Guo-Wei Le

Increasing Oxidative Stress with Progressive Hyperlipidemia in Human: Relation between Malondialdehyde and Atherogenic Index

The aim of this study was to examine whether malondialdehyde (MDA) formation, a marker of oxidant stress, is altered in different stages of development of hyperlipidemia and whether it correlates with atherogenic index (AI), an important risk factor of atherosclerosis. Commercial kits were used to measure the levels of lipid profile and antioxidant status in the serum of 15 hyperlipidemic patients and 30 age and sex-matched normolipidemic subjects. The normolipidemic subjects were divided into lower and higher lipid groups according to their blood lipid level. The activities of superoxide dismutase and glutathione peroxidase decreased in higher lipid group compared with lower lipid group, and were even lower in hyperlipidemic subjects. An increase in the levels of MDA, triglycerides, total cholesterol and LDL-C concentration were observed in higher lipid group, and even significantly increased in hyperlipidemic patients. A significant progressive decline in HDL-C concentration was found during hyperlipidemia evolution. There was a positive correlation between MDA and AI (r = 0.61, p<0.05). These data indicate that oxidative stress is an early event in the evolution of hyperlipidemia, and appropriate support for enhancing antioxidant supply in higher lipid subjects may help prevent the course of the disease.

Lipoic acid prevents high-fat diet-induced dyslipidemia and oxidative stress : A microarray analysis

OBJECTIVEnWe previously found that lipoic acid (LA) improved high-fat diet (HFD)-induced dyslipidemia in rats. To elucidate the molecular mechanisms of that effect, we carried out experiments aimed at analyzing biochemical parameters and gene expression profiles.nnnMETHODSnC57BL/6 mice were randomly assigned to one of three groups (n = 8). The control group consumed an ordinary diet (4.89% fat, w/w). The other two experimental groups were fed with an HFD (21.45% fat, w/w) or an HFD plus 0.1% LA. After 6 wk, plasma lipid level and antioxidant status were examined. To investigate the molecular mechanisms underlying the effects of LA on lipid metabolism and oxidative stress, we examined gene expression profiles in liver using the GeneChip microarray system. The differential expression of genes of interest identified by microarray technique was validated by real-time reverse transcription-polymerase chain reaction.nnnRESULTSnHFD resulted in significant alterations in lipid profiles and a depressed antioxidant defense system. LA supplementation induced decreases in lipid peroxidation, plasma cholesterol, triacylglycerols, and low-density lipoprotein cholesterol and an increase in high-density lipoprotein in HFD-fed mice. DNA microarray analysis of the liver showed that LA ingestion upregulated the expression of genes related to beta-oxidation and free radical scavenger enzymes, whereas those involved in cholesterol synthesis were downregulated.nnnCONCLUSIONnLA can prevent HFD-induced dyslipidemia by modulating lipid metabolism, especially by increasing beta-oxidation and decreasing cholesterol synthesis, and oxidative stress by increasing those of free radical scavenger enzyme gene expression.

Lactobacilli prevent hydroxy radical production and inhibit Escherichia coli and Enterococcus growth in system mimicking colon fermentation

Aims:u2002 To explore the effect of Lactobacillus on redox state of colon chyme.

Expression of Genes Associated with Bone Resorption is Increased and Bone Formation is Decreased in Mice Fed a High-Fat Diet

A high-fat diet (HFD) leads to an increased risk of osteoporosis-related fractures, but the molecular mechanisms for its effects on bone metabolism have rarely been addressed. The present study investigated the possible molecular mechanisms for the dyslipidemic HFD-induced bone loss through comparing femoral gene expression profiles in HFD-fed mice versus the normal diet-fed mice during the growth stage. We used Affymetrix 430A Gene Chips to identify the significant changes in expression of the genes involved in bone metabolism, lipid metabolism, and the related signal transduction pathways. Quantitative RT-PCR was carried out on some significant genes for corroboration of the microarray results. At the conclusion of the 12-week feeding, the down-regulation of most of the genes related to bone formation and the up-regulation of most of the genes related to bone resorption were observed in the HFD-fed mice, consistent with the changes in plasma bone metabolic biomarkers. Together, the HFD induced a decrease in the majority of the adipogenesis-, lipid biosynthesis-, and fatty acid oxidation-related gene expression, such as PPARg and APOE. Furthermore, some genes engaged in the related signal transduction pathway were strongly regulated at the transcript level, including IGFBP4, TGFbR1, IL-17a, IL-4, and P53. These results indicate that an HFD may induce inhibitory bone formation and enhanced bone resorption, thus causing adverse bone status.

Lipoic acid attenuates high fat diet-induced chronic oxidative stress and immunosuppression in mice jejunum: a microarray analysis.

A high fat diet (HFD) has long been linked to immune dysfunction, including diminished numbers or reactivity of lymphocytes, increased susceptibility to infection, inhibited lymphocytes function during antigen-specific responses and developed oxidative stress. Whereas the molecular mechanistic events associated with immune deficiency remain to be fully determined. Using the DNA microarray system, we analyzed the gene expression patterns of lymphocyte related signal transduction proteins in jejunum of C57BL/6 mice in order to gain insight on the possible molecular mechanism by which HFD induced oxidative stress effects on signal transduction of lymphocytes. Results of present study showed that HFD induced oxidative stress and immunosuppression in jejunum. Antioxidant lipoic acid (LA) supplement ameliorated that HFD induced oxidative stress and immunosuppression by recovering transcriptional levels of the gene involved in B cell receptor, T cell differentiation signaling pathway, and free radical scavengers. The present study indicates that a HFD can induce chronic oxidative stress, suppress signal transduction of gut-associated lymphocytes, and lead to an inhibition of mucosal immunity.

High-fat-diet-induced obesity is associated with decreased antiinflammatory Lactobacillus reuteri sensitive to oxidative stress in mouse Peyer's patches

OBJECTIVEnDiet-induced inflammation in the small intestine may represent an early event that precedes and predisposes to obesity and insulin resistance. This is related to decrease of lactobacilli in Peyers patches (PP) revealed in our previous study. The present study aimed to clarify specific changes of PP Lactobacillus on the strain level and related biological activity.nnnMETHODSnC57 BL/6 J male mice were fed with either low-fat diet (control [CT]; 10% calories from fat) or high-fat diet (HFD; 50% calories from fat) for 25 wk, and the HFD-fed mice were classified into obesity prone (OP) or obesity resistant (OR) on the basis of their body weight gain. Lactobacillus was isolated from PP using a selective medium. Oxidative resistance and cytokine-inducing effect were analyzed in vitro.nnnRESULTSnWe obtained 52, 18, and 22 isolates from CT, OP, and OR mice, respectively. They belonged to 13 different types according to enterobacterial repetitive intergenic consensus sequence-PCR analysis. Lactobacillus reuteri was the most abundant strain, but its abundance in OP mice was much lower than that in CT and OR mice. This strain includes eight subgroups according to genotyping. L. reuteri L3 and L. reuteri L8 were the specific strains found in CT and OP mice, respectively. Oxidative-resistant L. reuteri was much higher in HFD-fed mice. When co-cultured with PP cells, L8 induced higher production of proinflammatory cytokines such as interleukin (IL)-6, IL-12, and tumor necrosis factor-α, whereas L3 induced higher production of an anti-inflammatory cytokine (IL-10).nnnCONCLUSIONnHFD may induce oxidative stress that drives strain selection of Lactobacillus strains, resulting in decreased anti-inflammatory response in PP.

Association of Lactobacillus acidophilus with mice Peyer's patches

OBJECTIVEnTo clarify the adhesion mechanism of Lactobacillus acidophilus to Peyers patches.nnnMETHODSnAdhesion of L. acidophilus FN001 to mice Peyers patches was studied in vitro using a fluorescent quantization method. The nature of adhesion mediator was studied by the differing effects of physical, chemical, and enzymatic pre-treatments of the bacteria and the inhibitory effects of sugars on the adhesion. The presence of lectin-like proteins on the cell surface was determined by hemagglutination assay. The effect of L. acidophilus FN001 on the inhibition of adhesion of pathogens to Peyers patches was also studied.nnnRESULTSnThe adhesion of L. acidophilus FN001 was strongly inhibited in the presence of D-mannose and methyl-α-D-mannoside. Pretreatment of L. acidophilus FN001 with pepsin and trypsin decreased the adhesive capacity indicating that some cell surface proteins might be involved in the adhesion. L. acidophilus FN001 showed agglutinating activity toward the rabbit red cells in a mannose specific manner, which was decreased after protease pretreatment, suggesting possible occurrence of mannose specific lectin(s) on the L. acidophilus FN001 surface. In adhesion inhibition assay, L. acidophilus NF001, when applied to Peyers patches first or at the same time with pathogen, significantly inhibited adhesion of Escherichia coli ATCC25922 to Peyers patches.nnnCONCLUSIONnL. acidophilus FN001 contains some mannose-specific protein(s) on its surface that mediates its adhesion to the Peyers patches. FN001 inhibits the adhesion of E. coli, which also contains mannose specific lectin.

Effects of Lactobacillus plant arum on genes expression pattern in mice jejunal Peyer's patches.

Jejunal Peyers patches contain specialized epithelial M cells that take up ingested microorganisms from the lumen of the gut by transcytosis. Using DNA-micro array, we analyzed the gene expression patterns of jejunal Peyers patches in order to gain insight into the molecular mechanism by which Lp6 interacted with the host organism in a gnotobiotic environment v. in the gut normal microflora. The micro array data revealed that, among approximately 14,000 genes, 420 were expressed in Lp6 administration group at twofold or higher levels compared to the control group. These included genes involved in immune response, and cell differentiation, cell-cell signaling, cell adhesion, signal transcription, and transduction. Real-time PCR confirmed the reliability of the analysis. These data indicated that administration of Lactobacillus Lp6 was associated with a complex genetic response in the jejunal Peyers patches.

Effect of GABA on oxidative stress in the skeletal muscles and plasma free amino acids in mice fed high-fat diet

Increased levels of plasma free amino acids (pFAAs) can disturb the blood glucose levels in patients with obesity, diabetes mellitus and metabolic syndrome (MS) and are associated with enhanced protein oxidation. Oxidation of proteins, especially in the muscles, can promote protein degradation and elevate the levels of pFAAs. Gamma-aminobutyric acid (GABA), a food additive, can reduce high-fat diet (HFD)-induced hyperglycaemia; however, the mechanisms remain unclear. The aim of this study was to evaluate the effects of GABA on protein oxidation and pFAAs changes. One hundred male C57BL/6 mice were randomly divided into five groups that were fed with control diet, HFD and HFD supplied with 0.2%, 0.12% and 0.06% GABA in drinking water for 20 weeks respectively. HFD feeding led to muscular oxidative stress, protein oxidation, pFAA disorders, hyperglycaemia and augmented plasma GABA levels. Treatment with GABA restored normally fasting blood glucose level and dose-dependently inhibited body weight gains, muscular oxidation and protein degradation. While medium and low doses of GABA mitigated HFD-induced pFAA disorders, the high dose of GABA deteriorated the pFAA disorders. Medium dose of GABA increased the levels of GABA, but high dose of GABA reduced the levels of plasma GABA and increased the activity of succinic semialdehyde dehydrogenase in the liver. Therefore, treatment with GABA mitigated HFD-induced hyperglycaemia probably by repairing HFD-induced muscular oxidative stress and pFAA disorders in mice. Our data also suggest that an optimal dose of GABA is crucial for the prevention of excess GABA-related decrease in the levels of pFAA and GABA as well as obesity.

Isolation of lactobacillus reuteri from Peyer's patches and their effects on sIgA production and gut microbiota diversity

SCOPEnWe previously reported that specific Lactobacillus reuteri colonized within mouse Peyers patches (PP) effectively prevented high fat diet induced obesity and low-grade chronic inflammation. We further investigated the role of PP Lactobacillus reuteri on sIgA production in rats in this study.nnnMETHODS AND RESULTSnLactobacilli were isolated from rat PP. All isolates were L. reuteri and belonged to three phenotypes according to amplified fragment length polymorphism analysis. Typical strains of two main clusters, PP1 and PP2, were used to treat control and vitamin A deficient (VAD) rats, respectively. The feeding of PP1 and PP2 affected sIgA and Lactobacillus diversity by strain-specific manner. Free sIgA was significantly increased by PP1 (p = 0.069) and PP2 (p < 0.05) in the control rats but not in the VAD rats. Only PP1 significantly changed PP Lactobacillus diversity in the control rats (p < 0.05). However, PP2 specifically changed ileal Lactobacillus diversity in both control and VAD rats. Fecal sIgA was correlated with PP Lactobacillus diversity (R(2) = 0.7958, p = 0.011).nnnCONCLUSIONnModulation of sIgA production by PP L. reuteri of rat is dependent on vitamin A and change of Lactobacillus diversity in PP.