Fructooligosaccharides Ameliorating Cognitive Deficits and Neurodegeneration in APP/PS1 Transgenic Mice through Modulating Gut Microbiota

Exploring the interaction between the gut microbiota and cyclic adenosine monophosphate-protein kinase A signaling pathway: a potential therapeutic approach for neurodegenerative diseases

The interaction between the gut microbiota and cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) signaling pathway in the host's central nervous system plays a crucial role in neurological diseases and enhances communication along the gut-brain axis. The gut microbiota influences the cAMP-PKA signaling pathway through its metabolites, which activates the vagus nerve and modulates the immune and neuroendocrine systems. Conversely, alterations in the cAMP-PKA signaling pathway can affect the composition of the gut microbiota, creating a dynamic network of microbial-host interactions. This reciprocal regulation affects neurodevelopment, neurotransmitter control, and behavioral traits, thus playing a role in the modulation of neurological diseases. The coordinated activity of the gut microbiota and the cAMP-PKA signaling pathway regulates processes such as amyloid-β protein aggregation, mitochondrial dysfunction, abnormal energy metabolism, microglial activation, oxidative stress, and neurotransmitter release, which collectively influence the onset and progression of neurological diseases. This study explores the complex interplay between the gut microbiota and cAMP-PKA signaling pathway, along with its implications for potential therapeutic interventions in neurological diseases. Recent pharmacological research has shown that restoring the balance between gut flora and cAMP-PKA signaling pathway may improve outcomes in neurodegenerative diseases and emotional disorders. This can be achieved through various methods such as dietary modifications, probiotic supplements, Chinese herbal extracts, combinations of Chinese herbs, and innovative dosage forms. These findings suggest that regulating the gut microbiota and cAMP-PKA signaling pathway may provide valuable evidence for developing novel therapeutic approaches for neurodegenerative diseases.

The complex relationship between gut microbiota and Alzheimer's disease: A systematic review

Alzheimer's disease (AD) is a progressive, degenerative disorder of the central nervous system. Despite extensive research conducted on this disorder, its precise pathogenesis remains unclear. In recent years, the microbiota-gut-brain axis has attracted considerable attention within the field of AD. The gut microbiota communicates bidirectionally with the central nervous system through the gut-brain axis, and alterations in its structure and function can influence the progression of AD. Consequently, regulating the gut microbiota to mitigate the progression of AD has emerged as a novel therapeutic approach. Currently, numerous studies concentrate on the intrinsic relationship between the microbiota-gut-brain axis and AD. In this paper, we summarize the multifaceted role of the gut microbiota in AD and present detailed therapeutic strategies targeting the gut microbiota, including the treatment of AD with Traditional Chinese Medicine (TCM), which has garnered increasing attention in recent years. Finally, we discuss potential therapeutic strategies for modulating the gut microbiota to alleviate the progression of AD, the current challenges in this area of research, and provide an outlook on future research directions in this field.

Integrative approaches to atrial fibrillation prevention and management: Leveraging gut health for improved cardiovascular outcomes in the aging population

Atrial fibrillation (AF) is a prevalent clinical arrhythmia associated with a high incidence and severe complications such as cerebral embolism and heart failure. While the etiology and pathogenesis of AF involve numerous factors, recent research emphasizes the significant role of intestinal microbiota imbalance in the emergence and progression of AF, particularly among older adults. This review investigates the mechanisms by which intestinal flora and their metabolites contribute to the onset of AF in the elderly, highlighting novel interactions between gut health and cardiac function. Current literature often overlooks these critical connections, indicating a substantial research gap in understanding how dysbiosis may exacerbate AF and hinder recovery. Furthermore, exploring the bidirectional relationship between the gut microbiome and systemic inflammation in the context of AF provides a unique perspective that has yet to be thoroughly investigated. Future research should focus on longitudinal studies assessing gut microbiota composition and function in AF patients and consider probiotics or prebiotics as potential adjunctive therapies for mitigating AF. This comprehensive approach may pave the way for innovative treatments integrating cardiology with gastroenterology, enhancing patient outcomes through a holistic understanding of health.

Gut microbiome and Alzheimer's disease: What we know and what remains to be explored

With advancement in human microbiome research, an increasing number of scientific evidences have endorsed the key role of gut microbiota in the pathogenesis of Alzheimer disease. Microbiome dysbiosis, characterized by altered diversity and composition, as well as rise of pathobionts influence not only various gut disorder but also central nervous system disorders such as AD. On the basis of accumulated evidences of past few years now it is quite clear that the gut microbiota can control the functions of the central nervous system (CNS) through the gut-brain axis, which provides a new prospective into the interactions between the gut and brain. The main focus of this review is on the molecular mechanism of the crosstalk between the gut microbiota and the brain through the gut-brain axis, and on the onset and development of neurological disorders triggered by the dysbiosis of gut microbiota. Due to microbiota dysbiosis the permeability of the gut and blood brain barrier is increased which may mediate or affect AD. Along with this, bacterial population of the gut microbiota can secrete amyloid proteins and lipopolysaccharides in a large quantity which may create a disturbance in the signaling pathways and the formation of proinflammatory cytokines associated with the pathogenesis of AD. These topics are followed by a critical analysis of potential intervention strategies targeting gut microbiota dysbiosis, including the use of probiotics, prebiotics, metabolites, diets and fecal microbiota transplantation. The main purpose of this review includes the summarization and discussion on the recent finding that may explain the role of the gut microbiota in the development of AD. Understanding of these fundamental mechanisms may provide a new insight into the novel therapeutic strategies for AD.

Gut Microbiota and Immune System Dynamics in Parkinson's and Alzheimer's Diseases

The gut microbiota, a diverse collection of microorganisms in the gastrointestinal tract, plays a critical role in regulating metabolic, immune, and cognitive functions. Disruptions in the composition of these microbial communities, termed dysbiosis, have been linked to various neurodegenerative diseases (NDs), such as Parkinson's disease (PD) and Alzheimer's disease (AD). One of the key pathological features of NDs is neuroinflammation, which involves the activation of microglia and peripheral immune cells. The gut microbiota modulates immune responses through the production of metabolites and interactions with immune cells, influencing the inflammatory processes within the central nervous system. This review explores the impact of gut dysbiosis on neuroinflammation, focusing on the roles of microglia, immune cells, and potential therapeutic strategies targeting the gut microbiota to alleviate neuroinflammatory processes in NDs.

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.

Effects of inulin-type oligosaccharides (JSO) from Cichorium intybus L. on behavioral deficits induced by chronic restraint stress in mice and associated molecular alterations

Depression and anxiety are serious psychiatric disorders with significant physical and mental health impacts, necessitating the development of safe and effective treatments. This study aimed to evaluate the efficacy of Jiangshi oligosaccharide (JSO), a type of inulin-based oligosaccharide, in alleviating anxiety and depression and to investigate the underlying molecular mechanisms. Using a mouse model of chronic restraint stress (CRS), JSO was administered orally at doses of 50, 100, and 200 mg/kg for 21 days. Behavioral tests, including the novelty-suppressed feeding test (NSFT), open field test (OFT), elevated plus maze test (EPMT), tail suspension test (TST), and forced swimming test (FST), demonstrated that JSO significantly improved anxiety- and depressive-like behaviors (P< 0.05). Notably, JSO reduced feeding latency in the NSFT, increased time spent in the center in the OFT, enhanced time and entries into open arms in the EPMT, and decreased immobility time in the TST and FST (P< 0.01). Histological and molecular analyses revealed that JSO treatment attenuated neuronal loss in the hippocampus (Hip) and medial prefrontal cortex (mPFC) and reduced the expression of inflammatory markers such as Iba-1 and GFAP in these regions. JSO significantly downregulated the mRNA and protein expression of pro-inflammatory factors (IL-1β, TNF-α, IL-6) while increasing anti-inflammatory markers (IL-10, TGF-β) (P< 0.05). Furthermore, JSO inhibited the c-GAS-STING-NLRP3 axis and apoptosis-related proteins (Bax/Bcl-2, Caspase-3/8/9) while promoting the expression of brain-derived neurotrophic factor (BDNF), PSD-95, and synaptophysin (SYP), indicating improved neuronal survival and synaptic plasticity (P< 0.01). These findings suggest that JSO exerts potent anti-anxiety and antidepressant effects by modulating neuroinflammation, synaptic function, and neuronal apoptosis in the Hip and mPFC of CRS mice. This study highlighted JSO as a potential therapeutic agent for stress-induced anxiety and depression.

Encapsulated lactiplantibacillus plantarum improves Alzheimer's symptoms in APP/PS1 mice

BACKGROUND

Alzheimer's disease (AD) is a neurodegenerative disorder that can result in neurotoxicity and an imbalance in gut microbiota. Probiotics have been shown to play an important role in regulating the gut microbiota, but their viability and bioactivity are often compromised as they traverse the gastrointestinal tract, thereby reducing their efficacy and limiting their clinical utility.

RESULTS

In this work, layer-by-layer (LbL) encapsulation technology was used to encapsulate Lactiplantibacillus plantarum (LP) to improve the above shortcomings. Studies in APPswe/PS1dE9 (APP/PS1) transgenic mice show that LbL-encapsulated LP ((CS/SP)2-LP) protects LP from gastrointestinal damage while (CS/SP)2-LP treatment It improves brain neuroinflammation and neuronal damage in AD mice, reduces Aβ deposition, improves tau protein phosphorylation levels, and restores intestinal barrier damage in AD mice. In addition, post-synaptic density protein 95 (PSD-95) expression increased in AD mice after treatment, indicating enhanced synaptic plasticity. Fecal metabolomic and microbiological analyzes showed that the disordered intestinal microbiota composition of AD mice was restored and short-chain fatty acids (SCFAs) levels were significantly increased after (CS/SP)2-LP treatment.

CONCLUSION

Overall, the above evidence suggests that (CS/SP)2-LP can improve AD symptoms by restoring the balance of intestinal microbiota, and (CS/SP)2-LP treatment will provide a new method to improve the symptoms of AD patients.

Gut microbiota metabolites: potential therapeutic targets for Alzheimer's disease?

Background

Alzheimer's disease (AD) is a neurodegenerative disease characterized by progressive decline in cognitive function, which significantly increases pain and social burden. However, few therapeutic interventions are effective in preventing or mitigating the progression of AD. An increasing number of recent studies support the hypothesis that the gut microbiome and its metabolites may be associated with upstream regulators of AD pathology.

Methods

In this review, we comprehensively explore the potential mechanisms and currently available interventions targeting the microbiome for the improvement of AD. Our discussion is structured around modern research advancements in AD, the bidirectional communication between the gut and brain, the multi-target regulatory effects of microbial metabolites on AD, and therapeutic strategies aimed at modulating gut microbiota to manage AD.

Results

The gut microbiota plays a crucial role in the pathogenesis of AD through continuous bidirectional communication via the microbiota-gut-brain axis. Among these, microbial metabolites such as lipids, amino acids, bile acids and neurotransmitters, especially sphingolipids and phospholipids, may serve as central components of the gut-brain axis, regulating AD-related pathogenic mechanisms including β-amyloid metabolism, Tau protein phosphorylation, and neuroinflammation. Additionally, interventions such as probiotic administration, fecal microbiota transplantation, and antibiotic use have also provided evidence supporting the association between gut microbiota and AD. At the same time, we propose an innovative strategy for treating AD: a healthy lifestyle combined with targeted probiotics and other potential therapeutic interventions, aiming to restore intestinal ecology and microbiota balance.

Conclusion

Despite previous efforts, the molecular mechanisms by which gut microbes act on AD have yet to be fully described. However, intestinal microorganisms may become an essential target for connecting the gut-brain axis and improving the symptoms of AD. At the same time, it requires joint exploration by multiple centers and multiple disciplines.

Mechanisms of action and applications of Polygonatum sibiricum polysaccharide at the intestinal mucosa barrier: a review

As a medicinal and edible homologous Chinese herb, Polygonatum sibiricum has been used as a primary ingredient in various functional and medicinal products. Damage to the intestinal mucosal barrier can lead to or worsen conditions such as type 2 diabetes and Alzheimer's disease. Traditional Chinese medicine and its bioactive components can help prevent and manage these conditions by restoring the integrity of the intestinal mucosal barrier. This review delves into the mode of action of P. sibiricum polysaccharide in disease prevention and management through the restoration of the intestinal barrier. Polysaccharide from P. sibiricum effectively treats conditions by repairing the intestinal mucosal barrier, offering insights for treating complex diseases and supporting the application of P. sibiricum in clinical settings.

Interconnections between the Gut Microbiome and Alzheimer's Disease: Mechanisms and Therapeutic Potential

Alzheimer's disease (AD) is a neurodegenerative disease that is known to accumulate amyloid-β (Aβ) and tau protein. Clinical studies have not identified pathogenesis mechanisms or produced an effective cure for AD. The Aβ monoclonal antibody lecanemab reduces Aβ plaque formation for the treatment of AD, but more studies are required to increase the effectiveness of drugs to reduce cognitive decline. The lack of AD therapy targets and evidence of an association with an acute neuroinflammatory response caused by several bacteria and viruses in some individuals has led to the establishment of the infection hypothesis during the last 10 years. How pathogens cross the blood-brain barrier is highly topical and is seen to be pivotal in proving the hypothesis. This review summarizes the possible role of the gut microbiome in the pathogenesis of AD and feasible therapeutic approaches and current research limitations.

Causal relationship between the gut microbiota, immune cells, and coronary heart disease: a mediated Mendelian randomization analysis

Background

Recent studies have shown that the gut microbiota (GM), immune cells, and coronary heart disease (CHD) are closely related, but the causal nature of these relationships is largely unknown. This study aimed to investigate this causal relationship and reveal the effect of GM and immune cells on the risk of developing CHD using mediated Mendelian randomization (MR) analysis.

Methods

First, we searched for data related to GM, immune cells, and CHD through published genome-wide association studies (GWAS). We filtered the single nucleotide polymorphisms (SNPs) associated with GM and immune cells and then performed the first MR analysis to identify disease-associated intestinal bacteria and disease-associated immune cells. Subsequently, three MR analyses were conducted: from disease-associated GM to disease-associated immune cells, from disease-associated immune cells to CHD, and from disease-associated GM to CHD. Each MR analysis was conducted using inverse variance weighting (IVW), MR-Egger regression, weighted median, weighted models, and simple models.

Results

A total of six GM and 25 immune cells were found to be associated with CHD. In the MR analysis using the inverse variance weighting (IVW) method, g__Desulfovibrio.s__Desulfovibrio_piger was associated with EM DN (CD4-CD8-) %T cells (P < 0.05 and OR > 1), EM DN (CD4-CD8-) %T cells was associated with CHD (P < 0.05 and OR < 1), and g__Desulfovibrio.s__Desulfovibrio_piger was associated with CHD (P < 0.05 and OR < 1).

Conclusion

An increase in the abundance of g__Desulfovibrio.s__Desulfovibrio_piger leads to an increase in the amount of EM DN (CD4-CD8-) %T cells, and an increase in the amount of EM DN (CD4-CD8-) %T cells reduces the risk of developing CHD. Our study provides some references for reducing the incidence of CHD by regulating GM and immune cells.

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.

Banxia Xiexin Decoction Alleviated Cerebral Glucose Metabolism Disorder by Regulating Intestinal Microbiota in APP/PS1 Mice

OBJECTIVE

To identify whether Banxia Xiexin Decoction (BXD) alleviates cerebral glucose metabolism disorder by intestinal microbiota regulation in APP/PS1 mice.

METHODS

Forty-five 3-month-old male APP/PS1 mice were divided into 3 groups using a random number table (n=15 per group), including a model group (MG), a liraglutide group (LG) and a BXD group (BG). Fifteen 3-month-old male C57BL/6J wild-type mice were used as the control group (CG). Mice in the BG were administered BXD granules by gavage at a dose of 6 g/(kg•d) for 3 months, while mice in the LG were injected intraperitoneally once daily with Liraglutide Injection (25 nmol/kg) for 3 months. Firstly, liquid chromatography with tandem-mass spectrometry was used to analyze the active components of BXD granules and the medicated serum of BXD. Then, the cognitive deficits, Aβ pathological change and synaptic plasticity markers, including synaptophysin (SYP) and postsynaptic density protein 95 (PSD95), were measured in APP/PS1 mice. Brain glucose uptake was detected by micropositron emission tomography. Intestinal microbial constituents were detected by 16S rRNA sequencing. The levels of intestinal glucagon-like peptide 1 (GLP-1) and cerebral GLP-1 receptor (GLP-1R), as well as the phosphoinositide-3-kinase/protein kinase B/glycogen synthase kinase-3β (PI3K/Akt/GSK3β) insulin signaling pathway were determined by immunohistochemical (IHC) staining and Western blot analysis, respectively.

RESULTS

BXD ameliorated cognitive deficits and Aβ pathological features (P<0.01). The expressions of SYP and PSD95 in the BG were higher than those in the MG (P<0.01). Brain glucose uptake in the BG was higher than that in the MG (P<0.01). The intestinal microbial composition in the BG was partially reversed. The levels of intestinal GLP-1 in the BG were higher than those in the MG (P<0.01). Compared with the MG, the expression levels of hippocampal GLP-1R, Akt, PI3K and p-PI3K in the BG were significantly increased (P<0.01), while the levels of GSK3β were reduced (P<0.01).

CONCLUSION

BXD exhibited protective effects against Alzheimer's disease by regulating the gut microbiota/GLP-1/GLP-1R, enhancing PI3K/Akt/GSK3β insulin signaling pathway, and improving brain glucose metabolism.

Improvement of both human and animal memory by synergy between fructooligosaccharide and L-theanine function establishing a safe and effective food supplement

Aging is classically associated with a decline of cognitive abilities, especially in relation to memory. While the development of potential treatments for neurodegenerative diseases has been in sharp focus, mild cognitive impairment (MCI), a form of age-related memory loss, in the absence of severe functional impairment, a condition experienced by many healthy adults, has received relatively little attention. Advances in this space would make significant contributions to the goal of healthy aging and may also help promote cognitive performance across the wider population. The individual action of either fructooligosaccharide (FOS) or L-theanine, both natural plant-derived molecules, has been tentatively linked with improvements in cognition, but our understanding remains far from complete. We therefore determined the effect of different dose combinations of FOS and L-theanine (termed MT-01/GBL-Memory1) in mice against FOS and L-theanine monotherapy. FOS and L-theanine were found to synergistically enhance murine memory in our animal tests at a dose of 100 mg/kg (coefficient of drug interaction (CDI) < 1). In a subsequent human trial, we demonstrated that MT-01 improved the memory of healthy adults after 1 month of consumption. Our results suggest that a combination of FOS and L-theanine synergistically enhances murine memory within a specific dose range. We show that this plant natural product regimen also improves human memory in a population of healthy adults. MT-01 therefore represents a novel, safe, and effective dietary supplement to promote human memory and cognition.

Heat-moisture and acid treatments can increase levels of resistant starch in arrowroot starch without adversely affecting its prebiotic activity in human colon microbiota

Carbohydrates are an important macronutrient whose processing and digestive fate can have numerous beneficial or adverse effects on consumer health. This study investigated the impact of heat-moisture treatments (HMT) and citric acid treatments (CAT) on arrowroot starch (ARS) with a focus on its physicochemical properties, digestibility, and influence on gut microbiota. The results revealed that HMT and CAT did not alter the colloidal characteristics of ARS but significantly affected the balance between amorphous and crystalline regions. Changes in thermal properties, morphology, and particle size were also observed. These can influence ARS shelf life and functional properties in various food applications. Furthermore, certain treatments in both processing methods increased the resistant starch (RS) content of ARS, with HMT for 16 hours at 80 °C and CAT with 0.6 M citric acid, resulting in the most pronounced effects. These changes coincided with reductions in rapidly digestible starch (RDS) levels and improvements in the ratio of slowly digestible starch (SDS) to RDS, which could potentially improve glycemic control. This study also examined the impact of processed ARS on colonic microbiota composition. It found that ARS-derived RS formed under HMT and CAT did not negatively affect the prebiotic potential of the RS fraction. Both treatments were associated with lowering the Firmicutes to Bacteroidetes ratio (F/B), a marker of gut health, and decreasing the relative abundance of Proteobacteria, microbes associated with adverse health effects. Additionally, CAT-derived RS showed a significant increase in the relative abundance of Roseburia, a beneficial gut bacterium. In conclusion, processing ARS through HMT and CAT techniques has the potential for enhancing its RS content, improving its glycemic impact, and positively influencing the gut microbiota composition, potentially contributing to gut health and metabolic well-being.

Pseudostellaria heterophylla polysaccharide mitigates Alzheimer's-like pathology via regulating the microbiota-gut-brain axis in 5 × FAD mice

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterised by neuroinflammation, for which gut dysbiosis may be implicated. Our previous study showed that treatment with Pseudostellaria heterophylla aqueous extract and one of its cyclopeptides, heterophyllin B, attenuate memory deficits via immunomodulation and neurite regeneration. However, whether Pseudostellaria heterophylla polysaccharide (PH-PS) exerts neuroprotective effects against AD and its underlying mechanisms remain unclear. The infrared spectrum, molecular weight, and carbohydrate composition of the PH-PS were determined. The results showed that PH-PS (Mw 8.771 kDa) was composed of glucose (57.78 %), galactose (41.52 %), and arabinose (0.70 %). PH-PS treatment ameliorated learning and spatial memory deficits, reduced amyloid β build-up, and suppressed reactive glia and astrocytes in 5 × FAD mice. 16S rRNA sequencing further showed that PH-PS remodelled the intestinal flora composition by promoting probiotic microbiota, such as Lactobacillus, Muribaculum, Monoglobus, and [Eubacterium]_siraeum_group, and suppressing inflammation-related UCG-009 and Blautia. Additionally, PH-PS restored intestinal barrier function; ameliorated peripheral inflammation by reducing the secretion of inflammatory cytokines, thereby converting M1 microglia and A1 astrocyte toward beneficial M2 and A2 phenotypes; and contributed to Aβ plaques clearance by upregulation of insulin degradation enzyme and neprilysin. Collectively, our findings demonstrate that PH-PS may prevent the progression of AD via modulation of the gut microbiota and regulation of glial polarisation, which could provide evidence to design a potential diet therapy for preventing or curing AD.

Association of dietary live microbe intake with various cognitive domains in US adults aged 60 years or older

The purpose of this study was to explore whether dietary live microbe intake is associated with various cognitive domains using data from the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2014. And the specific relationship between low, medium and high dietary live microbe intake groups and cognitive ability of the elderly. Dietary live microbe intake was calculated from 24-h diet recall interviews. Cognitive function was assessed using the number symbol substitution test (DSST, which measures processing speed), the animal fluency test (AFT, which measures executive function), the Alzheimer's Registry sub-test (CERAD, which measures memory), and the Composite Z-score, which adds the Z-values of individual tests. Multiple linear regression models and restricted cubic bar graphs were used to investigate the relationship between live microbe intake and cognitive performance. A total of 2,450 participants aged 60 or older were included. Live microbe intake was positively correlated with cognitive ability on the whole. Specifically, when the intake of low, medium and high live microbe was > 2640 g, > 39 g and > 0 g respectively, the CERAD, DSST, AFT and compositive-Z score of the subjects increased with the increase of microbial intake (P < 0.05). In American adults age 60 or older, higher intakes of live microbes were associated with better cognitive performance, especially after a certain amount was reached.

The Role of Diet and Gut Microbiota in Alzheimer's Disease

Alzheimer's disease (AD), the most prevalent form of dementia, is characterized by the accumulation of amyloid-beta (Aβ) plaques and hyperphosphorylated tau tangles. Currently, Alzheimer's disease (AD) impacts 50 million individuals, with projections anticipating an increase to 152 million by the year 2050. Despite the increasing global prevalence of AD, its underlying pathology remains poorly understood, posing challenges for early diagnosis and treatment. Recent research suggests a link between gut dysbiosis and the aggregation of Aβ, the development of tau proteins, and the occurrence of neuroinflammation and oxidative stress are associated with AD. However, investigations into the gut-brain axis (GBA) in the context of AD progression and pathology have yielded inconsistent findings. This review aims to enhance our understanding of microbial diversity at the species level and the role of these species in AD pathology. Additionally, this review addresses the influence of confounding elements, including diet, probiotics, and prebiotics, on AD throughout different stages (preclinical, mild cognitive impairment (MCI), and AD) of its progression.

Gut microbiota defined epigenomes of Alzheimer's and Parkinson's diseases reveal novel targets for therapy

The origins of Alzheimer's disease (AD) and Parkinson's disease (PD) involve genetic mutations, epigenetic changes, neurotoxin exposure and gut microbiota dysregulation. The gut microbiota's dynamic composition and its metabolites influence intestinal and blood-brain barrier integrity, contributing to AD and PD development. This review explores protein misfolding, aggregation and epigenetic links in AD and PD pathogenesis. It also highlights the role of a leaky gut and the microbiota-gut-brain axis in promoting these diseases through inflammation-induced epigenetic alterations. In addition, we investigate the potential of diet, probiotics and microbiota transplantation for preventing and treating AD and PD via epigenetic modifications, along with a discussion related to current challenges and future considerations. These approaches offer promise for translating research findings into practical clinical applications.

Gut microbiome-targeted therapies for Alzheimer's disease

The advent of high-throughput 'omics' technologies has improved our knowledge of gut microbiome in human health and disease, including Alzheimer's disease (AD), a neurodegenerative disorder. Frequent bidirectional communications and mutual regulation exist between the gastrointestinal tract and the central nervous system through the gut-brain axis. A large body of research has reported a close association between the gut microbiota and AD development, and restoring a healthy gut microbiota may curb or even improve AD symptoms and progression. Thus, modulation of the gut microbiota has become a novel paradigm for clinical management of AD, and emerging effort has focused on developing potential novel strategies for preventing and/or treating the disease. In this review, we provide an overview of the connection and causal relationship between gut dysbiosis and AD, the mechanisms of gut microbiota in driving AD progression, and the successes and challenges of implementing available gut microbiome-targeted therapies (including probiotics, prebiotics, synbiotics, postbiotics, and fecal microbiota transplantation) in preventive and/or therapeutic preclinical and clinical intervention studies of AD. Finally, we discuss the future directions in this field.

Fecal microbiota transplantation: a novel strategy for treating Alzheimer's disease

Alzheimer's disease is a common neurological disorder, which has become one of the major factors affecting human health due to its serious impact on individuals, families and society. It has been confirmed that gut microbiota can affect the occurrence and development of Alzheimer's disease. Especially, fecal microbiota transplantation plays a positive role in the treatment of Alzheimer's disease. The mechanisms for improving Alzheimer's disease might include anti-inflammation and regulation of amyloid β-protein, synaptic plasticity, short-chain fatty acids, and histone acetylation. In this mini-review, the relationship between fecal microbiota transplantation and Alzheimer's disease was summarized. It is hoped that fecal microbiota transplantation would play a positive role in the prevention and treatment of Alzheimer's disease in the future.

Understanding the Gut-Brain Axis and Its Therapeutic Implications for Neurodegenerative Disorders

The gut-brain axis (GBA) is a complex bidirectional communication network connecting the gut and brain. It involves neural, immune, and endocrine communication pathways between the gastrointestinal (GI) tract and the central nervous system (CNS). Perturbations of the GBA have been reported in many neurodegenerative disorders (NDDs), such as Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS), among others, suggesting a possible role in disease pathogenesis. The gut microbiota is a pivotal component of the GBA, and alterations in its composition, known as gut dysbiosis, have been associated with GBA dysfunction and neurodegeneration. The gut microbiota might influence the homeostasis of the CNS by modulating the immune system and, more directly, regulating the production of molecules and metabolites that influence the nervous and endocrine systems, making it a potential therapeutic target. Preclinical trials manipulating microbial composition through dietary intervention, probiotic and prebiotic supplementation, and fecal microbial transplantation (FMT) have provided promising outcomes. However, its clear mechanism is not well understood, and the results are not always consistent. Here, we provide an overview of the major components and communication pathways of the GBA, as well as therapeutic approaches targeting the GBA to ameliorate NDDs.

Unveiling the role of gut-brain axis in regulating neurodegenerative diseases: A comprehensive review

Emerging evidence have shown the importance of gut microbiota in regulating brain functions. The diverse molecular mechanisms involved in cross-talk between gut and brain provide insight into importance of this communication in maintenance of brain homeostasis. It has also been observed that disturbed gut microbiota contributes to neurological diseases such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis and aging. Recently, gut microbiome-derived exosomes have also been reported to play an essential role in the development and progression of neurodegenerative diseases and could thereby act as a therapeutic target. Further, pharmacological interventions including antibiotics, prebiotics and probiotics can influence gut microbiome-mediated management of neurological diseases. However, extensive research is warranted to better comprehend this interconnection in maintenance of brain homeostasis and its implication in neurological diseases. Thus, the present review is aimed to provide a detailed understanding of gut-brain axis followed by possibilities to target the gut microbiome for improving neurological health.

Prebiotics modulate the microbiota-gut-brain axis and ameliorate cognitive impairment in APP/PS1 mice

PURPOSE

Prebiotics, including fructo-oligosaccharides (FOS) and galacto-oligosaccharides (GOS), stimulate beneficial gut bacteria and may be helpful for patients with Alzheimer's disease (AD). This study aimed to compare the effects of FOS and GOS, alone or in combination, on AD mice and to identify their underlying mechanisms.

METHODS

Six-month-old APP/PS1 mice and wild-type mice were orally administered FOS, GOS, FOS + GOS or water by gavage for 6 weeks and then subjected to relative assays, including behavioral tests, biochemical assays and 16S rRNA sequencing.

RESULTS

Through behavioral tests, we found that GOS had the best effect on reversing cognitive impairment in APP/PS1 mice, followed by FOS + GOS, while FOS had no effect. Through biochemical techniques, we found that GOS and FOS + GOS had effects on multiple targets, including diminishing Aβ burden and proinflammatory IL-1β and IL-6 levels, and changing the concentrations of neurotransmitters GABA and 5-HT in the brain. In contrast, FOS had only a slight anti-inflammatory effect. Moreover, through 16S rRNA sequencing, we found that prebiotics changed composition of gut microbiota. Notably, GOS increased relative abundance of Lactobacillus, FOS increased that of Bifidobacterium, and FOS + GOS increased that of both. Furthermore, prebiotics downregulated the expression levels of proteins of the TLR4-Myd88-NF-κB pathway in the colons and cortexes, suggesting the involvement of gut-brain mechanism in alleviating neuroinflammation.

CONCLUSION

Among the three prebiotics, GOS was the optimal one to alleviate cognitive impairment in APP/PS1 mice and the mechanism was attributed to its multi-target role in alleviating Aβ pathology and neuroinflammation, changing neurotransmitter concentrations, and modulating gut microbiota.

Gut Microbiota and its Metabolites: Bridge of Dietary Nutrients and Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disease characterized by progressive cognitive impairment and neuroinflammation. Recent research has revealed the crucial role of gut microbiota and microbial metabolites in modulating AD. However, the mechanisms by which the microbiome and microbial metabolites affect brain function remain poorly understood. Here, we review the literature on changes in the diversity and composition of the gut microbiome in patients with AD and in animal models of AD. We also discuss the latest progress in understanding the pathways by which the gut microbiota and microbial metabolites from the host or diet regulate AD. By understanding the effects of dietary components on brain function, microbiota composition, and microbial metabolites, we examine the potential for manipulation of the gut microbiota through dietary intervention to delay the progression of AD. Although it is challenging to translate our understanding of microbiome-based approaches to dietary guidelines or clinical therapies, these findings provide an attractive target for promoting brain function.

Role of microbial dysbiosis in the pathogenesis of Alzheimer's disease

Alzheimer's disease (AD) is the leading cause of dementia in the elderly and detected during the advanced stages where the chances of reversal are minimum. The gut-brain axis mediates a bidirectional communication between the gut and brain, which is dependent on bacterial products such as short chain fatty acids (SCFA) and neurotransmitters. Accumulating lines of evidence suggests that AD is associated with significant alteration in the composition of gut microbiota. Furthermore, transfer of gut microbiota from healthy individuals to patients can reshape the gut microbiota structure and thus holds the potential to be exploited for the treatment of various neurodegenerative disease. Moreover, AD-associated gut dysbiosis can be partially reversed by using probiotics, prebiotics, natural compounds and dietary modifications, but need further validations. Reversal of AD associated gut dysbiosis alleviate AD-associated pathological feature and therefore can be explored as a therapeutic approach in the future. The current review article will describe various studies suggesting that AD dysbiosis occurs with AD and highlights the causal role by focussing on the interventions that hold the potential to reverse the gut dysbiosis partially.

The contribution of probiotics for the double-edge effect of cefazolin on postoperative neurocognitive disorders by rebalancing the gut microbiota

Introduction

Emerging data suggest that perioperative gut dysbiosis is prevalent and may be associated with postoperative neurocognitive disorders (PND). Antibiotics and probiotics are key factors influencing the microbiota. Many antibiotics have anti-microorganisms and direct anti-inflammatory properties, which may have cognitive repercussions. NLRP3 inflammasome activation has been reported to be involved with cognitive deficits. This study aimed to determine the effect and mechanism of probiotics on neurocognitive problems associated with perioperative gut dysbiosis by the NLRP3 pathway.

Methods

In a randomized, controlled trial, adult male Kunming mice undergoing surgery were administered cefazolin, FOS + probiotics, CY-09, or a placebo in four distinct experimental cohorts. Fear conditioning (FC) tests evaluate learning and memory. Following FC tests to evaluate inflammatory response (IR) and the permeability of barrier systems, the hippocampus and colon were extracted, and feces were collected for 16 s rRNA.

Results

One week after surgery, surgery/anesthesia decreased the frozen behavior. Cefazolin attenuated this declination but aggravated postoperative freezing behavior 3 weeks after surgery. Probiotics ameliorated surgery/anesthesia-induced memory deficits and perioperative cefazolin-induced postoperative memory deficits 3 weeks after surgery. NLRP3, caspase-1, Interleukin-1β (IL-1β), and Interleukin-18 (IL-18) levels were increased 1 week after the hippocampus and colon surgery, which were attenuated by CY-09 and probiotics, respectively.

Discussion

Probiotics could correct dysbacteria and IR caused by surgery/anesthesia stress and cefazolin alone. These findings imply that probiotics are an efficient and effective way of maintaining the balance of gut microbiota, which may reduce NLRP3-related inflammation and alleviate PND.

Biopharmaceutical applications of microbial polysaccharides as materials: A review

Biological characteristics of natural polymers make microbial polysaccharides an excellent choice for biopharmaceuticals. Due to its easy purifying procedure and high production efficiency, it is capable of resolving the existing application issues associated with some plant and animal polysaccharides. Furthermore, microbial polysaccharides are recognized as prospective substitutes for these polysaccharides based on the search for eco-friendly chemicals. In this review, the microstructure and properties of microbial polysaccharides are utilized to highlight their characteristics and potential medical applications. From the standpoint of pathogenic processes, in-depth explanations are provided on the effects of microbial polysaccharides as active ingredients in the treatment of human diseases, anti-aging, and drug delivery. In addition, the scholarly developments and commercial applications of microbial polysaccharides as medical raw materials are also discussed. The conclusion is that understanding the use of microbial polysaccharides in biopharmaceuticals is essential for the future development of pharmacology and therapeutic medicine.

A Deep Insight into the Correlation Between Gut Dysbiosis and Alzheimer’s Amyloidopathy

Background

Recent research has shown a strong correlation between gut dysbiosis and Alzheimer’s disease (AD).

Purpose

To investigate the relationship between gut dysbiosis, immune system activation, and the onset of AD and to examine current breakthroughs in microbiota-targeted AD therapeutics.

Methods

A review of scientific literature was conducted to assess the correlation between gut dysbiosis and AD and the various factors associated.

Results

Gut dysbiosis produces an increase in harmful substances, such as bacterial amyloids, which makes the gut barrier and blood-brain barrier more permeable. This leads to the stimulation of immunological responses and an increase in cytokines such as interleukin-1β (IL-1β). As a result, gut dysbiosis accelerates the progression of AD.

Conclusion

The review highlights the connection between gut dysbiosis and AD and the potential for microbiota-targeted therapies in AD treatment.

Pictorial Abstract

Long-term supplementation with anthocyanin-rich or -poor Rubus idaeus berries does not influence microvascular architecture nor cognitive outcome in the APP/PS-1 mouse model of Alzheimer's disease

Disruption of microvascular architecture is a common pathogenic mechanism in the progression of Alzheimer's disease (AD). Given the anti-angiogenic activity of berry (poly)phenols, we investigated whether long-term feeding of Rubus idaeus (raspberries) could ameliorate cerebral microvascular pathology and improve cognition in the APP/PS-1 mouse model of AD. Male C57Bl/6J mice (50 wild type, 50 APP/PS-1) aged 4-months were fed for 24-weeks, with a normal diet enriched with either 100 mg/day glucose (control diet) or supplemented with glucose and freeze-dried anthocyanin-rich (red) or -poor (yellow) raspberries (100 mg/day) and assessed/sampled post intervention. Cerebral microvascular architecture of wild-type mice was characterised by regularly spaced capillaries with uniform diameters, unlike APP/PS-1 transgenic mice which showed dysregulated microvascular architecture. Long-term feeding of raspberries demonstrated limited modulation of microbiota and no substantive effect on microvascular architecture or cognition in either mice model although changes were evident in endogenous cerebral and plasmatic metabolites.

Neuroprotective effects of polysaccharide from Sparassis crispa on Alzheimer's disease-like mice: Involvement of microbiota-gut-brain axis

Alzheimer's disease (AD) is an irreversible neurodegenerative disease that may cause neurotoxicity and imbalance in gut microbiota. A polysaccharide derived from Sparassis crispa-1 (SCP-1) acts as a neuroprotective agent in vitro. There is, however, no clarity on the mechanism responsible for SCP-1's neuroprotective effects against AD. In this study, C57BL/6J male mice were treated with D-galactose and AlCl₃ to establish an animal model of AD, followed by treatment with SCP-1. As evidenced by behavioral tests and brain pathology, SCP-1 treatment ameliorated learning deficits and defective spatial recognition, reduced amyloidogenesis, and modulated the neurotransmitter levels (γ-aminobutyric acid, glutamate, and acetylcholine) in the brain of AD mice. The results of 16S rRNA sequencing revealed that SCP-1 reshaped the gut microbiota composition, especially by promoting the proliferation of butyrate-producing genera, such as Intestinaimonas, [Eubacterium] ventriosum group, Lachnospiraceae_UCG_010, and Lachnospiraceae_UCG_001, and suppressing the growth of inflammation-related bacteria (i.e., Escherichia/Shigella). Furthermore, SCP-1 significantly attenuated inflammation by reducing the levels of inflammatory cytokines, maintaining intestinal barrier function, inhibiting glial activation, and decreasing the expression of toll-like receptor 4 (TLR4) and nuclear factor-κB (NF-κB). Collectively, our findings suggest that SCP-1 may prevent the development of AD via modulation of gut microbiota and suppression of inflammation, for a potential application in preventing or managing AD.

Prophylactic Effect of Bovine Colostrum on Intestinal Microbiota and Behavior in Wild-Type and Zonulin Transgenic Mice

The microbiota-gut-brain axis (MGBA) involves bidirectional communication between intestinal microbiota and the gastrointestinal (GI) tract, central nervous system (CNS), neuroendocrine/neuroimmune systems, hypothalamic-pituitary-adrenal (HPA) axis, and enteric nervous system (ENS). The intestinal microbiota can influence host physiology and pathology. Dysbiosis involves the loss of beneficial microbial input or signal, diversity, and expansion of pathobionts, which can lead to loss of barrier function and increased intestinal permeability (IP). Colostrum, the first milk from mammals after birth, is a natural source of nutrients and is rich in oligosaccharides, immunoglobulins, growth factors, and anti-microbial components. The aim of this study was to investigate if bovine colostrum (BC) administration might modulate intestinal microbiota and, in turn, behavior in two mouse models, wild-type (WT) and Zonulin transgenic (Ztm)-the latter of which is characterized by dysbiotic microbiota, increased intestinal permeability, and mild hyperactivity-and to compare with control mice. Bioinformatics analysis of the microbiome showed that consumption of BC was associated with increased taxonomy abundance (p = 0.001) and diversity (p = 0.004) of potentially beneficial species in WT mice and shifted dysbiotic microbial community towards eubiosis in Ztm mice (p = 0.001). BC induced an anxiolytic effect in WT female mice compared with WT female control mice (p = 0.0003), and it reduced anxiogenic behavior in Ztm female mice compared with WT female control mice (p = 0.001), as well as in Ztm male mice compared with WT BC male mice (p = 0.03). As evidenced in MGBA interactions, BC supplementation may well be applied for prophylactic approaches in the future. Further research is needed to explore human interdependencies between intestinal microbiota, including eubiosis and pathobionts, and neuroinflammation, and the potential value of BC for human use. The MGH Institutional Animal Care and Use Committee authorized the animal study (2013N000013).

Psychobiotics and Elderly Health

While aging with physiological dimensions refers to the changes seen with chronological age, on the other hand, aging with psychological dimensions refers to the change of humans’ capacity to adaptively. Such as learning, psychomotor, problem-solving and personality traits. With the improvement of life quality in recent years, the average life expectancy and therefore the incidence of neurodegenerative diseases among the elderly have also increased. Although the aging process is universal, progressive, gradual and unstoppable, human gut microbiota-targeted aging management is a new approach to health and anti-aging. Nutrition plays a big factor in the elderly population with providing adequate cognitive and physical functions and when taking the right nutrition it also reduces the risk of chronic diseases. When adding functional foods into the diet, it can play a significant role to reduce the risk of diet-related diseases. Such as probiotics and prebiotics. In recent years, a new subclass of probiotics called ‘psychobiotics’ has emerged. These psychobiotics are defined as probiotics that, when taken in appropriate amounts, it creates positive psychiatric effects in human psychopathology. Examination of this new class of probiotics provides a glimmer of hope for the effective management of neurodegenerative diseases and various psychiatric disorders, especially with increasing life expectancy. Also, recommending the use of probiotics in old age will contribute to the treatment of some health problems related to aging.

High-yield production and purification of prebiotic inulin-type fructooligosaccharides

Due to the health-promoting effects and functional properties of inulin-type fructooligosaccharides (I-FOS), the global market for I-FOS is constantly growing. Hence, there is a continuing demand for new, efficient biotechnological approaches for I-FOS production. In this work, crude inulosucrase InuGB-V3 from Lactobacillus gasseri DSM 20604 was used to synthesize I-FOS from sucrose. Supplementation with 1 mM CaCl2, a pH of 3.5–5.5, and an incubation temperature of 40 °C were found to be optimal production parameters at which crude inulosucrase showed high conversion rates, low sucrose hydrolysis, and excellent stability over 4 days. The optimal process conditions were employed in cell-free bioconversion reactions. By elevating the substrate concentration from 570 to 800 g L−1, the I-FOS concentration and the synthesis of products with a low degree of polymerization (DP) could be increased, while sucrose hydrolysis was decreased. Bioconversion of 800 g L−1 sucrose for 20 h resulted in an I-FOS-rich syrup with an I-FOS concentration of 401 ± 7 g L−1 and an I-FOS purity of 53 ± 1% [w/w]. I-FOS with a DP of 3–11 were synthesized, with 1,1-kestotetraose (DP4) being the predominant transfructosylation product. The high-calorie sugars glucose, sucrose, and fructose were removed from the generated I-FOS-rich syrup using activated charcoal. Thus, 81 ± 5% of the initially applied I-FOS were recovered with a purity of 89 ± 1%.

A review of the preclinical and clinical studies on the role of the gut microbiome in aging and neurodegenerative diseases and its modulation

As the world population ages, the burden of age-related health problems grows, creating a greater demand for new novel interventions for healthy aging. Advancing aging is related to a loss of beneficial mutualistic microbes in the gut microbiota caused by extrinsic and intrinsic factors such as diet, sedentary lifestyle, sleep deprivation, circadian rhythms, and oxidative stress, which emerge as essential elements in controlling and prolonging life expectancy of healthy aging. This condition is known as gut dysbiosis, and it affects normal brain function via the brain-gut microbiota (BGM) axis, which is a bidirectional link between the gastrointestinal tract (GIT) and the central nervous system (CNS) that leads to the emergence of brain disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and frontotemporal dementia (FTD). Here, we reviewed the role of the gut microbiome in aging and neurodegenerative diseases, as well as provided a comprehensive review of recent findings from preclinical and clinical studies to present an up-to-date overview of recent advances in developing strategies to modulate the intestinal microbiome by probiotic administration, dietary intervention, fecal microbiota transplantation (FMT), and physical activity to address the aging process and prevent neurodegenerative diseases. The findings of this review will provide researchers in the fields of aging and the gut microbiome design innovative studies that leverage results from preclinical and clinical studies to better understand the nuances of aging, gut microbiome, and neurodegenerative diseases.

The gut microbiome and Alzheimer's disease: Complex and bidirectional interactions

Structural and functional alterations to the gut microbiome, referred to as gut dysbiosis, have emerged as potential key mediators of neurodegeneration and Alzheimer disease (AD) pathogenesis through the "gut -brain" axis. Emerging data from animal and clinical studies support an important role for gut dysbiosis in mediating neuroinflammation, central and peripheral immune dysregulation, abnormal brain protein aggregation, and impaired intestinal and brain barrier permeability, leading to neuronal loss and cognitive impairment. Gut dysbiosis has also been shown to directly influence various mechanisms involved in neuronal growth and repair, synaptic plasticity, and memory and learning functions. Aging and lifestyle factors including diet, exercise, sleep, and stress influence AD risk through gut dysbiosis. Furthermore, AD is associated with characteristic gut microbial signatures which offer value as potential markers of disease severity and progression. Together, these findings suggest the presence of a complex bidirectional relationship between AD and the gut microbiome and highlight the utility of gut modulation strategies as potential preventative or therapeutic strategies in AD. We here review the current literature regarding the role of the gut-brain axis in AD pathogenesis and its potential role as a future therapeutic target in AD treatment and/or prevention.

The effects and significance of gut microbiota and its metabolites on the regulation of osteoarthritis: Close coordination of gut-bone axis

Osteoarthritis (OA) is a common chronic degenerative disease of articular cartilage in middle-aged and older individuals, which can result in the joint pain and dysfunction, and even cause the joint deformity or disability. With the enhancing process of global aging, OA has gradually become a major public health problem worldwide. Explaining pathogenesis of OA is critical for the development of new preventive and therapeutic interventions. In recent years, gut microbiota (GM) has been generally regarded as a “multifunctional organ,” which is closely relevant with a variety of immune, metabolic and inflammatory functions. Meanwhile, more and more human and animal researches have indicated the existence of gut-bone axis and suggested that GM and its metabolites are closely involved in the pathogenic process of OA, which might become a potential and promising intervention target. Based on the close coordination of gut-bone axis, this review aims to summarize and discuss the mechanisms of GM and its metabolites influencing OA from the aspects of the intestinal mucosal barrier modulation, intestinal metabolites modulation, immune modulation and strategies for the prevention or treatment of OA based on perspectives of GM and its metabolites, thus providing a profound knowledge and recognition of it.

Microbiome-Based Therapies in Parkinson's Disease: Can Tuning the Microbiota Become a Viable Therapeutic Strategy?

Progressive neurodegenerative disorders such as Parkinson's disease (PD) have continued to baffle medical science, despite strides in the understanding of their pathology. The inability of currently available therapies to halt disease progression is a testament to an incomplete understanding of pathways crucial to disease initiation, progression and management. Science has continued to link the activities and equilibrium of the gut microbiome to the health and proper functioning of brain neurons. They also continue to stir interest in the potential applications of technologies that may shift the balance of the gut microbiome towards achieving a favourable outcome in PD management. There have been suggestions that an improved understanding of the roles of the gut microbiota is likely to lead to the emergence of an era where their manipulation becomes a recognized strategy for PD management. This review examines the current state of our journey in the quest to understand how the gut microbiota can influence several aspects of PD. We highlight the relationship between the gut microbiome/microbiota and PD pathogenesis, as well as preclinical and clinical evidence evaluating the effect of postbiotics, probiotics and prebiotics in PD management. This is with a view to ascertaining if we are at the threshold of discovering the application of a usable tool in our quest for disease modifying therapies in PD.

Effect of Tanshinone IIA on Gut Microbiome in Diabetes-Induced Cognitive Impairment

Diabetes-induced cognitive impairment (DCI) presents a major public health risk among the aging population. Previous clinical attempts on known therapeutic targets for DCI, such as depleted insulin secretion, insulin resistance, and hyperglycaemia have delivered poor patient outcomes. However, recent evidence has demonstrated that the gut microbiome plays an important role in DCI by modulating cognitive function through the gut–brain crosstalk. The bioactive compound tanshinone IIA (TAN) has shown to improve cognitive and memory function in diabetes mellitus models, though the pharmacological actions are not fully understood. This study aims to investigate the effect and underlying mechanism of TAN in attenuating DCI in relation to regulating the gut microbiome. Metagenomic sequencing analyses were performed on a group of control rats, rats with diabetes induced by a high-fat/high-glucose diet (HFD) and streptozotocin (STZ) (model group) and TAN-treated diabetic rats (TAN group). Cognitive and memory function were assessed by the Morris water maze test, histopathological assessment of brain tissues, and immunoblotting of neurological biomarkers. The fasting blood glucose (FBG) level was monitored throughout the experiments. The levels of serum lipopolysaccharide (LPS) and tumor necrosis factor-α (TNF-α) were measured by enzyme-linked immunoassays to reflect the circulatory inflammation level. The morphology of the colon barrier was observed by histopathological staining. Our study confirmed that TAN reduced the FBG level and improved the cognitive and memory function against HFD- and STZ-induced diabetes. TAN protected the endothelial tight junction in the hippocampus and colon, regulated neuronal biomarkers, and lowered the serum levels of LPS and TNF-α. TAN corrected the reduced abundance of Bacteroidetes in diabetic rats. At the species level, TAN regulated the abundance of B. dorei, Lachnoclostridium sp. YL32 and Clostridiodes difficile. TAN modulated the lipid metabolism and biosynthesis of fatty acids in related pathways as the main functional components. TAN significantly restored the reduced levels of isobutyric acid and butyric acid. Our results supported the use of TAN as a promising therapeutic agent for DCI, in which the underlying mechanism may be associated with gut microbiome regulation.

Morais L. Convergent pathways of the gut microbiota-brain axis and neurodegenerative disorders

Recent research has been uncovering the role of the gut microbiota for brain health and disease. These studies highlight the role of gut microbiota on regulating brain function and behavior through immune, metabolic, and neuronal pathways. In this review we provide an overview of the gut microbiota axis pathways to lay the groundwork for upcoming sessions on the links between the gut microbiota and neurogenerative disorders. We also discuss how the gut microbiota may act as an intermediate factor between the host and the environment to mediate disease onset and neuropathology. Based on the current literature, we further examine the potential for different microbiota-based therapeutic strategies to prevent, to modify, or to halt the progress of neurodegeneration.

Effect of dendrobium mixture in alleviating diabetic cognitive impairment associated with regulating gut microbiota

Dendrobium mixture (DM) is a patent Chinese herbal formulation consisting of Dendrobii Caulis, Astragali Radix, Rehmanniae Radix as the main ingredients. DM has been shown to alleviate diabetic related symptoms attributed to its anti-hyperglycaemic and anti-inflammatory activities. However, the effect on diabetic induced cognitive dysfunction has not been investigated. This study aims to investigate the effect of DM in improving diabetic cognitive impairment and associated mechanisms. Our study confirmed the anti-hyperglycaemic effect of DM and showed its capacity to restore the cognitive and memory function in high fat/high glucose and streptozotocin-induced diabetic rats. The neuroprotective effect was manifested as improved learning and memory behaviours, restored blood-brain barrier tight junction, and enhanced expressions of neuronal survival related biomarkers. DM protected the colon tight junction, and effectively lowered the circulated proinflammatory mediators including tumour necrosis factor-α, interleukin-6 and lipopolysaccharides. In the gut microbiota, DM corrected the increase in the abundance of Firmicutes, the increase in the ratio of Firmicutes/Bacteroidetes, and the decrease in the abundance of Bacteroidetes in diabetic rats. It also reversed the abundance of Lactobacillus, Ruminococcus and Allobaculum genera. Short chain fatty acids, isobutyric acid and ethylmethylacetic acid, were negatively and significantly correlated to Ruminococcus and Allobaculum. Isovaleric acid was positively and significantly correlated with Lactobacillus, which all contributing to the improvement in glucose level, systemic inflammation and cognitive function in diabetic rats. Our results demonstrated the potential of DM as a promising therapeutic agent in treating diabetic cognitive impairment and the underlying mechanism may be associated with regulating gut microbiota.

Gut Microbiota Modification via Glucagon-like Peptide-1 with Beneficial Neuroprotective Effects

BACKGROUND: In recent decades, it has been shown that the association between intestinal bacterial imbalance (dysbiosis) and various diseases such as type 2 diabetes can play a role in the development of Alzheimer's and Parkinson's diseases. In this study, the beneficial effects of intestinal microbiota glucagon-like peptide 1 (GLP-1) in cognitive disorders were investigated. METHODS: PubMed-Medline, Web of Science, and Scopus were searched to identify experimental studies based on the bacterial strains along with GLP-1 1 expression in preventing or reducing cognitive impairment. Of the 233 studies, six were eligible for inclusion, and the Systematic Review Centre for Laboratory animal Experimentation (SYRCLE) risk of bias tool was used to evaluate the risk of bias in individual studies. RESULTS: The results showed that intestinal expression of GLP-1 1 could reduce the intestinal pathogenic genus such as Enterobacteriaceae and was obviously associated with a greater number of beneficial genera such as Lactobacillus and Akkermansia. Also, the neuroprotective effects of Clostridium butyricum with GLP-1 1 in a mice were approved. Therefore, the modulation of the intestinal microbiota, mediated by an increase in the intestinal GLP-1 1 level, consequently improved cognitive function. CONCLUSION: In this review, we have indicated that the gut microbiota, by stimulating the expression of the intestinal hormones like GLP-1 1, and also with a beneficial effect in inhibiting some involved genes in inflammation, can declined the development of cognitive disorders.

Novel Nutraceutical Compounds in Alzheimer Prevention

Alzheimer's disease (AD) incidence is increasing worldwide at an alarming rate. Considering this increase, prevention efforts, stemming from scientific research, health education, and public policies, are critical. Clinical studies evidenced that healthy lifestyles along with natural multitarget and disease-modifying agents have a preventative impact on AD or mitigate symptoms in diagnosed patients. The pathological alterations of AD start 30 years before symptoms, and it is essential to develop the capacity to detect those changes. In this regard, molecular biomarkers that detect early pathological manifestations are helpful. Based on markers data, early preventive interventions could reduce more than 40% of AD cases. Protective actions include exercise, shown to induce neurogenesis, cognitive stimulation, intellectual-social activity, and nutrition among others. Mediterranean diet, preprobiotics, and nutraceuticals containing bioactive molecules with antioxidant and anti-inflammatory properties are relevant. Antiprotein aggregation molecules whose mechanisms were described are important. Anti-inflammatory agents with anti-aggregation properties that help to control cognitive impairment, include quercetin, biocurcumin, rosemarinic acid, and Andean shilajit. Anthocyanidins, e.g., delphinidin, malvidin, and natural flavonoids, are also included. Quercetin and hydroxy-tyrosol are antiaging molecules and could have anti-AD properties. We emphasize the relevance of nutraceuticals as a main actor in the prevention and/or control of dementia and particularly AD.

Correlation between green tea polyphenols regulating intestinal bacteriophage and flora diversity in SPF mice

Green tea polyphenols (GTP) play an important role in shaping the gut microbiome, comprising of a range of densely colonizing microorganisms, including bacteriophages. Previous studies focused on the effect of...

The Gut Microbiota-Brain Axis: A New Frontier on Neuropsychiatric Disorders

Alzheimer's disease (AD) is a progressive and incurable neurodegenerative disorder of integrative areas of the brain, characterized by cognitive decline and disability resulting in negative impacts on the family of the patients and the health care services worldwide. AD involves oxidative stress, neuroinflammation and accelerated apoptosis, accompanied by deposition of amyloid-β peptide plaques and tau protein-based neurofibrillary tangles in the central nervous system. Among the multiple factors that contribute to the onset and evolution of this disease, aging stands out. That is why the prevalence of this disease has increased due to the constant increase in life expectancy. In the hope of finding new, more effective methods to slow the progression of this disease, over the last two decades, researchers have promoted "omics"-based approaches that include the gut microbiota and their reciprocal interactions with different targets in the body. This scientific advance has also led to a better understanding of brain compartments and the mechanisms that affect the integrity of the blood-brain barrier. This review aims to discuss recent advances related to the gut-brain-microbiota axis in AD. Furthermore, considering that AD involves psychiatric symptoms, this review also focuses on the psychiatric factors that interact with this axis (an issue that has not yet been sufficiently addressed in the literature).

Functional roles of the microbiota-gut-brain axis in Alzheimer’s disease: Implications of gut microbiota-targeted therapy

Increasing scientific evidence demonstrates that the gut microbiota influences normal physiological homeostasis and contributes to pathogenesis, ranging from obesity to neurodegenerative diseases, such as Alzheimer’s disease (AD). Gut microbiota can interact with the central nervous system (CNS) through the microbiota-gut-brain axis. The interaction is mediated by microbial secretions, metabolic interventions, and neural stimulation. Here, we review and summarize the regulatory pathways (immune, neural, neuroendocrine, or metabolic systems) in the microbiota-gut-brain axis in AD pathogenesis. Besides, we highlight the significant roles of the intestinal epithelial barrier and blood–brain barrier (BBB) in the microbiota-gut-brain axis. During the progression of AD, there is a gradual shift in the gut microbiota and host co-metabolic relationship, leading to gut dysbiosis, and the imbalance of microbial secretions and metabolites, such as lipopolysaccharides (LPS) and short-chain fatty acids (SCFAs). These products may affect the CNS metabolic state and immune balance through the microbiota-gut-brain axis. Further, we summarize the potential microbiota-gut-brain axis-targeted therapy including carbohydrates, probiotics, dietary measures, and propose new strategies toward the development of anti-AD drugs. Taken together, the data in this review suggest that remodeling the gut microbiota may present a tractable strategy in the management and development of new therapeutics against AD and other neurodegenerative diseases.