Reasearch Of Effects And Mechanism Of Edible Bird’s Nest On Intestinal Immunity In Immunosuppressive Mice

ObjectiveEdible Bird’s nest (EBN) is mainly comprised of saliva gland of several species of Aerodramus or Collocalia genus. It mainly produced in Indonesia, Malaysia, Vietnam Thailand, Hainan and Guangdong of China. Edible bird’s nest is a renowned Chinese delicacy which may have been around since the ancient Chinese dynasties. In recent years, with the improvement of people’s living standards, more and more consumers choose EBN as a senior tonic for lungs, beauty, enhancing immunity and other health recuperation. For a long time, the composition and efficacy of EBN has been lacking of systematic research. The random inspection of blood EBN showed that the nitrite exceed the standards and all the blood EBN were not qualified according to the report of Zhejiang Province in 2011.The nutritional efficacy issues of EBN again widespread concern and questioned. Ancient literature affirmed the EBN’s role of nourishing lung. According to the lung and large intestine theory that there is physiology and pathology link between the respiratory tract and gastrointestinal mucosa. so we speculate that EBN might affect the intestinal immune system through the role of nourishing lung. We mainly researched the effect of EBN on the intestinal immune and also explored the mechanism of EBN on gut immunity of EBN in order to provide the scientific basis for clarifying the effect of EBN.Methods and results1.Effect of EBN on intestinal immunity of normal miceBALB/c mice were randomly divided into four groups, the control group, high dose of EBN (EBNH), medium dose of EBN (EBNM), low dose of EBN (EBNL). Daily oral gavage EBN for 28 days. The impact of EBN on intestinal immunity of normal mice was determined by measuring the concentration of intestinal sIgA, the number of Peyer’s patch and the proportion of T, B lymphocytes in it. The results showed that:EBN could improve the level of sIgA in small intestine of mice nests, but there was no significant difference between the control group; EBN also had no significant effect on the number of Peyer’s patch in normal mouse and it had no significant impact on the proportion of lymphocytes in it.2.Effect of EBN on intestinal immunity of immunosuppressive miceThe immunosuppressive mice were produced by intraperitoneal injection of cyclophosphamide (100mg/kg). The evaluation of EBN on intestinal immunity of immunosuppressive mice was determined by measuring the concentration of intestinal sIgA, the number of Peyer’s patch and the proportion of lymphocytes in it. The results showed that:EBN can significantly increased the level of sIgA in immunosuppressive mice. Low dose, medium and high dose group of EBN had no significant effect on the number of Peyer’s patch in immunosuppressed mice. EBN could reduce the proportion of CD3+ cells and improve the proportion of CD19+ cells in immunosuppressed mice.3.Influence of edible bird’s nest on enteric bacteria flora of miceTo observe the effect of edible bird’s nest (EBN) on the intestinal flora of normal mice. KM mice were divided into four groups, the normal control group, high-dose of EBN group, middle-dose of EBN group,low-dose of EBN group. The contents of representative bacteria in cecum contents were determined by selective culture media of anaerobe and aerobe: Escherichia coli, Enterococcus, Clostridium perfringens, bacteroid, Enteric bifidobacterium and Lactobacillus. We analyzed the intestinal flora at 28d of the cecum contents in each group. Compared with the control group, the contents of Escherichia coli (P<0.01 or P<0.05) and Clostridium perfringens (P<0.05) in EBN group were significantly decreased. The contents of enterococci in EBN group with medium and high dose was significantly decreased(P<0.05 or P<0.01); while the amount of Enteric bifidobacterium and Lactobacillus increased in EBN group with high dose (P<0.05);the amount of bacteroid increased in middle and high-dose group also increased (P<0.05).4.Effect of EBN on activation and proliferation of T and B lymphocyteCCK-8 was used to study the effect of EBN on proliferation of lymphocyte; using two-color flow cytometry combined with fluorescent staining to the detect early, middle and late activation of mouse T, B lymphocytes; using CFDA-SE staining to study the effect of EBN on proliferation of T, B lymphocyte in mice. The results were as follows:CCK-8 assay showed that each dose group of EBN could significantly promote the proliferation of lymphocytes in mice; EBN had no significant impact on early, middle and late activation of T lymphocytes; Each dose group of EBN had no significant impact on T lymphocytes proliferation; EBN could promote B lymphocytes early, middle and late activation; each dose group of EBN could significantly promote the proliferation of mouse B cells.5. Using chromogenic substrate to assay the content of endotoxin in EBN; using of polymyxin B to exclude the impact of the B lymphocytes proliferation by endotoxin in EBNUsing chromogenic substrate to assay the content of endotoxin in EBN; using of polymyxin B to exclude the impact of the B lymphocytes proliferation by endotoxin in EBN. The results were as follows:chromogenic substrate assay results showed that endotoxin content of EBN was 4.3 × 103 (EU/ml); After adding polymyxin B, each dose of EBN remained a significant role in promoting proliferation of B lymphocyte, which indicated that the effect of EBN on B lymphocytes was not from endotoxin in it, but from other ingredients in it.6.Effect of EBN on the production of immunoglobulin in mouse lymphocytesAfter the cells were cultured with EBN, the supernatant was collected to determine the effect of EBN on the on the production of immunoglobulin in mouse lymphocytes. The results showed that:bird’s nest can significantly promote IgE, IgA, IgM, IgG3 antibody secretion, but not for IgG1, IgG2a, IgG2b antibodies secretion.ConelusionIn this study through the intestinal immune activity experiments, we first discovered that the EBN could regulate the immune immunity of immunosuppressed mice by promoting the secretion of intestinal sIgA and regulate T and B lymphocyte proportions in Peyer’s patch. In addition, EBN could regulate the intestinal flora in mice by fostering intestinal bacteria, inhibit harmful bacteria to play a regulatory role in intestinal immunity. Also EBN could promote the activation and proliferation of mouse B lymphocytes, as well as antibody production which maybe the mechanism of regulating intestinal immunity of EBN.