Modulation of the gut microbiota and glycometabolism by a probiotic to alleviate amyloid accumulation and cognitive impairments in AD rats

Dual-Carriers of Tartary Buckwheat-Derived Exosome-Like Nanovesicles Synergistically Regulate Glucose Metabolism in the Intestine-Liver Axis

The utilization of plant-derived exosome-like nanovesicles (ELNs) as nanocarriers for oral delivery of bioactives has garnered significant attention. However, their distinctive lipid membrane composition may result in elevated membrane permeability within the gastrointestinal environment, leading to the leakage of carried bioactives. Inspired by the concept of projectile design, Tartary buckwheat-derived ELNs (TB-ELNs) based dual-carriers are fabricated by loading chlorogenic acid (CGA) into the cores and bonding selenium nanoparticles (SeNPs) to the lipid membrane. The results indicate that SeNPs bond markedly augments the membrane rigidity, and therefore enhances the stability of TB-ELNs and the retention rate of the loaded CGA during gastrointestinal digestion. In vitro and in vivo studies indicates that the TB-ELNs based dual-carriers are internalized by epithelial cells and transcytosis via the endoplasmic reticulum, and show the synergistic regulatory effect on high-fat diet-induced hyperglycemia in the intestine-liver axis. These results may be attributed to the fact that SeNPs combination reduces the gastrointestinal degradation of the carried bioactives. Moreover, SeNPs with antioxidant property can protect ELNs and their carried bioactives from oxidative damage, thereby enhancing their biological activities. Collectively, this study offers a new strategy to develop highly efficient oral delivery systems for bioactives to alleviate hyperglycemia and diabetes.

Association of the dietary index for gut microbiota with sleep disorder among US adults: the mediation effect of dietary inflammation index

Background

Previous studies have confirmed the relationship between gut microbiota and sleep disorders, characterized by the persistent inability to achieve adequate sleep, with dietary composition playing a key role in maintaining microbiota homeostasis. Our study aims to explore the relationship between the newly proposed Dietary Index for Gut Microbiota (DI-GM) and sleep disorders, as well as whether the Dietary Inflammatory Index (DII) mediates this relationship.

Methods

This study is based on data from 30,406 participants in the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2018, a cross-sectional survey that represents the U.S. adult population. We used multivariable logistic regression models to examine the relationship between DI-GM and sleep disorders. Subgroup interaction analyses were conducted to assess the stability of the results. Mediation analysis was employed to explore the effect of the Dietary Inflammatory Index (DII) on the relationship between DI-GM and sleep disorders.

Results

The DI-GM score was significantly negatively correlated with sleep disorders. After adjusting for covariates, each unit increase in DI-GM was associated with a 5% reduction in the prevalence of sleep disorders (p < 0.001). Additionally, there was a trend toward a decrease in the prevalence of sleep disorders with increasing DI-GM (trend p < 0.05). Dose-response curve analysis revealed a linear relationship between DI-GM and sleep disorders, with higher DI-GM scores being associated with lower prevalence of sleep disorders. DII was positively correlated with sleep disorders (p < 0.001) and decreased as DI-GM increased (β = -0.37, p < 0.001). Mediation analysis showed that DII significantly mediated the relationship between DI-GM and sleep disorders, with a mediation proportion of 27.36% (p < 0.001).

Conclusion

The results of this study indicate that the DI-GM score was significantly negatively correlated with sleep disorders. A higher DI-GM score is associated with a lower incidence of sleep disorders, while the DII significantly mediated the relationship between DI-GM and sleep disorders. Specifically, an increase in DII may attenuate the protective effect of DI-GM on sleep disorders.

Coenzyme Q10 modulates the immunity by enhancing mononuclear macrophage, NK cell activity, and regulating gut microbiota

Introduction

Coenzyme Q10 (CoQ10), an important fat-soluble, bioactive molecule that predominantly found in the inner mitochondrial membrane, is widely used in functional food and health food raw materials, which has garnered considerable attention due to its potential role in immunoregulation. However, the intrinsic mechanism of CoQ10 on immunity, and the relationship to the gut microbiota have not been elucidated.

Methods

Here, we conducted a series of in vivo experiments with the aim of comprehensively exploring the effect of CoQ10 on both cellular and humoral immune functions, and on gut microbiota communities in mice.

Results

CoQ10 showed negligible impact on both mouse body weight fluctuations and tissue indices, but enhanced the mouse body immunity by elevating the carbon clearance ability and natural killer (NK) cellular viability. 16S rRNA gene sequencing revealed that administration of CoQ10 modulated the structure and composition of the gut microbiota in mice, notably by enhancing the abundance of Lactobacillus, Limosilactobacillus, and decreasing the abundance of Paramuribaculum species.

Discussion

This work makes a contribution to the application of CoQ10 as an immunomodulator in the biological, pharmaceutical and health care product industries.

Probiotics as Potential Treatments for Neurodegenerative Diseases: a Review of the Evidence from in vivo to Clinical Trial

Neurodegenerative diseases (NDDs), characterized by the progressive deterioration of the structure and function of the nervous system, represent a significant global health challenge. Emerging research suggests that the gut microbiota plays a critical role in regulating neurodegeneration via modulation of the gut-brain axis. Probiotics, defined as live microorganisms that confer health benefits to the host, have garnered significant attention owing to their therapeutic potential in NDDs. This review examines the current research trends related to the microbiome-gut-brain axis across various NDDs, highlighting key findings and their implications. Additionally, the effects of specific probiotic strains, including Lactobacillus plantarum, Bifidobacterium breve, and Lactobacillus rhamnosus, on neurodegenerative processes were assessed, focusing on their potential therapeutic benefits. Overall, this review emphasizes the potential of probiotics as promising therapeutic agents for NDDs, underscoring the importance of further investigation into this emerging field.

Novel insights into Cntnap4 in Alzheimer's disease: Intestinal flora interaction

Alzheimer's disease (AD) is a neurodegenerative disorder with unclear etiology. This study employs single-cell RNA sequencing (scRNA-seq), high-throughput transcriptome sequencing, 16s rRNA sequencing, and animal experiments to investigate the role of the contactin-associated protein like-4 (Cntnap4) gene in AD and its interaction with intestinal flora. We found that Cntnap4 deficiency in AD mice led to increased Tau protein phosphorylation, amyloid-beta plaque accumulation, and neuronal loss. Astrocytes in Cntnap4-/- mice showed impaired amyloid-beta processing. 16 s rRNA sequencing revealed distinct intestinal flora compositions between Cntnap4-/- and control mice, indicating a potential link between gut microbiota and AD progression. Notably, GABA supplementation improved cognitive impairment, restored synaptic currents, reduced amyloid-beta plaques, and increased neuronal counts. This study highlights Cntnap4's critical role in AD and suggests gut-brain axis involvement, offering novel insights for potential therapeutic strategies.

Exploring the gut-brain axis in alzheimer's disease treatment via probiotics: evidence from animal studies-a systematic review and meta-analysis

INTRODUCTION

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder in the elderly, causing cognitive impairment. Its pathogenesis is characterized by amyloid beta deposition, neurofibrillary tangles, and neuroinflammation. Recent research has identified the link between gut dysbiosis, an imbalance of intestinal microorganisms, to this pathogenesis via the gut-brain axis. This study aims to review the probiotics' therapeutic effect, targeting the gut-brain axis, for AD treatment in animals.

METHODS

The method utilized in this study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. Three reviewers searched articles through PubMed, Scopus, and Embase using advanced search strategy. Articles published between 2010 and 2023 that met the criteria were included.

RESULTS

Of 2,273 articles, 21 animal studies measuring the effects of probiotics genera Lactobacillus and/or Bifidobacterium on AD via at least one of these four outcomes: AD pathology, cognitive function, neuroinflammation, and gut microbiota composition. The results demonstrated that probiotics could repair gut dysbiosis by decreasing pro-inflammatory bacteria and increasing anti-inflammatory bacteria. Repaired dysbiosis was found to be associated with less neuroinflammation as significant reductions in neuroinflammatory markers related to the pathogenesis of AD such as TNF-α (SMD = -2.08, P = 0.005), IL-6 (SMD = -2.98, P < 0.0005), and IL-1β (SMD = -2.49, P = 0.003) were observed. Reduced amyloid beta deposition (SMD = -1.17, P = 0.009) was reported, but reduction in tau hyperphosphorylation was found to be insignificant. For cognitive function, positive results were demonstrated for all three aspects of cognitive function including long-term memory (SMD = 2.55, P < 0.00001), short-term memory (SMD = 1.32, P = 0.003), and spatial recognition (SMD = -1.13, P < 0.00001).

CONCLUSIONS

Particular formulas of probiotics showed potential effectiveness in AD therapies with demonstrated association with the gut-brain axis. Future studies are required to investigate strain-specific results and optimal dosages and regimens.

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.

Microglia and gut microbiota: A double-edged sword in Alzheimer's disease

The strong association between gut microbiota (GM) and brain functions such as mood, behaviour, and cognition has been well documented. Gut-brain axis is a unique bidirectional communication system between the gut and brain, in which gut microbes play essential role in maintaining various molecular and cellular processes. GM interacts with the brain through various pathways and processes including, metabolites, vagus nerve, HPA axis, endocrine system, and immune system to maintain brain homeostasis. GM dysbiosis, or an imbalance in GM, is associated with several neurological disorders, including anxiety, depression, and Alzheimer's disease (AD). Conversely, AD is sustained by microglia-mediated neuroinflammation and neurodegeneration. Further, GM and their products also affect microglia-mediated neuroinflammation and neurodegeneration. Despite the evidence connecting GM dysbiosis and AD progression, the involvement of GM in modulating microglia-mediated neuroinflammation in AD remains elusive. Importantly, deciphering the mechanism/s by which GM regulates microglia-dependent neuroinflammation may be helpful in devising potential therapeutic strategies to mitigate AD. Herein, we review the current evidence regarding the involvement of GM dysbiosis in microglia activation and neuroinflammation in AD. We also discuss the possible mechanisms through which GM influences the functioning of microglia and its implications for therapeutic intervention. Further, we explore the potential of microbiota-targeted interventions, such as prebiotics, probiotics, faecal microbiota transplantation, etc., as a novel therapeutic strategy to mitigate neuroinflammation and AD progression. By understanding and exploring the gut-brain axis, we aspire to revolutionize the treatment of neurodegenerative disorders, many of which share a common theme of microglia-mediated neuroinflammation and neurodegeneration.

NMN Synbiotics: A Multifaceted Therapeutic Approach for Alzheimer's Disease

With the aging global population, Alzheimer's disease (AD) has become a significant social and economic burden, necessitating the development of novel therapeutic strategies. This study investigates the therapeutic potential of nicotinamide mononucleotide (NMN) synbiotics, a combination of NMN, Lactiplantibacillus plantarum CGMCC 1.16089, and lactulose, in mitigating AD pathology. APP/PS1 mice were supplemented with NMN synbiotics and compared against control groups. The effects on amyloid-β (Aβ) deposition, intestinal histopathology, tight junction proteins, inflammatory cytokines, and reactive oxygen species (ROS) levels were assessed. NMN synbiotics intervention significantly reduced Aβ deposition in the cerebral cortex and hippocampus by 67% and 60%, respectively. It also ameliorated histopathological changes in the colon, reducing crypt depth and restoring goblet cell numbers. The expression of tight junction proteins Claudin-1 and ZO-1 was significantly upregulated, enhancing intestinal barrier integrity. Furthermore, NMN synbiotics decreased the expression of proinflammatory cytokines IL-1β, IL-6, and TNF-α, and reduced ROS levels, indicative of attenuated oxidative stress. The reduction in Aβ deposition, enhancement of intestinal barrier function, decrease in neuroinflammation, and alleviation of oxidative stress suggest that NMN synbiotics present a promising therapeutic intervention for AD by modulating multiple pathological pathways. Further research is required to elucidate the precise mechanisms, particularly the role of the NLRP3 inflammasome pathway, which may offer a novel target for AD treatment.

The Brain-Gut-Bone Axis in Neurodegenerative Diseases: Insights, Challenges, and Future Prospects

Neurodegenerative diseases are global health challenges characterized by the progressive degeneration of nerve cells, leading to cognitive and motor impairments. The brain-gut-bone axis, a complex network that modulates multiple physiological systems, has gained increasing attention owing to its profound effects on the occurrence and development of neurodegenerative diseases. No comprehensive review has been conducted to clarify the triangular relationship involving the brain-gut-bone axis and its potential for innovative therapies for neurodegenerative disorders. In light of this, a new perspective is aimed to propose on the interplay between the brain, gut, and bone systems, highlighting the potential of their dynamic communication in neurodegenerative diseases, as they modulate multiple physiological systems, including the nervous, immune, endocrine, and metabolic systems. Therapeutic strategies for maintaining the balance of the axis, including brain health regulation, intestinal microbiota regulation, and improving skeletal health, are also explored. The intricate physiological interactions within the brain-gut-bone axis pose a challenge in the development of effective treatments that can comprehensively target this system. Furthermore, the safety of these treatments requires further evaluation. This review offers a novel insights and strategies for the prevention and treatment of neurodegenerative diseases, which have important implications for clinical practice and patient well-being.

The gut microbiota-brain axis in neurological disorders

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

Microbiota-Gut-Brain Axis Dysregulation in Alzheimer's Disease: Multi-Pathway Effects and Therapeutic Potential

An essential regulator of neurodegenerative conditions like Alzheimer's disease (AD) is the gut microbiota. Alterations in intestinal permeability brought on by gut microbiota dysregulation encourage neuroinflammation, central immune dysregulation, and peripheral immunological dysregulation in AD, as well as hasten aberrant protein aggregation and neuronal death in the brain. However, it is unclear how the gut microbiota transmits information to the brain and how it influences brain cognition and function. In this review, we summarized the multiple pathways involved in the gut microbiome in AD and provided detailed treatment strategies based on the gut microbiome. Based on these observations, this review also discusses the problems, challenges, and strategies to address current therapeutic strategies.

Mechanism Explanation on Improved Cognitive Ability of D-Gal Inducing Aged Mice Model by Lactiplantibacillus plantarum MWFLp-182 via the Microbiota-Gut-Brain Axis

Gut microbiota can influence cognitive ability via the gut-brain axis. Lactiplantibacillus plantarum MWFLp-182 (L. plantarum MWFLp-182) was obtained from feces of long-living individuals and could exert marked antioxidant ability. Interestingly, this strain reduced the D-galactose-induced impaired cognitive ability in BALB/c mice. To comprehensively elucidate the underlying mechanism, we evaluated the colonization, antioxidant, and anti-inflammatory activities of L. plantarum MWFLp-182, along with the expression of potential genes associated with cognitive ability influenced and gut microbiota. L. plantarum MWFLp-182 enhanced the expression of anti-inflammatory cytokines, reduced the expression of proinflammatory cytokines, and increased tight junction protein expression in the colon. Moreover, L. plantarum MWFLp-182 could modify the gut microbiota. Notably, treatment with L. plantarum MWFLp-182 upregulated the expression of postsynaptic density protein-95, nuclear factor erythroid 2-related factor, nerve growth factor, superoxide dismutase, and brain-derived neurotrophic factor/neuronal nuclei, while downregulating the expression of bcl-2-associated X and malondialdehyde in the hippocampus and upregulating short-chain fatty acids against D-galactose-induced mouse brain deficits. Accordingly, L. plantarum MWFLp-182 could improve cognitive ability in a D-galactose-inducing mouse model.

Correlation between the gut microbiome and neurodegenerative diseases: a review of metagenomics evidence

A growing body of evidence suggests that the gut microbiota contributes to the development of neurodegenerative diseases via the microbiota-gut-brain axis. As a contributing factor, microbiota dysbiosis always occurs in pathological changes of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. High-throughput sequencing technology has helped to reveal that the bidirectional communication between the central nervous system and the enteric nervous system is facilitated by the microbiota's diverse microorganisms, and for both neuroimmune and neuroendocrine systems. Here, we summarize the bioinformatics analysis and wet-biology validation for the gut metagenomics in neurodegenerative diseases, with an emphasis on multi-omics studies and the gut virome. The pathogen-associated signaling biomarkers for identifying brain disorders and potential therapeutic targets are also elucidated. Finally, we discuss the role of diet, prebiotics, probiotics, postbiotics and exercise interventions in remodeling the microbiome and reducing the symptoms of neurodegenerative diseases.

Modulation of gut microbiota with probiotics as a strategy to counteract endogenous and exogenous neurotoxicity

The existing data demonstrate that probiotic supplementation affords protective effects against neurotoxicity of exogenous (e.g., metals, ethanol, propionic acid, aflatoxin B1, organic pollutants) and endogenous (e.g., LPS, glucose, Aβ, phospho-tau, α-synuclein) agents. Although the protective mechanisms of probiotic treatments differ between various neurotoxic agents, several key mechanisms at both the intestinal and brain levels seem inherent to all of them. Specifically, probiotic-induced improvement in gut microbiota diversity and taxonomic characteristics results in modulation of gut-derived metabolite production with increased secretion of SFCA. Moreover, modulation of gut microbiota results in inhibition of intestinal absorption of neurotoxic agents and their deposition in brain. Probiotics also maintain gut wall integrity and inhibit intestinal inflammation, thus reducing systemic levels of LPS. Centrally, probiotics ameliorate neurotoxin-induced neuroinflammation by decreasing LPS-induced TLR4/MyD88/NF-κB signaling and prevention of microglia activation. Neuroprotective mechanisms of probiotics also include inhibition of apoptosis and oxidative stress, at least partially by up-regulation of SIRT1 signaling. Moreover, probiotics reduce inhibitory effect of neurotoxic agents on BDNF expression, on neurogenesis, and on synaptic function. They can also reverse altered neurotransmitter metabolism and exert an antiamyloidogenic effect. The latter may be due to up-regulation of ADAM10 activity and down-regulation of presenilin 1 expression. Therefore, in view of the multiple mechanisms invoked for the neuroprotective effect of probiotics, as well as their high tolerance and safety, the use of probiotics should be considered as a therapeutic strategy for ameliorating adverse brain effects of various endogenous and exogenous agents.

Neuroprotective effects of probiotics on anxiety- and depression-like disorders in stressed mice by modulating tryptophan metabolism and the gut microbiota

Anxiety- and depression-like behaviors are commonly observed clinical features of depression and many other mental disorders. Recent evidence has revealed the crucial role of the microbiota-gut-brain axis in the bidirectional communication between the gastrointestinal tract and the central nervous system. Supplementation with psychobiotics may provide a novel approach for the adjunctive treatment of mental disorders by regulating the intestinal microecology. We isolated and identified a novel probiotic, Lactiplantibacillus plantarum D-9 (D-9), from traditional Chinese fermented foods in our previous work, which exhibited a high yield of gamma-aminobutyric acid (GABA). Herein, it was proved that the oral administration of D-9 could alleviate the depression- and anxiety-like behaviors of Chronic Unpredicted Mild Stress (CUMS) mice, and show non-toxicity or side-effects in the mice. Physiological and biochemical analyses demonstrated that D-9 regulated tryptophan metabolism, the HPA-axis and inflammation in CUMS mice. Moreover, D-9 modulated the structure and composition of the gut microbiota, leading to an increase in the relative abundance of Ligilactobacillus murinus and Lactobacillus johnsonii, and a decrease in the levels of Kineothrix alysoides and Helicobacter bilis compared to those in CUMS mice. Our work demonstrates that D-9 alleviated anxiety- and depression-like disorders in CUMS mice by modulating tryptophan metabolism and the gut microbiota. These findings provide an innovative strategy for the intervention and treatment of depressive disorders.

Fermented foods: Harnessing their potential to modulate the microbiota-gut-brain axis for mental health

Over the past two decades, whole food supplementation strategies have been leveraged to target mental health. In addition, there has been increasing attention on the ability of gut microbes, so called psychobiotics, to positively impact behaviour though the microbiota-gut-brain axis. Fermented foods offer themselves as a combined whole food microbiota modulating intervention. Indeed, they contain potentially beneficial microbes, microbial metabolites and other bioactives, which are being harnessed to target the microbiota-gut-brain axis for positive benefits. This review highlights the diverse nature of fermented foods in terms of the raw materials used and type of fermentation employed, and summarises their potential to shape composition of the gut microbiota, the gut to brain communication pathways including the immune system and, ultimately, modulate the microbiota-gut-brain axis. Throughout, we identify knowledge gaps and challenges faced in designing human studies for investigating the mental health-promoting potential of individual fermented foods or components thereof. Importantly, we also suggest solutions that can advance understanding of the therapeutic merit of fermented foods to modulate the microbiota-gut-brain axis.

Acupuncture modulates the gut microbiota in Alzheimer's disease: current evidence, challenges, and future opportunities

Alzheimer's disease, one of the most severe and common neurodegenerative diseases, has no effective cure. Therefore it is crucial to explore novel and effective therapeutic targets. The gut microbiota - brain axis has been found to play a role in Alzheimer's disease by regulating the neuro-immune and endocrine systems. At the same time, acupuncture can modulate the gut microbiota and may impact the course of Alzheimer's disease. In this Review, we discuss recent studies on the role of acupuncture on the gut microbiota as well current challenges and future opportunities of acupuncture as potential treatment for the prevention and treatment of Alzheimer's disease.

Microbiota-gut-brain axis and its therapeutic applications in neurodegenerative diseases

The human gastrointestinal tract is populated with a diverse microbial community. The vast genetic and metabolic potential of the gut microbiome underpins its ubiquity in nearly every aspect of human biology, including health maintenance, development, aging, and disease. The advent of new sequencing technologies and culture-independent methods has allowed researchers to move beyond correlative studies toward mechanistic explorations to shed light on microbiome-host interactions. Evidence has unveiled the bidirectional communication between the gut microbiome and the central nervous system, referred to as the "microbiota-gut-brain axis". The microbiota-gut-brain axis represents an important regulator of glial functions, making it an actionable target to ameliorate the development and progression of neurodegenerative diseases. In this review, we discuss the mechanisms of the microbiota-gut-brain axis in neurodegenerative diseases. As the gut microbiome provides essential cues to microglia, astrocytes, and oligodendrocytes, we examine the communications between gut microbiota and these glial cells during healthy states and neurodegenerative diseases. Subsequently, we discuss the mechanisms of the microbiota-gut-brain axis in neurodegenerative diseases using a metabolite-centric approach, while also examining the role of gut microbiota-related neurotransmitters and gut hormones. Next, we examine the potential of targeting the intestinal barrier, blood-brain barrier, meninges, and peripheral immune system to counteract glial dysfunction in neurodegeneration. Finally, we conclude by assessing the pre-clinical and clinical evidence of probiotics, prebiotics, and fecal microbiota transplantation in neurodegenerative diseases. A thorough comprehension of the microbiota-gut-brain axis will foster the development of effective therapeutic interventions for the management of neurodegenerative diseases.

Effects and mechanism of extracts rich in phenylpropanoids-polyacetylenes and polysaccharides from Codonopsis Radix on improving scopolamine-induced memory impairment of mice

ETHNOPHARMACOLOGICAL RELEVANCE

Alzheimer's disease (AD) is a progressive developmental neurodegenerative disease that primarily develops in old age. Memory impairment is an important manifestation of AD. It has been demonstrated that inflammation and oxidative stress are important mediators in the development and progression of AD. Codonopsis Radix (CR) has a long history of consumption, exhibiting lots of beneficial health effects, including anti-ageing, antioxidant, and anti-inflammatory properties. However, studies on the effects of CR on scopolamine-induced amnesia have rarely been reported.

AIM OF THE STUDY

The aim of this study was to investigate the ameliorative effect of macromolecular portion (polysaccharides, POL) and small molecule portion (fine extract rich in phenylpropanoids-polyacetylenes, EPP) from CR on improving scopolamine-induced memory impairment and to elucidate the potential mechanism of action.

MATERIALS AND METHODS

C57BL/6 mice were pretreated with EPP (0.2, 0.4, and 0.6 g/kg), POL (0.3, 0.6, and 0.9 g/kg), and donepezil (5 mg/kg) by gavage for 7 days, followed by intraperitoneal injection of scopolamine (1 mg/kg) to induce memory impairment. The 16S rRNA gene sequencing, histopathological, western blotting, and biochemical analysis (various biochemical markers and protein expressions related to cholinergic system, oxidative stress, and neuroinflammation) were performed to further elucidate the mechanism of action. Moreover, the acetylcholinesterase (AChE) inhibitory activities of POL, EPP, and its main compounds tangshenoside I, lobetyol, lobetyolin, and lobetyolinin were evaluated.

RESULTS

Experiments have confirmed that both POL and EPP from CR could improve scopolamine-induced spatial learning memory deficits. Both of them could regulate cholinergic function by inhibiting AChE and activating choline acetyltransferase (ChAT) activities. They also could enhance antioxidant defense via increasing the activities of superoxide dismutase and glutathione peroxidase, and anti-inflammatory function through suppressing inflammatory factors (nitric oxide, TNF-α, and IL-6) and regulating gut flora. Besides, in vitro experiments demonstrated that four monomeric compounds and EPP, except POL, exhibited inhibition of AChE activity.

CONCLUSION

EPP and POL from CR exert a beneficial effect on learning and memory processes in mice with scopolamine-induced memory impairment. CR may be a promising medicine for preventing and improving learning memory.

Improvement of inflammatory bowel disease by lactic acid bacteria-derived metabolites: a review

Lactic acid bacteria (LAB) plays a crucial role in the establishment and maintenance of host health, as well as the improvement of some diseases. One of the major modes is the secretion of metabolites that may be intermediate or end products of the LAB's metabolism. In this review, we summarized some common metabolites (particularly short-chain fatty acids [SCFAs], bacteriocin, and exopolysaccharide [EPS]) from LAB in fermented foods and the gut for the first time. The effects of LAB-derived metabolites (LABM) on inflammation, oxidative stress, the intestinal barrier, and gut microbiota in inflammatory bowel disease (IBD) model are also discussed. The discovery of LABM and identification of IBD biomarkers are mainly attributed to the development of metabolomics technologies, especially nuclear magnetic resonance (NMR), gas chromatography-mass spectrometry (GC-MS), and liquid chromatography tandem mass spectrometry (LC-MS). The application of these metabolomics technologies in identification of LABM and IBD biomarkers are also summarized and analyzed. Although the beneficial effects of some LABM have been explored, undiscovered metabolites and their functions still need further investigations.

Targeting the gut-microbiota-brain axis in irritable bowel disease to improve cognitive function - recent knowledge and emerging therapeutic opportunities

The brain-gut axis forms a bidirectional communication system between the gastrointestinal (GI) tract and cognitive brain areas. Disturbances to this system in disease states such as inflammatory bowel disease have consequences for neuronal activity and subsequent cognitive function. The gut-microbiota-brain axis refers to the communication between gut-resident bacteria and the brain. This circuits exists to detect gut microorganisms and relay information to specific areas of the central nervous system (CNS) that in turn, regulate gut physiology. Changes in both the stability and diversity of the gut microbiota have been implicated in several neuronal disorders, including depression, autism spectrum disorder Parkinson's disease, Alzheimer's disease and multiple sclerosis. Correcting this imbalance with medicinal herbs, the metabolic products of dysregulated bacteria and probiotics have shown hope for the treatment of these neuronal disorders. In this review, we focus on recent advances in our understanding of the intricate connections between the gut-microbiota and the brain. We discuss the contribution of gut microbiota to neuronal disorders and the tangible links between diseases of the GI tract with cognitive function and behaviour. In this regard, we focus on irritable bowel syndrome (IBS) given its strong links to brain function and anxiety disorders. This adds to the growing body of evidence supporting targeted therapeutic strategies to modulate the gut microbiota for the treatment of brain/mental-health-related disease.

Interactions between gut microbes and NLRP3 inflammasome in the gut-brain axis

The role of the gut-brain axis in maintaining the brain's and gut's homeostasis has been gradually recognized in recent years. The connection between the gut and the brain takes center stage. In this scenario, the nucleotide-binding oligomerization domain leucine-rich repeat and pyrin domain-containing protein 3 (NLRP3) inflammasome promotes inflammatory cell recruitment. It plays a crucial role in coordinating host physiology and immunity. Recent evidence shows how vital the gut-brain axis is for maintaining brain and gut homeostasis. However, more research is needed to determine the precise causal link between changed gut microbiota structure and NLRP3 activation in pathogenic circumstances. This review examines the connection between gut microbiota and the NLRP3 inflammasome. We describe how both dynamically vary in clinical cases and the external factors affecting both. Finally, we suggest that the crosstalk between the gut microbiota and NLRP3 is involved in signaling in the gut-brain axis, which may be a potential pathological mechanism for CNS diseases and intestinal disorders.