Dataset Information

Cerebrospinal fluid biomarkers of neurodegeneration, synaptic dysfunction, and axonal injury relate to atrophy in structural brain regions specific to Alzheimer's disease.

ABSTRACT:

Introduction

Patterns of atrophy can distinguish normal cognition from Alzheimer's disease (AD), but neuropathological drivers of this pattern are unknown. This study examined associations between cerebrospinal fluid biomarkers of AD pathology, synaptic dysfunction, and neuroaxonal injury with two AD imaging signatures.

Methods

Signatures were calculated using published guidelines. Linear regressions related each biomarker to both signatures, adjusting for demographic factors. Bootstrapped analyses tested if associations were stronger with one signature versus the other.

Results

Increased phosphorylated tau (p-tau), total tau, and neurofilament light (P-values <.045) related to smaller signatures (indicating greater atrophy). Diagnosis and sex modified associations between p-tau and neurogranin (P-values<.05) and signatures, such that associations were stronger among participants with mild cognitive impairment and female participants. The strength of associations did not differ between signatures.

Discussion

Increased evidence of neurodegeneration, axonopathy, and tau phosphorylation relate to greater AD-related atrophy. Tau phosphorylation and synaptic dysfunction may be more prominent in AD-affected regions in females.

SUBMITTER: Moore EE

PROVIDER: S-EPMC7781154 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature

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Publications

Cerebrospinal fluid biomarkers of neurodegeneration, synaptic dysfunction, and axonal injury relate to atrophy in structural brain regions specific to Alzheimer's disease.

Moore Elizabeth E EE Gifford Katherine A KA Khan Omair A OA Liu Dandan D Pechman Kimberly R KR Acosta Lealani Mae Y LMY Bell Susan P SP Turchan Maxim M Landman Bennett A BA Blennow Kaj K Zetterberg Henrik H Hohman Timothy J TJ Jefferson Angela L AL

Alzheimer's & dementia : the journal of the Alzheimer's Association 20200506 6

<h4>Introduction</h4>Patterns of atrophy can distinguish normal cognition from Alzheimer's disease (AD), but neuropathological drivers of this pattern are unknown. This study examined associations between cerebrospinal fluid biomarkers of AD pathology, synaptic dysfunction, and neuroaxonal injury with two AD imaging signatures.<h4>Methods</h4>Signatures were calculated using published guidelines. Linear regressions related each biomarker to both signatures, adjusting for demographic factors. Boo ...[more]

PMID: 32378327

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Project description:A biomarker of synapse loss, an early event in Alzheimer's disease (AD) pathophysiology that precedes neuronal death and symptom onset, would be a much-needed prognostic biomarker. With direct access to the brain interstitial fluid, the cerebrospinal fluid (CSF) is a potential source of synapse-derived proteins. In this study, we aimed to identify and validate novel CSF biomarkers of synapse loss in AD. Discovery: Combining shotgun proteomics of the CSF with an exhaustive search of the literature and public databases, we identified 251 synaptic proteins, from which we selected 22 for further study. Verification: Twelve proteins were discarded because of poor detection by Selected Reaction Monitoring (SRM). We confirmed the specific expression of 9 of the remaining proteins (Calsynytenin-1, GluR2, GluR4, Neurexin-2A, Neurexin-3A, Neuroligin-2, Syntaxin-1B, Thy-1, Vamp-2) at the human synapse using Array Tomography microscopy and biochemical fractionation methods. Exploration: Using SRM, we monitored these 9 synaptic proteins (20 peptides) in a cohort of CSF from cognitively normal controls and subjects in the pre-clinical and clinical AD stages (n = 80). Compared with controls, peptides from 8 proteins were elevated 1.3 to 1.6-fold (p < 0.04) in prodromal AD patients. Validation: Elevated levels of a GluR4 peptide at the prodromal stage were replicated (1.3-fold, p = 0.04) in an independent cohort (n = 60). Moreover, 7 proteins were reduced at preclinical stage 1 (0.6 to 0.8-fold, p < 0.04), a finding that was replicated (0.7 to 0.8-fold, p < 0.05) for 6 proteins in a third cohort (n = 38). In a cross-cohort meta-analysis, 6 synaptic proteins (Calsyntenin-1, GluR4, Neurexin-2A, Neurexin-3A, Syntaxin-1B and Thy-1) were reduced 0.8-fold (p < 0.05) in preclinical AD, changes that precede clinical symptoms and CSF markers of neurodegeneration. Therefore, these proteins could have clinical value for assessing disease progression, especially in preclinical stages of AD.

Project description:BACKGROUND:Synaptic and axonal loss are two major mechanisms underlying Alzheimer's disease (AD) pathogenesis, and biomarkers reflecting changes in these cellular processes are needed for early diagnosis and monitoring the progression of AD. Contactin-2 is a synaptic and axonal membrane protein that interacts with proteins involved in the pathology of AD such as amyloid precursor protein (APP) and beta-secretase 1 (BACE1). We hypothesized that AD might be characterized by changes in contactin-2 levels in the cerebrospinal fluid (CSF) and brain tissue. Therefore, we aimed to investigate the levels of contactin-2 in the CSF and evaluate its relationship with disease pathology. METHODS:Contactin-2 was measured in CSF from two cohorts (selected from the Amsterdam Dementia Cohort), comprising samples from controls (cohort 1, n?=?28; cohort 2, n?=?20) and AD (cohort 1, n?=?36; cohort 2, n?=?70) using an analytically validated commercial enzyme-linked immunosorbent assay (ELISA). The relationship of contactin-2 with cognitive decline (Mini-Mental State Examination (MMSE)) and other CSF biomarkers reflecting AD pathology were analyzed. We further characterized the expression of contactin-2 in postmortem AD human brain (n?=?14) versus nondemented controls (n?=?9). RESULTS:CSF contactin-2 was approximately?1.3-fold reduced in AD patients compared with controls (p?<?0.0001). Overall, contactin-2 levels correlated with MMSE scores (r?=?0.35, p?=?0.004). We observed that CSF contactin-2 correlated with the levels of phosphorylated tau within the control (r?=?0.46, p?<?0.05) and AD groups (r?=?0.31, p?<?0.05). Contactin-2 also correlated strongly with another synaptic biomarker, neurogranin (control: r?=?0.62, p?<?0.05; AD: r?=?0.60, p?<?0.01), and BACE1, a contactin-2 processing enzyme (control: r?=?0.64, p?<?0.01; AD: r?=?0.46, p?<?0.05). Results were further validated in a second cohort (p?<?0.01). Immunohistochemical analysis revealed that contactin-2 is expressed in the extracellular matrix. Lower levels of contactin-2 were specifically found in and around amyloid plaques in AD hippocampus and temporal cortex. CONCLUSIONS:Taken together, these data reveal that the contactin-2 changes observed in tissues are reflected in CSF, suggesting that decreased contactin-2 CSF levels might be a biomarker reflecting synaptic or axonal loss.

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Project description:ImportanceMeasures of neuronal loss are likely good surrogates for clinical and radiological disease progression in Alzheimer disease (AD). Cerebrospinal fluid (CSF) markers of neuronal injury or neurodegeneration may offer usefulness in predicting disease progression and guiding outcome assessments and prognostic decisions in clinical trials of disease-modifying therapies. Visinin-like protein 1 (VILIP-1) has demonstrated potential usefulness as a marker of neuronal injury in AD.ObjectiveTo investigate the usefulness of CSF VILIP-1, tau, p-tau181, and Aβ42 levels in predicting rates of whole-brain and regional atrophy in early AD and cognitively normal control subjects over time.Design, setting, and participantsLongitudinal observational study of brain atrophy in participants with early AD and cognitively normal controls. Study participants had baseline CSF biomarker measurements and longitudinal magnetic resonance imaging assessments for a mean follow-up period of 2 to 3 years. Mixed linear models assessed the ability of standardized baseline CSF biomarker measures to predict rates of whole-brain and regional atrophy over the follow-up period. The setting was The Charles F. and Joanne Knight Alzheimer's Disease Research Center, Washington University School of Medicine in St Louis. Participants (mean age, 72.6 years) were individuals with a clinical diagnosis of very mild AD (n = 23) and cognitively normal controls (n = 64) who were enrolled in longitudinal studies of healthy aging and dementia. The study dates were 2000 to 2010.Main outcomes and measuresCorrelations between baseline CSF biomarker measures and rates of whole-brain or regional atrophy in the AD and control cohorts over the follow-up period.ResultsBaseline CSF VILIP-1, tau, and p-tau181 levels (but not Aβ42 levels) predicted rates of whole-brain and regional atrophy in AD over the follow-up period. Baseline CSF VILIP-1 levels predicted whole-brain (P = .006), hippocampal (P = .01), and entorhinal (P = .001) atrophy rates at least as well as tau and p-tau181 in early AD. Cognitively normal controls whose CSF VILIP-1, tau, or p-tau181 levels were in the upper tercile had higher rates of whole-brain (P = .02, P = .003, and P = .02, respectively), hippocampal (P = .001, P = .01, and P = .02, respectively), and entorhinal (P = .007, P = .01, and P = .01, respectively) atrophy compared with those whose levels were in the lower 2 terciles.Conclusions and relevanceCerebrospinal fluid VILIP-1 levels predict rates of whole-brain and regional atrophy similarly to tau and p-tau181 and may provide a useful CSF biomarker surrogate for neurodegeneration in early symptomatic and preclinical AD.

Dataset Information

Cerebrospinal fluid biomarkers of neurodegeneration, synaptic dysfunction, and axonal injury relate to atrophy in structural brain regions specific to Alzheimer's disease.

Introduction

Methods

Results

Discussion

Publications

Cerebrospinal fluid biomarkers of neurodegeneration, synaptic dysfunction, and axonal injury relate to atrophy in structural brain regions specific to Alzheimer's disease.

Similar Datasets

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