Role of intestinal Bifidobacterium pseudolongum in dietary fructo-oligosaccharide inhibition of 2,4-dinitrofluorobenzene-induced contact hypersensitivity in mice

Daily Supplementation with Bifidobacterium longum KACC91563 Alleviates Allergic Contact Dermatitis in an Animal Model

Allergic contact dermatitis (ACD) is the most common chronic inflammatory skin disease (or immune-mediated disease), causing disruption to our psychological condition and life quality. In this study, the therapeutic properties of probiotic Bifidobacterium longum (B. longum) was investigated by using an ACD-induced animal model. For ACD induction, BALB/c mice ear and dorsal skin were sensitized with 240 µL of 1% (w/v) 2,4-dinitrochlorobenzene (DNCB) twice (3-day intervals). After a week of the first induction, the mice were re-sensitized by painting on their dorsal skin and ear with 0.4% (w/v) DNCB for a further three times (once per week). Before the ACD induction of 2 weeks and throughout the trial period, the BALB/c mice were supplemented daily with 1 mL of 1.0 × 109 CFU or 5.0 × 109 CFU B. longum using an intragastric gavage method. The ACD-induced mice without B. longum supplementation were used as a control. Results show that B. longum supplementation significantly alleviated ACD symptoms (e.g., ear swelling, epidermal damage) and immune response (e.g., reduced immune cell recruitment, serum IgE level, and cytokine production). The therapeutic efficiency of B. longum increased as the supplementation dose increased. Thus, daily supplementation with 5.0 × 109 CFU probiotic B. longum could be an effective method for the prevention and treatment of ACD.

Targeting IL-23 for the interception of obesity-associated colorectal cancer

Inflammation and obesity are two major factors that promote Colorectal cancer (CRC). Our recent data suggests that interleukin (IL)-23, is significantly elevated in CRC tumors and correlates with patient obesity, tumor grade and survival. Thus, we hypothesize that obesity and CRC may be linked via inflammation and IL-23 may be a potential target for intervention in high-risk patients. TCGA dataset and patient sera were evaluated for IL-23A levels. IL-23A [IL-23 p19-/-] knockout (KO) mice were crossed to Apcmin/+ mice and progeny were fed low-fat or high-fat diets. At termination intestines were evaluated for tumorigenesis. Tumors, serum, and fecal contents were analyzed for protein biomarkers, cytokines, and microbiome profile respectively. IL-23A levels are elevated in the sera of patients with obesity and colon tumors. Genetic ablation of IL-23A significantly suppressed colonic tumor multiplicity (76-96 %) and incidence (72-95 %) in male and female mice. Similarly, small-intestinal tumor multiplicity and size were also significantly reduced in IL-23A KO mice. IL-23A knockdown in Apcmin/+ mice fed high-fat diet, also resulted in significant suppression of colonic (50-58 %) and SI (41-48 %) tumor multiplicity. Cytokine profiling showed reduction in several circulating pro-inflammatory cytokines including loss of IL-23A. Biomarker analysis suggested reduced tumor cell proliferation and immune modulation with an increase in tumor-infiltrating CD4+ and CD8+ T-lymphocytes in the IL-23A KO mice compared to controls. Fecal microbiome analysis revealed potentially beneficial changes in the bacterial population profile. In summary, our data indicates a tumor promoting role for IL-23 in CRC including diet-induced obesity. With several IL-23 targeted therapies in clinical trials, there is a great potential for targeting this cytokine for CRC prevention and therapy.

Extraction, Physicochemical Properties, Functional Activities and Applications of Inulin Polysaccharide: a Review

Inulin is a naturally soluble dietary fiber that is widely distributed and primarily derived from plants. As a reserve biopolysaccharide in plants, inulin is considered an indigestible carbohydrate of fructan because of its unique β-(2,1)-glycosidic bond structure. Numerous recent animal and human experimental studies have shown that functional inulin possesses multiple bioactivities, including immunomodulatory, antioxidant, antitumor, hepatoprotective, hypoglycemic, and gastrointestinal protective activities. Due to its increasing popularity, people tend to consume foods containing inulin. Moreover, inulin holds promise as a bioactive compound for use in the development of various food products. Therefore, this paper provides a detailed review of the extraction method, physicochemical properties, functional activity, and application development of inulin polysaccharides, to provide a theoretical foundation for further advancements in the fields of preparation and application of functional foods.

Administration of Bifidobacterium pseudolongum suppresses the increase of colonic serotonin and alleviates symptoms in dextran sodium sulfate-induced colitis in mice

Previous studies suggested that altered gut serotonin (5-HT) signaling is implicated in the pathophysiology of inflammatory bowel disease (IBD). Indeed, 5-HT administration reportedly exacerbated the severity of murine dextran sodium sulfate (DSS)-induced colitis that mimics human IBD. Our recent study suggested that Bifidobacterium pseudolongum, one of the most predominant bifidobacterial species in various mammals, reduces the colonic 5-HT content in mice. The present study thus tested whether the administration of B. pseudolongum prevents DSS-induced colitis in mice. Colitis was induced by administering 3% DSS in drinking water in female BALB/c mice, and B. pseudolongum (10⁹ CFU/day) or 5-aminosalicylic acid (5-ASA, 200 mg/kg body weight) was intragastrically administered once daily throughout the experimental period. B. pseudolongum administration reduced body weight loss, diarrhea, fecal bleeding, colon shortening, spleen enlargement, and colon tissue damage and increased colonic mRNA levels of cytokine genes (Il1b, Il6, Il10, and Tnf) almost to an extent similar to 5-ASA administration in DSS-treated mice. B. pseudolongum administration also reduced the increase of colonic 5-HT content, whereas it did not alter the colonic mRNA levels of genes that encode the 5-HT synthesizing enzyme, 5-HT reuptake transporter, 5-HT metabolizing enzyme, and tight junction-associated proteins. We propose that B. pseudolongum is as beneficial against murine DSS-induced colitis as the widely used anti-inflammatory agent 5-ASA. However, further studies are needed to clarify the causal relationship between the reduced colonic 5-HT content and reduced severity of DSS-induced colitis caused by B. pseudolongum administration.

Modulation of allergic contact dermatitis via gut microbiota modified by diet, vitamins, probiotics, prebiotics, and antibiotics

Allergic contact dermatitis is one of the most common recorded occupational diseases. There are many different substances that the skin comes into contact with on a daily basis and that can cause ACD, e.g., preservatives, surfactants, and antimicrobial agents. The development of a mouse model of ACD has provided insight into the immune mechanisms involved. Drugs used in the treatment of skin diseases have many side effects. Therefore, alternative methods of suppressing the immune response to reduce the symptoms of skin diseases are being sought. In recent years, high hopes have been placed on dietary modulation and supplementation to affect the intestinal microbial composition and promote anti-inflammatory responses. In addition, other studies have shown the crucial role of intestinal microbiota in many immune-mediated diseases. Recognition and characterization of pro- and anti-inflammatory nutrients and supplements may be crucial to support the treatment of diseases such as atopic dermatitis, acne vulgaris, psoriasis, and allergic contact dermatitis.

Impact of Dietary Arachidonic Acid on Gut Microbiota Composition and Gut-Brain Axis in Male BALB/C Mice

Although arachidonic acid (ARA) is the precursor of the majority of eicosanoids, its influence as a food component on health is not well known. Therefore, we investigated its impact on the gut microbiota and gut-brain axis. Groups of male BALB/c mice were fed either a standard diet containing 5% lipids (Std-ARA) or 15%-lipid diets without ARA (HL-ARA) or with 1% ARA (HL + ARA) for 9 weeks. Fatty acid profiles of all three diets were the same. The HL-ARA diet favored the growth of Bifidobacterium pseudolongum contrary to the HL + ARA diet that favored the pro-inflammatory Escherichia-Shigella genus in fecal microbiota. Dietary ARA intake induced 4- and 15-fold colic overexpression of the pro-inflammatory markers IL-1β and CD40, respectively, without affecting those of TNFα and adiponectin. In the brain, dietary ARA intake led to moderate overexpression of GFAP in the hippocampus and cortex. Both the hyperlipidic diets reduced IL-6 and IL-12 in the brain. For the first time, it was shown that dietary ARA altered the gut microbiota, led to low-grade colic inflammation, and induced astrogliosis in the brain. Further work is necessary to determine the involved mechanisms.

Synergy between oligosaccharides and probiotics: From metabolic properties to beneficial effects

Synbiotic is defined as the dietary mixture that comprises both probiotic microorganisms and prebiotic substrates. The concept has been steadily gaining attention owing to the rising recognition of probiotic, prebiotics, and gut health. Among prebiotic substances, oligosaccharides demonstrated considerable health beneficial effects in varieties of food products and their combination with probiotics have been subjected to full range of evaluations. This review delineated the landscape of studies using microbial cultures, cell lines, animal model, and human subjects to explore the functional properties and host impacts of these combinations. Overall, the results suggested that these combinations possess respective metabolic properties that could facilitate beneficial activities therefore could be employed as dietary interventions for human health improvement and therapeutic purposes. However, uncertainties, such as applicational practicalities, underutilized analytical tools, contradictory results in studies, unclear mechanisms, and legislation hurdles, still challenges the broad utilization of these combinations. Future studies to address these issues may not only advance current knowledge on probiotic-prebiotic-host interrelationship but also promote respective applications in food and nutrition.

Faecalibaculum rodentium remodels retinoic acid signaling to govern eosinophil-dependent intestinal epithelial homeostasis

The intestinal epithelium plays critical roles in sensing and integrating dietary and microbial signals. How microbiota and intestinal epithelial cell (IEC) interactions regulate host physiology in the proximal small intestine, particularly the duodenum, is unclear. Using single-cell RNA sequencing of duodenal IECs under germ-free (GF) and different conventional microbiota compositions, we show that specific microbiota members alter epithelial homeostasis by increasing epithelial turnover rate, crypt proliferation, and major histocompatibility complex class II (MHCII) expression. Microbiome profiling identified Faecalibaculum rodentium as a key species involved in this regulation. F. rodentium decreases enterocyte expression of retinoic-acid-producing enzymes Adh1, Aldh1a1, and Rdh7, reducing retinoic acid signaling required to maintain certain intestinal eosinophil populations. Eosinophils suppress intraepithelial-lymphocyte-mediated production of interferon-γ that regulates epithelial cell function. Thus, we identify a retinoic acid-eosinophil-interferon-γ-dependent circuit by which the microbiota modulates duodenal epithelial homeostasis.

Role of Bifidobacteria on Infant Health

Bifidobacteria are among the predominant microorganisms during infancy, being a dominant microbial group in the healthy breastfed infant and playing a crucial role in newborns and infant development. Not only the levels of the Bifidobacterium genus but also the profile and quantity of the different bifidobacterial species have been demonstrated to be of relevance to infant health. Although no definitive proof is available on the causal association, reduced levels of bifidobacteria are perhaps the most frequently observed alteration of the intestinal microbiota in infant diseases. Moreover, Bifidobacterium strains have been extensively studied by their probiotic attributes. This review compiles the available information about bifidobacterial composition and function since the beginning of life, describing different perinatal factors affecting them, and their implications on different health alterations in infancy. In addition, this review gathers exhaustive information about pre-clinical and clinical studies with Bifidobacterium strains as probiotics in neonates.

Colonized Niche, Evolution and Function Signatures of Bifidobacterium pseudolongum within Bifidobacterial Genus

Background: Although genomic features of various bifidobacterial species have received much attention in the past decade, information on Bifidobacterium pseudolongum was limited. In this study, we retrieved 887 publicly available genomes of bifidobacterial species, and tried to elucidate phylogenetic and potential functional roles of B. pseudolongum within the Bifidobacterium genus. Results: The results indicated that B. pseudolongum formed a population structure with multiple monophyletic clades, and had established associations with different types of mammals. The abundance of B. pseudolongum was inversely correlated with that of the harmful gut bacterial taxa. We also found that B. pseudolongum showed a strictly host-adapted lifestyle with a relatively smaller genome size, and higher intra-species genetic diversity in comparison with the other tested bifidobacterial species. For functional aspects, B. pseudolongum showed paucity of specific metabolic functions, and enrichment of specific enzymes degrading complex plant carbohydrates and host glycans. In addition, B. pseudolongum possessed a unique signature of probiotic effector molecules compared with the other tested bifidobacterial species. The investigation on intra-species evolution of B. pseudolongum indicated a clear evolution trajectory in which considerable clade-specific genes, and variation on genomic diversity by clade were observed. Conclusions: These findings provide valuable information for explaining the host adaptability of B. pseudolongum, its evolutionary role, as well as its potential probiotic effects.

Daily Lifestyle and Inflammatory Skin Diseases

Throughout life, it is necessary to adapt to the Earth’s environment in order to survive. A typical example of this is that the daily Earth cycle is different from the circadian rhythm in human beings; however, the ability to adapt to the Earth cycle has contributed to the development of human evolution. In addition, humans can consume and digest Earth-derived foods and use luxury materials for nutrition and enrichment of their lives, as an adaptation to the Earth’s environment. Recent studies have shown that daily lifestyles are closely related to human health; however, less attention has been paid to the fact that obesity due to excessive energy intake, smoking, and alcohol consumption contributes to the development of inflammatory skin diseases. Gluten or wheat protein, smoking and alcohol, sleep disturbance, and obesity drive the helper T (Th)1/Th2/Th17 immune response, whereas dietary fiber and omega-3 fatty acids negatively regulate inflammatory cytokine production. In this review, we have focused on daily lifestyles and the mechanisms involved in the pathogenesis of inflammatory skin diseases.

Consumption of indigestible saccharides and administration of Bifidobacterium pseudolongum reduce mucosal serotonin in murine colonic mucosa

SCFA increase serotonin (5-hydroxytryptamine, 5-HT) synthesis and content in the colon in vitro and ex vivo, but little is known in vivo. We tested whether dietary indigestible saccharides, utilised as a substrate to produce SCFA by gut microbiota, would increase colonic 5-HT content in mice. Male C57BL/6J mice were fed a purified diet and water supplemented with 4 % (w/v) 1-kestose (KES) for 2 weeks. Colonic 5-HT content and enterochromaffin (EC) cell numbers were lower in mice supplemented with KES than those without supplementation, while monoamine oxidase A activity and mRNA levels of tryptophan hydroxylase 1 (Tph1), chromogranin A (Chga), Slc6a4 and monoamine oxidase A (Maoa) genes in the colonic mucosa, serum 5-HT concentration and total 5-HT content in the colonic contents did not differ between groups. Caecal acetate concentration and Bifidobacterium pseudolongum population were higher in KES-supplemented mice. Similar trends were observed in mice supplemented with other indigestible saccharides, that is, fructo-oligosaccharides, inulin and raffinose. Intragastric administration of live B. pseudolongum (108 colony-forming units/d) for 2 weeks reduced colonic 5-HT content and EC cell numbers. These results suggest that changes in synthesis, reuptake, catabolism and overflow of 5-HT in the colonic mucosa are not involved in the reduction of colonic 5-HT content by dietary indigestible saccharides in mice. We propose that gut microbes including B. pseudolongum could contribute to the reduction of 5-HT content in the colonic mucosa via diminishing EC cells.

Dietary prebiotics promote intestinal Prevotella in association with a low-responding phenotype in a murine oxazolone-induced model of atopic dermatitis

Atopic dermatitis is a chronic eczema commonly observed among children in Western countries. The gut microbiota is a significant factor in the pathogenesis, and ways to promote intestinal colonizers with anti-inflammatory capabilities are therefore favorable. The present study addressed the effects of a prebiotic, xylooligosaccharide (XOS), on the gut microbiota and ear inflammation in an oxazolone-induced dermatitis model in BALB/c mice. Mice were fed a XOS supplemented or a control diet throughout the experiment. Ear thickness and clinical skin inflammation were scored blindly after three weeks topical challenge with 0.4% oxazolone. The mice were divided into high and low responders to oxazolone-induced dermatitis based on clinical inflammation and histological evaluation of ear biopsies, and significantly fewer high responders were present in the XOS fed group. In addition, XOS fed mice had higher abundance of Prevotella spp. in their gut microbiota compared to the control fed mice. Serum IgE and ear tissue cytokine levels correlated significantly with the clinical scores, and with the abundance of Prevotella spp. The strong association between the low-responding phenotype and high abundance of Prevotella spp., indicates an alleviating effect of this intestinal colonizer in allergic sensitization. Prevotella should be considered as a relevant target for future microbiota-directed treatment strategies in atopic patients.

Intestinal microbiota transplantation reveals the role of microbiota in dietary regulation of RegIIIβ and RegIIIγ expression in mouse intestine

RegIIIβ and RegIIIγ are antimicrobial peptides expressed in intestinal epithelial cells. Expression of these peptides is reportedly decreased by high-fat diet (HFD) and increased by indigestible oligosaccharides in mice. Clearly, these dietary regimens change the structure of intestinal microbiota. We employed an intestinal microbiota transplantation (IMT) to test whether diet-induced changes in the expression of these peptides are mediated by gut microbiota. C57BL/6J mice were fed either a normal-fat diet (NFD), a HFD, or a NFD supplemented with or without 1-kestose (KES), an indigestible oligosaccharide. Ileal RegIIIβ and RegIIIγ mRNA levels were lower in mice receiving IMT from HFD-fed mice than in those receiving NFD-fed mice and higher in mice receiving IMT from KES-supplemented mice than in those receiving the mice without KES supplementation. Western blot analysis showed that serum RegIIIβ levels changed in parallel with the ileal mRNA levels. We propose that HFD- and KES-induced changes in the ileal RegIIIβ and RegIIIγ expression and in the circulating RegIIIβ levels are mediated, at least in part, by intestinal microbiota.

Distinct actions of the fermented beverage kefir on host behaviour, immunity and microbiome gut-brain modules in the mouse

BACKGROUND

Mounting evidence suggests a role for the gut microbiota in modulating brain physiology and behaviour, through bi-directional communication, along the gut-brain axis. As such, the gut microbiota represents a potential therapeutic target for influencing centrally mediated events and host behaviour. It is thus notable that the fermented milk beverage kefir has recently been shown to modulate the composition of the gut microbiota in mice. It is unclear whether kefirs have differential effects on microbiota-gut-brain axis and whether they can modulate host behaviour per se.

METHODS

To address this, two distinct kefirs (Fr1 and UK4), or unfermented milk control, were administered to mice that underwent a battery of tests to characterise their behavioural phenotype. In addition, shotgun metagenomic sequencing of ileal, caecal and faecal matter was performed, as was faecal metabolome analysis. Finally, systemic immunity measures and gut serotonin levels were assessed. Statistical analyses were performed by ANOVA followed by Dunnett's post hoc test or Kruskal-Wallis test followed by Mann-Whitney U test.

RESULTS

Fr1 ameliorated the stress-induced decrease in serotonergic signalling in the colon and reward-seeking behaviour in the saccharin preference test. On the other hand, UK4 decreased repetitive behaviour and ameliorated stress-induced deficits in reward-seeking behaviour. Furthermore, UK4 increased fear-dependent contextual memory, yet decreased milk gavage-induced improvements in long-term spatial learning. In the peripheral immune system, UK4 increased the prevalence of Treg cells and interleukin 10 levels, whereas Fr1 ameliorated the milk gavage stress-induced elevation in neutrophil levels and CXCL1 levels. Analysis of the gut microbiota revealed that both kefirs significantly changed the composition and functional capacity of the host microbiota, where specific bacterial species were changed in a kefir-dependent manner. Furthermore, both kefirs increased the capacity of the gut microbiota to produce GABA, which was linked to an increased prevalence in Lactobacillus reuteri.

CONCLUSIONS

Altogether, these data show that kefir can signal through the microbiota-gut-immune-brain axis and modulate host behaviour. In addition, different kefirs may direct the microbiota toward distinct immunological and behavioural modulatory effects. These results indicate that kefir can positively modulate specific aspects of the microbiota-gut-brain axis and support the broadening of the definition of psychobiotic to include kefir fermented foods. Video abstract.

Study of the alleviation effects of a combination of Lactobacillus rhamnosus and inulin on mice with colitis

Ulcerative colitis (UC) is a common inflammatory bowel disease (IBD) that has serious harmful effects on human health. Lactobacillus rhamnosus, a probiotic, has a strong colonization and adhesion effect and improves the intestinal health of the host. Inulin has good anti-inflammatory effects and can promote the proliferation of beneficial intestinal bacteria. The purpose of this study was to investigate the alleviating effects of L. rhamnosus 1.0320 in combination with inulin on UC, examining the resulting changes in intestinal flora. A UC model was established by having mice freely drink a 3% (w/v) dextran sodium sulphate (DSS) solution for seven days. After successful modeling, the mice were given antibiotics, L. rhamnosus 1.0320 by itself, inulin by itself, and L. rhamnosus 1.0320 combined with inulin as an intragastric intervention for 28 days. The abundance and structural changes of bacteria in the intestinal content of mice were analyzed by 16S rDNA high-throughput sequencing. The study found that male BALB/c mice can successfully establish a typical model of small intestinal inflammation by freely drinking a 3% DSS solution for one week. L. rhamnosus 1.0320 combined with inulin can alleviate DSS-induced colitis, reduce the Disease Activity Index (DAI) score of the pathological damage of colon tissue, decrease myeloperoxidase (MPO) activity, increase hemoglobin content, and regulate the expression levels of inflammatory cytokines IL-1β, IL-6, TNF-α and IL-10. The intestinal flora of mice is reduced after enteritis, and its structure gets disordered. The combination of L. rhamnosus 1.0320 and inulin can increase the abundance and diversity of intestinal flora, and increase the content of beneficial bacteria. Prebiotics promote the colonization ability of probiotics. L. rhamnosus 1.0320 combined with inulin can change the intestinal flora to relieve ulcerative colitis, providing a new theoretical basis for the study of UC mechanism.

Intestinal dysbiosis mediates experimental autoimmune pancreatitis via activation of plasmacytoid dendritic cells

Autoimmune pancreatitis (AIP) is a pancreatic manifestation of a newly proposed disease entity, IgG4-related disease (IgG4-RD), characterized by enhanced IgG4 antibody responses and involvement of multiple organs. We have previously reported that innate immune activation contributes to the development of AIP and IgG4-RD, as these diseases are characterized by the production of IFN-α and IL-33 by plasmacytoid dendritic cells (pDCs) that mediate chronic fibroinflammatory responses. In this study, we investigated the roles played by innate immunity against intestinal microflora in experimental AIP induced in MRL/MpJ mice by repeated administrations of 100 µg of polyinosinic-polycytidylic acid [poly (I:C)]. Bowel sterilization with a broad spectrum of antibiotics inhibited pancreatic accumulation of pDCs producing IFN-α and IL-33, and thereby suppressed the development of AIP. Mice treated with 10 µg of poly (I:C) developed severe AIP equivalent to that induced by 100 µg of poly (I:C) upon co-housing with mice treated with 100 µg of poly (I:C). Fecal microbiota transplantation (FMT) from donor mice treated with 100 µg of poly (I:C) led to the development of severe AIP in the recipient mice upon injection with 10 µg of poly (I:C). Induction of severe AIP in mice with 10 µg of poly (I:C) was associated with pancreatic accumulation of pDCs producing IFN-α and IL-33 in the co-housing and FMT experiments. These data collectively suggest that innate immune responses against intestinal microflora are involved in the development of experimental AIP, and that intestinal dysbiosis increases sensitivity to experimental AIP via activation of pDCs.

Fermentable Dietary Fiber Promotes Helminth Infection and Exacerbates Host Inflammatory Responses

Fermentable dietary fibers promote the growth of beneficial bacteria, can enhance mucosal barrier integrity, and reduce chronic inflammation. However, effects on intestinal type 2 immune function remain unclear. In this study, we used the murine whipworm Trichuris muris to investigate the effect of the fermentable fiber inulin on host responses to infection regimes that promote distinct Th1 and Th2 responses in C57BL/6 mice. In uninfected mice, dietary inulin stimulated the growth of beneficial bacteria, such as Bifidobacterium (Actinobacteria) and Akkermansia (Verrucomicrobia). Despite this, inulin prevented worm expulsion in normally resistant mice, instead resulting in chronic infection, whereas mice fed an equivalent amount of nonfermentable fiber (cellulose) expelled worms normally. Lack of expulsion in the mice fed inulin was accompanied by a significantly Th1-skewed immune profile characterized by increased T-bet⁺ T cells and IFN-γ production in mesenteric lymph nodes, increased expression of Ido1 in the cecum, and a complete absence of mast cell and IgE production. Furthermore, the combination of dietary inulin and high-dose T. muris infection caused marked dysbiosis, with expansion of the Firmicutes and Proteobacteria phyla, near elimination of Bacteroidetes, and marked reductions in cecal short-chain fatty acids. Neutralization of IFN-γ during infection abrogated Ido1 expression and was sufficient to restore IgE production and worm expulsion in inulin-fed mice. Our results indicate that, whereas inulin promoted gut health in otherwise healthy mice, during T. muris infection, it exacerbated inflammatory responses and dysbiosis. Thus, the positive effects of fermentable fiber on gut inflammation appear to be context dependent, revealing a novel interaction between diet and infection.

Modulation of the Gut Microbiota during High-Dose Glycerol Monolaurate-Mediated Amelioration of Obesity in Mice Fed a High-Fat Diet

Obesity and associated metabolic disorders are worldwide public health issues. The gut microbiota plays a key role in the pathophysiology of diet-induced obesity. Glycerol monolaurate (GML) is a widely consumed food emulsifier with antibacterial properties. Here, we explore the anti-obesity effect of GML (1,600 mg/kg of body weight) in high-fat diet (HFD)-fed mice. HFD-fed mice were treated with 1,600 mg/kg GML. Integrated microbiome, metabolome, and transcriptome analyses were used to systematically investigate the metabolic effects of GML, and antibiotic treatment was used to assess the effects of GML on the gut microbiota.

Obesity and associated metabolic disorders are worldwide public health issues. The gut microbiota plays a key role in the pathophysiology of diet-induced obesity. Glycerol monolaurate (GML) is a widely consumed food emulsifier with antibacterial properties. Here, we explore the anti-obesity effect of GML (1,600 mg/kg of body weight) in high-fat diet (HFD)-fed mice. HFD-fed mice were treated with 1,600 mg/kg GML. Integrated microbiome, metabolome, and transcriptome analyses were used to systematically investigate the metabolic effects of GML, and antibiotic treatment was used to assess the effects of GML on the gut microbiota. Our data indicated that GML significantly reduced body weight and visceral fat deposition, improved hyperlipidemia and hepatic lipid metabolism, and ameliorated glucose homeostasis and inflammation in HFD-fed mice. Importantly, GML modulated HFD-induced gut microbiota dysbiosis and selectively increased the abundance of Bifidobacterium pseudolongum. Antibiotic treatment abolished all the GML-mediated metabolic improvements. A multiomics (microbiome, metabolome, and transcriptome) association study showed that GML significantly modulated glycerophospholipid metabolism, and the abundance of Bifidobacterium pseudolongum strongly correlated with the metabolites and genes that participated in glycerophospholipid metabolism. Our results indicated that GML may be provided for obesity prevention by targeting the gut microbiota and regulating glycerophospholipid metabolism.

An improved rat model for chronic inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease (IBD) is an important cause of chronic disability in humans.

METHODS

We characterized a model of chronic IBD in young male Wistar rats by administering dextran sodium sulfate (DSS: 0%, 0.25%, 0.5%, or 1% in drinking water) for six weeks, with 0.5% DSS for twelve weeks, following DSS cessation or together with treatment with sulfasalazine for the last 6 weeks. We measured gastrointestinal characteristics including stool consistency, blood in stools, small intestine and colon length, intestinal transit and permeability, and gut microbiota, as well as extra-intestinal parameters including oral glucose tolerance, systolic blood pressure, fat and lean mass, and left ventricular stiffness.

RESULTS

At 6 weeks, 0.25-1% DSS produced gastrointestinal changes as diarrhea and blood in stools. At 12 weeks, 0.5% DSS produced chronic and sustained gastrointestinal changes, with marked infiltration of inflammatory cells throughout the gastrointestinal tract and crypt distortion. Firmicutes increased and Bacteroidetes and Actinobacteria decreased in DSS-treated rats. Changes were reversed by DSS cessation or sulfasalazine treatment. Gastrointestinal permeability and extra-intestinal parameters did not change, so DSS changes were limited to the gastrointestinal tract.

CONCLUSION

Chronic 0.5% DSS produces selective and reversible gastrointestinal changes, providing an improved chronic model in rats that mimics human IBD for testing new interventions.

Short-chain fatty acids and inulin, but not guar gum, prevent diet-induced obesity and insulin resistance through differential mechanisms in mice

The role of dietary fibre and short-chain fatty acids (SCFA) in obesity development is controversially discussed. Here, we investigated how various types of dietary fibre and different SCFA ratios affect metabolic syndrome-related disorders. Male mice (B6) were fed high-fat diets supplemented with dietary fibres (either cellulose, inulin or guar gum) or different Ac:Pr ratios (high acetate (HAc) or propionate (HPr)) for 30 weeks. Body-fat gain and insulin resistance were greatly reduced by inulin, but not by guar gum, and completely prevented by SCFA supplementation. Only inulin and HAc increased body temperature, possibly by the induction of beige/browning markers in WAT. In addition, inulin and SCFA lowered hepatic triglycerides and improved insulin sensitivity. Both, inulin and HAc reduced hepatic fatty acid uptake, while only inulin enhanced mitochondrial capacity and only HAc suppressed lipogenesis in liver. Interestingly, HPr was accompanied by the induction of Nrg4 in BAT. Fermentable fibre supplementation increased the abundance of bifidobacteria; B. animalis was particularly stimulated by inulin and B. pseudolongum by guar gum. We conclude that in contrast to guar gum, inulin and SCFA prevent the onset of diet-induced weight gain and hepatic steatosis by different mechanisms on liver and adipose tissue metabolism.

Polymannuronic acid ameliorated obesity and inflammation associated with a high-fat and high-sucrose diet by modulating the gut microbiome in a murine model

Polymannuronic acid (PM), one of numerous alginates isolated from brown seaweeds, is known to possess antioxidant activities. In this study, we examined its potential role in reducing body weight gain and attenuating inflammation induced by a high-fat and high-sucrose diet (HFD) as well as its effect on modulating the gut microbiome in mice. A 30-d PM treatment significantly reduced the diet-induced body weight gain and blood TAG levels (P2·0). PM also had a profound impact on the microbial composition in the gut microbiome and resulted in a distinct microbiome structure. For example, PM significantly increased the abundance of a probiotic bacterium, Lactobacillus reuteri (log10 LDA score>2·0). Together, our results suggest that PM may exert its immunoregulatory effects by enhancing proliferation of several species with probiotic activities while repressing the abundance of the microbial taxa that harbor potential pathogens. Our findings should facilitate mechanistic studies on PM as a potential bioactive compound to alleviate obesity and the metabolic syndrome.

Changes in the bacterial community in the fermentation process of kôso, a Japanese sugar-vegetable fermented beverage

Kôso is a Japanese fermented beverage made with over 20 kinds of vegetables, mushrooms, and sugars. The changes in the bacterial population of kôso during fermentation at 25 °C over a period of 10 days were studied using 454 pyrosequencing of the 16S rRNA gene. The analysis detected 224 operational taxonomic units (OTUs) clustered from 8 DNA samples collected on days 0, 3, 7, and 10 from two fermentation batches. Proteobacteria were the dominant phylum in the starting community, but were replaced by Firmicutes within three days. Seventy-eight genera were identified from the 224 OTUs, in which Bifidobacterium, Leuconostoc, Lactococcus, and Lactobacillus dominated, accounting for over 96% of the total bacterial population after three days’ fermentation. UniFrac–Principal Coordinate Analysis of longitudinal fermented samples revealed dramatic changes in the bacterial community in kôso, resulting in significantly low diversity at the end of fermentation as compared with the complex starting community.

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.