CTGF is a Modifiable Mediator of Flow-dependent Atherosclerosis under Peripheral Artery Disease Conditions

BackgroundPeripheral arterial disease (PAD) is the 3rd leading type of atherosclerotic disease (ASD) morbidity. Arterial stiffness is intimately connected to the onset and progression of peripheral artery disease (PAD). The role of arterial stiffening on flow-mediated atherosclerotic plaque formation is not well understood. The objective of this study is to discover endothelial cell (EC) pathways under PAD conditions and test the modifiability of these pathways on ASD. MethodsPAD conditions in mice were conferred by partial carotid ligation to induce disturbed Flow (D-flow) in pre-stiffened Fibulin-5 knockout (KO) mice that lack normal elastin function. EC pathways, including Connective tissue growth factor (CTGF/CCN) were quantified by gene analysis and histology. Atherogenic mice had PCSK9 infection + high fat diet. CTGF was inhibited in an EC-specific knockout (ECKOCTGF) and with a CTGF antibody (FG-3149). Human vascular tissue was used to validate PAD biomechanics and CTGF upregulation. ResultsBiomechanical testing demonstrated that d-flow KO arteries mimic biomechanics of PAD arteries. RNA microarray, qPCR, and immunohistochemistry identified EC plasticity in these arteries compared to WT and KO under stable flow. Under atherogenic conditions, KO arteries demonstrated vulnerable plaques not seen in WT animals. CTGF expression was increased by d-flow, in KO arteries, in aged (18 months) WT arteries, and vascular tissue under d-flow. CTGF inhibition by ECKOCTGF favorably improved plaque characteristics in male but not female animals. FG-3149 treatment of ECWTCTGF male animals delivered similar benefits to plaque characteristics and arterial compliance. ConclusionECs in PAD arteries exist under a complex hemodynamic environment that integrates stiffness and d-flow into an atherogenic and inflammatory environment. Stiffness + d-flow stimulates precocious onset of EC plasticity and a vulnerable plaque phenotype. CTGF is a matricellular protein that can tune fibro-inflammatory pathways. CTGF is a prominent mediator of D-flow-mediated arterial remodeling and focal atherosclerotic plaque remodeling. Inhibition of CTGF improves plaque phenotype and arterial compliance. CTGF-associated pathways hold promise as therapeutic targets for PAD patients.