Differential pattern of brain-specific CSF proteins tau and amyloid-beta in Parkinsonian syndromes

Head-to-head comparison of 6 plasma biomarkers in early multiple system atrophy

There is a dire need for reliable biomarkers to solidify an early and accurate diagnosis of multiple system atrophy (MSA). We sought to compare the ability of emerging plasma markers in distinguishing MSA from its mimics and healthy controls in early disease stages, and to evaluate their performance in detecting disease severity and brain atrophy. Plasma neurofilament light (NfL), glial fibrillary acidic protein (GFAP), phosphorylated tau181, amyloid-β (Aβ)42, and Aβ40 were measured using ultrasensitive Simoa in early-stage patients with MSA (n = 73), spinocerebellar ataxia (SCA, n = 29), Parkinson's disease (PD, n = 28), and healthy controls (n = 100). We observed that elevated NfL outperformed other biomarkers in distinguishing MSA and its subtypes (AUC = 0.9) versus controls. Intriguingly, when separating MSA from its mimics, increased GFAP (AUC = 0.717) in MSA-C and decreased Aβ40 (AUC = 0.807) in MSA-P best discriminated from SCA and PD respectively. Plasma levels were comparable between MSA-C and MSA-P and the differentiation by plasma index alone was poor. Combining plasma markers noticeably improved the discriminatory efficacy. Of note, among MSA patients, higher GFAP and NfL were correlated with the atrophy of brain regions vulnerable to MSA (e.g., cerebellum, pons, or putamen). They could also aggravate the severity of MSA, and this association was partially mediated by cerebral volumes. In contrast, no obvious associations of phosphorylated tau and Aβ with disease severity were observed. Collectively, plasma biomarkers, especially in combination, are useful to facilitate the discriminatory work-up of MSA at early stages. Moreover, NfL and GFAP may be promising biomarkers to monitor the disease severity of MSA.

Nanodelivery of Histamine H3/H4 Receptor Modulators BF-2649 and Clobenpropit with Antibodies to Amyloid Beta Peptide in Combination with Alpha Synuclein Reduces Brain Pathology in Parkinson's Disease

Parkinson's disease (PD) in military personnel engaged in combat operations is likely to develop in their later lives. In order to enhance the quality of lives of PD patients, exploration of novel therapy based on new research strategies is highly warranted. The hallmarks of PD include increased alpha synuclein (ASNC) and phosphorylated tau (p-tau) in the cerebrospinal fluid (CSF) leading to brain pathology. In addition, there are evidences showing increased histaminergic nerve fibers in substantia niagra pars compacta (SNpc), striatum (STr), and caudate putamen (CP) associated with upregulation of histamine H3 receptors and downregulation of H4 receptors in human brain. Previous studies from our group showed that modulation of potent histaminergic H3 receptor inverse agonist BF-2549 or clobenpropit (CLBPT) partial histamine H4 agonist with H3 receptor antagonist induces neuroprotection in PD brain pathology. Recent studies show that PD also enhances amyloid beta peptide (AβP) depositions in brain. Keeping these views in consideration in this review, nanowired delivery of monoclonal antibodies to AβP together with ASNC and H3/H4 modulator drugs on PD brain pathology is discussed based on our own observations. Our investigation shows that TiO₂ nanowired BF-2649 (1 mg/kg, i.p.) or CLBPT (1 mg/kg, i.p.) once daily for 1 week together with nanowired delivery of monoclonal antibodies (mAb) to AβP and ASNC induced superior neuroprotection in PD-induced brain pathology. These observations are the first to show the modulation of histaminergic receptors together with antibodies to AβP and ASNC induces superior neuroprotection in PD. These observations open new avenues for the development of novel drug therapies for clinical strategies in PD.

The Role of Tau beyond Alzheimer’s Disease: A Narrative Review

Nowadays, there is a need for reliable fluid biomarkers to improve differential diagnosis, prognosis, and the prediction of treatment response, particularly in the management of neurogenerative diseases that display an extreme variability in clinical phenotypes. In recent years, Tau protein has been progressively recognized as a valuable neuronal biomarker in several neurological conditions, not only Alzheimer’s disease (AD). Cerebrospinal fluid and serum Tau have been extensively investigated in several neurodegenerative disorders, from classically defined proteinopathy, e.g., amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and Parkinson’s disease (PD), but also in inflammatory conditions such as multiple sclerosis (MS), as a marker of axonal damage. In MS, total Tau (t-Tau) may represent, along with other proteins, a marker with diagnostic and prognostic value. In ALS, t-Tau and, mainly, the phosphorylated-Tau/t-Tau ratio alone or integrated with transactive DNA binding protein of ~43 kDa (TDP-43), may represent a tool for both diagnosis and differential diagnosis of other motoneuron diseases or tauopathies. Evidence indicated the crucial role of the Tau protein in the pathogenesis of PD and other parkinsonian disorders. This narrative review summarizes current knowledge regarding non-AD neurodegenerative diseases and the Tau protein.

A Panel of Plasma Biomarkers for Differential Diagnosis of Parkinsonian Syndromes

Objective

The aim of our study is to explore the most reliable panel of plasma biomarkers for differential diagnosis of parkinsonian syndromes (PDSs). We selected five kinds of neurodegenerative proteins in plasma: neurofilament light chain (NfL), α-synuclein (α-syn), total tau, β-amyloid 42 (Aβ42) and β-amyloid 40 (Aβ40), and investigated the diagnostic value of these biomarkers.

Methods

A total of 99 plasma samples from patients with Parkinson’s disease (PD), multiple system atrophy (MSA), progressive supranuclear palsy, and age-matched healthy controls (HCs) were enrolled in our study. Plasma NfL, α-syn, total tau, Aβ42, and Aβ40 levels were quantified by ultrasensitive single molecule array immunoassay. We used logistic regression analyses to examine diagnostic accuracy of these plasma biomarkers. Disease severity was assessed by the modified Hoehn and Yahr staging scale, Unified Parkinson’s Disease Rating Scale part III (UPDRS III), and the Mini-Mental State Examination (MMSE), and subsequently, correlation analysis was performed.

Results

A combination of α-syn, Aβ42, Aβ40, Aβ42/40, and NfL could achieve a best diagnostic value in differentiating PDSs from HC and PD from HC, with an AUC of 0.983 and 0.977, respectively. By adding NfL to measurements of α-syn or Aβ42 or Aβ40 or Aβ42/40, the best discriminating panel was formed in differentiating atypical parkinsonian disorder (APD) and HC, and the discriminatory potential could reach a sensitivity of 100% and specificity of 100% (AUC = 1.000). For further distinguishing PD from APD, we found a combination of NfL, Aβ42, and total tau was the most reliable panel with equally high diagnostic accuracy. With respect to differentiating the subtypes of APD from one another, our results revealed that measurement of NfL, total tau, Aβ42, Aβ40, and Aβ42/40 was the best discriminating panel. Correlation analysis suggests that plasma Aβ42 levels were positively correlated to UPDRS part III scores in MSA. In terms of cognitive function, there was a relationship between plasma Aβ42/40 level and MMSE scores in patients with APD.

Conclusion

In our study, various combinations of plasma biomarkers have great potentialities in identifying PDSs, with important clinical utility in improving diagnostic accuracy. Plasma NfL may have added value to a blood-based biomarker panel for differentiating PDSs.

Systematic Assessment of 10 Biomarker Candidates Focusing on α-Synuclein-Related Disorders

BACKGROUND

Objective diagnostic biomarkers are needed to support a clinical diagnosis.

OBJECTIVES

To analyze markers in various neurodegenerative disorders to identify diagnostic biomarker candidates for mainly α-synuclein (aSyn)-related disorders (ASRD) in serum and/or cerebrospinal fluid (CSF).

METHODS

Upon initial testing of commercially available kits or published protocols for the quantification of the candidate markers, assays for the following were selected: total and phosphorylated aSyn (pS129aSyn), neurofilament light chain (NfL), phosphorylated neurofilament heavy chain (pNfH), tau protein (tau), ubiquitin C-terminal hydrolase L1 (UCHL-1), glial fibrillary acidic protein (GFAP), calcium-binding protein B (S100B), soluble triggering receptor expressed on myeloid cells 2 (sTREM-2), and chitinase-3-like protein 1 (YKL-40). The cohort comprised participants with Parkinson's disease (PD, n = 151), multiple system atrophy (MSA, n = 17), dementia with Lewy bodies (DLB, n = 45), tau protein-related neurodegenerative disorders (n = 80, comprising patients with progressive supranuclear palsy (PSP, n = 38), corticobasal syndrome (CBS, n = 16), Alzheimer's disease (AD, n = 11), and frontotemporal degeneration/amyotrophic lateral sclerosis (FTD/ALS, n = 15), as well as healthy controls (HC, n = 20). Receiver operating curves (ROC) with area under the curves (AUC) are given for each marker.

RESULTS

CSF total aSyn was decreased. NfL, pNfH, UCHL-1, GFAP, S100B, and sTREM-2 were increased in patients with neurodegenerative disease versus HC (P < 0.05). As expected, some of the markers were highest in AD (i.e., UCHL-1, GFAP, S100B, sTREM-2, YKL-40). Within ASRD, CSF NfL levels were higher in MSA than PD and DLB (P < 0.05). Comparing PD to HC, interesting serum markers were S100B (AUC: 0.86), sTREM2 (AUC: 0.87), and NfL (AUC: 0.78). CSF S100B and serum GFAP were highest in DLB.

CONCLUSIONS

Levels of most marker candidates tested in serum and CSF significantly differed between disease groups and HC. In the stratification of PD versus other tau- or aSyn-related conditions, CSF NfL levels best discriminated PD and MSA. CSF S100B and serum GFAP best discriminated PD and DLB. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson Movement Disorder Society.

Cerebrospinal Fluid Biomarkers in Multiple System Atrophy Relative to Parkinson's Disease: A Meta-Analysis

Objective

To investigate the differences of candidate cerebrospinal fluid (CSF) biomarkers associated with multiple system atrophy (MSA) and Parkinson's disease (PD).

Method

Here, a systematic review and meta-analysis were conducted on studies related to CSF biomarkers associated with MSA and PD obtained from PubMed, Web of Science, Embase, and Cochrane databases. Data were pooled where appropriate and used to calculate standardized mean differences (SMDs) with 95% confidence intervals (CI). Heterogeneity was assessed using the I² statistic while Egger's test was used to test for existing publication bias.

Results

MSA patients had higher CSF t-tau (SMD = 0.41, 95% CI: 0.10 to 0.72) and YKL-40 (SMD = 0.63, 95% CI 0.12 to1.15) as well as DJ-1 (SMD = 1.05, 95% CI 0.67 to 1.42) levels than PD patients, while CSF p-tau (SMD = −0.17, 95% CI, -0.31 to -0.02) and Aβ-42 (SMD = −0.33, 95% CI, -0.55 to -0.12) levels in MSA patients were lower than those in PD patients. There were no differences in CSF's GFAP and Flt3 ligand levels in both MSA and PD patients.

Conclusion

The study revealed the differences in CSF biomarker levels between MSA and PD cohorts that can be further explored to clinically distinguish MSA from PD.

Unraveling Pathophysiological Mechanisms of Parkinson's Disease: Contribution of CSF Biomarkers

Diagnosis of Parkinson's disease (PD) relies on clinical history and physical examination, but misdiagnosis is common in early stages. Identification of biomarkers for PD may allow for early and more precise diagnosis and provide information about prognosis. Developments in analytical chemistry allow for the detection of a large number of molecules in cerebrospinal fluid (CSF), which are known to be associated with the pathogenesis of PD. Given the pathophysiology of PD, CSF α-synuclein species have the strongest rationale for use, also providing encouraging preliminary results in terms of early diagnosis. In the field of classical Alzheimer's disease (AD) biomarkers, low CSF Aβ₄₂ levels have shown a robust prognostic value in terms of development of cognitive impairment. Other CSF biomarkers including lysosomal enzymes, neurofilament light chain, markers of neuroinflammation and oxidative stress, although promising, have not proved to be reliable for diagnostic and prognostic purposes yet. Overall, the implementation of CSF biomarkers may give a substantial contribution to the optimal use of disease-modifying drugs.

Serum Glial Fibrillary Acidic Protein (GFAP) Is a Marker of Disease Severity in Frontotemporal Lobar Degeneration

Background: It is still unknown if serum glial fibrillary acidic protein (GFAP) is a useful marker in frontotemporal lobar degeneration (FTLD). Objective: To assess the diagnostic and prognostic value of serum GFAP in a large cohort of patients with FTLD. Methods: In this retrospective study, performed on 406 participants, we measured serum GFAP concentration with an ultrasensitive Single molecule array (Simoa) method in patients with FTLD, Alzheimer’s disease (AD), and in cognitively unimpaired elderly controls. We assessed the role of GFAP as marker of disease severity by analyzing the correlation with clinical variables, neurophysiological data, and cross-sectional brain imaging. Moreover, we evaluated the role of serum GFAP as a prognostic marker of disease survival. Results: We observed significantly higher levels of serum GFAP in patients with FTLD syndromes, except progressive supranuclear palsy, compared with healthy controls, but not compared with AD patients. In FTLD, serum GFAP levels correlated with measures of cognitive dysfunction and disease severity, and were associated with indirect measures of GABAergic deficit. Serum GFAP concentration was not a significant predictor of survival. Conclusion: Serum GFAP is increased in FTLD, correlates with cognition and GABAergic deficits, and thus shows promise as a biomarker of disease severity in FTLD.

Cerebrospinal Fluid Biomarkers in Parkinson's Disease: A Critical Overview of the Literature and Meta-Analyses

Parkinson’s disease (PD) is a common neurodegenerative disorder; however, well-established biochemical markers have not yet been identified. This review article covers several candidate cerebrospinal fluid (CSF) biomarkers for PD based on the recent literature and meta-analysis data. The decrease of α-synuclein in PD is supported by meta-analyses with modest reproducibility, and a decrease of amyloid β42 is seen as a prognostic marker for cognitive decline. Tau, phosphorylated tau (p-tau), and neurofilament light chains have been used to discriminate PD from other neurodegenerative disorders. This article also describes more hopeful biochemical markers, such as neurotransmitters, oxidative stress markers, and other candidate biomarkers.

Diagnostic utility of fluid biomarkers in multiple system atrophy: a systematic review and meta-analysis

BACKGROUND

Multiple system atrophy (MSA) is an adult onset, fatal neurodegenerative disease. However, no reliable biomarker is currently available to guide clinical diagnosis and help to determine the prognosis. Thus, a comprehensive meta-analysis is warranted to determine effective biomarkers for MSA and provide useful guidance for clinical diagnosis.

METHODS

A comprehensive literature search was made of the PubMed, Embase, Cochrane and Web of Science databases for relevant clinical trial articles for 1984-2019. Two review authors examined the full-text records, respectively, and determined which studies met the inclusion criteria. We estimated the mean difference, standard deviation and 95% confidence intervals.

RESULTS

A total of 28 studies and 11 biomarkers were included in our analysis. Several biomarkers were found to be useful to distinguish MSA patients from healthy controls, including the reduction of phosphorylated tau, α-synuclein (α-syn), 42-amino-acid form of Aβ and total tau (t-tau), the elevation of neurofilament light-chain protein (NFL) in cerebrospinal fluid, the elevation of uric acid and reduction of homocysteine and coenzyme Q10 in plasma. Importantly, α-syn, NFL and t-tau could be used to distinguish MSA from Parkinson's disease (PD), indicating that these three biomarkers could be useful biomarkers in MSA diagnosis.

CONCLUSION

The findings of our meta-analysis demonstrated diagnostic biomarkers for MSA. Moreover, three biomarkers could be used in differential diagnosis of MSA and PD. The results could be helpful for the early diagnosis of MSA and the accuracy of MSA diagnosis.

The discriminative capacity of CSF β-amyloid 42 and Tau in neurodegenerative diseases in the Chinese population

INTRODUCTION

In the past few years, the β-amyloid 42 peptide and tau protein in cerebrospinal fluid (CSF) have become primary diagnostic biomarkers in differentiating Alzheimer's disease (AD) and cognitive normal controls. As we know, several neurodegenerative diseases have been reported to overlap with AD in neuropathology and clinical symptoms. To examine the discriminative utility of these biomarkers in AD and other neurodegenerative diseases, we measured them in a cohort of Chinese population.

METHODS

We measured CSF Aβ₄₂, t-tau and p-tau₁₈₁ by ELISA tests and calculated the ratios of t-tau/Aβ₄₂ and p-tau₁₈₁/Aβ₄₂ in 240 Chinese Han patients with AD (n = 82), frontotemporal dementia (FTD, n = 20), Huntington's disease (HD, n = 27), multiple system atrophy (MSA, n = 24), spinocerebellar ataxia type-3 (SCA3, n = 27), amyotrophic lateral sclerosis (ALS, n = 36) and controls (n = 24).

RESULTS

As expected, all biomarkers showed high discriminative capacity between AD and non-AD groups (p < .05) except for the elevated CSF t-tau in FTD (p > .05). Comparing with the controls, tau related biomarkers significantly elevated in the FTD (p < .001) and MSA (p < .05) groups. Surprisingly, comparing with controls, we found that CSF Aβ₄₂ increased remarkably in the SCA3 (p < .05), HD and ALS groups (p < .001), achieving a high specificity, respectively.

CONCLUSION

To our best knowledge, this is the first comprehensive study in the Han Chinese population that confirmed the discriminative utility of CSF Aβ₄₂ and tau biomarkers between AD and other neurodegenerative diseases.

Cerebrospinal fluid levels of alpha-synuclein, amyloid β, tau, phosphorylated tau, and neuron-specific enolase in patients with Parkinson's disease, dementia with Lewy bodies or other neurological disorders: Their relationships with cognition and nuclear medicine imaging findings

Parkinson's disease (PD) and dementia with Lewy bodies (DLB) are common neurodegenerative disorders, but no established biochemical markers for these diseases have been identified. We enrolled 78 subjects (27 patients with PD/DLB, 34 patients with non-PD/DLB neurodegenerative disorders [non-PD/DLB], and 17 controls). Cerebrospinal fluid (CSF) was collected via the standard lumbar puncture technique. The CSF levels of alpha-synuclein, amyloid β40, amyloid β42, tau, phosphorylated tau (p-tau), neuron-specific enolase (NSE), and hemoglobin were measured with enzyme-linked immunosorbent assays. Dopamine transporter imaging with ¹²³I-ioflupane was also performed. The PD/DLB patients exhibited significantly lower CSF alpha-synuclein levels than non-PD/DLB group. Significantly elevated CSF levels of tau, p-tau, and NSE were detected in the non-PD/DLB group. Multivariate analysis revealed that the mini-mental state examination score was correlated with the CSF amyloid β42 level. The specific binding ratio on ¹²³I-ioflupane imaging was decreased in the PD/DLB group, but it was not correlated with the CSF alpha-synuclein level. These results indicate that (1) the CSF alpha-synuclein level is a useful biomarker of PD/DLB; (2) the CSF levels of tau, p-tau, and NSE can be used to discriminate PD/DLB from non-PD/DLB; and (3) the CSF amyloid β42 level is an independent predictor of cognitive decline in neurological disorders.

Imidazoline 2 binding sites reflecting astroglia pathology in Parkinson's disease: an in vivo11C-BU99008 PET study

Astroglia are multifunctional cells that regulate neuroinflammation and maintain homeostasis within the brain. Astroglial α-synuclein-positive cytoplasmic accumulations have been shown post-mortem in patients with Parkinson's disease and therefore astroglia may play an important role in the initiation and progression of Parkinson's disease. Imidazoline 2 binding sites are expressed on activated astroglia in the cortex, hippocampus, basal ganglia and brainstem; therefore, by measuring imidazoline 2 binding site levels we can indirectly evaluate astrogliosis in patients with Parkinson's disease. Here, we aimed to evaluate the role of astroglia activation in vivo in patients with Parkinson's disease using 11C-BU99008 PET, a novel radioligand with high specificity and selectivity for imidazoline 2 binding sites. Twenty-two patients with Parkinson's disease and 14 healthy control subjects underwent 3 T MRI and a 120-min 11C-BU99008 PET scan with volume of distribution (VT) estimated using a two-tissue compartmental model with a metabolite corrected arterial plasma input function. Parkinson's disease patients were stratified into early (n = 8) and moderate/advanced (n = 14) groups according to disease stage. In early Parkinson's disease, increased 11C-BU99008 VT uptake was observed in frontal (P = 0.022), temporal (P = 0.02), parietal (P = 0.026) and occipital (P = 0.047) cortical regions compared with healthy controls. The greatest 11C-BU99008 VT increase in patients with early Parkinson's disease was observed in the brainstem (52%; P = 0.018). In patients with moderate/advanced Parkinson's disease, loss of 11C-BU99008 VT was observed across frontal (P = 0.002), temporal (P < 0.001), parietal (P = 0.039), occipital (P = 0.024), and insula (P < 0.001) cortices; and in the subcortical regions of caudate (P < 0.001), putamen (P < 0.001) and thalamus (P < 0.001); and in the brainstem (P = 0.018) compared with healthy controls. In patients with Parkinson's disease, loss of 11C-BU99008 VT in cortical regions, striatum, thalamus and brainstem correlated with longer disease duration (P < 0.05) and higher disease burden scores, measured with Movement Disorder Society Unified Parkinson's Disease Rating Scale (P < 0.05). In the subgroup of patients with moderate/advanced Parkinson's disease, loss of 11C-BU99008 VT in the frontal (r = 0.79; P = 0.001), temporal (r = 0.74; P = 0.002) and parietal (r = 0.89; P < 0.001) cortex correlated with global cognitive impairment. This study demonstrates in vivo the role of astroglia in the initiation and progression of Parkinson's disease. Reactive astroglia observed early in Parkinson's disease could reflect a neuroprotective compensatory mechanisms and pro-inflammatory upregulation in response to α-synuclein accumulation. However, as the disease progresses and significant neurodegeneration occurs, astroglia lose their reactive function and such loss in the cortex has clinical relevance in the development of cognitive impairment.

Corticobasal degeneration and corticobasal syndrome: A review

Corticobasal degeneration (CBD) is a rare neurodegenerative disorder. The most common presentation of CBD is the corticobasal syndrome (CBS), which is a constellation of cortical and extrapyramidal symptoms and signs. Clinical-pathological studies have illustrated that CBD can present with diverse clinical phenotypes, including a non-fluent, agrammatic primary progressive aphasia syndrome, a behavioral, dysexecutive and visuospatial syndrome, as well as a progressive supranuclear palsy-like syndrome. Conversely, multiple pathologies, such as CBD, Alzheimer's disease and progressive supranuclear palsy may underlie a patient with CBS. This clinical-pathological overlap emphasizes the need for biomarkers that will assist in the accurate diagnosis of patients with CBS. This review presents an overview of the pathological, genetic, clinical and therapeutic characteristics of CBD, with an emphasis on the imaging (structural and functional) and biochemical (cerebrospinal fluid) biomarkers of CBD.

Plasma Biomarkers Differentiate Parkinson's Disease From Atypical Parkinsonism Syndromes

Objective: Parkinson’s disease (PD) has significant clinical overlaps with atypical parkinsonism syndromes (APS), which have a poorer treatment response and a more aggressive course than PD. We aimed to identify plasma biomarkers to differentiate PD from APS.

Methods: Plasma samples (n = 204) were obtained from healthy controls and from patients with PD, dementia with Lewy bodies (DLB), multiple system atrophy, progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), or frontotemporal dementia (FTD) with parkinsonism (FTD-P) or without parkinsonism. We measured plasma levels of α-synuclein, total tau, p-Tau181, and amyloid beta 42 (Aβ42) by immunomagnetic reduction-based immunoassay.

Results: Plasma α-synuclein level was significantly increased in patients with PD and APS when compared with controls and FTD without parkinsonism (p < 0.01). Total tau and p-Tau181 were significantly increased in all disease groups compared to controls, especially in patients with FTD (p < 0.01). A multivariate and receiver operating characteristic curve analysis revealed that a cut-off value for Aβ42 multiplied by p-Tau181 for discriminating patients with FTD from patients with PD and APS was 92.66 (pg/ml)², with an area under the curve (AUC) of 0.932. An α-synuclein cut-off of 0.1977 pg/ml could separate FTD-P from FTD without parkinsonism (AUC 0.947). In patients with predominant parkinsonism, an α-synuclein cut-off of 1.388 pg/ml differentiated patients with PD from those with APS (AUC 0.87).

Conclusion: Our results suggest that integrated plasma biomarkers improve the differential diagnosis of PD from APS (PSP, CBD, DLB, and FTD-P).

Tracking and predicting disease progression in progressive supranuclear palsy: CSF and blood biomarkers

Progressive supranuclear palsy (PSP) is a rare and progressive neurodegenerative condition characterised pathologically by neuronal cell loss due to abnormal tau deposits. Clinically, the condition manifests as parkinsonism with the addition of progressive balance, speech, swallowing, eye movement and cognitive impairment, ultimately leading to death. Measuring change over time in neurodegenerative conditions is central to defining the effects of therapeutic intervention and disease biology. The current gold standard for measuring clinical disease progression in PSP is the PSP Rating Scale score. However, such scales may be affected by intrarater and inter-rater variability. In addition, their use in clinical trials may be hindered by differences in the time interval between pathological disease progression/response to therapeutics and change in clinical state. Therefore, the need for reliable disease progression biomarkers to complement clinical rating scales is clear. Here we discuss the benefits of using biomarkers to predict and track disease progression in both clinical and research settings. Through reviewing the literature to date on the role of cerebrospinal fluid (CSF) and blood biomarkers, we highlight data that reveals the ability of CSF and plasma neurofilament light chain (NF-L) to predict and track clinical disease progression in PSP. We also discuss the need for large-scale longitudinal studies to identify novel biomarkers.

Cerebrospinal fluid biomarkers for Parkinson's disease - a systematic review

Diagnosis of Parkinson's disease (PD) relies on clinical history and physical examination, but misdiagnosis is common in early stages. Identification of biomarkers for PD may allow early and more precise diagnosis and monitoring of dopamine replacement strategies and disease modifying treatments. Developments in analytical chemistry allow the detection of large numbers of molecules in plasma or cerebrospinal fluid, associated with the pathophysiology or pathogenesis of PD. This systematic review includes cerebrospinal fluid biomarker studies focusing on different disease pathways: oxidative stress, neuroinflammation, lysosomal dysfunction and proteins involved in PD and other neurodegenerative disorders, focusing on four clinical domains: their ability to (1) distinguish PD from healthy subjects and other neurodegenerative disorders as well as their relation to (2) disease duration after initial diagnosis, (3) severity of disease (motor symptoms) and (4) cognitive dysfunction. Oligomeric alpha-synuclein might be helpful in the separation of PD from controls. Through metabolomics, changes in purine and tryptophan metabolism have been discovered in patients with PD. Neurofilament light chain (NfL) has a significant role in distinguishing PD from other neurodegenerative diseases. Several oxidative stress markers are related to disease severity, with the antioxidant urate also having a prognostic value in terms of disease severity. Increased levels of amyloid and tau-proteins correlate with cognitive decline and may have prognostic value for cognitive deficits in PD. In the future, larger longitudinal studies, corroborating previous research on viable biomarker candidates or using metabolomics identifying a vast amount of potential biomarkers, could be a good approach.

Biomarkers in Sporadic and Familial Alzheimer's Disease

Most forms of Alzheimer's disease (AD) are sporadic (sAD) or inherited in a non-Mendelian fashion, and less than 1% of cases are autosomal-dominant. Forms of sAD do not exhibit familial aggregation and are characterized by complex genetic and environmental interactions. Recently, the expansion of genomic methodologies, in association with substantially larger combined cohorts, has resulted in various genome-wide association studies that have identified several novel genetic associations of AD. Currently, the most effective methods for establishing the diagnosis of AD are defined by multi-modal pathways, starting with clinical and neuropsychological assessment, cerebrospinal fluid (CSF) analysis, and brain-imaging procedures, all of which have significant cost- and access-to-care barriers. Consequently, research efforts have focused on the development and validation of non-invasive and generalizable blood-based biomarkers. Among the modalities conceptualized by the systems biology paradigm and utilized in the "exploratory biomarker discovery arena", proteome analysis has received the most attention. However, metabolomics, lipidomics, transcriptomics, and epigenomics have recently become key modalities in the search for AD biomarkers. Interestingly, biomarker changes for familial AD (fAD), in many but not all cases, seem similar to those for sAD. The integration of neurogenetics with systems biology/physiology-based strategies and high-throughput technologies for molecular profiling is expected to help identify the causes, mechanisms, and biomarkers associated with the various forms of AD. Moreover, in order to hypothesize the dynamic trajectories of biomarkers through disease stages and elucidate the mechanisms of biomarker alterations, updated and more sophisticated theoretical models have been proposed for both sAD and fAD.

Fluid biomarkers in multiple system atrophy: A review of the MSA Biomarker Initiative

Despite growing research efforts, no reliable biomarker currently exists for the diagnosis and prognosis of multiple system atrophy (MSA). Such biomarkers are urgently needed to improve diagnostic accuracy, prognostic guidance and also to serve as efficacy measures or surrogates of target engagement for future clinical trials. We here review candidate fluid biomarkers for MSA and provide considerations for further developments and harmonization of standard operating procedures. A PubMed search was performed until April 24, 2015 to review the literature with regard to candidate blood and cerebrospinal fluid (CSF) biomarkers for MSA. Abstracts of 1760 studies were retrieved and screened for eligibility. The final list included 60 studies assessing fluid biomarkers in patients with MSA. Most studies have focused on alpha-synuclein, markers of axonal degeneration or catecholamines. Their results suggest that combining several CSF fluid biomarkers may be more successful than using single markers, at least for the diagnosis. Currently, the clinically most useful markers may comprise a combination of the light chain of neurofilament (which is consistently elevated in MSA compared to controls and Parkinson's disease), metabolites of the catecholamine pathway and proteins such as α-synuclein, DJ-1 and total-tau. Beyond future efforts in biomarker discovery, the harmonization of standard operating procedures will be crucial for future success.

Cerebrospinal fluid proteomics and protein biomarkers in frontotemporal lobar degeneration: Current status and future perspectives

Frontotemporal lobar degeneration (FTLD) comprises a spectrum of rare neurodegenerative diseases with an estimated prevalence of 15-22 cases per 100,000 persons including the behavioral variant of frontotemporal dementia (bvFTD), progressive non-fluent aphasia (PNFA), semantic dementia (SD), FTD with motor neuron disease (FTD-MND), progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS). The pathogenesis of the diseases is still unclear and clinical diagnosis of FTLD is hampered by overlapping symptoms within the FTLD subtypes and with other neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). Intracellular protein aggregates in the brain are a major hallmark of FTLD and implicate alterations in protein metabolism or function in the disease's pathogenesis. Cerebrospinal fluid (CSF) which surrounds the brain can be used to study changes in neurodegenerative diseases and to identify disease-related mechanisms or neurochemical biomarkers for diagnosis. In the present review, we will give an overview of the current literature on proteomic studies in CSF of FTLD patients. Reports of targeted and unbiased proteomic approaches are included and the results are discussed in regard of their informative value about disease pathology and the suitability to be used as diagnostic biomarkers. Finally, we will give some future perspectives on CSF proteomics and a list of candidate biomarkers which might be interesting for validation in further studies. This article is part of a Special Issue entitled: Neuroproteomics: Applications in neuroscience and neurology.

Cerebrospinal fluid biomarkers in parkinsonian conditions: an update and future directions

Parkinsonian diseases comprise a heterogeneous group of neurodegenerative disorders, which show significant clinical and pathological overlap. Accurate diagnosis still largely relies on clinical acumen; pathological diagnosis remains the gold standard. There is an urgent need for biomarkers to diagnose parkinsonian disorders, particularly in the early stages when diagnosis is most difficult. In this review, several of the most promising cerebrospinal fluid candidate markers will be discussed. Their strengths and limitations will be considered together with future developments in the field.

Differentiation of progressive supranuclear palsy: clinical, imaging and laboratory tools

Progressive supranuclear palsy (PSP) is the most common atypical parkinsonian syndrome comprising two main clinical subtypes: Richardson's syndrome (RS), characterized by prominent postural instability, supranuclear vertical gaze palsy and frontal dysfunction; and PSP-parkinsonism (PSP-P) which is characterized by an asymmetric onset, tremor and moderate initial therapeutic response to levodopa. The early clinical features of PSP-P are often difficult to discern from idiopathic Parkinson's disease (PD), and other atypical parkinsonian disorders, including multiple system atrophy (MSA) and corticobasal syndrome (CBS). In addition, rare PSP subtypes may be overlooked or misdiagnosed if there are atypical features present. The differentiation between atypical parkinsonian disorders and PD is important because the prognoses are different, and there are different responses to therapy. Structural and functional imaging, although currently of limited diagnostic value for individual use in early disease, may contribute valuable information in the differential diagnosis of PSP. A growing body of evidence shows the importance of CSF biomarkers in distinguishing between atypical parkinsonian disorders particularly early in their course when disease-modifying therapies are becoming available. However, specific diagnostic CSF biomarkers have yet to be identified. In the absence of reliable disease-specific markers, we provide an update of the recent literature on the assessment of clinical symptoms, pathology, neuroimaging and biofluid markers that might help to distinguish between these overlapping conditions early in the course of the disease.