The "perfect storm" for type 1 diabetes: the complex interplay between intestinal microbiota, gut permeability, and mucosal immunity

The Effect of Microbiome-Modulating Agents (MMAs) on Type 1 Diabetes: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Gut microbiome-modulating agents (MMAs), including probiotics, prebiotics, postbiotics, and synbiotics, are shown to ameliorate type 1 diabetes (T1D) by restoring the microbiome from dysbiosis. The objective of this systematic review and meta-analysis was to assess the impact of MMAs on hemoglobin A1c (HbA1c) and biomarkers associated with (T1D). A comprehensive search was conducted in PubMed, Web of Science, Embase, Cochrane Library, National Knowledge Infrastructure, WeiPu, and WanFang Data up to 30 November 2023. Ten randomized controlled trials (n = 630) were included, with study quality evaluated using the Cochrane risk-of-bias tool. Random-effect models with standardized mean differences (SMDs) were utilized. MMA supplementation was associated with improvements in HbA1c (SMD = -0.52, 95% CI [-0.83, -0.20]), daily insulin usage (SMD = -0.41, 95% confidence interval (CI) [-0.76, -0.07]), and fasting C-peptide (SMD = 0.99, 95% CI [0.17, 1.81]) but had no effects on FBG, CRP, TNF-α, IL-10, LDL, HDL, and the Shannon index. Subgroup analysis of HbA1c indicated that a long-term intervention (>3 months) might exert a more substantial effect. These findings suggest an association between MMAs and glycemic control in T1D. Further large-scale clinical trials are necessary to confirm these findings with investigations on inflammation and gut microbiota composition while adjusting confounding factors such as diet, physical activity, and the dose and form of MMA intervention.

Irisin delays the onset of type 1 diabetes in NOD mice by enhancing intestinal barrier

Type 1 diabetes (T1D), a complex autoimmune disease, is intricately linked to the gut's epithelial barrier function. Emerging evidence emphasizes the role of irisin, an exercise-related hormone, in preserving intestinal integrity. This study investigates whether irisin could delay T1D onset by enhancing the colon intestinal barrier. Impaired colon intestinal barriers were observed in newly diagnosed T1D patients and non-obese diabetic (NOD) mice, worsening with age and accompanied by islet inflammation. Using an LPS-induced colonic inflammation model, a dose-dependent impact of LPS on colon cells irisin expression, secretion, and barrier function was revealed. Exogenous irisin demonstrated remarkable effects, mitigating islet insulitis, enhancing energy expenditure, and alleviating autoimmune symptoms by reducing colon intestinal permeability. Single-cell RNA sequencing (scRNA-seq) highlighted irisin's positive impact on colon epithelial cell clusters, effectively restoring the intestinal barrier. Irisin also selectively modulated bacterial composition, averting potential bacterial translocation. Mechanistically, irisin enhanced colon intestinal barrier tight junction proteins through the AMPK/PI3K/AKT pathway, with FAM120A playing a crucial role. Irisin upregulated MUC3 expression, a protector against damage and inflammation. Harnessing irisin's exercise-mimicking properties suggests therapeutic potential in clinical settings for preventing T1D progression, offering valuable insights into fortifying the colon's intestinal barrier and managing autoimmune conditions associated with T1DM.

Research progress on the mechanism of TCM regulating intestinal microbiota in the treatment of DM mellitus

In recent years, with the improvement of people's living standards, the incidence of DM has increased year by year in China. DM is a common metabolic syndrome characterized by hyperglycemia caused by genetic, environmental and other factors. At the same time, long-term suffering from DM will also have an impact on the heart, blood vessels, eyes, kidneys and nerves, and associated serious diseases. The human body has a large and complex gut microbiota, which has a significant impact on the body's metabolism. Research shows that the occurrence and development of DM and its complications are closely related to intestinal microbiota. At present, western medicine generally treats DM with drugs. The hypoglycemic effect is fast and strong, but it can have a series of side effects on the human body. Compared with western medicine, Chinese medicine has its unique views and methods in treating DM. TCM can improve symptoms and treat complications by improving the imbalance of microbiota in patients with DM. Its characteristics of health, safety, and reliability are widely accepted by the general public. This article reviews the relationship between intestinal microbiota and DM, as well as the mechanism of TCM intervention in DM by regulating intestinal microbiota.

Hypoglycemic effects and associated mechanisms of resveratrol and related stilbenes in diet

Hyperglycemia has become a global health problem due to changes in diet and lifestyle. Most importantly, persistent hyperglycemia can eventually develop into type II diabetes. While the usage of current drugs is limited by their side effects, stilbenes derived from fruits and herbal/dietary plants are considered as important phytochemicals with potential hypoglycemic properties. Herein, the most common stilbenoids in consumed foods, i.e. resveratrol, pterostilbene, piceatannol, oxyresveratrol, and 2,3,5,4'-tetrahydroxystilbene-2-O-β-glucopyranoside (THSG), are reviewed in this paper. These stilbenes are found to regulate glucose homeostasis via (a) modulation of feeding behaviour and nutrition absorption; (b) restoration of insulin signalling by enhancing insulin production/insulin sensitivity; (c) improvement of gut permeability, gut microbial profile and resulting metabolomes; and (d) amelioration of circadian rhythm disruption. In this review, we have summarized the underlying mechanisms for the hypoglycemic effects of the five most common dietary stilbenoids listed above, providing a comprehensive framework for future study and applications.

A2 milk consumption and its health benefits: an update

Milk is a widely consumed nutrient-rich food containing protein variants such as casein A2 and A1. A1 differs from A2 in an amino acid at position 67 (Pro67 to His67). The breakdown of β-casein yields β-casomorphins (BCM), among which BCM-7 is extensively studied for its effects on the human body. Animal studies have shown that A1 β-casein milk increases digestive transit time and enhances myeloperoxidase activity. Individuals with lactose intolerance prefer A2 milk to conventional A1 milk, as BCM-7 in A1 milk can lead to inflammation and discomfort in sensitive individuals. A2 milk, which contains A2 β-casein, is believed to be more easily digestible than A1 β-casein. Its popularity has grown owing to reports linking A1 casein to diseases such as type 1 diabetes, heart disease, and autism. A2 milk has gained popularity as an alternative to A1 milk, primarily because of its potential benefits for individuals with certain diseases. This review aims to provide an updated understanding of A2 milk consumption and its health benefits. This review aims to provide an updated understanding of A2 milk consumption and its health benefits.

Effects of maternal type 1 diabetes and confounding factors on neonatal microbiomes

AIMS/HYPOTHESIS

Body niche-specific microbiota in maternal-neonatal dyads from gravidae with type 1 diabetes have not been quantitatively and functionally examined. Similarly, the impact of pregnancy-specific factors, such as the presence of comorbidities known to occur more frequently among gravidae with type 1 diabetes, including Caesarean delivery, as well as antibiotic prophylaxis, level of glycaemic control during each trimester of pregnancy and insulin administration, has not been adequately considered. The aims of this study were to characterise the maternal and neonatal microbiomes, assess aspects of microbiota transfer from the maternal microbiomes to the neonatal microbiome and explore the impact of type 1 diabetes and confounding factors on the microbiomes.

METHODS

In this observational case-control study, we characterised microbiome community composition and function using 16S rRNA amplicon sequencing in a total of 514 vaginal, rectal and ear-skin swabs and stool samples derived from 92 maternal-neonatal dyads (including 50 gravidae with type 1 diabetes) and in-depth clinical metadata from throughout pregnancy and delivery.

RESULTS

Type 1 diabetes-specific microbiota were identified among gravidae with type 1 diabetes and their neonates. Neonatal microbiome profiles of ear-skin swabs and stool samples were established, indicating the taxa more prevalent among neonates born to mothers with type 1 diabetes compared with neonates born to control mothers. Without taking into account the type 1 diabetes status of mothers, both delivery mode and intrapartum antibiotic prophylaxis were found to have an influence on neonatal microbiota composition (both p=0.001). In the logistic regression analysis involving all confounding variables, neonatal ear-skin microbiome variation was explained by maternal type 1 diabetes status (p=0.020) and small for gestational age birthweight (p=0.050). Moreover, in women with type 1 diabetes, a relationship was found between HbA1c levels >55 mmol/mol (>7.2%) measured in the first trimester of pregnancy and neonatal ear-skin microbiota composition (p=0.008). In the PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) assessment, pathways concerning carbohydrate biosynthesis were predicted as key elements of the microbial functional profiles dysregulated in type 1 diabetes. Additionally, in SourceTracker analysis, we found that, on average, 81.0% of neonatal microbiota was attributed to maternal sources. An increase in the contribution of maternal rectum microbiota and decrease in the contribution of maternal cervix microbiota were found in ear-skin samples of vaginally delivered neonates of mothers with type 1 diabetes compared with neonates born to control mothers (83.2% vs 59.5% and 0.7% vs 5.2%, respectively).

CONCLUSIONS/INTERPRETATION

These findings indicate that, in addition to maternal type 1 diabetes, glycaemic dysregulation before/in the first trimester of pregnancy, mode of delivery and intrapartum antibiotic prophylaxis may contribute to the inoculation and formation of the neonatal microbiomes.

DATA AVAILABILITY

The BioProject (PRJNA961636) and associated SRA metadata are available at http://www.ncbi.nlm.nih.gov/bioproject/961636 . Processed data on probiotic supplementation and the PICRUSt analysis are available in the Mendeley Data Repository ( https://doi.org/10.17632/g68rwnnrfk.1 ).

Zonulin as a Biomarker for the Development of Celiac Disease

OBJECTIVES

Increased intestinal permeability seems to be a key factor in the pathogenesis of autoimmune diseases, including celiac disease (CeD). However, it is unknown whether increased permeability precedes CeD onset. This study's objective was to determine whether intestinal permeability is altered before celiac disease autoimmunity (CDA) in at-risk children. We also examined whether environmental factors impacted zonulin, a widely used marker of gut permeability.

METHODS

We evaluated 102 children in the CDGEMM study from 2014-2022. We included 51 CDA cases and matched controls, who were enrolled for 12 months or more and consumed gluten. We measured serum zonulin from age 12 months to time of CDA onset, and the corresponding time point in controls, and examined clinical factors of interest. We ran a mixed-effects longitudinal model with dependent variable zonulin.

RESULTS

Children who developed CDA had a significant increase in zonulin in the 18.3 months (range 6-78) preceding CDA compared to those without CDA (slope differential = β = 0.1277, 95% CI: 0.001, 0.255). Among metadata considered, zonulin trajectory was only influenced by increasing number of antibiotic courses, which increased the slope of trajectory of zonulin over time in CDA subjects (P = .04).

CONCLUSIONS

Zonulin levels significantly rise in the months that precede CDA diagnosis. Exposure to a greater number of antibiotic courses was associated with an increase in zonulin levels in CDA subjects. This suggests zonulin may be used as a biomarker for preclinical CeD screening in at-risk children, and multiple antibiotic courses may increase their risk of CDA by increasing zonulin levels.

Engineered probiotics introduced to improve intestinal microecology for the treatment of chronic diseases: present state and perspectives

Purpose

Correcting intestinal microecological imbalance has become one of the core strategies to treat chronic diseases. Some traditional microecology-based therapies targeting intestine, such as prebiotic therapy, probiotic therapy and fecal microbiota transplantation therapy, have been used in the prevention and treatment of clinical chronic diseases, which still facing low safety and poor controllability problems. The development of synthetic biology technology has promoted the development of intestinal microecology-based therapeutics for chronic diseases, which exhibiting higher robustness and controllability, and become an important part of the next generation of microecological therapy. The purpose of this review is to summarize the application of synthetic biology in intestinal microecology-based therapeutics for chronic diseases.

Methods

The available literatures were searched to find out experimental studies and relevant review articles on the application of synthetic biology in intestinal microecology-based therapeutics for chronic diseases from year 1990 to 2023.

Results

Evidence proposed that synthetic biology has been applied in the intestinal microecology-based therapeutics for chronic diseases, covering metabolic diseases (e.g. diabetes, obesity, nonalcoholic fatty liver disease and phenylketonuria), digestive diseases (e.g. inflammatory bowel disease and colorectal cancer), and neurodegenerative diseases (e.g. Alzheimer's disease and Parkinson's disease).

Conclusion

This review summarizes the application of synthetic biology in intestinal microecology-based therapeutics for major chronic diseases and discusses the opportunities and challenges in the above process, providing clinical possibilities of synthetic biology technology applied in microecological therapies.

Fecal microbiota transplantation in the treatment of systemic lupus erythematosus: What we learnt from the explorative clinical trial

Systemic lupus erythematosus (SLE) is an autoimmune disease with the characterized presence of autoantibodies and resulting in multiple organ damage, which is incurable and can be lethal. The current treatments are limited and less progress has been made in drug discovery for the last few decades. Researches imply that gut dysbiosis exists in both patients and murine models with SLE, taking part in the pathogenesis of SLE through multiple mechanisms such as microbiota translocation and molecular mimicry. Intestinal interventions on the gut microbiome by fecal transplantations to reconstitute the gut-immunity homeostasis serve as a novel therapeutic option for SLE patients. Fecal microbiota transplantation (FMT), which is usually used in intestinal diseases, has been firstly demonstrated to be safe and efficient in recovering gut microbiota structure of SLE patients and reducing lupus activity in our recent clinical trial, which is the first trial testing FMT therapy in SLE treatment. In this paper, we reviewed the results of the single-arm clinical trial and made recommendations on FMT practice in SLE treatment including therapeutic indications, screening items and dosage regimen, trying to provide references for future study and clinical practice. We also came up with the unanswered questions that need to be solved by the ongoing randomized controlled trial as well as the future expectations for the intestinal intervention strategies of SLE patients.

Dendrobium huoshanense Polysaccharide Improves High-Fat Diet Induced Liver Injury by Regulating the Gut-Liver Axis

Dendrobium huoshanense is an important Traditional Chinese medicine that thickens the stomach and intestines. Its active ingredient Dendrobium huoshanense polysaccharide (DHP), was revealed to relieve the symptoms of liver injury. However, its mechanism of action remains poorly understood. This study aimed to investigate the mechanism of DHP in protecting the liver. The effects of DHP on lipid levels, liver function, and intestinal barrier function were investigated in mice with high-fat diet-induced liver damage. Changes in the gut flora and their metabolites were analyzed using 16S rRNA sequencing and metabolomics. The results showed that DHP reduced lipid levels, liver injury, and intestinal permeability. DHP altered the intestinal flora structure and increased the relative abundance of Bifidobacterium animalis and Clostridium disporicum. Furthermore, fecal metabolomics revealed that DHP altered fecal metabolites and significantly increased levels of gut-derived metabolites, spermidine, and indole, which have been reported to inhibit liver injury and improve lipid metabolism and the intestinal barrier. Correlation analysis showed that spermidine and indole levels were significantly negatively correlated with liver injury-related parameters and positively correlated with the intestinal species B. animalis enriched by DHP. Overall, this study confirmed that DHP prevented liver injury by regulating intestinal microbiota dysbiosis and fecal metabolites.

Ketone Bodies in Diabetes Mellitus: Friend or Foe?

In glucose-deprived conditions, ketone bodies are produced by the liver mitochondria, through the catabolism of fatty acids, and are used peripherally, as an alternative energy source. Ketones are produced in the body under normal conditions, including during pregnancy and the neonatal period, when following a ketogenic diet (KD), fasting, or exercising. Additionally, ketone synthesis is also augmented under pathological conditions, including cases of diabetic ketoacidosis (DKA), alcoholism, and several metabolic disorders. Nonetheless, diet is the main regulator of total body ketone concentrations. The KDs are mimicking the fasting state, altering the default metabolism towards the use of ketones as the primary fuel source. Recently, KD has gained recognition as a medical nutrition therapy for a plethora of metabolic conditions, including obesity and diabetes mellitus (DM). The present review aims to discuss the role of ketones, KDs, ketonemia, and ketonuria in DM, presenting all the available new evidence in a comprehensive manner.

Important denominator between autoimmune comorbidities: a review of class II HLA, autoimmune disease, and the gut

Human leukocyte antigen (HLA) genes are associated with more diseases than any other region of the genome. Highly polymorphic HLA genes produce variable haplotypes that are specifically correlated with pathogenically different autoimmunities. Despite differing etiologies, however, many autoimmune disorders share the same risk-associated HLA haplotypes often resulting in comorbidity. This shared risk remains an unanswered question in the field. Yet, several groups have revealed links between gut microbial community composition and autoimmune diseases. Autoimmunity is frequently associated with dysbiosis, resulting in loss of barrier function and permeability of tight junctions, which increases HLA class II expression levels and thus further influences the composition of the gut microbiome. However, autoimmune-risk-associated HLA haplotypes are connected to gut dysbiosis long before autoimmunity even begins. This review evaluates current research on the HLA-microbiome-autoimmunity triplex and proposes that pre-autoimmune bacterial dysbiosis in the gut is an important determinant between autoimmune comorbidities with systemic inflammation as a common denominator.

Exploring the interactive mechanism of acarbose with the amylase SusG in the starch utilization system of the human gut symbiont Bacteroides thetaiotaomicron through molecular modeling

The α-amylase, SusG, is a principal component of the Bacteroides thetaiotaomicron (Bt) starch utilization system (Sus) used to metabolize complex starch molecules in the human gastrointestinal (GI) tract. We previously reported the non-microbicidal growth inhibition of Bt by the acarbose-mediated arrest of the Sus as a potential therapeutic strategy. Herein, we report a computational approach using density functional theory (DFT), molecular docking, and molecular dynamics (MD) simulation to explore the interactive mechanism between acarbose and SusG at the atomic level in an effort to understand how acarbose shuts down the Bt Sus. The docking analysis reveals that acarbose binds orthosterically to SusG with a binding affinity of -8.3 kcal/mol. The MD simulation provides evidence of conformational variability of acarbose at the active site of SusG and also suggests that acarbose interacts with the main catalytic residues via a general acid-base double-displacement catalytic mechanism. These results suggest that small molecule competitive inhibition against the SusG protein could impact the entire Bt Sus and eliminate or reduce the system's ability to metabolize starch. This computational strategy could serve as a potential avenue for structure-based drug design to discover other small molecules capable of inhibiting the Sus of Bt with high potency, thus providing a holistic approach for selective modulation of the GI microbiota.

Constipation in DM are associated with both poor glycemic control and diabetic complications: Current status and future directions

Constipation is a major complications of diabetes mellitus. With the accelerating prevalence of diabetes worldwide and an aging population, there is considerable research interest regarding the altered function and structure of the gastrointestinal tract in diabetic patients. Despite current advances in hyperglycemic treatment strategies, the specific pathogenesis of diabetic constipation remains unknown. Patients with constipation, may be reluctant to eat regularly, which may worsen glycemic control and thus worsen symptoms associated with underlying diabetic bowel disease. This paper presents a review of the complex relationship between diabetes and constipation, exploring the morphological alterations and biomechanical remodeling associated with intestinal motility dysfunction, as well as alterations in intestinal neurons, cellular signaling pathways, and oxidative stress. Further studies focusing on new targets that may play a role in the pathogenesis of diabetic constipation may, provide new ideas for the development of novel therapies to treat or even prevent diabetic constipation.

Infant Feeding, Gut Permeability, and Gut Inflammation Markers

OBJECTIVES

Increased gut permeability and gut inflammation have been linked to the development of type 1 diabetes. Little is known on whether and how intake of different foods is linked to these mechanisms in infancy. We investigated whether the amount of breast milk and intake of other foods are associated with gut inflammation marker concentrations and permeability.

METHODS

Seventy-three infants were followed from birth to 12 months of age. Their diet was assessed with structured questionnaires and 3-day weighed food records at the age of 3, 6, 9, and 12 months. Gut permeability was assessed with the lactulose/mannitol test and fecal calprotectin and human β-defensin-2 (HBD-2) concentrations were analyzed from stool samples at the age of 3, 6, 9, and 12 months. The associations between foods and gut inflammation marker concentrations and permeability were analyzed using generalized estimating equations.

RESULTS

Gut permeability and gut inflammation marker concentrations decreased during the first year of life. Intake of hydrolyzed infant formula ( P = 0.003) and intake of fruits and juices ( P = 0.001) were associated with lower intestinal permeability. Intake of fruits and juices ( P < 0.001), vegetables ( P < 0.001), and oats ( P = 0.003) were associated with lower concentrations of HBD-2. Higher intake of breast milk was associated with higher fecal calprotectin concentrations ( P < 0.001), while intake of fruits and juices ( P < 0.001), vegetables ( P < 0.001), and potatoes ( P = 0.007) were associated with lower calprotectin concentrations.

CONCLUSIONS

Higher intake of breast milk may contribute to higher calprotectin concentration, whereas several complementary foods may decrease gut permeability and concentrations of calprotectin and HBD-2 in infant gut.

The interplay between oral microbiota, gut microbiota and systematic diseases

Over the past two decades, the importance of microbiota in health and disease has become evident. The human gut microbiota and oral microbiota are the largest and second-largest microbiome in the human body, respectively, and they are physically connected as the oral cavity is the beginning of the digestive system. Emerging and exciting evidence has shown complex and important connections between gut microbiota and oral microbiota. The interplay of the two microbiomes may contribute to the pathological processes of many diseases, including diabetes, rheumatoid arthritis, nonalcoholic fatty liver disease, inflammatory bowel disease, pancreatic cancer, colorectal cancer, and so on. In this review, we discuss possible routes and factors of oral microbiota to affect gut microbiota, and the contribution of this interplay between oral and gut microbiota to systemic diseases. Although most studies are association studies, recently, there have been increasing mechanistic investigations. This review aims to enhance the interest in the connection between oral and gut microbiota, and shows the tangible impact of this connection on human health.

Alterations of the intestinal mucus layer correlate with dysbiosis and immune dysregulation in human Type 1 Diabetes

BACKGROUND

In preclinical models of Type 1 Diabetes (T1D) the integrity of the gut barrier (GB) is instrumental to avoid dysregulated crosstalk between the commensal microbiota and immune cells and to prevent autoimmunity. The GB is composed of the intestinal epithelial barrier (IEB) and of the mucus layer containing mucins and antimicrobial peptides (AMPs) that are crucial to maintain immune tolerance. In preclinical models of T1D the alterations of the GB primarily affect the mucus layer. In human T1D increased gut permeability and IEB damage have been demonstrated but the integrity of the mucus layer was never assessed.

METHODS

We evaluated GB integrity by measuring serological markers of IEB damage (serological levels of zonulin) and bacterial translocation such as lipopolysaccharide binding protein (LBP) and myeloid differentiation protein 2 (MD2), and mRNA expression of tight junction proteins, mucins and AMPs in intestinal tissue of T1D patients and healthy controls (HC). Simultaneously, we performed immunological profiling on intestinal tissue and 16S rRNA analysis on the mucus-associated gut microbiota (MAGM).

FINDINGS

Our data show a GB damage with mucus layer alterations and reduced mRNA expression of several mucins (MUC2, MUC12, MUC13, MUC15, MUC20, MUC21) and AMPs (HD4 and HD5) in T1D patients. Mucus layer alterations correlated with reduced relative abundance of short chain fatty acids (SCFA)-producing bacteria such as Bifidobacterium dentium, Clostridium butyricum and Roseburia intestinalis that regulate mucin expression and intestinal immune homeostasis. In T1D patients we also found intestinal immune dysregulation with higher percentages of effector T cells such as T helper (Th) 1, Th17 and TNF-α⁺ T cells.

INTERPRETATION

Our data show that mucus layer alterations are present in T1D subjects and associated with dysbiosis and immune dysregulation.

FUNDING

Research Grants from the Juvenile Diabetes Foundation (Grant 1-INO-2018-640-A-N to MF and 2-SRA-2019-680-S-B to JD) and from the Italian Ministry of Health (Grant RF19-12370721 to MF).

Infant gut microbiome composition correlated with type 1 diabetes acquisition in the general population: the ABIS study

AIMS/HYPOTHESIS

While autoantibodies are traditional markers for type 1 diabetes development, we identified gut microbial biomarkers in 1-year-old infants associated with future type 1 diabetes up to 20 years before diagnosis.

METHODS

Infants enrolled in the longitudinal general population cohort All Babies In Southeast Sweden (ABIS) provided a stool sample at a mean age of 12.5 months. Samples (future type 1 diabetes, n=16; healthy controls, n=268) were subjected to 16S ribosomal RNA (rRNA) sequencing and quantitative PCR. Microbial differences at the taxonomic and core microbiome levels were assessed. PICRUSt was used to predict functional content from the 16S rRNA amplicons. Sixteen infants, with a future diagnosis of type 1 diabetes at a mean age of 13.3±5.4 years, and one hundred iterations of 32 matched control infants, who remained healthy up to 20 years of age, were analysed.

RESULTS

Parasutterella and Eubacterium were more abundant in healthy control infants, while Porphyromonas was differentially more abundant in infants with future type 1 diabetes diagnosis. Ruminococcus was a strong determinant in differentiating both control infants and those with future type 1 diabetes using random forest analysis and had differing trends of abundance when comparing control infants and those with future type 1 diabetes. Flavonifractor and UBA1819 were the strongest factors for differentiating control infants, showing higher abundance in control infants compared with those with future type 1 diabetes. Alternatively, Alistipes (more abundant in control infants) and Fusicatenibacter (mixed abundance patterns when comparing case and control infants) were the strongest factors for differentiating future type 1 diabetes. Predicted gene content regarding butyrate production and pyruvate fermentation was differentially observed to be higher in healthy control infants.

CONCLUSIONS/INTERPRETATION

This investigation suggests that microbial biomarkers for type 1 diabetes may be present as early as 1 year of age, as reflected in the taxonomic and functional differences of the microbial communities. The possibility of preventing disease onset by altering or promoting a 'healthy' gut microbiome is appealing.

DATA AVAILABILITY

The forward and reverse 16S raw sequencing data generated in this study are available through the NCBI Sequence Read Archive under BioProject PRJNA875929. Associated sample metadata used for statistical comparison are available in the source data file. R codes used for statistical comparisons and figure generation are available at: https://github.com/PMilletich/T1D_Pipeline .

Akkermansia muciniphila as a Next-Generation Probiotic in Modulating Human Metabolic Homeostasis and Disease Progression: A Role Mediated by Gut-Liver-Brain Axes?

Appreciation of the importance of Akkermansia muciniphila is growing, and it is becoming increasingly relevant to identify preventive and/or therapeutic solutions targeting gut-liver-brain axes for multiple diseases via Akkermansia muciniphila. In recent years, Akkermansia muciniphila and its components such as outer membrane proteins and extracellular vesicles have been known to ameliorate host metabolic health and intestinal homeostasis. However, the impacts of Akkermansia muciniphila on host health and disease are complex, as both potentially beneficial and adverse effects are mediated by Akkermansia muciniphila and its derivatives, and in some cases, these effects are dependent upon the host physiology microenvironment and the forms, genotypes, and strain sources of Akkermansia muciniphila. Therefore, this review aims to summarize the current knowledge of how Akkermansia muciniphila interacts with the host and influences host metabolic homeostasis and disease progression. Details of Akkermansia muciniphila will be discussed including its biological and genetic characteristics; biological functions including anti-obesity, anti-diabetes, anti-metabolic-syndrome, anti-inflammation, anti-aging, anti-neurodegenerative disease, and anti-cancer therapy functions; and strategies to elevate its abundance. Key events will be referred to in some specific disease states, and this knowledge should facilitate the identification of Akkermansia muciniphila-based probiotic therapy targeting multiple diseases via gut-liver-brain axes.

Associations of disordered eating with the intestinal microbiota and short-chain fatty acids among young adults with type 1 diabetes

BACKGROUND AND AIMS

Disordered eating (DE) in type 1 diabetes (T1D) includes insulin restriction for weight loss with serious complications. Gut microbiota-derived short chain fatty acids (SCFA) may benefit host metabolism but are reduced in T1D. We evaluated the hypothesis that DE and insulin restriction were associated with reduced SCFA-producing gut microbes, SCFA, and intestinal microbial diversity in adults with T1D.

METHODS AND RESULTS

We collected stool samples at four timepoints in a hypothesis-generating gut microbiome pilot study ancillary to a weight management pilot in young adults with T1D. 16S ribosomal RNA gene sequencing measured the normalized abundance of SCFA-producing intestinal microbes. Gas-chromatography mass-spectrometry measured SCFA (total, acetate, butyrate, and propionate). The Diabetes Eating Problem Survey-Revised (DEPS-R) assessed DE and insulin restriction. Covariate-adjusted and Bonferroni-corrected generalized estimating equations modeled the associations. COVID-19 interrupted data collection, so models were repeated restricted to pre-COVID-19 data. Data were available for 45 participants at 109 visits, which included 42 participants at 65 visits pre-COVID-19. Participants reported restricting insulin "At least sometimes" at 53.3% of visits. Pre-COVID-19, each 5-point DEPS-R increase was associated with a -0.34 (95% CI -0.56, -0.13, p = 0.07) lower normalized abundance of genus Anaerostipes; and the normalized abundance of Lachnospira genus was -0.94 (95% CI -1.5, -0.42), p = 0.02 lower when insulin restriction was reported "At least sometimes" compared to "Rarely or Never".

CONCLUSION

DE and insulin restriction were associated with a reduced abundance of SCFA-producing gut microbes pre-COVID-19. Additional studies are needed to confirm these associations to inform microbiota-based therapies in T1D.

A diet enriched in omega-3 PUFA and inulin prevents type 1 diabetes by restoring gut barrier integrity and immune homeostasis in NOD mice

Introduction

The integrity of the gut barrier (GB) is fundamental to regulate the crosstalk between the microbiota and the immune system and to prevent inflammation and autoimmunity at the intestinal level but also in organs distal from the gut such as the pancreatic islets. In support to this idea, we recently demonstrated that breakage of GB integrity leads to activation of islet-reactive T cells and triggers autoimmune Type 1 Diabetes (T1D). In T1D patients as in the NOD mice, the spontaneous model of autoimmune diabetes, there are alterations of the GB that specifically affect structure and composition of the mucus layer; however, it is yet to be determined whether a causal link between breakage of the GB integrity and occurrence of autoimmune T1D exists.

Methods

Here we restored GB integrity in the NOD mice through administration of an anti-inflammatory diet (AID- enriched in soluble fiber inulin and omega 3-PUFA) and tested the effect on T1D pathogenesis.

Results

We found that the AID prevented T1D in NOD mice by restoring GB integrity with increased mucus layer thickness and higher mRNA transcripts of structural (Muc2) and immunoregulatory mucins (Muc1 and Muc3) as well as of tight junction proteins (claudin1). Restoration of GB integrity was linked to reduction of intestinal inflammation (i.e., reduced expression of IL-1β, IL-23 and IL-17 transcripts) and expansion of regulatory T cells (FoxP3⁺ Treg cells and IL-10⁺ Tr1 cells) at the expenses of effector Th1/Th17 cells in the intestine, pancreatic lymph nodes (PLN) and intra-islet lymphocytes (IIL) of AID-fed NOD mice. Importantly, the restoration of GB integrity and immune homeostasis were associated with enhanced concentrations of anti-inflammatory metabolites of the ω3/ω6 polyunsaturated fatty acids (PUFA) and arachidonic pathways and modifications of the microbiome profile with increased relative abundance of mucus-modulating bacterial species such as Akkermansia muciniphila and Akkermansia glycaniphila.

Discussion

Our data provide evidence that the restoration of GB integrity and intestinal immune homeostasis through administration of a tolerogenic AID that changed the gut microbial and metabolic profiles prevents autoimmune T1D in preclinical models.

Diabetes mellitus is an independent risk factor for a greater frequency of early satiation and diarrhea at one and three years: Two prospective longitudinal population-based studies

BACKGROUND

Psychological and lifestyle factors have been associated with gastrointestinal (GI) symptoms in individuals with diabetes mellitus, but it remains unclear whether they explain the relationship over time. We aimed to determine in two independent population-based studies whether diabetes is an independent risk factor for GI symptoms at a 1- and 3-year follow-up, adjusting for these factors.

METHODS

In study 1, 1900 individuals completed a baseline and 1-year follow-up survey, while in study 2, 1322 individuals completed a baseline and 3-year follow-up survey. Both studies asked about self-reported diagnoses of diabetes and GI symptoms over the previous 3 months. Psychological, lifestyle factors (body mass index [BMI], smoking) and age and sex were assessed.

KEY RESULTS

The baseline prevalence of diabetes was 7.8% in Survey 1 and 8.9% in Survey 2. In a multivariate model that included age, sex, BMI, anxiety, depression and smoking status at follow-up, reporting diabetes at baseline was an independent predictor of at least weekly early satiation (OR 1.58, 95% CI 1.05, 2.39, p = 0.03; OR = 1.67, 95% CI 1.14, 2.45, p = 0.009), fecal urgency (OR 1.44,95% CI 1.06, 1.95, p = 0.02; OR = 2.17, 95% CI 1.47, 3.22, p = 0.0001), > 3 bowel motions a day (OR 1.50, 95% CI 1.08, 2.07, p = 0.02; OR = 1.67, 95% CI 1.11, 2.51, p = 0.01), and loose stools (OR 1.40, 95% CI 1.04, 1.90, p = 0.03; OR = 1.68, 95% CI 1.13, 2.51, p = 0.01) at the 1- and 3-year follow-ups, respectively.

CONCLUSIONS & INFERENCES

Diabetes is an independent risk factor for a greater frequency of early satiation and diarrhea, adjusting for lifestyle and psychological factors.

Maternal provisions in type 1 diabetes: Evidence for both protective & pathogenic potential

Maternal influences on the immune health and development of an infant begin in utero and continue well into the postnatal period, shaping and educating the child's maturing immune system. Two maternal provisions include early microbial colonizers to initiate microbiota establishment and the transfer of antibodies from mother to baby. Maternal antibodies are a result of a lifetime of antigenic experience, reflecting the infection history, health and environmental exposure of the mother. These same factors are strong influencers of the microbiota, inexorably linking the two. Together, these provisions help to educate the developing neonatal immune system and shape lymphocyte repertoires, establishing a role for external environmental influences even before birth. In the context of autoimmunity, the transfer of maternal autoantibodies has the potential to be harmful for the child, sometimes targeting tissues and cells with devastating consequences. Curiously, this does not seem to apply to maternal autoantibody transfer in type 1 diabetes (T1D). Moreover, despite the rising prevalence of the disease, little research has been conducted on the effects of maternal dysbiosis or antibody transfer from an affected mother to her offspring and thus their relevance to disease development in the offspring remains unclear. This review seeks to provide a thorough evaluation of the role of maternal microorganisms and antibodies within the context of T1D, exploring both their pathogenic and protective potential. Although a definitive understanding of their significance in infant T1D development remains elusive at present, we endeavor to present what has been learned with the goal of spurring further interest in this important and intriguing question.

Pathophysiology of Type 1 Diabetes and Gut Microbiota Role

Type 1 diabetes (T1D) is a multifactorial autoimmune disease driven by T-cells against the insulin-producing islet β-cells, resulting in a marked loss of β-cell mass and function. Although a genetic predisposal increases susceptibility, the role of epigenetic and environmental factors seems to be much more significant. A dysbiotic gut microbial profile has been associated with T1D patients. Moreover, new evidence propose that perturbation in gut microbiota may influence the T1D onset and progression. One of the prominent features in clinically silent phase before the onset of T1D is the presence of a microbiota characterized by low numbers of commensals butyrate producers, thus negatively influencing the gut permeability. The loss of gut permeability leads to the translocation of microbes and microbial metabolites and could lead to the activation of immune cells. Moreover, microbiota-based therapies to slow down disease progression or reverse T1D have shown promising results. Starting from this evidence, the correction of dysbiosis in early life of genetically susceptible individuals could help in promoting immune tolerance and thus in reducing the autoantibodies production. This review summarizes the associations between gut microbiota and T1D for future therapeutic perspectives and other exciting areas of research.

Maternal energy-adjusted fatty acid intake during pregnancy and the development of cows' milk allergy in the offspring

Cows' milk allergy (CMA) is one of the earliest manifestations of allergic diseases. Early dietary factors, like maternal diet during pregnancy, may play a role in the development of allergic diseases in the offspring. We aimed to investigate the association between maternal intake of fatty acids during pregnancy and the risk of CMA in the offspring. Our study was conducted in a population-based cohort, the Finnish Type 1 Diabetes Prediction and Prevention study. We collected the maternal dietary data by a validated FFQ. We obtained the information on CMA in the study participants (n 448) from registers and from the parents. Dietary data and information on CMA were available for 4921 children. We used logistic regression in the analyses, and fatty acid intakes were energy adjusted. The maternal intake of SFA, MUFA, PUFA, n-3 PUFA, n-6 PUFA, trans fatty acids, ratio of n-3 PUFA to n-6 PUFA or ratio of linoleic acid to α-linolenic acid was not associated with the risk of CMA in the offspring when adjusted for perinatal factors, background factors, parental history of asthma or allergic rhinitis and infant animal contacts. The intake of α-linolenic acid was associated with a decreased risk (OR 0·72; 95 % CI 0·56, 0·93) of CMA in the offspring of mothers without a history of allergic rhinitis or asthma. In conclusion, the maternal intake of fatty acids during pregnancy is not associated with the risk of CMA in the offspring.

Lactiplantibacillus plantarum 299v supplementation modulates β-cell ER stress and antioxidative defense pathways and prevents type 1 diabetes in gluten-free BioBreeding rats

The increasing incidence of Type 1 diabetes has coincided with the emergence of the low-fiber, high-gluten Western diet and other environmental factors linked to dysbiosis. Since Lactiplantibacillus plantarum 299 v (Lp299v) supplementation improves gut barrier function and reduces systemic inflammation, we studied its effects in spontaneously diabetic DRlyp/lyp rats provided a normal cereal diet (ND) or a gluten-free hydrolyzed casein diet (HCD). All rats provided ND developed diabetes (62.5±7.7 days); combining ND with Lp299v did not improve survival. Diabetes was delayed by HCD (72.2±9.4 days, p = .01) and further delayed by HCD+Lp299v (84.9±14.3 days, p < .001). HCD+Lp299v pups exhibited increased plasma propionate and butyrate levels, which correlated with enriched fecal Bifidobacteriaceae and Clostridiales taxa. Islet transcriptomic and histologic analyses at 40-days of age revealed that rats fed HCD expressed an autophagy profile, while those provided HCD+Lp299v expressed ER-associated protein degradation (ERAD) and antioxidative defense pathways, including Nrf2. Exposing insulinoma cells to propionate and butyrate promoted the antioxidative defense response but did not recapitulate the HCD+Lp299v islet ERAD transcriptomic profile. Here, both diet and microbiota influenced diabetes susceptibility. Moreover, Lp299v supplement modulated antioxidative defense and ER stress responses in β-cells, potentially offering a new therapeutic direction to thwart diabetes progression and preserve insulin secretion.

Gut microbiota supports male reproduction via nutrition, immunity, and signaling

Gut microbiota (GM) is a major component of the gastrointestinal tract. Growing evidence suggests that it has various effects on many distal organs including the male reproductive system in mammals. GM and testis form the gut-testis axis involving the production of key molecules through microbial metabolism or de novo synthesis. These molecules have nutrition, immunity, and hormone-related functions and promote the male reproductive system via the circulatory system. GM helps maintain the integral structure of testes and regulates testicular immunity to protect the spermatogenic environment. Factors damaging GM negatively impact male reproductive function, however, the related mechanism is unknown. Also, the correlation between GM and testis remains to be yet investigated. This review discusses the complex influence of GM on the male reproductive system highlighting the impact on male fertility.

Crocin-I Protects Against High-Fat Diet-Induced Obesity via Modulation of Gut Microbiota and Intestinal Inflammation in Mice

Crocin-I can regulate physiological changes in the human body by altering inflammation and microbial composition. Gut microbiota are also involved in modulating the pathophysiology of obesity. However, crocin-I’s effect on obesity and the mechanism underlying its effects on gut microbiota and inflammation remain poorly understood. Here, high-fat diet (HFD) -induced obese mice were administrated crocin-I (20 mg/kg/day) for 10 weeks using an oral gavage (HFD-C20 group). HFD-C20, HFD, and Normal chow (NC) groups were compared. The fat content, colon tissue inflammatory cytokine levels, gut microbiota, and short-chain fatty acids (SCFAs) levels were measured. We show that crocin-I reduced body weight and liver weight and improved glucose resistance in HFD-induced mice, and reduced the lipid accumulation in the liver. Strikingly, crocin-I alleviated intestinal microbial disorders and decreased the F/B ratio and the abundance of Proteobacteria in HFD-induced obese mice. Crocin-I also rescued the decrease in the levels of SCFAs and repaired altered intestinal barrier functioning and intestinal inflammation in HFD-induced obese mice. These findings indicate that crocin-I may inhibit obesity by modulating the composition of gut microbiota and intestinal inflammation.

Maternal heme-enriched diet promotes a gut pro-oxidative status associated with microbiota alteration, gut leakiness and glucose intolerance in mice offspring

Maternal environment, including nutrition and microbiota, plays a critical role in determining offspring's risk of chronic diseases such as diabetes later in life. Heme iron requirement is amplified during pregnancy and lactation, while excessive dietary heme iron intake, compared to non-heme iron, has shown to trigger acute oxidative stress in the gut resulting from reactive aldehyde formation in conjunction with microbiota reshape. Given the immaturity of the antioxidant defense system in early life, we investigated the extent to which a maternal diet enriched with heme iron may have a lasting impact on gut homeostasis and glucose metabolism in 60-day-old C3H/HeN mice offspring.

As hypothesized, the form of iron added to the maternal diet differentially governed the offspring's microbiota establishment despite identical fecal iron status in the offspring. Importantly, despite female offspring was unaffected, oxidative stress markers were however higher in the gut of male offspring from heme enriched-fed mothers, and were accompanied by increases in fecal lipocalin-2, intestinal para-cellular permeability and TNF-α expression. In addition, male mice displayed blood glucose intolerance resulting from impaired insulin secretion following oral glucose challenge. Using an integrated approach including an aldehydomic analysis, this male-specific phenotype was further characterized and revealed close covariations between unidentified putative reactive aldehydes and bacterial communities belonging to Bacteroidales and Lachnospirales orders.

Our work highlights how the form of dietary iron in the maternal diet can dictate the oxidative status in gut offspring in a sex-dependent manner, and how a gut microbiota-driven oxidative challenge in early life can be associated with gut barrier defects and glucose metabolism disorders that may be predictive of diabetes development.

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Maternal heminic vs. non-heminic iron intake differentially and persistently imprints the offspring's fecal microbiota.

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Males from heme-fed dams exhibit increased gut lumen reactive aldehydes in absence of direct dietary exposure to heme iron.

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Some of the increased reactive aldehydes closely covariated with Orders belonging to Bacteroidales and Lachnospirales.

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Maternal exposure to dietary heme iron impairs gut barrier and glucose tolerance in male offspring.

Ectopic Colonization and Immune Landscapes of Periodontitis Microbiota in Germ-Free Mice With Streptozotocin-Induced Type 1 Diabetes Mellitus

A two-way relationship between diabetes and periodontitis has been discussed recently. Periodontitis microbiota might affect the immune homeostasis of diabetes, but the molecular mechanism of their interactions is still not clear. The aims of this study were to clarify the possible immune regulatory effects of periodontitis microbiota on diabetes and the correlation between immunomodulation and ectopic colonization. A model of germ-free mice with streptozotocin-induced type 1 diabetes mellitus (T1D), which was orally inoculated with mixed saliva samples for 2 weeks, was used in this study. Those mice were randomly divided into two groups, namely, SP (where the T1D mice were orally inoculated with mixed saliva samples from periodontitis patients) and SH (where the T1D mice were orally inoculated with mixed saliva samples from healthy subjects). Ectopic colonization of saliva microbiota was assessed using culture-dependent method and Sanger sequencing, and the composition of gut microbiota was analyzed using 16S rRNA gene sequencing. Changes in 15 types of immune cells and six cytokines either from the small intestine or spleen were detected by multicolor flow cytometry. The correlation between gut microbiota and immune cells was evaluated by redundancy analysis. Although periodontitis microbiota minorly colonized the lungs, spleens, and blood system, they predominantly colonized the gut, which was mainly invaded by Klebsiella. SH and SP differed in beta diversity of the gut bacterial community. Compared to SH, microbial alteration in small intestine occurred with an increase of Lacticaseibacillus, Bacillus, Agathobacter, Bacteroides, and a decrease of Raoultella in SP. More types of immune cells were disordered in the spleen than in the small intestine by periodontitis microbiota, mainly with a dramatical increase in the proportion of macrophages, plasmacytoid dendritic cells (pDCs), monocytes, group 3 innate lymphoid cells, CD4-CD8- T cells and Th17 cells, as well as a decline of αβT cells in SP. Cytokines of IFNγ, IL17, and IL22 produced by CD4 + T cells as well as IL22 produced by ILCs of small intestine rose in numbers, and the intestinal and splenic pDCs were positively regulated by gut bacterial community in SP. In conclusion, periodontitis microbiota invasion leads to ectopic colonization of the extra-oral sites and immune cells infiltration, which might cause local or systemic inflammation. Those cells are considered to act as a “bridge” between T1D and periodontitis.

Gut microbiome profiles and associated metabolic pathways in patients of adult-onset immunodeficiency with anti-interferon-gamma autoantibodies

Autoantibodies against interferon-gamma (AutoAbs-IFN-γ) can cause the immunodeficiency condition following various opportunistic infections. Gut microbiota can affect the human immune system in many ways. Many studies have shown that gut dysbiosis was associated with some immune diseases, such as autoimmune diseases and human immunodeficiency virus (HIV) infection, while its relationship at anti-IFN-γ AAbs remains unknown. We aimed to identify the anti-IFN-γ AAbs specific microbiome and the possible association with immunodeficiency. We profiled fecal microbiome for two cohorts of forty subjects, including seven patients with anti-IFN-γ AAbs and 33 individuals with competent immune. The study shows that patients with anti-IFN-γ AAbs have characterized the gut microbiome and have lower alpha diversity indexes than healthy controls (HC). There are significant differences in the microbiome structure at both the family and genera level between the two cohorts. The anti-IFN-γ AAbs cohort featured some microbiome such as Clostridium, including the possible opportunistic pathogen and fewer genera including Bacteroides, Ruminococcus, and Faecalibacterium, some of them with possible immune-related genera. The PICRUSt2 pathway demonstrated the decreased abundance of some immune-related pathways and one potential pathway related to the immune alternations in the anti- IFN-γ AAbs cohort. This was the first study to examine the gut microbiome characteristics in patients with anti-IFN-γ AAbs. It could be involved in the pathogenesis of anti-IFN-γ AAbs and contribute to the derived immune condition in this disease. This could lead to new strategies for treating and preventing patients suffering from this disease.

Intestinal Bacterial Translocation Contributes to Diabetic Kidney Disease

Background In recent years, many studies have focused on the intestinal environment to elucidate pathogenesis of various diseases, including kidney diseases. Impairment of the intestinal barrier function, the "leaky gut," reportedly contributes to pathological processes in some disorders. Mitochondrial antiviral signaling protein (MAVS), a component of innate immunity, maintains intestinal integrity. The effects of disrupted intestinal homeostasis associated with MAVS signaling in diabetic kidney disease remains unclear. Methods To evaluate the contribution of intestinal barrier impairment to kidney injury under diabetic conditions, we induced diabetic kidney disease in wild-type and MAVS knockout mice through unilateral nephrectomy and streptozotocin treatment. We then assessed effects on the kidney, intestinal injuries, and bacterial translocation. Results MAVS knockout diabetic mice showed more severe glomerular and tubular injuries compared with wild-type diabetic mice. Owing to impaired intestinal integrity, the presence of intestine-derived Klebsiella oxytoca and elevated IL-17 were detected in the circulation and kidneys of diabetic mice, especially in diabetic MAVS knockout mice. Stimulation of tubular epithelial cells with K. oxytoca activated MAVS pathways and the phosphorylation of Stat3 and ERK1/2, leading to the production of kidney injury molecule-1 (KIM-1). Nevertheless, MAVS inhibition induced inflammation in the intestinal epithelial cells and KIM-1 production in tubular epithelial cells under K. oxytoca supernatant or IL-17 stimulation. Treatment with neutralizing anti-IL-17 antibody treatment had renoprotective effects. In contrast, lipopolysaccharide administration accelerated kidney injury in the murine diabetic kidney disease model. Conclusions Impaired MAVS signaling both in the kidney and intestine contributes to the disrupted homeostasis, leading to diabetic kidney disease progression. Controlling intestinal homeostasis may offer a novel therapeutic approach for this condition.

Probiotic normalization of systemic inflammation in siblings of type 1 diabetes patients: an open-label pilot study

The incidence of type 1 diabetes (T1D) has increased, coinciding with lifestyle changes that have likely altered the gut microbiota. Dysbiosis, gut barrier dysfunction, and elevated systemic inflammation consistent with microbial antigen exposure, have been associated with T1D susceptibility and progression. A 6-week, single-arm, open-label pilot trial was conducted to investigate whether daily multi-strain probiotic supplementation could reduce this familial inflammation in 25 unaffected siblings of T1D patients. Probiotic supplementation was well-tolerated as reflected by high participant adherence and no adverse events. Community alpha and beta diversity were not altered between the pre- and post-supplement stool samplings. However, LEfSe analyses identified post-supplement enrichment of the family Lachnospiraceae, producers of the anti-inflammatory short chain fatty acid butyrate. Systemic inflammation was measured by plasma-induced transcription and quantified with a gene ontology-based composite inflammatory index (I.I._com). Post-supplement I.I._com was significantly reduced and pathway analysis predicted inhibition of numerous inflammatory mediators and activation of IL10RA. Subjects with the greatest post-supplement reduction in I.I._com exhibited significantly lower CD4+ CD45RO+ (memory):CD4+ CD45RA+ (naïve) T-cell ratios after supplementation. Post-supplement IL-12p40, IL-13, IL-15, IL-18, CCL2, and CCL24 plasma levels were significantly reduced, while post-supplement butyrate levels trended 1.4-fold higher. Probiotic supplementation may modify T1D susceptibility and progression and warrants further study.

The crosstalk between gut microbiota, intestinal immunological niche and visceral adipose tissue as a new model for the pathogenesis of metabolic and inflammatory diseases: the paradigm of type 2 diabetes mellitus

Gut microbiota (GM) comprises more than one thousand microorganisms between bacterial species, viruses, fungi, and protozoa, and represents the main actor of a wide net of molecular interactions, involving, among others, the endocrine system, immune responses, and metabolism. GM influences many endocrine functions such as adrenal steroidogenesis, thyroid function, sexual hormones, IGF-1 pathway and peptides produced in gastrointestinal system. It is fundamental in glycaemic control and obesity, while also exerting an important function in modulating the immune system and associated inflammatory disease. The result of this crosstalk in gut mucosa is the formation of the intestinal immunological niche. Visceral adipose tissue (VAT) produces about 600 different peptides, it is involved in lipid and glucose metabolism and in some immune reactions through several adipokines. GM and VAT interact in a bidirectional fashion: while gut dysbiosis can modify VAT adipokines and hormone secretion, VAT hyperplasia modifies GM composition. Acquired or genetic factors leading to gut dysbiosis or increasing VAT (i.e., Western diet) induce a proinflammatory condition, which plays a pivotal role in the development of dysmetabolic and immunologic conditions, such as diabetes mellitus. Diabetes is clearly associated with specific patterns of GM alterations, with an abundance or reduction of GM species involved in controlling mucosal barrier status, glycaemic levels and exerting a pro- or anti-inflammatory activity. All these factors could explain the higher incidence of several inflammatory conditions in Western countries; furthermore, besides the specific alterations observed in diabetes, this paradigm could represent a common pathway acting in many metabolic conditions and could pave the way to a new, interesting therapeutic approach.

Multiomics signatures of type 1 diabetes with and without albuminuria

AIMS/HYPOTHESIS

To identify novel pathophysiological signatures of longstanding type 1 diabetes (T1D) with and without albuminuria we investigated the gut microbiome and blood metabolome in individuals with T1D and healthy controls (HC). We also mapped the functional underpinnings of the microbiome in relation to its metabolic role.

METHODS

One hundred and sixty-one individuals with T1D and 50 HC were recruited at the Steno Diabetes Center Copenhagen, Denmark. T1D cases were stratified based on levels of albuminuria into normoalbuminuria, moderate and severely increased albuminuria. Shotgun sequencing of bacterial and viral microbiome in stool samples and circulating metabolites and lipids profiling using mass spectroscopy in plasma of all participants were performed. Functional mapping of microbiome into Gut Metabolic Modules (GMMs) was done using EggNog and KEGG databases. Multiomics integration was performed using MOFA tool.

RESULTS

Measures of the gut bacterial beta diversity differed significantly between T1D and HC, either with moderately or severely increased albuminuria. Taxonomic analyses of the bacterial microbiota identified 51 species that differed in absolute abundance between T1D and HC (17 higher, 34 lower). Stratified on levels of albuminuria, 10 species were differentially abundant for the moderately increased albuminuria group, 63 for the severely increased albuminuria group while 25 were common and differentially abundant both for moderately and severely increased albuminuria groups, when compared to HC. Functional characterization of the bacteriome identified 23 differentially enriched GMMs between T1D and HC, mostly involved in sugar and amino acid metabolism. No differences in relation to albuminuria stratification was observed. Twenty-five phages were differentially abundant between T1D and HC groups. Six of these varied with albuminuria status. Plasma metabolomics indicated differences in the steroidogenesis and sugar metabolism and circulating sphingolipids in T1D individuals. We identified association between sphingolipid levels and Bacteroides sp. abundances. MOFA revealed reduced interactions between gut microbiome and plasma metabolome profiles albeit polar metabolite, lipids and bacteriome compositions contributed to the variance in albuminuria levels among T1D individuals.

CONCLUSIONS

Individuals with T1D and progressive kidney disease stratified on levels of albuminuria show distinct signatures in their gut microbiome and blood metabolome.

Latent Autoimmune Diabetes in Adults (LADA): From Immunopathogenesis to Immunotherapy

Latent autoimmune diabetes in adults (LADA) is a type of diabetes characterized by slow autoimmune damage of pancreatic β cells without insulin treatment in the early clinical stage. There are differences between LADA and classical type 1 diabetes (T1D) and type 2 diabetes (T2D) in genetic background, autoimmune response, rate of islet function decline, clinical metabolic characteristics, and so on. The disease progression and drug response of patients with LADA are closely related to the level of islet autoimmunity, thus exploring the pathogenesis of LADA is of great significance for its prevention and treatment. Previous studies reported that adaptive immunity and innate immunity play a critical role in the etiology of LADA. Recent studies have shown that the intestinal microbiota which impacts host immunity hugely, participates in the pathogenesis of LADA. In addition, the progression of autoimmune pancreatic β cell destruction in LADA is slower than in classical T1D, providing a wider window of opportunities for intervention. Therefore, therapies including antidiabetic drugs with immune-regulation effects and immunomodulators could contribute to promising interventions for LADA. We also shed light on potential interventions targeting the gut microbiota and gut-associated immunity, which may be envisaged to halt or delay the process of autoimmunity in LADA.

Early glucose metabolism in children at risk for type 1 diabetes based on islet autoantibodies compared to low-risk control groups

BACKGROUND

Anatomic variation or early differences in glucose metabolism have been linked to the development of type 1 diabetes. We aimed to describe early glucose metabolism based on HbA1c, oral glucose tolerance test (OGTT), and random plasma glucose years before the presentation of type 1 diabetes in five risk groups based on autoantibody combinations. For the first time, we were able to include for comparison children with very low risk of progression to type 1 diabetes.

METHODS

The Finnish Diabetes Prediction and Prevention birth cohort study screened newborn infants for HLA susceptibility to type 1 diabetes since 1994. Those carrying a risk genotype were prospectively followed up with islet autoantibody testing. Glucose parameters were obtained starting from the time of seroconversion. By 31 August 2014, 1162 children had developed at least one islet autoantibody and were included in the current study. Type 1 diabetes was diagnosed in 335 children (progressors). In the non-progressor groups, 207 developed multiple (≥2) biochemical islet autoantibodies, 229 a single biochemical autoantibody, 370 ICA only, and 64 transient autoantibodies. Children were divided into five risk groups. Glucose metabolism was evaluated.

RESULTS

We observed lower HbA1c values in early follow-up 4.5 to 6.0 years before diagnosis in the progressors when compared to the same time in children with a single biochemical autoantibody or low-risk (ICA only and transient) participants, who did not progress to clinical type 1 diabetes. However, no such differences were observed in OGTTs or random plasma glucose. The variation was minimal in glucose values in the low-risk groups.

CONCLUSION

We report the possibility of early alteration in glucose metabolism in future progressors. This could suggest early defects in multiple glucose-regulating hormones.

The Protective Effect of Basic Fibroblast Growth Factor in Intestine of db/db Mice: A 1H NMR-Based Metabolomics Investigation

Diabetic enteropathy (DE) is a diabetic complication and affects the quality of life for which there are limited therapies. In this study, db/db mice were administered with a basic fibroblast growth factor (bFGF) to explore its therapeutic effect on the intestine. ¹H NMR-based metabolomics was applied to investigate the metabolic pattern. H&E and PAS staining were used to observe the morphological phenotypes related to intestinal barrier function. Tight junction proteins such as Zo-1 and Occluding were successively tested by immunofluorescence and real-time PCR. We found that bFGF treatment significantly restored intestinal barrier function. In addition, the administration of bFGF decreased the levels of inflammatory cytokines in the cecum. Metabolomic results show that bFGF remodeled metabolic phenotypes of the colon, cecum, and small intestine in db/db mice, including energy metabolism, short chain fatty acid metabolism, amino acid metabolism, and choline metabolism. Hence, this study indicates that the bFGF has a protective effect in diabetic bowel disease by restoring intestinal barrier function, reducing inflammatory infiltration, and remodeling metabolic function.

The Modulation of Gut Microbiota Composition in the Pathophysiology of Gestational Diabetes Mellitus: A Systematic Review

Simple Summary

Recent studies have placed a great deal of emphasis on the importance of the microbiome, especially the link between the alteration of gut microbiota and multiple associated diseases. Gut microbiota changes in pregnancy have a significant impact on metabolic function and may contribute to gestational diabetes mellitus (GDM). Although GDM carries long-term health risks that affect women, there are also significant short- and severe long-term consequences for the offspring. Regardless, there is a notable lack of research focusing on the impact of prominent microorganisms involved in the development of GDM. A comprehensive review was conducted to gather relevant data on the types of microorganisms that have been associated with GDM. The review found that certain microorganisms impact the onset and progression of GDM during pregnancy. Several bacterial strains associated with GDM are influenced by a diet high in fat and low in fiber. Therefore, integrating the idea of a microbiome-based individualized dietary intervention into gestational diabetes management may be incredibly beneficial.

Abstract

General gut microbial dysbiosis in diabetes mellitus, including gestational diabetes mellitus (GDM), has been reported in a large body of literature. However, evidence investigating the association between specific taxonomic classes and GDM is lacking. Thus, we performed a systematic review of peer-reviewed observational studies and trials conducted among women with GDM within the last ten years using standard methodology. The National Institutes of Health (NIH) quality assessment tools were used to assess the quality of the included studies. Fourteen studies investigating microbial interactions with GDM were found to be relevant and included in this review. The synthesis of literature findings demonstrates that Bacteroidetes, Proteobacteria, Firmicutes, and Actinobacteria phyla, such as Desulfovibrio, Ruminococcaceae, P. distasonis, Enterobacteriaceae, Collinsella, and Prevotella, were positively associated with GDM. In contrast, Bifidobacterium and Faecalibacterium, which produce butyrate, are negatively associated with GDM. These bacteria were associated with inflammation, adiposity, and glucose intolerance in women with GDM. Lack of good diet management demonstrated the alteration of gut microbiota and its impact on GDM glucose homeostasis. The majority of the studies were of good quality. Therefore, there is great potential to incorporate personalized medicine targeting microbiome modulation through dietary intervention in the management of GDM.

Early-life fingolimod treatment improves intestinal homeostasis and pancreatic immune tolerance in non-obese diabetic mice

Fingolimod has beneficial effects on multiple diseases, including type 1 diabetes (T1D) and numerous preclinical models of colitis. Intestinal dysbiosis and intestinal immune dysfunction contribute to disease pathogenesis of T1D. Thus, the beneficial effect of fingolimod on T1D may occur via the maintenance of intestinal homeostasis to some extent. Herein, we investigated the role of fingolimod in intestinal dysfunction in non-obese diabetic (NOD) mice and possible mechanisms. NOD mice were treated with fingolimod (1 mg · kg-1 per day, i.g.) from weaning (3-week-old) to 31 weeks of age. We found that fingolimod administration significantly enhanced the gut barrier (evidenced by enhanced expression of tight junction proteins and reduced intestinal permeability), attenuated intestinal microbial dysbiosis (evidenced by the reduction of enteric pathogenic Proteobacteria clusters), as well as intestinal immune dysfunction (evidenced by inhibition of CD4+ cells activation, reduction of T helper type 1 cells and macrophages, and the expansion of regulatory T cells). We further revealed that fingolimod administration suppressed the activation of CD4+ cells and the differentiation of T helper type 1 cells, promoted the expansion of regulatory T cells in the pancreas, which might contribute to the maintenance of pancreatic immune tolerance and the reduction of T1D incidence. The protection might be due to fingolimod inhibiting the toll-like receptor 2/4/nuclear factor-κB/NOD-like receptor protein 3 inflammasome pathway in the colon. Collectively, early-life fingolimod treatment attenuates intestinal microbial dysbiosis and intestinal immune dysfunction in the T1D setting, which might contribute to its anti-diabetic effect.

Gut microbiota influence in type 2 diabetes mellitus (T2DM)

A strong and expanding evidence base supports the influence of gut microbiota in human metabolism. Altered glucose homeostasis is associated with altered gut microbiota, and is clearly associated with the development of type 2 diabetes mellitus (T2DM) and associated complications. Understanding the causal association between gut microbiota and metabolic risk has the potential role of identifying susceptible individuals to allow early targeted intervention.

Insulin immunotherapy for pretype 1 diabetes

PURPOSE OF REVIEW

Loss of tolerance to insulin likely contributes to the immunopathogenesis of type 1 diabetes (T1D). Several large clinical trials and smaller mechanistic studies have failed to demonstrate the efficacy of insulin antigen therapy. The growing awareness of the heterogeneity of T1D likely affects the response to various immune therapies including insulin. Identification of biomarkers of clinical response will provide further insight into mechanisms leading to the disease and classify responders in the quest for personalized therapy.

RECENT FINDINGS

Several biomarkers have identified subpopulations in posthoc analyses that showed benefit from oral insulin even though the placebo-controlled study was as a whole unsuccessful. High insulin autoantibody titer, low first phase insulin response, and high Diabetes Prevention Trial-Type 1 Risk Score identify at-risk relatives more likely to benefit from oral insulin. Future incorporation of human leukocyte antigen and the variable number of tandem repeats polymorphism located in the insulin gene promoter (INS VNTR) is of interest for both primary and secondary prevention studies.

SUMMARY

Although primary and secondary prevention trials using oral insulin are ongoing, those completed have been largely unsuccessful. However, we believe that oral insulin should be considered in future trials as part of combination therapies as prerandomization biomarker testing is refined.

Casomorphins and Gliadorphins Have Diverse Systemic Effects Spanning Gut, Brain and Internal Organs

Food-derived opioid peptides include digestive products derived from cereal and dairy diets. If these opioid peptides breach the intestinal barrier, typically linked to permeability and constrained biosynthesis of dipeptidyl peptidase-4 (DPP4), they can attach to opioid receptors. The widespread presence of opioid receptors spanning gut, brain, and internal organs is fundamental to the diverse and systemic effects of food-derived opioids, with effects being evidential across many health conditions. However, manifestation delays following low-intensity long-term exposure create major challenges for clinical trials. Accordingly, it has been easiest to demonstrate causal relationships in digestion-based research where some impacts occur rapidly. Within this environment, the role of the microbiome is evidential but challenging to further elucidate, with microbiome effects ranging across gut-condition indicators and modulators, and potentially as systemic causal factors. Elucidation requires a systemic framework that acknowledges that public-health effects of food-derived opioids are complex with varying genetic susceptibility and confounding factors, together with system-wide interactions and feedbacks. The specific role of the microbiome within this puzzle remains a medical frontier. The easiest albeit challenging nutritional strategy to modify risk is reduced intake of foods containing embedded opioids. In future, constituent modification within specific foods to reduce embedded opioids may become feasible.

Role of Postbiotics in Diabetes Mellitus: Current Knowledge and Future Perspectives

In the last decade, the gastrointestinal microbiota has been recognised as being essential for health. Indeed, several publications have documented the suitability of probiotics, prebiotics, and symbiotics in the management of different diseases such as diabetes mellitus (DM). Advances in laboratory techniques have allowed the identification and characterisation of new biologically active molecules, referred to as “postbiotics”. Postbiotics are defined as functional bioactive compounds obtained from food-grade microorganisms that confer health benefits when administered in adequate amounts. They include cell structures, secreted molecules or metabolic by-products, and inanimate microorganisms. This heterogeneous group of molecules presents a broad range of mechanisms and may exhibit some advantages over traditional “biotics” such as probiotics and prebiotics. Owing to the growing incidence of DM worldwide and the implications of the microbiota in the disease progression, postbiotics appear to be good candidates as novel therapeutic targets. In the present review, we summarise the current knowledge about postbiotic compounds and their potential application in diabetes management. Additionally, we envision future perspectives on this topic. In summary, the results indicate that postbiotics hold promise as a potential novel therapeutic strategy for DM.

Maternal antioxidant intake during pregnancy and the development of cows' milk allergy in the offspring

Cows' milk allergy (CMA) is the most common food allergy in young children, and it is often the first manifestation of atopic diseases. Accordingly, very early environmental factors, such as maternal diet during pregnancy, may play a role in the development of CMA, but the evidence is limited. The aim of this study was to investigate the association between maternal intake of antioxidant nutrients during pregnancy and the subsequent development of CMA in the offspring in a prospective, population-based birth cohort within the Finnish Type 1 Diabetes Prediction and Prevention Study. Maternal dietary information during pregnancy was collected with a detailed, validated FFQ. The maternal dietary information and the information on putative confounding factors were available for 4403 children. Information on diagnosed CMA (n 448) was obtained from a medical registry and queried from the parents up to child's age of 3 years. The Finnish food composition database was used to calculate the average daily intake of nutrients. Logistic regression was applied for statistical analyses, and the nutrient intakes were adjusted for energy intake. OR are presented per 1 sd increment of the particular nutrient intake. Maternal total and dietary intake of β-carotene was associated with an increased risk of CMA in the offspring when adjusted for the putative confounding factors (total OR 1·10, 95 % CI 1·02, 1·20; dietary OR 1·10; 95 % CI 1·01, 1·19). Using dietary supplements containing antioxidants in addition to a balanced diet may not confer any additional benefits.

Ochratoxin A: its impact on poultry gut health and microbiota, an overview

Ochratoxin A (OTA) is a widespread mycotoxin, that has strong thermal stability, and is difficult to remove from feed. OTA is nephrotoxic, hepatotoxic, teratogenic, immunotoxic, and enterotoxic to several species of animals. The gut is the first defense barrier against various types of mycotoxins present in feed that enter the body, and it is closely connected to other tissues through enterohepatic circulation. Compared with mammals, poultry is more sensitive to OTA and has a lower absorption rate. Therefore, the gut is an important target tissue for OTA in poultry. This review comprehensively discusses the role of OTA in gut health and the gut microbiota of poultry, focusing on the effect of OTA on digestive and absorptive processes, intestinal barrier integrity, intestinal histomorphology, gut immunity, and gut microbiota. According to the studies described to date, OTA can affect gut dysbiosis, including increasing gut permeability, immunity, and bacterial translocation, and can eventually lead to gut and other organ injury. Although there are many studies investigating the effects of OTA on the gut health of poultry, further studies are needed to better characterize the underlying mechanisms of action and develop preventative or therapeutic interventions for mycotoxicosis in poultry.

Inulin Fermentable Fiber Ameliorates Type I Diabetes via IL22 and Short-Chain Fatty Acids in Experimental Models

BACKGROUND & AIMS

Nourishment of gut microbiota via consumption of fermentable fiber promotes gut health and guards against metabolic syndrome. In contrast, how dietary fiber impacts type 1 diabetes is less clear.

METHODS

To examine impact of dietary fibers on development of type 1 diabetes in the streptozotocin (STZ)-induced and spontaneous non-obese diabetes (NOD) models, mice were fed grain-based chow (GBC) or compositionally defined diets enriched with a fermentable fiber (inulin) or an insoluble fiber (cellulose). Spontaneous (NOD mice) or STZ-induced (wild-type mice) diabetes was monitored.

RESULTS

Relative to GBC, low-fiber diets exacerbated STZ-induced diabetes, whereas diets enriched with inulin, but not cellulose, strongly protected against or treated it. Inulin's restoration of glycemic control prevented loss of adipose depots, while reducing food and water consumption. Inulin normalized pancreatic function and markedly enhanced insulin sensitivity. Such amelioration of diabetes was associated with alterations in gut microbiota composition and was eliminated by antibiotic administration. Pharmacologic blockade of fermentation reduced inulin's beneficial impact on glycemic control, indicating a role for short-chain fatty acids (SCFA). Furthermore, inulin's microbiota-dependent anti-diabetic effect associated with SCFA-independent restoration of interleukin 22, which was necessary and sufficient to ameliorate STZ-induced diabetes. Inulin-enriched diets significantly delayed diabetes in NOD mice.

CONCLUSIONS

Fermentable fiber confers microbiota-dependent increases in SCFA and interleukin 22 that, together, may have potential to prevent and/or treat type 1 diabetes.

Analysis of inflammasomes and CYP27B1 genes in cuprizone demyelinated C57BL/6 mice and evaluation of Th1 and Th2 patterns after oral administration of Lactobacillus casei strain T2 (IBRC-M10783)

Multiple sclerosis is characterized by the destruction of myelin in the CNS. Various factors including genetics, epigenetics, and environmental factors are involved in the development of the disease. There is evidence that changes in the gut microbiome profile are associated with immune-related diseases such as MS. Probiotics can alter the composition of the gut microbiota on the mucosal surfaces by differentiating naive T cells into Th1, Th2, Th17, and Treg cells. Female C57BL/6 mice were divided into 6 groups (n = 7): Normal group, cuprizone group (gavage of cuprizone for 4 weeks), Probiotic group (gavage of probiotic for 4 weeks), Treatment1 group (Probiotic for 4 weeks and then cuprizone for 4 weeks), treatment2 group (cuprizone for 4 weeks and then probiotic for 4 weeks) and treatment3 group (cuprizone for 4 weeks and then probiotic for 4 weeks with vitamin D3). Then the expression of NLRP-1, NLRP-3, AIM2, and CYP27B1 genes were evaluated using Real-Time PCR, and serum levels of IFN-γ and IL-4 were also measured by ELISA.The results showed a significant decrease in the expression of inflammasome and CYP27B1 genes in the probiotic-treated groups compared to the cuprizone group. Also, the comparison between probiotic-treated groups and cuprizone group showed a significant decrease in the amount of IFN-γ and IL-4. Due to reduced expression of the inflammasome genes as well as the decrease in IFN-γ levels as an inflammatory cytokine, it appears that L. casei may be effective in the healing process of demyelinated mice.