The microbiota-gut-brain axis: pathways to better brain health. Perspectives on what we know, what we need to investigate and how to put knowledge into practice

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.

A prebiotic intervention improves mood in everyday life in healthy women but not in men: Exploratory results from a larger double-blind placebo controlled cross-over study

Prebiotic dietary fiber (PDF) may reduce feelings of stress or improve mood in healthy individuals. Yet gut intervention studies that focus on mood in daily life are lacking and few studies include extensive biological sample analyses to gain mechanistic insights. As part of a larger randomized placebo-controlled crossover study including healthy individuals, we explored the effects of 12 weeks of PDF (acacia gum and carrot powder) on everyday mood, as measured with ecological momentary assessment (EMA). Microbiome composition and levels of microbial metabolites, endocrine, and inflammatory markers were determined prior to and after both intervention phases. Fifty-four participants completed the study. The intervention significantly increased daily positive affect (PA) and reduced daily negative affect (NA) in female but not male participants. The intervention-induced reduction in NA was associated with an increase in microbial diversity in female participants. The intervention did not significantly affect levels of fecal short chain fatty acids, cortisol, and inflammatory markers. This is one of the first studies to show that a dietary fiber intervention can positively alter mood as it is experienced in everyday life. Overall, our findings may stimulate more targeted gut-microbiome interventions and detection of its mental health effects in real life.

Fecal microbiota transplantation, a tool to transfer healthy longevity

The complex gut microbiome influences host aging and plays an important role in the manifestation of age-related diseases. Restoring a healthy gut microbiome via Fecal Microbiota Transplantation (FMT) is receiving extensive consideration to therapeutically transfer healthy longevity. Herein, we comprehensively review the benefits of gut microbial rejuvenation - via FMT - to promote healthy aging, with few studies documenting life length properties. This review explores how preconditioning donors via standard - lifestyle and pharmacological - antiaging interventions reshape gut microbiome, with the resulting benefits being also FMT-transferable. Finally, we expose the current clinical uses of FMT in the context of aging therapy and address FMT challenges - regulatory landscape, protocol standardization, and health risks - that require refinement to effectively utilize microbiome interventions in the elderly.

Understanding immune system dysfunction and its context in mood disorders: psychoneuroimmunoendocrinology and clinical interventions

Mood disorders include a set of psychiatric manifestations of increasing prevalence in our society, being mainly represented by major depressive disorder (MDD) and bipolar disorder (BD). The etiopathogenesis of mood disorders is extremely complex, with a wide spectrum of biological, psychological, and sociocultural factors being responsible for their appearance and development. In this sense, immune system dysfunction represents a key mechanism in the onset and pathophysiology of mood disorders, worsening mainly the central nervous system (neuroinflammation) and the periphery of the body (systemic inflammation). However, these alterations cannot be understood separately, but as part of a complex picture in which different factors and systems interact with each other. Psychoneuroimmunoendocrinology (PNIE) is the area responsible for studying the relationship between these elements and the impact of mind-body integration, placing the immune system as part of a whole. Thus, the dysfunction of the immune system is capable of influencing and activating different mechanisms that promote disruption of the psyche, damage to the nervous system, alterations to the endocrine and metabolic systems, and disruption of the microbiota and intestinal ecosystem, as well as of other organs and, in turn, all these mechanisms are responsible for inducing and enhancing the immune dysfunction. Similarly, the clinical approach to these patients is usually multidisciplinary, and the therapeutic arsenal includes different pharmacological (for example, antidepressants, antipsychotics, and lithium) and non-pharmacological (i.e., psychotherapy, lifestyle, and electroconvulsive therapy) treatments. These interventions also modulate the immune system and other elements of the PNIE in these patients, which may be interesting to understand the therapeutic success or failure of these approaches. In this sense, this review aims to delve into the relationship between immune dysfunction and mood disorders and their integration in the complex context of PNIE. Likewise, an attempt will be made to explore the effects on the immune system of different strategies available in the clinical approach to these patients, in order to identify the mechanisms described and their possible uses as biomarkers.

The role of the microbiota-gut-brain axis and artificial intelligence in cognitive health of pediatric obstructive sleep apnea: A narrative review

Pediatric obstructive sleep apnea (OSA) is a prevalent sleep-related breathing disorder associated with significant neurocognitive and behavioral impairments. Recent studies have highlighted the role of gut microbiota and the microbiota-gut-brain axis (MGBA) in influencing cognitive health in children with OSA. This narrative review aims to summarize current knowledge on the relationship between gut microbiota, MGBA, and cognitive function in pediatric OSA. It also explores the potential of artificial intelligence and machine learning in advancing this field and identifying novel therapeutic strategies. Pediatric OSA is associated with gut dysbiosis, reduced microbial diversity, and metabolic disruptions. MGBA mechanisms, such as endocrine, immune, and neural pathways, link gut microbiota to cognitive outcomes. Artificial intelligence and machine learning methodologies offer promising tools to uncover microbial markers and mechanisms associated with cognitive deficits in OSA. Future research should focus on validating these findings through clinical trials and developing personalized therapeutic approaches targeting the gut microbiota.

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.

D, Rajendran P, N H, Singh S A. Exploring the potential of probiotics in Alzheimer's disease and gut dysbiosis

Alzheimer's disease is a fatal neurodegenerative disorder that causes memory loss and cognitive decline in older people. There is increasing evidence suggesting that gut microbiota alteration is a cause of Alzheimer's disease pathogenesis. This review explores the link between gut dysbiosis and the development of Alzheimer's disease contributing to neuroinflammation, amyloid β accumulation, and cognitive decline. We examine the recent studies that illustrate the gut-brain axis (GBA) as a bidirectional communication between the gut and brain and how its alteration can influence neurological health. Furthermore, we discuss the potential of probiotic supplementation as a management approach to restore gut microbiota balance, and ultimately improve cognitive function in AD patients. Based on current research findings, this review aims to provide insights into the promising role of probiotics in Alzheimer's disease management and the need for further investigation into microbiota-targeted interventions.

From Gut to Brain: Unraveling the Intricate Link Between Microbiome and Stroke

Stroke, a neurological disorder, is intricately linked to the gut microbiota, influencing microbial composition and elevating the risk of ischemic stroke. The neuroprotective impact of short-chain fatty acids (SCFAs) derived from dietary fiber fermentation contrasts with the neuroinflammatory effects of lipopolysaccharide (LPS) from gut bacteria. The pivotal role of the gut-brain axis, facilitating bidirectional communication between the gut and the brain, is crucial in maintaining gastrointestinal equilibrium and influencing cognitive functions. An in-depth understanding of the interplay among the gut microbiota, immune system, and neurological outcomes in stroke is imperative for devising innovative preventive and therapeutic approaches. Strategies such as dietary adjustments, probiotics, prebiotics, antibiotics, or fecal transplantation offer promise in modulating stroke outcomes. Nevertheless, comprehensive research is essential to unravel the precise mechanisms governing the gut microbiota's involvement in stroke and to establish effective therapeutic interventions. The initiation of large-scale clinical trials is warranted to assess the safety and efficacy of interventions targeting the gut microbiota in stroke management. Tailored strategies that reinstate eubiosis and foster a healthy gut microbiota hold potential for both stroke prevention and treatment. This review underscores the gut microbiota as a promising therapeutic target in stroke and underscores the need for continued research to delineate its precise role and develop microbiome-based interventions effectively.

(Poly)phenols and brain health - beyond their antioxidant capacity

(Poly)phenols are a group of naturally occurring phytochemicals present in high amounts in plant food and beverages with various structures and activities. The impact of (poly)phenols on brain function has gained significant attention due to the growing interest in the potential benefits of these dietary bioactive molecules for cognitive health and neuroprotection. This review will therefore summarise the current knowledge related to the impact of (poly)phenols on brain health presenting evidence from both epidemiological and clinical studies. Cellular and molecular mechanisms in relation to the observed effects will also be described, including their impact on the gut microbiota through the modulation of the gut-brain axis. Although (poly)phenols have the potential to modulate the gut-brain axis regulation and influence cognitive function and decline through their interactions with gut microbiota, anti-inflammatory and antioxidant properties, further research, including randomised controlled trials and mechanistic studies, is needed to better understand the underlying mechanisms and establish causal relationships between (poly)phenol intake and brain health.

The gut-brain-metabolic axis: exploring the role of microbiota in insulin resistance and cognitive function

The gut-brain-metabolic axis has emerged as a critical area of research, highlighting the intricate connections between the gut microbiome, metabolic processes, and cognitive function. This review article delves into the complex interplay between these interconnected systems, exploring their role in the development of insulin resistance and cognitive decline. The article emphasizes the pivotal influence of the gut microbiota on central nervous system (CNS) function, demonstrating how microbial colonization can program the hypothalamic-pituitary-adrenal (HPA) axis for stress response in mice. It further elucidates the mechanisms by which gut microbial carbohydrate metabolism contributes to insulin resistance, a key factor in the pathogenesis of metabolic disorders and cognitive impairment. Notably, the review highlights the therapeutic potential of targeting the gut-brain-metabolic axis through various interventions, such as dietary modifications, probiotics, prebiotics, and fecal microbiota transplantation (FMT). These approaches have shown promising results in improving insulin sensitivity and cognitive function in both animal models and human studies. The article also emphasizes the need for further research to elucidate the specific microbial species and metabolites involved in modulating the gut-brain axis, as well as the long-term effects and safety of these therapeutic interventions. Advances in metagenomics, metabolomics, and bioinformatics are expected to provide deeper insights into the complex interactions within the gut microbiota and their impact on host health. Overall, this comprehensive review underscores the significance of the gut-brain-metabolic axis in the pathogenesis and treatment of metabolic and cognitive disorders, offering a promising avenue for the development of novel therapeutic strategies targeting this intricate system.

Bifidobacteria with indole-3-lactic acid-producing capacity exhibit psychobiotic potential via reducing neuroinflammation

The escalating global prevalence of depression demands effective therapeutic strategies, with psychobiotics emerging as a promising solution. However, the molecular mechanisms governing the neurobehavioral impact of psychobiotics remain elusive. This study reveals a significant reduction in hippocampal indole-3-lactic acid (ILA) levels in depressed mice, which is ameliorated by the psychobiotic Bifidobacterium breve. In both human subjects and mice, the ILA increase in the circulatory system results from bifidobacteria supplementation. Further investigation identifies the key aromatic lactate dehydrogenase (Aldh) gene and pathway in bifidobacteria responsible for ILA production. Importantly, the antidepressant effects are nullified in the Aldh mutants compared to the wild-type strain. At the bifidobacteria species level, those with Aldh exhibit heightened antidepressant effects. Finally, this study emphasizes the antidepressant efficacy of psychobiotic-derived ILA, potentially mediated by aryl hydrocarbon receptor (AhR) signaling activation to alleviate neuroinflammation. This study unveils the molecular and genetic foundations of psychobiotics' antidepressant effects, offering insights for microbial therapies targeting mood disorders.

Positive Outcomes of Supplementation with Lecithin-Based Delivery Formulation of Curcuma longa and Boswellia serrata in IBS Subjects with Small Bowel Dysbiosis

BACKGROUND

Small bowel dysbiosis (SBD) is a frequent finding in subjects with irritable bowel syndrome (IBS). The sunflower lecithin (phytosome) formulation of Curcuma longa and Boswellia serrata demonstrated beneficial effects on intestinal microbiota. This study aimed to evaluate the impact of a lecithin-based delivery formulation of Curcuma longa and Boswellia serrata extracts (CUBO) on SBD in IBS subjects.

SUBJECTS

Forty-nine adult subjects with IBS and SBD were randomly supplemented for 30 days with CUBO and a low-FODMAP diet (LFD) (intervention) or with LFD and placebo (control group).

RESULTS

The intervention group showed a significant reduction in urinary indican (p < 0.001), which was the marker of SBD, and of abdominal bloating (p < 0.001) and abdominal pain (p < 0.001). The pre-post control group analysis did not evidence significant differences. The comparison between the two groups (net effect in intervention minus control subjects) showed that the changes differ significantly for urinary indican p < 0.001 (-42.88; 95% CI: -62.04 to -23.72), abdominal bloating p < 0.001 (-1.50; 95% CI: -1.93 to -1.07), and abdominal pain p < 0.001 (-2.37; 95% CI: -3.61 to -1.13) and for the global assessment of efficacy (p < 0.001). The efficacy was 20% greater in males than in females.

CONCLUSIONS

In IBS subjects, the intervention with CUBO and LFD shows a significantly higher reduction in SBD, abdominal pain, and bloating compared to LFD and placebo. Additional research is needed to confirm these data.

The Interaction Between Nutraceuticals and Gut Microbiota: a Novel Therapeutic Approach to Prevent and Treatment Parkinson's Disease

Parkinson's disease (PD) is a complex neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons, leading to motor and non-motor symptoms. Emerging research has shed light on the role of gut microbiota in the pathogenesis and progression of PD. Nutraceuticals such as curcumin, berberine, phytoestrogens, polyphenols (e.g., resveratrol, EGCG, and fisetin), dietary fibers have been shown to influence gut microbiota composition and function, restoring microbial balance and enhancing the gut-brain axis. The mechanisms underlying these benefits involve microbial metabolite production, restoration of gut barrier integrity, and modulation of neuroinflammatory pathways. Additionally, probiotics and prebiotics have shown potential in promoting gut health, influencing the gut microbiome, and alleviating PD symptoms. They can enhance the gut's antioxidant capacity of the gut, reduce inflammation, and maintain immune homeostasis, contributing to a neuroprotective environment. This paper provides an overview of the current state of knowledge regarding the potential of nutraceuticals and gut microbiota modulation in the prevention and management of Parkinson's disease, emphasizing the need for further research and clinical trials to validate their effectiveness and safety. The findings suggest that a multifaceted approach involving nutraceuticals and gut microbiota may open new avenues for addressing the challenges of PD and improving the quality of life for affected individuals.

Microbiota-gut-brain axis: Natural antidepressants molecular mechanism

BACKGROUND

Major depressive disorder (MDD) is a severe mental health condition characterized by persistent depression, impaired cognition, and reduced activity. Increasing evidence suggests that gut microbiota (GM) imbalance is closely linked to the emergence and advancement of MDD, highlighting the potential significance of regulating the "Microbiota-Gut-Brain" (MGB) axis to impact the development of MDD. Natural products (NPs), characterized by broad biological activities, low toxicity, and multi-target characteristics, offer unique advantages in antidepressant treatment by regulating MGB axis.

PURPOSE

This review was aimed to explore the intricate relationship between the GM and the brain, as well as host responses, and investigated the mechanisms underlying the MGB axis in MDD development. It also explored the pharmacological mechanisms by which NPs modulate MGB axis to exert antidepressant effects and addressed current research limitations. Additionally, it proposed new strategies for future preclinical and clinical applications in the MDD domain.

METHODS

To study the effects and mechanism by which NPs exert antidepressant effects through mediating the MGB axis, data were collected from Web of Science, PubMed, ScienceDirect from initial establishment to March 2024. NPs were classified and summarized by their mechanisms of action.

RESULTS

NPs, such as flavonoids,alkaloids,polysaccharides,saponins, terpenoids, can treat MDD by regulating the MGB axis. Its mechanism includes balancing GM, regulating metabolites and neurotransmitters such as SCAFs, 5-HT, BDNF, inhibiting neuroinflammation, improving neural plasticity, and increasing neurogenesis.

CONCLUSIONS

NPs display good antidepressant effects, and have potential value for clinical application in the prevention and treatment of MDD by regulating the MGB axis. However, in-depth study of the mechanisms by which antidepressant medications affect MGB axis will also require considerable effort in clinical and preclinical research, which is essential for the development of effective antidepressant treatments.

(Poly)phenol-rich grape and blueberry extract prevents LPS-induced disruption of the blood-brain barrier through the modulation of the gut microbiota-derived uremic toxins

The dynamic protective capacity of (poly)phenols, attributed to their potent antioxidant and anti-inflammatory properties, has been consistently reported. Due to their capacity to alter gut microbiome composition, further actions of (poly)phenols may be exerted through the modulation of the microbiota-gut-brain axis. However, the underlying mechanisms remain poorly defined. Here, we investigated the protective effect of a (poly)phenol-rich grape and blueberry extract (Memophenol™), on the microbiota-gut-brain axis in a model of chronic low-grade inflammation (0.5 mg/kg/wk lipopolysaccharide (LPS) for 8 weeks). Dietary supplementation of male C57BL/6 J mice with Memophenol™ prevented LPS-induced increases in the microbe-derived uremia-associated molecules, indoxyl sulfate (IS) and trimethylamine N-oxide (TMAO). These changes coincided with shifts in gut microbiome composition, notably Romboutsia and Desulfovibrio abundance, respectively. In the brain, LPS exposure disrupted the marginal localisation of the endothelial tight junction ZO-1 and downregulated ZO-1 mRNA expression to an extent closely correlated with TMAO and IS levels; a process prevented by Memophenol™ intake. Hippocampal mRNA sequencing analysis revealed significant downregulation in regulatory pathways of neurodegeneration with Memophenol™ intake. These findings may indicate a novel protective role of the (poly)phenol-rich grape and blueberry extract on the endothelial tight junction component ZO-1, acting through modulation of gut microbial metabolism.

Experiences of discrimination are associated with microbiome and transcriptome alterations in the gut

Background

Discrimination is a recognized psychosocial stressor that has been linked to various negative health outcomes. This study explored the impact of discrimination on gut health, specifically focusing on microbiome changes, predicted metagenomic differences, transcriptomic profiles, and the potential for using a multi-omic approach to predict discrimination to identify discrimination status for an individual. Methods: We conducted a comprehensive investigation involving male and premenopausal female participants, using the Everyday Discrimination Scale to classify them into either high or low discrimination. Multiple questionnaires were administered to evaluate participants' physiological, psychological, and perceived stressors. Two diet questionnaires were also administered. Stool samples were collected for microbiome analysis and RNA sequencing. Microbial composition changes were analyzed using the Shannon index and Chao1 richness estimator for alpha diversity and the Aitchison distance metric for beta diversity. Differential abundance was evaluated using MaAsLin2, followed by metatranscriptomics sequencing and annotation. A multi-omic approach utilizing random forest was used to assess the predictability of discrimination.

Results

The study results showed that high discrimination was linked to higher gut microbiome species richness (Chao1, p = 0.02) and significant beta diversity differences (p = 0.04). Prevotella and Ruminococcaceae were both less abundant in the high discrimination group. High discrimination participants also reported higher levels of depression, anxiety, perceived stress, early life adversity, visceral sensitivity, and neuroticism than those in the low discrimination group. Gene expression analysis revealed distinctive patterns, with significant changes in genes associated with environmental sensing (two-component system) and metabolic pathways. In a plot comparing gene transcription to DNA content, certain genes showed higher expression levels in participants who experienced both high and low levels of discrimination. Our random forest classifier demonstrated the capability to accurately differentiate individuals with high and low discrimination in our training cohort (AUC = 0.91).

Conclusion

These findings illuminate the substantial impact of discrimination on gut health, encompassing microbiome composition, gene expression, and functional pathways. These findings suggest that discrimination is associated with internal biological changes that can be associated with negative health outcomes, opening research to examine novel pathways that can be used to mitigate the negative health effects of discrimination.

Modulatory effects of traditional Chinese medicines on gut microbiota and the microbiota-gut-x axis

The gut microbiota offers numerous benefits to the human body, including the promotion of nutrient absorption, participation in metabolic processes, and enhancement of immune function. Recent studies have introduced the concept of the gut-organ axis, which encompasses interactions such as the gut-brain axis, gut-liver axis, and gut-lung axis. This concept underscores the complex interplay between gut microbiota and various organs and tissues, including the brain, heart, lungs, liver, kidneys, muscles, and bones. Growing evidence indicates that gut microbiota can influence the onset and progression of multi-organ system diseases through their effects on the gut-organ axis. Traditional Chinese medicine has demonstrated significant efficacy in regulating the gastrointestinal system, leveraging its unique advantages. Considerable advancements have been made in understanding the role of gut microbiota and the gut-organ axis within the mechanisms of action of traditional Chinese medicine. This review aims to elucidate the roles of gut microbiota and the gut-organ axis in human health, explore the potential connections between traditional Chinese medicine and gut microbiota, and examine the therapeutic effects of traditional Chinese medicine on the microbiota-gut-organ axis. Furthermore, the review addresses the limitations and challenges present in current research while proposing potential directions for future investigations in this area.

Oxymatrine and Gut Microbiota Modulation: A Potential Therapeutic Strategy for Bone Cancer Pain Management

Chronic pain often coincides with changes in gut microbiota composition. Yet, the role of gut microbiota in bone cancer pain (BCP) is still not fully understood. This study investigated the role of gut microbiota in BCP and the effect of oxymatrine (OMT) on gut microbiota in BCP. A BCP mice model was developed to assess gut microbiota composition, serum and brain tissue butyric acid levels, and blood-brain barrier (BBB) permeability. Microbiota transplantation was used to restore gut microbiota, and the effect of Clostridium butyricum or sodium butyrate (NaB) supplementation on pain-related behaviors and BBB integrity was evaluated. The potential benefits of OMT on gut microbiota composition, peroxisome proliferator-activated receptor gamma (PPARγ)/cyclooxygenase-2 (COX-2) signaling, BBB integrity, and pain-related behaviors were also explored. BCP significantly altered gut microbiota composition and reduced serum and brain tissue butyric acid levels. Additionally, BBB permeability increased considerably in the BCP group compared with sham and control mice. Microbiota transplantation, as well as C butyricum or NaB supplementation, ameliorated pain-related behaviors and BBB integrity; the supplementation of C butyricum or NaB boosted brain-tight-junction protein expression, potentially through modulating PPARγ/COX-2 signaling. OMT influenced gut microbiota composition and regulated PPARγ/COX-2 signaling in the BCP model, improving pain-related behaviors and BBB integrity. BCP affects gut microbiota composition and butyric acid levels. Modulating gut microbiota and butyric acid levels through transplantation or supplementation may alleviate BCP. OMT shows potential as a treatment by altering gut microbiota composition and regulating PPARγ/COX-2 signaling. These findings provide new insights into BCP pathophysiology and possible treatments. PERSPECTIVE: This study explores the impact of gut microbiota on BCP. Microbiota transplantation alleviates BCP and enhances BBB integrity. Also, C butyricum or NaB improves BBB via PPARγ/COX-2. OMT, a BCP treatment, modifies microbiota by regulating PPARγ/COX-2, in turn improving pain and BBB integrity. These findings suggest a therapeutic approach, emphasizing clinical relevance in targeting gut microbiota and restoring butyric acid levels.

From Microbes to Myocardium: A Comprehensive Review of the Impact of the Gut-Brain Axis on Cardiovascular Disease

Cardiovascular diseases (CVDs) remain the leading cause of morbidity and mortality worldwide despite advances in medical research and therapeutics. Emerging evidence suggests a significant role of the gut-brain axis, a complex communication network involving the gut microbiota, central nervous system, and cardiovascular system, in modulating cardiovascular health. The gut microbiota influences systemic inflammation, neurohumoral pathways, and metabolic processes, which are critical in the pathogenesis of CVD. Dysbiosis, or an imbalance in the gut microbiota, has been implicated in various cardiovascular conditions, including hypertension, atherosclerosis, and heart failure. This comprehensive review aims to elucidate the intricate relationship between the gut microbiome, brain, and cardiovascular system, highlighting the mechanisms by which gut-derived signals affect cardiovascular function. Key microbial metabolites, such as short-chain fatty acids (SCFAs) and trimethylamine N-oxide (TMAO), and their impact on vascular health and blood pressure regulation are discussed. Furthermore, the review explores potential therapeutic strategies targeting the gut-brain axis, including probiotics, prebiotics, dietary modifications, and pharmacological interventions, to improve cardiovascular outcomes. Despite promising findings, the field faces challenges such as individual variability in microbiome composition, complexities in gut-brain interactions, and the need for robust clinical trials to establish causality. Addressing these challenges through interdisciplinary research could pave the way for innovative, personalized therapeutic approaches. This review provides a comprehensive understanding of the gut-brain-cardiovascular axis, underscoring its potential as a novel target for preventing and treating CVD.

The Causal Relationships Between Gut Microbiota, Brain Volume, and Intelligence: A Two-Step Mendelian Randomization Analysis

BACKGROUND

Growing evidence indicates that dynamic changes in gut microbiome can affect intelligence; however, whether these relationships are causal remains elusive. We aimed to disentangle the poorly understood causal relationship between gut microbiota and intelligence.

METHODS

We performed a 2-sample Mendelian randomization (MR) analysis using genetic variants from the largest available genome-wide association studies of gut microbiota (N = 18,340) and intelligence (N = 269,867). The inverse-variance weighted method was used to conduct the MR analyses complemented by a range of sensitivity analyses to validate the robustness of the results. Considering the close relationship between brain volume and intelligence, we applied 2-step MR to evaluate whether the identified effect was mediated by regulating brain volume (N = 47,316).

RESULTS

We found a risk effect of the genus Oxalobacter on intelligence (odds ratio = 0.968 change in intelligence per standard deviation increase in taxa; 95% CI, 0.952-0.985; p = 1.88 × 10-4) and a protective effect of the genus Fusicatenibacter on intelligence (odds ratio = 1.053; 95% CI, 1.024-1.082; p = 3.03 × 10-4). The 2-step MR analysis further showed that the effect of genus Fusicatenibacter on intelligence was partially mediated by regulating brain volume, with a mediated proportion of 33.6% (95% CI, 6.8%-60.4%; p = .014).

CONCLUSIONS

Our results provide causal evidence indicating the role of the microbiome in intelligence. Our findings may help reshape our understanding of the microbiota-gut-brain axis and development of novel intervention approaches for preventing cognitive impairment.

What do Climate Change, Nutrition, and the Environment Have to do With Mental Health?

Climate change is becoming the most significant global challenge and must be addressed on a global scale. At the time that this article is being written, the planetary heat in 2023 was the hottest on record. Similarly, the World Health Organization reports that 99% of the world's population lives in regions of unhealthy air pollution. Similarly, depression has become one of the leading causes of global mental and physical disabilities, and the impact of depression is predicted to only worsen over the next 25 years. It is interesting to note that climate experts often overlook the adoption of nutrition via a whole plant-based diet as a solution to both mental illness and climate change. In this review, we will touch upon the role of nutrition in gut microbiota and mental health, the impact diet has on greenhouse gases, the role of ultra-processed food, and environmental factors such as air pollution and increasing planetary heat and their growing impacts on mental health. In the end, the promotion of plant-based foods has the potential to improve personal mental and physical health while improving planetary health.

Strengthening Neuroplasticity in Substance Use Recovery Through Lifestyle Intervention

The incidence of substance use and behavioral addictions continues to increase throughout the world. The Global Burden of Disease Study shows a growing impact in disability-adjusted life years due to substance use. Substance use impacts families, communities, health care, and legal systems; yet, the vast majority of individuals with substance use disorders do not seek treatment. Within the United States, new legislation has attempted to increase the availability of buprenorphine, but the impact of substance use continues. Although medications and group support therapy have been the mainstay of treatment for substance use, lifestyle medicine offers a valuable adjunct therapy that may help strengthen substance use recovery through healthy neuroplastic changes.

Impact of Gut Microbiota on Aging and Frailty: A Narrative Review of the Literature

Aging is a natural, complex, and individual process that focuses on the progressive decay of the body and a decrease in cell function that begins in approximately the sixth decade of life and ends with death. Current scientific evidence shows that the aging process is mostly related to genetic load and varies because of the environment. Therefore, aging can be adjusted through the intervention of factors that control homeostasis in genetic, biochemical, and immunological processes, including those involving the gut microbiota. Indeed, the diversity of the gut microbiota decreases during aging, based on the presence of modifications in the hormonal, immunological, and operational processes of the gastrointestinal tract. These modifications lead to a state of dysbiosis. However, altering bacterial communities remains complicated due to the great diversity of factors that influence their modification. Alterations caused by the aging process are known to foster dysbiosis and correspond to conditions that determine the degree of frailty in senior citizens. Consequently, the microbial structure can be used as a biomarker for geriatric care in the promotion of healthy aging.

Intestinal Akkermansia muciniphila is Beneficial to Functional Recovery Following Ischemic Stroke

Recent studies have demonstrated the interaction between gut microbiota and brain on ischemic stroke, but the roles of gut microbiota in the pathophysiology of ischemic stroke remain largely unclear. In this study, we detected a significant increase of intestinal Akkermansia muciniphila (AKK) following ischemic stroke by a rose bengal photothrombosis model. To investigate the function and mechanism of AKK on ischemic stroke, we performed the AKK administration prior to stroke surgery. The results showed that mice treated with AKK gained significantly higher body weight and behaved better than those in PBS group at 3 days after ischemic stroke. Consistently, AKK administration remarkably decreased the infarct volumes as well as the density of degenerating neurons and apoptotic cells after ischemic stroke. Notably, AKK is a potential therapeutic target in immune-related disorders connected to the microbiota, and inflammation is crucially involved in the pathophysiological process of ischemic stroke. For the determination of underlying mechanisms of this protective effect, we investigated whether there are associations between AKK and neuroinflammation following ischemic stroke. The results suggested that AKK administration significantly reduced the activation of astrocytes and microglia but up-regulated multiple anti-inflammatory factors following ischemic stroke. Therefore, our study highlighted the beneficial roles of intestinal AKK on ischemic stroke and provided a new perspective for the treatment of ischemic stroke.

Probiotics in Traumatic Brain Injury: New Insights into Mechanisms and Future Perspectives

Traumatic brain injury (TBI) is a serious global public health issue, recognized as a chronic and progressive disease that can affect multiple organs, including the gastrointestinal (GI) tract. Research shows that there is a specific link between the GI tract and the central nervous system, termed the gut-brain axis, which consists of bidirectional exchange between these two. Several preclinical and clinical studies have demonstrated intestinal barrier dysfunction, intestinal inflammation and gut dysbiosis in patients with TBI. It is proven that probiotics can modulate the inflammatory process and modify gut microbiota. Numerous animal studies and human clinical trials have proven the effectiveness of selected bacterial strains as an adjuvant treatment in reducing inflammation, infection rates and time spent in intensive care of hospitalized patients suffering from brain injury. Thus, this review summarizes the current evidence regarding the beneficial effects of probiotic administration in patients suffering from TBI-related complications. This review will help identify novel therapeutic strategies in the future as probiotics have an extensive history of apparently safe use.

Differential Patterns of Gut and Oral Microbiomes in Hispanic Individuals with Cognitive Impairment

Alzheimer's disease and related dementias (ADRD) have been associated with alterations in both oral and gut microbiomes. While extensive research has focused on the role of gut dysbiosis in ADRD, the contribution of the oral microbiome remains relatively understudied. Furthermore, the potential synergistic interactions between oral and gut microbiomes in ADRD pathology are largely unexplored. This study aims to evaluate distinct patterns and potential synergistic effects of oral and gut microbiomes in a cohort of predominantly Hispanic individuals with cognitive impairment (CI) and without cognitive impairment (NC). We conducted 16S rRNA gene sequencing on stool and saliva samples from 32 participants (17 CI, 15 NC; 62.5% female, mean age = 70.4 ± 6.2 years) recruited in San Antonio, Texas, USA. Correlation analysis through MaAslin2 assessed the relationship between participants' clinical measurements (e.g., fasting glucose and blood cholesterol) and their gut and saliva microbial contents. Differential abundance analysis evaluated taxa with significant differences between CI and NC groups, and alpha and beta diversity metrics assessed within-sample and group compositional differences. Our analyses revealed no significant differences between NC and CI groups in fasting glucose or blood cholesterol levels. However, a clear association was observed between gut microbiome composition and levels of fasting glucose and blood cholesterol. While alpha and beta diversity metrics showed no significant differences between CI and NC groups, differential abundance analysis revealed an increased presence of oral genera such as Dialister , Fretibacterium , and Mycoplasma in CI participants. Conversely, CI individuals exhibited a decreased abundance of gut genera, including Shuttleworthia , Holdemania , and Subdoligranulum , which are known for their anti-inflammatory properties. No evidence was found for synergistic contributions between oral and gut microbiomes in the context of ADRD. Our findings suggest that similar to the gut microbiome, the oral microbiome undergoes significant modifications as individuals transition from NC to CI. Notably, the identified oral microbes have been previously associated with periodontal diseases and gingivitis. These results underscore the necessity for further investigations with larger sample sizes to validate our findings and elucidate the complex interplay between oral and gut microbiomes in ADRD pathogenesis.

Dietary fiber supplementation increases Drosophila melanogaster lifespan and gut microbiota diversity

Dietary fiber has been shown to have multiple health benefits, including a positive effect on longevity and the gut microbiota. In the present study, Drosophila melanogaster has been chosen as an in vivo model organism to study the health effects of dietary fiber supplementation (DFS). DFS extended the mean half-life of male and female flies, but the absolute lifespan only increased in females. To reveal the underlying mechanisms, we examined the effect of DFS on gut microbiota diversity and abundance, local gut immunity, and the brain proteome. A significant difference in the gut microbial community was observed between groups with and without fiber supplementation, which reduced the gut pathogenic bacterial load. We also observed an upregulated expression of dual oxidase and a modulated expression of Attacin and Diptericin genes in the gut of older flies, possibly delaying the gut dysbiosis connected to the age-related gut immune dysfunction. Brain proteome analysis showed that DFS led to the modulation of metabolic processes connected to mitochondrial biogenesis, the RhoV-GTPase cycle, organelle biogenesis and maintenance, membrane trafficking and vesicle-mediated transport, possibly orchestrated through a gut-brain axis interaction. Taken together, our study shows that DFS can prolong the half-life and lifespan of flies, possibly by promoting a healthier gut environment and delaying the physiological dysbiosis that characterizes the ageing process. However, the RhoV-GTPase cycle at the brain level may deserve more attention in future studies.

Research progress on insomnia treated by traditional Chinese medicine and acupuncture based on microbial-gut-brain axis theory

Insomnia, as one of the emotional diseases, has been increasing in recent years, which has a great impact on people's life and work. Therefore, researchers are eager to find a more perfect treatment. The microbiome-gut-brain axis is a new theory that has gradually become popular abroad in recent years and has a profound impact in the field of insomnia. In recent years, traditional Chinese medicine (TCM) has played an increasingly important role in the treatment of insomnia, especially acupuncture and Chinese herbal medicine. It is the main method of TCM in the treatment of insomnia. This paper mainly reviews the combination degree of "microorganism-gut-brain axis" theory with TCM and acupuncture under the system of TCM. To explore the mechanism of TCM and acupuncture in the treatment of insomnia under the guidance of "microorganism-gut-brain axis" theory, in order to provide a new idea for the diagnosis and treatment of insomnia.

Exploring environmental exposomes and the gut-brain nexus: Unveiling the impact of pesticide exposure

This review delves into the escalating concern of environmental pollutants and their profound impact on human health in the context of the modern surge in global diseases. The utilisation of chemicals in food production, which results in residues in food, has emerged as a major concern nowadays. By exploring the intricate relationship between environmental pollutants and gut microbiota, the study reveals a dynamic bidirectional interplay, as modifying microbiota profile influences metabolic pathways and subsequent brain functions. This review will first provide an overview of potential exposomes and their effect to gut health. This paper is then emphasis the connection of gut brain function by analysing microbiome markers with neurotoxicity responses. We then take pesticide as example of exposome to elucidate their influence to biomarkers biosynthesis pathways and subsequent brain functions. The interconnection between neuroendocrine and neuromodulators elements and the gut-brain axis emerges as a pivotal factor in regulating mental health and brain development. Thus, manipulation of gut microbiota function at the onset of stress may offer a potential avenue for the prevention and treatment for mental disorder and other neurodegenerative illness.

Dietary (Poly)phenols and the Gut-Brain Axis in Ageing

As the population ages, the incidence of age-related neurodegenerative diseases is rapidly increasing, and novel approaches to mitigate this soaring prevalence are sorely needed. Recent studies have highlighted the importance of gut microbial homeostasis and its impact on brain functions, commonly referred to as the gut-brain axis, in maintaining overall health and wellbeing. Nonetheless, the mechanisms by which this system acts remains poorly defined. In this review, we will explore how (poly)phenols, a class of natural compounds found in many plant-based foods and beverages, can modulate the gut-brain axis, and thereby promote neural health. While evidence indicates a beneficial role of (poly)phenol consumption as part of a balanced diet, human studies are scarce and mechanistic insight is still lacking. In this regard, we make the case that dietary (poly)phenols should be further explored to establish their therapeutic efficacy on brain health through modulation of the gut-brain axis, with much greater emphasis on carefully designed human interventions.

α7 nicotinic acetylcholine receptor in memory processing

Information storage in the brain involves different memory types and stages that are processed by several brain regions. Cholinergic pathways through acetylcholine receptors actively participate on memory modulation, and their disfunction is associated with cognitive decline in several neurological disorders. During the last decade, the role of α7 subtype of nicotinic acetylcholine receptors in different memory stages has been studied. However, the information about their role in memory processing is still scarce. In this review, we attempt to identify brain areas where α7 nicotinic receptors have an essential role in different memory types and stages. In addition, we discuss recent work implicating-or not-α7 nicotinic receptors as promising pharmacological targets for memory impairment associated with neurological disorders.

The effect of psychoactive bacteria, Bifidobacterium longum Rosell®-175 and Lactobacillus rhamnosus JB-1, on brain proteome profiles in mice

RATIONALE

The gut microbiota may play an important role in the development and functioning of the mammalian central nervous system. The assumption of the experiment was to prove that the use of probiotic bacterial strains in the diet of mice modifies the expression of brain proteins involved in metabolic and immunological processes.

OBJECTIVES AND RESULTS

Albino Swiss mice were administered with Bifidobacterium longum Rosell®-175 or Lactobacillus rhamnosus JB-1 every 24 h for 28 days. Protein maps were prepared from hippocampal homogenates of euthanized mice. Selected proteins that were statistically significant were purified and concentrated and identified using MALDI-TOF mass spectrometry. Among the analysed samples, 13 proteins were identified. The mean volumes of calcyon, secreted frizzled-associated protein 3, and catalase in the hippocampus of mice from both experimental groups were statistically significantly higher than in the control group. In mice supplemented with Lactobacillus rhamnosus JB-1, a lower mean volume of fragrance binding protein 2, shadow of prion protein, and glycine receptor α4 subunit was observed compared to the control.

CONCLUSION

The psychobiotics Bifidobacterium longum Rosell®-175 and Lactobacillus rhamnosus JB-1enhances expression of proteins involved in the activation and maturation of nerve cells, as well as myelination and homeostatic regulation of neurogenesis in mice. The tested psychobiotics cause a decrease in the expression of proteins associated with CNS development and in synaptic transmission, thereby reducing the capacity for communication between nerve cells. The results of the study indicate that psychobiotic bacteria can be used in auxiliary treatment of neurological disorders.

Trimethylamine-N-oxide aggravated the sympathetic excitation in D-galactose induced aging rats by down-regulating P2Y12 receptor in microglia

This study aimed to determine whether trimethylamine N-oxide (TMAO) was involved in sympathetic activation in aging and the underlying mechanisms. Our hypothesis is TMAO reduces P2Y12 receptor (P2Y12R) and induces microglia-mediated inflammation in the paraventricular nucleus (PVN), then leading to sympathetic activation in aging. This study involved 18 young adults and 16 old adults. Aging rats were established by injecting D-galactose (D-gal, 200 mg/kg/d) subcutaneously for 12 weeks. TMAO (120 mg/kg/d) or 1% 3, 3-dimethyl-l-butanol (DMB) was administrated via drinking water for 12 weeks to investigate their effects on neuroinflammation and sympathetic activation in aging rats. Plasma TMAO, NE and IL-1β levels were higher in old adults than in young adults. In addition, standard deviation of all normal to normal intervals (SDNN) and standard deviation of the average of normal to normal intervals (SDANN) were lower in old adults and negatively correlated with TMAO, indicating sympathetic activation in old adults, which is associated with an increase in TMAO levels. Treatment of rats with D-gal showed increased senescence-associated protein levels and microglia-mediated inflammation, as well as decreased P2Y12R protein levels in PVN. Plasma TMAO, NE and IL-1β levels were increased, accompanied by enhanced renal sympathetic nerve activity (RSNA). While TMAO treatment exacerbated the above phenomenon, DMB mitigated it. These findings suggest that TMAO contributes to sympathetic hyperactivity in aging by downregulating P2Y12R in microglia and increasing inflammation in the PVN. These results may provide promising new target for the prevention and treatment of aging and aging-related diseases.

Effect of gut hormones on bone metabolism and their possible mechanisms in the treatment of osteoporosis

Bone is a highly dynamic organ that changes with the daily circadian rhythm. During the day, bone resorption is suppressed due to eating, while it increases at night. This circadian rhythm of the skeleton is regulated by gut hormones. Until now, gut hormones that have been found to affect skeletal homeostasis include glucagon-like peptide-1 (GLP-1), glucagon-like peptide-2 (GLP-2), glucose-dependent insulinotropic polypeptide (GIP), and peptide YY (PYY), which exerts its effects by binding to its cognate receptors (GLP-1R, GLP-2R, GIPR, and Y1R). Several studies have shown that GLP-1, GLP-2, and GIP all inhibit bone resorption, while GIP also promotes bone formation. Notably, PYY has a strong bone resorption-promoting effect. In addition, gut microbiota (GM) plays an important role in maintaining bone homeostasis. This review outlines the roles of GLP-1, GLP-2, GIP, and PYY in bone metabolism and discusses the roles of gut hormones and the GM in regulating bone homeostasis and their potential mechanisms.

Probiotics and Prebiotics Affecting Mental and Gut Health

The effects of the gut microbiota on mental and intestinal health are an area of great interest. This study aimed to reveal the relationship between the intake of probiotic and prebiotic foods and mental and gut health. Data were obtained using an online survey from young adults (n = 538) enrolled at Afyonkarahisar Health Sciences University who agreed to participate in this study in the 2022-2023 academic year. This study included 538 participants, mostly (85.5%) females. Participants who never consumed yogurt had 7.614 times higher Gastrointestinal Symptom Rating Scale scores than those who consumed yogurt daily (p < 0.01). Similarly, the frequency of ayran consumption had a statistically significant effect on Bristol Stool Scale scores (p < 0.05). The ratio of normal defecation to constipation was 68.7% lower in participants who consumed ayran daily, whereas the ratio of diarrhea to constipation was 76.4% lower in participants who never consumed ayran. However, the frequency of prebiotic consumption did not have a significant effect on Bristol Stool Scale scores (p > 0.05). The consumption of probiotic and prebiotic foods exerted a significant effect on GSRS total scores and subfactors of the Depression Anxiety Stress Scale-42, namely depression, anxiety, and stress.

Confounder or Confederate? The Interactions Between Drugs and the Gut Microbiome in Psychiatric and Neurological Diseases

The gut microbiome is emerging as an important factor in signaling along the gut-brain axis. The intimate physiological connection between the gut and the brain allows perturbations in the microbiome to be directly transmitted to the central nervous system and thereby contribute to psychiatric and neurological diseases. Common microbiome perturbations result from the ingestion of xenobiotic compounds including pharmaceuticals such as psychotropic drugs. In recent years, a variety of interactions between these drug classes and the gut microbiome have been reported, ranging from direct inhibitory effects on gut bacteria to microbiome-mediated drug degradation or sequestration. Consequently, the microbiome may play a critical role in influencing the intensity, duration, and onset of therapeutic effects, as well as in influencing the side effects that patients may experience. Furthermore, because the composition of the microbiome varies from person to person, the microbiome may contribute to the frequently observed interpersonal differences in the response to these drugs. In this review, we first summarize the known interactions between xenobiotics and the gut microbiome. Then, for psychopharmaceuticals, we address the question of whether these interactions with gut bacteria are irrelevant for the host (i.e., merely confounding factors in metagenomic analyses) or whether they may even have therapeutic or adverse effects.

Gut microbiota, nutrition, and mental health

The human brain remains one of the greatest challenges for modern medicine, yet it is one of the most integral and sometimes overlooked aspects of medicine. The human brain consists of roughly 100 billion neurons, 100 trillion neuronal connections and consumes about 20-25% of the body's energy. Emerging evidence highlights that insufficient or inadequate nutrition is linked to an increased risk of brain health, mental health, and psychological functioning compromise. A core component of this relationship includes the intricate dynamics of the brain-gut-microbiota (BGM) system, which is a progressively recognized factor in the sphere of mental/brain health. The bidirectional relationship between the brain, gut, and gut microbiota along the BGM system not only affects nutrient absorption and utilization, but also it exerts substantial influence on cognitive processes, mood regulation, neuroplasticity, and other indices of mental/brain health. Neuroplasticity is the brain's capacity for adaptation and neural regeneration in response to stimuli. Understanding neuroplasticity and considering interventions that enhance the remarkable ability of the brain to change through experience constitutes a burgeoning area of research that has substantial potential for improving well-being, resilience, and overall brain health through optimal nutrition and lifestyle interventions. The nexus of lifestyle interventions and both academic and clinical perspectives of nutritional neuroscience emerges as a potent tool to enhance patient outcomes, proactively mitigate mental/brain health challenges, and improve the management and treatment of existing mental/brain health conditions by championing health-promoting dietary patterns, rectifying nutritional deficiencies, and seamlessly integrating nutrition-centered strategies into clinical care.

Potential effects of the most prescribed drugs on the microbiota-gut-brain-axis: A review

The link between drug-induced dysbiosis and its influence on brain diseases through gut-residing bacteria and their metabolites, named the microbiota-gut-brain axis (MGBA), remains largely unexplored. This review investigates the effects of commonly prescribed drugs (metformin, statins, proton-pump-inhibitors, NSAIDs, and anti-depressants) on the gut microbiota, comparing the findings with altered bacterial populations in major brain diseases (depression, multiple sclerosis, Parkinson's and Alzheimer's). The report aims to explore whether drugs can influence the development and progression of brain diseases via the MGBA. Central findings indicate that all explored drugs induce dysbiosis. These dysbiosis patterns were associated with brain disorders. The influence on brain diseases varied across different bacterial taxa, possibly mediated by direct effects or through bacterial metabolites. Each drug induced both positive and negative changes in the abundance of bacteria, indicating a counterbalancing effect. Moreover, the above-mentioned drugs exhibited similar effects, suggesting that they may counteract or enhance each other's effects on brain diseases when taken together by comorbid patients. In conclusion, the interplay of bacterial species and their abundances may have a greater impact on brain diseases than individual drugs or bacterial strains. Future research is needed to better understand drug-induced dysbiosis and the implications for brain disease pathogenesis, with the potential to develop more effective therapeutic options for patients with brain-related diseases.

Epigallocatechin-3-Gallate and Genistein for Decreasing Gut Dysbiosis, Inhibiting Inflammasomes, and Aiding Autophagy in Alzheimer's Disease

There are approximately 24 million cases of Alzheimer's disease (AD) worldwide, and the number of cases is expected to increase four-fold by 2050. AD is a neurodegenerative disease that leads to severe dementia in most patients. There are several neuropathological signs of AD, such as deposition of amyloid beta (Aβ) plaques, formation of neurofibrillary tangles (NFTs), neuronal loss, activation of inflammasomes, and declining autophagy. Several of these hallmarks are linked to the gut microbiome. The gastrointestinal (GI) tract contains microbial diversity, which is important in regulating several functions in the brain via the gut-brain axis (GBA). The disruption of the balance in the gut microbiota is known as gut dysbiosis. Recent studies strongly support that targeting gut dysbiosis with selective bioflavonoids is a highly plausible solution to attenuate activation of inflammasomes (contributing to neuroinflammation) and resume autophagy (a cellular mechanism for lysosomal degradation of the damaged components and recycling of building blocks) to stop AD pathogenesis. This review is focused on two bioflavonoids, specifically epigallocatechin-3-gallate (EGCG) and genistein (GS), as a possible new paradigm of treatment for maintaining healthy gut microbiota in AD due to their implications in modulating crucial AD signaling pathways. The combination of EGCG and GS has a higher potential than either agent alone to attenuate the signaling pathways implicated in AD pathogenesis. The effects of EGCG and GS on altering gut microbiota and GBA were also explored, along with conclusions from various delivery methods to increase the bioavailability of these bioflavonoids in the body.

The many faces of microbiota-gut-brain axis in autism spectrum disorder

The gut-brain axis is gaining more attention in neurodevelopmental disorders, especially autism spectrum disorder (ASD). Many factors can influence microbiota in early life, including host genetics and perinatal events (infections, mode of birth/delivery, medications, nutritional supply, and environmental stressors). The gut microbiome can influence blood-brain barrier (BBB) permeability, drug bioavailability, and social behaviors. Developing microbiota-based interventions such as probiotics, gastrointestinal (GI) microbiota transplantation, or metabolite supplementation may offer an exciting approach to treating ASD. This review highlights that RNA sequencing, metabolomics, and transcriptomics data are needed to understand how microbial modulators can influence ASD pathophysiology. Due to the substantial clinical heterogeneity of ASD, medical caretakers may be unlikely to develop a broad and effective general gut microbiota modulator. However, dietary modulation followed by administration of microbiota modulators is a promising option for treating ASD-related behavioral and gastrointestinal symptoms. Future work should focus on the accuracy of biomarker tests and developing specific psychobiotic agents tailored towards the gut microbiota seen in ASD patients, which may include developing individualized treatment options.

Brain Health and Cognition in Older Adults: Roadmap and Milestones towards the Implementation of Preventive Strategies

In this narrative review, we delve into the evolving concept of brain health, as recognized by the WHO, focusing on its intersection with cognitive decline. We emphasize the imperative need for preventive strategies, particularly in older adults. We describe the target population that might benefit the most from risk-based approaches-namely, people with subjective cognitive decline. Additionally, we consider universal prevention in cognitively unimpaired middle-aged and older adults. Delving into multidomain personalized preventive strategies, we report on empirical evidence surrounding modifiable risk factors and interventions crucial in mitigating cognitive decline. Next, we highlight the emergence of brain health services (BHS). We explain their proposed role in risk assessment, risk communication, and tailored interventions to reduce the risk of dementia. Commenting on ongoing BHS pilot experiences, we present the inception and framework of our own BHS in Monza, Italy, outlining its operational structure and care pathways. We emphasize the need for global collaboration and intensified research efforts to address the intricate determinants of brain health and their potential impact on healthcare systems worldwide.

Advancing lifelong precision medicine for cardiovascular diseases through gut microbiota modulation

The gut microbiome is known as the tenth system of the human body that plays a vital role in the intersection between health and disease. The considerable inter-individual variability in gut microbiota poses both challenges and great prospects in promoting precision medicine in cardiovascular diseases (CVDs). In this review, based on the development, evolution, and influencing factors of gut microbiota in a full life circle, we summarized the recent advances on the characteristic alteration in gut microbiota in CVDs throughout different life stages, and depicted their pathological links in mechanism, as well as the highlight achievements of targeting gut microbiota in CVDs prevention, diagnosis and treatment. Personalized strategies could be tailored according to gut microbiota characteristics in different life stages, including gut microbiota-blood metabolites combined prediction and diagnosis, dietary interventions, lifestyle improvements, probiotic or prebiotic supplements. However, to fulfill the promise of a lifelong cardiovascular health, more mechanism studies should progress from correlation to causality and decipher novel mechanisms linking specific microbes and CVDs. It is also promising to use the burgeoning artificial intelligence and machine learning to target gut microbiota for developing diagnosis system and screening for new therapeutic interventions.

The nerve cells in gastrointestinal cancers: from molecular mechanisms to clinical intervention

Gastrointestinal (GI) cancer is a formidable malignancy with significant morbidity and mortality rates. Recent studies have shed light on the complex interplay between the nervous system and the GI system, influencing various aspects of GI tumorigenesis, such as the malignance of cancer cells, the conformation of tumor microenvironment (TME), and the resistance to chemotherapies. The discussion in this review first focused on exploring the intricate details of the biological function of the nervous system in the development of the GI tract and the progression of tumors within it. Meanwhile, the cancer cell-originated feedback regulation on the nervous system is revealed to play a crucial role in the growth and development of nerve cells within tumor tissues. This interaction is vital for understanding the complex relationship between the nervous system and GI oncogenesis. Additionally, the study identified various components within the TME that possess a significant influence on the occurrence and progression of GI cancer, including microbiota, immune cells, and fibroblasts. Moreover, we highlighted the transformation relationship between non-neuronal cells and neuronal cells during GI cancer progression, inspiring the development of strategies for nervous system-guided anti-tumor drugs. By further elucidating the deep mechanism of various neuroregulatory signals and neuronal intervention, we underlined the potential of these targeted drugs translating into effective therapies for GI cancer treatment. In summary, this review provides an overview of the mechanisms of neuromodulation and explores potential therapeutic opportunities, providing insights into the understanding and management of GI cancers.

Repeated (S)-ketamine administration ameliorates the spatial working memory impairment in mice with chronic pain: role of the gut microbiota-brain axis

Chronic pain is commonly linked with diminished working memory. This study explores the impact of the anesthetic (S)-ketamine on spatial working memory in a chronic constriction injury (CCI) mouse model, focusing on gut microbiome. We found that multiple doses of (S)-ketamine, unlike a single dose, counteracted the reduced spontaneous alteration percentage (%SA) in the Y-maze spatial working memory test, without affecting mechanical or thermal pain sensitivity. Additionally, repeated (S)-ketamine treatments improved the abnormal composition of the gut microbiome (β-diversity), as indicated by fecal 16S rRNA analysis, and increased levels of butyrate, a key gut - brain axis mediator. Protein analysis showed that these treatments also corrected the upregulated histone deacetylase 2 (HDAC2) and downregulated brain-derived neurotrophic factor (BDNF) in the hippocampi of CCI mice. Remarkably, fecal microbiota transplantation from mice treated repeatedly with (S)-ketamine to CCI mice restored %SA and hippocampal BDNF levels in CCI mice. Butyrate supplementation alone also improved %SA, BDNF, and HDAC2 levels in CCI mice. Furthermore, the TrkB receptor antagonist ANA-12 negated the beneficial effects of repeated (S)-ketamine on spatial working memory impairment in CCI mice. These results indicate that repeated (S)-ketamine administration ameliorates spatial working memory impairment in CCI mice, mediated by a gut microbiota - brain axis, primarily through the enhancement of hippocampal BDNF - TrkB signaling by butyrate.

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.

Long-Term Implicit Epigenetic Stress Information in the Enteric Nervous System and its Contribution to Developing and Perpetuating IBS

Psychiatric and mood disorders may play an important role in the development and persistence of irritable bowel syndrome (IBS). Previously, we hypothesized that stress-induced implicit memories may persist throughout life via epigenetic processes in the enteric nervous system (ENS), independent of the central nervous system (CNS). These epigenetic memories in the ENS may contribute to developing and perpetuating IBS. Here, we further elaborate on our earlier hypothesis. That is, during pregnancy, maternal prenatal stresses perturb the HPA axis and increase circulating cortisol levels, which can affect the maternal gut microbiota. Maternal cortisol can cross the placental barrier and increase cortisol-circulating levels in the fetus. This leads to dysregulation of the HPA axis, affecting the gut microbiota, microbial metabolites, and intestinal permeability in the fetus. Microbial metabolites, such as short-chain fatty acids (which also regulate the development of fetal ENS), can modulate a range of diseases by inducing epigenetic changes. These mentioned processes suggest that stress-related, implicit, long-term epigenetic memories may be programmed into the fetal ENS during pregnancy. Subsequently, this implicit epigenetic stress information from the fetal ENS could be conveyed to the CNS through the bidirectional microbiota-gut-brain axis (MGBA), leading to perturbed functional connectivity among various brain networks and the dysregulation of affective and pain processes.

The Role of the Gut Microbiota in Anorexia Nervosa in Children and Adults-Systematic Review

Among the factors incriminated in the appearance of eating disorders, intestinal microbiota has recently been implicated. Now there is evidence that the composition of gut microbiota is different in anorexia nervosa. We gathered many surveys on the changes in the profile of gut microbiota in patients with anorexia nervosa. This review comprehensively examines the contemporary experimental evidence concerning the bidirectional communication between gut microbiota and the brain. Drawing from recent breakthroughs in this area of research, we propose that the gut microbiota significantly contributes to the intricate interplay between the body and the brain, thereby contributing to overall healthy homeostasis while concurrently impacting disease risk, including anxiety and mood disorders. Particular attention is devoted to elucidating the structure and functional relevance of the gut microbiota in the context of Anorexia Nervosa.

Gut liver brain axis in diseases: the implications for therapeutic interventions

Gut-liver-brain axis is a three-way highway of information interaction system among the gastrointestinal tract, liver, and nervous systems. In the past few decades, breakthrough progress has been made in the gut liver brain axis, mainly through understanding its formation mechanism and increasing treatment strategies. In this review, we discuss various complex networks including barrier permeability, gut hormones, gut microbial metabolites, vagus nerve, neurotransmitters, immunity, brain toxic metabolites, β-amyloid (Aβ) metabolism, and epigenetic regulation in the gut-liver-brain axis. Some therapies containing antibiotics, probiotics, prebiotics, synbiotics, fecal microbiota transplantation (FMT), polyphenols, low FODMAP diet and nanotechnology application regulate the gut liver brain axis. Besides, some special treatments targeting gut-liver axis include farnesoid X receptor (FXR) agonists, takeda G protein-coupled receptor 5 (TGR5) agonists, glucagon-like peptide-1 (GLP-1) receptor antagonists and fibroblast growth factor 19 (FGF19) analogs. Targeting gut-brain axis embraces cognitive behavioral therapy (CBT), antidepressants and tryptophan metabolism-related therapies. Targeting liver-brain axis contains epigenetic regulation and Aβ metabolism-related therapies. In the future, a better understanding of gut-liver-brain axis interactions will promote the development of novel preventative strategies and the discovery of precise therapeutic targets in multiple diseases.

Microbiome analysis of circulating bacterial extracellular vesicles in obsessive-compulsive disorder

AIM

The present study examined the microbiome abundance and composition of drug-naive or drug-free patients with obsessive-compulsive disorder (OCD) compared with healthy controls. In addition, in the OCD group, the microbiome composition was compared between early-onset and late-onset OCD.

METHODS

Serum samples were collected from 89 patients with OCD and 107 age- and sex-matched healthy controls. Bacterial DNA was isolated from bacteria-derived extracellular vesicles in serum and then amplified and quantified using primers specific to the V3-V4 hypervariable region of the 16S ribosomal RNA gene. The 16S ribosomal DNA gene amplicon sequencing was performed.

RESULTS

The pooled estimate showed that α-diversity was significantly reduced in patients with OCD compared with that in healthy controls (PShannon  = 0.00015). In addition, a statistically significant difference was observed in β-diversity between patients with OCD and healthy controls at the order (P = 0.012), family (P = 0.003), genus (P < 0.001), and species (P = 0.005) levels. In the microbiome composition, Pseudomonas, Caulobacteraceae (f), Streptococcus, Novosphingobium, and Enhydrobacter at the genus level were significantly less prevalent in patients with OCD than in controls. In addition, among patients with OCD, the microbial composition in the early-onset versus late-onset types was significantly different with respect to the genera Corynebacterium and Pelomonas.

CONCLUSION

The present study showed an aberrant microbiome in patients with OCD, suggesting a role of the microbiota-brain interaction in the pathophysiology of OCD. Further longitudinal studies with larger sample sizes adjusting for various confounders are warranted.

Gastrointestinal Dysbiosis in Neuro-Critically Ill Patients: A Systematic Review of Case-Control Studies

The human gastrointestinal tract (GIT) has a rich and pre-programmed microbiome. This microbiome is essential for physiological functions such as digestion, immunity, metabolism, and structural integrity, and of prime concern to us in conducting this study is the nervous system communication. This two-way communication between the GIT and central nervous system (CNS) is known as the gut-brain axis (GBA) and has implications for neurocritical disease. A change in any factor relating to this microbiome is known as gut dysbiosis; this can lead to aberrant communication through the GBA and in turn, can contribute to disease states. The primary objective of this study is to determine the cause-specific dysbiotic organisms in neuro-critically ill patients and their effects. We performed this study by searching published literature as per Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies that defined gastrointestinal dysbiosis in neuro-critically ill patients were retrieved using Boolean search from 2000 to 2023 via PubMed and Google Scholar and narrowed the results down to five prospective case-control studies. We performed their quality assessment. The results concluded that in neurocritical illnesses such as encephalitis, brain tumors, intracerebral hemorrhage, and ischemic stroke, fluctuations in specific microbiota correlated with disease severity and prognosis. Moreover, the inhabiting population of dysbiotic organisms in neuro-critically ill patients were different in different diseases and there were no similarities in the composition of gut microbiota in these diseases. Taking stroke patients as an example; increased Enterobacteriaceae and lower Lachnospiraceae microbiome levels were found in patients with a higher stroke dysbiosis index (SDI). Those patients who developed stroke-associated pneumonia (SAP) displayed higher levels of Enterococcus species. In conclusion, dysbiosis has a major effect on neuro-critically ill patients' disease states and dysbiotic organisms can be used as a biomarker for disease. Further prospective studies on this topic are warranted for potential neurological and prognostic correlations.