PROJECT SUMMARY Alzheimer's Disease and Alzheimer's Disease Related Dementias (AD/ADRDs) are the most common forms of dementia. Due to the lack of effective approaches for prevention and treatment of these disorders, the toll on individuals, caregivers and society is currently enormous. Vascular contribution to cognitive impairment and dementia (VCID) is characterized by the aging neurovascular unit being confronted with, and failing to cope with, biological insults, resulting in cognitive decline. VCID, defined as an ADRD, is the second most common cause of dementia after AD and is also a frequent comorbidity with AD. Thus, an in-depth study on VCID will offer a better understanding of its pathology and consequently will result in novel approaches that improve the prevention and management of AD/ADRD. Microglia and resident macrophages, important members of the neurovascular unit, are involved in the early steps of AD/ADRD development and can be identified as potential therapeutic targets. Recently, metabolic reprogramming including glycolytic switching has been emphasized in activation of myeloid cells. However, the role of glycolytic reprogramming in microglia/macrophage activation in VCID has not been explored. Our current NEI-funded Parent project on “Targeting myeloid glycolysis in pathological ocular angiogenesis” (R01 EY030500-01) aims to uncover the role of Pfkfb3-mediated glycolysis in macrophages/microglia in pathological retinal angiogenesis. The Parent project focuses on the role of myeloid glycolysis in retinal dysfunction, especially in pathological vascular growth. Studies in the Parent project have shown that macrophages/microglia in the retinas of the mouse model of oxygen-induced retinopathy are hyper- glycolytic, as evidenced by high levels of glycolytic molecules and regulators/activators of glycolysis, including Pfkfb3. Pfkfb3-mediated glycolysis in macrophages/microglia activates pathways of hypoxic induced factors (HIFs) and histone acetylation, leading to increased production of pro-inflammatory and pro-angiogenic factors and subsequent development of dysfunctional vasculature. These results imply a possible role of microglia/macrophage Pfkfb3-mediated glycolysis in regulating neuroinflammation and cognitive destruction. Thus, this Supplement application will take advantage of the myeloid Pfkfb3-deficient mouse model generated from the Parent R01 to uncover the effect of microglia/macrophage glycolysis on neuroinflammation, cerebral vascular function and cognitive function. Importantly, we will use unbiased system biology approaches such as light sheet microscopy and single cell RNA sequencing to determine the effect of Pfkfb3-mediated glycolysis on activation of microglia/macrophage themselves and on other neurovascular unit cells such as endothelial cells, pericytes, astrocytes and neurons in a well-accepted mouse VCID model. This study will uncover how glycolytic reprogramming in microglia/macrophage causes dysfunction...