Brain-gut-microbe communication in health and disease

Gut microbiota: the indispensable player in neurodegenerative diseases

As one of the most urgent social and health problems in the world, neurodegenerative diseases have always been of interest to researchers. However, the pathological mechanisms and therapeutic approaches are not achieved. In addition to the established roles of oxidative stress, inflammation and immune response, changes of gut microbiota are also closely related to the pathogenesis of neurodegenerative diseases. Gut microbiota is the central player of the gut-brain axis, the dynamic bidirectional communication pathway between gut microbiota and central nervous system, and emerging insights have confirmed its indispensability in the development of neurodegenerative diseases. In this review, we discuss the complex relationship between gut microbiota and the central nervous system from the perspective of the gut-brain axis; review the mechanism of microbiota for the modulation different neurodegenerative diseases and discuss how different dietary patterns affect neurodegenerative diseases via gut microbiota; and prospect the employment of gut microbiota in the therapeutic approach to those diseases. © 2024 Society of Chemical Industry.

From microbes to mind: germ-free models in neuropsychiatric research

The gut-microbiota-brain axis refers to the bidirectional communication system between the gut, its microbial community, and the brain. This interaction involves a complex interplay of neural pathways, chemical transmitters, and immunological mechanisms. Germ-free animal models have been extensively employed to investigate gut-microbiota-brain interactions, significantly contributing to our current understanding of the role of intestinal microbes in brain function. However, despite the many benefits, this absence of microbiota is not futile. Germ-free animals present physiological and neurodevelopmental alterations that can persist even after reconstitution with normal microbiota. Therefore, the main goal of this minireview is to discuss how some of the inherent limitations of this model can interfere with the conclusion obtained when using these animals to study the complex nature of neuropsychiatric disorders. Furthermore, we examine the inclusion and use of antibiotic-based treatments as an alternative in the research of gut-brain interactions.

The Effect of Whole-Diet Interventions on Memory and Cognitive Function in Healthy Older Adults - A Systematic Review

An increasing number of cross-sectional studies suggests that diet may impact memory and cognition in healthy older adults. However, randomized controlled trials investigating the effects of whole-diet interventions on memory and cognition in healthy older adults are rather rare, and conflicting results are often reported. Therefore, a systematic review was conducted to compile the current evidence regarding the potential effects of whole-diet interventions on 1) memory and 2) other cognitive outcomes in older adults. Studies that reported on randomized controlled trials with dietary interventions in healthy older adults (≥60 y) were included. Studies utilizing supplements, single food items, or trials in specific patient groups (i.e., neurodegenerative diagnoses) were excluded. For the 23 included articles, the main outcomes examined fell into 1 or more of the following categories: cognitive task-based outcomes related to memory, other cognitive task-based outcomes, and additional outcomes related to cognitive function or disease risk. Three of the studies that investigated dietary interventions alone and 2 multidomain studies showed positive effects on memory function, whereas 5 multidomain interventions and 1 intervention that focused on diet alone showed positive effects on other cognitive outcomes. The effect of randomized, controlled whole-diet interventions on memory and cognitive function in healthy older adults is modest and inconclusive, highlighting the need for more well-designed, sufficiently powered studies. Furthermore, the potential mechanisms by which diet impacts cognition in healthy aging need to be elucidated. This systematic review is registered in PROSPERO as CRD42022329759.

Insights into the interplay between gut microbiota and lipid metabolism in the obesity management of canines and felines

Obesity is a prevalent chronic disease that has significant negative impacts on humans and our companion animals, including dogs and cats. Obesity occurs with multiple comorbidities, such as diabetes, hypertension, heart disease and osteoarthritis in dogs and cats. A direct link between lipid metabolism dysregulation and obesity-associated diseases has been implicated. However, the understanding of such pathophysiology in companion animals is limited. This review aims to address the role of lipid metabolism in various metabolic disorders associated with obesity, emphasizing the involvement of the gut microbiota. Furthermore, we also discuss the management of obesity, including approaches like nutritional interventions, thus providing novel insights into obesity prevention and treatment for canines and felines.

Changes in the gut microbiome of patients with esophageal cancer: A systematic review and meta-analysis based on 16S gene sequencing technology

BACKGROUND

Esophageal cancer (EC) possesses a high degree of malignancy and exhibits poor therapeutic outcomes and prognosis. However, its pathogenesis remains unclear. With the development of macrogene sequencing technology, changes in the intestinal flora have been found to be highly related to the development of EC, although discrepancies and controversies remain in this research area.

MATERIALS AND METHODS

We comprehensively searched the PubMed, EMBASE, and Cochrane's Central Controlled Trials Register and the Scientific Network's database search projects based on systematically reviewed preferred reporting projects and meta-analyses. We used Engauge Digitizer for data extraction and Stata 15.1 for data analysis. In addition, we used the Newcastle-Ottawa Scale for grade grading and forest and funnel plots, sensitivity, and Egger and Beggar tests to evaluate the risk of bias.

RESULTS

This study included 10 studies that assessed stool, tumor, and nontumor esophageal mucosa (gastroscopy and surgical resection) samples from 527 individuals, including 273 patients with EC and 254 healthy control group. We observed remarkable differences in microbial diversity in EC patients compared to healthy controls. The Chao1 index (46.01 vs. 42.67) was significantly increased in EC patients, whereas the Shannon index (14.90 vs. 19.05), ACE (39.24 vs. 58.47), and OTUs(28.93 vs. 70.10) were significantly lower. At the phylum level, the abundance of Bacteroidetes (37.89 vs. 32.77) increased significantly, whereas that of Firmicutes (37.63 vs. 38.72) decreased significantly; the abundance of Clostridium and Verruciformis increased, while that of Actinobacteria and Proteobacteria decreased to varying degrees. The abundance of Bacteroides (8.60 vs. 15.10) and Streptococcaceae (15.08 vs. 27.05) significantly reduced in EC.

CONCLUSIONS

According to our meta-analysis, in patients with EC, the Chao1 index increased, whereas the Shannon and the OTUs decreased. At the phylum level, the abundance of Firmicutes decreased significantly, whereas that of Bacteroidetes and Proteobacteria increased significantly. At the genus/family level, the abundance of Bacteroidaceae, Prevotellaceae and Streptococcaceae decreased significantly, whereas that of Veillonellaceae increased. This meta-analysis identified changes in gut microbiota in patients with EC; however, its conclusions were inconsistent.

New insights into the effects of serotonin on Parkinson's disease and depression through its role in the gastrointestinal tract

Neuropsychiatric and neurodegenerative disorders are frequently associated with gastrointestinal (GI) co-pathologies. Although the central and enteric nervous systems (CNS and ENS, respectively) have been studied separately, there is increasing interest in factors that may contribute to conditions affecting both systems. There is compelling evidence that serotonin (5-HT) may play an important role in several gut-brain disorders. It is well known that 5-HT is essential for the development and functioning of the CNS. However, most of the body's 5-HT is produced in the GI tract. A deeper understanding of the specific effects of enteric 5-HT on gut-brain disorders may provide the basis for the development of new therapeutic targets. This review summarizes current data focusing on the important role of 5-HT in ENS development and motility, with particular emphasis on novel aspects of 5-HT signaling in conditions where CNS and ENS comorbidities are common, such as Parkinson's disease and depressive disorders.

Overview of the Efficacy of Using Probiotics for Neurosurgical and Potential Neurosurgical Patients

This review delves into the emerging field of the gut microbiota-brain axis, emphasizing its bidirectional communication and implications for neurological health, particularly in trauma and neurosurgery. While disruptions in this axis can lead to dysbiosis and hinder neurological recovery, recent studies have highlighted the therapeutic potential of interventions like probiotics in targeting this axis. This review aims to focus on the efficacy of probiotic supplementation to support the gut microbiota-brain axis in trauma, neurosurgery, or pain based on the current clinical trials to assess the complex interplays among probiotics, the gut microbiota, and the central nervous system (CNS). This comprehensive literature review identified 10 relevant publications on probiotic interventions for various neurosurgical conditions across multiple countries. These studies demonstrated diverse outcomes, with significant improvements observed in gastrointestinal mobility, inflammatory responses, and infection rates, particularly in post-traumatic brain injury and spinal surgery. Probiotics also showed promise in mitigating antibiotic-associated diarrhea and modulating inflammatory cytokines. Despite the promising findings, the complex interplays among probiotics, the gut microbiota, and the central nervous system (CNS) call for cautious interpretation. Conflicting outcomes emphasize the need for better-designed trials to understand strain-specific and disease-specific effects accurately. In conclusion, probiotics offer a promising adjuvant therapy for neurosurgical patients, traumatic brain injuries, and post-spinal surgery. However, further well-designed randomized controlled trials are essential to elucidate the intricate relationship between microbiome-modulating interventions and the CNS via the gut microbiota-brain axis.

Faecal microbiota transplantation (FMT) in Norwegian outpatients with mild to severe myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): protocol for a 12-month randomised double-blind placebo-controlled trial

INTRODUCTION

The observed alteration of the intestinal microbiota in patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and the effect of transferring a healthy gut flora from a faecal donor using a faecal microbiota transplantation (FMT) will be explored in this trial.

METHODS AND ANALYSIS

This is a protocol for a randomised, double-blind, placebo-controlled, parallel-group, single-centre trial, with 12 months follow-up. 80 participants will be included and randomised (1:1:2) to either donor FMT (from two different donors) or placebo (autologous FMT). Participants will be included by the International Clinical Criteria for ME/CFS. The clinical measures of ME/CFS and disease activity include Modified DePaul Questionnaire, Fatigue Severity Scale (FSS), Hospital Anxiety and Depression Scale (HADS), 36-Item Short Form Health Survey (SF-36), ROMA IV criteria, Food Frequency Questionnaire, Repeatable Battery for the Assessment of Neuropsychological Status, heart rate variability testing and reports on the use of antibiotics and food supplements, as well as biobanking of blood, urine and faeces.The primary endpoint is proportion with treatment success in FSS score in donor versus autologous FMT group 3 months after treatment. Treatment success is defined as an FSS improvement of more than 1.2 points from baseline at 3 months after treatment. Adverse events will be registered throughout the study.

ETHICS AND DISSEMINATION

The Regional Committee for Medical Research Ethics Northern Norway has approved the study. The study has commenced in May 2019. Findings will be disseminated in international peer-reviewed journal(s), submitted to relevant conferences, and trial participants will be informed via phone calls.

TRIAL REGISTRATION NUMBER

NCT03691987.

Causal links between gut microbiomes, cytokines and risk of different subtypes of epilepsy: a Mendelian randomization study

Objective

Recent research suggests a potential link between the gut microbiome (GM) and epilepsy. We undertook a Mendelian randomization (MR) study to determine the possible causal influence of GM on epilepsy and its various subtypes, and explore whether cytokines act as mediators.

Methods

We utilized Genome-Wide Association Study (GWAS) summary statistics to examine the causal relationships between GM, cytokines, and four epilepsy subtypes. Furthermore, we assessed whether cytokines mediate the relationship between GM and epilepsy. Significant GMs were further investigated using transcriptomic MR analysis with genes mapped from the FUMA GWAS. Sensitivity analyses and reverse MR were conducted for validation, and false discovery rate (FDR) correction was applied for multiple comparisons.

Results

We pinpointed causal relationships between 30 GMs and various epilepsy subtypes. Notably, the Family Veillonellaceae (OR:1.03, 95%CI:1.02-1.05, p = 0.0003) consistently showed a strong positive association with child absence epilepsy, and this causal association endured even after FDR correction (p-FDR < 0.05). Seven cytokines were significantly associated with epilepsy and its subtypes. A mediating role for cytokines has not been demonstrated. Sensitivity tests validated the primary MR analysis outcomes. Additionally, no reverse causality was detected between significant GMs and epilepsy. Of the mapped genes of notable GMs, genes like BLK, FDFT1, DOK2, FAM167A, ZSCAN9, RNGTT, RBM47, DNAJC21, SUMF1, TCF20, GLO1, TMTC1, VAV2, and RNF14 exhibited a profound correlation with the risk factors of epilepsy subtypes.

Conclusion

Our research validates the causal role of GMs and cytokines in various epilepsy subtypes, and there has been no evidence that cytokines play a mediating role between GM and epilepsy. This could provide fresh perspectives for the prevention and treatment of epilepsy.

The Emerging Role of Human Gut Bacteria Extracellular Vesicles in Mental Disorders and Developing New Pharmaceuticals

In recent years, further evidence has emerged regarding the involvement of extracellular vesicles in various human physiopathological conditions such as Alzheimer's disease, Parkinson's disease, irritable bowel syndrome, and mental disorders. The biogenesis and cargo of such vesicles may reveal their impact on human health nd disease and set the underpinnings for the development of novel chemical compounds and pharmaceuticals. In this review, we examine the link between bacteria-derived exosomes in the gastrointestinal tract and mental disorders, such as depression and anxiety disorders. Crucially, we focus on whether changes in the gut environment affect the human mental state or the other way around. Furthermore, the possibility of handling bacteria-derived exosomes as vectors of chemicals to treat such conditions is examined.

Mood disturbance, but not overall diet quality, is associated with fecal microbiome diversity in free-living adults

OBJECTIVES

To investigate the gut-brain axis, we explored the relationships among mood disturbance (MD), diet quality (DQ), and fecal microbiota in free-living adults.

METHODS

A cross-sectional analysis was conducted with data from 75 healthy adults enrolled in two studies. Anthropometrics, 16s rRNA gene sequencing of fecal microbes, DQ as assessed by Healthy Eating Index-2015 (HEI), and MD determined by Profile of Mood States (POMS) were included. Alpha-diversity and DQ differences were explored between low (n = 37) and high MD (n = 38) groups. Spearman correlations were used to investigate relationships between alpha-diversity, DQ, and POMS subscales. Moderation analysis explored the effect of HEI score on the relationship between MD and alpha-diversity.

RESULTS

Participants were mostly white (67%), 54.5 years old (±11.8), and overweight (28.5 ± 6.5 kg/m2). Shannon and Simpson indices indicate higher alpha-diversity in participants with low MD compared to high MD (p = 0.004 and p = 0.008, respectively). Simpson and Shannon indices were correlated with subscale of anger (rho = -0.303, p = 0.011; rho = -0.265, p = 0.027, respectively)and total MD (rho = -0.404, p = 0.001; rho = -0.357, p = 0.002, respectively). Refined grains were associated with fatigue and tension subscales (rho = 0.428, p < 0.001; rho = 0.302, p = 0.014, respectively). DQ did not significantly moderate the relationship between alpha-diversity and mood disturbance (F(7, 53) = 2.00, p = 0.072, R2 = 0.209). Shannon index was a significant predictor of MD (b = -4.39, t(53) = -2.55, p = 0.014), but total HEI score and the interaction (Shannon index*HEI score) were not significant.

DISCUSSION

Greater bacterial diversity was associated with lower MD, and DQ was associated with various mood state subscales in this sample of adults.

Nanovesicular Mediation of the Gut-Brain Axis by Probiotics: Insights into Irritable Bowel Syndrome

BACKGROUND

Dysbiosis, influenced by poor diet or stress, is associated with various systemic diseases. Probiotic supplements are recognized for stabilizing gut microbiota and alleviating gastrointestinal issues, like irritable bowel syndrome (IBS). This study focused on the tryptophan pathways, which are important for the regulation of serotonin levels, and on host physiology and behavior regulation.

METHODS

Nanovesicles were isolated from the plasma of subjects with chronic diarrhea, both before and after 60 days of consuming a probiotic mix (Acronelle®, Bromatech S.r.l., Milan, Italy). These nanovesicles were assessed for the presence of Tryptophan 2,3-dioxygenase 2 (TDO 2). Furthermore, the probiotics mix, in combination with H2O2, was used to treat HT29 cells to explore its cytoprotective and anti-stress effect.

RESULTS

In vivo, levels of TDO 2 in nanovesicles were enhanced in the blood after probiotic treatment, suggesting a role in the gut-brain axis. In the in vitro model, a typical H2O2-induced stress effect occurred, which the probiotics mix was able to recover, showing a cytoprotective effect. The probiotics mix treatment significantly reduced the heat shock protein 60 kDa levels and was able to preserve intestinal integrity and barrier function by restoring the expression and redistribution of tight junction proteins. Moreover, the probiotics mix increased the expression of TDO 2 and serotonin receptors.

CONCLUSIONS

This study provides evidence for the gut-brain axis mediation by nanovesicles, influencing central nervous system function.

A Stress Reduction Intervention for Lactating Mothers Alters Maternal Gut, Breast Milk, and Infant Gut Microbiomes: Data from a Randomized Controlled Trial

BACKGROUND

This secondary analysis of data from a randomized controlled trial (RCT) investigated how the maternal gut, breast milk, and infant gut microbiomes may contribute to the effects of a relaxation intervention, which reduced maternal stress and promoted infant weight gain.

METHODS

An RCT was undertaken in healthy Chinese primiparous mother-infant pairs (340/7-376/7gestation weeks). Mothers were randomly allocated to either the intervention group (IG, listening to relaxation meditation) or the control group (CG). Outcomes were the differences in microbiome composition and the diversity in the maternal gut, breast milk, and infant gut at 1 (baseline) and 8 weeks (post-intervention) between IG and CG, assessed using 16S rRNA gene amplicon sequencing of fecal and breastmilk samples.

RESULTS

In total, 38 mother-infant pairs were included in this analysis (IG = 19, CG = 19). The overall microbiome community structure in the maternal gut was significantly different between the IG and CG at 1 week, with the difference being more significant at 8 weeks (Bray-Curtis distance R2 = 0.04 vs. R2 = 0.13). Post-intervention, a significantly lower α-diversity was observed in IG breast milk (observed features: CG = 295 vs. IG = 255, p = 0.032); the Bifidobacterium genera presented a higher relative abundance. A significantly higher α-diversity was observed in IG infant gut (observed features: CG = 73 vs. IG = 113, p < 0.001).

CONCLUSIONS

The findings were consistent with the hypothesis that the microbiome might mediate observed relaxation intervention effects via gut-brain axis and entero-mammary pathways; but confirmation is required.

A microfluidic chip for sustained oxygen gradient formation in the intestine ex vivo

The oxygen gradient across the intestine influences intestinal physiology and the microbial environment of the microbiome. The microbiome releases metabolites that communicate with enterochromaffin cells, neuronal cells, and resident immune cells to facilitate the bidirectional communication across the gut-brain axis. Measuring communication between various cell types within the intestine could provide essential information about key regulators of gut and brain health; however, the microbial environment of the intestine is heavily dependent on the physiological oxygen gradient that exists across the intestinal wall. Likewise, there exist a need for methods which enable real-time monitoring of intestinal signaling ex vivo yet this remains challenging due to the inability to adequately culture intestinal tissue ex vivo while also exposing the appropriate locations of the intestine for probe insertion and monitoring. Here, we designed and fabricated a 3D printed microfluidic device to maintain the oxygen gradient across precision cut murine intestinal slices with the capability to couple to external neurochemical recording techniques. The gradient is maintained from outlets below while allowing access to the slice from above for detection with fast scan cyclic voltammetry (FSCV) and carbon-fiber microelectrodes. A series of 11 outlet ports were designed to lay underneath the slice which were connected to channels to deliver oxygenated vs. deoxygenated media. Outlet ports were designed in an oval shape where deoxygenated media was delivered to the center of the slice and oxygenated media is delivered to the outer portion of the slice to mimic the location of oxygen across the intestine. An oxygen sensitive fluorescent dye, tris(2,2'-bipyridyl)dichlororuthenium(II), was used to characterize the tunability of the gradient. Viability of the tissue was confirmed by both fluorescence microscopy and FSCV. Additionally, we measured simultaneous serotonin and melatonin signaling with FSCV in the intestine for the first time. Overall, this chip provides a significant advance in our ability to culture intestinal slices ex vivo with the added benefit of direct access for measurements and imaging.

Influence of the brain‑gut axis on neuroinflammation in cerebral ischemia‑reperfusion injury (Review)

Stroke, a debilitating cerebrovascular ailment, poses significant threats to human life and health. The intricate interplay between the gut‑brain‑microbiota axis (GBMA) and cerebral ischemia‑reperfusion has increasingly become a focal point of scientific exploration, emerging as a pivotal research avenue in stroke pathophysiology. In the present review, the authors delved into the nexus between the GBMA and neuroinflammation observed post‑stroke. The analysis underscored the pivotal roles of histone deacetylase 3 and neutrophil extracellular traps subsequent to stroke incidents. The influence of gut microbial compositions and their metabolites, notably short‑chain fatty acids and trimethylamine N‑oxide, on neuroinflammatory processes, was further elucidated. The involvement of immune cells, especially regulatory T‑cells, and the intricate signaling cascades including cyclic GMP‑AMP synthase/stimulator of interferon genes/Toll‑like receptor, further emphasized the complex regulatory mechanisms of GBMA in cerebral ischemia/reperfusion injury (CI/RI). Collectively, the present review offered a comprehensive perspective on the metabolic, immune and inflammatory modulations orchestrated by GBMA, augmenting the understanding of its role in neuroinflammation following CI/RI.

Probiotic-fermented edible herbs as functional foods: A review of current status, challenges, and strategies

Recently, consumers have become increasingly interested in natural, health-promoting, and chronic disease-preventing medicine and food homology (MFH). There has been accumulating evidence that many herbal medicines, including MFH, are biologically active due to their biotransformation through the intestinal microbiota. The emphasis of scientific investigation has moved from the functionally active role of MFH to the more subtle role of biotransformation of the active ingredients in probiotic-fermented MFH and their health benefits. This review provides an overview of the current status of research on probiotic-fermented MFH. Probiotics degrade toxins and anti-nutritional factors in MFH, improve the flavor of MFH, and increase its bioactive components through their transformative effects. Moreover, MFH can provide a material base for the growth of probiotics and promote the production of their metabolites. In addition, the health benefits of probiotic-fermented MFH in recent years, including antimicrobial, antioxidant, anti-inflammatory, anti-neurodegenerative, skin-protective, and gut microbiome-modulating effects, are summarized, and the health risks associated with them are also described. Finally, the future development of probiotic-fermented MFH is prospected in combination with modern development technologies, such as high-throughput screening technology, synthetic biology technology, and database construction technology. Overall, probiotic-fermented MFH has the potential to be used in functional food for preventing and improving people's health. In the future, personalized functional foods can be expected based on synthetic biology technology and a database on the functional role of probiotic-fermented MFH.

Effect of gut microbiome modulation on muscle function and cognition: the PROMOTe randomised controlled trial

Studies suggest that inducing gut microbiota changes may alter both muscle physiology and cognitive behaviour. Gut microbiota may play a role in both anabolic resistance of older muscle, and cognition. In this placebo controlled double blinded randomised controlled trial of 36 twin pairs (72 individuals), aged ≥60, each twin pair are block randomised to receive either placebo or prebiotic daily for 12 weeks. Resistance exercise and branched chain amino acid (BCAA) supplementation is prescribed to all participants. Outcomes are physical function and cognition. The trial is carried out remotely using video visits, online questionnaires and cognitive testing, and posting of equipment and biological samples. The prebiotic supplement is well tolerated and results in a changed gut microbiome [e.g., increased relative Bifidobacterium abundance]. There is no significant difference between prebiotic and placebo for the primary outcome of chair rise time (β = 0.579; 95% CI -1.080-2.239 p = 0.494). The prebiotic improves cognition (factor score versus placebo (β = -0.482; 95% CI,-0.813, -0.141; p = 0.014)). Our results demonstrate that cheap and readily available gut microbiome interventions may improve cognition in our ageing population. We illustrate the feasibility of remotely delivered trials for older people, which could reduce under-representation of older people in clinical trials. ClinicalTrials.gov registration: NCT04309292.

Probiotics' Effects in the Treatment of Anxiety and Depression: A Comprehensive Review of 2014-2023 Clinical Trials

Changes in the gut microbiome can affect cognitive and psychological functions via the microbiota-gut-brain (MGB) axis. Probiotic supplements are thought to have largely positive effects on mental health when taken in sufficient amounts; however, despite extensive research having been conducted, there is a lack of consistent findings on the effects of probiotics on anxiety and depression and the associated microbiome alterations. The aim of our study is to systematically review the most recent literature of the last 10 years in order to clarify whether probiotics could actually improve depression and anxiety symptoms. Our results indicate that the majority of the most recent literature suggests a beneficial role of probiotics in the treatment of depression and anxiety, despite the existence of a substantial number of less positive findings. Given probiotics' potential to offer novel, personalized treatment options for mood disorders, further, better targeted research in psychiatric populations is needed to address concerns about the exact mechanisms of probiotics, dosing, timing of treatment, and possible differences in outcomes depending on the severity of anxiety and depression.

Effect of gut microbiota-derived metabolites and extracellular vesicles on neurodegenerative disease in a gut-brain axis chip

A new perspective suggests that a dynamic bidirectional communication system, often referred to as the microbiome-gut-brain axis, exists among the gut, its microbiome, and the central nervous system (CNS). This system may influence brain health and various brain-related diseases, especially in the realms of neurodevelopmental and neurodegenerative conditions. However, the exact mechanism is not yet understood. Metabolites or extracellular vesicles derived from microbes in the gut have the capacity to traverse the intestinal epithelial barrier or blood-brain barrier, gaining access to the systemic circulation. This phenomenon can initiate the physiological responses that directly or indirectly impact the CNS and its function. However, reliable and controllable tools are required to demonstrate the causal effects of gut microbial-derived substances on neurogenesis and neurodegenerative diseases. The integration of microfluidics enhances scientific research by providing advanced in vitro engineering models. In this study, we investigated the impact of microbe-derived metabolites and exosomes on neurodevelopment and neurodegenerative disorders using human induced pluripotent stem cells (iPSCs)-derived neurons in a gut-brain axis chip. While strain-specific, our findings indicate that both microbial-derived metabolites and exosomes exert the significant effects on neural growth, maturation, and synaptic plasticity. Therefore, our results suggest that metabolites and exosomes derived from microbes hold promise as potential candidates and strategies for addressing neurodevelopmental and neurodegenerative disorders.

Mood and microbes: a comprehensive review of intestinal microbiota's impact on depression

Depression is considered a multifaceted and intricate mental disorder of growing concern due to its significant impact on global health issues. The human gut microbiota, also known as the "second brain," has an important role in the CNS by regulating it through chemical, immunological, hormonal, and neurological processes. Various studies have found a significant bidirectional link between the brain and the gut, emphasizing the onset of depression therapies. The biological and molecular processes underlying depression and microbiota are required, as the bidirectional association may represent a novel study. However, profound insights into the stratification and diversity of the gut microbiota are still uncommon. This article investigates the emerging evidence of a bacterial relationship between the gut and the brain's neurological system and its potential pathogenicity and relevance. The interplay of microbiota, immune system, nervous system neurotransmitter synthesis, and neuroplasticity transitions is also widely studied. The consequences of stress, dietary fibers, probiotics, prebiotics, and antibiotics on the GB axis are being studied. Multiple studies revealed the processes underlying this axis and led to the development of effective microbiota-based drugs for both prevention and treatment. Therefore, the results support the hypothesis that gut microbiota influences depression and provide a promising area of research for an improved knowledge of the etiology of the disease and future therapies.

What we need to know about the germ-free animal models

The gut microbiota (GM), as a forgotten organ, refers to the microbial community that resides in the gastrointestinal tract and plays a critical role in a variety of physiological activities in different body organs. The GM affects its targets through neurological, metabolic, immune, and endocrine pathways. The GM is a dynamic system for which exogenous and endogenous factors have negative or positive effects on its density and composition. Since the mid-twentieth century, laboratory animals are known as the major tools for preclinical research; however, each model has its own limitations. So far, two main models have been used to explore the effects of the GM under normal and abnormal conditions: the isolated germ-free and antibiotic-treated models. Both methods have strengths and weaknesses. In many fields of host-microbe interactions, research on these animal models are known as appropriate experimental subjects that enable investigators to directly assess the role of the microbiota on all features of physiology. These animal models present biological model systems to either study outcomes of the absence of microbes, or to verify the effects of colonization with specific and known microbial species. This paper reviews these current approaches and gives advantages and disadvantages of both models.

A Combinational Therapy for Preventing and Delaying the Onset of Alzheimer's Disease: A Focus on Probiotic and Vitamin Co-Supplementation

Alzheimer's disease is a progressive neurodegenerative disorder with a complex etiology, and effective interventions to prevent or delay its onset remain a global health challenge. In recent years, there has been growing interest in the potential role of probiotic and vitamin supplementation as complementary strategies for Alzheimer's disease prevention. This review paper explores the current scientific literature on the use of probiotics and vitamins, particularly vitamin A, D, E, K, and B-complex vitamins, in the context of Alzheimer's disease prevention and management. We delve into the mechanisms through which probiotics may modulate gut-brain interactions and neuroinflammation while vitamins play crucial roles in neuronal health and cognitive function. The paper also examines the collective impact of this combinational therapy on reducing the risk factors associated with Alzheimer's disease, such as oxidative stress, inflammation, and gut dysbiosis. By providing a comprehensive overview of the existing evidence and potential mechanisms, this review aims to shed light on the promise of probiotic and vitamin co-supplementation as a multifaceted approach to combat Alzheimer's disease, offering insights into possible avenues for future research and clinical application.

Metabolic Insights into Caffeine's Anti-Adipogenic Effects: An Exploration through Intestinal Microbiota Modulation in Obesity

Obesity, a chronic condition marked by the excessive accumulation of adipose tissue, not only affects individual well-being but also significantly inflates healthcare costs. The physiological excess of fat manifests as triglyceride (TG) deposition within adipose tissue, with white adipose tissue (WAT) expansion via adipocyte hyperplasia being a key adipogenesis mechanism. As efforts intensify to address this global health crisis, understanding the complex interplay of contributing factors becomes critical for effective public health interventions and improved patient outcomes. In this context, gut microbiota-derived metabolites play an important role in orchestrating obesity modulation. Microbial lipopolysaccharides (LPS), secondary bile acids (BA), short-chain fatty acids (SCFAs), and trimethylamine (TMA) are the main intestinal metabolites in dyslipidemic states. Emerging evidence highlights the microbiota's substantial role in influencing host metabolism and subsequent health outcomes, presenting new avenues for therapeutic strategies, including polyphenol-based manipulations of these microbial populations. Among various agents, caffeine emerges as a potent modulator of metabolic pathways, exhibiting anti-inflammatory, antioxidant, and obesity-mitigating properties. Notably, caffeine's anti-adipogenic potential, attributed to the downregulation of key adipogenesis regulators, has been established. Recent findings further indicate that caffeine's influence on obesity may be mediated through alterations in the gut microbiota and its metabolic byproducts. Therefore, the present review summarizes the anti-adipogenic effect of caffeine in modulating obesity through the intestinal microbiota and its metabolites.

Associations between impulsivity and fecal microbiota in individuals abstaining from methamphetamine

INTRODUCTION

Methamphetamine (MA) abuse is a major public problem, and impulsivity is both a prominent risk factor and a consequence of addiction. Hence, clarifying the biological mechanism of impulsivity may facilitate the understanding of addiction to MA. The microbiota-gut-brain axis was suggested to underlie a biological mechanism of impulsivity induced by MA.

METHODS

We therefore recruited 62 MA addicts and 50 healthy controls (HCs) to investigate the alterations in impulsivity and fecal microbiota and the associations between them in the MA group. Thereafter, 25 MA abusers who abstained from MA for less than 3 months were followed up for 2 months to investigate the relationship between impulsivity and microbiota as abstinence became longer. 16S rRNA sequencing was conducted for microbiota identification.

RESULTS

Elevated impulsivity and dysbiosis characterized by an increase in opportunistic pathogens and a decrease in probiotics were identified in MA abusers, and both the increased impulsivity and disrupted microbiota tended to recover after longer abstinence from MA. Impulsivity was related to microbiota, and the effect of MA abuse on impulsivity was mediated by microbiota.

CONCLUSION

Our findings potentially highlighted the importance of abstention and implicated the significant role of the microbiota-gut-brain axis in the interrelationship between microbiota and behaviors, as well as the potential of microbiota as a target for intervention of impulsivity.

A comprehensive diversity analysis on the gut microbiomes of ASD patients: from alpha, beta to gamma diversities

Autism spectrum disorder (ASD) is estimated to influence as many as 1% children worldwide, but its etiology is still unclear. It has been suggested that gut microbiomes play an important role in regulating abnormal behaviors associated with ASD. A de facto standard analysis on the microbiome-associated diseases has been diversity analysis, and nevertheless, existing studies on ASD-microbiome relationship have not produced a consensus. Here, we perform a comprehensive analysis of the diversity changes associated with ASD involving alpha-, beta-, and gamma-diversity metrics, based on 8 published data sets consisting of 898 ASD samples and 467 healthy controls (HC) from 16S-rRNA sequencing. Our findings include: (i) In terms of alpha-diversity, in approximately 1/3 of the studies cases, ASD patients exhibited significantly higher alpha-diversity than the HC, which seems to be consistent with the "1/3 conjecture" of diversity-disease relationship (DDR). (ii) In terms of beta-diversity, the AKP (Anna Karenina principle) that predict all healthy microbiomes should be similar, and every diseased microbiome should be dissimilar in its own way seems to be true in approximately 1/2 to 3/4 studies cases. (iii) In terms of gamma-diversity, the DAR (diversity-area relationship) modeling suggests that ASD patients seem to have large diversity-area scaling parameter than the HC, which is consistent with the AKP results. However, the MAD (maximum accrual diversity) and RIP (ratio of individual to population diversity) parameters did not suggest significant differences between ASD patients and HC. Throughout the study, we adopted Hill numbers to measure diversity, which stratified the diversity measures in terms of the rarity-commonness-dominance spectrum. It appears that the differences between ASD patients and HC are more propounding on rare-species side than on dominant-species side. Finally, we discuss the apparent inconsistent diversity-ASD relationships among different case studies and postulate that the relationships are not monotonic.

Lactiplantibacillus plantarum X7022 Plays Roles on Aging Mice with Memory Impairment Induced by D-Galactose Through Restoring Neuronal Damage, Relieving Inflammation and Oxidative Stress

In this study, Lactiplantibacillus plantarum X7022 was applied to ameliorate memory impairment of aging mice induced by D-galactose. The strain showed specific choloylglycine hydrolysis ability based on in vitro investigation. Morris water maze test showed L. plantarum X7022 administration improved learning ability and spatial memory of aging mice. The gavage of L. plantarum X7022 displayed a promising ability of relieving cerebral oxidative stress and hippocampal inflammatory condition according to the increased GSH level and SOD activity and decreased MDA level, as well as decreased TNF-α, IL-1β, and IL-6 levels. The intervention with the strain could protect neuron by regulating cell apoptosis and AChE overexpression and inhibiting amyloid-β deposition, as well as affect neuron functions by regulating CREB-BDNF signaling pathways and iNOS expression. Besides, the strain could improve fecal SCFA contents and increase the abundance of anti-inflammatory and antioxidant-related genera such as Lactobacillus, Akkermansia, and Adlercreutzia. These results suggest that L. plantarum X7022 could be a prospective therapeutic alternative for the improvement of memory impairment among the elderly.

Helicobacter pylori infection and Parkinson's Disease: etiology, pathogenesis and levodopa bioavailability

Parkinson's disease (PD), a neurodegenerative disorder with an unknown etiology, is primarily characterized by the degeneration of dopamine (DA) neurons. The prevalence of PD has experienced a significant surge in recent years. The unidentified etiology poses limitations to the development of effective therapeutic interventions for this condition. Helicobacter pylori (H. pylori) infection has affected approximately half of the global population. Mounting evidences suggest that H. pylori infection plays an important role in PD through various mechanisms. The autotoxin produced by H. pylori induces pro-inflammatory cytokines release, thereby facilitating the occurrence of central inflammation that leads to neuronal damage. Simultaneously, H. pylori disrupts the equilibrium of gastrointestinal microbiota with an overgrowth of bacteria in the small intestinal known as small intestinal bacterial overgrowth (SIBO). This dysbiosis of the gut flora influences the central nervous system (CNS) through microbiome-gut-brain axis. Moreover, SIBO hampers levodopa absorption and affects its therapeutic efficacy in the treatment of PD. Also, H. pylori promotes the production of defensins to regulate the permeability of the blood-brain barrier, facilitating the entry of harmful factors into the CNS. In addition, H. pylori has been found to induce gastroparesis, resulting in a prolonged transit time for levodopa to reach the small intestine. H. pylori may exploit levodopa to facilitate its own growth and proliferation, or it can inflict damage to the gastrointestinal mucosa, leading to gastrointestinal ulcers and impeding levodopa absorption. Here, this review focused on the role of H. pylori infection in PD from etiology, pathogenesis to levodopa bioavailability.

Probiotics Show Promise as a Novel Natural Treatment for Neurological Disorders

Probiotics are beneficial microorganisms shown to improve human health when consumed regularly and in sufficient quantities. Numerous health benefits can be attained by possessing important metabolites with nutritional and medicinal qualities. It has been shown through scientific research that these living microbial consortiums can influence a variety of mental health outcomes, including but not limited to anxiety, depression, cognitive processes, stress responses, and behavioral patterns. Selected strains of bacteria and yeasts control how the central nervous system (CNS) communicates with the gut-brain axis (GBA) through neuronal, humoral, and metabolic pathways to ease mood. Psychobiotics are substances that can affect the digestive system as well as mood and anxiety. There is scant evidence to validate the beneficial effects of psychiatric drugs in treating neurological diseases or disorders. The therapeutic method of research into psychobiotics opens exciting prospects for the future of the field of development. This review compiles the current evidence available in the scientific literature on the use of probiotics to influence neurological disorders.

Chronic Stress Exposure Alters the Gut Barrier: Sex-Specific Effects on Microbiota and Jejunum Tight Junctions

Background

Major depressive disorder (MDD) is the leading cause of disability worldwide. Of individuals with MDD, 30% to 50% are unresponsive to common antidepressants, highlighting untapped causal biological mechanisms. Dysfunction in the microbiota-gut-brain axis has been implicated in MDD pathogenesis. Exposure to chronic stress disrupts blood-brain barrier integrity; still, little is known about intestinal barrier function in these conditions, particularly for the small intestine, where absorption of most foods and drugs takes place.

Methods

We investigated how chronic social or variable stress, two mouse models of depression, impact the jejunum intestinal barrier in males and females. Mice were subjected to stress paradigms followed by analysis of gene expression profiles of intestinal barrier-related targets, fecal microbial composition, and blood-based markers.

Results

Altered microbial populations and changes in gene expression of jejunum tight junctions were observed depending on the type and duration of stress, with sex-specific effects. We used machine learning to characterize in detail morphological tight junction properties, identifying a cluster of ruffled junctions in stressed animals. Junctional ruffling is associated with inflammation, so we evaluated whether lipopolysaccharide injection recapitulates stress-induced changes in the jejunum and observed profound sex differences. Finally, lipopolysaccharide-binding protein, a marker of gut barrier leakiness, was associated with stress vulnerability in mice, and translational value was confirmed on blood samples from women with MDD.

Conclusions

Our results provide evidence that chronic stress disrupts intestinal barrier homeostasis in conjunction with the manifestation of depressive-like behaviors in a sex-specific manner in mice and, possibly, in human depression.

Bridging the Mind and Gut: Uncovering the Intricacies of Neurotransmitters, Neuropeptides, and their Influence on Neuropsychiatric Disorders

BACKGROUND

The gut-brain axis (GBA) is a bidirectional signaling channel that facilitates communication between the gastrointestinal tract and the brain. Recent research on the gut-brain axis demonstrates that this connection enables the brain to influence gut function, which in turn influences the brain and its cognitive functioning. It is well established that malfunctioning of this axis adversely affects both systems' ability to operate effectively.

OBJECTIVE

Dysfunctions in the GBA have been associated with disorders of gut motility and permeability, intestinal inflammation, indigestion, constipation, diarrhea, IBS, and IBD, as well as neuropsychiatric and neurodegenerative disorders like depression, anxiety, schizophrenia, autism, Alzheimer's, and Parkinson's disease. Multiple research initiatives have shown that the gut microbiota, in particular, plays a crucial role in the GBA by participating in the regulation of a number of key neurochemicals that are known to have significant effects on the mental and physical well-being of an individual.

METHODS

Several studies have investigated the relationship between neuropsychiatric disorders and imbalances or disturbances in the metabolism of neurochemicals, often leading to concomitant gastrointestinal issues and modifications in gut flora composition. The interaction between neurological diseases and gut microbiota has been a focal point within this research. The novel therapeutic interventions in neuropsychiatric conditions involving interventions such as probiotics, prebiotics, and dietary modifications are outlined in this review.

RESULTS

The findings of multiple studies carried out on mice show that modulating and monitoring gut microbiota can help treat symptoms of such diseases, which raises the possibility of the use of probiotics, prebiotics, and even dietary changes as part of a new treatment strategy for neuropsychiatric disorders and their symptoms.

CONCLUSION

The bidirectional communication between the gut and the brain through the gut-brain axis has revealed profound implications for both gastrointestinal and neurological health. Malfunctions in this axis have been connected to a range of disorders affecting gut function as well as cognitive and neuropsychiatric well-being. The emerging understanding of the role of gut microbiota in regulating key neurochemicals opens up possibilities for novel treatment approaches for conditions like depression, anxiety, and neurodegenerative diseases.

Gut microbiota in women: The secret of psychological and physical well-being

The gut microbiota works in unison with the host, promoting its health. In particular, it has been shown to exert protective, metabolic and structural functions. Recent evidence has revealed the influence of the gut microbiota on other organs such as the central nervous system, cardiovascular and the endocrine-metabolic systems and the digestive system. The study of the gut microbiota is outlining new and broader frontiers every day and holds enormous innovation potential for the medical and pharmaceutical fields. Prevention and treatment of specific women's diseases involves the need to deepen the function of the gut as a junction organ where certain positive bacteria can be very beneficial to health. The gut microbiota is unique and dynamic at the same time, subject to external factors that can change it, and is capable of modulating itself at different stages of a woman's life, playing an important role that arises from the intertwining of biological mechanisms between the microbiota and the female genital system. The gut microbiota could play a key role in personalized medicine.

Integration of microbiota and metabolomics reveals the analgesic mechanisms of emodin against neuropathic pain

BACKGROUND AND OBJECTIVE

Neuropathic pain (NeP) induced dysbiosis of intestinal microbiota in chronic constriction injury (CCI) rats. Emodin has analgesic effect but the detailed mechanism is not clear at the present time. This study aims to explore the underling mechanism of action of emodin against NeP with in CCI model.

METHODS

Male SD rats (180-220 g) were randomly divided into three groups: sham group, CCI group, and emodin group. Behavioral tests were performed to evaluate the therapeutic effects of emodin on CCI model. Feces and spinal cords of all rats were collected 15 days after surgery. 16S rDNA sequencing, untargeted metabolomics, qPCR and ELISA were performed.

RESULTS

Mechanical withdrawal thresholds (MWT), thermal withdrawal latency (TWL) and Sciatic functional index (SFI) in emodin group were significantly higher than CCI group (P < 0.05). Emodin not only inhibited the expression of pro-inflammatory cytokines in the spinal cords and colonic tissue, but also increased the expression of tight junction protein in colonic tissue. 16S rDNA sequencing showed that emodin treatment changed the community structure of intestinal microbiota in CCI rats. Untargeted metabolomics analysis showed that 33 differential metabolites were screened out between CCI group and emodin group. After verification, we found that emodin increased the level of S-adenosylmethionine (SAM) and Histamine in the spinal cord of CCI rats.

CONCLUSION

Emodin was effective in relieving neuropathic pain, which is linked to inhibition inflammatory response, increasing the proportion of beneficial bacteria and beneficial metabolites.

Lactiplantibacillus plantarum as a promising adjuvant for neurological disorders therapy through the brain-gut axis and related action pathways

Dysbiosis in neurological disorders has highlighted the gut-microbiota-brain axis and psychobiotics and their ability to act on the brain-gut axis. Studying and discovering new approaches in therapies for neuropsychiatric disorders are strategies that have been discussed and put into practice. Lactiplantibacillus plantarum is a lactic acid bacteria species with an extensive history of safe use whose action as a psychobiotic has been successfully explored. This review describes and discusses the mechanisms of action of L. plantarum and its potential for the prevention and treatment of neurological disorders. Randomized and controlled trials in humans or animals and using supplements based on different strains of L. plantarum were selected. The psychobiotic effect of L. plantarum has been shown, mainly through its action on the Hypothalamic-Pituitary-Adrenal (HPA) axis and regulation of levels of pro-inflammatory cytokines. Furthermore, it could protect the integrity of the intestinal barrier and decrease inflammation, alleviating a series of symptoms of neurological diseases. The results showed improvements in cognitive function, memory, anxiety, hyperactivity, Attention Deficit Hyperactivity Disorder (ADHD), sleep quality, and growth stimulation of beneficial species of bacteria in the gut. Larger and deeper studies are needed to use psychobiotics to prevent and treat neurological disorders.

Identification of intestinal and fecal microbial biomarkers using a porcine social stress model

Understanding the relationships between social stress and the gastrointestinal microbiota, and how they influence host health and performance is expected to have many scientific and commercial implementations in different species, including identification and improvement of challenges to animal welfare and health. In particular, the study of the stress impact on the gastrointestinal microbiota of pigs may be of interest as a model for human health. A porcine stress model based on repeated regrouping and reduced space allowance during the last 4 weeks of the finishing period was developed to identify stress-induced changes in the gut microbiome composition. The application of the porcine stress model resulted in a significant increase in salivary cortisol concentration over the course of the trial and decreased growth performance and appetite. The applied social stress resulted in 32 bacteria being either enriched (13) or depleted (19) in the intestine and feces. Fecal samples showed a greater number of microbial genera influenced by stress than caecum or colon samples. Our trial revealed that the opportunistic pathogens Treponema and Clostridium were enriched in colonic and fecal samples from stressed pigs. Additionally, genera such as Streptococcus, Parabacteroides, Desulfovibrio, Terrisporobacter, Marvinbryantia, and Romboutsia were found to be enriched in response to social stress. In contrast, the genera Prevotella, Faecalibacterium, Butyricicoccus, Dialister, Alloprevotella, Megasphaera, and Mitsuokella were depleted. These depleted bacteria are of great interest because they synthesize metabolites [e.g., short-chain fatty acids (SCFA), in particular, butyrate] showing beneficial health benefits due to inhibitory effects on pathogenic bacteria in different animal species. Of particular interest are Dialister and Faecalibacterium, as their depletion was identified in a human study to be associated with inferior quality of life and depression. We also revealed that some pigs were more susceptible to pathogens as indicated by large enrichments of opportunistic pathogens of Clostridium, Treponema, Streptococcus and Campylobacter. Generally, our results provide further evidence for the microbiota-gut-brain axis as indicated by an increase in cortisol concentration due to social stress regulated by the hypothalamic-pituitary-adrenal axis, and a change in microbiota composition, particularly of bacteria known to be associated with pathogenicity and mental health diseases.

Gut Microbiota Signatures Are Associated With Psychopathological Profiles in Patients With Ulcerative Colitis: Results From an Italian Tertiary IBD Center

BACKGROUND

Several patients with ulcerative colitis (UC) suffer from psychiatric disorders, such as major depressive disorder, anxiety, or bipolar disorder, and show specific personality traits. Despite this, there are few data about personality profiles' characterization in UC patients and about correlation of their psychopathological profile with their intestinal microbiota.The aim of our study is to analyze the psychopathological and personality profile of UC patients and correlate it with specific signatures of their gut microbiota.

METHODS

This is a prospective interventional longitudinal cohort study. We enrolled consecutive patients affected by UC attending to the IBD Unit of Center for Digestive Disease of "A. Gemelli" IRCCS Hospital in Rome and a group of healthy subjects, matched for specific characteristics. Each patient was evaluated by a gastroenterologist and a psychiatrist. Moreover, all participants underwent psychological tests and a collection of stool samples.

RESULTS

We recruited 39 UC patients and 37 healthy subjects. Most patients showed high level of alexithymia, anxiety symptoms, depressive symptoms, as well as neuroticism and hypochondria, with obsessive-compulsive features at the behavioral level, which significantly impaired their quality of life and abilities at work. Gut microbiota analysis in UC patients demonstrated an increase in actinobacteria, Proteobacteria and Saccharibacteria (TM7), with a reduction in verrucomicrobia, euryarchaeota and tenericutes.

CONCLUSIONS

Our study confirmed the presence of high levels of psycho-emotional distress in UC patients, alongside alterations of the intestinal microbiota, and highlighted some families and genera of bacteria (Enterobacteriaceae, Streptococcus, Veillonella, Klebsiella, and Clostridiaceae) as potential markers of an altered gut-brain axis in these patients.

Discrimination exposure impacts unhealthy processing of food cues: crosstalk between the brain and gut

Experiences of discrimination are associated with adverse health outcomes, including obesity. However, the mechanisms by which discrimination leads to obesity remain unclear. Utilizing multi-omics analyses of neuroimaging and fecal metabolites, we investigated the impact of discrimination exposure on brain reactivity to food images and associated dysregulations in the brain-gut-microbiome system. We show that discrimination is associated with increased food-cue reactivity in frontal-striatal regions involved in reward, motivation and executive control; altered glutamate-pathway metabolites involved in oxidative stress and inflammation as well as preference for unhealthy foods. Associations between discrimination-related brain and gut signatures were skewed towards unhealthy sweet foods after adjusting for age, diet, body mass index, race and socioeconomic status. Discrimination, as a stressor, may contribute to enhanced food-cue reactivity and brain-gut-microbiome disruptions that can promote unhealthy eating behaviors, leading to increased risk for obesity. Treatments that normalize these alterations may benefit individuals who experience discrimination-related stress.

Intestinal permeability and low-grade chronic inflammation in schizophrenia: A multicentre study on biomarkers. Rationale, objectives, protocol and preliminary results

BACKGROUND

Altered intestinal permeability and low-grade chronic inflammation disrupt the integrity of the blood-brain barrier (microbiota-gut-brain axis), probably playing a role in the pathophysiology of schizophrenia-spectrum disorders. However, studies assessing the microbiota-gut-brain axis are inconsistent. This article describes the rationale, objectives, protocol, and presents descriptive results for a new project.

METHODS

The sample of this study came from an observational, cross-sectional and multisite study including four centers in Spain (PI17/00246) recruiting adult patients with DSM-5 schizophrenia-spectrum disorders at any stage of the disease. The aims of the project are to assess the interrelation between intestinal permeability and low-grade chronic inflammation in schizophrenia-spectrum disorders and the role of peripheral biomarkers, diet, exercise, metabolic syndrome, disease severity and functioning as well as cognition. Assessments included the following variables: (1) anthropometric, (2) intestinal permeability, diet, and physical exercise, (3) clinical and functional, (4) neuropsychological and cognitive reserve, and (5) peripheral biomarkers from blood.

RESULTS

A total of 646 patients were enrolled (257, 39.7% female). Mean age was 43.2±13.6 years, illness duration 15.1±11.5 years. 55.8% consumed tobacco. Positive PANSS score was 13.68±6.55, and 20.38±8.69 in the negative symptoms. CGI was 4.16±2.22 and GAF was 60.00±14.84.

CONCLUSION

The results obtained by this project are expected to contribute toward the understanding of the physiopathology of schizophrenia-spectrum disorders. This will likely aid to personalize treatments in real-world clinical practice, potentially including variables related to intestinal permeability and inflammation.

Exploring the gut microbiota: lifestyle choices, disease associations, and personal genomics

The gut microbiota is a rich and dynamic ecosystem that actively interacts with the human body, playing a significant role in the state of health and disease of the host. Diet, exercise, mental health, and other factors have exhibited the ability to influence the gut bacterial composition, leading to changes that can prevent and improve, or favor and worsen, both intestinal and extra-intestinal conditions. Altered gut microbial states, or 'dysbiosis', associated with conditions and diseases are often characterized by shifts in bacterial abundance and diversity, including an impaired Firmicutes to Bacteroidetes ratio. By understanding the effect of lifestyle on the gut microbiota, personalized advice can be generated to suit each individual profile and foster the adoption of lifestyle changes that can both prevent and ameliorate dysbiosis. The delivery of effective and reliable advice, however, depends not only on the available research and current understanding of the topic, but also on the methods used to assess individuals and to discover the associations, which can introduce bias at multiple stages. The aim of this review is to summarize how human gut microbial variability is defined and what lifestyle choices and diseases have shown association with gut bacterial composition. Furthermore, popular methods to investigate the human gut microbiota are outlined, with a focus on the possible bias caused by the lack of use of standardized methods. Finally, an overview of the current state of personalized advice based on gut microbiota testing is presented, underlining its power and limitations.

Unraveling the Gut-Brain Axis in Multiple Sclerosis: Exploring Dysbiosis, Oxidative Stress, and Therapeutic Insights

This comprehensive review delves into the intricate relationship between the gut microbiota and multiple sclerosis (MS), shedding light on the potential therapeutic avenues for this complex autoimmune disease. It emphasizes the multifactorial nature of MS, including genetic, environmental, and gender-related factors. Furthermore, the article highlights the emerging role of gut microbiota in MS pathophysiology, particularly in terms of gut dysbiosis, oxidative stress, and inflammasome activation within the gut-brain axis. This interplay raises intriguing questions about how the gut microbiota influences the onset and progression of MS. Environmental factors, such as diet and pollutants, add further layers of complexity to the connection between gut health and MS risk. This review also discusses promising therapeutic interventions, such as fecal microbiota transplantation, probiotics, dietary adjustments, and gut-derived metabolites that offer potential avenues for managing MS. It underscores the need for ongoing research to fully unravel the complexities of the role of the gut-brain axis in MS. Ultimately, this article provides a comprehensive exploration of the topic, offering hope for novel preventive and therapeutic strategies that could significantly improve the lives of individuals affected by this challenging autoimmune condition.

Comparative analysis of gut microbiota between common (Macaca fascicularis fascicularis) and Burmese (M. f. aurea) long-tailed macaques in different habitats

The environment has an important effect on the gut microbiota-an essential part of the host's health-and is strongly influenced by the dietary pattern of the host as these together shape the composition and functionality of the gut microbiota in humans and other animals. This study compared the gut microbiota of Macaca fascicularis fascicularis and M. f. aurea in mangrove and island populations using 16S rRNA gene sequencing on a nanopore platform to investigate the effect of the environment and/or diet. The results revealed that the M. f. fascicularis populations that received anthropogenic food exhibited a higher richness and evenness of gut microbiota than the M. f. aurea populations in different habitats. Firmicutes and Bacteroidetes were the two most abundant bacterial phyla in the gut microbiota of both these subspecies; however, the relative abundance of these phyla was significantly higher in M. f. aurea than in M. f. fascicularis. This variation in the gut microbiota between the two subspecies in different habitats mostly resulted from the differences in their diets. Moreover, the specific adaptation of M. f. aurea to different environments with a different food availability had a significant effect on their microbial composition.

Ameliorative effects of probiotics in AlCl3-induced mouse model of Alzheimer's disease

In recent years, gut microbiome alterations have been linked with complex underlying mechanisms of neurodegenerative disorders including Alzheimer's disease (AD). The gut microbiota modulates gut brain axis by facilitating development of hypothalamic-pituitary-adrenal axis and synthesis of neuromodulators. The study was designed to unravel the effect of combined consumption of probiotics; Lactobacillus rhamnosus GG (LGG®) and Bifidobacterium BB-12 (BB-12®) (1 × 109 CFU) on AlCl3-induced AD mouse model in comparison with potent acetylcholine esterase inhibitor drug for AD, donepezil. Mice were randomly allocated to six different study groups (n = 8). Behavioral tests were conducted to assess effect of AlCl3 (300 mg/kg) and probiotics treatment on cognition and anxiety through Morris Water Maze (MWM), Novel Object Recognition (NOR), Elevated Plus Maze (EPM), and Y-maze. The results indicated that the combined probiotic treatment significantly (p < 0.0001) reduced anxiety-like behavior post AlCl3 exposure. The AlCl3 + LGG® and BB-12®-treated group showed significantly improved spatial (p < 0.0001) and recognition memory (p < 0.0001) in comparison to AlCl3-treated group. The expression status of inflammatory cytokines (TNF-α and IL-1β) was also normalized upon treatment with LGG® and BB-12® post AlCl3 exposure. Our findings indicated that the probiotics LGG® and BB-12® have strong potential to overcome neuroinflammatory imbalance, cognitive deficits and anxiety-like behavior, therefore can be considered as a combination therapy for AD through modulation of gut brain axis. KEY POINTS: • Bifidobacterium BB-12 and Lactobacillus rhamnosus GG were fed to AlCl3-induced Alzheimer's disease mice. • This combination of probiotics had remarkable ameliorating effects on anxiety, neuroinflammation and cognitive deficits. • These effects may suggest that combined consumption of these probiotics instigate potential mitigation of AD associated consequences through gut brain axis modulation.

Serum Zonulin and Claudin-5 but not Interferon-Gamma and Interleukin-17A Levels Increased in Children with Specific Learning Disorder: A Case-Control Study

Background

Gut-blood and blood-brain barrier permeabilty (gut-brain axis) has been attracting increased attention in the etiology of neurodevelopmental disorders. In this study, we aimed to investigate serum levels of zonulin (a biomarker of intestinal permeability), claudin-5 (a biomarker of blood-brain barrier permeability), and interferon-gamma and interleukin-17A in children with specific learning disorder.

Methods

Forty-three children with DSM-5 diagnosis of specific learning disorder and 43 healthy children were included in this study. Serum levels of zonulin, claudin-5, interferon-gamma, and interleukin-17A were measured using commercial enzyme-linked immunosorbent assay kits.

Results

Serum zonulin and claudin-5 levels of the study group were significantly higher than the control group according to the multivariate analysis of covariance test while controlling for age, gender, and body mass index. However, serum interferon-gamma and interleukin-17A levels were not significantly different between the two groups. There was no correlation either between zonulin and interferon-gamma and interleukin-17A or claudin-5 and interferon-gamma and interleukin-17A.

Conclusion

Gut-blood and blood-brain barrier permeability may be disrupted in subjects with special learning disorder. Further research is needed to determine whether zonulin and claudin-5 may be biomarkers, and some dietary interventions or specific agents such as zonulin or claudin-5 inhibitors could be used in the management of neurodevelopmental disorders including special learning disorder.

A randomized controlled trial to examine the impact of a multi-strain probiotic on self-reported indicators of depression, anxiety, mood, and associated biomarkers

Objective

To examine the efficacy of supplementing with a multi-strain probiotic (MSP) on changes associated with mood, anxiety, and neurotransmitter levels.

Method

In a randomized, double-blind, placebo-controlled fashion, 70 healthy men and women (31.0 ± 9.5 years, 173.0 ± 10.4 cm, 73.9 ± 13.8 kg, 24.6 ± 3.5 kg/m2) supplemented with a single capsule of MSP (a total daily dose of 4 × 109 colony forming units [CFU] comprised of a 1 × 109 CFU dose from each of the following strains: Limosilactobacillus fermentum LF16, Lacticaseibacillus rhamnosus LR06, Lactiplantibacillus plantarum LP01, and Bifidobacterium longum 04, Probiotical S.p.A., Novara, Italy) or a maltodextrin placebo (PLA). After 0, 2, 4, and 6 weeks of supplementation and 3 weeks after ceasing supplementation, study participants completed the Beck Depression Inventory (BDI-II), State-Trait Anxiety Inventory (STAI), and Leiden Index of Depression Sensitivity (LEIDS-R) questionnaires and had plasma concentrations of cortisol, dopamine, serotonin, and C-reactive protein determined.

Results

BDI, STAI, and total LEIDS-R scores were reduced from baseline (p < 0.05) with MSP supplementation after 4 and 6 weeks of supplementation and 3 weeks after supplementation while no changes (p > 0.05) were reported in PLA. When compared to PLA, MSP scores for state anxiety, trait anxiety, and LEIDS-R (hopeless, aggression, rumination, and total score) were significantly lower (p < 0.05) after supplementation. Plasma serotonin concentrations in MSP were increased from baseline after 6 weeks of supplementation and 3 weeks after ceasing supplementation. No changes (p > 0.05) in plasma dopamine, C-reactive protein, or cortisol concentrations were observed between groups.

Conclusion

MSP supplementation resulted in widespread improvements in several questionnaires evaluating mood, anxiety, and depression in young, healthy men and women. MSP supplementation increased serotonin increased after 6 weeks of MSP supplementation with no change in dopamine, C-reactive protein, or cortisol.

Clinical trial registration

https://classic.clinicaltrials.gov/ct2/show/NCT05343533, NCT05343533.

Exposure to Roundup and Antibiotics Alters Gut Microbial Communities, Growth, and Behavior in Rana berlandieri Tadpoles

The gut microbiome is important for digestion, host fitness, and defense against pathogens, which provides a tool for host health assessment. Amphibians and their microbiomes are highly susceptible to pollutants including antibiotics. We explored the role of an unmanipulated gut microbiome on tadpole fitness and phenotype by comparing tadpoles of Rana berlandieri in a control group (1) with tadpoles exposed to: (2) Roundup® (glyphosate active ingredient), (3) antibiotic cocktail (enrofloxacin, sulfamethazine, trimethoprim, streptomycin, and penicillin), and (4) a combination of Roundup and antibiotics. Tadpoles in the antibiotic and combination treatments had the smallest dorsal body area and were the least active compared to control and Roundup-exposed tadpoles, which were less active than control tadpoles. The gut microbial community significantly changed across treatments at the alpha, beta, and core bacterial levels. However, we did not find significant differences between the antibiotic- and combination-exposed tadpoles, suggesting that antibiotic alone was enough to suppress growth, change behavior, and alter the gut microbiome composition. Here, we demonstrate that the gut microbial communities of tadpoles are sensitive to environmental pollutants, namely Roundup and antibiotics, which may have consequences for host phenotype and fitness via altered behavior and growth.

Association Between Gut Microbiota and Delirium in Acutely Ill Older Adults

Our aim was to investigate the association between gut microbiota and delirium occurrence in acutely ill older adults. We included 133 participants 65+ years consecutively admitted to the emergency department of a tertiary university hospital, between September 2019 and March 2020. We excluded candidates with ≥24-hour antibiotic utilization on admission, recent prebiotic or probiotic utilization, artificial nutrition, acute gastrointestinal disorders, severe traumatic brain injury, recent hospitalization, institutionalization, expected discharge ≤48 hours, or admission for end-of-life care. A trained research team followed a standardized interview protocol to collect sociodemographic, clinical, and laboratory data on admission and throughout the hospital stay. Our exposure measures were gut microbiota alpha and beta diversities, taxa relative abundance, and core microbiome. Our primary outcome was delirium, assessed twice daily using the Confusion Assessment Method. Delirium was detected in 38 participants (29%). We analyzed 257 swab samples. After adjusting for potential confounders, we observed that a greater alpha diversity (higher abundance and richness of microorganisms) was associated with a lower risk of delirium, as measured by the Shannon (odds ratio [OR] = 0.77; 95% confidence interval [CI] = 0.60-0.99; p = .042) and Pielou indexes (OR = 0.69; 95% CI = 0.51-0.87; p = .005). Bacterial taxa associated with pro-inflammatory pathways (Enterobacteriaceae) and modulation of relevant neurotransmitters (Serratia: dopamine; Bacteroides, Parabacteroides: GABA) were more common in participants with delirium. Gut microbiota diversity and composition were significantly different in acutely ill hospitalized older adults who experienced delirium. Our work is an original proof-of-concept investigation that lays a foundation for future biomarker studies and potential therapeutic targets for delirium prevention and treatment.

Liposomal Epigallocatechin-3-Gallate for the Treatment of Intestinal Dysbiosis in Children with Autism Spectrum Disorder: A Comprehensive Review

Autism Spectrum Disorder (ASD) is characterized by varying degrees of difficulty in social interaction and communication. These deficits are often associated with gastrointestinal symptoms, indicating alterations in both intestinal microbiota composition and metabolic activities. The intestinal microbiota influences the function and development of the nervous system. In individuals with ASD, there is an increase in bacterial genera such as Clostridium, as well as species involved in the synthesis of branched-chain amino acids (BCAA) like Prevotella copri. Conversely, decreased amounts of Akkermansia muciniphila and Bifidobacterium spp. are observed. Epigallocatechin-3-gallate (EGCG) is one of the polyphenols with the greatest beneficial activity on microbial growth, and its consumption is associated with reduced psychological distress. Therefore, the objective of this review is to analyze how EGCG and its metabolites can improve the microbial dysbiosis present in ASD and its impact on the pathology. The analysis reveals that EGCG inhibits the growth of pathogenic bacteria like Clostridium perfringens and Clostridium difficile. Moreover, it increases the abundance of Bifidobacterium spp. and Akkermansia spp. As a result, EGCG demonstrates efficacy in increasing the production of metabolites involved in maintaining epithelial integrity and improving brain function. This identifies EGCG as highly promising for complementary treatment in ASD.

Neurophysiology of Brain Networks Underlies Symptoms of Parkinson's Disease: A Basis for Diagnosis and Management

Parkinson's disease (PD) is one of the leading neurodegenerative disorders. It is considered a movement disorder, although it is accepted that many nonmotor symptoms accompany the classic motor symptoms. PD exhibits heterogeneous and overlaying clinical symptoms, and the overlap of motor and nonmotor symptoms complicates the clinical diagnosis and management. Loss of modulation secondary to the absence of dopamine due to degeneration of the substantia nigra compacta produces changes in firing rates and patterns, oscillatory activity, and higher interneuronal synchronization in the basal ganglia-thalamus-cortex and nigrovagal network involvement in motor and nonmotor symptoms. These neurophysiological changes can be monitored by electrophysiological assessment. The purpose of this review was to summarize the results of neurophysiological changes, especially in the network oscillation in the beta-band level associated with parkinsonism, and to discuss the use of these methods to optimize the diagnosis and management of PD.

Akkermansia muciniphila in neuropsychiatric disorders: friend or foe?

An accumulating body of evidence suggests that the bacterium Akkermansia muciniphila exhibits positive systemic effects on host health, mainly by improving immunological and metabolic functions, and it is therefore regarded as a promising potential probiotic. Recent clinical and preclinical studies have shown that A. muciniphila plays a vital role in a variety of neuropsychiatric disorders by influencing the host brain through the microbiota-gut-brain axis (MGBA). Numerous studies observed that A. muciniphila and its metabolic substances can effectively improve the symptoms of neuropsychiatric disorders by restoring the gut microbiota, reestablishing the integrity of the gut mucosal barrier, regulating host immunity, and modulating gut and neuroinflammation. However, A. muciniphila was also reported to participate in the development of neuropsychiatric disorders by aggravating inflammation and influencing mucus production. Therefore, the exact mechanism of action of A. muciniphila remains much controversial. This review summarizes the proposed roles and mechanisms of A. muciniphila in various neurological and psychiatric disorders such as depression, anxiety, Parkinson's disease, Alzheimer's disease, multiple sclerosis, strokes, and autism spectrum disorders, and provides insights into the potential therapeutic application of A. muciniphila for the treatment of these conditions.

Influence of Bariatric Surgery on Oral Microbiota: A Systematic Review

The study aims to systematically review the available literature to evaluate the changes in oral microbiota in patients after bariatric surgery (BS) and correlates these alterations in microorganisms with common oral manifestations. Relevant Electronic databases were systematically searched for indexed English literature. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were followed for framework designing, application, and reporting of the current systematic review. The focused PICO question was: "Is there any change in oral microbiota (O) of patients (P) who underwent BS (I) when compared with non-BS groups (C)?' Seven articles were selected for qualitative synthesis. On application of the National Institutes of Health (NIH) quality assessment tool, six studies were found to be of fair quality and one was of good quality. All the seven included studies evaluated the effect of BS on oral microbiota in humans. The outcomes of this review suggest that considerable changes take place in oral microbiota after BS which can be correlated with common oral manifestations. These changes are mainly due to the indirect effect of BS and may vary with the individuals. Due to variations in the included studies, it is difficult to proclaim any persistent pattern of oral microbiota found after BS.

Open multi-organ communication device for easy interrogation of tissue slices

Here, we have developed an open multi-organ communication device that facilitates cellular and molecular communication between ex vivo organ slices. Measuring communication between organs is vital for understanding the mechanisms of health regulation yet remains difficult with current technology. Communication between organs along the gut-brain-immune axis is a key regulator of gut homeostasis. As a novel application of the device, we have used tissue slices from the Peyer's patch (PP) and mesenteric lymph node (MLN) due to their importance in gut immunity; however, any organ slices could be used here. The device was designed and fabricated using a combination of 3D printed molds for polydimethylsiloxane (PDMS) soft lithography, PDMS membranes, and track-etch porous membranes. To validate cellular and protein transfer between organs on-chip, we used fluorescence microscopy to quantitate movement of fluorescent proteins and cells from the PP to the MLN, replicating the initial response to immune stimuli in the gut. IFN-γ secretion during perfusion from a naïve vs. inflamed PP to a healthy MLN was quantitated to demonstrate soluble signaling molecules are moving on-chip. Finally, transient catecholamine release was measured during perfusion from PP to MLN using fast-scan cyclic voltammetry at carbon-fiber microelectrodes to demonstrate a novel application of the device for real-time sensing during communication. Overall, we show an open-well multi-organ device capable of facilitating transfer of soluble factors and cells with the added benefit of being available for external analysis techniques like electrochemical sensing which will advance abilities to probe communication in real-time across multiple organs ex vivo.