Lipid accumulation is a key characteristic of advancing atherosclerotic lesions. Herein, we analyzed the ultrastructure of the accumulated lipids in endarterectomized human carotid atherosclerotic plaques using three-dimensional (3D) electron microscopy, a method never used in this context before. 3D electron microscopy revealed intracellular lipid droplets and extracellular lipoprotein particles. Most of the particles were aggregated, and some connected to needle-shaped or sheet-like cholesterol crystals. Proteomic analysis of isolated extracellular lipoprotein particles revealed that apolipoprotein B is their main protein component, indicating their origin from low-density lipoprotein, intermediate-density lipoprotein, very-low-density lipoprotein, lipoprotein (a), or chylomicron remnants. The particles also contained small exchangeable apolipoproteins, complement components, and immunoglobulins. Lipidomic analysis revealed differences between plasma lipoproteins and the particles, thereby indicating involvement of lipolytic enzymes in their generation. Incubation of human monocyte-derived macrophages with the isolated extracellular lipoprotein particles or with plasma lipoproteins that had been lipolytically modified in vitro induced intracellular lipid accumulation and triggered inflammasome activation in them. Taken together, extracellular lipids accumulate in human carotid plaques as distinct 3D structures that include aggregated and fused lipoprotein particles and cholesterol crystals. The particles originate from plasma lipoproteins, show signs of lipolytic modifications, and associate with cholesterol crystals. By inducing intracellular cholesterol accumulation (ie, foam cell formation) and inflammasome activation, the extracellular lipoprotein particles may actively enhance atherogenesis.

Objective-Activated mast cells (MCs) induce endothelial cell (EC) apoptosis in vitro and are present at sites of plaque erosions in vivo. To further elucidate the role of MCs in endothelial apoptosis and consequently in plaque erosion, we have studied the molecular mechanisms involved in MC-induced EC apoptosis. Methods and Results-Primary cultures of rat cardiac microvascular ECs (RCMECs) and human coronary artery ECs (HCAECs) were treated either with rat MC releasate (ie, mediators released on MC activation), rat chymase and tumor necrosis factor-␣ (TNF-␣), or with human chymase and TNF-␣, respectively. MC releasate induced RCMEC apoptosis by inactivating the focal adhesion kinase (FAK) and Akt-dependent survival signaling pathway, and apoptosis was partially inhibited by chymase and TNF-␣ inhibitors. Chymase avidly degraded both vitronectin (VN) and fibronectin (FN) produced by the cultured RCMECs. In addition, MC releasate inhibited the activation of NF-B (p65) and activated caspase-8 and -9. Moreover, in HCAECs, human chymase and TNF-␣ induced additive levels of apoptosis. Key Words: atherosclerosis Ⅲ mast cell Ⅲ apoptosis Ⅲ chymase Ⅲ plaque erosion T he most important pathological processes underlying the sudden onset of acute coronary syndromes, including unstable angina and acute myocardial infarction, are focal erosions and ruptures of a vulnerable coronary plaque. 1 Although erosions of coronary plaques account for as much as 30% of the fatal acute myocardial infarctions and sudden coronary deaths, 2 the molecular mechanisms of plaque erosion have remained enigmatic. One possible cause of plaque erosion is apoptosis of the involved endothelial cells (ECs). 3 Indeed, patients with unstable angina or myocardial infarction have increased levels of circulating EC-derived apoptotic microparticles, 4 and patients with symptomatic internal carotid artery plaques have increased numbers of apoptotic ECs. 5 EC apoptosis is especially seen in downstream areas of atherosclerotic plaques subjected to aberrant hemodynamic forces including turbulent blood flow. 6 The vulnerable sites of atherosclerotic plaques also contain an increased number of mast cells (MCs) that show signs of activation by degranulation, which is a prerequisite for the release of preformed mediators, both insoluble and soluble. 7,8 We have previously shown that activated rat serosal MCs induce apoptosis of rat cardiac microvascular ECs (RCMECs) in vitro, by a mechanism that involves the presence of both insoluble tumor necrosis factor-␣ (TNF-␣) in the granule-remnant fraction and soluble TNF-␣ in the granule-remnant free supernatant. 9 However, TNF-␣ alone could not explain the observed effects, 9 suggesting that other components of the MC releasate may have been involved. Chymase, the neutral serine protease of MCs, has been shown to induce apoptosis of smooth muscle cells (SMCs), 10 myocytes, 11 and epithelial cells. 12 Recently, we have shown that the MC-derived proteases, chymase and tryptase, when incubated with arterial segments in...

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This article discusses how decision-makers can be supported to strengthen a culture of prevention. This article presents an example of the United Nations Office on Drugs and Crime’s (UNODC) work to engage with decision-makers to create readiness, demand, and capacity for evidence-based prevention programming among them, particularly in low- and middle-income countries. First, we utilized two of the UNODC’s data sources to describe the context where the UNODC’s prevention efforts take place. Analysis of the first dataset on prevention activities implemented globally revealed a gap in translating evidence into practice on a global scale. The second dataset consisted of UNODC policy documents mandating and guiding global action to address substance use. The analysis showed that at the level of political frameworks, prevention is gradually gaining more attention but is still frequently left in the shadow of health- and law enforcement-related issues. In addition, these guiding documents did not reflect fully the current scientific understanding of what constitutes an effective prevention response. Against this background, the feasibility of the UNODC’s efforts to bridge the science–practice gap in the field of prevention was discussed by presenting the results from the UNODC’s regional capacity-building seminars focused on the role of monitoring and evaluation in prevention programming. The results showed potential of this capacity building to affect the attitudes and knowledge of targeted decision-makers. Such efforts to increase decision-makers’ readiness and ultimately their endorsement, adoption, and ongoing support of evidence-based preventive interventions should be continued and intensified.

Activated subendothelial mast cells may contribute to endothelial erosion by releasing proteases capable of degrading VE-cadherin and fibronectin.