Draft Genome Sequences of Two Strains of Bifidobacterium dentium Isolated from a Crude Fecal Extract Used for Fecal Microbiota Transplantation in the Republic of Korea.

We present the draft genome sequences of two Bifidobacterium dentium strains isolated from a fecal extract for fecal microbiota transplantation at a hospital in the Republic of Korea. Phylogenetic and functional analyses were performed to understand the physiological characteristics and functions of Bifidobacterium spp. in the human intestine.

Isolation and characterization of five novel probiotic strains from Korean infant and children faeces.

Probiotics are dietary supplements containing viable, non-pathogenic microorganisms that interact with the gastrointestinal microflora and directly with the immune system. The possible health effects of probiotics include modulating the immune system and exerting antibacterial, anticancer, and anti-mutagenic effects. The purpose of this study was to isolate, identify, and characterize novel strains of probiotics from the faeces of Korean infants. Various assays were conducted to determine the physiological features of candidate probiotic isolates, including Gram staining, 16S rRNA gene sequencing, tolerance assays to stimulated gastric juice and bile salts, adherence ability assays, antibiotic susceptibility testing, and assays of immunomodulatory effects. Based on these morphological and biochemical characteristics, five potential probiotic isolates (Enterococcus faecalis BioE EF71, Lactobacillus fermentum BioE LF11, Lactobacillus plantarum BioE LPL59, Lactobacillus paracasei BioE LP08, and Streptococcus thermophilus BioE ST107) were selected. E. faecalis BioE EF71 and L. plantarum BioE LPL59 showed high tolerance to stimulated gastric juice and bile salts, and S. thermophilus BioE ST107 as well as these two strains exhibited stronger adherence ability than reference strain Lactobacillus rhamnosus GG. All five strains inhibited secretion of lipopolysaccharide-induced pro-inflammatory cytokines IL-6 and TNF-α in RAW264.7 macrophages in vitro. L. fermentum BioE LF11, L. plantarum BioE LPL59, and S. thermophilus BioE ST107 enhanced the production of anti-inflammatory cytokine IL-10. Overall, our findings demonstrate that the five novel strains have potential as safe probiotics and encouraged varying degrees of immunomodulatory effects.

Characterization of the fecal microbiota differs between age groups in Koreans.

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.

Metformin Facilitates Amyloid-ß Generation by ß- and γ-Secretases via Autophagy Activation.

The evidence of strong pathological associations between type 2 diabetes and Alzheimer's disease (AD) has increased in recent years. Contrary to suggestions that anti-diabetes drugs may have potential for treating AD, we demonstrate here that the insulin sensitizing anti-diabetes drug metformin (Glucophage®) increased the generation of amyloid-ß (Aß), one of the major pathological hallmarks of AD, by promoting ß- and γ-secretase-mediated cleavage of amyloid-ß protein precursor (AßPP) in SH-SY5Y cells. In addition, we show that metformin caused autophagosome accumulation in Tg6799 AD model mice. Extremely high γ-secretase activity was also detected in autophagic vacuoles, apparently a novel site of Aß peptide generation. Together, these data suggest that metformin-induced accumulation of autophagosomes resulted in increased γ-secretase activity and Aß generation. Additional experiments indicated that metformin increased phosphorylation of AMP-activated protein kinase, which activates autophagy by suppressing mammalian target of rapamycin (mTOR). The suppression of mTOR then induces the abnormal accumulation of autophagosomes. We conclude that metformin, an anti-diabetes drug, may exacerbate AD pathogenesis by promoting amyloidogenic AßPP processing in autophagosomes.

Disruption of blood-brain barrier in Alzheimer disease pathogenesis.

Blood-brain barrier (BBB) regulates transport of various molecules and maintains brain homeostasis. Perturbed intracellular Ca(2+) homeostasis and BBB damage have been implicated in the pathogenesis of Alzheimer disease (AD). Although receptor for advanced glycation end products (RAGE) is known to mediate Aß transcytosis across the BBB, molecular mechanisms underlying Aß-RAGE interaction-induced BBB alterations are largely unknown. We found enhanced permeability, decreased zonula occludin-1 (ZO-1) expression and increased intracellular calcium and MMP secretion in endothelial cells exposed to Aß1-42. Aß-induced changes in ZO-1 were attenuated by neutralizing antibodies against RAGE and inhibitors of calcineurin (CaN) and MMPs, suggesting that Aß-RAGE interactions disrupt tight junction proteins via the Ca(2+)-CaN pathway. We also found disrupted microvessels near Aß plaque-deposited areas, elevated RAGE expression and enhanced MMP secretion in microvessels of the brains of 5XFAD mice, an animal model of AD. These results identify a potential molecular pathway underlying Aß-RAGE interaction-induced breakage of BBB integrity.

Aß1₋42-RAGE interaction disrupts tight junctions of the blood-brain barrier via Ca²âº-calcineurin signaling.

The blood-brain barrier (BBB), which is formed by adherens and tight junctions (TJs) of endothelial cells, maintains homeostasis of the brain. Disrupted intracellular Ca²âº homeostasis and breakdown of the BBB have been implicated in the pathogenesis of Alzheimer's disease (AD). The receptor for advanced glycation end products (RAGE) is known to interact with amyloid ß-peptide (Aß) and mediate Aß transport across the BBB, contributing to the deposition of Aß in the brain. However, molecular mechanisms underlying Aß-RAGE interaction-induced alterations in the BBB have not been identified. We found that Aß1₋42 induces enhanced permeability, disruption of zonula occludin-1 (ZO-1) expression in the plasma membrane, and increased intracellular calcium and matrix metalloproteinase (MMP) secretion in cultured endothelial cells. Neutralizing antibodies against RAGE and inhibitors of calcineurin and MMPs prevented Aß1₋42-induced changes in ZO-1, suggesting that Aß-RAGE interactions alter TJ proteins through the Ca²âº-calcineurin pathway. Consistent with these in vitro findings, we found disrupted microvessels near Aß plaque-deposited areas, elevated RAGE expression, and enhanced MMP secretion in microvessels of the brains of 5XFAD mice, an animal model for AD. We have identified a potential molecular pathway underlying Aß-RAGE interaction-induced breakage of BBB integrity. This pathway might play an important role in the pathogenesis of AD.

Intracellular amyloid-ß accumulation in calcium-binding protein-deficient neurons leads to amyloid-ß plaque formation in animal model of Alzheimer's disease.

One of the major hallmarks of Alzheimer's disease (AD) is the extracellular deposition of amyloid-ß (Aß) as senile plaques in specific brain regions. Clearly, an understanding of the cellular processes underlying Aß deposition is a crucial issue in the field of AD research. Recent studies have found that accumulation of intraneuronal Aß (iAß) is associated with synaptic deficits, neuronal death, and cognitive dysfunction in AD patients. In this study, we found that Aß deposits had several shapes and sizes, and that iAß occurred before the formation of extracellular amyloid plaques in the subiculum of 5XFAD mice, an animal model of AD. We also observed pyroglutamate-modified Aß (N3pE-Aß), which has been suggested to be a seeding molecule for senile plaques, inside the Aß plaques only after iAß accumulation, which argues against its seeding role. In addition, we found that iAß accumulates in calcium-binding protein (CBP)-free neurons, induces neuronal death, and then develops into senile plaques in 2-4-month-old 5XFAD mice. These findings suggest that N3pE-Aß-independent accumulation of Aß in CBP-free neurons might be an early process that triggers neuronal damage and senile plaque formation in AD patients. Our results provide new insights into several long-standing gaps in AD research, namely how Aß plaques are formed, what happens to iAß and how Aß causes selective neuronal loss in AD patients.

Isolation and characterization of postnatal stem cells from human dental tissues.

It was reported that postnatal stem cells are present in adult tissues such as bone marrow, liver, muscle, dental pulp, and periodontal ligament. We isolated postnatal stem cells from human dental tissues such as dental pulp (DPSC), periodontal ligament (PDLSC), periapical follicle (PAFSC), and the surrounding mandibular bone marrow (MBMSC) to ascertain their properties. Immunocytochemistry proved the existence of stem cells in these cell populations using STRO-1 as a stem cell marker. These cells also expressed the mesenchymal stem cell (MSC) markers CD29 and CD44. The isolated cells showed self-renewal capabilities and colony-forming efficiency. Almost all of the dental stem cells showed optimal growth when they were cultured in alpha modification of Eagle's medium (alpha-MEM) supplemented with 10% fetal calf serum (FCS) and 100 microM ascorbic acid. Only the PAFSC showed increased proliferation in 20% FCS and 50 microM ascorbic acid. All of the dental stem cells were capable of differentiating into adipocytes and mineral nodule forming cells. MBMSC, in particular, showed much better mineralization compared to the others. These results indicate that MSCs exist in various tissues of the teeth and can differentiate into osteoblasts, adipocytes, and other kinds of cells with varying efficiency.