Gut Microbiota and Obesity

Obesity aggravates contact hypersensitivity reaction in mice

BACKGROUND

Obesity is associated with chronic, low-grade inflammation in tissues and predisposes to various complications, including inflammatory skin diseases. However, the link between obesity and contact hypersensitivity (CHS) is not fully understood.

OBJECTIVES

We sought to determine the influence of obesity on T helper 1 (Th1)-mediated CHS.

METHODS

The activity/phenotype/cytokine profile of the immune cells was tested in vivo and in vitro. Using quantitative polymerase chain reaction (qPCR) and fecal microbiota transplantation (FMT), we tested the role of a high-fat diet (HFD)-induced gut microbiota (GM) dysbiosis in increasing the effects of CHS.

RESULTS

Exacerbated CHS correlates with an increased inflammation-inducing GM in obese mice. We showed a proinflammatory milieu in the subcutaneous adipose tissue of obese mice, accompanied by proinflammatory CD4+ T cells and dendritic cells in skin draining lymph nodes and spleen. Obese interleukin (IL)-17A-/-B6 mice are protected from CHS aggravation, suggesting the importance of IL-17A in CHS aggravation in obesity.

CONCLUSIONS

Obesity creates a milieu that induces more potent CHS-effector cells but does not have effects on already activated CHS-effector cells. IL-17A is essential for the pathogenesis of enhanced CHS during obesity. Our study provides novel knowledge about antigen-specific responses in obesity, which may help with the improvement of existing treatment and/or in designing novel treatment for obesity-associated skin disorders.

Impact of feeding regimens on the composition of gut microbiota and metabolite profiles of plasma and feces from Mongolian sheep

Mongolian sheep are an indigenous ruminant raised for wool and meat production in China. The gut microbial community plays an important role in animal performance and metabolism. The objective of this study was to investigate the effects of two feeding regimens on the diversity and composition of gut microbiota and metabolite profiles of feces and plasma from Mongolian sheep. A total of 20 Mongolian sheep were assigned to one of two feeding regimens: free grazing (FG) and barn confinement (BC). When samples were collected, the average live weights of the sheep were 31.28 ± 1.56 kg and 34.18 ± 1.87 kg for the FG and BC groups, respectively. At the genus level, the FG group showed higher levels of Bacteroides, RC9_gut_group, Alistipes, Phocaeicola, Barnesiella, and Oscillibacter, and lower levels of Succinivibrio, Treponema, and Prevotella, compared to the BC group. The butyric acid content in feces was lower in the FG group (P > 0.05). Higher levels of palmitic acid, oleic acid, alpha-linolenic acid, L-carnitine, L-citrulline, and L-histidine, and lower levels of L-tyrosine, L-phenylalanine, and L-kynurenine were found in the plasma of the FG sheep. Moreover, there were substantial associations between several gut microbiota genera and alterations in feces and plasma metabolites especially those involved in the metabolism of butyric acid, linolenic acid, and L-tyrosine. Feeding regimens can not only influence the composition of gut microbiota, but also alter metabolic homeaostasis in sheep.

Breast Cancer: Lifestyle, the Human Gut Microbiota/Microbiome, and Survivorship

Patients with a current diagnosis of breast cancer are enjoying dramatic cure rates and survivorship secondary to an increase in awareness, earlier detection, and more effective therapies. Although strategies such as Breast Cancer Awareness Month in October focus on early detection, lifestyle changes are seldom discussed other than dietary concerns and physical activity. Lifestyle modifications centered on diet and exercise have been demonstrated to affect overall disease-free survival in breast cancer. Since the early 2000s, the role of the human gut microbiota and its relation to breast cancer has become a major area of interest in the scientific and medical community. We live and survive owing to the symbiotic relationship with the microorganisms within us: the human microbiota. Scientific advances have identified a subset of the gut microbiota: the estrobolome, those bacteria that have the genetic capability to metabolize estrogen, which plays a key role in most breast cancers. Recent research provides evidence that the gut microbiome plays a substantial role in estrogen regulation. Gut microbiota diversity appears to be an essential component of overall health, including breast health. Future research attention should include a more extensive focus on the role of the human gut microbiota in breast cancer.

Role of Selenoproteins in Bacterial Pathogenesis

The trace element selenium is an essential micronutrient that plays an important role in maintaining homeostasis of several tissues including the immune system of mammals. The vast majority of the biological functions of selenium are mediated via selenoproteins, proteins which incorporate the selenium-containing amino acid selenocysteine. Several bacterial infections of humans and animals are associated with decreased levels of selenium in the blood and an adjunct therapy with selenium often leads to favorable outcomes. Many pathogenic bacteria are also capable of synthesizing selenocysteine suggesting that selenoproteins may have a role in bacterial physiology. Interestingly, the composition of host microbiota is also regulated by dietary selenium levels. Therefore, bacterial pathogens, microbiome, and host immune cells may be competing for a limited supply of selenium. Elucidating how selenium, in particular selenoproteins, may regulate pathogen virulence, microbiome diversity, and host immune response during a bacterial infection is critical for clinical management of infectious diseases.

The flavonoid-rich Quzhou Fructus Aurantii extract modulates gut microbiota and prevents obesity in high-fat diet-fed mice

Background

Flavonoids are reported to modulate the composition of gut microbiota, which play an important role in preventing obesity and associated metabolic diseases. In this study, we investigated the effect of Total Flavonoids of Quzhou Fructus Aurantii Extract (TFQ) on gut microbial community in mice fed with a high-fat diet (HFD).

Methods

C57BL/6J mice were fed with either a chow diet or HFD with or without oral gavage of TFQ (300 mg/kg/day) for 12 weeks.

Results

Our data indicate TFQ significantly reduced obesity, inflammatio,n and liver steatosis. TFQ elevates the expression of tight junction proteins and reduces metabolic endotoxemia. In addition, TFQ treatment reverses HFD-induced gut dysbiosis, as indicated by the reduction of Firmicutes to Bacteroidetes ratio, the increase of genera Akkermansia and Alistipes, and the decrease of genera Dubosiella, Faecalibaculum, and Lactobacillus.

Conclusion

These findings support a prebiotic role of TFQ as a dietary supplement for the intervention of gut dysbiosis and obesity-related metabolic disorders.

Effect of alcohol tincture of Aralia elata on the organism of rats and their gut microbiota against the background of excessive fat diet

Pharmacological effects of the medicinal plant Aralia elata (Miq.) Seem. 1868 (Araliaceae) are related to presence of over 150 secondary metabolites, including flavonoids, sterols, polysaccharides, terpenoid saponins and terpenoid acids, though the main biologically active substances of A. elata are saponins and flavonoids. Some clinical tests and experimental studies have proved the influence of A. elata on the organism through increase in physical work capacity, exerting an anti-stress effect against a broad range of harmful factors, including stress from cold, immobilization, ultraviolet radiation and low pressure. The literature also reports the anti-ulcer, anti-secretory, antifungal, anti-tumour, and antimicrobial activity of preparations from this plant. In our laboratory experiment, we determined that ethanolic tincture of A. elata has no effect on the intensity of growth of body weight of young rats against the background of excessive content of fat in their diet. Excessive fat-feeding of male rats leads mostly to disorders in the functioning of the liver and development of steatosis. This was accompanied by reduction in relative mass of the liver, increase in activity of hepatic enzymes, dysproteinemia, increase in the level of bilirubin and decrease in the level of urea. Additional use of 0.1% ethanol led to impaired functioning of the kidneys, reduction of their relative mass, signs of dehydration, increase in the level of creatinine and total calcium in the blood. Use of ethanolic tincture of A. elata mitigates negative excess of fat, is accompanied by normalization of indices of mass of the organs, less notable dysproteinemia, impairment in the level of creatinine, glucose, urea, cholesterol, bilirubin and total calcium. Ethanolic tincture of A. elata has a low immunosuppressive action, against the background of a high fat diet it leads to increase in the amount of typical Escherichia сoli, decrease in Еnterococcus spp. and Enterobacter spp., significant decrease and in high concentrations (0.1% ethanolic tincture of A. elata) elimination of bacteria of Clostridium and Klebsiella genera, and also various yeast fungi in the intestine. In the examined male rats, against the background of excess of fat in the diet, no serious changes in the composition of the normal gut microbiota (Bifidobacterium spp., Lactobacillus spp., Proteus spp., Staphylococcus spp., Candida spp.) was observed, nor were any lactose-negative enterobacteria (Citrobacter genus) found. Perspectives of further research include determining histological, histochemical and immune-histological changes in the organs of laboratory animals under the effect of ethanolic tincture of A. elata following excessive accumulation of fat.

Suppression of Obesity by an Intestinal Helminth through Interactions with Intestinal Microbiota

Obesity is increasingly causing lifestyle diseases in developed countries where helminthic infections are rarely seen. Here, we investigated whether an intestinal nematode, Heligmosomoides polygyrus, has a suppressive role in diet-induced obesity in mice. Infection with H. polygyrus suppressed weight gain in obese mice, which was associated with increased uncoupling protein 1 (UCP1) expression in adipocytes and a higher serum norepinephrine (NE) concentration. Blocking interactions of NE with its receptor on adipocytes resulted in the failure to prevent weight gain and to enhance UCP1 expression in obese mice infected with H. polygyrus, indicating that NE is responsible for the protective effects of H. polygyrus on obesity. In addition to sympathetic nerve-derived NE, the intestinal microbiota was involved in the increase in NE. Infection with H. polygyrus altered the composition of intestinal bacteria, and antibiotic treatment to reduce intestinal bacteria reversed the higher NE concentration, UCP1 expression, and prevention of the weight gain observed after H. polygyrus infection. Our data indicate that H. polygyrus exerts suppressive roles on obesity through modulation of microbiota that produce NE.

High dietary fat intake induces a microbiota signature that promotes food allergy

BACKGROUND

Diet-induced obesity and food allergies increase in tandem, but a potential cause-and-effect relationship between these diseases of affluence remains to be tested.

OBJECTIVE

We sought to test the role of high dietary fat intake, diet-induced obesity, and associated changes in gut microbial community structure on food allergy pathogenesis.

METHODS

Mice were fed a high-fat diet (HFD) for 12 weeks before food allergen sensitization on an atopic dermatitis-like skin lesion, followed by intragastric allergen challenge to induce experimental food allergy. Germ-free animals were colonized with a signature HFD or lean microbiota for 8 weeks before induction of food allergy. Food-induced allergic responses were quantified by using a clinical allergy score, serum IgE levels, serum mouse mast cell protease 1 concentrations, and type 2 cytokine responses. Accumulation of intestinal mast cells was examined by using flow cytometry and chloroacetate esterase tissue staining. Changes in the gut microbial community structure were assessed by using high-throughput 16S ribosomal DNA gene sequencing.

RESULTS

HFD-induced obesity potentiates food-induced allergic responses associated with dysregulated intestinal effector mast cell responses, increased intestinal permeability, and gut dysbiosis. An HFD-associated microbiome was transmissible to germ-free mice, with the gut microbial community structure of recipients segregating according to the microbiota input source. Independent of an obese state, an HFD-associated gut microbiome was sufficient to confer enhanced susceptibility to food allergy.

CONCLUSION

These findings identify HFD-induced microbial alterations as risk factors for experimental food allergy and uncouple a pathogenic role of an HFD-associated microbiome from obesity. Postdieting microbiome alterations caused by overindulgence of dietary fat might increase susceptibility to food allergy.

Effect of Marine Microalga Chlorella pyrenoidosa Ethanol Extract on Lipid Metabolism and Gut Microbiota Composition in High-Fat Diet-Fed Rats

Effects of marine microalga Chlorella pyrenoidosa 55% ethanol extract (CPE55) on lipid metabolism, gut microbiota and regulation mechanism in high fat diet-fed induced hyperlipidaemia rats were investigated. Structure characterizations of major compounds in CPE55 were determined by ultra-performance liquid chromatography-quadrupole/time of flight mass spectrometry (UPLC-Q-TOF-MS/MS). The compositions of gut microbiota in rats were analyzed by high-throughput next-generation 16S rRNA gene sequencing. Oral administration with CPE55 markedly alleviated dyslipidemia through improving adverse blood lipid profile and inhibiting hepatic lipid accumulation and steatosis. CPE55 has downregulated the gene expression levels of acetyl CoA carboxylase, sterol regulatory element-binding transcription factor-1c, and 3-hydroxy-3-methyl glutaryl coenzyme A reductase and upregulated adenosine 5'-monophosphate-activated protein kinase-α. It has also improved the abundance of bacteria Alistipes, Prevotella, Alloprevotella, and Ruminococcus1 and decreased the abundances of Turicibacter and Lachnospira. Turicibacter and Lachnospira were both positive correlations of metabolic phenotypes. The findings above illustrated that CPE55 might be developed as food ingredients to ameliorate lipid metabolic disorders and hyperlipidaemia.

Role of the Gut⁻Liver Axis in Driving Parenteral Nutrition-Associated Injury

For decades, parenteral nutrition (PN) has been a successful method for intravenous delivery of nutrition and remains an essential therapy for individuals with intolerance of enteral feedings or impaired gut function. Although the benefits of PN are evident, its use does not come without a significant risk of complications. For instance, parenteral nutrition-associated liver disease (PNALD)—a well-described cholestatic liver injury—and atrophic changes in the gut have both been described in patients receiving PN. Although several mechanisms for these changes have been postulated, data have revealed that the introduction of enteral nutrition may mitigate this injury. This observation has led to the hypothesis that gut-derived signals, originating in response to the presence of luminal contents, may contribute to a decrease in damage to the liver and gut. This review seeks to present the current knowledge regarding the modulation of what is known as the “gut–liver axis” and the gut-derived signals which play a role in PN-associated injury.

Genotype-by-sex-by-diet interactions for nutritional preference, dietary consumption, and lipid deposition in a field cricket

Changes in feeding behaviour, especially the overconsumption of calories, has led to a rise in the rates of obesity, diabetes, and other associated disorders in humans and a range of animals inhabiting human-influenced environments. However, understanding the relative contribution of genes, the nutritional environment, and their interaction to dietary intake and lipid deposition in the sexes still remains a major challenge. By combining nutritional geometry with quantitative genetics, we determined the effect of genes, the nutritional environment, and their interaction on the total nutritional preference (TP), total diet eaten (TE), and lipid mass (LM) of male and female black field crickets (Teleogryllus commodus) fed one of four diet pairs (DPs) differing in the ratio of protein to carbohydrate and total nutritional content. We found abundant additive genetic variance for TP, TE, and LM in both sexes and across all four DPs, with significant genetic correlations between TE and TP and between TP and LM in males. We also found significant genotype-by-DP and genotype-by-sex-by-DP interactions for each trait and significant genotype-by-sex interactions for TE and LM. Complex interactions between genes, sex, and the nutritional environment, therefore, play an important role in nutrient regulation and lipid deposition in T. commodus. This finding may also help explain the increasing rate of obesity and the maintenance of sex differences in obesity observed across many animal species, including humans.

Connecting homocysteine and obesity through pyroptosis, gut microbiome, epigenetics, peroxisome proliferator-activated receptor γ, and zinc finger protein 407

Although homocysteine (Hcy), a part of the epigenome, contributes to cell death by pyroptosis and decreases peroxisome proliferator-activated receptor γ (PPARγ) levels, the mechanisms are unclear. Hcy is found in high concentrations in the sera of obese individuals, which can elicit an immune response as well by hypermethylating CpG islands of specific gene promoters, a marker of epigenetics. Hcy has also been established to chelate divalent metal ions like Cu²⁺ and Zn²⁺, but this role of Hcy has not been established in relationship with obesity. It has been known for a while that PPARγ dysregulation results in various metabolic disorders including glucose and lipid metabolism. Recently, zinc finger protein 407 (Zfp407) is reported to regulate PPARγ target gene expression without affecting PPARγ transcript and protein levels by synergistically working with PPARγ. However, the mechanism(s) of this synergy, as well as other factors contributing to or inhibiting this synergism, have not been proven. This review suggests that Hcy contributes to pyroptosis, changes gut microbiome, and alters PPARγ-dependent mechanism(s) via Zfp407-mediated upregulated adipogenesis and misbalanced fatty acid metabolism, which can predispose to obesity and, consequently, obesity-related metabolic disorders.

A Walnut-Enriched Diet Affects Gut Microbiome in Healthy Caucasian Subjects: A Randomized, Controlled Trial

Regular walnut consumption is associated with better health. We have previously shown that eight weeks of walnut consumption (43 g/day) significantly improves lipids in healthy subjects. In the same study, gut microbiome was evaluated. We included 194 healthy subjects (134 females, 63 ± 7 years, BMI 25.1 ± 4.0 kg/m²) in a randomized, controlled, prospective, cross-over study. Following a nut-free run-in period, subjects were randomized to two diet phases (eight weeks each); 96 subjects first followed a walnut-enriched diet (43 g/day) and then switched to a nut-free diet, while 98 subjects followed the diets in reverse order. While consuming the walnut-enriched diet, subjects were advised to either reduce fat or carbohydrates or both to account for the additional calories. Fecal samples were collected from 135 subjects at the end of the walnut-diet and the control-diet period for microbiome analyses. The 16S rRNA gene sequencing data was clustered with a 97% similarity into Operational Taxonomic Units (OTUs). UniFrac distances were used to determine diversity between groups. Differential abundance was evaluated using the Kruskal–Wallis rank sum test. All analyses were performed using Rhea. Generalized UniFrac distance shows that walnut consumption significantly affects microbiome composition and diversity. Multidimensional scaling (metric and non-metric) indicates dissimilarities of approximately 5% between walnut and control (p = 0.02). The abundance of Ruminococcaceae and Bifidobacteria increased significantly (p < 0.02) while Clostridium sp. cluster XIVa species (Blautia; Anaerostipes) decreased significantly (p < 0.05) during walnut consumption. The effect of walnut consumption on the microbiome only marginally depended on whether subjects replaced fat, carbohydrates or both while on walnuts. Daily intake of 43 g walnuts over eight weeks significantly affects the gut microbiome by enhancing probiotic- and butyric acid-producing species in healthy individuals. Further evaluation is required to establish whether these changes are preserved during longer walnut consumption and how these are linked to the observed changes in lipid metabolism.

Antiobesity molecular mechanisms of action: Resveratrol and pterostilbene

Obesity is a current global epidemic that has led to a marked increase in metabolic diseases. However, its treatment remains a challenge. Obesity is a multifactorial disease, which involves the dysfunction of neuropeptides, hormones, and inflammatory adipokines from the brain, gut, and adipose tissue. An understanding of the mechanisms and signal interactions in the crosstalk between organs and tissue in the coordination of whole-body energy metabolism would be helpful to provide therapeutic and putative approaches to the treatment and prevention of obesity and related complications. Resveratrol and pterostilbene are well-known stilbenes that provide various potential benefits to human health. In particular, their potential anti-obesity effects have been proven in numerous cell culture and animal studies. Both compounds act to regulate energy intake, adipocyte life cycle and function, white adipose tissue (WAT) inflammation, energy expenditure, and gut microbiota by targeting multiple molecules and signaling pathways as an intervention for obesity. Although the efficacy of both compounds in humans requires further investigation with respect to their oral bioavailability, promising scientific findings have highlighted their potential as candidates for the treatment of obesity and the improvement of obesity-related metabolic diseases. © 2018 BioFactors, 44(1):50-60, 2018.

Does pet-keeping modify the association of delivery mode with offspring body size?

Caesarean-section (CS) delivery increases risk of childhood obesity, and is associated with a distinct early-life gut microbiome, which may contribute to obesity. Household pets may alter human gut microbiome composition. We examined if pet-keeping modified the association of CS with obesity at age 2 years in 639 Wayne County Health, Environment, Allergy and Asthma Longitudinal Study birth cohort participants. Pet-keeping was defined as having a dog or cat (indoors ≥1 h/day) at child age 2 years. We used logistic regression to test for an interaction between CS and pet-keeping with obesity (BMI ≥ 95th percentile) at age 2 years, adjusted for maternal obesity. A total of 328 (51.3 %) children were male; 367 (57.4 %) were African American; 228 (35.7 %) were born by CS; and 55 (8.6 %) were obese. After adjusting for maternal obesity, CS-born children had a non-significant (P = 0.25) but elevated 1.4 (95 % CI 0.8, 2.5) higher odds of obesity compared to those born vaginally. There was evidence of effect modification between current pet-keeping and delivery mode with obesity at age 2 years (interaction P = 0.054). Compared to children born vaginally without a pet currently in the home, children born via CS without a pet currently in the home had a statistically significant (P = 0.043) higher odds (odds ratio 2.00; 95 % CI 1.02, 3.93) of being obese at age 2 years. Pets modified the CS-BMI relationship; whether the underlying mechanism is through effects on environmental or gut microbiome requires specific investigation.

A review on possible therapeutic targets to contain obesity: The role of phytochemicals

The prevalence and severity of obesity has increased markedly in recent decades making it a global public health concern. Since obesity is a potential risk factor in the development of hypertension, type-2 diabetes, cardiovascular diseases, infertility, etc., it is no more viewed as a cosmetic issue. Currently, only a few FDA-approved anti-obesity drugs like Orlistat, Lorcaserin and Phentermine-topiramate are available in the market, but they have considerable side effects. On the other hand, bariatric surgery as an alternative is associated with high risk and expensive. In view of these there is a growing trend towards natural product-based drug intervention as one of the crucial strategies for management of obesity and related ailments. In Asian traditional medicine and Ayurvedic literature a good number of plant species have been used and quoted for possible lipid-lowering and anti-obesity effects; however, many of them have not been evaluated rigorously for a definite recommendation and also lack adequate scientific validation. This review explores and updates on various plant species, their used parts, bioactive components and focuses multiple targets/pathways to contain obesity which may pave the way to develop novel and effective drugs. We also summarised different drugs in use to treat obesity and their current status. Nature is future promise of our wellbeing.

Insights into environmental factors impacting celiac disease: microbiota modulation of disease pathogenesis

This commentary highlights the article by Galipeau et al exploring the role of microbiota in modulating gluten immune response and celiac disease-like pathology in a humanized mouse model.

Evaluation of immune response, microbiota, and blood markers after probiotic bacteria administration in obese mice induced by a high-fat diet

OBJECTIVE

Obesity is associated with alterations in intestinal microbiota and immunity. The aim of this study was to determine the effect of probiotic Lactobacillus casei CRL 431 administration on intestinal and humoral immune response, clinical parameters, and gut microbiota was evaluated using a high-fat diet to induce obesity in a mouse model.

METHODS

Adult mice received a conventional balanced diet or a high-fat diet supplemented with milk, milk fermented by Lactobacillus casei (FM), L. casei as suspension, or water over 60 d. Histology of liver and small intestine (SI), immunoglobulin A-positive cells and macrophages in SI, phagocytic activity of spleen and peritoneal macrophages, and humoral immune response to ovalbumin were studied. Clinical parameters in serum and gut microbiota were also analyzed.

RESULTS

FM was the most effective supplement for decreasing body weight and clinical parameters in serum. The histology of liver and SI was also improved in obese mice given FM. These animals had increased numbers of immunoglobulin A-positive cells and macrophages in SI. The gut microbiota showed that obese mice given probiotics had increased Bacteroides and bifidobacteria. Administration of FM or L. casei as suspension enhanced the phagocytic activity of macrophages. The anti-ovalbumin specific immune response was not increased by any supplement assayed.

CONCLUSION

Administration of probiotics to obese hosts improved the gut microbiota and the mucosal immunity altered by obesity, down-regulated some biochemical parameters in blood associated with metabolic syndrome, and decreased liver steatosis. These results demonstrate the potential use of probiotics in obese individuals to decrease the body weight and to improve the biochemical and immunologic parameters altered by obesity.

Gastric electrical stimulation for the treatment of obesity: from entrainment to bezoars-a functional review

GROWING WORLDWIDE OBESITY EPIDEMIC HAS PROMPTED THE DEVELOPMENT OF TWO MAIN TREATMENT STREAMS: (a) conservative approaches and (b) invasive techniques. However, only invasive surgical methods have delivered significant and sustainable benefits. Therefore, contemporary research exploration has focused on the development of minimally invasive gastric manipulation methods featuring a safe but reliable and long-term sustainable weight loss effect similar to the one delivered by bariatric surgeries. This antiobesity approach is based on placing external devices in the stomach ranging from electrodes for gastric electrical stimulation to temporary intraluminal bezoars for gastric volume displacement for a predetermined amount of time. The present paper examines the evolution of these techniques from invasively implantable units to completely noninvasive patient-controllable implements, from a functional, rather than from the traditional, parametric point of view. Comparative discussion over the available pilot and clinical studies related to gastric electrical stimulation outlines the promises and the fallacies of this concept as a reliable alternative anti-obesity strategy.