Influence Of Helicobacter Pylori Colonization On Gastric Microbial Flora

The human digestive tract are colonized with numbers of bacterial species, the amountof which is the largest and can reach as high as1014. These bacteria in the gastrointestinalspecial cavity, other physical and chemical factors together constitute the gastrointestinalmicroenvironment. It has significant impacts on human health whether themicroenvironment functions normally. Human microecology is a subject which focus onthe structure and function of normal microorganisms and their correlation with host. Asan important part of life sciences, human microecology plays an increasingly important rolein the understanding of disease occurrence, development and prognosis.Infection of Helicobacter pylori (Hp) is able to lead to a variety of diseases in stomach,such as gastritis, peptic ulcer and even with close relation with the generation, developmentand outcome of gastric cancers. However, its mechanism is still unclear. Previousstudies found that Hp genitic background, host varieties and many other factors play acausative role. As an important part of the gastrointestinal micro-environment, microflorais able to maintain stability and balance of the gastrointestinal microenvironment through avariety of regulatory ways. Once the balance of community structure is broken, it willlead to the generation of diseases. Hp is a major bacterium colonized in stomachmicroenvironment, therefore, whether is its colonization able to cause the changes ofstomach special microenvironment and to induce diseases? How does the stomach florastructure change? Whether is it able to inhibit Hp growth and treatment of Hp-relateddiseases through the reconstruction of micro-ecological environment in the stomach?Whether is there a connection between the micro-environment of the incidence of clinicaloutcomes?Thus, in this study with the help of the epidemiological investigation, the Mongoliangerbils model, PCR-DGGE to (polymerase chain reaction-denaturing gradient gelelectrophoresis technique) and other the means and methods, we try to clarify the relationship betweent the stomach microflora, Hp colonization and Hp infection relateddiseases, in order to provide new microbial modulator ideas for prevention and control ofHp infection related diseases, especially gastric cancers. The detailed research are dividedinto the following three parts:1. The effect of Hp infection on the changes of gastric mucosal flora in Mongoliagerbil.Due to the presence of gastric acid,pepsin, gastric peristalsis and other physical andchemical factors, the micro-environment in stomach is special. The pH value is around2,which inhibits the growth of the major bacteria, Thus the microbial community structureand other physical and chemical factors together form an unique microbial community inthe stomach. As an important component of micro-environment in the stomach, thecolonization of Hp may has important effects on the micro-environment within the stomach.In this study, Mongolia gerbils infected with Hp model was established, then PCR-DGGE,DNA sequencing and other molecular biological techniques was applied to study o therelationship and interaction between Hp colonization and the changes of gastric mucosalflora.Results found that the colonization of Hp will cause the changes of intragastricmicroflora in animal models. This changes include mainly the following two aspects:1)The type and number of bacteria will be affected by Hp colonization. The main leadingstrains within gastric does not was affected, however Hp colonization will competitivelysuppress the growth of a part of bacteria and caused change bacteria structure,such asBacillus.2) The process of pre-Department liquid is able to damage the micro-environmentand reduced the type and number of bacteria group significantly. The Hp colonization instomach will change the micro-environment to some extent, and then promote the recoveryof some strains that have originally cleared by pretreatment solution. Colonization of Hpin the stomach have both two effects on flora: suppression and promotion.2Study on the effect of Lactobacillus on Hp infection correlated changes of gastricmucosa flora in Mongolian gerbil.There is a difficult predicament Powerful antibiotics supplemented with PPI orH2-receptor blocking drugs, which are used for the treatment of Hp infection. Microbialmodulator treatment is attracted much attention gradually. The in vitro experiments have shown that Lactobacillus was able tonhibited Hp significantly, and the inhibition effect wasrelative was positively correlated with its concentration. In addition, probiotics ofLactobacillus may owe to the metabolites. However, these data were main derived from invitro experiments, and there is no clear evidence. In this study, the effect of Lactobacilluson Hp was observed in the gerbil model. PCR-DGGE and subsequent DNA sequencingwere used to investigated the changes of the gerbil stomach flora and to obtain in vivoexperimental data about Lactobacillus and Hp interaction.Three Lactobacillus strains isolated from normal gerbils stomach were used to gavageHp infection gerbil model. Results showed that all the Lactobacillus strains were able toclear Hp colonized in gerbil stomach at a relatively short time (two weeks), and theclearance rate was about60%. In addition, Hp infection-related symptoms were mitigated.Meanwhile, the structural destruction of stomach flora can not be improved purely byLactobacillus gavage treatment. These results implicated microecology treatment as annoval method for the control of Hp infection-related diseases.3. Hp infection related disease populations stomach flora structural differencescomparison and correlation analysis.In the first two sections, Hp colonization will cause changes in microbial community structure in the stomachon was found in animal model. This changes mainly divided into two sides: inhibition and promotion. In addition, Lactobacillus was able to cleare the colonization of Hp in a short time. Does this phenomenon exists in the human stomach? As the special strucuture of microbial community in the human stomach, there is an apparent inconsistency betweent the Hp infection rate and incidence of related diseases. And case studies found that clinical manifestations of Hp infected populations respectively vary. From the perspective of microbial ecology, this study plan to apply PCR-DGGE, DNA sequencing and other molecular biology techniques, in order to clarify the differences in the structure of the stomach flora among different clinical phenotypes.In this study, we found that the Hp infection and its related diseases are closely associated with the microbial community structure.1)With the increae of the severity of the disease, the gastric microflora will change significantly. The number of flora species will significantly reduce.2) Hp colonization will also have an impact on the microbial community structure. although there is no difference of the number of species betweent patients with or wit hout Hp colonization(P>0.05), but under the different condition of stomach diseases, The trends of flora species from non-Hp infected people reduced when compared with that fromHp infected. These results suggest that, from the view of the stomach microecology, It is ofgood clinical significance and prospects to reconstruct stomach microecological environment and to and achieve the cure of Hp-related diseases ultimately.