Nutrient control of energy homeostasis via gut-brain neural circuits

Multi-target regulation of intestinal microbiota by berberine to improve type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) and its complications are major public health problems that seriously affect the quality of human life. The modification of intestinal microbiota has been widely recognized for the management of diabetes. The relationship between T2DM, intestinal microbiota, and active ingredient berberine (BBR) in intestinal microbiota was reviewed in this paper. First of all, the richness and functional changes of intestinal microbiota disrupt the intestinal environment through the destruction of the intestinal barrier and fermentation/degradation of pathogenic/protective metabolites, targeting the liver, pancreas, visceral adipose tissue (VAT), etc., to affect intestinal health, blood glucose, and lipids, insulin resistance and inflammation. Then, we focus on BBR, which protects the composition of intestinal microbiota, the changes of intestinal metabolites, and immune regulation disorder of the intestinal environment as the therapeutic mechanism as well as its current clinical trials. Further research can analyze the mechanism network of BBR to exert its therapeutic effect according to its multi-target compound action, to provide a theoretical basis for the use of different phytochemical components alone or in combination to prevent and treat T2DM or other metabolic diseases by regulating intestinal microbiota.

Dietary fiber-derived short-chain fatty acids: A potential therapeutic target to alleviate obesity-related nonalcoholic fatty liver disease

Over the past several decades, increasing global prevalence of obesity-related nonalcoholic fatty liver disease (NAFLD) has been one of main challenges to human health. Recently, increasing evidence has validated connections among short chain fatty acids (SCFAs), a physiologically relevant concentration, the intestinal microbiota, and host metabolism. In this review, we summarized crosstalk between SCFAs and host metabolism in relation to NAFLD pathophysiology, focusing on recent advances. Firstly, how SCFAs are generated and absorbed under different nutritional conditions in the gut. Secondly, how SCFAs maintain gut barrier and alleviate hepatic inflammatory responses. Thirdly, how SCFAs maintain hepatic energy balance through controlling appetite and mediating the glucose homeostasis at the systemic level. Fourthly, G-protein-coupled receptors (GPRs) are widely involved in the above metabolic processes regulated by SCFAs. Overall, this review aimed to provide new insights into the prospects of SCFAs as a potential therapeutic target in management of liver diseases.

Effects of Nondigestible Oligosaccharides on Obesity

Obesity is a major public health concern that has almost reached the level of pandemic and is rapidly progressing. The gut microbiota has emerged as a crucial regulator involved in the etiology of obesity, and the manipulation of it by dietary intervention has been widely used for reducing the risk of obesity. Nondigestible oligosaccharides (NDOs) are attracting increasing interests as prebiotics, as the indigestible ingredients can induce compositional or metabolic improvement to the gut microbiota, thereby improving gut health and giving rise to the production of short-chain fatty acids (SCFAs) to elicit metabolic effects on obesity. In this review, the role NDOs play in obesity intervention via modification of the gut microecology, as well as the physicochemical and physiological properties and industrial manufacture of NDOs, is discussed. Our goal is to provide a critical assessment of and stimulate comprehensive research into NDO use in obesity.

Management of Five Hundred Patients With Gut Failure at a Single Center: Surgical Innovation Versus Transplantation With a Novel Predictive Model

OBJECTIVE(S)

To define the evolving role of integrative surgical management including transplantation for patients gut failure (GF).

METHODS

A total of 500 patients with total parenteral nutrition-dependent catastrophic and chronic GF were referred for surgical intervention particularly transplantation and comprised the study population. With a mean age of 45 ± 17 years, 477 (95%) were adults and 23 (5%) were children. Management strategy was guided by clinical status, splanchnic organ functions, anatomy of residual gut, and cause of GF. Surgery was performed in 462 (92%) patients and 38 (8%) continued medical treatment. Definitive autologous gut reconstruction (AGR) was achievable in 378 (82%), primary transplant in 42 (9%), and AGR followed by transplant in 42 (9%). The 84 transplant recipients received 94 allografts; 67 (71%) liver-free and 27 (29%) liver-contained. The 420 AGR patients received a total of 790 reconstructive and remodeling procedures including primary reconstruction, interposition alimentary-conduits, intestinal/colonic lengthening, and reductive/decompressive surgery. Glucagon-like peptide-2 was used in 17 patients.

RESULTS

Overall patient survival was 86% at 1-year and 68% at 5-years with restored nutritional autonomy (RNA) in 63% and 78%, respectively. Surgery achieved a 5-year survival of 70% with 82% RNA. AGR achieved better long-term survival and transplantation better (P = 0.03) re-established nutritional autonomy. Both AGR and transplant were cost effective and quality of life better improved after AGR. A model to predict RNA after AGR was developed computing anatomy of reconstructed gut, total parenteral nutrition requirements, cause of GF, and serum bilirubin.

CONCLUSIONS

Surgical integration is an effective management strategy for GF. Further progress is foreseen with the herein-described novel techniques and established RNA predictive model.

Dietary compounds and traditional Chinese medicine ameliorate type 2 diabetes by modulating gut microbiota

Diabetes mellitus (DM) and its complications are major public health concerns which strongly influence the quality of humans' life. Modification of gut microbiota has been widely used for the management of diabetes. In this review, the relationship between diabetes and gut microbiota, as well as the effects of different dietary components and traditional Chinese medicine (TCM) on gut microflora are summarized. Dietary compounds and TCM possessing bioactive components (fiber and phytochemicals) first change the composition of gut microbiota (inhibiting pathogens and promoting the beneficial bacteria growth) and then influence the production of their metabolites, which would further modify the intestinal environment through inhibiting the production of detrimental compounds (such as lipopolysaccharide, hydrogen sulfide, indol, etc.). Importantly, metabolites (short chain fatty acids and other bioactive components) fermented/degraded by gut microbiota can target multiple pathways in intestine, liver, pancreas, etc., resulting in the improvement of gut health, glycemic control, lipids profile, insulin resistance and inflammation. Furthermore, understanding the interaction between different dietary components and gut microbiota, as well as underlying mechanisms would help design different diet formula for the management of diabetes. Further researches could focus on the combination of different dietary components for preventing and treating diabetes, based on the principle of "multiple components against multiple targets" from the perspective of gut microbiota.

Gut as an emerging organ for the treatment of diabetes: focus on mechanism of action of bariatric and endoscopic interventions

Increasing worldwide prevalence of type 2 diabetes mellitus and its accompanying pathologies such as obesity, arterial hypertension and dyslipidemia represents one of the most important challenges of current medicine. Despite intensive efforts, high percentage of patients with type 2 diabetes does not achieve treatment goals and struggle with increasing body weight and poor glucose control. While novel classes of antidiabetic medications such as incretin-based therapies and gliflozins have some favorable characteristics compared to older antidiabetics, the only therapeutic option shown to substantially modify the progression of diabetes or to achieve its remission is bariatric surgery. Its efficacy in the treatment of diabetes is well established, but the exact underlying modes of action are still only partially described. They include restriction of food amount, enhanced passage of chymus into distal part of small intestine with subsequent modification of gastrointestinal hormones and bile acids secretion, neural mechanisms, changes in gut microbiota and many other possible mechanisms underscoring the importance of the gut in the regulation of glucose metabolism. In addition to bariatric surgery, less-invasive endoscopic methods based on the principles of bariatric surgery were introduced and showed promising results. This review highlights the role of the intestine in the regulation of glucose homeostasis focusing on the mechanisms of action of bariatric and especially endoscopic methods of the treatment of diabetes. A better understanding of these mechanisms may lead to less invasive endoscopic treatments of diabetes and obesity that may complement and widen current therapeutic options.

Roux-en-Y Gastric Bypass Surgery Suppresses Hepatic Gluconeogenesis and Increases Intestinal Gluconeogenesis in a T2DM Rat Model

BACKGROUND

Roux-en-Y gastric bypass (RYGB) is an effective surgical treatment for type 2 diabetes mellitus (T2DM). The present study aimed to investigate the effects of RYGB on glucose homeostasis, lipid metabolism, and intestinal morphological adaption, as well as hepatic and intestinal gluconeogenesis.

METHODS

Twenty adult male T2DM rats induced by high-fat diet and low dose of streptozotocin were randomly divided into sham and RYGB groups. The parameters of body weight, food intake, glucose tolerance, insulin sensitivity, and serum lipid profiles were assessed to evaluate metabolic changes. Intestinal sections were stained with hematoxylin and eosin (H&E) for light microscopy examination. The messenger RNA (mRNA) and protein expression levels of key regulatory enzymes of gluconeogenesis [phosphoenolpyruvate carboxykinase (PEPCK), glucose-6-phosphatase (G6Pase)] were determined through reverse-transcription PCR (RT-PCR) and Western blotting, respectively.

RESULTS

RYGB induced significant improvements in glucose tolerance and insulin sensitivity, along with weight loss and decreased food intake. RYGB also decreased serum triglyceride (TG) and free fatty acid (FFA) levels. The jejunum and ileum exhibited a marked increase in the length and number of intestinal villi after RYGB. The RYGB group exhibited downregulated mRNA and protein expression levels of PEPCK and G6Pase in the liver and upregulated expression of these enzymes in the jejunum and ileum tissues.

CONCLUSIONS

RYGB ameliorates glucose and lipid metabolism accompanied by weight loss and calorie restriction. The small intestine shows hyperplasia and hypertrophy after RYGB. Meanwhile, our study demonstrated that the reduced hepatic gluconeogenesis and increased intestinal gluconeogenesis may contribute to improved glucose homeostasis after RYGB.

Probiotics, prebiotics, synbiotics and insulin sensitivity

Animal studies indicate that the composition of gut microbiota may be involved in the progression of insulin resistance to type 2 diabetes. Probiotics and/or prebiotics could be a promising approach to improve insulin sensitivity by favourably modifying the composition of the gut microbial community, reducing intestinal endotoxin concentrations and decreasing energy harvest. The aim of the present review was to investigate the effects of probiotics, prebiotics and synbiotics (a combination of probiotics and prebiotics) on insulin resistance in human clinical trials and to discuss the potential mechanisms whereby probiotics and prebiotics improve glucose metabolism. The anti-diabetic effects of probiotics include reducing pro-inflammatory cytokines via a NF-κB pathway, reduced intestinal permeability, and lowered oxidative stress. SCFA play a key role in glucose homeostasis through multiple potential mechanisms of action. Activation of G-protein-coupled receptors on L-cells by SCFA promotes the release of glucagon-like peptide-1 and peptide YY resulting in increased insulin and decreased glucagon secretion, and suppressed appetite. SCFA can decrease intestinal permeability and decrease circulating endotoxins, lowering inflammation and oxidative stress. SCFA may also have anti-lipolytic activities in adipocytes and improve insulin sensitivity via GLUT4 through the up-regulation of 5'-AMP-activated protein kinase signalling in muscle and liver tissues. Resistant starch and synbiotics appear to have favourable anti-diabetic effects. However, there are few human interventions. Further well-designed human clinical studies are required to develop recommendations for the prevention of type 2 diabetes with pro- and prebiotics.

Gut microbial degradation of organophosphate insecticides-induces glucose intolerance via gluconeogenesis

BACKGROUND

Organophosphates are the most frequently and largely applied insecticide in the world due to their biodegradable nature. Gut microbes were shown to degrade organophosphates and cause intestinal dysfunction. The diabetogenic nature of organophosphates was recently reported but the underlying molecular mechanism is unclear. We aimed to understand the role of gut microbiota in organophosphate-induced hyperglycemia and to unravel the molecular mechanism behind this process.

RESULTS

Here we demonstrate a high prevalence of diabetes among people directly exposed to organophosphates in rural India (n = 3080). Correlation and linear regression analysis reveal a strong association between plasma organophosphate residues and HbA1c but no association with acetylcholine esterase was noticed. Chronic treatment of mice with organophosphate for 180 days confirms the induction of glucose intolerance with no significant change in acetylcholine esterase. Further fecal transplantation and culture transplantation experiments confirm the involvement of gut microbiota in organophosphate-induced glucose intolerance. Intestinal metatranscriptomic and host metabolomic analyses reveal that gut microbial organophosphate degradation produces short chain fatty acids like acetic acid, which induces gluconeogenesis and thereby accounts for glucose intolerance. Plasma organophosphate residues are positively correlated with fecal esterase activity and acetate level of human diabetes.

CONCLUSION

Collectively, our results implicate gluconeogenesis as the key mechanism behind organophosphate-induced hyperglycemia, mediated by the organophosphate-degrading potential of gut microbiota. This study reveals the gut microbiome-mediated diabetogenic nature of organophosphates and hence that the usage of these insecticides should be reconsidered.

Oat bran β-glucan improves glucose homeostasis in mice fed on a high-fat diet

The changes of body weight (A) and food intake (B) of mice fed on different diets of low-fat (LF), high-fat (HF), HF + grain form β-glucan (HFGF), and HF + extracted β-glucan (HFEX).

Management of Crohn's Disease in the New Era of Gut Rehabilitation and Intestinal Transplantation

Despite recent therapeutic advances, patients with Crohn's disease (CD) continue to experience high recurrence with cumulative structural damage and ultimate loss of nutritional autonomy. With short bowel syndrome, strictures, and enteric fistulae being the underlying pathology, CD is the second common indication for home parenteral nutrition (HPN). With development of intestinal failure, nutritional management including HPN is required as a rescue therapy. Unfortunately, some patients do not escape the HPN-associated complications. Therefore, the concept of gut rehabilitation has evolved as part of the algorithmic management of these patients, with transplantation being the ultimate life-saving therapy. With type 2 intestinal failure, comprehensive rehabilitative measures including nutritional care, pharmacologic manipulation, autologous reconstruction, and bowel lengthening is often successful, particularly in patients with quiescent disease. With type 3 intestinal failure, transplantation is the only life-saving treatment for patients with HPN failure and intractable disease. With CD being the second common indication for transplantation in adults, survival outcome continues to improve because of surgical innovation, novel immunosuppression, and better postoperative care. Despite being a rescue therapy, the procedure has achieved survival rates similar to other solid organs, and comparable to those who continue to receive HPN therapy. With similar technical, immunologic, and infectious complications, survival is similar in the CD and non-CD recipients. Full nutritional autonomy is achievable in most survivors with better quality of life and long-term cost-effectiveness. CD recurrence is rare with no impact on graft function. Further progress is anticipated with new insights into the pathogenesis of CD and mechanisms of transplant tolerance.

Reshaping the gut microbiota: Impact of low calorie sweeteners and the link to insulin resistance?

Disruption in the gut microbiota is now recognized as an active contributor towards the development of obesity and insulin resistance. This review considers one class of dietary additives known to influence the gut microbiota that may predispose susceptible individuals to insulin resistance - the regular, long-term consumption of low-dose, low calorie sweeteners. While the data are controversial, mounting evidence suggests that low calorie sweeteners should not be dismissed as inert in the gut environment. Sucralose, aspartame and saccharin, all widely used to reduce energy content in foods and beverages to promote satiety and encourage weight loss, have been shown to disrupt the balance and diversity of gut microbiota. Fecal transplant experiments, wherein microbiota from low calorie sweetener consuming hosts are transferred into germ-free mice, show that this disruption is transferable and results in impaired glucose tolerance, a well-known risk factor towards the development of a number of metabolic disease states. As our understanding of the importance of the gut microbiota in metabolic health continues to grow, it will be increasingly important to consider the impact of all dietary components, including low calorie sweeteners, on gut microbiota and metabolic health.

The Intestinal Microbiota in Metabolic Disease

Gut bacteria exert beneficial and harmful effects in metabolic diseases as deduced from the comparison of germfree and conventional mice and from fecal transplantation studies. Compositional microbial changes in diseased subjects have been linked to adiposity, type 2 diabetes and dyslipidemia. Promotion of an increased expression of intestinal nutrient transporters or a modified lipid and bile acid metabolism by the intestinal microbiota could result in an increased nutrient absorption by the host. The degradation of dietary fiber and the subsequent fermentation of monosaccharides to short-chain fatty acids (SCFA) is one of the most controversially discussed mechanisms of how gut bacteria impact host physiology. Fibers reduce the energy density of the diet, and the resulting SCFA promote intestinal gluconeogenesis, incretin formation and subsequently satiety. However, SCFA also deliver energy to the host and support liponeogenesis. Thus far, there is little knowledge on bacterial species that promote or prevent metabolic disease. Clostridium ramosum and Enterococcus cloacae were demonstrated to promote obesity in gnotobiotic mouse models, whereas bifidobacteria and Akkermansia muciniphila were associated with favorable phenotypes in conventional mice, especially when oligofructose was fed. How diet modulates the gut microbiota towards a beneficial or harmful composition needs further research. Gnotobiotic animals are a valuable tool to elucidate mechanisms underlying diet–host–microbe interactions.

Neuroendocrine adaptations to bariatric surgery

The global epidemic of obesity and its related disease in combination with robust physiological defence of intentional weight loss generates a pressing need for effective weight loss therapies. Bariatric surgery, which works very effectively at delivering substantial sustained weight loss, has been an enigma with respect to mechanism of action. Naive concepts of restriction and malabsorption do not explain the efficacy of the most commonly used bariatric procedures. This century has seen increased interest in unravelling the mystery of the mechanisms underlying surgery associated weight loss with a focus on integrative gastrointestinal (GI) physiology, gut-brain signalling, and beyond weight loss effects on metabolism. GI interventions, some very minor, can alter GI wall stretch and pressure receptors; a range of GI hormones affecting hunger and satiety; bile acid metabolism and signalling; the characteristics of GI microbiome; portal vein nutrient sensing; and circulating concentrations of amino acids. Understanding the mechanisms involved should present targets for less invasive effective therapies.