Short-chain fatty acids: microbial metabolites that alleviate stress-induced brain-gut axis alterations

Psychobiotic Lactobacillus plantarum JYLP-326 relieves anxiety, depression, and insomnia symptoms in test anxious college via modulating the gut microbiota and its metabolism

Introduction

Test anxiety is a common issue among college students, which can affect their physical and psychological health. However, effective interventions or therapeutic strategies are still lacking. This study aims to evaluate the potential effects of Lactobacillus plantarum JYLP-326 on test anxious college students.

Methods

Sixty anxious students were enrolled and randomly allocated to the placebo group and the probiotic group. Both groups were instructed to take placebo and JYLP-326 products twice per day for three weeks, respectively. Thirty unanxious students with no treatments were assigned to a regular control group. The anxiety, depression, and insomnia questionnaires were used to measure students' mental states at the baseline and the end of this study. 16S rRNA sequencing and untargeted metabolomics were performed to analyze the changes in the gut microbiota and fecal metabolism.

Results

The questionnaire results suggested that JYLP-326 administration could relieve the symptoms of anxiety, depression, and insomnia in test anxious students. The gut microbiomes of the placebo group showed a significantly greater diversity index than the control group (p < 0.05). An increased abundance of Bacteroides and Roseburia at the genus level was observed in the placebo group, and the relative abundance of Prevotella and Bifidobacterium decreased. Whereas, JYLP-326 administration could partly restore the disturbed gut microbiota. Additionally, test anxiety was correlated with disordered fecal metabolomics such as a higher Ethyl sulfate and a lower Cyclohexylamine, which could be reversed after taking JYLP-326. Furthermore, the changed microbiota and fecal metabolites were significantly associated with anxiety-related symptoms.

Conclusion

The results indicate that the intervention of L. plantarum JYLP-326 could be an effective strategy to alleviate anxiety, depression, and insomnia in test anxious college students. The potential mechanism underlying this effect could be related to the regulation of gut microbiota and fecal metabolites.

The microbiota-gut-brain axis in stress and depression

Humans and animals are evolved to have instinctive physiological responses to threats. The perception of threat by the brain triggers a multitude of changes across the brain and body. A large body of research have demonstrated that our hardwired survival instinct, the stress response, can become maladaptive and promote major depressive disorders and other neuropsychiatric impairments. However, gaps in our understanding of how chronic stress contributes to depression and mental disorders suggest that we also need to consider factors beyond the biology of the host. The unravelling of the structure and function of microorganisms that humans and animals are host to have driven a paradigm shift in understanding the individual as a collective network composed of the host plus microbes. Well over 90% of bacteria in the body reside in the large intestines, and these microbes in the lower gut function almost like an organ in the body in the way it interacts with the host. Importantly, bidirectional interactions between the gut microbiota and the brain (i.e., the two-way microbiota-gut-brain axis) have been implicated in the pathophysiology of mental disorders including depression. Here, in summarizing the emerging literature, we envisage that further research particularly on the efferent brain-gut-microbiota axis will uncover transformative links in the biology of stress and depression.

Exploring the regulatory mechanism of osteoporosis based on intestinal flora: A review

Osteoporosis is 1 of the common diseases of bone metabolism in clinic. With the aging of the population in China, osteoporosis is becoming more and more serious, and it has become 1 of the major public health problems. However, traditional therapies, such as calcium therapy and estrogen therapy, can cause serious adverse effects and damage to the body when ingested over a long period of time. Therefore, there is an urgent need to explore alternative therapies with less side effects in clinical practice. Intestinal flora is a hot topic of research in recent years. It has been studied in inflammatory bowel disease, diabetes, depression and so on. Recently, intestinal flora has received increasing attention in the pathways regulating bone metabolism. This paper contains a review of recent studies related to osteoporosis and gut flora in terms of its metabolites, immune, endocrine, and brain-gut axis pathways. The strong association between intestinal flora and bone metabolism suggests, to some extent, that intestinal flora can be a potential target for osteoporosis prevention and treatment, providing new ideas and therapies for the prevention and treatment of osteoporosis.

Acetate suppresses myocardial contraction via the short-chain fatty acid receptor GPR43

The heart has high energy requirements, with an estimated 40%-60% of myocardial ATP production derived from the oxidation of fatty acids under physiological conditions. However, the effect of short-chain fatty acids on myocardial contraction remains controversial, warranting further research. The present study sought to investigate the effects and mechanisms of acetate, a short-chain fatty acid, on myocardial contraction in rat ventricular myocytes. Echocardiography and Langendorff heart perfusion were used to evaluate cardiac function. Cell shortening and calcium transient were measured in isolated cardiomyocytes. The patch-clamp method determined the action potential and L-type Ca²⁺ current in cardiomyocytes. Moreover, the expression of GPR43, a type of short-chain fatty acid receptors in cardiomyocytes was examined by immunofluorescent staining and Western blot. We demonstrated that acetate transiently reduced left ventricular developmental pressure in isolated Langendorff heart perfusion model, with no effect on stroke volume and cardiac output in vivo. In addition, acetate transiently and reversibly inhibited cardiomyocyte contraction and calcium transient. Acetate did not affect the action potential and L-type Ca²⁺ currents in cardiomyocytes. As a short-chain fatty acid receptor, GPR43 was expressed in rat cardiomyocytes. Furthermore, the GPR43 antagonist GLPG0974 prevented the acetate-induced inhibitory effect on myocardial contraction. We conclude that acetate transiently inhibits contraction via the short-chain fatty acid receptor GPR43 in cardiomyocytes.

Exploring the Connection Between the Gut Microbiome and Parkinson's Disease Symptom Progression and Pathology: Implications for Supplementary Treatment Options

The contribution of the microbiota to induce gastrointestinal inflammation is hypothesized to be a key component of alpha-synuclein (aSyn) aggregation within the gastrointestinal (GI) tract in the pathological progression of Parkinson's disease (PD). The function of the GI tract is governed by a system of neurons that form part of the enteric nervous system (ENS). The ENS hosts  100-500 million nerve cells within two thin layers lining the GI tract. The gut-brain axis (GBA) is the major communication pathway between the ENS and the central nervous system. It has become increasingly clear that the microbiota in the gut are key regulators of GBA function and help to maintain homeostasis in the immune and endocrine systems. The GBA may act as a possible etiological launching pad for the pathogenesis of age-related neurodegenerative diseases, such as PD, because of an imbalance in the gut microbiota. PD is a multi-faceted illness with multiple biological, immunological, and environmental factors contributing to its pathological progression. Interestingly, individuals with PD have an altered gut microbiota compared to healthy individuals. However, there is a lack of literature describing the relationship between microbiota composition in the gut and symptom progression in PD patients. This review article examines how the pathology and symptomology of PD may originate from dysregulated signaling in the ENS. We then discuss by targeting the imbalance within the gut microbiota such as prebiotics and probiotics, some of the prodromal symptoms might be alleviated, possibly curtailing the pathological spread of aSyn and ensuing debilitating motor symptoms.

Epigenetics in depression and gut-brain axis: A molecular crosstalk

Gut-brain axis is a dynamic, complex, and bidirectional communication network between the gut and brain. Changes in the microbiota-gut-brain axis are responsible for developing various metabolic, neurodegenerative, and neuropsychiatric disorders. According to clinical and preclinical findings, the gut microbiota is a significant regulator of the gut-brain axis. In addition to interacting with intestinal cells and the enteric nervous system, it has been discovered that microbes in the gut can modify the central nervous system through metabolic and neuroendocrine pathways. The metabolites of the gut microbiome can modulate a number of diseases by inducing epigenetic alteration through DNA methylation, histone modification, and non-coding RNA-associated gene silencing. Short-chain fatty acids, especially butyrate, are well-known histone deacetylases inhibitors. Similarly, other microbial metabolites such as folate, choline, and trimethylamine-N-oxide also regulate epigenetics mechanisms. Furthermore, various studies have revealed the potential role of microbiome dysbiosis and epigenetics in the pathophysiology of depression. Hence, in this review, we have highlighted the role of gut dysbiosis in epigenetic regulation, causal interaction between host epigenetic modification and the gut microbiome in depression and suggest microbiome and epigenome as a possible target for diagnosis, prevention, and treatment of depression.

Reviewing the role of gut microbiota in the pathogenesis of depression and exploring new therapeutic options

The relationship between gut microbiota (GM) and mental health is one of the focuses of psychobiology research. In recent years, the microbial-gut-brain axis (MGBA) concept has gradually formed about this bidirectional communication between gut and brain. But how the GM is involved in regulating brain function and how they affect emotional disorders these mechanisms are tenuous and limited to animal research, and often controversial. Therefore, in this review, we attempt to summarize and categorize the latest advances in current research on the mechanisms of GM and depression to provide valid information for future diagnoses and therapy of mental disorders. Finally, we introduced some antidepressant regimens that can help restore gut dysbiosis, including classic antidepressants, Chinese materia medica (CMM), diet, and exogenous strains. These studies provide further insight into GM's role and potential pathways in emotion-related diseases, which holds essential possible clinical outcomes for people with depression or related psychiatric disorders. Future research should focus on clarifying the causal role of GM in disease and developing microbial targets, applying these findings to the prevention and treatment of depression.

Antibiotics-induced depression in mice via the microbiota-gut-brain axis

BACKGROUND

Intestinal dysbacteriosis is associated with depression. This study aimed to establish an antibiotics-induced depression mouse model and explore the mechanism of antibiotic-induced depression.

METHODS

C57BL/6 J mice were treated with antibiotics to prepare the antibiotic-induced depression mouse model. Behavioral tests and depression-related bio-markers were examined. To understand the abundance of different bacteria in intestinal flora and screen out the predominant bacterial species, metagenomic analysis of feces was carried out. Finally, we detected the expression of NF-κB-p65 and p-NF-κB-p65 in PFC and the hippocampus using Western blot.

RESULTS

Mixtures A and B caused depression-like behavior in mice. Norepinephrine, 5-hydroxytryptamine, and brain-derived neurotrophic factor in hippocampus and PFC of antibiotic-induced depression mice significantly decreased. The serum adrenocorticotropic hormone and corticosterone concentrations increased. The abundance values of Bacteroides thetaiotaomicron, Klebsiella oxytoca, and Klebsiella aerogenes in antibiotic-induced depression mice significantly increased, and the characteristic KO genes and metabolic pathways in antibiotic-induced depression mice were significantly different with in CUMS depression mice (the positive control) and normal mice. The relative levels of p-NF-κB-p65 in antibiotics-induced depression mice were significantly higher than in normal mice.

LIMITATIONS

How dysbacteriosis induces inflammation in the central nervous system is unclear.

CONCLUSIONS

Specific antibiotic mixture can cause depression-like behavior and changes of depression-related bio-markers in mice. The antibiotic-induced depression mice display changes in the species and metabolism of intestinal bacterial flora. The activation of NF-κB inflammatory signaling pathway in the central nervous system may act as one of the mechanisms in the development of antibiotic-induced depression.

Dietary fiber ameliorates lead-induced gut microbiota disturbance and alleviates neuroinflammation

Dietary fiber (DF) is a carbohydrate from the edible part of plants and has the functions of promoting gastrointestinal motility, regulating gut microbiota (GM) and improving health. Lead is a non-essential toxic heavy metal that can accumulate in the environment over time and enter the body through the respiratory tract, skin and gastrointestinal tract. Lead not only causes disturbances in GM but also leads to loss of homeostasis of immune functions, causes neuronal damage and results in neuroinflammation. The scientific literature has reported that DF had anti-inflammatory activity as a natural product. This review highlights the role of DF and its metabolic products in alleviating lead-induced neuroinflammation by inducing changes in the species and quantity of GM and regulating the immune system, providing a potential dietary protective strategy for lead-induced disease. © 2022 Society of Chemical Industry.

Inhibition of FKBP51 induces stress resilience and alters hippocampal neurogenesis

Stress-related psychiatric disorders such as depression are among the leading causes of morbidity and mortality. Considering that many individuals fail to respond to currently available antidepressant drugs, there is a need for antidepressants with novel mechanisms. Polymorphisms in the gene encoding FK506-binding protein 51 (FKBP51), a co-chaperone of the glucocorticoid receptor, have been linked to susceptibility to stress-related psychiatric disorders. Whether this protein can be targeted for their treatment remains largely unexplored. The aim of this work was to investigate whether inhibition of FKBP51 with SAFit2, a novel selective inhibitor, promotes hippocampal neuron outgrowth and neurogenesis in vitro and stress resilience in vivo in a mouse model of chronic psychosocial stress. Primary hippocampal neuronal cultures or hippocampal neural progenitor cells (NPCs) were treated with SAFit2 and neuronal differentiation and cell proliferation were analyzed. Male C57BL/6 mice were administered SAFit2 while concurrently undergoing a chronic stress paradigm comprising of intermittent social defeat and overcrowding, and anxiety and depressive -related behaviors were evaluated. SAFit2 increased neurite outgrowth and number of branch points to a greater extent than brain derived neurotrophic factor (BDNF) in primary hippocampal neuronal cultures. SAFit2 increased hippocampal NPC neurogenesis and increased neurite complexity and length of these differentiated neurons. In vivo, chronic SAFit2 administration prevented stress-induced social avoidance, decreased anxiety in the novelty-induced hypophagia test, and prevented stress-induced anxiety in the open field but did not alter adult hippocampal neurogenesis in stressed animals. These data warrant further exploration of inhibition of FKBP51 as a strategy to treat stress-related disorders.

Gut microbiota alterations in patients with juvenile idiopathic arthritis

Currently, the issue of the relationship between gut microbiota and juvenile idiopathic arthritis (JIA) is still relevant. The study was aimed to assess alterations in the gut microbiota taxonomic composition and estimate the relationship between these alterations and cortisol, melatonin, and TNFα at the genus level in patients with JIA. The comparative cross-sectional study involved 65 patients with JIA (index group) and 60 healthy children (control group). The gut microbiota taxonomic composition and plasma levels of cortisol, melatonin, and TNFα were assessed. The following alterations of the gut microbiota taxonomic composition were found in patients with JIA: the significantly decreased abundance of Anaerostipes (р = 0.042), Lachnospira (р = 0.034), Roseburia (р = 0.002), Coprococcus (р = 0.014), Dialister (р = 0.003) and the increase in the abundance of Ruminococcus (р = 0.012). There were significant correlations of cortisol levels with the abundance of Lachnospira (r = –0.44; p = 0.001), melatonin concentrations and the abundance of Coprococcus (r = –0.48; p = 0.023), the levels of TNFα and the abundance of Ruminococcus (r = 0.52; p = 0.001). The association of the Lachnospira, Roseburia, and Ruminococcus abundance with the higher DAS28 scores was discovered (r = –0.57; p = 0.002; r = –0.44; p = 0.002; r = 0.54; p = 0.032, respectively). The findings provide additional information about the features of gut microbiota alterations and their correlation with some hormone and inflammatory biomarkers associated with JIA, that could provide the basis for further research and possibly for new approaches to treatment of this disorder.

An unexpected connection: A narrative review of the associations between Gut Microbiome and Musculoskeletal Pain

PURPOSE

Multiple diverse factors contribute to musculoskeletal pain, a major cause of physical dysfunction and health-related costs worldwide. Rapidly growing evidence demonstrates that the gut microbiome has overarching influences on human health and the body's homeostasis and resilience to internal and external perturbations. This broad role of the gut microbiome is potentially relevant and connected to musculoskeletal pain, though the literature on the topic is limited. Thus, the literature on the topic of musculoskeletal pain and gut microbiome was explored.

METHODS

This narrative review explores the vast array of reported metabolites associated with inflammation and immune-metabolic response, which are known contributors to musculoskeletal pain. Moreover, it covers known modifiable (e.g., diet, lifestyle choices, exposure to prescription drugs, pollutants, and chemicals) and non-modifiable factors (e.g., gut architecture, genetics, age, birth history, and early feeding patterns) that are known to contribute to changes to the gut microbiome. Particular attention is devoted to modifiable factors, as the ultimate goal of researching this topic is to implement gut microbiome health interventions into clinical practice.

RESULTS

Overall, numerous associations exist in the literature that could converge on the gut microbiome's pivotal role in musculoskeletal health. Particularly, a variety of metabolites that are either directly produced or indirectly modulated by the gut microbiome have been highlighted.

CONCLUSION

The review highlights noticeable connections between the gut and musculoskeletal health, thus warranting future research to focus on the gut microbiome's role in musculoskeletal conditions.

The Role of the Gallbladder, the Intestinal Barrier and the Gut Microbiota in the Development of Food Allergies and Other Disorders

The microbiota present in the gastrointestinal tract is involved in the development or prevention of food allergies and autoimmune disorders; these bacteria can enter the gallbladder and, depending on the species involved, can either be benign or cause significant diseases. Occlusion of the gallbladder, usually due to the presence of calculi blocking the bile duct, facilitates microbial infection and inflammation, which can be serious enough to require life-saving surgery. In addition, the biliary salts are secreted into the intestine and can affect the gut microbiota. The interaction between the gut microbiota, pathogenic organisms, and the human immune system can create intestinal dysbiosis, generating a variety of syndromes including the development of food allergies and autoimmune disorders. The intestinal microbiota can aggravate certain food allergies, which become severe when the integrity of the intestinal barrier is affected, allowing bacteria, or their metabolites, to cross the intestinal barrier and invade the bloodstream, affecting distal body organs. This article deals with health conditions and severe diseases that are either influenced by the gut flora or caused by gallbladder obstruction and inflammation, as well as putative treatments for those illnesses.

Gut microbiome metabolites as key actors in atherosclerosis co-depression disease

Cardiovascular diseases, mainly characterized by atherosclerosis (AS), and depression have a high comorbidity rate. However, previous studies have been conducted under a single disease, and there is a lack of studies in comorbid states to explore the commonalities in the pathogenesis of both diseases. Modern high-throughput technologies have made it clear that the gut microbiome can affect the development of the host's own disorders and have shown that their metabolites are crucial to the pathophysiology of AS and depression. The aim of this review is to summarize the current important findings on the role of gut microbiome metabolites such as pathogen-associated molecular patterns, bile acids, tryptophan metabolites, short-chain fatty acids, and trimethylamine N -oxide in depression and AS disease, with the aim of identifying potential biological targets for the early diagnosis and treatment of AS co-depression disorders.

Gut microbiota-generated short-chain fatty acids are involved in para-chlorophenylalanine-induced cognitive disorders

Neurocognitive disorders (NCDs) include complex and multifactorial diseases that affect many patients. The 5-hydroxytryptamine (5-HT) neuron system plays an important role in NCDs. Existing studies have reported that para-chlorophenylalanine (PCPA), a 5-HT scavenger, has a negative effect on cognitive function. However, we believe that PCPA may result in NCDs through other pathways. To explore this possibility, behavioral tests were performed to evaluate the cognitive function of PCPA-treated mice, suggesting the appearance of cognitive dysfunction and depression-like behavior. Furthermore, 16S rRNA and metabolomic analyses revealed that dysbiosis and acetate alternation could be related to PCPA-induced NCDs. Our results suggest that not only 5-HT depletion but also dysbiosis and acetate alternation contributed to PCPA-related NCDs. Specifically, the latter promotes NCDs by reducing short-chain fatty acid levels. Together, these findings provide an alternative perspective on PCPA-induced NCDs.

The Cognitive Improvement and Alleviation of Brain Hypermetabolism Caused by FFAR3 Ablation in Tg2576 Mice Is Persistent under Diet-Induced Obesity

Obesity and aging are becoming increasingly prevalent across the globe. It has been established that aging is the major risk factor for Alzheimer's disease (AD), and it is becoming increasingly evident that obesity and the associated insulin resistance are also notably relevant risk factors. The biological plausibility of the link between high adiposity, insulin resistance, and dementia is central for understanding AD etiology, and to form bases for prevention efforts to decrease the disease burden. Several studies have demonstrated a strong association between short chain fatty acid receptor FFAR3 and insulin sensitivity. Interestingly, it has been recently established that FFAR3 mRNA levels are increased in early stages of the AD pathology, indicating that FFAR3 could play a key role in AD onset and progression. Indeed, in the present study we demonstrate that the ablation of the Ffar3 gene in Tg2576 mice prevents the development of cognitive deficiencies in advanced stages of the disease. Notably, this cognitive improvement is also maintained upon a severe metabolic challenge such as the exposure to high-fat diet (HFD) feeding. Moreover, FFAR3 deletion restores the brain hypermetabolism displayed by Tg2576 mice. Collectively, these data postulate FFAR3 as a potential novel target for AD.

The Role of Short Chain Fatty Acids in Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder that is characterized by abdominal pain and disordered bowel habits. The etiology of IBS is multifactorial, including abnormal gut-brain interactions, visceral hypersensitivity, altered colon motility, and psychological factors. Recent studies have shown that the intestinal microbiota and its metabolites short chain fatty acids (SCFAs) may be involved in the pathogenesis of IBS. SCFAs play an important role in the pathophysiology of IBS. We discuss the underlying mechanisms of action of SCFAs in intestinal inflammation and immunity, intestinal barrier integrity, motility, and the microbiota-gut-brain axis. Limited to previous studies, further studies are required to investigate the mechanisms of action of SCFAs in IBS and provide more precise therapeutic strategies for IBS.

Microbiota-Gut-Brain Axis Regulation of Adult Hippocampal Neurogenesis

The birth, maturation, and integration of new neurons in the adult hippocampus regulates specific learning and memory processes, responses to stress, and antidepressant treatment efficacy. This process of adult hippocampal neurogenesis is sensitive to environmental stimuli, including peripheral signals from certain cytokines, hormones, and metabolites, which can promote or hinder the production and survival of new hippocampal neurons. The trillions of microorganisms resident to the gastrointestinal tract, collectively known as the gut microbiota, also demonstrate the ability to modulate adult hippocampal neurogenesis. In doing so, the microbiota-gut-brain axis can influence brain functions regulated by adult hippocampal neurogenesis. Unlike the hippocampus, the gut microbiota is highly accessible to direct interventions, such as prebiotics, probiotics, and antibiotics, and can be manipulated by lifestyle choices including diet. Therefore, understanding the pathways by which the gut microbiota shapes hippocampal neurogenesis may reveal novel targets for non-invasive therapeutics to treat disorders in which alterations in hippocampal neurogenesis have been implicated. This review first outlines the factors which influence both the gut microbiome and adult hippocampal neurogenesis, with cognizance that these effects might happen either independently or due to microbiota-driven mechanisms. We then highlight approaches for investigating the regulation of adult hippocampal neurogenesis by the microbiota-gut-brain axis. Finally, we summarize the current evidence demonstrating the gut microbiota's ability to influence adult hippocampal neurogenesis, including mechanisms driven through immune pathways, microbial metabolites, endocrine signalling, and the nervous system, and postulate implications for these effects in disease onset and treatment.

Maternal gut microbiota mediate intergenerational effects of high-fat diet on descendant social behavior

Dysbiosis of the maternal gut microbiome during pregnancy is associated with adverse neurodevelopmental outcomes. We previously showed that maternal high-fat diet (MHFD) in mice induces gut dysbiosis, social dysfunction, and underlying synaptic plasticity deficits in male offspring (F₁). Here, we reason that, if HFD-mediated changes in maternal gut microbiota drive offspring social deficits, then MHFD-induced dysbiosis in F₁ female MHFD offspring would likewise impair F₂ social behavior. Metataxonomic sequencing reveals reduced microbial richness among female F₁ MHFD offspring. Despite recovery of microbial richness among MHFD-descendant F₂ mice, they display social dysfunction. Post-weaning Limosilactobacillus reuteri treatment increases the abundance of short-chain fatty acid-producing taxa and rescues MHFD-descendant F₂ social deficits. L. reuteri exerts a sexually dimorphic impact on gut microbiota configuration, increasing discriminant taxa between female cohorts. Collectively, these results show multigenerational impacts of HFD-induced dysbiosis in the maternal lineage and highlight the potential of maternal microbiome-targeted interventions for neurodevelopmental disorders.

Psychological stress in inflammatory bowel disease: Psychoneuroimmunological insights into bidirectional gut–brain communications

Inflammatory bowel disease (IBD), mainly including ulcerative colitis (UC) and Crohn’s disease (CD), is an autoimmune gastrointestinal disease characterized by chronic inflammation and frequent recurrence. Accumulating evidence has confirmed that chronic psychological stress is considered to trigger IBD deterioration and relapse. Moreover, studies have demonstrated that patients with IBD have a higher risk of developing symptoms of anxiety and depression than healthy individuals. However, the underlying mechanism of the link between psychological stress and IBD remains poorly understood. This review used a psychoneuroimmunology perspective to assess possible neuro-visceral integration, immune modulation, and crucial intestinal microbiome changes in IBD. Furthermore, the bidirectionality of the brain–gut axis was emphasized in the context, indicating that IBD pathophysiology increases the inflammatory response in the central nervous system and further contributes to anxiety- and depression-like behavioral comorbidities. This information will help accurately characterize the link between psychological stress and IBD disease activity. Additionally, the clinical application of functional brain imaging, microbiota-targeted treatment, psychotherapy and antidepressants should be considered during the treatment and diagnosis of IBD with behavioral comorbidities. This review elucidates the significance of more high-quality research combined with large clinical sample sizes and multiple diagnostic methods and psychotherapy, which may help to achieve personalized therapeutic strategies for IBD patients based on stress relief.

The gut microbiome and Alzheimer's disease: Complex and bidirectional interactions

Structural and functional alterations to the gut microbiome, referred to as gut dysbiosis, have emerged as potential key mediators of neurodegeneration and Alzheimer disease (AD) pathogenesis through the "gut -brain" axis. Emerging data from animal and clinical studies support an important role for gut dysbiosis in mediating neuroinflammation, central and peripheral immune dysregulation, abnormal brain protein aggregation, and impaired intestinal and brain barrier permeability, leading to neuronal loss and cognitive impairment. Gut dysbiosis has also been shown to directly influence various mechanisms involved in neuronal growth and repair, synaptic plasticity, and memory and learning functions. Aging and lifestyle factors including diet, exercise, sleep, and stress influence AD risk through gut dysbiosis. Furthermore, AD is associated with characteristic gut microbial signatures which offer value as potential markers of disease severity and progression. Together, these findings suggest the presence of a complex bidirectional relationship between AD and the gut microbiome and highlight the utility of gut modulation strategies as potential preventative or therapeutic strategies in AD. We here review the current literature regarding the role of the gut-brain axis in AD pathogenesis and its potential role as a future therapeutic target in AD treatment and/or prevention.

Interactions between central nervous system and peripheral metabolic organs

According to Descartes, minds and bodies are distinct kinds of "substance", and they cannot have causal interactions. However, in neuroscience, the two-way interaction between the brain and peripheral organs is an emerging field of research. Several lines of evidence highlight the importance of such interactions. For example, the peripheral metabolic systems are overwhelmingly regulated by the mind (brain), and anxiety and depression greatly affect the functioning of these systems. Also, psychological stress can cause a variety of physical symptoms, such as bone loss. Moreover, the gut microbiota appears to play a key role in neuropsychiatric and neurodegenerative diseases. Mechanistically, as the command center of the body, the brain can regulate our internal organs and glands through the autonomic nervous system and neuroendocrine system, although it is generally considered to be outside the realm of voluntary control. The autonomic nervous system itself can be further subdivided into the sympathetic and parasympathetic systems. The sympathetic division functions a bit like the accelerator pedal on a car, and the parasympathetic division functions as the brake. The high center of the autonomic nervous system and the neuroendocrine system is the hypothalamus, which contains several subnuclei that control several basic physiological functions, such as the digestion of food and regulation of body temperature. Also, numerous peripheral signals contribute to the regulation of brain functions. Gastrointestinal (GI) hormones, insulin, and leptin are transported into the brain, where they regulate innate behaviors such as feeding, and they are also involved in emotional and cognitive functions. The brain can recognize peripheral inflammatory cytokines and induce a transient syndrome called sick behavior (SB), characterized by fatigue, reduced physical and social activity, and cognitive impairment. In summary, knowledge of the biological basis of the interactions between the central nervous system and peripheral organs will promote the full understanding of how our body works and the rational treatment of disorders. Thus, we summarize current development in our understanding of five types of central-peripheral interactions, including neural control of adipose tissues, energy expenditure, bone metabolism, feeding involving the brain-gut axis and gut microbiota. These interactions are essential for maintaining vital bodily functions, which result in homeostasis, i.e., a natural balance in the body's systems.

Recent progress of Lycium barbarum polysaccharides on intestinal microbiota, microbial metabolites and health: a review

Intestinal microbiota is symbiotically associated with host health, learning about the characteristics of microbiota and the factors that modulate it could assist in developing strategies to promote human health and prevent diseases. Polysaccharides from Lycium barbarum (LBPs) are found beneficial for enhancing the activity of gut microbiota, as a potential prebiotic, which not only participates in improving body immunity, obesity, hyperlipidemia and systemic inflammation induced by oxidative stress, but also plays a magnificent role in regulating intestinal microenvironment and improving host health and target intestinal effects via its biological activities, as well as gut microbiota and metabolites. To highlight the internal relationship between intestinal microbiota and LBPs, this review focuses on the latest advances in LBPs on the intestinal microbiota, metabolites, immune regulation, intestinal barrier protection, microbiota-gut-brain axis and host health. Moreover, the preparation, structure, bioactivity and modification of LBPs were also discussed. This review may offer new perspective on LBPs improving health of gut and host via intestinal microbiota, and provide useful guidelines for the application of LBPs in the food industry.

Depression and antidepressant effects of ketamine and its metabolites: The pivotal role of gut microbiota

The discovery of the robust antidepressant actions of ketamine is regarded as one of the greatest advancements in depression treatment in the past 60 years. Recent findings have provided strong evidence for the presence of bidirectional communication networks between the gastrointestinal tract and the brain in depression. Moreover, increasing evidence supports the antidepressant role of ketamine in regulating the gut microbiome and microbiota-derived molecules; however, the mechanisms underpinning such effects are still ambiguous. This review summarizes the current understanding of the anti-depressant mechanisms of ketamine and its metabolites regarding the bidirectional regulation by microbiota-gut-brain axis. We review the relationship between gut microbiota and the antidepressant mechanisms of ketamine, and discuss the role of stress response, brain-derived neurotrophic factor (BDNF)-mediated neurogenesis, anti-inflammatory effect and neurotransmitters.

Does the Gut Microbial Metabolome Really Matter? The Connection between GUT Metabolome and Neurological Disorders

Herein we gathered updated knowledge regarding the alterations of gut microbiota (dysbiosis) and its correlation with human neurodegenerative and brain-related diseases, e.g., Alzheimer’s and Parkinson’s. This review underlines the importance of gut-derived metabolites and gut metabolic status as the main players in gut-brain crosstalk and their implications on the severity of neural conditions. Scientific evidence indicates that the administration of probiotic bacteria exerts beneficial and protective effects as reduced systemic inflammation, neuroinflammation, and inhibited neurodegeneration. The experimental results performed on animals, but also human clinical trials, show the importance of designing a novel microbiota-based probiotic dietary supplementation with the aim to prevent or ease the symptoms of Alzheimer’s and Parkinson’s diseases or other forms of dementia or neurodegeneration.

Gut Bacteria and Neurotransmitters

Gut bacteria play an important role in the digestion of food, immune activation, and regulation of entero-endocrine signaling pathways, but also communicate with the central nervous system (CNS) through the production of specific metabolic compounds, e.g., bile acids, short-chain fatty acids (SCFAs), glutamate (Glu), γ-aminobutyric acid (GABA), dopamine (DA), norepinephrine (NE), serotonin (5-HT) and histamine. Afferent vagus nerve (VN) fibers that transport signals from the gastro-intestinal tract (GIT) and gut microbiota to the brain are also linked to receptors in the esophagus, liver, and pancreas. In response to these stimuli, the brain sends signals back to entero-epithelial cells via efferent VN fibers. Fibers of the VN are not in direct contact with the gut wall or intestinal microbiota. Instead, signals reach the gut microbiota via 100 to 500 million neurons from the enteric nervous system (ENS) in the submucosa and myenteric plexus of the gut wall. The modulation, development, and renewal of ENS neurons are controlled by gut microbiota, especially those with the ability to produce and metabolize hormones. Signals generated by the hypothalamus reach the pituitary and adrenal glands and communicate with entero-epithelial cells via the hypothalamic pituitary adrenal axis (HPA). SCFAs produced by gut bacteria adhere to free fatty acid receptors (FFARs) on the surface of intestinal epithelial cells (IECs) and interact with neurons or enter the circulatory system. Gut bacteria alter the synthesis and degradation of neurotransmitters. This review focuses on the effect that gut bacteria have on the production of neurotransmitters and vice versa.

Monobutyrin and monovalerin improve gut-blood-brain biomarkers and alter gut microbiota composition in high-fat fed apolipoprotein-E-knockout rats

Monobutyrin (MB) and monovalerin (MV), glycerol esters of short-chain fatty acids (SCFAs), have been shown to positively influence lipid profile and biomarkers in the gut and brain. This study examined whether MB and MV in high-fat diets, affected microbiota composition and gut-blood-brain markers in apolipoprotein E deficient (ApoE-/-) rats, a model for studies of lipid-associated disorders, and neurodegenerative processes in Alzheimer's disease (AD). ApoE-/- rats fed MB and MV increased Tenericutes and the brain neurotransmitter γ-aminobutyric acid (GABA), while the blood stress hormone corticosterone decreased compared to control rats. Only rats that received MB showed a significant increase in cholic acid and Adlercreutzia in the caecum. In rats fed MV, the decrease of Proteobacteria was associated with decreased corticosterone levels. Conclusively, dietary supplementation of SCFA glycerol esters can modulate gut-blood-brain markers and alter gut microbiota composition in ApoE-/- rats, suggesting that SCFAs also could counteract lipid disorders-related diseases.

Cyclic Nucleotide Phosphodiesterases in Alcohol Use Disorders: Involving Gut Microbiota

Alcohol abuse is 1 of the most significant public health problems in the world. Chronic, excessive alcohol consumption not only causes alcohol use disorder (AUD) but also changes the gut and lung microbiota, including bacterial and nonbacterial types. Both types of microbiota can release toxins, further damaging the gastrointestinal and respiratory tracts; causing inflammation; and impairing the functions of the liver, lung, and brain, which in turn deteriorate AUD. Phosphodiesterases (PDEs) are critical in the control of intracellular cyclic nucleotides, including cyclic adenosine monophosphate and cyclic guanosine monophosphate. Inhibition of certain host PDEs reduces alcohol consumption and attenuates alcohol-related impairment. These PDEs are also expressed in the microbiota and may play a role in controlling microbiota-associated inflammation. Here, we summarize the influences of alcohol on gut/lung bacterial and nonbacterial microbiota as well as on the gut-liver/brain/lung axis. We then discuss the relationship between gut and lung microbiota-mediated PDE signaling and AUD consequences in addition to highlighting PDEs as potential targets for treatment of AUD.

Survival and Interplay of γ-Aminobutyric Acid-Producing Psychobiotic Candidates with the Gut Microbiota in a Continuous Model of the Human Colon

Simple Summary

Appreciable evidence suggests that gut microbiota interact with the brain and play a key role in the pathogenesis of mental illnesses. Psychobiotics are beneficial bacteria (probiotics) or support for such bacteria (prebiotics) that can positively modulate microbiota–gut–brain interactions. Several trials suggest probiotics are involved in normalizing brain processes related to stress responses and mood improvements. Here, we studied the growth and competitiveness of recently identified GABA-producing psychobiotic candidates in a continuous model of the human colon. In summary, supplementation with these probiotic candidates positively modulated the gut microbiome composition and metabolism, suggesting their suitability for gut health-promoting applications.

Abstract

Over decades, probiotic research has focused on their benefits to gut health. Recently, the gut microbiota has been proven to share bidirectional connections with the brain through the gut–brain axis. Therefore, the manipulation of this axis via probiotics has garnered interest. We have recently isolated and characterized in vitro probiotic candidates producing γ-aminobutyric acid (GABA), a major neuromodulator of the enteric nervous system. This study investigates the growth and competitiveness of selected GABA-producing probiotic candidates (Bifidobacterium animalis, Streptococcus thermophilus, and Lactobacillus delbrueckii subsp. bulgaricus) in the presence of human gut microbiota ex vivo in a model mimicking physiological and microbiological conditions of the human proximal colon. Supplementation with GABA-producing probiotic candidates did not affect the overall gut microbiota diversity over 48 h of treatment. However, these candidates modulated the microbiota composition, especially by increasing the Bacteroidetes population, a key gut microbe associated with anti-inflammatory activities. The level of microbiota-generated SCFAs within 12 h of treatment was also increased, compared to the control group. Results from this study demonstrate the probiotic potential of the tested GABA-producing bacteria and their impact on gut microbiota structure and metabolism, suggesting their suitability for gut health-promoting applications.

Enteric nervous system and intestinal epithelial regulation of the gut-brain axis

The gut-brain axis describes a bidirectional interplay within the enteric environment between the intestinal epithelium, the mucosal immune system, and the microbiota with the enteric nervous system. This interplay provides a link between exogenous environmental stimuli such as nutrient sensing, and nervous system function, as well as a mechanism of feedback from cortical and sensory centers of the brain to enteric activities. The intestinal epithelium is one of the human body's largest sources of hormones and neurotransmitters, which have critical effects on neuronal function. The influence of the gut microbiota on these processes appears to be profound; yet to date, it has been insufficiently explored. Disruption of the intestinal microbiota is linked not only to diseases in the gut but also to brain symptomatology, including neurodegenerative and behavioral disorders (Parkinson disease, Alzheimer disease, autism, and anxiety and/or depression). In this review we discuss the cellular wiring of the gut-brain axis, with a particular focus on the epithelial and neuronal interaction, the evidence that has led to our current understanding of the intestinal role in neurologic function, and future directions of research to unravel this important interaction in both health and allergic disease.

Modulation of gut microbiota and fecal metabolites by corn silk among high-fat diet-induced hypercholesterolemia mice

Corn silk (CS) is known to reduce cholesterol levels, but its underlying mechanisms remain elusive concerning the gut microbiota and metabolites. The aim of our work was to explore how altered gut microbiota composition and metabolite profile are influenced by CS intervention in mice using integrated 16S ribosomal RNA (rRNA) sequencing and an untargeted metabolomics methodology. The C57BL/6J mice were fed a normal control diet, a high-fat diet (HFD), and HFD supplemented with the aqueous extract of CS (80 mg/mL) for 8 weeks. HFD-induced chronic inflammation damage is alleviated by CS extract intervention and also resulted in a reduction in body weight, daily energy intake as well as serum and hepatic total cholesterol (TC) levels. In addition, CS extract altered gut microbial composition and regulated specific genera viz. Allobaculum, Turicibacter, Romboutsia, Streptococcus, Sporobacter, Christensenella, ClostridiumXVIII, and Rikenella. Using Spearman’s correlation analysis, we determined that Turicibacter and Rikenella were negatively correlated with hypercholesterolemia-related parameters. Fecal metabolomics analysis revealed that CS extract influences multiple metabolic pathways like histidine metabolism-related metabolites (urocanic acid, methylimidazole acetaldehyde, and methiodimethylimidazoleacetic acid), sphingolipid metabolism-related metabolites (sphinganine, 3-dehydrosphinganine, sphingosine), and some bile acids biosynthesis-related metabolites including chenodeoxycholic acid (CDCA), lithocholic acid (LCA), ursodeoxycholic acid (UDCA), and glycoursodeoxycholic acid (GUDCA). As a whole, the present study indicates that the modifications in the gut microbiota and subsequent host bile acid metabolism may be a potential mechanism for the antihypercholesterolemic effects of CS extract.

Host-microbiota interactions: The aryl hydrocarbon receptor in the acute and chronic phases of cerebral ischemia

The relationship between gut microbiota and brain function has been studied intensively in recent years, and gut microbiota has been linked to a couple of neurological disorders including stroke. There are multiple studies linking gut microbiota to stroke in the “microbiota-gut-brain” axis. The aryl hydrocarbon receptor (AHR) is an important mediator of acute ischemic damage and can result in subsequent neuroinflammation. AHR can affect these responses by sensing microbiota metabolites especially tryptophan metabolites and is engaged in the regulation of acute ischemic brain injury and chronic neuroinflammation after stroke. As an important regulator in the “microbiota-gut-brain” axis, AHR has the potential to be used as a new therapeutic target for ischemic stroke treatment. In this review, we discuss the research progress on AHR regarding its role in ischemic stroke and prospects to be used as a therapeutic target for ischemic stroke treatment, aiming to provide a potential direction for the development of new treatments for ischemic stroke.

Microbiota-derived metabolites as drivers of gut-brain communication

Alterations in the gut microbiota composition have been associated with a range of neurodevelopmental, neurodegenerative, and neuropsychiatric disorders. The gut microbes transform and metabolize dietary- and host-derived molecules generating a diverse group of metabolites with local and systemic effects. The bi-directional communication between brain and the microbes residing in the gut, the so-called gut-brain axis, consists of a network of immunological, neuronal, and endocrine signaling pathways. Although the full variety of mechanisms of the gut-brain crosstalk is yet to be established, the existing data demonstrates that a single metabolite or its derivatives are likely among the key inductors within the gut-brain axis communication. However, more research is needed to understand the molecular mechanisms underlying how gut microbiota associated metabolites alter brain functions, and to examine if different interventional approaches targeting the gut microbiota could be used in prevention and treatment of neurological disorders, as reviewed herein.Abbreviations:4-EPS 4-ethylphenylsulfate; 5-AVA(B) 5-aminovaleric acid (betaine); Aβ Amyloid beta protein; AhR Aryl hydrocarbon receptor; ASD Autism spectrum disorder; BBB Blood-brain barrier; BDNF Brain-derived neurotrophic factor; CNS Central nervous system; GABA ɣ-aminobutyric acid; GF Germ-free; MIA Maternal immune activation; SCFA Short-chain fatty acid; 3M-4-TMAB 3-methyl-4-(trimethylammonio)butanoate; 4-TMAP 4-(trimethylammonio)pentanoate; TMA(O) Trimethylamine(-N-oxide); TUDCA Tauroursodeoxycholic acid; ZO Zonula occludens proteins.

Remodeling of microbiota gut-brain axis using psychobiotics in depression

Depression is a multifaceted psychiatric disorder mainly orchestrated by dysfunction of neuroendocrine, neurochemical, immune, and metabolic systems. The interconnection of gut microbiota perturbation with the central nervous system disorders has been well documented in recent times. Indeed, alteration of commensal intestinal microflora is noted in several psychiatric disorders such as anxiety and depression, which are presumed to be routed through the enteric nervous system, autonomic nervous system, endocrine, and immune system. This review summarises the new mechanisms underlying the crosstalk between gut microbiota and brain involved in the management of depression. Depression-induced changes in the commensal intestinal microbiota are majorly linked with the disruption of gut integrity, hyperinflammation, and modulation of short-chain fatty acids, neurotransmitters, kynurenine metabolites, endocannabinoids, brain-derived neurotropic factors, hypothalamic-pituitary-adrenal axis, and gut peptides. The restoration of gut microbiota with prebiotics, probiotics, postbiotics, synbiotics, and fermented foods (psychobiotics) has gained a considerable attention for the management of depression. Recent evidence also propose the role of gut microbiota in the process of treatment-resistant depression. Thus, remodeling of the microbiota-gut-brain axis using psychobiotics appears to be a promising therapeutic approach for the reversal of psychiatric disorders, and it is imperative to decipher the underlying mechanisms for gut-brain crosstalk.

Gut dysbiosis impairs hippocampal plasticity and behaviors by remodeling serum metabolome

Accumulating evidence suggests that gut microbiota as a critical mediator of gut-brain axis plays an important role in human health. Altered gut microbial profiles have been implicated in increasing the vulnerability of psychiatric disorders, such as autism, depression, and schizophrenia. However, the cellular and molecular mechanisms underlying the association remain unknown. Here, we modified the gut microbiome with antibiotics in newborn mice, and found that gut microbial alteration induced behavioral impairment by decreasing adult neurogenesis and long-term potentiation of synaptic transmission, and altering the gene expression profile in hippocampus. Reconstitution with normal gut flora produced therapeutic effects against both adult neurogenesis and behavioral deficits in the dysbiosis mice. Furthermore, our results show that circulating metabolites changes mediate the effect of gut dysbiosis on hippocampal plasticity and behavior outcomes. Elevating the serum 4-methylphenol, a small aromatic metabolite produced by gut bacteria, was found to induce autism spectrum disorder (ASD)-like behavior impairment and hippocampal dysfunction. Together our finding demonstrates that early-life gut dysbiosis and its correlated metabolites change contribute to hippocampal dysfunction and behavior impairment, hence highlight the potential microbiome-mediated therapies for treating psychiatric disorders.

Substance use, microbiome and psychiatric disorders

Accumulating evidence from several studies has shown association between substance use, dysregulation of the microbiome and psychiatric disorders such as depression, anxiety, and psychosis. Many of the abused substances such as cocaine and alcohol have been shown to alter immune signaling pathways and cause inflammation in both the periphery and the central nervous system (CNS). In addition, these substances of abuse also alter the composition and function of the gut microbiome which is known to play important roles such as the synthesis of neurotransmitters and metabolites, that affect the CNS homeostasis and consequent behavioral outcomes. The emerging interactions between substance use, microbiome and CNS neurochemical alterations could contribute to the development of psychiatric disorders. This review provides an overview of the associative effects of substance use such as alcohol, cocaine, methamphetamine, nicotine and opioids on the gut microbiome and psychiatric disorders involving anxiety, depression and psychosis. Understanding the relationship between substance use, microbiome and psychiatric disorders will provide insights for potential therapeutic targets, aimed at mitigating these adverse outcomes.

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

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

Role of Short Chain Fatty Acids in Epilepsy and Potential Benefits of Probiotics and Prebiotics: Targeting “Health” of Epileptic Patients

The WHO’s definition of health transcends the mere absence of disease, emphasizing physical, mental, and social well-being. As this perspective is being increasingly applied to the management of chronic diseases, research on gut microbiota (GM) is surging, with a focus on its potential for persistent and noninvasive dietary therapeutics. In patients with epilepsy (PWE), a chronic lack of seizure control along with often neglected psychiatric comorbidities greatly disrupt the quality of life. Evidence shows that GM-derived short chain fatty acids (SCFAs) may impact seizure susceptibility through modulating (1) excitatory/inhibitory neurotransmitters, (2) oxidative stress and neuroinflammation, and (3) psychosocial stress. These functions are also connected to shared pathologies of epilepsy and its two most common psychiatric consequences: depression and anxiety. As the enhancement of SCFA production is enabled through direct administration, as well as probiotics and prebiotics, related dietary treatments may exert antiseizure effects. This paper explores the potential roles of SCFAs in the context of seizure control and its mental comorbidities, while analyzing existing studies on the effects of pro/prebiotics on epilepsy. Based on currently available data, this study aims to interpret the role of SCFAs in epileptic treatment, extending beyond the absence of seizures to target the health of PWE.

Material Engineering in Gut Microbiome and Human Health

Tremendous progress has been made in the past decade regarding our understanding of the gut microbiome's role in human health. Currently, however, a comprehensive and focused review marrying the two distinct fields of gut microbiome and material research is lacking. To bridge the gap, the current paper discusses critical aspects of the rapidly emerging research topic of "material engineering in the gut microbiome and human health." By engaging scientists with diverse backgrounds in biomaterials, gut-microbiome axis, neuroscience, synthetic biology, tissue engineering, and biosensing in a dialogue, our goal is to accelerate the development of research tools for gut microbiome research and the development of therapeutics that target the gut microbiome. For this purpose, state-of-the-art knowledge is presented here on biomaterial technologies that facilitate the study, analysis, and manipulation of the gut microbiome, including intestinal organoids, gut-on-chip models, hydrogels for spatial mapping of gut microbiome compositions, microbiome biosensors, and oral bacteria delivery systems. In addition, a discussion is provided regarding the microbiome-gut-brain axis and the critical roles that biomaterials can play to investigate and regulate the axis. Lastly, perspectives are provided regarding future directions on how to develop and use novel biomaterials in gut microbiome research, as well as essential regulatory rules in clinical translation. In this way, we hope to inspire research into future biomaterial technologies to advance gut microbiome research and gut microbiome-based theragnostics.

Lactobacillus plantarum WSJ-06 alleviates neurobehavioral injury induced by lead in mice through the gut microbiota

Chronic lead exposure can result in cognitive dysfunction and behavioral disorders. However, the current treatments for alleviating lead poisoning have many side effects. Previous studies have suggested that probiotics may have the potential to ameliorate neurotoxicity caused by lead exposure. This study determines the alleviating effects of Lactobacillus plantarum WSJ-06 on neurological disorders induced by chronic lead exposure from the perspective of the gut microbiota and serum metabolites. The results showed that treatment with Lactobacillus plantarum WSJ-06 alleviated memory dysfunction and reduced the levels of inflammatory cytokines in the serum and hippocampus induced by lead exposure. In addition, Lactobacillus plantarum WSJ-06 partially restored the lead-induced gut microbiota dysbiosis. It also increased the proportion of some beneficial metabolites in the serum, such as arachidonic acid, tryptophan hydroxylase, serotonin, vitamin B12, trehalose, and kynurenic acid, and decreased some metabolites in the serum, such as LPS 20:5 and L-kynurenine. A correlation analysis further indicated that lead-induced neurobehavioral disorders were related to intestinal microbiota (the [Eubacterium]_siraeum_group, Roseburia, Lactobacillus, etc) and serum metabolites (LPS 20:5, serotonin, vitamin B12, etc). In conclusion, Lactobacillus plantarum WSJ-06 alleviated neuroinflammation and memory impairment caused by lead exposure by modulating the gut microbiota and metabolites in the serum.

Role of a mixed probiotic product, VSL#3, in the prevention and treatment of colorectal cancer

Colorectal cancer (CRC) is a multifactorial disease. The incidence of this type of cancer in younger patients has increased in recent years, and more strategies are needed to prevent and delay the progression of CRC. Probiotics play an adjunctive role in the prevention and treatment of CRC and can not only prevent the onset and delay the progression of disease but also reduce the side effects after the application of anti-cancer drugs. The anti-cancer effect of individual probiotics has been extensively studied, and the exact curative effect of various probiotics has been found, but the anti-cancer effect of mixed probiotics is still not well summarized. In this review, we discuss the positive effects of mixed probiotics on CRC and the related mechanisms of action, especially VSL#3 (VSL Pharmaceuticals, Inc., Gaithersburg, MD, USA), thus providing new ideas for the treatment of CRC. Moreover, we suggest the need to search for more therapeutic possibilities, especially via the research and application of synbiotics and postbiotics.

Metabolic Pathways Associated With Psychoneurological Symptoms in Children With Cancer Receiving Chemotherapy

CONTEXT

Children with cancer undergoing chemotherapy experience a cluster of psychoneurological symptoms (PNS), including pain, fatigue, anxiety, and depressive symptoms. Metabolomics is promising to differentiate metabolic pathways associated with the PNS cluster.

OBJECTIVES

Identify metabolic pathways associated with the PNS cluster in children with cancer before and after chemotherapy.

METHODS

Pain, fatigue, anxiety, and depressive symptoms were assessed using the Pediatric PROMIS scales. T-scores were computed and divided dichotomously by a cutoff point of 50; the PNS cluster was a sum of the four symptoms ranging from 0 (all T-scores <50) to 4 (all T-scores ≥50). Serum metabolites were processed using liquid chromatography mass-spectrometry untargeted metabolomics approach. Linear regression models examined metabolites associated with the PNS cluster. Metabolic pathway enrichment analysis was performed.

RESULTS

Participant demographics (n = 40) were 55% female, 60% white, 62.5% aged 13-19 years, and 62.5% diagnoses of Hodgkin's lymphoma and B-cell acute lymphocytic leukemia. Among 9276 unique metabolic features, 454 were associated with pain, 281 with fatigue, 596 with anxiety, 551 with depressive symptoms, and 300 with the PNS cluster across one chemotherapy cycle. Fatty acids pathways were associated with pain: de novo fatty acid biosynthesis (p < .001), fatty acid metabolism (p = .001), fatty acid activation (p = .004), and omega-3 fatty acid metabolism (p = .009). Tryptophan amino acid pathway was associated with fatigue (p < .001), anxiety (p = .015), and the PNS cluster (p = .037). Carnitine shuttle was associated with the PNS cluster (p = .015).

CONCLUSION

Fatty acids and amino acids pathways were associated with PNS in children undergoing chemotherapy. These findings require further investigation in a larger sample.

A Diet Supplemented with Polyphenols, Prebiotics and Omega-3 Fatty Acids Modulates the Intestinal Microbiota and Improves the Profile of Metabolites Linked with Anxiety in Dogs

Simple Summary

This study used a nutrition-based approach to examine the effects of foods supplemented with fish oil and a polyphenol blend (citrus pulp, carrot, and spinach) with or without added tomato pomace on anxiety-related biomarkers in dogs. First, all dogs consumed the same initial food, then either the control or test (with tomato pomace) foods, then the washout food, then switched over to the test or control foods, each for 30-day periods. Many more changes in plasma and fecal metabolites were observed when comparing the washout food with the control or test foods than when the control and test foods were compared. Plasma levels of several metabolites that were previously associated with anxiety disorders, including 4-ethylphenyl sulfate, were decreased with the control or test foods compared with the washout food. In addition, bacterial genera that are decreased in the feces of those with anxiety-like disorders were increased following the consumption of the control or test foods. Overall, these data indicate that foods supplemented with omega-3 fatty acids and selected fiber and polyphenol sources lead to beneficial changes in anxiety-related metabolites and gut bacteria.

Abstract

A nutrition-based approach was utilized to examine the effects of fish oil and a polyphenol blend (with or without tomato pomace) on the fecal microbiota and plasma/fecal metabolomes. Forty dogs, aged 5–14 years, were fed a washout food, then randomized to consume a control (fish oil and polyphenol blend without tomato pomace) or test (fish oil and polyphenol blend with tomato pomace) food, then the washout food, and crossed over to consume the test or control food; each for 30 days. Several metabolites differed when comparing consumption of the washout with either the control or test foods, but few changed significantly between the test and control foods. Plasma levels of 4-ethylphenyl sulfate (4-EPS), a metabolite associated with anxiety disorders, demonstrated the largest decrease between the washout food and the control/test foods. Plasma 4-EPS levels were also significantly lower after dogs ate the test food compared with the control food. Other plasma metabolites linked with anxiety disorders were decreased following consumption of the control/test foods. Significant increases in Blautia, Parabacteroides, and Odoribacter in the fecal microbiota correlated with decreases in 4-EPS when dogs ate the control/test foods. These data indicate that foods supplemented with polyphenols and omega-3 fatty acids can modulate the gut microbiota to improve the profile of anxiety-linked metabolites.

The Role of Banana (Musa balbisiana Colla) Peel Floss as Functional Food Matrix to Alleviate Chronic Stress

BACKGROUND: Banana peel (Musa balbisiana Colla) already has a diverse variety of nutritional benefits, but its perishable nature necessitates additional food processing, one of which is banana peel floss. AIM: The objective of this study was to examine the antidepressant effects of banana peel floss in experimental animals subjected to chronic mild stress (CMS) for 6 weeks. METHODS: Animals were randomly assigned into five groups. The first group was fed a control diet without CMS as a negative control. The other four groups were exposed to CMS and fed a control diet as a positive control, with three of the five groups fed a control diet supplemented with 15%, 30%, and 60% banana peel floss. The tail suspension test (TST) and the Morris water maze were used as behavioral parameters in this study (MWM). Cortisol and serotonin levels were measured in two stages: after CMS exposure or before banana peel floss intervention, and after 4 weeks of banana peel floss intervention. RESULTS: The results showed that the immobility time in TST and escape latency in the MWM test were significantly reduced in the groups supplemented with 15% and 30% banana peel floss, respectively. Furthermore, we observed a significant association between serotonin and cortisol levels and also between the duration of immobility time in TST and serotonin levels. CONCLUSIONS: The administration of banana peel floss caused significant changes in plasma serotonin concentrations, implying that the presence of dietary fiber, tryptophan, and bioactive components in banana peel floss can reduce stress-induced depression by regulating cortisol levels and increasing serotonin levels.

Drugs, Guts, Brains, but Not Rock and Roll: The Need to Consider the Role of Gut Microbiota in Contemporary Mental Health and Wellness of Emerging Adults

Emerging adulthood (ages 18-25) is a critical period for neurobiological development and the maturation of the hypothalamic-pituitary-adrenal axis. Recent findings also suggest that a natural perturbation of the gut microbiota (GM), combined with other factors, may create a unique vulnerability during this period of life. The GM of emerging adults is thought to be simpler, less diverse, and more unstable than either younger or older people. We postulate that this plasticity in the GM suggests a role in the rising mental health issues seen in westernized societies today via the gut-brain-microbiota axis. Studies have paid particular attention to the diversity of the microbiota, the specific function and abundance of bacteria, and the production of metabolites. In this narrative review, we focus specifically on diet, physical activity/exercise, substance use, and sleep in the context of the emerging adult. We propose that this is a crucial period for establishing a stable and more resilient microbiome for optimal health into adulthood. Recommendations will be made about future research into possible behavioral adjustments that may be beneficial to endorse during this critical period to reduce the probability of a "dysbiotic" GM and the emergence and severity of mental health concerns.

Gut Microbial Dysbiosis and Cognitive Impairment in Bipolar Disorder: Current Evidence

Recent studies have reported that the gut microbiota influences mood and cognitive function through the gut-brain axis, which is involved in the pathophysiology of neurocognitive and mental disorders, including Parkinson’s disease, Alzheimer’s disease, and schizophrenia. These disorders have similar pathophysiology to that of cognitive dysfunction in bipolar disorder (BD), including neuroinflammation and dysregulation of various neurotransmitters (i.e., serotonin and dopamine). There is also emerging evidence of alterations in the gut microbial composition of patients with BD, suggesting that gut microbial dysbiosis contributes to disease progression and cognitive impairment in BD. Therefore, microbiota-centered treatment might be an effective adjuvant therapy for BD-related cognitive impairment. Given that studies focusing on connections between the gut microbiota and BD-related cognitive impairment are lagging behind those on other neurocognitive disorders, this review sought to explore the potential mechanisms of how gut microbial dysbiosis affects cognitive function in BD and identify potential microbiota-centered treatment.

Biogenic action of Lactobacillus plantarum SBT2227 promotes sleep in Drosophila melanogaster

Lactic acid bacteria (LAB) influence multiple aspects of host brain function via the production of active metabolites in the gut, which is known as the pre/probiotic action. However, little is known about the biogenic effects of LAB on host brain function. Here, we reported that the Lactobacillus plantarum SBT2227 promoted sleep in Drosophila melanogaster. Administration of SBT2227 primarily increased the amount of sleep and decreased sleep latency at the beginning of night-time. The sleep-promoting effects of SBT2227 were independent of the existing gut flora. Furthermore, heat treatment or mechanical crushing of SBT2227 did not suppress the sleep-promoting effects, indicative of biogenic action. Transcriptome analysis and RNAi mini-screening for gut-derived peptide hormones revealed the requirement of neuropeptide F, a homolog of the mammalian neuropeptide Y, for the action of SBT2227. These biogenic effects of SBT2227 on the host sleep provide new insights into the interaction between the brain and gut bacteria.

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Lactobacillus plantarum SBT2227 promotes sleep at the onset of nighttime

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Existing intestinal microbes do not affect the SBT2227 sleep effect

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Heat-stable intracellular/intramembrane components are candidates for active substances

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Neuropeptide F is required for the sleep-promoting effect of SBT2227