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Association between plasma exosome neurogranin and brain structure in patients with Alzheimer's disease: a protocol study.

ABSTRACT: INTRODUCTION:Neurogranin is known to be significantly elevated in patients with Alzheimer's disease (AD) and may be an effective clinical predictor of cognitive decline and neurodegeneration. Amnestic mild cognitive impairment (aMCI) is an intermediate disease state between normal cognitive ageing and dementia, the latter of which can easily revert to AD. There remains significant uncertainty regarding the conversion of aMCI to AD, and therefore, elucidating such progression is paramount to the field of cognitive neuroscience. In this protocol study, we therefore aim to investigate the changes in plasma neurogranin in the early stage of AD and the mechanism thereof regarding the cognitive progression towards AD. METHODS AND ANALYSIS:In this study, patients with aMCI and AD patients (n=70?each) will be recruited at the memory clinic of the Department of Neurology of Hongqi Hospital affiliated with the Mudanjiang Medical University of China. Healthy older controls (n=70) will also be recruited from the community. All subjects will undergo neuroimaging and neuropsychological evaluations in addition to blood collection at the first year and the third year. We hope to identify a new biomarker of cognitive decline associated with AD and characterise its behaviour throughout the progression of aMCI to AD. This work will reveal novel targets for the therapeutic prevention, diagnosis and treatment of AD. The primary outcome measures will be (1) neuropsychological evaluation, including Mini-Mental State Examination, Montreal Cognitive Assessment, Clinical Dementia Rating scale, Shape Trail Test-A&B, Auditory Verbal Learning Test-HuaShan version; (2) microstructural alterations and hippocampal features from MRI scans; and (3) neurogranin levels in the neuronal-derived exosomes from peripheral blood samples. ETHICS AND DISSEMINATION:The ethics committee of the Hongqi Hospital affiliated with the Mudanjiang Medical University of China has approved this study protocol. The results will be published in peer-reviewed journals and presented at national or international scientific conferences. TRIAL REGISTRATION NUMBER:ChiCTR2000029055.

SUBMITTER: He M

PROVIDER: S-EPMC7430441 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature

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Association between plasma exosome neurogranin and brain structure in patients with Alzheimer's disease: a protocol study.

He MengFei M Sun Li L Cao Wenhui W Yin Changhao C Sun Wenqiang W Liu Ping P Tan Lin L Xu Zheng Z Zhao Weina W

BMJ open 20200816 8

<h4>Introduction</h4>Neurogranin is known to be significantly elevated in patients with Alzheimer's disease (AD) and may be an effective clinical predictor of cognitive decline and neurodegeneration. Amnestic mild cognitive impairment (aMCI) is an intermediate disease state between normal cognitive ageing and dementia, the latter of which can easily revert to AD. There remains significant uncertainty regarding the conversion of aMCI to AD, and therefore, elucidating such progression is paramount ...[more]

PMID: 32801201

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Project description:BackgroundRecent studies suggest that plasma phosphorylated tau181 (p-tau181) is a highly specific biomarker for Alzheimer's disease (AD)-related tau pathology. It has great potential for the diagnostic and prognostic evaluation of AD, since it identifies AD with the same accuracy as tau PET and CSF p-tau181 and predicts the development of AD dementia in cognitively unimpaired (CU) individuals and in those with mild cognitive impairment (MCI). Plasma p-tau181 may also be used as a biomarker in studies exploring disease pathogenesis, such as genetic or environmental risk factors for AD-type tau pathology. The aim of the present study was to investigate the relation between polygenic risk scores (PRSs) for AD and plasma p-tau181.MethodsData from the Alzheimer's Disease Neuroimaging Initiative (ADNI) was used to examine the relation between AD PRSs, constructed based on findings in recent genome-wide association studies, and plasma p-tau181, using linear regression models. Analyses were performed in the total sample (n = 818), after stratification on diagnostic status (CU (n = 236), MCI (n = 434), AD dementia (n = 148)), and after stratification on Aβ pathology status (Aβ positives (n = 322), Aβ negatives (n = 409)).ResultsAssociations between plasma p-tau181 and APOE PRSs (p = 3e-18-7e-15) and non-APOE PRSs (p = 3e-4-0.03) were seen in the total sample. The APOE PRSs were associated with plasma p-tau181 in all diagnostic groups (CU, MCI, and AD dementia), while the non-APOE PRSs were associated only in the MCI group. The APOE PRSs showed similar results in amyloid-β (Aβ)-positive and negative individuals (p = 5e-5-1e-3), while the non-APOE PRSs were associated with plasma p-tau181 in Aβ positives only (p = 0.02).ConclusionsPolygenic risk for AD including APOE was found to associate with plasma p-tau181 independent of diagnostic and Aβ pathology status, while polygenic risk for AD beyond APOE was associated with plasma p-tau181 only in MCI and Aβ-positive individuals. These results extend the knowledge about the relation between genetic risk for AD and p-tau181, and further support the usefulness of plasma p-tau181 as a biomarker of AD.

Project description:Synaptic degeneration and neuronal loss are early events in Alzheimer's disease (AD), occurring long before symptom onset, thus making synaptic biomarkers relevant for enabling early diagnosis. The postsynaptic protein neurogranin (Ng) is a cerebrospinal fluid (CSF) biomarker for AD, also in the prodromal phase. Here we tested the hypothesis that during AD neurodegeneration, processing of full-length Ng into endogenous peptides in the brain is increased. We characterized Ng in post-mortem brain tissue and investigated the levels of endogenous Ng peptides in relation to full-length protein in brain tissue of patients with sporadic (sAD) and familial Alzheimer's disease (fAD), healthy controls and individuals who were cognitively unaffected but amyloid-positive (CU-AP) in two different brain regions. Brain tissue from parietal cortex [sAD (n = 10) and age-matched controls (n = 10)] and temporal cortex [sAD (n = 9), fAD (n = 10), CU-AP (n = 13) and controls (n = 9)] were included and all the samples were analyzed by three different methods. Using high-resolution mass spectrometry, 39 endogenous Ng peptides were identified while full-length Ng was found to be modified including disulfide bridges or glutathione. In sAD parietal cortex, the ratio of peptide-to-total full-length Ng was significantly increased for eight endogenous Ng peptides compared to controls. In the temporal cortex, several of the peptide-to-total full-length Ng ratios were increased in both sAD and fAD cases compared to controls and CU-AP. This finding was confirmed by western blot, which mainly detects full-length Ng, and enzyme-linked immunosorbent assay, most likely detecting a mix of peptides and full-length Ng. In addition, Ng was significantly associated with the degree of amyloid and tau pathology. These results suggest that processing of Ng into peptides is increased in AD brain tissue, which may reflect the ongoing synaptic degeneration, and which is also mirrored as increased levels of Ng peptides in CSF.

Dataset Information

Association between plasma exosome neurogranin and brain structure in patients with Alzheimer's disease: a protocol study.

Publications

Association between plasma exosome neurogranin and brain structure in patients with Alzheimer's disease: a protocol study.

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