Parkinson's Disease: The Emerging Role of Gut Dysbiosis, Antibiotics, Probiotics, and Fecal Microbiota Transplantation

PhyloMix: enhancing microbiome-trait association prediction through phylogeny-mixing augmentation

MOTIVATION

Understanding the associations between traits and microbial composition is a fundamental objective in microbiome research. Recently, researchers have turned to machine learning (ML) models to achieve this goal with promising results. However, the effectiveness of advanced ML models is often limited by the unique characteristics of microbiome data, which are typically high-dimensional, compositional, and imbalanced. These characteristics can hinder the models' ability to fully explore the relationships among taxa in predictive analyses. To address this challenge, data augmentation has become crucial. It involves generating synthetic samples with artificial labels based on existing data and incorporating these samples into the training set to improve ML model performance.

RESULTS

Here, we propose PhyloMix, a novel data augmentation method specifically designed for microbiome data to enhance predictive analyses. PhyloMix leverages the phylogenetic relationships among microbiome taxa as an informative prior to guide the generation of synthetic microbial samples. Leveraging phylogeny, PhyloMix creates new samples by removing a subtree from one sample and combining it with the corresponding subtree from another sample. Notably, PhyloMix is designed to address the compositional nature of microbiome data, effectively handling both raw counts and relative abundances. This approach introduces sufficient diversity into the augmented samples, leading to improved predictive performance. We empirically evaluated PhyloMix on six real microbiome datasets across five commonly used ML models. PhyloMix significantly outperforms distinct baseline methods including sample-mixing-based data augmentation techniques like vanilla mixup and compositional cutmix, as well as the phylogeny-based method TADA. We also demonstrated the wide applicability of PhyloMix in both supervised learning and contrastive representation learning.

AVAILABILITY AND IMPLEMENTATION

The Apache-licensed source code is available at (https://github.com/batmen-lab/phylomix).

Microbial Trojan Horses: Virulence Factors as Key Players in Neurodegenerative Diseases

Changes in population demographics indicate that the elderly population will reach 2.1 billion worldwide by 2050. In parallel, there will be an increase in neurodegenerative diseases such as Alzheimer's and Parkinson's. This review explores dysbiosis occurring in these pathologies and how virulence factors contribute to the worsening or development of clinical conditions, and it summarizes existing and potential ways to combat microorganisms related to these diseases. Microbiota imbalances can contribute to the progression of neurodegenerative diseases by increasing intestinal permeability, exchanging information through innervation, and even acting as a Trojan horse affecting immune cells. The microorganisms of the microbiota produce virulence factors to protect themselves from host defenses, many of which contribute to neurodegenerative diseases. These virulence factors are expressed according to the genetic composition of each microorganism, leading to a wide range of factors to be considered. Among the main virulence factors are LPS, urease, curli proteins, amyloidogenic proteins, VacA, and CagA. These factors can also be packed into bacterial outer membrane vesicles, which transport proteins, RNA, and DNA, enabling distal communication that impacts various diseases, including Alzheimer's and Parkinson's.

Antibiotic Exposure and Risk of Parkinson Disease in South Korea: A Nationally Representative Retrospective Cohort Study

Background and Objectives

Recent studies have suggested that antibiotics could be a contributing factor to Parkinson disease (PD), but validation in other population cohorts, such as Asians, is needed. This study examined the association between exposure to antibiotics and PD risk in the Korean population.

Methods

Using the National Health Insurance Service (NHIS) database, this population-level cohort research study from Korea included 298,379 people aged 40 years and older who underwent a national health examination in 2004-2005. Cumulative antibiotic exposure days were investigated over 4 years (2002-2005), and new cases of PD were followed for 14 years (2006-2019). Various covariates, such as infectious diseases, were considered in the analysis. Multivariable Cox proportional hazards regression was used to calculate adjusted hazard ratios (aHRs) and CIs for the PD risk from antibiotic exposure.

Results

PD risk was statistically significantly higher in those exposed to antibiotics for ≥121 days than in those not exposed to antibiotics (aHR, 1.29; 95% CI 1.07-1.55). In addition, compared with those exposed to antibiotics for 1-14 days, those exposed to antibiotics for ≥121 days had a higher risk of PD (aHR, 1.37; 95% CI 1.17-1.61). The results of sensitivity analyses that applied washout periods or extended antibiotic exposure periods were consistent with those of the main analyses.

Discussion

Extended usage of antibiotics was linked to a higher incidence of PD, even after controlling for several risk variables. Further research is needed to warrant the causation and mechanisms of antibiotic exposure and PD.

Aging and MPTP Sensitivity Depend on Molecular and Ultrastructural Signatures of Astroglia and Microglia in Mice Substantia Nigra

Both astroglia and microglia show region-specific distribution in CNS and often maladapt to age-associated alterations within their niche. Studies on autopsied substantia nigra (SN) of Parkinson's disease (PD) patients and experimental models propose gliosis as a trigger for neuronal loss. Epidemiological studies propose an ethnic bias in PD prevalence, since Caucasians are more susceptible than non-whites. Similarly, different mice strains are variably sensitive to MPTP. We had earlier likened divergent MPTP sensitivity of C57BL/6 J and CD-1 mice with differential susceptibility to PD, based on the numbers of SN neurons. We examined whether the variability was incumbent to inter-strain differences in glial features of male C57BL/6 J and CD-1 mice. Stereological counts showed relatively more microglia and fewer astrocytes in the SN of normal C57BL/6 J mice, suggesting persistence of an immune-vigilant state. MPTP-induced microgliosis and astrogliosis in both strains suggest their involvement in pathogenesis. ELISA of pro-inflammatory cytokines in the ventral-midbrain revealed augmentation of TNF-α and IL-6 at middle age in both strains that reduced at old age, suggesting middle age as a critical, inflamm-aging-associated time point. TNF-α levels were high in C57BL/6 J, through aging and post-MPTP, while IL-6 and IL-1β were upregulated at old age. CD-1 had higher levels of anti-inflammatory cytokine TGF-β. MPTP challenge caused upregulation of enzymes MAO-A, MAO-B, and iNOS in both strains. Post-MPTP enhancement in fractalkine and hemeoxygenase-1 may be neuron-associated compensatory signals. Ultrastructural observations of elongated astroglial/microglial mitochondria vis-à-vis the shrunken ones in neurons suggest a scale-up of their functions with neurotoxic consequences. Thus, astroglia and microglia may modulate aging and PD susceptibility.

Unraveling the Ties: Type 2 Diabetes and Parkinson's Disease - A Nano-Based Targeted Drug Delivery Approach

The link between Type 2 Diabetes (T2DM) and Parkinson's Disease (PD) dates back to the early 1960s, and ongoing research is exploring this association. PD is linked to dysregulation of dopaminergic pathways, neuroinflammation, decreased PPAR-γ coactivator 1-α, increased phosphoprotein enriched in diabetes, and accelerated α-Syn amyloid fibril production caused by T2DM. This study aims to comprehensively evaluate the T2DM-PD association and risk factors for PD in T2DM individuals. The study reviews existing literature using reputable sources like Scopus, ScienceDirect, and PubMed, revealing a significant association between T2DM and worsened PD symptoms. Genetic profiles of T2DM-PD individuals show similarities, and potential risk factors include insulin-resistance and dysbiosis of the gut-brain microbiome. Anti-diabetic drugs exhibit neuroprotective effects in PD, and nanoscale delivery systems like exosomes, micelles, and liposomes show promise in enhancing drug efficacy by crossing the Blood-Brain Barrier (BBB). Brain targeting for PD uses exosomes, micelles, liposomes, dendrimers, solid lipid nanoparticles, nano-sized polymers, and niosomes to improve medication and gene therapy efficacy. Surface modification of nanocarriers with bioactive compounds (such as angiopep, lactoferrin, and OX26) enhances α-Syn conjugation and BBB permeability. Natural exosomes, though limited, hold potential for investigating DM-PD pathways in clinical research. The study delves into the underlying mechanisms of T2DM and PD and explores current therapeutic approaches in the field of nano-based targeted drug delivery. Emphasis is placed on resolved and ongoing issues in understanding and managing both conditions.

Revolutionizing Neuroimmunology: Unraveling Immune Dynamics and Therapeutic Innovations in CNS Disorders

Neuroimmunology is reshaping the understanding of the central nervous system (CNS), revealing it as an active immune organ rather than an isolated structure. This review delves into the unprecedented discoveries transforming the field, including the emerging roles of microglia, astrocytes, and the blood-brain barrier (BBB) in orchestrating neuroimmune dynamics. Highlighting their dual roles in both repair and disease progression, we uncover how these elements contribute to the intricate pathophysiology of neurodegenerative diseases, cerebrovascular conditions, and CNS tumors. Novel insights into microglial priming, astrocytic cytokine networks, and meningeal lymphatics challenge the conventional paradigms of immune privilege, offering fresh perspectives on disease mechanisms. This work introduces groundbreaking therapeutic innovations, from precision immunotherapies to the controlled modulation of the BBB using nanotechnology and focused ultrasound. Moreover, we explore the fusion of immune modulation with neuromodulatory technologies, underscoring new frontiers for personalized medicine in previously intractable diseases. By synthesizing these advancements, we propose a transformative framework that integrates cutting-edge research with clinical translation, charting a bold path toward redefining CNS disease management in the era of precision neuroimmunology.

Use of Caenorhabditis elegans to Unravel the Tripartite Interaction of Kynurenine Pathway, UPRmt and Microbiome in Parkinson's Disease

The model organism Caenorhabditis elegans and its relationship with the gut microbiome are gaining traction, especially for the study of neurodegenerative diseases such as Parkinson's Disease (PD). Gut microbes are known to be able to alter kynurenine metabolites in the host, directly influencing innate immunity in C. elegans. While the mitochondrial unfolded protein response (UPRmt) was first characterized in C. elegans in 2007, its relevance in host-microbiome interactions has only become apparent in recent years. In this review, we provide novel insights into the current understanding of the microbiome-gut-brain axis with a focus on tripartite interactions between the UPRmt, kynurenine pathway, and microbiome in C. elegans, and explore their relationships for PD remediations.

Intestinal permeability disturbances: causes, diseases and therapy

Nowadays, a pathological increase in the permeability of the intestinal barrier (the so-called leaky gut) is increasingly being diagnosed. This condition can be caused by various factors, mainly from the external environment. Damage to the intestinal barrier entails a number of adverse phenomena: dysbiosis, translocation of microorganisms deep into the intestinal tissue, immune response, development of chronic inflammation. These phenomena can ultimately lead to a vicious cycle that promotes the development of inflammation and further damage to the barrier. Activated immune cells in mucosal tissues with broken barriers can migrate to other organs and negatively affect their functioning. Damaged intestinal barrier can facilitate the development of local diseases such as irritable bowel disease, inflammatory bowel disease or celiac disease, but also the development of systemic inflammatory diseases such as rheumatoid arthritis, ankylosing spondylitis, hepatitis, and lupus erythematosus, neurodegenerative or psychiatric conditions, or metabolic diseases such as diabetes or obesity. However, it must be emphasized that the causal links between a leaky gut barrier and the onset of certain diseases often remain unclear and require in-depth research. In light of recent research, it becomes crucial to prevent damage to the intestinal barrier, as well as to develop therapies for the barrier when it is damaged. This paper presents the current state of knowledge on the causes, health consequences and attempts to treat excessive permeability of the intestinal barrier.

Health by design; optimising our urban environmental microbiomes for human health

Humans have evolved in direct and intimate contact with their environment and the microbes that it contains, over a period of 2 million years. As a result, human physiology has become intrinsically linked to environmental microbiota. Urbanisation has reduced our exposure to harmful pathogens, however there is now increasing evidence that these same health-protective improvements in our environment may also be contributing to a hidden disease burden: immune dysregulation. Thoughtful and purposeful design has the potential to ameliorate these health concerns by providing sources of microbial diversity for human exposure. In this narrative review, we highlight the role of environmental microbiota in human health and provide insights into how we can optimise human health through well-designed cities, urban landscapes and buildings. The World Health Organization recommends there should be at least one public green space of least 0.5 ha in size within 300m of a place of residence. We argue that these larger green spaces are more likely to permit functioning ecosystems that deliver ecosystem services, including the provision of diverse aerobiomes. Urban planning must consider the conservation and addition of large public green spaces, while landscape design needs to consider how to maximise environmental, social and public health outcomes, which may include rewilding. Landscape designers need to consider how people use these spaces, and how to optimise utilisation, including for those who may experience challenges in access (e.g. those living with disabilities, people in residential care). There are also opportunities to improve health via building design that improves access to diverse environmental microbiota. Considerations include having windows that open, indoor plants, and the relationship between function, form and organization. We emphasise possibilities for re-introducing potentially health-giving microbial exposures into urban environments, particularly where the benefits of exposure to biodiverse environments may have been lost.

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.

Prevotella copri transplantation promotes neurorehabilitation in a mouse model of traumatic brain injury

BACKGROUND

The gut microbiota plays a critical role in regulating brain function through the microbiome-gut-brain axis (MGBA). Dysbiosis of the gut microbiota is associated with neurological impairment in Traumatic brain injury (TBI) patients. Our previous study found that TBI results in a decrease in the abundance of Prevotella copri (P. copri). P. copri has been shown to have antioxidant effects in various diseases. Meanwhile, guanosine (GUO) is a metabolite of intestinal microbiota that can alleviate oxidative stress after TBI by activating the PI3K/Akt pathway. In this study, we investigated the effect of P. copri transplantation on TBI and its relationship with GUO-PI3K/Akt pathway.

METHODS

In this study, a controlled cortical impact (CCI) model was used to induce TBI in adult male C57BL/6J mice. Subsequently, P. copri was transplanted by intragastric gavage for 7 consecutive days. To investigate the effect of the GUO-PI3K/Akt pathway in P. copri transplantation therapy, guanosine (GUO) was administered 2 h after TBI for 7 consecutive days, and PI3K inhibitor (LY294002) was administered 30 min before TBI. Various techniques were used to assess the effects of these interventions, including quantitative PCR, neurological behavior tests, metabolite analysis, ELISA, Western blot analysis, immunofluorescence, Evans blue assays, transmission electron microscopy, FITC-dextran permeability assay, gastrointestinal transit assessment, and 16 S rDNA sequencing.

RESULTS

P. copri abundance was significantly reduced after TBI. P. copri transplantation alleviated motor and cognitive deficits tested by the NSS, Morris's water maze and open field test. P. copri transplantation attenuated oxidative stress and blood-brain barrier damage and reduced neuronal apoptosis after TBI. In addition, P. copri transplantation resulted in the reshaping of the intestinal flora, improved gastrointestinal motility and intestinal permeability. Metabolomics and ELISA analysis revealed a significant increase in GUO levels in feces, serum and injured brain after P. copri transplantation. Furthermore, the expression of p-PI3K and p-Akt was found to be increased after P. copri transplantation and GUO treatment. Notably, PI3K inhibitor LY294002 treatment attenuated the observed improvements.

CONCLUSIONS

We demonstrate for the first time that P. copri transplantation can improve GI functions and alter gut microbiota dysbiosis after TBI. Additionally, P. copri transplantation can ameliorate neurological deficits, possibly via the GUO-PI3K/Akt signaling pathway after TBI.

Effects of the Pharmabiotic U-21 under Conditions of a Combined Neuroinflammatory Model of Parkinson's Disease in Rats

Data on the participation of microbiota in the development of Parkinson's disease allow us to discuss the ability of bacterial preparations to influence the processes leading to neurodegeneration. We studied the effect of oral administration of Limosilactobacillus fermentum U-21 lyophilisate on a model of Parkinson's disease in rats induced by combined intranigral injection of LPS and systemic administration of paraquat. The toxins significantly increased the number of missteps in the "narrowing beam walking" test, but a tendency to a decrease in this parameter was shown after treatment with U-21. It should be noted that U-21 did not reduce the neuronal death in the substantia nigra, but mitigated the inflammatory glial response, decreased the accumulation of phosphorylated α-synuclein and complement protein C3. Our study demonstrated the efficiency of the combined model of parkinsonism and reduction of proinflammatory changes under the influence of pharmabiotic without changes in the nigral neuronal death and motor deficits.

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.

Lysosomal storage, impaired autophagy and innate immunity in Gaucher and Parkinson's diseases: insights for drug discovery

Impairment of autophagic-lysosomal pathways is increasingly being implicated in Parkinson's disease (PD). GBA1 mutations cause the lysosomal storage disorder Gaucher disease (GD) and are the commonest known genetic risk factor for PD. GBA1 mutations have been shown to cause autophagic-lysosomal impairment. Defective autophagic degradation of unwanted cellular constituents is associated with several pathologies, including loss of normal protein homeostasis, particularly of α-synuclein, and innate immune dysfunction. The latter is observed both peripherally and centrally in PD and GD. Here, we will discuss the mechanistic links between autophagy and immune dysregulation, and the possible role of these pathologies in communication between the gut and brain in these disorders. Recent work in a fly model of neuronopathic GD (nGD) revealed intestinal autophagic defects leading to gastrointestinal dysfunction and immune activation. Rapamycin treatment partially reversed the autophagic block and reduced immune activity, in association with increased survival and improved locomotor performance. Alterations in the gut microbiome are a critical driver of neuroinflammation, and studies have revealed that eradication of the microbiome in nGD fly and mouse models of PD ameliorate brain inflammation. Following these observations, lysosomal-autophagic pathways, innate immune signalling and microbiome dysbiosis are discussed as potential therapeutic targets in PD and GD. This article is part of a discussion meeting issue 'Understanding the endo-lysosomal network in neurodegeneration'.

Gut dysbiosis and neurological modalities: An engineering approach via proteomic analysis of gut-brain axis

The human gut microbiota is a complex and dynamic community of microorganisms, that influence metabolic, neurodevelopmental, and immune pathways. Microbial dysbiosis, characterized by changes in microbial diversity and relative abundances, is implicated in the development of various chronic neurological and neurodegenerative disorders. These disorders are marked by the accumulation of pathological protein aggregates, leading to the progressive loss of neurons and behavioural functions. Dysregulations in protein-protein interaction networks and signalling complexes, critical for normal brain function, are common in neurological disorders but challenging to unravel, particularly at the neuron and synapse-specific levels. To advance therapeutic strategies, a deeper understanding of neuropathogenesis, especially during the progressive disease phase, is needed. Biomarkers play a crucial role in identifying disease pathophysiology and monitoring disease progression. Proteomics, a powerful technology, shows promise in accelerating biomarker discovery and aiding in the development of novel treatments. In this chapter, we provide an in-depth overview of how proteomic techniques, utilizing various biofluid samples from patients with neurological conditions and diverse animal models, have contributed valuable insights into the pathogenesis of numerous neurological disorders. We also discuss the current state of research, potential challenges, and future directions in proteomic approaches to unravel neuro-pathological conditions.

Lactiplantibacillus (Lactobacillus) plantarum as a Complementary Treatment to Improve Symptomatology in Neurodegenerative Disease: A Systematic Review of Open Access Literature

This systematic review addresses the use of Lactiplantibacillus (Lactobacillus) plantarum in the symptomatological intervention of neurodegenerative disease. The existence of gut microbiota dysbiosis has been associated with systemic inflammatory processes present in neurodegenerative disease, creating the opportunity for new treatment strategies. This involves modifying the strains that constitute the gut microbiota to enhance synaptic function through the gut-brain axis. Recent studies have evaluated the beneficial effects of the use of Lactiplantibacillus plantarum on motor and cognitive symptomatology, alone or in combination. This systematic review includes 20 research articles (n = 3 in human and n = 17 in animal models). The main result of this research was that the use of Lactiplantibacillus plantarum alone or in combination produced improvements in symptomatology related to neurodegenerative disease. However, one of the studies included reported negative effects after the administration of Lactiplantibacillus plantarum. This systematic review provides current and relevant information about the use of this probiotic in pathologies that present neurodegenerative processes such as Alzheimer's disease, Parkinson's disease and Multiple Sclerosis.

Involvement and repair of epithelial barrier dysfunction in allergic diseases

The epithelial barrier serves as a critical defense mechanism separating the human body from the external environment, fulfilling both physical and immune functions. This barrier plays a pivotal role in shielding the body from environmental risk factors such as allergens, pathogens, and pollutants. However, since the 19th century, the escalating threats posed by environmental pollution, global warming, heightened usage of industrial chemical products, and alterations in biodiversity have contributed to a noteworthy surge in allergic disease incidences. Notably, allergic diseases frequently exhibit dysfunction in the epithelial barrier. The proposed epithelial barrier hypothesis introduces a novel avenue for the prevention and treatment of allergic diseases. Despite increased attention to the role of barrier dysfunction in allergic disease development, numerous questions persist regarding the mechanisms underlying the disruption of normal barrier function. Consequently, this review aims to provide a comprehensive overview of the epithelial barrier's role in allergic diseases, encompassing influencing factors, assessment techniques, and repair methodologies. By doing so, it seeks to present innovative strategies for the prevention and treatment of allergic diseases.

Gut microbiome therapy: fecal microbiota transplantation vs live biotherapeutic products

The human intestine hosts a complex ecosystem of various microorganisms, collectively known as the gut microbiome, which significantly impacts human health. Disruptions in the gut microbiome are linked to various disorders, including gastrointestinal diseases, such as Clostridioides difficile infection and inflammatory bowel disease, as well as metabolic, neurological, oncologic conditions. Fecal microbiota transplantation (FMT) and live biotherapeutic products (LBPs) have emerged as prospective therapeutic procedures to restore microbial and metabolic balance in the gut. This review assesses the latest advancements, challenges, and therapeutic efficacy of FMT and LBPs, highlighting the need for standardization, safety, and long-term evaluation to optimize their clinical application.

Autophagic dysfunction and gut microbiota dysbiosis cause chronic immune activation in a Drosophila model of Gaucher disease

Mutations in the GBA1 gene cause the lysosomal storage disorder Gaucher disease (GD) and are the greatest known genetic risk factors for Parkinson's disease (PD). Communication between the gut and brain and immune dysregulation are increasingly being implicated in neurodegenerative disorders such as PD. Here, we show that flies lacking the Gba1b gene, the main fly orthologue of GBA1, display widespread NF-kB signalling activation, including gut inflammation, and brain glial activation. We also demonstrate intestinal autophagic defects, gut dysfunction, and microbiome dysbiosis. Remarkably, modulating the microbiome of Gba1b knockout flies, by raising them under germ-free conditions, partially ameliorates lifespan, locomotor and immune phenotypes. Moreover, we show that modulation of the immune deficiency (IMD) pathway is detrimental to the survival of Gba1 deficient flies. We also reveal that direct stimulation of autophagy by rapamycin treatment achieves similar benefits to germ-free conditions independent of gut bacterial load. Consistent with this, we show that pharmacologically blocking autophagosomal-lysosomal fusion, mimicking the autophagy defects of Gba1 depleted cells, is sufficient to stimulate intestinal immune activation. Overall, our data elucidate a mechanism whereby an altered microbiome, coupled with defects in autophagy, drive chronic activation of NF-kB signaling in a Gba1 loss-of-function model. It also highlights that elimination of the microbiota or stimulation of autophagy to remove immune mediators, rather than prolonged immunosuppression, may represent effective therapeutic avenues for GBA1-associated disorders.

The yeast prion protein Sup35 initiates α-synuclein pathology in mouse models of Parkinson's disease

Parkinson's disease (PD) is characterized by the pathologic aggregation and prion-like propagation of α-synuclein (α-syn). Emerging evidence shows that fungal infections increase the incidence of PD. However, the molecular mechanisms by which fungi promote the onset of PD are poorly understood. Here, we show that nasal infection with Saccharomyces cerevisiae (S. cerevisiae) in α-syn A53T transgenic mice accelerates the aggregation of α-syn. Furthermore, we found that Sup35, a prion protein from S. cerevisiae, is the key factor initiating α-syn pathology induced by S. cerevisiae. Sup35 interacts with α-syn and accelerates its aggregation in vitro. Notably, injection of Sup35 fibrils into the striatum of wild-type mice led to α-syn pathology and PD-like motor impairment. The Sup35-seeded α-syn fibrils showed enhanced seeding activity and neurotoxicity compared with pure α-syn fibrils in vitro and in vivo. Together, these observations indicate that the yeast prion protein Sup35 initiates α-syn pathology in PD.

The Involvement of Neuroinflammation in the Onset and Progression of Parkinson's Disease

Parkinson's disease is a neurodegenerative disease exhibiting the fastest growth in incidence in recent years. As with most neurodegenerative diseases, the pathophysiology is incompletely elucidated, but compelling evidence implicates inflammation, both in the central nervous system and in the periphery, in the initiation and progression of the disease, although it is not yet clear what triggers this inflammatory response and where it begins. Gut dysbiosis seems to be a likely candidate for the initiation of the systemic inflammation. The therapies in current use provide only symptomatic relief, but do not interfere with the disease progression. Nonetheless, animal models have shown promising results with therapies that target various vicious neuroinflammatory cascades. Translating these therapeutic strategies into clinical trials is still in its infancy, and a series of issues, such as the exact timing, identifying biomarkers able to identify Parkinson's disease in early and pre-symptomatic stages, or the proper indications of genetic testing in the population at large, will need to be settled in future guidelines.

The Impact of Microbiota on the Gut-Brain Axis: Examining the Complex Interplay and Implications

The association and interaction between the central nervous system (CNS) and enteric nervous system (ENS) is well established. Essentially ENS is the second brain, as we call it. We tried to understand the structure and function, to throw light on the functional aspect of neurons, and address various disease manifestations. We summarized how various neurological disorders influence the gut via the enteric nervous system and/or bring anatomical or physiological changes in the enteric nervous system or the gut and vice versa. It is known that stress has an effect on Gastrointestinal (GI) motility and causes mucosal erosions. In our literature review, we found that stress can also affect sensory perception in the central nervous system. Interestingly, we found that mutations in the neurohormone, serotonin (5-HT), would result in dysfunctional organ development and further affect mood and behavior. We focused on the developmental aspects of neurons and cognition and their relation to nutritional absorption via the gastrointestinal tract, the development of neurodegenerative disorders in relation to the alteration in gut microbiota, and contrariwise associations between CNS disorders and ENS. This paper further summarizes the synergetic relation between gastrointestinal and neuropsychological manifestations and emphasizes the need to include behavioral therapies in management plans.

A review of the auditory-gut-brain axis

Hearing loss places a substantial burden on medical resources across the world and impacts quality of life for those affected. Further, it can occur peripherally and/or centrally. With many possible causes of hearing loss, there is scope for investigating the underlying mechanisms involved. Various signaling pathways connecting gut microbes and the brain (the gut-brain axis) have been identified and well established in a variety of diseases and disorders. However, the role of these pathways in providing links to other parts of the body has not been explored in much depth. Therefore, the aim of this review is to explore potential underlying mechanisms that connect the auditory system to the gut-brain axis. Using select keywords in PubMed, and additional hand-searching in google scholar, relevant studies were identified. In this review we summarize the key players in the auditory-gut-brain axis under four subheadings: anatomical, extracellular, immune and dietary. Firstly, we identify important anatomical structures in the auditory-gut-brain axis, particularly highlighting a direct connection provided by the vagus nerve. Leading on from this we discuss several extracellular signaling pathways which might connect the ear, gut and brain. A link is established between inflammatory responses in the ear and gut microbiome-altering interventions, highlighting a contribution of the immune system. Finally, we discuss the contribution of diet to the auditory-gut-brain axis. Based on the reviewed literature, we propose numerous possible key players connecting the auditory system to the gut-brain axis. In the future, a more thorough investigation of these key players in animal models and human research may provide insight and assist in developing effective interventions for treating hearing loss.

Evaluation of plasma Short chain fatty acid levels as markers for Inflammatory bowel disease

BACKGROUND

Specific variations of short chain fatty acids in fecal samples have been shown for patients with inflammatory bowel disease. The aim of this study was to assess if Crohn's disease and ulcerative colitis are associated with altered concentrations of short chain fatty acids also in blood plasma.

METHOD

Between 2016-2019, Swedish adults referred to a tertiary center for colonoscopy were asked to participate in a cross-sectional study. Individuals with Crohn's disease or ulcerative colitis as well as individuals with no findings on the colonoscopy (defined as clean colon) were included in the study. Data on colonoscopy findings, blood samples (including haemoglobin, C-reactive protein and short chain fatty acid analysis) as well as a validated lifestyle questionnaire including 277 questions were collected from all participants. Linear regression was used to compare mean concentrations of short chain fatty acids between Crohn's disease, ulcerative colitis and clean colon.

RESULTS

The cohort consisted of 132 individuals with Crohn's disease, 119 with ulcerative colitis and 205 with clean colon. In the crude model, succinic acid was significantly lower (p < 0.05) among patients with Crohn's disease (mean 3.00 µM SE 0.10) and ulcerative colitis (mean 3.13 µM SE 0.10) in comparison to clean colon (mean 3.41 µM SE 0.08), however when adjusting for sex, age and diet the results did not remain statistically significant. No differences in plasma concentration of the other measured short chain fatty acids were detected.

CONCLUSION

Crohn's disease and ulcerative colitis are not associated with altered short chain fatty acid concentrations in plasma. Further research is needed to confirm or refute our findings.

New Pieces for an Old Puzzle: Approaching Parkinson's Disease from Translatable Animal Models, Gut Microbiota Modulation, and Lipidomics

Parkinson's disease (PD) is a severe neurodegenerative disease characterized by disabling motor alterations that are diagnosed at a relatively late stage in its development, and non-motor symptoms, including those affecting the gastrointestinal tract (mainly constipation), which start much earlier than the motor symptoms. Remarkably, current treatments only reduce motor symptoms, not without important drawbacks (relatively low efficiency and impactful side effects). Thus, new approaches are needed to halt PD progression and, possibly, to prevent its development, including new therapeutic strategies that target PD etiopathogeny and new biomarkers. Our aim was to review some of these new approaches. Although PD is complex and heterogeneous, compelling evidence suggests it might have a gastrointestinal origin, at least in a significant number of patients, and findings in recently developed animal models strongly support this hypothesis. Furthermore, the modulation of the gut microbiome, mainly through probiotics, is being tested to improve motor and non-motor symptoms and even to prevent PD. Finally, lipidomics has emerged as a useful tool to identify lipid biomarkers that may help analyze PD progression and treatment efficacy in a personalized manner, although, as of today, it has only scarcely been applied to monitor gut motility, dysbiosis, and probiotic effects in PD. Altogether, these new pieces should be helpful in solving the old puzzle of PD.

Role of enteric glia and microbiota-gut-brain axis in parkinson disease pathogenesis

The microbiota-gut-brain axis or simple gut-brain axis (GBA) is a complex and interactive bidirectional communication network linking the gut to the brain. Alterations in the composition of the gut microbiome have been linked to GBA dysfunction, central nervous system (CNS) inflammation, and dopaminergic degeneration, as those occurring in Parkinson's disease (PD). Besides inflammation, the activation of brain microglia is known to play a central role in the damage of dopaminergic neurons. Inflammation is attributed to the toxic effect of aggregated α-synuclein, in the brain of PD patients. It has been suggested that the α-synuclein misfolding might begin in the gut and spread "prion-like", via the vagus nerve into the lower brainstem and ultimately to the midbrain, known as the Braak hypothesis. In this review, we discuss how the microbiota-gut-brain axis and environmental influences interact with the immune system to promote a pro-inflammatory state that is involved in the initiation and progression of misfolded α-synuclein proteins and the beginning of the early non-motor symptoms of PD. Furthermore, we describe a speculative bidirectional model that explains how the enteric glia is involved in the initiation and spreading of inflammation, epithelial barrier disruption, and α-synuclein misfolding, finally reaching the central nervous system and contributing to neuroinflammatory processes involved with the initial non-motor symptoms of PD.

Microbiome-gut-brain dysfunction in prodromal and symptomatic Lewy body diseases

Lewy body diseases, such as Parkinson's disease and dementia with Lewy bodies, vary in their clinical phenotype but exhibit the same defining pathological feature, α-synuclein aggregation. Microbiome-gut-brain dysfunction may play a role in the initiation or progression of disease processes, though there are multiple potential mechanisms. We discuss the need to evaluate gastrointestinal mechanisms of pathogenesis across Lewy body diseases, as disease mechanisms likely span across diagnostic categories and a 'body first' clinical syndrome may better account for the heterogeneity of clinical presentations across the disorders. We discuss two primary hypotheses that suggest that either α-synuclein aggregation occurs in the gut and spreads in a prion-like fashion to the brain or systemic inflammatory processes driven by gastrointestinal dysfunction contribute to the pathophysiology of Lewy body diseases. Both of these hypotheses posit that dysbiosis and intestinal permeability are key mechanisms and potential treatment targets. Ultimately, this work can identify early interventions targeting initial disease pathogenic processes before the development of overt motor and cognitive symptoms.

Effects of a probiotic suspension Symprove™ on a rat early-stage Parkinson's disease model

An increasing number of studies in recent years have focused on the role that the gut may play in Parkinson's Disease (PD) pathogenesis, suggesting that the maintenance of a healthy gut may lead to potential treatments of the disease. The health of microbiota has been shown to be directly associated with parameters that play a potential role in PD including gut barrier integrity, immunity, function, metabolism and the correct functioning of the gut-brain axis. The gut microbiota (GM) may therefore be employed as valuable indicators for early diagnosis of PD and potential targets for preventing or treating PD symptoms. Preserving the gut homeostasis using probiotics may therefore lead to a promising treatment strategy due to their known benefits in improving constipation, motor impairments, inflammation, and neurodegeneration. However, the mechanisms underlying the effects of probiotics in PD are yet to be clarified. In this project, we have tested the efficacy of an oral probiotic suspension, Symprove™, on an established animal model of PD. Symprove™, unlike many commercially available probiotics, has been shown to be resistant to gastric acidity, improve symptoms in gastrointestinal diseases and improve gut integrity in an in vitro PD model. In this study, we used an early-stage PD rat model to determine the effect of Symprove™ on neurodegeneration and neuroinflammation in the brain and on plasma cytokine levels, GM composition and short chain fatty acid (SCFA) release. Symprove™ was shown to significantly influence both the gut and brain of the PD model. It preserved the gut integrity in the PD model, reduced plasma inflammatory markers and changed microbiota composition. The treatment also prevented the reduction in SCFAs and striatal inflammation and prevented tyrosine hydroxylase (TH)-positive cell loss by 17% compared to that observed in animals treated with placebo. We conclude that Symprove™ treatment may have a positive influence on the symptomology of early-stage PD with obvious implications for the improvement of gut integrity and possibly delaying/preventing the onset of neuroinflammation and neurodegeneration in human PD patients.

Immunological Features of LRRK2 Function and Its Role in the Gut-Brain Axis Governing Parkinson's Disease

Emerging evidence implicates intestinal involvement in the onset and/or progression on the selective degeneration of dopaminergic neurons characterizing Parkinson's disease (PD). On the one hand, there are studies supporting the Braak hypothesis that holds that pathologic α-synuclein, a hallmark of PD, is secreted by enteric nerves into intestinal tissue and finds its way to the central nervous system (CNS) via retrograde movement in the vagus nerve. On the other hand, there is data showing that cells bearing leucine-rich repeat kinase 2 (LRRK2), a signaling molecule with genetic variants associated with both PD and with inflammatory bowel disease, can be activated in intestinal tissue and contribute locally to intestinal inflammation, or peripherally to PD pathogenesis via cell trafficking to the CNS. Importantly, these gut-centered factors affecting PD development are not necessarily independent of one another: they may interact and enhance their respective pathologic functions. In this review, we discuss this possibility by analysis of studies conducted in recent years focusing on the ability of LRRK2 to shape immunologic responses and the role of α-synuclein in influencing this ability.

The effectiveness of photobiomodulation therapy in modulation the gut microbiome dysbiosis related diseases

Maintaining a healthy balance between commensal, and pathogenic bacteria within the gut microbiota is crucial for ensuring the overall health, and well-being of the host. In fact, by affecting innate, and adaptive immune responses, the gut microbiome plays a key role in maintaining intestinal homeostasis and barrier integrity. Dysbiosis is the loss of beneficial microorganisms and the growth of potentially hazardous microorganisms in a microbial community, which has been linked to numerous diseases. As the primary inducer of circadian rhythm, light can influence the human intestinal microbiome. Photobiomodulation therapy (PBMT), which is the use of red (630-700 nm), and near-infrared light (700 and 1200 nm), can stimulate healing, relieve pain, and reduce inflammation, and affect the circadian rhythm and gut microbiome beneficially. Our focus in this paper is on the effects of PBMT on gut microbiota, to provide an overview of how it can help control gut microbiota dysbiosis-related disorders.

The modulation of macrophage subsets in celiac disease pathogenesis

BACKGROUND

So far, limited studies have focused on the role of Macrophages (MQs) in the development or progression of celiac disease (CD). Researchers believe that increasing knowledge about the function of MQs in inflammatory disorders plays a critical role in finding a new treatment for these kinds of diseases.

MAIN BODY

CD is a permanent autoimmune intestinal disorder triggered by gluten exposure in predisposed individuals. This disorder happens due to the loss of intestinal epithelial barrier integrity characterized by dysregulated innate and adaptive immune responses. MQs are known as key players of the innate immune system that link innate and adaptive immunity. MQs of human intestinal lamina propria participate in maintaining tissue homeostasis, and also intestinal inflammation development. Previous studies suggested that gliadin triggers a proinflammatory phenotype (M1 MQ) in human primary MQs. Moreover, M2-related immunosuppressive mediators are also present in CD. In fact, CD patients present an impaired transition from pro-inflammatory to anti-inflammatory responses due to inappropriate responses to gliadin peptides.

CONCLUSION

The M1/M2 MQs polarization balancing regulators can be considered novel therapeutic targets for celiac disease.

Association between Parkinson's Disease and Diabetes Mellitus: From Epidemiology, Pathophysiology and Prevention to Treatment

Diabetes mellitus (DM) and Parkinson's disease (PD) are both age-related diseases of global concern being among the most common chronic metabolic and neurodegenerative diseases, respectively. While both diseases can be genetically inherited, environmental factors play a vital role in their pathogenesis. Moreover, DM and PD have common underlying molecular mechanisms, such as misfolded protein aggregation, mitochondrial dysfunction, oxidative stress, chronic inflammation, and microbial dysbiosis. Recently, epidemiological and experimental studies have reported that DM affects the incidence and progression of PD. Moreover, certain antidiabetic drugs have been proven to decrease the risk of PD and delay its progression. In this review, we elucidate the epidemiological and pathophysiological association between DM and PD and summarize the antidiabetic drugs used in animal models and clinical trials of PD, which may provide reference for the clinical translation of antidiabetic drugs in PD treatment.

Integrating nutriepigenomics in Parkinson's disease management: New promising strategy in the omics era

Parkinson's disease (PD) is the most prevalent brain motor disorder and is frequently regarded as an idiopathic and sporadic disease due to its unclear etiology. Although the pathological mechanisms of PD have already been investigated at various omics levels, no disease-modifying drugs are currently available. At the moment, treatments can only provide symptomatic relief to control or improve motor symptoms. Parkinson's disease is a multifactorial disease, the development and progression of which are influenced by multiple factors, including the genetic markups and the environment. As an indispensable component of our daily life, nutrition is considered one of the most robust environmental factors affecting our health. Consequently, depending on our dietary habits, nutrition can either induce or reduce our susceptibility to PD. Epigenetic mechanisms regulate gene expression through DNA methylation, histone modifications, and non-coding RNAs (ncRNAs) activity. Accumulating evidence from nutriepigenomics studies has reported altered epigenetic mechanisms in clinical and pre-clinical PD models, and the potential role of nutrition in modifying the changes. In addition, through nutrigenetics and nutrigenomics studies, the diet-gene, and gene-diet interactions concerning PD development and progression have been investigated. Herein, current findings on the roles of nutrition in epigenetic mechanisms underpinning PD development and progression are discussed. Recent advancements in the multi-omics approach in PD nutrition research are also underlined. The ability of nutrients to influence epigenetic mechanisms and the availability of multi-omics applications compel the immediate use of personalized nutrition as adjuvant therapy for PD.

GRID2 aberration leads to disturbance in neuroactive ligand-receptor interactions via changes to the species richness and composition of gut microbes

OBJECTIVE

To explore the association between phenotype and the gut microbiome following damage to the GRID2 gene.

METHODS

Ten wild-type (WT) mice and 11 GRID2 knockout heterozygous mice (GRID2(±)) of a similar age and weight were randomly selected. Fresh feces were collected from both groups of mice under specified pathogen-free (SPF) conditions. The bacterial genomes were extracted from the feces, the 16S rRNA genes were sequenced, and the data were analyzed to determine clustering, diversity, abundance, LEfSe, and functional differences. Differential expression and enrichment analyses of the RNA-seq and protein levels of the GRID2 gene were also performed using data in the GENE database and the new version of the Human Protein Atlas portal (www.proteinatlas.org).

RESULTS

The diversity analysis showed differences in species composition between the two groups at different levels. At phylum level, compared with the WT group, the distribution was more bacteriophages but showed a lower content of Tenericutes in the GRID2(±) group. At the order level, compared with the WT group, a higher content of Actinomycetales and Bacteriophages were found in the GRID2(±) group. The species difference analysis showed that 17 species, including E. faecalis and Paracoccus spp., showed differences in content between the two groups. LEfSe analysis showed that the abundance of Clostridiaceae, Allobaculum, and other groups decreased in the GRID2(±) group compared with the WT group, while Mycoplasma, Sphingomonas, and Alphaproteobacteria increased in abundance. Functional analysis revealed eight differential functions between the WT and GRID2(±) group (P &lt; 0.05). The most significantly disrupted were neuroactive ligand-receptor interactions (P &lt; 9.99e-4). In addition, the differential expression and enrichment analyses performed at RNA-seq and protein levels revealed that the GRID2 gene showed organ-specific expression and was mainly enriched in the brain tissue.

CONCLUSIONS

Compared with the WT group, the defective GRID2 gene affected the species richness and composition of gut microbes in the GRID2(±) mice, which in turn affected the function of gut microbes, leading to the disruption of neuroactive ligand-receptor interactions. Our findings indicate that the host gene, GRID2, can influence the abundance of a subset of gut microbes but the exact mechanisms still need further investigation.

What Are the Key Gut Microbiota Involved in Neurological Diseases? A Systematic Review

There is a growing body of evidence highlighting there are significant changes in the gut microbiota composition and relative abundance in various neurological disorders. We performed a systematic review of the different microbiota altered in a wide range of neurological disorders (Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis, and stroke). Fifty-two studies were included representing 5496 patients. At the genus level, the most frequently involved microbiota are Akkermansia, Faecalibacterium, and Prevotella. The overlap between the pathologies was strongest for MS and PD, sharing eight genera (Akkermansia, Butyricicoccus, Bifidobacterium, Coprococcus, Dorea, Faecalibacterium, Parabacteroides, and Prevotella) and PD and stroke, sharing six genera (Enterococcus, Faecalibacterium, Lactobacillus, Parabacteroides, Prevotella, and Roseburia). The identification signatures overlapping for AD, PD, and MS raise the question of whether these reflect a common etiology or rather common consequence of these diseases. The interpretation is hampered by the low number and low power for AD, ALS, and stroke with ample opportunity for false positive and false negative findings.

Dysbiosis of Gut Microbiota from the Perspective of the Gut-Brain Axis: Role in the Provocation of Neurological Disorders

The gut-brain axis is a bidirectional communication network connecting the gastrointestinal tract and central nervous system. The axis keeps track of gastrointestinal activities and integrates them to connect gut health to higher cognitive parts of the brain. Disruption in this connection may facilitate various neurological and gastrointestinal problems. Neurodegenerative diseases are characterized by the progressive dysfunction of specific populations of neurons, determining clinical presentation. Misfolded protein aggregates that cause cellular toxicity and that aid in the collapse of cellular proteostasis are a defining characteristic of neurodegenerative proteinopathies. These disorders are not only caused by changes in the neural compartment but also due to other factors of non-neural origin. Mounting data reveal that the majority of gastrointestinal (GI) physiologies and mechanics are governed by the central nervous system (CNS). Furthermore, the gut microbiota plays a critical role in the regulation and physiological function of the brain, although the mechanism involved has not yet been fully interpreted. One of the emerging explanations of the start and progression of many neurodegenerative illnesses is dysbiosis of the gut microbial makeup. The present understanding of the literature surrounding the relationship between intestinal dysbiosis and the emergence of certain neurological diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and multiple sclerosis, is the main emphasis of this review. The potential entry pathway of the pathogen-associated secretions and toxins into the CNS compartment has been explored in this article at the outset of neuropathology. We have also included the possible mechanism of undelaying the synergistic effect of infections, their metabolites, and other interactions based on the current understanding.

Molecular and Cellular Interactions in Pathogenesis of Sporadic Parkinson Disease

An increasing number of the population all around the world suffer from age-associated neurodegenerative diseases including Parkinson’s disease (PD). This disorder presents different signs of genetic, epigenetic and environmental origin, and molecular, cellular and intracellular dysfunction. At the molecular level, α-synuclein (αSyn) was identified as the principal molecule constituting the Lewy bodies (LB). The gut microbiota participates in the pathogenesis of PD and may contribute to the loss of dopaminergic neurons through mitochondrial dysfunction. The most important pathogenetic link is an imbalance of Ca²⁺ ions, which is associated with redox imbalance in the cells and increased generation of reactive oxygen species (ROS). In this review, genetic, epigenetic and environmental factors that cause these disorders and their cause-and-effect relationships are considered. As a constituent of environmental factors, the example of organophosphates (OPs) is also reviewed. The role of endothelial damage in the pathogenesis of PD is discussed, and a ‘triple hit hypothesis’ is proposed as a modification of Braak’s dual hit one. In the absence of effective therapies for neurodegenerative diseases, more and more evidence is emerging about the positive impact of nutritional structure and healthy lifestyle on the state of blood vessels and the risk of developing these diseases.

The Role of Diet and Dietary Patterns in Parkinson's Disease

Parkinson's Disease (PD) is a neurodegenerative disorder associated with diminished nutrition status and decreased quality of life. While the prevalence of PD is expected to increase, no preventative or curative therapy for PD exists at this time. Although nutrition and diet represent modifiable risk factors for reducing chronic disease risk, research on the impact of single nutrients on PD has yielded mixed results. As a result, this single-nutrient approach may be the driving force behind the inconsistency, and a holistic dietary approach may overcome this inconsistency by accounting for the interactions between nutrients. The following review aims to examine the impact of a generally healthy dietary pattern, the protein-restricted diet (PRD), the ketogenic diet (KD), the Mediterranean diet (MD), and the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet on PD risk, progression, and severity. While most of the included studies support the role of diet and dietary patterns in reducing the risk of PD or alleviating PD severity, the inconsistent results and need for further evidence necessitate more research being conducted before making dietary recommendations. Research on the potential beneficial effects of dietary patterns on PD should also investigate potential risks.

New Insights on the Role of Bioactive Food Derivatives in Neurodegeneration and Neuroprotection

Over the last three decades, neurodegenerative diseases have received increasing attention due to their frequency in the aging population and the social and economic burdens they are posing. In parallel, an era's worth of research in neuroscience has shaped our current appreciation of the complex relationship between nutrition and the central nervous system. Particular branches of nutrition continue to galvanize neuroscientists, in particular the diverse roles that bioactive food derivatives play on health and disease. Bioactive food derivatives are nowadays recognized to directly impact brain homeostasis, specifically with respect to their actions on cellular mechanisms of oxidative stress, neuroinflammation, mitochondrial dysfunction, apoptosis and autophagy. However, ambiguities still exist regarding the significance of the influence of bioactive food derivatives on human health. In turn, gut microbiota dysbiosis is emerging as a novel player in the pathogenesis of neurodegenerative diseases. Currently, several routes of communication exist between the gut and the brain, where molecules are either released in the bloodstream or directly transported to the CNS. As such, bioactive food derivatives can modulate the complex ecosystem of the gut-brain axis, thus, targeting this communication network holds promises as a neuroprotective tool. This review aims at addressing one of the emerging aspects of neuroscience, particularly the interplay between food bioactive derivatives and neurodegeneration. We will specifically address the role that polyphenols and omega-3 fatty acids play in preventing neurodegenerative diseases and how dietary intervention complements available pharmacological approaches.

Probiotics treatment for Parkinson disease: a systematic review and meta-analysis of clinical trials

BACKGROUND AND AIMS

People with Parkinson disease (PwP) exhibit gut dysbiosis and considerable gastrointestinal (GI) symptoms. Probiotics, beneficial strains of microorganisms, supplement and optimize the intestinal environment and alleviate GI symptoms among elderly people. We conducted a systematic review and meta-analysis of clinical trials to investigate the effects of probiotics on PwP.

METHODS

We searched the PubMed, Embase, and Cochrane Library databases. Major outcomes were the effects on GI symptoms, including bowel movement and stool characteristics. This study was registered with PROSPERO (CRD42021262036).

RESULTS

Six randomized controlled trials (RCTs) and two open-label studies were included. Most of the probiotic regimens were based on Lactobacillus and Bifidobacterium. Six studies investigated the benefit of probiotics for GI symptoms, especially for PwP with functional constipation, and two RCTs assessed probiotics' effect on systematic metabolism and inflammation. In the meta-analysis, probiotic treatment significantly increased the frequency of bowel movements among PwP (mean difference [MD]: 1.06 /week, 95% confidence interval [CI]: 0.61 to 1.51, p < 0.001, I2 = 40%). Additionally, probiotic treatment significantly normalized stool consistency (standard MD: 0.61, 95% CI = 0.31 to 0.91, p < 0.001, I2 = 0%).

CONCLUSIONS

Although the probiotic compositions varied, probiotic treatment significantly attenuated constipation for PwP and exhibited possible systematic effects on inflammation and metabolism. Given the tolerability of probiotics, the present meta-analysis may provide more consolidated evidence of the benefit of probiotics on constipation in PwP and a possible new therapeutic approach for disease modification.

Obesity and the Brain

Innate and adaptive immunity are essential for neurodevelopment and central nervous system (CNS) homeostasis; however, the fragile equilibrium between immune and brain cells can be disturbed by any immune dysregulation and cause detrimental effects. Accumulating evidence indicates that, despite the blood-brain barrier (BBB), overactivation of the immune system leads to brain vulnerability that increases the risk of neuropsychiatric disorders, particularly upon subsequent exposure later in life. Disruption of microglial function in later life can be triggered by various environmental and psychological factors, including obesity-driven chronic low-grade inflammation and gut dysbiosis. Increased visceral adiposity has been recognized as an important risk factor for multiple neuropsychiatric conditions. The review aims to present our current understanding of the topic.

Adverse events of intestinal microbiota transplantation in randomized controlled trials: a systematic review and meta-analysis

Background

Intestinal microbiota transplantation (IMT) has been recognized as an effective treatment for recurrent Clostridium difficile infection (rCDI) and a novel treatment option for other diseases. However, the safety of IMT in patients has not been established.

Aims

This systematic review and meta-analysis was conducted to assess the safety of IMT.

Methods

We systematically reviewed all randomized controlled trials (RCTs) of IMT studies published up to 28 February 2021 using databases including PubMed, EMBASE and the Cochrane Library. Studies were excluded if they did not report adverse events (AEs). Two authors independently extracted the data. The relative risk (RR) of serious adverse events (SAEs) and common adverse events (CAEs) were estimated separately, as were predefined subgroups. Publication bias was evaluated by a funnel plot and Egger’s regression test.

Results

Among 978 reports, 99 full‐text articles were screened, and 20 articles were included for meta-analysis, involving 1132 patients (603 in the IMT group and 529 in the control group). We found no significant difference in the incidence of SAEs between the IMT group and the control group (RR = 1.36, 95% CI 0.56–3.31, P = 0.50). Of these 20 studies, 7 described the number of patients with CAEs, involving 360 patients (195 in the IMT group and 166 in the control group). An analysis of the eight studies revealed that the incidence of CAEs was also not significantly increased in the IMT group compared with the control group (RR = 1.06, 95% CI  0.91–1.23, P = 0.43). Subgroup analysis showed that the incidence of CAEs was significantly different between subgroups of delivery methods (P_(CAE) = 0.04), and the incidence of IMT-related SAEs and CAEs was not significantly different in the other predefined subgroups.

Conclusion

Currently, IMT is widely used in many diseases, but its associated AEs should not be ignored. To improve the safety of IMT, patients' conditions should be fully evaluated before IMT, appropriate transplantation methods should be selected, each operative step of faecal bacteria transplantation should be strictly controlled, AE management mechanisms should be improved, and a close follow-up system should be established.

Constipation Predicts Cognitive Decline in Parkinson's Disease: Results from the COPPADIS Cohort at 2-Year Follow-up and Comparison with a Control Group

BACKGROUND

Constipation has been linked to cognitive impairment development in Parkinson's disease (PD).

OBJECTIVE

Our aim was to analyze cognitive changes observed in PD patients and controls from a Spanish cohort with regards to the presence or not of constipation.

METHODS

PD patients and controls recruited from 35 centers of Spain from the COPPADIS cohort from January 2016 to November 2017 were followed-up during 2 years. The change in cognitive status from baseline (V0) to 2-year follow-up was assessed with the PD-CRS (Parkinson's Disease Cognitive Rating Scale). Subjects with a score ≥1 on item 21 of the NMSS (Non-Motor Symptoms Scale) at baseline (V0) were considered as "with constipation". Regression analyses were applied for determining the contribution of constipation in cognitive changes.

RESULTS

At V0, 39.7% (198/499) of PD patients presented constipation compared to 11.4% of controls (14/123) (p < 0.0001). No change was observed in cognitive status (PD-CRS total score) neither in controls without constipation (from 100.24±13.72 to 100.27±13.68; p = 0.971) and with constipation (from 94.71±10.96 to 93.93±13.03; p = 0.615). The PD-CRS total score decreased significantly in PD patients with constipation (from 89.14±15.36 to 85.97±18.09; p < 0.0001; Coehn's effect = -0.35) compared to patients without constipation (from 93.92±15.58 to 93.14±17.52; p = 0.250) (p = 0.018). In PD patients, to suffer from constipation at V0 was associated with a decrease in the PD-CRS total score from V0 to V2 (β= -0.1; 95% CI, -4.36 - -0.27; p = 0.026) and having cognitive impairment at V2 (OR = 1.79; 95% CI, 1.01 - 3.17; p = 0.045).

CONCLUSION

Constipation is associated with cognitive decline in PD patients but not in controls.

Effects of Cannabidiol on Parkinson’s Disease in a Transgenic Mouse Model by Gut-Brain Metabolic Analysis

Parkinson's disease (PD) is a common neurodegenerative disease characterized by a disorder of the dopaminergic system in the midbrain, causing classical PD motor symptoms. The therapeutic effect of cannabidiol (CBD) on PD has been a research frontier in recent years. However, the pathogenesis of PD and the therapeutic mechanism of cannabinoid remain unclear. To further study the causes of PD and the effect of CBD on PD, we exposed the PD transgenic mouse model to CBD and then estimated the motorial and postural coordination through a modified swim test. Afterwards, the mechanism was investigated via the histopathology of substantia nigra and the gut-brain metabolic analysis in the approach of UHPLC-TOF-MS. The results showed that CBD significantly improved motor deficits of PD model and protected the substantia nigra area. The metabolic function of fatty acid biosynthesis, arginine biosynthesis/metabolism, butanoate (ketone body) metabolism, β-alanine metabolism, and pantothenate/CoA biosynthesis was highlighted in the pathological and therapeutic process along the gut-brain axis. In conclusion, CBD could attenuate PD via the neuroprotective effect on the midbrain. The attenuation of the central nervous system in turn improved motor performance of PD, which might be partially induced by the metabolic interaction between the gut-brain. In view of gut-brain metabolomics, the mechanism of PD pathogenesis and the effect of CBD on PD are highly related to the biosynthesis and metabolism of energy and essential substance.

Risk of Neurodegenerative Diseases in Patients with Inflammatory Bowel Disease: A Nationwide Population-based Cohort Study

BACKGROUND AND AIMS

Although recent studies have reported that inflammatory bowel disease [IBD] is associated with the development of neurodegenerative diseases via chronic intestinal inflammation and the gut-brain axis, there is insufficient evidence supporting this notion. The aim of this study was to determine the risk of neurodegenerative diseases including Parkinson's disease [PD] and Alzheimer's disease [AD] in patients with IBD.

METHODS

Using the National Health Insurance Service data for the entire Korean population, we identified patients with IBD and controls from 2009 to 2011 and followed them up until 2017. We selected the controls in a 1:4 ratio based on age and sex for comparison with cases.

RESULTS

Of 24 830 IBD patients and 99 320 non-IBD controls, 98 IBD patients and 256 controls developed PD, and 644 IBD patients and 2303 controls developed AD. The overall neurodegenerative disease risk was higher in IBD patients (PD: adjusted hazard ratio [HR], 1.56; 95% confidence interval [CI], 1.24-1.97; AD: adjusted HR, 1.14; 95% CI, 1.05-1.25). Younger IBD patients aged 40-65 years had a higher risk of PD compared with controls [adjusted HR, 2.34; 1.63-3.35]. In contrast, patients aged ≥65 years had an increased risk of AD compared with controls [adjusted HR, 1.14; 1.04-1.25]. In a nested case-control study of the IBD cohort, patients aged ≥65 years and the female sex were risk factors for AD, whereas living in an urban area was protective against AD.

CONCLUSIONS

The risk of neurodegenerative diseases was higher in IBD patients than in the non-IBD population.

Remote Photobiomodulation Treatment for the Clinical Signs of Parkinson's Disease: A Case Series Conducted During COVID-19

Objective: To assess whether remote application of photobiomodulation (PBM) is effective in reducing clinical signs of Parkinson's disease (PD). Background: PD is a progressive neurodegenerative disease for which there is no cure and few treatment options. There is a strong link between the microbiome-gut-brain axis and PD. PBM in animal models can reduce the signs of PD and protect the neurons from damage when applied directly to the head or to remote parts of the body. In a clinical study, PBM has been shown to improve clinical signs of PD for up to 1 year. Methods: Seven participants were treated with PBM to the abdomen and neck three times per week for 12 weeks. Participants were assessed for mobility, balance, cognition, fine motor skill, and sense of smell on enrolment, after 12 weeks of treatment in a clinic and after 33 weeks of home treatment. Results: A number of clinical signs of PD were shown to be improved by remote PBM treatment, including mobility, cognition, dynamic balance, spiral test, and sense of smell. Improvements were individual to the participant. Some improvements were lost for certain participants during at-home treatment, which coincided with a number of enforced coronavirus disease 2019 (COVID-19) pandemic lockdown periods. Conclusions: Remote application of PBM was shown to be an effective treatment for a number of clinical signs of PD, with some being maintained for 45 weeks, despite lockdown restrictions. Improvements in clinical signs were similar to those seen with the application of remote plus transcranial PBM treatment in a previous study. Clinical Trial Registration number: U1111-1205-2035.

Intestinal Permeability, Dysbiosis, Inflammation and Enteric Glia Cells: The Intestinal Etiology of Parkinson’s Disease

The scientific and medical communities are becoming more aware of the substantial relationship between the function of the central nervous system (CNS) and the state of the gut environment. Parkinson's disease (PD) is a neurodegenerative disorder that affects the nigrostriatal pathway in the midbrain, presenting not only motor symptoms but also various non-motor manifestations, including neuropsychiatric symptoms and gastrointestinal (GI) symptoms. Over time, our knowledge of PD has progressed from the detection of midbrain dopaminergic deficits to the identification of a multifaceted disease with a variety of central and peripheral manifestations, with increased attention to the intestinal tract. Accumulating evidence has revealed that intestinal disorders are not only the peripheral consequence of PD pathogenesis, but also the possible pathological initiator decades before it progresses to the CNS. Here, we summarized recent research findings on the involvement of the intestinal environment in PD, with an emphasis on the involvement of the intestinal barrier, microbiome and its metabolites, inflammation, and enteric glial cells

Gut microbiota relieves inflammation in the substantia nigra of chronic Parkinson's disease by protecting the function of dopamine neurons

The composition of the intestinal flora of patients with Parkinson's disease (PD) can change. However, whether reshaping the gut microbial composition can treat PD remains to be seen. The present study evaluated the effect of intestinal flora in the treatment of PD in a C57BL/6 mouse PD model induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Chronic, low-dose, MPTP-treated mice exhibited upregulated gene expression levels of TNF-α and IL-1β in the substantia nigra (SN) of the mice, and induced intestinal microbial disorders. This indicated that the chronic low-dose MPTP model could be used to evaluate the progress of early intestinal pathology and intestinal flora imbalance in PD. After transplantation of faecal bacteria to MPTP-induced PD mice, the level of inflammation in the SN of the mice was reduced, and motor dysfunction was alleviated. Notably, faecal microbiota transplantation (FMT) upregulated the abundance of Blautia but downregulated Anaerostipes, Bifidobacterium, ASF356 and Ruminococcus in the gut of PD mice. In addition, FMT reduced the activation of microglia and astrocytes in the SN and reduced the expression levels of GSK3β, IL-1β, inducible nitric oxide synthase and phosphorylated PTEN in the SN. Overall, the present study demonstrated that gut microbial dysfunction is associated with the pathogenesis of PD, and that FMT can protect PD mice by inhibiting neuroinflammation.

Efficacy of probiotics for managing infantile colic due to their anti-inflammatory properties: a meta-analysis and systematic review

BACKGROUND

Infantile colic (IC) is excessive crying in otherwise healthy children. Despite vast research efforts, its etiology remains unknown.

PURPOSE

Most treatments for IC carry various side effects. The collection of evidence may inform researchers of new strategies for the management and treatment of IC as well as new clues for understanding its pathogenesis. This review and meta-analysis aimed to evaluate the efficacy and possible mechanisms of probiotics for mananaging IC.

METHODS

Ten papers met the study inclusion and exclusion criteria, and the meta-analysis was conducted using Review Manager (RevMan) software and a random-effects model.

RESULTS

This meta-analysis revealed that probiotics are effective for treating infantile colic, while the review showed that this efficacy may be due to their anti-inflammatory effects.

CONCLUSION

Probiotics may be an important treatment option for managing infantile colic due to their anti-inflammatory properties.