Hippocampal sclerosis of aging (HS-Aging) is a major pathologic substrate of dementia but there currently are no validated strategies in the clinical setting to diagnose or treat the disease. HS-Aging affects ~15% of elderly persons and is associated with substantial cognitive impairment. Our group has studied this area extensively, leading to the following major hypothesis: thyroid hormone (TH) dysregulation contributes to HS-Aging pathogenesis. This novel pathogenetic mechanism may provide the basis to diagnose HS- Aging during life using CSF analyses, and to develop a therapeutic strategy. However, critical knowledge gaps remain in terms of characterizing the specific association between TH dysfunction and brain pathology, and the potential to target the mechanism for therapeutic purposes. We propose a research program to fill these knowledge gaps while testing key hypotheses via the following Specific Aims: Hypothesis 1: Clinical TH status is associated with presence and severity of HS-Aging pathology.
Specific Aim 1 : Test the hypothesis in a convenience sample (n=205, including cognitively intact and diverse non-HS-Aging dementia controls) from the University of Kentucky AD Center biobank. We will apply rigorous, quantitative digital pathologic methods to assess TDP-43 pathology, AD plaques/tangles, and ?- synucleinopathy for correlation with clinical TH status: self-reported TH disease and TH medications are well- documented. As expected in aged persons, more than 25% of the subjects exhibited clinical TH dysfunction. Hypothesis 2: CSF TH levels are associated with HS-Aging pathology and may provide a novel biomarker.
Specific Aim 2 : Evaluate TH (triiodothyronine, or T3) in CSF as a clinical biomarker of HS-Aging. We will assess human CSF TH levels with direct correlation with various subtypes of pathology. We also will test TH in clinical CSF from lumbar punctures, correlated with established AD-related biomarkers (A? and tau) and HS-Aging SNPs, with the goal of developing a new method to diagnose HS-Aging in living persons. We have obtained CSF from autopsied individuals (n=104) and clinical CSF samples (n=195) to accomplish this Aim. Hypothesis 3: Specific HS-Aging risk-associated gene variants induce altered brain TH levels with extensive impact on brain gene expression, and orally available drugs can alter this pathogenetic mechanism.
Specific Aim 3 : Define gene expression changes relevant to TH and HS-Aging. We will analyze human genomics databases to define how gene changes linked to HS-Aging risk contribute to variability in ABCC9 and SLCO1C1 (a major brain TH transporter) expression. We will test human cells (cultured human hESC astrocytes and lymphoblastoid cells transformed with DNA from people with known genotypes and pathology) to determine the potential for manipulating the levels of ABCC9, of TH transporter SLCO1C1, and of other TH- regulated genes. Finally, in mice, we will test how TH-responsive gene expression, neuropathology, and neurobehavior are affected in vivo by treatment with TH and/or the ABCC9 agonist drug glimepiride.

Public Health Relevance

We are performing studies of a brain disease (hippocampal sclerosis of aging) that mimics Alzheimer's disease in the clinical setting, and which affects millions of Americans. Our group has studied this disease extensively, leading to the following major hypothesis: thyroid hormone dysregulation contributes to hippocampal sclerosis dementia. The experiments described in this proposal are necessary for developing future clinical strategies aimed at detecting and ultimately preventing this underappreciated, prevalent, and high-morbidity brain disease.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
5R01AG057187-02
Application #
9526982
Study Section
Clinical Neuroscience and Neurodegeneration Study Section (CNN)
Program Officer
Opanashuk, Lisa A
Project Start
2017-07-15
Project End
2022-03-31
Budget Start
2018-04-15
Budget End
2019-03-31
Support Year
2
Fiscal Year
2018
Total Cost
Indirect Cost
Name
University of Kentucky
Department
Neurosciences
Type
Schools of Medicine
DUNS #
939017877
City
Lexington
State
KY
Country
United States
Zip Code
40526
Niedowicz, Dana M; Özcan, Sabire; Nelson, Peter T (2018) Glimepiride Administered in Chow Reversibly Impairs Glucose Tolerance in Mice. J Diabetes Res 2018:1251345
Brenowitz, Willa D; Han, Fang; Kukull, Walter A et al. (2018) Treated hypothyroidism is associated with cerebrovascular disease but not Alzheimer's disease pathology in older adults. Neurobiol Aging 62:64-71
Katsumata, Yuriko; Nelson, Peter T; Estus, Steven et al. (2018) Translating Alzheimer's disease-associated polymorphisms into functional candidates: a survey of IGAP genes and SNPs. Neurobiol Aging 74:135-146
Fardo, David W; Katsumata, Yuriko; Kauwe, John S K et al. (2017) CSF protein changes associated with hippocampal sclerosis risk gene variants highlight impact of GRN/PGRN. Exp Gerontol 90:83-89
Wang, Wang-Xia; Fardo, David W; Jicha, Gregory A et al. (2017) A Customized Quantitative PCR MicroRNA Panel Provides a Technically Robust Context for Studying Neurodegenerative Disease Biomarkers and Indicates a High Correlation Between Cerebrospinal Fluid and Choroid Plexus MicroRNA Expression. Mol Neurobiol 54:8191-8202
Ighodaro, Eseosa T; Nelson, Peter T; Kukull, Walter A et al. (2017) Challenges and Considerations Related to Studying Dementia in Blacks/African Americans. J Alzheimers Dis 60:1-10
Cykowski, Matthew D; Powell, Suzanne Z; Schulz, Paul E et al. (2017) Hippocampal Sclerosis in Older Patients: Practical Examples and Guidance With a Focus on Cerebral Age-Related TDP-43 With Sclerosis. Arch Pathol Lab Med 141:1113-1126