Yuxing Guo

Antioxidant and immunomodulatory activity of selenium exopolysaccharide produced by Lactococcus lactis subsp. lactis.

Exopolysaccharide (EPS) was isolated and purified from Lactococcus lactis subsp. Lactis culture broth. Selenium chloride oxide (SeCl(2)O) was added to the EPS to synthesize selenium-exopolysaccharide (Se-EPS). The in vitro and in vivo antioxidant and in vivo immunomodulatory activity of EPS and Se-EPS were compared. EPS and Se-EPS scavenged superoxide anions and hydroxyl radicals. They also increased catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity, while decreasing malondialdehyde (MDA) levels in serum and in the livers of mice. Se-EPS showed stronger in vitro and in vivo antioxidant activity than were shown by EPS. The in vivo immunoenhancement activity of EPS and Se-EPS induced by cyclophosphamide (CY) treatment in immunosuppressed mice was researched. EPS and Se-EPS treatments increased macrophage phagocytosis, spleen and thymus indices and haemolytic complement activity (HC(50)). Se-EPS showed stronger immunomodulatory activity than did EPS.

The probiotic properties of Lactobacillus buchneri P2

Aims:  To isolate new lactobacilli strain with cholesterol‐lowering effect and analyse its probiotic properties and possible mechanisms of cholesterol removal.

Structure and anti-inflammatory capacity of peptidoglycan from Lactobacillus acidophilus in RAW-264.7 cells.

Probiotic bacteria, especially the Lactobacillus species, can potentially play a significant role in the antiviral and antimicrobial activity of a hosts immune system. Lactobacillus acidophilus, an intestinal bacterium, is involved in the intestinal epithelial cell response when a pathogen adheres to a cell. In this study, the structure of peptidoglycan (PGN) isolated from L. acidophilus was determined with the help of HPLC, NMR, FT-IR and MALDI-TOF/TOF MS. The molecular mass of PGN is 875.260 Da. The anti-inflammatory capacity of PGN was evaluated in model RAW 264.7 cells. Epifluorescence microscopy images and western blot analysis provided compelling evidence of PGNs anti-inflammatory capacity on LPS-induced macrophages. A significant decrease in inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) levels when PGN was added up to 200 μg/ml. These data provide new insight into the cellular and molecular mechanisms by which probiotic bacteria can contribute to maintaining good health.

Immunomodulatory activity of selenium exopolysaccharide produced by Lactococcus lactis subsp. Lactis

Exopolysaccharide (EPS) was isolated and purified from Lactococcus lactis subsp. Lactis culture and then selenium chloride oxide (SeCl2O) was added to synthesise selenium-exopolysaccharide (Se-EPS). This study sought to evaluate the immunomodulatory effects of EPS and Se-EPS on the activity of peritoneal macrophages and spleen lymphocytes. In mouse peritoneal macrophages, the EPS and Se-EPS enhanced phagocytosis and increased nitric oxide (NO), IFN-γ, IL-1, IL-6 and IL-12 secretion, but not IL-10 levels. Preliminary in vitro tests revealed that EPS and Se-EPS stimulated mouse spleen lymphocyte proliferation, and strongly improved levels of TNF-α, IL-2 and IL-6 mRNA in spleen cells. These findings indicate that EPS and Se-EPS can enhance the immune response via enhanced macrophage and spleen lymphocyte stimulation. Se-EPS showed stronger immunomodulatory activity than EPS.

Antioxidant activity of phosphorylated exopolysaccharide produced by Lactococcus lactis subsp. lactis

Exopolysaccharide (EPS) of Lactococcus lactis subsp. lactis was isolated and purified from MRS culture broth. Phosphorylated exopolysaccharide (P-EPS) was synthesized by using the purified EPS and sodium hexametaphosphate (SHMP). The in vitro and in vivo antioxidant activity of EPS and P-EPS was analyzed. Both EPS and P-EPS displayed superoxide anion (O(2-•)), hydroxyl radical (OH•) and DPPH scavenging activity. Catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity increased in serum and the livers of mice treated with EPS and P-EPS, while malondialdehyde (MDA) levels decreased. P-EPS was shown to prevent the progression of D-galactose-induced oxidative stress in hepatocytes in vivo. P-EPS showed stronger in vitro and in vivo antioxidant activity than EPS.

Peptidoglycan diversity and anti-inflammatory capacity in Lactobacillus strains.

Lactobacillus species are potential probiotic bacteria for humans because of their capacity to improve certain biological functions in the hosts immune system. In this study, we focused on three peptidoglycans (PGNs) derived from different Lactobacillus strains and investigated each PGNs anti-inflammatory capacity. Each PGN was analyzed using HPLC, MALDI-TOF/TOF MS and FTIR. All three PGNs displayed a β-1,4-linked N-acetylmuramic acid (MurNAc) and N-acetylglucosamine (GlcNAc) structure with some modifications in the polypeptides at the end of the MurNAc residue. In a new insight, we found that PGNs inhibit the release of inflammatory cytokines in LPS-induced RAW 264.7 cells; a capacity that may be related to the TLR-4 pathway. The goal for exploring PGN diversity in Lactobacillus strains is to better understand the potential use of Lactobacillus PGNs in food and pharmaceutical applications.

Antialcoholic liver activity of whey fermented by Lactobacillus casei isolated from koumiss

Whey fermented liquid (WFL) was studied for its hepatoprotective effects by using chronic alcohol-induced mice. Whey fermented liquid, prepared by inoculating whey with 4% (vol/vol) Lactobacillus casei and then incubating at 41°C for 8h, was used to orally treat alcohol-induced mice at 3 dosages for 5 wk. Ethanol consumption significantly reduced the activity of superoxide dismutase and glutathione peroxidase, while lowering glutathione content and increasing levels of aspartate aminotransferase, alanine aminotransferase, total triglyceride, malondialdehyde, and cytochrome P450 2E1. Treatment with WFL significantly attenuated the increased levels of alanine aminotransferase, aspartate aminotransferase, triglyceride, and cytochrome P450 2E1, while decreasing superoxide dismutase, glutathione peroxidase, malondialdehyde, and glutathione levels. Pathological changes in the livers of mice who had ingested alcohol were improved by the administration of WFL. These results suggest that WFL may exert a protective effect against alcoholic liver disease by increasing antioxidant activity, which supports the use of WFL as an antialcoholic liver disease treatment.

Transepithelial transport of milk-derived angiotensin-I converting enzyme inhibitory peptide with the RLSFNP sequence

BACKGROUND To exert an antihypertensive effect after oral administration, angiotensin I-converting enzyme (ACE)-inhibitory peptides must remain active after intestinal transport. The purpose of this article is to elucidate the transport permeability and route of ACE-inhibitory peptide Arg-Leu-Ser-Phe-Asn-Pro (RLSFNP) across the intestinal epithelium using Caco-2 cell monolayers. RESULTS Intact RLSFNP and RLSFNP breakdown fragments F, FNP, SFNP and RLSF were found in RLSFNP transport solution across Caco-2 cell monolayers using ultra-performance liquid chromatography-tandem mass spectrometry. RLSFNP fragments FNP, SFNP and RLSF also contributed to ACE inhibitory effects. Protease inhibitors (bacitracin and leupeptin) and absorption enhancers (sodium glycocholate hydrate, sodium deoxycholate and Na2 EDTA) improved the transport flux of RLSFNP. A transport inhibitor experiment showed that intact RLSFNP may be transported via the paracellular route. CONCLUSION Intact RLSFNP can be transported across the Caco-2 cell monolayers via the paracellular route. Extensive hydrolysis was the chief reason for the low permeability of RLSFNP.

Purification of Lactobacillus acidophilus surface‐layer protein and its immunomodulatory effects on RAW264.7 cells

BACKGROUND Surface-layer proteins (SLP) have been found in the outermost layer of the cell wall in many types of lactobacillus are considered to be an important factor with respect to intestinal immunity. RESULTS The present study compared the effects of SLP extracted by different concentrations of LiCl and carbamide, and subsequently identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, circular dichroism and differential scanning calorimetry. Furthermore, RAW 264.7 cells were used to evaluate the immunomodulatory effects of SLP. SLP were derived from Lactobacillus acidophilus CICC6074 with a molecular weight of 46 kDa, and consisted of 16.9% α-helix, 42.3% β-sheet, 20.8% β-turns and 22.5% random coils. SLP promoted NO secretion and higher quantities of NO were produced as the SLP concentrations increased. SLP concentrations over 50 µg mL-1 significantly decreased the amount of tumor necrosis factor-α secreted by RAW264.7 cells. CONCLUSION SLP can trigger immunomodulatory effects in RAW 264.7 cells. This provides crucial information that will enable the further use of L. acidophilus in food, medicine and other products.

Extraction of Lactobacillus acidophilus CICC 6074 S-Layer Proteins and Their Ability to Inhibit Enteropathogenic Escherichia coli

An adhesion-related protein of Lactobacillus acidophilus strain CICC 6074 involved in binding to Caco-2 cells and inhibiting Enteropathogenic Escherichia coli (EPEC) was isolated and characterized. The S-layer protein was extracted with 5M LiCl and the active fraction purified by gel filtration (G-75). The S-layer protein was visualized by SDS-PAGE and characterized by estimating the relative molecular weight using mass spectra. The inhibitory effect of L. acidophilus and its S-layer proteins on the ability of EPEC to adhere to cells was explored by using a Caco-2 cell model. The results suggest that the S-layer proteins of L. acidophilus are adhesive in nature and are involved in the competitive exclusion of EPEC from Caco-2 cells.