Brain endothelial-specific adipose triglyceride lipase (ATGL) knockdown promotes cerebromicrovascular dysfunction in aging

Dysregulated brain lipid metabolism resulting in excessive accumulation of lipid droplets (LDs) has been implicated in aging and neurodegeneration. Most studies have focused on glial cells and neurons, while endothelial cells (ECs), key regulators of cerebral blood flow (CBF) and cognitive function, remain largely overlooked in the context of lipotoxicity and brain aging. We have recently shown that brain ECs are equally vulnerable to lipid accumulation with age. Moreover, lipid-laden brain ECs exhibited a transcriptional profile associated with reduced LD turnover, increased inflammation, and impaired blood-brain barrier (BBB) function, indicative of a dysfunctional phenotype. Based on our transcriptomic findings, we hypothesize that endothelial LD accumulation drives cerebromicrovascular dysfunction, impairing neurovascular coupling (NVC), reducing brain glucose uptake, disrupting BBB, and triggering neuroinflammation, ultimately leading to cognitive decline in aging. To mechanistically investigate the impact of age-related LD accumulation in brain ECs, we leveraged recent developments in brain endothelial-specific AAV technology (AAV.BI30). We custom-developed AAV.BI30 that carried shRNA against adipose triglyceride lipase (ATGL, an enzyme that mediates lipid hydrolysis, AAV-ATGL) or scrambled shRNA (AAV-control). Twelve-months old C57BL/6J mice were retro-orbitally injected with 2x1011 vg/animal of AAV-ATGL or AAV-control. Three months after transduction, functional ultrasound imaging and 18F-FDG PET-CT imaging was performed to assess neurovascular coupling responses and brain glucose uptake, respectively. Our results showed that AAV-ATGL successfully downregulated ATGL protein levels in isolated brain ECs compared to AAV-control. Brain EC-specific ATGL downregulation impaired NVC responses and reduced brain glucose uptake, indicating lipid accumulation-mediated endothelial dysfunction. Ongoing studies are further investigating the impact of ATGL knockdown and lipid accumulation in brain ECs on BBB function, neuroinflammation and cognitive function. Together, these results demonstrate for the first time that endothelial lipid accumulation is a driver of microvascular dysfunction in the aging brain and highlight lipid metabolism as a promising therapeutic target to preserve endothelial and cognitive function with aging. Funding was provided by NIH K01AG073613, R03AG095868, AFAR Junior Faculty Award, American Heart Association CDA1048544, HHDC Pilot grant and Stephenson Cancer Center, University of Oklahoma Health Campus. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.