Fermentable fibres condition colon microbiota and promote diabetogenesis in NOD mice

The Impact of Essential Amino Acids on the Gut Microbiota of Broiler Chickens

The research involving the beneficial aspects of amino acids being added to poultry feed pertaining to performance, growth, feed intake, and feed conversion ratio is extensive. Yet currently the effects of amino acids on the gut microbiota aren't fully understood nor have there been many studies executed in poultry to explain the relationship between amino acids and the gut microbiota. The overall outcome of health has been linked to bird gut health due to the functionality of gastrointestinal tract (GIT) for digestion/absorption of nutrients as well as immune response. These essential functions of the GI are greatly driven by the resident microbiota which produce metabolites such as butyrate, propionate, and acetate, providing the microbiota a suitable and thrive driven environment. Feed, age, the use of feed additives and pathogenic infections are the main factors that have an effect on the microbial community within the GIT. Changes in these factors may have potential effects on the gut microbiota in the chicken intestine which in turn may have an influence on health essentially affecting growth, feed intake, and feed conversion ratio. This review will highlight limited research studies that investigated the possible role of amino acids in the gut microbiota composition of poultry.

Pectin from Fruit- and Berry-Juice Production by-Products: Determination of Physicochemical, Antioxidant and Rheological Properties

Plums (Prunus domestica); red currants (Ribes rubrum); black currants (Ribes nigrum); gooseberries (Ribes uva-crispa); sour cherries (Prunus cerasus); pumpkins (Cuccurbita spp.) are sources for valuable fruit- and berry-juice and cider production. This process leaves a large number of by-products (BP) in the form of pomace, which accounts for up to 80% of the raw material. This by-product represents a rich source of biologically active compounds, especially in the form of different pectic polysaccharides. The pectin extracted from commercial fruits such as citric fruits and apples has high medicinal properties, can be used as edible films and coatings, and is also useful in texture improvement and gel production in the food industry. However, many under-utilized fruits have received little attention regarding the extraction and characterization of their high/value pectin from their by-products. Moreover, the commercial extraction process involving strong acids and high temperature to obtain high-purity pectin leads to the loss of many bioactive components, and these lost components are often compensated for by the addition of synthetic antioxidants and colorants. The aim of the research is to extract pectin from juice production by-products with hot-water extraction using weak organic (0.1 N) citric acid, thus minimizing the impact on the environment. The yield of pectin (PY = 4.47-17.8% DM), galacturonic acid content (47.22-83.57 g 100^-1), ash content (1.42-2.88 g 100 g^-1), degree of esterification (DE = 45.16-64.06%), methoxyl content (ME = 4.27-8.13%), the total content of phenolic compounds (TPC = 2.076-4.668 µg mg^-1, GAE) and the antiradical scavenging activity of the pectin samples (DPPH method (0.56-37.29%)) were determined. Free and total phenolic acids were quantified by saponification using high-pressure liquid chromatography (HPLC). The pectin contained phenolic acids-benzoic (0.25-0.92 µg mg^-1), gallic (0.14-0.57 µg mg^-1), coumaric (0.04 µg mg^-1), and caffeic (0.03 µg mg^-1). The pectin extracts from by-products showed glucose and galactose (3.89-21.72 g 100 g^-1) as the main neutral sugar monosaccharides. Pectin analysis was performed using FT-IR, and the rheological properties of the pectin gels were determined. The quality of the obtained pectin from the fruit and berry by-products in terms of their high biological activity and high content of glucuronic acids indicated that the products have the potential to be used as natural ingredients in various food products and in pharmaceutical products.

Calorie restriction remodels gut microbiota and suppresses tumorigenesis of colorectal cancer in mice

Colorectal cancer (CRC) is one of the most common cancers worldwide and the consumption of a high-calorie diet is one of its risk factors. Calorie restriction (CR) slows tumor growth in a variety of cancers, including colorectal cancer; however, the mechanism behind this remains unknown. In the present study, CR effectively reduced the tumor volume and weight in a xenograft BALB/c male nude mouse model. In addition, tumor immunohistochemistry revealed that the CR group had significantly higher expression of Bax (P<0.001) and significantly lower levels of Bcl2 (P<0.0001) and Ki67 (P<0.001) compared with control group. Furthermore, data from 16S ribosomal (r)RNA sequencing implied that CR was able to reprogram the microbiota structure, characterized by increased Lactobacillus constituent ratio (P<0.05), with amelioration of microbial dysbiosis caused by CRC. Further receiver operating characteristic curves demonstrated that the bacteria Bacteroides [area under the curve (AUC)=0.800], Lactobacillus (AUC=0.760) and Roseburia (AUC=0.720) served key roles in suppression of CRC in the mouse model. The functional prediction of intestinal flora indicated 'cyanoamino acid metabolism' (P<0.01), 'replication initiation protein REP (rolling circle plasmid replication)' (P<0.01), 'tRNA G10 N-methylase Trm11' (P<0.01) and 'uncharacterized protein with cyclophilin fold, contains DUF369 domain' (P<0.05) were downregulated in CR group. These findings implied that CR suppressed CRC in mice and altered the gut microbiota.

Gut microbiota induces DNA methylation via SCFAs predisposing obesity-prone individuals to diabetes

Obesity-prone (OP) individuals have a significant predisposition to obesity and diabetes. Previously, we have found that OP individuals, despite being normal in weight and BMI, have already exhibited diabetes-related DNA methylation signatures. However, the underlying mechanisms remain obscure. Here we determined the effects of gut microbiota on DNA methylation and investigated the underlying mechanism from microbial-derived short-chain fatty acids (SCFAs). Diabetes-related DNA methylation loci were screened and validated in a new OP cohort. Moreover, the OP group was revealed to have distinct gut microbiota compositions, and fecal microbiota transplantation (FMT) demonstrated the role of gut microbiota in inducing diabetes-related DNA methylations and glucolipid disorders. UPLC-ESI-MS/MS analysis indicated a significantly lower level of total fecal SCFAs in the OP group. The gut microbiota from OP subjects yielded markedly decreased total SCFAs, while notably enriched propionate. Additionally, propionate was also identified by variable importance in projection (VIP) score as the most symbolic SCFAs of the OP group. Further cellular experiments verified that propionate could induce hypermethylation at locus cg26345888 and subsequently inhibit the expression of the target gene DAB1, which was crucially associated with clinical vitamin D deficiency and thus may affect the development and progression of diabetes. In conclusion, our study revealed that gut microbiota-derived propionate induces specific DNA methylation, thus predisposing OP individuals to diabetes. The findings partially illuminate the mechanisms of diabetes susceptibility in OP populations, implying gut microbiota and SCFAs may serve as promising targets both for clinical treatment and medication development of diabetes.

Distinct Diet-Microbiota-Metabolism Interactions in Overweight and Obese Pregnant Women: a Metagenomics Approach

Diet and gut microbiota are known to modulate metabolic health. Our aim was to apply a metagenomics approach to investigate whether the diet-gut microbiota-metabolism and inflammation relationships differ in pregnant overweight and obese women. This cross-sectional study was conducted in overweight (n = 234) and obese (n = 152) women during early pregnancy. Dietary quality was measured by a validated index of diet quality (IDQ). Gut microbiota taxonomic composition and species diversity were assessed by metagenomic profiling (Illumina HiSeq platform). Markers for glucose metabolism (glucose, insulin) and low-grade inflammation (high sensitivity C-reactive protein [hsCRP], glycoprotein acetylation [GlycA]) were analyzed from blood samples. Higher IDQ scores were positively associated with a higher gut microbiota species diversity (r = 0.273, P = 0.007) in obese women, but not in overweight women. Community composition (beta diversity) was associated with the GlycA level in the overweight women (P = 0.04) but not in the obese. Further analysis at the species level revealed a positive association between the abundance of species Alistipes finegoldii and the GlycA level in overweight women (logfold change = 4.74, P = 0.04). This study has been registered at ClinicalTrials.gov under registration no. NCT01922791 (https://clinicaltrials.gov/ct2/show/NCT01922791).

IMPORTANCE We observed partially distinct diet-gut microbiota-metabolism and inflammation responses in overweight and obese pregnant women. In overweight women, gut microbiota community composition and the relative abundance of A. finegoldii were associated with an inflammatory status. In obese women, a higher dietary quality was related to a higher gut microbiota diversity and a healthy inflammatory status.

Why is the Incidence of Type 1 Diabetes Increasing?

Type 1 diabetes is a condition that can lead to serious long-term complications and can have significant psychological and quality of life implications. Its incidence is increasing in all parts of the world, but the reasons for this are incompletely understood. Genetic factors alone cannot explain such a rapid increase in incidence; therefore, environmental factors must be implicated. Lifestyle factors have been classically associated with type 2 diabetes. However, there are data implicating obesity and insulin resistance to type 1 diabetes as well (accelerator hypothesis). Cholesterol has also been shown to be correlated with the incidence of type 1 diabetes; this may be mediated by immunomodulatory effects of cholesterol. There is considerable interest in early life factors, including maternal diet, mode of delivery, infant feeding, childhood diet, microbial exposure (hygiene hypothesis), and use of anti-microbials in early childhood. Distance from the sea has recently been shown to be negatively correlated with the incidence of type 1 diabetes. This may contribute to the increasing incidence of type 1 diabetes since people are increasingly living closer to the sea. Postulated mediating mechanisms include hours of sunshine (and possibly vitamin D levels), mean temperature, dietary habits, and pollution. Ozone, polychlorinated biphenyls, phthalates, trichloroethylene, dioxin, heavy metals, bisphenol, nitrates/nitrites, and mercury are amongst the chemicals which may increase the risk of type 1 diabetes. Another area of research concerns the role of the skin and gut microbiome. The microbiome is affected by many of the factors mentioned above, including the mode of delivery, infant feeding, exposure to microbes, antibiotic use, and dietary habits. Research on the reasons why the incidence of type 1 diabetes is increasing not only sheds light on its pathogenesis but also offers insights into ways we can prevent type 1 diabetes.

Evaluating the Causal Role of Gut Microbiota in Type 1 Diabetes and Its Possible Pathogenic Mechanisms

Type 1 diabetes (T1D) is a multifactorial autoimmune disease mediated by genetic, epigenetic, and environmental factors. In recent years, the emergence of high-throughput sequencing has allowed us to investigate the role of gut microbiota in the development of T1D. Significant changes in the composition of gut microbiome, also termed dysbiosis, have been found in subjects with clinical or preclinical T1D. However, whether the dysbiosis is a cause or an effect of the disease remains unclear. Currently, increasing evidence has supported a causal link between intestine microflora and T1D development. The current review will focus on recent research regarding the associations between intestine microbiome and T1D progression with an intention to evaluate the causality. We will also discuss the possible mechanisms by which imbalanced gut microbiota leads to the development of T1D.

Antidiabetic Effects of Soluble Dietary Fiber from Steam Explosion-Modified Black Soybean Hull in Low-Dose Streptozotocin-Induced Type 2 Diabetic Mouses

This paper studies the antidiabetic effects of soluble dietary fiber (SDF) from steam explosion-modified black soybean hull in low-dose streptozotocin- (STZ-) induced type 2 diabetic mouses. Male C57/BL6 mouses were divided into 4 groups: control (nondiabetic, no SDF intake), model (diabetes only), metformin (metformin: 100 mg/kg body weight), and SDF (SDF: 600 mg/kg body weight). Four weeks post-SDF treatment, treatment of SDF decreased the weight gain of diabetic mouses, normalised the blood glucose level, and reduced the serum cholesterol, serum insulin, leptin, glucagon-like peptide, total cholesterol, triglyceride, low-density lipoprotein cholesterol, arteriosclerosis index, aspartate aminotransferase activity, and malondialdehyde. It also increased high-density lipoprotein cholesterol, adiponectin, glycopeptide peroxidase, superoxide dismutase activity and repaired the pancreatic injury of the diabetic mouses. Our research results show that SDF has the potential for use in type 2 diabetes treatment.

Yield and Physicochemical Properties of Soluble Dietary Fiber Extracted from Untreated and Steam Explosion-Treated Black Soybean Hull

Black soybean hull was subjected to steam explosion (SE) treatment under different conditions to improve the yield and properties of soluble dietary fiber (SDF) extract. Optimal conditions for SE treatment were found to be moisture content of 15%, pressure level of 1.0 MPa, and treatment time of 80 s. Under these conditions, the yield of SDF increased from 10.20% to 17.49%. In addition, structural and functional properties of SDF from untreated and SE-treated black soybean hull were investigated. Soluble dietary fiber extracted from SE-treated hull exhibited lower molecular weight and improved functional properties, such as cholesterol-binding capacity, when compared to SDF extracted from untreated soybean hull. In addition, SDF extracted from SE-treated black soybean hull showed a rough surface structure, while a smooth surface structure was found for SDF extracted from the untreated hull. The obtained results indicate that SE treatment can be successfully used to enhance the yield and the property of yolk cholesterol absorption of SDF adsorption of yolk cholesterol functional properties of SDF from black soybean hull.

Effect of Prebiotic on Microbiota, Intestinal Permeability, and Glycemic Control in Children With Type 1 Diabetes

CONTEXT

Patients with type 1 diabetes (T1D) have lower microbiota diversity and distinct gut microbial profiles that have been linked to changes in intestinal permeability. Prebiotics are nondigestible carbohydrates that alter gut microbiota and could potentially improve glycemic control and reduce intestinal permeability and thereby insulin sensitivity.

OBJECTIVE

To determine the effect of prebiotics on glycemic control, gut microbiota, and intestinal permeability in children with T1D.

DESIGN

A randomized, placebo-controlled trial in children 8 to 17 years of age with T1D using placebo or prebiotic oligofructose-enriched inulin for 12 weeks. Baseline, 3-month, and 6-month assessments included HbA1c, C-peptide, gut microbiota, intestinal permeability, frequency of diabetic ketoacidosis (DKA), and severe hypoglycemia.

RESULTS

Forty-three subjects were randomized and 38 completed the study. The groups were similar at baseline: prebiotic (N = 17), age 12.5 years (SD of 2.8), HbA1c 8.02% (SD of 0.82); placebo (N = 21), age 12.0 years (SD of 2.6), HbA1c 8.08% (SD of 0.91). No significant differences were found in the frequency of DKA or severe hypoglycemia. At 3-months, C-peptide was significantly higher (P = 0.029) in the group who received prebiotics, which was accompanied by a modest improvement in intestinal permeability (P = 0.076). There was a significant increase in the relative abundance of Bifidobacterium within the prebiotic group at 3 months that was no longer present after the 3-month washout. The placebo group had significantly higher relative abundance of Streptococcus, Roseburia inulinivorans, Terrisporobacter, and Faecalitalea compared with the prebiotic group at 3 months.

CONCLUSION

Prebiotics are a potentially novel, inexpensive, low-risk treatment addition for T1D that may improve glycemic control. Further larger-scale trials are needed.

Association of Cereal, Gluten, and Dietary Fiber Intake With Islet Autoimmunity and Type 1 Diabetes

IMPORTANCE

Dietary proteins, such as gluten, have been suggested as triggers of the disease process in type 1 diabetes (T1D).

OBJECTIVE

To study the associations of cereal, gluten, and dietary fiber intake with the development of islet autoimmunity (IA) and T1D.

DESIGN, SETTING, AND PARTICIPANTS

The prospective birth cohort Finnish Type 1 Diabetes Prediction and Prevention Study recruited children with genetic susceptibility to type 1 diabetes from September 1996 to September 2004 from 2 university hospitals in Finland and followed up every 3 to 12 months up to 6 years for diet, islet autoantibodies, and T1D. Altogether 6081 infants (78% of those invited) participated in the study. Dietary data were available for 5714 children (94.0%) and dietary and IA data were available for 5545 children (91.2%), of whom 3762 (68%) had data on islet autoantibodies up to age 6 years. Information on T1D was available for all children. Data were analyzed in 2018 and end point data were updated in 2015.

EXPOSURES

Each child's intake of cereals, gluten, and dietary fiber was calculated from repeated 3-day food records up to 6 years.

MAIN OUTCOMES AND MEASURES

Islet autoimmunity was defined as repeated positivity for islet cell antibodies and at least 1 biochemical autoantibody of 3 analyzed, or T1D. Data on the diagnosis of T1D were obtained from Finnish Pediatric Diabetes Register.

RESULTS

Of 5545 children (2950 boys [53.2%]), 246 (4.4%) developed IA and of 5714 children (3033 boys [53.1%]), 90 (1.6%) developed T1D during the 6-year follow-up. Based on joint models, the intake of oats (hazard ratio [HR], 1.08; 95% CI, 1.03-1.13), wheat (HR, 1.09; 95% CI, 1.03-1.15), rye (HR, 1.13; 95% CI, 1.03-1.23), gluten-containing cereals (HR, 1.07; 95% CI, 1.03-1.11), gluten without avenin from oats (HR, 2.23; 95% CI, 1.40-3.57), gluten with avenin (HR, 2.06; 95% CI, 1.45-2.92), and dietary fiber (HR, 1.41; 95% CI, 1.10-1.81) was associated with the risk of developing IA (HRs for 1 g/MJ increase in intake). The intake of oats (HR, 1.10; 95% CI, 1.00-1.21) and rye (HR, 1.20; 95% CI, 1.03-1.41) was associated with the risk of developing T1D. After multiple testing correction, the associations with IA remained statistically significant.

CONCLUSIONS AND RELEVANCE

A high intake of oats, gluten-containing cereals, gluten, and dietary fiber was associated with an increased risk of IA. Further studies are needed to confirm or rule out the findings and study potential mechanisms.

Targeting gut microbiota and barrier function with prebiotics to alleviate autoimmune manifestations in NOD mice

AIMS/HYPOTHESIS

Adopting a diet containing indigestible fibre compounds such as prebiotics to fuel advantageous bacteria has proven beneficial for alleviating inflammation. The effect of the microbial changes on autoimmunity, however, remains unknown. We studied the effects of prebiotic xylooligosaccharides (XOS) on pancreatic islet and salivary gland inflammation in NOD mice and tested whether these were mediated by the gut microbiota.

METHODS

Mother and offspring mice were fed an XOS-supplemented diet until diabetes onset or weaning and were compared with a control-fed group. Diabetes incidence was monitored, insulitis and sialadenitis were scored in histological sections from adult mice, and several metabolic and immune variables were analysed in mice before the development of diabetes. Gut barrier function was assessed using an in vivo FITC-dextran permeability test. The importance of XOS-mediated gut microbial changes were evaluated in antibiotic-treated mice fed either XOS or control diet or given a faecal microbiota transplant from test animals.

RESULTS

Diabetes onset was delayed in the XOS-fed mice, which also had fewer cellular infiltrations in their pancreatic islets and salivary glands. Interestingly, insulitis was most reduced in the XOS-fed groups when the mice were also treated with an antibiotic cocktail. There was no difference in sialadenitis between the dietary groups treated with antibiotics; the mice were protected by microbiota depletion regardless of diet. Faecal microbiota transplantation was not able to transfer protection. No major differences in glucose-insulin regulation, glucagon-like peptide-1, or short-chain fatty acid production were related to the XOS diet. The XOS diet did, however, reduce gut permeability markers in the small and large intestine. This was accompanied by a more anti-inflammatory environment locally and systemically, dominated by a shift from M1 to M2 macrophages, a higher abundance of activated regulatory T cells, and lower levels of induction of natural killer T cells and cytotoxic T cells.

CONCLUSIONS/INTERPRETATION

Prebiotic XOS have microbiota-dependent effects on salivary gland inflammation and microbiota-independent effects on pancreatic islet pathology that are accompanied by an improved gut barrier that seems able to heighten control of intestinal diabetogenic antigens that have the potential to penetrate the mucosa to activate autoreactive immune responses.

Dissecting the role of the gut microbiota and diet on visceral fat mass accumulation

Both gut microbiota and diet have been shown to impact visceral fat mass (VFM), a major risk factor for cardiometabolic disease, but their relative contribution has not been well characterised. We aimed to estimate and separate the effect of gut microbiota composition from that of nutrient intake on VFM in 1760 older female twins. Through pairwise association analyses, we identified 93 operational taxonomic units (OTUs) and 10 nutrients independently linked to VFM (FDR < 5%). Conditional analyses revealed that the majority (87%) of the 93 VFM-associated OTUs remained significantly associated with VFM irrespective of nutrient intake correction. In contrast, we observed that the effect of fibre, magnesium, biotin and vitamin E on VFM was partially mediated by OTUs. Moreover, we estimated that OTUs were more accurate predictors of VFM than nutrients and accounted for a larger percentage of its variance. Our results suggest that while the role of certain nutrients on VFM appears to depend on gut microbiota composition, specific gut microbes may affect host adiposity regardless of dietary intake. The findings imply that the gut microbiota may have a greater contribution towards shaping host VFM than diet alone. Thus, microbial-based therapy should be prioritised for VFM reduction in overweight and obese subjects.

Overall Dietary Quality Relates to Gut Microbiota Diversity and Abundance

Disturbances in gut microbiota homeostasis may have metabolic consequences with potentially serious clinical manifestations. Diet influences the host's metabolic health in several ways, either directly or indirectly by modulating the composition and function of gut microbiota. This study investigated the extent to which dietary quality is reflected in gut microbiota diversity in overweight and obese pregnant women at risk for metabolic complications. Dietary quality was measured by a validated index of diet quality (IDQ) and microbiota composition was analyzed using 16SrRNA gene sequencing from 84 women pregnant less than 18 weeks. The alpha diversity, measured as Chao1, observed operational taxonomic units (OTUs), phylogenetic diversity, and the Shannon index were calculated. The IDQ score correlated positively with the Shannon index (rho = 0.319, p = 0.003), but not with the other indexes. The women who had the highest dietary quality (highest IDQ quartile) had higher gut microbiota diversity in all the investigated indexes, when compared to the women with the lowest dietary quality (lowest IDQ quartile; p < 0.032). Consequently, a higher dietary quality was reflected in a higher gut microbiota diversity. The presented approach may aid in devising new tools for dietary counseling aiming at holistic health, as well as in microbiome studies, to control for dietary variance.

High-Esterified Pectin Reverses Metabolic Malprogramming, Improving Sensitivity to Adipostatic/Adipokine Hormones

Detrimental metabolic programming has become a determinant factor in obesity propensity and the development of metabolic disorders; therefore, the search of nutritional strategies to reverse it is very relevant. Pectin is a prebiotic with health-promoting effects, such as control of glucose homeostasis and lipid metabolism, although other possible health effects and the prevention of obesity have been poorly studied. We studied the effects of chronic physiological supplementation with high-esterified pectin (HEP) in the reversion of metabolic nutrition-sensitive malprogramming associated with gestational undernutrition. As a model of nutrition-sensitive malprogramming, we used the progeny of rats with mild calorie restriction (CR) during pregnancy and analyzed their performance under metabolic stress (high-sucrose diet). We focused on the study of the sensitivity to the main adipostatic/adipokine hormones, i.e., leptin, insulin, and adiponectin, at both peripheral (liver and circulating parameters) and central (hypothalamus) levels. Our main findings suggest that chronic HEP supplementation is able to prevent weight/fat gain, to substantially reverse the detrimental malprogramming caused by the CR condition, to improve general health circulating markers, to modulate oxidative/lipogenic balance in the liver and energy metabolism regulators in the hypothalamus, and to restore/improve adipostatic/adipokine sensitivity affected by maternal calorie restriction, both peripherally and centrally. HEP stands out as a food component potentially useful against the development of metabolic disorders and obesity.

Akkermansia muciniphila induces gut microbiota remodelling and controls islet autoimmunity in NOD mice

OBJECTIVE

Intestinal microbiota is implicated in the pathogenesis of autoimmune type 1 diabetes in humans and in non-obese diabetic (NOD) mice, but evidence on its causality and on the role of individual microbiota members is limited. We investigated if different diabetes incidence in two NOD colonies was due to microbiota differences and aimed to identify individual microbiota members with potential significance.

DESIGN

We profiled intestinal microbiota between two NOD mouse colonies showing high or low diabetes incidence by 16S ribosomal RNA gene sequencing and colonised the high-incidence colony with the microbiota of the low-incidence colony. Based on unaltered incidence, we identified a few taxa which were not effectively transferred and thereafter, transferred experimentally one of these to test its potential significance.

RESULTS

Although the high-incidence colony adopted most microbial taxa present in the low-incidence colony, diabetes incidence remained unaltered. Among the few taxa which were not transferred, Akkermansia muciniphila was identified. As A. muciniphila abundancy is inversely correlated to the risk of developing type 1 diabetes-related autoantibodies, we transferred A. muciniphila experimentally to the high-incidence colony. A. muciniphila transfer promoted mucus production and increased expression of antimicrobial peptide Reg3γ, outcompeted Ruminococcus torques from the microbiota, lowered serum endotoxin levels and islet toll-like receptor expression, promoted regulatory immunity and delayed diabetes development.

CONCLUSION

Transfer of the whole microbiota may not reduce diabetes incidence despite a major change in gut microbiota, but single symbionts such as A. muciniphila with beneficial metabolic and immune signalling effects may reduce diabetes incidence when administered as a probiotic.

Type 1 diabetes: Through the lens of human genome and metagenome interplay

Diabetes is a genetic- and epigenetic-related disease from which a large population worldwide suffers. Some genetic factors along with various mutations related to the immune system for disease mechanism(s) have contrastively been determined. However, sometimes mechanisms have not been fully managed for the clarification of the initiation and/or progression of diseases to help patients. In the recent years, due to familiarity with the role of gut microbiota in the health, it has been found that the changes of the microbial balance in the industrialized societies can cause a battery of modern diseases, for which we have no specific definition of how they emerge. This work aims to explore the relationship between the human gut microbiota and the immune system along with their possible role in avoiding/emerging of type 1 diabetes (T1D) accompanied with the relation between genome and metagenome and their imbalance in causing T1D. Moreover, it provides novel view on how to balance the intestinal microbiota by lifestyle to hinder the mechanisms leading to T1D.

Maternal treatment with short-chain fatty acids modulates the intestinal microbiota and immunity and ameliorates type 1 diabetes in the offspring

We recently hypothesized that the intestinal microbiota and the innate immune system play key roles in the mechanism of Kilham Rat Virus-induced type 1 diabetes in the LEW1.WR1 rat. We used this animal model to test the hypothesis that maternal therapy with short-chain fatty acids can modulate the intestinal microbiota and reverse virus-induced proinflammatory responses and type 1 diabetes in rat offspring. We observed that administration of short-chain fatty acids to rat breeders via drinking water prior to pregnancy and further treatment of the offspring with short-chain fatty acids after weaning led to disease amelioration. In contrast, rats that were administered short-chain fatty acids beginning at weaning were not protected from type 1 diabetes. Short-chain fatty acid therapy exerted a profound effect on the intestinal microbiome in the offspring reflected by a reduction and an increase in the abundances of Firmicutes and Bacteroidetes taxa, respectively, on day 5 post-infection, and reversed virus-induced alterations in certain bacterial taxa. Principal component analysis and permutation multivariate analysis of variance tests further revealed that short-chain fatty acids induce a distinct intestinal microbiota compared with uninfected animals or rats that receive the virus only. Short-chain fatty acids downregulated Kilham Rat Virus-induced proinflammatory responses in the intestine. Finally, short-chain fatty acids altered the B and T cell compartments in Peyer’s patches. These data demonstrate that short-chain fatty acids can reshape the intestinal microbiota and prevent virus-induced islet autoimmunity and may therefore represent a useful therapeutic strategy for disease prevention.

Specific inulin-type fructan fibers protect against autoimmune diabetes by modulating gut immunity, barrier function, and microbiota homeostasis

SCOPE

Dietary fibers capable of modifying gut barrier and microbiota homeostasis affect the progression of type 1 diabetes (T1D). Here, we aim to compare modulatory effects of inulin-type fructans (ITFs), natural soluble dietary fibers with different degrees of fermentability from chicory root, on T1D development in nonobese diabetic mice.

METHODS AND RESULTS

Female nonobese diabetic mice were weaned to long- and short-chain ITFs [ITF(l) and ITF(s), 5%] supplemented diet up to 24 weeks. T1D incidence, pancreatic-gut immune responses, gut barrier function, and microbiota composition were analyzed. ITF(l) but not ITF(s) supplementation dampened the incidence of T1D. ITF(l) promoted modulatory T-cell responses, as evidenced by increased CD25⁺ Foxp3⁺ CD4⁺ regulatory T cells, decreased IL17A⁺ CD4⁺ Th17 cells, and modulated cytokine production profile in the pancreas, spleen, and colon. Furthermore, ITF(l) suppressed NOD like receptor protein 3 caspase-1-p20-IL-1β inflammasome in the colon. Expression of barrier reinforcing tight junction proteins occludin and claudin-2, antimicrobial peptides β-defensin-1, and cathelicidin-related antimicrobial peptide as well as short-chain fatty acid production were enhanced by ITF(l). Next-generation sequencing analysis revealed that ITF(l) enhanced Firmicutes/Bacteroidetes ratio to an antidiabetogenic balance and enriched modulatory Ruminococcaceae and Lactobacilli.

CONCLUSION

Our data demonstrate that ITF(l) but not ITF(s) delays the development of T1D via modulation of gut-pancreatic immunity, barrier function, and microbiota homeostasis.

Is there a role for gut microbiota in type 1 diabetes pathogenesis?

Type 1 diabetes mellitus (T1D) is an autoimmune disease characterized by insufficient insulin production due to the destruction of insulin secreting β-cells in the Langerhans islets. A variety of factors, including chemicals, viruses, commensal bacteria and diet have been proposed to contribute to the risk of developing the disorder. In the last years, gut microbiota has been proposed as a main factor in T1D pathogenesis. Several alterations of gut microbiota composition were described both in animal model and in humans. The decrease of Firmicutes/Bacteroides ratio was the most frequent pattern described, in particular, in human studies. Furthermore, Bacteroides, Clostridium cluster XIVa, Lactobacillus, Bifidobacterium, and Prevotella relative abundances were different in healthy and affected subjects. Dysbiosis would seem to increase intestinal permeability and thus promote the development of a pro-inflammatory niche that stimulates β-cell autoimmunity in predisposed subjects. Preliminary studies on animal models were realized to investigate the role of gut microbiota modulation as therapy or prevention approach in predisposed animals: promising and stimulating results have been reported. Key message Dietary antigens and microbiota-derived products might act as triggers of T1D by causing a pro-inflammatory and metabolic dysfunctional environment.

Role of intestinal microbiota and metabolites on gut homeostasis and human diseases

Background

A vast diversity of microbes colonizes in the human gastrointestinal tract, referred to intestinal microbiota. Microbiota and products thereof are indispensable for shaping the development and function of host innate immune system, thereby exerting multifaceted impacts in gut health.

Methods

This paper reviews the effects on immunity of gut microbe-derived nucleic acids, and gut microbial metabolites, as well as the involvement of commensals in the gut homeostasis. We focus on the recent findings with an intention to illuminate the mechanisms by which the microbiota and products thereof are interacting with host immunity, as well as to scrutinize imbalanced gut microbiota (dysbiosis) which lead to autoimmune disorders including inflammatory bowel disease (IBD), Type 1 diabetes (T1D) and systemic immune syndromes such as rheumatoid arthritis (RA).

Results

In addition to their well-recognized benefits in the gut such as occupation of ecological niches and competition with pathogens, commensal bacteria have been shown to strengthen the gut barrier and to exert immunomodulatory actions within the gut and beyond. It has been realized that impaired intestinal microbiota not only contribute to gut diseases but also are inextricably linked to metabolic disorders and even brain dysfunction.

Conclusions

A better understanding of the mutual interactions of the microbiota and host immune system, would shed light on our endeavors of disease prevention and broaden the path to our discovery of immune intervention targets for disease treatment.

Effects of exposure to bisphenol A and ethinyl estradiol on the gut microbiota of parents and their offspring in a rodent model

Gut dysbiosis may result in various diseases, such as metabolic and neurobehavioral disorders. Exposure to endocrine disrupting chemicals (EDCs), including bisphenol A (BPA) and ethinyl estradiol (EE), especially during development, may also increase the risk for such disorders. An unexplored possibility is that EDC-exposure might alter the gut microbial composition. Gut flora and their products may thus be mediating factors for the disease-causing effects of these chemicals. To examine the effects of EDCs on the gut microbiome, female and male monogamous and biparental California mice (Peromyscus californicus) were exposed to BPA (50 mg/kg feed weight) or EE (0.1 ppb) or control diet from periconception through weaning. 16s rRNA sequencing was performed on bacterial DNA isolated from fecal samples, and analyses performed for P₀ and F₁ males and females. Both BPA and EE induced generational and sex-dependent gut microbiome changes. Many of the bacteria, e.g. Bacteroides, Mollicutes, Prevotellaceae, Erysipelotrichaceae, Akkermansia, Methanobrevibacter, Sutterella, whose proportions increase with exposure to BPA or EE in the P₀ or F₁ generation are associated with different disorders, such as inflammatory bowel disease (IBD), metabolic disorders, and colorectal cancer. However, the proportion of the beneficial bacterium, Bifidobacterium, was also elevated in fecal samples of BPA- and EE-exposed F₁ females. Intestinal flora alterations were also linked to changes in various metabolic and other pathways. Thus, BPA and EE exposure may disrupt the normal gut flora, which may in turn result in systemic effects. Probiotic supplementation might be an effective means to mitigate disease-promoting effects of these chemicals.

Gut Microbiota Richness and Composition and Dietary Intake of Overweight Pregnant Women Are Related to Serum Zonulin Concentration, a Marker for Intestinal Permeability

BACKGROUND

Increased intestinal permeability may precede adverse metabolic conditions. The extent to which the composition of the gut microbiota and diet contribute to intestinal permeability during pregnancy is unknown.

OBJECTIVE

The aim was to investigate whether the gut microbiota and diet differ according to serum zonulin concentration, a marker of intestinal permeability, in overweight pregnant women.

METHODS

This cross-sectional study included 100 overweight women [mean age: 29 y; median body mass index (in kg/m(2)): 30] in early pregnancy (<17 wk of gestation; median: 13 wk). Serum zonulin (primary outcome) was determined by using ELISA, gut microbiota by 16S ribosomal RNA sequencing, and dietary intake of macro- and micronutrients from 3-d food diaries. The Mann-Whitney U test was used for pairwise comparisons and linear regression and Spearman's nonparametric correlations for relations between serum zonulin and other outcome variables.

RESULTS

Women were divided into "low" (<46.4 ng/mL) and "high" (≥46.4 ng/mL) serum zonulin groups on the basis of the median concentration of zonulin (46.4 ng/mL). The richness of the gut microbiota (Chao 1, observed species and phylogenetic diversity) was higher in the low zonulin group than in the high zonulin group (P = 0.01). The abundances of Bacteroidaceae and Veillonellaceae, Bacteroides and Blautia, and Blautia sp. were lower and of Faecalibacterium and Faecalibacterium prausnitzii higher (P < 0.05) in the low zonulin group than in the high zonulin group. Dietary quantitative intakes of n-3 (ω-3) polyunsaturated fatty acids (PUFAs), fiber, and a range of vitamins and minerals were higher (P < 0.05) in women in the low zonulin group than those in the high zonulin group.

CONCLUSIONS

The richness and composition of the gut microbiota and the intake of n-3 PUFAs, fiber, and a range of vitamins and minerals in overweight pregnant women are associated with serum zonulin concentration. Modification of the gut microbiota and diet may beneficially affect intestinal permeability, leading to improved metabolic health of both the mother and fetus. This trial was registered at clinicaltrials.gov as NCT01922791.

Intestinal Microbiota in Animal Models of Inflammatory Diseases

The intestinal microbiota has long been known to play an important role in the maintenance of health. In addition, alterations of the intestinal microbiota have recently been associated with a range of immune-mediated and metabolic disorders. Characterizing the composition and functionality of the intestinal microbiota, unravelling relevant microbe-host interactions, and identifying disease-relevant microbes are therefore currently of major interest in scientific and medical communities. Experimental animal models for the respective diseases of interest are pivotal in order to address functional questions on microbe-host interaction and to clarify the clinical relevance of microbiome alterations associated with disease initiation and development. This review presents an overview of the outcomes of highly sophisticated experimental studies on microbe-host interaction in animal models of inflammatory diseases, with a focus on inflammatory bowel disease (IBD). We will address the advantages and drawbacks of analyzing microbe-host interaction in complex colonized animal models compared with gnotobiotic animal models using monoassociation, simplified microbial consortia (SMC), or microbial humanization.

Cutting Edge: Commensal Microbiota Has Disparate Effects on Manifestations of Polyglandular Autoimmune Inflammation

Polyglandular autoimmune inflammation accompanies type 1 diabetes (T1D) in NOD mice, affecting organs like thyroid and salivary glands. Although commensals are not required for T1D progression, germ-free (GF) mice had a very low degree of sialitis, which was restored by colonization with select microbial lineages. Moreover, unlike T1D, which is blocked in mice lacking MyD88 signaling adaptor under conventional, but not GF, housing conditions, sialitis did not develop in MyD88(-/-) GF mice. Thus, microbes and MyD88-dependent signaling are critical for sialitis development. The severity of sialitis did not correlate with the degree of insulitis in the same animal and was less sensitive to a T1D-reducing diet, but it was similar to T1D with regard to microbiota-dependent sexual dimorphism. The unexpected distinction in requirements for the microbiota for different autoimmune pathologies within the same organism is crucial for understanding the nature of microbial involvement in complex autoimmune disorders, including human autoimmune polyglandular syndromes.

Akkermansia muciniphila and improved metabolic health during a dietary intervention in obesity: relationship with gut microbiome richness and ecology

OBJECTIVE

Individuals with obesity and type 2 diabetes differ from lean and healthy individuals in their abundance of certain gut microbial species and microbial gene richness. Abundance of Akkermansia muciniphila, a mucin-degrading bacterium, has been inversely associated with body fat mass and glucose intolerance in mice, but more evidence is needed in humans. The impact of diet and weight loss on this bacterial species is unknown. Our objective was to evaluate the association between faecal A. muciniphila abundance, faecal microbiome gene richness, diet, host characteristics, and their changes after calorie restriction (CR).

DESIGN

The intervention consisted of a 6-week CR period followed by a 6-week weight stabilisation diet in overweight and obese adults (N=49, including 41 women). Faecal A. muciniphila abundance, faecal microbial gene richness, diet and bioclinical parameters were measured at baseline and after CR and weight stabilisation.

RESULTS

At baseline A. muciniphila was inversely related to fasting glucose, waist-to-hip ratio and subcutaneous adipocyte diameter. Subjects with higher gene richness and A. muciniphila abundance exhibited the healthiest metabolic status, particularly in fasting plasma glucose, plasma triglycerides and body fat distribution. Individuals with higher baseline A. muciniphila displayed greater improvement in insulin sensitivity markers and other clinical parameters after CR. These participants also experienced a reduction in A. muciniphila abundance, but it remained significantly higher than in individuals with lower baseline abundance. A. muciniphila was associated with microbial species known to be related to health.

CONCLUSIONS

A. muciniphila is associated with a healthier metabolic status and better clinical outcomes after CR in overweight/obese adults. The interaction between gut microbiota ecology and A. muciniphila warrants further investigation.

TRIAL REGISTRATION NUMBER

NCT01314690.

The role of the intestinal microbiota in type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) is a chronic immune-mediated disease with a subclinical prodromal period, characterized by selective loss of insulin-producing-β cells in the pancreatic islets of genetically susceptible individuals. The incidence of T1DM has increased several fold in most developed countries since World War II, in conjunction with other immune-mediated diseases. Rapid environmental changes and modern lifestyles are probably the driving factors that underlie this increase. These effects might be mediated by changes in the human microbiota, particularly the intestinal microbiota. Research on the gut microbiome of individuals at risk of developing T1DM and in patients with established disease is still in its infancy, but initial findings indicate that the intestinal microbiome of individuals with prediabetes or diabetes mellitus is different to that of healthy individuals. The gut microbiota in individuals with preclinical T1DM is characterized by Bacteroidetes dominating at the phylum level, a dearth of butyrate-producing bacteria, reduced bacterial and functional diversity and low community stability. However, these changes seem to emerge after the appearance of autoantibodies that are predictive of T1DM, which suggests that the intestinal microbiota might be involved in the progression from β-cell autoimmunity to clinical disease rather than in the initiation of the disease process.

Microbial community profiles of the colon from steers differing in feed efficiency

Ruminal microbial fermentation plays an essential role in host nutrition, and as a result, the rumen microbiota have been a major focus of research examining bovine feed efficiency. Microbial communities within other sections of the gastrointestinal tract may also be important with regard to feed efficiency, since it is critical to the health and nutrition of the host. The objective of this study was to characterize the microbial communities of the colon among steers differing in feed efficiency. Individual feed intake (FI) and body weight (BW) gain were determined from animals fed the same ration, within two contemporary groups of steers. Four steers from each contemporary group within each Cartesian quadrant were sampled (n = 16/group) from the bivariate distribution of average daily BW gain and average daily FI. Bacterial 16S rRNA gene amplicons were sequenced from the colon content using next-generation sequencing technology. Within the colon content, UniFrac principal coordinate analyses did not detect any separation of microbial communities, and bacterial diversity or richness did not differ between efficiency groups. Relative abundances of microbial populations and operational taxonomic units did reveal significant differences between efficiency groups. The phylum Firmicutes accounted for up to 70% of the populations within all samples, and families Ruminococcaceae and Clostridiaceae were highly abundant. Significant population shifts in taxa were detected, including the families Ruminococcaceae, Lachnospiraceae, and Sphingomonadaceae, and the genera Butyrivibrio, Pseudobutyrivibrio, Prevotella, Faecalibacterium and Oscillospira. This study suggests the association of the colon microbial communities as a factor influencing feed efficiency at the 16S level.