Acetate and Endothelial Pathobiology

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Chronic vascular inflammation is a hallmark of atherosclerosis, pulmonary arterial hypertension (PAH) and related conditions. It is also one of the principal causes of endothelial- to-mesenchymal transition (EndMT). We have recently demonstrated that disruption of EndMT, achieved by inhibiting endothelial-specific TGFβ signaling input, results in extensive (~70%) regression of established atherosclerotic lesion and prevention of development of new ones. It also prevents development of hypoxia-induced PAH. These data suggest that EndMT is key to the development and progression of illnesses associated with chronic inflammation, such as atherosclerosis, PAH, and transplant arteriopathy. However, a therapeutic strategy that relies on suppressing EndMT via control of endothelial TGFβ signaling is complicated because of the need of endothelial-specific delivery of therapeutic agents (systemic inhibition of TGFβ signaling is fraught with side effects and has been shown to promote atherosclerosis via its effects on smooth muscle cells). For these reasons, we focused on identifying another EndMT control point that can serve as an effective therapeutic target. Since endothelial cells have unique metabolic requirements and pathways, we concentrated on identifying potential metabolic-related control of EndMT. Our preliminary studies indicate that there indeed is metabolic control of EndMT that operates via acetylation-dependent regulation of TGFβ signaling. Moreover, the Ac-CoA needed for these acetylation events appears to be in large part derived atypically from acetate. Our goal in this application is to rigorously define and characterize the unique endothelial metabolic pathway that leads to generation of cytoplasmic Ac-CoA from acetate and the role that this Ac- CoA plays in TGFβ signaling. This will be tested in vitro and in vivo using genetically engineered mice. Finally, we will test two distinct translational strategies – a nanoparticle-based EC-specific RNAi delivery, and an oral specific inhibitor to test the effect of suppression of acetate-based Ac-CoA production on the development and progression of atherosclerosis