Individual Cerebrospinal Fluid Research Articles

Significant individual variation in cardiac-cycle-linked cerebrospinal fluid production following subarachnoid hemorrhage

BackgroundSpontaneous subarachnoid hemorrhage (SAH) often results in altered cerebrospinal fluid (CSF) flow and secondary hydrocephalus, yet the mechanisms behind these phenomena remain poorly understood. This study aimed to elucidate the impact of SAH on individual CSF flow patterns and their association with secondary hydrocephalus.MethodsIn patients who had experienced SAH, changes in CSF flow were assessed using cardiac-gated phase-contrast magnetic resonance imaging (PC-MRI) at the Sylvian aqueduct and cranio-cervical junction (CCJ). Within these regions of interest, volumetric CSF flow was determined for every pixel and net CSF flow volume and direction calculated. The presence of acute or chronic hydrocephalus was deemed from ventriculomegaly and need of CSF diversion. For comparison, we included healthy subjects and patients examined for different CSF diseases.ResultsTwenty-four SAH patients were enrolled, revealing a heterogeneous array of CSF flow alterations at the Sylvian aqueduct. The cardiac-cycle-linked CSF net flow in Sylvian aqueduct differed from the traditional figures of ventricular CSF production about 0.30–0.40 mL/min. In 15 out of 24 patients (62.5%), net CSF flow was retrograde from the fourth to the third and lateral ventricles, while it was upward at the cranio-cervical junction in 2 out of 2 patients (100%). The diverse CSF flow metrics did not distinguish between individuals with acute or chronic secondary hydrocephalus. In comparison, 4/4 healthy subjects showed antegrade net CSF flow in the Sylvian aqueduct and net upward CSF flow in CCJ. These net CSF flow measures also showed interindividual variability among other patients with CSF diseases.ConclusionsThere is considerable inter-individual variation in net CSF flow rates following SAH. Net CSF flow in the Sylvian aqueduct differs markedly from the traditional ventricular CSF production rates of 0.30–0.40 mL/min in SAH patients, but less so in healthy subjects. Furthermore, the cardiac-cycle-linked net CSF flow rates in Sylvian aqueduct and CCJ suggest an important role of extra-ventricular CSF production.

Alzheimer's Disease-Related Analytes Amyloid-β and Tau in Perilymph: Correlation With Patient Age and Cognitive Score.

To describe the collection methods for perilymph fluid biopsy during cochlear implantation, detect levels of amyloid β 42 and 40 (Aβ42 and Aβ40), and total tau (tTau) analytes with a high-precision assay, to compare these levels with patient age and Montreal Cognitive Assessment (MoCA) scores, and explore potential mechanisms and relationships with otic pathology. Prospective study. Tertiary referral center. Perilymph was collected from 25 patients using polyimide tubing to avoid amyloid adherence to glass, and analyzed with a single-molecule array advanced digital enzyme-linked immunosorbent assay platform for Aβ40, Aβ42, and tTau. Cognition was assessed by MoCA. Perilymph volumes ranged from ∼1 to 13 µL, with analyte concentrations spanning 2.67 to 1088.26 pg/mL. All samples had detectable levels of tTau, Aβ40, and Aβ42, with a significant positive correlation between Aβ42 and Aβ40 levels. Levels of Aβ42, Aβ40, and tTau were positively correlated with age, while MoCA scores were inversely correlated with age. tTau and Aβ42/Aβ40-ratios were significantly correlated with MoCA scores. Alzheimer's disease-associated peptides Aβ42, Aβ40, and tau analytes are detectable in human perilymph at levels approximately 10-fold lower than those found in cerebrospinal fluid (CSF). These species increase with age and correlate with cognitive impairment indicators, suggesting their potential utility as biomarkers for cognitive impairment in patients undergoing cochlear implantation. Future research should investigate the origin of these analytes in the perilymph and their potential links to inner ear pathologies and hearing loss, as well as their relationships to CSF and plasma levels in individuals.

Interval-specific likelihood ratios and probability-based models for interpreting combined CSF biomarkers for Alzheimer’s disease

BackgroundIn Alzheimer’s disease (AD) diagnosis, a cerebrospinal fluid (CSF) biomarker panel is commonly interpreted with binary cutoff values. However, these values are not generic and do not reflect the disease continuum. We explored the use of interval-specific likelihood ratios (LRs) and probability-based models for AD using a CSF biomarker panel. MethodsCSF biomarker (Aβ1-42, tTau and pTau181) data for both a clinical discovery cohort of 241 patients (measured with INNOTEST) and a clinical validation cohort of 129 patients (measured with EUROIMMUN), both including AD and non-AD dementia/cognitive complaints were retrospectively retrieved in a single-center study. Interval-specific LRs for AD were calculated and validated for univariate and combined (Aβ1-42/tTau and pTau181) biomarkers, and a continuous bivariate probability-based model for AD, plotting Aβ1-42/tTau versus pTau181 was constructed and validated. ResultsLR for AD increased as individual CSF biomarker values deviated from normal. Interval-specific LRs of a combined biomarker model showed that once one biomarker became abnormal, LRs increased even further when another biomarker largely deviated from normal, as replicated in the validation cohort. A bivariate probability-based model predicted AD with a validated accuracy of 88% on a continuous scale. ConclusionsInterval-specific LRs in a combined biomarker model and prediction of AD using a continuous bivariate biomarker probability-based model, offer a more meaningful interpretation of CSF AD biomarkers on a (semi-)continuous scale with respect to the post-test probability of AD across different assays and cohorts.

Constitutive knockout of interleukin-6 ameliorates memory deficits and entorhinal astrocytosis in the MRL/lpr mouse model of neuropsychiatric lupus.

Neuropsychiatric lupus (NPSLE) describes the cognitive, memory, and affective emotional burdens faced by many lupus patients. While NPSLE's pathogenesis has not been fully elucidated, clinical imaging studies and cerebrospinal fluid (CSF) findings, namely elevated interleukin-6 (IL-6) levels, point to ongoing neuroinflammation in affected patients. Not only linked to systemic autoimmunity, IL-6 can also activate neurotoxic glial cells the brain. A prior pre-clinical study demonstrated that IL-6 can acutely induce a loss of sucrose preference; the present study sought to assess the necessity of chronic IL-6 exposure in the NPSLE-like disease of MRL/lpr lupus mice. We quantified 1308 proteins in individual serum or pooled CSF samples from MRL/lpr and control MRL/mpj mice using protein microarrays. Serum IL-6 levels were plotted against characteristic NPSLE neurobehavioral deficits. Next, IL-6 knockout MRL/lpr (IL-6 KO; n = 15) and IL-6 wildtype MRL/lpr mice (IL-6 WT; n = 15) underwent behavioral testing, focusing on murine correlates of learning and memory deficits, depression, and anxiety. Using qPCR, we quantified the expression of inflammatory genes in the cortex and hippocampus of MRL/lpr IL-6 KO and WT mice. Immunofluorescent staining was performed to quantify numbers of microglia (Iba1 +) and astrocytes (GFAP +) in multiple cortical regions, the hippocampus, and the amygdala. MRL/lpr CSF analyses revealed increases in IL-17, MCP-1, TNF-α, and IL-6 (a priori p-value < 0.1). Serum levels of IL-6 correlated with learning and memory performance (R2 = 0.58; p = 0.03), but not motivated behavior, in MRL/lpr mice. Compared to MRL/lpr IL-6 WT, IL-6 KO mice exhibited improved novelty preference on object placement (45.4% vs 60.2%, p < 0.0001) and object recognition (48.9% vs 67.9%, p = 0.002) but equivalent performance in tests for anxiety-like disease and depression-like behavior. IL-6 KO mice displayed decreased cortical expression of aif1 (microglia; p = 0.049) and gfap (astrocytes; p = 0.044). Correspondingly, IL-6 KO mice exhibited decreased density of GFAP + cells compared to IL-6 WT in the entorhinal cortex (89 vs 148cells/mm2, p = 0.037), an area vital to memory. The inflammatory composition of MRL/lpr CSF resembles that of human NPSLE patients. Increased in the CNS, IL-6 is necessary to the development of learning and memory deficits in the MRL/lpr model of NPSLE. Furthermore, the stimulation of entorhinal astrocytosis appears to be a key mechanism by which IL-6 promotes these behavioral deficits.

The Immune Signature of CSF in Multiple Sclerosis with and without Oligoclonal Bands: A Machine Learning Approach to Proximity Extension Assay Analysis.

Early diagnosis of multiple sclerosis (MS) relies on clinical evaluation, magnetic resonance imaging (MRI), and cerebrospinal fluid (CSF) analysis. Reliable biomarkers are needed to differentiate MS from other neurological conditions and to define the underlying pathogenesis. This study aimed to comprehensively profile immune activation biomarkers in the CSF of individuals with MS and explore distinct signatures between MS with and without oligoclonal bands (OCB). A total of 118 subjects, including relapsing-remitting MS with OCB (MS OCB+) (n = 58), without OCB (MS OCB-) (n = 24), and controls with other neurological diseases (OND) (n = 36), were included. CSF samples were analyzed by means of proximity extension assay (PEA) for quantifying 92 immune-related proteins. Neurofilament light chain (NfL), a marker of axonal damage, was also measured. Machine learning techniques were employed to identify biomarker panels differentiating MS with and without OCB from controls. Analyses were performed by splitting the cohort into a training and a validation set. CSF CD5 and IL-12B exhibited the highest discriminatory power in differentiating MS from controls. CSF MIP-1-alpha, CD5, CXCL10, CCL23 and CXCL9 were positively correlated with NfL. Multivariate models were developed to distinguish MS OCB+ and MS OCB- from controls. The model for MS OCB+ included IL-12B, CD5, CX3CL1, FGF-19, CST5, MCP-1 (91% sensitivity and 94% specificity in the training set, 81% sensitivity, and 94% specificity in the validation set). The model for MS OCB- included CX3CL1, CD5, NfL, CCL4 and OPG (87% sensitivity and 80% specificity in the training set, 56% sensitivity and 48% specificity in the validation set). Comprehensive immune profiling of CSF biomarkers in MS revealed distinct pathophysiological signatures associated with OCB status. The identified biomarker panels, enriched in T cell activation markers and immune mediators, hold promise for improved diagnostic accuracy and insights into MS pathogenesis.

Head‐to‐head comparison of CSF AD biomarker assays: fully‐automated high‐throughput platforms (ECLIA and CLEIA) vs ELISA

AbstractBackgroundBiomarkers in cerebrospinal fluid (CSF) can help to diagnose Alzheimer’s disease (AD) and classify patients according to the amyloid/tau/neurodegeneration (ATN) research framework.MethodWe directly compared the performance of three different testing systems, i..e. traditional solid‐phase sandwich ELISA assays (Innotest®, Fujirebio Europe N.V., Gent, Belgium, and IBL, Minneapolis, USA), a fully automated electrochemiluminescence immunoassays (ECLIA) platform (Elecsys® CSF assays measured on the cobas e 411 analyzer, Roche Diagnostics International Ltd, Rotkreuz, Switzerland), and a fully automated chemiluminescent enzyme immunoassays (CLEIA) platform (Lumipulse® G600II, Fujirebio Europe N.V., Gent, Belgium), in 50 early AD patients (64±8.1y) and 25 cognitively unimpaired (CU) controls (65±9.4y)] from the same cohort. Individual CSF biomarkers Aβ42, Aβ40, pTau181 and tTau were measured using all systems. Ratios for pTau181/Aβ42, tTau/Aβ42, Aβ42/Aβ40, pTau181/Aβ42/Aβ40, tTau/Aβ42/Aβ40, pTau181/Aβ40, and tTau/Aβ40 were calculated.ResultAcross all systems, biomarkers and their ratios accurately distinguished AD patients from CU in a comparable manner: ROC: AUCs &gt;0.96 (upper bound of CI:1.0)], except for ELISA Aβ42/Aβ40 [AUC = 0.948 (CI: 0.901‐0.995)]; according to Youden Index (YI)‐derived optimal cut‐offs, sensitivity and specificity were comparably high. YI cut‐offs and manufacturer (MA) cut‐offs were highly consistent. However, for the ECLIA platform (Elecsys®), the YI cut‐off led to significantly higher sensitivity for tTau (97.8% [0.88‐1.00%]/ 80.9%) and pTau181 (97.8% [0.88‐1.00%]/ 83.0%), and higher specificity for Aβ42 (96.0% [79‐100%]/ 76.0%), than MA cut‐off, maybe due to high prevalence of AD. The two fully automated platforms showed markedly reduced maximal coefficients of variation (CV) than ELISA.ConclusionIn addition to increased time efficiency, fully automated platforms showed more consistent results than ELISA assays which favor single analyte measurements. Improved accuracy using YI cut‐offs suggests that in‐house cut‐offs might be important for optimal performance. The two fully automated platforms had comparable accuracy. Thus, the platform of choice might depend on the user’s needs; for instance, the pTau181/Aβ42 ratio (Elecsys®; (AUC: 1.0 [1.0‐1.0], sensitivity 100%, specificity 100%)) combines the two AD hallmarks (A and T) in one test. For ATN classification, the Aβ42/Aβ40 ratio (Lumipulse®, AUC: 1.0 [1.0‐1.0], sensitivity 100%, specificity 100%) might be a more accurate marker for amyloid positivity (A+) than Aβ42 alone.

Association between mitochondrial DNA levels and depression: a systematic review and meta-analysis

BackgroundMitochondrial dysfunction leading to disturbances in energy metabolism has emerged as one of the risk factors in the pathogenesis of depression. Numerous studies have identified alterations in the content of mitochondrial DNA (mtDNA) in peripheral blood and cerebrospinal fluid of individuals with depression. Researchers have sought to establish a clear association between mtDNA and depression. Consequently, we conducted a comprehensive meta-analysis to assess the existing evidence regarding the impact of mtDNA on depression.MethodsThis study conducted a thorough search of the following databases up to March 13, 2023: PubMed, Embase, the Cochrane Library, the Web of Science, Wanfang Database, SINOMED, the China Science and Technology Journal Database, and China National Knowledge Infrastructure. The meta-analysis was carried out using RevMan (version 5.4) and Stata (version 16.0) software. In addition, publication bias was assessed with funnel plots, Begg’s test and Egger’s test.ResultsOur analysis included data from 10 articles, including 12 studies for further examination. A total of 1400 participants were included in this study, comprising 709 (including 300 males and 409 females) patients with depression and 691 (including 303 males and 388 females) healthy controls. The average age of depressed patients was (42.98 ± 2.55) years, and the average age of healthy people was (41.71 ± 2.6) years. The scales used to assess outcomes are Hamilton-rating scale for Depression(4 articles), Montgomery-Asberg Depression Rating Scale(3 articles), and Mini-Internatioal Neuropsychiatric Interview (1 articles). The meta-analysis revealed significantly higher levels of mtDNA in circulating blood samples and skin fibroblasts of individuals with depression in comparison to healthy controls [standardized mean difference(SMD) = 0.42, 95% confidence intervals(CI): 0.16, 0.67].ConclusionsOur study concludes that there is a significant (p < 0.05) increase in mtDNA levels in serum, plasma, and cerebrospinal fluid in individuals with depression. These findings suggest that mtDNA could serve as a potential biomarker for diagnosing depression.Registration numberPROSPERO CRD42023414285.

Associations Between Plasma, Imaging, and Cerebrospinal Fluid Biomarkers with Driving Behavior and Cognitive Tests: Implications for Biomarker Usefulness.

Declines in instrumental activities of daily living like driving are hallmarks sequelae of Alzheimer's disease (AD). Although driving has been shown to be associated with traditional imaging and cerebrospinal fluid (CSF) biomarkers, it is possible that some biomarkers have stronger associations with specific aspects of driving behavior. Furthermore, associations between newer plasma biomarkers and driving behaviors are unknown. This study assessed the extent to which individual plasma, imaging, and CSF biomarkers are related to specific driving behaviors and cognitive functions among cognitively normal older adults. We analyzed naturalistic driving behavior from cognitively healthy older drivers (N = 167, 47% female, mean age = 73.3 years). All participants had driving, clinical, and demographic data and completed biomarker testing, including imaging, CSF, and/or plasma, within two years of study commencement. AD biomarkers were associated with different characteristics of driving and cognitive functioning within the same individuals. Elevated levels of plasma Aβ40 were associated with more speeding incidents, higher levels of CSF tau were related to shorter duration of trips, and higher CSF neurofilament light chain values were associated with traveling shorter distances, smaller radius of gyration, and fewer trips at night. We demonstrated that plasma, like CSF and imaging biomarkers, were helpful in predicting everyday driving behaviors. These findings suggest that different biomarkers offer complementary information with respect to driving behaviors. These distinct relationships may help in understanding how different biological changes that occur during the preclinical stage of AD can impact various sensorimotor and cognitive processes.

Elevated amyloid beta peptides and total tau in cerebrospinal fluid in individuals with Creatine transporter deficiency

BackgroundCreatine transporter deficiency (CTD) is a rare X-linked disorder of creatine transport caused by pathogenic variants in SLC6A8 (Xq28). The disorder is marked by developmental delay, especially speech delay. The biomarkers Aβ40, Aβ42 and total tau are abnormal in Alzheimer disease (AD), a common neurodegenerative disorder pathologically characterized by Aβ peptide containing amyloid plaques and tau neurofibrillary tangles. Although CTD results in neuronal energy deficiency, the pathological processes underlying the CTD phenotype are not fully characterized. MethodsCerebral spinal fluid (CSF) was collected as an optional part of a natural history study of CTD. Aβ40, Aβ42 and total tau levels were quantified in CSF from individuals with CTD and from age-appropriate comparison samples. Neuro3-Plex enzyme-linked immunoassay was performed on a Quanterix SR-X instrument. The Vineland Adaptive Behavior Scale, 3rd Edition was used to determine an overall Adaptive Behavior Composite (ABC) standard score. ResultsCSF from 12 individuals with CTD and 23 age appropriate non-CTD comparison samples were analyzed. We found that levels of total tau [t(32) = 4.05, p = 0.0003], Aβ40 [t(31) = 6.11, p < 0.0001], and Aβ42 [t(32) = 3.20, p = 0.003] were elevated in the participants with CTD relative to the comparison group. Additionally, except for one individual that we considered an outlier, all three biomarkers correlated inversely with the adaptive behavior score (total tau: ρ = −0.60 [−0.88, 0.005]; Aβ40: ρ = −0.67 [−0.91, −0.12]; Aβ42: ρ = −0.62 [−0.89, −0.02]). ConclusionWe describe here the novel finding of elevated protein biomarkers in the CSF of individuals with CTD. Aβ40, Aβ42 and total tau are markedly elevated in individuals with CTD compared to comparison samples, and increased levels of these biomarkers inversely correlated with ABC scores. We hypothesize that elevated CSF levels of Aβ40 and Aβ42 are due to cellular energy deficiency. Elevated CSF total tau levels may indicate ongoing neuronal damage. The observed inverse correlation of Vineland ABC scores with increased biomarker levels needs to be confirmed in a larger CTD cohort; however, our observation of increased Aβ40, Aβ42 and total tau levels in CSF from individuals with CTD may provide insight into pathological mechanisms contributing to the CTD phenotype and may prove useful as supportive data in future therapeutic trials.

Cerebrospinal fluid biomarkers for normal pressure hydrocephalus

Idiopathic normal pressure hydrocephalus (iNPH) is a potentially reversible disease characterized by gait disturbance, a frontal-subcortical pattern of cognitive impairment, and urinary incontinence with disproportionately enlarged ventricles. Its prevalence rises with aging. Patients with iNPH are treated with shunt placement, and predicting the surgical outcome is not always easy. Cerebrospinal fluid (CSF) has inevitably been an attractive matrix for biomarker identification in both the diagnosis and treatment of iNPH and the disease may have individual CSF composition changes. Additionally, in order to detect iNPH earlier, implement treatment faster, and have better therapeutic effects, the incorporation of CSF biomarkers in the diagnostic and treatment process is essential. In this review, CSF biomarkers of Alzheimer’s disease pathology, axonal damage, neuronal damage, astroglial dysfunction, myelin damage, inflammation, and extracellular matrix protein remodeling have been evaluated and tried to emphasize those of which have highly consistent findings in the studies. CSF samples collected only at a single time point may not be sufficient to identify a promising marker in such a dynamic and used to be a common comorbid condition to other neurodegenerative diseases. These confounders demonstrate the limitations of using solely biomarkers to diagnose the disease and to foresee the outcome of the shunt surgery. Therefore, CSF samples collected antemortem at different time points and biopsy-confirmed iNPH patients with and without other neurodegenerative diseases would fill the gaps in identifying a valid biomarker. Longitudinal observations of shunt responders and non-responders in multicenter with well-defined cohorts are also needed to understand iNPH-specific markers. Finally, biomarkers of a bioinformatic approach that includes micro-RNAs, extracellular vesicles, metabolomics, the microbiome, or else are warranted to identify novel and useful diagnostic and prognostic biomarker tools in iNPH.

Altered angiogenic and neuroinflammatory markers in peripartum individuals with and without severe preeclampsia compared to non-pregnant adults (P3-5.008)

<h3>Objective:</h3> To characterize angiogenic and neuroinflammatory cytokine levels in serum and cerebrospinal fluid (CSF) of peripartum individuals with and without preeclampsia. <h3>Background:</h3> Preeclampsia, a hypertensive disorder of pregnancy associated with systemic endothelial dysfunction, carries high risk of neurovascular complications. Preliminary studies suggest maternal blood-brain barrier (BBB) dysfunction in preeclampsia. <h3>Design/Methods:</h3> We analyzed serum from 26 peripartum participants (13 severe preeclampsia, 13 normotensive controls), of whom 13 participants (7 cases, 6 controls) also had CSF available for analysis. ProcartaPlex and ELISA immunoassays were used to quantify angiogenic and neuroinflammatory proteins implicated in BBB dysfunction in serum and separately CSF. We used t-test or Wilcoxon tests to compare levels between participants with and without preeclampsia. We next compared our values to published normative values for healthy non-pregnant adults. We did not correct for multiple comparisons for this exploratory analysis. <h3>Results:</h3> We found no statistically significant difference in serum or CSF levels of angiogenic (VEGF, PlGF, and sFLT1) or neuroinflammatory (CCL5/RANTES, GM-CSF, CXCL10) markers between normotensive peripartum controls and those with severe preeclampsia. Compared to historical non-pregnant controls, serum levels in both cases and controls were lower of VEGF (p&lt;0.005 for both comparisons), CCL5 (p&lt;0.002 for both comparisons), and CXCL10 (p&lt;0.0.002 for both comparisons), and sFLT1 and GM-CSF were higher (p&lt;0.02 for all comparisons). In CSF analyses, the concentration of CXCL10 was significantly lower (p&lt;0.002 for both comparisons) and sFLT1 was significantly higher (p&lt;0.03 for both comparisons), compared with non-pregnant adult reference values. <h3>Conclusions:</h3> In this pilot study, angiogenic and neuroinflammatory profiles in the serum and CSF of peripartum individuals with and without severe preeclampsia were not significantly different. However, when compared with normative values for healthy non-pregnant adults, peripartum individuals demonstrate alterations in factors regulating BBB permeability. Our results suggest that the peripartum state may be associated with changes in BBB regulation, regardless of preeclampsia diagnosis. <b>Disclosure:</b> Miss Haghighi has nothing to disclose. Ms. Tuohy has nothing to disclose. Natalie Bello has nothing to disclose. Dr. Booker has nothing to disclose. Dr. Miltiades has nothing to disclose. Ronald Wapner has nothing to disclose. The institution of Dr. Marshall has received research support from NIH. Dr. Marshall has received publishing royalties from a publication relating to health care. Dr. Miller has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Elsevier. Dr. Miller has received personal compensation in the range of $500-$4,999 for serving as an Expert Witness for Argionis and Associates LLC. The institution of Dr. Miller has received research support from National Institutes of Health.

Quantifying mutant huntingtin protein in human cerebrospinal fluid to support the development of huntingtin-lowering therapies

Huntington’s disease (HD) is caused by a cytosine adenine guanine-repeat expansion in the huntingtin gene. This results in the production of toxic mutant huntingtin protein (mHTT), which has an elongated polyglutamine (polyQ) stretch near the protein’s N-terminal end. The pharmacological lowering of mHTT expression in the brain targets the underlying driver of HD and is one of the principal therapeutic strategies being pursued to slow or stop disease progression. This report describes the characterisation and validation of an assay designed to quantify mHTT in the cerebrospinal fluid of individuals with HD, for use in registrational clinical trials. The assay was optimised, and its performance was characterised with recombinant huntingtin protein (HTT) varying in overall and polyQ-repeat length. The assay was successfully validated by two independent laboratories in regulated bioanalytical environments and showed a steep signal increase as the polyQ stretch of recombinant HTTs pivoted from wild-type to mutant protein forms. Linear mixed effects modelling confirmed highly parallel concentration–response curves for HTTs, with only a minor impact of individual slopes of the concentration–response for different HTTs (typically < 5% of the overall slope). This implies an equivalent quantitative signal behaviour for HTTs with differing polyQ-repeat lengths. The reported method may be a reliable biomarker tool with relevance across the spectrum of HD mutations, which can facilitate the clinical development of HTT-lowering therapies in HD.

Cerebrospinal Fluid and Brain Proteoforms of the Granin Neuropeptide Family in Alzheimer's Disease.

The granin neuropeptide family is composed of acidic secretory signaling molecules that act throughout the nervous system to help modulate synaptic signaling and neural activity. Granin neuropeptides have been shown to be dysregulated in different forms of dementia, including Alzheimer's disease (AD). Recent studies have suggested that the granin neuropeptides and their protease-cleaved bioactive peptides (proteoforms) may act as both powerful drivers of gene expression and as a biomarker of synaptic health in AD. The complexity of granin proteoforms in human cerebrospinal fluid (CSF) and brain tissue has not been directly addressed. We developed a reliable nontryptic mass spectrometry assay to comprehensively map and quantify endogenous neuropeptide proteoforms in the brain and CSF of individuals diagnosed with mild cognitive impairment and dementia due to AD compared to healthy controls, individuals with preserved cognition despite AD pathology ("Resilient"), and those with impaired cognition but no AD or other discernible pathology ("Frail"). We drew associations between neuropeptide proteoforms, cognitive status, and AD pathology values. Decreased levels of VGF proteoforms were observed in CSF and brain tissue from individuals with AD compared to controls, while select proteoforms from chromogranin A showed the opposite effect. To address mechanisms of neuropeptide proteoform regulation, we showed that the proteases Calpain-1 and Cathepsin S can cleave chromogranin A, secretogranin-1, and VGF into proteoforms found in both the brain and CSF. We were unable to demonstrate differences in protease abundance in protein extracts from matched brains, suggesting that regulation may occur at the level of transcription.

1,2-13C2-Glucose Tracing Approach to Assess Metabolic Alterations of Human Monocytes under Neuroinflammatory Conditions.

Neuroinflammation is one of the common features in most neurological diseases including multiple sclerosis (MScl) and neurodegenerative diseases such as Alzheimer's disease (AD). It is associated with local brain inflammation, microglial activation, and infiltration of peripheral immune cells into cerebrospinal fluid (CSF) and the central nervous system (CNS). It has been shown that the diversity of phenotypic changes in monocytes in CSF relates to neuroinflammation. It remains to be investigated whether these phenotypic changes are associated with functional or metabolic alteration, which may give a hint to their function or changes in cell states, e.g., cell activation. In this article, we investigate whether major metabolic pathways of blood monocytes alter after exposure to CSF of healthy individuals or patients with AD or MScl. Our findings show a significant alteration of the metabolism of monocytes treated with CSF from patients and healthy donors, including higher production of citric acid and glutamine, suggesting a more active glycolysis and tricarboxylic acid (TCA) cycle and reduced production of glycine and serine. These alterations suggest metabolic reprogramming of monocytes, possibly related to the change of compartment (from blood to CSF) and/or disease-related. Moreover, the levels of serine differ between AD and MScl, suggesting different phenotypic alterations between diseases.

Assessing Risk of Incident Cognitive Impairment Using Stages of Objective Memory Impairment (SOMI) and Cerebrospinal Fluid

AbstractBackgroundThe asymptomatic period for persons with preclinical Alzheimer’s disease (AD) lasts for several years despite the presence of AD biomarkers. These biomarkers are critical for disease detection and monitoring, but collection is burdensome and costly. Sensitive cognitive measures such as Stages of Objective Memory Impairment (SOMI) may be a low‐cost alternative or adjunctive marker of disease‐progression risk. Here, we used longitudinal data from the Knight Alzheimer’s Disease Research Center to investigate the odds of disease progression associated with baseline SOMI stage and cerebrospinal fluid (CSF) biomarkers of Aβ42/Aβ40 ratio, p‐tau181, and t‐tau.MethodsWe used data from 617 cognitively unimpaired participants with baseline Clinical Dementia Rating (CDR) of 0, CSF measures, and longitudinal Free and Cued Selective Reminding Test (FCSRT) scores used to classify participants into different SOMI stages (Table 1). We examined the association between SOMI stage, CSF biomarkers, and incident cognitive impairment based on time to conversion from CDR of 0 to CDR&gt;0 (incident cognitive impairment) using Cox Models.ResultsParticipants, at enrollment (Table 2), were on average 67.2 (SD = 9.4) years old, 56.6% were female, and had average 7.5 years of follow‐up (range 1‐18). At baseline, 325 (52.7%) were SOMI‐0, 206 (33.4%) were SOMI‐1, 64 (10.4%) were SOMI‐2, and 22 (3.6%) were SOMI‐3 or ‐4 (merged groups). A total of 127 (20.6%) individuals converted to CDR&gt;0. The Cox proportional hazards regression models indicated that in comparison with individuals in SOMI‐0 stage, those in SOMI‐3/4 stage were more than twice as likely to show disease progression (HR=2.43 (95% CI, 1.21‐4.89, p=0.013)) (Table 3). Adding individual CSF biomarkers to the models did not affect the association of SOMI‐3/4 with incident cognitive impairment (p&lt;0.05 for all). In models that included SOMI stages and all CSF biomarkers, SOMI‐3/4 (HR=2.13, 95% CI 1.07‐4.12, p=0.033) Aβ42/Aβ40 (HR=9.76e‐6, 95% CI=2.70e‐10 ‐ 0.35, p=0.031) and t‐tau (HR=1.001, 95% CI=1.000‐1.002, p=0.018), but not p‐tau (p=0.645), showed significant association with incident cognitive impairment.ConclusionsSOMI‐3/4 predicts incident cognitive impairment (change in CDR) independently from CSF AD biomarkers. These results support the utility of SOMI stage as an early marker of incident cognitive impairment.

Pro-Inflammatory and Anti-Inflammatory Cytokines Levels are Significantly Altered in Cerebrospinal Fluid of Unruptured Intracranial Aneurysm (UIA) Patients

Identifying all the relevant "players" in the formation and development of brain aneurysms may help understand the mechanisms responsible for the formation of an aneurysm, as well as in the search for non-invasive targets for aneurysm pharmacotherapy. The evaluation of the concentration of pro-inflammatory and anti-inflammatory cytokines in cerebrospinal fluid (CSF) and serum of patients with unruptured intracranial aneurysms (UIA) in comparison to individuals without vascular lesions in the brain. The concentration of 27 proteins in the CSF and serum of UIA patients (N = 40) and individuals without vascular lesions in the brain (N = 15) was evaluated using a multiplex ELISA kit (Bio-Plex Pro Human Cytokine 27-Plex Panel). In the CSF 13 out of 27 proteins evaluated presented a concentration 1.36-fold or greater in UIA patients in comparison to the control group. Significantly higher were IL-1β, IL-1ra, IL-2, IL-4, IL-5, IL-7, IL-8, IL-12, IL-13, TNF-α, INF-γ, MCP-1, and VEGF. In the serum none of the proteins evaluated significantly differ between UIA patients and the control group. The correlation coefficient analysis showed that CSF IL-1β, IL-8, and TNF-α positively, while IL-13 negatively correlated with the size of aneurysms. CSF IL-6 and MCP-1 concentrations positively correlated with the number of aneurysms. In patients with UIA, pro-inflammatory and anti-inflammatory mechanisms are activated simultaneously, because the concentration of promoting and suppressing inflammatory response proteins was significantly higher in CSF of UIA patients compared to the control group. The preventive therapy of brain aneurysm development should be focused on IL-1β, IL-6, IL-8, MCP-1, and TNF-α, the concentration of which in CSF positively correlated with the size and number of aneurysms.

Identification of cerebrospinal fluid biomarker candidates for anti-N-methyl-D-aspartate receptor encephalitis: High-throughput proteomic investigation.

Although the diagnosis is mainly dependent on the detection of anti-N-methyl-D-aspartate receptor (NMDAR) antibodies in cerebrospinal fluid (CSF) and/or serum, there was no direct correlations between anti-NMDAR antibody titers in CSF and disease severity and prognosis in anti-NMDAR encephalitis patients. Here, we aimed to extensively identify CSF biomarkers related to the occurrence, development, and prognosis of anti-NMDAR encephalitis using a high-throughput proteomic approach. A CSF cytokine antibody array containing 80 cytokines and inflammatory mediators related to immune and inflammatory responses was applied to identify biomarker candidates in individual CSF samples from a well-characterized cohort comprising patients with anti-NMDAR encephalitis (n = 6) and controls (n = 6). Validation and specific detection were performed in an extended cohort consisting of anti-NMDAR encephalitis patients (n = 13), controls (n = 13), and viral encephalitis (n = 13) by enzyme-linked immunosorbent assay (ELISA). Additionally, the levels of some inflammatory proteins in three groups in cohort 2 reported in previous literatures that may be involved in the development of anti-NMDAR encephalitis were also tested by ELISA. Correlations between candidate biomarkers and clinical characteristics of anti-NMDAR encephalitis patients were analyzed. Three differentially expressed cytokines and inflammatory mediators were screened from the 80-cytokine array in cohort 1. Functional enrichment analysis results suggested that these differentially expressed proteins were related to autophagy, immune/inflammatory responses, cell death, and other processes. In cohort 2, the elevations of cellular inhibitor of apoptosis protein-1 (cIAP-1), macrophage colony-stimulating factor (MCSF), CXC chemokine ligand 13 (CXCL13), and nucleotide binding oligomerization domain-like receptor protein 3 (NLRP3) in anti-NMDAR encephalitis were validated by ELISA. Linear regression revealed that the levels of CSF CXCL13 and cIAP-1 were positively correlated with the highest modified Rankin scale (mRS) score in the acute phase (p < 0.05). The level of cIAP-1 was positively correlated with the anti-NMDAR Encephalitis One-Year Functional Status (NEOS) score (p < 0.05). These biomarkers show promising functions to evaluate severity or prognosis of anti-NMDAR encephalitis. The biological processes of immune/inflammatory responses, altered levels of autophagy, and the tumornecrosis factor (TNF) signal pathway may be involved in the pathophysiology of anti-NMDAR encephalitis to some extent.

Regional variability and genotypic and pharmacodynamic effects on PrP concentration in the CNS

Prion protein (PrP) concentration controls the kinetics of prion replication and is a genetically and pharmacologically validated therapeutic target for prion disease. In order to evaluate PrP concentration as a pharmacodynamic biomarker and assess its contribution to known prion disease risk factors, we developed and validated a plate-based immunoassay reactive for PrP across 6 species of interest and applicable to brain and cerebrospinal fluid (CSF). PrP concentration varied dramatically across different brain regions in mice, cynomolgus macaques, and humans. PrP expression did not appear to contribute to the known risk factors of age, sex, or common PRNP genetic variants. CSF PrP was lowered in the presence of rare pathogenic PRNP variants, with heterozygous carriers of P102L displaying 55%, and D178N just 31%, of the CSF PrP concentration of mutation-negative controls. In rodents, pharmacologic reduction of brain Prnp RNA was reflected in brain parenchyma PrP and, in turn in CSF PrP, validating CSF as a sampling compartment for the effect of PrP-lowering therapy. Our findings support the use of CSF PrP as a pharmacodynamic biomarker for PrP-lowering drugs and suggest that relative reduction from individual baseline CSF PrP concentration may be an appropriate marker for target engagement.

JC Polyomavirus Whole Genome Sequencing at the Single-Molecule Level Reveals Emerging Neurotropic Populations in Progressive Multifocal Leukoencephalopathy.

JC polyomavirus (JCV) mostly causes asymptomatic persistent renal infections but may give rise in immunosuppressed patients to neurotropic variants that replicate in the brain, causing progressive multifocal leukoencephalopathy (PML). Rearrangements in the JCV genome regulator noncoding control region (NCCR) and missense mutations in the viral capsid VP1 gene differentiate neurotropic variants from virus excreted in urine. To investigate intrahost emergence of JCV neurotropic populations in PML, we deep sequenced JCV whole genome recovered from cerebrospinal fluid (CSF) and urine samples from 32 human immunodeficiency virus (HIV)-infected and non-HIV-infected PML patients at the single-molecule level. JCV strains distributed among 6 of 7 known genotypes. Common patterns of NCCR rearrangements included an initial deletion mostly located in a short 10-nucleotide sequence, followed by duplications/insertions. Multiple NCCR variants present in individual CSF samples shared at least 1 rearrangement, suggesting they stemmed from a unique viral population. NCCR variants independently acquired single or double PML-specific adaptive VP1 mutations. NCCR variants recovered from urine and CSF displayed opposite deletion or duplication patterns in binding sites for transcription factors. Long-read deep sequencing shed light on emergence of neurotropic JCV populations in PML.

Alpha desynchronization during Stroop test unmasks cognitively healthy individuals with abnormal CSF Amyloid/Tau

Synaptic dysfunctions precede cognitive decline in Alzheimer's disease by decades, affect executive functions, and can be detected by quantitative electroencephalography (qEEG). We used quantitative electroencephalography combined with Stroop testing to identify changes of inhibitory controls in cognitively healthy individuals with an abnormal versus normal ratio of cerebrospinal fluid (CSF) amyloid/total-tau. We studied two groups of participants (60–94 years) with either normal (CH-NAT or controls, n = 20) or abnormal (CH-PAT, n = 21) CSF amyloid/tau ratio. We compared: alpha event-related desynchronization (ERD), alpha spectral entropy (SE), and their relationships with estimated cognitive reserve. CH-PATs had more negative occipital alpha ERD, and higher frontal and occipital alpha SE during low load congruent trials, indicating hyperactivity. CH-PATs demonstrated fewer frontal SE changes with higher load, incongruent Stroop testing. Correlations of alpha ERD with estimated cognitive reserve were significant in CH-PATs but not in CH-NATs. These results suggested compensatory hyperactivity in CH-PATs compared to CH-NATs. We did not find differences in alpha ERD comparisons with individual CSF amyloid(A), p-tau(T), total-tau(N) biomarkers.