Gut Microbiota of Obese, Type 2 Diabetic Individuals is Enriched in Faecalibacterium prausnitzii, Akkermansia muciniphila and Peptostreptococcus anaerobius after Weight Loss.

BACKGROUND: Beside the influence of nutritional habits and reduced physical activity, metabolic syndrome is associated with alterations in the structure of gut microbiota influencing the inflammatory immune responses. Gut microbiota and microbial metabolic activities are known to affect the lipid and glucose metabolism, satiety and chronic low-grade inflammation in the metabolic syndrome. The aim of the study was to identify genera or even species affecting host metabolism in obesity and type 2 diabetes beside the common used indicator: Firmicutes/ Bacteroidetes ratio. METHODS: Differences in gut microbiota were investigated in three groups of subjects over a four month intervention period: type 2 diabetics under GLP1-Agonist therapy, obese individuals without established insulin resistance, both receiving nutritional counseling concerning weight reduction, and a lean control group. Collection of fecal samples was accomplished at two time points, before treatment, and after four months of treatment. For identification of bacteria at species-level we used 454 high-throughput sequencing and fragment length polymorphism analysis based on IS-pro (Intergenic-Spacer-profiling). Five bacterial species, two bacterial genera, total bacterial abundance, and the Firmicutes/Bacteroidetes ratio were determined. RESULTS: Type 2 diabetics showed a higher Firmicutes/Bacteroidetes ratio even with an increase to the second time point (p=0.07). The abundance of B. thetaiotaomicron remained unaffected, whereas B. vulgatus significantly increased in type 2 diabetics (p=0.07) over the study period. Either Alistipes spp. showed an increase in type 2 diabetics between the time points (p=0.06). The abundance of F. prausnitzii (p=0.03) and A. muciniphila (p=0.03) also increased in type 2 diabetics over study period. In addition, the concentration of P. anaerobius (p=0.03) was significantly higher in type 2 diabetics after intervention compared to lean and obese controls. CONCLUSION: Our results clearly show a difference in the gut bacterial composition in type 2 diabetics compared to lean controls or obesity. Therefore, the ratio of Fimicutes/Bacteroidetes might only be an indicator, but a detailed view at species level is even more important in regard to distinction of their functions.

Interleukin-6 CpG Methylation and Body Weight Correlate Differently in Type 2 Diabetes Patients Compared to Obese and Lean Controls.

BACKGROUND/AIMS: Diabetes mellitus type 2 (DMT2) is accompanied by systemic low-grade inflammation with elevated levels of interleukin-6 (IL-6), which is encoded by a gene (IL-6) previously shown to be regulated by DNA methylation. We investigated seven CpG sites in IL-6 in individuals with DMT2, obese individuals and lean controls. Further, the DMT2 group received the glucagon-like peptide 1 agonist liraglutide. METHODS: Blood samples were taken at the beginning of the study and after 4 months. The DNA methylation was assessed using pyrosequencing. RESULTS: Methylation levels at the CpG sites -664, -628 and +13 at the first sampling time point (T1) and at -666 and -664 at the second sampling time point (T2) correlated negatively with initial body weight in the DMT2 group. We found positive correlations for the obese and the lean control group. In the obese group, CpG +27 methylation at T1 correlated with initial body weight (r = 0.685; p = 0.014). In the lean group, CpG -664 at T1 (r = 0.874; p = 0.005) and CpG -628 at T2 (r = 0.632; p = 0.050) correlated with initial body weight. CONCLUSION: These findings are an informative basis for further studies to elucidate epigenetic mechanisms underlying DMT2. Additionally, our results might provide starting points for the development of biomarkers for prevention and therapy strategies.

Obesity: epigenetic regulation ­ recent observations.

Genetic and environmental factors, especially nutrition and lifestyle, have been discussed in the literature for their relevance to epidemic obesity. Gene-environment interactions may need to be understood for an improved understanding of the causes of obesity, and epigenetic mechanisms are of special importance. Consequences of epigenetic mechanisms seem to be particularly important during certain periods of life: prenatal, postnatal and intergenerational, transgenerational inheritance are discussed with relevance to obesity. This review focuses on nutrients, diet and habits influencing intergenerational, transgenerational, prenatal and postnatal epigenetics; on evidence of epigenetic modifiers in adulthood; and on animal models for the study of obesity.

Helichrysum and Grapefruit Extracts Boost Weight Loss in Overweight Rats Reducing Inflammation.

Obesity is characterized by an increased production of inflammatory markers. High levels of circulating free fatty acids and chronic inflammation lead to increased oxidative stress, contributing to the development of insulin resistance (IR). Recent studies have focused on the potential use of flavonoids for obesity management due to their antioxidant and anti-inflammatory properties. This study was designed to investigate the antioxidant and anti-inflammatory effects of helichrysum and grapefruit extracts in overweight insulin-resistant rats. Thirty-eight male Wistar rats were randomly distributed in two groups: control group (n=8) and high-fat sucrose (HFS) group (n=30). After 22 days of ad libitum water and food access, the rats fed HFS diet changed to standard diet and were reassigned into three groups (n=10 each group): nonsupplemented, helichrysum extract (2 g/kg bw), and grapefruit extract (1 g/kg bw) administered for 5 weeks. Rats supplemented with both extracts gained less body weight during the 5-week period of treatment, showed lower serum insulin levels and liver TBARS levels. Leptin/adiponectin ratio, as an indicator of IR, was lower in both extract-administered groups. These results were accompanied by a reduction in TNFα gene expression in epididymal adipose tissue and intestinal mucosa, and TLR2 expression in intestinal mucosa. Helichrysum and grapefruit extracts might be used as complement hypocaloric diets in weight loss treatment. Both extracts helped to reduce weight gain, hyperinsulinemia, and IR, improved inflammation markers, and decreased the HFS diet-induced oxidative stress in insulin-resistant rats.

Modulation of hyperglycemia and TNFα-mediated inflammation by helichrysum and grapefruit extracts in diabetic db/db mice.

Type-2 diabetes is associated with a chronic low-grade systemic inflammation accompanied by an increased production of adipokines/cytokines by obese adipose tissue. The search for new antidiabetic drugs with different mechanisms of action, such as insulin sensitizers, insulin secretagogues and α-glucosidase inhibitors, has directed the focus on the potential use of flavonoids in the management of type-2 diabetes. Thirty six diabetic male C57BL/6J db/db mice were fed a standard diet and randomly assigned into four experimental groups: non-treated control, (n = 8); acarbose (5 mg per kg bw, n = 8); helichrysum (1 g per kg bw, n = 10) and grapefruit (0.5 g per kg bw, n = 10) for 6 weeks. The mRNA expression in pancreas, liver and epididymal adipose tissue was determined by RT-PCR. DNA methylation was quantified in epididymal fat using pyrosequencing. Mice supplemented with helichrysum and grapefruit extracts showed a significant decrease in fasting glucose levels (p < 0.05). A possible mechanism of action could be the up-regulation of liver glucokinase (p < 0.05). The antihyperglycemic effect of both extracts was accompanied by decreased mRNA expression of some proinflammatory genes (monocyte chemotactic protein-1, tumor necrosis factor-α, cyclooxygenase-2, nuclear factor-kappaB) in the liver and epididymal adipose tissue. The CpG3 site of TNFα, located 5 bp downstream of the transcription start site, showed increased DNA methylation in the grapefruit group compared with the non-treated group (p < 0.01). In conclusion, helichrysum and grapefruit extracts improved hyperglycemia through the regulation of glucose metabolism in the liver and reduction of the expression of proinflammatory genes in the liver and visceral fat. The hypermethylation of TNFα in adipose tissue may contribute to reduce the inflammation associated with diabetes and obesity.

Effects of short chain fatty acid producing bacteria on epigenetic regulation of FFAR3 in type 2 diabetes and obesity.

The human gut microbiota and microbial influences on lipid and glucose metabolism, satiety, and chronic low-grade inflammation are known to be involved in metabolic syndrome. Fermentation end products, especially short chain fatty acids, are believed to engage the epigenetic regulation of inflammatory reactions via FFARs (free fatty acid receptor) and other short chain fatty acid receptors. We studied a potential interaction of the microbiota with epigenetic regulation in obese and type 2 diabetes patients compared to a lean control group over a four month intervention period. Intervention comprised a GLP-1 agonist (glucagon-like peptide 1) for type 2 diabetics and nutritional counseling for both intervention groups. Microbiota was analyzed for abundance, butyryl-CoA:acetate CoA-transferase gene and for diversity by polymerase chain reaction and 454 high-throughput sequencing. Epigenetic methylation of the promoter region of FFAR3 and LINE1 (long interspersed nuclear element 1) was analyzed using bisulfite conversion and pyrosequencing. The diversity of the microbiota as well as the abundance of Faecalibacterium prausnitzii were significantly lower in obese and type 2 diabetic patients compared to lean individuals. Results from Clostridium cluster IV and Clostridium cluster XIVa showed a decreasing trend in type 2 diabetics in comparison to the butyryl-CoA:acetate CoA-transferase gene and according to melt curve analysis. During intervention no significant changes were observed in either intervention group. The analysis of five CpGs in the promoter region of FFAR3 showed a significant lower methylation in obese and type 2 diabetics with an increase in obese patients over the intervention period. These results disclosed a significant correlation between a higher body mass index and lower methylation of FFAR3. LINE-1, a marker of global methylation, indicated no significant differences between the three groups or the time points, although methylation of type 2 diabetics tended to increase over time. Our results provide evidence that a different composition of gut microbiota in obesity and type 2 diabetes affect the epigenetic regulation of genes. Interactions between the microbiota and epigenetic regulation may involve not only short chain fatty acids binding to FFARs. Therefore dietary interventions influencing microbial composition may be considered as an option in the engagement against metabolic syndrome.