Ann C. McKee, MD, Case Western Reserve University - US grants

Alzheimer's disease, the most frequent cause of dementia and a major cause of morbidity and mortality in the elderly, is defined by histopathological features, notably neurofibrillary tangles and senile plaques. Because no animal model exists for the disorder, advances in understanding the pathogenesis of Alzheimer's disease have depended on studies of biopsy or postmortem human brain tissue. Previous studies have shown that disruption of the neuronal cytoskeleton, which normally functions to maintain cytoplasmic compartmentalization, intracellular transport and neuronal morphology, is a key feature of Alzheimer's disease. Paired helical filaments, the primary ultrastructural constituent of neurofibrillary tangles, contain the microtubule associated protein, tau as an integral component. Tau and other cytoskeletal proteins are reorganized in Alzheimer's disease, thereby providing a potential substrate for widespread degeneration and growth response. Our hypothesis is that degeneration and regeneration are critically dependent on cytoskeletal composition. A major goal of the present study is to establish the precise morphology and distribution of MAP2, type II Ca2+/calmodulin kinase and calbindin D28K immunoreactive neurons in the medial temporal lobe and their relationship to neurofibrillary tangles, as defined by thioflavine S, Hicks-Gallyas and tau staining, in aged controls and Alzheimer's disease patients. The medial temporal lobe encompasses a range of cortical and subcortical regions fundamental to memory processing which are lesioned in Alzheimer's disease. We will determine the sequence of neurofibrillary change by examining the interrelationship of tubulin, tau, ubiquitin, and MAP2 in degenerating neurons. Differentially affected regions will be examined in patients with Alzheimer's disease of variable severity, duration, and age of onset to determine the chronology of alterations. The nature and extent of growth response in Alzheimer's disease will be examined using markers associated with growth cones, including actin, GAP 43, and neural cell adhesion molecule (NCAM). The expression of tau protein in regenerating structures will be studied with hybridization histochemistry to determine if there is increased synthesis of tau in regenerating elements in Alzheimer's disease. These goals will be achieved using immunocytochemical, section Golgi, and local tract tracing methods at the light and electron microscopic levels. Specific procedures include immunoperoxidase, immunofluorescence, and immunogold procedures using well characterized antisera. Colocalization studies to determine the interrelationship of cytoskeletal proteins will be performed using double immunofluorescence and immunoperoxidase procedures.

The specific aims of the Neuropathology Core are to establish accurate, comprehensive neuropathological diagnoses using strict, reliable diagnostic criteria and to precisely document the neuropathological findings on brains of participants enrolled in the Patient/Control Registry, brain donors from the Framingham Heart Study and other brains referred for neuropathological examination.. These intensive neuropathological analyses, including quantitative histological, anatomical and immunocytochemical evaluations, facilitate clinicopathological, correlative studies of the functional, behavioral, and neuropsychiatric aspects of AD. In addition, the Boston University Brain Bank of the Neuropathology Core serves as a source of fresh, fixed and protocol has been established to ensure high quality fresh, fixed and frozen tissue to investigators requiring tissue with brief post-mortem intervals. The computerized database, maintained under the direction of the Administrative Core contains all clinical and pathological diagnoses, neuropathological data, post-mortem intervals, associated chronic diseases and storage conditions of the tissue. Tissue availability and distribution is monitored using a computer program specifically developed for this project. Quality assurance in tissue procurement, handling, processing storage and neuropathological diagnoses is provided by monthly meetings of the 5-member Neuropathology board. Tissue prioritization and distribution is also supervised by the Neuropathology board. The autopsy rate on participants enrolled in Patient Control Registry currently averages 76%. A continued effort will be made to obtain brain donations from other Boston community participants, especially African Americans using educational approaches focused on care providers, especially medical students, senior housing staff and residents and participants families, in conjunction with the Education Core. As a further aim, the Neuropathology Core will provide well- characterized blood-brain barrier endothelial cells obtained from post- mortem donors, for researchers who wish to carry out AD-related studies on cultured living cells.

DESCRIPTION (provided by applicant): Traumatic brain injury (TBI) is associated clinically with progressive cognitive decline and dementia and pathologically with axonal injury and the deposition of multiple aggregated proteins. Repetitive mild TBI can trigger chronic traumatic encephalopathy (CTE), a unique tauopathy, and single TBI can provoke an Alzheimer's-like neurodegeneration. Unfortunately, the only way to diagnose these posttraumatic neurodegenerations, including CTE, is by post-mortem brain examination. In order to conduct prospective research into the incidence, prevalence, risk factors, clinical course, and ultimately, treatment for posttraumatic neurodegeneration, consensus criteria for diagnosis as well as objective biomarkers for disease must first be established. This initiative will assemble a multicenter team of expert neuroscientists to evaluate the late effects of TBI, including single and repetitive TBI of varying severity, and CTE, using histological examination of postmortem bio specimens and neuroimaging tools as a foundation to develop in vivo diagnostics. As a first aim, this proposal will bring together a team of 5 accomplished neuropathologists in neurodegenerative disease to establish consensus criteria for the post-mortem diagnosis of CTE. This team will also define the stages of CTE pathology, the features that differentiate CTE from other neurodegenerations and the effects of substance abuse, and the characteristics of posttraumatic neurodegeneration after single TBI. As a second aim, this proposal will establish a national bio specimen and data bank for TBI (Understanding Neurological Injury and Traumatic Encephalopathy (UNITE) bio bank) by developing a nationwide brain donor registry and hotline to acquire high quality bio specimens and data. The UNITE bank will use strictly standardized protocols and a web-based interface to ensure that tissue and data are readily available to qualified investigators. Comprehensive retrospective clinical data including clinical symptoms, brain trauma and substance abuse history, and medical records (including common data elements) will be entered into a secure database. Behavioral/ mood dysfunction, cognitive changes, substance abuse and traumatic exposure will be correlated with quantitative assessment of the multifocal tauopathy, Ass deposition and axonal injury. As a third aim, neuroimaging signatures of the neuropathology will be determined in post-mortem tissue using high spatial resolution diffusion tensor imaging (DTI) and autoradiography using a highly selective PET ligand for tau. Quantitative assessment of axonal injury, tau, and Ass will be correlated with ex vivo DTI abnormalities and tau ligand autoradiography. Pilot neuroimaging studies of individuals at high risk for the development of CTE will also be conducted in the final 2 years of the proposal. This proposal will determine the clinical and neuroimaging correlates of CTE and posttraumatic neurodegeneration and create the groundwork for establishing their incidence and prevalence. This study will have a tremendous impact on public health of millions of Americans and greatly increase our understanding of the latent effects of brain trauma.

Since 1996, the Neuropathology Core (NPC) of the Boston University Alzheimer's Disease Center (BU ADC) has conducted cutting-edge research on the neuropathology of Alzheimer's disease (AD). Recently, the NPC directed groundbreaking research on chronic traumatic encephalopathy (CTE), research that revolutionized public health by identifying repetitive brain trauma as a major risk factor for neurodegeneration, including CTE (6-27). During the last funding cycle, the NPC published preliminary criteria for the neuropathological diagnosis of CTE (9), criteria that are in the process of being validated by a NINDS funded UO1 panel of expert neuropathologists from other ADRCs and academic centers and will eventually be incorporated into NIA-AA guidelines (27). One of the major outcomes from NPC research has been the recognition that some of the clinical symptoms of CTE can be very similar to AD, raising the possibility that some subjects clinically diagnosed with AD dementia may, in fact, have CTE. Our studies have also found beta amyloid (Aß) deposition in 52% of individuals diagnosed pathologically with CTE (17) and that the presence of Aß in CTE is significantly associated with increased clinical severity and tau and alpha-synuclein pathology. Ongoing research also indicates that changes of CTE are a common co-morbidity in ADC and other neurodegenerative disease brain banks (26). These advances suggest a dynamic synergism between CTE and AD pathobiology, and highlight the importance of studying the effects of repetitive brain trauma on the development of AD. The overarching goals of the NPC are to conduct and foster research on AD and to determine the relationship of AD and other neurodegenerative pathology to repetitive head impacts (RHI) and CTE. The specific aims of the NPC consist of fundamental Core functions, namely to perform state-of-the-art diagnostic neuropathology, optimally store and distribute CNS tissue and other biospecimens, and provide neuropathological data to the other cores of the BU ADC and to NACC. The specific aims also build upon the significant innovations of the NPC with regard to CTE and focus on determining the relationship of RHI to AD and CTE. Over the past cycle, there have been substantial increases in funding and personnel, including 2 new MD, PhD neuropathologists, as well as large increases in infrastructure and equipment. These expansions have stimulated major technical innovations in qualitative and quantitative neuropathology. Other advances of the NPC include developing biomarkers for AD, CTE and related disorders, expanding the collection of CNS tissue to include spinal cord, eyes, plasma, serum and CSF, and increased collection of control tissues. To accomplish these aims, the NPC will continue to work in close collaboration with the other BU ADC Cores, other ADCs and ADRCs.

Defining the mechanisms driving tau deposition and spread is a critical but poorly understood issue in Alzheimer's disease (AD) and Chronic Traumatic Encephalopathy (CTE). There is growing evidence that microvascular dysfunction and neuroinflammation occur early in both diseases and exacerbate tau pathology. Microvasculopathy, blood brain barrier (BBB) dysfunction and neuroinflammation are also consequences of exposure to repetitive head impacts (RHI) experienced during contact sports and military participation. CTE is characterized by the perivascular accumulation of tau and progressive decline in cognitive, behavioral and mood function; CTE is also associated with RHI exposure. Our preliminary studies suggest that the microvasculopathy and inflammation associated with CTE is distinctive from AD and that tau deposition is accelerated in CTE, resulting in neurofibrillary degeneration of the medial temporal lobe a decade earlier than in aging or AD. Identifying the molecular features driving tau pathology in CTE will provide important insights into mechanisms governing tau pathology in AD. Pinpointing the distinctions and commonalities in inflammation, microvasculopathy and BBB pathology between AD and CTE and determining their relationship to RHI will provide fundamental insights into the initiation and spread of tau pathology and the pathogenesis of tauopathies. Given that 15 million students participate in contact sports and 300,000 military veterans have been exposed to blast and concussive injury, there is great urgency to understanding the effects of RHI exposure on microvasculopathy, inflammation and the development of tau pathology in CTE and AD. In this application, we will use large, well-characterized, novel cohorts, including the largest neuropathologically confirmed autopsy cohort of subjects with CTE in the world (N=250), our AD brain bank (N=800), and controls from the VA and Framingham Heart Study, both exposed to RHI (N=40) and not exposed to RHI (N=80), and comprehensive clinical and pathological FITBIR-compliant datasets, to study the relationship between RHI exposure, tau pathology, microvasculopathy, neuroinflammation, Aß, ?-synuclein, and TDP-43 accumulation and clinical decline in CTE, AD, RHI-controls and non-RHI controls. We will also examine whether APOE?4 and MAPT status impact these relationships. Our long-term goal is to identify innovative biomarkers and targets for pharmacotherapy based on the distinctive microvascular and inflammatory profiles of AD and CTE. Most biomarkers for the detection of CTE and AD in living subjects have focused on tau, Aß, axonal, and astrocytic markers, yet vascular dysfunction is an early event in AD and CTE and heralds the onset of clinical symptoms. The proposed studies will expand potential biomarkers to include novel markers of vascular dysfunction, inflammation and accelerated tau pathology in the medial temporal lobe as suggested by our preliminary studies. This research has the potential to transform our conceptualization of neurodegeneration and identify key mechanisms driving tau deposition and spread in tauopathies.  

The Administrative Core will be directed by Dr. McKee and the Administrative offices will be located at the Boston University Alzheimer's Disease Center (BUADC) and CTE Center at Boston University School of Medicine. The leadership, administrative management and coordination of the proposed activities will be based on the prior experience and success of 2 previous harmonized UO1s (McKee, PI, Dams-O'Connor, PI). This U54 application includes 3 well-integrated projects, 3 cores and utilizes 8 brain banks across BUSM and ISMMS. Each project and core complements the others so that a synergistic relationship is achieved with a common focus on the major goals of the program: to comprehensively characterize the neuropathological substrate of neurodegeneration after TBI and RHI, to describe the associations between neuropathological burden and ante mortem clinical symptoms, to elucidate the contribution of key individual (gender, age at time of injury, time since injury, genotype, cardiovascular health and cognitive reserve) and injury characteristics (severity, frequency) to describe associations between neuropathological burden and clinical symptoms and to determine the prevalence of TBI-related parkinsonism, dementia and CTE in 8 participating brain banks. This U54 will develop the largest brain donor cohort with well-characterized histories of RHI and TBI across the severity spectrum and the tissue collected will be used for broad sharing through the UNITE (VA-BU-CLF) brain bank and the NIH biobank at ISMMS. The U54 will also develop a digital library of pathology slides that will be hosted and shared by FITBIR. The administrative core will provide overall leadership and organization to ensure regular, coordinated scientific interaction, harmonized data acquisition, and harmonized clinical and neuropathological assessment across sites. The administrative core will also manage all communication, reporting, dispute resolution, use of resources and meeting milestones. To accomplish these goals, the following components will be assembled: a Scientific Advisory Board (SAB) consisting of 5 leading independent scientific experts in neurology, neuropathology, TBI, RHI, AD, ADRD, and CTE; an Executive Committee (EC), the central decision-making and policy development group for the proposal; a Scientific Working Group (SWG) to ensure scientific advancement and productivity through sharing of scientific results and discussion; a Publications Committee; a Tissue Request Oversight committee and a Fiscal Management Committee. The Administrative Core will ensure that all U54 milestones and metrics for each project and core are met. Given the well-established, productive working relationships between the PI, project and core leaders and investigators at BUSM and ISMSS and their proven track record of success, we are confident that the Administrative Core can effectively support the 3 inter-linking cores and projects to fully achieve the proposed goals and milestones of this U54.

The overarching goals of the Brain Banking Core (BBC) are to conduct and foster research on RHI and TBI and to determine associations with AD, ADRD, CTE, and other neurodegenerative pathology as well as clinical outcomes. The BBC will include 8 brain bank cohorts, 6 from Boston University School of Medicine (BUSM) and the VA Boston Healthcare System: the BU Alzheimer Disease Center (BUADC), Framingham Heart Study (FHS), VA Post-Traumatic Stress Disorder (PTSD), VA amyotrophic lateral sclerosis (ALS), Chronic Effects of Neurotrauma (CENC) and VA-BU-CLF (UNITE) and 2 from the Icahn School of Medicine at Mount Sinai (ISMMS) to systematically evaluate the precise neuropathology of RHI and TBI-related neurodegeneration. These combined brain banks contain over 2500 cases, and include the largest neuropathologically confirmed autopsy cohort of CTE subjects (n= 361) in the world. In addition, the LETBI, CENC, ALS, and UNITE brain banks hold at least 50 cases of remote, moderately-severe TBI with a chronic cavitary lesion (cTBI). The specific aims of the BBC consist of fundamental Core functions, namely to perform state-of-the-art diagnostic neuropathology, optimally store and distribute CNS tissue and other biospecimens, and provide neuropathological data for Projects 1-3 and to the Federal Interagency Traumatic Brain Injury Research (FITBIR) for the general scientific community. All neuropathological protocols will be aligned with those proposed by the NINDS Neuropathological CTE Consensus Conference for biospecimen collection, blocking, staining and storage, which the PI led and helped establish. In addition, a digital library of the pathology slides will be generated for each participant and made publicly available. Finally, the BBC will work to develop novel methods for the assessment of RHI and cTBI-related injury to include axonal and white matter degeneration, gliosis, and inflammation. The specific aims also build upon the significant innovations of the PI and investigators with regard to RHI, cTBI, and CTE and focus on determining the pathological and clinical associations following brain impacts and injury. To accomplish these aims, the BBC will work in close collaboration with the Administration and Data Cores and Projects 1-3, as well as the associated ISMMS Alzheimer's Disease and Research Center Brain Bank and the BUADC. Overall, the BBC will provide a harmonized neuropathological workup and assessment in order to facilitate the storage and distribution of biospecimens, comprehensive diagnoses, digital library creation, and the development of novel quantitative neuropathological measures in order to best capture the chronic sequalae of RHI and TBI. Specimens and data collected by the BBC will be linked to RHI and TBI history determined in Project 1, harmonized clinical outcomes assessed in Project 2, and additional pathological and inflammatory measures determined in Project 3. The harmonized data will be used extensively across Projects 1-3 and made widely available for outside investigators.

Establishing an accurate neuropathological diagnosis is a critical function of the Alzheimer's Disease Center (ADC) Neuropathology Cores and is a prerequisite to all tissue-based research. Although chronic traumatic encephalopathy (CTE), primary age-related tauopathy (PART), argyrophilic grain disease (AGD) and aging- related tau astrogliopathy (ARTAG) are all age-related tauopathies, each has distinctive patterns of abnormal tau deposition. Additionally, each has specific, but overlapping, effects on cognitive and neuropsychiatric function. Neuropathological criteria to diagnose CTE, PART, AGD and ARTAG have been recently proposed, yet no modules exist to capture these disorders in the National Alzheimer's Coordinating Center (NACC) database. Without rigorous, reproducible protocols for the diagnosis of age-related tauopathies, their disease- specific contributors to late life cognitive and neuropsychiatric impairment may be overlooked and obscured. This proposal will draw on the neuropathological expertise of Drs. Ann McKee, Dennis Dickson, and John Crary, who have pioneered investigations of CTE, AGD and PART. We will use 250 cases of AD and age- related tauopathies from the Boston University, Mayo Clinic Jacksonville and Mount Sinai ADCs to identiify novel tau and inflammatory markers that accurately detect and distinguish the age-related tauopathies. After re-examining tissue from the NACC-Neuropathology Data Set (NDS), we will establish the frequency of CTE, PART, AGD and ARTAG among individuals who had ante-mortem clinical diagnoses of normal cognition, mild cognitive impairment, or dementia. We will determine the unique contribution of these disorders to clinical diagnosis and to cognitive and neuropsychiatric impairment. We will also determine whether examining under- studied brain regions, namely the prefrontal cortex, uncal gyrus and amygdala identifies new cases of age- related tauopathies and whether pathology in these regions contributes to neuropsychiatric impairment. Lastly, we will apply knowledge gained from this project to develop CTE, PART, AGD and ARTAG assessment and diagnostic modules that we will use to organize an international NIH consensus conference to harmonize the neuropathological diagnoses of the age-related tauopathies for general use. Overall, this proposal will address critical, yet still unknown issues related to CTE, PART, AGD and ARTAG: 1) Identification of novel tau and neuroinflammatory biomarkers to aid in detection and discrimination of the age-related tauopathies, 2) Determination of age-related tauopathy frequency among memory disorder clinic patients; 3) Determination of age-related tauopathy contribution to cognitive and neuropsychiatric impairment; and 4) Development of harmonized criteria for age-related tauopathy neuropathological diagnosis. This project will also enrich the existing NACC-NDS, making data on age-related tauopathies available to other researchers. Overall, the successful completion of this proposal will transform the way we conceptualize the tauopathies and will facilitate future research on the diagnosis, treatment, and prevention of AD and related disorders.

In 1997, the FHS began its brain donation program, and has 568 currently enrolled subjects and 241 who have come to autopsy. As a community-aging brain bank, there is a spectrum of pathologies present, including a significant number of participants that were cognitively intact at the time of death (e.g., CDR 0; 32%), mild cognitively impaired (19%), or demented (48%), including 34.2% with possible or probable AD. This spectrum of disease allows for the study of heterogeneous pathologies on clinical outcomes. Traditional pathological methods used to characterize the distribution of amyloid and tau throughout the brain are semi-quantitative and the diagnosis of AD is dependent on meeting specified thresholds of density and regional involvement. Neuropathological characterization of vascular disease into standard quantification methods is still not uniform and quantification of other pathologies (e.g., Lewy bodies, hippocampal sclerosis, argyrophilic grain disease, etc.) relies on estimation of regional density and a summary impression of overall distribution patterns. Accurate assessment of pathological burden is further complicated by the prevalence of mixed pathologies, which increases with advanced age. Digital technologies offer an exciting opportunity to attenuate the limitations of traditional semi-quantitative methods and provide a level of measurement that is significantly enhanced in its precision and objectivity. The proposed Neuropathology Core proposes to continue neuropathological characterization of FHS participants who come to autopsy integrating longitudinally applied semi-quantification methods with new technologies to allow precise quantification of AD and cerebrovascular pathologies. The aims of the Neuropathology Core are (1) perform state-of-the-art diagnostic neuropathology, (2) develop novel methods for qualitative and quantitative histopathological characterization of the tissue, (3) optimally store and distribute brain tissue, and (4) provide neuropathological data for Project 3 and other ancillary studies by both Framingham Heart Study-Brain Aging Program (FHS-BAP) and external investigators. FHS' neuropathological protocol is already aligned with the Boston University Alzheimer Disease Center (BU ADC) in biospecimen collection, blocking, staining and storage, and will be further aligned with 7 other brain bank cohorts through a newly funded U54 led by Neuropathology Core Leader, Ann McKee and co-Leader Thor Stein. In addition, a digital library of the pathology slides will be generated for each participant and through the Data Core, will be made publicly available.

Individuals who experience traumatic brain injury (TBI) are at increased risk for developing dementia and parkinsonism later in life. Exposure to repetitive head impacts (RHI) from contact sports and military service is also associated with a tau-based neurodegeneration, chronic traumatic encephalopathy (CTE). Our small case studies indicate that the neuropathological substrate of TBI-related neurodegeneration is a heterogeneous condition with varying degrees of beta-amyloid (Aß), phosphorylated tau (ptau), pTDP-43, and alpha-synuclein pathologies that does not conform to conventional Alzheimer's disease (AD) or AD related dementias (ADRD). Our studies also suggest that other pathologies, including gray and white matter atrophy, vascular pathology, neuronal, axonal and myelin loss, astrocytosis, and neuroinflammation contribute to neurodegeneration after TBI and RHI. Moreover, it is increasingly recognized that the type, frequency and severity of TBI or RHI and other genetic and non-genetic factors exert striking influence on the long-term outcome. TBI and RHI have not been well studied in brain bank cohorts, subsequently, the contribution of TBI and RHI to AD, ADRD, CTE and other pathologies is not known. There is a critical unmet need to determine the relationship of TBI and RHI to AD, ADRD, CTE and other pathologies, to understand the neuropathological phenotype of TBI, to determine the prevalence of TBI-related neurodegeneration and CTE in brain bank cohorts, and to determine the relationship of TBI and RHI to cognitive decline and parkinsonism. To accomplish our goals, we will leverage the infrastructure of our successful Understanding Neurological Injury and Traumatic Encephalopathy (UNITE) study (U01NS086659, R01AG057902) and our collaboration with Mount Sinai (U01NS086625). We will harmonize 8 novel brain banks: 6 at Boston University (BU) and 2 at Icahn School of Medicine at Mount Sinai (ISMMS). In this proposal, we will examine the association of RHI and TBI with AD, ADRD, CTE neuropathology and other pathologies and investigate genetic and non-genetic modifiers of these effects. The overarching hypotheses are: RHI and TBI will have distinct associations with AD, ADRD, CTE and other pathologies; these effects will be modified by genetic (e.g., APOE ?4, TMEM106b) and non-genetic factors (e.g., age of first exposure to RHI ) and TBI, age, cardiovascular disease, resistance, among other RHI/TBI characteristics and demographic, lifestyle, and medical histories ; and these pathologies will have direct associations with clinical outcomes of dementia and parkinsonism. This U54 will develop the largest brain donor cohort with well-characterized histories of RHI and TBI across the severity spectrum. This project will advance knowledge on the specific risks for the pathological development of AD, ADRD, CTE and other degenerative pathologies after RHI and TBI, establish the neuropathological features of TBI-related neurodegeneration, and determine the association of post-RHI and TBI neuropathologies with the clinical phenotypes of dementia and parkinsonism. This U54 proposal will lay the foundation for future strategies to intervene, prevent and treat TBI-related neurodegeneration and CTE.