Large Extracellular Vesicle-Associated Rap1 Accumulates in Atherosclerotic Plaques, Correlates With Vascular Risks and Is Involved in Atherosclerosis.

RATIONALE: Metabolic syndrome (MetS) is a cluster of interrelated risk factors for cardiovascular diseases and atherosclerosis. Circulating levels of large extracellular vesicles (lEVs), submicrometer-sized vesicles released from plasma membrane, from MetS patients were shown to induce endothelial dysfunction, but their role in early stage of atherosclerosis and on vascular smooth muscle cells (SMC) remain to be fully elucidated. OBJECTIVE: To determine the mechanisms by which lEVs lead to the progression of atherosclerosis in the setting of MetS. METHODS AND RESULTS: Proteomic analysis revealed that the small GTPase, Rap1 was overexpressed in lEVs from MetS patients compared with those from non-MetS subjects. Rap1 was in GTP-associated active state in both types of lEVs, and Rap1-lEVs levels correlated with increased cardiovascular risks, including stenosis. MetS-lEVs, but not non-MetS-lEVs, increased Rap1-dependent endothelial cell permeability. MetS-lEVs significantly promoted migration and proliferation of human aortic SMC and increased expression of proinflammatory molecules and activation of ERK (extracellular signal-regulated kinase) 5/p38 pathways. Neutralization of Rap1 by specific antibody or pharmacological inhibition of Rap1 completely prevented the effects of lEVs from MetS patients. High-fat diet-fed ApoE-/- mice displayed an increased expression of Rap1 both in aortas and circulating lEVs. lEVs accumulated in plaque atherosclerotic lesions depending on the progression of atherosclerosis. lEVs from high-fat diet-fed ApoE-/- mice, but not those from mice fed with a standard diet, enhanced SMC proliferation. Human atherosclerotic lesions were enriched in lEVs expressing Rap1. CONCLUSIONS: These data demonstrate that Rap1 carried by MetS-lEVs participates in the enhanced SMC proliferation, migration, proinflammatory profile, and activation of ERK5/p38 pathways leading to vascular inflammation and remodeling, and atherosclerosis. These results highlight that Rap1 carried by MetS-lEVs may be a novel determinant of diagnostic value for cardiometabolic risk factors and suggest Rap1 as a promising therapeutic target against the development of atherosclerosis. Graphical Abstract: A graphical abstract is available for this article.

Aging and glycation promote erythrocyte phagocytosis by human endothelial cells: Potential impact in atherothrombosis under diabetic conditions.

BACKGROUND AND AIMS: Atherothrombotic plaques of type 2 diabetic (T2D) patients are characterized by an increased neovascularization and intraplaque hemorrhage. The clearance of erythrocytes may be carried out by vascular cells. We explored the potential of human endothelial cells to bind and phagocyte in vitro aged and/or glycated erythrocytes as well as erythrocytes obtained from diabetic patients. METHODS: Fresh, aged and glycated-aged erythrocytes from healthy volunteers and T2D patients were tested for their binding and phagocytosis capacity as well as the potential functional consequences on endothelial cells (viability, proliferation and wound healing capacity). Immunohistochemistry was also performed in human carotid atherothrombotic samples (from patients with or without T2D). RESULTS: Aging and glycation of erythrocytes induced phosphatidylserine (PS) exposure and oxidative stress leading to enhanced endothelial cell binding and engulfment. Phagocytosis by endothelial cells was more pronounced with aged and glycated erythrocytes than with fresh ones. Phagocytosis was enhanced with T2D versus healthy erythrocytes. Furthermore, endothelial wound healing potential was significantly blunted after exposure to glycated-aged versus fresh erythrocytes. Finally, we show that interactions between erythrocytes and endothelial cells and their potential phagocytosis may occur in vivo, in atherothrombotic conditions, in neovessels and in the luminal endothelial lining. CONCLUSIONS: Endothelial cells may play an important role in erythrocyte clearance in an atherothrombotic environment. Under diabetic conditions, erythrocyte glycation favors their engulfment by endothelial cells and may participate in endothelial dysfunction, thereby promoting vulnerable atherothrombotic plaques to rupture.

Synthesis and Automated Labeling of [18F]Darapladib, a Lp-PLA2 Ligand, as Potential PET Imaging Tool of Atherosclerosis.

Atherosclerosis and its associated clinical complications are major health issues in industrialized countries. Lipoprotein-associated phospholipase A2 (Lp-PLA2) was demonstrated to play an important role in atherogenesis and to be a potential risk prediction factor of plaque rupture. Darapladib is one of the most potent Lp-PLA2 inhibitors with an IC50 of 0.25 nM. Using its affinity for Lp-PLA2, we describe herein the total synthesis of darapladib radiolabeling precursor and the automated radiolabeling process for positron emission tomography (PET) imaging via an arylboronate moiety. The tracer thus obtained was tested in a mouse model of atherosclerosis (ApoE KO) and compared with the widely used [18F]fluorodeoxyglucose ([18F]FDG) PET tracer, known to label metabolically active cells. [18F]Darapladib showed a significant accumulation within mice aortic atheromatous plaques dissected out ex vivo compared to [18F]FDG. Incubation of the radiotracer with human carotid samples showed a strong accumulation within the atherosclerotic plaques and supports its potential for use in PET imaging.

Acute carotid artery thrombosis: description of 12 surgically treated cases.

The morbidity and mortality of stroke secondary to acute internal carotid artery thrombosis range from 40 to 69% and from 15 to 55%, respectively, after purely medical treatment. This report describes a series of 12 patients who underwent urgent surgical treatment for primary acute carotid artery thrombosis between January 1999 and December 2002. Upon admission, all patients had severe neurologic deficits contralateral to carotid artery thrombosis. One patient experienced ongoing changes in the level of consciousness. The interval between the onset of symptoms and admission was less than 6 hr in all cases. Initial work-up in all patients included a brain computed tomographic scan with contrast injection and carotid duplex scan. The operative procedure consisted of carotid thomboemdarterectomy after shunt placement with prosthetic patch closure. Intraoperative angiography was performed in all cases. Following treatment, we observed deterioration of neurologic status leading to death in one case; improvement with partial regression of initial neurologic deficit in two cases, including one patient who died from causes unrelated to carotid artery disease; and full neurologic recovery in nine cases. The delay to revascularization was longer than 6 hr in both patients who died. These data support surgical intervention for carotid artery thrombosis in selected patients without major disturbances of consciousness or hemorrhagic infarction, provided that the delay to revascularization is less than 6 hr.

Endovascular repair for acute rupture of the descending thoracic aorta.

PURPOSE: To report the endovascular treatment of acute descending thoracic aortic rupture as an alternative to open surgery in high-risk patients. METHODS: Between November 1999 and April 2001, 10 patients (7 men; median age 75 years) underwent endovascular stent-grafting of the descending thoracic aorta for acute rupture from an aneurysm (n=7) or blunt trauma (n=3). All patients were evaluated as high operative risk. The aortic rupture was associated with isolated mediastinal hematomas (n=7), left hemothorax (n=2), or aortobronchial fistula (n=1). The Excluder Thoracic Endoprosthesis was used predominantly. RESULTS: The mean interval to the endovascular repair was 45.3+/-28.4 hours. All stent-grafts were successfully deployed. Two patients required common iliac artery access, and 2 needed covered stents for iatrogenic iliac artery rupture. There was 1 postoperative death (myocardial infarction) and no renal failure, neurological complications, embolization, stent-graft migration, or perigraft leak. One patient died 4 months later from an unrelated cause. At a mean follow-up of 7.9+/-5.1 months, all aneurysms and rupture sites were excluded with no evidence of endoleak or hematoma. CONCLUSIONS: Endoluminal treatment is a feasible technique for the management of acute rupture of the descending thoracic aorta. Long-term studies are required to assess the effectiveness and durability of this technique in comparison to open repair.

Improvement in proximal aortic endograft fixation: an experimental study using different stent-grafts in human cadaveric aortas.

PURPOSE: To compare the proximal fixation characteristics of different types of stent-grafts (SG) and the adjunctive effect of a proximally placed Palmaz stent. METHODS: Human cadaveric aortas were obtained at autopsy and cut into 30 aortic segments. Appropriately oversized (10% to 20%) commercial stent-grafts (Zenith, Ancure, Excluder, Talent) and 4 configurations of homemade Palmaz-based stent-grafts (polytetrafluoroethylene or polyester coverings each with no uncovered proximal edge or a 20-mm bare section of stent) were implanted 20 mm into an aortic segment and balloon dilated. Each segment was placed in an experimental apparatus to measure the dislodgment force. Bare Palmaz stents were used to reinforce the proximal fixation of the commercial stent-grafts, and the measurements were repeated. Manual anastomoses were made and their dislodgment force tested for comparison. RESULTS: The median dislodgment force ranged from 6.5 N for the Excluder to 26.5 N for the Zenith (8.0 N for the Talent, 11.8 N for the Ancure, and 8.1 to 10.7 N for the various Palmaz stent-graft designs). There was no significant difference between the Zenith and the Ancure groups or between the Excluder and the Talent groups. However, the Zenith and Ancure devices required significantly higher (p=0.0004) force (approximately 25%) to displace them than the other stent-grafts tested. With the Palmaz stent added to the proximal attachment site, the median dislodgment force for the different commercial endografts was significantly improved for all devices (p<0.03): 34% for the Zenith device, 69% for the Ancure, 73% for the Talent, and 80% for the Excluder endoprosthesis. CONCLUSIONS: The Zenith stent-graft had the best resistance to dislodgment. An additional Palmaz stent placed at the proximal attachment site greatly improves endograft fixation regardless of the type of stent-graft. For complex aneurysm necks or for intraoperative type I endoleak management, an adjunctive Palmaz stent could be used.

Dissection of the abdominal aorta in blunt trauma: Endovascular or conventional surgical management?

BACKGROUND: Dissection of the abdominal aorta caused by blunt trauma is a rare injury, often complicated by thrombosis within the true and false lumens and sometimes aortic rupture. The mortality rate with conservative medical management is approximately 75%, whereas it ranges from 18% to 37% with surgical treatment. METHODS: At our institution, 7 of the 87 patients admitted because of blunt aortic trauma, between January 1995 and January 2002, had abdominal aortic dissection. RESULTS: Four patients were treated using endovascular techniques by percutaneous stent placement. The indications for endovascular management were lower limb ischemia in one case and extension of the dissection in two; one patient was asymptomatic. Aortic dissection was complicated by ischemic paraplegia in two patients, and both were treated by conventional operative repair. One patient was managed medically because of a minimal intimal disruption. No deaths were related to the aortic dissection or its treatment. Angiographic and computed tomographic (CT) studies showed thrombosis of the false lumen and complete obliteration of the dissection in the endovascular group. The neurologic condition of the two paraplegic patients either cleared completely or partially improved. CONCLUSION: In the absence of ischemic paraplegia or other injuries that require emergency surgery, endovascular treatment is a safe and efficient method for treating traumatic infrarenal aortic dissection.