The role of clusterin in amyloid-?-associated neurodegeneration.
ABSTRACT: Converging evidence indicates that clusterin, a chaperone glycoprotein, influences Alzheimer disease neurodegeneration. However, the precise role of clusterin in Alzheimer disease pathogenesis is still not well understood.To elucidate the relationship between clusterin, amyloid-? (A?), phosphorylated tau (p-tau), and the rate of brain atrophy over time among nondemented older individuals.This longitudinal cohort included cognitively normal older participants and individuals with mild cognitive impairment assessed with baseline lumbar puncture and longitudinal structural magnetic resonance imaging. We examined 241 nondemented older individuals from research centers across the United States and Canada (91 participants with a Clinical Dementia Rating score of 0 and 150 individuals with a Clinical Dementia Rating score of 0.5).Using linear mixed-effects models, we investigated interactions between cerebrospinal fluid (CSF) clusterin, CSF A?1-42, and CSF p-tau at threonine 181 (p-tau181p) on the atrophy rate of the entorhinal cortex and hippocampus.Across all participants, we found a significant interaction between CSF clusterin and CSF A?1-42 on the entorhinal cortex atrophy rate but not on the hippocampal atrophy rate. Cerebrospinal fluid clusterin was associated with the entorhinal cortex atrophy rate among CSF A?1-42-positive individuals but not among CSF A?1-42-negative individuals. In secondary analyses, we found significant interactions between CSF A?1-42 and CSF clusterin, as well as CSF A?1-42 and CSF p-tau181p, on the entorhinal cortex atrophy rate. We found similar results in subgroup analyses within the mild cognitive impairment and cognitively normal cohorts.In nondemented older individuals, A?-associated volume loss occurs in the presence of elevated clusterin. The effect of clusterin on A?-associated brain atrophy is not confounded or explained by p-tau. These findings implicate a potentially important role for clusterin in the earliest stages of the Alzheimer disease neurodegenerative process and suggest independent effects of clusterin and p-tau on A?-associated volume loss.
Project description:The relationship between neurodegeneration and the 2 hallmark proteins of Alzheimer's disease, amyloid-? (A?) and tau, is still unclear. Here, we examined 286 nondemented participants (107 cognitively normal older adults and 179 memory impaired individuals) who underwent longitudinal magnetic resonance (MR) imaging and lumbar puncture. Using mixed effects models, we investigated the relationship between longitudinal entorhinal cortex atrophy rate, cerebrospinal fluid (CSF) p-tau(181p) and CSF A?(1-42) . We found a significant relationship between elevated entorhinal cortex atrophy rate and decreased CSF A?(1-42) only with elevated CSF p-tau(181p) . Our findings indicate that A?-associated volume loss occurs only in the presence of phospho-tau in humans at risk for dementia.
Project description:<h4>Background and purpose</h4>Among cognitively healthy older individuals, the relationship among the 2 hallmark proteins of AD (Aβ and τ APOE ε4) and neurodegeneration is not well-understood. Here, we investigated the relationship between Aβ, p-τ, and APOE ε4 on longitudinal brain atrophy in preclinical AD.<h4>Materials and methods</h4>We examined 107 cognitively healthy older adults who underwent longitudinal MR imaging and baseline lumbar puncture. Within the same linear mixed-effects model, we concurrently investigated main and interactive effects between the APOE ε4 genotype and CSF Aβ(1-42), CSF p-τ and CSF Aβ(1-42), and the APOE ε4 genotype and CSF p-τ on entorhinal cortex atrophy rate. We also examined the relationship of APOE ε4, CSF p-τ, and CSF Aβ(1-42) on the atrophy rate of other AD-vulnerable neuroanatomic regions.<h4>Results</h4>The full model with main and interactive effects demonstrated a significant interaction only between CSF p-τ and CSF Aβ(1-42) on entorhinal cortex atrophy rate, indicating elevated atrophy with time in individuals with increased CSF p-τ and decreased CSF Aβ(1-42). The APOE ε4 genotype was significantly and specifically associated with CSF Aβ(1-42). However, the interaction between the APOE ε4 genotype and either CSF Aβ(1-42) or CSF p-τ on entorhinal cortex atrophy rate was not significant. We found similar results in other AD-vulnerable regions.<h4>Conclusions</h4>On the basis of our findings and building on prior experimental evidence, we propose a model of the pathogenic cascade underlying preclinical AD in which APOE ε4 primarily influences the pathology of Alzheimer disease via Aβ-related mechanisms, and in turn, Aβ-associated neurodegeneration occurs only in the presence of p-τ.
Project description:<h4>Background</h4>Epidemiological and molecular findings suggest a relationship between Alzheimer's disease (AD) and dyslipidemia, although the nature of this association is not well understood.<h4>Results</h4>Using linear mixed effects models, we investigated the relationship between CSF levels of heart fatty acid binding protein (HFABP), a lipid binding protein involved with fatty acid metabolism and lipid transport, amyloid-? (A?), phospho-tau, and longitudinal MRI-based measures of brain atrophy among 295 non-demented and demented older individuals. Across all participants, we found a significant association of CSF HFABP with longitudinal atrophy of the entorhinal cortex and other AD-vulnerable neuroanatomic regions. However, we found that the relationship between CSF HABP and brain atrophy was significant only among those with low CSF A?1-42 and occurred irrespective of phospho-tau181p status.<h4>Conclusions</h4>Our findings indicate that A?-associated volume loss occurs in the presence of elevated HFABP irrespective of phospho-tau. This implicates a potentially important role for fatty acid binding proteins in Alzheimer's disease neurodegeneration.
Project description:CSF levels of A?1-42, t-tau, and p-tau181p are potential early diagnostic markers for probable Alzheimer disease (AD). The influence of genetic variation on these markers has been investigated for candidate genes but not on a genome-wide basis. We report a genome-wide association study (GWAS) of CSF biomarkers (A?1-42, t-tau, p-tau181p, p-tau181p/A?1-42, and t-tau/A?1-42).A total of 374 non-Hispanic Caucasian participants in the Alzheimer's Disease Neuroimaging Initiative cohort with quality-controlled CSF and genotype data were included in this analysis. The main effect of single nucleotide polymorphisms (SNPs) under an additive genetic model was assessed on each of 5 CSF biomarkers. The p values of all SNPs for each CSF biomarker were adjusted for multiple comparisons by the Bonferroni method. We focused on SNPs with corrected p<0.01 (uncorrected p<3.10×10(-8)) and secondarily examined SNPs with uncorrected p values less than 10(-5) to identify potential candidates.Four SNPs in the regions of the APOE, LOC100129500, TOMM40, and EPC2 genes reached genome-wide significance for associations with one or more CSF biomarkers. SNPs in CCDC134, ABCG2, SREBF2, and NFATC4, although not reaching genome-wide significance, were identified as potential candidates.In addition to known candidate genes, APOE, TOMM40, and one hypothetical gene LOC100129500 partially overlapping APOE; one novel gene, EPC2, and several other interesting genes were associated with CSF biomarkers that are related to AD. These findings, especially the new EPC2 results, require replication in independent cohorts.
Project description:Measures 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.To investigate the usefulness of CSF VILIP-1, tau, p-tau181, and A?42 levels in predicting rates of whole-brain and regional atrophy in early AD and cognitively normal control subjects over time.Longitudinal 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.Correlations between baseline CSF biomarker measures and rates of whole-brain or regional atrophy in the AD and control cohorts over the follow-up period.Baseline CSF VILIP-1, tau, and p-tau181 levels (but not A?42 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.Cerebrospinal 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.
Project description:The goal of this study is to investigate the value of tau phosphorylated at threonine 181 (P-tau181P) in the Alzheimer's disease (AD) cerebrospinal fluid (CSF) biomarker panel for differential dementia diagnosis in autopsy confirmed AD and non-AD patients. The study population consisted of 140 autopsy confirmed AD and 77 autopsy confirmed non-AD dementia patients. CSF concentrations of amyloid-? peptide of 42 amino acids (A?1-42), total tau protein (T-tau), and P-tau181P were determined with single analyte ELISA-kits (INNOTEST(®), Fujirebio, Ghent, Belgium). Diagnostic accuracy was assessed through receiver operating characteristic (ROC) curve analyses to obtain area under the curve (AUC) values and to define optimal cutoff values to discriminate AD from pooled and individual non-AD groups. ROC curve analyses were only performed on biomarkers and ratios that differed significantly between the groups. Pairwise comparison of AUC values was performed by means of DeLong tests. The A?1-42/P-tau181P ratio (AUC?=?0.770) performed significantly better than A?1-42 (AUC?=?0.677, P?=?0.004), T-tau (AUC?=?0.592, P?<?0.001), and A?1-42/T-tau (AUC?=?0.678, P?=?0.001), while P-tau181P (AUC?=?0.720) performed significantly better than T-tau (AUC?=?0.592, P?<?0.001) to discriminate between AD and the pooled non-AD group. When comparing AD and the individual non-AD diagnoses, A?1-42/P-tau181P (AUC?=?0.894) discriminated AD from frontotemporal dementia significantly better than A?1-42 (AUC?=?0.776, P?=?0.020) and T-tau (AUC?=?0.746, P?=?0.004), while P-tau181P/T-tau (AUC?=?0.958) significantly improved the differentiation between AD and Creutzfeldt-Jakob disease as compared to A?1-42 (AUC?=?0.688, P?=?0.004), T-tau (AUC?=?0.874, P?=?0.040), and A?1-42/P-tau181P (AUC?=?0.760, P?=?0.003). In conclusion, this study demonstrates P-tau181P is an essential component of the AD CSF biomarker panel, and combined assessment of A?1-42, T-tau, and P-tau181P renders, to present date, the highest diagnostic power to discriminate between AD and non-AD dementias.
Project description:<h4>Background</h4>According to the amyloid, tau, neurodegeneration research framework classification, amyloid and tau positive (A+T+) mild cognitive impairment (MCI) individuals are defined as prodromal Alzheimer disease. This study was designed to compare the clinical and biomarker features between A+T+MCI individuals who progressed to progressive MCI (pMCI) and those who remained stable MCI (sMCI), and to identify relevant baseline clinical biomarker and features that could be used to predict progression to dementia within 2 years.<h4>Methods</h4>We stratified 197 A+T+MCI individuals into pMCI (n = 64) and sMCI (n = 133) over 2 years. Demographics and cognitive assessment scores, cerebrospinal fluid (CSF), and neuroimaging biomarkers (18F-florbetapir positron emission tomography mean standardized uptake value ratios [SUVR] and structural magnetic resonance imaging [MRI]) were compared between pMCI and sMCI at baseline, 12- and 24-month follow-up. Logistic regression models then were used to evaluate clinical baseline and biomarker features that predicted dementia progression in A+T+MCI.<h4>Results</h4>pMCI individuals had higher mean 18F-florbetapir SUVR, CSF total-tau (t-tau), and p-tau181P than those in sMCI individuals. pMCI individuals performed poorer in cognitive assessments, both global and domain specific (memory, executive, language, attention, and visuospatial skills) than sMCI. At baseline, there were significant differences in regions of interest of structural MRI between the two groups, including bilateral amygdala, hippocampus and entorhinal, bilateral inferior lateral ventricle, left superior and middle temporal, left posterior and caudal anterior cingulate (P < 0.05). Baseline CSF t-tau levels and cognitive scores of Montreal cognitive assessment, functional assessment questionnaire, and everyday cognition by the patient's study partner language domain could predict progression to dementia in A+T+MCI within 2 years.<h4>Conclusions</h4>In future clinical trials, specific CSF and cognitive measures that predict dementia progression in A+T+MCI might be useful risk factors for assessing the risk of dementia progression.
Project description:<h4>Background and aim</h4>Toxic oligomeric ?-synuclein (?S; O-?S) has been suggested to play a central role in the pathogenesis of Lewy body diseases such as Parkinson's disease (PD). Cerebrospinal fluid (CSF) levels of ?S, O-?S, total and phosphorylated tau, and amyloid ? 1-42 (A?1-42) are thought to reflect the pathophysiology or clinical symptoms in PD. In this study, we examined correlations of the CSF levels of these proteins with the clinical symptoms, and with each other in drug-naïve patients with PD.<h4>Methods</h4>Twenty-seven drug-naïve patients with PD were included. Motor and cognitive functions were assessed using the Unified Parkinson's Disease Rating Scale (UPDRS), Montreal Cognitive Assessment (MoCA), and Neurobehavioral Cognitive Status Examination (COGNISTAT). CSF levels of total ?S, O-?S, A?1-42, total tau and tau phosphorylated at threonine 181 (P-tau181p) were measured. CSF levels of these proteins were compared with clinical assessments from the UPDRS, MoCA and COGNISTAT using Spearman correlation analysis. Spearman correlation coefficients among CSF protein levels were also evaluated.<h4>Results</h4>CSF levels of ?S were negatively correlated with UPDRS part III (motor score) (p?<?0.05) and bradykinesia (p?<?0.01), and positively correlated with COGNISTAT subtest of judgement (p?<?0.01) and CSF levels of A?1-42 (p?<?0.001), total tau (p?<?0.001) and P-tau181p (p?<?0.01). Lower CSF levels of A?1-42, total tau and P-tau181p were significantly related to worsening of some motor and/or cognitive functions. The CSF level of O-?S showed no correlation with any motor and cognitive assessments or with CSF levels of the other proteins.<h4>Conclusion</h4>CSF levels of ?S are correlated with some clinical symptoms and CSF levels of other pathogenic proteins in drug-naïve PD patients. These correlations suggest a central role for interaction and aggregation of ?S with A?1-42, tau, and phosphorylated tau in the pathogenesis of PD. Although O-?S has been shown to have neurotoxic effects, CSF levels do not reflect clinical symptoms or levels of other proteins in cross-sectional assessment.
Project description:Cerebrospinal fluid (CSF) levels of Abeta peptide 1-42 (Abeta 42), tau, and phosphorylated tau (ptau) are potential biomarkers of Alzheimer disease.To determine whether Abeta 42, tau, and ptau predict the rate of cognitive change in individuals with very mild dementia of the Alzheimer type (DAT).Retrospective analysis of CSF biomarkers and clinical data.An academic Alzheimer disease research center.Research volunteers in a longitudinal study of aging and cognition. Participants (n = 49) had a clinical diagnosis of very mild DAT with a Clinical Dementia Rating (CDR) of 0.5 at the time of lumbar puncture. All the participants had at least 1 follow-up assessment (mean [SD] follow-up, 3.5 [1.8] years).Baseline CSF levels of Abeta 42, Abeta 40, tau, and ptau at threonine 181 (ptau181) and the rate of dementia progression as measured using the CDR sum of boxes (CDR-SB) score and psychometric performance.The rate of dementia progression was significantly more rapid in individuals with lower baseline CSF Abeta 42 levels, higher tau or ptau181 levels, or high tau: Abeta 42 ratios. For example, the annual change in the CDR-SB score was 1.1 for the lowest 2 tertiles of Abeta 42 values and 0.3 for the highest tertile of Abeta 42 values.In individuals with very mild DAT, lower CSF Abeta 42 levels, high tau or ptau181 levels, or high tau:Abeta 42 ratios quantitatively predict more rapid progression of cognitive deficits and dementia. Biomarkers of CSF may be useful prognostically and to identify individuals who are more likely to progress for participation in therapeutic clinical trials.