α‐Synuclein in blood cells differentiates Parkinson’s disease from healthy controls (original) (raw)
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Scientific Reports, 2015
A marker for diagnosis of Parkinson’s disease (PD), which reflects on the occurrence of peripheral pathogenic mechanisms, would potentially improve therapy. The significance of α-Synuclein (α-Syn) expression in red blood cells (RBC) is currently unclear. Here we investigated whether RBC’s-expressed α-Syn may associate with PD. To this aim, we determined the levels of total and proteinase K-resistant α-Syn in samples of packed red blood cells (PRBCs). Twenty-one individuals with PD at various disease stages and 15 healthy controls, with similar demographic features, were recruited to this study. α-Syn levels were determined by their biochemical property to bind phospholipids, using a phospholipid-ELISA assay. A significantly lower ratio of total-to-proteinase K-resistant α-Syn levels was detected in PD patients than in the healthy control group. However, there was considerable overlap between the two groups. Suggesting a need for additional markers to be tested in combination with α-...
Scientific reports, 2017
Parkinson's disease (PD) is a progressive neurodegenerative disorder known for the typical motor features associated. Pathologically, it is characterized by the intracellular accumulation of alpha-synuclein (aSyn) in Lewy bodies and Lewy neurites. Currently, there are no established biochemical markers for diagnosing or for following disease progression, a major limitation for the clinical practice. Posttranslational modifications (PTMs) in aSyn have been identified and implicated on its pathobiology. Since aSyn is abundant in blood erythrocytes, we aimed to evaluate whether PTMs of aSyn in the blood might hold value as a biomarker for PD. We examined 58 patients with PD and 30 healthy age-matched individuals. We found that the levels of Y125 phosphorylated, Y39 nitrated, and glycated aSyn were increased in PD, while those of SUMO were reduced. A combinatory analysis of the levels of these PTMs resulted in an increased sensitivity, with an area under curve (AUC) of 0.843 for PD ...
The FASEB journal, 2006
To date there is no accepted clinical diagnostic test for Parkinson's disease (PD) based on biochemical analysis of blood or cerebrospinal fluid (CSF). ␣-Synuclein (␣-syn) protein has been linked to the pathogenesis of PD with the discovery of mutations in the gene encoding ␣-syn in familial cases with early-onset PD. Lewy bodies and Lewy neurites, which constitute the main pathological features in the brains of patients with sporadic PD and dementia with Lewy bodies, are formed by the conversion of soluble monomers of ␣-syn into insoluble aggregates. We recently reported the presence of ␣-syn in normal human blood plasma and in postmortem CSF. Here, we investigated whether ␣-syn can be used as a biomarker for PD. We have developed a novel ELISA method that detects only oligomeric "soluble aggregates" of ␣-syn. Using this ELISA, we report the presence of significantly elevated
The FASEB Journal, 2006
To date there is no accepted clinical diagnostic test for Parkinson's disease (PD) based on biochemical analysis of blood or cerebrospinal fluid (CSF). ␣-Synuclein (␣-syn) protein has been linked to the pathogenesis of PD with the discovery of mutations in the gene encoding ␣-syn in familial cases with early-onset PD. Lewy bodies and Lewy neurites, which constitute the main pathological features in the brains of patients with sporadic PD and dementia with Lewy bodies, are formed by the conversion of soluble monomers of ␣-syn into insoluble aggregates. We recently reported the presence of ␣-syn in normal human blood plasma and in postmortem CSF. Here, we investigated whether ␣-syn can be used as a biomarker for PD. We have developed a novel ELISA method that detects only oligomeric "soluble aggregates" of ␣-syn. Using this ELISA, we report the presence of significantly elevated
The FASEB Journal, 2006
To date there is no accepted clinical diagnostic test for Parkinson's disease (PD) based on biochemical analysis of blood or cerebrospinal fluid (CSF). ␣-Synuclein (␣-syn) protein has been linked to the pathogenesis of PD with the discovery of mutations in the gene encoding ␣-syn in familial cases with early-onset PD. Lewy bodies and Lewy neurites, which constitute the main pathological features in the brains of patients with sporadic PD and dementia with Lewy bodies, are formed by the conversion of soluble monomers of ␣-syn into insoluble aggregates. We recently reported the presence of ␣-syn in normal human blood plasma and in postmortem CSF. Here, we investigated whether ␣-syn can be used as a biomarker for PD. We have developed a novel ELISA method that detects only oligomeric "soluble aggregates" of ␣-syn. Using this ELISA, we report the presence of significantly elevated (P)200.0؍ levels of oligomeric forms of ␣-syn in plasma samples obtained from 34 PD patients compared with 27 controls; 52% (95% confidence intervals 0.353-0.687) of the PD patients displayed signals >0.5 OD with our ELISA assay in comparison to only 14.8% (95% confidence intervals 0.014-0.281) for the control cases. An analysis of the test's diagnostic value revealed a specificity of 0.852 (95% confidence intervals 0.662-0.958), sensitivity of 0.529 (95% confidence intervals 0.351-0.702) and a positive predictive value of 0.818 (95% confidence intervals 0.597-0.948). These observations offer new opportunities for developing diagnostic tests for PD and related diseases and for testing therapeutic agents aimed at preventing or reversing the aggregation of ␣-syn.-El-Agnaf, O. M. A., Salem, S. A.,
Plasma α-synuclein is decreased in subjects with Parkinson's disease
Experimental Neurology, 2007
α-Synuclein (αSN) is implicated in Parkinson's disease (PD) and is the major component of Lewy bodies (LBs). Although αSN is mainly expressed in neuronal cells and exists as a cytoplasmic protein, it has been found in body fluids including cerebrospinal fluid and blood. This study explored plasma αSN as a diagnostic marker for PD. Western blot analysis was used to characterize plasma αSN compared to brain αSN. Plasma αSN of 16 kDa migrates with the same mobility as its brain counterpart and recombinant αSN on denatured polyacrylamide gels and reacted with three different antibodies against the C-terminal and NAC regions of the αSN protein. The αSN levels in plasma from PD subjects are significantly lower than that in age-matched controls (p = 0.001), and the αSN levels in patients with early-onset PD are lower than that in both late-onset PD and controls. This initial study indicates that measurement of αSN in plasma can provide support for a clinical diagnosis of Parkinson's disease and warrants further study in a larger population.
Parkinson’s disease biomarkers based on α‐synuclein
Journal of Neurochemistry, 2019
Parkinson's disease is the second most common neurodegenerative disorder after Alzheimer's disease and is estimated to affect approximately 1-4% of individuals aged over 60 years old. Although considerable efforts have been invested into developing disease-modifying therapies for Parkinson's disease, such efforts have been confounded by the difficulty in accurately diagnosing Parkinson's disease during life to enable accurate patient stratification for clinical trialling of candidate therapeutics. Therefore, the search for effective biomarkers that can be accurately evaluated during life with non-invasive means is a pressing issue in the field. Since the discovery of α-synuclein as a protein linked to a familial form of Parkinson's disease, later identified as the major protein component of the neuropathological hallmark of idiopathic Parkinson's disease, considerable interest has focused on this protein and its distinct conformers. We describe here the progress that has been made in the area of Parkinson's disease biomarker discovery with a focus on α-synuclein. In particular, we highlight the novel assays that have been employed and the increasing complexity in evaluating α-synuclein with regard to the considerable diversity of conformers that exist in the biofluids and peripheral tissues under disease conditions. Abbreviations used α-syn-alpha-synuclein CSF-cerebrospinal fluid DATATOP-Deprenyl and tocopherol antioxidative therapy of parkinsonism DeNoPA-De novo parkinson's disease DLB-dementia with lewy bodies ELISA-enzyme linked immunosorbent assay LB-Lewy body o-α-syn-oligomeric α-syn PD-Parkinson's disease PMCA-protein misfolding cyclic amplification PPMI-Parkinson's progression markers initiative pS129 α-syn-phosphorylated α-syn at S129 PSP-progressive supranuclear palsy RT-QuIC-real-time quaking-induced conversion
Alpha-Synuclein as a Biomarker of Parkinson’s Disease: Good, but Not Good Enough
Frontiers in Aging Neuroscience
Parkinson’s disease (PD) is the second most common neurodegenerative disorder of the elderly, presenting primarily with symptoms of motor impairment. The disease is diagnosed most commonly by clinical examination with a great degree of accuracy in specialized centers. However, in some cases, non-classical presentations occur when it may be difficult to distinguish the disease from other types of degenerative or non-degenerative movement disorders with overlapping symptoms. The diagnostic difficulty may also arise in patients at the early stage of PD. Thus, a biomarker could help clinicians circumvent such problems and help them monitor the improvement in disease pathology during anti-parkinsonian drug trials. This review first provides a brief overview of PD, emphasizing, in the process, the important role of α-synuclein in the pathogenesis of the disease. Various attempts made by the researchers to develop imaging, genetic, and various biochemical biomarkers for PD are then briefly...
Parkinson's disease (PD) is a progressive neurodegenerative disorder known for the typical motor features associated. Pathologically, it is characterized by the intracellular accumulation of alpha-synuclein (aSyn) in Lewy bodies and Lewy neurites. Currently, there are no established biochemical markers for diagnosing or for following disease progression, a major limitation for the clinical practice. Posttranslational modifications (PTMs) in aSyn have been identified and implicated on its pathobiology. Since aSyn is abundant in blood erythrocytes, we aimed to evaluate whether PTMs of aSyn in the blood might hold value as a biomarker for PD. We examined 58 patients with PD and 30 healthy age-matched individuals. We found that the levels of Y125 phosphorylated, Y39 nitrated, and glycated aSyn were increased in PD, while those of SUMO were reduced. A combinatory analysis of the levels of these PTMs resulted in an increased sensitivity, with an area under curve (AUC) of 0.843 for PD versus healthy controls, and correlated with disease severity and duration. We conclude that the levels of these selected PTMs hold strong potential as biochemical markers for PD. Ultimately, our findings might facilitate the monitoring of disease progression in clinical trials, opening the possibility for developing more effective therapies against PD. Parkinson's disease (PD) is the second most common progressive neurodegenerative disorder affecting 1–2% of people over the age of 65 years 1. The diagnosis of PD is currently based on typical clinical motor features, such as bradykinesia, resting tremor, or rigidity 2. The response to levodopa treatment represents an important factor for diagnosis, since PD patients usually present a good response to this medication 3. Different clinical scales are routinely used to classify and stage the disease. The Movement Disorder Society (MDS) recently revised the Unified PD Rating Scale (MDS-UPDRS), which is subdivided into four components 4. Parts I and II are associated to the non-motor and motor experiences of everyday, while part III is reserved to the motor evaluation and finally Part IV is related to motor complications 5. The Hoehn and Yahr (HY) scale is divided into 5 stages that reflect motor progression of the disease 6. However, misdiagnosis of PD is rather common 7,8 , affecting therapeutics and complicating patient selection for clinical trials. Thus, it is urgent to identify novel and objective biomarkers to unequivocally diagnose and follow disease progression. Pathologically, PD is characterized by the loss of nigrostriatal dopaminergic neurons and the accumulation of neuronal cytoplasmic inclusions known as Lewy bodies (LBs) or Lewy neurites, which are primarily composed of the protein alpha-synuclein (aSyn) 9. The majority of PD cases are sporadic, however several genes have been associated with familial cases 10. Mutations and multiplications in the gene encoding for aSyn are also associated with familial forms of PD 11. Interestingly, in both sporadic and familial forms of PD the progression and severity of the disease correlate with the distribution of aSyn inclusions 12. For reasons we still do not fully understand, aSyn is prone to misfolding and self-association into high molecular weight species, ultimately forming LBs 13. Posttranslational modifications (PTMs) have a direct impact in the aggregation and toxicity of aSyn. The protein undergoes several PTMs such as acetylation and glycation, as we recently described 14,15 , as well as oxidation, phosphorylation, nitration, sumoylation, and ubiquitination 16–18. We showed that while acetylation protects from aSyn aggregation and toxicity 14 , glycation exacerbates oligomeriza-tion and cytotoxicity, inducing dopaminergic neuronal death 15. Phosphorylation has been extensively studied PTM since most aSyn found in LBs is phosphorylated on serine 129 19,20. However, the effects of S129 phosphoryl-ation are still controversial 21–25. Other modifications, such as nitration 26 and oxidation 27 enhance, while sumoyla-tion 28 prevents/reduces the aggregation of aSyn. Nevertheless, although PTMs may play important roles on aSyn biology, our understanding of the precise effects of PTMs on aSyn is still limited. aSyn is present in various body fluids such as cerebrospinal fluid (CSF) and blood 29,30. Thus, the presence of this protein in easily-accessible body fluids opens the possibility of investigating PTMs in aSyn. Taking advantage of the thermo-stability of aSyn 31 , we detected PTMs in aSyn extracted from brain tissue or from cultured cells 14,15,32. Although the pool of aSyn in the blood may differ from that in the brain or CSF, we hypothesized that, given the central role this protein plays in PD, it might report on disease-related alterations that may be used as bio-markers for PD. This is in line with the observation that aSyn can be secreted from neuronal cells 33 , and that it is phosphorylated on serine 129 in the serum of PD patients 34. In this study, we identified a specific pattern of aSyn PTMs that discriminated PD patients from controls individuals. As these PTMs correlate with disease severity and duration, we propose that these modifications may possibly be used as biochemical markers for PD. Results Patient population and demographics. We recruited a group of 88 individuals, divided into 3 subgroups: 28 diagnosed with PD for 2–4 years, 30 diagnosed for ≥10 years, and 30 controls. Blood samples were processed by the same personnel. The PD group diagnosed with the disease for 2–4 years presented a male to female (M:F) ratio of 1: 1, a mean age at onset of 69.0 ± 10.3 years, a mean disease duration of 3.1 ± 0.7 years, a MDS-UPDRS III of 38.4 ± 10.8 and a HY of 1.6 ± 0.8. The PD group diagnosed for ≥10 years presented a M:F ratio of 1: 1, a mean age of onset of 67.2 ± 7.6 years, a mean disease duration of 17.7 ± 4.3, a MDS-UPDRS III of 60.0 ± 19.9 and a HY of 3.0 ± 1.1. The mean age of controls was 67.2 ± 7.6 years. Male to female ratio in the control group was 1:2 (Table 1 and Fig. S1). aSyn purification and enrichment. To analyse PTMs of aSyn in blood, we first enriched the aSyn content from erythrocyte lysates taking advantage of the thermo-stability of aSyn, as previously described 32. Briefly, as described in Fig. 1a–d, by heating protein samples, non-thermo-stable proteins precipitated, while aSyn remained in the soluble fraction, enabling its detection (Fig. 1b–d). As haemoglobin is the major protein component of erythrocytes lysates (90%), we depleted this protein from thermo-enriched erythrocyte lysates using HemoVoid, a silica-based protein enrichment matrix that removes haemoglobin from lysates, enabling the additional concentration of other proteins of lower abundance 35. We confirmed the aSyn enrichment by immunoblotting (SDS-PAGE and dot-blot) (Fig. 1c,d). Thus, for all subsequent analysis, the erythrocyte fractions were thermo-enriched and haemoglobin depleted. Although the amount of haemoglobin is severely reduced in thermo-enriched-haemoglobin-depleted (TE-HD) extracts, and a band at 15 kDa is evident, other higher molecular weight bands are also observed (Fig. 1b).
CSF α-synuclein does not differentiate between parkinsonian disorders
Neurobiology of Aging, 2012
Differentiating between Parkinson's disease (PD) and atypical Parkinsonism (AP) is clinically relevant but challenging. A timely and correct diagnosis might result in better targeted treatment strategies, adequate patient counseling, and early recognition of disease-specific complications. We aimed to investigate whether cerebrospinal fluid (CSF) concentrations of ␣-synuclein are of additional diagnostic value. We examined 142 consecutive patients with parkinsonism, mean disease duration 39.7 mo (Parkinson's disease (PD), n ϭ 58; MSA, n ϭ 47; dementia with Lewy bodies (DLB), n ϭ 3; VaP, n ϭ 22; progressive supranuclear palsy (PSP), n ϭ 10; CBD, n ϭ 2). Gold standard was the clinical diagnosis established after 2 years of clinical follow-up. CSF concentrations of ␣-synuclein, blood pigments and the erythrocyte count were determined. No differences between CSF ␣-synuclein concentrations of patients with PD with the reference values from our laboratory were observed. We neither found significant differences between patients with PD and AP nor between AP subgroups. Adjustment for age, disease severity or presence of erythrocytes or blood pigments in CSF did not alter these results. Our results imply that CSF ␣-synuclein is currently unsuitable as biomarker to differentiate between PD and AP.