Screening for cholesterol-lowering probiotic based on deoxycholic acid removal pathway and studying its functional mechanisms in vitro

Effects of Probiotic Enterococcus faecium from Yak on the Intestinal Microflora and Metabolomics of Mice with Salmonella Infection

Salmonella spp. are pathogenic bacteria that cause diarrhea, abortion, and death in yak and severely harm livestock breeding. Therefore, it is vital to identify a probiotic that effectively antagonizes Salmonella. To the best of our knowledge, few prior studies have investigated the efficacy of Enterococcus faecium against Salmonella. Here, we evaluated the enteroprotective mechanism of E. faecium in a mouse Salmonella infection model using hematoxylin-eosin (H&E) staining, quantitative real-time polymerase chain reaction (Q-PCR) technology, microbial diversity sequencing, and metabonomics. Enterococcus faecium inhibited the proinflammatory cytokines IL-1β, IL-6, TNF-α, and IFN-γ and promoted the anti-inflammatory cytokine IL-10. The Firmicutes/Bacteroidota (F/B) ratio and the abundances of Firmicutes and Akkermansia were significantly higher in the E. faecium than in the Salmonella group. Metabonomics and microbial diversity sequencing disclosed five different metabolites with variable importance in the projection (VIP) > 3 that were characteristic of both the Salmonella and E. faecium groups. Combined omics revealed that Lactobacillus and Bacteroides were negatively and positively correlated, respectively, with cholic acid, while Desulfovibrio was positively correlated with lipids in both the control and Salmonella groups. Desulfovibrio was also positively correlated with lipids in both the Salmonella and E. faecium groups. Enterococcus faecium antagonizes Salmonella by normalizing the abundance of the intestinal microorganisms and modulating their metabolic pathways. Hence, it may efficaciously protect the host intestine against Salmonella infection.

Hypocholesterolemic potential of Bacillus amyloliquefaciens KAVK1 modulates lipid accumulation on 3T3-L1 adipose cells and high fat diet-induced obese rat model

The significance of microorganisms occurring in foods is predominantly targeted due to their application for identifying a novel range of the bacterial spectrum. Diverse microbial species are capable of exhibiting potential pharmacological activities like antimicrobial and anticancer. Microbial strains capable of reducing obesity-related syndromes have also been reported. In the present study, the hypocholesterolemic efficacy of Bacillus amyloliquefaciens isolated from dairy products was scrutinised by in vitro (3T3-L1 adipose cells) and in vivo (high-fat diet-induced obese Wistar albino rats) methods. Potential cholesterol-lowering isolates were screened using a plate assay method and optimised by physical parameters. Molecular identification of the topmost five cholesterol-lowering isolates was acquired by amplification of the 16 S rRNA gene region. Bacillus amyloliquefaciens strain KAVK1, followed by strains KAVK2, KAVK3, KAVK4, and KAVK5 were molecularly determined. Further, cholesterol-lowering strains degraded the spectral patterns determined by the side chain of a cholesterol molecule. The anti-lipase activity was demonstrated using the porcine pancreatic lipase inhibitory method and compared with the reference compound Atorvastatin. Lyophilised strain KAVK1 revealed maximum pancreatic lipase inhibition. Strain KAVK1 attenuated lipid accumulation in 3T3-L1 adipose cell line predicted by Oil Red O staining method. Significant reduction of body weight and change in lipid profile was recognised after the supplement of KAVK1 to obese rats. Histopathological changes in organs were predominantly marked. The result of this study implies that the cholesterol-lowering B. amyloliquefaciens KAVK1 strain was used to treat hypercholesterolemia.

Engineered Living Materials for Advanced Diseases Therapy

Natural living materials serving as biotherapeutics exhibit great potential for treating various diseases owing to their immunoactivity, tissue targeting, and other biological activities. In this review, the recent developments in engineered living materials, including mammalian cells, bacteria, viruses, fungi, microalgae, plants, and their active derivatives that are used for treating various diseases are summarized. Further, the future perspectives and challenges of such engineered living material-based biotherapeutics are discussed to provide considerations for future advances in biomedical applications.

High Antioxidant Capacity of Lacticaseibacillus paracasei TDM-2 and Pediococcus pentosaceus TCM-3 from Qinghai Tibetan Plateau and Their Function towards Gut Modulation

Probiotic supplementation is a key therapeutic strategy for promoting gut health and maintaining gut homeostasis by modulating functional microbiota. In this study, we isolated two lactic acid bacteria (LAB) strains, Pediococcus pentosaceus TCM-3 and Lacticaseibacillus paracasei TDM-2, from Qinghai-Tibetan plateau, and evaluated their probiotic properties and antioxidant bioactivity. In which, TDM-2 had higher T-AOC activity than either TCM-3 or LGG (4.10 μmol/mL vs. 3.68 and 3.53 μmol/mL, respectively, p < 0.05). These strains have shown high antioxidant activity compared to the LAB strains and were found to be acid and bile salt tolerant, confronting the safety issues of antibiotic resistance and the capability of surviving in simulated gastric and intestinal juices. In vitro fermentation experiments with human gut microbiota revealed significant differences in microbial community composition between samples supplemented with TCM-3 and TDM-2 and those without. The addition of these two strains resulted in an enrichment of beneficial taxa, such as the Pediococcus, Lactobacillus, and Clostridium_sensu_strictos at the genus level, and Firmicutes and Proteobacteria at the phylum level. Notably, the TCM-3 group exhibited higher short-chain fatty acid production than the TDM-2 group and untreated controls (acetic acid at 12 h: 4.54 mmol L^-1 vs. 4.06 mmol L^-1 and 4.00 mmol L^-1; acetic acid at 24 h: 4.99 mmol L^-1 vs. 4.90 mmol L^-1 and 4.82 mmol L^-1, p < 0.05). These findings demonstrate that LAB supplementation with high antioxidant capacity and probiotic properties can promote gut health by modulating functional microbiota and is enriching for beneficial taxa. Our study provides guidance for therapeutic strategies that use novel LAB strains to maintain gut homeostasis and functional microbiota modulation.

Akkermansia muciniphila Suppresses High-Fat Diet-Induced Obesity and Related Metabolic Disorders in Beagles

Obesity is one of the prevalent chronic diseases in human and companion animals usually associated with several metabolic disorders. The gut commensal bacterium Akkermansia muciniphila (A. muciniphila) is known for its therapeutic effects on metabolic disorders and inflammations. Here, we isolated the A. muciniphila AKK2 strain from the feces of interferon-inducible protein 204^−/− (IFI204^−/−) mice and further evaluated its anti-obesity effects on high-fat diet (HFD)-fed C57BL/6J mice and beagles. The results showed that it effectively controlled weight gain. Microbiome analysis using 16S rRNA gene sequencing revealed that HFD alters gut microbiota composition and A. muciniphila AKK2 increases the Firmicutes/Bacteroidetes (F/B) ratio in beagles. Furthermore, we prepared microcapsules containing A. muciniphila AKK2, and tolerance tests showed the encapsulation maintained high viability and stability in an aerobic environment and simulated the secretion of gastrointestinal fluids. Overall, this study widens the spectrum of A. muciniphila applications to prevent obesity.

Bile acids in immunity: Bidirectional mediators between the host and the microbiota

Host-microbiota interactions are bidirectional. On one hand, ecological pressures exerted by the host shape the composition and function of the microbiota. On the other, resident microbes trigger multiple pathways that influence the immunity of the host. Bile acids participate in both parts of this interplay. As host-derived compounds, they display bacteriostatic properties and affect the survival and growth of the members of the microbial community. As microbiota-modified metabolites, they further influence the microbiota composition and, in parallel, modulate the immunity of the host. Here, we provide a comprehensive overview of the mechanisms behind this unique dialogue and discuss how we can harness bile acids to treat intestinal inflammation.

Hierarchy-Assembled Dual Probiotics System Ameliorates Cholestatic Drug-Induced Liver Injury via Gut-Liver Axis Modulation

Cholestatic drug-induced liver injury (DILI) induced by drugs or other xenobiotics is a severe and even fatal clinical syndrome. Here, living materials of hierarchy-assembled dual probiotics system are fabricated by sequentially encapsulating probiotic Lactobacillus delbrueckii subsp. bulgaricus (LDB) and Lactobacillus rhamnosus GG (LGG) into Ca²⁺ -complexed polymer microspheres for effective prevention of cholestatic DILI. Upon entering intestinal tract of the constructed living materials, LGG is released because of pH-triggered dissolution of outer enteric polymer coating. The released LGG can inhibit hepatic bile acids (BAs) synthesis by activating intestinal farnesoid X receptor-fibroblast growth factor 15（FGF-15) signaling pathway. BAs excretion is also facilitated by LGG through increasing the abundance of bile salt hydrolase (BSH)-active gut commensal bacteria. Furthermore, exposed positively-charged chitosan shell can absorb the excessive BAs via electrostatic interaction, which leads to steady BAs fixation by the imprisoned LDB, decreasing the total BAs amounts in enterohepatic circulation. Together, the fabricated living materials, obtained here, can effectively prevent cholestatic DILI through dredging cholestasis via gut-liver axis modulation. The therapeutic effect is demonstrated in α-naphthylisothiocyanate and clinical antiepileptic drug valproate acid-induced cholestatic DILI mouse models, which reveal the great potential for effective cholestatic DILI management.

Probiotic properties of novel probiotic Levilactobacillus brevis KU15147 isolated from radish kimchi and its antioxidant and immune-enhancing activities

This study was conducted to evaluate the probiotic properties and antioxidant activities of lactic acid bacteria strains including Levilactobacillus brevis KU15147 isolated from kimchi to determine their potential as a probiotic. The tolerance of all strains to gastric acid and bile salts was more than 90%. The strains did not produce a β-glucuronidase and survived following treatment with gentamicin, kanamycin, streptomycin, and ciprofloxacin. L. brevis KU15147 showed greater adhesion activity to HT-29 cells (6.38%) and its antioxidant activities were higher than those of other tested strains, showing values of 38.56%, 22%, and 23.82% in DPPH, ABTS, and β-carotene bleaching assays, respectively. Additionally, the relative expression intensities of induced nitric oxide synthase and tumor necrosis factor-α of L. brevis KU15147 were greater than those of other strains, suggesting that this strain can be applied in the health food or pharmaceutical industry as a novel probiotic strain.

Probiotic Properties and Antioxidant Activities of Pediococcus pentosaceus SC28 and Levilactobacillus brevis KU15151 in Fermented Black Gamju

Black gamju is Korean traditional beverage fermented with molds. The aim of this study was to assess the probiotic properties and antioxidant activities of novel Pediococcus pentosaceus SC28 and Levilactobacillus brevis KU15151 to develop black gamju with bioactive properties for health. Tolerance against artificial gastric juice and bile salts, adhesion ability on HT-29 cells of strains, and antibiotics susceptibility were evaluated as probiotics, and various enzyme productions were detected. The 2,2-diphenyl-1-picrylhydrazyl assay, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate, and β-carotene bleaching assay were used for antioxidant activity of samples. The tolerance of both strains to artificial gastric juice and bile salts (Oxgall) was more than 90%. Additionally, both strains did not produce β-glucuronidase and were resistant to gentamicin, kanamycin, streptomycin, and ciprofloxacin. After fermentation of black gamju with each strain, the number of viable lactic acid bacteria increased to 8.25-8.95 log colony forming unit/mL, but the pH value of fermented samples decreased more (to pH 3.33-3.41) than that of control (pH 4.37). L. brevis KU15151 showed higher adhesion activity to HT-29 cells and antioxidant effects than P. pentosaceus SC28 in three antioxidant assays.

Effect of lotus seed resistant starch on tolerance of mice fecal microbiota to bile salt

We investigated the effect of lotus seed resistant starch (LRS) on mice fecal microbiota tolerance to bile salt by culturing organisms compared to inulin (INU) glucose (GLU) and waxy corn starch (WAX). Operational taxonomic units (OTUs) and diversity indices in LRS and INU groups were increased in the presence of 0.03% to 0.3% bile salt, while they were decreased in GLU, and OTUs were decreased in WAX. Specifically, LRS promoted proliferation of Lactobacillus, which potentially used bile acid, and inhibited growth of the potentially harmful bacteria Enterococcus and Staphylococcus. Moreover, Lactobacillus was negatively correlated with Salinicoccus and Granulicatella in GLU, LRS and INU groups at 1.5% bile salt. With LRS, amino acid metabolic pathways were increased while pathogens causing certain diseases were decreased. LRS increased the tolerance of mice fecal microbiota to bile salt by promoting the proliferation of bacteria utilizing bile acid and inhibiting the growth of harmful bacteria.

Lactulose: Patient- and dose-dependent prebiotic properties in humans

Lactulose is a disaccharide used in clinical practice since 1957 and has since been tested in the treatment of many human disorders, including chronic constipation, hepatic encephalopathy, and chronic kidney disease. Its mode of action is based on the lactulose fermentation by intestinal microbiota. Based on in silico, in vitro and in vivo studies we comprehensively review here the impact of lactulose on human gut/fecal and vaginal microbiota composition and both fecal and blood metabolomes. However, both in vitro and in vivo studies summarized in this review have revealed that the effects of lactulose on human microbiota composition are both patient- and dose-dependent. This highlights the need of heterogeneity indication in clinical trials.

Undernutrition Shapes the Gut Microbiota and Bile Acid Profile in Association with Altered Gut-Liver FXR Signaling in Weaning Pigs

Bile acids, synthesized in the liver and metabolized by microbiota, have emerged as important signaling molecules regulating immune responses and cell proliferation. However, the crosstalk among nutrition, microbiota, and bile acids remains unclear. Our study indicated that undernutrition in weaning piglets led to intestinal atrophy, increased colonic production, and systemic accumulation of lithocholic acid (LCA), deoxycholic acid (DCA), or their conjugated forms, which might be associated with decreased Lactobacillus abundance. Moreover, undernutrition led to increased portal fibroblast growth factor 19 ( FGF19) level, upregulated hepatic heterodimer partner ( SHP), and downregulated cholesterol 7a-hydroxylase ( CYP7A1) expression. The detrimental effects of DCA and LCA on proliferation and barrier function were confirmed in porcine enterocytes, whereas their roles in weaning piglets warrant further research. In summary, undernutrition in weaning piglets led to increased secondary bile acids production, which might be related to altered gut microbiome and enhanced farnesoid X receptor (FXR) signaling while CYP7A1 expression was suppressed.

Cholesterol lowering by Pediococcus acidilactici LAB4 and Lactobacillus plantarum LAB12 in adult zebrafish is associated with improved memory and involves an interplay between npc1l1 and abca1

This study assessed the cholesterol lowering effect of Pediococcus acidilactici LAB4 and Lactobacillus plantarum LAB12 using adult zebrafish. Animals were fed with a high cholesterol diet (HCD) with/without LAB for seven weeks. Serum and liver cholesterol was quantified using colorimetric and dye staining methods. Expressions of npc1l1 and abca1 in the liver and intestine and appa in the brain were quantified using RT-PCR. Serum and liver cholesterol was significantly lowered in LAB4- and LAB12-fed zebrafish (≤64% and ≤71%, respectively), with reduced liver cholesterol deposition. The cholesterol lowering effect was accompanied by down-regulation of npc1l1 in intestines (≤28.7%), up-regulation of abca1 in the liver (≥30.5%) and down-regulation of appa in the brain (≤24.5%). A moderately strong positive Pearson correlation (r = 0.617, p < 0.01) was found between appa and serum cholesterol. LAB-fed zebrafish exhibited improved spatial learning and memory. LAB4 and LAB12 can be potentially used in preventing hypercholesterolaemia and Alzheimer's diseases.

Probiotics: definition, scope and mechanisms of action

For a subject area of science, medicine and commerce to be so recently defined and investigated, few can compare to probiotics for the controversy they have incited. Barely a paper is published without the use of a different definition, or challenging the most used one, or proposing a different nuance of it. The situation has become even more surreal with the European Food and Safety Authority banning the word probiotic for use on labels. The reiteration of the FAO/WHO definition by the world's leading group of probiotic experts, should provide relative consistency in the near future, but what are the causes of these aberrations? This review will discuss the rationale for the definition, and the scope of the subject area and why alternatives emerge. While mechanisms of action are not widely proven, in vitro and some in vivo experiments support several. Ultimately, the goal of any field or product is to be understood by lay people and experts alike. Probiotics have come a long way in 100 years since Metchnikoff and 10 years since their globalization, but their evolution is far from over.

Effects of probiotics consumption on lowering lipids and CVD risk factors: a systematic review and meta-analysis of randomized controlled trials

This meta-analysis examined the effect of probiotics on the reduction of lipid components and coexisting risk factors associated with cardiovascular disease. All randomized controlled trials published in English on PubMed and Scopus from 2000 to 2014 were systematically searched. Using the PEDro scale to assess the quality of studies, a total of 15 studies with 788 subjects were selected for inclusion in the analysis. The mean difference and effect size with a 95% confidence interval (CI) were extracted from individual studies. Statistically significant pooled effects of probiotics were found on reduction of total cholesterol, low-density lipoprotein (LDL), body mass index (BMI), waist circumference, and inflammatory markers. Subgroup analysis revealed statistically significant effects of probiotics on total cholesterol and LDL when the medium was fermented milk or yogurt (P < 0.001) compared to capsule form, consumption was at least 8 weeks in duration (P < 0.001), and the probiotics consisted of multiple strains (P < 0.001) rather than a single strain. A significant reduction was found in LDL in trials which contained Lactobacillus Acidophilus strain (P < 0.001) compared to other types of strains. Our findings suggest that probiotic supplementation use is effective in lowering the lipid level and coexisting factors associated with cardiovascular disease.

Lactobacillus surface layer proteins: structure, function and applications

Bacterial surface (S) layers are the outermost proteinaceous cell envelope structures found on members of nearly all taxonomic groups of bacteria and Archaea. They are composed of numerous identical subunits forming a symmetric, porous, lattice-like layer that completely covers the cell surface. The subunits are held together and attached to cell wall carbohydrates by non-covalent interactions, and they spontaneously reassemble in vitro by an entropy-driven process. Due to the low amino acid sequence similarity among S-layer proteins in general, verification of the presence of an S-layer on the bacterial cell surface usually requires electron microscopy. In lactobacilli, S-layer proteins have been detected on many but not all species. Lactobacillus S-layer proteins differ from those of other bacteria in their smaller size and high predicted pI. The positive charge in Lactobacillus S-layer proteins is concentrated in the more conserved cell wall binding domain, which can be either N- or C-terminal depending on the species. The more variable domain is responsible for the self-assembly of the monomers to a periodic structure. The biological functions of Lactobacillus S-layer proteins are poorly understood, but in some species S-layer proteins mediate bacterial adherence to host cells or extracellular matrix proteins or have protective or enzymatic functions. Lactobacillus S-layer proteins show potential for use as antigen carriers in live oral vaccine design because of their adhesive and immunomodulatory properties and the general non-pathogenicity of the species.