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

Harnessing Gut Microbiota for Biomimetic Innovations in Health and Biotechnology

The gut microbiota is a complex and dynamic ecosystem that plays a fundamental role in human health by regulating immunity, metabolism, and the gut-brain axis. Beyond its critical physiological functions, it has emerged as a rich source of inspiration for biomimetic innovations in healthcare and biotechnology. This review explores the transformative potential of microbiota-based biomimetics, focusing on key biological mechanisms such as resilience, self-regulation, and quorum sensing. These mechanisms have inspired the development of innovative applications, including personalized probiotics, synbiotics, artificial microbiomes, bioinspired biosensors, and bioremediation systems. Such technologies aim to emulate and optimize the intricate functions of microbial ecosystems, addressing challenges in healthcare and environmental sustainability. The integration of advanced technologies, such as artificial intelligence, bioengineering, and multi-omics approaches, has further accelerated the potential of microbiota biomimetics. These tools enable the development of precision therapies tailored to individual microbiota profiles, enhance the efficacy of diagnostic systems, and facilitate the design of environmentally sustainable solutions, such as waste-to-energy systems and bioremediation platforms. Emerging areas of innovation, including gut-on-chip models and synthetic biology, offer unprecedented opportunities for studying and applying microbiota principles in controlled environments. Despite these advancements, challenges remain. The replication of microbial complexity in artificial environments, ethical concerns regarding genetically engineered microorganisms, and equitable access to advanced therapies are critical hurdles that must be addressed. This review underscores the importance of interdisciplinary collaboration and public awareness in overcoming these barriers and ensuring the responsible development of microbiota-based solutions. By leveraging the principles of microbial ecosystems, microbiota biomimetics represents a promising frontier in healthcare and sustainability. This approach has the potential to revolutionize therapeutic strategies, redefine diagnostic tools, and address global challenges, paving the way for a more personalized, efficient, and sustainable future in medicine and biotechnology.

Crosstalk Between the Nervous System and Colorectal Cancer

The nervous system is the dominant regulatory system in the human body. The traditional theory is that tumors lack innervation. However, an increasing number of studies have shown complex bidirectional interactions between tumors and the nervous system. Globally, colorectal cancer (CRC) is the third most common cancer. With the rise of tumor neuroscience, the role of nervous system imbalances in the occurrence and development of CRC has attracted increasing amounts of attention. However, there are still many gaps in the research on the interactions and mechanisms involved in the nervous system in CRC. This article systematically reviews emerging research on the bidirectional relationships between the nervous system and CRC, focusing on the following areas: (1) Effects of the nervous system on colon cancer. (2) Effects of CRC on the nervous system. (3) Treatment of CRC associated with the nervous system.

Role of oral-gut-brain axis in psychiatric and neurological disorders

The oral cavity and gut are two important microbial habitats in the human body, harboring the most ecologically rich and taxonomically diverse microbial communities in humans, which play a key role in microbiome related diseases. In recent years, the emerging concept of the oral-gut-brain axis has attracted widespread attention in the fields of neuroscience, digestive science, and microbiology. It is not only an anatomical description, but also a comprehensive concept that covers multiple physiological functions and pathological mechanisms. Simply put, the oral-gut-brain axis refers to the complex network that connects the mouth, gut, and brain tightly together through neural connections and hormonal and immune pathways. With the deepening of research on the oral-gut-brain axis theory, more and more evidence shows that it plays an important role in depression, Parkinson's disease, and other neurodegenerative diseases. This article reviews the recent progress in research of the oral-gut-brain axis in psychiatric and neurological diseases.

The relationship between acrylamide and neurodegenerative diseases: gut microbiota as a new intermediate cue

Acrylamide (AA), a compound formed during the thermal processing of high-carbohydrate foods, has been implicated in the onset and progression of neurodegenerative diseases. An increasing number of reports support that gut microbiota plays a significant role in brain function and diseases, suggesting it may act as a mediator between AA exposure and the development of neurodegenerative diseases. Available studies have shown that AA intake affects the composition of the gut microbiota and the integrity of the intestinal barrier, both of which are often thought to be associated with the pathogenesis of neurodegenerative diseases, given the numerous evidences linking gut microbiota with the brain. Based on the current understanding, this paper discusses that AA induces the onset and progression of neurodegenerative diseases by disrupting the composition of the gut microbiota and the structure of the intestinal barrier. Furthermore, it explores the interaction between probiotics and AA exposure, as well as the potential for polysaccharides and polyphenols to improve the gut microenvironment, which provides novel perspectives on modulating the neurodegenerative diseases caused by AA exposure through diet.

Gut microbiota and Alzheimer's disease: Exploring natural product intervention and the Gut-Brain axis for therapeutic strategies

Numerous studies conducted over the last ten years have shown a strong correlation between the gut microbiota and the onset and progression of Alzheimer's disease (AD). However, the exact underlying mechanism is still unknown. An ongoing communication mechanism linking the gut and the brain is highlighted by the term "microbiota-gut-brain axis," which was originally coined the "gut-brain axis." Key metabolic, endocrine, neurological, and immunological mechanisms are involved in the microbiota‒gut‒brain axis and are essential for preserving brain homeostasis. Thus, the main emphasis of this review is how the gut microbiota contributes to the development of AD and how various natural products intervene in this disease. The first part of the review provides an outline of various pathways and relationships between the brain and gut microbiota, and the second part provides various mechanisms involved in the gut microbiota and AD. Finally, this review provides knowledge about natural products and their effectiveness in treating gut microbiota-induced AD. AD may be treated in the future by altering the gut microbiota with a customized diet, probiotics/prebiotics, plant products, and natural products. This entails altering the microbiological partners and products (such as amyloid protein) that these partners generate.

The role of enteric nervous system and GDNF in depression: Conversation between the brain and the gut

Depression is a debilitating mental disorder that causes a persistent feeling of sadness and loss of interest. Approximately 280 million individuals worldwide suffer from depression by 2023. Despite the heavy medical and social burden imposed by depression, pathophysiology remains incompletely understood. Emerging evidence indicates various bidirectional interplay enable communication between the gut and brain. These interplays provide a link between intestinal and central nervous system as well as feedback from cortical and sensory centers to enteric activities, which also influences physiology and behavior in depression. This review aims to overview the significant role of the enteric nervous system (ENS) in the pathophysiology of depression and gut-brain axis's contribution to depressive disorders. Additionally, we explore the alterations in enteric glia cells (EGCs) and glial cell line-derived neurotrophic factor (GDNF) in depression and their involvement in neuronal support, intestinal homeostasis maintains and immune response activation. Modulating ENS function, EGCs and GDNF level could serve as novel strategies for future antidepressant therapy.

The emerging roles of neuroactive components produced by gut microbiota

BACKGROUND

As a multifunctional ecosystem, the human digestive system contains a complex network of microorganisms, collectively known as gut microbiota. This consortium composed of more than 1013 microorganisms and Firmicutes and Bacteroidetes are the dominant microbes. Gut microbiota is increasingly recognized for its critical role in physiological processes beyond digestion. Gut microbiota participates in a symbiotic relationship with the host and takes advantage of intestinal nutrients and mutually participates in the digestion of complex carbohydrates and maintaining intestinal functions.

METHOD AND RESULT

We reviewed the neuroactive components produced by gut microbiota. Interestingly, microbiota plays a crucial role in regulating the activity of the intestinal lymphatic system, regulation of the intestinal epithelial barrier, and maintaining the tolerance to food immunostimulating molecules. The gut-brain axis is a two-way communication pathway that links the gut microbiota to the central nervous system (CNS) and importantly is involved in neurodevelopment, cognition, emotion and synaptic transmissions. The connections between gut microbiota and CNS are via endocrine system, immune system and vagus nerve.

CONCLUSION

The gut microbiota produces common neurotransmitters and neuromodulators of the nervous system. These compounds play a role in neuronal functions, immune system regulation, gastrointestinal homeostasis, permeability of the blood brain barrier and other physiological processes. This review investigates the essential aspects of the neurotransmitters and neuromodulators produced by gut microbiota and their implications in health and disease.

Food Allergy, Nutrition, Psychology, and Health

This article explores food allergy and the nascent field of nutritional psychiatry. Individuals with food allergy experience lower levels of "food freedom" than their nonallergic counterparts, which can create cognitive, emotional, social, nutritional, and financial burdens. Patterns of food avoidance may influence neuroinflammatory states and the gut microbiome; these changes may be associated with neuropsychiatric symptoms. Food restriction may promote disruption of the microbiome neuroimmune axis, which has been linked to various allergic diseases. Targeted psychological counseling strategies can provide benefit. Food allergy and restricted diets may impact dietary health benefits.

Schwann cells and enteric glial cells: Emerging stars in colorectal cancer

Cancer neuroscience, a promising field dedicated to exploring interactions between cancer and the nervous system, has attracted growing attention. The gastrointestinal tracts exhibit extensive innervation, notably characterized by intrinsic innervation. The gut harbors a substantial population of glial cells, including Schwann cells wrapping axons of neurons in the peripheral nervous system and enteric glial cells intricately associated with intrinsic innervation. Glial cells play a crucial role in maintaining the physiological functions of the intestine, encompassing nutrient absorption, barrier integrity, and immune modulation. Nevertheless, it has only been in recent times that the significance of glial cells within colorectal cancer (CRC) has begun to receive considerable attention. Emerging data suggests that glial cells in the gut contribute to the progression and metastasis of CRC, by interacting with cancer cells, influencing inflammation, and modulating the tumor microenvironment. Here, we summarize the significant roles of glial cells in the development and progression of CRC and discuss the latest technologies that can be integrated into this field for in-depth exploration, as well as potential specific targeted strategies for future exploration to benefit patients.

Rutin, a natural flavonoid glycoside, ameliorates zearalenone induced liver inflammation via inhibiting lipopolysaccharide gut leakage and NF-κB signaling pathway in mice

Zearalenone (ZEN) poses a potential threat on human and animal health partly through the nuclear factor (NF)-κB signaling pathway. In silico study suggested that rutin effective against TLR4 and NF-κB. A wetting test was designed to evaluate the effect and underlying mechanism of rutin in alleviating ZEN-induced inflammation in animals. Twenty-four female mice were randomly divided into 4 groups: control (basal diet), ZEN group (basal diet + ZEN), rutin group (basic diet + rutin), Z + R group (basal diet + rutin + ZEN). Results showed that rutin effectively alleviated ZEN-induced inflammation and damage of liver and jejunum in mice. Rutin addition reduced the content of lipopolysaccharide (LPS) in serum and liver mainly by improving the intestinal barrier function resulted from the production increase of short-chain fatty acids (SCFA). In sum, this study showed that rutin alleviated ZEN-induced liver inflammation and injury by modulating the gut microbiota, increasing the production of SCFA and improving intestinal barrier function, leading to the decrease of LPS in liver and the inhibition of MyD88 independent NF-κB signaling pathway in mice. Specifically, these findings may provide useful insights into the screening of functional natural compounds and its action mechanism to alleviate ZEN induced liver inflammation.

The impact of alcohol consumption on the relationship between depression and chronic diarrhea: a cross-sectional study analysis on NHANES (2005-2010)

Background

Alcohol consumption, depression, and chronic diarrhea are all public health issues of concern, with irreversible consequences for individual health and significant economic burdens on health care systems. Previous studies have shown that depression increases the risk of developing chronic diarrhea, but few studies have explored whether alcohol consumption has an effect on the relationship between depression and chronic diarrhea.

Objective

To explore the effect of alcohol consumption on the relationship between depression and chronic diarrhea.

Methods

12,538 adults (≥20 years) in NHANES from 2005-2010 were analyzed. Participants were stratified according to drinking status, and differences between the risk of depression and chronic diarrhea among participants who drank alcohol or not were assessed using multiple regression analysis and likelihood ratio tests.

Results

In this cross sectional, after adding possible confounders, the prevalence of depression with chronic diarrhea was higher in the drinking population than in the non-drinking population (OR,2.34, 95%CI:1.84-2.98 and 1.26, 95%CI:0.85-1.86), with a likelihood ratio test of P=0.024.

Conclusion

Our findings suggest that there is a significant association between depression and chronic diarrhea and that alcohol consumption may increase the correlation between depression and chronic diarrhea. However, these findings require further prospective studies to provide more evidence.

Implications of Butyrate Signaling Pathways on the Motor Symptomatology of Parkinson's Disease and Neuroprotective Effects-Therapeutic Approaches: A Systematic Review

Parkinson's Disease (PD) is a prevalent neurodegenerative disorder characterized by motor and non-motor symptoms. Emerging evidence suggests that gut microbiota alterations, specifically involving short-chain fatty acids (SCFAs) like butyrate, may influence PD pathogenesis and symptomatology. This Systematic Review aims to synthesize current research on the role of butyrate in modulating motor symptoms and its neuroprotective effects in PD, providing insights into potential therapeutic approaches. A systematic literature search was conducted in April 2024 across databases, including ScienceDirect, Scopus, Wiley, and Web of Science, for studies published between 2000 and 2024. Keywords used were "neuroprotective effects AND butyrate AND (Parkinson disease OR motor symptoms)". Four authors independently screened titles, abstracts, and full texts, applying inclusion criteria focused on studies investigating butyrate regulation and PD motor symptoms. A total of 1377 articles were identified, with 40 selected for full-text review and 14 studies meeting the inclusion criteria. Data extraction was performed on the study population, PD models, methodology, intervention details, and outcomes. Quality assessment using the SYRCLE RoB tool highlighted variability in study quality, with some biases noted in allocation concealment and blinding. Findings indicate that butyrate regulation has a significant impact on improving motor symptoms and offers neuroprotective benefits in PD models. The therapeutic modulation of gut microbiota to enhance butyrate levels presents a promising strategy for PD symptom management.

The gut microbiota-brain axis in neurological disorders

Previous studies have shown a bidirectional communication between human gut microbiota and the brain, known as the microbiota-gut-brain axis (MGBA). The MGBA influences the host's nervous system development, emotional regulation, and cognitive function through neurotransmitters, immune modulation, and metabolic pathways. Factors like diet, lifestyle, genetics, and environment shape the gut microbiota composition together. Most research have explored how gut microbiota regulates host physiology and its potential in preventing and treating neurological disorders. However, the individual heterogeneity of gut microbiota, strains playing a dominant role in neurological diseases, and the interactions of these microbial metabolites with the central/peripheral nervous systems still need exploration. This review summarizes the potential role of gut microbiota in driving neurodevelopmental disorders (autism spectrum disorder and attention deficit/hyperactivity disorder), neurodegenerative diseases (Alzheimer's and Parkinson's disease), and mood disorders (anxiety and depression) in recent years and discusses the current clinical and preclinical gut microbe-based interventions, including dietary intervention, probiotics, prebiotics, and fecal microbiota transplantation. It also puts forward the current insufficient research on gut microbiota in neurological disorders and provides a framework for further research on neurological disorders.

Probiotics and the microbiota-gut-brain axis in neurodegeneration: Beneficial effects and mechanistic insights

Neurodegenerative diseases (NDs) are a group of heterogeneous disorders with a high socioeconomic burden. Although pharmacotherapy is currently the principal therapeutic approach for the management of NDs, mounting evidence supports the notion that the protracted application of available drugs would abate their dopaminergic outcomes in the long run. The therapeutic application of microbiome-based modalities has received escalating attention in biomedical works. In-depth investigations of the bidirectional communication between the microbiome in the gut and the brain offer a multitude of targets for the treatment of NDs or maximizing the patient's quality of life. Probiotic administration is a well-known microbial-oriented approach to modulate the gut microbiota and potentially influence the process of neurodegeneration. Of note, there is a strong need for further investigation to map out the mechanistic prospects for the gut-brain axis and the clinical efficacy of probiotics. In this review, we discuss the importance of microbiome modulation and hemostasis via probiotics, prebiotics, postbiotics and synbiotics in ameliorating pathological neurodegenerative events. Also, we meticulously describe the underlying mechanism of action of probiotics and their metabolites on the gut-brain axis in different NDs. We suppose that the present work will provide a functional direction for the use of probiotic-based modalities in promoting current practical treatments for the management of neurodegenerative-related diseases.

Stress and the gut-brain axis: an inflammatory perspective

The gut-brain axis (GBA) plays a dominant role in maintaining homeostasis as well as contributes to mental health maintenance. The pathways that underpin the axis expand from macroscopic interactions with the nervous system, to the molecular signals that include microbial metabolites, tight junction protein expression, or cytokines released during inflammation. The dysfunctional GBA has been repeatedly linked to the occurrence of anxiety- and depressive-like behaviors development. The importance of the inflammatory aspects of the altered GBA has recently been highlighted in the literature. Here we summarize current reports on GBA signaling which involves the immune response within the intestinal and blood-brain barrier (BBB). We also emphasize the effect of stress response on altering barriers' permeability, and the therapeutic potential of microbiota restoration by probiotic administration or microbiota transplantation, based on the latest animal studies. Most research performed on various stress models showed an association between anxiety- and depressive-like behaviors, dysbiosis of gut microbiota, and disruption of intestinal permeability with simultaneous changes in BBB integrity. It could be postulated that under stress conditions impaired communication across BBB may therefore represent a significant mechanism allowing the gut microbiota to affect brain functions.

Gut-Brain Axis in Focus: Polyphenols, Microbiota, and Their Influence on α-Synuclein in Parkinson's Disease

With the recognition of the importance of the gut-brain axis in Parkinson's disease (PD) etiology, there is increased interest in developing therapeutic strategies that target α-synuclein, the hallmark abhorrent protein of PD pathogenesis, which may originate in the gut. Research has demonstrated that inhibiting the aggregation, oligomerization, and fibrillation of α-synuclein are key strategies for disease modification. Polyphenols, which are rich in fruits and vegetables, are drawing attention for their potential role in this context. In this paper, we reviewed how polyphenols influence the composition and functional capabilities of the gut microbiota and how the resulting microbial metabolites of polyphenols may potentially enhance the modulation of α-synuclein aggregation. Understanding the interaction between polyphenols and gut microbiota and identifying which specific microbes may enhance the efficacy of polyphenols is crucial for developing therapeutic strategies and precision nutrition based on the microbiome.

From dysbiosis to defense: harnessing the gut microbiome in HIV/SIV therapy

BACKGROUND

Although the microbiota has been extensively associated with HIV pathogenesis, the majority of studies, particularly those using omics techniques, are largely correlative and serve primarily as a basis for hypothesis generation. Furthermore, most have focused on characterizing the taxonomic composition of the bacterial component, often overlooking other levels of the microbiome. The intricate mechanisms by which the microbiota influences immune responses to HIV are still poorly understood. Interventional studies on gut microbiota provide a powerful tool to test the hypothesis of whether we can harness the microbiota to improve health outcomes in people with HIV.

RESULTS

Here, we review the multifaceted role of the gut microbiome in HIV/SIV disease progression and its potential as a therapeutic target. We explore the complex interplay between gut microbial dysbiosis and systemic inflammation, highlighting the potential for microbiome-based therapeutics to open new avenues in HIV management. These include exploring the efficacy of probiotics, prebiotics, fecal microbiota transplantation, and targeted dietary modifications. We also address the challenges inherent in this research area, such as the difficulty in inducing long-lasting microbiome alterations and the complexities of study designs, including variations in probiotic strains, donor selection for FMT, antibiotic conditioning regimens, and the hurdles in translating findings into clinical practice. Finally, we speculate on future directions for this rapidly evolving field, emphasizing the need for a more granular understanding of microbiome-immune interactions, the development of personalized microbiome-based therapies, and the application of novel technologies to identify potential therapeutic agents.

CONCLUSIONS

Our review underscores the importance of the gut microbiome in HIV/SIV disease and its potential as a target for innovative therapeutic strategies.

Oral quercetin nanoparticles in hydrogel microspheres alleviate high-altitude sleep disturbance based on the gut-brain axis

High-altitude sleep disturbance is a common symptom of acute mountain sickness, which can be alleviated via modulation of the gut-brain axis. Quercetin (Que) is used to modulate gut microbiota and serves as a potential drug to regulate the gut-brain axis, but the poor solubility and bioavailability affect its biological functions. Here, Que nanoparticles (QNPs) were prepared with zein using an antisolvent method, and QNP-loaded calcium alginate hydrogel microspheres (QNP@HMs) were prepared using electrospinning technology to improve the gastrointestinal stability and intestinal adhesion of QNPs. In the mouse model of high-altitude sleep disturbance, oral administration of QNP@HMs before the mice entering high altitude prolonged sleep duration, improved blood cell recovery, spontaneous behavior and short-term memory, and reduced such inflammation factors as TNF-α and iNOS. Moreover, QNP@HMs enhanced the abundance of probiotics in the gut, including Lactobacillus and Lachnospira, and reduced intestinal inflammation. However, in the mice after gut sterilization by long-term oral antibiotics, QNP@HMs showed no therapeutic effect. QNP@HMs are a promising medication for the prevention of high-altitude sleep disturbance based on the gut-brain axis.

Accumulation of Alpha-Synuclein and Increase in the Inflammatory Response in the substantia nigra, Jejunum, and Colon in a Model of O3 Pollution in Rats

This work aimed to study the effect of repeated exposure to low doses of ozone on alpha-synuclein and the inflammatory response in the substantia nigra, jejunum, and colon. Seventy-two male Wistar rats were divided into six groups. Each group received one of the following treatments: The control group was exposed to air. The ozone groups were exposed for 7, 15, 30, 60, and 90 days for 0.25 ppm for four hours daily. Afterward, they were anesthetized, and their tissues were extracted and processed using Western blotting, immunohistochemistry, and qPCR. The results indicated a significant increase in alpha-synuclein in the substantia nigra and jejunum from 7 to 60 days of exposure and an increase in NFκB from 7 to 90 days in the substantia nigra, while in the jejunum, a significant increase was observed at 7 and 15 days and a decrease at 60 and 90 days for the colon. Interleukin IL-17 showed an increase at 90 days in the substantia nigra in the jejunum and increases at 30 days and in the colon at 15 and 90 days. Exposure to ozone increases the presence of alpha-synuclein and induces the loss of regulation of the inflammatory response, which contributes significantly to degenerative processes.

The Interplay of Sports and Nutrition in Neurological Health and Recovery

This comprehensive review explores the dynamic relationship between sports, nutrition, and neurological health. Focusing on recent clinical advancements, it examines how physical activity and dietary practices influence the prevention, treatment, and rehabilitation of various neurological conditions. The review highlights the role of neuroimaging in understanding these interactions, discusses emerging technologies in neurotherapeutic interventions, and evaluates the efficacy of sports and nutritional strategies in enhancing neurological recovery. This synthesis of current knowledge aims to provide a deeper understanding of how lifestyle factors can be integrated into clinical practices to improve neurological outcomes.

Clinical and Preclinical Evidence for Gut Microbiome Mechanisms in Substance Use Disorders

Substance use disorders are a set of recalcitrant neuropsychiatric conditions that cause tremendous morbidity and mortality and are among the leading causes of loss of disability-adjusted life years worldwide. While each specific substance use disorder is driven by problematic use of a different substance, they all share a similar pattern of escalating and out-of-control substance use, continued use despite negative consequences, and a remitting/relapsing pattern over time. Despite significant advances in our understanding of the neurobiology of these conditions, current treatment options remain few and are ineffective for too many individuals. In recent years, there has been a rapidly growing body of literature demonstrating that the resident population of microbes in the gastrointestinal tract, collectively called the gut microbiome, plays an important role in modulating brain and behavior in preclinical and clinical studies of psychiatric disease. While these findings have not yet been translated into clinical practice, this remains an important and exciting avenue for translational research. In this review, we highlight the current state of microbiome-brain research within the substance use field with a focus on both clinical and preclinical studies. We also discuss potential neurobiological mechanisms underlying microbiome effects on models of substance use disorder and propose future directions to bring these findings from bench to bedside.

Restraint stress-associated gastrointestinal injury and implications from the Evans blue-fed restraint stress mouse model

The association between stress and gastrointestinal (GI) tract diseases is well established, while the exact mechanism remains elusive. As a result, it is urgent to establish mouse models to investigate restraint stress-associated GI leakage, but current models have their limitations. A new Evans blue-fed restraint mouse model has recently been developed that allows researchers to study restraint stress-associated GI leakage in live animals. This review article will focus on this model, including its mechanisms, clinical implications, and applications for studying restraint stress-associated GI injury. Recent findings from studies using this model will also be highlighted, along with their potential for diagnosis and treatment. The article aims to discuss about current research and provide recommendations for further study, ultimately improving our understanding of the link between stress and GI injury and improving patient outcomes.

Understanding food allergy through neuroimmune interactions in the gastrointestinal tract

Food allergies are adverse immune reactions to food proteins in the absence of oral tolerance, and the incidence of allergies to food, including peanut, cow's milk, and shellfish, has been increasing globally. Although advancements have been made toward understanding the contributions of the type 2 immune response to allergic sensitization, crosstalk between these immune cells and neurons of the enteric nervous system is an area of emerging interest in the pathophysiology of food allergy, given the close proximity of neuronal cells of the enteric nervous system and type 2 effector cells, including eosinophils and mast cells. At mucosal sites, such as the gastrointestinal tract, neuroimmune interactions contribute to the sensing and response to danger signals from the epithelial barrier. This communication is bidirectional, as immune cells express receptors for neuropeptides and transmitters, and neurons express cytokine receptors, allowing for the detection of and response to inflammatory insults. In addition, it seems that neuromodulation of immune cells including mast cells, eosinophils, and innate lymphoid cells is critical for amplification of the type 2 allergic immune response. As such, neuroimmune interactions may be critical targets for future food allergy therapies. This review evaluates the contributions of local enteric neuroimmune interactions to the underlying immune response in food allergy and discusses considerations for future investigations into targeting neuroimmune pathways for treatment of food allergies.

The link between the gut microbiome, inflammation, and Parkinson's disease

As our society ages, the growing number of people with Parkinson's disease (PD) puts tremendous pressure on our society. Currently, there is no effective treatment for PD, so there is an urgent need to find new treatment options. In recent years, increasing studies have shown a strong link between gut microbes and PD. In this review, recent advances in research on gut microbes in PD patients were summarized. Increased potential pro-inflammatory microbes and decreased potential anti-inflammatory microbes are prominent features of gut microbiota in PD patients. These changes may lead to an increase in pro-inflammatory substances (such as lipopolysaccharide and H2S) and a decrease in anti-inflammatory substances (such as short-chain fatty acids) to promote inflammation in the gut. This gut microbiota-mediated inflammation will lead to pathological α-synuclein accumulation in the gut, and the inflammation and α-synuclein can spread to the brain via the microbiota-gut-brain axis, thereby promoting neuroinflammation, apoptosis of dopaminergic neurons, and ultimately the development of PD. This review also showed that therapies based on gut microbiota may have a bright future for PD. However, more research and new approaches are still needed to clarify the causal relationship between gut microbes and PD and to determine whether therapies based on gut microbiota are effective in PD patients. KEY POINTS: • There is a strong association between gut microbes and PD. • Inflammation mediated by gut microbes may promote the development of PD. • Therapies based on the gut microbiome provide a promising strategy for PD prevention.

Higher Bifidobacterium spp. fecal abundance is associated with a lower prevalence of hyperglycemia and cardiovascular risk markers among schoolchildren from Bahia, Brazil

The gut microbiome has recently been the subject of considerable scientific interest due to its essential bodily functions. Several factors can change the composition and function of the gut microbiome, and dietary habits are one of the most important contributors. Despite the recognition of the probiotic effects related to the genus Bifidobacterium spp. (BIF) studies aiming to assess its relationship with metabolic outcomes show conflicting results, particularly in the child population. This cross-sectional study aimed to evaluate the fecal abundance of BIF in a group of schoolchildren from public schools in Bahia, Brazil, and to investigate their relationship with food consumption and laboratory and anthropometric characteristics. A sample of 190 subjects aged 5 to 19y was randomly selected for dietary, laboratory, and anthropometric assessment. Fecal BIF abundance assessment was performed using the Real-Time Polymerase Chain Reaction assay. Fecal BIF abundance was higher among subjects who had lower intakes of meat. The abundance of BIF was also higher among subjects with lower Waist Circumference and Waist-to-Height Ratio (WHtR). Low BIF abundance was associated with a higher prevalence of hyperglycemia (PR 1.04, 95%CI 1.02-1.07, p = 0.001) and high WHtR (PR 1.04, 95%CI 1.01-1, 08, p = 0.015). These findings allow us to conclude that BIF fecal abundance is related to dietary and anthropometric parameters in schoolchildren, and its increase is associated with positive metabolic outcomes.

Gut Microbial Metabolome and Dysbiosis in Neurodegenerative Diseases: Psychobiotics and Fecal Microbiota Transplantation as a Therapeutic Approach-A Comprehensive Narrative Review

The comprehensive narrative review conducted in this study delves into the mechanisms of communication and action at the molecular level in the human organism. The review addresses the complex mechanism involved in the microbiota-gut-brain axis as well as the implications of alterations in the microbial composition of patients with neurodegenerative diseases. The pathophysiology of neurodegenerative diseases with neuronal loss or death is analyzed, as well as the mechanisms of action of the main metabolites involved in the bidirectional communication through the microbiota-gut-brain axis. In addition, interventions targeting gut microbiota restructuring through fecal microbiota transplantation and the use of psychobiotics-pre- and pro-biotics-are evaluated as an opportunity to reduce the symptomatology associated with neurodegeneration in these pathologies. This review provides valuable information and facilitates a better understanding of the neurobiological mechanisms to be addressed in the treatment of neurodegenerative diseases.

Microbiome and tryptophan metabolomics analysis in adolescent depression: roles of the gut microbiota in the regulation of tryptophan-derived neurotransmitters and behaviors in human and mice

BACKGROUND

Adolescent depression is becoming one of the major public health concerns, because of its increased prevalence and risk of significant functional impairment and suicidality. Clinical depression commonly emerges in adolescence; therefore, the prevention and intervention of depression at this stage is crucial. Recent evidence supports the importance of the gut microbiota (GM) in the modulation of multiple functions associated with depression through the gut-brain axis (GBA). However, the underlying mechanisms remain poorly understood. Therefore, in the current study, we aimed to screen the microbiota out from healthy and depressive adolescents, delineate the association of the targeted microbiota and the adolescent depression, address the salutary effects of the targeted microbiota on anti-depressive behaviors in mice involving the metabolism of the tryptophan (Trp)-derived neurotransmitters along the GBA.

RESULTS

Here, we found the gut microbiota from healthy adolescent volunteers, first diagnosis patients of adolescent depression, and sertraline interveners after first diagnosis displayed significant difference, the relative abundance of Faecalibacterium, Roseburia, Collinsella, Blautia, Phascolarctobacterium, Lachnospiraceae-unclassified decreased in adolescent depressive patients, while restored after sertraline treatment. Of note, the Roseburia abundance exhibited a high efficiency in predicting adolescent depression. Intriguingly, transplantation of the fecal microbiota from healthy adolescent volunteers to the chronic restraint stress (CRS)-induced adolescent depressed mice significantly ameliorated mouse depressive behaviors, in which the Roseburia exerted critical roles, since its effective colonization in the mouse colon resulted in remarkably increased 5-HT level and reciprocally decreased kynurenine (Kyn) toxic metabolites quinolinic acid (Quin) and 3-hydroxykynurenine (3-HK) levels in both the mouse brain and colon. The specific roles of the Roseburia were further validated by the target bacteria transplantation mouse model, Roseburia intestinalis (Ri.) was gavaged to mice and importantly, it dramatically ameliorated CRS-induced mouse depressive behaviors, increased 5-HT levels in the brain and colon via promoting tryptophan hydroxylase-2 (TPH2) or -1 (TPH1) expression. Reciprocally, Ri. markedly restrained the limit-step enzyme responsible for kynurenine (indoleamine2,3-dioxygenase 1, IDO1) and quinolinic acid (3-hydroxyanthranilic acid 3,4-dioxygenase, 3HAO) generation, thereby decreased Kyn and Quin levels. Additionally, Ri. administration exerted a pivotal role in the protection of CRS-induced synaptic loss, microglial activation, and astrocyte maintenance.

CONCLUSIONS

This study is the first to delineate the beneficial effects of Ri. on adolescent depression by balancing Trp-derived neurotransmitter metabolism and improving synaptogenesis and glial maintenance, which may yield novel insights into the microbial markers and therapeutic strategies of GBA in adolescent depression. Video Abstract.

Global Impacts of Western Diet and Its Effects on Metabolism and Health: A Narrative Review

The Western diet is a modern dietary pattern characterized by high intakes of pre-packaged foods, refined grains, red meat, processed meat, high-sugar drinks, candy, sweets, fried foods, conventionally raised animal products, high-fat dairy products, and high-fructose products. The present review aims to describe the effect of the Western pattern diet on the metabolism, inflammation, and antioxidant status; the impact on gut microbiota and mitochondrial fitness; the effect of on cardiovascular health, mental health, and cancer; and the sanitary cost of the Western diet. To achieve this goal, a consensus critical review was conducted using primary sources, such as scientific articles, and secondary sources, including bibliographic indexes, databases, and web pages. Scopus, Embase, Science Direct, Sports Discuss, ResearchGate, and the Web of Science were used to complete the assignment. MeSH-compliant keywords such "Western diet", "inflammation", "metabolic health", "metabolic fitness", "heart disease", "cancer", "oxidative stress", "mental health", and "metabolism" were used. The following exclusion criteria were applied: (i) studies with inappropriate or irrelevant topics, not germane to the review's primary focus; (ii) Ph.D. dissertations, proceedings of conferences, and unpublished studies. This information will allow for a better comprehension of this nutritional behavior and its effect on an individual's metabolism and health, as well as the impact on national sanitary systems. Finally, practical applications derived from this information are made.

Clostridium butyricum improves cognitive dysfunction in ICV-STZ-induced Alzheimer's disease mice via suppressing TLR4 signaling pathway through the gut-brain axis

In recent years, the relationship between gut-brain axis and Alzheimer's disease (AD) attracted increasing attention. The aim of this study is to investigate the therapeutic effect of Clostridium butyricum (CB) on intraventricular injection of streptozotocin (ICV-STZ)-induced mice and the potential mechanisms. ICV-STZ mice were treated with CB by gavage for 21 consecutive days. The pharmacological effect of CB was assessed by behavior test, brain tissue H&E staining and tau protein phosphorylation levels of hippocampus tissues. The expression levels of TLR4, MYD88, NF-κB p65, TNF-α, iNOS, Occludin and ZO-1 in hippocampal and colonic tissues were detected by Western-blot method. 16S rRNA gene sequencing analysis was used to analyze the intestinal microbiota of mice. The results showed that CB improved the cognitive dysfunction of ICV-STZ mice, restored the structure and cell number of hippocampal and cortical neurons, decreased the protein levels of pSer404-tau protein in hippocampal tissues and TLR4, MYD88, NF-κB p65 and iNOS in hippocampal and colonic tissues, and increased the protein levels of Occludin and ZO-1 in colonic tissues. Meanwhile, CB reversed the changes of intestinal microbiota in AD mice. Therefore, the mechanisms of cognitive function and brain pathological changes in AD mice improved by CB may be related to the regulation of TLR4 signaling pathway and intestinal microbiota. This study supports the potential anti-AD effect of CB and initially revealed its pharmacological mechanism of CB, providing a theoretical basis for further clinical application of CB.

Systemic sclerosis gastrointestinal dysmotility: risk factors, pathophysiology, diagnosis and management

Nearly all patients with systemic sclerosis (SSc) are negatively affected by dysfunction in the gastrointestinal tract, and the severity of gastrointestinal disease in SSc correlates with high mortality. The clinical complications of this dysfunction are heterogeneous and include gastro-oesophageal reflux disease, gastroparesis, small intestinal bacterial overgrowth, intestinal pseudo-obstruction, malabsorption and the requirement for total parenteral nutrition. The abnormal gastrointestinal physiology that promotes the clinical manifestations of SSc gastrointestinal disease throughout the gastrointestinal tract are diverse and present a range of therapeutic targets. Furthermore, the armamentarium of medications and non-pharmacological interventions that can benefit affected patients has substantially expanded in the past 10 years, and research is increasingly focused in this area. Here, we review the details of the gastrointestinal complications in SSc, tie physiological abnormalities to clinical manifestations, detail the roles of standard and novel therapies and lay a foundation for future investigative work.

Role of enteric glia and microbiota-gut-brain axis in parkinson disease pathogenesis

The microbiota-gut-brain axis or simple gut-brain axis (GBA) is a complex and interactive bidirectional communication network linking the gut to the brain. Alterations in the composition of the gut microbiome have been linked to GBA dysfunction, central nervous system (CNS) inflammation, and dopaminergic degeneration, as those occurring in Parkinson's disease (PD). Besides inflammation, the activation of brain microglia is known to play a central role in the damage of dopaminergic neurons. Inflammation is attributed to the toxic effect of aggregated α-synuclein, in the brain of PD patients. It has been suggested that the α-synuclein misfolding might begin in the gut and spread "prion-like", via the vagus nerve into the lower brainstem and ultimately to the midbrain, known as the Braak hypothesis. In this review, we discuss how the microbiota-gut-brain axis and environmental influences interact with the immune system to promote a pro-inflammatory state that is involved in the initiation and progression of misfolded α-synuclein proteins and the beginning of the early non-motor symptoms of PD. Furthermore, we describe a speculative bidirectional model that explains how the enteric glia is involved in the initiation and spreading of inflammation, epithelial barrier disruption, and α-synuclein misfolding, finally reaching the central nervous system and contributing to neuroinflammatory processes involved with the initial non-motor symptoms of PD.

Gut microbiome at the crossroad of genetic variants and behavior disorders

Genetic variants are traditionally known to shape the susceptibility to neuropsychiatric disorders. An increasing number of studies indicate that remodeling of the gut microbiome by genetic variance serves as a versatile regulator of gut-brain crosstalk and behavior. Evidence also emerges that certain behavioral symptoms are specifically attributed to gut microbial remodeling and gut-to-brain signals, which necessitates rethinking of neuropsychiatric disease etiology and treatment from a systems perspective of reciprocal gene-microbe interactions. Here, we present an emerging picture of how gut microbes and host genetics interactively shape complex psychiatric phenotypes. We illustrate the growing understanding of how the gut microbiome is shaped by genetic changes and its connection to behavioral outcome. We also discuss working strategies and open questions in translating associative gene-microbiome-behavior findings into causal links and novel targets for neurobehavioral disorders. Dual targeting of the genetic and microbial factors may expand the space of drug discovery for neuropsychiatric diseases.

Mucosal Immunity and the Gut-Microbiota-Brain-Axis in Neuroimmune Disease

Recent advances in next-generation sequencing (NGS) technologies have opened the door to a wellspring of information regarding the composition of the gut microbiota. Leveraging NGS technology, early metagenomic studies revealed that several diseases, such as Alzheimer's disease, Parkinson's disease, autism, and myalgic encephalomyelitis, are characterized by alterations in the diversity of gut-associated microbes. More recently, interest has shifted toward understanding how these microbes impact their host, with a special emphasis on their interactions with the brain. Such interactions typically occur either systemically, through the production of small molecules in the gut that are released into circulation, or through signaling via the vagus nerves which directly connect the enteric nervous system to the central nervous system. Collectively, this system of communication is now commonly referred to as the gut-microbiota-brain axis. While equally important, little attention has focused on the causes of the alterations in the composition of gut microbiota. Although several factors can contribute, mucosal immunity plays a significant role in shaping the microbiota in both healthy individuals and in association with several diseases. The purpose of this review is to provide a brief overview of the components of mucosal immunity that impact the gut microbiota and then discuss how altered immunological conditions may shape the gut microbiota and consequently affect neuroimmune diseases, using a select group of common neuroimmune diseases as examples.

Lipopolysaccharides (LPSs) as Potent Neurotoxic Glycolipids in Alzheimer's Disease (AD)

Lipopolysaccharides (LPSs) are microbiome-derived glycolipids that are among the most potent pro-inflammatory neurotoxins known. In Homo sapiens, the major sources of LPSs are gastrointestinal (GI)-tract-resident facultative anaerobic Gram-negative bacilli, including Bacteroides fragilis and Escherichia coli. LPSs have been abundantly detected in aged human brain by multiple independent research investigators, and an increased abundance of LPSs around and within Alzheimer's disease (AD)-affected neurons has been found. Microbiome-generated LPSs and other endotoxins cross GI-tract biophysiological barriers into the systemic circulation and across the blood-brain barrier into the brain, a pathological process that increases during aging and in vascular disorders, including 'leaky gut syndrome'. Further evidence indicates that LPSs up-regulate pro-inflammatory transcription factor complex NF-kB (p50/p65) and subsequently a set of NF-kB-sensitive microRNAs, including miRNA-30b, miRNA-34a, miRNA-146a and miRNA-155. These up-regulated miRNAs in turn down-regulate a family of neurodegeneration-associated messenger RNA (mRNA) targets, including the mRNA encoding the neuron-specific neurofilament light (NF-L) chain protein. While NF-L has been reported to be up-regulated in peripheral biofluids in AD and other progressive and lethal pro-inflammatory neurodegenerative disorders, NF-L is significantly down-regulated within neocortical neurons, and this may account for neuronal atrophy, loss of axonal caliber and alterations in neuronal cell shape, modified synaptic architecture and network deficits in neuronal signaling capacity. This paper reviews and reveals the most current findings on the neurotoxic aspects of LPSs and how these pro-inflammatory glycolipids contribute to the biological mechanism of progressive, age-related and ultimately lethal neurodegenerative disorders. This recently discovered gut-microbiota-derived LPS-NF-kB-miRNA-30b-NF-L pathological signaling network: (i) underscores a direct positive pathological link between the LPSs of GI-tract microbes and the inflammatory neuropathology, disordered cytoskeleton, and disrupted synaptic-signaling of the AD brain and stressed human brain cells in primary culture; and (ii) is the first example of a microbiome-derived neurotoxic glycolipid having significant detrimental miRNA-mediated actions on the expression of NF-L, an abundant filamentous protein known to be important in the maintenance of neuronal and synaptic homeostasis.