Gut microbiota controls adipose tissue expansion, gut barrier and glucose metabolism: novel insights into molecular targets and interventions using prebiotics

The Emerging Role of Metabolism in Brain-Heart Axis: New Challenge for the Therapy and Prevention of Alzheimer Disease. May Thioredoxin Interacting Protein (TXNIP) Play a Role?

Alzheimer disease (AD) is the most frequent cause of dementia and up to now there is not an effective therapy to cure AD. In addition, AD onset occurs decades before the diagnosis, affecting the possibility to set up appropriate therapeutic strategies. For this reason, it is necessary to investigate the effects of risk factors, such as cardiovascular diseases, in promoting AD. AD shows not only brain dysfunction, but also alterations in peripheral tissues/organs. Indeed, it exists a reciprocal connection between brain and heart, where cardiovascular alterations participate to AD as well as AD seem to promote cardiovascular dysfunction. In addition, metabolic dysfunction promotes both cardiovascular diseases and AD. In this review, we summarize the pathways involved in the regulation of the brain-heart axis and the effect of metabolism on these pathways. We also present the studies showing the role of the gut microbiota on the brain-heart axis. Herein, we propose recent evidences of the function of Thioredoxin Interacting protein (TXNIP) in mediating the role of metabolism on the brain-heart axis. TXNIP is a key regulator of metabolism at both cellular and body level and it exerts also a pathological function in several cardiovascular diseases as well as in AD.

High-Fat Diet Induces Disruption of the Tight Junction-Mediated Paracellular Barrier in the Proximal Small Intestine Before the Onset of Type 2 Diabetes and Endotoxemia

BACKGROUND/AIM

A link between an impaired intestinal barrier, endotoxemia, and the pathogenesis of metabolic diseases, such as type 2 diabetes mellitus (T2DM), has been proposed. In previous work, we have demonstrated that the tight junction (TJ)-mediated intestinal barrier in ileum/colon was marginally changed in prediabetic mice; therefore, it does not seem to mainly contribute to the T2DM onset. In this study, the TJ-mediated epithelial barrier in the duodenum and jejunum was evaluated in mice during the development of type 2 prediabetes.

METHODS/RESULTS

HF diet induced prediabetes after 60 days associated with a significant rise in intestinal permeability to the small-sized marker Lucifer yellow in these mice, with no histological signs of mucosal inflammation or rupture of the proximal intestine epithelium. As revealed by immunofluorescence, TJ proteins, such as claudins-1, -2, -3, and ZO-1, showed a significant decrease in junctional content in duodenum and jejunum epithelia, already after 15 days of treatment, suggesting a rearrangement of the TJ structure. However, no significant change in total cell content of these proteins was observed in intestinal epithelium homogenates, as assessed by immunoblotting. Despite the changes in intestinal permeability and TJ structure, the prediabetic mice showed similar LPS, zonulin, and TNF-α levels in plasma or adipose tissue, and in intestinal segments as compared to the controls.

CONCLUSION

Disruption of the TJ-mediated paracellular barrier in the duodenum and jejunum is an early event in prediabetes development, which occurs in the absence of detectable endotoxemia/inflammation and may contribute to the HF diet-induced increase in intestinal permeability.

GeGen QinLian decoction alleviate influenza virus infectious pneumonia through intestinal flora

Influenza in humans is often accompanied by gastroenteritis-like symptoms. GeGen QinLian decoction (GQD), a Chinese herb formula, has been widely used to treat infectious diarrhea for centuries and has the effect of restoring intestinal flora. Studies have also reported that GQD were used to treat patients with influenza. However, whether regulating the intestinal flora is one of the ways GQD treats influenza has not been confirmed. In present research, we conducted a systemic pharmacological study, and the results showed that GQD may acts through multiple targets and pathways. In influenza-infected mice, GQD treatment reduced mortality and lung inflammation. Most importantly, the mortality and lung inflammation were also reduced in influenza-infected mice that have undergone fecal microbiota transplantation (FMT) from GQD (FMT-GQD) treated mice. GQD treatment or FMT-GQD treatment restores the intestinal flora, resulting in an increase in Akkermansia_muciniphila, Desulfovibrio_C21_c20 and Lactobacillus_salivarius, and a decrease in Escherichia_coli. FMT-GQD treatment inhibited the NOD/RIP2/NF-κB signaling pathway in the intestine and affected the expression of downstream related inflammatory cytokines in mesenteric lymph nodes (mLNs) and serum. In addition, FMT-GQD treatment showed systemic protection by restraining the inflammatory differentiation of CD4+ T cells. In conclusion, our study shows that GQD can affect systemic immunity, at least in part, through the intestinal flora, thereby protect the mice against influenza virus infectious pneumonia.

Kaempferol reduces obesity, prevents intestinal inflammation, and modulates gut microbiota in high-fat diet mice

Kaempferol, a flavonoid identified in a wide variety of dietary sources, has been reported to possess anti-obesity properties; however, its underlying mechanism was poorly understood. Chronic, low-grade gut inflammation and dysbacteria are proposed as underlying factors as well as novel treatment approaches for obesity-associated pathologies. This present study aims to investigate the benefits of experimental treatment with kaempferol on intestinal inflammation and gut microbial balance in animal model of obesity. High fat diet (HFD) was applied to C57BL/6J mice for 16 weeks, during which the supplement of kaempferol served as a variable. Clearly, HFD induced obesity, fat accumulation, glucose intolerance and adipose inflammation, the metabolic syndrome of which was the main finding. All these metabolic disorders can be alleviated through kaempferol supplementation. In addition, increased intestinal permeability, infiltration of immunocytes (macrophage, dendritic cells and neutrophils) and overexpression of inflammatory cytokines (tumor necrosis factor-alpha, interleukin-1beta, interleukin-6, monocyte chemoattractant protein-1) were also found in the HFD-induced mice. Kaempferol supplementation improved intestinal barrier integrity and inhibited gut inflammation, by reducing the activation of TLR4/NF-κB pathway. Furthermore, the characterization of the cecal microbiota by sequencing showed that kaempferol supplementation was able to counteract the dysbiosis associated to obesity. Our study delineated the multiple mechanism of action underlying the anti-obesity effect of kaempferol, and provide scientific evidence to support the development of kaempferol as a dietary supplement for obesity treatment.

Microbial metabolites and the vagal afferent pathway in the control of food intake

The gut microbiota is able to influence overall energy balance via effects on both energy intake and expenditure, and is a peripheral target for potential obesity therapies. However, the precise mechanism by which the gut microbiota influences energy intake and body weight regulation is not clear. Microbes use small molecules to communicate with each other; some of these molecules are ligands at mammalian receptors and this may be a mechanism by which microbes communicate with the host. Here we briefly review the literature showing beneficial effects of microbial metabolites on food intake regulation and examine the potential role for vagal afferent neurons, the gut-brain axis.

Developing a model for estimating the activity of colonic microbes after intestinal surgeries

Background

The large intestine provides a compensatory role in energy recovery when surgical interventions such as extensive small intestinal resections or bypass operations lower the efficiency of nutrient absorption in the upper gastrointestinal (GI) tract. While microorganisms in the colon are known to play vital roles in recovering energy, their contributions remain to be qualified and quantified in the small intestine resection.

Objective

We develop a mathematical model that links nutrient absorption in the upper and lower GI tract in two steps.

Methods

First, we describe the effects of small intestine resection on the ileocecal output (ICO), which enters the colon and provides food for microbes. Second, we describe energy recovered by the colon’s microorganisms via short-chain fatty acid (SCFA) production. We obtain model parameters by performing a least-squares regression analysis on clinical data for subjects with normal physiology and those who had undergone small intestine resection.

Results

For subjects with their intestines intact, our model provided a metabolizable energy value that aligns well with the traditional Atwater coefficients. With removal of the small intestine, physiological absorption became less efficient, and the metabolizable energy decreased. In parallel, the inefficiencies in physiological absorption by the small intestine are partly compensated by production of short-chain fatty acids (SCFA) from proteins and carbohydrates by microorganisms in the colon. The colon recovered more than half of the gross energy intake when the entire small intestine was removed. Meanwhile, the quality of energy absorbed changed, because microbe-derived SCFAs, not the original components of food, become the dominant form of absorbed energy.

Conclusion

The mathematical model developed here provides an important framework for describing the effect of clinical interventions on the colon’s microorganisms.

Interactions between the microbiota and enteric nervous system during gut-brain disorders

For the last 20 years, researchers have focused their intention on the impact of gut microbiota in healthy and pathological conditions. This year (2021), more than 25,000 articles can be retrieved from PubMed with the keywords "gut microbiota and physiology", showing the constant progress and impact of gut microbes in scientific life. As a result, numerous therapeutic perspectives have been proposed to modulate the gut microbiota composition and/or bioactive factors released from microbes to restore our body functions. Currently, the gut is considered a primary site for the development of pathologies that modify brain functions such as neurodegenerative (Parkinson's, Alzheimer's, etc.) and metabolic (type 2 diabetes, obesity, etc.) disorders. Deciphering the mode of interaction between microbiota and the brain is a real original option to prevent (and maybe treat in the future) the establishment of gut-brain pathologies. The objective of this review is to describe recent scientific elements that explore the communication between gut microbiota and the brain by focusing our interest on the enteric nervous system (ENS) as an intermediate partner. The ENS, which is known as the "second brain", could be under the direct or indirect influence of the gut microbiota and its released factors (short-chain fatty acids, neurotransmitters, gaseous factors, etc.). Thus, in addition to their actions on tissue (adipose tissue, liver, brain, etc.), microbes can have an impact on local ENS activity. This potential modification of ENS function has global repercussions in the whole body via the gut-brain axis and represents a new therapeutic strategy.

Triggers of Exacerbation in Chronic Urticaria and Recurrent Angioedema-Prevalence and Relevance

Patients with urticaria and angioedema often have triggers that cause an outbreak or a swelling episode or worsen their chronic condition. Exploring these factors with each patient may result in better understanding and control of their disease. Patients should be advised to avoid known triggers, if feasible, or prepare to prevent or control an exacerbation with appropriate pretreatment if avoidance is not possible. In this review, we describe and discuss a variety of factors for which there is evidence that they cause or exacerbate chronic spontaneous urticaria and angioedema. These potentially exacerbating factors include drugs, food additives, and naturally occurring pseudoallergens, mental stress, and trauma.

Intestinal barrier function in obesity with or without metabolic syndrome: a systematic review protocol

INTRODUCTION

Intestinal barrier function is dependent on the structure and function of intestinal epithelial cells and paracellular pathway. The derangement of the intestinal barrier function can originate from conditions involving local and systemic chronic inflammation and metabolic diseases such as obesity and metabolic disorders. This study aims to describe a systematic review protocol investigating if obesity with or without metabolic syndrome is associated with an altered intestinal barrier function.

METHODS AND ANALYSIS

This protocol is guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols. The databases to be searched are PubMed, Embase, Scopus, Science Direct and Web of Science. The systematic review will include original articles with adults and the elderly, who present obesity with or without metabolic syndrome, that address the intestinal barrier function. Two independent reviewers will perform study selection, data extraction and methodological quality assessment. Key information will be tabulated and a narrative synthesis will be conducted. The Grading of Recommendation, Assessment, Development and Evaluation framework will be used to assess the quality of evidence concerning the associations between intestinal barrier function and obesity with or without metabolic syndrome. The present protocol will assist in producing a systematic review that addresses if obesity with or without metabolic syndrome alters intestinal barrier function.

ETHICS AND DISSEMINATION

No ethical statement will be required. The results will be disseminated through a peer-reviewed publication and conference presentations.

PROSPERO REGISTRATION NUMBER

CRD42020178658.

The role of the vaginal microbiome in distinguishing female chronic pelvic pain caused by endometriosis/adenomyosis

Background

This study aimed to investigate the specific vaginal microbiome in the differential diagnosis of endometriosis/adenomyosis (EM/AM)-associated chronic pelvic pain (CPP) from other types of CPP, and to explore the role of the vaginal microbiome in the mechanism of EM/AM-associated CPP.

Methods

We recruited 37 women with EM/AM-associated CPP, 25 women with chronic pelvic pain syndrome (CPPS) without EM/AM, and 66 women without CPPS into our study. All of the participants were free from human papillomavirus (HPV) infection. Sequencing of barcoded 16S rRNA gene fragments (V4) was used to determine the vaginal microbiome composition on the Illumina HiSeq2500 System. Taxonomic and functional bioinformatics analyses were performed using t-test, linear discriminant analysis effect size (LEfSe), MetaStat, and PICRUSt algorithms.

Results

At the species level, EM/AM-associated CPP was found to be associated with a predominance of Clostridium butyricum, Clostridium disporicum, Alloscardovia omnicolens, and Veillonella montpellierensis, and a concomitant paucity of Lactobacillus jensenii, Lactobacillus reuteri, and Lactobacillus iners. When the relative abundance of Clostridium disporicum was over 0.001105% and that of Lactobacillus reuteri was under 0.1911349%, the differential diagnostic sensitivity and specificity were 81.08% and 52.0%, respectively. When serum CA125 was combined, the sensitivity increased to 89.19%, but the specificity remained at 52.0%. The PICRUSt results identified 7 differentially regulated pathways within the 3 groups that may be of relevance.

Conclusions

Compared to that of CPPS patients without EM/AM and women without CPPS, the vaginal microbiome of patients with EM/AM-associated CPP shows significantly higher alpha (phylogenetic) diversity, as well as higher counts of Clostridium butyricum, Clostridium disporicum, Alloscardovia omnicolens, and Veillonella montpellierensis. These differences in the vaginal microbiome may interfere with local functional pathways, which could provide a direction for innovative metabolite-specific targeted treatment. The combination of vaginal biomarkers and serum CA125 may provide an original method to differentiate EM/AM-associated CPP.

Effect of oligofructose on resistance to postoperative high-fat diet-induced damage of metabolism in diabetic rats after sleeve gastrectomy

BACKGROUND

Sleeve gastrectomy (SG) can induce prominent remission of type 2 diabetes mellitus. However, the long-term remission rate of diabetes usually decreases over time. Oligofructose has been verified to modulate host metabolism. The aim of this study was to explore the protective effect of oligofructose on high-fat diet (HFD)-induced metabolic dysfunction after SG.

AIM

To study the effect and mechanism of oligofructose on diabetic remission in diabetic rats after SG.

METHODS

SG and SHAM operation were performed on diabetes rats induced with an HFD, nicotinamide, and low-dose streptozotocin. Then the rats in the SHAM and SG groups were continuously provided with the HFD, and the rats in sleeve gastrectomy-oligofructose group were provided with a specific HFD containing 10% oligofructose. Body weight, calorie intake, oral glucose tolerance test, homeostasis model assessment of insulin resistance, lipid profile, serum insulin, glucagon-like peptide 1 (GLP-1), total bile acids, lipopolysaccharide (LPS), and colonic microbiota levels were determined and compared at the designated time points. All statistical analyses were performed using Statistic Package for Social Science version 19.0 (IBM, United States), and the statistically significant difference was considered at P < 0.05.

RESULTS

At 2 wk after surgery, rats that underwent SG exhibited improved indexes of glucose and lipid metabolism. Compared with the SG group, the rats from SG-oligofructose group exhibited better parameters of glucose and lipid metabolism, lower body weight (526.86 ± 21.51 vs 469.25 ± 21.84, P < 0.001), calorie intake (152.14 ± 9.48 vs 129.63 ± 8.99, P < 0.001), homeostasis model assessment of insulin resistance (4.32 ± 0.57 vs 3.46 ± 0.52, P < 0.05), and LPS levels (0.19 ± 0.01 vs 0.16 ± 0.01, P < 0.05), and higher levels of insulin (1.17 ± 0.17 vs 1.58 ± 0.16, P < 0.001) and GLP-1 (12.39 ± 1.67 vs 14.94 ± 1.86, P < 0.001), and relative abundances of Bifidobacterium (0.0034 ± 0.0014 vs 0.0343 ± 0.0064, P < 0.001), Lactobacillus (0.0161 ± 0.0037 vs 0.0357 ± 0.0047, P < 0.001), and Akkermansia muciniphila (0.0050 ± 0.0024 vs 0.0507 ± 0.0100, P < 0.001) at the end of the study. However, no difference in total bile acids levels was observed between the two groups.

CONCLUSION

Oligofructose partially prevents HFD-induced glucose and lipid metabolism damage after SG, which may be due to the changes of calorie intake, insulin, GLP-1, LPS, and the gut microbiota in rats.

The Role of the Gut Microbiota in the Gut-Brain Axis in Obesity: Mechanisms and Future Implications

Interaction between the gut and the brain is essential for energy homeostasis. In obesity, this homeostasis is disrupted, leading to a positive energy balance and weight gain. Obesity is a global epidemic that affects individual health and strains the socioeconomic system. Microbial dysbiosis has long been reported in obesity and obesity-related disorders. More recent literature has focused on the interaction of the gut microbiota and its metabolites on human brain and behavior. Developing strategies that target the gut microbiota could be a future approach for the treatment of obesity. Here, we review the microbiota–gut–brain axis and possible therapeutic options.

Role of dietary polyphenols on gut microbiota, their metabolites and health benefits

The beneficial health roles of dietary polyphenols in preventing oxidative stress related chronic diseases have been subjected to intense investigation over the last two decades. As our understanding of the role of gut microbiota advances our knowledge of the antioxidant and anti-inflammatory functions of polyphenols accumulates, there emerges a need to examine the prebiotic role of dietary polyphenols. This review focused onthe role of different types and sources of dietary polyphenols on the modulation of the gut microbiota, their metabolites and how they impact on host health benefits. Inter-dependence between the gut microbiota and polyphenol metabolites and the vital balance between the two in maintaining the host gut homeostasis were discussed with reference to different types and sources of dietary polyphenols. Similarly, the mechanisms behind the health benefits by various polyphenolic metabolites bio-transformed by gut microbiota were also explained. However, further research should focus on the importance of human trials and profound links of polyphenols-gut microbiota-nerve-brain as they provide the key to unlock the mechanisms behind the observed benefits of dietary polyphenols found in vitro and in vivo studies.

Synbiotic Supplementation Improves Metabolic Factors and Obesity Values in Women with Polycystic Ovary Syndrome Independent of Affecting Apelin Levels: A Randomized Double-Blind Placebo - Controlled Clinical Trial

Background

This research investigated the symbiotic supplement influences on serum glycemic indices and lipids as well as apelin rates and obesity values in polycystic ovary syndrome (PCOS) patients.

Materials and Methods

A total of 68 obese or overweight patients (20-44 years old) with PCOS were enrolled to conduct a randomized double-blinded placebo-controlled clinical trial. A total of 34 people in the synbiotic group received a synbiotic supplement and 34 people in the placebo group received placebo, daily for 8 weeks. Fasting blood specimens, anthropometric measurements and dietary intake data were gathered three times during the study. The information was analyzed by independent t test, paired t test, analysis of covariance and chi-square test.

Results

Synbiotic supplementation significantly decreased serum fasting glucose (P=0.02), insulin (P=0.001), homeostatic model assessment for insulin resistance (IR, P=0.001), weight (P=0.02), body mass index (BMI, P=0.02), waist circumference (WC, P=0.01), hip circumference (HC, P=0.02), and waist-to-height ratio (WHtR, P=0.02) but significantly increased high-density lipoprotein (HDL) cholesterol (P=0.02) compared to the placebo. At the end of the trial, no significant differences were seen in serum total cholesterol, triglyceride (TG), low-density lipoprotein (LDL) cholesterol, or apelin levels as well as waist-to-hip ratio (WHR) between the two groups.

Conclusion

Synbiotic supplementation improved glycemic indices, lipid profile and obesity values in women with PCOS. These beneficial effects were not related with alterations in serum apelin levels (Registration number: IRCT20100408003664N19).

Carbohydrates to Prevent and Treat Obesity in a Murine Model of Diet-Induced Obesity

INTRODUCTION

The biggest risk factor for obesity and its associated comorbidities is a Western diet. This Western diet induces adipose tissue (AT) inflammation, which causes an AT dysfunction. Since AT is a vital endocrine organ, its dysfunction damages other organs, thus inducing a state of chronic inflammation and causing various comorbidities. Even though it is evident a Western diet, high in fat and carbohydrates, induces obesity and its complications, it is not known yet which macronutrient plays the most important role. Therefore, the aim of this study was to investigate the effect of macronutrient composition on obesity and to reverse the Western diet-induced metabolic risk via caloric restriction (CR) or a change of diet composition.

MATERIALS AND METHODS

Male, C57BL/6JRj mice were fed with a diet high in fat, sucrose, fructose, sucrose and fructose, starch, a Western diet, or a control diet for 15 weeks. To assess reversibility of the metabolic risk, mice were first made obese via 15 weeks of WD and then put on either a CR or switched to a sucrose-rich diet.

RESULTS

A sucrose-rich and high-starch diet induced less obesity and a better metabolic profile than a Western diet, evidenced by less hepatic steatosis, lower plasma cholesterol, and less insulin resistance. Furthermore, these diets induced less intra-abdominal AT inflammation than a Western diet, since mRNA levels of pro-inflammatory markers were lower and there was less macrophage infiltration. Expression of tight junction markers in colon tissue was higher in the sucrose-rich and high-starch group than the Western group, indicating a better intestinal integrity upon sucrose-rich and high-starch feeding. Additionally, CR induced weight loss and decreased both metabolic abnormalities and AT inflammation, regardless of macronutrient composition. However, effects were more pronounced upon CR with sucrose-rich or high-starch diet. Even without CR, switching obese mice to a sucrose-rich diet induced weight loss and decreased AT inflammation and metabolic aberrations.

DISCUSSION

A diet high in sucrose or starch induces less obesity and obesity-associated complications. Moreover, switching obese mice to a sucrose-rich diet elicits weight loss and decreases obesity-induced metabolic complications, highlighting the potential of carbohydrates to treat obesity.

Cardiac Autonomic Neuropathy: A Progressive Consequence of Chronic Low-Grade Inflammation in Type 2 Diabetes and Related Metabolic Disorders

Cardiac autonomic neuropathy (CAN) is one of the earliest complications of type 2 diabetes (T2D), presenting a silent cause of cardiovascular morbidity and mortality. Recent research relates the pathogenesis of cardiovascular disease in T2D to an ensuing chronic, low-grade proinflammatory and pro-oxidative environment, being the hallmark of the metabolic syndrome. Metabolic inflammation emerges as adipose tissue inflammatory changes extending systemically, on the advent of hyperglycemia, to reach central regions of the brain. In light of changes in glucose and insulin homeostasis, dysbiosis or alteration of the gut microbiome (GM) emerges, further contributing to inflammatory processes through increased gut and blood-brain barrier permeability. Interestingly, studies reveal that the determinants of oxidative stress and inflammation progression exist at the crossroad of CAN manifestations, dictating their evolution along the natural course of T2D development. Indeed, sympathetic and parasympathetic deterioration was shown to correlate with markers of adipose, vascular, and systemic inflammation. Additionally, evidence points out that dysbiosis could promote a sympatho-excitatory state through differentially affecting the secretion of hormones and neuromodulators, such as norepinephrine, serotonin, and γ-aminobutyric acid, and acting along the renin-angiotensin-aldosterone axis. Emerging neuronal inflammation and concomitant autophagic defects in brainstem nuclei were described as possible underlying mechanisms of CAN in experimental models of metabolic syndrome and T2D. Drugs with anti-inflammatory characteristics provide potential avenues for targeting pathways involved in CAN initiation and progression. The aim of this review is to delineate the etiology of CAN in the context of a metabolic disorder characterized by elevated oxidative and inflammatory load.

State-of-the-Art of the Nutritional Alternatives to the Use of Antibiotics in Humans and Monogastric Animals

Simple Summary

Antibiotic resistance represents a worldwide recognized issue affecting both human and veterinary medicine, with a particular focus being directed towards monogastric animals destined for human consumption. This scenario is the result of frequent utilization of the antibiotics either for therapeutic purposes (humans and animals) or as growth promoters (farmed animals). Therefore, the search for nutritional alternatives has progressively been the object of significant efforts by the scientific community. So far, probiotics, prebiotics and postbiotics are considered the most promising products, as they are capable of preventing or treating gastrointestinal diseases as well as restoring a eubiosis condition after antibiotic-induced dysbiosis development. This review provides an updated state-of-the-art of these nutritional alternatives in both humans and monogastric animals.

Abstract

In recent years, the indiscriminate use of antibiotics has been perpetrated across human medicine, animals destined for zootechnical productions and companion animals. Apart from increasing the resistance rate of numerous microorganisms and generating multi-drug resistance (MDR), the nonrational administration of antibiotics causes sudden changes in the structure of the intestinal microbiota such as dysbiotic phenomena that can have a great clinical significance for both humans and animals. The aim of this review is to describe the state-of-the-art of alternative therapies to the use of antibiotics and their effectiveness in humans and monogastric animals (poultry, pigs, fish, rabbits, dogs and cats). In particular, those molecules (probiotics, prebiotics and postbiotics) which have a direct function on the gastrointestinal health are herein critically analysed in the prevention or treatment of gastrointestinal diseases or dysbiosis induced by the consumption of antibiotics.

Maternal Linoleic Acid Overconsumption Alters Offspring Gut and Adipose Tissue Homeostasis in Young but Not Older Adult Rats

Maternal n-6 polyunsaturated fatty acids (PUFA) consumption during gestation and lactation can predispose offspring to the development of metabolic diseases such as obesity later in life. However, the mechanisms underlying the potential programming effect of n-6 PUFA upon offspring physiology are not yet all established. Herein, we investigated the effects of maternal and weaning linoleic acid (LA)-rich diet interactions on gut intestinal and adipose tissue physiology in young (3-month-old) and older (6-month-old) adult offspring. Pregnant rats were fed a control diet (2% LA) or an LA-rich diet (12% LA) during gestation and lactation. At weaning, offspring were either maintained on the maternal diet or fed the other diet for 3 or 6 months. At 3 months of age, the maternal LA-diet favored low-grade inflammation and greater adiposity, while at 6 months of age, offspring intestinal barrier function, adipose tissue physiology and hepatic conjugated linoleic acids were strongly influenced by the weaning diet. The maternal LA-diet impacted offspring cecal microbiota diversity and composition at 3 months of age, but had only few remnant effects upon cecal microbiota composition at 6 months of age. Our study suggests that perinatal exposure to high LA levels induces a differential metabolic response to weaning diet exposure in adult life. This programming effect of a maternal LA-diet may be related to the alteration of offspring gut microbiota.

Microbiota, Fiber, and NAFLD: Is There Any Connection?

Gut microbiota can contribute to the development and progression of non-alcoholic fatty liver disease (NAFLD). In fact, some specific changes of gut microbiota are observed in patients in what is called dysbiota. There has been a lot of investigation by using a variety of interventions, including diet, showing the possibility to modify components of gastrointestinal dysbiota towards healthy and multivariate microbiota to restore physiologic status. One of the main focuses has been dietary fiber (DF), in which most of its variants are prebiotics. The highest effective treatment for NAFLD is, so far, weight loss achieved by caloric restriction. DF supplementation with oligofructose facilitates weight loss, enhances the production of beneficial metabolites, decreases some pathogenic bacteria population by increasing Bifidobacteria, and has effects on intestinal barrier permeability. DF use has been associated with improvement in diverse metabolic diseases, including NAFLD, by modifying gut microbiota. Additionally, it has been shown that a higher insoluble fiber consumption (≥7.5 g/day) revealed improvements in 3 different scores of liver fibrosis. Further research is needed, but given the evidence available, it is reasonable to prescribe its consumption in early stages of NAFLD in order to prevent disease progression.

Exposure to air pollutants and the gut microbiota: a potential link between exposure, obesity, and type 2 diabetes

Work has shown that increased exposure to air pollutants independently contributes to obesity and type 2 diabetes risk, yet the exact mechanisms underlying these associations have not been fully characterized. The current review summarizes recent findings regarding the impact of inhaled and ingested air pollutants on the gut microbiota. Animal and human studies provide evidence that air pollutants, such as particulate matter, nitrogen oxides, and ozone, have the potential to alter the gut microbiota. Further, studies suggest that such exposure-induced alterations to the gut microbiota may contribute to increased risk for obesity and type 2 diabetes through inflammatory pathways. Future work is needed to fully understand the complex interactions between air pollution, the gut microbiome, and human health. Additionally, advanced sequencing methods for gut microbiome research present unique opportunities to study the underlying pathways that link increased air pollution exposure with obesity and type 2 diabetes risk.

Probiotics, Prebiotics, Synbiotics, Postbiotics, and Obesity: Current Evidence, Controversies, and Perspectives

PURPOSE OF REVIEW

In this review, we summarize current evidence on gut microbiome and obesity; we discuss the role of probiotics, prebiotics, synbiotics, and postbiotics in obesity prevention and management; and we highlight and analyze main limitations, challenges, and controversies of their use.

RECENT FINDINGS

Overall, the majority of animal studies and meta-analyses of human studies examining the use of probiotics and synbiotics in obesity has shown their beneficial effects on weight reduction and other metabolic parameters via their involvement in gut microbiota modulation. Bifidobacterium and Lactobacillus strains are still the most widely used probiotics in functional foods and dietary supplements, but next generation probiotics, such as Faecalibacterium prausnitzii, Akkermansia muciniphila, or Clostridia strains, have demonstrated promising results. On the contrary, meta-analyses of human studies on the use of prebiotics in obesity have yielded contradictory results. In animal studies, postbiotics, mainly short-chain fatty acids, may increase energy expenditure through induction of thermogenesis in brown adipose tissue as well as browning of the white adipose tissue. The main limitations of studies on biotics in obesity include the paucity of human studies; heterogeneity among the studied subgroups regarding age, gender, and lifestyle; and use of different agents with potential therapeutic effects in different formulations, doses, ratio and different pharmacodynamics/pharmacokinetics. In terms of safety, the supplementation with prebiotics, probiotics, and synbiotics has not been associated with serious adverse effects among immune-competent individuals, with the exception of the use of probiotics and synbiotics in immunocompromised patients. Further large-scale Randomized Controlled Trials (RCTs) in humans are required to evaluate the beneficial properties of probiotics, prebiotics, synbiotics, and postbiotics; their ideal dose; the duration of supplementation; and the durability of their beneficial effects as well as their safety profile in the prevention and management of obesity.

Gut-organ axis: a microbial outreach and networking

Human gut microbiota (GM) includes a complex and dynamic population of microorganisms that are crucial for well-being and survival of the organism. It has been reported as diverse and relatively stable with shared core microbiota, including Bacteroidetes and Firmicutes as the major dominants. They are the key regulators of body homeostasis, involving both intestinal and extra-intestinal effects by influencing many physiological functions such as metabolism, maintenance of barrier homeostasis, inflammation and hematopoiesis. Any alteration in GM community structures not only trigger gut disorders but also influence other organs and cause associated diseases. In recent past, the GM has been defined as a 'vital organ' with its involvement with other organs; thus, establishing a link or a bi- or multidirectional communication axis between the organs via neural, endocrine, immune, humoral and metabolic pathways. Alterations in GM have been linked to several diseases known to humans; although the exact interaction mechanism between the gut and the organs is yet to be defined. In this review, the bidirectional relationship between the gut and the vital human organs was envisaged and discussed under several headings. Furthermore, several disease symptoms were also revisited to redefine the communication network between the gut microbes and the associated organs.

Role of Small Intestinal Bacterial Overgrowth (SIBO) and Inflammation in Obese Children

Knowledge of the real incidence of small intestinal bacterial overgrowth (SIBO) in obese children and its role in obesity development seems essential for a more effective approach to the treatment of this condition. In this prospective, single-blind study, presence of SIBO was evaluated in a group of children with overweight/obesity. A blood sample for evaluation of cytokine profile was collected to establish the potential relationship with inflammatory condition and lactulose breath test (LBT) to diagnose SIBO was performed. A total of 36 patients with excess of adipose tissue were recruited. Among them, 16 (44.4%) were overweight and 20 (45.6%) were obese. Overall, 26 (72.2%) children had a positive LBT and were considered suffering from SIBO, 12 (75.0%) among those overweight and 14 (70.0%) among those obese. Measurement of cytokines (IL-1α, IL-1β, IL-4, IL-6, IL-7, IL-8, IL-10, IL-12p40, IL-12p70, IL-17, IFN-α2, IFN-γ, TNF-α), cytokine antagonists (IL-1ra), chemokines (IP10, MCP-1, MIP1α, MIP1β), and growth factors (EGF, G-CSF, GM-CSF, and VEGF) secreted in culture supernatants by PHA activated-PBMCs revealed that in the study population proinflammatory cytokines IL-1, IL-6, IL-8, IL-12, IFN-γ, IL-18, and TNF-α were high, whereas anti-inflammatory mediators IL-4 and IL-10 were low. However, no significance difference between children with SIBO and those without were evidenced. Evaluation of relationship of severity of SIBO showed a significant positive relationship between EGF or IFN-α2 and H2 but not CH4 levels and an inverse significant relationship with CH4 but not H2. Despite its limitations and further studies are needed, this study seems to indicate that SIBO is extremely common in overweight and obese children and can be demonstrated not only in severely obese subjects but also in moderately overweight patients. The inflammatory state seems to precede obesity development and SIBO does not seem to have relevance in obesity development, with no relationship found between severity of SIBO and inflammatory state.

Allicin-induced host-gut microbe interactions improves energy homeostasis

Allicin (diallylthiosulfinate) is a natural food compound with multiple biological and pharmacological functions. However, the mechanism of beneficial role of Allicin on energy homeostasis is not well studied. Gut microbiota (GM) profoundly affects host metabolism via microbiota-host interactions and coevolution. Here, we investigated the interventions of beneficial microbiome induced by Allicin on energy homeostasis, particularly obesity, and related complications. Interestingly, Allicin treatment significantly improved GM composition and induced the most significant alteration enrichment of Bifidobacterium and Lactobacillus. Importantly, transplantation of the Allicin-induced GM to HFD mice (AGMT) played a remarkable role in decreasing adiposity, maintaining glucose homeostasis, and ameliorating hepatic steatosis. Furthermore, AGMT was effective in modulating lipid metabolism, activated brown adipose tissues (BATs), induced browning in sWAT, reduced inflammation, and inhibited the degradation of intestinal villi. Mechanically, AGMT significantly increased Blautia [short-chain fatty acids (SCFAs)-producing microbiota] and Bifidobacterium in HFD mice, also increased the SCFAs in the cecum, which has been proved many beneficial effects on energy homeostasis. Our study highlights that Allicin-induced host-gut microbe interactions plays an important role in regulating energy homeostasis, which provides a promising potential therapy for obesity and metabolic disorders based on host-microbe interactions.

Contribution of adipogenesis to healthy adipose tissue expansion in obesity

The manner in which white adipose tissue (WAT) expands and remodels directly impacts the risk of developing metabolic syndrome in obesity. Preferential accumulation of visceral WAT is associated with increased risk for insulin resistance, whereas subcutaneous WAT expansion is protective. Moreover, pathologic WAT remodeling, typically characterized by adipocyte hypertrophy, chronic inflammation, and fibrosis, is associated with insulin resistance. Healthy WAT expansion, observed in the "metabolically healthy" obese, is generally associated with the presence of smaller and more numerous adipocytes, along with lower degrees of inflammation and fibrosis. Here, we highlight recent human and rodent studies that support the notion that the ability to recruit new fat cells through adipogenesis is a critical determinant of healthy adipose tissue distribution and remodeling in obesity. Furthermore, we discuss recent advances in our understanding of the identity of tissue-resident progenitor populations in WAT made possible through single-cell RNA sequencing analysis. A better understanding of adipose stem cell biology and adipogenesis may lead to novel strategies to uncouple obesity from metabolic disease.

Cultivation of the Next-Generation Probiotic Akkermansia muciniphila, Methods of Its Safe Delivery to the Intestine, and Factors Contributing to Its Growth In Vivo

Probiotics are widely used for treatment of various human diseases, and their spectrum is not limited by intestinal diseases only. That is why there is a growing interest in the development of new probiotics that can modify intestinal microbiome in accordance with the needs for treatment. In 2004, Akkermansia muciniphila was discovered, and later it was shown to prevent the development of metabolic syndrome and diabetes mellitus in mice. Nevertheless, before using it for treatment, conditions necessary for its growth need to be identified. In particular, certain carbohydrates, including amino sugars, such as N-acetylglucosamine and N-acetylgalactosamine, were discovered to be necessary for successful cultivation of A. muciniphila in vitro. This is not surprising, since the natural habitat of A. muciniphila is intestinal mucin, which contains different amino sugars. Besides, ways of A. muciniphila protection from harmful factors on the way to the intestine have been developed. In addition, prebiotics such as oligosaccharides, polyphenols, as well as metformin used for diabetes mellitus treatment can promote its growth in the intestine. Finally, there is the first evidence of A. muciniphila administration to humans, which confirms the safety of its use and describes positive metabolic effects. Overall, these data suggest the possibility of an early introduction of this next-generation probiotic into clinical practice.

Temporospatial shifts in the human gut microbiome and metabolome after gastric bypass surgery

Although the etiology of obesity is not well-understood, genetic, environmental, and microbiome elements are recognized as contributors to this rising pandemic. It is well documented that Roux-en-Y gastric bypass (RYGB) surgery drastically alters the fecal microbiome, but data are sparse on temporal and spatial microbiome and metabolome changes, especially in human populations. We characterized the structure and function (through metabolites) of the microbial communities in the gut lumen and structure of microbial communities on mucosal surfaces in nine morbidly obese individuals before, 6 months, and 12 months after RYGB surgery. Moreover, using a comprehensive multi-omic approach, we compared this longitudinal cohort to a previously studied cross-sectional cohort (n = 24). In addition to the expected weight reduction and improvement in obesity-related comorbidities after RYGB surgery, we observed that the impact of surgery was much greater on fecal communities in comparison to mucosal ones. The changes in the fecal microbiome were linked to increased concentrations of branched-chain fatty acids and an overall decrease in secondary bile acid concentrations. The microbiome and metabolome data sets for this longitudinal cohort strengthen our understanding of the persistent impact of RYGB on the gut microbiome and its metabolism. Our findings highlight the importance of changes in mucosal and fecal microbiomes after RYGB surgery. The spatial modifications in the microbiome after RYGB surgery corresponded to persistent changes in fecal fermentation and bile acid metabolism, both of which are associated with improved metabolic outcomes.

The FiberTAG project: Tagging dietary fibre intake by measuring biomarkers related to the gut microbiota and their interest for health

The scientific rationale for dietary fibre intake recommendations comes from the recognition of their benefits for health based on studies first published many years ago. It remains unclear which are the key physiological effects generated by dietary fibre in view of the diversity of the food components considered as dietary fibre, of the relevance of their classification (soluble and insoluble) and from the recent discoveries putting forward their interactions with the gut microbiota. The project FiberTAG (Joint Programming Initiative 'A Healthy Diet for a Healthy Life' 2017-2020 https://www.fibertag.eu/) aims to establish a set of biomarkers (markers of gut barrier function and bacterial co-metabolites including volatile compounds and lipid derivatives), measured in different biological compartments (faeces, blood or breath) linking dietary fibre intake and gut microbiota-related health effects. The FiberTAG consortium brings together academic and industrial partners from Belgium, France, Germany and Canada to share data and samples obtained from existing as well as new intervention studies in order to evaluate the relevance of such biomarkers. The FiberTAG consortium is currently working on five existing cohorts (prospective observational or nutritional interventions in healthy or obese patients), and a number of new intervention studies to analyse the effect of insoluble dietary fibre (wheat bran and chitin-glucan, provided by the industrial partners) in healthy individuals or in obese patients at high cardiometabolic risk.

Adipokines and Adipose Tissue-Related Metabolites, Nuts and Cardiovascular Disease

Adipose tissue is a complex structure responsible for fat storage and releasing polypeptides (adipokines) and metabolites, with systemic actions including body weight balance, appetite regulation, glucose homeostasis, and blood pressure control. Signals sent from different tissues are generated and integrated in adipose tissue; thus, there is a close connection between this endocrine organ and different organs and systems such as the gut and the cardiovascular system. It is known that functional foods, especially different nuts, may be related to a net of molecular mechanisms contributing to cardiometabolic health. Despite being energy-dense foods, nut consumption has been associated with no weight gain, weight loss, and lower risk of becoming overweight or obese. Several studies have reported beneficial effects after nut consumption on glucose control, appetite suppression, metabolites related to adipose tissue and gut microbiota, and on adipokines due to their fatty acid profile, vegetable proteins, l-arginine, dietary fibers, vitamins, minerals, and phytosterols. The aim of this review is to briefly describe possible mechanisms implicated in weight homeostasis related to different nuts, as well as studies that have evaluated the effects of nut consumption on adipokines and metabolites related to adipose tissue and gut microbiota in animal models, healthy individuals, and primary and secondary cardiovascular prevention.

The potential of insects as food sources - a review

Entomophagy is a long-time practice and a food source for many cultures. Still, many societies have abandoned it a long time ago, and regard it as a primal behavior. However, nowadays, the challenge for food demand, with the urge of new nutritional sources, and the problems of undernourishment, mainly on underdeveloped countries, has reached a point where a new perspective is demanded. This review gathers some of the most recent studies regarding the potential benefits and concerns of entomophagy, trying to show the potential of insects as food source and possible ways to introduce them in cultures that have disregarded entomophagy. Entomophagy is taking its place, showing the grand potential of insects as feed and food source. As neophobia and disgust are the main western cultures barriers to accept entomophagy, today's comprehension of this practice and processing capabilities can take that source, to any dish in any form. A simple but nutritive insect powder can create a path to a widely, sustainable, rich food source-insects.

Effect of Short-Term Dietary Intervention and Probiotic Mix Supplementation on the Gut Microbiota of Elderly Obese Women

Accumulating literature is providing evidence that the gut microbiota is involved in metabolic disorders, but the question of how to effectively modulate it to restore homeostasis, especially in the elderly, is still under debate. In this study, we profiled the intestinal microbiota of 20 elderly obese women (EO) at the baseline (T0), after 15 days of hypocaloric Mediterranean diet administered as part of a nutritional-metabolic rehabilitation program for obesity (T1), and after a further 15 days of the same diet supplemented with a probiotic mix (T2). Fecal samples were characterized by Illumina MiSeq sequencing of the 16S rRNA gene. The EO microbiota showed the typical alterations found in obesity, namely, an increase in potential pro-inflammatory components (i.e., Collinsella) and a decrease in health-promoting, short-chain fatty acid producers (i.e., Lachnospiraceae and Ruminococcaceae members), with a tendency to reduced biodiversity. After 15 days of the rehabilitation program, weight decreased by (2.7 ± 1.5)% and the gut microbiota dysbiosis was partially reversed, with a decline of Collinsella and an increase in leanness-related taxa. During the next 15 days of diet and probiotics, weight dropped further by (1.2 ± 1.1)%, markers of oxidative stress improved, and Akkermansia, a mucin degrader with beneficial effects on host metabolism, increased significantly. These findings support the relevant role of a correct dietetic approach, even in the short term, to modulate the EO gut microbiota towards a metabolic health-related configuration, counteracting the increased risk of morbidity in these patients.

Effects of Lactobacillus plantarum PMO 08 Alone and Combined with Chia Seeds on Metabolic Syndrome and Parameters Related to Gut Health in High-Fat Diet-Induced Obese Mice

This study researched the effects of Lactobacillus plantarum PMO 08 alone and combined with chia seeds on metabolic syndrome and parameters related to microbiota modulation and intestinal barrier integrity in obese mice fed high-fat diets (HFDs; 45% kcal fat). Male C57BL/6J mice were acclimated for a period of 2 weeks and then randomly separated into five groups depending on whether they received a normal diet (ND group), an HFD (HFD group), an HFD with L. plantarum (PMO group), an HFD with L. plantarum combined with chia seeds (PMOChia group), or an HFD with chia seeds (Chia group). Serum lipid profiles and related markers (cholesterol metabolism-related gene expression) were measured. Intestinal barrier integrity was assessed by measuring occludin mRNA expression of tight junction proteins. Mucosal bacteria were checked with quantitative reverse transcript polymerase chain reaction (qRT-PCR). After 16 weeks of feeding, the PMO group showed significantly lower serum total cholesterol, low-density lipoprotein cholesterol levels, atherogenic index, and cardiac risk factors compared to the HFD group. Moreover, the hepatic mRNA expression of SREBP2 (sterol regulatory element binding protein 2), a protein related to cholesterol metabolism, was significantly downregulated in the PMO group. We also found a positive synergistic effect in the PMOChia group, as manifested by the hepatic mRNA expression of hepatic CYP7A1 (cholesterol 7α-hydroxylase), strengthening of the gut barrier function, and the promotion of more L. plantarum in the colonic mucosa than in either the HFD or PMO group. In conclusion, our results indicate that PMO 08 may protect against metabolic syndrome by exerting effects on the regulation of lipid metabolism. Although the effects of chia seeds alone remain uncertain based on this experiment, its combination with PMO 08 was demonstrated to improve multiple beneficial effects of PMO 08 in obese mice fed HFD, which is a promising possibility for future research.

Dietary interventions, intestinal microenvironment, and obesity: a systematic review

CONTEXT

Obesity has been linked to the intestinal microenvironment. Diet plays an important role in obesity and has been associated with microbiota.

OBJECTIVE

This systematic review sought to evaluate the scientific evidence on the effect of dietary modification, including supplementation with prebiotics and probiotics, on microbiota diversity in obesity.

DATA SOURCES

A systematic search was performed in the MEDLINE and EMBASE databases. Studies were considered eligible if they were clinical trials evaluating dietary intervention and microbiota, body weight, or clinical parameters in obesity.

DATA EXTRACTION

Data were extracted by 2 independent reviewers.

RESULTS

From 168 articles identified, 20 were included (n = 931 participants). Increased phyla abundance after food interventions was the main finding in relation to microbiota. Regarding the impact of interventions, increased insulin sensitivity, reduced levels of inflammatory markers, and reduced body mass index were shown in several studies.

CONCLUSIONS

Interventions that modulate microbiota, especially prebiotics, show encouraging results in treating obesity, improving insulin levels, inflammatory markers, and body mass index. Because the studies included in this review were heterogeneous, it is difficult to achieve conclusive and definitive results.

Gene-Environment Interactions on Body Fat Distribution

The prevalence of obesity has been increasing markedly in the U.S. and worldwide in the past decades; and notably, the obese populations are signified by not only the overall elevated adiposity but also particularly harmful accumulation of body fat in the central region of the body, namely, abdominal obesity. The profound shift from “traditional” to “obesogenic” environments, principally featured by the abundance of palatable, energy-dense diet, reduced physical activity, and prolonged sedentary time, promotes the obesity epidemics and detrimental body fat distribution. Recent advances in genomics studies shed light on the genetic basis of obesity and body fat distribution. In addition, growing evidence from investigations in large cohorts and clinical trials has lent support to interactions between genetic variations and environmental factors, e.g., diet and lifestyle factors, in relation to obesity and body fat distribution. This review summarizes the recent discoveries from observational studies and randomized clinical trials on the gene–environment interactions on obesity and body fat distribution.

Microbiome and type 1 diabetes

The steep increase in the incidence of type 1 diabetes (T1D), in the Western world after World War II, cannot be explained solely by genetic factors but implies that this rise must be due to crucial interactions between predisposing genes and environmental changes. Three parallel phenomena in early childhood – the dynamic development of the immune system, maturation of the gut microbiome, and the appearance of the first T1D-associated autoantibodies – raise the question whether these phenomena might reflect causative relationships. Plenty of novel data on the role of the microbiome in the development of T1D has been published over recent years and this review summarizes recent findings regarding the associations between islet autoimmunity, T1D, and the intestinal microbiota.

Supplementation with Sodium Butyrate Modulates the Composition of the Gut Microbiota and Ameliorates High-Fat Diet-Induced Obesity in Mice

BACKGROUND

Short-chain fatty acids (SCFAs) have been reported to ameliorate obesity. However, the underlying mechanisms require further investigation.

OBJECTIVE

The aim of this study was to determine the role of butyrate, an SCFA, in the regulation of obesity, low-grade chronic inflammation, and alterations of microbiota composition in mice.

METHODS

Male C57BL/6J mice, 4-5 wk of age, were divided into 3 groups (n = 8 mice/group): low-fat diet (LFD; 10% energy from fat), high-fat diet (HFD; 45% energy from fat), or high-fat diet plus sodium butyrate (HSB). HSB mice received sodium butyrate at a concentration of 0.1 M in drinking water for 12 wk. Measures of inflammation, obesity, and intestinal integrity were assessed. Serum lipopolysaccharide (LPS) concentrations were measured in the 3 groups. Fecal samples were collected for gut microbiota analysis.

RESULTS

In HFD mice, body weight gain and hepatic triglyceride (TG), serum interleukin-6 (IL-6), and serum tumor necrosis factor (TNF)-α levels were 1-4 times higher than those in LFD mice (P < 0.05); they were 34-42% lower in HSB mice compared with HFD mice (P < 0.05). The HFD group had 28%-48% lower mRNA expression of both Tjp1 and Ocln in the ileum and colon compared with levels in LFD or HSB mice (P < 0.05), whereas there was no difference in expression levels between LFD and HSB mice. Furthermore, in HSB mice, serum LPS concentration was 53% lower compared with that in HFD mice but still 23% higher than that in LFD mice (P < 0.05). Results from principal component analysis showed that HSB and LFD mice had a similar gut microbiota structure, which was significantly different from that in HFD mice (P < 0.05).

CONCLUSIONS

Sodium butyrate administration beneficially changed HFD-induced gut microbiota composition and improved intestinal barrier, leading to lower serum LPS concentrations. These changes may correspond with improvements in obesity-related lipid accumulation and low-grade chronic inflammation.

Grape Seed Proanthocyanidins Target the Enteroendocrine System in Cafeteria-Diet-Fed Rats

SCOPE

The effects on the enteroendocrine system of three different grape seed proanthocyanidin extract (GSPE) treatments are analyzed in rats on a cafeteria diet for 17 weeks.

METHODS AND RESULTS

GSPE is administered in a corrective manner (15 last days of the cafeteria diet) at two doses, 100 and 500 mg GSPE per kg bw. A third, longer treatment in which GSPE (500 mg kg^-1 bw) is administered daily every other week during the 17 weeks of the cafeteria diet is also tested. Most GSPE treatments lead to ghrelin accumulation in the stomach, limited CCK secretion in the duodenum, and increased GLP-1 and PYY mRNA in colon. GSPE also increases cecal hypertrophy and reduces butyrate content. When the treatment is administered daily every other week during 17 weeks, there is also an increase in colon size. These effects are accompanied by a reduced food intake at the end of the experiment when GSPE is administered at 500 mg GSPE kg^-1 during the last 15 days, but not on the other treatments, despite an observed reduction in body weight in the longer treatment.

CONCLUSION

GSPE modulates the enteroendocrine system in models in which it also reduces food intake or body weight.

Immune-endocrine interactions related to a high risk of infections in chronic metabolic diseases: The role of PPAR gamma

Diverse disturbances in immune-endocrine circuitries are involved in the development and aggravation of several chronic metabolic diseases (CMDs), including obesity, diabetes, and metabolic syndrome. The chronic inflammatory syndrome observed in CMDs culminates in dysregulated immune responses with low microbial killing efficiency, by means low host innate immune response, and loss of ability to eliminate the pathogens, which results in a high prevalence of infectious diseases, including pneumonia, tuberculosis, and sepsis. Herein, we review evidence pointing out PPARγ as a putative player in immune-endocrine disturbances related to increased risk of infections in CMDs. Cumulated evidence indicates that PPARγ activation modulates host cells to control inflammation during CMDs because of PPARγ agonists have anti-inflammatory and pro-resolutive properties, increasing host ability to eliminate pathogen, modulating hormone production, and restoring glucose and lipid homeostasis. As such, we propose PPARγ as a putative therapeutic adjuvant for patients with CMDs to favor a better infection control.

Momordica charantia (bitter melon) modulates adipose tissue inflammasome gene expression and adipose-gut inflammatory cross talk in high-fat diet (HFD)-fed mice

Systemic and tissue-specific inflammation has a profound influence on regulation of metabolism, and therefore, strategies to reduce inflammation are of special interest in prevention and treatment of obesity and type 2 diabetes (T2D). Antiobesity and antidiabetic properties of Momordica charantia (bitter melon, BM) have been linked to its protective effects on inflammation and gut microbial dysbiosis. We investigated the mechanisms by which freeze-dried BM juice reduces adipose inflammation in mice fed a 60% high-fat diet (HFD) for 16 weeks. Although earlier studies indicated that BM inhibited recruitment of macrophages (Mφ) infiltration in adipose tissue of rodents and reduced NF-kB and IL-1β secretions, the mechanisms remain unknown. We demonstrate that freeze-dried BM juice inhibits recruitment of Mφ into adipose tissue and its polarization to inflammatory phenotype possibly due to reduction of sphingokinase 1 (SPK1) mRNA in HFD-fed mice. Furthermore, reduction of IL-1β secretion by freeze-dried BM juice in the adipose tissue of HFD-fed mice is correlated to alleviation of NLRP3 inflammasome components and their downstream signaling targets. We confirm previous observations that BM inhibited inflammation of colon and gut microbial dysbiosis in HFD-fed mice, which in part may be associated with the observed anti-inflammatory effects in adipose tissue if HFD-fed mice. Overall, functional foods such as BM may offer potential dietary interventions that may impact sterile inflammatory diseases such as obesity and T2D.

ECEIM consensus statement on equine metabolic syndrome

Equine metabolic syndrome (EMS) is a widely recognized collection of risk factors for endocrinopathic laminitis. The most important of these risk factors is insulin dysregulation (ID). Clinicians and horse owners must recognize the presence of these risk factors so that they can be targeted and controlled to reduce the risk of laminitis attacks. Diagnosis of EMS is based partly on the horse's history and clinical examination findings, and partly on laboratory testing. Several choices of test exist which examine different facets of ID and other related metabolic disturbances. EMS is controlled mainly by dietary strategies and exercise programs that aim to improve insulin regulation and decrease obesity where present. In some cases, pharmacologic aids might be useful. Management of an EMS case is a long‐term strategy requiring diligence and discipline by the horse's carer and support and guidance from their veterinarians.

A Data Integration Multi-Omics Approach to Study Calorie Restriction-Induced Changes in Insulin Sensitivity

Background: The mechanisms responsible for calorie restriction (CR)-induced improvement in insulin sensitivity (IS) have not been fully elucidated. Greater insight can be achieved through deep biological phenotyping of subjects undergoing CR, and integration of big data. Materials and Methods: An integrative approach was applied to investigate associations between change in IS and factors from host, microbiota, and lifestyle after a 6-week CR period in 27 overweight or obese adults (ClinicalTrials.gov: NCT01314690). Partial least squares regression was used to determine associations of change (week 6 - baseline) between IS markers and lifestyle factors (diet and physical activity), subcutaneous adipose tissue (sAT) gene expression, metabolomics of serum, urine and feces, and gut microbiota composition. ScaleNet, a network learning approach based on spectral consensus strategy (SCS, developed by us) was used for reconstruction of biological networks. Results: A spectrum of variables from lifestyle factors (10 nutrients), gut microbiota (10 metagenomics species), and host multi-omics (metabolic features: 84 from serum, 73 from urine, and 131 from feces; and 257 sAT gene probes) most associated with IS were identified. Biological network reconstruction using SCS, highlighted links between changes in IS, serum branched chain amino acids, sAT genes involved in endoplasmic reticulum stress and ubiquitination, and gut metagenomic species (MGS). Linear regression analysis to model how changes of select variables over the CR period contribute to changes in IS, showed greatest contributions from gut MGS and fiber intake. Conclusion: This work has enhanced previous knowledge on links between host glucose homeostasis, lifestyle factors and the gut microbiota, and has identified potential biomarkers that may be used in future studies to predict and improve individual response to weight-loss interventions. Furthermore, this is the first study showing integration of the wide range of data presented herein, identifying 115 variables of interest with respect to IS from the initial input, consisting of 9,986 variables. Clinical Trial Registration: clinicaltrials.gov (NCT01314690).

Synbiotic-driven improvement of metabolic disturbances is associated with changes in the gut microbiome in diet-induced obese mice

OBJECTIVE

The gut microbiota is an important influencing factor of metabolic health. Although dietary interventions with probiotics, prebiotics, and synbiotics can be effective means to regulate obesity and associated comorbidities, the underlying shifts in gut microbial communities, especially at the functional level, have not been characterized in great details. In this study, we sought to investigate the effects of synbiotics on the regulation of gut microbiota and the alleviation of high-fat diet (HFD)-induced metabolic disorders in mice.

METHODS

Specific pathogen-free (SPF) male C57BL/6J mice were fed diets with either 10% (normal diet, ND) or 60% (high-fat diet, HFD) of total calories from fat (lard). Dietary interventions in the HFD-fed mice included (i) probiotic (Bifidobacterium animalis subsp. lactis and Lactobacillus paracasei subsp. paracasei DSM 46331), (ii) prebiotic (oat β-glucan), and (iii) synbiotic (a mixture of i and ii) treatments for 12 weeks. Besides detailed characterization of host metabolic parameters, a multi-omics approach was used to systematically profile the microbial signatures at both the phylogenetic and functional levels using 16S rRNA gene sequencing, metaproteomics and targeted metabolomics analysis.

RESULTS

The synbiotic intervention significantly reduced body weight gain and alleviated features of metabolic complications. At the phylogenetic level, the synbiotic treatment significantly reversed HFD-induced changes in microbial populations, both in terms of richness and the relative abundance of specific taxa. Potentially important species such as Faecalibaculum rodentium and Alistipes putredinis that might mediate the beneficial effects of the synbiotic were identified. At the functional level, short-chain fatty acid and bile acid profiles revealed that all dietary interventions significantly restored cecal levels of acetate, propionate, and butyrate, while the synbiotic treatment reduced the bile acid pools most efficiently. Metaproteomics revealed that the effects of the synbiotic intervention might be mediated through metabolic pathways involved in carbohydrate, amino acid, and energy metabolisms.

CONCLUSIONS

Our results suggested that dietary intervention using the novel synbiotic can alleviate HFD-induced weight gain and restore gut microbial ecosystem homeostasis phylogenetically and functionally.

Metabolic endotoxemia promotes adipose dysfunction and inflammation in human obesity

Impaired adipose tissue (AT) lipid handling and inflammation is associated with obesity-related metabolic diseases. Circulating lipopolysaccharides (LPSs) from gut microbiota (metabolic endotoxemia), proposed as a triggering factor for the low-grade inflammation in obesity, might also be responsible for AT dysfunction. Nevertheless, this hypothesis has not been explored in human obesity. To analyze the relationship between metabolic endotoxemia and AT markers for lipogenesis, lipid handling, and inflammation in human obesity, 33 patients with obesity scheduled for surgery were recruited and classified according to their LPS levels. Visceral and subcutaneous AT gene and protein expression were analyzed and adipocyte and AT in vitro assays performed. Subjects with obesity with a high degree of metabolic endotoxemia had lower expression of key genes for AT function and lipogenesis ( SREBP1, FABP4, FASN, and LEP) but higher expression of inflammatory genes in visceral and subcutaneous AT than subjects with low LPS levels. In vitro experiments corroborated that LPS are responsible for adipocyte and AT inflammation and downregulation of PPARG, SCD, FABP4, and LEP expression and LEP secretion. Thus, metabolic endotoxemia influences AT physiology in human obesity by decreasing the expression of factors involved in AT lipid handling and function as well as by increasing inflammation.