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Fibronectin-splice variant containing extra domain A (Fn-EDA) is associated with smooth muscle cells (SMCs) following vascular injury. The role of SMC-derived Fn-EDA in SMC phenotypic switching or its implication in neointimal hyperplasia remains unclear. Herein, using human coronary artery sections with a bare metal stent, we demonstrate the expression of Fn-EDA in the vicinity of SMC-rich neointima and peri-strut areas. In mice, Fn-EDA colocalizes with SMCs in the neointima of injured carotid arteries and promotes neointima formation in the comorbid condition of hyperlipidemia by potentiating SMC proliferation and migration. No sex-based differences were observed. Mechanistic studies suggested that Fn-EDA mediates integrin- and TLR4-dependent proliferation and migration through activation of FAK/Src and Akt1/mTOR signaling, respectively. Specific deletion of Fn-EDA in SMCs, but not in endothelial cells, reduced intimal hyperplasia and suppressed the SMC synthetic phenotype concomitant with decreased Akt1/mTOR signaling. Targeting Fn-EDA in human aortic SMCs suppressed the synthetic phenotype and downregulated Akt1/mTOR signaling. These results reveal that SMC-derived Fn-EDA potentiates phenotypic switching in human and mouse aortic SMCs and neointimal hyperplasia in the mouse. We suggest that targeting Fn-EDA could be explored as a potential therapeutic strategy to reduce neointimal hyperplasia., Introduction Percutaneous coronary intervention (PCI) with stent implantation is commonly performed for the treatment of coronary artery disease. Neointimal hyperplasia with smooth muscle cell (SMC) migration and proliferation and extracellular [...]

Loss of function of the lipid kinase diacylglycerol kinase ε (DGKε), encoded by the gene DGKE, causes a form of atypical hemolytic uremic syndrome that is not related to abnormalities of the alternative pathway of the complement, by mechanisms that are not understood. By generating a potentially novel endothelial specific Dgke-knockout mouse, we demonstrate that loss of Dgke in the endothelium results in impaired signaling downstream of VEGFR2 due to cellular shortage of phosphatidylinositol 4,5-biphosphate. Mechanistically, we found that, in the absence of DGKε in the endothelium, Akt fails to be activated upon VEGFR2 stimulation, resulting in defective induction of the enzyme cyclooxygenase 2 and production of prostaglandin E2 (PGE2). Treating the endothelial specific Dgke-knockout mice with a stable PGE2 analog was sufficient to reverse the clinical manifestations of thrombotic microangiopathy and proteinuria, possibly by suppressing the expression of matrix metalloproteinase 2 through PGE2-dependent upregulation of the chemokine receptor CXCR4. Our study reveals a complex array of autocrine signaling events downstream of VEGFR2 that are mediated by PGE2, that control endothelial activation and thrombogenic state, and that result in abnormalities of the glomerular filtration barrier.

Abstract: Resting platelets rely on oxidative phosphorylation (OXPHOS) and aerobic glycolysis (conversion of glucose to lactate in the presence of oxygen) to generate adenosine triphosphate, whereas activated platelets exhibit a high level of aerobic glycolysis, suggesting the existence of metabolic flexibility in platelets. Mitochondrial pyruvate dehydrogenase kinases (PDK 1-4) play a pivotal role in metabolic flexibility by inhibiting pyruvate dehydrogenase complex. We determined whether metabolic reprogramming, diverting metabolism from aerobic glycolysis back to OXPHOS, would inhibit platelet function. PDKs activity in human and mouse platelets was inhibited with dichloroacetic acid (DCA), a potent inhibitor of all 4 forms of PDK. Human and mouse platelets pretreated with DCA exhibited decreased platelet aggregation to suboptimal doses of collagen, convulxin, thrombin, and adenosine diphosphate concomitant with decreased glucose uptake. Bioenergetics profile revealed that platelets pretreated with DCA exhibited decreased aerobic glycolysis in response to convulxin only. Furthermore, DCA inhibited ATP secretion, thromboxane A2 generation, and tyrosine phosphorylation of Syk and PLCγ2 in response to collagen or convulxin in human and mouse platelets (P < .05 vs vehicle treated). In the flow chamber assay, human and mouse blood pretreated with DCA formed smaller thrombi when perfused over collagen for 10 minutes at an arterial shear rate of 1500 s−1 (P < .05 vs control). Wild-type mice pretreated with DCA were less susceptible to thrombosis in the FeCl3-induced carotid and laser injury–induced mesenteric artery thrombosis models (P < .05 vs vehicle control), without altering hemostasis. Targeting metabolic plasticity with DCA may be explored as a novel strategy to inhibit platelet function.