Effect of the dietary supplement PERMEAPROTECT+ TOLERANCE© on gut permeability in a human co-culture epithelial and immune cells model

Background and objective

The leaky gut syndrome is characterized by an intestinal hyperpermeability observed in multiple chronic disorders. Alterations of the gut barrier are associated with translocation of bacterial components increasing inflammation, oxidative stress and eventually dysfunctions of cellular interactions at the origin pathologies. Therapeutic and/or preventive approaches have to focus on the identification of novel targets to improve gut homeostasis. In this context, this study aims to identify the role of PERMEAPROTECT + TOLERANE©, known as PERMEA, a food complement composed of a combination of factors (including l-Glutamine) known to improve gut physiology.

Methods

We tested the effects of PERMEA or l-Glutamine alone (as reference) on gut permeability (FITC dextran method, expression of tight junctions) and its inflammatory/oxidative consequences (cytokines and redox assays, RT-qPCR) in a co-culture of human cells (peripheral blood mononuclear cells and intestinal epithelial cells) challenged with TNFα.

Results

PERMEA prevented intestinal hyperpermeability induced by inflammation. This was linked with its antioxidant and immunomodulatory properties showing a better efficacity than l-Glutamine alone on several parameters including permeability, global antioxidant charge and production of cytokines.

Conclusion

PERMEA is more efficient to restore intestinal physiology, reinforcing the concept that combination of food constituents could be used to prevent the development of numerous diseases.

Gut microbiota in overweight and obesity: crosstalk with adipose tissue

Overweight and obesity are characterized by excessive fat mass accumulation produced when energy intake exceeds energy expenditure. One plausible way to control energy expenditure is to modulate thermogenic pathways in white adipose tissue (WAT) and/or brown adipose tissue (BAT). Among the different environmental factors capable of influencing host metabolism and energy balance, the gut microbiota is now considered a key player. Following pioneering studies showing that mice lacking gut microbes (that is, germ-free mice) or depleted of their gut microbiota (that is, using antibiotics) developed less adipose tissue, numerous studies have investigated the complex interactions existing between gut bacteria, some of their membrane components (that is, lipopolysaccharides), and their metabolites (that is, short-chain fatty acids, endocannabinoids, bile acids, aryl hydrocarbon receptor ligands and tryptophan derivatives) as well as their contribution to the browning and/or beiging of WAT and changes in BAT activity. In this Review, we discuss the general physiology of both WAT and BAT. Subsequently, we introduce how gut bacteria and different microbiota-derived metabolites, their receptors and signalling pathways can regulate the development of adipose tissue and its metabolic capacities. Finally, we describe the key challenges in moving from bench to bedside by presenting specific key examples.

NAPE-PLD in the ventral tegmental area regulates reward events, feeding and energy homeostasis

The N-acyl phosphatidylethanolamine-specific phospholipase D (NAPE-PLD) catalyzes the production of N-acylethanolamines (NAEs), a family of endogenous bioactive lipids, which are involved in various biological processes ranging from neuronal functions to energy homeostasis and feeding behaviors. Reward-dependent behaviors depend on dopamine (DA) transmission between the ventral tegmental area (VTA) and the nucleus accumbens (NAc), which conveys reward-values and scales reinforced behaviors. However, whether and how NAPE-PLD may contribute to the regulation of feeding and reward-dependent behaviors has not yet been investigated. This biological question is of paramount importance since NAEs are altered in obesity and metabolic disorders. Here, we show that transcriptomic meta-analysis highlights a potential role for NAPE-PLD within the VTA→NAc circuit. Using brain-specific invalidation approaches, we report that the integrity of NAPE-PLD is required for the proper homeostasis of NAEs within the midbrain VTA and it affects food-reward behaviors. Moreover, region-specific knock-down of NAPE-PLD in the VTA enhanced food-reward seeking and reinforced behaviors, which were associated with increased in vivo DA release dynamics in response to both food- and non-food-related rewards together with heightened tropism towards food consumption. Furthermore, midbrain knock-down of NAPE-PLD, which increased energy expenditure and adapted nutrient partitioning, elicited a relative protection against high-fat diet-mediated body fat gain and obesity-associated metabolic features. In conclusion, these findings reveal a new key role of VTA NAPE-PLD in shaping DA-dependent events, feeding behaviors and energy homeostasis, thus providing new insights on the regulation of body metabolism.

Rebaudioside D decreases adiposity and hepatic lipid accumulation in a mouse model of obesity

Overconsumption of added sugars has been pointed out as a major culprit in the increasing rates of obesity worldwide, contributing to the rising popularity of non-caloric sweeteners. In order to satisfy the growing demand, industrial efforts have been made to purify the sweet-tasting molecules found in the natural sweetener stevia, which are characterized by a sweet taste free of unpleasant aftertaste. Although the use of artificial sweeteners has raised many concerns regarding metabolic health, the impact of purified stevia components on the latter remains poorly studied. The objective of this project was to evaluate the impact of two purified sweet-tasting components of stevia, rebaudioside A and D (RebA and RebD), on the development of obesity, insulin resistance, hepatic health, bile acid profile, and gut microbiota in a mouse model of diet-induced obesity. Male C57BL/6 J mice were fed an obesogenic high-fat/high-sucrose (HFHS) diet and orally treated with 50 mg/kg of RebA, RebD or vehicle (water) for 12 weeks. An additional group of chow-fed mice treated with the vehicle was included as a healthy reference. At weeks 10 and 12, insulin and oral glucose tolerance tests were performed. Liver lipids content was analyzed. Whole-genome shotgun sequencing was performed to profile the gut microbiota. Bile acids were measured in the feces, plasma, and liver. Liver lipid content and gene expression were analyzed. As compared to the HFHS-vehicle treatment group, mice administered RebD showed a reduced weight gain, as evidenced by decreased visceral adipose tissue weight. Liver triglycerides and cholesterol from RebD-treated mice were lower and lipid peroxidation was decreased. Interestingly, administration of RebD was associated with a significant enrichment of Faecalibaculum rodentium in the gut microbiota and an increased secondary bile acid metabolism. Moreover, RebD decreased the level of lipopolysaccharide-binding protein (LBP). Neither RebA nor RebD treatments were found to impact glucose homeostasis. The daily consumption of two stevia components has no detrimental effects on metabolic health. In contrast, RebD treatment was found to reduce adiposity, alleviate hepatic steatosis and lipid peroxidation, and decrease LBP, a marker of metabolic endotoxemia in a mouse model of diet-induced obesity.

Impact of metformin and Dysosmobacter welbionis on diet-induced obesity and diabetes: from clinical observation to preclinical intervention

AIMS/HYPOTHESIS

We aimed to investigate the association between the abundance of Dysosmobacter welbionis, a commensal gut bacterium, and metabolic health in human participants with obesity and diabetes, and the influence of metformin treatment and prebiotic intervention.

METHODS

Metabolic variables were assessed and faecal samples were collected from 106 participants in a randomised controlled intervention with a prebiotic stratified by metformin treatment (Food4Gut trial). The abundance of D. welbionis was measured by quantitative PCR and correlated with metabolic markers. The in vitro effect of metformin on D. welbionis growth was evaluated and an in vivo study was performed in mice to investigate the effects of metformin and D. welbionis J115T supplementation, either alone or in combination, on metabolic variables.

RESULTS

D. welbionis abundance was unaffected by prebiotic treatment but was significantly higher in metformin-treated participants. Responders to prebiotic treatment had higher baseline D. welbionis levels than non-responders. D. welbionis was negatively correlated with aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels and fasting blood glucose levels in humans with obesity and type 2 diabetes. In vitro, metformin had no direct effect on D. welbionis growth. In mice, D. welbionis J115T treatment reduced body weight gain and liver weight, and improved glucose tolerance to a better level than metformin, but did not have synergistic effects with metformin.

CONCLUSIONS/INTERPRETATION

D. welbionis abundance is influenced by metformin treatment and associated with prebiotic response, liver health and glucose metabolism in humans with obesity and diabetes. This study suggests that D. welbionis may play a role in metabolic health and warrants further investigation.

CLINICAL TRIAL

NCT03852069.

Limosilactobacillus reuteri BIO7251 administration improves metabolic phenotype in obese mice fed a high fat diet: an inter-organ crosstalk between gut, adipose tissue and nervous system

Gut microbiota is implicated in the control of host physiology by releasing bioactive actors that could exert a direct or indirect effect on tissue. A dysfunction of the gut microbiota to tissue axis could participate in the development of pathological states such as obesity and diabetes. The aim of this study was to identify the metabolic effect of Limosilactobacillus reuteri (known as Lactobacillus reuteri) BIO7251 (L. reuteri BIO7251) isolated from Corsican clementine orange. Body weight gain, adiposity, glucose tolerance, glucose absorption and food intake were measured in mice fed a high-fat diet in response to a preventive oral administration of L. reuteri BIO7251. This strain of bacteria exerts a beneficial effect on body weight gain by decreasing the subcutaneous adipose tissue mass. The treatment with L. reuteri BIO7251 decreases glucose absorption and food intake in obese/diabetic mice. L. reuteri BIO7251 could be tested as new probiotic strain that could manage body weight during obesity.

A nanoparticle platform for combined mucosal healing and immunomodulation in inflammatory bowel disease treatment

Current treatments for inflammatory bowel disease (IBD) treatment consist of anti-inflammatory products. In this study, we sought to induce the physiological secretion of glucagon-like peptide 2, a peptide with intestinal growth-promoting activity, via nanoparticles while simultaneously providing with immunomodulation by tailoring the nanoparticle surface. To this end, we developed hybrid lipid hyaluronate-KPV conjugated nanoparticles loaded with teduglutide for combination therapy in IBD. The nanocarriers induced (or did not induce) immunosuppression depending on the presence (or absence) of a hyaluronan-KPV functionalization. This strategy holds promise as a nanoparticle platform for combined mucosal healing and immunomodulation in IBD treatment.

Pasteurized akkermansia muciniphila improves irritable bowel syndrome-like symptoms and related behavioral disorders in mice

Gut - brain communications disorders in irritable bowel syndrome (IBS) are associated with intestinal microbiota composition, increased gut permeability, and psychosocial disturbances. Symptoms of IBS are difficult to medicate, and hence much research is being made into alternative approaches. This study assesses the potential of a treatment with pasteurized Akkermansia muciniphila for alleviating IBS-like symptoms in two mouse models of IBS with different etiologies. Two clinically relevant animal models were used to mimic IBS-like symptoms in C57BL6/J mice: the neonatal maternal separation (NMS) paradigm and the Citrobacter rodentium infection model. In both models, gut permeability, colonic sensitivity, fecal microbiota composition and colonic IL-22 expression were evaluated. The cognitive performance and emotional state of the animals were also assessed by several tests in the C. rodentium infection model. The neuromodulation ability of pasteurized A. muciniphila was assessed on primary neuronal cells from mice dorsal root ganglia using a ratiometric calcium imaging approach. The administration of pasteurized A. muciniphila significantly reduced colonic hypersensitivity in both IBS mouse models, accompanied by a reinforcement of the intestinal barrier function. Beneficial effects of pasteurized A. muciniphila treatment have also been observed on anxiety-like behavior and memory defects in the C. rodentium infection model. Finally, a neuroinhibitory effect exerted by pasteurized A. muciniphila was observed on neuronal cells stimulated with two algogenic substances such as capsaicin and inflammatory soup. Our findings demonstrate novel anti-hyperalgesic and neuroinhibitory properties of pasteurized A. muciniphila, which therefore may have beneficial effects in relieving pain and anxiety in subjects with IBS.

Dysosmobacter welbionis effects on glucose, lipid, and energy metabolism are associated with specific bioactive lipids

The newly identified bacterium Dysosmobacter welbionis J115T improves host metabolism in high-fat diet (HFD)-fed mice. To investigate mechanisms, we used targeted lipidomics to identify and quantify bioactive lipids produced by the bacterium in the culture medium, the colon, the brown adipose tissue (BAT), and the blood of mice. In vitro, we compared the bioactive lipids produced by D. welbionis J115T versus the probiotic strain Escherichia coli Nissle 1917. D. welbionis J115T administration reduced body weight, fat mass gain, and improved glucose tolerance and insulin resistance in HFD-fed mice. In vitro, 19 bioactive lipids were highly produced by D. welbionis J115T as compared to Escherichia coli Nissle 1917. In the plasma, 13 lipids were significantly changed by the bacteria. C18-3OH was highly present at the level of the bacteria, but decreased by HFD treatment in the plasma and normalized in D. welbionis J115T-treated mice. The metabolic effects were associated with a lower whitening of the BAT. In the BAT, HFD decreased the 15-deoxy-Δ12,14-prostaglandin J2, a peroxisome proliferator-activated receptor (PPAR-γ) agonist increased by 700% in treated mice as compared to HFD-fed mice. Several genes controlled by PPAR-γ were upregulated in the BAT. In the colon, HFD-fed mice had a 60% decrease of resolvin D5, whereas D. welbionis J115T-treated mice exhibited a 660% increase as compared to HFD-fed mice. In a preliminary experiment, we found that D. welbionis J115T improves colitis. In conclusion, D. welbionis J115T influences host metabolism together with several bioactive lipids known as PPAR-γ agonists.

NAPE-PLD in the ventral tegmental area regulates reward events, feeding and energy homeostasis

The N-acyl phosphatidylethanolamine-specific phospholipase D (NAPE-PLD) catalyzes the production of N-acylethanolamines (NAEs), a family of endogenous bioactive lipids, which are involved in various biological processes ranging from neuronal functions to energy homeostasis and feeding behaviors. Reward-dependent behaviors depend on dopamine (DA) transmission between the ventral tegmental area (VTA) and the nucleus accumbens (NAc), which conveys reward-values and scales reinforced behaviors. However, whether and how NAPE-PLD may contribute to the regulation of feeding and reward-dependent behaviors has not yet been investigated. This biological question is of paramount importance since NAEs are altered in obesity and metabolic disorders. Here, we show that transcriptomic meta-analysis highlights a potential role for NAPE-PLD within the VTA®NAc circuit. Using brain-specific invalidation approaches, we report that the integrity of NAPE-PLD is required for the proper homeostasis of NAEs within the midbrain VTA and it affects food-reward behaviors. Moreover, region-specific knock-down of NAPE-PLD in the VTA enhanced food-reward seeking and reinforced behaviors, which were associated with increased in vivo DA release dynamics in response to both food and non-food-related rewards together with heightened tropism towards food consumption. Furthermore, midbrain knock-down of NAPE-PLD, which increased energy expenditure and adapted nutrient partitioning, elicited a relative protection against high-fat diet-mediated body fat gain and obesity-associated metabolic features. In conclusion, these findings reveal a new key role of VTA NAPE-PLD in shaping DA-dependent events, feeding behaviors and energy homeostasis, thus providing new insights on the regulation of body metabolism.

The Sterilization of Human Milk by Holder Pasteurization or by High Hydrostatic Pressure Processing Leads to Differential Intestinal Effects in Mice

BACKGROUND

Human milk banks (HMBs) provide sterilized donor milk (DM) for the feeding of preterm infants. Most HMBs use the standard method of Holder pasteurization (HoP) performed by heating DM at 62.5 °C for 30 min. High hydrostatic pressure (HHP) processing has been proposed as an alternative to HoP. This study aims to evaluate intestinal barrier integrity and microbiota composition in adult mice subjected to a chronic oral administration of HoP- or HHP-DM.

METHODS

Mice were treated by daily gavages with HoP- or HHP-DM over seven days. Intestinal barrier integrity was assessed through in vivo 4 kDa FITC-dextran permeability assay and mRNA expression of several tight junctions and mucins in ileum and colon. Cecal short chain fatty acids (SCFAs) and microbiota were analyzed.

RESULTS

HHP-DM mice displayed decreased intestinal permeability to FITC-dextran and increased ileal mRNA expression levels of two tight junctions (Ocln and Cdh1) and Muc2. In the colon, mRNA expression levels of two tight junctions (Cdh1 and Tjp1) and of two mucins (Muc2 and Muc4) were decreased in HHP-DM mice. Cecal SCFAs and microbiota were not different between groups.

CONCLUSIONS

HHP processing of DM reinforces intestinal barrier integrity in vivo without affecting gut microbiota and SCFAs production. This study reinforces previous findings showing that DM sterilization through HHP might be beneficial for the intestinal maturation of preterm infants compared with the use of HoP for the treatment of DM.

Impact of a Powdered Meal Replacement on Metabolism and Gut Microbiota (PREMIUM) in individuals with excessive body weight: a study protocol for a randomised controlled trial

INTRODUCTION

Excess body weight is associated with a state of low-grade chronic inflammation and alterations of the gut microbiome. Powdered meal replacements (PMR) have been shown to be an effective strategy for weight management; however, their effect on inflammation and the gut microbiome remains unclear. The aim of this 12-week randomised control clinical trial is to investigate the effects of PMR consumption, here given as a soy-yoghurt-honey formula, on inflammation, gut microbiome and overall metabolism in individuals with excessive body weight.

METHODS AND ANALYSIS

Healthy adults with excess body weight (n=88) are being recruited and randomly assigned to one of the following groups: (1) Control group (CON): maintaining usual diet for 12 weeks, or (2) PMR group: replacing morning and afternoon snacks daily with a PMR for 12 weeks. Participants are asked to maintain body weight throughout the study and fill out a journal with information about PMR consumption, body weight, food intake, appetite sensations and medications. Three study visits are required: baseline, week 6 and week 12. Outcome measures include systemic inflammatory biomarkers, gut microbiome composition, metabolic blood markers, host energy metabolism, body composition, appetite sensations and host gene expression profile.

ETHICS AND DISSEMINATION

This research protocol was approved by the University of Alberta Ethics Board (Pro00070712) and adheres to the Canadian Tri-Council Policy statement on the use of human participants in research. Procedures and potential risks are fully discussed with participants. Study findings will be disseminated in peer-reviewed journals, conference presentations and social media.

TRIAL REGISTRATION NUMBER

NCT03235804.

Pediatric Autoimmune or Primary Sclerosing Cholangitis: Metronidazole Effectiveness on Biochemical Data, Bile Acid Profile, and Gut Microbiota: A Pilot Study

Objectives

Autoimmune hepatitis and primary sclerosing cholangitis (PSC) can both be present, resulting in autoimmune sclerosing cholangitis (ASC). PSC physiopathology could be based on the cross-talk between gut microbiota and bile acids (BAs); antibiotics are an innovative therapy. This pilot study assesses metronidazole (MTZ)'s effectiveness in ASC or PSC patients according to the stage of the disease, and its effects on biochemical parameters, BA profiles, and gut microbiota.

Methods

ASC or PSC patients from Cliniques universitaires Saint-Luc's pediatric hepato-gastroenterology division were enrolled retrospectively and prospectively; both datasets were merged. MTZ was administered over at least 14 days on top of standard treatment (ursodeoxycholic acid, azathioprine, and steroids). Fecal and blood samples were collected before (T0) and at MTZ day 14 (T14). Sustained biochemical remission was defined by the reduction of transaminases (AST and ALT), gamma-glutamyl transferase (GGT), and CRP until 12 months post-MTZ.

Results

A total of 18 patients (mean age, 13.2 ± 4.5 years) were enrolled (13 ASC and 5 PSC), and divided in remission or relapse patients. CRP, AST, ALT, and GGT levels decreased post-MTZ in both groups (excepting GGT in relapse patients), with decreases between T0 and T14 being significant for AST and ALT. Relapse patients were older (P = 0.0351) and in late-disease stage, with mainly large-duct PSC (P = 0.0466). In remission patients, the mean plasma relative abundance of hydrophilic BA increased by +6.3% (P = 0.0391) after MTZ. Neither at baseline nor T14, there were significant differences in gut microbiota recorded.

Conclusion

These data are likely indicative of long-term benefits following MTZ therapy at early-stage ASC or PSC, with increased hydrophilic BA abundance. Multicenter prospective studies are needed.

Hepatic deletion of serine palmitoyl transferase 2 impairs ceramide/sphingomyelin balance, bile acids homeostasis and leads to liver damage in mice

Ceramides (Cer) have been shown as lipotoxic inducers, which disturb numerous cell-signaling pathways, leading to metabolic disorders such as type 2 diabetes. In this study, we aimed to determine the role of de novo hepatic ceramide synthesis in energy and liver homeostasis in mice. We generated mice lacking serine palmitoyltransferase 2 (Sptlc2), the rate limiting enzyme of ceramide de novo synthesis, in liver under albumin promoter. Liver function, glucose homeostasis, bile acid (BA) metabolism and hepatic sphingolipids content were assessed using metabolic tests and LC-MS. Despite lower expression of hepatic Sptlc2, we observed an increased concentration of hepatic Cer, associated with a 10-fold increase in neutral sphingomyelinase 2 (nSMase2) expression, and a decreased sphingomyelin content in the liver. Sptlc2ΔLiv mice were protected against obesity induced by high fat diet and displayed a defect in lipid absorption. In addition, an important increase in tauro-muricholic acid was associated with a downregulation of the nuclear BA receptor FXR target genes. Sptlc2 deficiency also enhanced glucose tolerance and attenuated hepatic glucose production, while the latter effect was dampened in presence of nSMase2 inhibitor. Finally, Sptlc2 disruption promoted apoptosis, inflammation and progressive development of hepatic fibrosis, worsening with age. Our data suggest a compensatory mechanism to regulate hepatic ceramides content from sphingomyelin hydrolysis, with deleterious impact on liver homeostasis. In addition, our results show the involvement of hepatic sphingolipid modulation in BA metabolism and hepatic glucose production in an insulin-independent manner, which highlight the still under-researched role of ceramides in many metabolic functions.

Pasteurized Akkermansia muciniphila improves glucose metabolism is linked with increased hypothalamic nitric oxide release

Background and objective

Pasteurized Akkermansia muciniphila cells have shown anti-diabetic effects in rodents and human. Although, its primary site of action consists in maintaining the gut barrier function, there are no study exploring if A. muciniphila controls glycemia via a gut to brain axis. Targeting the gut motility represents an alternative pathway to treat hyperglycemia. Here, we tested the impact of pasteurized A. muciniphila on gut motility, gut-brain axis and glucose metabolism.

Methods

We used mice fed a 45% high-fat (HFD) treated or not with pasteurized A. muciniphila Muc^T during 12 weeks. We measured the effects of the treatment on body weight gain, glucose metabolism (insulin, glycemia, glucose tolerance), gut contraction and enteric neurotransmitter release, and hypothalamic nitric oxide (NO) release.

Results

We show that pasteurized A. muciniphila exerts positive effects on different metabolic parameters such as body weight, fat mass, insulin, glycemia and glucose tolerance. This could be explained by the ability of pasteurized A. muciniphila supplementation to decrease duodenal contraction and to increase hypothalamic NO release in HFD mice.

Conclusion

We demonstrate a novel mode of action of pasteurized A. muciniphila explaining its beneficial impact on the control of glycemia in a preclinical model of type 2 diabetes via gut-brain axis signaling.

Obese-associated gut microbes and derived phenolic metabolite as mediators of excessive motivation for food reward

BACKGROUND

Excessive hedonic consumption is one of the main drivers for weight gain. Identifying contributors of this dysregulation would help to tackle obesity. The gut microbiome is altered during obesity and regulates host metabolism including food intake.

RESULTS

By using fecal material transplantation (FMT) from lean or obese mice into recipient mice, we demonstrated that gut microbes play a role in the regulation of food reward (i.e., wanting and learning processes associated with hedonic food intake) and could be responsible for excessive motivation to obtain sucrose pellets and alterations in dopaminergic and opioid markers in reward-related brain areas. Through untargeted metabolomic approach, we identified the 3-(3'-hydroxyphenyl)propanoic acid (33HPP) as highly positively correlated with the motivation. By administrating 33HPP in mice, we revealed its effects on food reward.

CONCLUSIONS

Our data suggest that targeting the gut microbiota and its metabolites would be an interesting therapeutic strategy for compulsive eating, preventing inappropriate hedonic food intake. Video Abstract.

Exploiting the biological effect exerted by lipid nanocapsules in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) affects approximately 25% of the global adult population and can progress to end-stage liver disease with life-threatening complications; however, no pharmacologic therapy has been approved. Drug delivery systems such as lipid nanocapsules (LNCs) are a very versatile platform, easy to produce, and can induce the secretion of the native glucagon-like peptide 1 (GLP-1) when orally administered. GLP-1 analogs are currently being extensively studied in clinical trials in the context of NAFLD. Our nanosystem provides with increased levels of GLP-1, triggered by the nanocarrier itself, and by the plasmatic absorption of the encapsulated synthetic analog (exenatide). Our goal in this study was to demonstrate a better outcome and a greater impact on the metabolic syndrome and liver disease progression associated with NAFLD with our nanosystem than with the subcutaneous injection of the GLP-1 analog alone. To that end, we studied the effect of chronic administration (one month) of our nanocarriers in two mouse models of early NASH: a genetic model (foz/foz mice fed a high fat diet (HFD)) and a dietary model (C57BL/6J mice fed with a western diet plus fructose (WDF)). Our strategy had a positive impact in promoting the normalization of glucose homeostasis and insulin resistance in both models, mitigating the progression of the disease. In the liver, diverging results were observed between the models, with the foz/foz mice presenting a better outcome. Although a complete resolution of NASH was not achieved in either model, the oral administration of the nanosystem was more efficient at preventing the progression of the disease into more severe states than the subcutaneous injection. We thus confirmed our hypothesis that the oral administration of our formulation has a stronger effect on alleviating the metabolic syndrome associated with NAFLD than the subcutaneous injection of the peptide.

The gut microbiota in obesity and weight management: microbes as friends or foe?

Obesity is caused by a long-term difference between energy intake and expenditure - an imbalance that is seemingly easily restored by increasing exercise and reducing caloric consumption. However, as simple as this solution appears, for many people, losing excess weight is difficult to achieve and even more difficult to maintain. The reason for this difficulty is that energy intake and expenditure, and by extension body weight, are regulated through complex hormonal, neural and metabolic mechanisms that are under the influence of many environmental factors and internal responses. Adding to this complexity, the microorganisms (microbes) that comprise the gut microbiota exert direct effects on the digestion, absorption and metabolism of food. Furthermore, the gut microbiota exerts a miscellany of protective, structural and metabolic effects both on the intestinal milieu and peripheral tissues, thus affecting body weight by modulating metabolism, appetite, bile acid metabolism, and the hormonal and immune systems. In this Review, we outline historical and recent advances in understanding how the gut microbiota is involved in regulating body weight homeostasis. We also discuss the opportunities, limitations and challenges of using gut microbiota-related approaches as a means to achieve and maintain a healthy body weight.

Inulin increases the beneficial effects of rhubarb supplementation on high-fat high-sugar diet-induced metabolic disorders in mice: impact on energy expenditure, brown adipose tissue activity, and microbiota

Consumption of prebiotics and plant-based compounds have many beneficial health effects through modulation of gut microbiota composition and are considered as promising nutritional strategy for the treatment of metabolic diseases. In the present study, we assessed the separated and combined effects of inulin and rhubarb on diet-induced metabolic disease in mice. We showed that supplementation with both inulin and rhubarb abolished the total body and fat mass gain upon high-fat and high-sucrose diet (HFHS) as well as several obesity-associated metabolic disorders. These effects were associated with increased energy expenditure, lower whitening of the brown adipose tissue, higher mitochondria activity and increased expression of lipolytic markers in white adipose tissue. Despite modifications of intestinal gut microbiota and bile acid compositions by inulin or rhubarb alone, combination of both inulin and rhubarb had minor additional impact on these parameters. However, the combination of inulin and rhubarb increased the expression of several antimicrobial peptides and higher goblet cell numbers, thereby suggesting a reinforcement of the gut barrier. Together, these results suggest that the combination of inulin and rhubarb in mice potentiates beneficial effects of separated rhubarb and inulin on HFHS-related metabolic disease and could be considered as nutritional strategy for the prevention and treatment of obesity and related pathologies.

Fat and not sugar as the determining factor for gut microbiota changes, obesity, and related metabolic disorders in mice

Diet-induced obesity contributes to the development of type 2 diabetes, insulin resistance, metabolic inflammation, oxidative and endoplasmic reticulum (ER) stress. Overall, obesity is associated with deviations in the composition and functionality of the gut microbiota. There are many divergent findings regarding the link between the excessive intake of certain dietary components (i.e., fat and sugar) and obesity development. We therefore investigated the effect of specific diets, with a different content of sugar and fat, in promoting obesity and related comorbidities as well as their impact on microbial load and gut microbiota composition/diversity. C57BL/6J mice were fed either a low-sugar, low-fat control diet (CT), a high-sugar diet (HS), a high-fat, high-sugar diet (HF/HS), or a high-fat diet (HF) for 8 wk. The impact of the different diets on obesity, glucose metabolism, inflammation, and oxidative and ER stress was determined. Diet-induced changes in the gut microbiota composition and density were also analyzed. HF diet-fed mice showed the highest body weight and fat mass gains and displayed the most impaired glucose and insulin profiles. HS, HF/HS, and HF diets differently affected hepatic cholesterol content and mRNA expression of several markers associated with immune cells, inflammation, oxidative and ER stress in several organs/tissues. In addition, HF diet feeding resulted in a decreased microbial load at the end of the experiment. When analyzing the gut microbiota composition, we found that HS, HF/HS, and HF diets induced specific changes in the abundance of certain bacterial taxa. This was not associated with a specific change in systemic inflammatory markers, but HS mice exhibited higher FGF21 plasma levels compared with HF diet-fed mice. Taken together, our results highlight that dietary intake of different macronutrients distinctively impacts the development of an obese/diabetic state and the regulation of metabolic inflammation in specific organs. We propose that these differences are not only obesity-driven but that changes in the gut microbiota composition may play a key role in this context.NEW & NOTEWORTHY To our knowledge, this study is the first to demonstrate that dietary macronutrients (i.e., sugar and fat) have an impact on fecal bacterial cell counting and quantitative microbiome profiling in mice. Yet, we demonstrate that dietary fat is the determining factor to promote obesity and diabetes progression, and local inflammation in different body sites. These observations can help to disentangle the conundrum of the detrimental effects of fat and sugar in our dietary habits.

Prebiotic oligofructose protects against high-fat diet-induced obesity by changing the gut microbiota, intestinal mucus production, glycosylation and secretion

Obesity is a major risk factor for the development of type 2 diabetes and cardiovascular diseases, and gut microbiota plays a key role in influencing the host energy homeostasis. Moreover, obese mice have a different gut microbiota composition, associated with an alteration of the intestinal mucus layer, which represents the interface between the bacteria and the host. We previously demonstrated that prebiotic treatment with oligofructose (FOS) counteracted the effects of diet-induced obesity, together with changes in the gut microbiota composition, but it is not known if the intestinal mucus layer could be involved. In this study, we found that, in addition to preventing high-fat diet (HFD) induced obesity in mice, the treatment with FOS increased the expression of numerous genes involved in mucus production, glycosylation and secretion, the expression of both secreted and transmembrane mucins, and the differentiation and number of goblet cells. These results were associated with significant changes in the gut microbiota composition, with FOS significantly increasing the relative and absolute abundance of the bacterial genera Odoribacter, Akkermansia, two unknown Muribaculaceae and an unknown Ruminococcaceae. Interestingly, all these bacterial genera had a negative association with metabolic parameters and a positive association with markers of the mucus layer. Our study shows that FOS treatment is able to prevent HFD-induced metabolic disorders, at least in part, by acting on all the processes of the mucus production. These data suggest that targeting the mucus and the gut microbiota by using prebiotics could help to prevent or mitigate obesity and related disorders.

Developing Strategies to Help Bee Colony Resilience in Changing Environments

Climate change, loss of plant biodiversity, burdens caused by new pathogens, predators, and toxins due to human disturbance and activity are significant causes of the loss of bee colonies and wild bees. The aim of this review is to highlight some possible strategies that could help develop bee resilience in facing their changing environments. Scientists underline the importance of the links between nutrition, microbiota, and immune and neuroendocrine stress resistance of bees. Nutrition with special care for plant-derived molecules may play a major role in bee colony health. Studies have highlighted the importance of pollen, essential oils, plant resins, and leaves or fungi as sources of fundamental nutrients for the development and longevity of a honeybee colony. The microbiota is also considered as a key factor in bee physiology and a cornerstone between nutrition, metabolism, growth, health, and pathogen resistance. Another stressor is the varroa mite parasite. This parasite is a major concern for beekeepers and needs specific strategies to reduce its severe impact on honeybees. Here we discuss how helping bees to thrive, especially through changing environments, is of great concern for beekeepers and scientists.

Constipation Mitigation by Rhubarb Extract in Middle-Aged Adults Is Linked to Gut Microbiome Modulation: A Double-Blind Randomized Placebo-Controlled Trial

Gut microbiota alterations are intimately linked to chronic constipation upon aging. We investigated the role of targeted changes in the gut microbiota composition in the relief of constipation symptoms after rhubarb extract (RE) supplementation in middle-aged volunteers. Subjects (95% women, average 58 years old) were randomized to three groups treated with RE at two different doses determined by its content of rhein (supplementation of 12.5 mg and 25 mg per day) vs. placebo (maltodextrin) for 30 days. We demonstrated that daily oral supplementation of RE for 30 days was safe even at the higher dose. Stool frequency and consistency, and perceived change in transit problem, transit speed and difficulty in evacuating, investigated by validated questionnaires, were improved in both groups of RE-treated volunteers compared to placebo. Higher abundance of Lachnospiraceae (mainly Roseburia and Agathobacter) only occurred after RE treatment when present at low levels at baseline, whereas an opposite shift in short-chain fatty acid (SCFA) levels was observed in both RE-treated groups (increase) and placebo (decrease). Fecal Lachnospiraceae and SCFA were positively correlated with stool consistency. This study demonstrates that RE supplementation promotes butyrate-producing bacteria and SCFA, an effect that could contribute to relieving chronic constipation in middle-aged persons.

Reactive Oxygen Species/Reactive Nitrogen Species as Messengers in the Gut: Impact on Physiology and Metabolic Disorders

Significance: The role of reactive oxygen/nitrogen species as "friend" or "foe" messengers in the whole body is well characterized. Depending on the concentration in the tissue considered, these molecular actors exert beneficial or deleterious impacts leading to a pathological state, as observed in metabolic disorders such as type 2 diabetes and obesity. Recent Advances: Among the tissues impacted by oxidation and inflammation in this pathological state, the intestine is a site of dysfunction that can establish diabetic symptoms, such as alterations in the intestinal barrier, gut motility, microbiota composition, and gut/brain axis communication. In the intestine, reactive oxygen/nitrogen species (from the host and/or microbiota) are key factors that modulate the transition from physiological to pathological signaling. Critical Issues: Controlling the levels of intestinal reactive oxygen/nitrogen species is a complicated balance between positive and negative impacts that is in constant equilibrium. Here, we describe the synthesis and degradation of intestinal reactive oxygen/nitrogen species and their interactions with the host. The development of novel redox-based therapeutics that alter these processes could restore intestinal health in patients with metabolic disorders. Future Directions: Deciphering the mode of action of reactive oxygen/nitrogen species in the gut of obese/diabetic patients could result in a future therapeutic strategy that combines nutritional and pharmacological approaches. Consequently, preventive and curative treatments must take into account one of the first sites of oxidative and inflammatory dysfunctions in the body, that is, the intestine. Antioxid. Redox Signal. 37, 394-415.

Gut microbes and food reward: From the gut to the brain

Inappropriate food intake behavior is one of the main drivers for fat mass development leading to obesity. Importantly the gut microbiota-mediated signals have emerged as key actors regulating food intake acting mainly on the hypothalamus, and thereby controlling hunger or satiety/satiation feelings. However, food intake is also controlled by the hedonic and reward systems leading to food intake based on pleasure (i.e., non-homeostatic control of food intake). This review focus on both the homeostatic and the non-homeostatic controls of food intake and the implication of the gut microbiota on the control of these systems. The gut-brain axis is involved in the communications between the gut microbes and the brain to modulate host food intake behaviors through systemic and nervous pathways. Therefore, here we describe several mediators of the gut-brain axis including gastrointestinal hormones, neurotransmitters, bioactive lipids as well as bacterial metabolites and compounds. The modulation of gut-brain axis by gut microbes is deeply addressed in the context of host food intake with a specific focus on hedonic feeding. Finally, we also discuss possible gut microbiota-based therapeutic approaches that could lead to potential clinical applications to restore food reward alterations. Therapeutic applications to tackle these dysregulations is of utmost importance since most of the available solutions to treat obesity present low success rate.

HYGIEIA: HYpothesizing the Genesis of Infectious Diseases and Epidemics through an Integrated Systems Biology Approach

More than two years on, the COVID-19 pandemic continues to wreak havoc around the world and has battle-tested the pandemic-situation responses of all major global governments. Two key areas of investigation that are still unclear are: the molecular mechanisms that lead to heterogenic patient outcomes, and the causes of Post COVID condition (AKA Long-COVID). In this paper, we introduce the HYGIEIA project, designed to respond to the enormous challenges of the COVID-19 pandemic through a multi-omic approach supported by network medicine. It is hoped that in addition to investigating COVID-19, the logistics deployed within this project will be applicable to other infectious agents, pandemic-type situations, and also other complex, non-infectious diseases. Here, we first look at previous research into COVID-19 in the context of the proteome, metabolome, transcriptome, microbiome, host genome, and viral genome. We then discuss a proposed methodology for a large-scale multi-omic longitudinal study to investigate the aforementioned biological strata through high-throughput sequencing (HTS) and mass-spectrometry (MS) technologies. Lastly, we discuss how a network medicine approach can be used to analyze the data and make meaningful discoveries, with the final aim being the translation of these discoveries into the clinics to improve patient care.

Breath volatile metabolome reveals the impact of dietary fibres on the gut microbiota: Proof of concept in healthy volunteers

Background

Current data suggest that dietary fibre (DF) interaction with the gut microbiota largely contributes to their physiological effects. The bacterial fermentation of DF leads to the production of metabolites, most of them are volatile. This study analyzed the breath volatile metabolites (BVM) profile in healthy individuals (n=15) prior and after a 3-week intervention with chitin-glucan (CG, 4.5 g/day), an insoluble fermentable DF.

Methods

The present exploratory study presents the original data related to the secondary outcomes, notably the analysis of BVM. BVM were analyzed throughout the test days -in fasting state and after standardized meals - using selected ion flow tube mass spectrometry (SIFT-MS). BVM production was correlated to the gut microbiota composition (Illumina sequencing, primary outcome), analyzed before and after the intervention.

Findings

The data reveal that the post-prandial state versus fasting state is a key determinant of BVM fingerprint. Correlation analyses with fecal microbiota spotlighted butyrate-producing bacteria, notably Faecalibacterium, as dominant bacteria involved in butyrate and other BVM expiration. CG intervention promotes interindividual variations of fasting BVM, and decreases or delays the expiration of most exhaled BVM in favor of H₂ expiration, without any consequence on gastrointestinal tolerance.

Interpretation

Assessing BVM is a non-invasive methodology allowing to analyze the influence of DF intervention on the gut microbiota.

Funding

FiberTAG project was initiated from a European Joint Programming Initiative “A Healthy Diet for a Healthy Life” (JPI HDHL) and was supported by the Service Public de Wallonie (SPW-EER, convention 1610365, Belgium).

Glucose Stimulates Gut Motility in Fasted and Fed Conditions: Potential Involvement of a Nitric Oxide Pathway

(1) Background: Type 2 diabetes (T2D) is associated with a duodenal hypermotility in postprandial conditions that favors hyperglycemia and insulin resistance via the gut-brain axis. Enterosynes, molecules produced within the gut with effects on the enteric nervous system, have been recently discovered and pointed to as potential key modulators of the glycemia. Indeed, targeting the enteric nervous system that controls gut motility is now considered as an innovative therapeutic way in T2D to limit intestinal glucose absorption and restore the gut-brain axis to improve insulin sensitivity. So far, little is known about the role of glucose on duodenal contraction in fasted and fed states in normal and diabetic conditions. The aim of the present study was thus to investigate these effects in adult mice. (2) Methods: Gene-expression level of glucose transporters (SGLT-1 and GLUT2) were quantified in the duodenum and jejunum of normal and diabetic mice fed with an HFD. The effect of glucose at different concentrations on duodenal and jejunal motility was studied ex vivo using an isotonic sensor in fasted and fed conditions in both normal chow and HFD mice. (3) Results: Both SGLT1 and GLUT2 expressions were increased in the duodenum (47 and 300%, respectively) and jejunum (75% for GLUT2) of T2D mice. We observed that glucose stimulates intestinal motility in fasted (200%) and fed (400%) control mice via GLUT2 by decreasing enteric nitric oxide release (by 600%), a neurotransmitter that inhibits gut contractions. This effect was not observed in diabetic mice, suggesting that glucose sensing and mechanosensing are altered during T2D. (4) Conclusions: Glucose acts as an enterosyne to control intestinal motility and glucose absorption through the enteric nervous system. Our data demonstrate that GLUT2 and a reduction of NO production could both be involved in this stimulatory contracting effect.

Gut microbiome and health: mechanistic insights

The gut microbiota is now considered as one of the key elements contributing to the regulation of host health. Virtually all our body sites are colonised by microbes suggesting different types of crosstalk with our organs. Because of the development of molecular tools and techniques (ie, metagenomic, metabolomic, lipidomic, metatranscriptomic), the complex interactions occurring between the host and the different microorganisms are progressively being deciphered. Nowadays, gut microbiota deviations are linked with many diseases including obesity, type 2 diabetes, hepatic steatosis, intestinal bowel diseases (IBDs) and several types of cancer. Thus, suggesting that various pathways involved in immunity, energy, lipid and glucose metabolism are affected.In this review, specific attention is given to provide a critical evaluation of the current understanding in this field. Numerous molecular mechanisms explaining how gut bacteria might be causally linked with the protection or the onset of diseases are discussed. We examine well-established metabolites (ie, short-chain fatty acids, bile acids, trimethylamine N-oxide) and extend this to more recently identified molecular actors (ie, endocannabinoids, bioactive lipids, phenolic-derived compounds, advanced glycation end products and enterosynes) and their specific receptors such as peroxisome proliferator-activated receptor alpha (PPARα) and gamma (PPARγ), aryl hydrocarbon receptor (AhR), and G protein-coupled receptors (ie, GPR41, GPR43, GPR119, Takeda G protein-coupled receptor 5).Altogether, understanding the complexity and the molecular aspects linking gut microbes to health will help to set the basis for novel therapies that are already being developed.

Abstract 331: Modulation Of Murine Vasculitis And Cardiovascular Inflammation By The Gut Microbiota

Changes in intestinal microbiota composition and function are associated with development of cardiovascular disease, but the role of these alterations remains unclear in Kawasaki Disease (KD), an acute pediatric vasculitis that targets coronary arteries. Using a murine model of KD vasculitis, we observed reduced development of cardiovascular lesions in germ-free and antibiotic-treated mice. KD vasculitis in mice was associated with alterations in the gut microbiota composition and decreased abundance of Akkermansia muciniphila and Faecalibacterium prausnitzii . Supplementation with live or pasteurized A. muciniphila or F. prausnitzii attenuated the severity of KD cardiovascular inflammation. Oral administration of the short-chain fatty acids acetate or propionate, both produced by A. muciniphila, or butyrate, produced by F. prausnitzii , reduced the development of vascular inflammation. Furthermore, treatment with Amuc_1100, a purified protein isolated from the outer membrane of A. muciniphila , decreased the severity of murine KD vasculitis. Beneficial effects of either pasteurized A. muciniphila or Amuc_1100 on murine KD vasculitis development were associated with improvement of gut barrier function. These results reveal an underappreciated gut microbiota-cardiovascular inflammation axis during murine KD vasculitis. Our findings may incite the development of novel diagnostic tools and therapeutic strategies that modulate the intestinal microbiota composition and function for KD patients.

Gut microbiome and health: mechanistic insights

The gut microbiota is now considered as one of the key elements contributing to the regulation of host health. Virtually all our body sites are colonised by microbes suggesting different types of crosstalk with our organs. Because of the development of molecular tools and techniques (ie, metagenomic, metabolomic, lipidomic, metatranscriptomic), the complex interactions occurring between the host and the different microorganisms are progressively being deciphered. Nowadays, gut microbiota deviations are linked with many diseases including obesity, type 2 diabetes, hepatic steatosis, intestinal bowel diseases (IBDs) and several types of cancer. Thus, suggesting that various pathways involved in immunity, energy, lipid and glucose metabolism are affected.In this review, specific attention is given to provide a critical evaluation of the current understanding in this field. Numerous molecular mechanisms explaining how gut bacteria might be causally linked with the protection or the onset of diseases are discussed. We examine well-established metabolites (ie, short-chain fatty acids, bile acids, trimethylamine N-oxide) and extend this to more recently identified molecular actors (ie, endocannabinoids, bioactive lipids, phenolic-derived compounds, advanced glycation end products and enterosynes) and their specific receptors such as peroxisome proliferator-activated receptor alpha (PPARα) and gamma (PPARγ), aryl hydrocarbon receptor (AhR), and G protein-coupled receptors (ie, GPR41, GPR43, GPR119, Takeda G protein-coupled receptor 5).Altogether, understanding the complexity and the molecular aspects linking gut microbes to health will help to set the basis for novel therapies that are already being developed.

Gut microbiota modulates the development of murine Kawasaki disease vasculitis

Alterations of gut microbiota composition and function influence the development of cardiovascular disease, but the role of these aberrations remains poorly understood in Kawasaki Disease (KD), an acute pediatric vasculitis that targets coronary arteries. Using a murine model of KD vasculitis, we found that germ-free and antibiotic-treated mice displayed reduced inflammation and cardiovascular lesions. Development of KD vasculitis in mice was associated with alterations in the composition of the intestinal microbiota, specifically decreased abundance of Akkermansia muciniphila and Faecalibacterium prausnitzii. Supplementation with live or pasteurized A. muciniphila or F. prausnitzii attenuated the severity of KD cardiovascular inflammation. Oral administration of the short-chain fatty acids acetate or butyrate, which are produced by A. muciniphila and F. prausnitzii respectively, or treatment with Amuc_1100, a purified protein isolated from the outer membrane of A. muciniphila, ameliorated the severity of KD cardiovascular lesions. Reduced development of KD vasculitis in mice receiving either pasteurized A. muciniphila or Amuc_1100 was associated with improvements of gut barrier function. These results reveal an underappreciated gut microbiota-cardiovascular inflammation axis during murine KD vasculitis. Our findings may stimulate the development of novel diagnostic tools and therapeutic strategies that modulate the intestinal microbiota composition and function for KD patients.

Research is supported by the NIH grants R01AI072726 to M.A. and R01HL139766 to M.N.R. 

Physical activity enhances the improvement of body mass index and metabolism by inulin: a multicenter randomized placebo-controlled trial performed in obese individuals

BACKGROUND

Dietary interventions targeting the gut microbiota have been proposed as innovative strategies to improve obesity-associated metabolic disorders. Increasing physical activity (PA) is considered as a key behavioral change for improving health. We have tested the hypothesis that changing the PA status during a nutritional intervention based on prebiotic supplementation can alter or even change the metabolic response to the prebiotic. We confirm in obese subjects and in high-fat diet fed mice that performing PA in parallel to a prebiotic supplementation is necessary to observe metabolic improvements upon inulin.

METHODS

A randomized, single-blinded, multicentric, placebo-controlled trial was conducted in obese participants who received 16 g/day native inulin versus maltodextrin, coupled to dietary advice to consume inulin-rich versus -poor vegetables for 3 months, respectively, in addition to dietary caloric restriction. Primary outcomes concern the changes on the gut microbiota composition, and secondary outcomes are related to the measures of anthropometric and metabolic parameters, as well as the evaluation of PA. Among the 106 patients who completed the study, 61 patients filled a questionnaire for PA before and after intervention (placebo: n = 31, prebiotic: n = 30). Except the dietitian (who provided dietary advices and recipes book), all participants and research staff were blinded to the treatments and no advices related to PA were given to participants in order to change their habits. In parallel, a preclinical study was designed combining both inulin supplementation and voluntary exercise in a model of diet-induced obesity in mice.

RESULTS

Obese subjects who increased PA during a 3 months intervention with inulin-enriched diet exhibited several clinical improvements such as reduced BMI (- 1.6 kg/m²), decreased liver enzymes and plasma cholesterol, and improved glucose tolerance. Interestingly, the regulations of Bifidobacterium, Dialister, and Catenibacterium genera by inulin were only significant when participants exercised more. In obese mice, we highlighted a greater gut fermentation of inulin and improved glucose homeostasis when PA is combined with prebiotics.

CONCLUSION

We conclude that PA level is an important determinant of the success of a dietary intervention targeting the gut microbiota.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03852069 (February 22, 2019 retrospectively registered).

Camu-Camu Reduces Obesity and Improves Diabetic Profiles of Obese and Diabetic Mice: A Dose-Ranging Study

Overweight, obesity, and their comorbidities are currently considered a major public health concern. Today considerable efforts are still needed to develop efficient strategies able to attenuate the burden of these diseases. Nutritional interventions, some with plant extracts, present promising health benefits. In this study, we evaluated the action of Camu-Camu (Myrciaria dubia), an Amazonian fruit rich in polyphenols and vitamin C, on the prevention of obesity and associated disorders in mice and the abundance of Akkermansia muciniphila in both cecum and feces. Methods: We investigated the dose-response effects of Camu-Camu extract (CCE) in the context of high-fat-diet (HFD)-induced obesity. After 5 weeks of supplementation, we demonstrated that the two doses of CCE differently improved glucose and lipid homeostasis. The lowest CCE dose (62.5 mg/kg) preferentially decreased non-HDL cholesterol and free fatty acids (FFA) and increased the abundance of A. muciniphila without affecting liver metabolism, while only the highest dose of CCE (200 mg/kg) prevented excessive body weight gain, fat mass gain, and hepatic steatosis. Both doses decreased fasting hyperglycemia induced by HFD. In conclusion, the use of plant extracts, and particularly CCE, may represent an additional option in the support of weight management strategies and glucose homeostasis alteration by mechanisms likely independent from the modulation of A. muciniphila abundance.

Serum metabolite profiling yields insights into health promoting effect of A. muciniphila in human volunteers with a metabolic syndrome

Reduction of A. muciniphila relative abundance in the gut microbiota is a widely accepted signature associated with obesity-related metabolic disorders. Using untargeted metabolomics profiling of fasting plasma, our study aimed at identifying metabolic signatures associated with beneficial properties of alive and pasteurized A. muciniphila when administrated to a cohort of insulin-resistant individuals with metabolic syndrome. Our data highlighted either shared or specific alterations in the metabolome according to the form of A. muciniphila administered with respect to a control group. Common responses encompassed modulation of amino acid metabolism, characterized by reduced levels of arginine and alanine, alongside several intermediates of tyrosine, phenylalanine, tryptophan, and glutathione metabolism. The global increase in levels of acylcarnitines together with specific modulation of acetoacetate also suggested induction of ketogenesis through enhanced β-oxidation. Moreover, our data pinpointed some metabolites of interest considering their emergence as substantial compounds pertaining to health and diseases in the more recent literature.

Dysosmobacter welbionis is a newly isolated human commensal bacterium preventing diet-induced obesity and metabolic disorders in mice

OBJECTIVE

To investigate the abundance and the prevalence of Dysosmobacter welbionis J115^T, a novel butyrate-producing bacterium isolated from the human gut both in the general population and in subjects with metabolic syndrome. To study the impact of this bacterium on host metabolism using diet-induced obese and diabetic mice.

DESIGN

We analysed the presence and abundance of the bacterium in 11 984 subjects using four human cohorts (ie, Human Microbiome Project, American Gut Project, Flemish Gut Flora Project and Microbes4U). Then, we tested the effects of daily oral gavages with live D. welbionis J115^T on metabolism and several hallmarks of obesity, diabetes, inflammation and lipid metabolism in obese/diabetic mice.

RESULTS

This newly identified bacterium was detected in 62.7%-69.8% of the healthy population. Strikingly, in obese humans with a metabolic syndrome, the abundance of Dysosmobacter genus correlates negatively with body mass index, fasting glucose and glycated haemoglobin. In mice, supplementation with live D. welbionis J115^T, but not with the pasteurised bacteria, partially counteracted diet-induced obesity development, fat mass gain, insulin resistance and white adipose tissue hypertrophy and inflammation. In addition, live D. welbionis J115^T administration protected the mice from brown adipose tissue inflammation in association with increased mitochondria number and non-shivering thermogenesis. These effects occurred with minor impact on the mouse intestinal microbiota composition.

CONCLUSIONS

These results suggest that D. welbionis J115^T directly and beneficially influences host metabolism and is a strong candidate for the development of next-generation beneficial bacteria targeting obesity and associated metabolic diseases.

Gut microbes participate in food preference alterations during obesity

Hypothalamic regulations of food intake are altered during obesity. The dopaminergic mesocorticolimbic system, responsible for the hedonic response to food intake, is also affected. Gut microbes are other key players involved in obesity. Therefore, we investigated whether the gut microbiota plays a causal role in hedonic food intake alterations contributing to obesity. We transferred fecal material from lean or diet-induced obese mice into recipient mice and evaluated the hedonic food intake using a food preference test comparing the intake of control and palatable diets (HFHS, High-Fat High-Sucrose) in donor and recipient mice. Obese mice ate 58% less HFHS during the food preference test (p < 0.0001) than the lean donors, suggesting a dysregulation of the hedonic food intake during obesity. Strikingly, the reduction of the pleasure induced by eating during obesity was transferable through gut microbiota transplantation since obese gut microbiota recipient mice exhibited similar reduction in HFHS intake during the food preference test (40% reduction as compared to lean gut microbiota recipient mice, p < 0.01). This effect was associated with a consistent trend in modifications of dopaminergic markers expression in the striatum. We also pinpointed a highly positive correlation between HFHS intake and Parabacteroides (p < 0.0001), which could represent a potential actor involved in hedonic feeding probably through the gut-to-brain axis. We further demonstrated the key roles played by gut microbes in this paradigm since depletion of gut microbiota using broad-spectrum antibiotics also altered HFHS intake during food preference test in lean mice. In conclusion, we discovered that gut microbes regulate hedonic aspects of food intake. Our data demonstrate that gut microbiota modifications associated with obesity participate in dysregulations of the reward and hedonic components of the food intake. These data provide evidence that gut microbes could be an interesting therapeutic target to tackle hedonic disorders related to obesity.

Microbiota and Metabolite Profiling as Markers of Mood Disorders: A Cross-Sectional Study in Obese Patients

Obesity is associated with an increased risk of several neurological and psychiatric diseases, but few studies report the contribution of biological features in the occurrence of mood disorders in obese patients. The aim of the study is to evaluate the potential links between serum metabolomics and gut microbiome, and mood disturbances in a cohort of obese patients. Psychological, biological characteristics and nutritional habits were evaluated in 94 obese subjects from the Food4Gut study stratified according to their mood score assessed by the Positive and Negative Affect Schedule (PANAS). The fecal gut microbiota and plasma non-targeted metabolomics were analysed. Obese subjects with increased negative mood display elevated levels of Coprococcus as well as decreased levels of Sutterella and Lactobacillus. Serum metabolite profile analysis reveals in these subjects altered levels of several amino acid-derived metabolites, such as an increased level of L-histidine and a decreased in phenylacetylglutamine, linked to altered gut microbiota composition and function rather than to differences in dietary amino acid intake. Regarding clinical profile, we did not observe any differences between both groups. Our results reveal new microbiota-derived metabolites that characterize the alterations of mood in obese subjects, thereby allowing to propose new targets to tackle mood disturbances in this context. Food4gut, clinicaltrial.gov: NCT03852069.

Three of a Kind: Control of the Expression of Liver-Expressed Antimicrobial Peptide 2 (LEAP2) by the Endocannabinoidome and the Gut Microbiome

The endocannabinoidome (expanded endocannabinoid system, eCBome)-gut microbiome (mBIome) axis plays a fundamental role in the control of energy intake and processing. The liver-expressed antimicrobial peptide 2 (LEAP2) is a recently identified molecule acting as an antagonist of the ghrelin receptor and hence a potential effector of energy metabolism, also at the level of the gastrointestinal system. Here we investigated the role of the eCBome-gut mBIome axis in the control of the expression of LEAP2 in the liver and, particularly, the intestine. We confirm that the small intestine is a strong contributor to the circulating levels of LEAP2 in mice, and show that: (1) intestinal Leap2 expression is profoundly altered in the liver and small intestine of 13 week-old germ-free (GF) male mice, which also exhibit strong alterations in eCBome signaling; fecal microbiota transfer (FMT) from conventionally raised to GF mice completely restored normal Leap2 expression after 7 days from this procedure; in 13 week-old female GF mice no significant change was observed; (2) Leap2 expression in organoids prepared from the mouse duodenum is elevated by the endocannabinoid noladin ether, whereas in human Caco-2/15 epithelial intestinal cells it is elevated by PPARγ activation by rosiglitazone; (3) Leap2 expression is elevated in the ileum of mice with either high-fat diet—or genetic leptin signaling deficiency—(i.e., ob/ob and db/db mice) induced obesity. Based on these results, we propose that LEAP2 originating from the small intestine may represent a player in eCBome- and/or gut mBIome-mediated effects on food intake and energy metabolism.

Gut barrier and microbiota changes with glycine and branched-chain amino acid supplementation in chronic haemodialysis patients

BACKGROUND

We have previously shown that glycine increases fat-free mass in chronic haemodialysis patients with features of malnutrition as compared with branched-chain amino acids (BCAAs). This multicentre randomized double-blind crossover study evaluates the impact of these amino acids on the gut barrier and microbiota.

METHODS

Haemodialysis patients were included if they had plasma albumin <38 g/L or weight loss >5% of dry body weight, and daily dietary intakes <30 kcal/kg and <1 g protein/kg. They consumed glycine or BCAA (7 g twice daily) for 4 months and underwent a 1 month washout period, before crossover of supplementations. Faecal microbiota (16S rRNA gene sequencing) and immunoglobulin A (IgA), serum levels of cytokines, surrogate markers of intestinal permeability, appetite mediators, and endocannabinoids were obtained at the start and end of each supplementation. Supplementations were compared by multiple mixed linear regression models, adjusted for age, sex, month of supplementation (0 and 4 in each period), and period (Period 1: first 4 months; Period 2: last 4 months). Microbiota comparisons were performed using principal coordinate analysis and permutational multivariate analysis of variance, Shannon diversity index estimate and analysis of composition of microbiomes analysis, and Wilcoxon tests.

RESULTS

We analysed 27 patients compliant to the supplementations. Multiple mixed linear regression models were significant only for interleukin-6 (P = 0.002), glucagon-like peptide 1 (P = 0.028), cholecystokinin (P = 0.021), and peptide YY (P = 0.002), but not for the other outcomes. The significant models did not show any impact of the type of supplementation (P < 0.05 in all models). Principal coordinate analysis and permutational multivariate analysis of variance (P = 0.0001) showed strong microbiota clustering by subject, but no effect of the amino acids. Bacterial alpha diversity and zero-radius operational taxonomic unit richness remained stable, whatever the supplementation. Lacticaseibacillus paracasei (0.030; Q1-Q3 0.008-0.078 vs. 0.004; Q1-Q3 0.001-0.070) and Bifidobacterium dentium (0.0247; Q1-Q3 0.002-0.191 vs. 0.003; Q1-Q3 0.001-0.086) significantly decreased with the BCAA supplementation.

CONCLUSIONS

The BCAA and glycine supplementations had no impact on the serum levels of cytokines, appetite mediators, intestinal permeability, endocannabinoids, or faecal IgA. Overall faecal microbiota composition and microbial diversity did not change with the glycine or BCAA supplementation but decreased the abundance of L. paracasei and B. dentium.

Glycine increases fat-free mass in malnourished haemodialysis patients: a randomized double-blind crossover trial

BACKGROUND

Protein energy wasting is associated with negative outcome in patients under chronic haemodialysis (HD). Branched-chain amino acids (BCAAs) may increase the muscle mass. This post hoc analysis of a controlled double-blind randomized crossover study assessed the impact of BCAAs on nutritional status, physical function, and quality of life.

METHODS

We included 36 chronic HD patient features of protein energy wasting as plasma albumin <38 g/L, and dietary intakes <30 kcal/kg/day and <1 g protein/kg/day. Patients received either oral BCAA (2 × 7 g/day) or glycine (2 × 7 g/day) for 4 months (Period 1), followed by a washout period of 1 month, and then received the opposite supplement (Period 2). The outcomes were lean body mass measured by dual-energy X-ray absorptiometry, fat-free mass index measured by bioelectrical impedance, resting energy expenditure, dietary intake and appetite rating, physical activity and function, quality of life, and blood parameters. Analyses were performed by multiple mixed linear regressions including type of supplementation, months, period, sex, and age as fixed effects and subjects as random intercepts.

RESULTS

Twenty-seven patients (61.2 ± 13.7 years, 41% women) were compliant to the supplementations (consumption >80% of packs) and completed the study. BCAA did not affect lean body mass index and body weight, but significantly decreased fat-free mass index, as compared with glycine (coeff -0.27, 95% confidence interval -0.43 to -0.10, P = 0.002, respectively). BCAA and glycine intake had no effect on the other clinical parameters, blood chemistry tests, or plasma amino acids.

CONCLUSIONS

Branched-chain amino acid did not improve lean body mass as compared with glycine. Unexpectedly, glycine improved fat-free mass index in HD patients, as compared with BCAA. Whether long-term supplementation with glycine improves the clinical outcome remains to be demonstrated.

Exploring the endocannabinoidome in genetically obese (ob/ob) and diabetic (db/db) mice: Links with inflammation and gut microbiota

BACKGROUND

Obesity and type 2 diabetes are two interrelated metabolic disorders characterized by insulin resistance and a mild chronic inflammatory state. We previously observed that leptin (ob/ob) and leptin receptor (db/db) knockout mice display a distinct inflammatory tone in the liver and adipose tissue. The present study aimed at investigating whether alterations in these tissues of the molecules belonging to the endocannabinoidome (eCBome), an extension of the endocannabinoid (eCB) signaling system, whose functions are important in the context of metabolic disorders and inflammation, could reflect their different inflammatory phenotypes.

RESULTS

The basal eCBome lipid and gene expression profiles, measured by targeted lipidomics and qPCR transcriptomics, respectively, in the liver and subcutaneous or visceral adipose tissues, highlighted a differentially altered eCBome tone, which may explain the impaired hepatic function and more pronounced liver inflammation remarked in the ob/ob mice, as well as the more pronounced inflammatory state observed in the subcutaneous adipose tissue of db/db mice. In particular, the levels of linoleic acid-derived endocannabinoid-like molecules, of one of their 12-lipoxygenase metabolites and of Trpv2 expression, were always altered in tissues exhibiting the highest inflammation. Correlation studies suggested the possible interactions with some gut microbiota bacterial taxa, whose respective absolute abundances were significantly different between ob/ob and the db/db mice.

CONCLUSIONS

The present findings emphasize the possibility that bioactive lipids and the respective receptors and enzymes belonging to the eCBome may sustain the tissue-dependent inflammatory state that characterizes obesity and diabetes, possibly in relation with gut microbiome alterations.

Gut Microbiota-Induced Changes in β-Hydroxybutyrate Metabolism Are Linked to Altered Sociability and Depression in Alcohol Use Disorder

Patients with alcohol use disorder (AUD) present with important emotional, cognitive, and social impairments. The gut microbiota has been recently shown to regulate brain functions and behavior but convincing evidence of its role in AUD is lacking. Here, we show that gut dysbiosis is associated with metabolic alterations that affect behavioral (depression, sociability) and neurobiological (myelination, neurotransmission, inflammation) processes involved in alcohol addiction. By transplanting the gut microbiota from AUD patients to mice, we point out that the production of ethanol by specific bacterial genera and the reduction of lipolysis are associated with a lower hepatic synthesis of β-hydroxybutyrate (BHB), which thereby prevents the neuroprotective effect of BHB. We confirm these results in detoxified AUD patients, in which we observe a persisting ethanol production in the feces as well as correlations among low plasma BHB levels and social impairments, depression, or brain white matter alterations.

Novel insights into the genetically obese (ob/ob) and diabetic (db/db) mice: two sides of the same coin

BACKGROUND

Leptin-deficient ob/ob mice and leptin receptor-deficient db/db mice are commonly used mice models mimicking the conditions of obesity and type 2 diabetes development. However, although ob/ob and db/db mice are similarly gaining weight and developing massive obesity, db/db mice are more diabetic than ob/ob mice. It remains still unclear why targeting the same pathway-leptin signaling-leads to the development of two different phenotypes. Given that gut microbes dialogue with the host via different metabolites (e.g., short-chain fatty acids) but also contribute to the regulation of bile acids metabolism, we investigated whether inflammatory markers, bacterial components, bile acids, short-chain fatty acids, and gut microbes could contribute to explain the specific phenotype discriminating the onset of an obese and/or a diabetic state in ob/ob and db/db mice.

RESULTS

Six-week-old ob/ob and db/db mice were followed for 7 weeks; they had comparable body weight, fat mass, and lean mass gain, confirming their severely obese status. However, as expected, the glucose metabolism and the glucose-induced insulin secretion were significantly different between ob/ob and db/db mice. Strikingly, the fat distribution was different, with db/db mice having more subcutaneous and ob/ob mice having more epididymal fat. In addition, liver steatosis was more pronounced in the ob/ob mice than in db/db mice. We also found very distinct inflammatory profiles between ob/ob and db/db mice, with a more pronounced inflammatory tone in the liver for ob/ob mice as compared to a higher inflammatory tone in the (subcutaneous) adipose tissue for db/db mice. When analyzing the gut microbiota composition, we found that the quantity of 19 microbial taxa was in some way affected by the genotype. Furthermore, we also show that serum LPS concentration, hepatic bile acid content, and cecal short-chain fatty acid profiles were differently affected by the two genotypes.

CONCLUSION

Taken together, our results elucidate potential mechanisms implicated in the development of an obese or a diabetic state in two genetic models characterized by an altered leptin signaling. We propose that these differences could be linked to specific inflammatory tones, serum LPS concentration, bile acid metabolism, short-chain fatty acid profile, and gut microbiota composition. Video abstract.

A dynamic association between myosteatosis and liver stiffness: Results from a prospective interventional study in obese patients

Background & Aims

Retrospective cross-sectional studies linked sarcopenia and myosteatosis with metabolic dysfunction-associated fatty liver disease (MAFLD). Here, we wanted to clarify the dynamic relationship between sarcopenia, myosteatosis, and MAFLD.

Methods

A cohort of 48 obese patients was randomised for a dietary intervention consisting of 16 g/day of inulin (prebiotic) or maltodextrin (placebo) supplementation. Before and after the intervention, we evaluated liver steatosis and stiffness with transient elastography (TE); we assessed skeletal muscle index (SMI) and skeletal muscle fat index (SMFI) (a surrogate for absolute fat content in muscle) using computed tomography (CT) and bioelectrical impedance analysis (BIA).

Results

At baseline, sarcopenia was uncommon in patients with MAFLD (4/48, 8.3%). SMFI was higher in patients with high liver stiffness than in those with low liver stiffness (640.6 ± 114.3 cm²/ Hounsfield unit [HU] vs. 507.9 ± 103.0 cm²/HU, p = 0.001). In multivariate analysis, SMFI was robustly associated with liver stiffness even when adjusted for multiple confounders (binary logistic regression, p <0.05). After intervention, patients with inulin supplementation lost weight, but this was not associated with a decrease in liver stiffness. Remarkably, upon intervention (being inulin or maltodextrin), patients who lowered their SMFI, but not those who increased SMI, had a 12.7% decrease in liver stiffness (before = 6.36 ± 2.15 vs. after = 5.55 ± 1.97 kPa, p = 0.04).

Conclusions

Myosteatosis, but not sarcopenia, is strongly and independently associated with liver stiffness in obese patients with MAFLD. After intervention, patients in which the degree of myosteatosis decreased reduced their liver stiffness, irrespective of body weight loss or prebiotic treatment. The potential contribution of myosteatosis to liver disease progression should be investigated.

Clinical Trials registration number

NCT03852069.

Lay summary

The fat content in skeletal muscles (or myosteatosis) is strongly associated with liver stiffness in obese patients with MAFLD. After a dietary intervention, patients in which the degree of myosteatosis decreased also reduced their liver stiffness. The potential contribution of myosteatosis to liver disease progression should be investigated.

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Low-radiation CT scan enables muscle evaluation (quantity and composition).

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Muscle mass is not low in patients with MAFLD and high liver stiffness.

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In contrast, myosteatosis is strongly associated with liver stiffness.

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Lower myosteatosis after dietary intervention is associated with improved MAFLD.