Cerebrospinal Fluid Protein Markers Research Articles

Evaluation of Apo A IV and Haptoglobin as Potential CSF Markers in Patients with Guillain-Barre´ Syndrome: A Cross-Sectional Study.

Brain- and blood-derived protein analysis in the cerebro-spinal fluid (CSF) in various studies performed abroad found that some proteins and their isoforms were altered significantly in Guillain-Barre´ syndrome (GBS) patients in comparison to controls. However, data are lacking in India with respect to the blood- or brain-derived proteins in patients of GBS. This study aimed to identify the role of apolipoprotein A IV (Apo A IV) and haptoglobin as potential protein markers in CSF of patients with GBS in our population. The study comprised 28 participants where 12 confirmed cases of GBS and 16 control subjects admitted for non-infectious neurological disorders were recruited after obtaining approval from the Institutional Ethics Committee. CSF glucose, protein, and adenosine deaminase were analyzed using an autoanalyzer. The concentrations of Apo A IV and haptoglobin were estimated with enzyme-linked immuno-sorbent assay (ELISA) kits. The CSF protein concentrations of cases were higher as compared to controls. The concentrations of haptoglobin and Apo A IV were higher in the confirmed cases of GBS as compared to the control subjects, and this difference was found to be significant. The receiver operating characteristic curve analysis for haptoglobin revealed that the area under the curve (AUC) was 0.867 (95% CI: 0.732-1.001), with a sensitivity of 83.8% and a specificity of 63.3%. The AUC for Apo A IV was 0.883 (95% CI: 0.758-1.009), with a sensitivity of 91.7% and a specificity of 73.3%. Haptoglobin along with Apo A IV can emerge as a potential biochemical marker in CSF for the diagnosis of GBS.

Comparison of Commonly Measured Plasma and Cerebrospinal Fluid Proteins and Their Significance for the Characterization of Cognitive Impairment Status.

Although cerebrospinal fluid (CSF) amyloid-β42 peptide (Aβ42) and phosphorylated tau (p-tau) and blood p-tau are valuable for differential diagnosis of Alzheimer's disease (AD) from cognitively normal (CN) there is a lack of validated biomarkers for mild cognitive impairment (MCI). This study sought to determine how plasma and CSF protein markers compared in the characterization of MCI and AD status. This cohort study included Alzheimer's Disease Neuroimaging Initiative (ADNI) participants who had baseline levels of 75 proteins measured commonly in plasma and CSF (257 total, 46 CN, 143 MCI, and 68 AD). Logistic regression, least absolute shrinkage and selection operator (LASSO) and Random Forest (RF) methods were used to identify the protein candidates for the disease classification. We observed that six plasma proteins panel (APOE, AMBP, C3, IL16, IGFBP2, APOD) outperformed the seven CSF proteins panel (VEGFA, HGF, PRL, FABP3, FGF4, CD40, RETN) as well as AD markers (CSF p-tau and Aβ42) to distinguish the MCI from AD [area under the curve (AUC) = 0.75 (plasma proteins), AUC = 0.60 (CSF proteins) and AUC = 0.56 (CSF p-tau and Aβ42)]. Also, these six plasma proteins performed better than the CSF proteins and were in line with CSF p-tau and Aβ42 in differentiating CN versus MCI subjects [AUC = 0.89 (plasma proteins), AUC = 0.85 (CSF proteins) and AUC = 0.89 (CSF p-tau and Aβ42)]. These results were adjusted for age, sex, education, and APOEϵ4 genotype. This study suggests that the combination of 6 plasma proteins can serve as an effective marker for differentiating MCI from AD and CN.

Comparison of plasma and cerebrospinal fluid protein markers and their significance for the characterization of dementia disease status

AbstractBackgroundAlthough Aβ42 and phosphorylated tau (p‐tau) in cerebrospinal fluid (CSF) are valuable to diagnose Alzheimer’s disease (AD), many patients are reluctant to accept lumbar puncture. In addition, there is lack of biomarkers for the different stages of AD dementia. This study sought to compare the plasma and CSF protein markers to characterize dementia status.MethodThis cohort study included Alzheimer’s Disease Neuroimaging Initiative (ADNI) participants who had baseline levels of 73 proteins measured in plasma (566 total, 58 cognitively normal (CN), 396 mild cognitive impairment (MCI), and 112 AD) and in CSF (310 total, 92 CN, 149 MCI, and 69 AD). Univariate/multivariate logistic regression and least absolute shrinkage and selection operator (LASSO) were used to identify the protein candidates for the disease classification. The following three models were examined for CN vs. MCI and MCI vs. AD; model 1: proteins only, model 2: proteins adjusted for age, sex, education, and model 3: model 2 plus APOE4 status.ResultNine proteins in plasma and CSF were chosen based on their importance from LASSO. The area under the curve (AUC) for the final multivariate logistic regression including the 9 proteins was calculated for each disease group in plasma [CN vs. MCI: 0.895 (model 1), 0.899 (model 2), 0.921 (model 3), and MCI vs. AD: 0.828 (model 1), 0.842 (model 2), 0.856 (model 3)]. In addition, AUC in CSF [CN vs. MCI: 0.678 (model 1), 0.726 (model 2), 0.770 (model 3) and MCI vs. AD: 0.711 (model 1), 0.738 (model 2), 0.765 (model 3)] was also estimated. We observed that plasma proteins outperformed the CSF proteins to be associated with MCI and AD. Also, plasma proteins were significantly better than the established AD markers, namely CSF Aβ42 and p‐tau in CN vs. MCI [AUC: 0.836 (model 1), 0.842 (model 2), 0.862 (model 3)] and MCI vs. AD [AUC: 0.665 (model 1), 0.673 (model 2), 0.680 (model 3)].ConclusionThis study demonstrates that the combination of plasma proteins could be considered an effective marker for diagnosing AD and its early‐stage symptoms with better performance than the other markers.

Cerebrospinal Fluid Protein Markers Indicate Neuro-Damage in SARS-CoV-2-Infected Nonhuman Primates

Neurologic manifestations are among the most frequently reported complications of COVID-19. However, given the paucity of tissue samples and the highly infectious nature of the etiologic agent of COVID-19, we have limited information to understand the neuropathogenesis of COVID-19. Therefore, to better understand the impact of COVID-19 on the brain, we used mass-spectrometry–based proteomics with a data-independent acquisition mode to investigate cerebrospinal fluid (CSF) proteins collected from two different nonhuman primates, Rhesus Macaque and African Green Monkeys, for the neurologic effects of the infection. These monkeys exhibited minimal to mild pulmonary pathology but moderate to severe central nervous system (CNS) pathology. Our results indicated that CSF proteome changes after infection resolution corresponded with bronchial virus abundance during early infection and revealed substantial differences between the infected nonhuman primates and their age-matched uninfected controls, suggesting these differences could reflect altered secretion of CNS factors in response to SARS-CoV-2-induced neuropathology. We also observed the infected animals exhibited highly scattered data distributions compared to their corresponding controls indicating the heterogeneity of the CSF proteome change and the host response to the viral infection. Dysregulated CSF proteins were preferentially enriched in functional pathways associated with progressive neurodegenerative disorders, hemostasis, and innate immune responses that could influence neuroinflammatory responses following COVID-19. Mapping these dysregulated proteins to the Human Brain Protein Atlas found that they tended to be enriched in brain regions that exhibit more frequent injury following COVID-19. It, therefore, appears reasonable to speculate that such CSF protein changes could serve as signatures for neurologic injury, identify important regulatory pathways in this process, and potentially reveal therapeutic targets to prevent or attenuate the development of neurologic injuries following COVID-19.

Human prion disease

AbstractHuman prion diseases (HPDs) are progressive and fatal neurodegenerative diseases caused by abnormal prion protein (PrPSc). They can be sporadic, genetic or acquired. Sporadic HPDs include sporadic Creutzfeldt–Jakob disease (CJD) and sporadic fatal insomnia. Genetic HPDs include genetic CJD, Gerstman–Sträussler–Scheinker disease and fatal familial insomnia. Acquired HPDs include Kuru, variant CJD and iatrogenic CJD. The World Health Organization clinical diagnostic criteria for HPDs include clinical findings, cerebrospinal fluid protein markers and electroencephalography, and the UK and European clinical diagnostic criteria include a combination of clinical findings, 14‐3‐3 protein in the cerebrospinal fluid, magnetic resonance imaging diffusion‐weighted imaging and electroencephalography. Recently, the development and clinical application of real‐time quaking‐induced conversion has allowed pre‐mortem diagnosis of sporadic CJD. The real‐time quaking‐induced conversion assay allows detection of >1 fg of PrPSc in diluted CJD brain homogenate, as well as a variety of biological tissues and cerebrospinal fluid. However, the real‐time quaking‐induced conversion assay does not provide prognostic data and has lower diagnostic accuracy for some rarer, atypical prion diseases. Furthermore, recent advancements in laboratory testing and magnetic resonance imaging diffusion‐weighted imaging have shown improved diagnostic accuracy for prion diseases. Clinical trials of prion disease treatments have recently begun in many countries. The therapeutic window consists mainly of the early stage of disease, and few clinical studies have examined the role of biomarkers at this stage. Therefore, biomarkers, imaging and clinical symptoms might be extremely important for the diagnosis of prion diseases.Clinical trials of prion disease treatments have recently begun in many countries. The therapeutic window mainly consists of the early stage of disease, and few clinical studies have examined the role of biomarkers at this stage. Therefore, biomarkers, imaging and clinical symptoms might be extremely important for the diagnosis of prion diseases.

Altered levels of CSF proteins in patients with FTD, presymptomatic mutation carriers and non-carriers

BackgroundThe clinical presentations of frontotemporal dementia (FTD) are diverse and overlap with other neurological disorders. There are, as of today, no biomarkers in clinical practice for diagnosing the disorders. Here, we aimed to find protein markers in cerebrospinal fluid (CSF) from patients with FTD, presymptomatic mutation carriers and non-carriers.MethodsAntibody suspension bead arrays were used to analyse 328 proteins in CSF from patients with behavioural variant FTD (bvFTD, n = 16) and progressive primary aphasia (PPA, n = 13), as well as presymptomatic mutation carriers (PMC, n = 16) and non-carriers (NC, n = 8). A total of 492 antibodies were used to measure protein levels by direct labelling of the CSF samples. The findings were further examined in an independent cohort including 13 FTD patients, 79 patients with Alzheimer’s disease and 18 healthy controls.ResultsWe found significantly altered protein levels in CSF from FTD patients compared to unaffected individuals (PMC and NC) for 26 proteins. The analysis show patterns of separation between unaffected individuals and FTD patients, especially for those with a clinical diagnosis of bvFTD. The most statistically significant differences in protein levels were found for VGF, TN-R, NPTXR, TMEM132D, PDYN and NF-M. Patients with FTD were found to have higher levels of TN-R and NF-M, and lower levels of VGF, NPTXR, TMEM132D and PDYN, compared to unaffected individuals. The main findings were reproduced in the independent cohort.ConclusionIn this pilot study, we show a separation of FTD patients from unaffected individuals based on protein levels in CSF. Further investigation is required to explore the CSF profiles in larger cohorts, but the results presented here has the potential to enable future clinical utilization of these potential biomarkers within FTD.

Hypothesis: cerebrospinal fluid protein markers suggest a pathway toward symptomatic resilience to AD pathology

IntroductionWe sought biological pathways that explained discordance between Alzheimer's disease (AD) pathology and symptoms. MethodsIn 306 Alzheimer's Disease Neuroimaging Initiative (ADNI)-1 participants across the AD clinical spectrum, we investigated association between cognitive outcomes and 23 cerebrospinal fluid (CSF) analytes associated with abnormalities in the AD biomarkers amyloid β1-42 and total-tau. In a 200-person “training” set, Least Absolute Shrinkage and Selection Operator regression estimated model weights for the 23 proteins, and for the AD biomarkers themselves, as predictors of ADAS-Cog11 scores. In the remaining 106 participants (“validation” set), fully adjusted regression models then tested the Least Absolute Shrinkage and Selection Operator–derived models and a related protein marker summary score as predictors of ADAS-Cog11, ADNI diagnostic category, and longitudinal cognitive trajectory. ResultsAD biomarkers alone explained 26% of the variance in validation set cognitive scores. Surprisingly, the 23 AD-related proteins explained 31% of this variance. The biomarkers and protein markers appeared independent in this respect, jointly explaining 42% of test score variance. The composite protein marker score also predicted ADNI diagnosis and subsequent cognitive trajectory. Cognitive outcome prediction redounded principally to ten markers related to lipid or vascular functions or to microglial activation or chemotaxis. In each analysis, apoE protein and four markers in the latter immune-activation group portended better outcomes. DiscussionCSF markers of vascular, lipid-metabolic and immune-related functions may explain much of the disjunction between AD biomarker abnormality and symptom severity. In particular, our results suggest the hypothesis that innate immune activation improves cognitive outcomes in persons with AD pathology. This hypothesis should be tested by further study of cognitive outcomes related to CSF markers of innate immune activation.

Evaluation of cerebrospinal fluid proteins as potential biomarkers for early stage Parkinson’s disease diagnosis

Cerebrospinal fluid (CSF) has often been used as the source of choice for biomarker discovery with the goal to support the diagnosis of neurodegenerative diseases. For this study, we selected 15 CSF protein markers which were identified in previously published clinical investigations and proposed as potential biomarkers for PD diagnosis. We aimed at investigating and confirming their suitability for early stage diagnosis of the disease. The current study was performed in a two-fold confirmatory approach. Firstly, the CSF protein markers were analysed in confirmatory cohort I comprising 80 controls and 80 early clinical PD patients. Through univariate analysis we found significant changes of six potential biomarkers (α-syn, DJ-1, Aβ42, S100β, p-Tau and t-Tau). In order to increase robustness of the observations for potential patient differentiation, we developed–based on a machine learning approach—an algorithm which enabled identifying a panel of markers which would improve clinical diagnosis. Based on that model, a panel comprised of α-syn, S100β and UCHL1 were suggested as promising candidates. Secondly, we aimed at replicating our observations in an independent cohort (confirmatory cohort II) comprising 30 controls and 30 PD patients. The univariate analysis demonstrated Aβ42 as the only reproducible potential biomarker. Taking into account both technical and clinical aspects, these observations suggest that the large majority of the investigated CSF proteins currently proposed as potential biomarkers lack robustness and reproducibility in supporting diagnosis in the early clinical stages of PD.

Cerebrospinal fluid protein markers in PD patients after DBS-STN surgery—A retrospective analysis of patients that underwent surgery between 1993 and 2001

ObjectiveCerebrospinal fluid (CSF) markers of neurodegeneration [neurofilament light chain (NFL), total Tau (T-Tau)], tau pathology [phosphorylated tau (p-Tau)], glial cell damage or activation [glial fibrillary acidic protein (GFAP)], and brain amyloidosis [β-amyloid 1-42 (Aβ42)] are useful for diagnosis and prognosis in several neurodegenerative disorders. In this paper we investigate these markers and their relationship to key clinical milestones in patients with advanced Parkinson´s disease (PD) operated at our center with subthalamic nucleus deep brain stimulation (STN-DBS) for at least 15 years ago. Patients and methodsRetrospective analysis of available cerebrospinal fluid and clinical data in PD-patients, 15 years or more after they underwent STN-DBS surgery. All PD-patients implanted with STN-DBS at Sahlgrenska University Hospital before January 1, 2001, were regularly assessed until January 10, 2018, or until death, or until lost to follow-up. ResultsTwenty three PD patients were operated with STN-DBS. Sixteen of these (six females and ten males) underwent at least one lumbar puncture (LP) immediately prior to or after STN-DBS. Their age at the latest available LP was 64 (55–75) years [median (range)], PD duration 20 (11–33) years, and Hoehn & Yahr (H&Y) stage 3 (2–4). Time between DBS operation and the last LP was 4.5 (0.3–10.8) years. Time from the last LP to the last follow up was 6 (0.1–18) years, and for the entire cohort 115 person-years. On January 10, 2018, four PD-patients (25%) were still alive.All preoperative CSF marker levels were normal. Between two days and six months after DBS, NFL and GFAP levels increased sharply but they normalized thereafter in most patients, and were normal up to almost 11 years after neurosurgery. Over time, all patients deteriorated slowly. At the last follow up, H&Y was 5 (3–5) and 12/16 were demented.There was no significant correlation between postoperative (> 6 months) CSF NFL, GFAP, T-Tau, p-Tau, β-amyloid levels and the presence of dementia, psychosis, inability to walk or need for nursing home at the time for LP, nor for presence of dementia at the last follow up or for death as of January 10, 2018. ConclusionCSF protein biomarkers remain normal despite long PD duration, severe disability, and chronic STN-DBS. They cannot be used for PD staging or prognostication but may indicate brain damage caused by other pathological factors.

Characterization and clinical use of inflammatory cerebrospinal fluid protein markers in Alzheimer\u2019s disease

BackgroundNeuroinflammation has gained increasing attention as a potential contributing factor in Alzheimer’s disease (AD) pathology. A clinical cerebrospinal fluid biomarker capable of monitoring this process during the course of the disease has yet to emerge, chiefly owing to contradictory research findings. In this study, we sought to clarify the utility of inflammatory biomarkers in diagnostic procedures of AD in three steps: (1) to screen for proteins that are robustly detectable in cerebrospinal fluid; (2) based on this analysis, to explore any associations between the analytically robust markers and salient pathological features of AD; and (3) to determine the discriminative power of these markers in the clinical diagnosis of AD.MethodsFrom a total of 46 proteins, 15 that were robustly detectable in cerebrospinal fluid were identified. A subsequent analysis of these markers in a cohort of 399 patients (nondemented subjects, patients with mild cognitive impairment [MCI], and patients with AD, supplemented by smaller cohorts of other diseases) was conducted. Fluid biomarker data were related to AD pathology and neuropsychological markers and adjusted for confounders such as age, sex, apolipoprotein E genotype, and biobank storage time.ResultsCerebrospinal fluid levels of C-reactive protein and soluble TREM2 differed between nondemented subjects, patients with MCI, or patients with AD and were associated with amyloid and tau pathology. Several markers were associated with tau pathology only or with other neurodegenerative diseases. Correlations between neuropsychological performance and inflammatory markers were weak, but they were most prominent in AD and for the most challenging cognitive tests. All investigated covariates had significant influence, with varying effects across the markers. Still, none of the markers achieved discriminative power of more than 70% to distinguish between patient groups defined by clinical or neuropathological categories.ConclusionsBasic analytical considerations proved indispensable for this type of study because only one-third of the tested markers were robustly detectable in cerebrospinal fluid. Detectable inflammatory protein markers were associated in multiple ways with AD pathology. Yet, even significantly associated markers were not powerful enough in terms of effect strength, sensitivity, and specificity, and hence they were not suited for direct use in clinical diagnostic practice. Targets other than those most commonly considered in this field of research might provide results with better clinical applicability.

Value of determining the cerebrospinal fluid protein markers of amyloidosis and neurodegeneration in the diagnosis of vascular and neurodegenerative cognitive impairments

The article presents data on different forms of moderate cognitive impairments (MCI) and the specific features of their transformation to dementia. Cerebrospinal fluid (CSF) was investigated in 60 patients with the amnestic and neurodynamic types of MCI, in 15 patients with vascular dementia (VD), 50 patients with Alzheimer’s disease (AD), and 23 patients with mixed vascular and neurodegenerative dementia (MVND). The specific features of β-amyloid and τ-protein concentrations were established in the preclinical stages of dementia, which reflects the main components of the pathogenesis of neurodegeneration. In the amnestic form of MCI and AD, there was drastically decreased Aβ-42 and increased τ-protein levels in SCF. As cognitive impairments progressed, there was a rise in the concentration of τ-protein; its level correlated with the severity of dementia. In MND, the level of Aβ-42 was significantly reduced while the concentration of τ-protein was much increased; moreover, to a greater extent than in AD and VD. Cerebrovascular damage and neurodegeneration were related to each other and mutually worsened clinical and pathogenic effects.

Diagnostic accuracy of cerebrospinal fluid protein markers for sporadic Creutzfeldt-Jakob disease in Canada: a 6-year prospective study.

BackgroundTo better characterize the value of cerebrospinal fluid (CSF) proteins as diagnostic markers in a clinical population of subacute encephalopathy patients with relatively low prevalence of sporadic Creutzfeldt-Jakob disease (sCJD), we studied the diagnostic accuracies of several such markers (14-3-3, tau and S100B) in 1000 prospectively and sequentially recruited Canadian patients with clinically suspected sCJD.MethodsThe study included 127 patients with autopsy-confirmed sCJD (prevalence = 12.7%) and 873 with probable non-CJD diagnoses. Standard statistical measures of diagnostic accuracy were employed, including sensitivity (Se), specificity (Sp), predictive values (PVs), likelihood ratios (LRs), and Receiver Operating Characteristic (ROC) analysis.ResultsAt optimal cutoff thresholds (empirically selected for 14-3-3, assayed by immunoblot; 976 pg/mL for tau and 2.5 ng/mL for S100B, both assayed by ELISA), Se and Sp respectively were 0.88 (95% CI, 0.81-0.93) and 0.72 (0.69-0.75) for 14-3-3; 0.91 (0.84-0.95) and 0.88 (0.85-0.90) for tau; and 0.87 (0.80-0.92) and 0.87 (0.84-0.89) for S100B. The observed differences in Sp between 14-3-3 and either of the other 2 markers were statistically significant. Positive LRs were 3.1 (2.8-3.6) for 14-3-3; 7.4 (6.9-7.8) for tau; and 6.6 (6.1-7.1) for S100B. Negative LRs were 0.16 (0.10-0.26) for 14-3-3; 0.10 (0.06-0.20) for tau; and 0.15 (0.09-0.20) for S100B. Estimates of areas under ROC curves were 0.947 (0.931-0.961) for tau and 0.908 (0.888-0.926) for S100B. Use of interval LRs (iLRs) significantly enhanced accuracy for patient subsets [e.g., 41/120 (34.2%) of tested sCJD patients displayed tau levels > 10,000 pg/mL, with an iLR of 56.4 (22.8-140.0)], as did combining tau and S100B [e.g., for tau > 976 pg/mL and S100B > 2.5 ng/mL, positive LR = 18.0 (12.9-25.0) and negative LR = 0.02 (0.01-0.09)].ConclusionsCSF 14-3-3, tau and S100B proteins are useful diagnostic markers of sCJD even in a low-prevalence clinical population. CSF tau showed better overall diagnostic accuracy than 14-3-3 or S100B. Reporting of quantitative assay results and combining tau with S100B could enhance case definitions used in diagnosis and surveillance of sCJD.

The role of cerebrospinal fluid proteins as early diagnostic markers for sporadic Creutzfeldt–Jakob disease

The utility of cerebrospinal fluid (CSF) proteins such as 14-3-3, tau protein and S-100b as diagnostic markers in the early stages of sporadic Creutzfeldt–Jakob disease (sCJD) is unclear. We examined the diagnostic value of these CSF proteins in the early stages of sCJD (within 6 weeks of onset of symptoms). Four groups of patients were compared: patients with probable or neuropathologically confirmed sCJD with CSF taken within 6 weeks of onset (‘sCJD < 6-week group’, n = 47); patients with CSF taken within 6 weeks of disease onset but with a diagnosis other than CJD (‘non-sCJD < 6-week group’, n = 21); patients with neuropathologically proven sCJD where CSF was taken later than 6 weeks after onset (’sCJD > 6-week group’, n = 206); patients with CSF taken later than 6 weeks after onset of symptoms but with a diagnosis other than CJD (‘non-sCJD > 6-week group’, n = 166). The sensitivity and specificity of different combinations of neuronal proteins were ascertained. The sensitivities of all three markers were similar and ranged from 96% to 98%. The sensitivity of these markers was greater in the ‘sCJD < 6-week group’ than in the ‘sCJD > 6-week group’. This may be due to differences in the PRNP codon 129 and PrP isotype distribution between these groups. CSF tau protein had the greatest specificity (82%). We found all three CSF protein markers to be highly sensitive in the early stages of sCJD, with CSF tau protein having the greatest specificity and efficiency. Our findings indicate that CSF protein markers are effective tests in the early stages of sCJD.

A Novel Panel of Cerebrospinal Fluid Biomarkers for the Differential Diagnosis of Alzheimer’s Disease versus Normal Aging and Frontotemporal Dementia

Background: An early and accurate diagnosis of Alzheimer’s disease (AD) is important in order to initiate symptomatic treatment with currently approved drugs and will be of even greater importance with the advent of disease-modifying compounds. Methods: Protein profiles of human cerebrospinal fluid samples from patients with AD (n = 85), frontotemporal dementia (n = 20), and healthy controls (n = 32) were analyzed by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry to verify previously discovered biomarkers. Results: We verified 15 protein biomarkers that were able to differentiate between AD and controls, and 7 of these 15 markers also differentiated AD from FTD. Conclusion: A panel of cerebrospinal fluid protein markers was verified by a proteomics technology which may potentially improve the accuracy of the AD diagnosis.

Identification of disease-related biomarkers by proteome analysis of cerebrospinal fluid in Guillain–Barré syndrome

Evaluation of: Jin T, Hu LS, Chang M, Wu J, Winblad B, Zhu J: Proteomic identification of potential protein markers in cerebrospinal fluid of GBS patients. Eur. J. Neurol. 14(5), 563–568 (2007). This study aimed to identify disease-related biomarkers in cerebrospinal fluid (CSF) from patients with Guillain–Barré syndrome (GBS) using the proteomic analysis 2D difference in gel electrophoresis. Six different protein levels were found to be changed in CSF of GBS patients as compared with controls. Haptoglobin, ApoA-IV and an unnamed protein (PRO2044) were increased in CSF of GBS patients, while transthyretin, ApoE and fibrinogen were found to be decreased. The significance of these proteins remains to be further evaluated by quantitative assays and by taking into account disease-related variables such as blood–CSF barrier function and subtype of GBS.

Proteomic identification of potential protein markers in cerebrospinal fluid of GBS patients

Increased protein level in the cerebrospinal fluid (CSF) is a characteristic of patients with Guillain-Barré syndrome (GBS), an acute inflammatory autoimmune disorder in the peripheral nervous system (PNS). However, the molecular mechanisms underlying the disease remain poorly understood and so far no reliable disease-related markers are available. By comparing the CSF proteome of GBS patients with control subjects suffering from other neurological disorders, it may be possible to identify proteins that involve in the disease process and thus to study the pathogenesis of GBS. We used two-dimensional difference gel electrophoresis (2D DIGE) technique, in combination with matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS), to determine the abnormal CSF proteins in GBS patients. Our data showed that the levels of six proteins and their isoforms in CSF were significantly altered in GBS patients compared with controls. Haptoglobin, apolipoprotein A-IV and PRO2044 (unnamed protein) were considerably increased in the CSF of GBS patients, whereas transthyretin, apolipoprotein E and fibrinogen were considerably decreased. We concluded that these six proteins may be involved in the pathogenesis of GBS and call for further studying the role of these proteins in the pathogenesis of the disease.

Comparative Proteomic Analysis of Intra- and Interindividual Variation in Human Cerebrospinal Fluid

Cerebrospinal fluid (CSF) is a potential source of biomarkers for many disorders of the central nervous system, including Alzheimer disease (AD). Prior to comparing CSF samples between individuals to identify patterns of disease-associated proteins, it is important to examine variation within individuals over a short period of time so that one can better interpret potential changes in CSF between individuals as well as changes within a given individual over a longer time span. In this study, we analyzed 12 CSF samples, composed of pairs of samples from six individuals, obtained 2 weeks apart. Multiaffinity depletion, two-dimensional DIGE, and tandem mass spectrometry were used. A number of proteins whose abundance varied between the two time points was identified for each individual. Some of these proteins were commonly identified in multiple individuals. More importantly, despite the intraindividual variations, hierarchical clustering and multidimensional scaling analysis of the proteomic profiles revealed that two CSF samples from the same individual cluster the closest together and that the between-subject variability is much larger than the within-subject variability. Among the six subjects, comparison between the four cognitively normal and the two very mildly demented subjects also yielded some proteins that have been identified in previous AD biomarker studies. These results validate our method of identifying differences in proteomic profiles of CSF samples and have important implications for the design of CSF biomarker studies for AD and other central nervous system disorders.

Proteomic studies of potential cerebrospinal fluid protein markers for Alzheimer's disease

By comparing the cerebrospinal fluid (CSF) proteome between Alzheimer's disease (AD) patients and controls, it may be possible to identify proteins that play a role in the disease process and thus to study the pathogenesis of AD. Two-dimensional gel electrophoresis (2-DE), SYPRO Ruby staining and mass spectrometry were used for clinical screening of disease-influenced CSF proteins in AD patients compared to controls. In order to increase the detection of CSF proteins and to improve the separation of protein isoforms in a 2-D gel, micro-narrow range IPG strips were used. The levels of eight proteins and their isoforms, including apolipoprotein A1, apolipoprotein E, apolipoprotein J, β-trace, retinol-binding protein, kininogen, α-1 antitrypsin, cell cycle progression 8 protein, and α-1β glycoprotein were significantly altered in CSF of AD patients compared to controls. Furthermore, we also used liquid-phase IEF, as a prefractionation step, prior to 2-DE for comparison of CSF proteins between individual AD patients and controls. The levels of 37 proteins spots were altered in AD patients. One of the identified proteins, α-2-HS glycoprotein, has not previously been linked to AD. Our study shows that several glycoproteins are altered in AD.