Gut Microbiota and Metabolome Alterations Associated with Parkinson's Disease

Gut microbiota modulates neurotransmitter and gut-brain signaling

Neurotransmitters, including 5-hydroxytryptamine (5-HT), dopamine (DA), gamma-aminobutyric acid (GABA), and glutamate, are essential transductors in the Gut-Brain Axis (GBA), playing critical roles both peripherally and centrally. Accumulating evidence suggests that the gut microbiota modulates intestinal neurotransmitter metabolism and gut-to-brain signaling, shedding light on the crucial role of the gut microbiota in brain function and the pathogenesis of various neuropsychiatric diseases, such as major depression disorder (MDD), anxiety, addiction and Parkinson's disease (PD). Despite the exciting findings, the mechanisms underlying the modulation of neurotransmitter metabolism and function by the gut microbiota are still being elucidated. In this review, we aim to provide a comprehensive overview of the existing knowledge about the role of the gut microbiota in neurotransmitter metabolism and function in animal and clinical experiments. Moreover, we will discuss the potential mechanisms through which gut microbiota-derived neurotransmitters contribute to the pathogenesis of neuropsychiatric diseases, thus highlighting a novel therapeutic target for these conditions.

Ageing, proteostasis, and the gut: Insights into neurological health and disease

Recent research has illuminated the profound bidirectional communication between the gastrointestinal tract and the brain, furthering our understanding of neurological ailments facilitating possible therapeutic strategies. Technological advancements in high-throughput sequencing and multi-omics have unveiled significant alterations in gut microbiota and their metabolites in various neurological disorders. This review provides a thorough analysis of the role of microbiome-gut-brain axis in neurodegenerative disease pathology, linking it to reduced age-associated proteostasis. We discuss evidences that substantiate the existence of a gut-brain cross talk ranging from early clinical accounts of James Parkinson to Braak's hypothesis. In addition to understanding of microbes, the review particularly entails specific metabolites which are altered in neurodegenerative diseases. The regulatory effects of microbial metabolites on protein clearance mechanisms, proposing their potential therapeutic implications, are also discussed. By integrating this information, we advocate for a combinatory therapeutic strategy that targets early intervention, aiming to restore proteostasis and ameliorate disease progression. This approach not only provides a new perspective on the pathogenesis of neurodegenerative diseases but also highlights innovative strategies to combat the increasing burden of these age-related disorders.

The role of gut-derived short-chain fatty acids in Parkinson's disease

The emerging function of short-chain fatty acids (SCFAs) in Parkinson's disease (PD) has been investigated in this article. SCFAs, which are generated via the fermentation of dietary fiber by gut microbiota, have been associated with dysfunction of the gut-brain axis and, neuroinflammation. These processes are integral to the development of PD. This article examines the potential therapeutic implications of SCFAs in the management of PD, encompassing their capacity to modulate gastrointestinal permeability, neuroinflammation, and neuronal survival, by conducting an extensive literature review. As a whole, this article emphasizes the potential therapeutic utility of SCFAs as targets for the management and treatment of PD.

Modulating the biosynthesis and TLR4-interaction of lipopolysaccharide as an approach to counter gut dysbiosis and Parkinson's disease: Role of phyto-compounds

The prevalence of the world's second leading neurodegenerative disorder Parkinson's disease (PD) is well known while its pathogenesis is still a topical issue to explore. Clinical and experimental reports suggest the prevalence of disturbed gut microflora in PD subjects, with an abundance of especially Gram-negative bacteria. The endotoxin lipopolysaccharide (LPS) released from the outer cell layer of these bacteria interacts with the toll-like receptor 4 (TLR4) present on the macrophages and it stimulates the downstream inflammatory cascade in both the gut and brain. Recent research also suggests a positive correlation between LPS, alpha-synuclein, and TLR4 levels, which indicates the contribution of a parallel LPS-alpha-synuclein-TLR4 axis in stimulating inflammation and neurodegeneration in the gut and brain, establishing a body-first type of PD. However, owing to the novelty of this paradigm, further investigation is mandatory. Modulating LPS biosynthesis and LPS-TLR4 interaction can ameliorate gut dysbiosis and PD. Several synthetic LpxC (UDP-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase; LPS-synthesizing enzyme) inhibitors and TLR4 antagonists are reported to show beneficial effects including neuroprotection in PD models, however, are not devoid of side effects. Plant-derived compounds have been long documented for their benefits as nutraceuticals and thus to search for effective, safer, and multitarget therapeutics, the present study focused on summarizing the evidence reporting the potential of phyto-compounds as LpxC inhibitors and TLR4 antagonists. Studies demonstrating the dual potential of phyto-compounds as the modulators of LpxC and TLR4 have not yet been reported. Also, very few preliminary studies have reported LpxC inhibition by phyto-compounds. Nevertheless, remarkable neuroprotection along with TLR4 antagonism has been shown by curcumin and juglanin in PD models. The present review thus provides a wide look at the research progressed to date in discovering phyto-compounds that can serve as LpxC inhibitors and TLR4 antagonists. The study further recommends the need for expanding the search for potential candidates that can render dual protection by inhibiting both the biosynthesis and TLR4 interaction of LPS. Such multitarget therapeutic intervention is believed to bring fruitful yields in countering gut dysbiosis, neuroinflammation, and dopaminergic neuron damage in PD patients through a single treatment paradigm.

Influence of human gut microbiome on the healthy and the neurodegenerative aging

The gut microbiome plays a crucial role in host health throughout the lifespan by influencing brain function during aging. The microbial diversity of the human gut microbiome decreases during the aging process and, as a consequence, several mechanisms increase, such as oxidative stress, mitochondrial dysfunction, inflammatory response, and microbial gut dysbiosis. Moreover, evidence indicates that aging and neurodegeneration are closely related; consequently, the gut microbiome may serve as a novel marker of lifespan in the elderly. In this narrative study, we investigated how the changes in the composition of the gut microbiome that occur in aging influence to various neuropathological disorders, such as mild cognitive impairment (MCI), dementia, Alzheimer's disease (AD), and Parkinson's disease (PD); and which are the possible mechanisms that govern the relationship between the gut microbiome and cognitive impairment. In addition, several studies suggest that the gut microbiome may be a potential novel target to improve hallmarks of brain aging and to promote healthy cognition; therefore, current and future therapeutic interventions have been also reviewed.

The gut microbiome: an important role in neurodegenerative diseases and their therapeutic advances

There are complex interactions between the gut and the brain. With increasing research on the relationship between gut microbiota and brain function, accumulated clinical and preclinical evidence suggests that gut microbiota is intimately involved in the pathogenesis of neurodegenerative diseases (NDs). Increasingly studies are beginning to focus on the association between gut microbiota and central nervous system (CNS) degenerative pathologies to find potential therapies for these refractory diseases. In this review, we summarize the changes in the gut microbiota in Alzheimer's disease, Parkinson's disease, multiple sclerosis, and amyotrophic lateral sclerosis and contribute to our understanding of the function of the gut microbiota in NDs and its possible involvement in the pathogenesis. We subsequently discuss therapeutic approaches targeting gut microbial abnormalities in these diseases, including antibiotics, diet, probiotics, and fecal microbiota transplantation (FMT). Furthermore, we summarize some completed and ongoing clinical trials of interventions with gut microbes for NDs, which may provide new ideas for studying NDs.

Gut Microbes Associated with Neurodegenerative Disorders: A Comprehensive Review of the Literature

Evidence shows that neurodegenerative and neuropsychiatric disorders are influenced by alterations in the gut microbiome. Various diseases have been linked to microbiome dysbiosis, yet there are inconclusive data regarding which microorganisms are associated with each disorder. The aim of our study is to systematically review the recent literature of the past decade to clarify whether the gut microbiome contributes to the understanding of pathogenesis and progression of neurodegenerative disorders. Most included studies showed a strong correlation between the relative abundance of certain microorganisms, mainly species of the phyla Firmicutes and Bacteroidetes, and disorders such as Parkinson's disease (PD) and Alzheimer's disease (AD). It is speculated that the microorganisms and their byproducts have a significant role in brain protein accumulation, neuro-inflammation, and gut permeability. The estimation of microbial populations could potentially improve clinical outcomes and hinder the progression of the disease. However, further research is needed to include more diseases and larger patient samples and identify specific species and subspecies associated with these disorders.

The Gut Microbiome as a Catalyst and Emerging Therapeutic Target for Parkinson's Disease: A Comprehensive Update

Parkinson's Disease is the second most prevalent neurological disorder globally, and its cause is still largely unknown. Likewise, there is no cure, and existing treatments do little more than subdue symptoms before becoming ineffective. It is increasingly important to understand the factors contributing to Parkinson's Disease aetiology so that new and more effective pharmacotherapies can be established. In recent years, there has been an emergence of research linking gut dysbiosis to Parkinson's Disease via the gut-brain axis. Advancements in microbial profiling have led to characterisation of a Parkinson's-specific microbial signature, where novel treatments that leverage and correct gut dysbiosis are beginning to emerge for the safe and effective treatment of Parkinson's Disease. Preliminary clinical studies investigating microbiome-targeted therapeutics for Parkinson's Disease have revealed promising outcomes, and as such, the aim of this review is to provide a timely and comprehensive update of the most recent advances in this field. Faecal microbiota transplantation has emerged as a novel and potential frontrunner for microbial-based therapies due to their efficacy in alleviating Parkinson's Disease symptomology through modulation of the gut-brain axis. However, more rigorous clinical investigation, along with technological advancements in diagnostic and in vitro testing tools, are critically required to facilitate the widespread clinical translation of microbiome-targeting Parkinson's Disease therapeutics.

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.

Bisphenol S exposure induces intestinal inflammation via altering gut microbiome

Bisphenol S (BPS), a substitute for bisphenol A, is widely used in the manufacture of food packaging materials, raising concern over its toxicity. However, evidence is still lacking on whether gut microbiota involved in BPS induced intestinal inflammation in mammals, as well as its underlying mechanism. Using mouse BPS exposure model, we found intestinal inflammation characterized by shortened colon length, crypt distortion, macrophage accumulation and increased apoptosis. As for gut microbiota, 16s rRNA gene amplicon sequencing showed BPS exposure induced gut dysbiosis, including increased pro-inflammatory microbes such as Ileibacterium, and decreased anti-inflammatory genera such as Lactobacillus, Blautia and Romboutsia. Besides, LC-MS/MS-based untargeted metabolomic analysis indicated BPS impaired both bacteria and host metabolism. Additionally, transcriptome analysis of the intestine revealed abnormal gene expression in intestinal mucosal barrier and inflammation. More importantly, treating mice with antibiotics significantly attenuated BPS-induced gut inflammation via the regulation of both bacterial and host metabolites, indicating the role of gut microbiota. Collectively, BPS exposure induces intestinal inflammation via altering gut microbiota in mouse. This study provides the possibility of madecassic acid, an anti-inflammatory metabolite, to prevent BPS-induced intestinal inflammation and also new insights in understanding host-microbiota interaction in BPS toxicity.

The role of HLA-DR on plasmacytoid dendritic cells in mediating the effects of Butyrivibrio gut microbiota on Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is viewed as a progressively deteriorating neurodegenerative disorder, the exact etiology of which remains not fully deciphered to this date. The gut microbiota could play a crucial role in PD development by modulating the human immune system.

OBJECTIVE

This study aims to explore the relationship between gut microbiota and PD, focusing on how immune characteristics may both directly and indirectly influence their interaction.

METHODS

Utilizing cumulative data from genome-wide association studies (GWAS), our research conducted a two-sample Mendelian randomization (MR) analysis to clarify the association between the gut microbiome and PD. Additionally, by employing a two-step MR approach, we assessed the impact of gut microbiota on PD development via immune characteristics and quantified HLA-DR mediation effect on plasmacytoid dendritic cells (pDCs).

RESULTS

We discovered significant associations between PD and microbiota, comprising one class, one order, two families, and two genera. Furthermore, we explored the extent to which HLA-DR on pDCs mediates the effect of Butyrivibrio gut microbiota on PD.

CONCLUSION

Our study emphasizes the complex interactions between the gut microbiota, immune characteristics, and PD. The relationships and intermediary roles identified in our research provide important insights for developing potential therapies that target the gut microbiome to alleviate symptoms in PD patients.

Association between environmental phthalates exposure and gut microbiota and metabolome in dementia with Lewy bodies

BACKGROUND

Emerging evidence has shown the potential involvement of phthalates (PAEs) exposure in the development of dementia with Lewy bodies (DLB). Metabolomics can reflect endogenous metabolites variation in the progress of disease after chemicals exposure. However, little is known about the association between PAEs, gut microbiota and metabolome in DLB.

OBJECTIVE

We aim to explore the intricate relationship among urinary PAEs metabolites (mPAEs), dysbiosis of gut bacteria, and metabolite profiles in DLB.

METHODS

A total of 43 DLB patients and 45 normal subjects were included in this study. Liquid chromatography was used to analyze the levels of mPAEs in the urine of the two populations. High-throughput sequencing and liquid chromatography-mass spectrometry were used to analyze gut microbiota and the profile of gut metabolome, respectively. The fecal microbiota transplantation (FMT) experiment was performed to verify the potential role of mPAEs on gut dysbiosis contribute to aggravating cognitive dysfunction in α-synuclein tg DLB/PD mice.

RESULTS

The DLB patients had higher DEHP metabolites (MEOHP, MEHHP and MEHP), MMP and MnBP, lower MBP and MBzP than the control group and different microbiota. A significantly higher abundance of Ruminococcus gnavus and lower Prevotella copri, Prevotella stercorea and Bifidobacterium were observed in DLB. Higher 3 DEHP metabolites, MMP, MnBP and lower MBP and MBzP were significantly negatively associated with Prevotella copri, Prevotella stercorea and Bifidobacterium. Additionally, using metabolomics, we found that altered bile acids, short-chain fatty acids and amino acids metabolism are linked to these mPAEs. We further found that FMT of fecal microbiota from highest DEHP metabolites donors significantly impaired cognitive function in the germ-free DLB/PD mice.

CONCLUSION

Our study suggested that PAEs exposure may alter the microbiota-gut-brain axis and providing novel insights into the interactions among environmental perturbations and microbiome-host in pathogenesis of DLB.

Association between dietary niacin intake and risk of Parkinson's disease in US adults: cross-sectional analysis of survey data from NHANES 2005-2018

Parkinson's disease (PD) is one of the most common neurodegenerative diseases and involves various pathogenic mechanisms, including oxidative stress and neuroinflammation. Niacin, an important cofactor in mitochondrial energy metabolism, may play a key role in the pathogenesis of PD. An in-depth exploration of the relationship between niacin and mitochondrial energy metabolism may provide new targets for the treatment of PD. The present study was designed to examine the association between dietary niacin intake and the risk of PD in US adults. Data from adults aged 40 years and older collected during cycles of the United States (US) National Health and Nutrition Examination Survey (NHANES) from 2005 to 2018 were used. A multiple logistic regression model was used to analyze the relationship between dietary niacin intake and the risk of PD. Further linear tests using restricted cubic splines (RCS) were performed to explore the shape of the dose-response relationship. Subgroup stratification and interaction analyses were conducted according to years of education, marital status, smoking, and hypertension to evaluate the stability of the association between different subgroups. A total of 20,211 participants were included in this study, of which 192 were diagnosed with PD. In the fully adjusted multiple logistic regression model, dietary niacin intake was negatively associated with the risk of PD (OR: 0.77, 95%CI: 0.6-0.99; p = 0.042). In the RCS linear test, the occurrence of PD was negatively correlated with dietary niacin intake (nonlinearity: p = 0.232). In stratified analyses, dietary niacin intake was more strongly associated with PD and acted as an important protective factor in patients with fewer years of education (OR: 0.35, 95%CI: 0.13-0.93), married or cohabitating (OR: 0.71, 95%CI: 0.5-0.99), taking dietary supplements (OR: 0.6, 95%CI: 0.37 0.97), non-smokers (OR: 0.57, 95%CI: 0.39-0.85), those with hypertension (OR: 0.63, 95%CI: 0.63-0.95), coronary artery disease (OR: 0.77, 95%CI: 0.6-1), and stroke (OR: 0.75, 95%CI: 0.88-0.98), but the interaction was not statistically significant in all subgroups. Dietary niacin intake was inversely associated with PD risk in US adults, with a 23% reduction in risk for each 10 mg increase in niacin intake.

Causal association between phenylalanine and Parkinson's disease: a two-sample bidirectional mendelian randomization study

Background

Research findings indicate a putative indirect or latent association between phenylalanine (Phe) and Parkinson's disease (PD). In this study, we aimed to analyze the causal relationship between Phe and PD by two sample Mendelian randomization (MR) analysis.

Methods

In this study, the PD-related dataset and Phe-related dataset were downloaded from Integrative Epidemiology U1nit (IEU) Open Genome-Wide Association Study (GWAS) database. Four algorithms (MR Egger, maximum likelihood, inverse variance weighting (IVW) and unweighted regression) were used to perform MR analysis. The sensitivity analysis (heterogeneity test, horizontal pleiotropy test and Leave-One-Out (LOO) analysis) was used to assess the reliability of MR analyses.

Results

In the forward MR analysis, Phe was a safety factor for PD (p-value < 0.05 and odds ratios (OR) < 1). The results of reverse MR analysis showed that there was no causal relationship between PD and Phe (p-value > 0.05). In addition, sensitivity analysis showed that MR analysis was reliable.

Conclusion

The results of this study revealed that Phe was a safety factor for PD, meaning that Phe reduced the risk of PD.

Identification of metabolites reproducibly associated with Parkinson's Disease via meta-analysis and computational modelling

Many studies have reported metabolomic analysis of different bio-specimens from Parkinson's disease (PD) patients. However, inconsistencies in reported metabolite concentration changes make it difficult to draw conclusions as to the role of metabolism in the occurrence or development of Parkinson's disease. We reviewed the literature on metabolomic analysis of PD patients. From 74 studies that passed quality control metrics, 928 metabolites were identified with significant changes in PD patients, but only 190 were replicated with the same changes in more than one study. Of these metabolites, 60 exclusively increased, such as 3-methoxytyrosine and glycine, 54 exclusively decreased, such as pantothenic acid and caffeine, and 76 inconsistently changed in concentration in PD versus control subjects, such as ornithine and tyrosine. A genome-scale metabolic model of PD and corresponding metabolic map linking most of the replicated metabolites enabled a better understanding of the dysfunctional pathways of PD and the prediction of additional potential metabolic markers from pathways with consistent metabolite changes to target in future studies.

Longitudinal microbiome investigation throughout prion disease course reveals pre- and symptomatic compositional perturbations linked to short-chain fatty acid metabolism and cognitive impairment in mice

Commensal intestinal bacteria shape our microbiome and have decisive roles in preserving host metabolic and immune homeostasis. They conspicuously impact disease development and progression, including amyloid-beta (Aβ) and alpha (α)-synuclein pathology in neurodegenerative diseases, conveying the importance of the brain-gut-microbiome axis in such conditions. However, little is known about the longitudinal microbiome landscape and its potential clinical implications in other protein misfolding disorders, such as prion disease. We investigated the microbiome architecture throughout prion disease course in mice. Fecal specimens were assessed by 16S ribosomal RNA sequencing. We report a temporal microbiome signature in prion disease and uncovered alterations in Lachnospiraceae, Ruminococcaceae, Desulfovibrionaceae, and Muribaculaceae family members in this disease. Moreover, we determined the enrichment of Bilophila, a microorganism connected to cognitive impairment, long before the clinical manifestation of disease symptoms. Based on temporal microbial abundances, several associated metabolic pathways and resulting metabolites, including short-chain fatty acids, were linked to the disease. We propose that neuroinflammatory processes relate to perturbations of the intestinal microbiome and metabolic state by an interorgan brain-gut crosstalk. Furthermore, we describe biomarkers possibly suitable for early disease diagnostics and anti-prion therapy monitoring. While our study is confined to prion disease, our discoveries might be of equivalent relevance in other proteinopathies and central nervous system pathologies.

Citrobacter rodentium infection impairs dopamine metabolism and exacerbates the pathology of Parkinson's disease in mice

Parkinson's disease (PD) is a prevalent neurodegenerative disorder with indistinct etiology and ill-defined pathophysiology. Intestinal inflammation involved in the pathogenesis of PD, but the underlying mechanism is not fully understood. Citrobacter rodentium (C.R) is a gram-negative bacterium that can be used to induce human inflammatory bowel disease in mice. Here, we investigated whether the proinflammatory effects caused by C.R infection initiate PD-like injury and/or exacerbate PD pathology and extensively studied the underlying mechanism. Mice were gavaged once with C.R and monitored for several pathological features at 9 days post infection. The results showed that C.R delivery in mice induced IBD-like symptoms, including significant weight loss, increased fecal water content, an impaired intestinal barrier, intestinal hyperpermeability and inflammation, and intestinal microbiota disturbances. Notably, C.R infection modified dopamine (DA) metabolism in the brains of both male and female mice. Subsequently, a single high dose of MPTP or normal saline was administered at 6 days post infection. At 3 days after MPTP administration, the feces were collected for 16 S rRNA analysis, and PD-like phenotypes and mechanisms were systemically analyzed. Compared with C.R or MPTP injection alone, the injection of C.R and MPTP combined worsened behavioral performance. Moreover, such combination triggered more severe dopaminergic degeneration and glial cell overactivation in the nigrostriatal pathway of mice. Mechanistically, the combination of C.R and MPTP increased the expression of TLR4 and NF-κB p65 in the colon and striatum and upregulated proinflammatory cytokine expression. Therefore, C.R infection-induced intestinal inflammation can impair dopamine metabolism and exacerbate PD pathological processes.

Post-stroke cognitive impairment: exploring molecular mechanisms and omics biomarkers for early identification and intervention

Post-stroke cognitive impairment (PSCI) is a major stroke consequence that has a severe impact on patients' quality of life and survival rate. For this reason, it is especially crucial to identify and intervene early in high-risk groups during the acute phase of stroke. Currently, there are no reliable and efficient techniques for the early diagnosis, appropriate evaluation, or prognostication of PSCI. Instead, plenty of biomarkers in stroke patients have progressively been linked to cognitive impairment in recent years. High-throughput omics techniques that generate large amounts of data and process it to a high quality have been used to screen and identify biomarkers of PSCI in order to investigate the molecular mechanisms of the disease. These techniques include metabolomics, which explores dynamic changes in the organism, gut microbiomics, which studies host-microbe interactions, genomics, which elucidates deeper disease mechanisms, transcriptomics and proteomics, which describe gene expression and regulation. We looked through electronic databases like PubMed, the Cochrane Library, Embase, Web of Science, and common databases for each omics to find biomarkers that might be connected to the pathophysiology of PSCI. As all, we found 34 studies: 14 in the field of metabolomics, 5 in the field of gut microbiomics, 5 in the field of genomics, 4 in the field of transcriptomics, and 7 in the field of proteomics. We discovered that neuroinflammation, oxidative stress, and atherosclerosis may be the primary causes of PSCI development, and that metabolomics may play a role in the molecular mechanisms of PSCI. In this study, we summarized the existing issues across omics technologies and discuss the latest discoveries of PSCI biomarkers in the context of omics, with the goal of investigating the molecular causes of post-stroke cognitive impairment. We also discuss the potential therapeutic utility of omics platforms for PSCI mechanisms, diagnosis, and intervention in order to promote the area's advancement towards precision PSCI treatment.

Gut microbiota is involved in male reproductive function: a review

Globally, ~8%-12% of couples confront infertility issues, male-related issues being accountable for 50%. This review focuses on the influence of gut microbiota and their metabolites on the male reproductive system from five perspectives: sperm quality, testicular structure, sex hormones, sexual behavior, and probiotic supplementation. To improve sperm quality, gut microbiota can secrete metabolites by themselves or regulate host metabolites. Endotoxemia is a key factor in testicular structure damage that causes orchitis and disrupts the blood-testis barrier (BTB). In addition, the gut microbiota can regulate sex hormone levels by participating in the synthesis of sex hormone-related enzymes directly and participating in the enterohepatic circulation of sex hormones, and affect the hypothalamic-pituitary-testis (HPT) axis. They can also activate areas of the brain that control sexual arousal and behavior through metabolites. Probiotic supplementation can improve male reproductive function. Therefore, the gut microbiota may affect male reproductive function and behavior; however, further research is needed to better understand the mechanisms underlying microbiota-mediated male infertility.

Buty and the beast: the complex role of butyrate in Parkinson's disease

Parkinson's disease (PD) is a complex neurodegenerative disease which is often associated with gastrointestinal (GI) dysfunction. The GI tract is home to a wide range of microorganisms, among which bacteria, that can influence the host through various mechanisms. Products produced by these bacteria can act in the gut but can also exert effects in the brain via what is now well established to be the microbiota-gut-brain axis. In those with PD the gut-bacteria composition is often found to be different to that of non-PD individuals. In addition to compositional changes, the metabolic activity of the gut-microbiota is also changed in PD. Specifically, it is often reported that key producers of short chain fatty acids (SCFAs) as well as the concentration of SCFAs themselves are altered in the stool and blood of those with PD. These SCFAs, among which butyrate, are essential nutrients for the host and are a major energy source for epithelial cells of the GI tract. Additionally, butyrate plays a key role in regulating various host responses particularly in relation to inflammation. Studies have demonstrated that a reduction in butyrate levels can have a critical role in the onset and progression of PD. Furthermore, it has been shown that restoring butyrate levels in those with PD through methods such as probiotics, prebiotics, sodium butyrate supplementation, and fecal transplantation can have a beneficial effect on both motor and non-motor outcomes of the disease. This review presents an overview of evidence for the altered gut-bacteria composition and corresponding metabolite production in those with PD, with a particular focus on the SCFA butyrate. In addition to presenting current studies regarding SCFA in clinical and preclinical reports, evidence for the possibility to target butyrate production using microbiome based approaches in a therapeutic context is discussed.

Gut dysbiosis was inevitable, but tolerance was not: temporal responses of the murine microbiota that maintain its capacity for butyrate production correlate with sustained antinociception to chronic voluntary morphine

The therapeutic benefits of opioids are compromised by the development of analgesic tolerance, which necessitates higher dosing for pain management thereby increasing the liability for dependence and addiction. Rodent models indicate opposing roles of the gut microbiota in tolerance: morphine-induced gut dysbiosis exacerbates tolerance, whereas probiotics ameliorate tolerance. Not all individuals develop tolerance which could be influenced by differences in microbiota, and yet no study has capitalized upon this natural variation to identify specific features linked to tolerance. We leveraged this natural variation in a murine model of voluntary oral morphine self-administration to elucidate the mechanisms by which microbiota influences tolerance. Although all mice shared similar and predictive morphine-driven microbiota changes that largely masked informative associations with variability in tolerance, our high-resolution temporal analyses revealed a divergence in the progression of dysbiosis that best explained differences in the development in tolerance. Mice that did not develop tolerance also maintained a higher abundance of taxa capable of producing the short-chain fatty acid (SCFA) butyrate, known to bolster intestinal barriers, suppress inflammation, and promote neuronal homeostasis. Furthermore, dietary butyrate supplementation significantly reduced the development of tolerance. These findings could inform immediate therapies to extend the analgesic efficacy of opioids.

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

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

Advances in molecular mechanisms and therapeutic strategies for central nervous system diseases based on gut microbiota imbalance

BACKGROUD

Central nervous system (CNS) diseases pose a serious threat to human health, but the regulatory mechanisms and therapeutic strategies of CNS diseases need to be further explored. It has been demonstrated that the gut microbiota (GM) is closely related to CNS disease. GM structure disorders, abnormal microbial metabolites, intestinal barrier destruction and elevated inflammation exist in patients with CNS diseases and promote the development of CNS diseases. More importantly, GM remodeling alleviates CNS pathology to some extent.

AIM OF REVIEW

Here, we have summarized the regulatory mechanism of the GM in CNS diseases and the potential treatment strategies for CNS repair based on GM regulation, aiming to provide safer and more effective strategies for CNS repair from the perspective of GM regulation.

KEY SCIENTIFIC CONCEPTS OF REVIEW

The abundance and composition of GM is closely associated with the CNS diseases. On the basis of in-depth analysis of GM changes in mice with CNS disease, as well as the changes in its metabolites, therapeutic strategies, such as probiotics, prebiotics, and FMT, may be used to regulate GM balance and affect its microbial metabolites, thereby promoting the recovery of CNS diseases.

Age-Related Gut Microbiota Transplantation Disrupts Myocardial Energy Homeostasis and Induces Oxidative Damage

BACKGROUND

Aging-related energy homeostasis significantly affects normal heart function and disease development. The relationship between the gut microbiota and host energy metabolism has been well established. However, the influence of an aged microbiota on energy metabolism in the heart remains unclear.

OBJECTIVE

The objective of this was to explore the effects of age-related microbiota composition on energy metabolism in the heart.

METHODS

In this study, we used the fecal microbiota transplantation (FMT) method. The fecal microbiota from young (2-3 mo) and aged (18-22 mo) donor mice were transplanted into separate groups of young (2-3 mo) recipient mice. The analysis utilized whole 16S rRNA sequencing and plasma metabolomics to assess changes in the gut microbiota composition and metabolic potential. Energy changes were monitored by performing an oral glucose tolerance test, biochemical testing, body composition analysis, and metabolic cage measurements. Metabolic markers and markers of DNA damage were assessed in heart samples.

RESULTS

FMT of an aged microbiota changed the composition of the recipient's gut microbiota, leading to an elevated Firmicutes-to-Bacteroidetes ratio. It also affected overall energy metabolism, resulting in elevated plasma glucose concentrations, impaired glucose tolerance, and epididymal fat accumulation. Notably, FMT of an aged microbiota increased the heart weight and promoted cardiac hypertrophy. Furthermore, there were significant associations between heart weight and cardiac hypertrophy indicators, epididymal fat weight, and fasting glucose concentrations. Mechanistically, FMT of an aged microbiota modulated the glucose metabolic pathway and induced myocardial oxidative damage.

CONCLUSIONS

Our findings suggested that an aged microbiota can modulate metabolism and induce cardiac injury. This highlights the possible role of the gut microbiota in age-related metabolic disorders and cardiac dysfunction.

Metabolomics approach for predicting stomach and colon contents in dead Arctocephalus pusillus pusillus, Arctocephalus tropicalis, Lobodon carcinophaga and Ommatophoca rossii from sub-Antarctic region

The dietary habits of seals play a pivotal role in shaping management and administration policies, especially in regions with potential interactions with fisheries. Previous studies have utilized various methods, including traditional approaches, to predict seal diets by retrieving indigestible prey parts, such as calcified structures, from intestines, feces, and stomach contents. Additionally, methods evaluating nitrogen and stable isotopes of carbon have been employed. The metabolomics approach, capable of quantifying small-scale molecules in biofluids, holds promise for specifying dietary exposures and estimating disease risk. This study aimed to assess the diet composition of five seal species-Arctocephalus pusillus pusillus, Lobodon carcinophaga, Ommatophoca rossii, and Arctocephalus tropicalis 1 and 2-by analyzing stomach and colon contents collected from stranded dead seals at various locations. Metabolite concentrations in the seal stomach and colon contents were determined using Nuclear Magnetic Resonance Spectroscopy. Among the colon and stomach contents, 29 known and 8 unknown metabolites were identified. Four metabolites (alanine, fumarate, lactate, and proline) from stomach contents and one metabolite (alanine) from colon contents showed no significant differences between seal species (p>0.05). This suggests that traces of these metabolites in the stomach and colon contents may be produced by the seals' gut microbiome or derived from other animals, possibly indicating reliance on fish caught at sea. Despite this insight, the cause of death for stranded seals remains unclear. The study highlights the need for specific and reliable biomarkers to precisely indicate dietary exposures across seal populations. Additionally, there is a call for the development of relevant metabolite and disease interaction networks to explore disease-related metabolites in seals. Ultimately, the metabolomic method employed in this study reveals potential metabolites in the stomach and colon contents of these seal species.

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.

Role of the Exposome in Neurodegenerative Disease: Recent Insights and Future Directions

Neurodegenerative diseases are increasing in prevalence and place a significant burden on society. The causes are multifactorial and complex, and increasing evidence suggests a dynamic interplay between genes and the environment, emphasizing the importance of identifying and understanding the role of lifelong exposures, known as the exposome, on the nervous system. This review provides an overview of recent advances toward defining neurodegenerative disease exposomes, focusing on Parkinson's disease, amyotrophic lateral sclerosis, and Alzheimer's disease. We present the current state of the field based on emerging data, elaborate on key themes and potential mechanisms, and conclude with limitations and future directions. ANN NEUROL 2024;95:635-652.

Comprehensive analysis of the microbiome in Apis cerana honey highlights honey as a potential source for the isolation of beneficial bacterial strains

Background

Honey is a nutritious food made by bees from nectar and sweet deposits of flowering plants and has been used for centuries as a natural remedy for wound healing and other bacterial infections due to its antibacterial properties. Honey contains a diverse community of bacteria, especially probiotic bacteria, that greatly affect the health of bees and their consumers. Therefore, understanding the microorganisms in honey can help to ensure the quality of honey and lead to the identification of potential probiotic bacteria.

Methods

Herein, the bacteria community in honey produced by Apis cerana was investigated by applying the next-generation sequencing (NGS) method for the V3-V4 hypervariable regions of the bacterial 16S rRNA gene. In addition, lactic acid bacteria (LAB) in the honey sample were also isolated and screened for in vitro antimicrobial activity.

Results

The results showed that the microbiota of A. cerana honey consisted of two major bacterial phyla, Firmicutes (50%; Clostridia, 48.2%) and Proteobacteria (49%; Gammaproteobacteria, 47.7%). Among the 67 identified bacterial genera, the three most predominant genera were beneficial obligate anaerobic bacteria, Lachnospiraceae (48.14%), followed by Gilliamella (26.80%), and Enterobacter (10.16%). Remarkably, among the identified LAB, Lactobacillus kunkeei was found to be the most abundant species. Interestingly, the isolated L. kunkeei strains exhibited antimicrobial activity against some pathogenic bacteria in honeybees, including Klebsiella spp., Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa and Staphylococcus aureus. This underscores the potential candidacy of L. kunkeei for developing probiotics for medical use. Taken together, our results provided new insights into the microbiota community in the A. cerana honey in Hanoi, Vietnam, highlighting evidence that honey can be an unexplored source for isolating bacterial strains with potential probiotic applications in honeybees and humans.

Oral and gut microbial profiling in periodontitis and Parkinson's disease

Objectives

We tested the hypothesis that Parkinson's disease (PA) alters the periodontitis-associated oral microbiome.

Method

Patients with periodontitis with Parkinson's disease (PA+P) and without PA (P) and systemically and periodontally healthy individuals (HC) were enrolled. Clinical, periodontal and neurological parameters were recorded. The severity of PA motor functions was measured. Unstimulated saliva samples and stool samples were collected. Next-generation sequencing of 16S ribosomal RNA (V1-V3 regions) was performed.

Results

PA patients had mild-to-moderate motor dysfunction and comparable plaque scores as those without, indicating that oral hygiene was efficient in the PA+P group. In saliva, there were statistically significant differences in beta diversity between HC and PA+P (p = 0.001), HC and P (p = 0.001), and P and PA+P (p = 0.028). The microbial profiles of saliva and fecal samples were distinct. Mycoplasma faucium, Tannerella forsythia, Parvimonas micra, and Saccharibacteria (TM7) were increased in P; Prevotella pallens, Prevotella melaninogenica, Neisseria multispecies were more abundant in PA+P group, Ruthenibacterium lactatiformans, Dialister succinatiphilus, Butyrivibrio crossotus and Alloprevotella tannerae were detected in fecal samples in P groups compared to healthy controls.

Conclusions

No significant differences were detected between Parkinson's and non-Parkinson's gut microbiomes, suggesting that Parkinson's disease modifies the oral microbiome in periodontitis subjects independent of the gut microbiome.

Role of the Gut Microbiome and Bacterial Amyloids in the Development of Synucleinopathies

Less than ten years ago, evidence began to accumulate about association between the changes in the composition of gut microbiota and development of human synucleinopathies, in particular sporadic form of Parkinson's disease. We collected data from more than one hundred and thirty experimental studies that reported similar results and summarized the frequencies of detection of different groups of bacteria in these studies. It is important to note that it is extremely rare that a unidirectional change in the population of one or another group of microorganisms (only an elevation or only a reduction) was detected in the patients with Parkinson's disease. However, we were able to identify several groups of bacteria that were overrepresented in the patients with Parkinson's disease in the analyzed studies. There are various hypotheses about the molecular mechanisms that explain such relationships. Usually, α-synuclein aggregation is associated with the development of inflammatory processes that occur in response to the changes in the microbiome. However, experimental evidence is accumulating on the influence of bacterial proteins, including amyloids (curli), as well as various metabolites, on the α-synuclein aggregation. In the review, we provided up-to-date information about such examples.

Microbiota-microglia crosstalk between Blautia producta and neuroinflammation of Parkinson's disease: A bench-to-bedside translational approach

Parkinson's disease (PD) is intricately linked to abnormal gut microbiota, yet the specific microbiota influencing clinical outcomes remain poorly understood. Our study identified a deficiency in the microbiota genus Blautia and a reduction in fecal short-chain fatty acid (SCFA) butyrate level in PD patients compared to healthy controls. The abundance of Blautia correlated with the clinical severity of PD. Supplementation with butyrate-producing bacterium B. producta demonstrated neuroprotective effects, attenuating neuroinflammation and dopaminergic neuronal death in mice, consequently ameliorating motor dysfunction. A pivotal inflammatory signaling pathway, the RAS-related pathway, modulated by butyrate, emerged as a key mechanism inhibiting microglial activation in PD. The change of RAS-NF-κB pathway in PD patients was observed. Furthermore, B. producta-derived butyrate demonstrated the inhibition of microglial activation in PD through regulation of the RAS-NF-κB pathway. These findings elucidate the causal relationship between specific gut microbiota and PD, presenting a novel microbiota-based treatment perspective for PD.

The role of short-chain fatty acids in central nervous system diseases: A bibliometric and visualized analysis with future directions

Background

Short-chain fatty acids (SCFAs) are thought to play a key role in the microbe-gut-brain axis and involve in the pathogenesis of a variety of neurological diseases. This study aimed to identify research hotspots and evolution trends in SCFAs in central nervous diseases (CNS) and examine current research trends.

Methods

The bibliometric analysis was performed using CiteSpace, and the results were visualized via network maps.

Results

From 2002 to 2022, 480 publications in the database met the criteria. On the country level, China produced the highest number of publications, while the United States had the highest centrality. On the institutional level, University College Cork contributed to the most publications, and John F. Cryan from this university was the key researcher with considerable academic influence. The article, the role of short-chain fatty acids in microbiota-gut-brain, written by Boushra Dalile et al., in 2019 was the most cited article. Furthermore, the journal Nutrients had the maximum number of publications, while Plos One was the most cited journal. "Gut microbiome", "SCFAs", and "central nervous system" were the three most frequent keywords. Among them, SCFAs had the highest centrality. "Animal model" was the keyword with the highest burst strength, with the latest burst keywords being "social behavior", "pathogenesis", and "insulin sensitive". In addition, the research topics on SCFAs in CNS diseases from 2002 to 2022 mainly focused on following aspects: SCFAs plays a key role in microbe-gut-brain crosstalk; The classification and definition of SCFAs in the field of CNS; Several CNS diseases that are closely related to SCFAs research; Mechanism and translational studies of SCFAs in the CNS diseases. And the hotspots over the past 5 years have gradually increased the attention to the therapeutic potential of SCFAs in the CNS diseases.

Conclusion

The research of SCFAs in CNS diseases is attracting growing attention. However, there is a lack of cooperation between countries and institutions, and additional measures are required to promote cooperation. The current evidence for an association between SCFAs and CNS diseases is preliminary and more work is needed to pinpoint the precise mechanism. Moreover, large-scale clinical trials are needed in the future to define the therapeutic potential of SCFAs in CNS diseases.

Electroacupuncture at ST25 corrected gut microbial dysbiosis and SNpc lipid peroxidation in Parkinson's disease rats

Introduction

Parkinson's disease (PD) remains one kind of a complex, progressive neurodegenerative disease. Levodopa and dopamine agonists as widely utilized PD therapeutics have not shown significant positive long-term outcomes. Emerging evidences indicate that electroacupuncture (EA) have potential effects on the therapy of nervous system disorders, particularly PD, but its specific underlying mechanism(s) remains poorly understood, leading to the great challenge of clinical application and management. Previous study has shown that acupuncture ameliorates PD motor symptoms and dopaminergic neuron damage by modulating intestinal dysbiosis, but its intermediate pathway has not been sufficiently investigated.

Methods

A rat model of PD was induced using rotenone. The therapeutic effect of EA on PD was assessed using the pole and rotarod tests and immunohistostaining for tyrosine hydroxylase (TH) in the substantia nigra (SN) of brain. The role of gut microbiota was explored using 16S rRNA gene sequencing and metabonomic analysis. PICRUSt2 analysis, lipidomic analysis, LPS and inflammatory factor assays were used for subsequent exploration and validation. Correlation analysis was used to identify the key bacteria that EA regulates lipid metabolism to improve PD.

Results

The present study firstly reappeared the effects of EA on protecting motor function and dopaminergic neurons and modulation of gut microbial dysbiosis in rotenone-induced PD rat model. EA improved motor dysfunction (via the pole and rotarod tests) and protected TH+ neurons in PD rats. EA increased the abundance of beneficial bacteria such as Lactobacillus, Dubosiella and Bifidobacterium and decreased the abundance of Escherichia-Shigella and Morganella belonging to Pseudomonadota, suggesting that the modulation of gut microbiota by EA improving the symptoms of PD motility via alleviating LPS-induced inflammatory response and oxidative stress, which was also validated by various aspects such as microbial gene functional analysis, fecal metabolomics analysis, LPS and inflammatory factor assays and SNpc lipidomics analysis. Moreover, correlation analyses also verified strong correlations of Escherichia-Shigella and Morganella with motor symptoms and SNpc lipid peroxidation, explicating targets and intermediate pathways through which EA improve PD exercise symptom.

Conclusion

Our results indicate that the improvement of motor function in PD model by EA may be mediated in part by restoring the gut microbiota, which intermediate processes involve circulating endotoxins and inflammatory mediators, SNpc oxidative stress and lipid peroxidation. The gut-microbiome - brain axis may be a potential mechanism of EA treatment for the PD.

Multi-omics analysis on the mechanism of the effect of Isatis leaf on the growth performance of fattening sheep

Introduction

This study evaluated the effects of Isatis Leaf (ISL) on the growth performance, gastrointestinal tissue morphology, rumen and intestinal microbiota, rumen, serum and urine metabolites, and rumen epithelial tissue transcriptome of fattening sheep.

Methods

Twelve 3.5-month-old healthy fattening sheep were randomly divided into two groups, each with 6 replicates, and fed with basal diet (CON) and basal diet supplemented with 80 g/kg ISL for 2.5 months. Gastrointestinal tract was collected for histological analysis, rumen fluid and feces were subjected to metagenomic analysis, rumen fluid, serum, and urine for metabolomics analysis, and rumen epithelial tissue for transcriptomics analysis.

Results

The results showed that in the ISL group, the average daily gain and average daily feed intake of fattening sheep were significantly lower than those of the CON group (P < 0.05), and the rumen ammonia nitrogen level was significantly higher than that of the CON group (P < 0.01). The thickness of the reticulum and abomasum muscle layer was significantly increased (P < 0.05). At the genus level, the addition of ISL modified the composition of rumen and fecal microorganisms, and the relative abundance of Methanobrevibacter and Centipeda was significantly upregulated in rumen microorganisms, The relative abundance of Butyrivibrio, Saccharofermentans, Mogibacterium, and Pirellula was significantly downregulated (P < 0.05). In fecal microorganisms, the relative abundance of Papillibacter, Pseudoflavonifractor, Butyricicoccus, Anaerovorax, and Methanocorpusculum was significantly upregulated, while the relative abundance of Roseburia, Coprococcus, Clostridium XVIII, Butyrivibrio, Parasutterella, Macellibacteroides, and Porphyromonas was significantly downregulated (P < 0.05). There were 164, 107, and 77 different metabolites in the rumen, serum, and urine between the ISL and CON groups (P < 0.05). The differential metabolic pathways mainly included thiamine metabolism, niacin and nicotinamide metabolism, vitamin B6 metabolism, taurine and taurine metabolism, beta-Alanine metabolism and riboflavin metabolism. These metabolic pathways were mainly involved in the regulation of energy metabolism and immune function in fattening sheep. Transcriptome sequencing showed that differentially expressed genes were mainly enriched in cellular physiological processes, development, and immune regulation.

Conclusion

In summary, the addition of ISL to the diet had the effect of increasing rumen ammonia nitrogen levels, regulating gastrointestinal microbiota, promoting body fat metabolism, and enhancing immunity in fattening sheep.

Does gut brain axis has an impact on Parkinson's disease (PD)?

Parkinson's Disease (PD) is becoming a growing global concern by being the second most prevalent disease next to Alzheimer's Disease (AD). Henceforth new exploration is needed in search of new aspects towards the disease mechanism and origin. Evidence from recent studies has clearly stated the role of Gut Microbiota (GM) in the maintenance of the brain and as a root cause of various diseases and disorders including other neurological conditions. In the case of PD, with an unknown etiology, the GM is said to have a larger impact on the disease pathophysiology. Although GM and its metabolites are crucial for maintaining the normal physiology of the host, it is an undeniable fact that there is an influence of GM in the pathophysiology of PD. As such the Enteroendocrine Cells (EECs) in the epithelium of the intestine are one of the significant regulators of the gut-brain axis and act as a communication mediator between the gut and the brain. The communication is established via the molecules of neuroendocrine which are said to have a crucial part in neurological diseases such as AD, PD, and other psychiatry-related disorders. This review is focused on understanding the proper role of GM and EECs in PD. Here, we also focus on some of the metabolites and compounds that can interact with the PD genes causing various dysfunctions in the cell and facilitating the disease conditions using bioinformatical tools. Various mechanisms concerning EECs and PD, their identification, the latest studies, and available current therapies have also been discussed.

Efficacy and mechanism study of Baichanting compound, a combination of Acanthopanax senticosus (Rupr. and Maxim.) Harms, Paeonia lactiflora Pall and Uncaria rhynchophylla (Miq.) Miq. ex Havil, on Parkinson's disease based on metagenomics and metabolomics

ETHNOPHARMACOLOGICAL RELEVANCE

Parkinson's disease (PD) is a rapidly progressing neurological disorder. Currently, Medication for PD has numerous limitations. Baichanting Compound (BCT) is a Chinese herbal prescription, a Combination of Acanthopanax senticosus (Rupr. and Maxim.) Harms, Paeonia lactiflora Pall and Uncaria rhynchophylla (Miq.) Miq. ex Havil, that was developed to treat PD and holds a national patent (ZL, 201110260536.3).

AIM OF THE STUDY

To clarify the therapeutic effect of BCT on PD and explore its possible mechanism based on metabolomics and metagenomics.

MATERIALS AND METHODS

C57BL/6 mice were used as a control group, and α-syn transgenic C57BL/6 mice were randomly assigned to the PD (without treatment) or BCT (with BCT treatment) group. UPLC-MS was performed to detect dopamine levels in brain tissue, while ELISA was used to determine inflammatory factors such as IL-1β, IL-6, TNF-α, IFN-γ and NO, and oxidative stress indicators such as malondialdehyde, superoxide dismutase and glutathione peroxidase enzyme activity. Fecal metabolomics was used to detect fecal metabolic profiles, screen differential metabolic markers, and predict metabolic pathways by KEGG enrichment analysis. Metagenomics was used to determine the intestinal microbial composition, and KO enrichment analysis was performed to predict the potential function of different gut microbiota. Finally, Spearman correlation analysis was used to find the possible relationships among intestinal flora, metabolic markers, inflammatory factors, oxidative stress and dopamine levels.

RESULTS

BCT increased the superoxide dismutase activity of α-Syn transgenic C57BL/6 mice (P < 0.01), decreased the levels of TNF-α, IFN-γ, IL-1β, IL-6, NO and malondialdehyde (P < 0.01, 0.05), and increased the release of dopamine (P < 0.01). Metabolomics results show that BCT could regulate Acetatifactor, Marvinbryantia, Faecalitalea, Anaeromassilibacillus, Anaerobium, Pseudobutyrivibrio and Lachnotalea and Acetatifactor_muris, Marvinbryantia_formatexigens, Lachnotalea_sp_AF33_28, Faecalitalea_sp_Marseille_P3755 and Anaerobium_acetethylicum, Gemmiger_sp_An120 abundance to restore intestinal flora function, and reverse fecal metabolism trend, restoring the content of α-D-glucose, cytidine, L-glutamate, L-glutamine, N-acetyl-L-glutamate, raffinose and uracil. In addition, it regulates arginine biosynthesis, D-glutamine and D-glutamate, pyrimidine, galactose and alanine, aspartate and glutamate metabolic pathways.

CONCLUSION

BCT may regulate the composition of the gut microbiota to reverse fecal metabolism in PD mice to protect the substantia nigra and striatum from oxidative stress and inflammatory factors and ultimately play an anti-PD role.

Role of the Gut Bacteria-Derived Metabolite Phenylacetylglutamine in Health and Diseases

Over the past few decades, it has been well established that gut microbiota-derived metabolites can disrupt gut function, thus resulting in an array of diseases. Notably, phenylacetylglutamine (PAGln), a bacterial derived metabolite, has recently gained attention due to its role in the initiation and progression of cardiovascular and cerebrovascular diseases. This meta-organismal metabolite PAGln is a byproduct of amino acid acetylation of its precursor phenylacetic acid (PAA) from a range of dietary sources like egg, meat, dairy products, etc. The microbiota-dependent metabolism of phenylalanine produces PAA, which is a crucial intermediate that is catalyzed by diverse microbial catalytic pathways. PAA conjugates with glutamine and glycine in the liver and kidney to predominantly form phenylacetylglutamine in humans and phenylacetylglycine in rodents. PAGln is associated with thrombosis as it enhances platelet activation mediated through the GPCRs receptors α2A, α2B, and β2 ADRs, thereby aggravating the pathological conditions. Clinical evidence suggests that elevated levels of PAGln are associated with pathology of cardiovascular, cerebrovascular, and neurological diseases. This Review further consolidates the microbial/biochemical synthesis of PAGln and discusses its role in the above pathophysiologies.

Alterations of gut microbiota and its correlation with the liver metabolome in the process of ameliorating Parkinson's disease with Buyang Huanwu decoction

ETHNOPHARMACOLOGICAL RELEVANCE

Buyang Huanwu decoction (BHD), a famous traditional Chinese medicine (TCM) formula, was first recorded in Qing Dynasty physician Qingren Wang's Yi Lin Gai Cuo. BHD has been widely utilized in the treatment of patients with neurological disorders, including Parkinson's disease (PD). However, the underlying mechanism has not been fully elucidated. In particular, little is known about the role of gut microbiota.

AIM OF THE STUDY

We aimed to reveal the alterations and functions of gut microbiota and its correlation with the liver metabolome in the process of improving PD with BHD.

MATERIALS AND METHODS

The cecal contents were collected from PD mice treated with or without BHD. 16S rRNA gene sequencing was performed on an Illumina MiSeq-PE250 platform, and the ecological structure, dominant taxa, co-occurrence patterns, and function prediction of the gut microbial community were analyzed by multivariate statistical methods. The correlation between differential microbial communities in the gut and differentially accumulated metabolites in the liver was analyzed using Spearman's correlation analysis.

RESULTS

The abundance of Butyricimonas, Christensenellaceae, Coprococcus, Peptococcaceae, Odoribacteraceae, and Roseburia was altered significantly in the model group, which was by BHD. Ten genera, namely Dorea, unclassified_Lachnospiraceae, Oscillospira, unidentified_Ruminococcaceae, unclassified_Clostridiales, unidentified_Clostridiales, Bacteroides, unclassified_Prevotellaceae, unidentified_Rikenellaceae, and unidentified_S24-7, were identified as key bacterial communities. According to the function prediction of differential genera, the mRNA surveillance pathway might be a target of BHD. Integrated analysis of gut microbiota and the liver metabolome revealed that several gut microbiota genera such as Parabacteroides, Ochrobactrum, Acinetobacter, Clostridium, and Halomonas, were positively or negatively correlated with some nervous system-related metabolites, such as L-carnitine, L-pyroglutamic acid, oleic acid, and taurine.

CONCLUSIONS

Gut microbiota might be a target of BHD in the process of ameliorating PD. Our findings provide novel insight into the mechanisms underlying the effects of BHD on PD and contribute to the development of TCM.

Simultaneous quantification of seven B vitamins in human faeces by stable isotope label-based high-performance liquid chromatography-tandem mass spectrometry

B vitamins in the human distal gut are primarily derived from the gut microbiota because daily dietary vitamins are fully absorbed in the small intestine under normal dietary and physiological conditions. Quantitative determination of B vitamins in the distal gut and faecal samples is crucial for understanding the intricate relationship between gut B vitamins, gut microbiota, and host health. In this study, we developed a rapid, robust, and reliable method with a simple extraction procedure for the simultaneous analysis of seven B vitamins in human faeces using high-performance liquid chromatography-electrospray ionisation-tandem mass spectrometry (HPLC-ESI-MS/MS) with stable isotope-labelled internal standards. A protein precipitation approach using methanol as the precipitant was employed to extract vitamin B from human faecal samples. Seven B vitamins were adequately separated and quantified within 9 min by HPLC-ESI-MS/MS with a Pursuit PFP column (2.0 ×150 mm, 3.0 µm), including vitamins B1, B2, B3, B5, pyridoxic acid, pyridoxine, and B7. The lower limits of quantification were within the range of 0.1-25 ng mL-1. The intra-day and inter-day precision and accuracy were both within 15 %. The validated method was successfully applied to 55 faecal samples collected from healthy individuals, patients with type 2 diabetes, and obese patients. Compared with healthy controls, obese patients had lower faecal concentrations of vitamins B1 and B3 and pyridoxic acid, whereas patients with type 2 diabetes had lower faecal concentrations of vitamins B1 and B5.

Localized Pantothenic Acid (Vitamin B5) Reductions Present Throughout the Dementia with Lewy Bodies Brain

Background

Localized pantothenic acid deficiencies have been observed in several neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease dementia (PDD), and Huntington's disease (HD), indicating downstream energetic pathway perturbations. However, no studies have yet been performed to see whether such deficiencies occur across the dementia with Lewy bodies (DLB) brain, or what the pattern of such dysregulation may be.

Objective

Firstly, this study aimed to quantify pantothenic acid levels across ten regions of the brain in order to determine the localization of any pantothenic acid dysregulation in DLB. Secondly, the localization of pantothenic acid alterations was compared to that previously in AD, PDD, and HD brains.

Methods

Pantothenic acid levels were determined in 20 individuals with DLB and 19 controls by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) across ten brain regions. Case-control differences were determined by nonparametric Mann-Whitney U test, with the calculation of S-values, risk ratios, E-values, and effect sizes. The results were compared with those previously obtained in DLB, AD, and HD.

Results

Pantothenic acid levels were significantly decreased in six of the ten investigated brain regions: the pons, substantia nigra, motor cortex, middle temporal gyrus, primary visual cortex, and hippocampus. This level of pantothenic acid dysregulation is most similar to that of the AD brain, in which pantothenic acid is also decreased in the motor cortex, middle temporal gyrus, primary visual cortex, and hippocampus. DLB appears to differ from other neurodegenerative diseases in being the only of the four to not show pantothenic acid dysregulation in the cerebellum.

Conclusions

Pantothenic acid deficiency appears to be a shared mechanism of several neurodegenerative diseases, although differences in the localization of this dysregulation may contribute to the differing clinical pathways observed in these conditions.

Neuroprotective effect of dexpanthenol on rotenone-induced Parkinson's disease model in rats

Parkinson's disease (PD) is the second most common and progressive neurodegenerative disease. This experimental study was designed to investigate the neuroprotective effects of dexpanthenol on antioxidant and anti-inflammatory processes in a rotenone-induced Parkinson's disease model in rats. Twenty-one male rats were randomly divided into 2 groups. The rotenone group (n = 14) was administered rotenone by intrastriatal injection, and the vehicle group (n = 7) was administered DMSO with the same application route. All animals underwent rotational movement testing with apomorphine injection 10 days later. Those with Parkinson's disease model were randomly divided into 2 groups. While 1 ml/kg of saline was applied to the saline group (n = 7), 500 mg/kg was administered to the dexpanthenol group intraperitoneally for 28 days. After 28 days, all rats were euthanized and brain tissue was removed. While striatal areas were evaluated immunohistochemically, brain MDA, TNF-α, and HVA levels were measured to evaluate their anti-oxidative and anti-inflammatory effects. In the dexpanthenol group, the total count (p < 0.001) and intensity (p < 0.001) of dopaminergic neurons in the striatal areas increased compared to the saline group. It was revealed that MDA (nmol/g) (p < 0.001) and TNF-α (pg/g) (p < 0.001) levels decreased in the dexpanthenol group, while HVA (ng/mg) levels increased (p < 0.01). This study suggests that dexpanthenol may have a neuroprotective effect by reducing neuronal loss, oxidative damage, and neuroinflammation in the striatum in rats.

Multidirectional associations between the gut microbiota and Parkinson's disease, updated information from the perspectives of humoral pathway, cellular immune pathway and neuronal pathway

The human gastrointestinal tract is inhabited by a diverse range of microorganisms, collectively known as the gut microbiota, which form a vast and complex ecosystem. It has been reported that the microbiota-gut-brain axis plays a crucial role in regulating host neuroprotective function. Studies have shown that patients with Parkinson's disease (PD) have dysbiosis of the gut microbiota, and experiments involving germ-free mice and fecal microbiota transplantation from PD patients have revealed the pathogenic role of the gut microbiota in PD. Interventions targeting the gut microbiota in PD, including the use of prebiotics, probiotics, and fecal microbiota transplantation, have also shown efficacy in treating PD. However, the causal relationship between the gut microbiota and Parkinson's disease remains intricate. This study reviewed the association between the microbiota-gut-brain axis and PD from the perspectives of humoral pathway, cellular immune pathway and neuronal pathway. We found that the interactions among gut microbiota and PD are very complex, which should be "multidirectional", rather than conventionally regarded "bidirectional". To realize application of the gut microbiota-related mechanisms in the clinical setting, we propose several problems which should be addressed in the future study.

Parkinson's disease and gut microbiota: from clinical to mechanistic and therapeutic studies

Parkinson's disease (PD) is one of the most prevalent neurodegenerative diseases. The typical symptomatology of PD includes motor symptoms; however, a range of nonmotor symptoms, such as intestinal issues, usually occur before the motor symptoms. Various microorganisms inhabiting the gastrointestinal tract can profoundly influence the physiopathology of the central nervous system through neurological, endocrine, and immune system pathways involved in the microbiota-gut-brain axis. In addition, extensive evidence suggests that the gut microbiota is strongly associated with PD. This review summarizes the latest findings on microbial changes in PD and their clinical relevance, describes the underlying mechanisms through which intestinal bacteria may mediate PD, and discusses the correlations between gut microbes and anti-PD drugs. In addition, this review outlines the status of research on microbial therapies for PD and the future directions of PD-gut microbiota research.

Gut microbiota and risk of polycystic ovary syndrome: Insights from Mendelian randomization

Background

Polycystic ovary syndrome (PCOS) is a multifaceted endocrine and metabolic syndrome with complex origins and pathogenesis that has not yet been fully elucidated. Recently, the interconnection between gut microbiota and metabolic diseases has gained prominence in research, generating new insights into the correlation between PCOS and gut microbiota composition. However, the causal link between PCOS and gut microbiota remains relatively unexplored, indicating a crucial gap in current research.

Methods

We conducted a two-sample Mendelian randomization analysis using summary statistics obtained from the MiBioGen Consortium's extensive genome-wide association studies (GWAS) meta-analysis, focusing on the gut microbiota. Summary statistics for PCOS were acquired from the FinnGen Consortium R7 release data. Various statistical approaches, including inverse variance weighted, MR-Egger, maximum likelihood, weighted model, and weighted median, have been employed to investigate the causal association between the gut microbiota and PCOS. Additionally, we performed a reverse causal analysis. Cochran's Q statistic was used to assess the heterogeneity of the instrumental variables. Regarding the relationships between PCOS and specific genera within the gut microbiota, a significance level of P < 0.05 was observed, but only when q ≥ 0.1.

Results

Our analysis revealed that specific microbial genera, namely Bilophila (P = 4.62 × 10-3), Blautia (P = 0.02), and Holdemania (P = 0.04), displayed a protective effect against PCOS. Conversely, the presence of the Lachnospiraceae family of bacteria was associated with a detrimental effect on PCOS (P = 0.04). Furthermore, reverse Mendelian randomization analysis confirmed the significant influence of Lachnospiraceae on PCOS. No significant variations in instrumental variables or evidence of horizontal pleiotropy were observed.

Conclusions

The results revealed a definitive causal link between PCOS and the presence of Bilophila, Blautia, Holdemania, and Lachnospiraceae in the gut microbiota. This discovery could provide pivotal insights, leading to novel preventive and therapeutic approaches for PCOS.

Automated identification and quantification of metabolites in human fecal extracts by nuclear magnetic resonance spectroscopy

We report the development of a software program, called MagMet-F, that automates the processing and quantification of 1D 1 H NMR of human fecal extracts. To optimize the program, we identified 82 potential fecal metabolites using 1D 1 H NMR of six human fecal extracts using manual profiling and a literature review of known fecal metabolites. We acquired pure versions of those metabolites and then acquired their 1D 1 H NMR spectra at 700 MHz to generate a fecal metabolite spectral library for MagMet-F. The fitting of these metabolites by MagMet-F was iteratively optimized to replicate manual profiling. We validated MagMet-F's automated profiling using a test set of six fecal extracts. It correctly identified 80% of the compounds and quantified those within <20% of the values determined by manual profiling using Chenomx. We also compared MagMet-F's profiling performance to two other open-access NMR profiling tools, Bayesil and Batman. MagMet-F outperformed both. Bayesil repeatedly overestimated metabolite concentrations by 10% to 40% while Batman was unable to properly quantify any compounds and took 10-20× longer. We have implemented MagMet-F as a freely accessible web server to enable automated, fast and convenient 1D 1 H NMR spectral profiling of fecal samples. MagMet-F is available at https://www.magmet.ca.

Gut microbiota and metabolome in sporadic Creutzfeldt-Jakob disease

BACKGROUND

Gut dysbiosis and the resulting changes in the metabolites have been associated with neurological diseases. However, the relationship between the gut microbiota and sporadic Creutzfeldt-Jakob disease (sCJD) need to be clarified. The aim of this study was to evaluate the changes in the composition of gut microbiota and metabolome accompanying sCJD, and determine their correlation with disease severity.

METHODS

Fecal samples were collected from 25 sCJD patients and 23 healthy controls. The composition of the fecal microbiota and metabolites was respectively analyzed by 16S ribosomal RNA sequencing and untargeted metabolomics. The correlation of gut microbiota and metabolites with MMSE, MoCA and MRC scores was analyzed.

RESULTS

The sCJD patients showed significant differences in the composition of gut microbiota and metabolites relative to the healthy controls. Several bacteria taxa in sCJD patients were increased at genus level, such as Turicibacter, norank_f_Christensenellaceae, Eisenbergiella, Bilophila and Holdemania. A total of 547 differential metabolites were identified between these two groups (VIP > 1, FDR p < 0.05). As per KEGG analysis, the metabolites related to the biosynthesis of phenylpropanoids, especially biochanin A, showed the most obvious decrease in the sCJD group. In addition, most metabolites involved in the pathways related to linoleic acid metabolism and steroid hormone biosynthesis were associated with MRC scale.

CONCLUSION

Our findings provide new insights into the relationship between gut microbiota and metabolites and sCJD. Some compounds, especially those related to the biosynthesis of phenylpropanoids were significantly altered in patients with sCJD, and those related to linoleic acid metabolism and steroid hormone biosynthesis might be biomarkers of evaluating disease severity.

Omics data integration suggests a potential idiopathic Parkinson's disease signature

The vast majority of Parkinson's disease cases are idiopathic. Unclear etiology and multifactorial nature complicate the comprehension of disease pathogenesis. Identification of early transcriptomic and metabolic alterations consistent across different idiopathic Parkinson's disease (IPD) patients might reveal the potential basis of increased dopaminergic neuron vulnerability and primary disease mechanisms. In this study, we combine systems biology and data integration approaches to identify differences in transcriptomic and metabolic signatures between IPD patient and healthy individual-derived midbrain neural precursor cells. Characterization of gene expression and metabolic modeling reveal pyruvate, several amino acid and lipid metabolism as the most dysregulated metabolic pathways in IPD neural precursors. Furthermore, we show that IPD neural precursors endure mitochondrial metabolism impairment and a reduced total NAD pool. Accordingly, we show that treatment with NAD precursors increases ATP yield hence demonstrating a potential to rescue early IPD-associated metabolic changes.

Compositional changes in fecal microbiota in a new Parkinson's disease model: C57BL/6-Tg(NSE-haSyn) mice

BACKGROUND

The gut-brain axis (GBA) in Parkinson's disease (PD) has only been investigated in limited mice models despite dysbiosis of the gut microbiota being considered one of the major treatment targets for neurodegenerative disease. Therefore, this study examined the compositional changes of fecal microbiota in novel transgenic (Tg) mice overexpressing human α-synuclein (hαSyn) proteins under the neuron-specific enolase (NSE) to analyze the potential as GBA model.

RESULTS

The expression level of the αSyn proteins was significantly higher in the substantia nigra and striatum of NSE-hαSyn Tg mice than the Non-Tg mice, while those of tyrosine hydroxylase (TH) were decreased in the same group. In addition, a decrease of 72.7% in the fall times and a 3.8-fold increase in the fall number was detected in NSE-hαSyn Tg mice. The villus thickness and crypt length on the histological structure of the gastrointestinal (GI) tract decreased in NSE-hαSyn Tg mice. Furthermore, the NSE-hαSyn Tg mice exhibited a significant increase in 11 genera, including Scatolibacter, Clostridium, Feifania, Lachnoclostridium, and Acetatifactor population, and a decrease in only two genera in Ligilactobacillus and Sangeribacter population during enhancement of microbiota richness and diversity.

CONCLUSIONS

The motor coordination and balance dysfunction of NSE-hαSyn Tg mice may be associated with compositional changes in gut microbiota. In addition, these mice have potential as a GBA model.

Microbiota Metabolites and Immune Regulation Affect Ischemic Stroke Occurrence, Development, and Prognosis

The gut microbiota are not only related to the development and occurrence of digestive system disease, but also have a bidirectional relationship with nervous system diseases via the microbiota-gut-brain axis. At present, correlations between the gut microbiota and neurological diseases, including stroke, are one of the focuses of investigation and attention in the medical community. Ischemic stroke (IS) is a cerebrovascular disease accompanied by focal neurological deficit or central nervous system injury or death. In this review, we summarize the contemporary latest research on correlations between the gut microbiota and IS. Additionally, we discuss the mechanisms of gut microbiota implicated in IS and related to metabolite production and immune regulation. Moreover, the factors of gut microbiota that affecting IS occurrence, and research implicating the gut microbiota as potential therapeutic targets for IS, are highlighted. Our review highlights the evidential relationships and connections between the gut microbiota and IS pathogenesis and prognosis.