The human intestinal microbiota is a community of 10(13)-10(14) microorganisms that harbor in the intestine and normally participate in a symbiotic relationship with human. Technical and conceptual advances have enabled rapid progress in characterizing the taxonomic composition, metabolic capacity and immunomodulatory activity of the human intestinal microbiota. Their collective genome, defined as microbiome, is estimated to contain > or =150 times as many genes as 2.85 billion base pair human genome. The intestinal microbiota and its microbiome form a diverse and complex ecological community that profoundly impact intestinal homeostasis and disease states. It is becoming increasingly evident that the large and complex bacterial population of the large intestine plays an important role in colorectal carcinogenesis. Numerous studies show that gut immunity and inflammation have impact on the development of colorectal cancer. Additionally, bacteria have been linked to colorectal cancer by the production of toxic and genotoxic bacterial metabolite. In this review, we discuss the multifactorial role of intestinal microbiota in colorectal cancer and role for probiotics in the prevention of colorectal cancer.
Animals ; Bacteroides/metabolism ; Colorectal Neoplasms/immunology/*microbiology ; Fatty Acids, Nonesterified/metabolism ; Humans ; Hydrogen Sulfide/metabolism ; Intestinal Mucosa/immunology/microbiology ; Metagenome ; *Probiotics ; Reactive Oxygen Species/metabolism ; Toxins, Biological/metabolism

This study was aimed to prepare a reconstructed B. Fragilis-derived recombinant α-galactosidase developed for human B to O blood group conversion. Based on the construction of recombinant E. Coli (DE3) which can express α-galactosidase, the inducing time and inducer concentration were optimized for high expression of α-galactosidase. Then, the expression products in supernatant were purified by cation and anion exchange column chromatography. The purified α-galactosidase was used to treat B group red blood cells in phosphate buffer (pH 6.8) for 2 hours to prepare O group red blood cells. The results showed that the optimal inducing conditions for α-galactosidase expression were IPTG 0.1 mmol/L, 37°C and 2 hours. The specific enzyme activity of purified protein increased from 0.42 U/mg to 2.1 U/mg as compared with pre-purification. And, the conditions of B to O blood group conversion were 26°C, pH 6.8 (neutral pH condition) and 2 hours. Moreover, 225 µg of the enzyme could converse 1 ml B red blood cells to O completely. It is concluded that the technology of expression and purification of recombinant α-galactosidase has been established, and the purified protein can converse B red blood cells to O completely, which means that an effective enzyme conversing B red blood cells to O has been obtained.
ABO Blood-Group System ; immunology ; Bacteroides fragilis ; enzymology ; Cloning, Molecular ; Escherichia coli ; metabolism ; Humans ; Recombinant Proteins ; biosynthesis ; alpha-Galactosidase ; biosynthesis

OBJECTIVETo investigate the influence of the LPS of Bacteroides fragilis on the secretion of IL-2 and IL-4 from the peripheral blood mononuclear cells of normal individuals, so as to elucidate the mechanism of the infection by Bacteroides fragilis.

METHODSLPS was obtained from both the strains isolated from patients and from standard NCTC9343. Peripheral blood mononuclear cells (PBMCs) were treated with different concentrations of LPS thus obtained. The supernatants from the cell culture of the PBMCs were harvested at 24 PBHs and were subjected to the determination of the IL-2 and IL-4 contents by ELISA method. RESULTS The IL-2 secretion from the PBMCs of normal volunteers was obviously inhibited by the LPS from Bacteroides fragilis (P < 0.01), and the inhibitory effect was dose-dependent. Nevertheless, the IL-4 secretion from the PBMCs of normal volunteers was significantly stimulated by the LPS from Bacteroides Fragilis (P < 0.05), and it was not concentration dependent. There was no difference between the effects of the LPSs from patients and standard strains (P < 0.05).

CONCLUSIONThe LPS from Bacteroides fragilis was inhibitory to the secretion of IL-2 from PBMCs and was stimulative to that of IL-4 from PBMCs of normal human persons.

Bacteroides fragilis ; metabolism ; Cells, Cultured ; Humans ; Interleukin-2 ; immunology ; secretion ; Interleukin-4 ; immunology ; secretion ; Lipopolysaccharides ; pharmacology ; Monocytes ; drug effects ; immunology

OBJECTIVETo investigate the effect of triggering receptor expressed on myeloid cells 1 (TREM-1) vshRNA vector on expression of inflammatory cytokines and survival rate in septic mice infected by Bacteroides fragilis.

METHODS(1) TREM-1 vshRNA vector was constructed. Bacteroides fragilis (2.5 x 10(9) CFU/mL, 0.5 mL) was intraperitoneally injected in each mouse, and septic model was reproduced after 12 hours. (2) One hundred and fifteen mice were divided into healthy control group (n = 3, HC), sepsis group (n = 28, S), TREM-1 vshRNA group (n = 28, T), TREM-1 vshRNA hd group (n = 28, Th), GFP group (n = 28, G) according to random number table. Mice in S, T, Th, G groups were firstly injected with isotonic saline, TREM-1 vshRNA 2 x 10(8) TU, TREM-1 vshRNA 1 x 10(8) TU, GFP siRNA through tail vein, and then sepsis was induced after 1 hour. Mice in HC group were injected with equal volume of isotonic saline through tail vein. Three mice in each group were sacrificed after 12 hours for determination of plasma level of TNF-alpha, IL-1 beta and IL-6, and level of TREM-1mRNA and its protein in hepatic tissue. The survival rate of other mice in each group was monitored for 72 hours. (3) In 125 mice sepsis was reproduced, among them 100 mice were injected with TREM-1 vshRNA 2 x 10(8) TU after 1, 2, 4, 6 hours through tail vein (25 mice at each time point), other 25 mice were injected with equal volume of isotonic saline as control. The survival rate of mice in each group was recorded 72 hours after injection.

RESULTS(1) Compared with those in S group, the plasma level of TNF-alpha, IL-1 beta and IL-6 lowered in T and Th groups (P < 0.05), especially in T group, while those in G group showed no obvious difference (P > 0.05). (2) Compared with those in G group, the level of TREM-1mRNA and its protein in hepatic tissue in T and Th groups decreased (P < 0.01), especially in T group. (3) The survival rate of mice in S and G group was 16%, which was obviously lower than that in T and Th groups (76%, 44%, respectively, P < 0.05 or P < 0.01). (4) The survival rate of mice at 1, 2, 4, 6 hours after injection was 72%, 56%, 40%, 16%, respectively, while all that except at 6 hour after injection were higher significantly than that of control (P < 0.05 or P < 0.01).

CONCLUSIONSThe intervention with TREM-1 vshRNA can effectively decrease hepatic level of TREM-1 in septic mice induced by Bacteroides fragilis, inhibit inflammatory response, and improve the survival rate.

Animals ; Bacteroides fragilis ; Disease Models, Animal ; Genetic Vectors ; Lentivirus ; Male ; Mice ; Mice, Inbred BALB C ; RNA, Messenger ; metabolism ; Receptors, Immunologic ; genetics ; Sepsis ; metabolism ; microbiology ; therapy ; Virosomes

Heparinase III (HepIII) is a 73-kDa polysaccharide lyase (PL) that degrades the heparan sulfate (HS) polysaccharides at sulfate-rare regions, which are important co-factors for a vast array of functional distinct proteins including the well-characterized antithrombin and the FGF/FGFR signal transduction system. It functions in cleaving metazoan heparan sulfate (HS) and providing carbon, nitrogen and sulfate sources for host microorganisms. It has long been used to deduce the structure of HS and heparin motifs; however, the structure of its own is unknown. Here we report the crystal structure of the HepIII from Bacteroides thetaiotaomicron at a resolution of 1.6 Å. The overall architecture of HepIII belongs to the (α/α)₅ toroid subclass with an N-terminal toroid-like domain and a C-terminal β-sandwich domain. Analysis of this high-resolution structure allows us to identify a potential HS substrate binding site in a tunnel between the two domains. A tetrasaccharide substrate bound model suggests an elimination mechanism in the HS degradation. Asn260 and His464 neutralize the carboxylic group, whereas Tyr314 serves both as a general base in C-5 proton abstraction, and a general acid in a proton donation to reconstitute the terminal hydroxyl group, respectively. The structure of HepIII and the proposed reaction model provide a molecular basis for its potential practical utilization and the mechanism of its eliminative degradation for HS polysaccarides.
Amino Acid Sequence ; Bacteroides ; enzymology ; Catalytic Domain ; Crystallography, X-Ray ; Heparitin Sulfate ; metabolism ; Kinetics ; Models, Molecular ; Molecular Sequence Data ; Polysaccharide-Lyases ; chemistry ; metabolism ; Substrate Specificity

BACKGROUND/AIMS: Tens of trillions of microorganisms constitute the gut microbiota of the human body. The microbiota plays a critical role in maintaining host immunity and metabolism. Analyses of the gut microbial composition in Korea are limited to a few studies consisting of small sample sizes. To investigate the gut microbial community in a large sample of healthy Koreans, we analyzed the 16S ribosomal RNA of 4 representative bacterial genera Lactobacillus, Bifidobacterium, Bacteroides, and Clostridium. METHODS: A total of 378 DNA samples extracted from 164 infants and 214 adults were analyzed using quantitative real-time polymerase chain reaction. RESULTS: Analysis of 16S ribosomal RNA of 4 representative bacterial genera Lactobacillus, Bifidobacterium, Bacteroides, and Clostridium showed that the gut microbiota in infants had higher relative abundances of Bifidobacterium and Lactobacillus than that in adults, which was dominated by Bacteroides and Clostridium. CONCLUSIONS: To the best of our knowledge, this was the first study evaluating the distinct characteristics of the microbial community of Korean infants and adults. The differences between the 2 populations suggest that external factors such as age, diet, and the environment are important contributing factors to the change in gut microbial composition during development.
Adult ; Bacteroides ; Bifidobacterium ; Clostridium ; Diet ; DNA ; Gastrointestinal Microbiome ; Human Body ; Humans ; Infant ; Korea ; Lactobacillus ; Metabolism ; Microbiota* ; Real-Time Polymerase Chain Reaction ; RNA, Ribosomal, 16S ; Sample Size ; Transcutaneous Electric Nerve Stimulation