Protein Deimination Signatures in Plasma and Plasma-EVs and Protein Deimination in the Brain Vasculature in a Rat Model of Pre-Motor Parkinson's Disease

The identification of biomarkers for early diagnosis of Parkinson’s disease (PD) is of pivotal importance for improving approaches for clinical intervention. The use of translatable animal models of pre-motor PD therefore offers optimal opportunities for novel biomarker discovery in vivo. Peptidylarginine deiminases (PADs) are a family of calcium-activated enzymes that contribute to protein misfolding through post-translational deimination of arginine to citrulline. Furthermore, PADs are an active regulator of extracellular vesicle (EV) release. Both protein deimination and extracellular vesicles (EVs) are gaining increased attention in relation to neurodegenerative diseases, including in PD, while roles in pre-motor PD have yet to be investigated. The current study aimed at identifying protein candidates of deimination in plasma and plasma-EVs in a rat model of pre-motor PD, to assess putative contributions of such post-translational changes in the early stages of disease. EV-cargo was further assessed for deiminated proteins as well as three key micro-RNAs known to contribute to inflammation and hypoxia (miR21, miR155, and miR210) and also associated with PD. Overall, there was a significant increase in circulating plasma EVs in the PD model compared with sham animals and inflammatory and hypoxia related microRNAs were significantly increased in plasma-EVs of the pre-motor PD model. A significantly higher number of protein candidates were deiminated in the pre-motor PD model plasma and plasma-EVs, compared with those in the sham animals. KEGG (Kyoto encyclopedia of genes and genomes) pathways identified for deiminated proteins in the pre-motor PD model were linked to “Alzheimer’s disease”, “PD”, “Huntington’s disease”, “prion diseases”, as well as for “oxidative phosphorylation”, “thermogenesis”, “metabolic pathways”, “Staphylococcus aureus infection”, gap junction, “platelet activation”, “apelin signalling”, “retrograde endocannabinoid signalling”, “systemic lupus erythematosus”, and “non-alcoholic fatty liver disease”. Furthermore, PD brains showed significantly increased staining for total deiminated proteins in the brain vasculature in cortex and hippocampus, as well as increased immunodetection of deiminated histone H3 in dentate gyrus and cortex. Our findings identify EVs and post-translational protein deimination as novel biomarkers in early pre-motor stages of PD.

Plasma Cytokines Profile in Patients with Parkinson's Disease Associated with Mutations in GBA Gene

Plasma cytokine concentration in patients with Parkinson's disease and mutation in GBA gene, in patients with sporadic Parkinson's disease, and in healthy volunteers were measured by ELISA and multiplex analysis. In patients with Parkinson's disease and mutation in GBA gene, elevated plasma concentrations of IL-1β and TNFα were revealed by ELISA in comparison with both controls and patients with sporadic form of Parkinson's disease. Multiplex analysis revealed enhanced secretion of IL-1β, IL-2, IFNγ and reduced plasma levels of monocyte chemoattractant protein-1 (MCP-1) in patients with Parkinson's disease and mutation in GBA gene (in comparison with other groups) and increased plasma levels of IL-13 (only in comparison with the healthy volunteers). Our results support the hypothesis that the concentrations of inflammatory mediators are increased in patients with Parkinson's disease and mutation in GBA gene.

Assessment of vitamin D and inflammatory markers profile in cardiac tissue on Parkinson disease animal model

BACKGROUND

Cardiovascular dysfunctions are common non-motor symptoms in patients with Parkinson's disease (PD) that can result in reduced quality of life and even death. Research in animal models designed to characterize the pathological association between PD and cardiovascular abnormalities is still in its infancy. This study assessed the early impact of the nigrostriatal dopaminergic damage on cardiological features in the unilateral 6-OHDA rat model of PD.

METHODS

Male Wistar rats received unilateral intrastriatal injections of 6-OHDA and sham rats were injected with saline. Animals were studied 15 days later. Immunohistochemistry was used for visualization of tyrosine hydroxylase (TH)-positive neurons in the nigrostriatal system. Electrocardiogram recordings of heart rate were performed in conscious rats. Heart levels of vitamin D, inflammatory cytokines and C-reactive protein were assessed through electrochemiluminescence immunoassay, quantitative reverse transcription PCR and turbidimetric method, respectively.

RESULTS

We found a post-injury reduction of TH-immunoreactivity of approximately 45% in the substantia nigra pars compacta and 20% in the striatum. Heart rate reduction was found in 6-OHDA-lesioned rats as compared with sham counterparts. Reduced levels of vitamin D and increased levels of inflammatory factors (C-reactive protein, IL-6, TNF-α and TGF-β) were detected in the heart tissue of PD rats in comparison with sham.

CONCLUSION

Our findings suggest a link between cardiac tissue changes and cardiac functional changes early after the central dopaminergic damage induced by 6-OHDA. Knowledge of the cardiac abnormalities in the 6-OHDA model is critical in identifying future therapeutic targets and disease-modifying approaches for PD non-motor features.

Soluble TREM2 is elevated in Parkinson's disease subgroups with increased CSF tau

Parkinson's disease is the second most common neurodegenerative disease after Alzheimer's disease and affects 1% of the population above 60 years old. Although Parkinson's disease commonly manifests with motor symptoms, a majority of patients with Parkinson's disease subsequently develop cognitive impairment, which often progresses to dementia, a major cause of morbidity and disability. Parkinson's disease is characterized by α-synuclein accumulation that frequently associates with amyloid-β and tau fibrils, the hallmarks of Alzheimer's disease neuropathological changes; this co-occurrence suggests that onset of cognitive decline in Parkinson's disease may be associated with appearance of pathological amyloid-β and/or tau. Recent studies have highlighted the appearance of the soluble form of the triggering receptor expressed on myeloid cells 2 (sTREM2) receptor in CSF during development of Alzheimer's disease. Given the known association of microglial activation with advancing Parkinson's disease, we investigated whether CSF and/or plasma sTREM2 differed between CSF biomarker-defined Parkinson's disease participant subgroups. In this cross-sectional study, we examined 165 participants consisting of 17 cognitively normal elderly subjects, 45 patients with Parkinson's disease with no cognitive impairment, 86 with mild cognitive impairment, and 17 with dementia. Stratification of subjects by CSF amyloid-β and tau levels revealed that CSF sTREM2 concentrations were elevated in Parkinson's disease subgroups with a positive tau CSF biomarker signature, but not in Parkinson's disease subgroups with a positive CSF amyloid-β biomarker signature. These findings indicate that CSF sTREM2 could serve as a surrogate immune biomarker of neuronal injury in Parkinson's disease.

Increased plasma phosphatidylcholine/lysophosphatidylcholine ratios in patients with Parkinson's disease

RATIONALE

Changes in lipid composition might be associated with the onset and progression of various neurodegenerative diseases. Herein, we investigated the changes in the plasma phosphatidylcholine (PC)/lysophosphatidylcholine (LPC) ratios in patients with Parkinson's disease (PD) in comparison with healthy subjects and their correlation with clinico-pathological features.

METHODS

The study included 10 controls and 25 patients with PD. All patients were assigned to groups based on clinico-pathological characteristics (gender, age at examination, duration of disease and Hoehn and Yahr (H&Y) stage). The analysis of the PC/LPC intensity ratios in plasma lipid extracts was performed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

RESULTS

PD patients exhibited an increased PC/LPC intensity ratio in comparison with the control group of healthy subjects. Furthermore, the investigated ratio was shown to be correlated with clinico-pathological parameters, in particular with H&Y stage and disease duration. The PC/LPC intensity ratio in plasma samples of PD patients was found to be elevated in all examined H&Y stages and throughout the disease duration.

CONCLUSIONS

To our knowledge, this is the first study examining the PC/LPC ratios in plasma of patients with PD and illustrating their correlation with clinico-pathological features. Although the presented results may be considered as preliminary due to the limited number of participants, the observed alterations of PC/LPC ratios in plasma might be a first step in the characterization of plasma lipid changes in PD patients and an indicator of lipid reconfiguration.

Efficacy of oral administration of licorice as an adjunct therapy on improving the symptoms of patients with Parkinson's disease, A randomized double blinded clinical trial

ETHNOPHARMACOLOGICAL RELEVANCE

Licorice preparations are used as neuroprotective remedies in Persian ethnomedicine, in order to prevent from disabilities in neurodegenerative conditions like Parkinson's disease (PD).

AIM OF THE STUDY

This study was designed to determine the licorice (root of Glycyrrhiza glabra L.) effectiveness as an adjunct treatment in the PD management.

MATERIAL AND METHODS

In this double-blinded trial, 128 patients were assessed for eligibility criteria. Seventy-eight patients were ineligible and 11 of them refused from participating. Thirty-nine PD patients (YAHR staging ≤ 3) were divided into two groups by random. The patients received oral licorice or placebo syrups with a dose of 5 cc, twice a day for 6 months. High-performance liquid chromatography and spectrophotometric instruments determined licorice syrup constituents. The patients' situation for Unified Parkinson's rating scale (UPDRS) was assessed every 6 weeks for the duration of six months. In addition, patients' blood pressure, blood glucose, sodium and potassium levels, quality of life and dizziness were determined.

RESULTS

Six weeks after intervention, total UPDRS, daily activities and tremor were significantly improved with a considerable effect size. A significant better motor test and rigidity scores were observed 4 months after licorice intake (p > 0.05). No electrolyte abnormality, significant changes in blood pressure or blood glucose levels were observed during the study. Each 5cc of syrup contained 136 mg of licorice extract with 12.14 mg glycyrrhizic acid, and also 136 μg of polyphenols.

CONCLUSION

The licorice intake could improve the symptoms in PD patients without serious adverse events.

Alteration of brain temperature and systemic inflammation in Parkinson's disease

Objectives

Parkinson’s disease (PD) is known to be related to various factors, including neuroinflammation, increased oxidative stress, and brain temperature alteration. We aimed to evaluate the correlation between these factors using diffusion-weighted imaging (DWI) thermometry and blood tests of systemic inflammation.

Methods

From July 2012 to Jun 2017, 103 patients with PD (44 men and 59 women; mean age, 60.43 ± 9.12 years) and 106 sex- and age-matched healthy volunteers (48 men and 58 women; mean age, 58.16 ± 8.45 years) retrospectively underwent magnetic resonance DWI thermometry to estimate brain intraventricular temperature (T_v). Subjects were divided into three subgroups in light of their ages. The tested inflammatory markers included plasma nuclear DNA, mitochondrial DNA, apoptotic leukocytes, and serum adhesion molecules. The correlations among the T_v values, clinical severity, and systemic inflammatory markers were then calculated.

Results

The PD patients did not show a natural trend of decline in T_v with age. Comparisons among the different age groups revealed that the younger PD subjects had significantly lower T_v values than the younger controls, but the older subjects had no significant group differences. Overall, the PD patients exhibited lower T_v values than the controls, as well as increased oxidative stress. The brain temperature showed positive correlations with inflammatory markers, including plasma nuclear DNA and L-selectin levels, in all the subjects.

Conclusions

Possible pathophysiological correlations between systemic inflammation and brain temperature were indicated by the results of this study, a finding which may aid us in investigating the underlying pathogenesis of PD.

Electronic supplementary material

The online version of this article (10.1007/s10072-019-04217-3) contains supplementary material, which is available to authorized users.

SEAweb: the small RNA Expression Atlas web application

We present the Small RNA Expression Atlas (SEAweb), a web application that allows for the interactive querying, visualization and analysis of known and novel small RNAs across 10 organisms. It contains sRNA and pathogen expression information for over 4200 published samples with standardized search terms and ontologies. In addition, SEAweb allows for the interactive visualization and re-analysis of 879 differential expression and 514 classification comparisons. SEAweb's user model enables sRNA researchers to compare and re-analyze user-specific and published datasets, highlighting common and distinct sRNA expression patterns. We provide evidence for SEAweb's fidelity by (i) generating a set of 591 tissue specific miRNAs across 29 tissues, (ii) finding known and novel bacterial and viral infections across diseases and (iii) determining a Parkinson's disease-specific blood biomarker signature using novel data. We believe that SEAweb's simple semantic search interface, the flexible interactive reports and the user model with rich analysis capabilities will enable researchers to better understand the potential function and diagnostic value of sRNAs or pathogens across tissues, diseases and organisms.

An Assessment of LRRK2 Serine 935 Phosphorylation in Human Peripheral Blood Mononuclear Cells in Idiopathic Parkinson's Disease and G2019S LRRK2 Cohorts

The phosphorylated form of LRRK2, pS935 LRRK2, has been proposed as a target modulation biomarker for LRRK2 inhibitors. The primary aim of the study was to characterize and qualify this biomarker for therapeutic trials of LRRK2 inhibitors in Parkinson's disease (PD). To this end, analytically validated assays were used to monitor levels of pS935 LRRK2 and total LRRK2 in peripheral blood mononuclear cells (PBMCs) from the following donor groups: healthy controls, idiopathic PD, and G2019S carriers with and without PD. Neither analyte correlated with age, gender, or disease severity. While total LRRK2 levels were similar across the four groups, there was a significant reduction in pS935 LRRK2 levels in disease-manifesting G2019S carriers compared to idiopathic PD. In aggregate, these data indicate that phosphorylation of LRRK2 at S935 may reflect a state marker for G2019S LRRK2-driven PD, the underlying biology for which requires investigation in future studies. This study also provides critical foundational data to inform the integration of pS935 and total LRRK2 levels as biomarkers in therapeutic trials of LRRK2 kinase inhibitors.

α-Synuclein in blood cells differentiates Parkinson's disease from healthy controls

OBJECTIVE

To determine whether blood cells expressed α-Syn can differentiate Parkinson's disease (PD) from healthy controls (HC).

METHODS

The concentrations of α-Syn were determined in samples of blood cell pellets using a quantitative Lipid-ELISA assay. In addition, the levels of total protein, hemoglobin, iron and H-ferritin were determined. The study includes samples from the Biofind cohort (n = 46 PD and 45 HC) and results were validated with an additional cohort (n = 35 PD and 28 HC).

RESULTS

A composite biomarker consisting of the concentrations of total α-Syn, proteinase-K resistant (PKres ) α-Syn and phospho-Serine 129 α-Syn (PSer 129), is designed based on the analysis of the discovery BioFIND cohort. This composite biomarker differentiates a PD subgroup, presenting motor symptoms without dementia from a HC group, with a convincing accuracy, represented by an AUC = 0.81 (95% CI, 0.71 to 0.92). Closely similar results were obtained for the validation cohort, that is, AUC = 0.81, (95% CI, 0.70 to 0.94).

INTERPRETATION

Our results demonstrate the potential usefulness of blood cells expressed α-Syn as a biomarker for PD.

Peripheral immune biomarkers and neurodegenerative diseases: A prospective cohort study with 20 years of follow-up

OBJECTIVE

To assess the associations of several blood immune biomarkers with the future risks of amyotrophic lateral sclerosis and Parkinson disease in a prospective cohort study with 20 years of follow-up.

METHODS

The Swedish Apolipoprotein-Related Mortality Risk study is a longitudinal cohort study including 812,073 participants with repeated blood biomarker measurements between 1985 and 1996 and a follow-up until 2011. Using a Cox model, we first estimated hazard ratios of amyotrophic lateral sclerosis and Parkinson disease in relation to leukocytes, immunoglobulin G, haptoglobin, and uric acid. We further described the temporal changes of these biomarkers during the 20 years prior to the diagnosis of these diseases.

RESULTS

A total of 585 incident cases of amyotrophic lateral sclerosis and 3,769 incident cases of Parkinson disease were identified during the follow-up. Increasing concentrations of leukocytes, haptoglobin, and uric acid were associated with a lower risk of Parkinson disease. No statistically significant association was, however, noted between the studied biomarkers and amyotrophic lateral sclerosis. Parkinson disease patients appeared to have lower levels of leukocytes and haptoglobin between 20 and 10 years before diagnosis and lower levels of uric acid during the 20 years before diagnosis, compared to controls, although statistically significant differences were only noted during parts of the respective time intervals after multivariable adjustment. No clear differences were noted between patients with amyotrophic lateral sclerosis and controls.

INTERPRETATION

If verified in studies of independent populations, our findings may suggest a different role of systemic inflammation on the risk of Parkinson disease compared to amyotrophic lateral sclerosis. ANN NEUROL 2019;86:913-926.

Specific Signatures of Serum miRNAs as Potential Biomarkers to Discriminate Clinically Similar Neurodegenerative and Vascular-Related Diseases

Neurodegenerative diseases (NDs) are age-dependent; among them, Alzheimer's disease (AD) and Parkinson's disease (PD) are the most frequent. Similarly, cerebrovascular damage can induce the development of vascular-related disorders that share common features with AD and PD, respectively, named vascular dementia (VD) and vascular parkinsonism (VP). To date, ND diagnosis is mainly clinical; therefore, since these disorders show similar symptoms, their correct discrimination may be difficult. We detected 23 ND-associated microRNAs (miRNAs) by literature mining and investigated their serum expression in a cohort of 139 patients including AD, PD, VD, and VP patients and healthy controls. TaqMan RT-PCR data showed that miR-23a upregulation was associated with an ongoing neurodegenerative process, similar to miR-22* and miR-29a, while let-7d, miR-15b, miR-24, miR-142-3p, miR-181c, and miR-222 showed an altered expression in Parkinson-like phenotypes, as well as miR-34b, miR-125b, and miR-130b in Alzheimer-like disorders. By computing logistic regression models and ROC curves, we identified signatures of neuro-miRNAs specific for each disease, showing good diagnostic performance. Interestingly, we found that miR-23a, miR-29a, miR-34b, and miR-125b exhibited a different distribution between exosomes and vesicle-free serum, suggesting a heterogeneity of secretion for these miRNAs. Our results suggest that miRNA signatures could discriminate in a non-invasive manner neurodegenerative disorders, thus improving clinical diagnoses.

Pharmacogenetics of Atremorine-Induced Neuroprotection and Dopamine Response in Parkinson's Disease

Atremorine is a novel bioproduct with neuroprotective effects on dopaminergic neurons and a natural L-DOPA donor in Parkinson's disease (PD). In the present study, we show the effects of a single dose of Atremorine (5 g, p. o.) on plasma dopamine (DA) response and brain function in PD (n = 183) and the influence that pathogenic (LRRK2), metabolic (CYP2D5, CYP2C9, CYP2C19, CYP3A5, NAT2), transporter (ABCB1), pleiotropic (APOE), and detoxifying genes (CYP1B1, GSTT1, GSTP1, GSTM1, SOD2) involved in the pharmacogenetic network exerts on Atremorine-induced DA response. Over 90% of PD patients at diagnosis show plasma DA levels below 20 pg/mL. Atremorine induces DA synthesis causing a significant increase in plasma DA levels 1 h after administration in practically 100% of patients. Females tend to show lower basal DA levels than males and the response of DA to Atremorine is stronger in males than in females. Atremorine-induced DA response is pharmacogenotype-specific and lasts from 6 - 12 h depending upon the pharmacogenetic profile of each patient. Genetic variants in pathogenic genes, metabolic genes, and genes involved in the detoxification processes affect the response of DA to Atremorine in a genotype-specific manner. Atremorine or any of its bioactive components can cross the blood-brain barrier and improve brain function and motor function, as revealed by the reduction in slow wave activity in brain mapping and psychometric assessment, respectively. Atremorine is a selective neuroprotective agent for dopaminergic neurons with prophylactic and therapeutic potential in PD.

Acetaminophen Overdose as a Potential Risk Factor for Parkinson's Disease

Four complementary approaches were used to investigate acetaminophen overdose as a risk factor for Parkinson's disease (PD). Circulating microRNAs (miRNAs) serum profiles from acetaminophen-overdosed patients were compared with patients with terminal PD, revealing four shared miRNAs. Similarities were found among molecular structures of dopamine (DA), acetaminophen, and two known PD inducers indicating affinity for dopaminergic transport. Potential interactions between acetaminophen and the human DA transporter were confirmed by molecular docking modeling and binding free energy calculations. Thus, it is plausible that acetaminophen is taken up by the dopaminergic transport system into the substantia nigra (SN). A ChEMBL query identified proteins that are similarly targeted by DA and acetaminophen. Here, we highlight CYP3A4, present in the SN, a predominant metabolizer of acetaminophen into its toxic metabolite N-acetyl-p-benzoquinone imine and shown to be regulated in PD. Overall, based on our results, we hypothesize that overdosing of acetaminophen is a potential risk factor for parkinsonism.

Differential proteomic analysis of serum exosomes reveals alterations in progression of Parkinson disease

Exosomes are nanometer-sized vesicles with intercellular communication functions, and their encapsulated proteins may participate in the pathological process of neurodegenerative disorders. The aim of this study was to identify the protein changes of serum exosomes in Parkinson disease (PD) patients with different disease progress types, and to identify potential biomarkers. The exosomes of PD patients with different severity and healthy control group were isolated from serum. The exosome proteins were analyzed by mass spectrometry with label-free quantitative proteomics. A total of 429 proteins were identified, of which 14 were significantly different in mild and severe PD patients. The expression levels of 7 proteins, including pigmented epithelium-derived factor, afamin, apolipoprotein D and J, were significantly increased in PD patients. The expression levels of 7 proteins, including complement C1q and protein Immunoglobulin Lambda Variable 1-33 (IGLV1-33)Cluster -33, were decreased in PD patients. These differentially expressed proteins were analyzed by gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis, which confirmed that the interaction between prion diseases and ECM receptors was the most significant pathways of enrichment. The changes of proteins and pathways may be related to the pathophysiological mechanism of PD. Therefore, some of these proteins could be considered as potential biomarkers for early PD diagnosis.

Characterization of Parkinson's disease using blood-based biomarkers: A multicohort proteomic analysis

BACKGROUND

Parkinson's disease (PD) is a progressive neurodegenerative disease affecting about 5 million people worldwide with no disease-modifying therapies. We sought blood-based biomarkers in order to provide molecular characterization of individuals with PD for diagnostic confirmation and prediction of progression.

METHODS AND FINDINGS

In 141 plasma samples (96 PD, 45 neurologically normal control [NC] individuals; 45.4% female, mean age 70.0 years) from a longitudinally followed Discovery Cohort based at the University of Pennsylvania (UPenn), we measured levels of 1,129 proteins using an aptamer-based platform. We modeled protein plasma concentration (log10 of relative fluorescence units [RFUs]) as the effect of treatment group (PD versus NC), age at plasma collection, sex, and the levodopa equivalent daily dose (LEDD), deriving first-pass candidate protein biomarkers based on p-value for PD versus NC. These candidate proteins were then ranked by Stability Selection. We confirmed findings from our Discovery Cohort in a Replication Cohort of 317 individuals (215 PD, 102 NC; 47.9% female, mean age 66.7 years) from the multisite, longitudinally followed National Institute of Neurological Disorders and Stroke Parkinson's Disease Biomarker Program (PDBP) Cohort. Analytical approach in the Replication Cohort mirrored the approach in the Discovery Cohort: each protein plasma concentration (log10 of RFU) was modeled as the effect of group (PD versus NC), age at plasma collection, sex, clinical site, and batch. Of the top 10 proteins from the Discovery Cohort ranked by Stability Selection, four associations were replicated in the Replication Cohort. These blood-based biomarkers were bone sialoprotein (BSP, Discovery false discovery rate [FDR]-corrected p = 2.82 × 10-2, Replication FDR-corrected p = 1.03 × 10-4), osteomodulin (OMD, Discovery FDR-corrected p = 2.14 × 10-2, Replication FDR-corrected p = 9.14 × 10-5), aminoacylase-1 (ACY1, Discovery FDR-corrected p = 1.86 × 10-3, Replication FDR-corrected p = 2.18 × 10-2), and growth hormone receptor (GHR, Discovery FDR-corrected p = 3.49 × 10-4, Replication FDR-corrected p = 2.97 × 10-3). Measures of these proteins were not significantly affected by differences in sample handling, and they did not change comparing plasma samples from 10 PD participants sampled both on versus off dopaminergic medication. Plasma measures of OMD, ACY1, and GHR differed in PD versus NC but did not differ between individuals with amyotrophic lateral sclerosis (ALS, n = 59) versus NC. In the Discovery Cohort, individuals with baseline levels of GHR and ACY1 in the lowest tertile were more likely to progress to mild cognitive impairment (MCI) or dementia in Cox proportional hazards analyses adjusting for age, sex, and disease duration (hazard ratio [HR] 2.27 [95% CI 1.04-5.0, p = 0.04] for GHR, and HR 3.0 [95% CI 1.24-7.0, p = 0.014] for ACY1). GHR's association with cognitive decline was confirmed in the Replication Cohort (HR 3.6 [95% CI 1.20-11.1, p = 0.02]). The main limitations of this study were its reliance on the aptamer-based platform for protein measurement and limited follow-up time available for some cohorts.

CONCLUSIONS

In this study, we found that the blood-based biomarkers BSP, OMD, ACY1, and GHR robustly associated with PD across multiple clinical sites. Our findings suggest that biomarkers based on a peripheral blood sample may be developed for both disease characterization and prediction of future disease progression in PD.

Novel clinical features of glycine receptor antibody syndrome: A series of 17 cases

Objective

To describe novel clinical features of GlyRα1-IgG-positive patients.

Methods

Patients with a positive serum GlyRα1-IgG were identified during a 2-year period from July 2016 to December 2018 at 2 academic centers and followed prospectively. All patients in this series were evaluated in the Neuroimmunology and Autoimmune Neurology clinics at the University of Utah or the University of Colorado.

Results

Thirteen of 17 patients had phenotypes more typically associated with glutamic acid decarboxylase (GAD65) antibody syndromes, consisting of stiff-person syndrome (SPS) with parkinsonism or cerebellar signs. One patient with parkinsonism had a presentation similar to rapidly progressive multiple system atrophy with severe dysautonomia. Ten of 17 patients had various visual symptoms including visual snow, spider web-like images forming shapes and 3-dimensional images, palinopsia, photophobia, visual hallucinations, synesthesia, and intermittent diplopia. Three of 17 patients presented with primarily autoimmune epilepsy accompanied by psychiatric symptoms.

Conclusions

Clinicians should consider testing for GlyR antibodies in GAD65 antibody-negative or low-positive GAD65 antibody patients with SPS-like presentations, especially in the setting of atypical features such as visual disturbances, parkinsonism, or epilepsy.

Demographics and Autoantibody Profiles of Pemphigoid Patients with Underlying Neurologic Diseases

Bullous pemphigoid (BP) is an autoantibody-mediated blistering disease that is often associated with neurologic disease. BP antibodies target two epidermal adhesion molecules, known as BP180 and BP230. Homologues to these proteins are found in the brain, and it is hypothesized that neurologic disease leads to the production of autoantibodies that can cross-react with their cutaneous forms. To better understand the link between BP and neurologic disease, we evaluated primary demographic features (age, sex, race, ethnicity, and elapsed time between onset of skin symptoms and BP diagnosis), severity of BP, and IgG and IgE autoantibody levels in BP control individuals and patients with BP with preceding Parkinson disease, dementia, and stroke. The main findings of this study are that patients with BP with preceding neurologic disease have a shorter elapsed time between onset of skin disease and BP diagnosis and that patients with preceding Parkinson disease or dementia, but not stroke, are significantly older than patients with BP without neurologic disease. However, no significant differences in clinical presentation, BP severity scores, or autoantibody (IgG and IgE) responses were observed among the groups. These findings suggest that, despite the age difference, the clinical phenotype of BP is not affected by preceding neurologic disease.

Mitochondrial MsrB2 serves as a switch and transducer for mitophagy

Mitophagy can selectively remove damaged toxic mitochondria, protecting a cell from apoptosis. The molecular spatial-temporal mechanisms governing autophagosomal selection of reactive oxygen species (ROS)-damaged mitochondria, particularly in a platelet (no genomic DNA for transcriptional regulation), remain unclear. We now report that the mitochondrial matrix protein MsrB2 plays an important role in switching on mitophagy by reducing Parkin methionine oxidation (MetO), and transducing mitophagy through ubiquitination by Parkin and interacting with LC3. This biochemical signaling only occurs at damaged mitochondria where MsrB2 is released from the mitochondrial matrix. MsrB2 platelet-specific knockout and in vivo peptide inhibition of the MsrB2/LC3 interaction lead to reduced mitophagy and increased platelet apoptosis. Pathophysiological importance is highlighted in human subjects, where increased MsrB2 expression in diabetes mellitus leads to increased platelet mitophagy, and in platelets from Parkinson's disease patients, where reduced MsrB2 expression is associated with reduced mitophagy. Moreover, Parkin mutations at Met192 are associated with Parkinson's disease, highlighting the structural sensitivity at the Met192 position. Release of the enzyme MsrB2 from damaged mitochondria, initiating autophagosome formation, represents a novel regulatory mechanism for oxidative stress-induced mitophagy.

Genes associated with Parkinson's disease respond to increasing polychlorinated biphenyl levels in the blood of healthy females

Polychlorinated biphenyls (PCBs) are a class of widespread environmental pollutants, commonly found in human blood, that have been suggested to be linked to the occurrence of sporadic Parkinson's disease (PD). It has been reported that some non-coplanar PCBs accumulate in the brains of female PD patients. To improve our understanding of the association between PCB exposure and PD risk we have applied whole transcriptome gene expression analysis in blood cells from 594 PCB-exposed subjects (369 female, 225 male). Interestingly, we observe that in females, blood levels of non-coplanar PCBs appear to be associated with expression levels of PD-specific genes. However, no such association was detected in males. Among the 131 PD-specific genes affected, 39 have been shown to display similar changes in expression levels in the substantia nigra of deceased PD patients. Especially among the down-regulated genes, transcripts of genes involved in neurotransmitter vesicle-related functions were predominant.

A metabolomic signature of treated and drug-naïve patients with Parkinson's disease: a pilot study

INTRODUCTION

About 90% of cases of Parkinson's disease (PD) are idiopathic and attempts to understand pathogenesis typically assume a multifactorial origin. Multifactorial diseases can be studied using metabolomics, since the cellular metabolome reflects the interplay between genes and environment.

OBJECTIVE

The aim of our case-control study is to compare metabolomic profiles of whole blood obtained from treated PD patients, de-novo PD patients and controls, and to study the perturbations correlated with disease duration, disease stage and motor impairment.

METHODS

We collected blood samples from 16 drug naïve parkinsonian patients, 84 treated parkinsonian patients, and 42 age matched healthy controls. Metabolomic profiles have been obtained using gas chromatography coupled to mass spectrometry. Multivariate statistical analysis has been performed using supervised models; partial least square discriminant analysis and partial least square regression.

RESULTS

This approach allowed separation between discrete classes and stratification of treated patients according to continuous variables (disease duration, disease stage, motor score). Analysis of single metabolites and their related metabolic pathways revealed unexpected possible perturbations related to PD and underscored existing mechanisms that correlated with disease onset, stage, duration, motor score and pharmacological treatment.

CONCLUSION

Metabolomics can be useful in pathogenetic studies and biomarker discovery. The latter needs large-scale validation and comparison with other neurodegenerative conditions.

Plasma VCAM1 levels correlate with disease severity in Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by motor and non-motor symptoms. There is increasing evidence that PD pathology is accompanied by an inflammatory response. This is highly relevant for understanding disease progression and the development of novel neuroprotective therapies.

OBJECTIVE

Assessing potential dysregulation of a panel of inflammatory mediators in the peripheral blood mononuclear cells (PBMCs) and plasma of PD patients and in the context of clinical outcome metrics.

METHODS

We performed a screening of selected cell-surface chemokine receptors and adhesion molecules in PBMCs from PD patients and age-matched healthy controls in a flow cytometry-based assay. ELISA was used to quantify VCAM1 levels in the plasma of PD patients. Lymphocytic chemotactic ability was assessed using a modified Boyden chamber assay.

RESULTS

VLA4 expression was significantly downregulated on CD3+ T cells, CD56+ NK cells, and CD3+/CD56+ NK-T cells from PD patients; further, an increase of the soluble VLA4 ligand VCAM1 in patient plasma was noted. sVCAM1 in PD patients was even higher than reported for patients with multiple sclerosis, neuromyelitis optica, and rheumatoid arthritis. sVCAM1 levels correlated with the disease stage (Hoehn and Yahr scale) and motor impairment. Chemoattraction with SDF-1α revealed impaired motility of lymphocytes from PD patients relative to controls.

CONCLUSION

Our data provides evidence for a functional dysregulation of the sVCAM1-VLA4 axis in PD. Further studies evaluating the therapeutic potential of this axis are warranted.

Gender specific decrease of a set of circulating N-acylphosphatidyl ethanolamines (NAPEs) in the plasma of Parkinson's disease patients

INTRODUCTION

Current markers of Parkinson's disease (PD) fail to detect the early progression of disease state. Conversely, current omics techniques allow the investigation of hundreds of molecules potentially altered by disease conditions. Based on evidence previously collected by our group in a mouse model of PD, we speculated that a particular set of circulating lipids might be significantly altered by the pathology.

OBJECTIVES

The aim of current study was to evaluate the potential of a particular set of N-acyl-phosphatidylethanolamines (NAPEs) as potential non-invasive plasma markers of ongoing neurodegeneration from Parkinson's disease in human subjects.

METHODS

A panel of seven NAPEs were quantified by LC-MS/MS in the plasma of 587 individuals (healthy controls, n = 319; Parkinson's disease, n = 268); Random Forest classification and statistical modeling was applied to compare Parkinson's disease versus controls. All p-values obtained in different tests were corrected for multiplicity by controlling the false discovery rate (FDR).

RESULTS

The results indicate that this panel of NAPEs is able to distinguish female PD patients from the corresponding healthy controls. Further to this, the observed downregulation of these NAPEs is in line with the results in plasma of a mouse model of Parkinson's (6-OHDA).

CONCLUSIONS

In the current study we have shown the downregulation of NAPEs in plasma of PD patients and we thus speculate that these lipids might serve as candidate biomarkers for PD. We also suggest a molecular mechanism, explaining our findings, which involves gut microbiota.

Selected serum cytokines and nitric oxide as potential multi-marker biosignature panels for Parkinson disease of varying durations: a case-control study

BACKGROUND

Dopaminergic neuronal loss begins years before motor symptoms appear in Parkinson disease (PD). Thus, reliable biomarkers for early diagnosis and prognosis of PD are an essential pre-requisite to develop disease modifying therapies. Inflammation-derived oxidative stress is postulated to contribute to nigrostriatal degeneration. We evaluated the role of selected serum immune mediators (IFNγ, TNFα, IL-10, and NOx) in PD progression and estimated their usefulness in preclinical diagnosis.

METHODS

This case-control study recruited 72 PD patients with varying disease durations (< 1-year, n = 12 patients; 1-3 years, n = 30; > 3 years, n = 30) and 56 age- and gender-matched controls (26 with other neurological disorders as disease controls, and 30 healthy controls). Serum cytokine levels and NOx quantified using Sandwich Enzyme Linked Immunosorbent Assay kits, and the Griess test, respectively, were evaluated for diagnostic accuracy of optimal marker combinations by the CombiROC method. PD patients were clinically evaluated for motor and non-motor symptoms, and staged based on Hoehn and Yahr (H-Y) scale.

RESULTS

A significant increase in serum IFNγ and IL-10 was observed in PD compared to healthy controls (p < 0.001). The Th1: Th2 (IFNγ: IL-10) cytokine ratio was higher in PD of 3-12 years compared with PD < 1 year (p < 0.001). Highest levels of NOx manifested during early PD (1-3 years) through a subsequent decline with disease duration. TNFα level was highest at PD onset. A low serum NOx level was associated with cognitive impairment (p = 0.002). The potential of using multi-biomarker panel, IFNγ, IL-10 and TNFα, for detection of PD onset was evident (sensitivity [SE] = 83.3%, specificity [SP] =80.4%, area under curve [AUC] = 0.868), while for early and late PD the multi-biomarker signature of IFNγ, IL-10 and NOx appeared to be more promising (SE = 93.3%, SP = 87.5%, AUC = 0.924).

CONCLUSION

A Th1 cytokine-biased immune response predominates with PD progression. Both IFNγ and IL-10 are involved in disease severity. However, TNFα-mediated neurotoxicity appears to occur in early PD.

Pharmacokinetics and pharmacodynamics of a single dose Nilotinib in individuals with Parkinson's disease

Nilotinib is a broad-based tyrosine kinase inhibitor with the highest affinity to inhibit Abelson (c-Abl) and discoidin domain receptors (DDR1/2). Preclinical evidence indicates that Nilotinib reduces the level of brain alpha-synuclein and attenuates inflammation in models of Parkinson's disease (PD). We previously showed that Nilotinib penetrates the blood-brain barrier (BBB) and potentially improves clinical outcomes in individuals with PD and dementia with Lewy bodies (DLB). We performed a physiologically based population pharmacokinetic/pharmacodynamic (popPK/PD) study to determine the effects of Nilotinib in a cohort of 75 PD participants. Participants were randomized (1:1:1:1:1) into five groups (n = 15) and received open-label random single dose (RSD) 150:200:300:400 mg Nilotinib vs placebo. Plasma and cerebrospinal fluid (CSF) were collected at 1, 2, 3, and 4 hours after Nilotinib administration. The results show that Nilotinib enters the brain in a dose-independent manner and 200 mg Nilotinib increases the level of 3,4-Dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), suggesting alteration to dopamine metabolism. Nilotinib significantly reduces plasma total alpha-synuclein and appears to reduce CSF oligomeric: total alpha-synuclein ratio. Furthermore, Nilotinib significantly increases the CSF level of triggering receptors on myeloid cells (TREM)-2, suggesting an anti-inflammatory effect. Taken together, 200 mg Nilotinib appears to be an optimal single dose that concurrently reduces inflammation and engages surrogate disease biomarkers, including dopamine metabolism and alpha-synuclein.

Brain cholesterol metabolism and Parkinson's disease

BACKGROUND

Circulating cholesterol levels have been linked to PD, but not directly to brain physiology.

OBJECTIVE

To assess whether brain cholesterol metabolism is related to PD.

METHODS

Sixty PD patients and 64 controls were recruited from an academic movement disorder clinic (2009-2012). Thirty-five PD patients and 33 controls returned approximately 36 months later. Fasting plasma (S)24-OH-cholesterol (brain-derived cholesterol metabolite) and 27-OH-cholesterol (peripheral cholesterol metabolite) were quantified. Odds ratios for PD were derived from logistic regression models, adjusting for potential confounders. Relationships between the oxysterols and clinical measurements were explored using Spearman correlation coefficients.

RESULTS

Mean age of PD subjects was 63.8 ± 8.3 years and disease duration was 5.0 ± 5.4 years. Plasma (S)24-OH-cholesterol levels were inversely associated with the odds of having PD, with an odds ratio of 0.92 (95% confidence interval: 0.87-0.97) for each 1-ng/mL increase (P = 0.004). Compared to the lowest tertile, the odds ratio was 0.34 (0.12-0.98) for the second tertile (P = 0.045) and 0.08 (0.02-0.31) for the highest tertile (P < 0.001). Higher (S)24-OH-cholesterol levels also were correlated with better sense of smell (r = 0.35; P = 0.01). No significant associations were found between clinical measures and 27-OH-cholesterol, a peripheral cholesterol metabolite. Furthermore, (S)24-OH-cholesterol levels were stable over time, whereas 27-OH-cholesterol decreased with time in both cases and controls.

CONCLUSIONS

Results indicate that plasma (S)24-OH-cholesterol (possibly reflecting brain cholesterol metabolism) is inversely linked to PD, is relatively stable over time, and may serve as a new biomarker for PD. Further investigation is necessary to determine the mechanistic and clinical implications. © 2019 International Parkinson and Movement Disorder Society.

Plasma alpha-synuclein levels in patients with Parkinson's disease: a systematic review and meta-analysis

OBJECTIVE

To date, there are no definitive biomarkers for diagnose Parkinson's disease (PD). The detection of α-synuclein (α-Syn) in plasma of PD patients has yielded promising but inconclusive results. To determine the performance of α-Syn as a diagnostic biomarker of PD, we used a meta-analysis.

METHODS

We identified 173 studies through a systematic literature review. From those, only studies reporting data on total α-Syn levels were included in the meta-analysis (10 publications, 1302 participants). Quality of studies was assessed by Newcastle-Ottawa scale.

RESULTS

The α-Syn levels were significantly higher in PD patients than healthy controls (standardized mean difference [SMD] = 0.778, 95% confidence interval = 0.284 to 1.272, p = 0.002). Similar results were found after omitting any individual study from meta-analysis, with SMD ranges from 0.318 (95% CI = 0.064 to 0.572, p = 0.014) to 0.914 (95% CI = 0.349 to 1.480, p = 0.002). According to meta-regression analysis, increased mean patients age (slope = - 0.232, 95% CI = - 0.456 to - 0.008, p = 0.042), increased total number of participants (slope = - 0.007, 95% CI = - 0.013 to - 0.0004, p = 0.038), and increased percentage of males (slope = - 6.444, 95% CI = - 10.841 to - 2.047, p = 0.004) were associated with decreased SMD of α-Syn levels across studies. We did not find any significant association between the SMD in α-Syn levels and disease duration, disease severity, and quality of studies. Most of studies applied ELISA assays.

CONCLUSION

Total plasma α-Syn levels were higher in PD patients than controls. Analytical factors were important limitations.

The impact of an aquatic exercise program on BDNF levels in Parkinson's disease patients: short-and long-term outcomes

The present study aimed to analyze the short-and long-term effects of an aquatic exercise program on plasma brain-derived neurotrophic factor (BDNF) levels in individuals with Parkinson's disease (PD). The aquatic exercise program lasted one month, and consisted of two sessions per week (1 hour per session). Blood samples were collected at four different timepoints: pre-intervention (T0), immediately after the first session (T1), 48 hours after the first session (T2), and 1 month after the intervention (T3). We found a significant decrease in BDNF levels at T2 vs T1 (p<0.05). However, no changes were observed at the other time-points. Our results demonstrated that the intervention reduced plasma BDNF levels in PD individuals in a time-dependent manner: specifically, we observed acute effects, but no delayed effects.

Correlation of serum levels and gene expression of tumor necrosis factor-α-induced protein-8 like-2 with Parkinson disease severity

Different immune-mediated mechanisms involved in the pathogenesis of Parkinson disease (PD) as a neurodegenerative and inflammatory disease. According to our knowledge, there is no report evaluating Tumor necrosis factor-α-induced protein-8 like-2 (TIPE2), a cytokine maintaining immune homeostasis, in PD. We analyzed the correlation of the serum levels and circulatory gene expression of TIPE2 with severity of PD. In this case-control study, 43 patients with PD and 40 healthy subjects were enrolled. The diagnosis of PD was performed byclinical diagnostic criteria of the UK Parkinson's Disease Society Brain Bank. The severity of PD was evaluated by modified Hoehn and Yahr (H and Y) scale. Serum levels and gene expression of TIPE2 were assessed by Elisa and real time PCR, respectively. The mean serum levels and gene expression of TIPE2 in patients with PD did not have significant difference compared to healthy subjects. Linear multiple regression analysis showed that increased serum levels of TIPE2 are positively related to age and severity of PD (P ≤ 0.0001). In addition, the gene expression of TIPE2 was found to be associated with age (P < 0.0001). Our study showed that the serum levels of TIPE2 and its gene expression might be important prognostic biomarkers of PD.

Proposition of zinc supplementation during levodopa-carbidopa intestinal gel treatment

OBJECTIVES

Levodopa-carbidopa intestinal gel (LCIG) infusion is a useful therapy for the wearing-off phenomenon of advanced Parkinson's disease (PD) patients. Recently, we found three PD patients that may have had a zinc deficiency after the LCIG infusion, possibly due to the zinc-chelating action of levodopa. This study aims to evaluate changes in serum zinc levels in three patients that received LCIG treatment and to determine possible remedies for zinc deficiency during treatment.

MATERIALS AND METHODS

We performed a prospective blood analysis of serum zinc levels before, when possible, and after LCIG treatment in our three PD patients.

RESULTS

The serum zinc levels of the first patient before treatment and 4 months after beginning LCIG treatment were 69 and 58 μg/dl, respectively. For the second patient, serum zinc levels before treatment and two months after starting LCIG treatment were 87 and 46 μg/dl, respectively. The baseline serum zinc level for the third patient was not examined, but was 48 μg/dl 5 months after starting the LCIG infusion.

CONCLUSIONS

Levodopa-carbidopa intestinal gel infusion might have caused a zinc deficiency through levodopa zinc chelation. Zinc deficiency with LCIG infusion has not yet been reported, though preventing zinc deficiency may be an important factor in future LCIG treatment strategies.

Levels of plasma neurofilament light chain and cognitive function in patients with Alzheimer or Parkinson disease

Plasma neurofilament light (NFL) has been proposed as a blood-based biomarker for neurodegeneration in Alzheimer's disease (AD) and parkinsonian disorders. However, the relationship between plasma NFL and cognitive decline in dementia due to Parkinson's disease (PD) remains to be elucidated. In this research, 119 AD, 56 mild cognitive impairment (MCI), 26 non-demented PD (PDND), and 23 Parkinson's disease dementia (PDD) patients, as well as 59 cognitively healthy controls (HC) were recruited. Each subject underwent a battery of neuropsychological testing. Plasma NFL levels were measured in duplicate using an NF-Light assay and transferred onto the Simoa platform with a home-brew kit. Plasma NFL was significantly increased in the AD group, compared with the control, MCI, PDND, and PDD groups. Plasma NFL was significantly higher in the PDD group, compared with the PDND group. High plasma NFL correlated with poor cognition in AD and PD, but not with motor symptoms in PD. Plasma NFL may represent a biomarker of cognitive decline in AD and PD, with more specificity for AD.

Altered regulation of serum lysosomal acid hydrolase activities in Parkinson's disease: A potential peripheral biomarker?

INTRODUCTION

Recent studies have indicated that lysosomal dysfunction contributes to the development of idiopathic Parkinson's disease (PD). It is uncertain whether dysregulation of serum lysosomal acid hydrolase activity exists in sporadic PD patients compared with normal controls (NCs) and parkinsonian syndrome (PS) patients.

METHODS

Sporadic PD patients without GBA1 mutations (n = 68) were matched with normal controls (n = 45), and parkinsonian syndrome patients (n = 32) in terms of family history, age, and sex. We measured the activities of lysosomal enzymes, α-galactosidase, β-galactosidase, and β-hexosaminidase and examined the possible correlations between lysosomal acid hydrolase activities with age in NCs, PD, and PS patients.

RESULTS

β-Galactosidase activity was significantly higher in the PD and PS than in the NC group (P < 0.001). The β-galactosidase to α-galactosidase and β-hexosaminidase to β-galactosidase activity ratios were more useful for distinguishing PD and PS patients from NCs (P < 0.0001). Furthermore, α-galactosidase activity was significantly higher in PS patients than both PD and NC groups (p = 0.04). β-Galactosidase and α-galactosidase activities exhibited a statistically significant negative correlation with age in NCs, and β-hexosaminidase activity showed a positive correlation with age in PS. However, PD patients did not show any of these correlations.

CONCLUSION

Our results suggest the presence of an unknown regulatory mechanism(s) of serum acid hydrolase activities with aging in the normal population and abnormalities in their regulation in PD and PS patients. However, the pattern of dysregulation in these two groups is different. Thus, serum lysosomal acid hydrolase activity can be used as a peripheral biomarker for PD.

Serum 25-hydroxyvitamin D3 level may be associated with olfactory dysfunction in de novo Parkinson's disease

The purpose of our study was to investigate the association between olfactory function in Parkinson's disease (PD) and serum vitamin D status. Thirty-nine patients with de novo PD were enrolled in this study. Olfactory function was assessed by an odor identification test, as a part of the KVSS (Korean version of sniffin' sticks) II test. All patients were also assessed with the NMSS (Non-Motor Symptoms Scale for PD) to check the subjective change in ability to smell. Vitamin D status was determined by measuring the level of serum 25-hydroxyvitamin D3 (25-OHD3). Multiple linear regression tests and correlation analysis were applied to verify the association between serum 25-OHD3 level and patients' subjective and objective olfactory dysfunction. The serum 25-OHD3 level was independently associated with odor identification score in patients with PD (β = 0.38, p < 0.01). Another statistically significant variable was clinical subtype of PD (Intermediate subtype: β = -0.33, p < 0.05; Akinetic rigid type: β = -0.55, p < 0.01). The serum 25-OHD3 level was also negatively correlated with the score for item number 28 in NMSS (Spearman's rho = -0.32, p < 0.05). Our results showed that vitamin D status might be an independent factor for olfactory dysfunction in PD. Although the underlying mechanism has not been clearly identified, we postulate that vitamin D plays a role in the pathogenesis of olfactory dysfunction in PD. Further investigation to elucidate the precise relationship of vitamin D to PD is essential.

Cortisol levels, motor, cognitive and behavioral symptoms in Parkinson's disease: a systematic review

Parkinson's disease (PD) is a progressive and multifactorial neurodegenerative disease. It has been suggested that a dysregulation of the hypothalamic-pituitary-adrenal axis (HPA) occurs in PD. Furthermore, this dysregulation may be involved in triggering, exacerbation or progression of disease. The objective of this study was to systematically review the literature regarding cortisol levels and their relation with motor, cognitive and behavioral symptoms in patients with PD. A systematic search was performed in PubMed and Embase databases, according to PRISMA norms. Twenty-one studies were included, which evaluated baseline levels of cortisol and motor, cognitive, behavioral symptoms, drugs administration or deep brain stimulation to PD treatment. Sample size ranged from 7 to 249 individuals. In 14 studies that assessed cortisol levels in PD patients, seven showed elevation of cortisol levels. In relation to symptomatology, high levels of cortisol were associated with worst functional scores evaluated by UPDRS, depression and behavior in risk preference. Medication interactions showed an influence on the regulation of cortisol release, mainly, conventional drugs used in the PD's treatment, such as levodopa. The results found in this review point to a possible relationship between cortisol levels and symptoms in PD, indicating that an HPA axis dysfunction related to cortisol level occurs in PD.

Elevated microRNA-520d-5p in the serum of patients with Parkinson's disease, possibly through regulation of cereloplasmin expression

Iron metabolism dysfunction and redox-active iron-induced oxidative stress in the brain may contribute to the pathogenesis of Parkinson's disease. We have previously demonstrated that reduced serum ceruloplasmin level exacerbates nigral iron deposition in Parkinson's disease, although the underlying cause of the low serum ceruloplasmin level in Parkinson's disease remains unknown. Fluorescent quantitative real-time polymerase chain reaction analysis revealed that patients with Parkinson's disease had higher serum levels of microRNA (miR)-520d-5p than controls (p = 0.0011). Patients with Alzheimer's disease or multiple system atrophy did not have significantly elevated miR-520d-5p levels. Expression of miR-520d-5p did not correlate with disease severity or the motor phenotype of Parkinson's disease. Luciferase assays confirmed that miR-520d-5p was associated with ceruloplasmin gene expression, as predicted by the TargetScan tool and miRBase. In vitro experiments showed that miR-520d-5p reduced ceruloplasmin gene expression in the U251 astrocyte cell line. Our data suggest that miR-520d-5p may be a potential regulator of ceruloplasmin gene expression in vitro.

Decreased Serum Lipid Levels and Ratios Correlate with Low Prevalence of Coronary Heart Disease in Patients with Parkinson's Disease

BACKGROUND

Patients with Parkinson's disease (PD) are at a lower risk of suffering cardiovascular events, but the underlying factors for this decreased risk remain unclear. Serum triglycerides (TG) and total cholesterol (TC), and their expression relative to high-density lipoprotein cholesterol (TG/HDL-C and TC/HDL-C), are independent predictors of cardiovascular events. This study aimed to determine if PD patients have decreased lipid levels and lipid ratios, which may underlie the decreased risk of coronary heart disease (CHD).

METHODS

This retrospective study included 92 PD patients (PD group), 450 control subjects with no CHD (OD group), and 450 CHD patients (CHD group). We analyzed serum lipid levels and lipid ratios in each group.

RESULTS

There were significant differences in TC (F = 10.459, p < 0.0001), TG (F = 46.856, p < 0.0001), low density lipoprotein cholesterol (LDL-C) (F = 6.910, p = 0.001), high density lipoprotein cholesterol HDL-C (F = 30.694, p < 0.0001), TC/HDL-C (F = 32.675, p < 0.0001), and TG/HDL-C (F = 45.554, p < 0.0001) between all three groups; TC/LDL-C (F = 2.518, p = 0.081) was not significantly different between groups. Compared to the CHD group, PD patients had lower TC (p < 0.0001), TG (p < 0.0001), LDL-C (p = 0.001), TG/HDL-C (p < 0.0001), and TC/HDL-C (p < 0.0001); TC/LDL-C (p = 0.563) and HDL-C (p = 0.196) were not significantly different. TC and LDL-C levels were positively correlated within individual groups (all p < 0.0001). In addition, TG and HDL-C were negatively correlated in the OD and CHD groups (p < 0.0001); no significant negative association was observed in the PD group (p = 0.077). TG/HDL and LDL-C levels were inversely correlated in the CHD group (p < 0.0001) and weakly positively correlated in the PD (p = 0.159) and OD (p = 0.199) groups.

CONCLUSIONS

TC/HDL and TG/HDL ratios were significantly lower in PD patients compared to CHD patients, suggesting there is a strong correlation between lipid ratios and incidence of CHD in PD patients.

Upgraded Methodology for the Development of Early Diagnosis of Parkinson's Disease Based on Searching Blood Markers in Patients and Experimental Models

Numerous attempts to develop an early diagnosis of Parkinson's disease (PD) by searching biomarkers in biological fluids were unsuccessful. The drawback of this methodology is searching markers in patients at the clinical stage without guarantee that they are also characteristic of either preclinical stage or prodromal stage (preclinical-prodromal stage). We attempted to upgrade this methodology by selecting only markers that are found both in patients and in PD animal models. HPLC and RT-PCR were used to estimate the concentration of amino acids, catecholamines/metabolites in plasma and gene expression in lymphocytes in 36 untreated early-stage PD patients and 52 controls, and in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice at modeling the clinical ("symptomatic") stage and preclinical-prodromal ("presymptomatic") stage of PD. It was shown that among 13 blood markers found in patients, 7 markers are characteristic of parkinsonian symptomatic mice and 3 markers of both symptomatic and presymptomatic mice. According to our suggestion, the detection of the same marker in patients and symptomatic animals indicates adequate reproduction of pathogenesis along the corresponding metabolic pathway, whereas the detection of the same marker in presymptomatic animals indicates its specificity for preclinical-prodromal stage. This means that the minority of markers found in patients-decreased concentration of L-3,4-dihydroxyphenylalanine (L-DOPA) and dihydroxyphenylacetic acid (DOPAC) and increased dopamine D3 receptor gene expression-are specific for preclinical-prodromal stage and are suitable for early diagnosis of PD. Thus, we upgraded a current methodology for development of early diagnosis of PD by searching blood markers not only in patients but also in parkinsonian animals.

Finding useful biomarkers for Parkinson's disease

The recent advent of an "ecosystem" of shared biofluid sample biorepositories and data sets will focus biomarker efforts in Parkinson's disease, boosting the therapeutic development pipeline and enabling translation with real-world impact.

Uric Acid and Cognitive Function in Older Individuals

Hyperuricemia has been recognized as an independent cardiovascular risk factor in epidemiological studies. However, uric acid can also exert beneficial functions due to its antioxidant properties, which may be particularly relevant in the context of neurodegenerative diseases. In this paper, we critically revise the evidence on the relationship between serum uric acid levels and cognitive function in older individuals, focusing on the etiology of cognitive impairment (Alzheimer’s disease, Parkinson’s dementia, and vascular dementia) and on the interactive connections between uric acid, dementia, and diet. Despite high heterogeneity in the existing studies, due to different characteristics of studied populations and methods of cognitive dysfunction assessment, we conclude that serum uric acid may modulate cognitive function in a different way according to the etiology of dementia. Current studies indeed demonstrate that uric acid may exert neuroprotective actions in Alzheimer’s disease and Parkinson’s dementia, with hypouricemia representing a risk factor for a quicker disease progression and a possible marker of malnutrition. Conversely, high serum uric acid may negatively influence the disease course in vascular dementia. Further studies are needed to clarify the physio-pathological role of uric acid in different dementia types, and its clinical-prognostic significance.

Biomarker repurposing: Therapeutic drug monitoring of serum theophylline offers a potential diagnostic biomarker of Parkinson's disease

Caffeine has been considered a neuroprotective agent against Parkinson’s disease (PD). Recent metabolomic analysis showed that levels of caffeine and its metabolites were decreased in sera from patients with PD compared with those from healthy controls. We focused on theophylline, which is one of the primary caffeine metabolites, as a candidate biomarker of PD because: (1) its serum level can be measured in hospital laboratories by standardized immunoassay kits for therapeutic drug monitoring and (2) because it is less markedly affected by caffeine intake. This was a pilot study to measure the levels of theophylline in sera of 31 patients with PD and 33 age-matched disease controls using an immunoassay kit. We confirmed the previous finding of significantly lower levels of serum theophylline in the PD group compared with control group (PD: 0.07±0.09 μg/mL, control: 0.18±0.24 μg/mL, p<0.05). Using such an approach of applying known medical biomarkers for neurodegenerative diseases may allow us to skip the process from the discovery phase to clinical application, and subsequently shorten the period of time necessary for biomarker development.

The Effects of Probiotic Supplementation on Gene Expression Related to Inflammation, Insulin and Lipid in Patients with Parkinson's Disease: A Randomized, Double-blind, PlaceboControlled Trial

BACKGROUND

This study was conducted to evaluate the effects of probiotic supplementation on gene expression related to inflammation, insulin and lipid in patients with Parkinson's disease (PD).

METHODS

This randomized, double-blind, placebo-controlled clinical trial was conducted in 50 patients with PD as a pilot study. Participants were randomly allocated into two groups to take either 8×109 CFU/day probiotic supplements or placebo (n = 25 each group, one capsule daily) for 12 weeks. Gene expression related to inflammation, insulin, and lipid was quantified in peripheral blood mononuclear cells (PBMC) of PD patients, with RT-PCR method.

RESULTS

After the 12-week intervention, compared with the placebo, probiotic intake downregulated gene expression of interleukin-1 (IL-1) (P = 0.03), IL-8 (P < 0.001) and tumor necrosis factor alpha (TNF-α) (P=0.04) in PBMC of subjects with PD. In addition, probiotic supplementation upregulated transforming growth factor beta (TGF-β) (P = 0.02) and peroxisome proliferatoractivated receptor gamma (PPAR-γ) (P = 0.03) in PBMC of subjects with PD compared with the placebo. We did not observe any significant effect of probiotic intake on gene expression of low-density lipoprotein receptor (LDLR) and vascular endothelial growth factor (VEGF) in PBMC of patients with PD.

CONCLUSION

Overall, probiotics supplementation for 12 weeks in PD patients significantly improved gene expression of IL-1, IL-8, TNF-α, TGF-β and PPAR-γ, but did not affect gene expression of VEGF and LDLR, and biomarkers of inflammation and oxidative stress.

Supplementation of Blackcurrant Anthocyanins Increased Cyclic Glycine-Proline in the Cerebrospinal Fluid of Parkinson Patients: Potential Treatment to Improve Insulin-Like Growth Factor-1 Function

Background: Insulin-like growth factor-1 (IGF-1) function is impaired in Parkinson disease. Cyclic glycine-proline (cGP), a metabolite of IGF-1, is neuroprotective through improving IGF-1 function. Parkinson disease patients score lower on Hospital-associated Anxiety and Depression Scale after supplementing blackcurrant anthocyanins (BCA), which may be associated with IGF-1 function. We evaluated the changes of cGP and IGF-1 before and after the supplementation. Methods: Plasma and cerebrospinal fluid (CSF) were collected from 11 male patients before and after 28 day supplementation of BCA. The concentrations of IGF-1, IGF binding protein (IGFBP)-3, and cGP were measured using ELISA and HPLC-MS assays. The presence of cGP in the BCA was evaluated. Results: cGP presented in the BCA. BCA supplementation increased the concentration of cGP (p < 0.01), but not IGF-1 and IGFBP-3 in the CSF. CSF concentration of cGP was correlated with plasma concentration of cGP (R = 0.68, p = 0.01) and cGP/IGF-1 molar ratio (R = 0.66, p = 0.01). The CSF/plasma ratio was high in cGP and low in IGF-1 and IGFBP-3. Conclusion: cGP is a natural nutrient to the BCA. The increased CSF cGP in Parkinson disease patients may result from the central uptake of plasma cGP. Given neurotrophic function, oral availability, and effective central uptake of cGP, the BCA has the potential to be developed to treat neurological conditions with IGF-1 deficiency.

Level of uric acid and uric acid/creatinine ratios in correlation with stage of Parkinson disease

This study aims to investigate relationship between the level of uric acid (UA) and UA/creatinine ratios (UA/Cr) to the stage of Parkinson disease (PD).A total of 120 cases of PD patients who were admitted in our hospital between 2013 and 2015 were enrolled into this study; these 120 cases of PD patients were divided into 3 groups, according to Hoehn-Yahr (H-Y) classification: early stage (1-2 classification), medium stage (2.5-3 classification), and advanced stage (4-5 classification); UA and UA/Cr level in each group was compared. Then, factors including age, gender, dopamine dosage, UA, and UA/Cr levels were analyzed to find the independent predictive factors of PD by logistic regression.UA and UA/Cr levels in the early and medium stage PD patients were significantly higher than in the advanced stage ones. UA and UA/Cr levels in patients with good prognosis were significantly higher than in the poor ones.UA and UA/Cr levels are negatively correlated with the stages of PD and are independent negatively predicting biological indexes of PD incidence and progression.

Serum uric acid level and its association with motor subtypes and non-motor symptoms in early Parkinson's disease: PALS study

OBJECTIVE

Uric acid has been found to be potentially neuroprotective in Parkinson's disease (PD). We investigated the relationship between serum uric acid levels and both motor and non-motor features in a prospective early PD cohort study.

METHODS

Fasting serum uric acid levels were measured from 125 early PD patients. Demographic, clinical characteristics, motor and non-motor assessments were performed. Patients were categorized into three motor subtypes: tremor-dominant (TD), postural instability/gait difficulty (PIGD), and mixed. Non-motor symptoms were classified as present or absent based on the appropriate cut-offs for each non-motor instrument.

RESULTS

Most patients had TD (n = 51, 40.8%) and mixed (n = 63, 50.4%) motor subtypes, while a minority had PIGD (n = 11, 8.8%) motor subtype. The mean serum uric acid levels were significantly different between the three motor subtypes (p = 0.0106), with the mixed subtype having the lowest serum uric acid levels. Using the TD subtype as reference, patients with higher serum uric acid levels were less likely to have the mixed (OR = 0.684; p = 0.0312) subtype as opposed to the TD subtype. Uric acid levels were not significantly different between the TD and PIGD subtypes. For non-motor symptoms, higher serum uric acid levels were significantly associated with less fatigue (OR = 0.693; p = 0.0408).

CONCLUSION

Higher serum uric acid levels were associated with TD motor subtype and less fatigue in early PD, which could be related to its anti-oxidative properties. Uric acid could be an important biomarker for specific motor features and symptoms of fatigue in PD.

Peripheral T lymphocyte immunity and l-dopamine in patients with Parkinson's disease

This study aimed to evaluate the efficacy of T-cell immune function and L-dopamine (L-DOPA) in patients with Parkinson’s disease (PD). Sixty subjects (included in the study group) with PD who were patients of the Neurology Department of The Affiliated Hospital of Hangzhou Normal University from July 2015 to March 2017 were selected. The study group was then categorized into groups according to the age of the patients, severity of disease, level of cognition, and treatment of L-DOPA. The control group (30 cases) was from the healthy population of the check-up center at The Affiliated Hospital of Hangzhou Normal University. The peripheral blood T-lymphocyte subsets of the study group were measured by direct immunofluorescence flow cytometry staining and compared with the control group. At the same time, correlation analysis was carried out on patients with different degrees of disease severity according to staging, different accompanying symptoms, and whether L-DOPA was administered. The results of the study show that the levels of CD4+, CD8+, CD3+, and CD4+/CD8+ peripheral blood in PD patients were significantly lower than those in the control group (P less than 0.05). It was found that the levels of CD4+, CD8+, CD3+, and CD4+/CD8+ decreased with age. The CD4+, CD8+, CD3+, and CD4+/CD8+ in patients with advanced stage PD were more significant than those with low PD stages (P less than 0.05). The levels of CD4+, CD8+, CD3+, and CD4+/CD8+ in the dementia group were significantly lower than those in the non-dementia group (P less than 0.05). The levels of CD4+, CD8+, CD3+, and CD4+/CD8+ in PD patients treated with L-DOPA were higher than those of PD patients without L-DOPA treatment (P less than 0.05). In conclusion, the immune function of T cells in patients suffering from PD is low, and the immune function of T cells in patients with severe disease is lower. Therefore, it is of certain significance to further study the pathophysiological mechanism of PD.

Relationships between Rapid Eye Movement Sleep Behavior Disorder and Neurodegenerative Diseases: Clinical Assessments, Biomarkers, and Treatment

OBJECTIVE

Rapid eye movement sleep behavior disorder (RBD) is characterized by dream enactment and loss of muscle atonia during rapid eye movement sleep. RBD is closely related to α-synucleinopathies including Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. Many studies have investigated the markers of imaging and neurophysiological, genetic, cognitive, autonomic function of RBD and their predictive value for neurodegenerative diseases. This report reviewed the progress of these studies and discussed their limitations and future research directions.

DATA SOURCES

Using the combined keywords: "RBD", "neurodegenerative disease", "Parkinson disease", and "magnetic resonance imaging", the PubMed/MEDLINE literature search was conducted up to January 1, 2018.

STUDY SELECTION

A total of 150 published articles were initially identified citations. Of the 150 articles, 92 articles were selected after further detailed review. This study referred to all the important English literature in full.

RESULTS

Single-nucleotide polymorphisms in SCARB2 (rs6812193) and MAPT (rs12185268) were significantly associated with RBD. The olfactory loss, autonomic dysfunction, marked electroencephalogram slowing during both wakefulness and rapid eye movement sleep, and cognitive impairments were potential predictive markers for RBD conversion to neurodegenerative diseases. Traditional structural imaging studies reported relatively inconsistent results, whereas reduced functional connectivity between the left putamen and substantia nigra and dopamine transporter uptake demonstrated by functional imaging techniques were relatively consistent findings.

CONCLUSIONS

More longitudinal studies should be conducted to evaluate the predictive value of biomarkers of RBD. Moreover, because the glucose and dopamine metabolisms are not specific for assessing cognitive cognition, the molecular metabolism directly related to cognition should be investigated. There is a need for more treatment trials to determine the effectiveness of interventions of RBD on preventing the conversion to neurodegenerative diseases.

High expression of the HMGB1-TLR4 axis and its downstream signaling factors in patients with Parkinson's disease and the relationship of pathological staging

Objective

To detect the expression of high-mobility group box protein 1 (HMGB1) and toll-like receptor 4 (TLR4) and their downstream signaling factors-myeloid differentiation factor 88 (MyD88), nuclear factor kappa B (NF-κB), and tumor necrosis factor alpha (TNF-α)-in the sera of patients with Parkinson's disease (PD) in order to evaluate the relationship of the HMGB1-TLR4 axis with PD development and progression.

Methods

The serum HMGB1 and TLR4 protein levels of 120 patients with PD and 100 healthy volunteers were measured using double-antibody sandwich ELISA, and their correlations with PD staging, disease duration, drug treatment effectiveness, and clinical classification were analyzed. In addition, their correlations with the key downstream factors of the HMGB1-TLR4 axis (MyD88, NF-κB, and TNF-α) were analyzed.

Results

HMGB1 and TLR4 expressions were higher in the peripheral blood of patients with PD than in healthy volunteers. PD patients with poor drug treatment outcomes had significantly higher HMGB1 and TLR4 expressions than PD patients with stable drug treatment outcomes. Higher HMGB1 and TLR4 expressions were found in patients at higher PD stages, and patients with >4-year disease duration had significantly higher HMGB1 and TLR4 expressions than patients with <4-year disease duration. No significant difference in HMGB1 and TLR4 expressions was found among patients with tremor-dominant, akinetic-rigid, and mixed subtypes of PD. NF-κB and TNF-α expressions were positively correlated with high expression of the HMGB1-TLR4 axis.

Conclusion

High expression of the HMGB1-TLR4 axis is closely associated with PD development, progression, drug treatment effectiveness, staging, and disease duration and has great significance for PD diagnosis and treatment.

Augmented frontal cortex diacylglycerol levels in Parkinson's disease and Lewy Body Disease

Background

Research from our laboratory, and that of other investigators, has demonstrated augmented levels of diacylglycerols (DAG) in the frontal cortex and plasma of subjects with Alzheimer’s disease (AD) and Mild Cognitive Impairment (MCI). We have extended these observations to investigate the frontal cortex of subjects with Parkinson’s disease (PD) and Lewy Body Disease (LBD), with and without coexisting pathologic features of AD.

Methods/Principal findings

Utilizing a high-resolution mass spectrometry analytical platform, we clearly demonstrate that DAG levels are significantly increased in the frontal cortex of subjects with PD, LBD with intermediate neocortical AD neuropathology, and in LBD with established neocortical AD neuropathology. In the case of the PD cohort, increases in cortical DAG levels were detected in cases with no neocortical pathology but were greater in subjects with neocortical pathology. These data suggest that DAG changes occur early in the disease processes and are amplified as cortical dysfunction becomes more established.

Conclusions

These findings suggest that altered DAG synthesis/metabolism is a common feature of neurodegenerative diseases, characterized by proteinopathy, that ultimately result in cognitive deficits. With regard to the mechanism responsible for these biochemical alterations, selective decrements in cortical levels of phosphatidylcholines in LBD and PD suggest that augmented degradation and/or decreased synthesis of these structural glycerophospholipids may contribute to increases in the pool size of free DAGs. The observed augmentation of DAG levels may be phospholipase-driven since neuroinflammation is a consistent feature of all disease cohorts. If this conclusion can be validated it would support utilizing DAG levels as a biomarker of the early disease process and the investigation of early intervention with anti-inflammatory agents.