Screening Of Human Lactic Acid Bacteria And Its Immunoregulation In Mice

The immune system is the body’s own defense system, which can identify and eliminate any foreign body of invasive alien, it can also handle aging and death cell of itself. Immunocompromised is a direct manifestation of the imbalance in the immune system, it is a sub-health state of the body, but lactic acid and related products have physiological functions of enhance immunity. In this study, take the lactic acid bacteria from longevity crowd of Guangxi Bama as research target, filter out tolerance and high adhesion lactobacillus by in-vitro tests, set spleen lymphocytes and macrophages as target cells, research which immunomodulatory activity to cells by in-vitro tests, and explore its regulatory effect on the in-vivo immune system by immunocompromised mouse model. The main results are as follows:1. Research the tolerability and adhesion ability of lactic acid bacteria from humanized intestinal by in-vitro tests. Filter out the lactic acid bacteria with stronger tolerance and antibacterial activity by measuring the viability of lactic acid bacteria isolated at the medium of different pH of artificial gastric juice、artificial intestinal juice and bile salt concentration, and the suppression to E.coli, Salmonella, Staphylococcus aureus, Then study their surface hydrophobicity, self-polymerization ability and adhesion ability. The results shows:get 119 strains from the samples,71 of which was identified as lactobacillus,43 of which with the rate of acid production; 21 of which the survival rates are more than 20% in the medium with pH 2.0 culture 3h survival of artificial gastric juice and artificial intestinal juice, the survival rate is more than 10% in the medium with bile salt concentration of 0.5%; further study found,12 plant height adhesion Lactobacillus with surface hydrophobicity more than 25%, self-polymerization more than 25%, The average number of bacteria per cell adherence is more than 8; by correlation analysis of Surface hydrophobicity, self-adhesion and aggregation capabilities, find out, surface hydrophobicity and adhesion has a significant positive correlation (P<0.01), the ability of self-polymerization and adhesion has a significant positive correlation (P<0.01)2. In vitro study of lactic acid bacteria culture on immune cell activity. The induced immune cell proliferation rate, phagocytic ability, secretion of IL-2 and TNF-α and NO level in order to study its effect on the activity of immune cells determined lactic acid bacteria in vitro. The results show that the 12 strains of lactic acid bacteria on spleen lymphocyte induced proliferation rate were more than 40% of the isolates LV108, PW1, RBM7 and XJH301. The strain LV108 on cell induced the strongest effect (P<0.05); stimulation of splenic lymphocytes to secrete IL-2 content was higher than 30.00ng/L strains LV108, T2 and XJH301; stimulation of splenic lymphocytes to secrete TNF-a content were greater than 34.40ng/L strains LV108, N4, XJH301 and w9 On macrophage induced proliferation rate were more than 40% of the isolates LV108, N4, XJH301 and Z9; strain LV108, pw4 and XJH301 induced macrophage phagocytosis of neutral red and the positive control group had no significant difference (P>0.05); stimulate the secretion of macrophage nitric oxide (NO)content were greater than 6.80 μmol/L strain LV108, Q3 and XJH301. Through the study of lactic acid bacteria culture influence on the activity of immune cells found that strains LV108 and XJH301 on cellular immune stimulation effect and the secretion of immunoreactive material was higher than that of the other strains, and of the two strains of lactic acid bacteria in vivo immune regulating function for further study.3. Study on probiotic properties of humanized lactic acid bacteria. Determination of lactic acid bacteria to 13 kinds of antibiotic gentamicin, amikacin and vancomycin susceptibility, against Staphylococcus aureus, Escherichia coli and Salmonella bacteria three pathogenic bacteria antibacterial and antioxidant ability to study the functional characteristics of lactic acid bacteria in vitro. The results showed that the resistant strains LV108 and XJH301 spectrum is relatively narrow, neomycin, sulfamethoxazole and streptomycin has tolerance, of cefoperazone and ceftriaxone moderately sensitive; all of amikacin and vancomycin, card kanamycin and erythromycin sensitive. The bacterial inhibition zone diameters of 3 pathogenic bacteria were 21.40mm,17.50mm and 19.50mm, respectively. The diameter of the strain XJH301 was 18.33mm,17.07mm and 20.17mm, respectively. Strains LV108 and XJH301 fermentation liquid on hydroxyl radical scavenging rate was more than 53%; the DPPH free radical scavenging rate was more than 62%; reducing power was greater than 2. For screening immune regulation performance strong, probiotic properties better strains LV108 and XJH301 API identification and 16S rDNA sequence analysis found that the strain LV108 for Lactobacillus rhamnosus, strain XJH301 for Bifidobacterium breve.4. It’s a study on the effect of lactic acid bacteria on the immune regulation of low immunity mice. To establish the Immunosuppressive Model in mice by intraperitoneal injection of cyclophosphamide, with levamisole as positive control drug, study of lactic acid bacteria suspension and fermented milk regulating effect on immune system. A comparative analysis of the changes in body weight growth rate, organ index, serum levels of immune molecules. At the same time, we detected the serum hemolysis content, ear swelling degree and splenic lymphocytes value-added rate (specific immune function indexes) and macrophage phagocytosis (nonspecific immune function indexes) activity. The results show that the method of using cyclophosphamide for 3 consecutive days of subcutaneous injection of 80mg/kg was successfully established immunosuppressional model mice, the intervention group organ index, hemolysin content, ear swelling index was significantly higher than that of model group (P<0.05); after 4 weeks of intervention by lactic acid bacteria, found that LV108 and XJH301 suspension group and fermented milk group weight gain was significantly higher than that of model group (P<0.05); the serum IL-2 contents were 163.11ng/L,167.41ng/L,160.11ng/L, 166.18ng/L, serum IgG contents were 0.90g/L,0.96g/L,0.85g/L and 0.93g/L were significantly higher than those in the model group (P<0.05); The hemolysin content in serum clearance index and phagocytic index of mice K and a were significantly higher than those in the model group (P<0.05); the study also found that the mice spleen index and thymus index of lactic acid bacteria were significantly higher than those of model group intervention (P<0.05), and the fermented milk group was significantly higher than that of the bacterial suspension group (P<0.05), and the same results were found in the two indexes of ear swelling degree and spleen lymphocyte proliferation rate.