The Gut-Brain Axis: How Microbiota and Host Inflammasome Influence Brain Physiology and Pathology

Analysis of gut microbiota and depression and anxiety: Mendelian randomization from three datasets

BACKGROUND

Emerging evidence supports gut microbiota's association with mental distress, particularly depression and anxiety, the microbiota-gut-brain axis was the believed to be the underlying mechanism. This study investigated the causal relationships between specific gut microbiota and depression and anxiety disorders using large-scale genome-wide association study (GWAS) data.

METHODS

A two-sample bidirectional Mendelian randomization (MR) analysis was conducted to explore the causal effects of 211 microbial taxa on depression and anxiety across three large GWAS databases: FinnGen, Pan-UKBB, and PGC. Sensitive analyses were followed to validate the robustness of results. Random-effect meta-analysis was further performed to enhance the statistical power.

RESULTS

The MR analysis revealed that the Bifidobacteriales (IVW: OR 0.90, 95 %CI 0.83 to 0.98) and Bifidobacteriaceae (IVW: OR 0.90, 95 %CI 0.83 to 0.98) had a protective effect against depression. Clostridiales (cML-MA: OR 0.88, 95 %CI 0.81 to 0.95) and Parasutterella (cML-MA: OR 0.75, 95 %CI 0.64 to 0.88) showed negative associations with depression. Increased abundance of Oxalobacteraceae (cML-MA: OR 1.78, 95 %CI 1.24 to 2.56), Deltaproteobacteria (cML-MA: OR 2.17, 95 %CI 1.38 to 3.40), and Desulfovibrionales (cML-MA: OR 2.22, 95 %CI 1.41 to 3.49) was associated with a higher risk of depression. For anxiety, protective effects were found for Actinobacteria (phylum: IVW: OR 0.83, 95 %CI 0.76 to 0.87; class: IVW: OR 0.84, 95 %CI 0.75 to 0.93), Bifidobacteriales (IVW: OR 0.80, 95 %CI 0.75 to 0.85), Bifidobacteriaceae (IVW: OR 0.80, 95 %CI 0.75 to 0.85) and Bifidobacterium [g] (IVW: OR 0.79, 95 %CI 0.74 to 0.84). Lactobacillaceae [f] (cML-MA: OR 1.18, 95 %CI 1.08 to 1.28), Clostridia [c] (cML-MA: OR 1.15, 95 %CI 0.1.06 to 1.26) and Clostridiales [o] (IVW: OR 1.15, 95 %CI 1.05 to 1.27) were associated with increased anxiety risk. Meta-analysis results indicated significant associations, particularly the protective effects of Actinobacteria (OR 0.90, 95 % CI, 0.83 to 0.98) and Clostridiaceae1 (OR 0.91, 95 % CI, 0.83 to 0.99) on depression and several taxa on anxiety. No significant instrumental variables for depression or anxiety on gut microbiota were identified.

CONCLUSIONS

Our findings highlight specific gut microbiota that are associated with depression and anxiety, underscoring the causal relationships between these intestinal microbes and psychiatric disorders. These results suggest potential strategies for mitigating disease symptoms and improving quality of life through microbiome-targeted therapies. Further studies, including randomized controlled trials and investigations into sex-specific effects, are essential to validate and expand upon these findings.

Non-starch polysaccharides and health: gut-target organ axis influencing obesity

Obesity is recognized as a global epidemic that can result in changes in the human body and metabolism. Accumulating evidence indicates that gut microbiota (GM) can affect the development of obesity. The GM not only plays a crucial role in digesting and absorbing nutrients, but also in maintaining the overall health of the host. Dietary supplements such as non-starch polysaccharides are mainly fermented by the GM in the colon. Recent findings suggest that shaping the GM through the prebiotic function of non-starch polysaccharides may be a viable strategy against obesity. In this paper, the effects of non-starch polysaccharides on host health, together with their prebiotic function influencing the GM to control obesity via the gut-target organ axis, are reviewed. Potential perspectives of non-starch polysaccharides exhibiting anti-obesity effects via the gut-target organ axis are proposed for future research.

Graphical abstract

Unlocking the therapeutic potential of gut microbiota for preventing and treating aging-related neurological disorders

Billions of microorganisms inhabit the human gut and maintain overall health. Recent research has revealed the intricate interaction between the brain and gut microbiota through the microbiota-gut-brain axis (MGBA) and its effect on neurodegenerative disorders (NDDs). Alterations in the gut microbiota, known as gut dysbiosis, are linked to the development and progression of several NDDs. Studies suggest that the gut microbiota may be a viable target for improving cognitive health and reducing hallmarks of brain aging. Numerous pathways including hypothalamic-pituitary-adrenal axis stimulation, neurotransmitter release disruption, system-wide inflammation, and increased intestinal and blood-brain barrier permeability connect gut dysbiosis to neurological conditions. Metabolites produced by the gut microbiota influence neural processes that affect brain function. Clinical interventions depend on the capacity to understand the equilibrium between beneficial and detrimental gut microbiota, as it affects both neurodegeneration and neuroprotection. The importance of the gut microbiota and its metabolites during brain aging and the development of neurological disorders is summarized in this review. Moreover, we explored the possible therapeutic effects of the gut microbiota on age-related NDDs. Highlighting various pathways that connect the gut and the brain, this review identifies several important domains where gut microbiota-based interventions could offer possible solutions for age-related NDDs. Furthermore, prebiotics and probiotics are discussed as effective alternatives for mitigating indirect causes of gut dysbiosis. These therapeutic interventions are poised to play a significant role in improving dysbiosis and NDDs, paving the way for further research.

Microbiome Gut-Brain-Axis: Impact on Brain Development and Mental Health

The current discovery that the gut microbiome, which contains roughly 100 trillion microbes, affects health and disease has catalyzed a boom in multidisciplinary research efforts focused on understanding this relationship. Also, it is commonly demonstrated that the gut and the CNS are closely related in a bidirectional pathway. A balanced gut microbiome is essential for regular brain activities and emotional responses. On the other hand, the CNS regulates the majority of GI physiology. Any disruption in this bidirectional pathway led to a progression of health problems in both directions, neurological and gastrointestinal diseases. In this review, we hope to shed light on the complicated connections of the microbiome-gut-brain axis and the critical roles of gut microbiome in the early development of the brain in order to get a deeper knowledge of microbiome-mediated pathological conditions and management options through rebalancing of gut microbiome.

Intestinal Lactobacillus johnsonii protects against neuroangiostrongyliasis in BALB/c mice through modulation of immune response

Neuroangiostrongyliasis is characterized by eosinophilic meningoencephalitis with a robust onset of severe neurological symptoms, by which immunological factors and peripheral metabolites have been postulated to affect the course of the disease. The gut-brain axis provides a bidirectional communication between the gut and the central nervous system, and therefore, understanding the gut microbiome may provide us with a deeper insight into the pathogenesis of angiostrongyliasis. Using 16S rRNA sequencing, we identified an increase in the abundance of different Lactobacillus species in Angiostrongylus cantonensis-infected mice, which was correlated to the disease severity. However, attempts to inoculate L. johnsonii into A. cantonensis-infected mice surprisingly revealed an improvement in neuroinflammation and prolonged survival. RNA sequencing suggested an immune-modulatory effect of L. johnsonii, which was confirmed by ELISA, showing increased levels of IL-10 and reduced levels of IL-2, IL-4, IL-5, and MCP-1 in the brain. Nevertheless, L. johnsonii-associated improvements were not associated with microbiome-related metabolites, as UHPLC-MS/MS analysis revealed no change in short-chain fatty acids, tryptophan metabolites, and bile acids. Our results suggest that while intestinal L. johnsonii appears to be linked to the progression of neuroangiostrongyliasis, these bacteria are likely attempting to modulate the dysregulated immune response to combat the disease. This is one of the first studies to investigate the gut microbiome in mice with A. cantonensis infection, which extends our knowledge from the microbiome-point-of-view of the pathogenesis of angiostrongyliasis and how the body defends against A. cantonensis. This work also extends to possible treatment approaches using L. johnsonii as probiotics.

Combined Administration of Metformin and Propionate Reduces the Degree of Oxidative/Nitrosative Damage of Hypothalamic Neurons in Rat Model of Type 2 Diabetes Mellitus

Many complications associated with type 2 diabetes mellitus (T2DM) are closely linked with the generation of reactive species or free radicals leading to oxidative/nitrosative stress. The aim of this study was to investigate the effect of combined administration of metformin with propionate on the degree of oxidative/nitrosative damage in the brain of rats with an experimental model of T2DM. Male Wistar rats were divided into control (healthy rats); rats with T2DM and no further therapy; rats with T2DM that received: metformin, propionate, propionate + metformin. Ventromedial hypothalamus samples were analyzed by transmission electron microscopy, gas-liquid chromatography, Western blotting, RT-PCR and electron paramagnetic resonance. Combined treatment resulted in normalization of the neuronal NOS levels and reduction of mRNA level of induced nitric oxide synthase (NOS) and superoxide radicals compared to untreated T2DM rats. A decrease was also observed in the level of 8-oxyguanine with normalization of fatty acids distribution. The combined treatment partially mitigated ultrastructural alterations resulting from oxidative/nitrosative damage in neurons' mitochondria in T2DM. Thus, we demonstrated a positive effect of the combined use of metformin and propionate on all indicators of oxidative/nitrosative stress in T2DM.

Investigating Polyreactivity of CD4+ T Cells to the Intestinal Microbiota

Antigen-specific recognition of microbiota by T cells enforces tolerance at homeostasis. Conversely, dysbiosis leads to imbalanced T-cell responses, triggering inflammatory and autoimmune diseases. Despite their significance, the identities of immunogenic microbial antigens remain largely enigmatic. Here, we leveraged a sensitive, unbiased, genome-wide screening platform to identify peptides from Akkermansia muciniphila (AKK) and Bacteroides thetaiotaomicron (BT) recognized by CD4+ T cells. The platform is based on screening peptide libraries using an NFAT-fluorescence reporter cell line transduced with a retrovirus encoding an MHC-TCR (MCR) hybrid molecule. We discovered several novel epitopes from AKK and BT. T-cell hybridomas reactive to AKK and BT bacteria demonstrated polyreactivity to microbiota-derived peptides in co-cultures with MCR reporter cells. Steady-state T cells recognized these epitopes in an MHC-restricted fashion. Intriguingly, most of the identified epitopes are broadly conserved within the given phylum and originate from membrane and intracellular proteins. Ex vivo stimulation of CD4+ T cells from mice vaccinated with the identified peptides revealed mono-specific IFN-γ and IL-17 responses. Our work showcases the potential of the MCR system for identifying immunogenic microbial epitopes, providing a valuable resource. Our study facilitates decoding antigen specificity in immune system-bacterial interactions, with applications in understanding microbiome and pathogenic bacterial immunity.

Vagal Sensory Gut-Brain Pathways That Control Eating-Satiety and Beyond

The vagus nerve is the body's primary sensory conduit from gut to brain, traditionally viewed as a passive relay for satiety signals. However, emerging evidence reveals a far more complex system-one that actively encodes diverse aspects of meal-related information, from mechanical stretch to nutrient content, metabolic state, and even microbial metabolites. This review challenges the view of vagal afferent neurons (VANs) as simple meal-termination sensors and highlights their specialized subpopulations, diverse sensory modalities, and downstream brain circuits, which shape feeding behavior, metabolism, and cognition. We integrate recent advances from single-cell transcriptomics, neural circuit mapping, and functional imaging to examine how VANs contribute to gut-brain communication beyond satiety, including their roles in food reward and memory formation. By synthesizing the latest research and highlighting emerging directions for the field, this review provides a comprehensive update on vagal sensory pathways and their role as integrators of meal information.

Multidimensional mechanisms of anxiety and depression in Parkinson's Disease: integrating neuroimaging, neurocircuits, and molecular pathways

Anxiety and depression are common non-motor symptoms of Parkinson's disease (PD) that significantly affect patients' quality of life. In recent years, our understanding of PD has advanced through multifaceted studies on the pathological mechanisms associated with anxiety and depression in PD. These classic psychiatric symptoms involve complex pathophysiology, with both distinct features and connections to the mechanisms underlying the aetiology of PD. Furthermore, the co-occurrence of anxiety and depression in PD blurs the boundaries between them. Therefore, a comprehensive summary of the pathogenic mechanisms associated with anxiety and depression will aid in better addressing the emergence of these classic psychiatric symptoms in PD. This article integrates neuroanatomical, neural projection, neurotransmitter, neuroinflammatory, brain-gut axis, neurotrophic, hypothalamic-pituitary-adrenal axis, and genetic perspectives to provide a comprehensive description of the core pathological alterations underlying anxiety and depression in PD, aiming to provide an up-to-date perspective and broader therapeutic prospects for PD patients suffering from anxiety or depression.

A retrospective study on blood microbiota as a marker for cognitive decline: implications for detecting Alzheimer's disease and amnestic mild cognitive impairment in Republic of Korea

Objectives

This study aimed to investigate the relationship between blood microbiota, specifically bacterial DNA, and cognitive decline in individuals with subjective cognitive decline (SCD) and amnestic mild cognitive impairment (aMCI). The objective was to identify potential microbial signatures that could serve as biomarkers for cognitive deterioration.

Methods

Forty-seven participants were recruited, including 13 with aMCI, 20 with SCD, and 14 normal cognition (NC). Blood samples were collected, and microbial DNA was analyzed using 16S rRNA sequencing on the Illumina MiSeq platform. Bioinformatics analyses-including α- and β-diversity measures and differential abundance testing (using edgeR)-were employed to assess microbial diversity and differences in bacterial composition among groups. Logistic regression models were used to evaluate the predictive impact of the microbiota on cognitive decline.

Results

Microbial diversity differed significantly between groups, with NC exhibiting the highest α-diversity. Both the aMCI and SCD groups showed reduced diversity. Taxa such as Bacteroidia, Alphaproteobacteria, and Clostridia were significantly decreased in the aMCI group compared to NC (p<0.05). In contrast, Gammaproteobacteria increased significantly in the aMCI group compared to both NC and SCD, indicating progressive microbial changes from SCD to aMCI. No significant differences were found between the NC and SCD groups.

Conclusion

Distinct bacterial taxa-particularly the increase in Gammaproteobacteria along with decreases in Bacteroidia, Alphaproteobacteria, and Clostridia-are associated with the progression of cognitive decline. These findings suggest that blood microbiota could serve as potential biomarkers for the early detection of aMCI. However, the small sample size and the lack of control for confounding factors such as diet and medication limit the findings. Larger studies are needed to validate these results and further explore the role of microbiota in neurodegeneration.

Targeting gut microbiota: a potential therapeutic approach for tumor microenvironment in glioma

Glioma, being one of the malignant tumors with the highest mortality rate globally, has an unclear pathogenesis, and the existing treatment effects still have certain limitations. The tumor microenvironment (TME) plays an important role in the occurrence, development, and recurrence of glioma. As one of the important regulatory factors of TME, the gut microbiota can regulate the progression of glioma not only by interacting with the brain through the brain-gut axis but also by influencing the tumor immune microenvironment (TIME) and inflammatory microenvironment. Recent studies have identified the gut microbiota and TME as potential therapeutic targets for glioma. This paper aims to summarize the role of the gut microbiota in TME, the association between them and glioma, and the potential of developing new intervention measures by targeting the gut microbiota. Understanding the involvement process of the gut microbiota in glioma may pave the way for the development of effective treatment methods that can regulate TME and prevent disease progression.

A Mendelian randomization study to reveal gut-disc axis: causal associations between gut microbiota with intervertebral disc diseases

PURPOSE

Emerging evidence suggests a link between gut microbiota and intervertebral disc diseases (IDDs); however, the causal relationships remain unclear. This study aimed to evaluate the causal effects of gut microbiota on the risk of cervical disc disorders (CDD), other intervertebral disc disorders (OIDD), pyogenic intervertebral disc infections, and discitis, shedding light on the potential "gut-disc axis".

METHODS

Genetic variation data for 202 gut microbiota taxa were obtained from the Dutch Microbiome Project, and disease outcome data were sourced from the FinnGen consortium. A Mendelian Randomization (MR) approach was employed to assess causal relationships, using genetic variants as instrumental variables. Sensitivity analyses, including tests for pleiotropy, heterogeneity, and reverse causation, ensured robust findings.

RESULTS

The study identified 20 gut microbial taxa with significant associations to IDDs. Notably, taxa within the Erysipelotrichaceae family showed consistent protective effects against OIDD after Bonferroni correction (P < 0.05). Associations between several species and specific diseases, such as Alistipes senegalensis with CDD and Ruminococcus lactaris with discitis, were also observed. Sensitivity analyses confirmed no evidence of confounding or reverse causation.

CONCLUSION

This study provides evidence of causal relationships between specific gut microbiota and IDDs, supporting the existence of a "gut-disc axis." The findings suggest that microbial dysbiosis may influence spinal health through systemic inflammation and immune regulation. These insights open new possibilities for microbiota-targeted interventions, such as probiotics or dietary modifications, to prevent or manage IDDs. However, further research is required to validate these therapeutic strategies.

The gut microbiota-immune-brain axis: Therapeutic implications

The microbiota-gut-brain axis has major implications for human health including gastrointestinal physiology, brain function, and behavior. The immune system represents a key pathway of communication along this axis with the microbiome implicated in neuroinflammation in health and disease. In this review, we discuss the mechanisms as to how the gut microbiota interacts with the brain, focusing on innate and adaptive immunity that are often disrupted in gut-brain axis disorders. We also consider the implications of these observations and how they can be advanced by interdisciplinary research. Leveraging an increased understanding of how these interactions regulate immunity has the potential to usher in a new era of precision neuropsychiatric clinical interventions for psychiatric, neurodevelopmental, and neurological disorders.

Health implications of established and emerging stressors: design of the prospective New Jersey Population Health Cohort (NJHealth) Study

INTRODUCTION

Some stressors, like the death of a partner, are common and rigorously studied, while others, such as those related to climate change or social media, are just emerging and in need of systematic research. The New Jersey Population Health Cohort (NJHealth) Study aims to characterise established and emerging stressors and delineate the pathways through which they influence health, especially among groups likely to experience chronic exposure to stressors including immigrants, people of colour, multigenerational families and low-income families.

METHODS AND ANALYSIS

A prospective cohort, the NJHealth Study is recruiting 8000 NJ residents aged 14 and older using probabilistic and purposive methods to include members of multigenerational families, marginalised racial/ethnic and low-income populations, and recent immigrant groups. Building on ecosocial, life course and stress process models, the NJHealth Study employs multimodal data collection to comprehensively measure stress-related factors at individual and societal levels. Interviews include self-assessments of individual and societal stressors, potential stress buffers and amplifiers, and health and well-being outcomes, including cognitive function, activity limitations and self-reported health. In addition, salivary DNA, fasting plasma, health assessments and actigraphy data are collected from selected participants; and existing electronic health records, health insurance claims, social service and employment data, and vital records are linked. NJ's socioeconomic and demographic diversity make it an exceptional setting for the study. Strong community and stakeholder engagement supports effective translation of research findings into practical policy and programme applications.

ETHICS AND DISSEMINATION

The study was approved by the WCGIRB (Study #1321099) (formerly Western IRB). Informed consent is obtained from participants for each source of participant-level data as well as linked administrative and clinical records. Findings will be reported to study participants, funding bodies, governmental and policy stakeholders, presented at scientific meetings and submitted for peer-review publication.

The Application of DNA Viruses to Biotechnology

The delivery of biomolecules to target cells has been a longstanding challenge in biotechnology. DNA viruses naturally evolved the ability to deliver genetic material to cells and modulate cellular processes. As such, they inherently possess requisite characteristics that have led to their extensive study, engineering, and development as biotechnological tools. Here, we overview the application of DNA viruses to biotechnology, with specific implications in basic research, health, biomanufacturing, and agriculture. For each application, we review how an increasing understanding of virology and technological methods to genetically manipulate DNA viruses has enabled advances in these fields. Additionally, we highlight the remaining challenges to unlocking the full biotechnological potential of DNA viral technologies. Finally, we discuss the importance of balancing continued technological progress with ethical and biosafety considerations.

Stress and the gut microbiota-brain axis

The gut microbiota-brain axis is a complex system that links the bacteria in our gut with our brain, it plays a part in what way we respond to stress. This chapter explores how stress affects the types of bacteria in the gut and shows the two-way connection between them. Stress can change the bacteria in our gut, which can cause various problems related to stress, like depression, anxiety, and irritable bowel syndrome (IBS). Figuring out how these interactions may help us develop new treatments that focus on the connection between gut bacteria and the brain. This chapter looks at how gut bacteria could help identify stress-related problems. It also discusses the difficulties and possibilities of using this research in medical practice. In the end, the chapter talks about what comes next in this quickly changing area. It highlights how important it is to include research about the gut-brain connection in overall public health plans.

Multi-omics approaches reveal the therapeutic mechanism of Naoxintong capsule against ischemic stroke

ETHNOPHARMACOLOGICAL RELEVANCE

Ischemic stroke (IS) is a leading cause of long-term disability and mortality worldwide. The Chinese Pharmacopeia 2020 lists Naoxintong Capsule (NXT), a traditional Chinese medicine prescription, as having demonstrated substantial therapeutic efficacy for IS.

AIM OF THE STUDY

Our study aimed to evaluate the mechanism by which NXT treats IS by integrating the microbiome, transcriptome, and metabolomics.

MATERIALS AND METHODS

In a middle cerebral artery occlusion (MCAO) mouse model, the infarction rate, neurological scores, lipopolysaccharide (LPS) levels, inflammatory factor levels (IL-1β, IL-17A, and IL-6), and intestinal permeability proteins (ZO-1, MUC2, and MUC4) were measured to confirm the effect of NXT on the brain and colon. 16S rRNA sequencing, transcriptomics analysis, and targeted amino acid (AA) metabolism were employed to evaluate the mechanism by which NXT treats IS. Furthermore, the neuroprotective effects of specific AAs, identified through targeted AA metabolism, were assessed in PC12 cells following oxygen-glucose deprivation (OGD) injury. In addition, the TLR4/NF-κB pathway was evaluated by Western blot (WB).

RESULTS

NXT administration substantially alleviated brain damage and colon injury by decreasing the infarction rate, neurological scores, LPS levels, and inflammatory factors, and increasing the expression of intestinal permeability protein. Transcriptomic analysis revealed that NXT regulated "inflammatory response," "Toll-like receptor signaling pathway,", and "NF-κB signaling pathway." Furthermore, WB confirmed that NXT inhibited the brain TLR4/NF-κB pathway. 16S rRNA sequencing indicated that NXT adjusted the intestinal microbiota composition and decreased the abundance of pathogenic bacteria, including Parasutterella_massiliensis and Ihubacter_excrementihominis. Targeted AA metabolism analysis demonstrated that NXT regulated the serum levels of serine, lysine, and proline in MCAO mice. Furthermore, serine, lysine, and proline inhibited the TLR4/NF-κB pathway to protect against OGD injury in PC12 cells.

CONCLUSION

Our study indicates that NXT reduces the abundance of Parasutterella_massiliensis and Ihubacter_excrementihominis, while increasing the levels of serine, lysine, and proline. These changes are significantly associated with neuroinflammation. Furthermore, NXT alleviates IS-induced neuroinflammation by inhibiting the TLR4/NF-κB pathway. Importantly, our study provides novel insights into the mechanisms underlying NXT's therapeutic effects on IS.

The role of the intestinal microbiome in cognitive decline in patients with kidney disease

Cognitive decline is frequently seen in patients with chronic kidney disease (CKD). The causes of cognitive decline in these patients are likely to be multifactorial, including vascular disease, uraemic toxins, blood-brain barrier leakage, and metabolic and endocrine changes. Gut dysbiosis is common in patients with CKD and contributes to the increase in uraemic toxins. However, the gut microbiome modulates local and systemic levels of several metabolites such as short-chain fatty acids or derivatives of tryptophan metabolism, neurotransmitters, endocannabinoid-like mediators, bile acids, hormones such as glucagon-like peptide 1 (GLP1) or cholecystokinin (CCK). These factors can affect gut function, immunity, autonomic nervous system activity and various aspects of brain function. Key areas include blood-brain barrier integrity, nerve myelination and survival/proliferation, appetite, metabolism and thermoregulation, mood, anxiety and depression, stress and local inflammation. Alterations in the composition of the gut microbiota and the production of biologically active metabolites in patients with CKD are well documented and are favoured by low-fiber diets, elevated urea levels, sedentary lifestyles, slow stool transit times and polypharmacy. In turn, dysbiosis can modulate brain function and cognitive processes, as discussed in this review. Thus, the gut microbiome may contribute to alterations in cognition in patients with CKD and may be a target for therapeutic interventions using diet, prebiotics and probiotics.

Pathological and Inflammatory Consequences of Aging

Aging is a complex, progressive, and irreversible biological process that entails numerous structural and functional changes in the organism. These changes affect all bodily systems, reducing their ability to respond and adapt to the environment. Chronic inflammation is one of the key factors driving the development of age-related diseases, ultimately causing a substantial decline in the functional abilities of older individuals. This persistent inflammatory state (commonly known as "inflammaging") is characterized by elevated levels of pro-inflammatory cytokines, an increase in oxidative stress, and a perturbation of immune homeostasis. Several factors, including cellular senescence, contribute to this inflammatory milieu, thereby amplifying conditions such as cardiovascular disease, neurodegeneration, and metabolic disorders. Exploring the mechanisms of chronic inflammation in aging is essential for developing targeted interventions aimed at promoting healthy aging. This review explains the strong connection between aging and chronic inflammation, highlighting potential therapeutic approaches like pharmacological treatments, dietary strategies, and lifestyle changes.

Intervention and research progress of gut microbiota-immune-nervous system in autism spectrum disorders among students

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder characterized by difficulties in social interaction and communication, repetitive and stereotyped behaviors, restricted interests, and sensory abnormalities. Its etiology is influenced by both genetic and environmental factors, with no definitive cause identified and no specific pharmacological treatments available, posing a significant burden on patients' families and society. In recent years, research has discovered that gut microbiota dysbiosis plays a crucial role in the pathogenesis of ASD. The gut microbiota can influence brain function and behavior through the gut-brain axis via the nervous system, immune system, and metabolic pathways. On the one hand, specific gut microbes such as Clostridium and Prevotella species are found to be abnormal in ASD patients, and their metabolic products, like short-chain fatty acids, serotonin, and GABA, are also involved in the pathological process of ASD. On the other hand, ASD patients exhibit immune system dysfunction, with gut immune cells and related cytokines affecting neural activities in the brain. Currently, intervention methods targeting the gut microbiota, such as probiotics, prebiotics, and fecal microbiota transplantation, have shown some potential in improving ASD symptoms. However, more studies are needed to explore their long-term effects and optimal treatment protocols. This paper reviews the mechanisms and interrelationships among gut microbiota, immune system, and nervous system in ASD and discusses the challenges and future directions of existing research, aiming to provide new insights for the prevention and treatment of ASD.

Pyroptosis; igniting neuropsychiatric disorders from mild depression to aging-related neurodegeneration

Neuropsychiatric disorders significantly impact global health and socioeconomic well-being, highlighting the urgent need for effective treatments. Chronic inflammation, often driven by the innate immune system, is a key feature of many neuropsychiatric conditions. NOD-like receptors (NLRs), which are intracellular sensors, detect danger signals and trigger inflammation. Among these, NLR protein (NLRP) inflammasomes play a crucial role by releasing pro-inflammatory cytokines and inducing a particular cell death process known as pyroptosis. Pyroptosis is defined as a proinflammatory form of programmed cell death executed by cysteine-aspartic proteases, also known as caspases. Currently, the role of pyroptotic flux has emerged as a critical factor in innate immunity and the pathogenesis of multiple diseases. Emerging evidence suggests that the induction of pyroptosis, primarily due to NLRP inflammasome activation, is involved in the pathophysiology of various neuropsychiatric disorders, including depression, stress-related issues, schizophrenia, autism spectrum disorders, and neurodegenerative diseases. Within this framework, the current review explores the complex relationship between pyroptosis and neuropsychiatric diseases, aiming to identify potential therapeutic targets for these challenging conditions.

Impact of Peripheral Inflammation on Blood-Brain Barrier Dysfunction and Its Role in Neurodegenerative Diseases

The blood-brain barrier (BBB) is essential for maintaining brain homeostasis by regulating molecular exchange between the systemic circulation and the central nervous system. However, its dysfunction, often driven by peripheral inflammatory processes, has been increasingly linked to the development and progression of neurodegenerative diseases such as Alzheimer's and Parkinson's. Emerging evidence suggests that the gut-brain axis plays a key role in BBB integrity, with intestinal dysbiosis and chronic inflammation contributing to barrier disruption through immune and metabolic pathways. Furthermore, the selective vulnerability of specific brain regions to BBB dysfunction appears to be influenced by regional differences in vascularization, metabolic activity, and permeability, making certain areas more susceptible to neurodegenerative processes. This review explored the molecular mechanisms linking peripheral inflammation, gut microbiota, and BBB dysfunction, emphasizing their role in neurodegeneration. A comprehensive literature review was conducted using Web of Science, PubMed, Scopus, Wiley, ScienceDirect, and Medline, covering publications from 2015 to 2025. The findings highlight a complex interplay between gut microbiota-derived metabolites, immune signaling, and BBB permeability, underscoring the need for targeted interventions such as microbiome modulation, anti-inflammatory therapies, and advanced drug delivery systems. The heterogeneity of the BBB across different brain regions necessitates the development of region-specific therapeutic strategies. Despite advancements, critical knowledge gaps persist regarding the precise mechanisms underlying BBB dysfunction. Future research should leverage cutting-edge methodologies such as single-cell transcriptomics and organ-on-chip models to translate preclinical findings into effective clinical applications. Addressing these challenges will be crucial for developing personalized therapeutic approaches to mitigate the impact of BBB dysfunction in neurodegenerative diseases.

Lactobacillus johnsonii HL79 modulates the microbiota-gut-brain axis to protect cognitive function in mice chronically exposed to high altitude

Introduction

High-altitude environments have significant effects on brain function, particularly a decline in cognitive function, due to insufficient oxygen supply. The microbiome-gut-brain axis (MGBA) plays an important role in regulating cognitive function, but its specific mechanism of action in high-altitude environments is unclear. Therefore, the aim of this study was to investigate whether the probiotic Lactobacillus johnsonii HL79 could alleviate high altitude-induced cognitive dysfunction in mice by modulating the gut microbiota.

Methods and results

Sixty C57BL/6 mice aged 8 weeks were randomly divided into four groups: control, high altitude exposure (HA), HL79-treated (P), and high altitude exposure plus HL79-treated (HAP). the HA and HAP groups were exposed to a low-pressure oxygen chamber at a simulated altitude of 3,500-4,000 m for 20 weeks, while the Control and P groups were maintained at the normal barometric pressure level. Probiotic HL79 was given daily by gavage in the P and HAP groups, while saline gavage was given daily in the other two groups. The cognitive functions of the mice were assessed by new object recognition test and elevated plus maze test. The results showed that HL79 treatment significantly improved the working memory abilities of high altitude exposed mice. In addition, HL79 treatment improved antioxidant capacity, decreased malondialdehyde (MDA) content, and increased superoxide dismutase (SOD) and catalase (CAT) activities in serum and whole brain tissue. Gut microbiota analysis showed that HL79 was able to modulate the structure of gut microbiota and increase the relative abundance of beneficial flora in high altitude environment.

Conclusion

Lactobacillus johnsonii HL79 significantly ameliorated cognitive dysfunction in high altitude-exposed mice by modulating the gut microbiota and antioxidant capacity, further confirming the important role of MGBA in high altitude environment.

Gut Metagenome Reveals the Microbiome Signatures in Tibetan and Black Pigs

The harsh conditions of the Qinghai-Tibet Plateau pose significant physiological challenges to local fauna, often resulting in gastrointestinal disorders. However, Tibetan pigs have exhibited remarkable adaptability to the high-altitude stress of the Tibetan Plateau, a phenomenon that remains not fully understood in terms of their gastrointestinal microbiota. This study collected 57 gastrointestinal tract samples from Tibetan pigs (n = 6) and plain black pigs (n = 6) with comparable genetic backgrounds. Samples from the stomach, jejunum, cecum, colon, and rectum, underwent comprehensive metagenomic analysis to elucidate the gut microbiota-related adaptive mechanisms in Tibetan pigs to the extreme high-altitude environment. A predominance of Pseudomonadota was observed within gut microbiome of Tibetan pigs. Significant differences in the microbial composition were also identified across the tested gastrointestinal segments, with 18 genera and 141 species exhibiting differential abundance. Genera such as Bifidobacterium, Megasphaera, Fusobacterium, and Mitsuokella were significantly more abundant in Tibetan pigs than in their lowland counterparts, suggesting specialized adaptations. Network analysis found greater complexity and modularity in the microbiota of Tibetan pigs compared to black pigs, indicating enhanced ecological stability and adaptability. Functional analysis revealed that the Tibetan pig microbiota was particularly enriched with bacterial species involved in metabolic pathways for propionate and butyrate, key short-chain fatty acids that support energy provision under low-oxygen conditions. The enzymatic profiles of Tibetan pigs, characterized by elevated levels of 4-hydroxybutyrate dehydrogenase and glutaconyl-CoA decarboxylase, highlighted a robust fatty acid metabolism and enhanced tricarboxylic acid cycle activity. In contrast, the gut microbiome of plain black pigs showed a reliance on the succinate pathway, with a reduced butyrate metabolism and lower metabolic flexibility. Taken together, these results demonstrate the crucial role of the gastrointestinal microbiota in the adaptation of Tibetan pigs to high-altitude environments by optimizing carbohydrate metabolism and short-chain fatty acid production for efficient energy utilization. This study not only highlights the metabolic benefits conferred by the gut microbiota of Tibetan pigs in extreme environments, but also advances our understanding of the adaptive gastrointestinal mechanisms in plateau-dwelling animals. These insights lay the foundation for exploring metabolic interventions to support health and performance in high-altitude conditions.

Advancements in the investigation of gut microbiota-based strategies for stroke prevention and treatment

Stroke represents a predominant cause of mortality and disability on a global scale, impacting millions annually and exerting a considerable strain on healthcare systems. The incidence of stroke exhibits regional variability, with ischemic stroke accounting for the majority of occurrences. Post-stroke complications, such as cognitive impairment, motor dysfunction, and recurrent stroke, profoundly affect patients' quality of life. Recent advancements have elucidated the microbiota-gut-brain axis (MGBA), underscoring the complex interplay between gut health and brain function. Dysbiosis, characterized by an imbalance in gut microbiota, is significantly linked to an elevated risk of stroke and unfavorable outcomes. The MGBA plays a crucial role in modulating immune function, neurotransmitter levels, and metabolic byproducts, which may intensify neuroinflammation and impair cerebral health. This review elucidates the role of MGBA in stroke pathophysiology and explores potential gut-targeted therapeutic strategies to reduce stroke risk and promote recovery, including probiotics, prebiotics, pharmacological interventions, and dietary modifications. However, the current prevention and treatment strategies based on intestinal flora still face many problems, such as the large difference of individual intestinal flora, the stability of efficacy, and the long-term safety need to be considered. Further research needs to be strengthened to promote its better application in clinical practice.

Gut-brain axis and neuroplasticity in health and disease: a systematic review

The gut microbiota emerged as a potential modulator of brain connectivity in health and disease. This systematic review details current evidence on the gut-brain axis and its influence on brain connectivity. The initial set of studies included 532 papers, updated to January 2024. Studies were selected based on employed techniques. We excluded reviews, studies without connectivity focus, studies on non-human subjects. Forty-nine papers were selected. Employed techniques in healthy subjects included 15 functional magnetic resonance imaging studies (fMRI), 5 diffusion tensor imaging, (DTI) 1 electroencephalography (EEG), 6 structural magnetic resonance imaging, 2 magnetoencephalography, 1 spectroscopy, 2 arterial spin labeling (ASL); in patients 17 fMRI, 6 DTI, 2 EEG, 9 structural MRI, 1 transcranial magnetic stimulation, 1 spectroscopy, 2 R2*MRI. In healthy subjects, the gut microbiota was associated with connectivity of areas implied in cognition, memory, attention and emotions. Among the tested areas, amygdala and temporal cortex showed functional and structural differences based on bacteria abundance, as well as frontal and somatosensory cortices, especially in patients with inflammatory bowel syndrome. Several studies confirmed the connection between microbiota and brain functions in healthy subjects and patients affected by gastrointestinal to renal and psychiatric diseases.

Gut microbiota in multiple sclerosis and animal models

Multiple sclerosis (MS) is a chronic central nervous system (CNS) neurodegenerative and neuroinflammatory disease marked by a host immune reaction that targets and destroys the neuronal myelin sheath. MS and correlating animal disease models show comorbidities, including intestinal barrier disruption and alterations of the commensal microbiome. It is accepted that diet plays a crucial role in shaping the microbiota composition and overall gastrointestinal (GI) tract health, suggesting an interplay between nutrition and neuroinflammation via the gut-brain axis. Unfortunately, poor host health and diet lead to microbiota modifications that could lead to significant responses in the host, including inflammation and neurobehavioral changes. Beneficial microbial metabolites are essential for host homeostasis and inflammation control. This review will highlight the importance of the gut microbiota in the context of host inflammatory responses in MS and MS animal models. Additionally, microbial community restoration and how it affects MS and GI barrier integrity will be discussed.

Impact of Native Probiotics on Autophagy and Oxidative Stress in Nickel-Exposed Mice: Insights Into the Gut-Brain Axis

BACKGROUND

The gut-brain axis plays a crucial role in mitigating the adverse effects of environmental agents such as nickel exposure. Nickel, recognized as a heavy metal, poses significant concerns for public health because of its impact on neurological disorders and oxidative stress; consequently, it is prioritized for evaluations of its effects on biological pathways. This study investigates the potential of native probiotic strains to modulate inflammatory and autophagy signaling pathways, which are vital for combating oxidative stress.

METHODS

Twenty male NMRI mice were divided into 4 groups randomly and were gavaged with NiCl2, followed by administration of a probiotic cocktail that consisted of 4 native probiotic Lactobacillus spp. and Bifidobacterium spp. Brain tissues from these treated mice were collected to analyze the expression of autophagy-related genes involved in phagophore, autophagosome, and autolysosome formation using quantitative real-time polymerase chain reaction (qPCR).

RESULTS

Our findings demonstrated that treatment with this cocktail of native probiotic Lactobacillus spp. and Bifidobacterium spp. significantly increased the expression of autophagy genes compared to the control group exposed to NiCl2 alone. Specifically, there was a notable upregulation in genes associated with autophagic processes, indicating that these probiotic strains effectively activated autophagy pathways in response to nickel-induced oxidative stress.

CONCLUSION

The beneficial effects of our native probiotic strains were confirmed through enhanced expression of autophagy genes and reduced neuroinflammation, suggesting their potential as therapeutic agents in mitigating the adverse impacts of nickel exposure on brain health via modulation of the gut-brain axis.

The roles of functional bacterial amyloids in neurological physiology and pathophysiology: Pros and cons for neurodegeneration

Bacterial biofilms, which are complex communities of microorganisms encapsulated in a self-produced extracellular matrix, play critical roles in various diseases. Recent research has underscored the dualistic nature of amyloids, structural proteins within these biofilms, in human health, particularly highlighting the significant role in neurodegenerative disorders such as Alzheimer's (AD) and Parkinson's disease (PD). These amyloids modulate the immune response by inducing the production of interleukin-10 (IL-10), which plays a role in anti-inflammatory processes. Additionally, they inhibit the aggregation of human amyloids and enhance the integrity of the intestinal barrier. Detrimentally, they exacerbate neuroinflammation by elevating inflammatory cytokines and promoting the aggregation of human amyloid proteins-amyloid-β (Aβ) in AD and α-synuclein (αS) in PD-through a process known as cross-seeding. Moreover, bacterial amyloids have also been shown to stimulate the production of anti-curli/DNA antibodies, which are implicated in the pathogenesis of autoimmune diseases. Given their dualistic nature, bacterial amyloids may, under specific conditions, function as beneficial proteins for human health. This understanding holds promise for the development of targeted therapeutic strategies aimed at modulating bacterial amyloids in the context of neurodegenerative diseases, such as AD and PD.

Structural characteristics of a heteropolysaccharide from Ganoderma lucidum and its protective effect against Alzheimer's disease via modulating the microbiota-gut-metabolomics

Ganoderma lucidum is a traditional Chinese medicine used to treat Alzheimer's disease (AD), whose main active ingredient is polysaccharides. A heteropolysaccharide named GLPZ-1 was isolated from Ganoderma lucidum. GLPZ-1 (6.608 kDa) predominantly consisted of Glc and minor Gal. The results of GC-MS and NMR analyses indicated that the backbone of GLPZ-1 was mainly composed of 1,4-α-D-Glcp, 1,4,6-α-Glcp and a minor amount of 1,3,4-β-D-Glcp, which was substituted with complex side chains at C-6 of 1,4,6-α-D-Glcp and at C-3 of 1,3,4-β-D-Glcp. GLPZ-1 demonstrated a protective effect on AD rats by improving behavioral abnormalities, alleviating pathological damage and ameliorating levels of IL-6, IL-1β, TNF-α and Th17, which were associated with GLPZ-1 modulating the microbiota-gut-metabolomics of AD rats. GLPZ-1 regulated the gut microbiota in AD rats by increasing the abundance of Bacteroides, unclassified_Lachnospiraceae, Lactobacillus, Pediococcus, Oscillibacter, Lachnoclostridium and Bifidobacterium, while simultaneously reducing the abundance of Pseudomonas and Desulfovibrio. GLPZ-1 could regulate fecal metabolites in AD rats tending towards the normal levels. These regulated fecal metabolites belonged to fatty acid metabolism, cholesterol and bile acid metabolism, neurotransmitters and aromatic amino acid metabolism. These findings provide a preliminary research basis for the exploitation of GLPZ-1 as an effective drug to prevent and delay AD.

Assessing the impact of moxibustion on colonic mucosal integrity and gut microbiota in a rat model of cerebral ischemic stroke: insights from the "brain-gut axis" theory

Objective

The aim of this study is to assess the impact of moxibustion on the colonic mucosal barrier and gut microbiota in a rat model of cerebral ischemic stroke (CIS).

Method

The CIS rat model was established using the modified Zea Longa suture method. Successfully modeled rats were randomly allocated into a model group and a moxibustion group, with a sham surgery group serving as the control. The moxibustion group received suspended moxibustion at Dazhui (GV 14), Baihui (GV 20), Fengfu (GV 16), and bilateral Tianshu (ST 25) and Shangjuxu (ST 37) acupoints. Neurological function was assessed using the Longa score, and brain infarct size was assessed through 2,3,5-triphenyl tetrazolium chloride staining. Gut microbiota composition was analyzed using 16S rDNA amplification sequencing. Intestinal mucosal permeability was evaluated using the FITC-Dextran tracer method. The serum ET-1 levels and the expression of Occludin and ZO-1 proteins in colonic tissues were also measured.

Result

The model group exhibited significantly higher Longa scores, larger brain infarct size, and higher serum FITC-Dextran levels and ET-1 levels when compared with the sham surgery group (p < 0.01). The model group demonstrated decreased expression of Occludin and ZO-1 in colonic tissues (p < 0.01) and changes in gut microbiota structure. When compared to the model group, the moxibustion group demonstrated significantly lower Longa scores, smaller brain infarct size, and lower serum FITC-Dextran levels and ET-1 levels (p < 0.05). Furthermore, the moxibustion group demonstrated decreased inflammatory cell infiltration in colonic tissues, increased expression of Occludin and ZO-1 proteins in colonic tissues (p < 0.05), enhanced gut microbiota structure, and a decreased Simpson index (p < 0.05).

Conclusion

Moxibustion can improve the neurological dysfunction in CIS model rats. The mechanism may be associated with the improvement in gut microbiota dysbiosis, reduction in colonic mucosal permeability, and restoration of intestinal mucosal barrier damage.

Biotransformation of Ganoderma lucidum and Hericium erinaceus for ex vivo gut-brain axis modulation and mood-related outcomes in humans: CREB/BDNF signaling and microbiota-driven synergies

BACKGROUND

The human gut microbiota plays a crucial role in various aspects of health, extending beyond digestion and nutrient absorption. Ganoderma lucidum (Reishi) and Hericium erinaceus (Lion's Mane), traditional medicinal mushrooms, have garnered interest due to their potential to exert positive health effects. The aim of our study was to investigate the molecular impact of Reishi and Lion's Mane on mood regulation through the gut-brain axis.

METHODS

We utilized a dynamic simulator of the human intestinal microbial ecosystem (SHIME), followed by HPLC-ESI-QTOF-MS/MS and a series of biochemical and molecular assays, including MTT for cell viability, fluorogenic probes for redox balance (ROS and GSH), and Western blot for protein analysis.

RESULTS

Chromatographic analysis confirmed the presence of bioactive compounds in both mushrooms, including triterpenoids (ganoderic acids) and polysaccharides in G. lucidum, as well as hericenones and erinacines in H. erinaceus. We observed concentration-dependent changes in metabolic activity and redox balance due to microbiome cell-free supernatant treatment (M-CFSs). M-CFSs also influenced the Nrf2 pathway and activated heat shock proteins, which may confer neuroprotective effects. Notably, M-CFSs upregulated neurotrophic factors such as BDNF, CDNF, and MANF, crucial for neuronal function. Our study revealed alterations in intracellular signaling cascades, most notably the CREB/BDNF pathway. Moreover, the Akt/mTOR and ERK1/2 showed no significant changes, while Akt/GSK3α/β displayed only partial modifications. The overlapping effects of synaptic activity and activation of the gut-brain axis appear to contribute to mood enhancement.

CONCLUSIONS

These pilot findings suggest a potential role for G. lucidum and H. erinaceus in mood disorder regulation through multifaceted mechanisms involving the gut microbiota. The study underscores the importance of understanding the synergistic interactions between medicinal fungi, gut microbiota, and neural processes to develop novel or preventive strategies for mental health disorders.

Gut microbiota regulates optic nerve fiber myelination

Introduction

Recent evidence supports the hypothesis of an association between gut microbiota and the pathogenesis of retinal and eye diseases, suggesting the existence of a gut-eye axis. However, no data are available on the possible effect of the gut microbiota on the optic nerve fiber maturation and myelin development.

Methods

We investigated the impact of gut microbiota on the optic nerves collected from neonatal and young adult germ-free (GF), gnotobiotic (stably colonized with 12 bacteria strains, OMM12) and control (colonized with a complex gut microbiota, CGM) mice, by performing stereological and morphoquantitative analyses with transmission electron microscopy and gene expression analysis by quantitative real-time PCR.

Results

Young adult GF and OMM12 optic nerve axons are smaller and hypermyelinated compared to CGM ones, while no such differences were detected in neonatal optic nerves. The transcription factors Olig1, Olig2, and Sox10 (oligodendrocyte myelination positive regulators) are downregulated in CGM and OMM12 young adult mice compared to the respective neonates. Such developmental downregulation was not observed in GF optic nerves, suggesting that the absence of the gut microbiota prolongs the stimulation of optic nerve fiber myelination, possibly through mechanisms that are yet to be identified.

Discussion

Altogether, these data underscore the gut microbiota pivotal role in driving optic nerve myelination, contributing to our knowledge about both the gut-eye axis and the gut-brain axis, and opening new horizons for further investigations that will explore the role of the microbiota also in pathologies, injuries and regeneration associated with the optic nerve.

Effects of Chlorpyrifos on gut dysbiosis and barriers integrity in women with a focus on pregnancy and prebiotic intervention: Insights from advanced in vitro human models

Chlorpyrifos (CPF), a commonly used organophosphate pesticide, poses potential risks to human health, particularly affecting the gut microbiota (GM), intestinal barrier (IB), and blood-brain barrier (BBB). CPF-induced gut dysbiosis compromises the integrity of both the IB and the BBB, leading to increased intestinal permeability, inflammation, and bacterial translocation, all of which may impact neurological health. Although CPF's effects on the GM are documented, limited research explores how these impacts differ in women, particularly during pregnancy. To address this gap, this study investigates CPF's effects using three advanced human in vitro models: the Simulator of the Human Intestinal Microbial Ecosystem (SHIME®) to mimic the gut environment of women of child-bearing age and pregnant women, a Caco-2 model for the IB, and a BBB model to assess CPF's effects and the protective role of the prebiotic inulin. Microbiological analyses of SHIME® supernatants, including bacterial culture and quantification of short-chain fatty acids (SCFAs) and CPF metabolites, were conducted to assess gut composition and pesticide degradation. We also examined the effects of CPF-induced dysbiosis on IB and BBB permeability to FITC-Dextran, focusing on bacterial translocation after 4 h of exposure to CPF-treated SHIME® supernatants. Our results revealed significant intestinal imbalance, marked by an increase in potentially pathogenic bacteria in the GM of both non-pregnant and pregnant women exposed to CPF. This dysbiosis led to a significant shift in SCFAs ratio and increased IB permeability and bacterial translocation across the IB, but not the BBB. Notably, inulin supplementation restored GM balance and prevented bacterial translocation, highlighting its potential as a preventive measure against CPF-induced dysbiosis. This study enhances our understanding of the health risks associated with CPF exposure in women, with implications for maternal and fetal health, and underscores the importance of considering physiological states such as pregnancy in toxicological research.

Exploring the microbiota-gut-brain axis: impact on brain structure and function

The microbiota-gut-brain axis (MGBA) plays a significant role in the maintenance of brain structure and function. The MGBA serves as a conduit between the CNS and the ENS, facilitating communication between the emotional and cognitive centers of the brain via diverse pathways. In the initial stages of this review, we will examine the way how MGBA affects neurogenesis, neuronal dendritic morphology, axonal myelination, microglia structure, brain blood barrier (BBB) structure and permeability, and synaptic structure. Furthermore, we will review the potential mechanistic pathways of neuroplasticity through MGBA influence. The short-chain fatty acids (SCFAs) play a pivotal role in the MGBA, where they can modify the BBB. We will therefore discuss how SCFAs can influence microglia, neuronal, and astrocyte function, as well as their role in brain disorders such as Alzheimer's disease (AD), and Parkinson's disease (PD). Subsequently, we will examine the technical strategies employed to study MGBA interactions, including using germ-free (GF) animals, probiotics, fecal microbiota transplantation (FMT), and antibiotics-induced dysbiosis. Finally, we will examine how particular bacterial strains can affect brain structure and function. By gaining a deeper understanding of the MGBA, it may be possible to facilitate research into microbial-based pharmacological interventions and therapeutic strategies for neurological diseases.

Multiple Sclerosis: A Story of the Interaction Between Gut Microbiome and Components of the Immune System

Multiple sclerosis (MS) is defined as an inflammatory disorder that chronically affects the central nervous system of young people mostly and is distributed globally. It is associated with degeneration and demyelination of the myelin sheath around the nerves, resulting in multiple neurological disability symptoms ranging from mild to severe cases that end with paralysis sometimes. MS is one of the rising diseases globally that is unfortunately associated with reduced quality of life and adding national economic burdens. The definite MS mechanism is not clearly defined; however, all the previous researches confirm the role of the immune system as the master contributor in the pathogenesis. Innate and adaptive immune cells are activated peripherally then attracted toward the central nervous system (CNS) due to the breakdown of the blood-brain barrier. Recently, the gut-brain axis was shown to depend on gut metabolites that are produced by different microorganisms in the colon. The difference in microbiota composition between individuals is responsible for diversity in secreted metabolites that affect immune responses locally in the gut or systemically when reach blood circulation to the brain. It may enhance or suppress immune responses in the central nervous system (CNS) (repeated short forms); consequently, it may exacerbate or ameliorate MS symptoms. Recent data showed that some metabolites can be used as adjuvant therapy in MS and other inflammatory diseases. This review sheds light on the nature of MS and the possible interaction between gut microbiota and immune system regulation through the gut-brain axis, hence contributing to MS pathogenesis.

Traditional Chinese herbal formula, Fuzi-Lizhong pill, produces antidepressant-like effects in chronic restraint stress mice through systemic pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Fuzi-Lizhong pill (FLP) is a well-validated traditional Chinese medicine (TCM) formula that has long been used in China for gastrointestinal disease and adjunctive therapy for depression. In our previous study, we reported that the principal herb of FLP, Aconitum carmichaelii Debx. (Fuzi), exhibits antidepressant-like effects. However, there have been no reports on whether FLP produces antidepressant-like effects and its potential molecular mechanisms.

AIM OF THE STUDY

We aim to demonstrate the antidepressant-like effects of FLP in chronic restraint stress (CRS) mice and to explore the associated molecular mechanisms.

MATERIALS AND METHODS

The active components and probable molecular targets of FLP, as well as the targets related to depression, were identified through network pharmacology. A protein-protein interaction (PPI) network was generated using the overlapping targets, followed by the visualization as well as identification of the core targets associated with the antidepressant-like action of FLP. Subsequently, KEGG and GO enrichment analyses were conducted. UHPLC-MS/MS was employed to further detect the active compounds in FLP. Molecular docking was applied to assess the connections between the active components as well as the core targets. The efficacy of FLP in treating depression and its molecular mechanisms were examined using western blotting, ELISA, 16S rRNA sequencing, HE staining, Nissl staining, and Golgi-Cox staining in a CRS-induced mouse model.

RESULTS

Network pharmacology and UHPLC-MS/MS analyses indicated that the active compounds of FLP comprised taraxerol, songorine, neokadsuranic acid B, ginkgetin, hispaglabridin B, quercetin, benzoylmesaconine and liquiritin. KEGG pathway analysis implicated that the PI3K/Akt/mTOR as well as MAPK signaling pathways are closely related to the therapeutic effects of FLP on depression. Molecular docking analysis demonstrated that the main components of FLP bind to PI3K, AKT, mTOR, BDNF and MAPK. FLP significantly decreased immobility in mice that were elevated by CRS in the FST and the TST. FLP also significantly increased sucrose preference in mice after CRS in the SPT. FLP upregulated proteins associated with BDNF-TrkB and PI3K/Akt/mTOR signaling and downregulated proteins associated with MAPK signaling. Serum levels of CORT, IL-6, IL-1β, and TNF-α in CRS mice were significantly decreased following treatment with FLP. In addition, FLP ameliorated CRS-induced gut microbiota dysbiosis as demonstrated by 16S rRNA sequencing analysis. FLP ameliorated CRS-induced intestinal inflammation and neuronal damage. Finally, antidepressant-like effects and concomitant increases in dendritic spine density induced by FLP administration were also reduced after rapamycin treatment.

CONCLUSION

These results demonstrate that FLP has antidepressant-like effects in mice exposed to CRS that involve activation of the PI3K/Akt/mTOR signaling pathway, increase in spinogenesis, inhibition of the MAPK signaling pathway, decrease in inflammation, and amelioration of gut microbiota dysbiosis. These findings provide novel evidence for the clinical application of FLP on depression.

Advancements in the Pathogenesis, Diagnosis, and Therapeutic Implications of Intestinal Bacteria

Intestinal bacteria form one of the most complex microbial communities in the human body, playing a crucial role in maintaining host health and contributing to the development of various diseases. Here, we provide a comprehensive overview of the composition and function of intestinal bacteria, the factors affecting their homeostasis, and their association and mechanisms with a range of diseases (e.g., inflammatory bowel diseases, colorectal cancer, metabolic diseases). Additionally, their advanced potential in disease diagnosis and treatment is highlighted. Therapies, such as chemotherapy, radiotherapy, and immunotherapy, are significantly impacted by intestinal bacteria, with research indicating that bacteria can enhance chemoimmunotherapy efficiency by affecting T cell recruitment and immune cell infiltration. Fecal microbiota transplantation has emerged as a promising option for treating recurrent Clostridium difficile infections and certain metabolic and neurological disorders. Gut bacteria-related serum metabolites serve as non-invasive indicators for diagnosing CRC, while fecal immunochemical tests offer promising applications in CRC screening. Future research is needed to better understand the causal relationships between intestinal bacteria and diseases, develop more precise diagnostic tools, and evaluate the effectiveness and safety of microbiome-targeted therapies in clinical treatment. This study provides deeper insights into the role of intestinal bacteria in human health and disease, providing a scientific basis for innovative therapeutic strategies that have the potential to transform the landscape of healthcare.

Gut microbiota-derived short chain fatty acids act as mediators of the gut-liver-brain axis

The gut microbiota plays a crucial role in the communication between the gut, liver, and brain through the production of short chain fatty acids (SCFAs). SCFAs serve as key mediators in the Gut-Liver-Brain Axis, influencing various physiological processes and contributing to overall health. SCFAs are produced by bacterial fermentation of dietary fiber in the gut, and they exert systemic effects by signaling through various pathways. In the Gut-Liver axis, SCFAs regulate liver metabolism through peroxisome proliferator-activated receptor-γ (PPAR-γ), AMP-activated protein kinase (AMPK) and other pathways, promotes fat oxidation, modulate inflammation through mTOR pathway, and impact metabolic health. In the Gut-Brain axis, SCFAs influence brain function, behavior, and may have implications for neurological disorders, in which G-protein coupled receptors (GPCRs) play an essential role, along with other pathways such as hypothalamic-pituitary-adrenal (HPA) pathway. Understanding the mechanisms by which SCFAs mediate communication between the gut, liver, and brain is crucial for elucidating the complex interplay of the Gut-Liver-Brain Axis. This review aims to provide insight into the role of gut microbiota-derived SCFAs as mediators of the Gut-Liver-Brain Axis and their potential therapeutic implications. Further research in this area will be instrumental in developing novel strategies to target the Gut-Liver-Brain Axis for the prevention and treatment of various health conditions.

Gut-Brain Axis and Brain Microbiome Interactions from a Medical Perspective

Background: The gut microbiome directly impacts brain health and activity, meaning the two are closely associated. This relationship suggests a link between microbial imbalances and diseases such as Alzheimer's, although multiple other contributing factors, such as genetics, also play a part. Additionally, recent studies discovered that cerebrospinal fluid has some microbial deoxyribonucleic acid (DNA), which can be interpreted to mean a microbiome exists in the brain too. The vagus nerve and the central nervous and immune systems are responsible for the connection between the brain and gut microbiome. Aims and Objectives: The main aim of this systematic review is to analyze existing research on the gut-brain axis and the brain microbiome to fill the current knowledge gap. Materials and Methods: A search was conducted on the PubMed database based on a set of predefined MeSH terms. Results: After the search, 2716 articles meeting the MeSH parameters were found in PubMed. This list was then downloaded and analyzed according to the inclusion/exclusion criteria, and 63 relevant papers were selected. Discussion: Bacteria in the gut microbiome produce some substances that are considered neuroactive. These compounds can directly or indirectly affect brain function through the gut-brain axis. However, various knowledge gaps on the mechanisms involved in this connection need to be addressed first.

Emerging Medications for Treatment-Resistant Depression: A Review with Perspective on Mechanisms and Challenges

Background/Objectives: Non-response to initial treatment options for major depressive disorder (MDD) is a common clinical challenge with profound deleterious impacts for affected patients. Few treatments have received regulatory approval for treatment-resistant depression (TRD). Methods: A systematic search of United States and European Union clinical trials registries was conducted to identify Phase II, III, or IV clinical trials, with a last update posted on or after 1 January 2020, that were evaluating medications for TRD. For both the US and EU registries, the condition term "treatment resistant depression" and associated lower-level terms (per registry search protocol) were used. For the US registry, a secondary search using the condition term "depressive disorders" and the modifying term "inadequate" was also performed to capture registrations not tagged as TRD. Two additional searches were also conducted in the US registry for the terms "suicide" and "anhedonia" as transdiagnostic targets of investigational medications. Trials were categorized based on the primary mechanism of action of the trial's investigational medication. Results: Fifty clinical trials for TRD, 20 for anhedonia, and 25 for suicide were identified. Glutamate system modulation was the mechanism currently with the most compounds in development, including antagonists and allosteric modulators of NMDA receptors, AMPA receptors, metabotropic type 2/3 glutamate receptors, and intracellular effector molecules downstream of glutamate signaling. Psychedelics have seen the greatest surge among mechanistic targets in the past 5 years, however, with psilocybin in particular garnering significant attention. Other mechanisms included GABA modulators, monoamine modulators, anti-inflammatory/immune-modulating agents, and an orexin type 2 receptor antagonist. Conclusions: These investigations offer substantial promise for more efficacious and potentially personalized medication approaches for TRD. Challenges for detecting efficacy in TRD include the heterogeneity within the TRD population stemming from the presumed variety of biological dysfunctions underlying the disorder, comorbid disorders, chronic psychosocial stressors, and enduring effects of prior serotonergic antidepressant medication treatments.

Mannuronate Oligosaccharides Ameliorate Experimental Colitis and Secondary Neurological Dysfunction by Manipulating the Gut-Brain Axis

Microbiota dysfunction induces intestinal disorders and neurological diseases. Mannuronate oligosaccharides (MAOS), a kind of alginate oligosaccharide (AOS), specifically exert efficacy in shaping gut microbiota and relieving cognitive impairment. However, the key regulatory factors involved, such as the specific strains and metabolites as well as their regulatory mechanisms, remain unclear at present. This research investigates how MAOS specifically impact the gut-brain axis in vivo and in vitro. The results showed that pretreatment with MAOS significantly ameliorated dextran sodium sulfate (DSS)-induced colitis and secondary nerve injury. This preventive mechanism operates through the regulation of serum DOPC abundance and the gut-brain axis, achieved by inhibiting the TLR4/MyD88/NF-κB pathway. These findings underscore the crucial role of dietary MAOS in the prevention of colitis and neurological disorders, providing a rationale for the application of MAOS in disease prevention and functional food ingredients.

Photobiomodulation of gut microbiota with low-level laser therapy: a light for treating neuroinflammation

The gut microbiota is known to interact with various organs in the body, including the central nervous system, through the gut-brain axis. Intestinal dysbiosis can lead to increased peripheral inflammation and, consequently, affect the brain, resulting in neuroinflammation. Photobiomodulation (PBM) has demonstrated positive regulatory effects on the imbalance of certain body functions, including pain, inflammation, immunity, wound healing, and gut microbiota dysbiosis. Therefore, PBM at the intestinal level could help improve intestinal dysbiosis and reestablish cerebral homeostasis. In this context, this study aimed to conduct a narrative review of the literature on the effects of PBM at the intestinal level on intestinal dysbiosis and neuroinflammation. Overall, the findings highlight that PBM modulates the gut microbiota, suggesting it could serve as a therapy for neurological conditions affecting the gut-brain axis. Future research should focus on further elucidating the molecular mechanisms underlying this therapy.

Probiotics in autism spectrum disorders: a systematic review of clinical studies and future directions

CONTEXT

It is hypothesized that gut dysbiosis, a typical feature of patients with autism spectrum disorder (ASD), could be involved in the origin of this neurodevelopmental disorder. Therefore, the use of probiotics to restore gastrointestinal (GI) equilibrium might be a promising therapeutic strategy due to its capacity to balance the gut-brain axis and behavioral responses.

OBJECTIVE

To summarize current knowledge on the use of probiotics to treat core clinical ASD symptoms and concomitant GI signs, compare the design of published studies with those of ongoing trials, assess the near future of this field, and provide recommendations for improving novel studies.

DATA SOURCES

The literature search was conducted in February 2020 and updated in March 2021, using a broad range of bibliographic and clinical trial-specific databases.

DATA EXTRACTION

Data were extracted using a standardized form, and articles reporting on 28 clinical studies (already published or still ongoing) were included. The risk of bias in clinical studies was evaluated using the Cochrane Collaboration Risk of Bias Assessment tool for randomized trials and the Risk of Bias in Nonrandomized Studies-Interventions tool for nonrandomized trials.

RESULTS

The results suggest that probiotics improve ASD-like social deficits, GI symptoms, and gut microbiota profile. However, inconsistencies among studies and their methodological limitations make it difficult to draw any conclusions regarding the efficacy of probiotics in ASD. This review provides specific suggestions for future research to improve the quality of the studies.

CONCLUSIONS

Although ongoing studies have improved designs, the available knowledge does not permit solid conclusions to be made regarding the efficacy of probiotics in ameliorating the symptoms (psychiatric and/or GI) associated with ASD. Thus, more high-quality research and new approaches are needed to design effective probiotic strategies for ASD.

Vagus nerve stimulation and gut microbiota interactions: A novel therapeutic avenue for neuropsychiatric disorders

The rising prevalence of treatment-resistant neuropsychiatric disorders underscores the need for innovative and effective treatment strategies. The gut microbiota (GM) plays a pivotal role in the progression of these diseases, influencing the brain and mental health through the gut-brain axis (GBA). The vagus nerve plays a significant role in the GBA, making it a key area of focus for potential novel therapeutic interventions. Vagus nerve stimulation (VNS) was introduced and approved as a treatment for refractory forms of some neuropsychological disorders, such as depression and epilepsy. Considering its impact on several brain regions that play a vital part in mood, motivation, affection, and cognitive function, the VNS has shown significant therapeutic potential for treating a variety of neuropsychiatric disorders. Using VNS to target the bidirectional communication pathways linking the GM and the VN could present an exciting and novel approach to treating neuropsychological disorders. Imbalances in the GM, such as dysbiosis, can impair the communication pathways between the gut and the brain, contributing to the development of neuropsychological disorders. VNS shows potential for modulating these interconnected systems, helping to restore balance. Interestingly, the composition of the GM may also influence the effectiveness of VNS, as it has the potential to modify the brain's response to this therapeutic approach. This study provides a comprehensive analysis of a relatively unexplored but noteworthy interaction between VNS and GM in the treatment of neuropsychiatric disorders. In addition, we discussed the mechanisms, therapeutic potential, and clinical implications of VNS on the GBA across neuropsychiatric disorders.

Gut Microbiota-Induced Modulation of the Central Nervous System Function in Parkinson's Disease Through the Gut-Brain Axis and Short-Chain Fatty Acids

Recent insights into Parkinson's disease (PD), a progressive neurodegenerative disorder, suggest a significant influence of the gut microbiome on its pathogenesis and progression through the gut-brain axis. This study integrates 16S rRNA sequencing, high-throughput transcriptomic sequencing, and animal model experiments to explore the molecular mechanisms underpinning the role of gut-brain axis in PD, with a focus on short-chain fatty acids (SCFAs) mediated by the SCFA receptors FFAR2 and FFAR3. Our findings highlighted prominent differences in the gut microbiota composition between PD patients and healthy individuals, particularly in taxa such as Escherichia_Shigella and Bacteroidetes, which potentially impact SCFA levels through secondary metabolite biosynthesis. Notably, fecal microbiota transplantation (FMT) from healthy to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse models significantly improved motor function, enhanced dopamine and serotonin levels in the striatum, and increased the number of dopaminergic neurons in the substantia nigra while reducing glial cell activation. This therapeutic effect was associated with increased levels of SCFAs such as acetate, propionate, and butyrate in the gut of MPTP-lesioned mice. Moreover, transcriptomic analyses revealed upregulated expression of FFAR2 and FFAR3 in MPTP-lesioned mice, indicating their crucial role in mediating the benefits of FMT on the central nervous system. These results provide compelling evidence that gut microbiota and SCFAs play a critical role in modulating the gut-brain axis, offering new insights into PD's etiology and potential targets for therapeutic intervention.

Protective Effects of Bifidobacterium Breve MCC1274 as a Novel Therapy for Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of dementia and is characterized by memory impairment that significantly interferes with daily life. Therapeutic options for AD that substantively modify disease progression remain a critical unmet need. In this regard, the gut microbiota is crucial in maintaining human health by regulating metabolism and immune responses, and increasing evidence suggests that probiotics, particularly beneficial bacteria, can enhance memory and cognitive functions. Recent studies have highlighted the positive effects of Bifidobacterium breve MCC1274 (B. breve MCC1274) on individuals with mild cognitive impairment (MCI) and schizophrenia. Additionally, oral supplementation with B. breve MCC1274 has been shown to effectively prevent memory decline in AppNL-G-F mice. In relation to Alzheimer's pathology, oral supplementation with B. breve MCC1274 has been found to reduce amyloid-β (Aβ) accumulation and tau phosphorylation in both AppNL-G-F and wild-type (WT) mice. It also decreases microglial activation and increases levels of synaptic proteins. In this review, we examine the beneficial effects of B. breve MCC1274 on AD, exploring potential mechanisms of action and how this probiotic strain may aid in preventing or treating the disease. Furthermore, we discuss the broader implications of B. breve MCC1274 for improving overall host health and provide insights into future research directions for this promising probiotic therapy.

Sleep deprivation-induced shifts in gut microbiota: Implications for neurological disorders

Sleep deprivation is a prevalent issue in contemporary society, with significant ramifications for both physical and mental well-being. Emerging scientific evidence illuminates its intricate interplay with the gut-brain axis, a vital determinant of neurological function. Disruptions in sleep patterns disturb the delicate equilibrium of the gut microbiota, resulting in dysbiosis characterized by alterations in microbial composition and function. This dysbiosis contributes to the exacerbation of neurological disorders such as depression, anxiety, and cognitive decline through multifaceted mechanisms, including heightened neuroinflammation, disturbances in neurotransmitter signalling, and compromised integrity of the gut barrier. In response to these challenges, there is a burgeoning interest in therapeutic interventions aimed at restoring gut microbial balance and alleviating neurological symptoms precipitated by sleep deprivation. Probiotics, dietary modifications, and behavioural strategies represent promising avenues for modulating the gut microbiota and mitigating the adverse effects of sleep disturbances on neurological health. Moreover, the advent of personalized interventions guided by advanced omics technologies holds considerable potential for tailoring treatments to individualized needs and optimizing therapeutic outcomes. Interdisciplinary collaboration and concerted research efforts are imperative for elucidating the underlying mechanisms linking sleep, gut microbiota, and neurological function. Longitudinal studies, translational research endeavours, and advancements in technology are pivotal for unravelling the complex interplay between these intricate systems.