Probiotics and the Treatment of Parkinson's Disease: An Update

Fecal Microbiota Transplantation for Treatment of Parkinson Disease: A Randomized Clinical Trial

Importance

Dysbiosis has been robustly demonstrated in Parkinson disease (PD), and fecal microbiota transplantation (FMT) has shown promising effects in preclinical PD models.

Objective

To assess the safety and symptomatic efficacy of colonic single-dose anaerobically prepared FMT.

Design, Setting, and Participants

This was a double-blind, placebo-controlled, randomized clinical trial conducted between November 2020 and June 2023 with a follow-up period of 12 months at 4 hospitals in Finland. Patients with PD aged 35 to 75 years in Hoehn & Yahr stage 1-3 with a mild to moderate symptom burden and dysbiosis of fecal microbiota were included. Of 229 patients screened, 48 were randomized and 47 received the intervention. One patient discontinued due to worsening of PD symptoms. Two further patients were excluded before analysis and 45 were included in the intention-to-treat analysis.

Intervention

Participants were randomized in a 2:1 ratio to receive FMT or placebo via colonoscopy.

Main Outcomes and Measures

The primary end point was the change of Movement Disorder Society Unified Parkinson's Disease Rating Scale parts I-III (part III off medication) at 6 months. Safety was assessed by recording adverse events (AEs).

Results

The median (IQR) age was 65 (52.5-70.0) years in the placebo group and 66 (59.25-69.75) years in the FMT group; 9 (60.0%) and 16 (53.3%) patients were male in the placebo group and the FMT group, respectively. The primary outcome did not differ between the groups (0.97 points, 95% CI, -5.10 to 7.03, P = .75). Gastrointestinal AEs were more frequent in the FMT group (16 [53%] vs 1 [7%]; P = .003). Secondary outcomes and post hoc analyses showed stronger increase of dopaminergic medication and improvement of certain motor and nonmotor outcomes in the placebo group. Microbiota changes were more pronounced after FMT but differed by donor. Nevertheless, dysbiosis status was reversed more frequently in the placebo group.

Conclusions and Relevance

FMT was safe but did not offer clinically meaningful improvements. Further studies-for example, through modified FMT approaches or bowel cleansing-are warranted regarding the specific impact of donor microbiota composition and dysbiosis conversion on motor and nonmotor outcomes as well as medication needs in PD.

Trial Registration

ClinicalTrials.gov Identifier: NCT04854291.

Differentiation and regulation of CD4+ T cell subsets in Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease, and its hallmark pathological features are the loss of dopaminergic (DA) neurons in the midbrain substantia nigra pars compacta (SNpc) and the accumulation of alpha-synuclein (α-syn). It has been shown that the integrity of the blood-brain barrier (BBB) is damaged in PD patients, and a large number of infiltrating T cells and inflammatory cytokines have been detected in the cerebrospinal fluid (CSF) and brain parenchyma of PD patients and PD animal models, including significant change in the number and proportion of different CD4+ T cell subsets. This suggests that the neuroinflammatory response caused by CD4+ T cells is an important risk factor for the development of PD. Here, we systematically review the differentiation of CD4+ T cell subsets, and focus on describing the functions and mechanisms of different CD4+ T cell subsets and their secreted cytokines in PD. We also summarize the current immunotherapy targeting CD4+ T cells with a view to providing assistance in the diagnosis and treatment of PD.

Gut microbiota from patients with Parkinson's disease causes motor deficits in honeybees

Objective

Parkinson's disease (PD) is possibly caused by genetic factors, environmental factors, and gut microbiota dysbiosis. This study aims to explore whether the microbiota contributes to the behavior abnormalities of PD.

Methods

We transplanted gut microbiota from patients with PD or healthy controls (HC) into microbiota-free honeybees. We also established two more groups, namely the rotenone (ROT) group, in which PD-like symptoms of honeybees were induced by rotenone, and the conventional (CV) group, in which honeybees were colonized with conventional gut microbiota. The climbing assay was performed to assess the motor capabilities of honeybees. Histopathological examination was conducted to evaluate the integrity of gut mucosa. Tyrosine hydroxylase (TH) gene expression levels and dopamine (DA) concentrations in the brain were also examined. Additionally, metagenomics and full-length 16S rRNA analyses were performed to identify alterations in gut microbiota profiles, both in PD patients and honeybees.

Results

Honeybees in the PD and ROT groups exhibited slower climbing speeds, downregulated TH gene expression, and impaired gut barriers. Both the HC and PD groups of honeybees successfully harbored a portion of gut microbiota from corresponding human donors, and differences in microbial composition were identified. Morganella morganii and Erysipelatoclostridium ramosum exhibited significantly increased relative abundance in the HC group, while Dorea longicatena, Collinsella aerofaciens, Lactococcus garvieae, Holdemanella biformis, Gemmiger formicilis, and Blautia obeum showed significantly increased relative abundance in the PD group. Functional predictions of microbial communities in the PD group indicated an increased synthesis of hydrogen sulfide and methane.

Conclusion

A novel PD model was induced in honeybees with rotenone and gut microbiota from PD patients. This study linked PD-related behaviors to altered gut microbiota, highlighting a potential gut microbiota-brain axis involvement in PD pathogenesis. We identify previously unrecognized associations of Dorea longicatena, Collinsella aerofaciens, Lactococcus garvieae, Holdemanella biformis, Gemmiger formicilis, and Blautia obeum with PD. Additionally, pathways related to hydrogen sulfide and methane synthesis have been previously suggested as potential contributors to the development of PD, and our research further supports this hypothesis.

Unveiling the Journey from the Gut to the Brain: Decoding Neurodegeneration-Gut Connection in Parkinson's Disease

Parkinson's disease, a classical motor disorder affecting the dopaminergic system of the brain, has been as a disease of the brain, but this classical notion has now been viewed differently as the pathology begins in the gut and then gradually moves up to the brain regions. The microorganisms in the gut play a critical role in maintaining the physiology of the gut from maintaining barrier integrity to secretion of microbial products that maintain a healthy gut state. The pathology subsequently alters the normal composition of gut microbes and causes deleterious effects that ultimately trigger strong neuroinflammation and nonmotor symptoms along with characteristic synucleopathy, a pathological hallmark of the disease. Understanding the complex pathomechanisms in distinct and established preclinical models is the primary goal of researchers to decipher how exactly gut pathology has a central effect; the quest has led to many answered and some open-ended questions for researchers. We summarize the popular opinions and some contrasting views, concise footsteps in the treatment strategies targeting the gastrointestinal system.

Global biomarker trends in Parkinson's disease research: A bibliometric analysis

As the second most common neurodegenerative disease globally, Parkinson's disease (PD) affects millions of people worldwide. In recent years, the scientific publications related to PD biomarker research have exploded, reflecting the growing interest in unraveling the complex pathophysiology of PD. In this study, we aim to use various bibliometric tools to identify key scientific concepts, detect emerging trends, and analyze the global trends and development of PD biomarker research.The research encompasses various stages of biomarker development, including exploration, identification, and multi-modal research. MOVEMENT DISORDERS emerged as the leading journal in terms of publications and citations. Key authors such as Mollenhauer and Salem were identified, while the University of Pennsylvania and USA stood out in collaboration and research output. NEUROSCIENCES emerged as the most important research direction. Key biomarker categories include α-synuclein-related markers, neurotransmitter-related markers, inflammation and immune system-related markers, oxidative stress and mitochondrial function-related markers, and brain imaging-related markers. Furthermore, future trends in PD biomarker research focus on exosomes and plasma biomarkers, miRNA, cerebrospinal fluid biomarkers, machine learning applications, and animal models of PD. These trends contribute to early diagnosis, disease progression monitoring, and understanding the pathological mechanisms of PD.

Global biomarker trends in Parkinson's disease research: A bibliometric analysis

As the second most common neurodegenerative disease globally, Parkinson's disease (PD) affects millions of people worldwide. In recent years, the scientific publications related to PD biomarker research have exploded, reflecting the growing interest in unraveling the complex pathophysiology of PD. In this study, we aim to use various bibliometric tools to identify key scientific concepts, detect emerging trends, and analyze the global trends and development of PD biomarker research.The research encompasses various stages of biomarker development, including exploration, identification, and multi-modal research. MOVEMENT DISORDERS emerged as the leading journal in terms of publications and citations. Key authors such as Mollenhauer and Salem were identified, while the University of Pennsylvania and USA stood out in collaboration and research output. NEUROSCIENCES emerged as the most important research direction. Key biomarker categories include α-synuclein-related markers, neurotransmitter-related markers, inflammation and immune system-related markers, oxidative stress and mitochondrial function-related markers, and brain imaging-related markers. Furthermore, future trends in PD biomarker research focus on exosomes and plasma biomarkers, miRNA, cerebrospinal fluid biomarkers, machine learning applications, and animal models of PD. These trends contribute to early diagnosis, disease progression monitoring, and understanding the pathological mechanisms of PD.

Psychobiotics and the Microbiota-Gut-Brain Axis: Where Do We Go from Here?

The bidirectional relationship between the gut microbiota and the nervous system is known as the microbiota-gut-brain axis (MGBA). The MGBA controls the complex interactions between the brain, the enteric nervous system, the gut-associated immune system, and the enteric neuroendocrine systems, regulating key physiological functions such as the immune response, sleep, emotions and mood, food intake, and intestinal functions. Psychobiotics are considered tools with the potential to modulate the MGBA through preventive, adjunctive, or curative approaches, but their specific mechanisms of action on many aspects of health are yet to be characterized. This narrative review and perspectives article highlights the key paradigms needing attention as the scope of potential probiotics applications in human health increases, with a growing body of evidence supporting their systemic beneficial effects. However, there are many limitations to overcome before establishing the extent to which we can incorporate probiotics in the management of neuropsychiatric disorders. Although this article uses the term probiotics in a general manner, it remains important to study probiotics at the strain level in most cases.

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.

[Resveratrol protects dopaminergic neurons in a mouse model of Parkinson's disease by regulating the gut-brain axis via inhibiting the TLR4 signaling pathway]

OBJECTIVE

To investigate the protective effect of resveratrol on intestinal barrier in 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced Parkinson's disease (PD) mouse models and its mechanism for regulating TLR4/MyD88/NF-κB signaling to protect dopaminergic neurons.

METHODS

Fifty-two C57BL/6J mice were randomized into control group (n= 12), MPTP group (n=14), MPTP + resveratrol (30 mg/kg) group (n=13), and MPTP + resveratrol (90 mg/kg) group (n=13), and mouse models were established by intraperitoneal MPTP (30 mg/kg) injection for 7 days in the latter 3 groups. Behavioral tests were conducted to evaluate the effect of resveratrol on motor symptoms of the mice. Western blotting was used to detect the expression of TH, α-syn, ZO-1, Claudin-1, TLR4, MyD88, and NF-κB in the brain tissues of the mice. Immunohistochemistry, immunofluorescence, ELISA and transmission electron microscopy were used to verify the effect of resveratrol for suppressing inflammation and protecting the intestinal barrier.

RESULTS

Compared with those in the normal control group, the mice in MPTP group showed significant changes in motor function, number of dopaminergic neurons, neuroinflammation, levels of LPS and LBP, and expressions of tight junction proteins in the intestinal barrier. Resveratrol treatment significantly improved motor function of the PD mice (P < 0.01), increased the number of neurons and TH protein expression (P < 0.05), down-regulated the expressions of GFAP, Iba-1, and TLR4, lowered fecal and plasma levels of LPS and LBP (P < 0.05), restored the expression levels of ZO-1 and Claudin-1 (P < 0.01), and down-regulated the expressions of TLR4, MyD88, and NF-κB in the colon tissue (P < 0.05). The mice with resveratrol treatment at 30 mg/kg showed normal morphology of the tight junction complex with neatly and tightly arranged intestinal villi.

CONCLUSION

Resveratrol repairs the intestinal barrier by inhibiting TLR4/MyD88/NF-κB signaling pathway-mediated inflammatory response, thereby improving motor function and neuropathy in mouse models of MPTP-induced PD.

[Relationships between microbiome and neurodegeneration]

BACKGROUND

Neurodegenerative diseases are often associated with changes in the (gut) microbiome.

OBJECTIVE

Based on studies in Parkinson's disease (PD) and Alzheimer's disease (AD), an overview of the current evidence of microbial changes and their possible role in the development of these diseases is given.

METHODS

Analysis, summary, and evaluation of the current literature on (gut) microbiome and neurodegeneration.

RESULTS

Numerous studies have shown dysbiotic changes in the gut microbiome of PD and AD patients compared to healthy individuals, some of which might occur even in the prodromal phase. Specifically, these patients show a reduction in bacteria involved in the synthesis of short-chain fatty acids. These microbial alterations have been associated with systemic inflammation and a compromised integrity of the intestinal barrier and blood-brain barrier. Bacterial molecules such as lipopolysaccharides may play an important role in these changes. Additionally, the bacterial protein curli, found on the surface of e.g., Escherichia coli, has been shown in vitro and in animal models to promote the misfolding of α-synuclein, thus suggesting a crucial pathomechanism. Moreover, certain oral bacteria appear to be more prevalent in AD patients and may contribute to the pathogenesis of AD.

CONCLUSION

Neurodegenerative diseases are associated with dysbiosis of the (gut) microbiome, which can have diverse systemic effects; however, it remains unclear whether this dysbiosis is a cause or a consequence of the diseases. Further investigation of this (prodromal) microbial imbalance could reveal new approaches for targeted therapeutic manipulation of the microbiome to modify and prevent these diseases.

Neurodegenerative and Neurodevelopmental Diseases and the Gut-Brain Axis: The Potential of Therapeutic Targeting of the Microbiome

The human gut microbiome contains the largest number of bacteria in the body and has the potential to greatly influence metabolism, not only locally but also systemically. There is an established link between a healthy, balanced, and diverse microbiome and overall health. When the gut microbiome becomes unbalanced (dysbiosis) through dietary changes, medication use, lifestyle choices, environmental factors, and ageing, this has a profound effect on our health and is linked to many diseases, including lifestyle diseases, metabolic diseases, inflammatory diseases, and neurological diseases. While this link in humans is largely an association of dysbiosis with disease, in animal models, a causative link can be demonstrated. The link between the gut and the brain is particularly important in maintaining brain health, with a strong association between dysbiosis in the gut and neurodegenerative and neurodevelopmental diseases. This link suggests not only that the gut microbiota composition can be used to make an early diagnosis of neurodegenerative and neurodevelopmental diseases but also that modifying the gut microbiome to influence the microbiome-gut-brain axis might present a therapeutic target for diseases that have proved intractable, with the aim of altering the trajectory of neurodegenerative and neurodevelopmental diseases such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, autism spectrum disorder, and attention-deficit hyperactivity disorder, among others. There is also a microbiome-gut-brain link to other potentially reversible neurological diseases, such as migraine, post-operative cognitive dysfunction, and long COVID, which might be considered models of therapy for neurodegenerative disease. The role of traditional methods in altering the microbiome, as well as newer, more novel treatments such as faecal microbiome transplants and photobiomodulation, are discussed.

The Impact of Nutrition, Physical Activity, Beneficial Microbes, and Fecal Microbiota Transplant for Improving Health

The recognition that microbes are integral to human life has led to studies on how to manipulate them in favor of health outcomes. To date, there has been no conjoint recommendation for the intake of dietary compounds that can complement the ingested organisms in terms of promoting an improved health outcome. The aim of this review is to discuss how beneficial microbes in the form of probiotics, fermented foods, and donor feces are being used to manage health. In addition, we explore the rationale for selecting beneficial microbial strains and aligning diets to accommodate their propagation in the gut. A pilot clinical trial design is presented to examine the effects of probiotics and exercise in patients with phenylketonuria (PKU); it is the most common inborn error of amino acid metabolism, and it is a complication that requires lifelong dietary intervention. The example design is provided to illustrate the importance of using omics technology to see if the intervention elevates neuroactive biogenic amines in the plasma; increases the abundance of Eubacterium rectale, Coprococcus eutactus, Akkermansia muciniphila, or Butyricicoccus; and increases Escherichia/Shigella in the gut, all as markers of improved health. By emphasizing the combined importance of diet, microbial supplements, and the gut microbiome, we hope that future studies will better align these components, not only to improve outcomes, but also to enhance our understanding of the mechanisms.

Probiotic Influences on Motor Skills: A Review

The effects of probiotics have mostly been shown to be favorable on measures of anxiety and stress. More recent experiments indicate single- and multi-strain probiotics in treating motorrelated diseases. Initial studies in patients with Parkinson's disease and Prader-Willi syndrome are concordant with this hypothesis. In addition, probiotics improved motor coordination in normal animals and models of Parkinson's disease, multiple sclerosis, and spinal cord injury as well as grip strength in hepatic encephalopathy. Further studies should delineate the most optimal bacterial profile under each condition.

The Interplay between Gut Microbiota and Parkinson's Disease: Implications on Diagnosis and Treatment

The bidirectional interaction between the gut microbiota (GM) and the Central Nervous System, the so-called gut microbiota brain axis (GMBA), deeply affects brain function and has an important impact on the development of neurodegenerative diseases. In Parkinson’s disease (PD), gastrointestinal symptoms often precede the onset of motor and non-motor manifestations, and alterations in the GM composition accompany disease pathogenesis. Several studies have been conducted to unravel the role of dysbiosis and intestinal permeability in PD onset and progression, but the therapeutic and diagnostic applications of GM modifying approaches remain to be fully elucidated. After a brief introduction on the involvement of GMBA in the disease, we present evidence for GM alterations and leaky gut in PD patients. According to these data, we then review the potential of GM-based signatures to serve as disease biomarkers and we highlight the emerging role of probiotics, prebiotics, antibiotics, dietary interventions, and fecal microbiota transplantation as supportive therapeutic approaches in PD. Finally, we analyze the mutual influence between commonly prescribed PD medications and gut-microbiota, and we offer insights on the involvement also of nasal and oral microbiota in PD pathology, thus providing a comprehensive and up-to-date overview on the role of microbial features in disease diagnosis and treatment.

Gut Microbiota: A Novel Therapeutic Target for Parkinson’s Disease

Parkinson’s disease (PD) is the second most common neurodegenerative disease characterized by motor dysfunction. Growing evidence has demonstrated that gut dysbiosis is involved in the occurrence, development and progression of PD. Numerous clinical trials have identified the characteristics of the changed gut microbiota profiles, and preclinical studies in PD animal models have indicated that gut dysbiosis can influence the progression and onset of PD via increasing intestinal permeability, aggravating neuroinflammation, aggregating abnormal levels of α-synuclein fibrils, increasing oxidative stress, and decreasing neurotransmitter production. The gut microbiota can be considered promising diagnostic and therapeutic targets for PD, which can be regulated by probiotics, psychobiotics, prebiotics, synbiotics, postbiotics, fecal microbiota transplantation, diet modifications, and Chinese medicine. This review summarizes the recent studies in PD-associated gut microbiota profiles and functions, the potential roles, and mechanisms of gut microbiota in PD, and gut microbiota-targeted interventions for PD. Deciphering the underlying roles and mechanisms of the PD-associated gut microbiota will help interpret the pathogenesis of PD from new perspectives and elucidate novel therapeutic strategies for PD.