Oral administration of Pantoea agglomerans-derived lipopolysaccharide prevents metabolic dysfunction and Alzheimer's disease-related memory loss in senescence-accelerated prone 8 (SAMP8) mice fed a high-fat diet.

The pathogenesis of Alzheimer's disease (AD) remains unclear, but an imbalance between the production and clearance of amyloid-ß (Aß) peptides is known to play a critical role in AD progression. A promising preventative approach is to enhance the normal Aß clearance activity of brain phagocytes such as microglia. In mice, the intraperitoneal injection of Toll-like receptor 4 agonist was shown to enhance Aß clearance and exhibit a preventative effect on AD-related pathology. Our previous clinical study demonstrated that orally administered Pantoea agglomerans-derived lipopolysaccharide (LPSp) exhibited an LDL (low-density lipoprotein)-lowering effect in human volunteers with hyperlipidemia, a known risk factor for AD. In vitro studies have shown that LPSp treatment increases Aß phagocytosis by microglial cells; however it is still unclear whether orally administered LPSp exhibits a preventive effect on AD progression. We show here that in senescence-accelerated prone 8 (SAMP8) mice fed a high-fat diet, oral administration of LPSp at 0.3 or 1 mg/kg body weight·day for 18 weeks significantly improved glucose metabolism and lipid profiles. The LPSp treatment also reduced pro-inflammatory cytokine expression and oxidative-burst activity in the peripheral blood. Moreover, LPSp significantly reduced brain Aß burden and memory impairment as seen in the water maze test, although we could not confirm a significant enhancement of Aß phagocytosis in microglia isolated from the brains after treatment. Taken together, our results show that LPSp holds promise as a preventative therapy for AD or AD-related diseases induced by impairment of metabolic functions.

Oral administration of Pantoea agglomerans-derived lipopolysaccharide prevents development of atherosclerosis in high-fat diet-fed apoE-deficient mice via ameliorating hyperlipidemia, pro-inflammatory mediators and oxidative responses.

Pantoea agglomerans (P. agglomerans) is a Gram-negative bacterium that grows symbiotically with various edible plants, and the oral or sublingual administration of lipopolysaccharide derived from P. agglomerans (LPSp) have been suggested to contribute to prevention of immune-related diseases. Our previous study indicated that orally administered LPSp was shown to exhibit an LDL-lowering effect in hyperlipidemic volunteers; however, a preventive effect of LPSp on atherosclerosis is unclear. The present study attempted to evaluate the anti-atherosclerotic effect by LPSp in a mouse model of high-fat diet (HFD)-induced atherosclerosis. For 16 weeks, apoE-deficient mice were fed an HFD and received drinking water containing LPSp (0.3 or 1 mg/kg body weight/day). The results showed that the orally administered LPSp decreased body weight. A significant reduction in atherosclerotic plaque deposition was observed even with the lower dose of LPSp. The biochemical analyses showed that LPSp markedly improved glucose tolerance and reduced plasma LDL and oxidized LDL levels. In addition, LPSp significantly reduced the production of pro-inflammatory mediators including MCP-1 (in the plasma), TNF-α and IL-6 (in the colon), and decreased the oxidative burst activities in the peripheral blood sample. Taken together, these results suggest the possibility that oral administration of LPSp can effectively ameliorate HFD-induced hyperlipidemia and inflammatory/oxidative responses to prevent atherosclerosis and related metabolic disorders.

L­histidine augments the oxidative damage against Gram­negative bacteria by hydrogen peroxide.

Excessive damage to DNA and lipid membranes by reactive oxygen species reduces the viability of bacteria. In the present study, the proliferation of recA­deficient Escherichia coli strains was revealed to be inhibited by 1% L­histidine under aerobic conditions. This inhibition of proliferation was not observed under anaerobic conditions, indicating that L­histidine enhances oxidative DNA damage to E. coli cells. Reverse transcription­quantitative polymerase chain reaction analysis demonstrated that the expression of recA in E. coli MG1655 increased ~7­fold following treatment with 10 mM hydrogen peroxide (H2O2) plus 1% L­histidine, compared with that following exposure to H2O2 alone. L­histidine increased the genomic fragmentation of E. coli MG1655 following exposure to H2O2. In addition, L­histidine increased the generation of intracellular hydroxyl radicals in the presence of H2O2 in E. coli cells. Next, our group investigated the disinfection properties of the H2O2 and L­histidine combination. The combination of 100 mM H2O2 and 1.0% L­histidine significantly reduced the number of viable cells of extended­spectrum­ß­lactamase­producing E. coli and multidrug­resistant Pseudomonas aeruginosa, and this treatment was more effective than 100 mM H2O2 alone, but this effect was not observed in methicillin­resistant Staphylococcus aureus or vancomycin­resistant Enterococcus faecium. The combination of L­histidine and H2O2 may be a useful strategy to selectively increase the microbicidal activity of oxidative agents against Gram­negative bacteria.

Lipopolysaccharides Derived from Pantoea agglomerans Can Promote the Phagocytic Activity of Amyloid ß in Mouse Microglial Cells.

BACKGROUND/AIM: Recent studies reported that lipopolysaccharide (LPS) exhibits beneficial effects on prevention of immune-related diseases by activating macrophages. We previously demonstrated that pre-treatment with LPS derived from Pantoea agglomerans (LPSp) activated amyloid ß (Aß) phagocytosis in mouse primary microglia. In the present study, we further examined the promotory effect on phagocytosis of phagocytic particles in the C8-B4 microglia cell line. MATERIALS AND METHODS: Phagocytic analysis of C8-B4 cells was evaluated using phagocytic particles (latex beads or HiLyte™ Fluor 488-conjugated Aß1-42). RESULTS: The phagocytic activity of latex beads was dependent on the concentration of beads and incubation time. LPSp, at as low as 100 pg/ml, significantly increased phagocytosis against the beads. In the experiment of Aß1-42 phagocytosis, LPSp significantly increased Aß phagocytic activity. CONCLUSION: LPSp treatment was confirmed to enhance Aß1-42 phagocytosis by mouse microglia. It is suggested that the use of LPSp may be a potential promising candidate for the prevention of Alzheimer's disease.

Counterselection employing mutated pheS for markerless genetic deletion in Bacteroides species.

Markerless gene deletion is necessary for multiple gene disruptions due to the limited number of antibiotic resistant markers for some bacteria. However, even in transformable strains, obtaining the expected mutation without a marker requires laborious screening of a large number of colonies. Previous studies had success in various bacteria with a counter-selection system where a conditional lethal gene was incorporated into the vector. We examined the efficacy of the mutated pheS gene (pheS*) as a counter-selective marker for gene deletion in Bacteroides. This mutation produces an amino acid substitution (A303G) in the alpha subunit of Bacteroides phenylalanyl tRNA synthetase, which in E. coli alters the specificity of the tRNA synthetase resulting in a conditional lethal mutation due to the incorporation of p-chloro-phenylalanine (p-Cl-Phe) into protein. B. fragilis YCH46 and B. thetaiotaomicron VPI-5482 transformed with a pheS*-harboring shuttle vector were clearly growth-inhibited in the presence of >5 mM p-Cl-Phe in liquid defined minimal media (DMM) and on DMM agar plates. A targeting plasmid was constructed to delete the genetic region for capsular polysaccharide PS2 in B. fragilis or PS1 in B. thetaiotaomicron. After counterselection, p-Cl-Phe-resistant colonies were generated at a frequency of 8.1 × 10-3 for B. fragilis and 1.7 × 10-3 for B. thetaiotaomicron. Of the p-Cl-Phe-resistant colonies, 4.2% and 72% harbored the correct genetic deletion for B. fragilis and B. thetaiotaomicron, respectively. These results indicate that mutated pheS is a useful counter-selective gene to construct markerless genetic deletions in Bacteroides.

Effect of Lipopolysaccharide Derived from Pantoea agglomerans on the Phagocytic Activity of Amyloid ß by Primary Murine Microglial Cells.

BACKGROUND/AIM: Monophosphoryl lipid A, lipopolysaccharide (LPS)-derived Toll-like receptor (TLR) 4 agonist, has been shown to be effective in the prevention of Alzheimer's disease (AD) by enhancing phagocytosis of amyloid ß (Aß) by brain microglia. Our recent study demonstrated that oral administration of LPS derived from Pantoea agglomerans (LPSp) activates peritoneal macrophages and enhances the phagocytic activity via TLR4 signaling pathway; however, the effect of LPSp on Aß phagocytosis in microglia is still unknown. MATERIALS AND METHODS: Primary microglial cells were isolated from adult mouse brain by enzymatic digestion, following myelin removal and magnetic separation of cluster of differentiation (CD) 11b. Phagocytic analysis of the primary microglia was measured by using HiLyte™ Fluor 488-conjugated Aß1-42 RESULTS: Using our protocols, the average yield of isolated CD11b(+) cells was around 2.2×10(5) cells per brain. CD11b(+)CD45(+)CD39(+) cells were defined here as microglia. The phagocytic activity of Aß1-42 by the isolated microglia was confirmed. LPSp (10 ng/ml) pre-treatment for 18 h significantly increased Aß phagocytic activity. CONCLUSION: The enhancement of Aß1-42 phagocytosis by LPSp treatment in the primary mouse microglia was demonstrated for the first time.

Mariner-based transposon mutagenesis for Bacteroides species.

Bacteroides is one of the most predominant groups of human gut microbiota. Recent metagenomic analyses and studies on gnotobiotic mice demonstrated the tight association of Bacteroides with epithelial function, the gut immune system and systemic metabolism in the host. The mariner family transposon shows relatively low target site specificity and has hosts ranging from prokaryotes to eukaryotes. Thereby, random mutagenesis using the mariner family transposon is expected to identify key molecules for human-Bacteroides symbiosis. In this study, we constructed the plasmid pMI07 to deliver the gene cassette (ermF/ITR), which harbors the erythromycin resistant marker (ermF) and the inverted repeat sequences (ITRs) recognized by Himar1 transposase, to Bacteroides via electrotransformation. pMI07 successfully delivered ermF/ITR to the Bacteroides genomes and generated thousands of insertion mutants/µg of pMI07 in B. thetaiotaomicron, B. fragilis, B. ovatus, and also, although to a lesser extent, B. vulgatus. Analyses of the ermF/ITR insertion sites in B. thetaiotaomicron and B. vulgatus revealed that the cassette targeted the dinucleotide TA and integrated into the genomes in an unbiased manner. The data reported here will provide useful information for transposon mutagenesis in Bacteroides species, which will enable identification of the genes responsible for their unique phenotypes.

Role of chicken Pit-1 isoforms in activating growth hormone gene.

In the present study, we expressed chicken (ch) Pit-1α (chPit-1α) and chPit-1γin vitro to compare the roles of chPit-1s in the transcription of the chicken growth hormone (chGH) gene. Both green fluorescence protein (GFP)-fused chPit-1γ and GFP-fused chPit-1α were localized in the nuclei of COS-7 cells. In a luciferase reporter gene assay, both chPit-1α and chPit-1γ transactivated the chGH promoter, and chPit-1α showed a more potent effect than chPit-1γ. On the other hand, an increase of cellular cAMP induced by forskolin promoted transactivation of the chGH gene with chPit-1α and chPit-1γ to similar extents. These results suggest that chPit-1γ may modulate the basal promoter activity of the chGH gene to the same degree as chPit-1α; however, a structural difference observed at the N-terminus transactivation domains in chPit-1α and chPit-1γ could be associated with the efficiency of basal activation of the chGH promoter.

Cloning and characterization of the gene encoding endo-beta-1,3-glucanase from Arthrobacter sp. NHB-10.

The gluA gene, encoding an endo-beta-1,3-glucanase from Arthrobacter sp. (strain NHB-10), was cloned and analyzed. The deduced endo-beta-1,3-glucanase amino acid sequence was 750 amino acids long and contained a 42 amino acid signal peptide with a mature protein of 708 amino acids. There was no similarity to known endo-beta-1,3-glucanases, but GluA was partially similar to two fungal exo-beta-1,3-glucanases in glycoside hydrolase (GH) family 55. Of five possible residues for catalysis and two motifs in two beta-helix heads of GH family 55, three residues and one motif were conserved in GluA, suggesting that GluA is the first bacterial endo-beta-1,3-glucanase in GH family 55. Significant similarity was also found to two proteins of unknown function from Streptomyces coelicolor A3(2) and S. avermitilis.

Anti-human immunodeficiency virus activity of 3,4,5-tricaffeoylquinic acid in cultured cells of lettuce leaves.

3,4,5-Tricaffeoylquinic acid (TCQA) that is not found in intact plant of lettuce leaves was isolated from the cultured cells. The intact plant produced chicoric acid (dicaffeoyl tartaric acid: L-CCA) as well as chlorogenic acid (3-caffeoylquinic acid: 3-CQA) as the major metabolites. After subculturing of the cells for 40 days, the amount of 3,4,5-TCQA reached to 0.14 mg/g fresh weight. The inhibitory effect of 3,4,5-TCQA for human immunodeficiency virus (HIV) Type 1 integrase was assayed. Anti-HIV activity using HIV and MT-2 cells was 1.15 microM and IC(50) against HIV integrase was 0.063 microM whereas cell toxicity of this chemical was expressed as 5% death of all living cells to be 18.4 microM. The HIV inhibitory effect of 3,4,5-TCQA was the highest in values among L-CCA, and other dicaffeoylquinic acids. This data will provide a new possibility for creating a new drug design for HIV.

Purification and antifungal activity of recombinant chitinase from Escherichia coli carrying the family 19 chitinase gene of Streptomyces sp. J-13-3.

A recombinant chitinase was purified from the cell extract of Escherichia coli JM109 transformed by plasmid pUC19 carrying the gene encoding family 19 chitinase of Streptomyces sp. J-13-3 by column chromatography on DEAE-Sepharose, CM-Sepharose, and Bio-Gel P-100. The final preparation was homogenous in polyacrylamide gel electrophoresis. The molecular weight of the purified enzyme was estimated to be 32,000. The recombinant chitinase hydrolyzed the trimer to hexamer of N-acetylglucosamine and had the identical N-terminal amino acid sequence of the mature protein, indicating removal of the signal sequence by E. coli signal peptidase. The fungal growth in well (200 microl of medium) of microplate by measurement of absorbance at 595 nm indicated that the chitinase (10 microg) completely and half inhibited growth of Trichoderma reesei and Aspergillus niger respectively.

Molecular cloning and expression of the gene encoding family 19 chitinase from Streptomyces sp. J-13-3.

The gene encoding chitinase from Streptomyces sp. (strain J-13-3) was cloned and its nucleotide structure was analyzed. The chitinase consisted of 298 amino acids containing a signal peptides (29 amino acids) and a mature protein (269 amino acids), and had calculated molecular mass of 31,081 Da. The calculated molecular mass (28,229 Da) of the mature protein was almost same as that of the native chitinase determined by matrix-assisted laser desorption ionization time-of-flight mass spectrometer. Comparison of the encoded amino acid sequences with those of other chitinases showed that J-13-3 chitinase was a member of the glycosyl-hydrolase family 19 chitinases and the mature protein had a chitin binding domain (65 amino acids) containing AKWWTQ motif and a catalytic domain (204 amino acids). The J-13-3 strain had a single chitinase gene. The chitinase (298 amino acids) with C-terminal His tag was overexpressed in Escherichia coli BL21(DE3) cells. The recombinant chitinase purified from the cell extract had identical N-terminal amino acid sequence of the mature protein in spite of confirmation of the nucleotide sequence, suggesting that the signal peptide sequence is successfully cut off at the predicted site by signal peptidase from E. coli and will be a useful genetic tool in protein engineering for production of soluble recombinant protein. The optimum temperature and pH ranges of the purified chitinase were at 35-40 degrees C and 5.5-6.0, respectively. The purified chitinase hydrolyzed colloidal chitin and trimer to hexamer of N-acetylglucosamine and also inhibited the hyphal extension of Tricoderma reesei.

A new approach for the detection of multiple protein kinases using monoclonal antibodies directed to the highly conserved region of protein kinases.

To explore the protein kinase family enzymes expressed in cells, we attempted to generate antibodies that could detect a wide variety of protein kinases. For the production of such antibodies, synthetic peptides corresponding to amino acid sequences of a highly conserved subdomain (subdomain VIB) of the protein kinase family were used for immunization. Among the various peptide antigens, a peptide with 16 amino acids, CVVHRDLKPENLLLAS, effectively produced polyclonal antibodies with broad cross-reactivities to protein kinases. Two monoclonal antibodies, designated M8C and M1C, detected a variety of protein kinases such as calmodulin-dependent protein kinase II, calmodulin-dependent protein kinase IV, cAMP-dependent protein kinase, and mitogen-activated protein kinases, on Western blotting. The antibodies also immunoprecipitated various protein kinases in cell extracts. Furthermore, these antibodies could be used for detection of positive clones in the expression cloning of various protein kinases. Among 39 positive clones obtained from mouse brain cDNA library, 36 clones were identified as cDNA clones for various known and novel protein serine/threonine kinases, suggesting that the antibodies reacted highly specifically with various protein kinases. These results indicate that the present monoclonal antibodies directed to multiple protein kinases will be a powerful tool for the detection of a variety of known and novel protein kinases in cells.

Possible antitumor promoters in Spinacia oleracea (spinach) and comparison of their contents among cultivars.

Spinach leaves were found to contain two potent antitumor promoters as detected by the activity against tumor promoter-induced Epstein-Barr virus activation. The active components were identified as 1-O-alpha-linolenoyl-2-O-(7Z,10Z,13Z)-hexadecatrienoyl-3-O-beta-D-galactopyranosyl-sn-glycerol and 1,2-di-O-alpha-linolenoyl-3-O-beta-D-galactopyranosyl-sn-glycerol by spectroscopic data and some chemical and enzymatic reactions. Their contents significantly varied with the cultivar and with the culture conditions.