Alexandra Badea, PhD - US grants

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Atlases; CRISP; Computer Retrieval of Information on Scientific Projects Database; Doctor of Philosophy; Funding; Grant; Image; Inbred Mouse; Institution; Investigators; NIH; National Institutes of Health; National Institutes of Health (U.S.); Neurosciences; Ph.D.; PhD; Price; Recombinants; Research; Research Personnel; Research Resources; Researchers; Resources; Services; Societies; Source; System; System, LOINC Axis 4; United States National Institutes of Health; imaging; interoperability; pricing

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Perform fluorescence imaging of mouse brains with optical CT and correlation with MR in mice with endogenous green fluorescent protein distribution in the brain.

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. This project has changed direction and now includes optimizing the image acquisition parameters, blood pool concentration, and scan time to achieve a high-resolution (43 microns) mouse brain atlas. This is work in progress, and we hope to present it at an upcoming Society for Neuroscience (SFN) meeting.

DESCRIPTION (provided by applicant): The etiology of Alzheimer's disease (AD) is not yet known, therapies are not yet available, yet its debilitating effects will impact ~ 10 million in th US alone by 2050. Early imaging of AD phenotypes and measurable outcomes of proposed therapies are urgently needed. This K01 award will allow the candidate, Alexandra Badea, PhD, to train at Duke University Medical Center to develop into an independent investigator in quantitative methods for assessing neurodegenerative diseases in small animal models. The goal is to achieve through training a multidisciplinary perspective on disease biomarkers. This will be possible under guidance from experienced mentors with distinct expertise, all located on the Duke University West Campus. Dr. G Allan Johnson, director of the Center for In Vivo Microscopy (CIVM) is an expert in preclinical animal imaging. The imaging equipment at CIVM can offer an integrated view on aspects of brain structure and function in small animal models. Dr. Carol Colton laboratory examines the role of the innate immune response in the brain and its role in neurodegeneration. Her CVN mouse offers a model in which AD most pathologies are replicated and therapies can be tested. Dr. William Wetsel, director of the Neuroendocrine and Behavioral Facility at Duke is an expert on behavioral assays that will independently evaluate disease progression. The training process will cover: 1) neuroanatomy, pathology, and behavior in the context of AD-like pathology; 2) imaging protocol de- sign and MR sequence programming; 3) advanced image processing, statistics, and multimodal integration; 4) responsible conduct of research. We will focus on integrating high-resolution imaging with cognitive measures, to provide multivariate biomarkers for AD models. The candidate expects to advance methods for: 1) image analysis for morphometry, with a focus on diffusion tensor and vascular data; 2) integration of multiple anatomical, physiological and cognitive markers. The Specific Aims will address: 1) the value of magnetic resonance histology and diffusion tensor imaging in charting AD like phenotypes; 2) in vivo multivariate imaging biomarkers addressing the vascular aspect; 3) the relationship of imaging markers with cognitive and olfactory deficits, and the rescue of these phenotypes response following intranasal therapy. This award will help establish a timeline of imaging and cognitive changes in mouse models of AD, and provide anatomical, vascular and cognitive markers for disease progression, and as measurable outcomes of putative therapies. The proposed training will equip the candidate with unique a set of skills to become a thought leader in multidisciplinary approaches for characterizing models of neurodegenerative diseases, such as AD, and evaluating proposed therapies.

Biological sex and APOE genotype are now well known to impact the susceptibility to Alzheimer's disease (AD). However, although well studied, the underlying mechanisms that facilitate AD pathology in females compared to males or, in individuals expressing an APOE4/4 compared to an APOE3/3 genotype, remain unknown. Our preliminary data clearly indicate that the immune response to disease is one principal point of commonality between male/female differences, APOE genotype and AD. Both estrogen levels and APOE genotype alter ?activation status? of brain microglia, thereby impacting brain inflammation. The presence of estrogen is commonly shown to be anti-inflammatory, acting to maintain acquired immune privilege and restrict pro-inflammatory responses. The presence of the APOE4 gene allele in females superimposes an enhanced response to infectious pathogens through its effects on estrogen receptor activation and through APOE4-mediated changes in regulation of immunity. These interactions between inflammation and biological sex and inflammation and APOE genotype have become extremely important to understand in more detail because of the strong, increasing data demonstrating a direct involvement of inflammation in the onset and progression of AD. In this proposal we will establish mouse models that enable a direct comparison of AD- like pathology between male and female mice that will also carry a human APOE3 or APOE4 gene allele (in place of the mouse APOE gene alleles) and will represent either familial or sporadic AD. Baseline morphological and biochemical/gene data will be collected at specific ages from each mouse strain and will serve as base line comparisons to establish male/female differences, APOE and biological sex-regulated APOE- based differences. The relationship of these base line values with age will be correlated to established AD pathologies. Our preliminary data strongly implicate a evolutionary significant metabolic pathway involving arginine/ornithine utilization that is regulated by immunity and is both biological sex and APOE genotype specific. This pathway will be examined in detail using heavy isotope labeling and LC/MS to trace and define specific pathway differences between models. Finally, the impact of estrogen loss (equivalent to the induction of menopause in human women) on the baseline data and the specific pathway analyses will be used to better understand how age related loss of estrogen impacts AD-like pathology.  

There is a rapid growth in the number of people living with Alzheimer?s disease, and only 25% get diagnosed; still we do not know its etiology or have effective treatments. To examine factors which contribute to switching from normal to pathological aging we focus on the APOE polymorphic alleles. The causes for increased risk, or conversely resilience, conferred by the major APOE alleles are not known. The APOE4/4 genotype is the main genetic risk for late onset Alzheimer?s disease (AD), and is associated with a 30-55% risk of developing mild cognitive impairment or AD by age 85, compared to 10-15% for the APOE3/3 genotype. In contrast APOE2 is under-represented in AD patients, and it has been associated with longevity. To help understand the mechanisms through which APOE genes and their products differentially modulate the brain and its circuits to switch from healthy to pathological aging, we will take an integrative and unbiased multi-disciplinary approach using homozygous targeted replacement APOE2, APOE3, and APOE4 mice expressing the major human APOE isoforms, under the control of the mouse endogenous ApoE promoter. APOE2 mice have a significantly longer lifespan than APOE3 mice, which in turn have a significantly longer lifespan than APOE4 mice. These mice reasonably match the human APOE-genotype/lifespan data. To model the human immune response to aging we will use double-transgenic mice that express human NOS2 gene products. This modification enables nitric oxide (NO) production and immune activity regulated by NO to better mimic the human response. Our models include male and female APOE2/HN (APOE2/2 + human NOS2 on a mouse Nos2-/- background), APOE3/HN, and APOE4/HN mice, at 2 ages corresponding to middle and old human age. Mice will be characterized with a cognitive behavioral battery, and with MRI to determine selective vulnerability of brain networks. Our imaging measures will be based on volume, vascular perfusion, and diffusion tensor imaging; and will provide connectomes and network measures. RNA-Seq transcriptomics will identify differential expression of gene products associated with APOE genotypes, during aging. We will use an unbiased statistical approach to map molecular pathways underlying the behavioral and imaging phenotypes for aging. Our efforts will help build models that explain the influence of APOE genotypes on age and AD associated network vulnerability. We expect to hone in on pathways involved in aging, AD, inflammation, and oxidative phosphorylation. To test models, we will add a stressor conferring risk in aging and AD, through a high fat/high sugar diet (mimicking the Western diet). We will assess behavioral, and MRI phenotypes, in conjunction with transcriptomics, and determine through pathway analysis how diet shifts the predicted outcomes in male and female APOE2/HN, APOE3/HN and APOE4/HN mice. Our research will reveal mechanisms through which APOE interacts with environmental stressors to confer vulnerability, or resilience to select brain circuits during aging.