Classical Cerebrospinal Fluid Research Articles

AQP4 labels a subpopulation of white matter-dependent glial radial cells affected by pediatric hydrocephalus, and its expression increased in glial microvesicles released to the cerebrospinal fluid in obstructive hydrocephalus

Hydrocephalus is a distension of the ventricular system associated with ventricular zone disruption, reactive astrogliosis, periventricular white matter ischemia, axonal impairment, and corpus callosum alterations. The condition's etiology is typically attributed to a malfunction in classical cerebrospinal fluid (CSF) bulk flow; however, this approach does not consider the unique physiology of CSF in fetal and perinatal patients. The parenchymal fluid contributes to the glymphatic system, and plays a fundamental role in pediatric hydrocephalus, with aquaporin 4 (AQP4) as the primary facilitator of these fluid movements. Despite the importance of AQP4 in the pathophysiology of hydrocephalus, it’s expression in human fetal life is not well-studied. This manuscript systematically defines the brain expression of AQP4 in human brain development under control (n = 13) and hydrocephalic conditions (n = 3). Brains from 8 postconceptional weeks (PCW) onward and perinatal CSF from control (n = 2), obstructive (n = 6) and communicating (n = 6) hydrocephalic samples were analyzed through immunohistochemistry, immunofluorescence, western blot, and flow cytometry. Our results indicate that AQP4 expression is observed first in the archicortex, followed by the ganglionic eminences and then the neocortex. In the neocortex, it is initially at the perisylvian regions, and lastly at the occipital and prefrontal zones. Characteristic astrocyte end-feet labeling surrounding the vascular system was not established until 25 PCW. We also found AQP4 expression in a subpopulation of glial radial cells with processes that do not progress radially but, rather, curve following white matter tracts (corpus callosum and fornix), which were considered as glial stem cells (GSC). Under hydrocephalic conditions, GSC adjacent to characteristic ventricular zone disruption showed signs of early differentiation into astrocytes which may affect normal gliogenesis and contribute to the white matter dysgenesis. Finally, we found that AQP4 is expressed in the microvesicle fraction (p < 0.01) of CSF from patients with obstructive hydrocephalus. These findings suggest the potential use of AQP4 as a diagnostic and prognostic marker of pediatric hydrocephalus and as gliogenesis biomarker.

Fluid Biomarkers in Alzheimer's Disease and Other Neurodegenerative Disorders: Toward Integrative Diagnostic Frameworks and Tailored Treatments.

The diagnosis of neurodegenerative diseases (NDDs) represents an increasing social burden, with the unsolved issue of disease-modifying therapies (DMTs). The failure of clinical trials treating Alzheimer′s Disease (AD) so far highlighted the need for a different approach in drug design and patient selection. Identifying subjects in the prodromal or early symptomatic phase is critical to slow down neurodegeneration, but the implementation of screening programs with this aim will have an ethical and social aftermath. Novel minimally invasive candidate biomarkers (derived from blood, saliva, olfactory brush) or classical cerebrospinal fluid (CSF) biomarkers have been developed in research settings to stratify patients with NDDs. Misfolded protein accumulation, neuroinflammation, and synaptic loss are the pathophysiological hallmarks detected by these biomarkers to refine diagnosis, prognosis, and target engagement of drugs in clinical trials. We reviewed fluid biomarkers of NDDs, considering their potential role as screening, diagnostic, or prognostic tool, and their present-day use in clinical trials (phase II and III). A special focus will be dedicated to novel techniques for the detection of misfolded proteins. Eventually, an applicative diagnostic algorithm will be proposed to translate the research data in clinical practice and select prodromal or early patients to be enrolled in the appropriate DMTs trials for NDDs.

Multivariate Assessment of Lipoxidative Metabolites, Trace Biometals, and Antioxidant and Detoxifying Activities in the Cerebrospinal Fluid Define a Fingerprint of Preclinical Stages of Alzheimer's Disease.

There exists considerable interest in the identification of molecular traits during early stages of Alzheimer's disease (AD). Mild cognitive impairment (MCI) is considered the closest prodromal stage of AD, and to develop gradually from earlier stages although not always progresses to AD. Classical cerebrospinal fluid (CSF) AD biomarkers, amyloid-β peptides and tau/p-tau proteins, have been measured in prodromal stages yet results are heterogeneous and far from conclusive. Therefore, there exists a pressing need to identify a neurochemical signature for prodromal stages and to predict which cases might progress to AD. Exploring potential CSF biomarkers related to brain oxidative and inorganic biochemistry during prodromal stages of the disease. We have analyzed CSF levels of lipoxidative markers (MDA and 8-isoF2α), biometals (Cu, Zn, Se, Mn, and Fe), iron-transport protein transferrin (TFER), antioxidant enzymes (SOD and GPx4), detoxifying enzymes (GST and BuChE), as well as classical amyloid-β and total and phosphorylated tau, in cognitively healthy controls, patients with MCI, and subjects exhibiting subjective memory complaints (SMC). Inter-group differences for several variables exhibit differentiable trends along the HC ⟶ SMC ⟶ MCI sequence. More interestingly, the combination of Se, Cu, Zn, SOD, TFER, and GST variables allow differentiable fingerprints for control subjects and each prodromal stage. Further, multivariate scores correlate positively with neurocognitive In-Out test, hence with both episodic memory decline and prediction to dementia. We conclude that changes in the CSF biochemistry related to brain oxidative defense and neurometallomics might provide more powerful and accurate diagnostic tools in preclinical stages of AD.

CSF protein panels reflecting multiple pathophysiological mechanisms for early and specific diagnosis of Alzheimer’s disease

AbstractBackgroundThe development of disease‐modifying therapies against Alzheimer’s disease (AD) requires biomarker panels that reflect the diverse pathological pathways specifically involved in AD. Here we aimed to identify and validate panels of cerebrospinal fluid (CSF) proteins covering different molecular pathways for early and specific diagnosis of AD.MethodWe measured 665 proteins in 797 CSF samples from patients with mild cognitive impairment with abnormal amyloid (MCI(Aβ+): n=50), AD‐dementia (n=230), non‐AD dementias (n=322; 123 DLB and 199 FTD) and cognitively‐unimpaired controls (n=195; classical AD CSF biomarkers negative) using proximity ligation‐based multiplex immunoassays. Nested and penalized linear modeling were used to identify protein differences (q&lt;0,05) and translatable classification signatures.ResultWe detected highly dysregulated CSF proteins in MCI(Aβ+) or AD compared to controls (112 and 288 proteins respectively, lowest q:1‐15 and 1‐23), as well as between AD and non‐AD dementias (469 proteins; lowest q:1‐29). We confirmed previous findings (e.g., DDAH1, ENO2, PARK7), but we also identified novel proteins especially associated to the prodromal and/or dementia AD stages (e.g., ABL1, SCD4, ENTPD5). Proteins dysregulated in MCI(Aβ+) were primarily related to oxidative stress and energy metabolism, while those specifically dysregulated in later stages of AD dementia were related to cell remodeling, vascular function and immune system. Using penalised generalised linear modeling we identified the minimal number of markers with maximal power to discriminate clinical groups: for MCI(Aβ+) vs. controls: 10‐CSF proteins, AUC:0.99 (95%CI:0.97‐1); for AD vs. controls: 8‐CSF proteins, AUC:0.95 (95%CI:0.92‐0.99) and for AD vs. non‐AD dementias: 9‐CSF proteins, AUC:0.87 (95%CI:0.81‐0.93). The CSF panel discriminating AD from cognitively unimpaired controls was validated in an independent external cohort (n=62, AUC:0.94). Only 3 proteins overlapped across panels, suggesting that the panels with the strongest discriminative power are specific for disease stage and clinical group.ConclusionThis unprecedented large and protein‐rich CSF study indicates that CSF proteome follows a highly dynamic trajectory with distinct CSF profiles associated to different biological processes along the AD continuum. We unveil optimal CSF biomarker panels reflecting the specific multifactorial nature of AD, which can be now translated into customised assays for widespread validation and potential use in heterogeneous diagnostic settings or clinical trials.

Cerebrospinal fluid dynamics

The classical cerebrospinal fluid (CSF) circulation theory has been accepted as an established theory of CSF physiology. It describes bulk CSF flow from production site to absorption site. However, much controversy remains regarding the basic CSF physiology and the mechanisms behind the development of hydrocephalus. In the recent observations made using advanced magnetic resonance imaging (MRI) technique, namely, the time spatial inversion pulse (Time-SLIP) method, CSF was used as internal CSF tracer to trace true CSF movement. Observation of the CSF dynamics using this method reveals aspects of CSF dynamics that are different from those of classical CSF circulation theory. Cerebrospinal fluid shows pulsation but does not show bulk flow from production site to absorption site, a theory that was built upon externally injected tracer studies. Observation of the exogeneous tracer studies were true but misinterpreted. Causes of misinterpretations are the differences between results obtained using the true CSF tracer and exogenous tracers. A better understanding of the real CSF physiology can be significant for the advancement of medical sciences in the future. Revisiting CSF flow physiology is a necessary step toward this goal.

Combined testing of cerebrospinal fluid IL-12 (p40) and serum C-reactive protein as a possible discriminator of acute bacterial neuroinfections

IntroductionCentral nervous system infections (CNS) are life-threatening diseases, with meningitis being the most common. Viral infections are usually self-limiting diseases but bacterial pathogens are associated with higher mortality rates and persistent neurological sequelae. We aimed to study the role of IL-6, IL-8, IL-10, IL-12(p40), TNF-α cytokines, classical cerebrospinal fluid (CSF) parameters, and serum C-reactive protein levels (CRP) for discriminating bacterial from viral central nervous system infections. Material and methodsThis prospective study included 80 patients with clinical signs and abnormal cerebrospinal fluid laboratory findings typical for neuroinfection admitted to St. George University Hospital-Plovdiv. Routine methods such as direct microscopy, culturing and identification were used for microbiological analysis as well as latex-agglutination test and multiplex PCR. Cytokines' concentrations were measured by ELISA. CRP and CSF parameters were collected from the patients' medical records. ResultsWe observed the highest discriminatory power among cytokines for cerebrospinal IL-12(p40) (AUC = 0.925; p = 0.000). CSF protein levels were the best predictor for bacterial neuroinfection (AUC = 0.973; p = 0.000). The AUC for the serum CRP as a stand-alone biomarker was estimated to be 0.943. The discriminatory power can be increased up to 0.995 (p = 0.000) when combining cerebrospinal fluid IL-12(p40) and serum CRP, with an optimal cut-off value of 144 (Sensitivity 100%; Specificity 90.9%). ConclusionThe combined testing of CSF IL-12(p40) and serum CRP is associated with the highest diagnostic accuracy.

Diagnostic performance of new and classic CSF biomarkers in age-related dementias.

The identification of diagnostic-prognostic biomarkers of dementia has become a global priority due to the prevalence of neurodegenerative diseases in aging populations. The objective of this study was to assess the diagnostic performance of cerebrospinal fluid (CSF) biomarkers across patients affected by either Alzheimer’s disease (AD), tauopathies other than AD (TP), or vascular dementia (VD), and cognitively normal subjects (CNS). One hundred fifty-three patients were recruited and tested for classical AD CSF biomarkers- Amyloid-ß42 and tau proteins - and novel candidate biomarkers - neurofilament (NF-) light and microRNA (miR) -21, -125b, -146a, and -222.All dementia patients had significantly higher concentrations of NF-light compared to CNS, with the TP group displaying the highest NF-light values. A significant inverse correlation was also observed between NF-light and cognitive impairment. Of the four miRNAs analyzed, miR-222 levels were significantly increased in VD patients compared to both CNS and AD. In addition, while NF-light showed a better diagnostic performance than miR-222 and classical AD biomarkers in differentiating TP and VD from CNS, classical AD biomarkers revealed higher performance in discriminating AD from non-AD disorders.Overall, our results suggest that CSF NF-light and miR-222 are promising biomarkers that may help to diagnose non-AD disorders.

Improved Differential Diagnosis of Alzheimer's Disease by Integrating ELISA and Mass Spectrometry-Based Cerebrospinal Fluid Biomarkers.

Background: Alzheimer’s disease (AD) is diagnosed based on a clinical evaluation as well as analyses of classical biomarkers: Aβ42, total tau (t-tau), and phosphorylated tau (p-tau) in cerebrospinal fluid (CSF). Although the sensitivities and specificities of the classical biomarkers are fairly good for detection of AD, there is still a need to develop novel biochemical markers for early detection of AD.Objective: We explored if integration of novel proteins with classical biomarkers in CSF can better discriminate AD from non-AD subjects.Methods: We applied ELISA, mass spectrometry, and multivariate modeling to investigate classical biomarkers and the CSF proteome in subjects (n = 206) with 76 AD patients, 74 mild cognitive impairment (MCI) patients, 11 frontotemporal dementia (FTD) patients, and 45 non-dementia controls. The MCI patients were followed for 4–9 years and 21 of these converted to AD, whereas 53 remained stable.Results: By combining classical CSF biomarkers with twelve novel markers, the area of the ROC curves (AUROCS) of distinguishing AD and MCI/AD converters from non-AD were 93% and 96%, respectively. The FTDs and non-dementia controls were identified versus all other groups with AUROCS of 96% and 87%, respectively.Conclusions: Integration of new and classical CSF biomarkers in a model-based approach can improve the identification of AD, FTD, and non-dementia control subjects.

Non-Phosphorylated Tau in Cerebrospinal Fluid is a Marker of Alzheimer's Disease Continuum in Young Urbanites Exposed to Air Pollution.

Long-term exposure to fine particulate matter (PM2.5) and ozone (O3) above USEPA standards is associated with Alzheimer's disease (AD) risk. Metropolitan Mexico City (MMC) children exhibit subcortical pretangles in infancy and cortical tau pre-tangles, NFTs, and amyloid phases 1-2 by the 2nd decade. Given their AD continuum, we measured in 507 normal cerebrospinal fluid (CSF) samples (MMC 354, controls 153, 12.82±6.73 y), a high affinity monoclonal non-phosphorylated tau antibody (non-P-Tau), as a potential biomarker of AD and axonal damage. In 81 samples, we also measured total tau (T-Tau), tau phosphorylated at threonine 181 (P-Tau), amyloid-β1-42, BDNF, and vitamin D. We documented by electron microscopy myelinated axonal size and the pathology associated with combustion-derived nanoparticles (CDNPs) in anterior cingulate cortex white matter in 6 young residents (16.25±3.34 y). Non-P-Tau showed a strong increase with age significantly faster among MMC versus controls (p = 0.0055). Aβ1 - 42 and BDNF concentrations were lower in MMC children (p = 0.002 and 0.03, respectively). Anterior cingulate cortex showed a significant decrease (p = <0.0001) in the average axonal size and CDNPs were associated with organelle pathology. Significant age increases in non-P-Tau support tau changes early in a population with axonal pathology and evolving AD hallmarks in the first two decades of life. Non-P-Tau is an early biomarker of axonal damage and potentially valuable to monitor progressive longitudinal changes along with AD multianalyte classical CSF markers. Neuroprotection of young urbanites with PM2.5 and CDNPs exposures ought to be a public health priority to halt the development of AD in the first two decades of life.

Levels of ADAM10 are reduced in Alzheimer\u2019s disease CSF

BackgroundThe disintegrin metalloproteinase 10 (ADAM10) is the main α-secretase acting in the non-amyloidogenic processing of the amyloid precursor protein. This study assesses whether ADAM10 is present in cerebrospinal fluid (CSF), and whether it has potential as a biomarker for Alzheimer’s disease (AD).MethodsADAM10 was characterized in human CSF samples by immunoprecipitation and western blotting using antibodies specific for different domains of the protein and by ultracentrifugation in sucrose density gradients. Samples from AD patients (n = 20) and age-matched non-AD controls (n = 20) were characterized for classical CSF biomarkers, Aβ42, T-tau, or P-tau by ELISA, and assayed for soluble ADAM10 levels by western blotting.ResultsWe found that ADAM10 is present in human CSF as several distinct species: an immature form retaining the prodomain (proADAM10; ~ 80 kDa), a mature unprocessed full-length form (ADAM10f; ~ 55 kDa), and a truncated large soluble form released from the membrane (sADAM10; ~ 50 kDa). Fractionation by ultracentrifugation on sucrose density gradients showed that the ADAM10f and sADAM10 species form large complexes. Immunoblotting revealed a significant decrease in ADAM10f and sADAM10 in AD CSF compared to control CSF, while proADAM10 levels remained unaltered.ConclusionsSeveral forms of ADAM10 are present in CSF, mainly assembled as high-molecular weight complexes. The determination of the levels of mature forms of CSF-ADAM10 may be useful as a biomarker for AD.

Assessment of kallikrein 6 as a cross-sectional and longitudinal biomarker for Alzheimer\u2019s disease

BackgroundKallikrein 6 (KLK6) is known to be an age-related protease expressed at high levels in the central nervous system. It was previously shown to be involved in proteolysis of extracellular proteins implicated in neurodegenerative diseases such as Alzheimer’s disease (AD), prompting validation of KLK6 as a potential biomarker of disease. However, analyses of both plasma and cerebrospinal fluid (CSF) levels of KLK6 in patients with AD have been inconclusive. We present a detailed analysis of KLK6 in plasma and CSF in two separate cohorts in a cross-sectional and a longitudinal clinical setting.MethodsThe cross-sectional cohort included control subjects without dementia and patients with AD, and the longitudinal cohort included patients with MCI and patients with AD followed over a 2-year period. Plasma and CSF levels of KLK6 were quantified by use of a previously developed and validated enzyme-linked immunosorbent assay. Statistical analyses were performed to compare KLK6 levels between diagnostic groups and to identify potential associations between KLK6 level, age, apolipoprotein E (APOE) genotype, total apoE level and the classical CSF AD biomarkers.ResultsIn the cross-sectional setting, KLK6 levels in plasma but not in CSF were significantly higher in the AD group than in control subjects. CSF but not plasma KLK6 levels were positively correlated with age in both the cross-sectional and longitudinal settings. In both cohorts, the CSF KLK6 levels were significantly and positively correlated with the CSF levels of core AD biomarkers. Total plasma and CSF apoE levels were positively associated with KLK6 in the cross-sectional study. Finally, during the 2-year monitoring period of the longitudinal cohort, CSF KLK6 levels increased with disease progression over time in the investigated patient groups.ConclusionsIn two separate cohorts we have confirmed the previously reported correlation between age and CSF levels of KLK6. Increased plasma KLK6 levels in patients with AD with a more advanced disease stage suggest KLK6 as a potential biomarker in patients with AD with more severe dementia. Significant correlations between KLK6 levels and core CSF AD biomarkers suggest molecular links between KLK6 and AD-related pathological processes.

Role of cerebrospinal fluid lactate dehydrogenase and creatine phosphokinase in the differential diagnosis of bacterial, viral, and tubercular meningitis

Background: Meningitis is a common clinical problem, caused by various bacteria and viruses. Its etiology needs to be ascertained swiftly to institute appropriate therapy to prevent morbidity and mortality. In some cases, the precise etiological diagnosis cannot be ascertained in spite of thorough work up. Objectives: The present study was a prospective study undertaken in cases of meningitis admitted in the Medicine Ward of Burdwan Medical College and Hospital to determine the levels of cerebrospinal fluid (CSF) lactate dehydrogenase (LDH), and creatine phosphokinase (CPK) concentration and their possible roles in the etiological diagnosis of different kinds of meningitis. Materials and Methods: A prospective study was conducted on 150 patients, 50 patients of each of bacterial, viral, and tubercular meningitis, admitted in the Medicine Ward of Burdwan Medical College and Hospital. The values of CSF CPK, and LDH were calculated for each patient and variation of means was analyzed by appropriate biomedical software. The SPSS for the Windows 20.0 statistical package program has been used in the evaluation of the data. The quantitative data of the groups were compared using ANOVA with post hoc test for comparison. P < 0.05 was considered statistically significant. Results: It was found that CSF LDH, and CPK were significantly elevated in pyogenic meningitis and tubercular meningitis as compared to viral meningitis. The differences between the CSF LDH, and CSF-CPK values in differentiating any one of the three forms against another were found to be statistically significant. Conclusion: Thus, CSF CPK and LDH may serve as an useful marker for differentiation of etiology of meningitis at least in conjunction with the classical CSF markers and especially in the doubtful cases.

Cerebrospinal Fluid Levels of Amyloid Beta 1-43 Mirror 1-42 in Relation to Imaging Biomarkers of Alzheimer’s Disease

Introduction: Amyloid beta 1-43 (Aβ43), with its additional C-terminal threonine residue, is hypothesized to play a role in early Alzheimer’s disease pathology possibly different from that of amyloid beta 1-42 (Aβ42). Cerebrospinal fluid (CSF) Aβ43 has been suggested as a potential novel biomarker for predicting conversion from mild cognitive impairment (MCI) to dementia in Alzheimer’s disease. However, the relationship between CSF Aβ43 and established imaging biomarkers of Alzheimer’s disease has never been assessed.Materials and Methods: In this observational study, CSF Aβ43 was measured with ELISA in 89 subjects; 34 with subjective cognitive decline (SCD), 51 with MCI, and four with resolution of previous cognitive complaints. All subjects underwent structural MRI; 40 subjects on a 3T and 50 on a 1.5T scanner. Forty subjects, including 24 with SCD and 12 with MCI, underwent 18F-Flutemetamol PET. Seventy-eight subjects were assessed with 18F-fluorodeoxyglucose PET (21 SCD/7 MCI and 11 SCD/39 MCI on two different scanners). Ten subjects with SCD and 39 with MCI also underwent diffusion tensor imaging.Results: Cerebrospinal fluid Aβ43 was both alone and together with p-tau a significant predictor of the distinction between SCD and MCI. There was a marked difference in CSF Aβ43 between subjects with 18F-Flutemetamol PET scans visually interpreted as negative (37 pg/ml, n = 27) and positive (15 pg/ml, n = 9), p < 0.001. Both CSF Aβ43 and Aβ42 were negatively correlated with standardized uptake value ratios for all analyzed regions; CSF Aβ43 average rho -0.73, Aβ42 -0.74. Both CSF Aβ peptides correlated significantly with hippocampal volume, inferior parietal and frontal cortical thickness and axial diffusivity in the corticospinal tract. There was a trend toward CSF Aβ42 being better correlated with cortical glucose metabolism. None of the studied correlations between CSF Aβ43/42 and imaging biomarkers were significantly different for the two Aβ peptides when controlling for multiple testing.Conclusion: Cerebrospinal fluid Aβ43 appears to be strongly correlated with cerebral amyloid deposits in the same way as Aβ42, even in non-demented patients with only subjective cognitive complaints. Regarding imaging biomarkers, there is no evidence from the present study that CSF Aβ43 performs better than the classical CSF biomarker Aβ42 for distinguishing SCD and MCI.

Evaluation of α-synuclein as a novel cerebrospinal fluid biomarker in different forms of prion diseases

IntroductionAccurate diagnosis of prion diseases and discrimination from alternative dementias gain importance in the clinical routine, but partial overlap in cerebrospinal fluid (CSF) biomarkers impedes absolute discrimination in the differential diagnostic context. MethodsWe established the clinical parameters for prion disease diagnosis for the quantification of CSF α-synuclein in patients with sporadic (n = 234) and genetic (n = 56) prion diseases, in cases with cognitive impairment/dementia or neurodegenerative disease (n = 278), and in the neurologic control group (n = 111). ResultsAn optimal cutoff value of 680 pg/mL α-synuclein results in 94% sensitivity and 96% specificity when diagnosing sporadic Creutzfeldt-Jakob disease (CJD). Genetic CJD cases showed increased CSF α-synuclein values. No increased α-synuclein levels were detected in non-CJD cases with rapid progression course. DiscussionDetection of α-synuclein in the CSF of patients with suspected CJD is a valuable diagnostic test reaching almost full discrimination from non-prion disease cases. These data highlight the utility of CSF α-synuclein quantification in front of classical CSF biomarkers in clinical routine.

No diurnal variation of classical and candidate biomarkers of Alzheimer's disease in CSF.

BackgroundCerebrospinal fluid (CSF) biomarkers have gained increasing importance in the diagnostic work-up of Alzheimer’s disease (AD). The core CSF biomarkers related to AD pathology (Aβ42, t-tau and p-tau) are currently used in CSF diagnostics, while candidate markers of amyloid metabolism (Aβ38, Aβ40, sAPPα, sAPPβ), synaptic loss (neurogranin), neuroinflammation (YKL-40), neuronal damage (VILIP-1) and genetic risk (apolipoprotein E) are undergoing evaluation. Diurnal fluctuation in the concentration of CSF biomarkers has been reported and may represent a preanalytical confounding factor in the laboratory diagnosis of AD. The aim of the present study was to investigate the diurnal variability of classical and candidate CSF biomarkers in a cohort of neurosurgical patients carrying a CSF drainage.MethodSamples were collected from a cohort of 13 neurosurgical patients from either ventricular (n = 6) or lumbar (n = 7) CSF drainage at six time points during the day, 1–7 days following the neurosurgical intervention. Concentrations of the core biomarkers were determined by immunoassays.ResultsAlthough absolute values largely varied among subjects, none of the biomarkers showed significant diurnal variation. Site of drainage (lumbar vs. ventricular) did not influence this result. The different immunoassays used for tau and Aβ markers provided similar results.ConclusionTime of day at CSF collection does not ultimately affect the concentration levels of classical and candidate AD biomarkers. Similar trends were found when using different immunoassays, thus corroborating the consistency of the data.Electronic supplementary materialThe online version of this article (doi:10.1186/s13024-016-0130-3) contains supplementary material, which is available to authorized users.

Preanalytical Confounding Factors in the Analysis of Cerebrospinal Fluid Biomarkers for Alzheimer's Disease: The Issue of Diurnal Variation.

Given the growing use of cerebrospinal fluid (CSF) beta-amyloid (Aβ) and tau as biomarkers for early diagnosis of Alzheimer’s disease (AD), it is essential that the diagnostic procedures are standardized and the results comparable across different laboratories. Preanalytical factors are reported to be the cause of at least 50% of the total variability. Among them, diurnal variability is a key issue and may have an impact on the comparability of the values obtained. The available studies on this issue are not conclusive so far. Fluctuations of CSF biomarkers in young healthy volunteers have been previously reported, while subsequent studies have not confirmed those observations in older subjects, the ones most likely to receive this test. The observed differences in circadian rhythms need to be further assessed not only in classical CSF biomarkers but also in novel forthcoming biomarkers. In this review, the existing data on the issue of diurnal variations of CSF classical biomarkers for AD will be analyzed, also evaluating the available data on new possible biomarkers.

Diagnosing external ventricular drain-related ventriculitis by means of local inflammatory response: soluble triggering receptor expressed on myeloid cells-1.

IntroductionExternal ventricular drainage (EVD)-related ventriculitis is one of the most severe complications associated with the use of EVDs. Establishing an early and certain diagnosis can be difficult in critically ill patients. We performed this prospective study to evaluate the usefulness of soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) determination in cerebrospinal fluid (CSF) in the diagnosis of ventriculitis.MethodsA prospective observational study was conducted of 73 consecutive patients with EVD. Samples of CSF for culture, cytobiochemical analysis and sTREM-1 determination were extracted three times a week. Ventriculitis diagnosis required a combination of microbiological, cytobiochemical and clinical criteria.ResultsSeventy-three consecutive patients were included. EVD-related ventriculitis was diagnosed in six patients and EVD-colonization in ten patients. Patients without clinical or microbiological findings were considered controls. The median CSF sTREM-1 was 4,320 pg/ml (interquartile range (IQR): 2,987 to 4,886) versus 266 pg/ml (118 to 689); P <0.001. There were no differences when comparing colonized-patients and controls. The best cut-off sTREM-1 value for the diagnosis of ventriculitis was 2,388.79 pg/ml (sensitivity 100%, specificity 98.5%, positive predictive value 85.71%, negative predictive value 100%). CSF proteins, glucose and the ratio CSF/serum glucose were also significantly different (P = 0.001). Serum biomarkers were not useful to diagnose EVD-related infection. These results were confirmed by a case–control study with ventriculitis patients (cases) and non-ventriculitis (control subjects) matched by age, comorbidities, severity scales and EVD duration (P = 0.004).ConclusionsCSF sTREM-1 was useful in the diagnosis of ventriculitis, in a similar measure to classical CSF parameters. Furthermore, CSF sTREM-1 could prove the diagnosis in uncertain cases and discriminate between EVD-colonization and infection.

Cerebrospinal fluid physiology: visualization of cerebrospinal fluid dynamics using the magnetic resonance imaging Time-Spatial Inversion Pulse method.

Previously there have been no methods for directly tracing the flow of cerebrospinal fluid (CSF) under physiological conditions, and the circulation of CSF has therefore been studied and visualized by injecting a radioactively labeled tracer or contrast medium visible in x-ray images. The newly developed Time-Spatial Inversion Pulse (Time-SLIP) method makes it possible to directly visualize the flow of CSF using magnetic resonance imaging (MRI), permitting CSF dynamics to be depicted in a certain time frame. The CSF dynamics visualized using Time-SLIP has been found to differ markedly from the classical CSF circulation theory described in medical textbooks. It can be said that research on CSF dynamics has advanced to the next stage with the use of this innovative imaging method. Obtaining a more accurate understanding of normal CSF physiology and pathophysiology should lead to improved diagnostic accuracy, permit the identification of new etiological factors in a variety of diseases, and promote the development of new therapeutic approaches.

Toward a Predictive Model of Alzheimer’s Disease Progression Using Capillary Electrophoresis–Mass Spectrometry Metabolomics

Alzheimer's disease (AD) is the most prevalent form of dementia with an estimated worldwide prevalence of over 30 million people, and its incidence is expected to increase dramatically with an increasing elderly population. Up until now, cerebrospinal fluid (CSF) has been the preferred sample to investigate central nervous system (CNS) disorders since its composition is directly related to metabolite production in the brain. In this work, a nontargeted metabolomic approach based on capillary electrophoresis-mass spectrometry (CE-MS) is developed to examine metabolic differences in CSF samples from subjects with different cognitive status related to AD progression. To do this, CSF samples from 85 subjects were obtained from patients with (i) subjective cognitive impairment (SCI, i.e. control group), (ii) mild cognitive impairment (MCI) which remained stable after a follow-up period of 2 years, (iii) MCI which progressed to AD within a 2-year time after the initial MCI diagnostic and, (iv) diagnosed AD. A prediction model for AD progression using multivariate statistical analysis based on CE-MS metabolomics of CSF samples was obtained using 73 CSF samples. Using our model, we were able to correctly classify 97-100% of the samples in the diagnostic groups. The prediction power was confirmed in a blind small test set of 12 CSF samples, reaching a 83% of diagnostic accuracy. The obtained predictive values were higher than those reported with classical CSF AD biomarkers (Aβ42 and tau) but need to be confirmed in larger samples cohorts. Choline, dimethylarginine, arginine, valine, proline, serine, histidine, creatine, carnitine, and suberylglycine were identified as possible disease progression biomarkers. Our results suggest that CE-MS metabolomics of CSF samples can be a useful tool to predict AD progression.

Diagnosis of Listeria monocytogenes Meningoencephalitis by Real-Time PCR for the hly Gene

Listeria monocytogenes is a bacterial pathogen that can invade the central nervous system (CNS), causing meningoencephalitis and brain abscesses. The diagnosis of CNS listeriosis, based on the isolation of the bacteria in the cerebrospinal fluid (CSF), can be difficult because of previous antibiotic treatment and a low number of bacteria in the CSF. To improve the sensitivity of microbiological diagnosis, we have developed a real-time PCR assay for detecting and quantifying L. monocytogenes DNA in the CSF. The designed primers specifically amplify the L. monocytogenes hly gene, which encodes listeriolysin O, a pore-forming cytolysin. The PCR assay for the hly gene (PCR-hly) provides reproducible quantitative results over a wide dynamic range of concentrations and was highly sensitive while detecting a single gene copy/ml. By assaying a large panel of bacterial species, including species secreting pore-forming cytolysin, we determined the specificity of the PCR-hly, which exclusively detects the L. monocytogenes DNA. We then analyzed 214 CSF samples from patients suspected of having CNS listeriosis. PCR-hly was positive in all cases in which L. monocytogenes was isolated by culture. Positive PCR-hly of the CSF was also obtained for five additional, clinically confirmed cases of CNS listeriosis for which bacterial cultures were negative presumably due to previous treatment with antibiotics. As a complement to classical bacteriological CSF culture, our designed real-time PCR-hly assay proved to be valuable by enhancing the rapidity and the accuracy of the diagnosis of CNS infection by L. monocytogenes. In addition, the quantitative results provided may, in some instances, be useful for the follow-up of patients under treatment.