Atorvastatin attenuates remnant lipoprotein-induced monocyte adhesion to vascular endothelium under flow conditions

Association between multiple inflammatory biomarkers and remnant cholesterol levels in patients with percutaneous coronary intervention: A large-scale real-world study

BACKGROUND AND AIM

Remnant cholesterol (RC) has garnered increasing attention recently due to its association with adverse cardiovascular events. However, the relationship between RC levels and inflammation remains unclear. The goal of this study was to investigate and compare the predictive value of multiple inflammatory biomarkers for high RC in patients with percutaneous coronary intervention (PCI).

METHODS AND RESULTS

Initially, a total of 10,724 consecutive individuals hospitalized for PCI at Fu Wai Hospital in 2013 were enrolled. Finally, 9983 patients receiving dual antiplatelet therapy and drug-eluting stent were selected for analysis. The inflammatory biomarkers included high-sensitivity C-reactive protein (hs-CRP), hs-CRP-to-albumin ratio (CAR), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), lymphocyte-to-monocyte ratio (LMR), lymphocyte-to-hs-CRP ratio (LCR), and systemic immune-inflammation index (SII). Patients were divided into higher RC and lower RC groups based on the median RC level. Multivariate logistic regression showed that hs-CRP (OR per SD: 1.254), CAR (OR per SD: 1.245), PLR (OR per SD: 1.139), and SII (OR per SD: 1.077) were associated with high RC (≥median), while LCR (OR per SD: 0.792) was associated with low RC (

CONCLUSIONS

In PCI patients, hs-CRP, CAR, PLR, LCR, and SII were independently associated with RC levels. Among these inflammatory biomarkers, hs-CRP conferred better prediction for high RC. This investigation further supports the close relationship between inflammation and residual lipid risk biomarker RC.

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Key Words

• Inflammation
• Percutaneous coronary intervention
• Remnant cholesterol
• hs-CRP

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MESH Headings

• Humans
• C-Reactive Protein/analysis
• Percutaneous Coronary Intervention/adverse effects
• Drug-Eluting Stents
• Biomarkers
• Inflammation/diagnosis
• Inflammation/etiology

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Affiliation(s)

Jiawen Li Department of Cardiology, National Clinical Research Center for Cardiovascular Diseases, State Key Laboratory of Cardiovascular Disease, Fu Wai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 Beilishi Road, Xicheng District, Beijing 100037, China
Kailun Yan Department of Cardiology, National Clinical Research Center for Cardiovascular Diseases, State Key Laboratory of Cardiovascular Disease, Fu Wai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 Beilishi Road, Xicheng District, Beijing 100037, China
Pei Zhu Department of Cardiology, National Clinical Research Center for Cardiovascular Diseases, State Key Laboratory of Cardiovascular Disease, Fu Wai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 Beilishi Road, Xicheng District, Beijing 100037, China
Jingjing Xu Department of Cardiology, National Clinical Research Center for Cardiovascular Diseases, State Key Laboratory of Cardiovascular Disease, Fu Wai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 Beilishi Road, Xicheng District, Beijing 100037, China
Xiaofang Tang Department of Cardiology, National Clinical Research Center for Cardiovascular Diseases, State Key Laboratory of Cardiovascular Disease, Fu Wai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 Beilishi Road, Xicheng District, Beijing 100037, China
Yulong Li Department of Cardiology, National Clinical Research Center for Cardiovascular Diseases, State Key Laboratory of Cardiovascular Disease, Fu Wai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 Beilishi Road, Xicheng District, Beijing 100037, China
Weixian Yang Department of Cardiology, National Clinical Research Center for Cardiovascular Diseases, State Key Laboratory of Cardiovascular Disease, Fu Wai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 Beilishi Road, Xicheng District, Beijing 100037, China
Shubin Qiao Department of Cardiology, National Clinical Research Center for Cardiovascular Diseases, State Key Laboratory of Cardiovascular Disease, Fu Wai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 Beilishi Road, Xicheng District, Beijing 100037, China
Yuejin Yang Department of Cardiology, National Clinical Research Center for Cardiovascular Diseases, State Key Laboratory of Cardiovascular Disease, Fu Wai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 Beilishi Road, Xicheng District, Beijing 100037, China
Runlin Gao Department of Cardiology, National Clinical Research Center for Cardiovascular Diseases, State Key Laboratory of Cardiovascular Disease, Fu Wai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 Beilishi Road, Xicheng District, Beijing 100037, China
Jinqing Yuan Department of Cardiology, National Clinical Research Center for Cardiovascular Diseases, State Key Laboratory of Cardiovascular Disease, Fu Wai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 Beilishi Road, Xicheng District, Beijing 100037, China.
Xueyan Zhao Department of Cardiology, National Clinical Research Center for Cardiovascular Diseases, State Key Laboratory of Cardiovascular Disease, Fu Wai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 167 Beilishi Road, Xicheng District, Beijing 100037, China.

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Monocytic Cell Adhesion to Oxidised Ligands: Relevance to Cardiovascular Disease

Atherosclerosis, the major cause of vascular disease, is an inflammatory process driven by entry of blood monocytes into the arterial wall. LDL normally enters the wall, and stimulates monocyte adhesion by forming oxidation products such as oxidised phospholipids (oxPLs) and malondialdehyde. Adhesion molecules that bind monocytes to the wall permit traffic of these cells. CD14 is a monocyte surface receptor, a cofactor with TLR4 forming a complex that binds oxidised phospholipids and induces inflammatory changes in the cells, but data have been limited for monocyte adhesion. Here, we show that under static conditions, CD14 and TLR4 are implicated in adhesion of monocytes to solid phase oxidised LDL (oxLDL), and also that oxPL and malondialdehyde (MDA) adducts are involved in adhesion to oxLDL. Similarly, monocytes bound to heat shock protein 60 (HSP60), but this could be through contaminating lipopolysaccharide. Immunohistochemistry on atherosclerotic human arteries demonstrated increased endothelial MDA adducts and HSP60, but endothelial oxPL was not detected. We propose that monocytes could bind to MDA in endothelial cells, inducing atherosclerosis. Monocytes and platelets synergized in binding to oxLDL, forming aggregates; if this occurs at the arterial surface, they could precipitate thrombosis. These interactions could be targeted by cyclodextrins and oxidised phospholipid analogues for therapy.

Triglyceride and Triglyceride-Rich Lipoproteins in Atherosclerosis

Cardiovascular disease (CVD) is still the leading cause of death globally, and atherosclerosis is the main pathological basis of CVDs. Low-density lipoprotein cholesterol (LDL-C) is a strong causal factor of atherosclerosis. However, the first-line lipid-lowering drugs, statins, only reduce approximately 30% of the CVD risk. Of note, atherosclerotic CVD (ASCVD) cannot be eliminated in a great number of patients even their LDL-C levels meet the recommended clinical goals. Previously, whether the elevated plasma level of triglyceride is causally associated with ASCVD has been controversial. Recent genetic and epidemiological studies have demonstrated that triglyceride and triglyceride-rich lipoprotein (TGRL) are the main causal risk factors of the residual ASCVD. TGRLs and their metabolites can promote atherosclerosis via modulating inflammation, oxidative stress, and formation of foam cells. In this article, we will make a short review of TG and TGRL metabolism, display evidence of association between TG and ASCVD, summarize the atherogenic factors of TGRLs and their metabolites, and discuss the current findings and advances in TG-lowering therapies. This review provides information useful for the researchers in the field of CVD as well as for pharmacologists and clinicians.

Hypertriglyceridemia: A Neglected Risk Factor for Ischemic Stroke?

Hypertriglyceridemia is caused by defects in triglyceride metabolism and generally manifests as abnormally high plasma triglyceride levels. Although the role of hypertriglyceridemia may not draw as much attention as that of plasma cholesterol in stroke, plasma triglycerides, especially nonfasting triglycerides, are thought to be correlated with the risk of ischemic stroke. Hypertriglyceridemia may increase the risk of ischemic stroke by promoting atherosclerosis and thrombosis and increasing blood viscosity. Moreover, hypertriglyceridemia may have some protective effects in patients who have already suffered a stroke via unclear mechanisms. Therefore, further studies are needed to elucidate the role of hypertriglyceridemia in the development and prognosis of ischemic stroke.

Atorvastatin and blood flow regulate expression of distinctive sets of genes in mouse carotid artery endothelium

Hypercholesterolemia is a well-known pro-atherogenic risk factor and statin is the most effective anti-atherogenic drug that lowers blood cholesterol levels. However, despite systemic hypercholesterolemia, atherosclerosis preferentially occurs in arterial regions exposed to disturbed blood flow (d-flow), while the stable flow (s-flow) regions are spared. Given their predominant effects on endothelial function and atherosclerosis, we tested whether (1) statin and flow regulate the same or independent sets of genes and (2) statin can rescue d-flow-regulated genes in mouse artery endothelial cells in vivo. To test the hypotheses, C57BL/6 J mice (8-week-old male, n=5 per group) were pre-treated with atorvastatin (10mg/kg/day, Orally) or vehicle for 5 days. Thereafter, partial carotid ligation (PCL) surgery to induce d-flow in the left carotid artery (LCA) was performed, and statin or vehicle treatment was continued. The contralateral right carotid artery (RCA) remained exposed to s-flow to be used as the control. Two days or 2 weeks post-PCL surgery, endothelial-enriched RNAs from the LCAs and RCAs were collected and subjected to microarray gene expression analysis. Statin treatment in the s-flow condition (RCA+statin versus RCA+vehicle) altered the expression of 667 genes at 2-day and 187 genes at 2-week timepoint, respectively (P<0.05, fold change (FC)≥±1.5). Interestingly, statin treatment in the d-flow condition (LCA+statin versus LCA+vehicle) affected a limited number of genes: 113 and 75 differentially expressed genes at 2-day and 2-week timepoint, respectively (P<0.05, FC≥±1.5). In contrast, d-flow in the vehicle groups (LCA+vehicle versus RCA+vehicle) differentially regulated 4061 genes at 2-day and 3169 genes at 2-week timepoint, respectively (P<0.05, FC≥±1.5). Moreover, statin treatment did not reduce the number of flow-sensitive genes (LCA+statin versus RCA+statin) compared to the vehicle groups: 1825 genes at 2-day and 3788 genes at 2-week, respectively, were differentially regulated (P<0.05, FC≥±1.5). These results revealed that both statin and d-flow regulate expression of hundreds or thousands of arterial endothelial genes, respectively, in vivo. Further, statin and d-flow regulate independent sets of endothelial genes. Importantly, statin treatment did not reverse d-flow-regulated genes except for a small number of genes. These results suggest that both statin and flow play important independent roles in atherosclerosis development and highlight the need to consider their therapeutic implications for both.

Postprandial dyslipidemia in insulin resistant states in adolescent populations

Obesity and the metabolic syndrome are becoming increasingly prevalent not only in adults, but also in adolescents. The metabolic syndrome, a complex cluster of metabolic abnormalities, increases one's risk of developing type 2 diabetes and cardiovascular disease (CVD). Dyslipidemia, a key component of the metabolic syndrome, is highly associated with insulin resistance and contributes to increased CVD risk. Dyslipidemia has traditionally been assessed using a fasting lipid profile [i.e. fasting triglycerides, total cholesterol, low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C)]. However, the postprandial state predominates over the course of a day and non-fasting triglycerides independently predict CVD risk. In insulin resistant states, the intestine overproduces triglyceride-rich lipoprotein (TRL) particles, termed chylomicrons (CMs), following ingestion of a fat-containing meal, as well as in the fasting state. Along with elevated hepatic TRLs (i.e. very-low density lipoproteins), CMs contribute to remnant lipoprotein accumulation, small dense LDL particles, and reduced HDL-C, which collectively increase CVD risk. Given the early genesis of atherosclerosis and physiological metabolic changes during adolescence, studying postprandial dyslipidemia in the adolescent population is an important area of study. Postprandial dyslipidemia in the pediatric population poses a significant public health concern, warranting a better understanding of its pathogenesis and association with insulin resistance and CVD. This review discusses the metabolic syndrome, focusing on the link between insulin resistance, postprandial dyslipidemia, and CVD risk. Furthermore, the clinical significance and functional assessment of postprandial dyslipidemia, specifically in the adolescent population, is discussed in more detail.

Combined Effect of Small Dense Low-Density Lipoprotein Cholesterol (sdLDL-C) and Remnant-Like Particle Cholesterol (RLP-C) on Low-Grade Inflammation

Aims: Small dense low-density lipoprotein cholesterol (sdLDL-C) and remnant-like particle cholesterol (RLP-C) are the novel atherosclerotic risk factors and might be strongly associated with inflammation. The basic evidence supports that sdLDL and RLP have some different mechanisms inducing an inflammatory response. Many studies have focused on the mechanism of inflammation of sdLDL-C or RLP-C per se, with limited data on the association between sdLDL-C and RLP-C in the real-world, population-based setting. Thus, the aim of this study was to investigate the association between sdLDL-C and RLP-C with inflammation.

Methods: We examined the baseline cross-sectional data of participants from the Jichi Medical School-II Cohort Study. In total, 5,305 participants (2,439 men and 2,866 women) were included in this study.

Results: Of all quartiles of sdLDL-C, the fourth had the highest high-sensitivity C-reactive protein (hs-CRP) level. Once adjusted for age, sex, smoking status, homeostasis model assessment of insulin resistance, antidyslipidemic and antihyperglycemic medication use, and RLP-C, sdLDL-C was significantly and positively associated with hs-CRP (geometric mean, 95% confidence interval (CI), 0.36 mg/L (0.34–0.38 mg/L), 0.37 mg/L (0.35–0.39 mg/L), 0.40 mg/L (0.37–0.42 mg/L) versus 0.44 mg/L (0.42–0.47 mg/L), P < 0.001 for trend). After stratifying the participants into four sdLDL-C×four RLP-C categories, the group in the fourth sdLDL-C quartile and the forth RLP-C quartile had the highest hs-CRP level (geometric mean, 95% CI, 0.52 mg/L, 0.48–0.57 mg/L, interaction P = 0.75).

Conclusions: SdLDL-C and RLP-C had different associations with inflammation. Our results support sdLDL-C as the potential novel factor of cardiovascular disease, independently of RLP-C.

Atorvastatin Inhibited ROS Generation and Increased IL-1β And IL-6 Release by Mononuclear Cells from Diabetic Patients

BACKGROUND

Atorvastatin (ATV) inhibits the conversion of 3-Hydroxy-3-Methylglutaryl Coenzyme A (HMG-CoA) to mevalonate formation and promotes lowering of the LDL cholesterol fraction. However, ATV exhibits pleiotropic metabolic actions beyond cholesterol-lowering properties.

OBJECTIVE

We aimed to evaluate the effect of ATV on oxidizing species generation and cytokine secretion in Peripheral Blood Mononuclear Cells (PBMNC) of Type 2 Diabetes Mellitus (T2DM) patients in comparison to healthy control.

METHODS

Both NADPH-oxidase-dependent and mitochondrial ROS generation were assessed by chemoluminescence luminol-dependent assay and fluorometric experiment, using Dichlorofluorescein Assay (DCFH-DA), respectively. IL-1β and IL-6 were quantified by classical ELISA.

RESULTS

ATV inhibited NADPH-oxidase dependent ROS generation, but showed no effect on mitochondrial ROS generation and activated IL-1β and IL-6 secretions in PBMNC from control and T2DM patients. ROS generation and cytokine secretion in the presence of an inhibitor of Protein Kinase Cβ (iPKCβ) and ATV led to similar results. The secretion of IL-1β, PDB-induced in the presence of iPKCβ, but not ATV, was increased. ATV and iPKCβ exacerbated PDB-induced IL-6 secretion. LPS activated the secretion of IL-1β and IL-6 which was potentiated by ATV.

CONCLUSION

ATV inhibited ROS generation and activated IL-1 β/IL-6 secretion in PBMNC of diabetes patients. Its effect was not affected by the hyperglycemia.

Postprandial Hyperlipidemia and Remnant Lipoproteins

Fasting hypertriglyceridemia is positively associated with the morbidity of coronary heart disease (CHD), and postprandial (non-fasting) hypertriglyceridemia is also correlated with the risk status for CHD, which is related to the increase in chylomicron (CM) remnant lipoproteins produced from the intestine. CM remnant particles, as well as oxidized low density lipoprotein (LDL) or very low density lipoprotein (VLDL) remnants, are highly atherogenic and act by enhancing systemic inflammation, platelet activation, coagulation, thrombus formation, and macrophage foam cell formation. The cholesterol levels of remnant lipoproteins significantly correlate with small, dense LDL; impaired glucose tolerance (IGT) and CHD prevalence. We have developed an assay of apolipoprotein (apo)B-48 levels to evaluate the accumulation of CM remnants. Fasting apoB-48 levels correlate with the morbidity of postprandial hypertriglyceridemia, obesity, type III hyperlipoproteinemia, the metabolic syndrome, hypothyroidism, chronic kidney disease, and IGT. Fasting apoB-48 levels also correlate with carotid intima-media thickening and CHD prevalence, and a high apoB-48 level is a significant predictor of CHD risk, independent of the fasting TG level. Diet interventions, such as dietary fibers, polyphenols, medium-chain fatty acids, diacylglycerol, and long-chain n-3 polyunsaturated fatty acids (PUFA), ameliorate postprandial hypertriglyceridemia, moreover, drugs for dyslipidemia (n-3 PUFA, statins, fibrates or ezetimibe) and diabetes concerning incretins (dipeptidyl-peptidase IV inhibitor or glucagon like peptide-1 analogue) may improve postprandial hypertriglyceridemia. Since the accumulation of CM remnants correlates to impaired lipid and glucose metabolism and atherosclerotic cardiovascular events, further studies are required to investigate the characteristics, physiological activities, and functions of CM remnants for the development of new interventions to reduce atherogenicity.

Hyperlipoproteinemia type 3: the forgotten phenotype

Hyperlipoproteinemia type 3 (HLP3) is caused by impaired removal of triglyceride-rich lipoproteins (TGRL) leading to accumulation of TGRL remnants with abnormal composition. High levels of these remnants, called β-VLDL, promote lipid deposition in tuberous xanthomas, atherosclerosis, premature coronary artery disease, and early myocardial infarction. Recent genetic and molecular studies suggest more genes than previously appreciated may contribute to the expression of HLP3, both through impaired hepatic TGRL processing or removal and increased TGRL production. HLP3 is often highly amenable to appropriate treatment. Nevertheless, most HLP3 probably goes undiagnosed, in part because of lack of awareness of the relatively high prevalence (about 0.2% in women and 0.4-0.5% in men older than 20 years) and largely because of infrequent use of definitive diagnostic methods.

Effect of atorvastatin on the angiogenic responsiveness of coronary endothelial cells in normal and streptozotocin (STZ) induced diabetic rats

Atorvastatin, a lipid lowering agent, possesses various pleiotropic vasculoprotective effects, but its role in coronary angiogenesis is still controversial. Our objective was to study the effects of atorvastatin on the angiogenic responsiveness of coronary endothelial cells (cEC) from normal and diabetic rats. Male Wistar rats were distributed among 9 groups; (i) normal rats, (ii) 30 day diabetic rats, (iii) 60 day diabetic rats, (iv) normal rats administered a low dose of atorvastatin (1 mg/kg body mass, per oral (p.o.), for 15 days); (v) 30 day diabetic rats administered a low dose of atorvastatin; (vi) 60 day diabetic rats administered a low dose of atorvastatin; (vii) normal rats administered a high dose of atorvastatin (5 mg/kg, p.o., for 15 days); (viii) 30 day diabetic rats administered a high dose of atorvastatin; (ix) 60 day diabetic rats administered a high dose of atorvastatin. Each group was further divided into 2 subgroups, (i) sham ischemia-reperfusion and (ii) rats hearts that underwent ischemia-reperfusion. Angiogenic responsiveness the and nitric oxide (NO) releasing properties of the subgroups of cECs were studied using a chorioallantoic membrane assay and the Griess method, respectively. Atorvastatin treatment significantly increased VEGF-induced angiogenic responsiveness and the NO-releasing properties of cECs from all of the subgroups, compared with their respective non-treated subgroups except for the late-phase diabetic rat hearts that underwent ischemia-reperfusion, and the high dose of atorvastatin treatment groups. These effects of atorvastatin were significantly inhibited by pretreatment of cECs with l-NAME, wortmannin, and chelerythrine. Thus, treatment with a low dose of atorvastatin improves the angiogenic responsiveness of the cECs from normal and diabetic rats, in the presence of VEGF, via activation of eNOS-NO release.

Protein kinase C beta mediates CD40 ligand-induced adhesion of monocytes to endothelial cells

Accumulating evidence supports the early involvement of monocyte/macrophage recruitment to activated endothelial cells by leukocyte adhesion molecules during atherogenesis. CD40 and its ligand CD40L are highly expressed in vascular endothelial cells, but its impact on monocyte adhesion and the related molecular mechanisms are not fully understood. The present study was designed to evaluate the direct effect of CD40L on monocytic cell adhesion and gain mechanistic insight into the signaling coupling CD40L function to the proinflammatory response. Exposure of cultured human aortic endothelial cells (HAECs) to clinically relevant concentrations of CD40L (20 to 80 ng/mL) dose-dependently increased human monocytic THP-1 cells to adhere to them under static condition. CD40L treatment induced the expression of vascular cell adhesion molecule-1 (VCAM-1) mRNA and protein expression in HAECs. Furthermore, exposure of HAECs to CD40L robustly increased the activation of protein kinase C beta (PKCβ) in ECs. A selective inhibitor of PKCβ prevented the rise in VCAM-1 and THP-1 cell adhesion to ECs. Moreover, stimulation of ECs to CD40L induced nuclear factor-κB (NF-κB) activation. PKCβ inhibition abolished CD40L-induced NF-κB activation, and NF-κB inhibition reduced expression of VCAM-1, each resulting in reduced THP-1 cell adhesion. Our findings provide the evidence that CD40L increases VCAM-1 expression in ECs by activating PKCβ and NF-κB, suggesting a novel mechanism for EC activation. Finally, administration of CD40L resulted in PKCβ activation, increased VCAM-1 expression and activated monocytes adhesiveness to HAECs, processes attenuated by PKCβ inhibitor. Therefore, CD40L may contribute directly to atherogenesis by activating ECs and recruiting monocytes to them.

Endothelial FAK as a therapeutic target in disease

Focal adhesions (FA) are important mediators of endothelial cytoskeletal interactions with the extracellular matrix (ECM) via transmembrane receptors, integrins and integrin-associated intracellular proteins. This communication is essential for a variety of cell processes including EC barrier regulation and is mediated by the non-receptor protein tyrosine kinase, focal adhesion kinase (FAK). As FA mediate the basic response of EC to a variety of stimuli and FAK is essential to these responses, the idea of targeting EC FAK as a therapeutic strategy for an assortment of diseases is highly promising. In particular, inhibition of FAK could prove beneficial in a variety of cancers via effects on EC proliferation and angiogenesis, in acute lung injury (ALI) via the attenuation of lung vascular permeability, and in rheumatoid arthritis via reductions in synovial angiogenesis. In addition, there are potential therapeutic benefits of FAK inhibition in cardiovascular disease and diabetic nephropathy as well. Several drugs that target EC FAK are now in existence and include agents currently under investigation in preclinical models as well as drugs that are readily available such as the sphingolipid analog FTY720 and statins. As the role of EC FAK in the pathogenesis of a variety of diseases continues to be explored and new insights are revealed, drug targeting of FAK will continue to be an important area of investigation and may ultimately lead to highly novel and effective strategies to treat these diseases.

Combination of amlodipine and atorvastatin synergistically reduces leukocyte recruitment to mechanically injured mouse femoral artery

Recent studies have demonstrated a potential synergistic effect of the combination of amlodipine with atorvastatin to reduce acute inflammation. The intraluminal wire injury of the mouse femoral artery induced significant leukocyte recruitment to the injured area and oxidative stress within 24 h. Administration of low-dose amlodipine (0.5 mg kg(-1) per day) or atorvastatin (1 mg kg(-1) per day) alone for 7 days failed to modulate leukocyte adhesion, whereas their co-administration for 7 days significantly inhibited leukocyte adhesion. Moreover, flow cytometric analysis showed that injury-induced oxidative stress and CD11b expression in three leukocyte fractions were elevated after injury and then reduced after the co-administration. Next, adoptive transfer of mononuclear cells (MNCs) was performed and MNCs were harvested from mice after wire injury exhibited adhesion to the recipient injured artery. Furthermore, the co-administration of low-dose atorvastatin and amlodipine to MNCs or the vasculature reduced the recruitment of MNCs to the injured artery. Our findings indicate that amlodipine and atorvastatin synergistically inhibit vascular inflammation. The underlying mechanisms of their effect involve, at least in part, stabilizing oxidative stress at the point of injury, suggesting the clinical efficacy of this drug combination for the treatment of vascular diseases.

Participation of Mac-1, LFA-1 and VLA-4 integrins in the in vitro adhesion of sickle cell disease neutrophils to endothelial layers, and reversal of adhesion by simvastatin

BACKGROUND

Pharmacological approaches to inhibit increased leukocyte adhesive interactions in sickle cell disease may represent important strategies for the prevention of vaso-occlusion in patients with this disorder. We investigated, in vitro, the adhesion molecules involved in endothelial-sickle cell disease neutrophil interactions and the effect of simvastatin on sickle cell disease neutrophil adhesion to tumor necrosis factor-α-activated endothelial monolayers (human umbilical vein endothelial cells), and neutrophil chemotaxis.

DESIGN AND METHODS

Sickle cell disease patients in steady state and not on hydroxyurea were included in the study. Endothelial cells treated, or not, with tumor necrosis factor-α and simvastatin were used for neutrophil adhesion assays. Neutrophils treated with simvastatin were submitted to interleukin 8-stimulated chemotaxis assays.

RESULTS

Sickle cell disease neutrophils showed greater adhesion to endothelial cells than control neutrophils. Adhesion of control neutrophils to endothelial cells was mediated by Mac-1 under basal conditions and by the Mac-1 and LFA-1 integrins under inflammatory conditions. In contrast, adhesion of sickle cell disease neutrophils to endothelium, under both basal and tumor necrosis factor-α-stimulated conditions, was mediated by Mac-1 and LFA-1 integrins and also by VLA-4. Under stimulated inflammatory conditions, simvastatin significantly reduced sickle cell disease neutrophil adhesion, and this effect was reversed by inhibition of nitric oxide synthase. Furthermore, intercellular adhesion molecule-1 expression was significantly abrogated on tumor necrosis factor-α-stimulated endothelium incubated with simvastatin, and statin treatment inhibited the interleukin-8-stimulated migration of both control and sickle cell disease neutrophils.

CONCLUSIONS

The integrins Mac-1, LFA-1 and, interestingly, VLA-4 mediate the adhesion of sickle cell disease leukocytes to activated endothelial cell layers, in vitro. Our data indicate that simvastatin may be able to reduce endothelial activation and consequent leukocyte adhesion in this in vitro model; future experiments and clinical trials may determine whether simvastatin therapy could be employed in patients with sickle cell disease, with beneficial effects on vaso-occlusion.

Casein-derived tripeptide, Val-Pro-Pro (VPP), modulates monocyte adhesion to vascular endothelium

AIM

A food-derived bioactive tripeptide, Val-Pro-Pro (VPP), has been shown to possess angiotensin I-converting enzyme (ACE) inhibitory activity and foods containing such peptides exhibit an anti-hypertensive effect in clinical settings.

METHODS

The present study focused on the effect of VPP on monocyte adhesion to endothelium under flow conditions using phorbol 12-myristate 13-acetate (PMA)-stimulated monocytic THP-1 cells.

RESULTS

Pre-incubation of THP-1 cells with VPP (1 mM, 24 hours) significantly decreased the PMA-induced adhesion of THP-1 cells (p<0.05) to human umbilical vein endothelial cells (HUVECs). PMA-induced up-regulation of beta1 and beta2 integrin activation in THP-1 cells was downregulated by VPP, which significantly suppressed only the PMA-induced phosphorylation of JNK (p<0.05) in THP-1 cells. In addition, preincubation of THP-1 with SP600125, a specific inhibitor of JNK, resulted in significant reduction of the PMA-induced adhesion of THP-1. Interestingly, another tripeptide with comparable ACE inhibitory activity, Leu-Gly-Pro (LGP), failed to reduce the PMA-induced adhesion of THP-1, suggesting a distinct anti-inflammatory effect of VPP on THP-1 adhesion.

CONCLUSION

These observations suggest that VPP moderates monocyte adhesion to inflamed endothelia via attenuation of the JNK pathway in monocytes, which might contribute to the primary prevention of atherosclerosis.

Pleiotropic vasoprotective effects of statins: the chicken or the egg?

Statins (3-hydroxy-3-methyl glutaryl coenzyme A [HMG-CoA] reductase inhibitors) are the most commonly used lipid-lowering drugs. Their main lipid-lowering effect is achieved by an increase in the expression of low-density lipoprotein cholesterol receptors associated with inhibition of cholesterol synthesis through inhibition of HMG-CoA reductase - the first and rate-limiting step in cholesterol synthesis. However, beyond cholesterol synthesis inhibition, inhibition of the HMG-CoA reductase affects as well the synthesis of other molecules with significant roles in different, yet often intercalating, metabolic pathways. On this basis, and supported by an increasing series of advocating epidemiological and experimental data, an extended dialogue has been established over the last few years regarding the nonlipid or "pleiotropic" actions of statins.

Polymorphisms of fractalkine receptor CX3CR1 gene in patients with symptomatic and asymptomatic carotid artery stenosis

AIM

The chemokine fractalikine is expressed in vascular endothelium, exerting a pro-atherogenic effect. Two single-nucleotide polymorphisms of the CX3CR1 gene (T280M and V249I) affect frac-talkine receptor expression and function. We aimed to assess the prevalence of CX3CR1 polymor-phisms and the association with ischemic cerebrovascular attacks in a cohort of carotid atheromatous disease patients and age-matched controls.

METHODS

Using PCR-RFLP, we analyzed allelotypes for T280M and V249I in 150 patients with and 151 controls without carotid atherosclerosis assessed using carotid duplex ultrasound; the subjects were patients admitted for any reason to a tertiary hospital. Genotype data were compared with modifiable risk factors for cerebrovascular disease and the reason for admission, using ischemic stroke as an endpoint. Stroke types associated with carotid atherosclerosis were analysed separately.

RESULTS

The M280 allelic frequency was lower among carotid atherosclerosis patients than controls (0.15 versus 0.23, adjusted OR 0.47, 95% CI 0.30-0.74). Absence of M280 allele was an indepen-dent factor associated with carotid atherosclerosis (OR 3.70, 95% CI 1.92-7.14), stronger than hypertension, dyslipidemia, diabetes and cigarette smoking. The I249 allele was also under-repre-sented in carotid atherosclerosis; this was not statistically significant. T280M and V249I genotypes were not associated with admission due to ischemic stroke of the large vessel subtype (TOAST classi-fication, 73 episodes), whereas carotid atherosclerosis, previous ischemic event, age, hypertension, diabetes, hyperlipidemia and cigarette smoking were all independently associated.

CONCLUSIONS

The M280 fractalkine receptor gene allele is associated with a lower risk of carotid ath-eromatous disease, independent from the modifiable cerebrovascular risk factors.

Remnant lipoproteins as strong key particles to atherogenesis

Recent epidemiologic studies have revealed that hypertriglyceridemia is associated with atherosclerosis independent of other coronary risk factors. However, it is difficult to select patients at high risk for coronary artery disease using only serum triglyceride levels compared with low-density lipoprotein cholesterol levels since multiple factors are associated with elevating triglycerides. Atherosclerotic diseases with high triglyceride levels can be found in patients with familial combined hyperlipidemia, diabetes mellitus, and metabolic syndrome, in which remnant lipoproteins accumulate in the circulating blood. Recent researches have paid attention to remnant lipoproteins as atherogenic particles with the development of methods for measuring remnant cholesterol levels and apolipoprotein B-48 levels directly from human serum. Measurement of these parameters in addition to serum triglycerides may help to distinguish high-risk patients and enable us to prevent or suppress the progression of atherosclerotic diseases in those patients. However, questions remain to be answered to evaluate the significance of remnant lipoproteins. Here, we focus on three issues: the underlying problems in measuring remnant lipoprotein cholesterol, the assessment of postprandial hyperlipidemia as an atherogenic condition, and finally a review of our experimental and clinical findings about the mechanisms by which remnant lipoproteins induce atherosclerosis.

Apolipoprotein CIII links dyslipidemia with atherosclerosis

Plasma levels of lipoproteins that contain apolipoprotein (apo) CIII predict coronary heart disease (CHD), and associate with contributors to metabolic syndrome such as type 2 diabetes and hypertriglyceridemia. ApoCIII causes hypertriglyceridemia by inhibiting the catabolism and the clearance of TG-rich lipoproteins (TLRs), and the association of apoCIII with CHD has been commonly attributed to these properties; however, it has been untested whether apoCIII itself or in association with lipoproteins directly affects atherogenic mechanisms in vascular cells. This review describes the proatherogenic effect of apoCIII-containing lipoproteins. In brief, apoCIII-rich VLDL (VLDL CIII+) increased the adhesion of human monocytes to vascular endothelial cells (ECs). ApoCIII alone also increased monocyte adhesion to vascular ECs. Interestingly, apoCIII-rich HDL did not reduce the adhesion of monocytes to vascular ECs, whereas HDL without apoCIII decreased their adhesion, suggesting that apoCIII in HDL counteracts the anti-inflammatory property of HDL. ApoCIII alone as well as VLDL CIII+also activated vascular ECs through the activation of NF-kappaB, and induced the recruitment of monocytes to vascular ECs. Moreover, apoCIII induced insulin resistance in vascular ECs and caused endothelial dysfunction. These findings indicate that apoCIII in TLRs not only modulates their metabolism, but also may directly contribute to the development of atherosclerosis by activating the proinflammatory signal transduction of vascular cells. Here, we propose a novel role for apoCIII that links dyslipidemia with atherosclerosis.

Metabolic syndrome abating the beneficial effect of pravastatin treatment on adhesion of endothelium by monocytes in subjects with hypercholesterolemia

Statin, a potent lipid-lowering agent, ameliorates the interaction of monocytes and endothelium, a critical step in the atherosclerotic process. However, it remains unclear whether this effect of statin depends on different doses or the presence of metabolic syndrome. In this prospectively double-blind study, 21 hypercholesterolemia subjects, with low-density lipoprotein cholesterol between 130 and 170 mg/dL, received low-dose (10 mg/d) or high-dose (40 mg/d) pravastatin treatment for 8 weeks. We assessed the reduction of monocyte adhesion to cultured endothelium between different-dose groups and the relationship to metabolic syndrome. Total cholesterol and low-density lipoprotein cholesterol were significantly decreased after 40-mg pravastatin treatment (-23.3% +/- 3.7%, P < .001 and -28.8% +/- 3.0%, P < .001), and the reductions were greater than those in the 10-mg group (P = .041 and P = .045, respectively). There was no significant difference in monocyte adhesion between high-dose and low-dose pravastatin treatment. When all subjects were divided into an improvement group and a no improvement group, according to the median of change percentage of monocyte adhesion after pravastatin treatment, there were significantly more subjects with metabolic syndrome in the no improvement than the improvement group (6 vs 1 person, P =.024). Using logistic regression analysis, metabolic syndrome, rather than dose effect of pravastatin, was an independent predictor of interaction between monocytes and endothelium (95% confidence interval = 0.001-0.865, P = .041). Attenuating adhesion between monocytes and endothelium is altered by the presence of metabolic syndrome when hypercholesterolemia subjects receive pravastatin treatment.

Toll-like receptor 2 mediates apolipoprotein CIII-induced monocyte activation

Apolipoprotein (apo)CIII predicts risk for coronary heart disease. We recently reported that apoCIII directly activates human monocytes. Recent evidence indicates that toll-like receptor (TLR)2 can contribute to atherogenesis through transduction of inflammatory signals. Here, we tested the hypothesis that apoCIII activates human monocytoid THP-1 cells through TLR2. ApoCIII induced the association of TLR2 with myeloid differentiation factor 88, activated nuclear factor (NF)-kappaB in THP-1 cells, and increased their adhesion to human umbilical vein endothelial cells (HUVECs). Anti-TLR2 blocking antibody, but not anti-TLR4 blocking antibody or isotype-matched IgG, inhibited these processes (P<0.05). ApoCIII bound with high affinity to human recombinant TLR2 protein and showed a significantly higher (P<0.05) and saturable binding to 293 cells overexpressing human TLR2 than to parental 293 cells with no endogenous TLR2. Overexpression of TLR2 in 293 cells augmented apoCIII-induced NF-kappaB activation and beta(1) integrin expression, processes inhibited by anti-apoCIII antibody as well as anti-TLR2 antibody. Exposure of peripheral blood monocytes isolated from C57BL/6 (wild-type) mice to apoCIII activated their NF-kappaB and increased their adhesiveness to HUVECs. In contrast, apoCIII did not activate monocytes from TLR2-deficient mice. Finally, intravenous administration to C57BL/6 mice of apoCIII-rich very-low-density lipoprotein (VLDL), but not of apoCIII-deficient VLDL, activated monocytes and increased their adhesiveness to HUVECs, processes attenuated by anti-TLR2 or anti-apoCIII antibody. ApoCIII-rich VLDL did not activate monocytes from TLR2-deficient mice. In conclusion, apoCIII activated monocytes at least partly through a TLR2-dependent pathway. The present study identifies a novel mechanism for proinflammatory and proatherogenic effects of apoCIII and a role for TLR2 in atherosclerosis induced by atherogenic lipoproteins.

Apolipoprotein CIII links hyperlipidemia with vascular endothelial cell dysfunction

BACKGROUND

Apolipoprotein CIII (apoCIII) is a component of some triglyceride-rich very-low-density and low-density lipoprotein and is elevated in dyslipidemia with insulin resistance and the metabolic syndrome. We previously reported that apoCIII directly activates proinflammatory and atherogenic signaling in vascular endothelial cells through protein kinase C-beta (PKCbeta). Because PKCbeta impairs the response of vascular endothelial cells to insulin, we tested the hypothesis that apoCIII affects insulin signaling in vascular endothelial cells and its function in vitro and in vivo.

METHODS AND RESULTS

ApoCIII inhibited insulin-induced tyrosine phosphorylation of insulin receptor substrate 1 (IRS-1), decreasing phosphatidylinositol 3-kinase (PI3K)/Akt activation in human umbilical vein endothelial cells. These effects of apoCIII led to reduced endothelial nitric oxide synthase (eNOS) activation and NO release into the media. ApoCIII activated PKCbeta in human umbilical vein endothelial cells, resulting in IRS-1 dysfunction via serine phosphorylation. ApoCIII also activated mitogen-activated protein kinase through PKCbeta. The impaired insulin signaling was restored by PKCbeta inhibitor or MEK1 inhibitor. ApoCIII-rich very-low-density lipoprotein and apoCIII impaired insulin signaling in the aorta of C57BL/6J mice and in human umbilical vein endothelial cells, which was recovered by PKCbeta inhibitor. They also inhibited endothelium-dependent relaxation of the aortas of C57BL/6J mice. In summary, apoCIII in very-low-density lipoprotein impaired insulin stimulation of NO production by vascular endothelium and induced endothelial dysfunction in vivo. This adverse effect of apoCIII was mediated by its activation of PKCbeta, which inhibits the IRS-1/PI3K/Akt/eNOS pathway.

CONCLUSIONS

Our results suggest that apoCIII is a crucial link between dyslipidemia and insulin resistance in vascular endothelial cells with consequential deleterious effects on their atheroprotective functions.

Lectin-like oxidized LDL receptor-1 (LOX-1) acts as a receptor for remnant-like lipoprotein particles (RLPs) and mediates RLP-induced migration of vascular smooth muscle cells

OBJECTIVE

Remnant-like lipoprotein particles (RLPs) have been implicated in atherogenesis especially by diabetic dyslipidemia; however, their receptor(s) and effects on vascular smooth muscle cells (VSMCs) remain unclear. In this study, we examined if lectin-like oxidized LDL receptor-1 (LOX-1) acts as a receptor for RLPs and its biological effects in VSMCs.

METHODS AND RESULTS

RLPs were isolated from human plasma by immunoaffinity gel containing anti-apolipoprotein A-I and anti-apolipoprotein B-100 monoclonal antibodies. DiI-labeled RLPs were taken up by CHO-K1 cells stably expressing LOX-1 but not by wild-type CHO-K1 cells. RLPs induced LOX-1 expression and cell migration in bovine VSMCs (BVSMCs), which were significantly suppressed by transfection with LOX-1 specific siRNAs. Inhibitors of metalloproteinases, epidermal growth factor (EGF) receptor tyrosine kinase, heparin-binding EGF-like growth factor (HB-EGF), p38 mitogen-activated protein kinase (p38 MAPK), MAPK kinase (MEK1) and phosphoinositide 3-kinase (PI3K) significantly blocked RLP-induced LOX-1 expression and cell migration of BVSMCs.

CONCLUSIONS

The present study provides direct evidence that LOX-1 is a novel receptor for RLPs in VSMCs. LOX-1-mediated uptake of RLPs may thus play important roles in atherogenesis by inducing LOX-1 expression and VSMC migration especially in the settings of postprandial hyperlipidemia, diabetes and metabolic syndrome.

Suppressive effects of diacylglycerol oil on postprandial hyperlipidemia in insulin resistance and glucose intolerance

The diacylglycerol (DAG), a commonly used as a cooking oil in Japan, results in a lower elevation of serum triglyceride (TG) after ingestion compared to triacylglycerol (TAG). Postprandial hyperlipidemia (PPHL) and an increase in remnant lipoproteins (RLP) levels are risk factors for CAD, and a close relationship between PPHL and type 2 diabetes and/or insulin resistance has been reported. To evaluate the effect of DAG on PPHL in insulin resistance and glucose intolerance, 11 subjects with a normal glucose tolerance (NGT) and 14 subjects with IGT received oral fat tolerance test (OFTT) twice. They ingested emulsified test oils prepared with either DAG or TAG. In the IGT subjects, after the DAG and TAG load, the serum concentrations of TG, RLP-TG, and RLP-cholesterol increased throughout the 4-h study. The responses of these variables above baseline after the DAG load were significantly smaller than those after the TAG load (p<0.05). In contrast, in the NGT subjects, changes in these parameters were much smaller than those observed for IGT subjects. The difference in the integrated responses for serum RLP-cholesterol concentration during OFTT between DAG and TAG in all subjects can be easily explained by the integrated response of insulin rather than glucose during oral glucose tolerance test (r=0.7, p<0.01). DAG was more effective in insulin resistant and hyperinsulinemic participants regardless of glucose intolerance, and may be beneficial in reducing the extent of CAD risk in such individuals.

Angiotensin-Converting Enzyme Inhibitor Attenuates Monocyte Adhesion to Vascular Endothelium through Modulation of Intracellular Zinc

To elucidate an anti-inflammatory role of angiotensin-converting enzyme inhibitors (ACEIs) in cardiovascular disease, we studied the effect of ACEIs in monocyte adhesion to endothelial cells and underlying molecular mechanisms. Treatment of human monocytic THP-1 cells with monocyte chemoattractant protein-1 (MCP-1; 100 ng/ml; 10 min) significantly increased their adhesion to human umbilical vein endothelial cells (HUVECs) under flow condition (P < 0.001). Preincubation of THP-1 cells with imidaprilat (50 nM; 4 h), an active metabolite of imidapril, reduced MCP-1-triggered THP-1 cell adhesion (P < 0.01). Similar effects were obtained with experiments using human peripheral monocytes (P < 0.05). MCP-1 activated protein kinase C (PKC)alpha in THP-1 cells, resulting in the up-regulation of alpha4 and beta2 integrin. Imidaprilat attenuated MCP-1-induced PKC activation and integrin up-regulation in THP-1 cells. Imidaprilat also inhibited THP-1 cell adhesion induced by phorbol 12-myristate 13-acetate (PMA), a potent PKC activator. In attempt to elucidate the mechanisms for the modulation of PKC activity by imidaprilat, we found that MCP-1 or PMA increased labile zinc in THP-1 cells, which was canceled by imidaprilat. Indeed, zinc/pyrithione activated PKC and increased THP-1 cell adhesion. Zinc chelator as well as PKC inhibitor inhibited these processes, suggesting the role for labile zinc in PKC activation and THP-1 cell adhesion. Imidaprilat attenuated zinc/pyrithione-induced PKC activation and THP-1 cell adhesion. These data suggest that ACEI reduces MCP-1 or PMA-triggered monocyte adhesion to activated HUVECs by modulating labile zinc in monocytes. Our findings may point out a novel anti-inflammatory mechanism of ACEIs in atherogenesis.

Sphingosine 1-phosphate (S1P) inhibits monocyte-endothelial cell interaction by regulating of RhoA activity

Recent studies suggest that sphingosine 1-phosphate (S1P) protects against atherosclerosis. We assessed the effects of S1P on monocyte-endothelial interaction in the presence of inflammatory mediators. Pretreatment of THP-1 cells with S1P abolished Phorbol 12 myristate 13-acetate (PMA)-induced THP-1 cell adhesion to human umbilical vein endothelial cells (HUVECs). S1P inhibited PMA-induced activation of RhoA, but not PKCs. S1P activated p190Rho GTPase activation protein (GAP) only in the presence of PMA, suggesting an inhibitory effect of S1P and PMA to suppress RhoA. In conclusion, S1P inhibited monocyte-endothelial interactions by inhibiting RhoA activity which may explain its anti-atherogenic effects.

Immunomodulation by statins: Inhibition of cholesterol vs. isoprenoid biosynthesis

Due to their ability to inhibit the synthesis of cholesterol, statins are widely used in medical practice and are the principal therapy for hypercholesterolemia. In addition, various findings suggest that statins also exert anti-inflammatory properties and may so play a role in modulating the immune system. Because of these properties, statins could provide a potential treatment for various chronic inflammatory diseases, including neuroinflammatory disorders such as multiple sclerosis. Here, we will review the effect of statins on the expression and function of a variety of immune relevant molecules and the underlying mechanisms that contribute to the immunomodulatory properties of statins. In this discussion we will also evaluate the effects of statins on central nervous system cells to emphasize the potential of these agents in the treatment of neuroinflammatory disorders.

Remnant-like lipoprotein particles impair endothelial function: direct and indirect effects on nitric oxide synthase

Remnant-like lipoprotein particles (RLPs) have been implicated as potentially atherogenic lipoproteins. Endothelial dysfunction is known to be an early event in atherosclerosis and an important contributor to the pathogenesis of coronary artery disease. Moreover, there is considerable evidence linking increased RLP cholesterol levels with endothelial dysfunction, reflected by impaired endothelial vasodilatation and abnormal endothelial secretion. The underlying mechanisms by which RLPs may contribute to endothelial dysfunction are complex and have not been completely elucidated. Because the expression and activation of endothelial nitric oxide synthase (eNOS) are vital to endothelial function, and recent data have implied an association between RLPs and eNOS, this manuscript proposes the hypothesis that RLPs could impair endothelial function via direct and indirect effects on eNOS: RLPs may affect the autophosphorylation of focal adhesion kinase and its downstream phosphatidylinositol kinase/Akt (protein kinase B) signaling pathway, resulting in eNOS inactivation through induction of intracellular oxidative stress in endothelial cells; and RLPs could affect the expression or activation of eNOS indirectly by stimulating secretion of various inflammatory factors from multiple origins. The practical applications of this manuscript provide new insights for the future investigation of RLPs.

Endothelial and leukocyte adhesion molecules in primary hypertriglyceridemia

Hypertriglyceridemia is known to be associated to functional impairment of the endothelium and, consequently, to higher risk of atherosclerosis. Nevertheless, some crucial steps in the development of the atherosclerotic plaque are still unknown in primary hypertriglyceridemia. The aim of the present study was to explore the expression of soluble and leukocyte-associated cell adhesion molecules in a group of patients with primary hypertriglyceridemia, both including (n=50) and excluding (n=24) subjects with metabolic syndrome, in comparison with control normotriglyceridemic individuals (n=30). Lipid profile, CETP activity, HDL and VLDL chemical composition were evaluated. Soluble (VCAM-1, ICAM-1 and E-selectin) and leukocyte cell adhesion molecules (CD18, CD49d and CD54) were measured by enzyme-linked immunosorbent assay and flow cytometry, respectively. Patients with primary hypertriglyceridemia as compared with control subjects showed significantly higher VCAM-1 (15.6+/-4.5 ng/ml versus 13.9+/-3.8 ng/ml, respectively; p<0.05) and ICAM-1 (16.9+/-3.1 ng/ml versus 15.2+/-3.2 ng/ml, respectively; p<0.05). Regarding leukocyte cell adhesion molecules, significant increases were also detected in monocyte CD18 (398+/-180 versus 332+/-136 arbitrary units, respectively; p<0.05) and CD54 (49+/-14 versus 42+/-12 arbitrary units, respectively; p<0.05), and lymphocyte CD18 (122+/-53 versus 101+/-33 arbitrary units, respectively; p<0.05). ICAM-1 plasma levels, as well as monocyte CD18 and CD54, and lymphocyte CD18 persisted elevated even if patients with metabolic syndrome were discarded among those with hypertriglyceridemia. The increase in circulating and leukocyte cell adhesion molecules in primary hypertriglyceridemic patients would highlight the inflammatory process which is a key event in atherogenesis.

The role of hypertriglyceridemia in atherosclerosis

Atherosclerosis is a chronic disease associated with accumulation of lipids in lesions along blood vessels, leading to the occlusion of blood flow. Much of the focus has been on the role of low-density lipoprotein (LDL), and of oxidatively modified LDL, in the initiation and progression of this disease. LDL is in fact a metabolic end-product of the triglyceride-rich lipoproteins (ie, very-low density lipoproteins). Over the years, univariate analyses have implicated triglycerides as a contributor in atherosclerosis. However, depending on the studies, the significance of this relationship is either reduced or nullified when other co-variates are taken into account. This review summarizes more recent data that support the role of triglyceride-rich lipoproteins in the atherosclerotic process, both in the fasted as well as in the postprandial state.

HIV envelope protein gp120-triggered CD4+ T-cell adhesion to vascular endothelium is regulated via CD4 and CXCR4 receptors

Activation of T-lymphocytes is an important component of inflammatory and infectious processes, including HIV infection. It is regulated via the actions of various cell-surface receptors, including CD4 and CXCR4. We examined the roles of CD4 and CXCR4 in the adhesive interaction of CD4+T-cells with the vascular endothelium. CD4+Jurkat cells were incubated in the presence or absence of anti-CD4 to stimulate CD4, or with SDF-1 alpha, a cognate ligand of CXCR4. Stimulation of CD4 or CXCR4 each significantly enhanced cell adhesion. We next stimulated the two receptors together, using gp120, a component of HIV. This enhanced cell adhesion was greater than stimulation of CD4 or CXCR4 individually. Western blotting revealed that stimulation of CXCR4 by SDF-1 alpha significantly increased the phosphorylation of ERK1/2 in Jurkat cells. Treatment with anti-CD4 also activated ERK1/2, although to a lesser extent. When the expression of CD4 was reduced by siRNA transfection, both CD4-dependent adhesion and MAPK activation were diminished. Furthermore, pre-treatment with fluvastatin, significantly attenuated observed Jurkat cell adhesion. These findings indicate novel mechanisms of CD4+ T-cells recruitment to activated endothelium via CD4 and CXCR4, which are modulated by statin.

Remnant like particles may induce atherosclerosis via accelerating endothelial progenitor cells senescence

Remnant like particles (RLPs) are closely associated with coronary heart disease, whereas the underlying mechanisms are complex and have not been fully elucidated. Studies show that maintenance of endothelial cells layer is essential for normal function of vessel. Endothelial progenitor cells (EPCs) were shown to incorporate into sites of neovascularization and home to sites of endothelial denudation, thus provide an endogenous repair mechanism. Risk factors of coronary heart disease can impair EPCs repairing function by inducing EPCs senescence. EPCs senescence is associated with telomerase inactivation, which is regulated via phosphatidylinositol-3-kinase/Akt kinase (PI3K/Akt) signaling pathway. RLPs are triglyceride rich lipoproteins reflecting chylomicron remnants and very-low-density lipoprotein remnants. RLPs can impair endothelial function via inhibiting endothelial NO synthase (eNOS) activity and nitric oxide (NO) production by inducing intracellular oxidant levels. However, there is no research about effect of RLPs on EPCs. Evidence shows that RLPs can induce focal adhesion kinase (FAK) activation in monocytic U937 cells. Therefore, it can be hypothesized that RLPs could inhibit eNOS and telomerase activities, thus induce atherosclerosis by promoting EPCs senescence via FAK and its downstream PI3K/Akt pathway through an oxidative mechanism.

Cholesteryl ester transfer protein promotes the formation of cholesterol-rich remnant like lipoprotein particles in human plasma

BACKGROUND

Cholesteryl ester transfer protein (CETP) is suggested to be involved in the cholesterol level in remnant like lipoprotein particles (RLP), but there is no direct evidence that CETP increases cholesterol-rich RLP in plasma.

METHODS

Human plasma was incubated with or without HDL containing [(3)H]-labeled cholesteryl ester ([(3)H]CE), recombinant CETP or CETP inhibitors at 37 degrees C in vitro.

RESULTS

The RLP-cholesterol (RLP-C) level increased time-dependently and the amount of RLP-C increase (DeltaRLP-C) by the incubation was positively correlated with triglyceride (TG) level in plasma (r=0.597, P=0.0070). [(3)H]CE in HDL was transferred to RLP fraction under 37 degrees C incubation, and the amount of [(3)H]CE transferred to RLP correlated significantly with DeltaRLP-C in plasma (r=0.611, P=0.0156). Human recombinant CETP enhanced the RLP-C increase, while CETP inhibitor JTT-705 and anti-human CETP monoclonal antibody inhibited both the RLP-C increase and [(3)H]CE transfer to RLP. On the other hand, an inhibition of lecithin: cholesterol acyltransferase (LCAT) did not affect the RLP-C increase. In triglyceride-rich lipoproteins (TRL) fraction, JTT-705 inhibited [(3)H]CE transfer to RLP more strongly than that to non-RLP.

CONCLUSIONS

CETP promotes the formation of cholesterol-rich RLP through the transfer of CE from HDL to TRL and CETP inhibitors are useful to reduce RLP-C.

High plasma concentration of remnant lipoprotein cholesterol in obese children and adolescents

OBJECTIVE

Remnant lipoproteins (RLPs) are the products of the lipolytic degradation of triglyceride-rich lipoproteins produced by the liver and intestine. Recent studies have demonstrated that RLPs are correlated with cardiovascular risk. We assessed the relationship between obesity and RLP and evaluated the factors related to RLP in children and adolescents.

RESEARCH DESIGN AND METHODS

We measured BMI, waist circumference, blood pressure, body fat mass, total abdominal fat, visceral and subcutaneous fat areas, fasting glucose, insulin, total cholesterol, triglycerides, LDL cholesterol, HDL cholesterol, and RLP cholesterol in 135 children and adolescents (67 boys and 68 girls). Plasma RLP fractions were isolated using an immunoaffinity gel containing specific anti-apolipoprotein (apo) B-100 and anti-apoA-I antibodies. Based on the BMI percentile, the subjects were divided into two groups: normal (< 85th percentile) and overweight (> or = 85th percentile).

RESULTS

RLP cholesterol was significantly correlated with age, sex, BMI, waist circumference, systolic and diastolic blood pressures, visceral and subcutaneous fat areas, visceral-to-subcutaneous fat area ratio, total cholesterol, triglycerides, HDL cholesterol, apoB, and homeostasis model assessment of insulin resistance (HOMA-IR). According to the multivariate regression analysis, triglycerides (beta = 0.928, P < 0.001) were independently correlated with RLP cholesterol. After excluding lipid profiles as an independent variable, the multivariate regression analysis revealed that HOMA-IR (beta = 0.231, P = 0.007) and systolic blood pressure (beta = 0.169, P = 0.046) were independently associated with RLP cholesterol.

CONCLUSIONS

RLP cholesterol was significantly higher in obese children and adolescents. Triglycerides, systolic blood pressure, and insulin resistance were related to RLP cholesterol.

SDF-1-induced adhesion of monocytes to vascular endothelium is modulated by azelnidipine via protein kinase C inhibition

Monocyte-endothelial interaction and its modulation by chemokines play a key role in atherogenesis and inflammation. We examined the potential effects of stromal cell-derived factor (SDF-1) and azelnidipine, a novel dihydropyridine derivative, toward monocyte-endothelial interaction. Human monocytes were prepared from peripheral blood mononuclear cells obtained from healthy volunteers and pretreated with azelnidipine (1 microM) for 48 h, after which their adhesion to interleukin-1beta (IL-1beta)-activated human umbilical vein endothelial cells (HUVECs) was analyzed using an in vitro flow apparatus with a shear stress of 1 dyn/cm(2). In some experiments, monocytes were incubated in the presence of stromal cell-derived factor (SDF-1), a chemokine, just prior to the assay. Pre-incubation of monocytes with SDF-1 enhanced their adhesion to activated HUVECs. When monocytes were pre-incubated in the presence of azelnidipine, baseline levels as well as SDF-1-induced monocyte adhesion levels were reduced. Interestingly, the surface expressions of the adhesion molecules CD11a, CD11b, and CD36, were not changed by azelnidipine treatment. Western blotting analysis revealed that activation of protein kinase C (PKC)alpha was inhibited by azelnidipine treatment, while it also reduced the SDF-1-induced increase in intracellular calcium concentration ([Ca(2+)](i)). Further, pre-incubation of monocytes with Go6976, a potent inhibitor of PKCalpha, significantly reduced monocyte adhesion to HUVECs. Our results demonstrated an inhibitory action of azelnidipine toward adhesive interactions of monocytes to HUVECs, which involves inhibition of PKCalpha and a reduction in [Ca(2+)](i). These findings imply a protective role of azelnidipine against inflammation in atherosclerosis.

Apolipoprotein CIII induces expression of vascular cell adhesion molecule-1 in vascular endothelial cells and increases adhesion of monocytic cells

BACKGROUND

Activation of vascular endothelial cells (ECs) plays an important role in atherogenesis and plaque instability. Lipoproteins containing apolipoprotein CIII (apoCIII) predict coronary heart disease (CHD). We recently reported that apoCIII has a proinflammatory effect on human monocytes. In this study, we looked for a direct effect of apoCIII on EC expression of adhesion molecules, leading to monocytic cell adhesion.

METHODS AND RESULTS

Treatment of ECs with apoCIII or apoCIII-rich VLDL caused human monocytic THP-1 cells to adhere to them under static condition or under laminar sheer stress (1.0 dyne/cm2). ApoCIII increased EC expression of vascular cell adhesion molecule-1 (VCAM-1) protein and intercellular cell adhesion molecule-1 (ICAM-1) protein (4.9 +/- 1.5-fold and 1.4 +/- 0.5-fold versus control, respectively). Furthermore, apoCIII remarkably increased membrane-bound protein kinase C (PKC) beta in ECs, indicating activation. A selective inhibitor of PKCbeta prevented the rise in VCAM-1 and THP-1 cell adhesion to ECs. Moreover, exposure of ECs to apoCIII induced nuclear factor-kappaB (NF-kappaB) activation. PKCbeta inhibition abolished apoCIII-induced NF-kappaB activation, and NF-kappaB inhibition reduced expression of VCAM-1, each resulting in reduced THP-1 cell adhesion. ApoCIII-rich VLDL also activated PKCbeta and NF-kappaB in ECs and increased expression of VCAM-1. Pretreatment of ApoCIII-rich VLDL with anti-apoCIII neutralizing antibody abolished its effect on PKCbeta activation.

CONCLUSIONS

Our findings provide the first evidence that apoCIII increases VCAM-1 and ICAM-1 expression in ECs by activating PKCbeta and NF-kappaB, suggesting a novel mechanism for EC activation induced by dyslipidemia. Therefore, apoCIII-rich VLDL may contribute directly to atherogenesis by activating ECs and recruiting monocytes to them.

The oxidative modification hypothesis of atherosclerosis: The comparison of atherogenic effects on oxidized LDL and remnant lipoproteins in plasma

A tremendous number of articles on oxidized LDL (Ox-LDL) and scavenger receptor in macrophage have been published since Steinberg proposed Ox-LDL hypothesis as the major cause of atherosclerosis. This hypothesis has provided strong support for the efficacy of LDL lowering drugs, indicating that lowering LDL means lowering Ox-LDL in vivo. This manuscript proposed a new oxidative modification hypothesis that remnant lipoproteins determined as remnant-like lipoprotein particles (RLP), not LDL are the major oxidized lipoproteins in plasma, resulting from the plasma concentration of these oxidized lipoproteins. Remnant lipoproteins may play a pivotal role for the initiation of atherosclerosis via lectin-like oxidized LDL receptor-1 (LOX-1) in endothelial cells. Isolated remnant lipoproteins were found to be oxidized or susceptible to be oxidized in plasma, not necessary to be further oxidized in vitro as Ox-LDL. High similarity of proatherogenic and proinflammatory properties of isolated Ox-LDL and remnant lipoporteins have been reported and predicted the presence of similar oxidized phospholipids in both lipoproteins as bioactive components. These results suggest the possibility that reducing plasma remnant lipoproteins rather than LDL should be the target for hyperlipidemic therapy especially in patients with metabolic syndrome for the prevention of endothelial dysfunction in the initiation of atherosclerosis.

Apolipoprotein CIII in apolipoprotein B lipoproteins enhances the adhesion of human monocytic cells to endothelial cells

BACKGROUND

Lipoproteins containing apolipoprotein (apo) CIII predict coronary heart disease and associate with components of the metabolic syndrome. ApoCIII inhibits lipoprotein catabolism in plasma. However, it is unknown whether apoCIII itself, or in association with VLDL, LDL, or HDL, directly affects atherogenic mechanisms in vascular cells. Thus, we investigated the direct effect of lipoproteins that do or do not have apoCIII, and apoCIII itself, on adhesion of THP-1 cells, a human monocytic cell line, to vascular endothelial cells (ECs).

METHODS AND RESULTS

VLDL CIII+ and LDL CIII+ (100 microg apoB/mL) from fasting plasma of 18 normolipidemic volunteers increased THP-1 cell adhesion to ECs under static conditions by 2.4+/-0.3-fold and 1.8+/-0.7-fold, respectively (P<0.01), whereas VLDL or LDL without apoCIII did not affect THP-1 cell adhesion. ApoCIII (100 microg/mL), but not apoCI, apoCII or apoE, also increased THP-1 cell adhesion by 2.1+/-0.6-fold. Studies with human peripheral blood monocytes yielded similar results. ApoCIII also had strong proadhesive effects under shear flow conditions. VLDL CIII+, LDL CIII+, or apoCIII itself activated PKCalpha and RhoA in THP-1 cells, which resulted in beta1-integrin activation and enhancement of THP-1 cell adhesion. Interestingly, HDL CIII+ did not affect THP-1 cell adhesion, whereas HDL without apoCIII decreased their adhesion.

CONCLUSIONS

ApoB lipoproteins that contain apoCIII increase THP-1 cell adhesion to ECs via PKCalpha and RhoA-mediated beta1-integrin activation. These results indicate that apoCIII not only modulates lipoprotein metabolism but also may directly contribute to the development of atherosclerosis.

Involvement of Rho signaling in PAR2-mediated regulation of neutrophil adhesion to lung epithelial cells

Protease-activated receptor 2 (PAR2) has been implicated in the pathogenesis of airway inflammation. We report that epithelial PAR2 stimulation with trypsin (0.05-1 U/ml) or an agonist peptide (SLIGKV-NH2, 1-100 microM) for 0.5-3 h dose- and time-dependently enhanced neutrophil adhesion to alveolar type II epithelial cells (A549 cells) and that this stimulation also induced the formation of epithelial actin filaments. Both responses in neutrophil adhesion and epithelial actin reorganization were reduced by a Rho inhibitor, mevastatin and by a Rho-associated kinase (ROCK) inhibitor, Y-27632 ((R)-(+)-trans-N-(4-Pyridyl)-4-(1-aminoethyl)-cyclohexanecarboxamide). Neutrophil adherence was also inhibited by an inhibitor of actin polymerization, cytochalasin D and a tyrosine kinase inhibitor, genistein. Further, the PAR2-mediated tyrosine phosphorylation of focal adhesion kinase (FAK), a major cytoskeleton protein, was detected, and this response was inhibited by mevastatin or Y-27632. These results suggest that PAR2 stimulation of alveolar epithelial cells enhances neutrophil adhesion presumably at least in part through Rho/ROCK signal-mediated actin cytoskeleton reorganization associated with the tyrosine phosphorylation of FAK.

Rho GTPases in hematopoietic cells

The ubiquitous Rho GTPases are instrumental in the organization of the actin cytoskeleton, but also for the control of gene expression. Here we review the role of the major members of this family, i.e., RhoA, Rac1, Rac2, and Cdc42, and their intracellular signaling in hematopoietic cells. Although these proteins have been classically implicated in chemotaxis, there are now clear indications on how differential signaling toward other, more specific functions, such as phagocytosis or the production of reactive oxygen species, is regulated by relatively small differences in primary sequence. The identification of mutations in these GTPases or their regulators has provided novel insights in their function as well as their relevance for the development of hematological diseases.

Are Remnant-Like Particles Independent Predictors of Coronary Heart Disease Incidence?

Background— Remnant-like particles have been proposed as a new risk factor for coronary heart disease (CHD). This is the first long-term prospective investigation of the relationship between remnant-like particles and a cardiovascular disease outcome in healthy men.

Methods and Results— A cohort of 1156 Japanese-American men aged 60 to 82 from the Honolulu Heart Program was followed for 17 years. During that period 164 incident cases of CHD were identified. In multivariate Cox regression analyses, baseline remnant-like particle cholesterol (RLP-C) and triglyceride (RLP-TG) levels were significantly related to CHD incidence independently of nonlipid cardiovascular risk factors and of total cholesterol or high-density and low-density lipoprotein cholesterol levels. Total triglyceride levels were an independent predictor of CHD incidence. However, in models including RLP and triglyceride level simultaneously, neither variable was significant when adjusted for the other. This finding can be attributed to the strong correlation between RLP-C and RLP-TG levels and total triglycerides. When individuals with normal triglyceride levels (n=894) were separated from those with elevated triglycerides (n=260), the association between RLPs and CHD relative risk was only significant for the group with elevated triglyceride levels.

Conclusions— RLP levels predicted CHD incidence independently of nonlipid risk factors and of total cholesterol or high-density and low-density lipoprotein cholesterol levels. However, RLP levels did not provide additional information about CHD incidence over and above total triglyceride levels. Therefore, this study does not support the need for testing of remnants in men if measures of fasting triglycerides are available.

Atorvastatin

The introduction of statins has drastically changed the treatment and prevention of atherosclerotic vascular disease. By lowering lipid levels and reducing the risk of coronary heart disease, these drugs are among the most effective at reducing morbidity and mortality available to clinical practice. In fact, these compounds have demonstrated the reversible nature of the process of atherosclerosis and can be considered the most useful drugs we currently have in our armamentarium in the prevention of atherosclerosis and its clinical sequelae. Atorvastatin provides pronounced lipid lowering in a broad range of individuals with hypercholesterolaemia and, as such, is an appropriate first-line therapy for patients at low to high risk of coronary heart disease. Reductions in total and low-density lipoprotein cholesterol achieved with atorvastatin have been shown to translate into reductions in risk of cardiovascular morbidity and mortality in both primary and secondary prevention settings. Significant clinical benefits have specifically been observed among patients with Type 2 diabetes and in those with acute coronary syndromes. In common with other members of the statin class, atorvastatin is well tolerated, and adverse events are generally mild and transient in nature. Despite the significant clinical benefits provided by atorvastatin, its full potential in the management of atherosclerotic disease has yet to be wholly explored; however, studies currently ongoing will answer many of the outstanding questions.

Effect of remnant-like particle on shear-induced platelet activation and its inhibition by antiplatelet agents

Remnant-like particles (RLPs) have been reported to promote atherosclerosis and to have effects on platelet function. We studied the effects of RLP on shear-induced platelet activation and their inhibition by antiplatelet agents in vitro. RLP were separated using two monoclonal antibodies, anti apo B-100 and anti apo A-I. These RLP fractions were added to whole blood (WB) or platelet-rich plasma (PRP) in serial dilution of 1, 10 or 100 microg RLP triglyceride (TG) per ml of total sample volume. These samples were incubated, and then stimulated with a high shear stress of 108 dyn/cm(2). Shear-induced platelet aggregation (SIPA) was calculated from the percentage of single platelet loss. P-selectin expression on platelet surface and platelet-derived microparticle (PMP) generation were measured before and after stimulation with shear stress using flow cytometer. SIPA was significantly enhanced by RLP in WB but not in PRP. This enhancing effect was not dose-dependent and was greatest at 10 microg TG/ml. P-selectin expression induced by shear stress was only enhanced by RLP at a concentration of 100 microg TG/ml in both WB and PRP, while generation of PMP induced by shear stress was only enhanced by RLP at a concentration of 100 microg TG/ml in WB. Aspirin inhibited only the enhancement of SIPA by RLPs, while cilostazol inhibited the enhancement of not only SIPA but also p-selectin expression and PMP generation by RLPs.

Lipid and non-lipid effects of statins

Long- and short-term trials with the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) have demonstrated significant reductions in cardiovascular events in patients with and without history of coronary heart disease. Statins are well-established low-density lipoprotein (LDL)-lowering agents, but their clinical benefit is believed to result from a number of lipid and non-lipid effects beyond LDL lowering, including a rise in plasma high-density lipoprotein levels. Beyond improving the lipid profile, statins have additional non-lipid effects including benefit on endothelial function, inflammatory mediators, intima-media thickening, prothombotic factors that ultimately result in plaque stabilization. These effects arise through the inhibition of several mevalonate-derived metabolites other than cholesterol itself, which are involved in the control of different cellular functions. Although statins represent the gold standard in the prevention and treatment of coronary heart disease, combination therapy with other lipid-lowering drugs, as well as novel therapeutic indications, may increase their therapeutic potential.