Atherosclerosis is an inflammatory disease

The relation of severity of depressive symptoms to monocyte-associated proinflammatory cytokines and chemokines in apparently healthy men

OBJECTIVE

We examined the relation of severity of depressive symptoms to lipopolysaccharide-stimulated expression of monocyte-associated proinflammatory cytokines and chemokines in 53 nonsmoking, healthy men.

METHODS

Assessments of cytokine and chemokine expression and severity of depressive symptoms were conducted on the same day. The 21-item Beck Depression Inventory (BDI) was used to assess severity of depressive symptoms experienced during the week before study participation. Dual-color flow cytometry was used to determine monocyte-associated (CD14+) expression of interleukin-1alpha (IL-1alpha), IL-1beta, tumor necrosis factor-alpha (TNF-alpha), IL-8, and monocyte chemotactic protein-1 (MCP-1) after in vitro lipopolysaccharide stimulation of undiluted whole blood.

RESULTS

Calculations of partial correlation coefficients controlling for age, race, body mass index, and alcohol use indicated that BDI score was significantly associated with IL-1alpha (r = 0.27), IL-1beta (r = 0.44), TNF-alpha (r = 0.57), MCP-1 (r = 0.52), and IL-8 (r = 0.33). In addition, relative to men with BDI scores below 10, men with BDI scores of 10 or above exhibited an overexpression of IL-1beta (p =.004), TNF-alpha (p =.005), IL-8 (p =.002), and MCP-1 (p =.025).

CONCLUSIONS

Relative to men with no or minimal symptoms of depression, men with mild to moderate levels of depressive symptoms showed overexpression of monocyte-associated proinflammatory cytokines and chemokines.

Endothelium-dependent effects of statins

The vascular endothelium is a dynamic endocrine organ that regulates contractile, secretory, and mitogenic activities in the vessel wall and hemostatic processes within the vascular lumen. Risk factors for cardiovascular disease, such as cigarette smoking, hypertension, and elevated serum lipid levels, impair endothelial function and lead to the development of atherosclerotic vessels. Recent studies suggest that statins reduce cardiovascular events in part by improving endothelial function. Statins reduce plasma cholesterol levels, thereby decreasing the uptake of modified lipoproteins by vascular wall cells. There is increasing evidence, however, that statins may also exert effects beyond cholesterol lowering. Indeed, many of these cholesterol-independent or "pleiotropic" vascular effects of statins appear to involve restoring or improving endothelial function through increasing the bioavailability of nitric oxide, promoting re-endothelialization, reducing oxidative stress, and inhibiting inflammatory responses. Thus, the endothelium-dependent effects of statins are thought to contribute to many of the beneficial effects of statin therapy in cardiovascular disease.

BMP-2 inhibits proliferation of human aortic smooth muscle cells via p21Cip1/Waf1

Bone-morphogenetic proteins (BMP)-2 and -7, multifunctional members of the transforming growth factor (TGF)-beta superfamily with powerful osteoinductive effects, cause cell cycle arrest in a variety of transformed cell lines by activating signaling cascades that involve several cyclin-dependent kinase inhibitors (CDKIs). CDKIs in the cip/kip family, p21(Cip1/Waf1) and p27(Kip1), have been shown to negatively regulate the G1 cyclins and their partner cyclin-dependent kinase proteins, resulting in BMP-mediated growth arrest. Bone morphogens have also been associated with antiproliferative effects in vascular tissue by unknown mechanisms. We now show that BMP-2-mediated inhibition of platelet-derived growth factor (PDGF)-stimulated human aortic smooth muscle cell (HASMC) proliferation is accompanied by increased levels of p21 protein. Antisense oligodeoxynucleotides specific for p21 attenuate BMP-2-induced inhibition of proliferation when transfected into HASMCs, demonstrating that BMP-2 inhibits PDGF-stimulated proliferation of HASMCs through induction of p21. Whether p21-mediated induction of cell cycle arrest by BMP-2 sets the stage for osteogenic differentiation of vascular smooth muscle cells, ultimately leading to vascular mineralization, remains to be investigated.

Evidence for enhanced 8-isoprostane plasma levels, as index of oxidative stress in vivo, in patients with coronary artery disease

BACKGROUND

It is well known that free radicals contribute to endothelial dysfunction and are involved in ageing and in the pathogenesis and development of many cardiovascular diseases, such as atherosclerosis. Measurement of F(2)-isoprostanes has emerged as probably the most reliable approach to assess oxidative stress status in vivo. In particular, 8-isoprostane (8-epiPGF(2alpha)) has been indicated as a marker of antioxidant deficiency and oxidative stress of potential relevance to assess human vascular diseases.

DESIGN

To provide evidence for enhanced oxidative stress in coronary artery disease (CAD).

METHODS

Plasma levels of 8-epiPGF(2alpha) (EIA, Cayman Chemicals, Ann Arbor, Michigan, USA) were measured in 51 patients (19 females, 32 males, age: 58.7+/-1.6 years, mean+/-SEM). Subjects included 13 healthy control subjects (group I), and 38 patients underwent coronary angiography; 11 patients without coronary artery atherosclerotic lesions (group II), and 27 with angiographically proven CAD (group III).

RESULTS

Plasma levels of 8-epiPGF(2alpha) were 123.2+/-9.5, 314.6+/-40 and 389.6+/-36.2 pg/ml in groups I, II and III respectively (P<0.05 and P<0.001 groups II and III versus group I, respectively). In group III, 8-epiPGF(2alpha) levels increased with the number of affected vessels (324.4+/-47.2 and 408.3+/-44.1 pg/ml for one- and multi-vessel disease, P=0.07 and P<0.001 versus control subjects, respectively). A significant difference in 8-epiPGF(2alpha) levels was observed between patients with and without hypertension (394.2+/-42.7 and 232.7+/-25.1 pg/ml, P<0.01, respectively). In addition, patients with dyslipidaemia presented higher 8-epiPGF(2alpha) levels with respect to non-dyslipidaemic patients (359.1+/-35.6 and 240.3+/-34.3 pg/ml, P<0.05, respectively). A positive relationship was found between age and 8-epiPGF(2alpha) levels (r=0.42, P<0.01) in the whole population.

CONCLUSION

These findings indicate that elevated levels of plasma 8-epiPGF(2alpha) levels are associated with the extent and the severity of coronary artery disease and with the occurrence of different atherogenic risk factors, supporting the hypothesis that the evaluation of oxidative stress may represent an additional prognostic predictor in such events and a potential target of future therapeutic interventions.

The -308 G/A tumor necrosis factor-alpha gene dimorphism: a risk factor for unstable angina

Since the inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) may play a major role in the pathophysiology of acute coronary syndromes, 299 consecutive male patients hospitalized for coronary artery disease (i.e., lumen lost > or = 50%) were genotyped for the functional -308G/A TNF-alpha polymorphism using restriction fragment length polymorphism method, in order to evaluate its potential association with the risk of unstable angina and/or myocardial infarction. A higher frequency of carriers of the A allele was observed in patients with unstable angina (n = 58) when compared to control patients with stable angina (n = 95) (39.66% vs. 23.16% respectively, p = 0.029, odds ratio = 2.2) but not in patients with myocardial infarction (n = 146) (23.97% vs. 23.16%, p = NS). Furthermore, we evidenced an interaction of the polymorphism studied with body mass index in patients with unstable angina. Thus, when stratified analysis was performed, results in patients with a body mass index < or = 27 showed a more striking association between A allele carriage frequency and unstable angina (p = 0.012, odds ratio = 3.0). These results suggest the crucial role of TNF-alpha in the mechanisms responsible for unstable angina in accordance with the concept of vulnerable plaque. On the other hand, mechanisms controlling myocardial infarction appear more complex and heterogeneous.

C-reactive protein and procalcitonin as markers of mortality in hemodialysis patients: a 2-year prospective study

OBJECTIVE

We have previously shown in a transversal study that PCT combined to CRP is associated to an altered nutritional status in hemodialysis patients. In a 2-year prospective study, we have assessed the relationship between markers of inflammation or nutrition and mortality.

DESIGN

Two-year prospective study, in 61 patients dialyzed in our unit (29 M/32 F, age 63 +/- 15 years, on dialysis for 76 +/- 94 months, 12 hrs/wk, on high-flux (HF) membrane for 25 patients and low-flux (LF) for 36 patients, without reuse). Kt/V was 1.53 +/- 0.30.

SETTING

Hospital-based dialysis unit.

MAIN OUTCOME MEASURE

CRP, PCT, ferritin, albumin, and prealbumin, were measured in 04/99 (T0) and every 6 months thereafter. Interleukin-6 (IL6) and fibrinogen were measured at the start of study. The outcome and the causes of death of patients were noted in 58 patients, 3 patients were lost of follow-up.

RESULTS

The mortality (24 deaths) was 42% at 2 years in this hospital based unit. The main causes of mortality were cardiovascular diseases (71%) and infection (17%). Patients were classified according to their CRP (CRP+ if CRP > or = 5 mg/L; n = 40), and PCT values (PCT + if PCT > or = 0.5 ng/mL; n = 25). IL6 level was > or = 10 pg/mL for 95% of the patients. Mortality was higher in the CRP+ group (Kaplan-Meier test P < .01) but not in the PCT or IL6 positive patients. All patients of the CRP+ group at T0 remained CRP+. Only 56% of patients of PCT+ remained positive at 6 months. When patients were grouped according to CRP quartile the difference on survival remained significant (P = .03), patients who were classified in the third and fourth quartile (upper than 9.9 mg/L), exhibited a higher rate of mortality than the lower quartile. The concomitant presence of a high level of PCT and CRP was associated with a worsened nutritional status at T0 but PCT level had no influence on 2-year mortality.

CONCLUSION

In this 2-year prospective study in a hospital-based cohort of high-risk hemodialysis patients, elevated CRP, but not raised PCT, was associated with increased mortality. Inflammation remained present throughout a 2-year follow-up in patients with an initial CRP higher than 5 mg/L. An upper value of CRP above 9.9 mg/L is independly predictive of mortality, mainly from cardiovascular causes. The association of high PCT and CRP was no more predictive of mortality than high CRP.

Vascular MRI in the diagnosis and therapy of the high risk atherosclerotic plaque

Disruption of a high risk plaque is known as the primary cause of cardiovascular events. Characterization of arterial wall components has become an essential adjunct in the identification of patients with plaques prone to rupture. Magnetic Resonance Imaging (MRI) has been revealed as one of the noninvasive tools possibly capable of identifying and characterizing high risk atherosclerotic plaque. MRI may facilitate diagnosis, and guide and serially monitor interventional and pharmacological treatment of atherosclerotic disease. In addition, it permits the simultaneous assessment of the anatomy, morphology, and hemodynamics for the study of flow-induced atherogenesis. It possibly will identify asymptomatic patients with subclinical atherosclerosis. This has potential significance for the improvement of strategies in primary and secondary prevention.

Identification of differentially expressed genes in coronary atherosclerotic plaques from patients with stable or unstable angina by cDNA array analysis

The composition of atherosclerotic plaques is a crucial factor in determining rupture, thrombosis and clinical events. In this study, we analyzed gene expression in coronary plaques from patients with stable or unstable angina using gene arrays. Total RNA was extracted from eight plaques collected by therapeutic directional coronary atherectomy. cDNA probes, generated by amplification, were hybridized to nylon arrays containing 482 genes. Here we report the results for the inflammation, adhesion and hemostasis subsets. Many genes not previously associated with atherosclerosis, such as the lymphocyte adhesion molecule MadCAM, were expressed in the plaques. anova analysis showed higher tissue factor (TF) expression in unstable angina samples. Five genes were expressed at lower levels in unstable angina samples: anticoagulant protein S, cyclooxygenase (COX)-1, interleukin (IL)-7 and chemokines monocyte chemotactic protein (MCP)-1 and -2. Gene arrays provide a new approach to study plaque composition and identify candidate markers of plaque instability.

Chemical regulation of nitric oxide: a role for intracellular myoglobin?

The detailed chemistry of nitric oxide (*NO) and regulation of this potent signal molecule through interactions with cellular components are complex and not clearly understood. In the vasculature, *NO plays a crucial role in vessel dilation by activating soluble guanylyl cyclase (sGC) in vascular smooth muscle cells (VSMC). *NO is responsible for maintaining coronary blood flow and normal cardiac function. However, *NO is a highly reactive molecule and this reactivity toward a range of alternate substrates may interfere with the activation of its preferred molecular target within VSMC. Interestingly, marked changes to *NO homeostasis are linked to disease progression. Thus, the physiological concentration of *NO is carefully regulated. Myoglobin is a haem-containing protein that is present in relatively high concentration in cardiac and skeletal muscle. Recently, the presence of myoglobin has been confirmed in human smooth muscle. The role of intracellular myoglobin is generally accepted as that of a passive di-oxygen storage protein. However, oxygenated myoglobin readily reacts with *NO to yield higher order N-oxides such as nitrate, while both the ferrous and ferric forms of the protein form a stable complex with *NO. Together, these two reactions effectively eliminate *NO on the physiological time-scale and strongly support the idea that myoglobin plays a role in maintaining *NO homeostasis in tissues that contain the protein. Interestingly, human myoglobin contains a sulfhydryl group and forms an S-nitroso-adduct similar to haemoglobin. In this article we discuss the potential for human myoglobin to actively participate in the regulation of *NO by three distinct mechanisms, namely oxidation, ligand binding, and through formation of biologically active S-nitroso-myoglobin.

PPARdelta is a very low-density lipoprotein sensor in macrophages

Although triglyceride-rich particles, such as very low-density lipoprotein (VLDL), contribute significantly to human atherogenesis, the molecular basis for lipoprotein-driven pathogenicity is poorly understood. We demonstrate that in macrophages, VLDL functions as a transcriptional regulator via the activation of the nuclear receptor peroxisome proliferator-activated receptor delta. The signaling components of native VLDL are its triglycerides, whose activity is enhanced by lipoprotein lipase. Generation of peroxisome proliferator-activated receptor delta null macrophages verifies the absolute requirement of this transcription factor in mediating the VLDL response. Thus, our data reveal a pathway through which dietary triglycerides and VLDL can directly regulate gene expression in atherosclerotic lesions.

Viral and bacterial DNA in carotid atherosclerotic lesions

Atherosclerosis is a major health problem in industrialised countries. Several studies have suggested an association exists between certain microorganisms and the development of atherosclerosis. The aim of the study presented here was to assess the presence of viral or bacterial DNA in carotid atherosclerotic lesions. Nucleic acids were extracted from 18 carotid atherosclerotic lesions that had been collected surgically. Polymerase chain reaction was used to screen for specific genomic DNA from Chlamydia pneumoniae, cytomegalovirus and herpes simplex virus types 1 and 2. An original approach, based on the amplification by PCR of conserved bacterial 16S rDNA nucleotide sequences was also used to detect any bacterial species. The amplification product was identified by sequencing. Chlamydia pneumoniae, cytomegalovirus and herpes simplex 2 DNA were not detected in any of the samples. Herpes simplex 1 DNA was detected in 3 of the 18 samples. Genes encoding bacterial 16S rRNA were amplified and sequenced in eight atherosclerotic lesions. DNA sequences were identified by comparison with sequences registered in the GenBank database. These eight carotid atherosclerotic lesions were shown to contain several bacterial species belonging to human flora or the environment. The exact role of these microorganisms in the genesis or development of the atherosclerotic lesions remains unclear, but they may increase the inflammatory process or be an epiphenomenon.

Fetal plasma stimulates endothelial cell production of cytokines and the family of suppressor of cytokine signaling in umbilical placental vascular disease

OBJECTIVE

We have shown that fetal plasma from pregnancies with placental vascular disease that were identified by an abnormal umbilical artery Doppler study causes endothelial cell activation. We investigated the hypothesis that this would be associated with endothelial cell production of cytokines and their natural regulators, the suppressor of cytokine signaling family. Activation of suppressor of cytokine signaling at the time of cytokine release confirms the fact that cytokine production is occurring in a stimulated cell.

STUDY DESIGN

Aliquots from a common culture of human umbilical vein endothelial cells were incubated with fetal plasma from normal pregnancy (n = 29 pregnancies), from umbilical placental vascular disease defined by abnormal umbilical artery Doppler waveforms (n = 38 pregnancies), and from preeclampsia with normal umbilical artery Doppler scans (n = 10 pregnancies). The expression of messenger RNA for the cytokines interleukin-6 and interleukin-8 and the members of suppressor of cytokine signaling family (cytokine-inducible SH2-containing protein, suppressor of cytokine signaling 1, 2, and 3) were assessed by reverse transcriptase-polymerase chain reaction.

RESULTS

Endothelial cell expression of interleukin-6 messenger RNA (1.94 +/- 0.24 vs 1.31 +/- 0.16) and interleukin-8 messenger RNA (2.62 +/- 0.33 vs 1.64 +/- 0.22) were enhanced in response to incubation with fetal plasma from placental vascular disease in comparison to incubation with fetal plasma from normal pregnancy. The messenger RNA expression of suppressor of cytokine signaling-2 (2.03 +/- 0.23 vs 1.37 +/- 0.16) was up-regulated significantly in placental vascular disease. Differences for cytokine-inducible SH2-containing protein, suppressor of cytokine signaling-1, and suppressor of cytokine signaling-3 were not significant. The expression of cytokines and the suppressor of cytokine signaling family did not differ from normal in the group with maternal preeclampsia and a normal umbilical study. Interestingly, in the umbilical placental vascular disease group, the results were similar in the subgroups, with or without preeclampsia in the mother.

CONCLUSION

We have shown that factors that cause endothelial cell injury are present in the fetal circulation in umbilical placental vascular disease. This study is the first report of cytokine production and release and activation of the suppressor of cytokine signaling family by endothelial cells in response to fetal plasma in placental vascular disease. The role of all members of the suppressor of cytokine signaling family in this process must be investigated further. The fact that both the agonist (cytokines) and the antagonist (suppressor of cytokine signaling-2) are produced points to a significant role of endothelial cells in this disease.

Carvedilol modulates in-vitro granulocyte-macrophage colony-stimulating factor-induced interleukin-10 production in U937 cells and human monocytes

Both granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-10 (IL-10) are important mediators regulating inflammatory responses. Inflammatory processes have an important role in atherogenesis. In this paper, the effects of carvedilol on GM-CSF-induced IL-10 production were examined on human monocytic cell line, U937, and purified human monocytes. First, we showed that one-time carvedilol pretreatment at concentrations 0.3-10 microM dose-dependently inhibited GM-CSF-induced IL-10 production in U937 cells. In addition, we found carvedilol to be non-cytotoxic at concentrations equal to or less than 10 microM. However, at concentrations higher than 10 microM, carvedilol induced programmed cell death in U937 cells. The inhibition of GM-CSF-induced IL-10 production by carvedilol was also observed at the expression of mRNA. Furthermore, the inhibition of IL-10 production was demonstrated in GM-CSF-activated purified human peripheral blood monocytes. Finally, long-term carvedilol pretreatment of U937 cells up to 2 months at concentrations of 1.0 microM mildly enhanced the IL-10 production. Our observations that carvedilol modulated GM-CSF-induced IL-10 production may have some implication in understanding the broad-spectrum effects of carvedilol in regulating inflammatory reactions.

Whole grains protect against atherosclerotic cardiovascular disease

Atherosclerotic cardiovascular disease (ASCVD) is the most common cause of death in most Western countries. Nutrition factors contribute importantly to this high risk for ASCVD. Favourable alterations in diet can reduce six of the nine major risk factors for ASCVD, i.e. high serum LDL-cholesterol levels, high fasting serum triacylglycerol levels, low HDL-cholesterol levels, hypertension, diabetes and obesity. Wholegrain foods may be one the healthiest choices individuals can make to lower the risk for ASCVD. Epidemiological studies indicate that individuals with higher levels (in the highest quintile) of whole-grain intake have a 29 % lower risk for ASCVD than individuals with lower levels (lowest quintile) of whole-grain intake. It is of interest that neither the highest levels of cereal fibre nor the highest levels of refined cereals provide appreciable protection against ASCVD. Generous intake of whole grains also provides protection from development of diabetes and obesity. Diets rich in wholegrain foods tend to decrease serum LDL-cholesterol and triacylglycerol levels as well as blood pressure while increasing serum HDL-cholesterol levels. Whole-grain intake may also favourably alter antioxidant status, serum homocysteine levels, vascular reactivity and the inflammatory state. Whole-grain components that appear to make major contributions to these protective effects are: dietary fibre; vitamins; minerals; antioxidants; phytosterols; other phytochemicals. Three servings of whole grains daily are recommended to provide these health benefits.

Overexpression of p73 causes apoptosis in vascular smooth muscle cells

Abnormal vascular smooth muscle (VSM) cell proliferation contributes to the development of atherosclerosis and its associated disorders, including angioplasty restenosis. The tumor-suppressor protein p53 has been linked to the development of atherosclerotic lesions, and its homolog, p73, is proving to have contrasting functions in a variety of tissues. As an outgrowth of our previous finding that p73 is increased in serum-stimulated VSM cells and human atherosclerotic tissue, we examined p73 overexpression in VSM cells to elucidate causality of p73 expression with growth response. Overexpression of p73 results in decreased cell cycle transit and is accompanied by apoptosis. The apoptotic changes in p73 overexpressing VSM cells are independent of p53 and are associated with a decrease in levels of p21(waf1/cip1). In conjunction with our previous data finding that p73 is increased in serum-stimulated VSM cells, this work suggests a role for p73 in vascular proliferative diseases.

Effects of supplementation with fish oil-derived n-3 fatty acids and gamma-linolenic acid on circulating plasma lipids and fatty acid profiles in women

BACKGROUND

Eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and gamma-linolenic acid (GLA) have lipid-modifying and antiinflammatory properties. The effects of supplement mixtures of these fatty acids on plasma lipids and the fatty acid compositions of serum phospholipids have received little attention.

OBJECTIVE

The objective was to determine the effects of different levels of GLA supplementation together with a constant intake of EPA plus DHA on the triacylglycerol-lowering effect of EPA plus DHA alone and on the fatty acid patterns (eicosanoid precursors) of serum phospholipids.

DESIGN

Thirty-one women were assigned to 1 of 4 groups, equalized on the basis of their fasting triacylglycerol concentrations. They received supplements providing 4 g EPA+DHA (4:0, EPA+DHA:GLA; control group), 4 g EPA+DHA plus 1 g GLA (4:1), 2 g GLA (4:2), or 4 g GLA (4:4) daily for 28 d. Plasma lipids and fatty acids of serum phospholipids were measured on days 0 and 28.

RESULTS

Plasma triacylglycerol concentrations were significantly lower on day 28 than on day 0 in the 4:0, 4:1, and 4:2 groups. LDL cholesterol decreased significantly (by 11.3%) in the 4:2 group. Dihomo-gamma-linolenic acid increased significantly in serum phospholipids only in the 4:2 and 4:4 groups; however, total n-3 fatty acids increased in all 4 groups.

CONCLUSIONS

A mixture of 4 g EPA+DHA and 2 g GLA favorably altered blood lipid and fatty acid profiles in healthy women. On the basis of calculated PROCAM values, the 4:2 group was estimated to have a 43% reduction in the 10-y risk of myocardial infarction.

Vascular collagens: spotlight on the role of type VIII collagen in atherogenesis

Collagens play a central role in maintaining the integrity and stability of the undiseased as well as of the atherosclerotic vessel wall. An imbalanced metabolism may lead to uncontrolled collagen accumulation reducing vessel wall velocity, frequently resulting in arterial occlusion or thrombosis. A reduced production of collagen and its uncontrolled degradation may affect the stability of the vessel wall and especially of the atherosclerotic plaques by making them prone to rupture and aneurysm. This review presents an overview on the four groups of vascular collagens and on their role in atherogenesis. The major focus was to highlight the extraordinary role and importance of the short chain network forming type VIII collagen in the extracellular matrix of undiseased arteries and of atherosclerotic plaques. The molecular structure of type VIII collagen, its cellular origin, its implication in atherogenesis, its temporal and spatial expression patterns in human and experimental models of atherogenesis, the factors modulating its expression, and--not at least--its potential function is discussed.

Serum concentrations of elastin-derived peptides in patients with specific manifestations of atherosclerotic disease

OBJECTIVE

To measure serum concentrations of elastin-derived peptides (S-EDP) in patients with aneurysmal, occlusive and ulcerative manifestations of atherosclerotic disease.

MATERIALS AND METHODS

S-EDP concentrations were measured by a competitive enzyme-linked immunosorbent assay in 10 patients with infrarenal aneurysms 5cm in diameter (AAA), 10 patients with distal aortic occlusive disease (AOD), 10 patients with symptomatic carotid stenosis (>or=70%) and plaque ulceration (SCS) and a control group of 10 patients with no similar specific manifestations of atherosclerotic disease (NAM).

RESULTS

S-EDP concentrations (median, range) were significantly higher in patients with AAA (42ng/ml, 35-52, p<0.001) and SCS (49ng/ml, 37-60, p<0.001) but not AOD (28ng/ml, 22-38, p=0.240) compared to NAM (26ng/ml, 19-36) patients.

CONCLUSION

Increased concentrations of S-EDP were associated with aneurysmal and ulcerative, but not occlusive, manifestations of atherosclerosis.

Angiotensin II is associated with activation of NF-kappaB-mediated genes and downregulation of PPARs

Angiotensin II (ANG II) promotes vascular inflammation through nuclear factor-kappaB (NF-kappaB)-mediated induction of pro-inflammatory genes. The role of peroxisome proliferator-activated receptors (PPARs) in modulating vascular inflammation and atherosclerosis in vivo is unclear. The aim of the present study was to examine the effects of ANG II on PPARs and NF-kappaB-dependent pro-inflammatory genes in the vascular wall in an in vivo model of atherosclerosis and aneurysm formation. Six-month-old male apolipoprotein E-deficient (apoE-KO) mice were treated with ANG II (1.44 mg/kg per day for 30 days). ANG II enhanced vascular inflammation, accelerated atherosclerosis, and induced formation of abdominal aortic aneurysms. These effects of ANG II in the aorta were associated with downregulation of both PPAR-alpha and PPAR-gamma mRNA and protein and an increase in transcription of monocyte chemotactic protein-1 (MCP-1), macrophage-colony stimulating factor (M-CSF), endothelial-selectin (E-selectin), intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) throughout the entire aorta. ANG II also activated NF-kappaB with increases in both p52 and p65 NF-kappaB subunits. In summary, these in vivo results indicate that ANG II, through activation of NF-kappaB-mediated pro-inflammatory genes, promotes vascular inflammation, leading to acceleration of atherosclerosis and induction of aneurysm in apoE-KO mice. Downregulation of PPAR-alpha and -gamma by ANG II may diminish the anti-inflammatory potential of PPARs, thus contributing to enhanced vascular inflammation.

Arterial retention of apolipoprotein B(48)- and B(100)-containing lipoproteins in atherogenesis

PURPOSE OF REVIEW

The "response to retention" hypothesis of atherosclerosis suggests that the arterial deposition of cholesterol is directly proportional to the concentration of circulating plasma lipoproteins. However, there is increasing evidence to support the concept that specific lipoproteins may be preferentially retained within the arterial wall, possibly as a result of greater affinity for cell surface and extracellular matrices.

RECENT FINDINGS

Recently, key studies have provided insight into mechanisms involved in the interaction of apolipoprotein B (apoB)-containing lipoproteins with extracellular matrices. In addition, novel methods and innovative experimental design has enabled us to differentiate between the delivery, retention and efflux of apoB(48)- and apoB(100)-containing lipoproteins. Other studies have demonstrated a relationship between extracellular matrix proteoglycan expression and the development of atherosclerosis. Discussion in the present review also extends to the mechanisms that are involved in the relative intimal retention of apoB(48)- and apoB(100)-containing lipoproteins in order to explain the atherogenicity of these macromolecules.

SUMMARY

The perspective of this review is to highlight recent advances in the area of arterial lipoprotein retention and the physiological significance these processes may have in the aetiology of cardiovascular disease. Importantly, an understanding of the mechanisms responsible for the retention of apoB(48)/B(100)-containing lipoproteins will enable new strategies to be developed for the future management of cardiovascular disease.

Experimental hyperlipidemia and the effect of NSAIDs

The effects of ip administration of NSAIDs in experimentally induced hyperlipidemia in rats was studied. An isotonic solution of Triton WR1339 (tyloxapol) was administered ip to rats one hour after ip administration of the examined anti-inflammatory drug. After 24 h, blood was collected for the determination of plasma total cholesterol (TC), LDL and trigluceride (TG) concentrations. The NSAIDs used in our experimental model are selective or non selective COX-1 inhibitors as well as one non selective COX-2 inhibitor. Most of the drugs significantly reduced the TC, TG and LDL concentrations in the plasma of hyperlipidemic rats. While studies link atheromatosis to inflammation, our results potentially also link anti-inflammatory activity with hypolipidemia. Thus, NSAIDs not only may address the inflammatory aspect of atherosclerosis but also may contribute directly by inducing hypolipidemia.

High sensitivity C-reactive protein: an emerging role in cardiovascular risk assessment

Coronary heart disease (CHD) is the major cause of death in the developed world and screening for conventional cardiovascular risk factors fails to identify more than 50% of the individuals who will present with acute coronary syndromes. Chronic inflammation appears to play a significant role in the initiation and development of atherosclerosis. Recent investigations have shown an association between inflammatory markers such as C-reactive protein (CRP) and CHD. These markers have proven useful as prognostic indicators in acute coronary syndromes and in predicting future coronary events in apparently healthy men and women. The availability of high sensitivity CRP (hs-CRP) assays has been crucial in exploring the role of this acute phase reactant in primary prevention settings. In this review, we discuss the evidence associating these inflammatory markers, especially CRP, with the pathogenesis of atherosclerosis and acute coronary syndromes, and we address the mechanism of risk as well as the clinical utility of this marker.

Identification of 5-lipoxygenase as a major gene contributing to atherosclerosis susceptibility in mice

We previously reported the identification of a locus on mouse chromosome 6 that confers almost total resistance to atherogenesis, even on a hypercholesterolemic (LDL receptor-null) background. 5-Lipoxygenase (5-LO) is the rate-limiting enzyme in leukotriene synthesis and was among the chromosome 6 locus candidate genes that we examined. The levels of 5-LO mRNA were reduced about 5-fold in a congenic strain, designated CON6, containing the resistant chromosome 6 region derived from the CAST/Ei strain (CAST), as compared with the background C57BL/6J (B6) strain. 5-LO protein levels were similarly reduced in the CON6 mice. Sequencing of the 5-LO cDNA revealed several differences between CON6 and the B6 strain. To test the whether 5-LO is responsible for the resistant phenotype, we bred a 5-LO knockout allele onto an LDL receptor-null (LDLR(-/-)) background. On this background, the mice bred poorly and only heterozygous 5-LO knockout mice were obtained. These mice showed a dramatic decrease (>26-fold; P<0.0005) in aortic lesion development, similar to the CON6 mice. Immunohistochemistry revealed that 5-LO was abundantly expressed in atherosclerotic lesions of apoE(-/-) and LDLR(-/-) deficient mice, appearing to colocalize with a subset of macrophages but not with all macrophage-staining regions. When bone marrow from 5-LO(+/-) mice was transplanted into LDLR(-/-), there was a significant reduction in atherogenesis, suggesting that macrophage 5-LO is responsible, at least in part, for the effect on atherosclerosis. These results indicate that 5-LO contributes importantly to the atherogenic process and they provide strong presumptive evidence that reduced 5-LO expression is partly responsible for the resistance to atherosclerosis in CON6 mice.

Endothelial cell expression of adhesion molecules is induced by fetal plasma from pregnancies with umbilical placental vascular disease

OBJECTIVE

To test the hypothesis that local production with spill into the fetal circulation of factor(s) injurious to endothelium is responsible for the vascular pathology present when the umbilical artery Doppler study is abnormal. Expression of adhesion molecules is a feature of endothelial cell activation.

DESIGN

Case-control study.

SETTING

University teaching hospital.

SAMPLES

Fetal plasma was collected from 27 normal pregnancies, 39 pregnancies with umbilical placental vascular disease defined by abnormal umbilical artery Doppler and 11 pregnancies with pre-eclampsia and normal umbilical artery Doppler.

METHODS

Isolated and cultured human umbilical vein endothelial cells from normal pregnancies were incubated with fetal plasma from three study groups. mRNA expression of intercellular cell adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and platelet-endothelial cell adhesion molecule-1 (PECAM-1) were assessed by reverse transcription-polymerase chain reaction. To confirm the occurrence of this in vivo, we measured the levels of soluble fractions of sICAM-1, sVCAM-1 and sPECAM-1 in the fetal circulation in the fetal plasma used for endothelial cell incubation.

RESULTS

The mRNA expression of ICAM-1 [median 1.1 (interquartile range 0.5-1.9) vs 0.7 (0.3-1.2), P < 0.05] and PECAM-1 [2.1 (1.2-3.0) vs 1.5 (0.7-2.1), P < 0.05] was significantly higher following incubation with fetal plasma from umbilical placental vascular disease compared with the normal group. There was no difference in the expression of VCAM-1 [1.2 (0.9-1.8) vs 1.1 (0.8-1.6), ns]. The group with maternal pre-eclampsia and normal umbilical artery Doppler did not differ from the normal group. In the umbilical placental vascular disease group, the results were similar in the presence or absence of pre-eclampsia. For soluble fractions of the adhesion molecules released into the fetal circulation, we found the levels (ng/mL) of sICAM- I [median 248.5 (interquartile range 197.3-315.7) vs 174.2 (144.5-212.9), P < 0.05] and sPECAM-1 [9.3 (6.2-11.1) vs 6.1 (5.4-7.7), P < 0.05] in fetal plasma to be significantly increased in the presence of umbilical placental vascular disease compared with the normal.

CONCLUSIONS

Vascular disease in the fetal umbilical placental circulation is associated with an elevation in mRNA expression by endothelial cells of ICAM-1 and PECAM-1. Our study provides evidence for endothelial cell activation and dysfunction in umbilical placental vascular disease. We speculate that the plasma factor(s) affecting the vessels of the umbilical villous tree is locally released by the trophoblast. The occurrence of the maternal syndrome of pre-eclampsia appears to be independent of this.

Effect of Atorvastatin and Fish Oil on Plasma High-Sensitivity C-Reactive Protein Concentrations in Individuals with Visceral Obesity

Background: Chronic low-grade inflammation may contribute to the increased risk of atherosclerosis in visceral obesity. Statin and fish oil have been reported to have antiinflammatory effects. We studied whether dyslipidemic, obese individuals have increased plasma high-sensitivity C-reactive protein (hs-CRP) concentrations and whether treatment with atorvastatin and fish oil lowered plasma hs-CRP concentrations.

Methods: We compared plasma hs-CRP, interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) concentrations in 48 obese individuals with the concentrations in 10 lean normolipidemic men. The obese individuals were then randomized to treatment with atorvastatin (40 mg/day), fish oil (4 g/day), atorvastatin plus fish oil, or matching placebo for 6 weeks.

Results: Compared with controls, obese individuals had increased hs-CRP [geometric mean, 2.19 mg/L (95% confidence interval, 2.15–3.15 mg/L) vs 0.49 mg/L (0.30– 0.93 mg/L); P &lt;0.001] and IL-6 [351 pg/L (318–449 pg/L) vs 251 pg/L (211–305 pg/L); P &lt;0.01]. Atorvastatin treatment had a significant main effect of decreasing plasma hs-CRP (−0.87 mg/L; 95% confidence interval, −0.10 to −1.60 mg/L; P &lt;0.01) and IL-6 (−70 pg/L; 10 to −140 pg/L; P &lt;0.01), but this was not seen with fish oil. The reductions in hs-CRP with atorvastatin were not significantly correlated to changes in plasma lipids, IL-6, insulin resistance, or cholesterogenesis. Plasma TNF-α concentrations in obese individuals, however, were neither statistically different from concentrations in the lean controls nor altered with atorvastatin or fish oil treatment.

Conclusions: This study shows that visceral obesity is associated with increased plasma hs-CRP and IL-6 and, hence, a low-grade chronic inflammatory state and that treatment with atorvastatin or atorvastatin with fish oil, but not fish oil alone, reverses this abnormality.

Chlamydia pneumoniae infection induces differentiation of monocytes into macrophages

Migration and differentiation of monocytes to the intima of blood vessels may be a crucial first step in the development of atherosclerosis associated with Chlamydia (Chlamydophila) pneumoniae. However, the involvement of C. pneumoniae infection in such steps is not clear. In the present study, therefore, the differentiation-inducing activity of C. pneumoniae to monocytes was examined. Human THP-1 monocytic cell line cells were infected with C. pneumoniae, and the differentiation of monocytes to macrophages was assessed by cell morphology, phagocytic activity, and expression of a cell surface adhesion molecule. The monocytic cells infected with viable bacteria markedly differentiated into macrophages associated with diffused cell morphology, increased uptake of polystyrene beads and increased ICAM-1 (intercellular adhesion molecule 1) expression on the cell surfaces. Heat-killed bacteria did not induce any morphological changes or increase of phagocytosis, but they did induce an increase of cell surface ICAM-1 expressions in THP-1 monocytic cells. The antibiotic minocycline treatment of infected cells resulted in marked inhibition of the cell differentiation as well as C. pneumoniae growth in the cells, but not ICAM-1 expression. In addition, the experiments with human peripheral blood monocytes infected with C. pneumoniae also showed the differentiation of macrophages assessed by morphological change and phagocytic activity. These results indicate that C. pneumoniae infection may directly induce the differentiation of monocytes to macrophages. However, antigenic stimulation of monocytes with bacteria may not be sufficient for a full macrophage differentiation.

Nucleotide receptors involved in UTP-induced rat arterial smooth muscle cell migration

Many factors have been shown to be involved in the development of hyperplasic lesions of vessels, but the role of extracellular nucleotides remains largely unknown. The presence of P2Y and P2X nucleotide receptors on arterial endothelial and smooth muscle cells suggests a potential role for nucleotides in the vessel pathophysiology. Although the role of P2X in physiology of vessels is well documented, that of P2Y is not completely understood. We recently demonstrated that extracellular nucleotides, and particularly UTP, induced migration of cultured arterial smooth muscle cells (ASMCs). This migration is dependent on osteopontin expression and involves the Rho and mitogen-activated protein (MAP) kinase pathways. An important question is to determine the specific role of the different P2Y receptors of rat ASMCs in the UTP-induced migration process. Therefore, we first quantified mRNA levels of P2Y(2), P2Y(4), and P2Y(6) nucleotide receptors in cultured rat ASMCs by a competitive RT-PCR approach and demonstrated that P2Y(2) is the most highly expressed among these receptors potentially involved in the UTP-mediated response. In addition to UTP, UDP also induced ASMC migration even when UTP regeneration was inhibited, suggesting the involvement of UDP receptor P2Y(6). Moreover, suramin, a specific antagonist of rat P2Y(2) receptor, acted as an inhibitor of UTP-induced migration. Taken together, these results suggest a prominent role for the UTP receptor, P2Y(2), and for the UDP receptor, P2Y(6), in UTP-induced rat ASMC migration.

Role of monocytes and macrophages in adult angiogenesis: a light at the tunnel's end

In spite of sustained efforts, there are still gaps in our understanding of angiogenesis as it takes place in vivo. Older observations and a number of recent developments strongly involve the blood mononuclear cell population, collectively known as monocytes (MC), in the normal and pathological adult angiogenesis. An emerging paradigm should eventually incorporate the established biochemical cross talk between MC and their descendents, tissular macrophages (Mph), and the endothelial cells (EC); additionally, it should account for both the intercellular cooperation at the morphological level and the phenotypic overlap between the two cell populations. This focused review puts together the pieces of this puzzle in such a way as to suggest an alternative angiogenic model applicable to adult animals, and particularly to pathological conditions. A working hypothesis is put forward, which is centered on the preformation of capillary lumen as a "tunnel" drilled by penetrating MC/Mph. The tunnels may be colonized in a later stage by sprouts, circulating progenitor endothelial cells (CPEC) or transdifferentiated EC. Thus, MC/Mph are suggested to be included among the targets of therapeutic manipulation of angiogenesis.

Chronic infections and atherosclerosis/thrombosis

An emerging pathophysiologic paradigm implicates chronic inflammation in the initiation, progression, and destabilization of atherosclerotic vascular disease. Various potential contributors to the inflammatory response in the vessel wall include atherogenic lipids, mechanical stress and injury, hypertension and angiotensin II, cigarette smoking, immune response to neoantigens, and chronic infections with viruses and or bacteria (Table 1). The potential link between chronic infection and atherosclerosis/thrombosis is under extensive investigation in several laboratories around the world. Although indirect evidence and experimental data tend to support this link, definitive proof is still lacking. If such a link is eventually proven to be causal in nature, it will provide a novel target for preventive and therapeutic strategies (anti-infective drugs, vaccines, etc.) against a common disease that is the leading killer of people in Western nations. Results of ongoing, large-scale clinical trials are eagerly awaited.

Inhibitors of soluble epoxide hydrolase attenuate vascular smooth muscle cell proliferation

Atherosclerosis, in its myriad incarnations the foremost killer disease in the industrialized world, is characterized by aberrant proliferation of vascular smooth muscle (VSM) cells in part as a result of the recruitment of inflammatory cells to the blood vessel wall. The epoxyeicosatrienoic acids are synthesized from arachidonic acid in a reaction catalyzed by the cytochrome P450 system and are vasoactive substances. Metabolism of these compounds by epoxide hydrolases results in the formation of compounds that affect the vasculature in a pleiotropic manner. As an outgrowth of our observations that urea inhibitors of the soluble epoxide hydrolase (sEH) reduce blood pressure in spontaneously hypertensive rats as well as the findings of other investigators that these compounds possess antiinflammatory actions, we have examined the effect of sEH inhibitors on VSM cell proliferation. We now show that the sEH inhibitor 1-cyclohexyl-3-dodecyl urea (CDU) inhibits human VSM cell proliferation in a dose-dependent manner and is associated with a decrease in the level of cyclin D1. In addition, cis-epoxyeicosatrienoic acid mimics the growth-suppressive activity of CDU; there is no evidence of cellular toxicity or apoptosis in CDU-treated cells when incubated with 20 microM CDU for up to 48 h. These results, in light of the antiinflammatory and antihypertensive properties of these compounds that have been demonstrated already, suggest that the urea class of sEH inhibitors may be useful for therapy for diseases such as hypertension and atherosclerosis characterized by exuberant VSM cell proliferation and vascular inflammation.

Association of postmenopausal hormone replacement therapy with carotid atherosclerosis and soluble thrombomodulin: the vascular aging (EVA) study. Etude du Vieillissement Artériel

Hormone replacement therapy (HRT) may reduce atherosclerosis among postmenopausal women, partly by reducing vascular endothelium damage. We have tested this hypothesis by evaluating the association of HRT with firstly, carotid intima media thickness (IMT) and plaques, and secondly, with endothelial cell damage, indicated by soluble thrombomodulin (sTM). Then, we tested the association between the two markers of atherosclerosis and the levels of sTM. Among 747 postmenopausal women included into the EVA study, we compared 154 HRT users (including 80% transdermal treatment) with 593 never users. Carotid IMT and plaques were measured with B-mode ultrasonography and sTM with ELISA. At least one plaque was detected among 13.6% of HRT users and 27.3% of never users. After adjustment for confounding factors, the odds ratio for the presence of plaque was 0.45 (95% confidence interval, 0.25-0.78, P=0.005) in HRT users in comparison with nonusers. HRT users had a slightly lower crude mean IMT than nonusers, but the difference was not significant. sTM was positively associated with mean IMT (P for trend=0.001) but not with plaques. Finally, estrogen users had a lower sTM level than nonusers (difference 0.14 ng/ml, P=0.03). As HRT was associated with sTM and plaques, but not with IMT, while sTM was only associated with IMT, our hypothesis was not confirmed. This suggests that the possible beneficial effects of HRT on atherosclerosis may not go through the endothelial cell damage assessed by plasma thrombomodulin.

IFN-gamma pretreatment augments immune complex-induced matrix metalloproteinase-1 expression in U937 histiocytes

We reported recently that immune complexes (ICs) induced matrix metalloproteinase-1 (MMP-1) expression in U937 histiocytes. The present study was undertaken to determine the effect of pretreatment of U937 cells with interferon-gamma (IFN-gamma) on IC-induced MMP-1 expression. Our flow cytometry studies showed that IFN-gamma upregulated the surface expression of FcgammaRI, but not FcgammaRII. Results also showed that pretreatment of the cells with IFN-gamma augmented LDL-containing IC (LDL-IC)-induced MMP-1 secretion in a dose- and time-dependent manner. Furthermore, Northern blot analysis revealed that IFN-gamma pretreatment led to a marked increase in MMP-1 mRNA. Finally, we demonstrated that PD98059 was able to block LDL-IC-induced MMP-1 secretion, regardless of whether the cells were pretreated with IFN-gamma or not, suggesting that IFN-gamma pretreatment did not alter the essential role of the ERK signaling pathway in LDL-IC-induced MMP-1 expression. In conclusion, the present study has demonstrated that IFN-gamma pretreatment augments LDL-IC-induced MMP-1 expression in U937 cells, thus elucidating an immune mechanism potentially involved in plaque destabilization.

Chlamydial heat shock protein 60 activates macrophages and endothelial cells through Toll-like receptor 4 and MD2 in a MyD88-dependent pathway

Active inflammation and NF-kappaB activation contribute fundamentally to atherogenesis and plaque disruption. Accumulating evidence has implicated specific infectious agents including Chlamydia pneumoniae in the progression of atherogenesis. Chlamydial heat shock protein 60 (cHSP60) has been implicated in the induction of deleterious immune responses in human chlamydial infections and has been found to colocalize with infiltrating macrophages in atheroma lesions. cHSP60 might stimulate, enhance, and maintain innate immune and inflammatory responses and contribute to atherogenesis. In this study, we investigated the signaling mechanism of cHSP60. Recombinant cHSP60 rapidly activated NF-kappaB in human microvascular endothelial cells (EC) and in mouse macrophages, and induced human IL-8 promoter activity in EC. The inflammatory effect of cHSP60 was heat labile, thus excluding a role of contaminating LPS, and was blocked by specific anti-chlamydial HSP60 mAb. In human vascular EC which express Toll-like receptor 4 (TLR4) mRNA and protein, nonsignaling TLR4 constructs that act as dominant negative blocked cHSP60-mediated NF-kappaB activation. Furthermore, an anti-TLR4 Ab abolished cHSP60-induced cellular activation, whereas a control Ab had no effect. In 293 cells, cHSP60-mediated NF-kappaB activation required both TLR4 and MD2. A dominant-negative MyD88 construct also inhibited cHSP60-induced NF-kappaB activation. Collectively, our results indicate that cHSP60 is a potent inducer of vascular EC and macrophage inflammatory responses, which are very relevant to atherogenesis. The inflammatory effects are mediated through the innate immune receptor complex TLR4-MD2 and proceeds via the MyD88-dependent signaling pathway. These findings may help elucidate the mechanisms by which chronic asymptomatic chlamydial infection contribute to atherogenesis.

Unsaturated fatty acids selectively induce an inflammatory environment in human endothelial cells

BACKGROUND

Activation of the vascular endothelium by dietary fatty acids may be among the most critical early events in the development of atherosclerosis. However, the specific effects of fatty acids on inflammatory responses in endothelial cells are not fully understood.

OBJECTIVE

The present study focused on the induction of inflammatory genes in human endothelial cells exposed to individual dietary fatty acids. Because of the significance of nuclear factor kappaB (NF-kappaB) and activator protein 1 (AP-1) in the regulation of inflammatory gene expression, we also determined the effects of fatty acids on NF-kappaB and AP-1 transcriptional activation.

DESIGN

Human umbilical vein endothelial cells were exposed to dietary mono- and polyunsaturated 18-carbon fatty acids. Transcriptional activation of NF-kappaB and AP-1 was determined in human umbilical vein endothelial cells transfected with reporter constructs regulated by these transcription factors. Induction of the inflammatory genes was studied by use of reverse transcriptase-polymerase chain reaction.

RESULTS

Of the fatty acids studied, linoleic acid stimulated NF-kappaB and AP-1 transcriptional activation the most. In addition, treatment with this fatty acid markedly enhanced messenger RNA levels of tumor necrosis factor alpha, monocyte chemoattractant protein 1, vascular cell adhesion molecule 1, and intercellular adhesion molecule 1. Treatment with linolenic acid stimulated only a moderate induction of the genes encoding for these inflammatory mediators, and exposure to oleic acid either had no effect or resulted in decreased inflammatory gene messenger RNA. In addition, exposure to both linoleic and linolenic acids strongly stimulated induction of the phospholipid hydroperoxide glutathione peroxidase gene.

CONCLUSION

Specific unsaturated dietary fatty acids, particularly linoleic acid, can selectively stimulate the development of a proinflammatory environment within the vascular endothelium.

Toll-like receptor-4 is expressed by macrophages in murine and human lipid-rich atherosclerotic plaques and upregulated by oxidized LDL

BACKGROUND

Inflammation is implicated in atherogenesis and plaque disruption. Toll-like receptor 2 (TLR-2) and TLR-4, a human homologue of drosophila Toll, play an important role in the innate and inflammatory signaling responses to microbial agents. To investigate a potential role of these receptors in atherosclerosis, we assessed the expression of TLR-2 and TLR-4 in murine and human atherosclerotic plaques.

METHODS AND RESULTS

Aortic root lesions of high-fat diet-fed apoE-deficient mice (n=5) and human coronary atherosclerotic plaques (n=9) obtained at autopsy were examined for TLR-4 and TLR-2 expression by immunohistochemistry. Aortic atherosclerotic lesions in all apoE-deficient mice expressed TLR-4, whereas aortic tissue obtained from control C57BL/6J mice showed no TLR-4 expression. All 5 lipid-rich human plaques expressed TRL-4, whereas the 4 fibrous plaques and 4 normal human arteries showed no or minimal expression. Serial sections and double immunostaining showed TLR-4 colocalizing with macrophages both in murine atherosclerotic lesions and at the shoulder region of human coronary artery plaques. In contrast to TLR-4, none of the plaques expressed TLR-2. Furthermore, basal TLR-4 mRNA expression by human monocyte-derived macrophages was upregulated by ox-LDL in vitro.

CONCLUSIONS

Our study demonstrates that TLR-4 is preferentially expressed by macrophages in murine and human lipid-rich atherosclerotic lesions, where it may play a role to enhance and sustain the innate immune and inflammatory responses. Moreover, upregulation of TLR-4 in macrophages by oxidized LDL suggests that TLR-4 may provide a potential pathophysiological link between lipids and infection/inflammation and atherosclerosis.

Differential cell cycle progression patterns of infiltrating leukocytes and resident cells after balloon injury of the rat carotid artery

The heterogeneous nature of the cell populations involved in vascular repair remains a major hurdle for the assessment of the cellular events that take place in injured arteries. The present experiments were designed to estimate the proportions and cell cycle progression of infiltrating leukocytes versus resident vascular cells after balloon injury of the rat common carotid artery. After tissue disaggregation, cell suspension samples from each artery were analyzed by flow cytometry. Cells were stained with anti-CD45 or anti-alpha-smooth muscle actin antibodies to identify leukocytes and smooth muscle cells, respectively. A day after injury, a 12-fold increase in CD45+ leukocytes was found. Double labeling with CD45 and CD-3, ED-1, or granulocyte markers revealed that most infiltrating cells were monocytes and granulocytes. Approximately 14% of infiltrating leukocytes were found to enter apoptosis at day 1, and 17% entered S phase at day 3. In contrast, the highest proliferation rate of resident alpha-smooth muscle actin-positive cells was observed at day 7 (19%). The present results demonstrate that infiltrating leukocytes and resident vascular smooth muscle cells have dissimilar cell cycle profiles. Furthermore, our study demonstrates the feasibility of using flow cytometry to quantitatively determine the cell types and their relative activation state in injured arteries.

Relation of the leukocyte count to recurrent cardiac events in stable patients after acute myocardial infarction

Increasing evidence implicates inflammation as a risk factor for coronary artery disease. We determined whether an elevated leukocyte count is associated with an increased risk of death or reinfarction in stable patients with a past acute myocardial infarction (AMI). The current analysis is a substudy of the Multicenter Diltiazem Postinfarction Trial, which investigated the effect of diltiazem on mortality and reinfarction in 2,466 patients hospitalized for AMI. We included 1,294 patients in whom a leukocyte count was obtained 6 months after the index AMI. The composite end point of reinfarction or death was used as the primary end point of the study and reinfarction or cardiac death was used as a secondary end point. The study population was divided into 4 quartiles (Q1, Q2, Q3, and Q4) based on the leukocyte count. During a mean follow-up period of 25 months, 163 patients reached the primary end point: 8.7%, 10.9%, 14.0%, and 16.7%, in Q1, Q2, Q3, and, Q4 respectively (p = 0.01). After adjusting for potential covariates, Cox proportional-hazards analysis revealed that an increased leukocyte count was associated with an increased risk of both the primary end point (hazard ratio/1 quartile increase in leukocyte count, 1.26; p = 0.003; 95% confidence interval 1.08 to 1.47) and secondary end point (hazard ratio, 1.18/1-quartile increase; p = 0.05; 95% confidence interval 1.00 to 1.40). In conclusion, an increased leukocyte count measured in the stable post-AMI period is associated with an increased risk of cardiac events. These findings indicate that the leukocyte count may be another marker of an atherosclerotic inflammatory process that contributes to cardiac events in postinfarction patients.

Histamine increases the expression of LOX-1 via H2 receptor in human monocytic THP-1 cells

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a member of the scavenger receptor family, and is known to be expressed in monocytes/macrophages. We investigated the effect of histamine on the expression of LOX-1 in cells of the human monocytic leukemia cell line THP-1. Histamine as well as forskolin and dibutyryl cyclic AMP (Bt2-cAMP) stimulated the THP-1 monocytes to express the LOX-1 gene at the transcription level. This histamine effect on LOX-1 gene expression, via the histamine H2 receptor-mediated cAMP signal transduction pathway, was reduced after differentiation of the cells into macrophages, even though forskolin and Bt2-cAMP still enhanced the gene expression. The alteration of the responsiveness of LOX-1 expression to histamine was related to suppressed expression of the H2 receptor in THP-1 macrophages. The switch of the predominant class of histamine receptors between H1 and H2 would modulate the effects of histamine on LOX-1 gene expression in monocytes and macrophages, and therefore, would play a certain role in the inflammatory aspects of atherogenesis.

Pleiotropic effects of 3-hydroxy-3-methylglutaryl coenzyme a reductase inhibitors

The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors or statins are potent inhibitors of cholesterol biosynthesis. Several large clinical trials have demonstrated the beneficial effects of statins in the primary and secondary prevention of coronary heart disease. However, the overall clinical benefits observed with statin therapy appear to be greater than what might be expected from changes in lipid profile alone, suggesting that the beneficial effects of statins may extend beyond their effects on serum cholesterol levels. Indeed, recent experimental and clinical evidence indicates that some of the cholesterol-independent or "pleiotropic" effects of statins involve improving or restoring endothelial function, enhancing the stability of atherosclerotic plaques, and decreasing oxidative stress and vascular inflammation. Many of these pleiotropic effects of statins are mediated by their ability to block the synthesis of important isoprenoid intermediates, which serve as lipid attachments for a variety of intracellular signaling molecules. In particular, the inhibition of small GTP-binding proteins, Rho, Ras, and Rac, whose proper membrane localization and function are dependent on isoprenylation, may play an important role in mediating the direct cellular effects of statins on the vascular wall.

The chemokine KC, but not monocyte chemoattractant protein-1, triggers monocyte arrest on early atherosclerotic endothelium

In a reconstituted flow chamber system, preincubation with chemokines can trigger the arrest of rolling monocytes, suggesting that this interaction could help recruit these cells to early atherosclerotic lesions. To date, however, the contribution of endothelium-derived chemokines found in these lesion to monocyte arrests has not been investigated. The endothelium of lesion-prone carotid arteries from apolipoprotein E-deficient (ApoE(-/-)) mice, but not control mice, presents the chemokines KC (mouse GRO-alpha) and JE (mouse monocyte chemoattractant protein-1 [MCP-1]). Arrest of a monocytic cell line or mouse blood monocytes perfused through carotid arteries of ApoE(-/-) mice was reduced by treating with either pertussis toxin, an antagonist of CXCR2, or an antibody to KC, but this process was insensitive to agents that blocked CCR-2 or JE. Conversely, monocyte accumulation more than doubled upon pre-perfusion of the carotid artery with KC but not with mouse MCP-1. Blockade of alpha(4)beta(1) integrin (VLA-4) or vascular cell adhesion molecule-1, but not CD18 or intercellular adhesion molecule-1, almost completely inhibited the arrest of monocytes. We conclude that when presented by early atherosclerotic lesions, KC but not murine MCP-1 triggers VLA-4-dependent monocyte recruitment.

Survival of Chlamydia pneumoniae-infected Mono Mac 6 cells is dependent on NF-kappaB binding activity

The respiratory tract pathogen Chlamydia pneumoniae has been associated with atherosclerosis. Monocytes are supposed to serve as a vehicle for systemic dissemination of intracellular C. pneumoniae from the lung to the artery vessel wall. We were therefore interested in pathogen-induced cellular events associated with NF-kappaB, a crucial transcription factor for both inflammatory cytokines and antiapoptotic molecules. In this study we demonstrate by electrophoretic mobility shift assay that C. pneumoniae infection of the human monocytic cell line Mono Mac 6 induces activation of NF-kappaB over 48 h, with a maximum level at 1 h postinfection. As shown by supershift assay, the activated NF-kappaB complex consists of the subunits RelA (p65) and NF-kappaB1 (p50). Apoptotic host cells were not detected during the early stages of the infection when maximal activation of NF-kappaB was detected. Pretreatment of Mono Mac 6 with the antioxidant and NF-kappaB inhibitor PDTC (pyrrolidine dithiocarbamate) induced activation of caspase-3 and led to apoptotic cell death. The C. pneumoniae-induced activation of the NF-kappaB complex was reduced by PDTC, which in parallel resulted in an increased apoptosis, as quantified by annexin V labeling and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling reaction. In the complete absence of activated NF-kappaB, when Mono Mac 6 cells were pretreated with the more potent NF-kappaB inhibitors MG-132 and parthenolide a C. pneumoniae-mediated rescue of cells from induced apoptosis could not be achieved. Our results indicate that activation of NF-kappaB in C. pneumoniae-infected Mono Mac 6 cells is associated with protection of Mono Mac 6 cells against apoptosis and might thereby contribute to systemic spread of the pathogen.

T-cell immunity in acute coronary syndromes

Acute coronary syndromes (ACS) are complications of atherosclerotic vascular disease that are triggered by the sudden rupture of an atheroma. Atherosclerotic plaque stability is determined by multiple factors, of which immune and inflammatory pathways are critical. Unstable plaque is characterized by an infiltrate of T cells and macrophages, thereby resembling a delayed hypersensitivity reaction. On activation, T cells secrete cytokines that regulate the activity of macrophages, or the T cells may differentiate into effector cells with tissue-damaging potential. Constitutive stimulation of T cells and macrophages in ACS is not limited to the vascular lesion but also involves peripheral immune cells, suggesting fundamental abnormalities in homeostatic mechanisms that control the assembly, turnover, and diversity of the immune system as a whole. This review gives particular attention to the emergence of a specialized T-cell subset, natural killer T cells, in patients with ACS. Natural killer T cells have proinflammatory properties and the capability of directly contributing to vascular injury.

Association of osteoporosis and cardiovascular disease in women with systemic lupus erythematosus

OBJECTIVE

Young women with lupus are at increased risk for premature osteoporosis and cardiovascular disease. Experimental evidence suggests that inflammation and immune-mediated mechanisms, key factors in the pathogenesis of lupus, play a role in osteogenesis and atherogenesis. This study investigated whether bone mineral density (BMD) was associated with the carotid plaque index, intima media thickness (IMT), or coronary artery calcium score in lupus patients.

METHODS

In this pilot study, 65 women with lupus underwent carotid B-mode ultrasound to measure the carotid plaque index and IMT, and dual x-ray absorptiometry to measure BMD at the lumbar spine and hip. As part of a feasibility study, 13 of these 65 patients also underwent electron-beam computed tomography to assess coronary artery calcification.

RESULTS

The carotid plaque index was higher (1.00, 1.00, and 0.38, respectively) in the patients in the lowest and middle tertiles of hip BMD when compared with patients in the highest tertile of hip BMD. The correlation coefficient between the coronary artery calcium score and lumbar spine BMD was -0.57 (P = 0.04), and between the coronary artery calcium score and hip BMD was -0.55 (P = 0.05).

CONCLUSION

These results demonstrate an association between decreased BMD and both an increased carotid plaque index and presence of coronary artery calcification in a small cohort of young women with lupus.

Interleukin-6 gene -174g>c and -572g>c promoter polymorphisms are strong predictors of plasma interleukin-6 levels after coronary artery bypass surgery

Interleukin-6 (IL-6) synthesized in response to diverse stimuli may play an important role in bridging the inflammatory and atherosclerotic processes. The acute-phase response after coronary artery bypass graft surgery (CABG) is associated with the induction and release of cytokines, such as IL-6. We have examined the effect of common polymorphisms in the IL-6 gene promoter (-174G>C, -572G>C, and -597G>A) on IL-6 levels after elective CABG. DNA extracted from the peripheral blood of 127 patients was amplified by polymerase chain reaction. IL-6 genotypes were resolved by gel electrophoresis after restriction enzyme digestion. Serum IL-6 was measured before surgery and in serial samples at 6, 24, 48, and 72 hours after CABG. Genotype distribution was as expected for a population in Hardy-Weinberg equilibrium for all polymorphisms. Rare allele frequencies (+/-95% CIs) were similar to those reported previously: -597A 0.36 (0.30 to 0.42), -572C 0.07 (0.04 to 0.10), and -174C 0.37 (0.31 to 0.43). The -174G>C and -597G>A genotypes were in strong allelic association (Delta=0.97, P<0.001). Baseline IL-6 levels did not significantly differ between patients with different genotypes for any polymorphism. However, 6 hours after CABG, peak IL-6 levels were significantly higher (P=0.03) in carriers of the -572C allele than in those of the -572GG genotype (355+/-67 versus 216+/-13 pg/mL, respectively) and in those with genotype -174CC compared with -174G allele carriers (287+/-31 versus 227+/-15 pg/mL, respectively; P=0.04). These effects remained statistically significant after adjusting for possible confounders, including age, sex, smoking, duration of cardiopulmonary bypass, aortic cross-clamp time, and total duration of surgery. These data demonstrate that IL-6 promoter polymorphisms influence peak IL-6 production after CABG, suggesting that these polymorphisms, which are functional in vitro, are also functional in vivo, suggesting a genetic influence on IL-6 levels after acute severe injury.

HIV envelope gp120 activates human arterial smooth muscle cells

There have been increasing reports of acute coronary thrombotic events in patients with HIV. Although these clinical events have been attributed primarily to dyslipidemia associated with protease inhibitor therapy, autopsy studies in children with HIV suggest the presence of an underlying arteriopathy. This study demonstrates that the HIV envelope protein, gp120, activates human arterial smooth muscle cells to express tissue factor, the initiator of the coagulation cascade. The induction of tissue factor by gp120 is mediated by two biologically relevant coreceptors for HIV infection, CXCR4 and CCR5, and is also dependent on the presence of functional CD4. Induction of tissue factor by gp120 requires activation of mitogen-activating protein kinases, activation of protein kinase C, and generation of reactive oxygen species, signaling pathways that have protean effects on smooth muscle cell physiology. The activation of smooth muscle cells by gp120 may play an important role in the vascular, thrombotic, and inflammatory responses to HIV infection.

VLDL modulates the cytokine secretion profile to a proinflammatory pattern

Human very-low-density lipoprotein (VLDL) inhibits DNA synthesis in lymphocytes activated by the nonspecific mitogen concanavalin A (Con A). We studied the effects of VLDL on lymphocyte activation (IL-2 receptor expression), cell cycle progression, and production of IL-2 and of IL-4 (a proinflammatory and an anti-inflammatory interleukin, respectively) to understand why an atherogenic lipoprotein inhibits cell proliferation. After 48 h of stimulation with the mitogen, VLDL decreased the population of cells bearing IL-2 receptor and the population of T-cells that progress through the cell cycle, increasing the population of T-cells in G(0)/G(1). Cells cultured in the presence of Con A and VLDL produced higher levels of IL-2 and lower levels of IL-4 than cells cultured without VLDL. These results suggest that VLDL inhibits lymphocyte proliferation by reducing IL-2 receptor and enhancing the levels of IL-2. Probably, one atherogenic effect of VLDL is to modulate the cytokine secretion profile of lymphocytes to a predominantly proinflammatory response.