The Gut-Brain Axis, the Human Gut Microbiota and Their Integration in the Development of Obesity

Gut Microbiome, Intestinal Permeability, and Tissue Bacteria in Metabolic Disease: Perpetrators or Bystanders?

The emerging evidence on the interconnectedness between the gut microbiome and host metabolism has led to a paradigm shift in the study of metabolic diseases such as obesity and type 2 diabetes with implications on both underlying pathophysiology and potential treatment. Mounting preclinical and clinical evidence of gut microbiota shifts, increased intestinal permeability in metabolic disease, and the critical positioning of the intestinal barrier at the interface between environment and internal milieu have led to the rekindling of the "leaky gut" concept. Although increased circulation of surrogate markers and directly measurable intestinal permeability have been linked to increased systemic inflammation in metabolic disease, mechanistic models behind this phenomenon are underdeveloped. Given repeated observations of microorganisms in several tissues with congruent phylogenetic findings, we review current evidence on these unanticipated niches, focusing specifically on the interaction between gut permeability and intestinal as well as extra-intestinal bacteria and their joint contributions to systemic inflammation and metabolism. We further address limitations of current studies and suggest strategies drawing on standard techniques for permeability measurement, recent advancements in microbial culture independent techniques and computational methodologies to robustly develop these concepts, which may be of considerable value for the development of prevention and treatment strategies.

The impact of probiotics, prebiotics, and synbiotics on the biochemical, clinical, and immunological markers, as well as on the gut microbiota of obese hosts

Obesity is currently considered a global epidemic and it leads to several alterations on the human body and its metabolism. There are evidences showing that the intestinal microbiota can influence on the pathogenesis of obesity. Microbiota plays a vital role not only in the digestion and absorption of nutrients, but also in the homeostatic maintenance of host immunity, metabolism, and gut barrier. Its dietary alteration is an important target in the treatment of obesity. Emerging evidence suggests that modifying the composition of the gut microbiota through probiotic, prebiotic, and synbiotic supplementation may be a viable adjuvant treatment option for obese individuals. In this review, the impact of probiotics, prebiotics, and synbiotics on the anthropometric profile, biochemical regulation, clinical, and immunological markers, as well as on the gut microbiota of obese hosts is described. It also emphasizes how changes in the composition and/or metabolic activity of the gut microbiota through the administration of nutrients with probiotic, prebiotic, or synbiotic properties can modulate the host's gene expression and metabolism, and thereby positively influence on the host's adipose tissue development and related metabolic disorders. The beneficial effects on the host's metabolism promoted by prebiotics, probiotics, and synbiotics have been successfully demonstrated by several studies. However, further investigation is needed to fully explain the cellular mechanisms of action of probiotics and prebiotics on human health, and also to elucidate the relationship between microbiota and obesity etiology, using well-designed, long-term, and large-scale clinical interventions.

Hydroxycinnamic acids and human health: recent advances

There is an urgent need to improve human diet globally. Compelling evidence gathered over the past several decades suggests that a suboptimal diet is associated with many chronic diseases and may be responsible for more deaths than any other risks worldwide. The main components in our diet that need higher intake are whole grains, fruit and vegetables, and nuts and seeds; all of these are important sources of dietary fiber and polyphenols. The health benefits of dietary fiber and polyphenols are also supported by several decades of valuable research. However, the conclusions drawn from interventional human trials are not straightforward and the action mechanisms in improving human health are not fully understood. Moreover, there is a great inter-individual variation caused by different individual capabilities of processing, absorbing and using these compounds effectively. Data on the bioavailability and bioefficacy of hydroxycinnamic acids (HCAs) are limited when compared to other classes of polyphenols (e.g. anthocyanins). This review aims to summarize the latest research advances related to HCA bioavailability and their biological effects revealed by epidemiological data, pre-clinical and clinical studies. Moreover, we aim to review the effects of HCAs on gut microbiota diversity and function and its respective influence on host health. © 2019 Society of Chemical Industry.

The Role of Neuropeptide Y and Peptide YY in the Development of Obesity via Gut-brain Axis

Obesity is one of the main challenges of public health in the 21st century. Obesity can induce a series of chronic metabolic diseases, such as diabetes, dyslipidemia, hypertension and nonalcoholic fatty liver, which seriously affect human health. Gut-brain axis, the two-direction pathway formed between enteric nervous system and central nervous system, plays a vital role in the occurrence and development of obesity. Gastrointestinal signals are projected through the gut-brain axis to nervous system, and respond to various gastrointestinal stimulation. The central nervous system regulates visceral activity through the gut-brain axis. Brain-gut peptides have important regulatory roles in the gut-brain axis. The brain-gut peptides of the gastrointestinal system and the nervous system regulate the gastrointestinal movement, feeling, secretion, absorption and other complex functions through endocrine, neurosecretion and paracrine to secrete peptides. Both neuropeptide Y and peptide YY belong to the pancreatic polypeptide family and are important brain-gut peptides. Neuropeptide Y and peptide YY have functions that are closely related to appetite regulation and obesity formation. This review describes the role of the gutbrain axis in regulating appetite and maintaining energy balance, and the functions of brain-gut peptides neuropeptide Y and peptide YY in obesity. The relationship between NPY and PYY and the interaction between the NPY-PYY signaling with the gut microbiota are also described in this review.

[Glucagon-like peptide-1 (GLP1) and the gastrointestinal tract. GLP1 receptor agonists: overemphasized gastric, forgotten intestinal ("ileal brake") effect?]

Glucagon-like peptide-1 (GLP1) and their receptor agonists - beside their blood glucose lowering and central effects- affect also the gastrointestinal function in many respects. They slow down the stomach emptying, the motility of the small bowel and colon - this is the explanation for the "ileal brake" terminology -, stimulate the function of exocrine pancreatic acinar cells and increase amylase production. GLP1 receptor agonists belong to the defining tools of the blood glucose lowering therapy in type 2 diabetes. Their long- and short-acting derivatives have different influence on the fasting and the postprandial blood glucose, respectively. By introducing the term non-prandial and prandial type analogues - which seems to be forced in light of the newer data - the potential slowdown in gastric emptying is the center of interest, lately, however, especially in the case of long-acting GLP1 variants, at least such attention should be paid to controlling bowel function. The article reviews the physiological effects of GLP1 on the gastrointestinal tract and draws attention to the potential for the prevention of possible side effects through detailed patient information and dietary advises. Orv Hetil. 2019; 160(49): 1927-1934.

Recent Advances in the Neurobiology of Altered Motivation Following Bariatric Surgery

PURPOSE OF REVIEW

There is compelling evidence in the clinical population that long-term weight loss secondary to bariatric surgery is mitigated by the reemergence of maladaptive feeding behaviors and in some cases new onset substance abuse.

RECENT FINDINGS

A review of the current literature suggests that physical restructuring of the GI tract during WLS alters secretion of feeding peptides and nutrient-sensing mechanisms that directly target the brain's endogenous reward system, the mesolimbic dopamine system. Post-surgical changes in GI physiology augment activation of the mesolimbic system. In some patients, this process may contribute to a reduced appetite for palatable food whereas in others it may support maladaptive motivated behavior for food and chemical drugs. It is concluded that future studies are required to detail the timing and duration of surgical-induced changes in GI-mesolimbic communication to more fully understand this phenomenon.

Early-life high-fat diet-induced obesity programs hippocampal development and cognitive functions via regulation of gut commensal Akkermansia muciniphila

Obesity is one of the most serious public health challenges in the world. Obesity during early life has been associated with an increased risk of neurodevelopmental disorders, including deficits in learning and memory, yet the underlying mechanisms remain unclear. Here, we show that early life high-fat diet (HFD) feeding impairs hippocampus-dependent contextual/spatial learning and memory, and alters the gut microbiota, particularly by depleting Akkermansia muciniphila (A. muciniphila), in mice. Transplantation of the HFD microbiota confers hippocampus-dependent learning and memory deficits to mice fed a chow diet. Oral treatment of HFD-fed mice with the gut commensal A. muciniphila corrects gut permeability, reduces hippocampal microgliosis and proinflammatory cytokines (tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and IL-6) expression, and restores neuronal development and synapse plasticity, thus ameliorates defects in learning and memory. Interestingly, treatment of mice with lipopolysaccharide (LPS) mimics HFD-induced hippocampus-dependent cognitive impairment in chow-fed mice. In line with these findings, pharmacologic blockade of Toll-like receptor 4 (TLR4) signalling or antibiotics treatment both effectively prevent hippocampus-dependent learning and memory deficits in HFD-fed mice. Collectively, our findings demonstrate an unexpected pivotal role of gut microbiota in HFD-induced cognitive deficits and identify a potential probiotic therapy for obesity associated with cognitive dysfunction during early life.

Bridging intestinal immunity and gut microbiota by metabolites

The gastrointestinal tract is the site of nutrient digestion and absorption and is also colonized by diverse, highly mutualistic microbes. The intestinal microbiota has diverse effects on the development and function of the gut-specific immune system, and provides some protection from infectious pathogens. However, interactions between intestinal immunity and microorganisms are very complex, and recent studies have revealed that this intimate crosstalk may depend on the production and sensing abilities of multiple bioactive small molecule metabolites originating from direct produced by the gut microbiota or by the metabolism of dietary components. Here, we review the interplay between the host immune system and the microbiota, how commensal bacteria regulate the production of metabolites, and how these microbiota-derived products influence the function of several major innate and adaptive immune cells involved in modulating host immune homeostasis.

Health Benefits of Lactobacillus gasseri CP2305 Tablets in Young Adults Exposed to Chronic Stress: A Randomized, Double-Blind, Placebo-Controlled Study

Short-term administration of Lactobacillus gasseri CP2305 improves stress-associated symptoms and clinical symptoms in healthy young adults and in patients with irritable bowel syndrome, respectively. We evaluated the efficacy and health benefits of the long-term use of a tablet containing heat-inactivated, washed Lactobacillus gasseri CP2305 (CP2305) in healthy young adults. Sixty Japanese medical students (41 men and 19 women) preparing for the national examination for medical practitioners ingested CP2305-containing or placebo tablets once daily for 24 weeks. Intake of the CP2305 tablet significantly reduced anxiety and sleep disturbance relative to placebo, as quantitated by the Spielberger State-Trait Anxiety Inventory and the Pittsburgh Sleep Quality Index. Single-channel sleep electroencephalograms show that CP2305 significantly shortened sleep latency and wake time after sleep onset and increased the delta power ratio in the first sleep cycle. CP2305 also significantly lowered salivary chromogranin A levels compared with placebo. Furthermore, 16S rRNA gene sequencing of participant feces demonstrated that CP2305 administration attenuated the stress-induced decline of Bifidobacterium spp. and the stress-induced elevation of Streptococcus spp. We conclude that the long-term use of CP2305-containing tablets may improve the mental state, sleep quality, and gut microbiota of healthy adults under stressful conditions.

Acupuncture Regulating Gut Microbiota in Abdominal Obese Rats Induced by High-Fat Diet

Objective

To investigate the effects of acupuncture on metabolic health and gut microbiota dysbiosis in diet-induced abdominal obese model.

Materials and Methods

Male Sprague-Dawley rats were randomly distributed into normal chow diet (NCD) group and high-fat diet (HFD) group. After 12 weeks of HFD feeding, an abdominal obese rat model was established. The abdominal obese rats were further assigned to acupuncture group (n=7) and nontreated HFD group (n=7). Acupuncture was applied to bilateral GB 26 of rats for 8 weeks. Subsequently, the body weight, waist circumference (WC), visceral fat mass, and liver weight were measured weekly in all rats. Metabolic parameters such as total cholesterol, triglyceride, alanine aminotransferase, aspartate transaminase, and blood glucose were measured by an automatic biochemical analyzer. The serum levels of insulin (INS) were determined using Rat INS ELISA Kit. Analysis of gut microbiota was carried out by 16S rRNA gene sequencing.

Results

Acupuncture decreased the body weight, WC, and visceral adipose tissues of HFD-induced abdominal obese rats. In addition, insulin sensitivity, glucose homeostasis, and lipid metabolism were improved by this treatment. Furthermore, electroacupuncture effectively modified the composition of gut microbiota, mainly via decreasing Firmicutes/Bacteroidetes ratio and increasing Prevotella_9 abundance.

Conclusions

Electroacupuncture can ameliorate abdominal obesity and prevent metabolic disorders in HFD-induced abdominal obese rats, via the modulation of gut microbiota.

Gut microbiota: a new angle for traditional herbal medicine research

Traditional Herbal Medicine (THM) has been used for thousands of years, and is popular worldwide due to its effectiveness in a variety of diseases. THM has also formed the basis of the discovery of modern drugs like artemisinin and paclitaxel. However, at present, studies that focus on development in the field of THM are stagnant because currently, the effective ingredients in the herbal formulations and the ambiguity of the underlying mechanisms of action are unknown. In this review, we have investigated the studies available that focused on the efficacy, active ingredients and bioavailability of THM, and the function of gut microbiota in THM-mediated treatment of disease. We hypothesized that most THMs treat diseases via three mechanisms: (1) metabolizing into active metabolites by the action of gut microbiota, (2) regulation of gut microbiota balance, and (3) regulating the fermentation products of the gut microbes. Therefore, focusing on these aspects can help elucidate the pharmacodynamic constituents of THM preparations, and their therapeutic mechanisms of action.

Gut Microbiota and Energy Homeostasis in Fish

The microorganisms within the intestinal tract (termed gut microbiota) have been shown to interact with the gut-brain axis, a bidirectional communication system between the gut and the brain mediated by hormonal, immune, and neural signals. Through these interactions, the microbiota might affect behaviors, including feeding behavior, digestive/absorptive processes (e.g., by modulating intestinal motility and the intestinal barrier), metabolism, as well as the immune response, with repercussions on the energy homeostasis and health of the host. To date, research in this field has mostly focused on mammals. Studies on non-mammalian models such as fish may provide novel insights into the specific mechanisms involved in the microbiota-brain-gut axis. This review describes our current knowledge on the possible effects of microbiota on feeding, digestive processes, growth, and energy homeostasis in fish, with emphasis on the influence of brain and gut hormones, environmental factors, and inter-specific differences.

Adhesion Ileus after Fecal Microbiota Transplantation in Long-Standing Radiation Colitis

Fecal microbiota transplantation (FMT) is a novel strategy for the therapy of dysbiosis-associated disorders via modulation of the gut microbiota. Intestinal dysbiosis is associated not only with digestive disorders, but also with a variety of extra-digestive disorders. A worldwide increasing number of FMT can be expected in the future as well as an increase in adverse events. We describe the case of a patient with chronic radiation colitis that developed adhesion ileus 2 days after FMT. Since these problems never occured before and the short time interval favours a causality, we speculate about FMT-induced alterations in gut motility causing a “trapping” of the small intestine in an adhesion and other mechanisms beyond “pure” coincidence.

Obesity and Socioeconomic Disparities: Rethinking Causes and Perinatal Care

Obesity affects more than 35% of women aged 20 to 39 years in the United States. This article summarizes recent research that reconceptualizes obesity as adipose disease associated with smoking; socio-economic disparities in employment, education, healthcare access, food quality, and availability; and environmental toxins, ultimately altering microbiomes and epigenetics. Individual prenatal care of women with obesity includes early testing for diabetes, counseling on epigenetic diets, advice supporting weight gain within national guidelines, and vigilance for signs of hypertensive disorders of pregnancy. Intrapartum care includes mechanical cervical ripening measures, patience with prolonged labor, and uterotonic medication readiness in the event of postpartum hemorrhage. Postpartum care includes thrombus risk amelioration through early ambulation, use of compression stockings, and anticoagulation. Delays in lactogenesis II can be offset by measures to support early breastfeeding. Sociopolitical action by nurses at national, state, and community levels to reduce population disparities in racism, education, and employment; reduce pollution from obesogenic chemicals; and improve food quality and distribution policies is likely to have the broadest impact in future obesity reductions and prevention.

Etiology, pathogenesis, diagnosis and treatment of bile reflux gastritis

Bile reflux gastritis is a common disease of the digestive system, whose clinical characteristics are abdominal pain, abdominal distention and nausea and vomiting, affecting the quality of life of patients seriously. However, the etiology and pathogenesis of bile reflux gastritis are still unclear, which may be related to gastrointestinal surgery, gallbladder disease, Helicobacter pylori infection, psychological factors, etc. There are many diagnostic methods, but a consensus on diagnosis is still lacking. Most of the current treatments are symptomatic treatments, but the overall efficacy is poor. This article reviews the etiology, pathogenesis, diagnosis and treatment of bile reflux gastritis, with an aim to provide a reference for further research of this disease.

Humble beginnings with big goals: Small molecule soluble epoxide hydrolase inhibitors for treating CNS disorders

Soluble epoxide hydrolase (sEH) degrades epoxides of fatty acids including epoxyeicosatrienoic acid isomers (EETs), which are produced as metabolites of the cytochrome P450 branch of the arachidonic acid pathway. EETs exert a variety of largely beneficial effects in the context of inflammation and vascular regulation. sEH inhibition is shown to be therapeutic in several cardiovascular and renal disorders, as well as in peripheral analgesia, via the increased availability of anti-inflammatory EETs. The success of sEH inhibitors in peripheral systems suggests their potential in targeting inflammation in the central nervous system (CNS) disorders. Here, we describe the current roles of sEH in the pathology and treatment of CNS disorders such as stroke, traumatic brain injury, Parkinson's disease, epilepsy, cognitive impairment, dementia and depression. In view of the robust anti-inflammatory effects of stem cells, we also outlined the potency of stem cell treatment and sEH inhibitors as a combination therapy for these CNS disorders. This review highlights the gaps in current knowledge about the pathologic and therapeutic roles of sEH in CNS disorders, which should guide future basic science research towards translational and clinical applications of sEH inhibitors for treatment of neurological diseases.