Social overcrowding impacts gut microbiota, promoting stress, inflammation, and dysglycemia.

An array of chronic inflammatory diseases, including metabolic diseases such as obesity and diabetes, are thought to be promoted by disturbance of the intestinal microbiota. Such diseases disproportionately impact low-income communities, which are frequently afflicted by chronic stress and increased density housing. Hence, we hypothesized that overcrowded housing might promote stress, microbiota dysbiosis, inflammation, and, consequently, metabolic diseases. We tested this hypothesis in a tractable murine model of social overcrowding (SOC), in which mice were housed at twice normal density. SOC moderately impacted behavior in some widely used assays (Open Field, Elevated Plus Maze and Light/Dark tests) and resulted in a stark increase in corticosterone levels. Such indices of stress were associated with mild chronic gut inflammation, hyperglycemia, elevations in colonic cytokines, and alterations in gut microbiota composition. All of these consequences of SOC were eliminated by broad spectrum antibiotics, while some (inflammation and hyperglycemia) were transmitted by microbiota transplantation from SOC mice to germfree mice housed at normal density. Altogether, these results suggest a central role for intestinal microbiota in driving stress, inflammation, and chronic diseases that are promoted by overcrowded housing.

The Impact of Microbial Composition on Postprandial Glycaemia and Lipidaemia: A Systematic Review of Current Evidence.

Postprandial hyperglycaemia is associated with increased risk of cardiovascular disease. Recent studies highlight the role of the gut microbiome in influencing postprandial glycaemic (PPG) and lipidaemic (PPL) responses. The authors of this review sought to address the question: "To what extent does individual gut microbiome diversity and composition contribute to PPG and PPL responses?". CINAHL Plus, PubMed, Web of Science, and the Cochrane Central Register of Controlled Trials (CENTRAL) databases were searched from January 2010 to June 2020. Following screening, 22 studies were eligible to be included in the current review. All trials reported analysis of gut microbiome diversity and composition and PPG and/or PPL. Results were reported according to the 'Preferred Reporting Items for Systematic Reviews and Meta-Analysis' (PRISMA) statement. Individual microbiota structure was found to play a key role in determining postprandial metabolic responses in adults and is attributed to a complex interplay of diet, microbiota composition, and metagenomic activity, which may be predicted by metagenomic analysis. Alterations of gut microbiota, namely relative abundance of bacterial phylum Actinobacteria and Proteobacteria, along with Enterobacteriaceae, were associated with individual variation in postprandial glycaemic response in adults. The findings of the current review present new evidence to support a personalised approach to nutritional recommendations and guidance for optimal health, management, and treatment of common metabolic disorders. In conclusion, personalised nutrition approaches based on individual microbial composition may improve postprandial regulation of glucose and lipids, providing a potential strategy to ameliorate cardiometabolic health outcomes.

Three-year mortality in cryptococcal meningitis: Hyperglycemia predict unfavorable outcome.

Existing evidence revealed grave prognosis for cryptococcal meningitis (CM), particularly its short-term mortality. However, its long-term survival and prognostic factors remained unknown. This study investigated 3-year mortality and analyzed its predictive factors in patients with CM. This retrospective cohort study with 83 cerebrospinal fluid culture-confirmed CM patients was conducted at China Medical University Hospital from 2003 to 2016. The 3-year mortality rate in patients with CM was 54% (45 deaths among 83 patients). Advanced age, human immunodeficiency virus (HIV) seronegative state, low Glasgow Coma Scale score on admission, decreased hemoglobin and hyperglycemia on diagnosis were associated with 3-year mortality. After multivariate adjustment in the Cox proportional hazard model, only severe hyperglycemia (serum glucose ≥200 mg/dL) on diagnosis could predict 3-year mortality.

Amelioration of hyperglycaemia and hyperlipidaemia by adjusting the interplay between gut microbiota and bile acid metabolism: Radix Scutellariae as a case.

BACKGROUND: Our previous clinical research showed that the interaction between gut microbiota and bile acids (BAs) in patients with type 2 diabetes mellitus (T2DM) changed significantly. We hypothesized that T2DM could be improved by adjusting this interaction mediated by farnesoid X receptor (FXR). T2DM belongs to the category of "xiaoke" in traditional Chinese medicine. Radix scutellariae has the effects of clearing away heat and eliminating dampness, curing jaundice and quenching thirst and is widely used alone or in combination with other medicines for the treatment of T2DM in China and throughout Asia. Additionally, the interaction between Radix scutellariae and gut microbiota may influence its efficacy in the treatment of T2DM. PURPOSE: This study chose Radix scutellariae to validate that T2DM could improve by adjusting the interaction between gut microbiota and bile acid metabolism. STUDY DESIGN AND METHODS: Radix scutellariae water extract (WESB) was administered to a T2DM rat model established by a high-fat diet combined with streptozotocin. The body weight and blood glucose and insulin levels were measured. The levels of serum lipids, creatinine, uric acid, albumin and total bile acid were also detected. Changes in the pathology and histology of the pancreas, liver and kidney were observed by haematoxylin-eosin staining. The 16S rRNAs of gut microbiota were sequenced, and the faecal and serum BAs were determined by liquid chromatography tandem mass spectrometry. The expression levels of BA metabolism-associated proteins in the liver and intestine were evaluated by immunoblot analysis. RESULTS: The results showed that WESB improved hyperglycaemia, hyperlipaemia, and liver and kidney damage in T2DM rats. In addition, the abundances of key gut microbiota and the concentrations of certain secondary BAs in faeces and serum were restored. Moreover, there was a significant correlation between the restored gut microbiota and BAs, which might be related to the activation of liver cholesterol 7α-hydroxylase (CYP7A1) and the inhibition of FXR expression in the intestine rather than the liver. CONCLUSIONS: This study provided new ideas for the prevention or treatment of clinical diabetes and its complications by adjusting the interaction between gut microbiota and bile acid metabolism.

Microbiota and Diabetes Mellitus: Role of Lipid Mediators.

Diabetes Mellitus (DM) is an inflammatory clinical entity with different mechanisms involved in its physiopathology. Among these, the dysfunction of the gut microbiota stands out. Currently, it is understood that lipid products derived from the gut microbiota are capable of interacting with cells from the immune system and have an immunomodulatory effect. In the presence of dysbiosis, the concentration of lipopolysaccharides (LPS) increases, favoring damage to the intestinal barrier. Furthermore, a pro-inflammatory environment prevails, and a state of insulin resistance and hyperglycemia is present. Conversely, during eubiosis, the production of short-chain fatty acids (SCFA) is fundamental for the maintenance of the integrity of the intestinal barrier as well as for immunogenic tolerance and appetite/satiety perception, leading to a protective effect. Additionally, it has been demonstrated that alterations or dysregulation of the gut microbiota can be reversed by modifying the eating habits of the patients or with the administration of prebiotics, probiotics, and symbiotics. Similarly, different studies have demonstrated that drugs like Metformin are capable of modifying the composition of the gut microbiota, promoting changes in the biosynthesis of LPS, and the metabolism of SCFA.

Probiotic-fermented blueberry juice prevents obesity and hyperglycemia in high fat diet-fed mice in association with modulating the gut microbiota.

Blueberry dietary interventions have demonstrated remarkable potential against obesity and type 2 diabetes mellitus. However, the effects of fermented blueberry juice on metabolic syndrome, the gut microbiota, and insulin resistance have not yet been reported. This study aimed to investigate the potential of fermented blueberry juice against obesity, hyperglycemia, and gut microbiota dysbiosis in high fat diet (HFD)-fed mice. Our study findings revealed that supplementation with fresh blueberry juice (BBJ), and fermented blueberry juice with homemade probiotic starter (FBJ) or commercial starter (CFBJ) significantly decreased fat accumulation and low density lipoprotein cholesterol (LDL-C) levels in HFD-fed mice. FBJ showed relatively more potency to reduce body weight than BBJ and CFBJ. The percentage increase in the body weight of the FBJ group was almost the same as that in the normal chow diet (NCD) group, and was approximately 10% lower than the BBJ and CFBJ groups. Overall, all blueberry juices significantly ameliorated hyperlipidemia and insulin resistance in HFD-fed mice. Moreover, the dietary interventions with BBJ, FBJ, and CFBJ for 17 weeks significantly improved the community richness and diversity of the gut microflora along with an altered structure in the HFD-fed mice group. The FBJ treated mice group showed relatively low abundance of Firmicutes, obesity-related bacteria (Oscillibacter and Alistipes), and high abundance of lean bacteria (Akkermansia, Barnesiella, Olsenella, Bifidobacterium, and Lactobacillus) compared to the HFD-fed mice group. Furthermore, BBJ and FBJ treatments regulated the liver mRNA and protein expression levels involved in lipid and glucose metabolism. This study inferred that fermented blueberry juice could be used as a functional food to prevent the modern pandemics i.e., obesity and insulin resistance.

Perturbations of gut microbiota in gestational diabetes mellitus patients induce hyperglycemia in germ-free mice.

Shifts in the maternal gut microbiota have been implicated in the development of gestational diabetes mellitus (GDM). Understanding the interaction between gut microbiota and host glucose metabolism will provide a new target of prediction and treatment. In this nested case-control study, we aimed to investigate the causal effects of gut microbiota from GDM patients on the glucose metabolism of germ-free (GF) mice. Stool and peripheral blood samples, as well as clinical information, were collected from 45 GDM patients and 45 healthy controls (matched by age and prepregnancy body mass index (BMI)) in the first and second trimester. Gut microbiota profiles were explored by next-generation sequencing of the 16S rRNA gene, and inflammatory factors in peripheral blood were analyzed by enzyme-linked immunosorbent assay. Fecal samples from GDM and non-GDM donors were transferred to GF mice. The gut microbiota of women with GDM showed reduced richness, specifically decreased Bacteroides and Akkermansia, as well as increased Faecalibacterium. The relative abundance of Akkermansia was negatively associated with blood glucose levels, and the relative abundance of Faecalibacterium was positively related to inflammatory factor concentrations. The transfer of fecal microbiota from GDM and non-GDM donors to GF mice resulted in different gut microbiota colonization patterns, and hyperglycemia was induced in mice that received GDM donor microbiota. These results suggested that the shifting pattern of gut microbiota in GDM patients contributed to disease pathogenesis.

Hyperglycemia suppresses the regulatory effect of hypoxia-inducible factor-1α in pulmonary Aspergillus fumigatus infection.

Aspergillus fumigatus is one of the most common fungal infections involved in the pulmonary diseases. Hypoxia-inducible factor-1α (HIF-1α) is important for antifungal immunity. Diabetes is a risk factor of pulmonary A. fumigatus infection and could affect the expression of HIF-1α. The aim of this investigation was to evaluate the role of HIF-1α in pulmonary A. fumigatus infection in diabetes. In murine model, we found diabetic mice had aggravated pulmonary A. fumigatus infection and declined expression of HIF-1α following pulmonary A. fumigatus infection. And these changes could be corrected by dimethyloxalylglycine (DMOG), the agonist of HIF-1α. In cell experiment, after A. fumigatus stimulation, hyperglycemic state was with a decreased HIF-1α expression and increased NLRP3/IL-1ß signal pathway. The percentages of Th1 and Treg cells decreased, while percentages of Th2 and Th17 increased in hyperglycemic group. DMOG suppressed A. fumigatus-stimulated NLRP3 and IL-1ß expressions in hyperglycemic group and corrected Th and Treg cells differentiation. These regulatory effects of DMOG could be dampened by activating of NLRP3. These data indicated that hyperglycemia suppressed the regulatory effect of HIF-1α in pulmonary A. fumigatus infection, which can affect Th and Treg cells differentiation by regulating the NLRP3/IL-1ß signal pathway.

Gut microbiota in early pregnancy among women with Hyperglycaemia vs. Normal blood glucose.

BACKGROUND: Recent studies suggest that there is a link between the gut microbiota and glucose metabolism. This study aimed to compare the gut microbiota during early pregnancy of women with hyperglycymia to those with normal blood glucose. METHODS: Gut microbial composition was analysed in 22 women with hyperglycaemia and 28 age-matched healthy controls during their first prenatal visits (< 20 weeks) using high throughput sequencing of the V3-V4 region of the 16S ribosomal RNA gene. Hyperglycemia was diagnosed based on the criteria recommended by the International Association of Diabetes and Pregnancy Study Groups in 2010. RESULTS: Women with hyperglycemia in pregnancy (HIP) had significantly lower microbial richness and diversity compared with healthy pregnant women. The proportions of the Firmicutes and Bacteroidetes phyla and the ratio of Firmicutes:Bacteroidetes were not different between the two groups. We observed that individuals with HIP had an increased abundance of Nocardiaceae, Fusobacteriaceae, etc., whereas healthy controls had significantly higher levels of Christensenellaceae, Clostridiales_vadinBB60_group, Coriobacteriaceae, etc. Similarly, levels of the members of the Ruminococcaceae family, including Ruminococcaceae_UCG-014, Ruminococcaceae_UCG-003, and Ruminococcaceae_UCG-002, were significantly reduced in the HIP group and were negatively correlated with HbA1c. HbA1c levels were positively correlated with Bacteroidaceae and Enterobacteriaceae and negatively correlated with Christensenellaceae, etc. CRP was positively correlated with the Bacteroidaceae and Fusobacteriaceae families and the Fusobacterium genus. CONCLUSIONS: Our study revealed that individuals with HIP have gut microbial dysbiosis and that certain bacterial groups are associated with glucose metabolism during pregnancy. Further study is needed to provide new ideas to control glucose by modifying the gut microbiota.

Type 2 diabetes induced microbiome dysbiosis is associated with therapy resistance in pancreatic adenocarcinoma.

Resistance to therapy is one of the major factors that contribute to dismal survival statistics in pancreatic cancer. While there are many tumor intrinsic and tumor microenvironment driven factors that contribute to therapy resistance, whether pre-existing metabolic diseases like type 2 diabetes (T2D) contribute to this has remained understudied. It is well accepted that hyperglycemia associated with type 2 diabetes changes the gut microbiome. Further, hyperglycemia also enriches for a "stem-like" population within the tumor. In the current study, we observed that in a T2D mouse model, the microbiome changed significantly as the hyperglycemia developed in these animals. Our results further showed that, tumors implanted in the T2D mice responded poorly to gemcitabine/paclitaxel (Gem/Pac) standard of care compared to those in the control group. A metabolomic reconstruction of the WGS of the gut microbiota further revealed that an enrichment of bacterial population involved in drug metabolism in the T2D group. Additionally, we also observed an increase in the CD133+ tumor cells population in the T2D model. These observations indicated that in an animal model for T2D, microbial dysbiosis is associated with increased resistance to chemotherapeutic compounds.

Bound Phenolics Ensure the Antihyperglycemic Effect of Rice Bran Dietary Fiber in db/db Mice via Activating the Insulin Signaling Pathway in Skeletal Muscle and Altering Gut Microbiota.

Whole-grain dietary fiber intake is beneficial in the prevention of metabolic syndrome. Considering rich in bound phenolics being a special characteristic of whole-grain dietary fiber, the aim of this study was to evaluate the effects of the presence or absence of bound phenolics in rice bran dietary fiber (RBDF) on regulating glucose metabolism in diabetic db/db mice. In comparison to phenolics-removed RBDF (PR-RBDF) intervention without an antihyperglycemic effect, RBDF and formulated RBDF (F-RBDF, obtained by mixing PR-RBDF and hydrolyzed-bound phenolics) significantly reduced fasting blood glucose levels after 1 and 5 weeks of interventions, respectively. The presence of bound phenolics interventions could activate the IRS1/AKT/GLUT4 insulin signaling pathway in skeletal muscle and alter gut microbiota by modulating gut microbiota dysbiosis and enriching the butyric-acid-producing bacteria genera of the families Lachnospiraceae and Ruminococcaceae, thus leading to the reduction of blood glucose levels. These findings indicate that bound phenolics ensure the antihyperglycemic effect of RBDF.

Severe pulmonary radiological manifestations are associated with a distinct biochemical profile in blood of tuberculosis patients with dysglycemia.

BACKGROUND: Diabetes mellitus (DM) is thought to affect tuberculosis (TB) clinical presentation and treatment response. Whether DM impacts radiological manifestations of pulmonary TB is still not clear. This study investigated the impact of glycemic status on radiological manifestations of pulmonary TB cases and its relationship with concentration of biochemical parameters in peripheral blood. METHODS: A retrospective cross-sectional study used data from 132 microbiologically confirmed pulmonary TB patients from Lima, Peru, evaluated in a previous investigation performed between February and December 2017. Chest radiographs were analyzed by a radiologist and a pulmonologist. Radiographic lesions were identified as cavities, alveolar infiltrates and fibrous tracts. Hyperglycemia in TB patients was identified by use of fasting plasma glucose, HbA1c and oral glucose tolerance test. Clinical, biochemical and hematological parameters were also analyzed. RESULTS: TB patients with hyperglycemia presented more frequently with cavities, alveolar infiltrates and fibrous tracts than those with normoglycemia. Hierarchical clustering analysis indicated that patients with more diverse and higher number of lung lesions exhibited a distinct laboratorial profile characterized by heightened white blood cell counts and circulating levels of total cholesterol, triglycerides and transaminases and simultaneously low levels of albumin and hemoglobin. Multivariable regression analyses adjusted for age, sex, prior TB, hemoglobin levels and acid-fast bacilli ≥2+ in sputum smears, demonstrated that presence of prediabetes or diabetes in TB patients was associated with increased odds of having 3 pulmonary lesion types (p = 0.003 and p < 0.01 respectively) or ≥ 4 lesions (p = 0.001 and p = 0.01 respectively). CONCLUSION: Hyperglycemia (both DM and prediabetes) significantly affected the presentation of radiographic manifestations and the number of lesions in pulmonary TB patients as well as the biochemical profile in peripheral blood.

Activation of TRPV1 channel antagonizes diabetic nephropathy through inhibiting endoplasmic reticulum-mitochondria contact in podocytes.

The impairment of podocyte protein filtration function caused by excessive mitochondrial calcium intake is a critical feature of diabetic nephropathy (DN). Ca2+ channel transient receptor potential cation channel subfamily V member 1 (TRPV1) has been reported to protect against ischemia-reperfusion induced acute renal injury, but there is no report about its role in DN. Here, we report that dietary capsaicin potently inhibits and reverses chronic renal structural and functional damages in db/db or streptozotocin (STZ)-induced diabetic mice in a TRPV1-dependent manner. Activation of TRPV1 by capsaicin alleviated hyperglycemia-induced mitochondrial dysfunction in podocytes, accompanied by reduced mitochondria-associated membranes (MAMs) formation and fewer Ca2+ transport from endoplasmic reticulum (ER) to mitochondria. Mechanistically, TRPV1-mediated transient Ca2+ influx activated 5' AMP-activated protein kinase (AMPK) that reduced the transcription of Fundc1, a key molecule participating in MAMs formation. Inhibition of AMPK or overexpression of Fundc1 obviously blocked the inhibitory effect of capsaicin on MAMs formation and functional decline in podocytes. These findings emphasize the critical role of mitochondrial Ca2+ homeostasis in the maintenance of normal renal function and suggest an effective intervention method to counteract DN.

Identification of hyperglycemia-associated microbiota alterations in saliva and gingival sulcus.

Oral microbes are a contributing factor to hyperglycemia by inducing an increase in insulin resistance resulting in uncontrolled blood glucose levels. However, the relationship between the distribution of oral flora and hyperglycemia is still controversial. Combining the power of MALDI-Biotyper with anaerobic bacterial culture, this study explores the correlation between anaerobic bacteria in the oral cavity and blood glucose levels. The results demonstrated that altered blood glucose levels contributed to a varied bacterial distribution in the oral cavity. Specifically, Veillonella spp. and Prevotella spp. were identified in a higher proportion in people with elevated blood glucose levels. Six bacterial species identified in this study (Prevotella melaninogenica, Campylobacter rectus, Streptococcus gordonii, Streptococcus mitis, Streptococcus salivarius, and Veillonella parvula) not only demonstrated a positive association with higher blood glucose levels, but also likely contribute to the development of the condition. The data demonstrated MALDI-TOF MS to be a simpler, faster, and more economical clinical identification tool that provides clarity and depth to the research on blood glucose and oral microbiota.

Polysaccharide from Rosa roxburghii Tratt Fruit Attenuates Hyperglycemia and Hyperlipidemia and Regulates Colon Microbiota in Diabetic db/db Mice.

This study was aimed at investigating the hypoglycemic and hypolipidemic effects of a polysaccharide (RTFP) isolated from Rosa roxburghii Tratt fruit on type-2 diabetic db/db mice. The results indicated that the oral administration of RTFP could significantly decrease the body weight, fat, and liver hypertrophy and the levels of fasting blood glucose, serum insulin, and serum lipids of the db/db mice. Histopathological observation showed that RTFP could effectively protect the pancreas, liver, and epididymal fat against damage and dysfunction. Real-time quantitative polymerase chain reaction analysis confirmed that the gene expression levels of peroxisome proliferator-activated receptors-γ (PPAR-γ), sterol regulatory element-binding protein-1 (SREBP-1c), acetyl-CoA carboxylase-1 (ACC-1), fatty acid synthase (FAS), and glucose-6-phosphatase (G6 Pase) were significantly down-regulated in the liver of db/db mice after treatment with RTFP. Moreover, RTFP treatment reversed gut dysbiosis by lowering the Firmicutes-to-Bacteroidetes ratio and enhancing the relative abundances of beneficial bacteria including Bacteroidaceae, Bacteroidaceae S24-7 group, and Lactobacillaceae. These findings suggest that RTFP can be used as a promising functional supplement for the prevention and treatment of type-2 diabetes mellitus.

The Intracellular Growth of M. tuberculosis Is More Associated with High Glucose Levels Than with Impaired Responses of Monocytes from T2D Patients.

Diabetes mellitus, a metabolic disease characterized by hyperglycemia and poor glucose control, is a risk factor for Mycobacterium tuberculosis (M. tuberculosis) infection and the development of active tuberculosis. To evaluate whether M. tuberculosis infection susceptibility is associated with an intrinsic factor in monocytes from type 2 diabetes (T2D) patients or it is associated with hyperglycemia per se, we analyzed TLR-2 and TLR-4 expression by flow cytometry and the cytokines IL-1ß, IL-6, IL-8, IL-10, and TNF-α by cytometric bead array assays, either stimulated with TLR-2 and TLR-4 ligands or infected with M. tuberculosis in the whole blood from T2D patients (n = 43) and healthy subjects (n = 26) or in CD14+ monocytes from healthy subjects cultured in high glucose (HG) (30 mM). The intracellular growth of M. tuberculosis was evaluated by CFU counts at 0, 1, and 3 days in both monocytes from T2D patients and monocytes from healthy subjects cultured in HG. We did not find significant differences in TLR expression, cytokine production, or growth of M. tuberculosis in monocytes from T2D patients compared with those in monocytes from healthy subjects. Despite these results, in vitro assays of monocytes cultured with 30 mM glucose led to significantly increased TLR-2 and TLR-4 basal expression compared to those of monocytes cultured with 11 mM glucose (P < 0.05). Conversely, the production of IL-6 by TLR-2 ligand stimulation, of IL-1ß, IL-6, and IL-8 by TLR-4 ligand stimulation, and of IL-8 by M. tuberculosis infection significantly decreased in monocytes cultured in HG (P < 0.05). Additionally, the intracellular survival of M. tuberculosis increased in monocytes in HG after day 3 of culture (P < 0.05). In conclusion, HG decreased IL-8 production and the intracellular growth control of M. tuberculosis by monocytes, supporting the hypothesis that hyperglycemia plays an important role in the impaired immune responses to M. tuberculosis in patients with T2D.

Amelioration of metabolic syndrome by metformin associates with reduced indices of low-grade inflammation independently of the gut microbiota.

Metformin beneficially impacts several aspects of metabolic syndrome including dysglycemia, obesity, and liver dysfunction, thus making it a widely used frontline treatment for early-stage type 2 diabetes, which is associated with these disorders. Several mechanisms of action for metformin have been proposed, including that it acts as an anti-inflammatory agent, possibly as a result of its impact on intestinal microbiota. In accord with this possibility, we observed herein that, in mice with diet-induced metabolic syndrome, metformin impacts the gut microbiota by preventing its encroachment upon the host, a feature of metabolic syndrome in mice and humans. However, the ability of metformin to beneficially impact metabolic syndrome in mice was not markedly altered by reduction or elimination of gut microbiota, achieved by the use of antibiotics or germfree mice. Although reducing or eliminating microbiota by itself suppressed diet-induced dysglycemia, other features of metabolic syndrome including obesity, hepatic steatosis, and low-grade inflammation remained suppressed by metformin in the presence or absence of gut microbiota. These results support a role for anti-inflammatory activity of metformin, irrespective of gut microbiota, in driving some of the beneficial impacts of this drug on metabolic syndrome.

Polyphenol-Rich Extracts from Brown Macroalgae Lessonia trabeculate Attenuate Hyperglycemia and Modulate Gut Microbiota in High-Fat Diet and Streptozotocin-Induced Diabetic Rats.

Brown macroalgae are an important source of polyphenols with multiple health functions. In this work, polyphenol extracts from Lessonia trabeculate were purified and investigated for the antidiabetic activity in vitro and in vivo. The purified polyphenol extracts exhibited good antioxidant activities, α-glucosidase and lipase inhibition activities (IC50 < 0.25 mg/mL). The HPLC-DAD-ESI-MS/MS analysis indicated that the compounds in polyphenol extracts were mainly phlorotannin derivatives, phenolic acid derivatives, and gallocatechin derivatives. In vivo, C57BL/6J rats treated with polyphenol extracts for 4 weeks had lower fasting blood glucose levels, insulin levels, as well as better serum lipid profiles and antioxidant stress parameters, compared with the diabetic control (DC) group. Histopathology revealed that polyphenol extracts preserved the architecture and function of the liver. Short-chain fatty acid contents in rats' fecal samples with polyphenols administration were significantly recovered as compared with the DC group. Furthermore, the gut microflora of rats was investigated with high-throughput 16S rRNA gene sequencing and results indicated that polyphenol extracts had a positive effect on regulating the dysbiosis of the microbial ecology in diabetic rats. All of the results from the study provided a scientific reference of the potentially beneficial effects of L. trabeculate polyphenols on diabetes management.

Resveratrol-mediated glycemic regulation is blunted by curcumin and is associated to modulation of gut microbiota.

The polyphenols resveratrol (RSV) and curcumin (Cur) are phytoalexines and natural antibiotics with numerous pharmacological functions and metabolic impacts. Recent evidences show a broad control of gut microbiota by polyphenols which could influence glycemic regulation. The aim of this work is to estimate the respective effect of RSV and Cur alone or in association on the control of glycemia and on gut microbiota. A 5-week chronic treatment of hyperglycemic mice with RSV and/or Cur resulted in a differential effect on glucose tolerance test and modified gut microbiome. We precisely identified groups of bacteria representing a specific signature of the glycemic effect of RSV. Inferred metagenomic analysis and metabolic pathway prediction showed that the sulfur and branched-chain amino-acid (BCAA) metabolic activities are tightly correlated with the efficacy of RSV for the control of glycaemia. The impact on BCAA metabolism was further validated by serum metabolomics analysis. Altogether, we show that polyphenols specifically impact gut microbiota and corresponding metabolic functions which could be responsible for their therapeutic role.

Response of gut microbiota in type 2 diabetes to hypoglycemic agents.

PURPOSE: Accumulated evidence has indicated that the gut microbiome affected the pharmacology of anti-diabetic agents, and their metabolic products induced by the agents transformed the structure of gastrointestinal microbiota in return. However, the studies around heredity, ethnicity, or living condition, referring to human microbiome were mostly represented by an occidental pattern partial and rare studies that focused on the effect of several first-line hypoglycemic agents on the gut flora in a single medical center. Therefore, we aimed to explore the interaction between gut microbiome and type 2 diabetes (T2D) or hypoglycemics in Chinese population. METHODS: A total of 130 T2D patients with a specific hypoglycemic treatment and 50 healthy volunteers were enrolled in this study. Gut microbiome compositons were analyzed by 16S ribosomal RNA gene-based sequencing protocol. RESULTS: Hypoglycemic agents contributed to the alteration of specific species in gut bacteria rather than its total diversity. Metformin increased the abundance of Spirochaete, Turicibacter, and Fusobacterium. Insulin also increased Fusobacterium, and α-glucosidase inhibitors (α-GIs) contributed to the plentitude of Bifidobacterium and Lactobacillus. Both metformin and insulin improved taurine and hypotaurine metabolism, and α-GI promoted several amino acid pathways. Although the community of gut microbiota with metformin and insulin showed similarity, significant differences were available in each diabetic group with hypoglycemia. CONCLUSIONS: Gut microbiota is significantly associated with anti-diabetic agents. The gut microbiome and metabolism have shown respective characteristics in different T2D groups, which were also significantly different from the healthy group. This study provides some new insights for identification and exploration of the pathogenesis of T2D.