Gut microbiota is associated with differential metabolic characteristics: A study on a defined cohort of Africans and Chinese.

Objective: This study intended to determine the associations between gut microbiota and glucose response in healthy individuals and analyze the connection between the gut microbiome and glucose-metabolism-related parameters. Methods: Fecal bacterial composition and anthropometric, body composition, body fat distribution, and biochemical measures were analyzed. A 75-g oral glucose tolerance test (OGTT) was given to each participant to investigate changes in glucagon-like peptide 1 (GLP-1), insulin, and glucose. The whole body fat and the regions of interest of local body composition were analyzed using dual-energy X-ray absorptiometry (DEXA), and gut microbiota composition was assessed through variable regions (V3-V4) of the bacterial 16s ribosomal RNA gene using high-throughput sequencing techniques. Spearman correlation analysis was used to evaluate the association between gut microbiota and clinical and metabolic changes. Results: The number of operational taxonomic units (OTUs) demonstrated a reduction in the diversity and composition of gut microbiota associated with enhanced adiposity, dyslipidemia, insulin resistance, and hyperglycemia. The alpha diversity revealed that microbiota diversity, richness, and composition were higher in the African group and lower in the Chinese group. Principal coordinates analysis (PCoA) plots of beta diversity showed significant variability in gut microbial community structure between the two groups (p = 0.0009). LEfSe analysis showed that phylum Bacteroidetes was significantly more abundant in the Chinese group, and this group also harbored members of the order Bacteroidales, family Bacteroidaceae, and genus Bacteroides. In contrast, the phylum Verrucomicrobia was significantly more prevalent in the African group (all p < 0.05). Concerning species, metastats analysis revealed 8 species in the Chinese group and 18 species in the African group that were significantly abundant. Spearman's correlation analysis demonstrated that gut microbiota correlated with the factors that related to glucose metabolism. Conclusion: Our data suggest that there is an interaction between gut microbiota, host physiology, and glucometabolic pathways, and this could contribute to adiposity and pathophysiology of hyperlipidemia, insulin resistance, and hyperglycemia. These findings provide an important basis for determining the relation between the gut microbiota and the pathogenesis of various metabolic disorders.

DNA 6mA Demethylase ALKBH1 Orchestrates Fatty Acid Metabolism and Suppresses Diet-Induced Hepatic Steatosis.

BACKGROUND & AIMS: Nonalcoholic fatty liver disease (NAFLD) is a major cause of liver-related morbidity and mortality whereas the pathogenic mechanism remains largely elusive. DNA N6-methyladenosine (6mA) modification is a recently identified epigenetic mark indicative of transcription in eukaryotic genomes. Here, we aimed to investigate the role and mechanism of DNA 6mA modification in NAFLD progression. METHODS: Dot blot and immunohistochemistry were used to detect DNA 6mA levels. Liver-specific AlkB homolog 1 (ALKBH1)-knockout mice and mice with ALKBH1 overexpression in liver were subjected to a high-fat diet or methionine choline-deficient diet to evaluate the critical role of ALKBH1-demethylated DNA 6mA modification in the pathogenesis of hepatic steatosis during NAFLD. RNA sequencing and chromatin immunoprecipitation sequencing were performed to investigate molecular mechanisms underlying this process. RESULTS: The DNA 6mA level was increased significantly with hepatic steatosis, while ALKBH1 expression was down-regulated markedly in both mouse and human fatty liver. Deletion of ALKBH1 in hepatocytes increased genomic 6mA levels and accelerated diet-induced hepatic steatosis and metabolic dysfunction. Comprehensive analyses of transcriptome and chromatin immunoprecipitation sequencing data indicated that ALKBH1 directly bound to and exclusively demethylated 6mA levels of genes involved in fatty acid uptake and lipogenesis, leading to reduced hepatic lipid accumulation. Importantly, ALKBH1 overexpression was sufficient to suppress lipid uptake and synthesis, and alleviated diet-induced hepatic steatosis and insulin resistance. CONCLUSIONS: Our findings show an indispensable role of ALKBH1 as an epigenetic suppressor of DNA 6mA in hepatic fatty acid metabolism and offer a potential therapeutic target for NAFLD treatment.

Adding Sodium-Glucose Co-Transporter 2 Inhibitors to Sulfonylureas and Risk of Hypoglycemia: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Background: Hypoglycemia is an important event that could be related to increased mortality in patients with diabetes. The risk of hypoglycemia is not clearly illustrated to increase when Sodiumglucose co-transporter 2 (SGLT-2) inhibitors are used concomitantly with sulfonylureas. The present study will assess the risk of hypoglycemia associated with the concomitant use of SGLT-2 inhibitors and sulfonylureas compared with placebo and sulfonylureas. Method: We searched Medline, EMBASE, Cochrane Central Register of Controlled Trials, and Clinicaltrial.gov and identified the randomized trials comparing SGLT-2 inhibitors with placebo for type 2 diabetes treated with sulfonylureas. The risk of bias in each trial was assessed using the Cochrane tool. The risk ratio of hypoglycemia was measured using the Mantel Haenszel method. We also performed subgroup analysis to examine the dosage effects. The number needed to harm (NNH) was measured according to the duration of intervention. Results: A total of 12 studies, including 3761 participants, were enrolled in our systematic review and meta-analysis. The risk ratio of hypoglycemia was 1.67 (95% CI 1.42 to 1.97). The NNH was 13 (95% CI 9 to 21) for a treatment duration of 24 weeks or less, 11 (8 to 18) for 25 to 48 weeks, and 7 (5 to 10) for more than 48 weeks. Subgroup analysis showed that no difference was found between higher and lower doses of SGLT-2 inhibitors. The risk ratio related to lower dose SGLT-2 inhibitors was 1.56 (95% CI 1.30 to 1.88), and the risk ratio related to higher dose SGLT-2 inhibitors was 1.70 (95% CI 1.42 to 2.04). Conclusions: The risk of hypoglycemia was significantly increased in subjects treated with SGLT-2 inhibitors compared with placebo. Addition of SGLT-2 inhibitors to sulfonylureas would lead to one more case of hypoglycemia in every 13 patients with a treatment duration less than 24 weeks. This suggests that a decrease in sulfonylureas dose may be an important recommendation when adding SGLT-2 inhibitors to sulfonylureas.

Alpha-mangostin attenuates diabetic nephropathy in association with suppression of acid sphingomyelianse and endoplasmic reticulum stress.

AIMS: Diabetic nephropathy is a common complication of diabetes, but there are currently few treatment options. The aim of this study was to gain insight into the effect of alpha-mangostin on diabetic nephropathy and possible related mechanisms. METHODS: Goto-Kakizaki rats were used as a diabetic model and received alpha-mangostin or desipramine treatment with normal saline as a control. Ten age-matched Sprague Dawley rats were used as normal controls and treated with normal saline. At week 12, blood glucose, albuminuria, apoptosis and renal pathologic changes were assessed. Protein levels for acid sphingomyelinase, glucose-regulated protein 78, phosphorylated PKR-like ER-resident kinase, activated transcription factor 4, CCAAT/enhancer-binding protein, homologous protein), and cleaved-caspase12 were measured. RESULTS: The level of acid sphingomyelinase was significantly increased, and ER stress was activated in diabetic rat kidneys when compared to the control animals. When acid sphingomyelinase was inhibited by alpha-mangostin, the expression of ER stress-related proteins was down-regulated in association with decreased levels of diabetic kidney injury. CONCLUSIONS: Alpha-mangostin, an acid sphingomyelinase inhibitor plays a protective role in diabetic neuropathy by relieving ER stress induced-renal cell apoptosis.