of peritoneal macrophages in BALB/c mice through the MAPK/NF-κB pathway.(3)CTX was used to induce BALB/c mice and the immunocompromised model was established,the protective effect of LRP on immunocompromised mice was studied.The results showed that CTX reduced the body weight,food intake and water intake of mice,the size of the spleen was decreased,the thymus and spleen index of mice were decreased,the spleen and liver were damaged,the jejunum villi were shortenedand and the intestinal wall was thinned.However,LRP increased the weight gain rate of CTX mice,enlarged the spleen of mice,the immune organ indexs of mice were improved,the damage of the spleen and liver were relieved,the shape of the jejunal villi was restored,and the immune damage of the organ was repaired.(4)LRP intervention modulated the structure of the gut microbiota in CTX-induced immunocompromised mice.At the phylum level,LRP significantly increased the relative abundance of Bacteroidetes in the gut of immunocompromised mice,and the relative abundance of the pathogenic bacteria Epsilonbacteraeota was decreased.At the family level,the relative abundances of Lachnospiraceae,Ruminococcaceae and Prevotellaceae were increased.And at the genus level,LRP increased the relative abundance of Lachnospiraceae＿NK4A136＿group,Alloprevotella and Bacteroides,which has a good effect on repaired organ damage and improved intestinal immunity. |
