Oligomeric Protein Variants as Biomarkers for AD and TBI Susceptibility

Project: Research project

Project Details

Description

Background: Misfolding and aggregation of the proteins amyloid beta (A) and tau result in the hallmark pathological plaques and tangles associated with AD, while aggregates of alpha-synuclein (a-syn) form Lewy Bodies, the hallmark feature of Parkinsons disease and Dementia with Lewy Bodies (DLB). While large fibrillar aggregates of these proteins are diagnostic features of these diseases, smaller soluble oligomeric species are the important key neurotoxins involved in onset and progression of these devastating diseases. Since A, tau and a-syn all also accumulate in the brain following traumatic brain injury (TBI), presence of selected toxic aggregate forms of these proteins can be valuable early biomarkers for AD and other neurodegenerative diseases and for specific neuronal damage in soldiers who have incurred TBI. Our lab has developed unique technology to isolate reagents that bind specific morphologies of a target protein. We developed recombinant antibody fragments, or nanobodies, that selectively recognize different oligomeric A, a-syn species, and tau species. This pool of nanobody reagents can be used to probe human serum samples to identify biomarkers for early diagnosis of AD and to identify neuronal damage following TBI. Objective/Hypothesis. Our hypothesis is that characterizing levels of a target set of key toxic biomarkers in serum will provide a means to identify the level of neuronal injury following TBI and to facilitate early diagnosis of AD and other neurodegenerative diseases. The biomarker set will include morphologically distinct toxic variants of A, a-syn and tau. Our objective is to identify a set of serum biomarkers that are indicative of the type of neuronal damage following TBI and sets that are diagnostic for different stages of AD including presyptomatic biomarkers. Soldiers suffering TBI who have a biomarker set similar to one indicative of AD brain will be at increased risk for AD and may benefit from early interventions. Rationale: Specific Aims: 1: Isolate additional nanobodies specific to selected tau species unique to TBI. 2. Generate and validate activity of each of the nanobodies including 3 anti-oligomeric A nanobodies, two anti-oligomeric a-syn nanobodies, an anti-oligomeric tau nanobody plus additional anti-tau nanobodies specific for TBI generated from Aim 1 3. Assay serum samples from of TBI, cognitively normal (ND), and AD patients utilizing our set of morphology specific nanobodies to determine concentration profiles of key toxic protein variants. 4. Identify oligomeric protein fingerprints that uniquely identify healthy, TBI and AD serum samples. Study Design: Objective 1). Generate nanobodies that selectively recognize tau variants uniquely present in CSF of patients suffering TBI. We will immunoprecipitate total tau from healthy and TBI CSF patients, then remove all nanobody clones that bind to healthy CSF tau forms and then isolate clones that selectively bind tau TBI specific tau forms. 2) Produce all nanobody reagents, purified by affinity chromatography and verify activity of each nanobody. 3) Use novel sandwich ELISA with femtomolar or better sensitivity to assay serum samples from three veteran population sets: a control group, a TBI group that has not converted to AD and an AD group. Serum samples will be provided by Dr. Yaffe (UCSF). We will quantify levels of the different oligomeric A, a-syn and tau variants using the morphology specific nanobodies described above. 4). We will compare results obtained from analysis of the ND, AD and TBI serum samples to identify biomarker sets that are indicative of TBI and those that are indicative of AD. Relevance: An early diagnostic indicator for AD, and particularly of increased susceptibility to AD following TBI, is critically important to identify which soldiers have neuronal damage consistent with AD so treatment can begin early and the effectiveness of the treatments can be monitored.
StatusFinished
Effective start/end date9/15/149/14/19

Funding

  • DOD-ARMY: Army Medical Research Acquisition Activity (USAMRAA) : $707,733.00

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