Tissue Factor and Its Cerebrospinal Fluid Protein Profiles in Parkinson's Disease.

Background: Prior investigations have elucidated pathophysiological interactions involving blood coagulation and neurodegenerative diseases. These interactions pertain to age-related effects and a mild platelet antiaggregant function of exogenous α-Synuclein. Objective: Our study sought to explore whether cerebrospinal fluid (CSF) levels of tissue factor (TF), the initiator of the extrinsic pathway of hemostasis, differ between controls (CON) compared to patients with Parkinson's disease (PD) and dementia with Lewy bodies (DLB), considering that these conditions represent a spectrum of α-Synuclein pathology. We further investigated whether TF levels are associated with longitudinal progression in PD. Methods: We examined CSF levels of TF in 479 PD patients, 67 patients diagnosed with DLB, and 16 CON in order to evaluate potential continuum patterns among DLB, PD, and CON. Of the 479 PD patients, 96 carried a GBA1 variant (PD GBA1), while the 383 non-carriers were classified as PD wildtype (PD WT). We considered both longitudinal clinical data as well as CSF measurements of common neurodegenerative markers (amyloid-ß 1-42, h-Tau, p-Tau, NfL, α-Synuclein). Kaplan-Meier survival and Cox regression analysis stratified by TF tertile levels was conducted. Results: Higher CSF levels of TF were associated with an older age at examination in PD and a significant later onset of postural instability in PD GBA1. TF levels were lower in male vs. female PD. DLB GBA1 exhibited the lowest TF levels, followed by PD GBA1, with CON showing the highest levels. Conclusions: TF as representative of blood hemostasis could be an interesting CSF candidate to further explore in PD and DLB.

Parkinson's disease is a common age-related condition, primarily affecting older individuals. However, it shows a wide range of symptoms and clinical courses, influenced by genetic mutations, neuroinflammatory processes and lifestyle factors. Research into the disease's mechanisms is important for developing new therapies that could potentially slow its progression. Early diagnosis is also essential, as new disease-modifying therapies are most effective when started at an early stage of the disease. In this paper, we focus on a protein called tissue factor, which plays a role in both blood coagulation and neuroinflammation. Proteins involved in blood-coagulation also exhibit an increase in blood-concentration with higher age. Also, a subtle platelet antiaggregant function of exogenous α-Synuclein was found, a protein which aggregates in the brain of patients with Parkinson's disease. Additionally, higher tissue factor levels were found in plaques of proteins (amyloid-ß 1-42) found in Alzheimer's disease. Thus, tissue factor could be a promising biomarker candidate for neurodegenerative diseases. We analyzed the concentration of this protein in the cerebrospinal fluid of 479 patients with Parkinson's disease, 16 control participants, and 67 patients with dementia with Lewy bodies, a sub-type of Parkinson's disease with exceptionally high levels of α-Synuclein in the brain. Our findings showed the lowest levels of tissue factor in patients with dementia with Lewy bodies, followed by those with typical Parkinson's disease, and the highest levels in controls. Additionally, older patients had higher tissue factor levels than younger patients, and levels were lower in male patients compared to female patients. Thus, measuring tissue factor levels could help in diagnosing Parkinson's disease. Further studies, especially with larger control groups, are needed to confirm these results. Additionally, exploring the connections between blood coagulation and Parkinson's disease could improve our understanding of the disease's mechanisms, potentially leading to new pharmaceutical developments.

Association of elevated cerebrospinal fluid levels of the longevity protein α-Klotho with a delayed onset of cognitive impairment in Parkinson's disease patients.

BACKGROUND AND PURPOSE: Parkinson's disease (PD) is an age-related condition characterized by substantial phenotypic variability. Consequently, pathways and proteins involved in biological aging, such as the central aging pathway comprising insulin-like growth factor 1-α-Klotho-sirtuin 1-forkhead box O3-peroxisome proliferator-activated receptor γ, may potentially influence disease progression. METHODS: Cerebrospinal fluid (CSF) levels of α-Klotho in 471 PD patients were examined. Of the 471 patients, 96 carried a GBA1 variant (PD GBA1), whilst the 375 non-carriers were classified as PD wild-type (PD WT). Each patient was stratified into a CSF α-Klotho tertile group based on the individual level. Kaplan-Meier survival curves and Cox regression analysis stratified by tertile groups were conducted. These longitudinal data were available for 255 patients. Follow-up times reached from 8.4 to 12.4 years. The stratification into PD WT and PD GBA1 was undertaken to evaluate potential continuum patterns, particularly in relation to CSF levels. RESULTS: Higher CSF levels of α-Klotho were associated with a significant later onset of cognitive impairment. Elevated levels of α-Klotho in CSF were linked to higher Montreal Cognitive Assessment scores in male PD patients with GBA1 mutations. CONCLUSIONS: Our results indicate that higher CSF levels of α-Klotho are associated with a delayed cognitive decline in PD. Notably, this correlation is more prominently observed in PD patients with GBA1 mutations, potentially reflecting the accelerated biological aging profile characteristic of individuals harboring GBA1 variants.

Longitudinal cognitive decline characterizes the profile of non-PD-manifest GBA1 mutation carriers.

With disease-modifying treatment for Parkinson's disease (PD) associated with variants in the glucocerebrosidase gene (GBA1) under way, the challenge to design clinical trials with non-PD-manifest GBA mutation carriers (GBA1NMC) comes within close reach. To delineate trajectories of motor and non-motor markers as well as serum neurofilament light (sNfL) levels and to evaluate clinical endpoints as outcomes for clinical trials in GBA1NMC, longitudinal data of 56 GBA1NMC carriers and 112 age- and sex-matched GBA1 wildtype participants (GBA1wildtype) with up to 9 years of follow-up was analyzed using linear mixed-effects models (LMEM) and Kaplan-Meier survival analysis of clinical endpoints for motor and cognitive function. GBA1NMC showed worse performance in Pegboard, 20 m fast walking, global cognition as well as in executive and memory function at baseline. Longitudinally, LMEM revealed a higher annual increase of the MDS-UPDRS III bradykinesia subscore in GBA1NMC compared to GBA1wildtype, but comparable trajectories of all other motor and non-motor markers as well as sNfL. Kaplan-Meier survival analysis showed a significantly earlier progression to clinical endpoints of cognitive decline in GBA1NMC. Incidence of PD was significantly higher in GBA1NMC. In conclusion, our study extends data on GBA1NMC indicating early cognitive decline as a potentially characteristic feature. Comprehensive longitudinal assessments of cognitive function are crucial to delineate the evolution of early changes in GBA1NMC enabling a more accurate stratification and allow for a more precise definition of trial design and sample size.

Association of Misfolded α-Synuclein Derived from Neuronal Exosomes in Blood with Parkinson's Disease Diagnosis and Duration.

Background: Misfolded α-synuclein can be detected in blood samples of Parkinson's disease (PD) patients by a seed amplification assay (SAA), but the association with disease duration is not clear, yet. Objective: In the present study we aimed to elucidate whether seeding activity of misfolded α-synuclein derived from neuronal exosomes in blood is associated with PD diagnosis and disease duration. Methods: Cross-sectional samples of PD patients were analyzed and compared to samples of age- and gender-matched healthy controls using a blood-based SAA. Presence of α-synuclein seeding activity and differences in seeding parameters, including fluorescence response (in arbitrary units) at the end of the amplification assay (F60) were analyzed. Additionally, available PD samples collected longitudinally over 5-9 years were included. Results: In the cross-sectional dataset, 79 of 80 PD patients (mean age 69 years, SD = 8; 56% male) and none of the healthy controls (n = 20, mean age 70 years, SD = 10; 55% male) showed seeding activity (sensitivity 98.8%). When comparing subgroups divided by disease duration, longer disease duration was associated with lower α-synuclein seeding activity (F60: p < 0.001). In the longitudinal analysis 10/11 patients showed a gradual decrease of α-synuclein seeding activity over time. Conclusions: This study confirms the high sensitivity of the blood-based α-synuclein SAA applied here. The negative association of α-synuclein seeding activity in blood with disease duration makes this parameter potentially interesting as biomarker for future studies on the pathophysiology of disease progression in PD, and for biologically oriented trials in this field.

CSF α-synuclein seed amplification kinetic profiles are associated with cognitive decline in Parkinson's disease.

Seed amplification assays have been implemented in Parkinson's disease to reveal disease-specific misfolded alpha-synuclein aggregates in biospecimens. While the assays' qualitative dichotomous seeding response is valuable to stratify and enrich cohorts for alpha-synuclein pathology in general, more quantitative parameters that are associated with clinical dynamics of disease progression and that might potentially serve as exploratory outcome measures in clinical trials targeting alpha-synuclein would add important information. To evaluate whether the seeding kinetic parameters time required to reach the seeding threshold (LAG phase), the peak of fluorescence response (Imax), and the area under the curve (AUC) are associated with clinical trajectories, we analyzed LAG, Imax, and AUC in relation to the development of cognitive decline in a longitudinal cohort of 199 people with Parkinson's disease with positive CSF alpha-synuclein seeding status. Patients were stratified into tertiles based on their individual CSF alpha-synuclein seeding kinetic properties. The effect of the kinetic parameters on longitudinal development of cognitive impairment defined by MoCA ≤25 was analyzed by Cox-Regression. Patients with a higher number of positive seeding replicates and tertile groups of shorter LAG, higher Imax, and higher AUC showed a higher prevalence of and a shorter duration until cognitive impairment longitudinally (3, 6, and 3 years earlier with p ≤ 0.001, respectively). Results remained similar in separate subgroup analyses of patients with and without GBA mutation. We conclude that a more prominent alpha-synuclein seeding kinetic profile translates into a more rapid development of cognitive decline.

Inflammatory CSF profiles and longitudinal development of cognitive decline in sporadic and GBA-associated PD.

Inflammation modifies the incidence and progression of Parkinson's disease (PD). By using 30 inflammatory markers in CSF in 498 people with PD and 67 people with dementia with Lewy bodies (DLB) we show that: (1) levels of ICAM-1, Interleukin-8, MCP-1, MIP-1 beta, SCF and VEGF were associated with clinical scores and neurodegenerative CSF biomarkers (Aß1-42, t-Tau, p181-Tau, NFL and α-synuclein). (2) PD patients with GBA mutations show similar levels of inflammatory markers compared to PD patients without GBA mutations, even when stratified by mutation severity. (3) PD patients who longitudinally developed cognitive impairment during the study had higher levels of TNF-alpha at baseline compared to patients without the development of cognitive impairment. (4) Higher levels of VEGF and MIP-1 beta were associated with a longer duration until the development of cognitive impairment. We conclude that the majority of inflammatory markers is limited in robustly predicting longitudinal trajectories of developing cognitive impairment.

Linking the phenotype of SNCA Triplication with PET-MRI imaging pattern and alpha-synuclein CSF seeding.

Lewy-body pathology with aggregation of abnormal conformations of the protein alpha-synuclein (α-Syn) represent the histopathological hallmarks of Parkinson's disease (PD). Genetic prototypes such as PD due to mutations in the alpha-synuclein gene (SNCA) offer the opportunity to evaluate α-Syn-related profiles in patient-derived biomaterial. We identified a family with a SNCA triplication and assessed the index patient for CSF α-Syn seeding capacity and levels of total α-Syn along with other neurodegenerative CSF markers (Aß1-42, total-Tau, phospho-Tau, NFL). As no published CSF data in patients with SNCA triplication are available, we descriptively compared his CSF profiles to those of sporadic PD patients and PD patients with GBA mutations as these are also specifically associated with prominent α-Syn pathology. Additionally, skin biopsies with staining for phospho-α-Syn were done. To assess cerebral glucose metabolism and brain atrophy combined positron emission tomography and magnetic resonance imaging ([18F]FDG-PET/MRI) was performed. Age at onset was 24 years and motor impairment was accompanied by prominent non-motor symptoms with early development of dementia, depression, REM sleep behavior disorder, hyposmia, and dysautonomia. Correspondingly, PET-MRI showed hypometabolism and atrophy in frontal, temporoparietal and occipital regions. CSF levels of total α-Syn were threefold higher and RT-QuIC showed remarkable α-Syn seeding activity in all kinetic categories in the SNCATriplication patient compared to patients with GBA mutations. Our results are consistent with findings that not only mutant forms but also overexpression of the wild-type α-Syn protein lead to PD and PD dementia and show a striking CSF α-Syn seeding profile, thus substantiating the role of RT-QuIC as a specific in vivo biomarker of α-Syn brain pathology.

CSF and Serum Levels of Inflammatory Markers in PD: Sparse Correlation, Sex Differences and Association With Neurodegenerative Biomarkers.

Background: An involvement of the central-nervous and peripheral, innate and adaptive immune system in the pathogenesis of Parkinson's disease (PD) is nowadays well established. Objectives: We face several open questions in preparation of clinical trials aiming at disease-modification by targeting the immune system: Do peripheral (blood) inflammatory profiles reflect central (CSF) inflammatory processes? Are blood/CSF inflammatory markers associated with CSF levels of neurodegenerative/PD-specific biomarkers? Methods: Using a multiplex assay we assessed 41 inflammatory markers in CSF/serum pairs in 453 sporadic PD patients. We analyzed CSF/serum correlation as well as associations of inflammatory markers with clinical outcome measures (UPDRS-III, H&Y, MoCA) and with CSF levels of α-synuclein, Aß1-42, t-Tau, p181-Tau and NFL. All analyses were stratified by sex as the immune system shows relevant sex-specific differences. Results: Correlations between CSF and serum were sparse and detected in only 25% (9 out of 36) of the analysable inflammatory markers in male PD patients and in only 38% (12 out of 32) of female PD patients. The most important pro-inflammatory mediators associated with motor and cognitive decline as well as with neurodegenerative/PD-specific biomarkers were FABP, ICAM-1, IL-8, MCP-1, MIP-1-beta, and SCF. Results were more robust for CSF than for serum. Interpretation: Levels of central-nervous and peripheral inflammatory markers might be regulated independently of each other with CSF inflammatory markers reflecting CNS pathology more accurately than peripheral markers. These findings along with sex-specific characteristics have to be considered when designing clinical trials aiming at disease-modification by targeting the immune system.

Association between CSF alpha-synuclein seeding activity and genetic status in Parkinson's disease and dementia with Lewy bodies.

The clinicopathological heterogeneity in Lewy-body diseases (LBD) highlights the need for pathology-driven biomarkers in-vivo. Misfolded alpha-synuclein (α-Syn) is a lead candidate based on its crucial role in disease pathophysiology. Real-time quaking-induced conversion (RT-QuIC) analysis of CSF has recently shown high sensitivity and specificity for the detection of misfolded α-Syn in patients with Parkinson's disease (PD) and dementia with Lewy bodies (DLB). In this study we performed the CSF RT-QuIC assay in 236 PD and 49 DLB patients enriched for different genetic forms with mutations in GBA, parkin, PINK1, DJ1, and LRRK2. A subgroup of 100 PD patients was also analysed longitudinally. We correlated kinetic seeding parameters of RT-QuIC with genetic status and CSF protein levels of molecular pathways linked to α-Syn proteostasis. Overall, 85% of PD and 86% of DLB patients showed positive RT-QuIC α-Syn seeding activity. Seeding profiles were significantly associated with mutation status across the spectrum of genetic LBD. In PD patients, we detected positive α-Syn seeding in 93% of patients carrying severe GBA mutations, in 78% with LRRK2 mutations, in 59% carrying heterozygous mutations in recessive genes, and in none of those with bi-allelic mutations in recessive genes. Among PD patients, those with severe GBA mutations showed the highest seeding activity based on RT-QuIC kinetic parameters and the highest proportion of samples with 4 out of 4 positive replicates. In DLB patients, 100% with GBA mutations showed positive α-Syn seeding compared to 79% of wildtype DLB. Moreover, we found an association between α-Syn seeding activity and reduced CSF levels of proteins linked to α-Syn proteostasis, specifically lysosome-associated membrane glycoprotein 2 and neurosecretory protein VGF.These findings highlight the value of α-Syn seeding activity as an in-vivo marker of Lewy-body pathology and support its use for patient stratification in clinical trials targeting α-Syn.

Gut Microbiome Signatures of Risk and Prodromal Markers of Parkinson Disease.

OBJECTIVE: Alterations of the gut microbiome in Parkinson disease (PD) have been repeatedly demonstrated. However, little is known about whether such alterations precede disease onset and how they relate to risk and prodromal markers of PD. We investigated associations of these features with gut microbiome composition. METHODS: Established risk and prodromal markers of PD as well as factors related to diet/lifestyle, bowel function, and medication were studied in relation to bacterial α-/ß-diversity, enterotypes, and differential abundance in stool samples of 666 elderly TREND (Tübingen Evaluation of Risk Factors for Early Detection of Neurodegeneration) study participants. RESULTS: Among risk and prodromal markers, physical inactivity, occupational solvent exposure, and constipation showed associations with α-diversity. Physical inactivity, sex, constipation, possible rapid eye movement sleep behavior disorder (RBD), and smoking were associated with ß-diversity. Subthreshold parkinsonism and physical inactivity showed an interaction effect. Among other factors, age and urate-lowering medication were associated with α- and ß-diversity. Constipation was highest in individuals with the Firmicutes-enriched enterotype, and physical inactivity was most frequent in the Bacteroides-enriched enterotype. Constipation was lowest and subthreshold parkinsonism least frequent in individuals with the Prevotella-enriched enterotype. Differentially abundant taxa were linked to constipation, physical inactivity, possible RBD, smoking, and subthreshold parkinsonism. Substantia nigra hyperechogenicity, olfactory loss, depression, orthostatic hypotension, urinary/erectile dysfunction, PD family history, and the prodromal PD probability showed no significant microbiome associations. INTERPRETATION: Several risk and prodromal markers of PD are associated with gut microbiome composition. However, the impact of the gut microbiome on PD risk and potential microbiome-dependent subtypes in the prodrome of PD need further investigation based on prospective clinical and (multi)omics data in incident PD cases. ANN NEUROL 2021;90:E1-E12.

α-Synuclein in Plasma-Derived Extracellular Vesicles Is a Potential Biomarker of Parkinson's Disease.

BACKGROUND: Extracellular vesicles are small vesicles that are released from many cells, including neurons. α-Synuclein has recently been described in extracellular vesicles derived from the central nervous system and may contribute to the spreading of disease pathology in α-synuclein-related neurodegeneration. OBJECTIVES: We aimed to examine the potential diagnostic value of α-synuclein in plasma extracellular vesicles from patients with Parkinson's disease (PD). METHODS: Preanalytical variables were studied to establish an optimized assay for preparation of plasma extracellular vesicles and detection of extracellular vesicle-derived α-synuclein. Plasma samples were obtained from 2 independent cohorts. The Tübingen cohort contained 96 patients with PD, 50 patients with dementia with Lewy bodies, 50 patients with progressive supranuclear palsy (PSP), and 42 healthy controls; the Kassel cohort included 47 patients with PD, 43 patients with dementia with Lewy bodies, and 36 controls with secondary parkinsonian syndromes. Extracellular vesicles were prepared from total plasma by size exclusion chromatography and quantified by nanoparticle tracking analysis, α-synuclein content was measured by an electrochemiluminescence assay. RESULTS: α-Synuclein concentration in plasma extracellular vesicles provided the best discrimination between PD, dementia with Lewy bodies, PSP, and healthy controls, with an area under the curve of 0.804 (PD vs dementia with Lewy bodies), 0.815 (PD vs. PSP), and 0.769 (PD vs healthy controls) in the Tübingen cohort. Results were validated in the Kassel cohort. CONCLUSIONS: The concentration of α-synuclein in plasma extracellular vesicles may serve as a potential diagnostic biomarker for PD. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

The Mutation Matters: CSF Profiles of GCase, Sphingolipids, α-Synuclein in PDGBA.

BACKGROUND: With pathway-specific trials in PD associated with variants in the glucocerebrosidase gene (PDGBA ) under way, we need markers that confirm the impact of genetic variants in patient-derived biofluids in order to allow patient stratification merely based on genetics and that might serve as biochemical read-out for target engagement. OBJECTIVE: To explore GBA-pathway-specific biomarker profiles cross-sectionally (TUEPAC-MIGAP, PPMI) and longitudinally (PPMI). METHODS: We measured enzyme activity of the lysosomal glucocerebrosidase, CSF levels of glucosylceramides (upstream substrate of glucocerebrosidase), CSF levels of ceramides (downstream product of glucocerebrosidase), lactosylceramides, sphingosines, sphingomyelin (by-products) and CSF levels of total α-synuclein in PDGBA patients compared to PDGBA_wildtype patients. RESULTS: Cross-sectionally in both cohorts and longitudinally in PPMI: (1) glucocerebrosidase activity was significantly lower in PDGBA compared to PDGBA_wildtype . (2) CSF levels of upstream substrates (glucosylceramides species) were higher in PDGBA compared to PDGBA_wildtype . (3) CSF levels of total α-synuclein were lower in PDGBA compared to PDGBA_wildtype . All of these findings were most pronounced in PDGBA with severe mutations (PDGBA_severe ). Cross-sectionally in TUEPAC-MIGAP and longitudinally in PPMI, CSF levels of downstream-products (ceramides) were higher in PDGBA_severe . Cross-sectionally in TUEPAC-MIGAP by-products sphinganine and sphingosine-1-phosphate and longitudinally in PPMI species of by-products lactosylceramides and sphingomyelin were higher in PDGBA_severe . INTERPRETATION: These findings confirm that GBA mutations have a relevant functional impact on biomarker profiles in patients. Bridging the gap between genetics and biochemical profiles now allows patient stratification for clinical trials merely based on mutation status. Importantly, all findings were most prominent in PDGBA with severe variants. © 2021 International Parkinson and Movement Disorder Society.

The longevity gene Klotho and its cerebrospinal fluid protein profiles as a modifier for Parkinson´s disease.

BACKGROUND: Parkinson´s disease (PD) has a large phenotypic variability, which may, at least partly, be genetically driven including alterations of gene products. Candidates might not only be proteins associated with disease risk but also pathways that play a role in aging. OBJECTIVE: To evaluate phenotype-modifying effects of genetic variants in Klotho, a longevity gene. METHODS: We analyzed two longitudinal cohorts: one local cohort comprising 459 PD patients who underwent genotyping for the KL-VS haplotype in Klotho including a subgroup of 125 PD patients and 50 healthy controls who underwent biochemical cerebrospinal fluid (CSF) analyses of Klotho and fibroblast growth factor 23 as well as vitamin D metabolites. The second cohort comprised 297 patients from the Parkinson's Progression Markers Initiative (PPMI) for validation of genetic-clinical findings. RESULTS: PD patients carrying the KL-VS haplotype demonstrated a shorter interval between PD onset and onset of cognitive impairment (both cohorts) and higher Unified Parkinson´s Disease Rating Scale part III (UPDRS III) scores (PPMI). CSF protein levels of Klotho and fibroblast growth factor 23 were lower in PD patients irrespective of gender compared to controls. Moreover, low CSF levels of Klotho were associated with higher scores in the UPDRS III and Hoehn and Yahr Scale. CONCLUSIONS: Our results indicate that genetic variants in Klotho together with its corresponding CSF protein profiles are associated with aspects of disease severity in PD. These findings suggest that pathways associated with aging might be targets for future biomarker research in PD.

Phenylalanine Effects on Brain Function in Adult Phenylketonuria.

OBJECTIVE: To evaluate the relationship between circulating phenylalanine and brain function as well as neuropsychiatric symptoms in adults with phenylketonuria. METHODS: In this prospective cross-sectional study, early-treated patients with phenylketonuria older than 30 years and age- and sex-matched controls were included. Extensive neurologic evaluation, neuropsychological and behavioral testing, sensory and motor evoked potentials, and MRI were performed. CSF concentrations of neurodegenerative markers were evaluated in addition in a subset of 10 patients. RESULTS: Nineteen patients with phenylketonuria (median age 41 years) with different phenylalanine levels (median 873 µmol/L) entered the study. They showed higher prevalence of neurologic symptoms, cognitive and behavioral abnormalities, autonomic dysfunction, alterations in neurophysiologic measures, and atrophy in putamen and right thalamus compared to controls. In CSF, patients with phenylketonuria exhibited higher ß-amyloid 1-42 (p = 0.003), total tau (p < 0.001), and phosphorylated tau (p = 0.032) levels compared to controls. Plasma phenylalanine levels highly correlated with the number of failed neuropsychological tests (r = 0.64, p = 0.003), neuropsychiatric symptoms (r = 0.73, p < 001), motor evoked potential latency (r = 0.48, p = 0.030), and parietal lobe atrophy. CONCLUSIONS: Our study provides strong evidence for a correlation between phenylalanine levels and clinical, neuropsychological, neurophysiologic, biochemical, and imaging alterations in adult patients with phenylketonuria.

Common diseases alter the physiological age-related blood microRNA profile.

Aging is a key risk factor for chronic diseases of the elderly. MicroRNAs regulate post-transcriptional gene silencing through base-pair binding on their target mRNAs. We identified nonlinear changes in age-related microRNAs by analyzing whole blood from 1334 healthy individuals. We observed a larger influence of the age as compared to the sex and provide evidence for a shift to the 5' mature form of miRNAs in healthy aging. The addition of 3059 diseased patients uncovered pan-disease and disease-specific alterations in aging profiles. Disease biomarker sets for all diseases were different between young and old patients. Computational deconvolution of whole-blood miRNAs into blood cell types suggests that cell intrinsic gene expression changes may impart greater significance than cell abundance changes to the whole blood miRNA profile. Altogether, these data provide a foundation for understanding the relationship between healthy aging and disease, and for the development of age-specific disease biomarkers.

Mitochondrial damage-associated inflammation highlights biomarkers in PRKN/PINK1 parkinsonism.

There is increasing evidence for a role of inflammation in Parkinson's disease. Recent research in murine models suggests that parkin and PINK1 deficiency leads to impaired mitophagy, which causes the release of mitochondrial DNA (mtDNA), thereby triggering inflammation. Specifically, the CGAS (cyclic GMP-AMP synthase)-STING (stimulator of interferon genes) pathway mitigates activation of the innate immune system, quantifiable as increased interleukin-6 (IL6) levels. However, the role of IL6 and circulating cell-free mtDNA in unaffected and affected individuals harbouring mutations in PRKN/PINK1 and idiopathic Parkinson's disease patients remain elusive. We investigated IL6, C-reactive protein, and circulating cell-free mtDNA in serum of 245 participants in two cohorts from tertiary movement disorder centres. We performed a hypothesis-driven rank-based statistical approach adjusting for multiple testing. We detected (i) elevated IL6 levels in patients with biallelic PRKN/PINK1 mutations compared to healthy control subjects in a German cohort, supporting the concept of a role for inflammation in PRKN/PINK1-linked Parkinson's disease. In addition, the comparison of patients with biallelic and heterozygous mutations in PRKN/PINK1 suggests a gene dosage effect. The differences in IL6 levels were validated in a second independent Italian cohort; (ii) a correlation between IL6 levels and disease duration in carriers of PRKN/PINK1 mutations, while no such association was observed for idiopathic Parkinson's disease patients. These results highlight the potential of IL6 as progression marker in Parkinson's disease due to PRKN/PINK1 mutations; (iii) increased circulating cell-free mtDNA serum levels in both patients with biallelic or with heterozygous PRKN/PINK1 mutations compared to idiopathic Parkinson's disease, which is in line with previous findings in murine models. By contrast, circulating cell-free mtDNA concentrations in unaffected heterozygous carriers of PRKN/PINK1 mutations were comparable to control levels; and (iv) that circulating cell-free mtDNA levels have good predictive potential to discriminate between idiopathic Parkinson's disease and Parkinson's disease linked to heterozygous PRKN/PINK1 mutations, providing functional evidence for a role of heterozygous mutations in PRKN or PINK1 as Parkinson's disease risk factor. Taken together, our study further implicates inflammation due to impaired mitophagy and subsequent mtDNA release in the pathogenesis of PRKN/PINK1-linked Parkinson's disease. In individuals carrying mutations in PRKN/PINK1, IL6 and circulating cell-free mtDNA levels may serve as markers of Parkinson's disease state and progression, respectively. Finally, our study suggests that targeting the immune system with anti-inflammatory medication holds the potential to influence the disease course of Parkinson's disease, at least in this subset of patients.

Gut Microbiome Signatures of Risk and Prodromal Markers of Parkinson Disease.

OBJECTIVE: Alterations of the gut microbiome in Parkinson disease (PD) have been repeatedly demonstrated. However, little is known about whether such alterations precede disease onset and how they relate to risk and prodromal markers of PD. We investigated associations of these features with gut microbiome composition. METHODS: Established risk and prodromal markers of PD as well as factors related to diet/lifestyle, bowel function, and medication were studied in relation to bacterial α-/ß-diversity, enterotypes, and differential abundance in stool samples of 666 elderly TREND (Tübingen Evaluation of Risk Factors for Early Detection of Neurodegeneration) study participants. RESULTS: Among risk and prodromal markers, physical activity, occupational solvent exposure, and constipation showed associations with α-diversity. Physical activity, sex, constipation, possible rapid eye movement sleep behavior disorder (RBD), and smoking were associated with ß-diversity. Subthreshold parkinsonism and physical activity showed an interaction effect. Among other factors, age and urate-lowering medication were associated with α- and ß-diversity. Physical inactivity and constipation were highest in individuals with the Firmicutes-enriched enterotype. Constipation was lowest and subthreshold parkinsonism least frequent in individuals with the Prevotella-enriched enterotype. Differentially abundant taxa were linked to constipation, physical activity, possible RBD, smoking, and subthreshold parkinsonism. Substantia nigra hyperechogenicity, olfactory loss, depression, orthostatic hypotension, urinary/erectile dysfunction, PD family history, and the prodromal PD probability showed no significant microbiome associations. INTERPRETATION: Several risk and prodromal markers of PD are associated with gut microbiome composition. However, the impact of the gut microbiome on PD risk and potential microbiome-dependent subtypes in the prodrome of PD need further investigation based on prospective clinical and (multi)omics data in incident PD cases. ANN NEUROL 2020;88:320-331.

CSF NFL in a Longitudinally Assessed PD Cohort: Age Effects and Cognitive Trajectories.

BACKGROUND: Neurofilament light protein is an unspecific biofluid marker that reflects the extent of neuronal/axonal damage and thereby offers the chance monitor disease severity and progression. The objective of this study was to investigate cerebrospinal fluid (CSF) levels of neurofilament light protein in Parkinson's disease (PD) patients with clinical trajectories of motor and cognitive function longitudinally. METHODS: CSF neurofilament light protein levels were assessed in 371 PDsporadic , 126 genetic PD patients (91 PDGBA , 8 PDLRRK2 , 21 PDPRKN/PINK1/DJ1_heterozygous , 6 PDPRKN/PINK1/DJ1_homozygous ), and 71 healthy controls. Participants were followed up longitudinally for up to 8 years. RESULTS: At baseline, mean CSF neurofilament light protein levels were highest in PD patients with cognitive impairment (Montreal Cognitive Assessment score ≤ 25; 1207 pg/mL) but also higher in PD patients with normal cognitive function (757 pg/mL) compared with healthy controls (593 pg/mL; P ≤ 0.001). In healthy controls and in PD patients older age was associated with higher CSF levels of neurofilament light protein (P ≤ 0.001). In PD patients, male gender, older age at onset, longer disease duration, higher Hoehn and Yahr stages, higher UPDRS-III scores, and lower Montreal Cognitive Assessment scores were associated with higher CSF levels of neurofilament light protein (P < 0.01). In patients who developed cognitive impairment during study, CSF neurofilament light protein levels prior to conversion to cognitive impairment were not significantly different compared with CSF neurofilament light protein levels of patients who remained cognitively normal. CONCLUSIONS: Increased CSF levels of neurofilament light protein are associated with cognitive decline and motor impairment in PD. However, this increase seems not a very early event and does not mark the conversion to cognitive impairment beforehand. Therefore, the predictive value needs to be discussed critically. © 2020 International Parkinson and Movement Disorder Society.

Intraindividual Neurofilament Dynamics in Serum Mark the Conversion to Sporadic Parkinson's Disease.

BACKGROUND AND OBJECTIVES: With disease-modifying treatment strategies on the horizon, stratification of individual patients at the earliest stages of Parkinson's disease (PD) is key-ideally already at clinical disease onset. Blood levels of neurofilament light chain (NfL) provide an easily accessible fluid biomarker that might allow capturing the conversion from prodromal to manifest PD. METHODS: We assessed longitudinal serum NfL levels in subjects converting from prodromal to manifest sporadic PD (converters), at-risk subjects, and matched controls (72 participants with ≈4 visits), using single-molecule array (Simoa) technique. RESULTS: While NfL levels were not increased at the prodromal stage, subjects converting to the manifest motor stage showed a significant intraindividual acceleration of the age-dependent increase of NfL levels. CONCLUSIONS: The temporal dynamics of intraindividual NfL blood levels might mark the conversion to clinically manifest PD, providing a potential stratification biomarker for individual disease onset in the advent of precision medicine for PD. © 2020 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.