Mitochondrial dysfunction is linked to the onset and progression of Alzheimer's disease (AD), including the deposition of plaques and neurofibrillary tangles that are hallmarks of this disease. The premise of this study is derived from multiple lines of evidence indicating that impairments in neural as well as peripheral bioenergetics are related to cognitive decline and may contribute to AD pathology. Despite mounting evidence implicating mitochondria as promising targets for AD prevention and therapy, the mechanisms underlying bioenergetic decline observed across tissues remain unclear. Seminal studies have demonstrated that circulating factors play a key role in aging and multiple age-related disorders. We propose that circulating, blood-borne, factors mediate systemic bioenergetic decline in AD and its prodrome, mild cognitive impairment (MCI). Our preliminary studies demonstrate that non-cellular components, in human serum, can mediate mitochondrial function in a manner consistent with observations linking cognitive impairment and low bioenergetic capacity.
The aims of this proposal are to identify mediators of systemic bioenergetic capacity 1) across stages of AD and the 3 year progression of dementia and pathology; and 2) in response to exercise, a promising AD intervention widely recognized to have systemic bioenergetic benefits. Circulating factors including peptides, lipid metabolites, RNAs, cytokines; and more recently, exosomes, have been suggested to be involved in various age-related disorders. In order to address the complexities of this line of research, we have developed a novel systematic approach for examining human serum, in-vitro, to identify the components responsible for mediating bioenergetic capacity across multiple cell types. We will utilize serum fractionation / subfractionation and reiterative respirometric profiling of neurons and peripheral cells to determine which serum components (exosomes, free proteins, and/or free metabolites) are capable of mediating differences in bioenergetic capacity associated with AD status, progression, and response to intervention. Individual serum components will be analyzed by RNAseq, proteomics, and metabolomics to identify circulating factors that are differentially expressed based on AD status, progression, and response to intervention. This project will be completed in a highly cost-effective and efficient manner by utilizing samples from ongoing studies at our NIH funded WFSM AD Core Center (ADCC) and AD Cooperative Study (ADCS) sites across the country. The results of this study will provide key mechanistic insights into mediators of systemic AD pathology and could shift the focus of AD prevention and therapy to include strategies targeting mitochondrial bioenergetics and its regulators. The robust framework of this study will generate an extensive repository of bioenergetic, proteomic, metabolomic, and RNAseq data linked to biological specimens and clinical outcomes that will be available to the broader research community to support future research.
Systemic mitochondrial dysfunction plays a central role in the onset and development of Alzheimer's disease. This project will identify circulating factors that mediate mitochondrial bioenergetics over the 3 year progression of AD and in response to exercise intervention. The results of this study will provide novel mechanistic insights into the development of systemic AD pathology and support the development of novel therapeutic strategies that target mitochondrial bioenergetics and its regulators.
