Oral feeding of Bifidobacterium bifidum (BGN4) prevents CD4(+) CD45RB(high) T cell-mediated inflammatory bowel disease by inhibition of disordered T cell activation

Causal relationship between gut microbiota and myasthenia gravis: a bidirectional mendelian randomization study

BACKGROUND

Observational studies have demonstrated an association between gut microbiota and myasthenia gravis; however, the causal relationship between the two still lacks clarity. Our goals are to ascertain the existence of a bidirectional causal relationship between gut microbiota composition and myasthenia gravis, and to investigate how gut microbiota plays a role in reducing the risk of myasthenia gravis.

METHODS

We acquired gut microbiota data at the phylum, class, order, family, and genus levels from the MiBioGen consortium (N = 18,340) and myasthenia gravis data from the FinnGen Research Project (426 cases and 373,848 controls). In the two-sample Mendelian randomization analysis, we assessed the causal relationship between the gut microbiota and myasthenia gravis. We also conducted bidirectional MR analysis to determine the direction of causality. The inverse variance weighted, mendelian randomization-Egger, weighted median, simple mode, and weighted mode were used to test the causal relationship between the gut microbiota and severe myasthenia gravis. We used MR-Egger intercept and Cochran's Q test to assess for pleiotropy and heterogeneity, respectively. Furthermore, we utilized the MR-PRESSO method to evaluate horizontal pleiotropy and detect outliers.

RESULTS

In the forward analysis, the inverse-variance weighted method revealed that there is a positive correlation between the genus Lachnoclostridium (OR = 2.431,95%CI 1.047-5.647, p = 0.039) and the risk of myasthenia gravis. Additionally, the family Clostridiaceae1 (OR = 0.424,95%CI 0.202-0.889, p = 0.023), family Defluviitaleaceae (OR = 0.537,95%CI  0.290-0.995, p = 0.048), family Enterobacteriaceae (OR = 0.341,95%CI  0.135-0.865, p = 0.023), and an unknown genus (OR = 0.407,95%CI  0.209-0.793, p = 0.008) all demonstrated negative correlation with the risk of developing myasthenia gravis. Futhermore, reversed Mendelian randomization analysis proved a negative correlation between the risk of myasthenia gravis and genus Barnesiella (OR = 0.945,95%CI  0.906-0.985, p = 0.008).

CONCLUSION

Our research yielded evidence of a causality connection in both directions between gut microbiota and myasthenia gravis. We identified specific types of microbes associated with myasthenia gravis, which offers a fresh window into the pathogenesis of this disease and the possibility of developing treatment strategies. Nonetheless, more studies, both basic and clinical, are necessary to elucidate the precise role and therapeutic potential of the gut microbiota in the pathogenesis of myasthenia gravis.

Probiotic Species in the Management of Periodontal Diseases: An Overview

Periodontal diseases are one of the most common chronic inflammatory diseases of the oral cavity, which are initiated and sustained by pathogenic plaque biofilms. Central to modern periodontology is the idea that dysbiosis of periodontal microecology and disorder of host inflammatory response gives rise to degradation of periodontal tissues together, which eventually leads to tooth loss, seriously affecting the life quality of patients. Probiotics were originally used to treat intestinal diseases, while in recent years, extensive studies have been exploring the utilization of probiotics in oral disease treatment and oral healthcare. Probiotic bacteria derived from the genera Lactobacillus, Bifidobacterium, Streptococcus, and Weissella are found to play an effective role in the prevention and treatment of periodontal diseases via regulating periodontal microbiota or host immune responses. Here, we review the research status of periodontal health-promoting probiotic species and their regulatory effects. The current issues on the effectiveness and safety of probiotics in the management of periodontal diseases are also discussed at last. Taken together, the use of probiotics is a promising approach to prevent and treat periodontal diseases. Nevertheless, their practical use for periodontal health needs further research and exploration.

Bifidobacterium bifidum BGN4 Paraprobiotic Supplementation Alleviates Experimental Colitis by Maintaining Gut Barrier and Suppressing Nuclear Factor Kappa B Activation Signaling Molecules

Inflammatory bowel diseases, including Crohn's disease and ulcerative colitis, are characterized by chronic gastrointestinal inflammation with continuous relapse-remission cycles. This study aimed to evaluate the protective effect of Bifidobacterium bifidum BGN4 as a probiotic or paraprobiotic against dextran sulfate sodium (DSS)-induced colitis in mice. Ten-week-old female BALB/c mice were randomly divided into five groups. The control (CON) and DSS groups received oral gavage of PBS, whereas the live B. bifidum (LIVE), heat-killed B. bifidum BGN4 (HEAT), and lysozyme-treated B. bifidum BGN4 (LYSOZYME) groups received live B. bifidum BGN4, heat-killed B. bifidum BGN4, and lysozyme-treated B. bifidum BGN4, respectively, for 10 days, followed by DSS supply to induce colitis. The paraprobiotic (HEAT and LYSOZYME) groups had less body weight loss and colon length shortening than the DSS or LIVE groups. The LYSOZYME group exhibited better preserved intestinal barrier integrity than the LIVE group by upregulating gap junction protein expression possibly through activating NOD-like receptor family pyrin domain containing 6/caspase-1/interleukin (IL)-18 signaling. The LYSOZYME group showed downregulated proinflammatory molecules, including p-inhibitor of kappa B proteins alpha (IκBα), cycloxygenase 2 (COX2), IL-1β, and T-bet, whereas the expression of the regulatory T cell transcription factor, forkhead box P3 expression, was increased. The paraprobiotic groups showed distinct separation of microbiota distribution and improved inflammation-associated dysbiosis. These results suggest that B. bifidum BGN4 paraprobiotics, especially lysozyme-treated BGN4, have a preventive effect against DSS-induced colitis, impacting intestinal barrier integrity, inflammation, and dysbiosis.

Gut Microbiota and Autoimmune Diseases: A Charming Real World Together with Probiotics

BACKGROUND

The role of gut microbiota in human disease is fascinating for hundreds of researchers worldwide. Many works have highlighted that gut microbiota modulates the immune system and that its disruption can trigger autoimmune and inflammatory immune-mediated diseases. Probiotics are able to positively modify microbiota composition.

OBJECTIVE

The aim of this review is to report the most important findings regarding the effects of probiotics administration in the most common autoimmune disease and inflammatory immune-mediated diseases.

METHODS

Literature research was performed in PubMed, Google Scholar, and Medline, as well as in specific journal websites using the keywords: "autoimmunity", "microbiota", and "probiotics". The article selection has been made independently by three authors, and controversies have been solved by a fourth researcher. Only English-language articles were included and preference was given to clinical trials, meta-analysis, and case series. After the review process, 68 articles have been considered.

RESULTS

Relying on this evidence, many studies have investigated the potential of probiotics in restoring gut eubiosis, thus affecting pathogenesis, clinical manifestations, and course of these pathologies. Even in the light of few and sometimes contradictory studies, physicians should start to consider these preliminary findings when approaching patients suffering from autoimmune disease. After an accurate case-by-case evaluation of potential candidates, probiotics might be introduced besides the standard therapeutic plan as supportive measures.

Understanding the Functional Activity of Polyphenols Using Omics-Based Approaches

Plant polyphenols are the main category of natural active substances, and are distributed widely in vegetables, fruits, and plant-based processed foods. Polyphenols have a beneficial performance in preventing diseases and maintaining body health. However, its action mechanism has not been well understood. Foodomics is a novel method to sequence and widely used in nutrition, combining genomics, proteomics, transcriptomics, microbiome, and metabolomics. Based on multi-omics technologies, foodomics provides abundant data to study functional activities of polyphenols. In this paper, physiological functions of various polyphenols based on foodomics and microbiome was discussed, especially the anti-inflammatory and anti-tumor activities and gut microbe regulation. In conclusion, omics (including microbiomics) is a useful approach to explore the bioactive activities of polyphenols in the nutrition and health of human and animals.

Lysed and disrupted Bifidobacterium bifidum BGN4 cells promote anti-inflammatory activities in lipopolysaccharide-stimulated RAW 264.7 cells

Bifidobacterium bifidum BGN4 has been shown to improve the immune system by regulating interleukin (IL)-6 in RAW 264.7 macrophage cells. In this study, the dead cells of B. bifidum BGN4 were produced by enzymatic and physical processing to enhance the inhibition properties of pro-inflammatory cytokines using lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Notably, the secretion levels of cytokines such as interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α were decreased by the cell-wall disrupted extracts compared to heat-killed cells. The result suggests that the exposed interior-surface of B. bifidum BGN4 has a potential ability to regulate the immune-responses in the gastrointestinal tract due to major substances in inside-cell wall such as peptidoglycan and teichoic acids. In conclusion, the lysed and disrupted cells from the inside out of B. bifidum BGN4 have anti-inflammatory properties as paraprobiotic agents to control chronic inflammatory related-diseases.

Production of biologically active human interleukin-10 by Bifidobacterium bifidum BGN4

BACKGROUND

Bifidobacterium spp. are representative probiotics that play an important role in the health of their hosts. Among various Bifidobacterium spp., B. bifidum BGN4 exhibits relatively high cell adhesion to colonic cells and has been reported to have various in vivo and in vitro bio functionalities (e.g., anti-allergic effect, anti-cancer effect, and modulatory effects on immune cells). Interleukin-10 (IL-10) has emerged as a major suppressor of immune response in macrophages and other antigen presenting cells and plays an essential role in the regulation and resolution of inflammation. In this study, recombinant B. bifidum BGN4 [pBESIL10] was developed to deliver human IL-10 effectively to the intestines.

RESULTS

The vector pBESIL10 was constructed by cloning the human IL-10 gene under a gap promoter and signal peptide from Bifidobacterium spp. into the E. coli-Bifidobacterium shuttle vector pBES2. The secreted human IL-10 from B. bifidum BGN4 [pBESIL10] was analyzed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), Western Blotting, and enzyme-linked immunosorbent assay (ELISA). More than 1,473 ± 300 ng/mL (n = 4) of human IL-10 was obtained in the cell free culture supernatant of B. bifidum BGN4 [pBESIL10]. This productivity is significantly higher than other previously reported human IL-10 level from food grade bacteria. In vitro functional evaluation of the cell free culture supernatant of B. bifidum BGN4 [pBESIL10] revealed significantly inhibited interleukin-6 (IL-6) production in lipopolysaccharide (LPS)-induced Raw 264.7 cells (n = 6, p < 0.0001) and interleukin-8 (IL-8) production in LPS-induced HT-29 cells (n = 6, p < 0.01) or TNFα-induced HT-29 cells (n = 6, p < 0.001).

CONCLUSION

B. bifidum BGN4 [pBESIL10] efficiently produces and secretes significant amounts of biologically active human IL-10. The human IL-10 production level in this study is the highest of all human IL-10 production reported to date. Further research should be pursued to evaluate B. bifidum BGN4 [pBESIL10] producing IL-10 as a treatment for various inflammation-related diseases, including inflammatory bowel disease, rheumatoid arthritis, allergic asthma, and cancer immunotherapy.

Bifidobacterium animalis ssp. Lactis 420 Mitigates Autoimmune Hepatitis Through Regulating Intestinal Barrier and Liver Immune Cells

Autoimmune hepatitis (AIH) is an immune-mediated inflammatory liver disease of uncertain cause. Accumulating evidence shows that gut microbiota and intestinal barrier play significant roles in AIH thus the gut–liver axis has important clinical significance as a potential therapeutic target. In the present study, we found that Bifidobacterium animalis ssp. lactis 420 (B420) significantly alleviated S100-induced experimental autoimmune hepatitis (EAH) and modulated the gut microbiota composition. While the analysis of clinical specimens revealed that the fecal SCFA quantities were decreased in AIH patients, and B420 increased the cecal SCFA quantities in EAH mice. Remarkably, B420 application improved intestinal barrier function through upregulation of tight junction proteins in both vitro and vivo experiments. Moreover, B420 decreased the serum endotoxin level and suppressed the RIP3 signaling pathway of liver macrophages in EAH mice thus regulated the proliferation of Th17 cells. Nevertheless, the inhibition effect of B420 on RIP3 signaling pathway was blunted in vitro studies. Together, our results showed that early intervention with B420 contributed to improve the liver immune homeostasis and liver injury in EAH mice, which might be partly due to the protection of intestinal barrier. Our study suggested the potential efficacy of probiotics application against AIH and the promising therapeutic strategies targeting gut–liver axis for AIH.

Crude Turmeric Extract Improves the Suppressive Effects of Lactobacillus rhamnosus GG on Allergic Inflammation in a Murine Model of House Dust Mite-Induced Asthma

There is a strong correlation between dysregulation of the gastrointestinal microbiota and development of allergic diseases. The most prevalent therapies for relieving asthma symptoms are associated with serious side effects, and therefore novel approaches are needed. Our objective was to elucidate whether oral administration of Lactobacillus rhamnosus GG (LGG) as a probiotic or turmeric powder (TP) as a prebiotic or both as a synbiotic mitigate allergic inflammation including lung function, airway inflammatory cell infiltration, Th2 cytokines/chemokine in a murine model of house dust mite (HDM)-induced asthma. BALB/c mice were intranasally sensitized and challenged with HDM received TP (20 mg/Kg mouse), or/and LGG (10⁵ or 10⁷ cfu/ml), or both orally. Interestingly, the synbiotic intervention (HDM-TP-LGG E7) specifically suppress the developement of airway hyperresponsiveness in response to methacholine. Besides, our synbiotic, TP, and LGG strongly down-regulated eosinophilia, IL-5, CCL17, IL-13. In terms of T cell response, CD4⁺ Th2 cells and CD4⁺ Th17 population were reduced in the splenocytes of the treatment groups compared to control. The synbiotic group not only elevated CD25⁺Foxp3⁺Treg frequency compared to asthmatic group, but also increased T reg cells compared to the probiotic group. The synbiotic also indicated the superior effect in suppressing Th2 cells compared to probiotic. Although, TP and LGG alone displayed suppressive effects, this study showed that the combination therapy consisting of TP and LGG (synbiotic) is more effective in some of the parameters than either of the treatments alone. This novel synbiotic, might be considered as a potential food-based drug for translational medicine and can possibly be used along with corticosteroid treatment.

Cesarean section increases sensitivity to oxazolone-induced colitis in C57BL/6 mice

Children born by cesarean section (CS) have an increased risk of developing inflammatory bowel disease (IBD), possibly due to skewed microbial colonization during birth and consequently impaired bacterial stimulation of the developing immune system. The aim of this study was to investigate the association between CS and experimental colitis in a murine model of IBD. It was hypothesized that CS aggravates colonic inflammation due to a change in gut microbiota (GM) composition. C57BL/6 mice, delivered by CS or vaginal delivery (VD), were intra-rectally challenged with oxazolone at 8 weeks of age and monitored for colitis symptoms. The results showed that CS delivered mice experienced an increased body weight loss and colon weight, together with higher colonic concentrations of TNF-α and MPO compared with VD mice. Increased infiltration of inflammatory cells was present in CS delivered mice, as well as a downregulation in expression of the gut integrity genes occludin and tight junction protein 1 indicative of an impaired barrier function. The GM from CS delivered mice without colitis partly contributed to the increase in colitis symptoms when inoculated into germ-free recipient mice. In conclusion, CS increased sensitivity to oxazolone induced colitis in mice.

Analysis of hypoxia-associated dendritic cells in colitic mice and effects of probiotics on IL-10 production in inflammatory dendritic-cells under hypoxia

The aim of this study was to analyse hypoxia-associated dendritic cells (DCs) in colitic mice and the effects of probiotics on interleukin (IL)-10 production in inflammatory DCs under hypoxic conditions. Extensive hypoxia was observed in the colonic mucosa of dextran sodium sulphate-induced colitic mice. Flow cytometric analysis demonstrated that hypoxia-inducible factor-1α+ DCs in colonic lamina propria (CLP) lymphocytes and mesenteric lymph nodes (MLN) were more abundant in colitic mice than those in controls. Among three subsets of DCs, i.e. plasmacytoid DCs, conventional DCs (cDCs), and monocyte-derived DCs (mDCs), cDCs and mDCs were more abundant in CLP of colitic mice. Bone marrow-derived Flt-3L-induced DCs (Flt-DCs) but not bone marrow-derived GM-CSF-induced DCs (GM-DCs), incubated with 1% O2 exhibited an inflammatory phenotype, with higher CD86, IL-6, and tumour necrosis factor-α expression, and lower IL-10 levels than those in Flt-DCs incubated with 21% O2. The hypoxia-induced decrease in IL-10 expression in Flt-DCs was restored by Bifidobacterium bifidum JCM 1255T promoted IL-10 expression through the p38 pathway under normoxic conditions. The anti-inflammatory effects of B. bifidum JCM 1255T in Flt-DCs were mediated through different cellular mechanisms under hypoxic and normoxic conditions. B. bifidum JCM 1255T could be used therapeutically for its anti-inflammatory effects.

Baseline human gut microbiota profile in healthy people and standard reporting template

A comprehensive knowledge of the types and ratios of microbes that inhabit the healthy human gut is necessary before any kind of pre-clinical or clinical study can be performed that attempts to alter the microbiome to treat a condition or improve therapy outcome. To address this need we present an innovative scalable comprehensive analysis workflow, a healthy human reference microbiome list and abundance profile (GutFeelingKB), and a novel Fecal Biome Population Report (FecalBiome) with clinical applicability. GutFeelingKB provides a list of 157 organisms (8 phyla, 18 classes, 23 orders, 38 families, 59 genera and 109 species) that forms the baseline biome and therefore can be used as healthy controls for studies related to dysbiosis. This list can be expanded to 863 organisms if closely related proteomes are considered. The incorporation of microbiome science into routine clinical practice necessitates a standard report for comparison of an individual's microbiome to the growing knowledgebase of "normal" microbiome data. The FecalBiome and the underlying technology of GutFeelingKB address this need. The knowledgebase can be useful to regulatory agencies for the assessment of fecal transplant and other microbiome products, as it contains a list of organisms from healthy individuals. In addition to the list of organisms and their abundances, this study also generated a collection of assembled contiguous sequences (contigs) of metagenomics dark matter. In this study, metagenomic dark matter represents sequences that cannot be mapped to any known sequence but can be assembled into contigs of 10,000 nucleotides or higher. These sequences can be used to create primers to study potential novel organisms. All data is freely available from https://hive.biochemistry.gwu.edu/gfkb and NCBI's Short Read Archive.

Effects of Bifidobacterium bifidum in Mice Infected with Citrobacter rodentium

In vitro and in vivo studies suggest that selected Bifidobacterium bifidum strains sustain intestinal homeostasis. This study aimed to examine whether the administration of B. bifidum MIMBb75 (BB75) attenuates Citrobacter rodentium infection, a murine model for enteric infection and inflammatory bowel disease in humans. C57Bl6/J mice were randomized to receive BB75 daily starting before or after C. rodentium infection. BB75 load and infection kinetics were monitored. On day 10 post-infection (p.i.), histological parameters of the large intestine were assessed. Barrier integrity was evaluated by pathogen translocation to secondary organs and in vivo permeability test. Fecal C. rodentium load peaked at 10¹⁰ CFU/g at day 10 p.i., with clearance at day 24 p.i., regardless of probiotic treatment. BB75 administration resulted in 10⁷ cells/g of feces with no effect of timing of administration. BB75 treatment did not attenuate C. rodentium-induced crypt hyperplasia nor inflammation. C. rodentium and BB75 can co-exist in the gut with no mutual displacement. However, BB75 cannot counteract C. rodentium pathology. Our findings provide insight for the understanding of probiotics behavior and their clinical relevance in intestinal inflammation.

β-Sitosterol improves experimental colitis in mice with a target against pathogenic bacteria

In this article, we aim to examine the novel effects of β-sitosterol on murine experimental colitis. β-Sitosterol significantly reduces the weight loss, colon length, and alleviated microscopic appearances of colitis induced by dextran sulfate sodium. This compound also decreases the levels of TNF-α, IL-6, and IL-1β in intestinal tissue of mice with experimental colitis in a concentration-dependent manner. β-Sitosterol treatment to intestinal epithelial cells significantly increases expression of antimicrobial peptides and reduces survival of intracellular Salmonella typhimurium. These results showed the multiple effects of β-sitosterol against pathogenic bacteria for a novel approach to the treatment of colonic inflammation.

Improvement of electroporation-mediated transformation efficiency for a Bifidobacterium strain to a reproducibly high level

Bifidobacteria are representative probiotics which are defined as live microorganisms that confer a health benefit on the host. Because of their safety and healthfulness when applied to humans, bifidobacteria are suitable as genetically engineered bacteria for applications to benefit human physiology and pathology. However, molecular biological studies of bifidobacteria have been limited due to insufficient genetic tools including effective transformation methods. The aim of this study is to improve the electroporation-mediated transformation efficiency of bifidobacteria to a reproducibly high level. The crucial factors that determine electroporation efficiency are the restriction-modification system, together with the cell wall and cell membrane structure of the bacteria. We optimized the bifidobacterial electroporation conditions by focusing on these factors as well as the amount of plasmid DNA used, the electrical parameters and the bacterial growth phase. As a result, the electroporation efficiency of B. bifidum BGN4 drastically and consistently increased from 10³ to 10⁵ CFU / μg DNA. The most significant factor for increasing the electroporation efficiency was the cell wall weakening mediated by NaCl, which improved the electroporation frequency by 20 times. Because the optimized electrotransformation conditions reported here should be widely applicable to other Bifidobacterium species, these could promote the extensive genetic manipulation of the various Bifidobacterium species in future studies.

Production of Selenomethionine-Enriched Bifidobacterium bifidum BGN4 via Sodium Selenite Biocatalysis

Selenium is a trace element essential for human health that has received considerable attention due to its nutritional value. Selenium’s bioactivity and toxicity are closely related to its chemical form, and several studies have suggested that the organic form of selenium (i.e., selenomethionine) is more bioavailable and less toxic than its inorganic form (i.e., sodium selenite). Probiotics, especially Bifidobacteriium and Lactobacillus spp., have received increasing attention in recent years, due to their intestinal microbial balancing effects and nutraceutical benefits. Recently, the bioconversion (a.k.a biotransformation) of various bioactive molecules (e.g., minerals, primary and secondary metabolites) using probiotics has been investigated to improve substrate biofunctional properties. However, there have been few reports of inorganic selenium conversion into its organic form using Bifidobacterium and Lactobacillus spp. Here we report that the biosynthesis of organic selenium was accomplished using the whole cell bioconversion of sodium selenite under controlled Bifidobacterium bifidum BGN4 culture conditions. The total amount of organic and inorganic selenium was quantified using an inductively coupled plasma-atomic emission spectrometer (ICP-AES). The selenium species were separated via anion-exchange chromatography and analyzed with inductively coupled plasma-mass spectrometry (ICP-MS). Our findings indicated that the maximum level of organic selenium was 207.5 µg/g in selenium-enriched B. bifidum BGN4. Selenomethionine was the main organic selenium in selenium-enriched B. bifidum BGN4 (169.6 µg/g). Considering that B. bifidum BGN4 is a commercial probiotic strain used in the functional food industry with clinically proven beneficial effects, selenium-enriched B. bifidum BGN4 has the potential to provide dual healthy functions as a daily supplement of selenium and regulator of intestinal bacteria. This is the first report on the production of organic selenium using B. bifidum spp.

Administration of bifidobacterium and lactobacillus strains modulates experimental myasthenia gravis and experimental encephalomyelitis in Lewis rats

Probiotics beneficial effects on the host are associated with regulation of the intestinal microbial homeostasis and with modulation of inflammatory immune responses in the gut and in periphery. In this study, we investigated the clinical efficacy of two lactobacillus and two bifidobacterium probiotic strains in experimental autoimmune myasthenia gravis (EAMG) and experimental autoimmune encephalomyelitis (EAE) models, induced in Lewis rats. Treatment with probiotics led to less severe disease manifestation in both models; ex vivo analyses showed preservation of neuromuscular junction in EAMG and myelin content in EAE spinal cord. Immunoregulatory transcripts were found differentially expressed in gut associated lymphoid tissue and in peripheral immunocompetent organs. Feeding EAMG animals with probiotics resulted in increased levels of Transforming Growth Factor-β (TGFβ) in serum, and increased percentages of regulatory T cells (Treg) in peripheral blood leukocyte. Exposure of immature dendritic cells to probiotics induced their maturation toward an immunomodulatory phenotype, and secretion of TGFβ. Our data showed that bifidobacteria and lactobacilli treatment effectively modulates disease symptoms in EAMG and EAE models, and support further investigations to evaluate their use in autoimmune diseases.

Bifidobacteria alleviate experimentally induced colitis by upregulating indoleamine 2, 3-dioxygenase expression

The goal of this study was explore the role of indoleamine 2, 3-dioxygenase (IDO) in the therapeutic effect of probiotics on inflammatory bowel disease (IBD). Trinitrobenzene sulfonic acid (TNBS) was used to induce colitis in mice and 1-methyltryptophan (1-MT) to block expression of IDO. Clinical manifestations and macroscopic and microscopic colonic changes were assessed using a disease activity index (DAI), the Wallace-Keenan, and Curtner scoring systems, respectively. Expression of colonic IDO was detected by western blot. Immunohistochemistry analysis to evaluate numbers of CD11c⁺ cells and expression of IL-17 and Foxp3 showed that DAI, Wallace-Keenan, and Curtner scores were lower in the Bifidobacteria treatment group than the control group and that the therapeutic effect of Bifidobacteria was blocked by 1-MT (P < 0.05). Additionally, Bifidobacteria were found to increase expression of IDO and the numbers of CD11c⁺ cells, CD11c⁺ and IDO double positive cells and Foxp3⁺ Treg cells, while decreasing the number of IL-17⁺ cells (P < 0.05). The generation of Foxp3⁺ Treg cells induced by Bifidobacteria was abrogated by 1-MT (P < 0.05). These findings study suggest that Bifidobacteria attenuate TNBS-induced colitis by inducing expression of IDO, which further increases generation of Foxp3⁺ Treg cells.

Exploring the role of the microbiota member Bifidobacterium in modulating immune-linked diseases

The gut-associated microbiota is essential for multiple physiological processes, including immune development. Acquisition of our initial pioneer microbial communities, including the dominant early life genus Bifidobacterium, occurs at a critical period of immune maturation and programming. Bifidobacteria are resident microbiota members throughout our lifetime and have been shown to modulate specific immune cells and pathways. Notably, reductions in this genus have been associated with several diseases, including inflammatory bowel disease. In this review, we provide an overview of bifidobacteria profiles throughout life and how different strains of bifidobacteria have been implicated in immune modulation in disease states. The focus will be examining preclinical models and outcomes from clinical trials on immune-linked chronic conditions. Finally, we highlight some of the important unresolved questions in relation to Bifidobacterium-mediated immune modulation and implications for future directions, trials, and development of new therapies.

Clinical Effect of IRT-5 Probiotics on Immune Modulation of Autoimmunity or Alloimmunity in the Eye

BACKGROUND

Although the relation of the gut microbiota to a development of autoimmune and inflammatory diseases has been investigated in various animal models, there are limited studies that evaluate the effect of probiotics in the autoimmune eye disease. Therefore, we aimed to investigate the effect of IRT-5 probiotics consisting of Lactobacillus casei, Lactobacillus acidophilus, Lactobacillus reuteri, Bifidobacterium bifidum, and Streptococcus thermophilus on the autoimmunity of uveitis and dry eye and alloimmunity of corneal transplantation.

METHODS

Experimental autoimmune uveitis was induced by subcutaneous immunization with interphotoreceptor-binding protein and intraperitoneal injection of pertussis toxin in C57BL/6 (B6) mice. For an autoimmune dry eye model, 12-weeks-old NOD.B10.H2b mice were used. Donor cornea of B6 mice was transplanted into BALB/C mice. IRT-5 probiotics or phosphate buffered saline (PBS) were administered for three weeks immediately after induction of uveitis or transplantation. The inflammation score of the retinal tissues, dry eye manifestations (corneal staining and tear secretion), and graft survival were measured in each model. The changes of T cells were evaluated in drainage lymph nodes using fluorescence-activated cell sorting.

RESULTS

Retinal histology score in IRT-5 group of uveitis was lower than that in PBS group (p = 0.045). Ocular staining score was lower (p < 0.0001) and tear secretion was higher (p < 0.0001) in the IRT-5 group of NOD.B10.H2b mice than that in the PBS group. However, the graft survival in the IRT-5 group was not different from those of PBS group. The percentage of regulatory T cells was increased in the IRT-5-treated dry eye models (p = 0.032). The percentage of CD8⁺IL-17hi (p = 0.027) and CD8⁺ interferon gamma (IFNγ)hi cells (p = 0.022) were significantly decreased in the IRT-5-treated uveitis models and the percentage of CD8⁺IFNγhi cells was markedly reduced (p = 0.036) in IRT-5-treated dry eye model.

CONCLUSION

Our results suggest that administration of IRT-5 probiotics may modulate clinical manifestations of autoimmunity in the eye, but not on alloimmunity of corneal transplantation.

Selection, Characterization and Interaction Studies of a DNA Aptamer for the Detection of Bifidobacterium bifidum

A whole-bacterium-based SELEX (Systematic Evolution of Ligands by Exponential Enrichment) procedure was adopted in this study for the selection of an ssDNA aptamer that binds to Bifidobacterium bifidum. After 12 rounds of selection targeted against B. bifidum, 30 sequences were obtained and divided into seven families according to primary sequence homology and similarity of secondary structure. Four FAM (fluorescein amidite) labeled aptamer sequences from different families were selected for further characterization by flow cytometric analysis. The results reveal that the aptamer sequence CCFM641-5 demonstrated high-affinity and specificity for B. bifidum compared with the other sequences tested, and the estimated K_d value was 10.69 ± 0.89 nM. Additionally, sequence truncation experiments of the aptamer CCFM641-5 led to the conclusion that the 5'-primer and 3'-primer binding sites were essential for aptamer-target binding. In addition, the possible component of the target B. bifidum, bound by the aptamer CCFM641-5, was identified as a membrane protein by treatment with proteinase. Furthermore, to prove the potential application of the aptamer CCFM641-5, a colorimetric bioassay of the sandwich-type structure was used to detect B. bifidum. The assay had a linear range of 10⁴ to 10⁷ cfu/mL (R² = 0.9834). Therefore, the colorimetric bioassay appears to be a promising method for the detection of B. bifidum based on the aptamer CCFM641-5.

Review on Bifidobacterium bifidum BGN4: Functionality and Nutraceutical Applications as a Probiotic Microorganism

Bifidobacterium bifidum BGN4 is a probiotic strain that has been used as a major ingredient to produce nutraceutical products and as a dairy starter since 2000. The various bio-functional effects and potential for industrial application of B. bifidum BGN4 has been characterized and proven by in vitro (i.e., phytochemical bio-catalysis, cell adhesion and anti-carcinogenic effects on cell lines, and immunomodulatory effects on immune cells), in vivo (i.e., suppressed allergic responses in mouse model and anti-inflammatory bowel disease), and clinical studies (eczema in infants and adults with irritable bowel syndrome). Recently, the investigation of the genome sequencing was finished and this data potentially clarifies the biochemical characteristics of B. bifidum BGN4 that possibly illustrate its nutraceutical functionality. However, further systematic research should be continued to gain insight for academic and industrial applications so that the use of B. bifidum BGN4 could be expanded to result in greater benefit. This review deals with multiple studies on B. bifidum BGN4 to offer a greater understanding as a probiotic microorganism available in functional food ingredients. In particular, this work considers the potential for commercial application, physiological characterization and exploitation of B. bifidum BGN4 as a whole.

Topological distortion and reorganized modular structure of gut microbial co-occurrence networks in inflammatory bowel disease

The gut microbiome plays a key role in human health, and alterations of the normal gut flora are associated with a variety of distinct disease states. Yet, the natural dependencies between microbes in healthy and diseased individuals remain far from understood. Here we use a network-based approach to characterize microbial co-occurrence in individuals with inflammatory bowel disease (IBD) and healthy (non-IBD control) individuals. We find that microbial networks in patients with IBD differ in both global structure and local connectivity patterns. While a “core” microbiome is preserved, network topology of other densely interconnected microbe modules is distorted, with potent inflammation-mediating organisms assuming roles as integrative and highly connected inter-modular hubs. We show that while both networks display a rich-club organization, in which a small set of microbes commonly co-occur, the healthy network is more easily disrupted by elimination of a small number of key species. Further investigation of network alterations in disease might offer mechanistic insights into the specific pathogens responsible for microbiome-mediated inflammation in IBD.

The influence of the young microbiome on inflammatory diseases--Lessons from animal studies

Chronic inflammatory diseases are on the rise in the Westernized world. This rise has been correlated to a range of environmental factors, such as birth mode, rural versus urban living conditions, and use of antibiotics. Such environmental factors also influence early life gut microbiota (GM) colonization and maturation--and there is growing evidence that the negative effects of these factors on human health are mediated via GM alterations. Colonization of the gut initiates priming of the immune system from birth, driving tolerance towards non-harmful microorganisms and dietary antigens and proper reactions towards invading pathogens. This early colonization is crucial for the establishment of a healthy GM, and throughout life the balanced interaction of GM and immune system is a key element in maintaining health. An immune system out of balance increases the risk for later life inflammatory diseases. Animal models are indispensable in the studies of GM influence on disease mechanisms and progression, and focus points include studies of GM modification during pregnancy and perinatal life. Here, we present an overview of animal studies which have contributed to our understanding of GM functions in early life and how alterations affect risk and expression of certain inflammatory diseases with juvenile onset, including interventions, such as birth mode, antibiotics, and probiotics.

Bifidobacterium species lower serum glucose, increase expressions of insulin signaling proteins, and improve adipokine profile in diabetic mice

This study, using C57BL/6J mice with streptozotocin (STZ)-induced diabetes, aimed to determine whether Bifidobacterium species (spp.) both induces the expressions of proteins in the insulin signaling pathway and enhances the expressions of certain adipocytokines. The protein expressions of IκB kinase alpha (IKKα), IκB kinase beta (IKKβ), nuclear factor-kappaB inhibitor alpha (IκBα), and the mitogen-activated protein kinase (MAPK) pathway were also investigated. Oral administration of Bifidobacterium spp. reduced blood glucose levels significantly and increased the protein expressions of insulin receptor beta, insulin receptor substrate 1, protein kinase B (Akt/PKB), IKKα, and IκBα. Extracellular-signal-regulated kinase 2 (ERK2) showed increased expression. Bifidobacterium spp. also induced the adiponectin expression and decreased both macrophage chemoattractant protein-1 (MCP-1) and interleukin-6 (IL-6) expression. In addition, IKKβ, c-Jun NH2-terminal kinase (JNK) and p38 MAP kinase expressions showed no significant changes in both groups. In conclusion, Bifidobacterium spp. may be the promising bacteria for treating diabetes.

Oral delivery of Bifidobacterium longum expressing α-melanocyte-stimulating hormone to combat ulcerative colitis

α-Melanocyte-stimulating hormone (α-MSH) is a tridecapeptide derived from pro-opiomelanocortin that exhibits potent anti-inflammatory properties by regulating the production of inflammatory mediators. This peptide has been well established in several inflammatory models, including inflammatory bowel disease (IBD). However, its extremely short duration in vivo limits its clinical application. To address this limitation, Bifidobacterium was used here as a carrier to deliver α-MSH. We utilized α-MSH-engineered Bifidobacterium against IBD, which is closely linked to immune and intestinal microbiota dysfunction. First, we constructed a Bifidobacterium longum secreting α-MSH (B. longum-α-MSH). We then tested the recombinant α-MSH expression and determined its bioactivity in HT-29 cells. To assess its effectiveness, B. longum-α-MSH was used against an ulcerative colitis (UC) model in rats induced by dextran sulfate sodium. The data showed that α-MSH expression in B. longum-α-MSH was effective, and its biological activity was similar to the synthesized one. This UC model experiment indicated that B. longum-α-MSH successfully colonized the intestinal gut, expressed bioactive α-MSH and had a significant anti-inflammatory effect. The results demonstrate the feasibility of preventing IBD by using B. longum-α-MSH.

Oral administration of Bifidobacterium spp. improves insulin resistance, induces adiponectin, and prevents inflammatory adipokine expressions

The intestinal microbiome might be an important contributor to the development of type 2 diabetes. This study was designed to test the hypothesis that oral administration of Bifidobacterium species (spp.) (including B. longum, B. bifidum, B. infantis, and B. animalis) may both ameliorate insulin resistance and reduce the expressions of inflammatory adipocytokines. Male Swiss-Webster mice fed a high-fat diet with or without oral administration of Bifidobacterium spp. for 5 weeks were subjected to an insulin tolerance test and an oral glucose tolerance test. Plasma levels of glucose at 30, 60, 90 and 120 min after insulin injection or glucose administration were significantly lower in the Bifidobacterium spp. than in the control group (P < 0.05), showing the beneficial effect of oral administration on insulin resistance in obese Swiss mice. In addition, Bifidobacterium spp. increased the adiponectin mRNA level and decreased those of monocyte chemoattractant protein 1 and interleukin 6 in non-diabetic C57BL/6J mice fed a normal diet, indicating a molecular mechanism which may ameliorate the inflammatory state, thereby reducing insulin resistance. In conclusion, oral administration of Bifidobacterium spp. improves insulin resistance and glucose tolerance in obese mice by reducing inflammation, as it does in the lean state.

Comparative genomic analysis of 45 type strains of the genus Bifidobacterium: a snapshot of its genetic diversity and evolution

Bifidobacteria are well known for their human health-promoting effects and are therefore widely applied in the food industry. Members of the Bifidobacterium genus were first identified from the human gastrointestinal tract and were then found to be widely distributed across various ecological niches. Although the genetic diversity of Bifidobacterium has been determined based on several marker genes or a few genomes, the global diversity and evolution scenario for the entire genus remain unresolved. The present study comparatively analyzed the genomes of 45 type strains. We built a robust genealogy for Bifidobacterium based on 402 core genes and defined its root according to the phylogeny of the tree of bacteria. Our results support that all human isolates are of younger lineages, and although species isolated from bees dominate the more ancient lineages, the bee was not necessarily the original host for bifidobacteria. Moreover, the species isolated from different hosts are enriched with specific gene sets, suggesting host-specific adaptation. Notably, bee-specific genes are strongly associated with respiratory metabolism and are potential in helping those bacteria adapt to the oxygen-rich gut environment in bees. This study provides a snapshot of the genetic diversity and evolution of Bifidobacterium, paving the way for future studies on the taxonomy and functional genomics of the genus.

Intestinal epithelial cell toll-like receptor 5 regulates the intestinal microbiota to prevent low-grade inflammation and metabolic syndrome in mice

BACKGROUND & AIMS

Mice lacking the receptor Toll-like receptor 5 (TLR5-null mice), which recognizes flagellin, have an altered intestinal microbiota composition compared with wild-type mice; they develop low-grade inflammation and metabolic syndrome and are prone to colitis. The relative roles of intestinal epithelial cell (IEC) vs dendritic cell (DC) TLR5 in mediating these phenotypes are not clear; modification of intestinal microbiota composition has been reported to reflect animal husbandry practices rather than loss of TLR5. We generated mice with specific disruption of Tlr5 in IECs or DCs by using a breeding scheme that allows comparison with cohoused siblings as controls.

METHODS

We generated C57BL/6 mice with LoxP sites flanking Tlr5. These mice were crossed with mice expressing Cre recombinase, regulated by the villin or CD11c promoters, to generate mice that lacked expression of TLR5 by IECs (TLR5(ΔIEC)) or DCs (TLR5(ΔDC)), respectively. Tlr5(fl/fl) siblings were used as controls. On weaning, mice were housed by sex and genotype or by sex only (genotypes cohoused). Mice were examined for basal phenotypes, including microbiota composition; we also analyzed responses to pathobiont challenge, administration of dextran sodium sulfate, and high-fat diets.

RESULTS

Similar to previous findings from TLR5-null mice, TLR5(ΔIEC) mice had low-grade inflammation (mild splenomegaly, shortened colons, and increased fecal levels of lipocalin 2), metabolic syndrome, and an inability to clear pathobionts and were prone to developing colitis compared with their sibling controls under both housing conditions. Development of this inflammation in the TLR5(ΔIEC) mice was eliminated by administration of antibiotics and associated with alterations in localization of microbiota and levels of fecal lipopolysaccharide and flagellin. The composition of the microbiota clustered more closely according to genotype than housing. Loss of TLR5 from DCs did not associate with development of inflammation-associated phenotypes or alterations in the composition of the microbiota but resulted in complete loss of flagellin-induced production of interleukin-22.

CONCLUSIONS

In mice, flagellin activation of TLR5 on DCs leads to production of interleukin-22. Expression of TLR5 on IECs regulates the composition and localization of the intestinal microbiota, preventing diseases associated with intestinal inflammation.

Myasthenia Gravis: paradox versus paradigm in autoimmunity

Myasthenia Gravis (MG) is a paradigm of organ-specific autoimmune disease (AID). It is mediated by antibodies that target the neuromuscular junction. The purpose of this review is to place MG in the general context of autoimmunity, to summarize the common mechanisms between MG and other AIDs, and to describe the specific mechanisms of MG. We have chosen the most common organ-specific AIDs to compare with MG: type 1 diabetes mellitus (T1DM), autoimmune thyroid diseases (AITD), multiple sclerosis (MS), some systemic AIDs (systemic lupus erythematous (SLE), rheumatoid arthritis (RA), Sjogren's syndrome (SS)), as well as inflammatory diseases of the gut and liver (celiac disease (CeD), Crohn's disease (CD), and primary biliary cirrhosis (PBC)). Several features are similar between all AIDs, suggesting that common pathogenic mechanisms lead to their development. In this review, we address the predisposing factors (genetic, epigenetic, hormones, vitamin D, microbiota), the triggering components (infections, drugs) and their interactions with the immune system [1,2]. The dysregulation of the immune system is detailed and includes the role of B cells, Treg cells, Th17 and cytokines. We particularly focused on the role of TNF-α and interferon type I whose role in MG is very analogous to that in several other AIDS. The implication of AIRE, a key factor in central tolerance is also discussed. Finally, if MG is a prototype of AIDS, it has a clear specificity compared to the other AIDS, by the fact that the target organ, the muscle, is not the site of immune infiltration and B cell expansion, but exclusively that of antibody-mediated pathogenic mechanisms. By contrast, the thymus in the early onset subtype frequently undergoes tissue remodeling, resulting in the development of ectopic germinal centers surrounded by high endothelial venules (HEV), as observed in the target organs of many other AIDs.

Anti-inflammatory effects of the Chinese herbal formula FAHF-2 in experimental and human IBD

BACKGROUND

Crohn's disease (CD) is a chronic inflammatory disease with increasing incidence in children. Current medications have potentially serious side effects, hence increasing interest in alternative therapies. We previously developed an herbal formula, FAHF-2, based on a classical traditional Chinese herbal formula Wu Mei Wan that has long been used in China to treat colitis. We investigated FAHF-2's potential anti-inflammatory effects.

METHODS

FAHF-2 efficacy was tested in vivo in the CD45RbRAG1 transfer colitis model. Weight loss, colonic histology, and cytokine production from mesenteric lymph nodes were assessed. Human peripheral blood mononuclear cells (PBMCs) and colonic biopsies were obtained from children newly diagnosed with CD and controls and cultured with or without FAHF-2. Cytokine levels were measured by multiplex immunoassay. The effect of FAHF-2 on TNF-α-producing cells was determined by flow cytometry. NF-κB signaling was investigated in human lamina propria mononuclear cells upon FAHF-2 treatment by In-Cell Western.

RESULTS

FAHF-2-treated mice had decreased weight loss, improved histology, and reduced TNF-α, IL-17, IL-6, and IFN-γ production. In vitro treated PBMCs produced less TNF-α, IFN-γ, and IL-12. FAHF-2 reduced the TNF-α-producing monocytes and T cells. Inflamed CD biopsies produced less TNF-α, IL-17, IL-6, and IL-1β. These effects are because of decreased NF-κB activation.

CONCLUSIONS

FAHF-2 inhibited both adaptive and innate immune proinflammatory cytokine responses in PBMCs and inflamed CD mucosa due in part to blockage of NF-κB activation. FAHF-2 was effective in halting progression of colitis in a murine model. This study shows that FAHF-2 has potential as a novel treatment of CD.

Prophylactic effect of probiotics on the development of experimental autoimmune myasthenia gravis

Probiotics are live bacteria that confer health benefits to the host physiology. Although protective role of probiotics have been reported in diverse diseases, no information is available whether probiotics can modulate neuromuscular immune disorders. We have recently demonstrated that IRT5 probiotics, a mixture of 5 probiotics, could suppress diverse experimental disorders in mice model. In this study we further investigated whether IRT5 probiotics could modulate the progression of experimental autoimmune myasthenia gravis (EAMG). Myasthenia gravis (MG) is a T cell dependent antibody mediated autoimmune disorder in which acetylcholine receptor (AChR) at the neuromuscular junction is the major auto-antigen. Oral administration of IRT5 probiotics significantly reduced clinical symptoms of EAMG such as weight loss, body trembling and grip strength. Prophylactic effect of IRT5 probiotics on EMAG is mediated by down-regulation of effector function of AChR-reactive T cells and B cells. Administration of IRT5 probiotics decreased AChR-reactive lymphocyte proliferation, anti-AChR reactive IgG levels and inflammatory cytokine levels such as IFN-γ, TNF-α, IL-6 and IL-17. Down-regulation of inflammatory mediators in AChR-reactive lymphocytes by IRT5 probiotics is mediated by the generation of regulatory dendritic cells (rDCs) that express increased levels of IL-10, TGF-β, arginase 1 and aldh1a2. Furthermore, DCs isolated from IRT5 probiotics-fed group effectively converted CD4⁺ T cells into CD4⁺Foxp3⁺ regulatory T cells compared with control DCs. Our data suggest that IRT5 probiotics could be applicable to modulate antibody mediated autoimmune diseases including myasthenia gravis.

Nutritional and probiotic supplementation in colitis models

In vitro and animals models have long been used to study human diseases and identify novel therapeutic approaches that can be applied to combat these conditions. Ulcerative colitis and Crohn's disease are the two main entities of inflammatory bowel disease (IBD). There is an intricate relationship between IBD features in human patients, in vitro and animal colitis models, mechanisms and possible therapeutic approaches in these models, and strategies that can be extrapolated and applied in humans. Malnutrition, particularly protein-energy malnutrition and vitamin and micronutrient deficiencies, as well as dysregulation of the intestinal microbiota, are common features of IBD. Based on these observations, dietary supplementation with essential nutrients known to be in short supply in the diet in IBD patients and with other molecules believed to provide beneficial anti-inflammatory effects, as well as with probiotic organisms that stimulate immune functions and resistance to infection has been tested in colitis models. Here we review current knowledge on nutritional and probiotic supplementation in in vitro and animal colitis models. While some of these strategies require further fine-tuning before they can be applied in human IBD patients, their intended purpose is to prevent, delay or treat disease symptoms in a non-pharmaceutical manner.

Horizontal distribution of the fecal microbiota in adolescents with inflammatory bowel disease

BACKGROUND AND AIMS

The commensal microbiota of the gastrointestinal tract plays an important role in the pathogenesis of inflammatory bowel disease. We examined the horizontal structure of the fecal microbiota in the colon in adolescents with Crohn disease or ulcerative colitis and a control group.

PATIENTS AND METHODS

Fecal samples were collected in 3 fractions from patients with Crohn disease (n = 22), ulcerative colitis (n = 12), and controls (n = 24) during preparation for colonoscopy. Additionally, biopsies from colon tissue were taken. Samples were examined using a culture technique and a fluorescent in situ hybridization method. The mucin degradation assay was carried out.

RESULTS

Quantitative composition of the microbiota was different in the consecutive 3 fecal fractions and in the colon tissue of the study groups, but in patients from the control group, the composition of microbiota in the consecutive fractions was similar. Statistical analyses showed that the total distribution of the studied bacterial taxons in the contents in all 3 fecal fractions and in the colon tissue in the given disease group, and in the control group was characteristic for the studied patient group. Differences in species distribution among the cohorts studied were highly significant (P < 0.0001). Moreover, it was shown that in the fecal fraction I and in the colon tissue samples, there is no significant difference for any of the analyzed bacterial groups, using the culture methods or fluorescent in situ hybridization, but significant results were demonstrated in the II and III fractions for specific bacterial groups. The bacterial flora attached to the mucus layer in the UC group had significantly more degraded mucus in comparison with the control group (P = 0.045).

CONCLUSIONS

Distribution of the microbiota in the colon is layered, which can be called horizontal distribution of the fecal flora. Only in the ulcerative colitis group, the bacterial flora attached to the mucous layer exerts action on the mucin.

Lessons from probiotic-host interaction studies in murine models of experimental colitis

In inflammatory bowel diseases (IBD), it is known that besides genetic and environmental factors (e.g. diet, drugs, stress), the microbiota play an important role in the pathogenesis. Patients with IBD have an altered microbiota (dysbiosis) and therefore, probiotics, defined as 'live micro-organisms that when administered in adequate amounts can confer a health benefit on the host', have been suggested as nutritional supplements to restore these imbalances. The best response on probiotics among the different types of IBD appears to be in the case of ulcerative colitis. Although probiotics show promise in IBD in both clinical and animal studies, further mechanistic studies are necessary to optimize the use of probiotics as supporting therapy in IBD. Murine models of experimental colitis have been used for decades to study this pathology, and these models have been proven useful to search for new therapeutic approaches. The purpose of this review is to summarize probiotic-host interaction studies in murine models of experimental colitis and to evaluate how these models can further help in understanding these complex interactions. Unraveling the molecular mechanisms behind the beneficial effects will assist in better and possibly more efficient probiotic formulations.

Pathogenic factors involved in the development of irritable bowel syndrome: focus on a microbial role

Irritable bowel syndrome (IBS) is a symptom complex characterized by recurrent abdominal pain or discomfort, and accompanied by abnormal bowel habits, in the absence of any discernible organic abnormality. Its origin remains unclear, partly because multiple pathophysiologic mechanisms are likely to be involved. A significant proportion of patients develop IBS symptoms after an episode of gastrointestinal infection. In addition to gastrointestinal pathogens, recent evidence suggests that patients with IBS have abnormal composition and higher temporal instability of their intestinal microbiota. Because the intestinal microbiota is an important determinant of normal gut function and immunity, this instability may constitute an additional mechanism that leads to symptom generation and IBS. More importantly, a role for altered microbiota composition in IBS raises the possibility of therapeutic interventions through selective antibiotic or probiotic administration. The new concept of functional bowel diseases incorporates the bidirectional communication between the gut and the central nervous system (gut-brain axis), which may explain the multiple facets of IBS by linking emotional and cognitive centers of the brain with peripheral functioning of the gastrointestinal tract and vice versa.

Bifidobacterium lactis attenuates onset of inflammation in a murine model of colitis

AIM

To assess the anti-inflammatory effect of the probiotic Bifidobacterium lactis (B. lactis) in an adoptive transfer model of colitis.

METHODS

Donor and recipient mice received either B. lactis or bacterial culture medium as control (deMan Rogosa Sharpe) in drinking water for one week prior to transfer of a mix of naive and regulatory T cells until sacrifice.

RESULTS

All recipient mice developed signs of colonic inflammation, but a significant reduction of weight loss was observed in B. lactis-fed recipient mice compared to control mice. Moreover, a trend toward a diminution of mucosal thickness and attenuated epithelial damage was revealed. Colonic expression of pro-inflammatory and T cell markers was significantly reduced in B. lactis-fed recipient mice compared to controls. Concomitantly, forkhead box protein 3, a marker of regulatory T cells, was significantly up-regulated by B. lactis.

CONCLUSION

Daily oral administration of B. lactis was able to reduce inflammatory and T cells mediators and to promote regulatory T cells specific markers in a mouse model of colitis.

Genomic insights into bifidobacteria

Since the discovery in 1899 of bifidobacteria as numerically dominant microbes in the feces of breast-fed infants, there have been numerous studies addressing their role in modulating gut microflora as well as their other potential health benefits. Because of this, they are frequently incorporated into foods as probiotic cultures. An understanding of their full interactions with intestinal microbes and the host is needed to scientifically validate any health benefits they may afford. Recently, the genome sequences of nine strains representing four species of Bifidobacterium became available. A comparative genome analysis of these genomes reveals a likely efficient capacity to adapt to their habitats, with B. longum subsp. infantis exhibiting more genomic potential to utilize human milk oligosaccharides, consistent with its habitat in the infant gut. Conversely, B. longum subsp. longum exhibits a higher genomic potential for utilization of plant-derived complex carbohydrates and polyols, consistent with its habitat in an adult gut. An intriguing observation is the loss of much of this genome potential when strains are adapted to pure culture environments, as highlighted by the genomes of B. animalis subsp. lactis strains, which exhibit the least potential for a gut habitat and are believed to have evolved from the B. animalis species during adaptation to dairy fermentation environments.

Gatekeepers of intestinal inflammation

The intestine is subjected to a barrage of insults from food, bacterial flora, and pathogens. Despite this constant antigenic challenge, the mucosal tissues lining the intestinal tract remain largely under control. The mechanisms regulating the homeostatic balance in the gut have been investigated for many years by many groups, but the precise nature of the regulatory control remains elusive. In this review, we provide an overview of pathways proposed to be involved in dampening the inflammatory response and maintaining the homeostatic balance in the intestine, and how these pathways may be disrupted in ulcerative colitis and Crohn's disease.

Effect of probiotic mix (Bifidobacterium bifidum, Bifidobacterium lactis, Lactobacillus acidophilus) in the primary prevention of eczema: a double-blind, randomized, placebo-controlled trial

Controversy exists regarding the preventive effect of probiotics on the development of eczema or atopic dermatitis. We investigated whether supplementation of probiotics prevents the development of eczema in infants at high risk. In a randomized, double-blind, placebo-controlled trial, 112 pregnant women with a family history of allergic diseases received a once-daily supplement, either a mixture of Bifidobacterium bifidum BGN4, B. lactis AD011, and Lactobacillus acidophilus AD031, or placebo, starting at 4-8 wks before delivery and continuing until 6 months after delivery. Infants were exclusively breast-fed during the first 3 months, and were subsequently fed with breastmilk or cow's milk formula from 4 to 6 months of age. Clinical symptoms of the infants were monitored until 1 yr of age, when the total and specific IgE against common food allergens were measured. A total of 68 infants completed the study. The prevalence of eczema at 1 yr in the probiotic group was significantly lower than in the placebo group (18.2% vs. 40.0%, p=0.048). The cumulative incidence of eczema during the first 12 months was reduced significantly in probiotic group (36.4% vs. 62.9%, p=0.029); however, there was no difference in serum total IgE level or the sensitization against food allergens between the two groups. Prenatal and postnatal supplementation with a mixture of B. bifidum BGN4, B. lactis AD011, and L. acidophilus AD031 is an effective approach in preventing the development of eczema in infants at high risk of allergy during the first year of life.

Clinical efficacy of Lactobacillus acidophilus against experimental murine colitis and its effects on the expression of STAT1, T-bet and GATA3

AIM: To investigate the therapeutic efficacy of Lactobacillus acidophilus against experimental murine colitis and its effects on the expression of STAT1, T-bet and GATA3.

METHODS: Experimental murine colitis was induced with 2.5% dextran sulfate sodium (DSS). A total of 70 mice were randomly and equally divided into seven groups: model control group, negative control group, mesalamine group, low-dose Lactobacillus acidophilus group, medium-dose Lactobacillus acidophilus group, high-dose Lactobacillus acidophilus group and normal control group. The expression of STAT1, T-bet and GATA3 mRNAs in colonic mucosa was measured by reverse transcription-polymerase chain reaction (RT-PCR). The expression of T-bet protein was measured by Western blot and immunohistochemistry (IHC). Colonic tissue damage was assessed using histopathologic score. The body weight and disease activity index (DAI) of all rats were evaluated daily.

RESULTS: Compared with the normal control group, the disease activity index and histopathologic scores were significantly increased (both P < 0.05) in the model control group. All doses of Lactobacillus acidophilus and mesalamine could significantly reduce disease activity index and histopathologic scores when compared to the model control group (6.20 ± 2.64, 5.00 ± 1.21, 5.72 ± 2.63 and 5.81 ± 1.32 vs 7.81 ± 1.02; 4.25 ± 2.05, 2.56 ± 1.81, 2.20 ± 1.12 and 3.10 ± 2.60 vs 5.80 ± 2.94; all P < 0.05). The expression levels of STAT1 and T-bet mRNAs in all Lactobacillus acidophilus groups (low-, medium- and high-dose) and mesalazine group were lower than that in the model control group (all P < 0.05). Moreover, the expression levels of T-bet protein in all Lactobacillus acidophilus groups and mesalazine group were also significantly lower than that in the model control group (0.27 ± 0.04, 0.23 ± 0.02, 0.18 ± 0.04 and 0.27 ± 0.11 vs 0.30 ± 0.04; 0.263 ± 0.045, 0.234 ± 0.015, 0.114 ± 0.025 and 0.252 ± 0.024 vs 0.322 ± 0.064; all P < 0.05). Optimum effects were achieved in the high-dose Lactobacillus acidophilus group.

CONCLUSION: Inhibition of transcriptional factors STAT1/T-bet activation maybe one mechanism contributing to the therapeutic effects of Lactobacillus acidophilus against ulcerative colitis.

Effect of probiotics on symptoms in korean adults with irritable bowel syndrome

Background/Aims

Irritable bowel syndrome (IBS) is a troublesome disease. Some strains of probiotics reportedly exert remarkable immunomodulatory effects, and so we designed a prospective double-blind randomized placebo-controlled clinical study to assess their effects in Korean adults with IBS.

Methods

IBS patients who met Rome III criteria were randomly assigned to receive composite probiotics or placebo. A total of 20 billion lyophilized bacteria were administered twice daily for 8 weeks. Primary outcome variables were symptom scores consisting of abdominal pain, flatulence, defecation discomfort, and sum of symptom scores. A visual analogue scale was used to quantify the severity. Secondary outcome variables consisted of the quality of life and bowel habits including defecation frequency and stool form.

Results

Thirty-six and 34 patients were randomized to the probiotics and placebo groups, respectively. Intention-to-treat analysis showed significant reductions in pain after 8 weeks of treatment: -31.9 and -17.7 in the probiotics and placebo groups, respectively (p=0.045). The reductions in abdominal pain, defecation discomfort, and sum of scores were more significant in 58 patients with a score of at least 3 on the baseline stool-form scale.

Conclusions

Composite probiotics containing Bifidobacterium bifidum BGN4, Lactobacillus acidophilus AD031, and other species are safe and effective, especially in patients who excrete normal or loose stools.

Commensal bacteria, traditional and opportunistic pathogens, dysbiosis and bacterial killing in inflammatory bowel diseases

PURPOSE OF REVIEW

The authors present evidence published during the past 2 years of the roles of commensal and pathogenic bacteria in the pathogenesis of the inflammatory bowel diseases.

RECENT FINDINGS

Rodent models conclusively implicate commensal enteric bacteria in chronic, immune-mediated, experimental colitis, and genetically determined defects in bacterial killing by innate immune cells are found in a subset of patients with Crohn's disease. There is no evidence that a single pathogen, including Mycobacterium avium subspecies paratuberculosis, causes Crohn's disease or ulcerative colitis. However, adherent/invasive Escherichia coli are associated with ileal Crohn's disease, with the mechanisms and genetics of adherent/invasive E. coli virulence being elucidated. Molecular characterization of the microbiota in patients with inflammatory bowel diseases reveals decreased biodiversity of commensal bacteria, most notably the phyla Bacteroidetes and Firmicutes, including the clinically relevant Faecalibacterium prausnitzii, and increased E. coli concentrations. VSL#3 is one probiotic preparation shown to be efficacious in certain clinical situations in small clinical trials.

SUMMARY

Further characterization of altered microbiota in patients with inflammatory bowel diseases and linking dysbiosis with host genetic alterations in immunoregulation, innate microbial killing and barrier function are critical, so that individualized treatments to increase beneficial commensals and their metabolic products (probiotic and prebiotic administration) and diminish deleterious species such as adherent/invasive E. coli can be tailored for defined patient subsets.

Probiotics, prebiotics, and synbiotics

According to the German definition, probiotics are defined viable microorganisms, sufficient amounts of which reach the intestine in an active state and thus exert positive health effects. Numerous probiotic microorganisms (e.g. Lactobacillus rhamnosus GG, L. reuteri, bifidobacteria and certain strains of L. casei or the L. acidophilus-group) are used in probiotic food, particularly fermented milk products, or have been investigated--as well as Escherichia coli strain Nissle 1917, certain enterococci (Enterococcus faecium SF68) and the probiotic yeast Saccharomyces boulardii--with regard to their medicinal use. Among the numerous purported health benefits attributed to probiotic bacteria, the (transient) modulation of the intestinal microflora of the host and the capacity to interact with the immune system directly or mediated by the autochthonous microflora, are basic mechanisms. They are supported by an increasing number of in vitro and in vivo experiments using conventional and molecular biologic methods. In addition to these, a limited number of randomized, well-controlled human intervention trials have been reported. Well-established probiotic effects are: 1. Prevention and/or reduction of duration and complaints of rotavirus-induced or antibiotic-associated diarrhea as well as alleviation of complaints due to lactose intolerance. 2. Reduction of the concentration of cancer-promoting enzymes and/or putrefactive (bacterial) metabolites in the gut. 3. Prevention and alleviation of unspecific and irregular complaints of the gastrointestinal tracts in healthy people. 4. Beneficial effects on microbial aberrancies, inflammation and other complaints in connection with: inflammatory diseases of the gastrointestinal tract, Helicobacter pylori infection or bacterial overgrowth. 5. Normalization of passing stool and stool consistency in subjects suffering from obstipation or an irritable colon. 6. Prevention or alleviation of allergies and atopic diseases in infants. 7. Prevention of respiratory tract infections (common cold, influenza) and other infectious diseases as well as treatment of urogenital infections. Insufficient or at most preliminary evidence exists with respect to cancer prevention, a so-called hypocholesterolemic effect, improvement of the mouth flora and caries prevention or prevention or therapy of ischemic heart diseases or amelioration of autoimmune diseases (e.g. arthritis). A prebiotic is "a selectively fermented ingredient that allows specific changes, both in the composition and/or activity in the gastrointestinal microflora that confers benefits upon host well being and health", whereas synergistic combinations of pro- and prebiotics are called synbiotics. Today, only bifidogenic, non-digestible oligosaccharides (particularly inulin, its hydrolysis product oligofructose, and (trans)galactooligosaccharides), fulfill all the criteria for prebiotic classification. They are dietary fibers with a well-established positive impact on the intestinal microflora. Other health effects of prebiotics (prevention of diarrhoea or obstipation, modulation of the metabolism of the intestinal flora, cancer prevention, positive effects on lipid metabolism, stimulation of mineral adsorption and immunomodulatory properties) are indirect, i.e. mediated by the intestinal microflora, and therefore less-well proven. In the last years, successful attempts have been reported to make infant formula more breast milk-like by the addition of fructo- and (primarily) galactooligosaccharides.

Probiotics and prebiotics in inflammatory bowel disease: microflora 'on the scope'

The intestinal microflora is a large bacterial community that colonizes the gut, with a metabolic activity equal to an organ and various functions that affect the physiology and pathology of the host's mucosal immune system. Intestinal bacteria are useful in promotion of human health, but certain components of microflora, in genetically susceptible individuals, contribute to various pathological disorders, including inflammatory bowel disease. Clinical and experimental observations indicate an imbalance in protective and harmful microflora components in these disorders. Manipulation of gut flora to enhance its protective and beneficial role represents a promising field of new therapeutic strategies of inflammatory bowel disease. In this review, we discuss the implication of gut flora in the intestinal inflammation that justifies the role of probiotics and prebiotics in the prevention and treatment of inflammatory bowel disease and we address the evidence for therapeutic benefits from their use in experimental models of colitis and clinical trials.