-
Movement Disorders : Official Journal... Sep 2023Parkinson's disease (PD) biomarkers are needed by both clinicians and researchers (for diagnosis, identifying study populations, and monitoring therapeutic response).... (Meta-Analysis)
Meta-Analysis Review
Parkinson's disease (PD) biomarkers are needed by both clinicians and researchers (for diagnosis, identifying study populations, and monitoring therapeutic response). Imaging, genetic, and biochemical biomarkers have been widely studied. In recent years, extracellular vesicles (EVs) have become a promising material for biomarker development. Proteins and molecular material from any organ, including the central nervous system, can be packed into EVs and transported to the periphery into easily obtainable biological specimens like blood, urine, and saliva. We performed a systematic review and meta-analysis of articles (published before November 15, 2022) reporting biomarker assessment in EVs in PD patients and healthy controls (HCs). Biomarkers were analyzed using random effects meta-analysis and the calculated standardized mean difference (Std.MD). Several proteins and ribonucleic acids have been identified in EVs in PD patients, but only α-synuclein (aSyn) and leucine-rich repeat kinase 2 (LRRK2) were reported in sufficient studies (n = 24 and 6, respectively) to perform a meta-analysis. EV aSyn was significantly increased in neuronal L1 cell adhesion molecule (L1CAM)-positive blood EVs in PD patients compared to HCs (Std.MD = 1.84, 95% confidence interval = 0.76-2.93, P = 0.0009). Further analysis of the biological sample and EV isolation method indicated that L1CAM-IP (immunoprecipitation) directly from plasma was the best isolation method for assessing aSyn in PD patients. Upcoming neuroprotective clinical trials immediately need peripheral biomarkers for identifying individuals at risk of developing PD. Overall, the improved sensitivity of assays means they can identify biomarkers in blood that reflect changes in the brain. CNS-derived EVs in blood will likely play a major role in biomarker development in the coming years. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
Topics: Humans; alpha-Synuclein; Biomarkers; Extracellular Vesicles; Neural Cell Adhesion Molecule L1; Parkinson Disease
PubMed: 37449706
DOI: 10.1002/mds.29497 -
International Journal of Molecular... Jul 2023There are currently no pharmacological treatments available that completely halt or reverse the progression of Parkinson's Disease (PD). Hence, there is an unmet need... (Review)
Review
There are currently no pharmacological treatments available that completely halt or reverse the progression of Parkinson's Disease (PD). Hence, there is an unmet need for neuroprotective therapies. Lewy bodies are a neuropathological hallmark of PD and contain aggregated α-synuclein (α-syn) which is thought to be neurotoxic and therefore a suitable target for therapeutic interventions. To investigate this further, a systematic review was undertaken to evaluate whether anti-α-syn therapies are effective at preventing PD progression in preclinical in vivo models of PD and via current human clinical trials. An electronic literature search was performed using MEDLINE and EMBASE (Ovid), PubMed, the Web of Science Core Collection, and Cochrane databases to collate clinical evidence that investigated the targeting of α-syn. Novel preclinical anti-α-syn therapeutics provided a significant reduction of α-syn aggregations. Biochemical and immunohistochemical analysis of rodent brain tissue demonstrated that treatments reduced α-syn-associated pathology and rescued dopaminergic neuronal loss. Some of the clinical studies did not provide endpoints since they had not yet been completed or were terminated before completion. Completed clinical trials displayed significant tolerability and efficacy at reducing α-syn in patients with PD with minimal adverse effects. Collectively, this review highlights the capacity of anti-α-syn therapies to reduce the accumulation of α-syn in both preclinical and clinical trials. Hence, there is potential and optimism to target α-syn with further clinical trials to restrict dopaminergic neuronal loss and PD progression and/or provide prophylactic protection to avoid the onset of α-syn-induced PD.
Topics: Humans; alpha-Synuclein; Parkinson Disease; Lewy Bodies; Brain; Disease Progression
PubMed: 37446200
DOI: 10.3390/ijms241311022 -
CNS Neuroscience & Therapeutics Dec 2023Parkinsonian disorders, such as Parkinson's disease (PD), multiple system atrophy (MSA), dementia with Lewy bodies (DLB), progressive supranuclear palsy (PSP) and... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND & AIMS
Parkinsonian disorders, such as Parkinson's disease (PD), multiple system atrophy (MSA), dementia with Lewy bodies (DLB), progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS), share early motor symptoms but have distinct pathophysiology. As a result, accurate premortem diagnosis is challenging for neurologists, hindering efforts for disease-modifying therapeutic discovery. Extracellular vesicles (EVs) contain cell-state-specific biomolecules and can cross the blood-brain barrier to the peripheral circulation, providing a unique central nervous system (CNS) insight. This meta-analysis evaluated blood-isolated neuronal and oligodendroglial EVs (nEVs and oEVs) α-synuclein levels in Parkinsonian disorders.
METHODS
Following PRISMA guidelines, the meta-analysis included 13 studies. An inverse-variance random-effects model quantified effect size (SMD), QUADAS-2 assessed risk of bias and publication bias was evaluated. Demographic and clinical variables were collected for meta-regression.
RESULTS
The meta-analysis included 1,565 patients with PD, 206 with MSA, 21 with DLB, 172 with PSP, 152 with CBS and 967 healthy controls (HCs). Findings suggest that combined concentrations of nEVs and oEVs α-syn is higher in patients with PD compared to HCs (SMD = 0.21, p = 0.021), while nEVs α-syn is lower in patients with PSP and CBS compared to patients with PD (SMD = -1.04, p = 0.0017) or HCs (SMD = -0.41, p < 0.001). Additionally, α-syn in nEVs and/or oEVs did not significantly differ in patients with PD vs. MSA, contradicting the literature. Meta-regressions show that demographic and clinical factors were not significant predictors of nEVs or oEVs α-syn concentrations.
CONCLUSION
The results highlight the need for standardized procedures and independent validations in biomarker studies and the development of improved biomarkers for distinguishing Parkinsonian disorders.
Topics: Humans; alpha-Synuclein; Biomarkers; Central Nervous System; Extracellular Vesicles; Multiple System Atrophy; Parkinson Disease; Parkinsonian Disorders
PubMed: 37416941
DOI: 10.1111/cns.14341 -
Frontiers in Molecular Biosciences 2023Dementia with Lewy Bodies (DLB) is the second most common cause of neurodegenerative dementia after Alzheimer's disease (AD), but the field is still lacking a specific... (Review)
Review
Dementia with Lewy Bodies (DLB) is the second most common cause of neurodegenerative dementia after Alzheimer's disease (AD), but the field is still lacking a specific biomarker for its core pathology: alpha synuclein (α-syn). Realtime quaking induced conversion (RT-QuIC) has recently emerged as a strong biomarker candidate to detect misfolded α-syn in DLB. However, the variability in the parameters of the technique and the heterogeneity of DLB patients make the reproducibility of the results difficult. Here, we provide an overview of the state-of-the-art research of α-syn RT-QuIC in DLB focused on: (1) the capacity of α-syn RT-QuIC to discriminate DLB from controls, Parkinson's disease (PD) and AD; (2) the capacity of α-syn RT-QuIC to identify prodromal stages of DLB; and (3) the influence of co-pathologies on α-syn RT-QuIC's performance. We also assessed the influence of different factors, such as technical conditions (e.g., temperature, pH, shaking-rest cycles), sample type, and clinical diagnosis versus autopsy confirmation. We conducted a systematic review following the PRISMA guidelines in August 2022, without any limits in publication dates. Search terms were combinations of "RT-QuIC" and "Lewy Bodies," "DLB" or "LBD". Our meta-analysis shows that α-syn RT-QuIC reaches very high diagnostic performance in discriminating DLB from both controls (pooled sensitivity and specificity of 0.94 and 0.96, respectively) and AD (pooled sensitivity and specificity of 0.95 and 0.88) and is promising for prodromal phases of DLB. However, the performance of α-syn RT-QuIC to discriminate DLB from PD is currently low due to low specificity (pooled sensitivity and specificity of 0.94 and 0.11). Our analysis showed that α-syn RT-QuIC's performance is not substantially influenced by sample type or clinical diagnosis versus autopsy confirmation. Co-pathologies did not influence the performance of α-syn RT-QuIC, but the number of such studies is currently limited. We observed technical variability across published articles. However, we could not find a clear effect of technical variability on the reported results. There is currently enough evidence to test misfolded α-syn by RT-QuIC for clinical use. We anticipate that harmonization of protocols across centres and advances in standardization will facilitate the clinical establishment of misfolded α-syn detection by RT-QuIC.
PubMed: 37266333
DOI: 10.3389/fmolb.2023.1193458 -
Movement Disorders Clinical Practice May 2023Real-time quaking-induced conversion (RT-QuIC) and protein misfolding cyclic amplification (PMCA) have been developed to detect minute amounts of amyloidogenic proteins... (Review)
Review
BACKGROUND
Real-time quaking-induced conversion (RT-QuIC) and protein misfolding cyclic amplification (PMCA) have been developed to detect minute amounts of amyloidogenic proteins via amplification techniques and have been used to detect misfolded α-synuclein (αSyn) aggregates in the cerebrospinal fluid (CSF) and other source materials of patients with Parkinson's Disease and other synucleinopathies.
OBJECTIVES
The aim of this systematic review and meta-analysis was to evaluate the diagnostic accuracy of αSyn seed amplification assays (αSyn-SAAs), including RT-QuIC and PMCA, using CSF as source material to differentiate synucleinopathies from controls.
METHODS
The electronic MEDLINE database PubMed was searched for relevant articles published until June 30, 2022. Study quality assessment was performed using the QUADAS-2 toolbox. A random effects bivariate model was exploited for data synthesis.
RESULTS
Our systematic review identified 27 eligible studies according to the predefined inclusion criteria, of which 22 were included in the final analysis. Overall, 1855 patients with synucleinopathies and 1378 non-synucleinopathies as control subjects were included in the meta-analysis. The pooled sensitivity and specificity to differentiate synucleinopathies from controls with αSyn-SAA were 0.88 (95% CI, 0.82-0.93) and 0.95 (95% CI, 0.92-0.97), respectively. Evaluating the diagnostic performance of RT-QuIC in a subgroup analysis for the detection of patients with multiple system atrophy the pooled sensitivity decreased to 0.30 (95% CI, 0.11-0.59).
CONCLUSIONS
While our study clearly demonstrated a high diagnostic performance of RT-QuIC and PMCA for differentiating synucleinopathies with Lewy bodies from controls, results for the diagnosis of multiple system atrophy were less robust.
PubMed: 37205253
DOI: 10.1002/mdc3.13710 -
Neurogastroenterology and Motility Aug 2023There is strong support from studies in humans and in animal models that Parkinson's disease (PD) may begin in the gut. This brings about a unique opportunity for... (Review)
Review
BACKGROUND
There is strong support from studies in humans and in animal models that Parkinson's disease (PD) may begin in the gut. This brings about a unique opportunity for researchers in the field of neurogastroenterology to contribute to advancing the field and making contributions that could lead to the ability to diagnose and treat PD in the premotor stages. Lack of familiarity with some of the aspects of the experimental approaches used in these studies may present a barrier for neurogastroenterology researchers to enter the field. Much remains to be understood about intestinal-specific components of gut-first PD pathogenesis and the field would benefit from contributions of enteric and central nervous system neuroscientists.
PURPOSE
To address these issues, we have conducted a systematic review of the two most frequently used experimental models of gut-first PD: transneuronal propagation of α-synuclein preformed fibrils and oral exposure to environmental toxins. We have reviewed the details of these studies and present methodological considerations for the use of these models. Our aim is that this review will serve as a framework and useful reference for neuroscientists, gastroenterologists, and neurologists interested in applying their expertise to advancing our understanding of gut-first PD.
Topics: Animals; Humans; Parkinson Disease; alpha-Synuclein; Central Nervous System; Brain; Models, Theoretical
PubMed: 37125607
DOI: 10.1111/nmo.14604 -
Heliyon Mar 2023The aim of this study was to evaluate the effects of probiotics on the treatment of constipation in patients with Parkinson's disease (PD) by analyzing data from... (Review)
Review
OBJECTIVES
The aim of this study was to evaluate the effects of probiotics on the treatment of constipation in patients with Parkinson's disease (PD) by analyzing data from published randomized clinical trials (RCTs). PD is a neurodegenerative disease characterized by clinical symptoms such as rigidity, bradykinesia, and resting tremor. Constipation is a common complaint reported by PD patients. Probiotics are often used to treat functional constipation. The potential mechanisms behind PD-related constipation include dysfunction of the enteric nervous system due to alpha-synuclein aggregation, dyssynergic contractions of the puborectalis muscle, and alterations of the gut microbiome.
METHOD
To conduct this study, we searched Scopus, PubMed, and Google Scholar for published articles on PD, probiotics, and constipation. We selected RCTs from 944 studies, and ultimately included 3 RCTs in our meta-analysis. The frequency of bowel movements per week was the only index that could be summarized among the records. We extracted and analyzed the results as means and standard deviations.
RESULT
We calculated a standardized mean difference (SMD) of 0.92 (95% CI, 0.65 to 1.19; I-squared = 57.0%; p < 0.001) to determine the treatment effect in terms of frequency of bowel movements per week in the RCTs.
CONCLUSION
Our results show that probiotic intake has beneficial effects on constipation in PD patients. Further research, including multicenter studies, is needed to assess the long-term efficacy and safety of probiotic supplements in neurodegenerative diseases.
PubMed: 36938477
DOI: 10.1016/j.heliyon.2023.e14312 -
Annals of Palliative Medicine Dec 2022There is no consensus on the efficacy of using α-synuclein as the primary immunotherapy site for Parkinson's disease (PD). The present study sought to investigate the... (Meta-Analysis)
Meta-Analysis
BACKGROUND
There is no consensus on the efficacy of using α-synuclein as the primary immunotherapy site for Parkinson's disease (PD). The present study sought to investigate the safety and effectiveness of α-synuclein immunotherapy for treating PD.
METHODS
The databases of CNKI, CBM, Cochrane Library, PubMed, Web of Science, and Embase were searched for randomized controlled trials (RCTs). Cochrane Collaboration's bias assessment tool was used to assess the risk of bias in the included articles, and the included PD patients older than 18 years adopted immunotherapy. Stata 15.0 was employed for statistical analysis.
RESULTS
A total of 6 RCTs were eligible for the present study, involving 606 immunotherapy recipients (using alpha-synuclein immunotherapy) and 254 control individuals (placebo). Our meta-analysis found no statistical difference in the Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) total score [weighted mean difference (WMD): -0.72, 95% confidence interval (CI): -1.56 to 0.13, P=0.099], adverse event incidence [relative risk (RR): 1.06, 95% CI: 0.98 to 1.15, P=0.150], headache incidence (RR: 0.95, 95% CI: 0.67 to 1.34, P=0.773), and constipation incidence (RR: 1.47, 95% CI: 0.77 to 2.78, P=0.242). However, the infection rate in the immunotherapy group was higher than in the control group (RR: 2.29, 95% CI: 1.40 to 3.74, P=0.003). The above results indicate that immunotherapy is significantly different from placebo in MDS-UPDRS and adverse event incidence, but it can reduce the incidence of infection rate.
CONCLUSIONS
Existing results showed that α-synuclein immunotherapy had no significant effect on PD. high-quality, multi-center, and large-scale clinical studies are desired to corroborate our findings.
Topics: Humans; Parkinson Disease; alpha-Synuclein; Immunotherapy
PubMed: 36636001
DOI: 10.21037/apm-22-1356 -
Sleep Medicine Jan 2023The glymphatic system is thought to be responsible for waste clearance in the brain. As it is primarily active during sleep, different components of sleep, subjective... (Review)
Review
OBJECTIVE
The glymphatic system is thought to be responsible for waste clearance in the brain. As it is primarily active during sleep, different components of sleep, subjective sleep quality, and sleep patterns may contribute to glymphatic functioning. This systematic review aimed at exploring the effect of sleep components, sleep quality, and sleep patterns on outcomes associated with the glymphatic system in healthy adults.
METHODS
PubMed®, Scopus, and Web of Science were searched for studies published in English until December 2021. Articles subjectively or objectively investigating sleep components (total sleep time, time in bed, sleep efficiency, sleep onset latency, wake-up after sleep onset, sleep stage, awakenings), sleep quality, or sleep pattern in healthy individuals, on outcomes associated with glymphatic system (levels of amyloid-β, tau, α-synuclein; cerebrospinal fluid, perivascular spaces; apolipoprotein E) were selected.
RESULTS
Out of 8359 records screened, 51 studies were included. Overall, contradictory findings were observed according to different sleep assessment method. The most frequently assessed sleep parameters were total sleep time, sleep quality, and sleep efficiency. No association was found between sleep efficiency and amyloid-β, and between slow-wave activity and tau. Most of the studies did not find any correlation between total sleep time and amyloid-β nor tau level. Opposing results correlated sleep quality with amyloid-β and tau.
CONCLUSIONS
This review highlighted inconsistent results across the studies; as such, the specific association between the glymphatic system and sleep parameters in healthy adults remains poorly understood. Due to the heterogeneity of sleep assessment methods and the self-reported data representing the majority of the observations, future studies with universal study design and sleep methodology in healthy individuals are advocated.
Topics: Adult; Humans; Amyloid beta-Peptides; Brain; Glymphatic System; Sleep; Sleep Wake Disorders
PubMed: 36481512
DOI: 10.1016/j.sleep.2022.11.012 -
Cureus Oct 2022Neurodegenerative diseases, in particular Parkinson's disease (PD), a disabling disorder, require early attention due to the course the diseases take. By the time of... (Review)
Review
Neurodegenerative diseases, in particular Parkinson's disease (PD), a disabling disorder, require early attention due to the course the diseases take. By the time of clinical manifestation, dopaminergic neuron death would have already exceeded a damaging level. Therefore, the discovery of biomarkers that will effectively diagnose PD at an early stage and help monitor disease advancement is crucial. Out of the available biomarkers and bodily sources from which these can be isolated; alpha-synuclein (a-syn) from saliva seems to be a promising and easily accessible option. This has been further investigated in this systematic review. A comprehensive literature search on PubMed, PubMed Central (PMC), and Science Direct resulted in 1,439 articles. After screening and exclusion, 12 relevant articles were derived. In many of the studies, there was a decrease in total salivary a-syn in PD patients compared to healthy controls (HC), with an increase in oligo a-syn and oligo a-syn/total a-syn ratio as a rather consistent finding amongst the studies reviewed. On the other hand, a few studies revealed no significant difference in a-syn levels between the controls and PD patients. Another common finding was the lack of disease severity correlation with the marker, probably due to the scarcity of longitudinal studies conducted and smaller cohorts recruited in the studies. Overall, the total a-syn did show a genetic and phenotypic association, whilst oligo a-syn had the potential to serve as a biomarker for disease diagnosis. With the standardization of sample collection methods and diagnostic tools, and the accomplishment of longitudinal studies, further importance of salivary a-syn as a biomarker in PD could be established, utilizing the already existing data as an encouraging foundation for future research.
PubMed: 36348879
DOI: 10.7759/cureus.29880