Akkermansia muciniphila is Negatively Correlated with Hemoglobin A1c in Refractory Diabetes

Detecting and quantifying Veillonella by real-time quantitative PCR and droplet digital PCR

Veillonella spp. are Gram-negative opportunistic pathogens present in the respiratory, digestive, and reproductive tracts of mammals. An abnormal increase in Veillonella relative abundance in the body is closely associated with periodontitis, inflammatory bowel disease, urinary tract infections, and many other diseases. We designed a pair of primers and a probe based on the 16S rRNA gene sequences of Veillonella and conducted real-time quantitative PCR (qPCR) and droplet digital PCR (ddPCR) to quantify the abundance of Veillonella in fecal samples. These two methods were tested for specificity and sensitivity using simulated clinical samples. The sensitivity of qPCR was 100 copies/μL, allowing for the accurate detection of a wide range of Veillonella concentrations from 103 to 108 CFU/mL. The sensitivity of ddPCR was 11.3 copies/μL, only allowing for the accurate detection of Veillonella concentrations from 101 to 104 CFU/mL because of the limited number of droplets generated by ddPCR. ddPCR is therefore more suitable for the detection of low-abundance Veillonella samples. To characterize the validity of the assay system, clinical samples from children with inflammatory bowel disease were collected and analyzed, and the results were verified using isolation methods. We conclude that molecular assays targeting the 16S rRNA gene provides an important tool for the rapid diagnosis of chronic and infectious diseases caused by Veillonella and also supports the isolation and identification of Veillonella for research purposes. KEY POINTS: • With suitable primer sets, the qPCR has a wider detection range than ddPCR. • ddPCR is suitable for the detection of low-abundance samples. • Methods successfully guided the isolation of Veillonella in clinical sample.

Insights into the Mechanisms of Action of Akkermansia muciniphila in the Treatment of Non-Communicable Diseases

This comprehensive review delineates the extensive roles of Akkermansia muciniphila in various health domains, spanning from metabolic and inflammatory diseases to neurodegenerative disorders. A. muciniphila, known for its ability to reside in the mucous layer of the intestine, plays a pivotal role in maintaining gut integrity and interacting with host metabolic processes. Its influence extends to modulating immune responses and potentially easing symptoms across several non-communicable diseases, including obesity, diabetes, inflammatory bowel disease, and cancer. Recent studies highlight its capacity to interact with the gut-brain axis, suggesting a possible impact on neuropsychiatric conditions. Despite the promising therapeutic potential of A. muciniphila highlighted in animal and preliminary human studies, challenges remain in its practical application due to stability and cultivation issues. However, the development of pasteurized forms and synthetic mediums offers new avenues for its use in clinical settings, as recognized by regulatory bodies like the European Food Safety Authority. This narrative review serves as a crucial resource for understanding the broad implications of A. muciniphila across different health conditions and its potential integration into therapeutic strategies.

Intestinal Epithelial Axin1 Deficiency Protects Against Colitis via Altered Gut Microbiota

Intestinal homeostasis is maintained by specialized host cells and the gut microbiota. Wnt/β-catenin signaling is essential for gastrointestinal development and homeostasis, and its dysregulation has been implicated in inflammation and colorectal cancer. Axin1 negatively regulates activated Wnt/β-catenin signaling, but little is known regarding its role in regulating host-microbial interactions in health and disease. Here, we aim to demonstrate that intestinal Axin1 determines gut homeostasis and host response to inflammation. Axin1 expression was analyzed in human inflammatory bowel disease datasets. To explore the effects and mechanism of intestinal Axin1 in regulating intestinal homeostasis and colitis, we generated new mouse models with Axin1 conditional knockout in intestinal epithelial cell (IEC; Axin1 ΔIEC) and Paneth cell (PC; Axin1 ΔPC) to compare with control (Axin1 LoxP; LoxP: locus of X-over, P1) mice. We found increased Axin1 expression in the colonic epithelium of human inflammatory bowel disease (IBD). Axin1 ΔIEC mice exhibited altered goblet cell spatial distribution, PC morphology, reduced lysozyme expression, and enriched Akkermansia muciniphila (A. muciniphila). The absence of intestinal epithelial and PC Axin1 decreased susceptibility to dextran sulfate sodium (DSS)-induced colitis in vivo. Axin1 ΔIEC and Axin1 ΔPC mice became more susceptible to DSS-colitis after cohousing with control mice. Treatment with A. muciniphila reduced DSS-colitis severity. Antibiotic treatment did not change the IEC proliferation in the Axin1 Loxp mice. However, the intestinal proliferative cells in Axin1 ΔIEC mice with antibiotic treatment were reduced compared with those in Axin1 ΔIEC mice without treatment. These data suggest non-colitogenic effects driven by the gut microbiome. In conclusion, we found that the loss of intestinal Axin1 protects against colitis, likely driven by epithelial Axin1 and Axin1-associated A. muciniphila. Our study demonstrates a novel role of Axin1 in mediating intestinal homeostasis and the microbiota. Further mechanistic studies using specific Axin1 mutations elucidating how Axin1 modulates the microbiome and host inflammatory response will provide new therapeutic strategies for human IBD.

Polysaccharides from Phellinus linteus attenuate type 2 diabetes mellitus in rats via modulation of gut microbiota and bile acid metabolism

Type 2 diabetes mellitus (T2DM) is the most prevalent metabolic disorder. Polysaccharides from Phellinus linteus (PLP) have been found to have anti-diabetes effects, but the mechanism has not been elucidated. The purpose of this study was to investigate the mechanism of PLP on T2DM through the gut microbiota and bile acids metabolism. The T2DM rat model was induced by a high-fat high-carbohydrate (HFHC) diet and streptozocin (30 mg/kg). We found that PLP ameliorated diabetes symptoms. Besides, PLP intervention increased the abundance of g_Bacteroides, g_Parabacteroides, and g_Alistioes, which are associated with the biosynthesis of short-chain fatty acids (SCFAs) and bile acids (BAs) metabolism. Meanwhile, untargeted and targeted metabolomics indicated that PLP could regulate the composition of BAs and increase the levels of SCFAs. Real-time quantitative PCR (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA) were performed to analyze the expression levels of BAs metabolism enzymes in the liver. Finally, the results of correlation analysis and Glucagon-like peptide-1 (GLP-1) showed that PLP stimulated the release of GLP-1 by regulating SCFAs and BAs. In conclusion, this study demonstrated that PLP can regulate gut microbiota and BAs metabolism to promote GLP-1 secretion, thereby increasing insulin release, decreasing blood glucose and attenuating T2DM.

A Comprehensive Review of the Effects of Glycemic Carbohydrates on the Neurocognitive Functions Based on Gut Microenvironment Regulation and Glycemic Fluctuation Control

Improper glycemic carbohydrates (GCs) consumption can be a potential risk factor for metabolic diseases such as obesity and diabetes, which may lead to cognitive impairment. Although several potential mechanisms have been studied, the biological relationship between carbohydrate consumption and neurocognitive impairment is still uncertain. In this review, the main effects and mechanisms of GCs' digestive characteristics on cognitive functions are comprehensively elucidated. Additionally, healthier carbohydrate selection, a reliable research model, and future directions are discussed. Individuals in their early and late lives and patients with metabolic diseases are highly susceptible to dietary-induced cognitive impairment. It is well known that gut function is closely related to dietary patterns. Unhealthy carbohydrate diet-induced gut microenvironment disorders negatively impact cognitive functions through the gut-brain axis. Moreover, severe glycemic fluctuations, due to rapidly digestible carbohydrate consumption or metabolic diseases, can impair neurocognitive functions by disrupting glucose metabolism, dysregulating calcium homeostasis, oxidative stress, inflammatory responses, and accumulating advanced glycation end products. Unstable glycemic status can lead to more severe neurological impairment than persistent hyperglycemia. Slow-digested or resistant carbohydrates might contribute to better neurocognitive functions due to stable glycemic response and healthier gut functions than fully gelatinized starch and nutritive sugars.

Potential Effects of Akkermansia Muciniphila in Aging and Aging-Related Diseases: Current Evidence and Perspectives

Akkermansia muciniphila (A. muciniphila) is an anaerobic bacterium that widely colonizes the mucus layer of the human and animal gut. The role of this symbiotic bacterium in host metabolism, inflammation, and cancer immunotherapy has been extensively investigated over the past 20 years. Recently, a growing number of studies have revealed a link between A. muciniphila, and aging and aging-related diseases (ARDs). Research in this area is gradually shifting from correlation analysis to exploration of causal relationships. Here, we systematically reviewed the association of A. muciniphila with aging and ARDs (including vascular degeneration, neurodegenerative diseases, osteoporosis, chronic kidney disease, and type 2 diabetes). Furthermore, we summarize the potential mechanisms of action of A. muciniphila and offer perspectives for future studies.

Diabetes Mellitus and Gastric Cancer: Correlation and Potential Mechanisms

This review summarizes the correlation between diabetes mellitus (DM) and gastric cancer (GC) from the perspectives of epidemiology, drug use, and potential mechanisms. The association between DM and GC is inconclusive, and the positive direction of the association reported in most published meta-analyses suggests that DM may be an independent risk factor for GC. Many clinical investigations have shown that people with DM and GC who undergo gastrectomy may have better glycemic control. The potential link between DM and GC may involve the interaction of multiple common risk factors, such as obesity, hyperglycemia and hyperinsulinemia, H. pylori infection, and the use of metformin. Although in vitro and in vivo data support that H. pylori infection status and metformin can influence GC risk in DM patients, there are conflicting results. Patient survival outcomes are influenced by multiple factors, so further research is needed to identify the patients who may benefit.

Akkermansia muciniphila supplementation improves glucose tolerance in intestinal Ffar4 knockout mice during the daily light to dark transition

IMPORTANCE

Alterations in the intestinal environment are associated with various diseases, and FFAR4 is abundantly enriched in the intestine, where it has been shown to have the ability to regulate intestinal hormone secretion and intestinal microbiota; here, we confirmed previous reports. Meanwhile, we found that intestinal FFAR4 regulates glucagon-like peptide 1 secretion by decreasing Akkermansia muciniphila abundance and show that such change is associated with the level of glucose utilization at ZT12 in mice. Intestinal FFAR4 deficiency leads to severely impaired glucose tolerance at the ZT12 moment in mice, and Akkermansia muciniphila supplementation ameliorates the abnormal glucose utilization at the ZT12 moment caused by FFAR4 deficiency, which is very similar to the dawn phenomenon in diabetic patients. Collectively, our data suggest that intestinal Ffar4 deteriorates glucose tolerance at the daily light to dark transition by affecting Akkermansia muciniphila.

Inulin Inhibits the Inflammatory Response through Modulating Enteric Glial Cell Function in Type 2 Diabetic Mellitus Mice by Reshaping Intestinal Flora

Inulin, a commonly used dietary fiber supplement, is capable of modulating the gut microbiome. Chronic inflammation resulting from metabolic abnormalities and gut flora dysfunction plays a significant role in the development of type 2 diabetes mellitus (T2DM). Our research has demonstrated that inulin administration effectively reduced colonic inflammation in T2DM mice by inducing changes in the gut microbiota and increasing the concentration of butyric acid, which in turn modulated the function of enteric glial cells (EGCs). Experiments conducted on T2DM mice revealed that inulin administration led to an increase in the Bacteroidetes/Firmicutes ratio and the concentration of butyric acid in the colon. The anti-inflammatory effects of altered gastrointestinal flora and its metabolites were further confirmed through fecal microbiota transplantation. Butyric acid was found to inhibit the activation of the κB inhibitor kinase β/nuclear factor κB pathway, regulate the expression levels of interleukin-6 and tumor necrosis factor-α, suppress the abnormal activation of EGCs, and prevent the release of inflammatory factors by EGCs. Similar results were observed in vitro experiments with butyric acid. Our findings demonstrate that inulin, by influencing the intestinal flora, modifies the activity of EGCs to effectively reduce colonic inflammation in T2DM mice.

Unveiling the potential pleiotropic effects of metformin in treating COVID-19: a comprehensive review

This review article explores the potential of metformin, a medication commonly used for type 2 diabetes, as an antiviral and anti-inflammatory agent in the context of coronavirus disease 2019 (COVID-19). Metformin has demonstrated inhibitory effects on the growth of SARS-CoV-2 in cell culture models and has shown promising results in reducing viral load and achieving undetectable viral levels in clinical trials. Additionally, metformin exhibits anti-inflammatory properties by reducing the production of pro-inflammatory cytokines and modulating immune cell function, which may help prevent cytokine storms associated with severe COVID-19. The drug's ability to regulate the balance between pro-inflammatory Th17 cells and anti-inflammatory Treg cells suggests its potential in mitigating inflammation and restoring T cell functionality. Furthermore, metformin's modulation of the gut microbiota, particularly changes in bacterial taxa and the production of short-chain fatty acids, may contribute to its therapeutic effects. The interplay between metformin, bile acids, the gut microbiome, glucagon-like peptide-1 secretion, and glycemic control has implications for the management of diabetes and potential interventions in COVID-19. By refreshing the current evidence, this review highlights the potential of metformin as a therapeutic option in the management of COVID-19, while also exploring its effects on the gut microbiome and immunometabolism.

Diet, Gut Microbiome, and Their End Metabolites Associate With Acute Pancreatitis Risk

INTRODUCTION

Diet and decreased gut microbiome diversity has been associated with acute pancreatitis (AP) risk. However, differences in dietary intake, gut microbiome, and their impact on microbial end metabolites have not been studied in AP. We aimed to determine differences in (i) dietary intake (ii) gut microbiome diversity and sulfidogenic bacterial abundance, and (iii) serum short-chain fatty acid (SCFA) and hydrogen sulfide (H 2 S) concentrations in AP and control subjects.

METHODS

This case-control study recruited 54 AP and 46 control subjects during hospitalization. Clinical and diet data and stool and blood samples were collected. 16S rDNA sequencing was used to determine gut microbiome alpha diversity and composition. Serum SCFA and H 2 S levels were measured. Machine learning (ML) model was used to identify microbial targets associated with AP.

RESULTS

AP patients had a decreased intake of vitamin D 3 , whole grains, fish, and beneficial eicosapentaenoic, docosapentaenoic, and docosahexaenoic acids. AP patients also had lower gut microbiome diversity ( P = 0.021) and a higher abundance of sulfidogenic bacteria including Veillonella sp. and Haemophilus sp., which were associated with AP risk. Serum acetate and H 2 S concentrations were significantly higher in the AP group ( P < 0.001 and P = 0.043, respectively). ML model had 96% predictive ability to distinguish AP patients from controls.

DISCUSSION

AP patients have decreased beneficial nutrient intake and gut microbiome diversity. An increased abundance of H 2 S-producing genera in the AP and SCFA-producing genera in the control group and predictive ability of ML model to distinguish AP patients indicates that diet, gut microbiota, and their end metabolites play a key role in AP.

Milk protects against sarcopenic obesity due to increase in the genus Akkermansia in faeces of db/db mice

BACKGROUND

Sarcopenic obesity, a combination of sarcopenia and obesity, is a pathological feature of type 2 diabetes. Several human studies have shown that milk is useful in the prevention of sarcopenia. This study was aimed at clarifying the effect of milk on the prevention of sarcopenic obesity in db/db mice.

METHODS

A randomized and investigator-blinded study was conducted using male db/db mice. Eight-week-old db/db mice were housed for 8 weeks and fed milk (100 μL/day) using a sonde. The faecal microbiota transplantation (FMT) group received antibiotics for 2 weeks, starting at 6 weeks of age, followed by FMT twice a week until 16 weeks of age.

RESULTS

Milk administration to db/db mice increased grip strength (Milk-: 164.2 ± 4.7 g, Milk+: 230.2 ± 56.0 g, P = 0.017), muscle mass (soleus muscle, Milk-: 164.2 ± 4.7 mg, Milk+: 230.2 ± 56.0 mg, P < 0.001; plantaris muscle, Milk-: 13.3 ± 1.2 mg, Milk+: 16.0 ± 1.7 mg, P < 0.001) and decreased visceral fat mass (Milk-: 2.39 ± 0.08 g, Milk+: 1.98 ± 0.04 mg, P < 0.001), resulting in a significant increase in physical activity (light: P = 0.013, dark: P = 0.034). FMT from mice fed milk not only improved sarcopenic obesity but also significantly improved glucose intolerance. Microarray analysis of gene expression in the small intestine revealed that the expression of amino acid absorption transporter genes, namely, SIc7a5 (P = 0.010), SIc7a1 (P = 0.015), Ppp1r15a (P = 0.041) and SIc7a11 (P = 0.029), was elevated in mice fed milk. In 16S rRNA sequencing of gut microbiota, the genus Akkermansia was increased in both the mice fed milk and the FMT group from the mice fed milk.

CONCLUSIONS

The findings of this study suggest that besides increasing the intake of nutrients, such as amino acids, milk consumption also changes the intestinal environment, which might contribute to the mechanism of milk-induced improvement of sarcopenic obesity.

The role of intestinal microbiota and microRNAs in the anti-inflammatory effects of cranberry: from pre-clinical to clinical studies

Cranberries have known anti-inflammatory properties, which extend their benefits in the context of several chronic diseases. These benefits highly rely on the polyphenol profile of cranberries, one of few foods rich in A-type proanthocyanidin (PAC). A-type PAC comprises flavan-3-ol subunits with an additional interflavan ether bond in the conformational structure of the molecule, separating them from the more commonly found B-type PAC. PACs with a degree of polymerization higher than three are known to reach the colon intact, where they can be catabolyzed by the gut microbiota and biotransformed into lower molecular weight organic acids that are available for host absorption. Gut microbiota-derived metabolites have garnered much attention in the past decade as mediators of the health effects of parent compounds. Though, the mechanisms underlying this phenomenon remain underexplored. In this review, we highlight emerging evidence that postulates that polyphenols, including ones derived from cranberries, and their metabolites could exert anti-inflammatory effects by modulating host microRNAs. Our review first describes the chemical structure of cranberry PACs and a pathway for how they are biotransformed by the gut microbiota. We then provide a brief overview of the benefits of microbial metabolites of cranberry in the intestinal tract, at homeostasis and in inflammatory conditions. Finally, we discuss the role of microRNAs in intestinal health and in response to cranberry PAC and how they could be used as targets for the maintenance of intestinal homeostasis. Most of this research is pre-clinical and we recognize that conducting clinical trials in this context has been hampered by the lack of reliable biomarkers. Our review discusses the use of miRNA as biomarkers in this context.

A Higher Abundance of Actinomyces spp. in the Gut Is Associated with Spontaneous Preterm Birth

Preterm birth is a major challenge in pregnancy worldwide. Prematurity is the leading cause of death in infants and may result in severe complications. Nearly half of preterm births are spontaneous, but do not have recognizable causes. This study investigated whether the maternal gut microbiome and associated functional pathways might play a key role in spontaneous preterm birth (sPTB). Two hundred eleven women carrying singleton pregnancies were enrolled in this mother-child cohort study. Fecal samples were freshly collected at 24-28 weeks of gestation before delivery, and the 16S ribosomal RNA gene was sequenced. Microbial diversity and composition, core microbiome, and associated functional pathways were then statistically analyzed. Demographic characteristics were collected using records from the Medical Birth Registry and questionnaires. The result showed that the gut microbiome of mothers with over-weight (BMI ≥ 24) before pregnancy have lower alpha diversity than those with normal BMI before pregnancy. A higher abundance of Actinomyces spp. was filtered out from the Linear discriminant analysis (LDA) effect size (LEfSe), Spearman correlation, and random forest model, and was inversely correlated with gestational age in sPTB. The multivariate regression model showed that the odds ratio of premature delivery was 3.274 [95% confidence interval (CI): 1.349; p = 0.010] in the group with over-weight before pregnancy with a cutoff Hit% > 0.022 for Actinomyces spp. The enrichment of Actinomyces spp. was negatively correlated with glycan biosynthesis and metabolism in sPTB by prediction from the Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) platform. Maternal gut microbiota showing a lower alpha diversity, increased abundance of Actinomyces spp., and dysregulated glycan metabolism may be associated with sPTB risk.

Role of Akkermansia in Human Diseases: From Causation to Therapeutic Properties

The gut microbiota plays a critical role in the modulation of host metabolism and immune response, and its impairment has been implicated in many gastrointestinal and extraintestinal diseases. Current evidence shows the well-documented role of A. muciniphila in maintaining the integrity of the intestinal barrier, modulating the host immune response, and improving several metabolic pathways, making it a key element in the pathogenesis of several human diseases. In this scenario, A. muciniphila is the most promising next-generation probiotic and one of the first microbial species suitable for specific clinical use when compared with traditional probiotics. Further studies are needed to provide more accurate insight into its mechanisms of action and to better elucidate its properties in several major areas, paving the way for a more integrated and personalized therapeutic approach that finally makes the most of our knowledge of the gut microbiota.

Pharmacomicrobiomics and type 2 diabetes mellitus: A novel perspective towards possible treatment

Type 2 diabetes mellitus (T2DM), a major driver of mortality worldwide, is more likely to develop other cardiometabolic risk factors, ultimately leading to diabetes-related mortality. Although a set of measures including lifestyle intervention and antidiabetic drugs have been proposed to manage T2DM, problems associated with potential side-effects and drug resistance are still unresolved. Pharmacomicrobiomics is an emerging field that investigates the interactions between the gut microbiome and drug response variability or drug toxicity. In recent years, increasing evidence supports that the gut microbiome, as the second genome, can serve as an attractive target for improving drug efficacy and safety by manipulating its composition. In this review, we outline the different composition of gut microbiome in T2DM and highlight how these microbiomes actually play a vital role in its development. Furthermore, we also investigate current state-of-the-art knowledge on pharmacomicrobiomics and microbiome's role in modulating the response to antidiabetic drugs, as well as provide innovative potential personalized treatments, including approaches for predicting response to treatment and for modulating the microbiome to improve drug efficacy or reduce drug toxicity.

Health and Disease: Akkermansia muciniphila , the Shining Star of the Gut Flora

Akkermansia muciniphila ( A. muciniphila ) has drawn much attention as an important gut microbe strain in recent years. A. muciniphila can influence the occurrence and development of diseases of the endocrine, nervous, digestive, musculoskeletal, and respiratory systems and other diseases. It can also improve immunotherapy for some cancers. A. muciniphila is expected to become a new probiotic in addition to Lactobacillus and Bifidobacterium . An increase in A. muciniphila abundance through direct or indirect A. muciniphila supplementation may inhibit or even reverse disease progression. However, some contrary findings are found in type 2 diabetes mellitus and neurodegenerative diseases, where increased A. muciniphila abundance may aggravate the diseases. To enable a more comprehensive understanding of the role of A. muciniphila in diseases, we summarize the relevant information on A. muciniphila in different systemic diseases and introduce regulators of A. muciniphila abundance to promote the clinical transformation of A. muciniphila research.

Changes in Gut Microbiome upon Orchiectomy and Testosterone Administration in AOM/DSS-Induced Colon Cancer Mouse Model

PURPOSE

Sex hormones are known to affect the gut microbiota. Previously, we reported that endogenous and exogenous testosterone are associated with colorectal cancer (CRC) development and submucosal invasion. In the present study, we investigated whether the gut microbiota is affected by orchiectomy (ORX) and testosterone propionate (TP) administration using an azoxymethane/dextran sulfate sodium (AOM/DSS)-induced CRC mouse model.

MATERIALS AND METHODS

Gut microbiota was evaluated by means of 16S rRNA gene sequencing of stool DNA extracted from feces that were obtained at 13 weeks after AOM injection (from 22-week-old animals) and stored in a gas-generating pouch.

RESULTS

The increase in microbial diversity (Chao1 and Phylogenetic Diversity index) and Firmicutes/Bacteroidetes (F/B) ratio upon AOM/DSS treatment in ORX mice was significantly decreased by TP supplementation. The ratio of commensal bacteria to opportunistic pathogens was lower in the TP-administered females and ORX mice than in the AOM/DSS group. Opportunistic pathogens (Mucispirillum schaedleri or Akkermansia muciniphila) were identified only in the TP group. In addition, microbial diversity and F/B ratio were higher in male controls than in female and ORX controls. Flintibacter butyricus, Ruminococcus bromii, and Romboutsia timonensis showed similar changes in the male control group as those in the female and ORX controls.

CONCLUSION

In conclusion, testosterone determines the dysbiosis of gut microbiota, which suggests that it plays a role in the sex-related differences in colorectal carcinogenesis.

The human gut microbiota and glucose metabolism: a scoping review of key bacteria and the potential role of SCFAs

The gut microbiota plays a fundamental role in human nutrition and metabolism and may have direct implications for type 2 diabetes and associated preconditions. An improved understanding of relations between human gut microbiota and glucose metabolism could lead to novel opportunities for type 2 diabetes prevention, but human observational studies reporting on such findings have not been extensively reviewed. Here, we review the literature on associations between gut microbiota and markers and stages of glucose dysregulation and insulin resistance in healthy adults and in adults with metabolic disease and risk factors. We present the current evidence for identified key bacteria and their potential roles in glucose metabolism independent of overweight, obesity, and metabolic drugs. We provide support for SCFAs mediating such effects and discuss the role of diet, as well as metabolites derived from diet and gut microbiota interactions. From 5983 initially identified PubMed records, 45 original studies were eligible and reviewed. α Diversity and 45 bacterial taxa were associated with selected outcomes. Six taxa were most frequently associated with glucose metabolism: Akkermansia muciniphila, Bifidobacterium longum, Clostridium leptum group, Faecalibacterium prausnitzii, and Faecalibacterium (inversely associated) and Dorea (directly associated). For Dorea and A. muciniphila, associations were independent of metabolic drugs and body measures. For A. muciniphila and F. prausnitzii, limited evidence supported SCFA mediation of potential effects on glucose metabolism. We conclude that observational studies applying metagenomics sequencing to identify species-level relations are warranted, as are studies accounting for confounding factors and investigating SCFA and postprandial glucose metabolism. Such advances in the field will, together with mechanistic and prospective studies and investigations into diet-gut microbiota interactions, have the potential to bring critical insight into roles of gut microbiota and microbial metabolites in human glucose metabolism and to contribute toward the development of novel prevention strategies for type 2 diabetes, including precision nutrition.

Gut microbiota in women with gestational diabetes mellitus has potential impact on metabolism in pregnant mice and their offspring

Studies have shown that gestational diabetes mellitus (GDM) is closely related to abnormalities in the gut microbiota, and the offspring of these women have an increased risk of diabetes. There is no direct evidence of whether bacteria in women with GDM colonize the intestinal tract of offspring and cause hyperglycemia. In this fecal microbiota transplantation (FMT), pregnant mouse model study, two groups of germ-free (GF) mice after FMT showed different colonization patterns of gut microbiota and phenotype. Compared with the control group (healthy-FMT), we found in the GDM-FMT group as a lower relative abundance of Akkermansia and Faecalibacterium; a lower content of short-chain fatty acids and naringenin in feces; an elevated blood glucose; an inflammatory factor expression (TNF-α, CXCL-15, and IL-6), and a hepatic fat deposition. In addition, the influence of the gut microbiota continued in offspring. The gut microbiota of the offspring of GDM-FMT mice was still different from that of the control group as a lower relative abundance of Akkermansia and Parvibacter; and a higher relative abundance of bacteria such as Oscillibacter, Romboutsia, and Harryflintia. In addition, the offspring of GDM-FMT mice had higher body weight and blood glucose levels than the control offspring.

Akkermansia muciniphila and Gut Immune System: A Good Friendship That Attenuates Inflammatory Bowel Disease, Obesity, and Diabetes

Akkermansia muciniphila is a Gram-negative anaerobic mucus-layer-degrading bacterium that colonizes the intestinal mucosa of humans and rodents. Metagenomic data have shown an inverse correlation between the abundance of A. muciniphila and diseases such as inflammatory bowel disease (IBD), obesity, and diabetes. Thus, in recent decades, the potential of this bacterium as an immunomodulatory probiotic for autoimmune and chronic inflammatory diseases has been explored in experimental models. Corroborating these human correlation data, it has been reported that A. muciniphila slows down the development and progression of diabetes, obesity, and IBD in mice. Consequently, clinical studies with obese and diabetic patients are being performed, and the preliminary results are very promising. Therefore, this mini review highlights the main findings regarding the beneficial roles of A. muciniphila and its action mechanisms in autoimmune and chronic inflammatory diseases.

Fiber Consumption Mediates Differences in Several Gut Microbes in a Subpopulation of Young Mexican Adults

Diet is a determinant for bodyweight and gut microbiota composition. Changes in dietary patterns are useful for the prevention and management of overweight and obesity. We aim to evaluate diet behavior and its potential association with selected gut bacteria and body weight among Mexican young adults. Mexican college students aged between 18 and 25 (normal-weight, overweight, and obese) were recruited. Anthropometric variables were recorded. A validated food frequency questionnaire was applied to all the participants. The percentages of macronutrients, fiber, and energy were calculated, and fecal samples were analyzed by real-time-qPCR to quantify selected gut bacteria. All the participants showed an unbalanced dietary pattern. However, the consumption of fruits, non-fat cereals, and oils and fats without protein were higher in the normal-weight individuals. In the overweight/obese participants, fiber intake did not correlate with the microbial variables, while Kcal from protein and Clostridium leptum correlated positively with Lactobacillus. Similarly, Clostridium coccoides-Eubacterium rectale correlated with Akkermansia muciniphila. In the normal-weight participants, Clostridium leptum and Lactobacillus correlated positively with Clostridium coccoides-Eubacterium rectale and Bifidobacterium, respectively, and Bacteroidetes negatively with Akkermansia muciniphila. In conclusion, a higher fiber intake had a positive impact on body weight and bacterial gut composition in this Mexican population of college students.

Gut Microbiota: An Important Player in Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is one of the common metabolic diseases in the world. Due to the rise in morbidity and mortality, it has become a global health problem. To date, T2DM still cannot be cured, and its intervention measures mainly focus on glucose control as well as the prevention and treatment of related complications. Interestingly, the gut microbiota plays an important role in the development of metabolic diseases, especially T2DM. In this review, we introduce the characteristics of the gut microbiota in T2DM population, T2DM animal models, and diabetic complications. In addition, we describe the molecular mechanisms linking host and the gut microbiota in T2DM, including the host molecules that induce gut microbiota dysbiosis, immune and inflammatory responses, and gut microbial metabolites involved in pathogenesis. These findings suggest that we can treat T2DM and its complications by remodeling the gut microbiota through interventions such as drugs, probiotics, prebiotics, fecal microbiota transplantation (FMT) and diets.

Adjuvant Probiotics of Lactobacillus salivarius subsp. salicinius AP-32, L. johnsonii MH-68, and Bifidobacterium animalis subsp. lactis CP-9 Attenuate Glycemic Levels and Inflammatory Cytokines in Patients With Type 1 Diabetes Mellitus

INTRODUCTION

Type 1 diabetes mellitus (T1DM) is characterized by autoimmune destruction of pancreatic β cells. Previous study has discovered that probiotic strains residing in the gut play essential roles in host immune regulation. However, few clinical results demonstrated probiotic would actually benefit in attenuating glycated hemoglobin (HbA1c) along with inflammatory cytokine levels of the T1DM patients and analyzed their gut microbiota profile at the same time. In this clinical trial, we evaluated the therapeutic efficacy of probiotics on HbA1c along with inflammatory cytokine levels of T1DM patients to determine an alternative administration mode for T1DM medication. The probiotics changed T1DM gut microbiota profile will be measured by next-generation sequencing (NGS).

RESEARCH DESIGN AND METHODS

A randomized, double-blind, placebo-controlled trial was performed at China Medical University Hospital. T1DM patients between 6 and 18 years of age were enrolled. 27 patients were administered regular insulin therapy plus capsules containing probiotic strains Lactobacillus salivarius subsp. salicinius AP-32, L. johnsonii MH-68, and Bifidobacterium animalis subsp. lactis CP-9 daily for 6 months, and 29 patients were administered insulin therapy without extra probiotic supplement as placebo group. The variations of fasting blood glucose and HbA1c in these patients were analyzed. In addition, serum levels of inflammatory cytokines and anti-inflammatory cytokine were assessed using enzyme-linked immunosorbent assay. Patients' stool microbiota were all subjects to NGS analysis.

RESULTS

NGS data showed elevated populations of Bifidobacterium animalis, Akkermansia muciniphila and Lactobacillus salivarius in the gut of patients with T1DM who were taking probiotics. Patients with T1DM who were administered probiotics showed significantly reduced fasting blood glucose levels compared with the before-intervention levels. The HbA1c levels of the patients also improved after administration of probiotics. The concentrations of IL-8, IL-17, MIP-1β, RANTES, and TNF-α were significantly reduced and were associated with an increased TGF-β1 expression after probiotic intervention. The persistence effect of glycemic control and immunomodulation were observed even 3 months after discontinuation of the probiotics.

CONCLUSIONS

Here, we found that conventional insulin therapy plus probiotics supplementation attenuated T1DM symptoms than receiving insulin treatment only. Probiotics supplementation with insulin treatment changed gut microbiota and revealed better outcome in stabilizing glycemic levels and reducing HbA1c levels in patients with T1DM through beneficial regulation of immune cytokines.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, identifier NCT03880760.

The Effect of Formula-based Nutritional Treatment on Colitis in a Murine Model

BACKGROUND

Exclusive enteral nutrition (EEN) induces remission in pediatric Crohn's disease (CD). The exact mechanism of EEN therapy in CD is unknown, but alteration of the intestinal microflora after EEN is thought to affect mucosal healing. To determine the link between EEN therapy and therapeutic efficacy in CD, we established a murine model of dextran sulfate sodium (DSS)-induced colitis and applied EEN therapy.

METHODS

Eight-week-old C57BL/6 mice were administered DSS for 4 days to induce colitis, and either normal chow (NC) or EEN was administered for the following 4 days. The mice were grouped according to the feeding pattern after DSS administration: DSS/NC and DSS/EEN groups. The clinical course was confirmed via daily observation of the weight and stool. Fecal samples were collected and 16sRNA sequencing was used. The mice were sacrificed to confirm colonic histopathology.

RESULTS

Weight reduction and increase in disease activity were observed as the day progressed for 4 days after DSS administration. There was significant weight recovery and improvement in disease activity in the EEN group compared to that in the NC group. Verrucomicrobia and Proteobacteria abundances tended to increase and Bacteroidetes abundance decreased in the EEN group. In the EEN group, significant changes in the β-diversity of the microbiota were observed. In the analysis of microbiome species, abundances of Akkermansia muciniphila, Clostridium cocleatum, mucin-degrading bacteria, Flintibacter butyricus, and Parabacteroides goldsteinii, which are beneficial microbiota, were significantly increased in the EEN group compared to those in the NC group. More abundant mucins were confirmed in the colonic histopathology of the EEN group. These microbial and histopathological differences suggested that EEN might improve colitis symptoms in a murine colitis model by promoting mucin recycling and subsequently inducing the healing effect of the gut barrier.

CONCLUSION

EEN showed clinical efficacy in a murine model of colitis. Based on the increase in mucin-degrading bacteria and the pathological increase in mucin production after EEN administration, it can be observed that mucin plays an important role in the therapeutic effect of EEN.

Comprehensive profiles and diagnostic value of menopausal-specific gut microbiota in premenopausal breast cancer

In Western countries, breast cancer tends to occur in older postmenopausal women. However, in Asian countries, the proportion of younger premenopausal breast cancer patients is increasing. Increasing evidence suggests that the gut microbiota plays a critical role in breast cancer. However, studies on the gut microbiota in the context of breast cancer have mainly focused on postmenopausal breast cancer. Little is known about the gut microbiota in the context of premenopausal breast cancer. This study aimed to comprehensively explore the gut microbial profiles, diagnostic value, and functional pathways in premenopausal breast cancer patients. Here, we analyzed 267 breast cancer patients with different menopausal statuses and age-matched female controls. The α-diversity was significantly reduced in premenopausal breast cancer patients, and the β-diversity differed significantly between breast cancer patients and controls. By performing multiple analyses and classification, 14 microbial markers were identified in the different menopausal statuses of breast cancer. Bacteroides fragilis was specifically found in young women of premenopausal statuses and Klebsiella pneumoniae in older women of postmenopausal statuses. In addition, menopausal-specific microbial markers could exhibit excellent discriminatory ability in distinguishing breast cancer patients from controls. Finally, the functional pathways differed between breast cancer patients and controls. Our findings provide the first evidence that the gut microbiota in premenopausal breast cancer patients differs from that in postmenopausal breast cancer patients and shed light on menopausal-specific microbial markers for diagnosis and investigation, ultimately providing a noninvasive approach for breast cancer detection and a novel strategy for preventing premenopausal breast cancer.

Polysaccharides Obtained from Cordyceps militaris Alleviate Hyperglycemia by Regulating Gut Microbiota in Mice Fed a High-Fat/Sucrose Diet

Polysaccharides isolated from fungus Cordyceps militaris display multi-biofunctions, such as immunostimulation, down-regulation of hyperlipidemia, and anti-cancer function. The occurrence of obesity and metabolic syndrome is related to the imbalance of gut microbiota. In this study, the effects of C. militaris and its fractions on modifying metabolic syndrome in mice were evaluated. Mice were fed a high-fat/high-sucrose diet (HFSD) for 14 weeks to induce body weight increase and hyperlipidemia symptoms in mice, and then the mice were simultaneously given a HFSD and C. militaris samples for a further 8 weeks. The results indicated that the fruit body, polysaccharides, and cordycepin obtained from C. militaris had different efficacies on regulating metabolic syndrome and gut microbiota in HFSD-treated mice. Polysaccharides derived from C. militaris decreased the levels of blood sugar and serum lipids in mice fed HFSD. In addition, C. militaris-polysaccharide treatment obviously improved intestinal dysbiosis through promoting the population of next generation probiotic Akkermansia muciniphila in the gut of mice fed HFSD. In conclusion, polysaccharides derived from C. militaris have the potential to act as dietary supplements and health food products for modifying the gut microbiota to improve the metabolic syndrome.