Humanin, a Cytoprotective Peptide, Is Expressed in Carotid Artherosclerotic Plaques in Humans

Objective

The mechanism of atherosclerotic plaque progression leading to instability, rupture, and ischemic manifestation involves oxidative stress and apoptosis. Humanin (HN) is a newly emerging endogenously expressed cytoprotective peptide. Our goal was to determine the presence and localization of HN in carotid atherosclerotic plaques.

Methods and Results

Plaque specimens from 34 patients undergoing carotid endarterectomy were classified according to symptomatic history. Immunostaining combined with digital microscopy revealed greater expression of HN in the unstable plaques of symptomatic compared to asymptomatic patients (29.42±2.05 vs. 14.14±2.13% of plaque area, p<0.0001). These data were further confirmed by immunoblot (density of HN/β-actin standard symptomatic vs. asymptomatic 1.32±0.14 vs. 0.79±0.11, p<0.01). TUNEL staining revealed a higher proportion of apoptotic nuclei in the plaques of symptomatic patients compared to asymptomatic (68.25±3.61 vs. 33.46±4.46% of nuclei, p<0.01). Double immunofluorescence labeling revealed co-localization of HN with macrophages (both M1 and M2 polarization), smooth muscle cells, fibroblasts, and dendritic cells as well as with inflammatory markers MMP2 and MMP9.

Conclusions

The study demonstrates a higher expression of HN in unstable carotid plaques that is localized to multiple cell types within the plaque. These data support the involvement of HN in atherosclerosis, possibly as an endogenous response to the inflammatory and apoptotic processes within the atheromatous plaque.     

Cholesterol lowering and the vessel wall: new insights and future perspectives.

The basis for most acute coronary events is either rupture or fissuring of unstable atherosclerotic plaques with subsequent thrombosis leading to coronary artery occlusion. The development of atherosclerotic plaques takes several decades, but the mechanical features determining its stability and the risk of rupture can change very rapidly depending on a number of internal factors. Unstable plaques have a large lipid core, a thin overlying fibrous cap and an abundance of inflammatory cells. The most important factor determining the plaque stability is the plasma level of atherogenic LDL particles. Increased levels of these particles cause endothelial dysfunction with impaired vasodilatation capacity and prevalence of vasoconstriction, maintain inflammatory infiltration of the plaque, impair the strength of the fibrous cap and facilitate aggregation and coagulation. Effective lowering of plasma cholesterol by pharmacological and non-pharmacological means can revert most of these processes and increase the plaque's mechanical stability within several hours to days. Lipid lowering therapy can therefore decrease the risk of acute coronary events within a very short space of time. Thus a radical decrease in lipid levels, along with modification of other risk factors, may become the cornerstone for treatment of acute coronary syndromes, in addition to being an effective treatment in primary and secondary prevention of coronary heart disease (CHD).     

Identifying Vulnerable Atherosclerotic Plaque in Rabbits Using DMSA-USPIO Enhanced Magnetic Resonance Imaging to Investigate the Effect of Atorvastatin

BackgroundRupture of an atherosclerotic plaque is the primary cause of acute cardiovascular and cerebrovascular syndromes. Early and non-invasive detection of vulnerable atherosclerotic plaques (VP) would be significant in preventing some aspects of these syndromes. As a new contrast agent, dimercaptosuccinic acid (DMSA) modified ultra-small super paramagnetic iron oxide (USPIO) was synthesized and used to identify VP and rupture plaque by magnetic resonance imaging (MRI).MethodsAtherosclerosis was induced in male New Zealand White rabbits by feeding a high cholesterol diet (n = 30). Group A with atherosclerosis plaque (n = 10) were controls. VP was established in groups B (n = 10) and C (n = 10) using balloon-induced endothelial injury of the abdominal aorta. Adenovirus-carrying p53 genes were injected into the aortic segments rich in plaques after 8 weeks. Group C was treated with atorvastatin for 8 weeks. Sixteen weeks later, all rabbits underwent pharmacological triggering, and imaging were taken daily for 5 d after DMSA-USPIO infusion. At the first day and before being killed, serum MMP-9, sCD40L, and other lipid indicators were measured.ResultsDMSA-USPIO particles accumulated in VP and rupture plaques. Rupture plaques appeared as areas of hyper-intensity on DMSA-USPIO enhanced MRI, especially T2*-weighted sequences, with a signal strength peaking at 96 h. The group given atorvastatin showed few DMSA-USPIO particles and had lower levels of serum indicators. MMP-9 and sCD40L levels in group B were significantly higher than in the other 2 groups (P <0.05).ConclusionAfter successfully establishing a VP model in rabbits, DMSA-USPIO was used to enhance MRI for clear identification of plaque inflammation and rupture. Rupture plaques were detectable in this way probably due to an activating inflammatory process. Atorvastatin reduced the inflammatory response and stabilizing VP possibly by decreasing MMP-9 and sCD40L levels.     

Prediction of atherosclerotic plaque ruptures with high-frequency ultrasound imaging and serum inflammatory markers

Atherosclerotic plaque rupture and thrombosis are the main causes of acute coronary syndrome. In the present study, we investigated whether ultrasound imaging and inflammatory parameters are predictive of plaque rupture in a newly established animal model. We developed a rabbit model for plaque rupture by locally delivering recombinant p53 adenovirus to plaques in rabbits fed a high-cholesterol diet for 10 wk, and plaque rupture was triggered using Chinese Russell's viper venom and histamine. We found that 81.1% of rabbits transfected with p53 (n = 37) had the ruptured plaques, which was significantly higher than results in rabbits transfected with the control vector (26.3%, n = 38; P < 0.001). Among measured biomarkers, high-sensitive C-reactive protein, soluble intercellular adhesion molecule-1, and soluble vascular cell adhesion molecule-1 were significantly different between rabbits with and without ruptured plaques. Using high-frequency duplex and intravascular ultrasound imaging techniques, we obtained a list of parameters. With the multivariate logistic regression model, we identified that plaque eccentric index, plaque area, high-sensitive C-reactive protein, and corrected integrated backscatter intensity were significant predictors of plaque rupture, with odds ratios of 7.056 [95% confidence interval (CI): 1.958, approximately 25.430], 1.942 (95% CI: 1.058, approximately 3.564), 1.025 (95% CI: 1.007, approximately 1.043), and 0.856 (95% CI: 0.775, approximately 0.946), respectively. Localized p53 overexpression technique induces plaque rupture, and the combined measurement of ultrasound and biochemical markers is a valuable tool in predicting plaque rupture.     

Calculation of arterial wall temperature in atherosclerotic arteries: effect of pulsatile flow,arterial geometry,and plaque structure

Background  

This paper presents calculations of the temperature distribution in an atherosclerotic plaque experiencing an inflammatory process; it analyzes the presence of hot spots in the plaque region and their relationship to blood flow, arterial geometry, and inflammatory cell distribution. Determination of the plaque temperature has become an important topic because plaques showing a temperature inhomogeneity have a higher likelihood of rupture. As a result, monitoring plaque temperature and knowing the factors affecting it can help in the prevention of sudden rupture.     

糖化清蛋白、高敏C反应蛋白与冠心病临界病变患者冠脉斑块形态学特征的关系及对功能性心肌缺血的预测研究

摘要 目的：分析糖化清蛋白、高敏C反应蛋白与冠心病临界病变患者冠脉斑块形态学特征的关系及对功能性心肌缺血的预测价值。方法：选择自2020年1月至2022年6月我院经冠脉造影确诊的165例冠心病临界病变患者作为研究对象,分为不稳定型心绞痛组和稳定型心绞痛组。检测两组血清糖化清蛋白、高敏C反应蛋白表达水平,使用靶血管造影检测冠脉斑块形态学指标,Pearson相关性分析血清糖化清蛋白、高敏C反应蛋白与冠脉斑块形态学指标的关系,通过ROC曲线下面积（AUC）评价血清糖化清蛋白联合高敏C反应蛋白对功能性心肌缺血的预测价值。结果：不稳定型心绞痛组血清糖化清蛋白、高敏C反应蛋白表达水平均高于稳定型心绞痛组（P＜0.05）;不稳定型心绞痛组最小管腔直径、最小管腔面积均小于稳定型心绞痛组,直径狭窄率、管腔面积狭窄率、斑块面积均大于稳定型心绞痛组（P＜0.05）;在165例冠心病临界病变患者中,发生冠脉易损斑块53例;易损斑块组血清糖化清蛋白、高敏C反应蛋白表达水平均高于非易损斑块组（P＜0.05）;经Pearson相关性分析,冠心病临界病变患者血清糖化清蛋白、高敏C反应蛋白表达水平均与最小管腔直径、最小管腔面积呈负相关,与直径狭窄率、管腔面积狭窄率、斑块面积呈正相关（P＜0.05）;经ROC曲线分析,血清糖化清蛋白联合高敏C反应蛋白预测冠心病临界病变患者发生功能性心肌缺血的AUC为0.910。结论：糖化清蛋白、高敏C反应蛋白与冠心病临界病变患者冠脉斑块形态学特征密切相关,有助于评估冠脉斑块易损性,联合预测功能性心肌缺血的效能较好,值得临床予以重视应用。     

Plaque Image Characteristics, Hyperhomocysteinemia, and Gene Polymorphism of Homocysteine Metabolism-Related Enzyme (MTHFR C677T) in Acute Coronary Syndrome

This study aims to investigate the correlation between the different characteristics of plaques, plasma level of homocysteine (Hcy), and gene polymorphism of Hcy metabolism-related enzyme. In this consecutive case–control study, we measured the plasma Hcy level using fluorescence biochemistry method and examined the gene polymorphism of Hcy metabolism-related enzyme methylenetetrahydrofolate reductase (MTHFR) C677T using TaqMan probe technology. We also examined these using intravascular ultrasound. We studied the characteristics of the plaque, measured the cross-sectional areas of the external elastic membrane and the lumen, calculated the plaque area, plaque burden, and eccentricity index, and examined the remodeling index. Hard plaques were more dominant in the (SPA) group, whereas soft plaques were more dominant in the acute coronary syndrome (ACS) group (P < 0.001). The risk of plaque rupture and thrombus is higher in the ACS group (P < 0.05). Compared with SPA group, plaque burden was heavier in the ACS group (P < 0.05), but the eccentricity index is significantly higher in SPA group than in the ACS group (P < 0.001). Positive remodeling was more frequent in ACS group, whereas negative remodeling was more frequent in the SPA group (P < 0.001). Plasma Hcy levels were higher in the unstable than in the stable plaque group (P < 0.001). The constituent ratio of MTHFR C677T genotype were different in stable plaque group and vulnerable plaque group (P < 0.05). The T genotype can increase the incidence rate of vulnerable plaque. Hcy and MTHFR C677T gene polymorphism were found to be risk factors for vulnerable plaque. Therefore, these can be used as indices to predict the instability of atherosclerotic plaque.     

Relation between TLR4/NF‐κB signaling pathway activation by 27‐hydroxycholesterol and 4‐hydroxynonenal,and atherosclerotic plaque instability

It is now thought that atherosclerosis, although due to increased plasma lipids, is mainly the consequence of a complicated inflammatory process, with immune responses at the different stages of plaque development. Increasing evidence points to a significant role of Toll‐like receptor 4 (TLR4), a key player in innate immunity, in the pathogenesis of atherosclerosis. This study aimed to determine the effects on TLR4 activation of two reactive oxidized lipids carried by oxidized low‐density lipoproteins, the oxysterol 27‐hydroxycholesterol (27‐OH) and the aldehyde 4‐hydroxynonenal (HNE), both of which accumulate in atherosclerotic plaques and play a key role in the pathogenesis of atherosclerosis. Secondarily, it examined their potential involvement in mediating inflammation and extracellular matrix degradation, the hallmarks of high‐risk atherosclerotic unstable plaques. In human promonocytic U937 cells, both 27‐OH and HNE were found to enhance cell release of IL‐8, IL‐1β, and TNF‐α and to upregulate matrix metalloproteinase‐9 (MMP‐9) via TLR4/NF‐κB‐dependent pathway; these actions may sustain the inflammatory response and matrix degradation that lead to atherosclerotic plaque instability and to their rupture. Using specific antibodies, it was also demonstrated that these inflammatory cytokines increase MMP‐9 upregulation, thus enhancing the release of this matrix‐degrading enzyme by macrophage cells and contributing to plaque instability. These innovative results suggest that, by accumulating in atherosclerotic plaques, the two oxidized lipids may contribute to plaque instability and rupture. They appear to do so by sustaining the release of inflammatory molecules and MMP‐9 by inflammatory and immune cells, for example, macrophages, through activation of TLR4 and its NF‐κB downstream signaling.     

Atherosclerosis-underlying inflammatory mechanisms and clinical implications

Inflammation plays an important role in the initiation and progression of atherosclerosis but many of its underlying mechanisms remain to be explored. Atherosclerotic plaques which are more prone to destabilisation and rupture, leading to clinical events, are characterised by increased infiltration of leukocytes and other inflammatory mediators, compared with stable fibrotic plaques. T cell mediated responses, through expression of cytokines and chemokines, play an important role in the inflammatory process; and more recently potentially anti-inflammatory markers have also been identified. Current management involves both mechanical restoration of blood flow and pharmacotherapy aimed in part at suppressing the underlying inflammatory mechanisms. The aims of this review are to outline the pro- and anti-inflammatory processes in atherosclerosis, as well as their clinical implications.     

Genetic deletion or TWEAK blocking antibody administration reduce atherosclerosis and enhance plaque stability in mice

Clinical complications associated with atherosclerotic plaques arise from luminal obstruction due to plaque growth or destabilization leading to rupture. Tumour necrosis factor ligand superfamily member 12 (TNFSF12) also known as TNF-related weak inducer of apoptosis (TWEAK) is a proinflammatory cytokine that participates in atherosclerotic plaque development, but its role in plaque stability remains unclear. Using two different approaches, genetic deletion of TNFSF12 and treatment with a TWEAK blocking mAb in atherosclerosis-prone mice, we have analysed the effect of TWEAK inhibition on atherosclerotic plaques progression and stability. Mice lacking both TNFSF12 and Apolipoprotein E (TNFSF12^−/−ApoE^−/−) exhibited a diminished atherosclerotic burden and lesion size in their aorta. Advanced atherosclerotic plaques of TNFSF12^−/−ApoE^−/− or anti-TWEAK treated mice exhibited an increase collagen/lipid and vascular smooth muscle cell/macrophage ratios compared with TNFSF12^+/+ApoE^−/− control mice, reflecting a more stable plaque phenotype. These changes are related with two different mechanisms, reduction of the inflammatory response (chemokines expression and secretion and nuclear factor kappa B activation) and decrease of metalloproteinase activity in atherosclerotic plaques of TNFSF12^−/−ApoE^−/−. A similar phenotype was observed with anti-TWEAK mAb treatment in TNFSF12^+/+ApoE^−/− mice. Brachiocephalic arteries were also examined since they exhibit additional features akin to human atherosclerotic plaques associated with instability and rupture. Features of greater plaque stability including augmented collagen/lipid ratio, reduced macrophage content, and less presence of lateral xanthomas, buried caps, medial erosion, intraplaque haemorrhage and calcium content were present in TNFSF12^−/−ApoE^−/− or anti-TWEAK treatment in TNFSF12^+/+ApoE^−/− mice. Overall, our data indicate that anti-TWEAK treatment has the capacity to diminish proinflamatory response associated with atherosclerotic plaque progression and to alter plaque morphology towards a stable phenotype.     

Oxysterols and symptomatic versus asymptomatic human atherosclerotic plaque

Atherosclerosis is the most common cause of mortality in the Western world, contributing to about 50% of all deaths. Atherosclerosis is characterized by deposition of lipids onto the coronary or carotid arterial wall and formation of an atherosclerotic plaque. Atherosclerotic plaques are categorized into two groups: symptomatic and asymptomatic. The symptomatic plaques tend to be unstable and prone to rupture, and are associated with an increase in ischemic events. Oxysterols, products of cholesterol oxidation, are cytotoxic materials. Their level and type may be associated with plaque formation, development and stability. Oxysterols stimulate the formation of foam cells, advance atherosclerotic plaque progression, and contribute to plaque vulnerability and instability due to their cytotoxicity and their ability to induce cell apoptosis. Studies indicate that plasma 7β-OH CH level can be used as a biomarker for detecting carotid and coronary artery disease. Further clinical studies are needed to evaluate the potential of oxysterols for use as biomarkers for plaque vulnerability and instability. The identification of biomarkers in the blood that can distinguish between symptomatic and asymptomatic plaques remains an unresolved issue.     

Phenotype commitment in vascular smooth muscle cells derived from coronary atherosclerotic plaques: differential gene expression of endothelial nitric oxide synthase

Unstable angina and myocardial infarction are the clinical manifestations of the abrupt thrombotic occlusion of an epicardial coronary artery as a result of spontaneous atherosclerotic plaque rupture or fissuring, and the exposure of highly thrombogenic material to blood. It has been demonstrated that the proliferation of vascular smooth muscle cells (VSMCs) and impaired bioavailabilty of nitric oxide (NO) are among the most important mechanisms involved in the progression of atherosclerosis. It has also been suggested that a NO imbalance in coronary arteries may be involved in myocardial ischemia as a result of vasomotor dysfunction triggering plaque rupture and the thrombotic response. We used 5' nuclease assays (TaqMan PCRs) to study gene expression in coronary plaques collected by means of therapeutic directional coronary atherectomy from 15 patients with stable angina (SA) and 15 with acute coronary syndromes (ACS) without ST elevation. Total RNA was extracted from the 30 plaques and the cDNA was amplified in order to determine endothelial nitric oxide synthase (eNOS) gene expression. Analysis of the results showed that the expression of eNOS was significantly higher (p<0.001) in the plaques from the ACS patients. Furthermore, isolated VSMCs from ACS and SA plaques confirmed the above pattern even after 25 plating passages. In situ RT-PCR was also carried out to co-localize the eNOS messengers and the VSMC phenotype. The eNOS gene was more expressed in ACS plaques and VSMCs cultured from them, thus indicating that: a) the expression of the most important differentiation markers is retained under in vitro conditions; and b) NO may play a pivotal role in coronary artery disease. Our findings suggest a new cell system model for studying the pathophysiology of unstable angina and myocardial infarction.     

Inflammation in human carotid atheroma plaques

Inflammation in carotid atherosclerotic plaque is linked to plaque rupture and cerebrovascular accidents. The balance between pro- and anti-inflammatory mediators governs development of the plaque, and may mediate enhancement of lesion broadening or, on the contrary, delay progression. In addition to macrophages and endothelial cells, smooth muscle cells (SMCs), which are the dominant cell subset in advanced plaques, are crucial players in carotid atherosclerosis development given their ability to differentiate into distinct phenotypes in reponse to specific signals received from the environment of the lesion. Carotid atheroma SMCs actively contribute to the inflammation in the lesion because of their acquired capacity to produce inflammatory mediators. We review the successive stages of carotid atheroma plaque formation via fatty streak early-stage toward more advanced rupture-prone lesions and document involvement of cytokines and chemokines and their cellular sources and targets in plaque progression and rupture.     

Flow cytometry analysis of atherosclerotic plaque cells from human carotids: a validation study

BACKGROUND: Atherosclerotic plaques are heterogeneous vascular lesions. Changes in cell plaque composition are fundamental events inside the plaque microenvironment that are strictly related to the clinical outcome of these lesions (organ damage). The knowledge of these modifications may help to better understand the pathophysiological mechanisms of atherosclerosis. METHODS: We report on a flow cytometry method to characterize and quantify the cell subpopulations in human atherosclerotic plaques. Cells were obtained from endarterectomy specimens after collagenase digestion. Both surface and intracytoplasmic antigens were labeled. RESULTS: Our data demonstrated that the method we described allowed the characterization of cell populations that compose the atherosclerotic plaque, avoiding contamination by tunica media smooth muscle cells and the noise of cellular debris. Moreover this validation study showed that about 50% of cells in the atherosclerotic plaques are inflammatory mononuclear cells (T lymphocytes and monocytes/macrophages). CONCLUSIONS: Reproducible quantitative methods for cell population characterization may increase the understanding of pathophysiological mechanisms responsible for plaque progression. The methodology herein described gave us the possibility of quickly calculating the relative amount of each cell population and studying both surface and intracellular markers to analyze the functional stage of the cells. The clinical correlation was not assessed in the present study, because we used a small patient group to validate the method, but should be the subject of further analyses in a larger patient population.     

Compressive mechanical properties of atherosclerotic plaques—Indentation test to characterise the local anisotropic behaviour

Accurate material models and associated parameters of atherosclerotic plaques are crucial for reliable biomechanical plaque prediction models. These biomechanical models have the potential to increase our understanding of plaque progression and failure, possibly improving risk assessment of plaque rupture, which is the main cause of ischaemic strokes and myocardial infarction. However, experimental biomechanical data on atherosclerotic plaque tissue is scarce and shows a high variability. In addition, most of the biomechanical models assume isotropic behaviour of plaque tissue, which is a general over-simplification. This review discusses the past and the current literature that focus on mechanical properties of plaque derived from compression experiments, using unconfined compression, micro-indentation or nano-indentation. Results will be discussed and the techniques will be mutually compared. Thereafter, an in-house developed indentation method combined with an inverse finite element method is introduced, allowing analysis of the local anisotropic mechanical properties of atherosclerotic plaques. The advantages and limitations of this method will be evaluated and compared to other methods reported in literature.     

Mast cells in vulnerable coronary plaques: potential mechanisms linking mast cell activation to plaque erosion and rupture

PURPOSE OF REVIEW: A novel link between inflammation and acute coronary syndromes is emerging, in that infiltrating inflammatory cells may convert a clinically silent coronary plaque into a dangerous and potentially lethal plaque. The majority of acute atherothrombotic events now relate to erosion or rupture of such unstable plaques. Here we summarize the molecular mechanisms by which activated mast cells may contribute to plaque erosion or rupture. RECENT FINDINGS: In-vitro experiments have revealed a multitude of paracrine effects exerted by activated mast cells. By secreting heparin proteoglycans and chymase, activated mast cells efficiently inhibit the proliferation of smooth muscle cells in vitro, and reduce their ability to produce collagen by a transforming growth factor beta-dependent and -independent mechanism. Mast cell chymase and tryptase are capable of activating matrix metalloproteinases types 1 and 3, causing degradation of the extracellular matrix component, collagen, necessary for the stability of the plaque. Activated mast cells also secrete matrix metalloproteinases types 1 and 9 themselves. Furthermore, chymase induces SMC apoptosis by degrading fibronectin, a pericellular matrix component necessary for SMC adhesion and survival, with the subsequent disruption of focal adhesions and loss of outside-in survival signaling. By secreting chymase and tumour necrosis factor alpha, activated mast cells also induce endothelial cell apoptosis. SUMMARY: Locally activated mast cells may participate in the weakening of atherosclerotic plaques by secreting heparin proteoglycans, chymase, and cytokines, which affect the growth, function and death of arterial endothelial cells and smooth muscle cells, thereby predisposing to plaque erosion or rupture.     

Pathophysiology and biochemistry of cardiovascular disease

Atherosclerosis is the major cause of cardiovascular disease. Hypercholesterolaemia, hypertension and cigarette smoking are the common risk factors for atherosclerosis. These risk factors unite behind a convergence of mechanism, involving oxidation and inflammation in the artery wall that, with time, gives rise to characteristic fatty-fibrous lesions. Physical trauma and inflammation produce lesion rupture, which can lead to clinical events such as heart attack and stroke, or resolve with plaque growth. Disease progression is marked by the inflammatory indicator CRP (C-reactive protein). Early indicators of heart attack are the inflammatory marker CD40, and the cardiac myofilament protein troponin. Coronary atherosclerosis is the common cause of heart failure (HF). Disordered calcium signalling to the myofilaments occurs in HF and in cardiomyopathy. Enhanced calcium signalling suppresses HF. Neuro-humoral and biomechanical processes, as seen in hypertension, produce cardiac hypertrophy, which predisposes to HF through apoptosis. Although in humans cardiac damage produces permanent loss of cells, because the heart cannot regenerate, developments in stem cell technology suggest that help is at hand.     

Expanding expression of the 5-lipoxygenase/leukotriene B4 pathway in atherosclerotic lesions of diabetic patients promotes plaque instability

Emerging evidence now indicates that the 5-lipoxygenase (5-LO) pathway play a role in the pathogenesis of atherosclerosis and restenosis. The expression of 5-LO by activated macrophages in symptomatic plaques leads to leukotriene B(4) (LTB(4)) accumulation and enhanced synthesis and release of matrix metalloproteinases (MMPs) that can promote plaque rupture. However, the role of 5-LO pathway in diabetic vascular disease has not been previously reported. Thus, the present study was designed to analyze the expression of 5-LO in carotid plaques of diabetic patients and to investigate the possible role of 5-LO pathway in the pathogenesis and progression of diabetic atherosclerosis. Atherosclerotic plaques from 60 patients undergoing carotid endarterectomy were divided into non-diabetic and diabetic group. Plaques were analyzed for 5-LO, MMP-2 and MMP-9 by immunohistochemical, Western blot, and densitometric analyses, whereas zymography was used to detect MMP activity. Immunocytochemistry was also used to identify CD68+macrophages, CD3+T-lymphocytes, and HLA-DR+inflammatory cells. LTB(4) were quantified by enzyme-linked immunosorbent assay. 5-LO showed abundant immunoreactivity in human atherosclerotic carotid lesions, and was colocalized with macrophage infiltrates in atherosclerotic intima. 5-LO expression was higher in diabetic compared with non-diabetic plaques and was associated with increased MMP-2 and MMP-9 expression. Follow-up analyze with zymography assay revealed MMP activity was elevated in diabetic compared with non-diabetic plaques. Notably, in contrast to non-diabetic plaques, LTB(4) levels were significantly increased in diabetic plaques by enzyme-linked immunosorbent assay. These results suggest that overexpression of 5-LO and LTB(4) in atherosclerotic plaques possibly promote MMP-induced plaque rupture in diabetes. Hence, anti-LTs may be useful, not only in reducing atherogenesis, but also in the prevention and treatment of acute atherothrombotic events in diabetic patients.     

Inflammatory markers: linking unstable plaques to coronary event, an interventional perspective

Abundant data links inflammatory mechanisms to atheromatous plaque destabilization leading to plaque rupture and coronary events. The discovery of inflammatory cells and inflammatory mediators within atherosclerotic plaques prone to rupture led to a series of studies demonstrating an association between various markers of inflammation and future coronary events. Inflammatory markers have also been used in patients undergoing coronary angioplasty in an attempt to predict restenosis and risk for post-procedural coronary events. This review article provides an overview on the potential use of inflammatory markers in the context of coronary interventions.