The inflamed plaque: cytokine production and cellular cholesterol balance in the vessel wall

Docosahexaenoic acid decreases TNF-α-induced lectin-like oxidized low-density lipoprotein receptor-1 expression in THP-1 cells

Docosahexaenoic acid (DHA) prevents atherosclerosis and may decrease monocyte/macrophage activation by tumor necrosis factor (TNF)-α. Here, we sought to determine the protective effects of DHA against TNF-α-induced stimulation of lectin-like oxidized low-density lipoprotein (LDL) receptor-1 (LOX-1) expression, which is associated with atherosclerosis. Using reverse transcription polymerase chain reaction, we found that TNF-α induced the expression of LOX-1 (OLR1), NADPH oxidase 2 (Nox2), p47phox (NCF1), very late antigen-4 (ITGA4), and lymphocyte function-associated antigen (ITGAL) genes. Additionally, DHA attenuated TNF-α-induced acetylated (Ac)-LDL uptake and reactive oxygen species (ROS) production, as measured using fluorescently labeled LDL and H2DCFDA, respectively, and reduced the expression levels of these genes. Moreover, the PI3 kinase inhibitor LY294002 blocked these effects of DHA. These results indicated that DHA inhibited several events associated with redox regulation in a PI3K-dependent manner, thereby mediating the expression of LOX-1 in monocytes/macrophages.

Therapeutic Potential of the Nitrite-Generated NO Pathway in Vascular Dysfunction

Nitric oxide (NO) generated through L-arginine metabolism by endothelial nitric oxide synthase (eNOS) is an important regulator of the vessel wall. Dysregulation of this system has been implicated in various pathological vascular conditions, including atherosclerosis, angiogenesis, arteriogenesis, neointimal hyperplasia, and pulmonary hypertension. The pathophysiology involves a decreased bioavailability of NO within the vessel wall by competitive utilization of L-arginine by arginase and “eNOS uncoupling.” Generation of NO through reduction of nitrate and nitrite represents an alternative pathway that may be utilized to increase the bioavailability of NO within the vessel wall. We review the therapeutic potential of the nitrate/nitrite/NO pathway in vascular dysfunction.

Deficiency of glycine N-methyltransferase aggravates atherosclerosis in apolipoprotein E-null mice

The mechanism underlying the dysregulation of cholesterol metabolism and inflammation in atherogenesis is not understood fully. Glycine N-methyltransferase (GNMT) has been implicated in hepatic lipid metabolism and the pathogenesis of liver diseases. However, little is known about the significance of GNMT in atherosclerosis. We showed the predominant expression of GNMT in foamy macrophages of mouse atherosclerotic aortas. Genetic deletion of GNMT exacerbated the hyperlipidemia, inflammation and development of atherosclerosis in apolipoprotein E-deficient mice. In addition, ablation of GNMT in macrophages aggravated oxidized low-density lipoprotein-mediated cholesterol accumulation in macrophage foam cells by downregulating the expression of reverse cholesterol transporters including ATP-binding cassette transporters-A1 and G1 and scavenger receptor BI. Furthermore, tumor necrosis factor-α-induced inflammatory response was promoted in GNMT-null macrophages. Collectively, our data suggest that GNMT is a crucial regulator in cholesterol metabolism and in inflammation, and contributes to the pathogenesis of atherosclerosis. This finding may reveal a potential therapeutic target for atherosclerosis.

Macrophage-specific transgenic expression of cholesteryl ester hydrolase attenuates hepatic lipid accumulation and also improves glucose tolerance in ob/ob mice

Cellular cholesterol homeostasis is increasingly being recognized as an important determinant of the inflammatory status of macrophages, and a decrease in cellular cholesterol levels polarizes macrophages toward an anti-inflammatory or M2 phenotype. Cholesteryl ester hydrolase (CEH) catalyzes the hydrolysis of stored intracellular cholesteryl esters (CE) and thereby enhances free cholesterol efflux and reduces cellular CE content. We have reported earlier reduced atherosclerosis as well as lesion necrosis and improved insulin sensitivity (due to decreased adipose tissue inflammation) in macrophage-specific CEH transgenic (CEHTg) mice in the LDLR(-/-) background. In the present study, we examined the effects of reduced intracellular accumulation of CE in CEHTg macrophages in an established diabetic mouse model, namely the leptin-deficient ob/ob mouse. Macrophage-specific transgenic expression of CEH improved glucose tolerance in ob/ob-CEHTg mice significantly compared with ob/ob nontransgenic littermates, but with no apparent change in macrophage infiltration into the adipose tissue. However, there was a significant decrease in hepatic lipid accumulation in ob/ob-CEHTg mice. Consistently, decreased [(14)C]acetate incorporation into total lipids and triglycerides was noted in precision-cut liver slices from ob/ob-CEHTg mice. In the primary hepatocyte-macrophage coculture system, macrophages from CEHTg mice significantly reduced the incorporation of [(14)C]acetate into triglycerides in hepatocytes, indicating a direct effect of macrophages on hepatocyte triglyceride biosynthesis. Kupffer cells isolated from ob/ob-CEHTg mice were polarized toward an anti-inflammatory M2 (Ly6C(lo)) phenotype. Taken together, these studies demonstrate that transgenic overexpression of CEH in macrophages polarizes hepatic macrophages (Kupffer cells) to an anti-inflammatory M2 phenotype that attenuates hepatic lipid synthesis and accumulation.

Linking immunity to atherosclerosis: implications for vascular pharmacology--a tribute to Göran K. Hansson

For the past decade, we have deepened our understanding of the pathogenesis of atherosclerosis, a chronic arterial disease that causes cardiac and cerebral infarction and peripheral vascular disorders. Because of this extended understanding, more effective strategies for prevention and treatment of this disease are emerging. One of the fundamental mechanisms that lead to progress or regression in atherosclerosis, thus influencing its life-threatening complications, occurs through functional changes in vascular immunity and inflammation. This review briefly summarizes the discoveries in basic and translational sciences in this area and recent advances in clinical medicine against atherosclerotic vascular diseases.

Macrophage cholesterol homeostasis and metabolic diseases: critical role of cholesteryl ester mobilization

Atherogenic dyslipidemia, including low HDL levels, is the major contributor of residual risk of cardiovascular disease that remains even after aggressive statin therapy to reduce LDL-cholesterol. Currently, distinction is not made between HDL-cholesterol and HDL, which is a lipoprotein consisting of several proteins and a core containing cholesteryl esters (CEs). The importance of assessing HDL functionality, specifically its role in facilitating cholesterol efflux from foam cells, is relevant to atherogenesis. Since HDLs can only remove unesterified cholesterol from macrophages while cholesterol is stored as CEs within foam cells, intracellular CE hydrolysis by CE hydrolase is vital. Reduction in macrophage lipid burden not only attenuates atherosclerosis but also reduces inflammation and linked pathologies such as Type 2 diabetes and chronic kidney disease. Targeting reduction in macrophage CE levels and focusing on enhancing cholesterol flux from peripheral tissues to liver for final elimination is proposed.

Vasomotor symptoms and coronary artery calcium in postmenopausal women

OBJECTIVE

We assessed whether vasomotor symptoms (VMS) are associated with coronary artery calcium (CAC) and how hormone therapy (HT) may influence this association.

METHODS

Participants were a subset of women aged 50 to 59 years with a history of hysterectomy who were enrolled in the Women's Health Initiative (WHI) estrogen-alone clinical trial and underwent a CT scan of the chest at the end of the trial to determine CAC. Participants provided information about VMS (hot flashes and/or night sweats), as well as HT use, on self-administered questionnaires at trial baseline.

RESULTS

The sample consisted of 918 women with a mean (SD) age of 55.1 (2.8) years at WHI randomization and 64.8 (2.9) years at CAC ascertainment. The prevalence of a CAC score higher than 0 was 46%, whereas the prevalence of a CAC score of 10 or higher and higher than 100 was 39% and 19%, respectively. At randomization, 77% reported a history of any VMS at any time before or at enrollment in the WHI, whereas 20% reported any VMS present only at enrollment. Compared with those without a history of any VMS and after adjustment for potential confounders, a history of any VMS at any time up to and including WHI enrollment was associated with significantly reduced odds for CAC higher than 0 (odds ratio, 0.66; 95% CI, 0.45-0.98). Moreover, as duration of HT increased, the inverse association between any VMS and CAC moved toward the null.

CONCLUSIONS

A history of any VMS was significantly associated with reduced odds for CAC independent of traditional cardiovascular disease risk factors and other relevant covariates. This association seems to be influenced by duration of HT.

Erythropoietin suppresses the formation of macrophage foam cells: role of liver X receptor alpha

BACKGROUND

In addition to the hematopoietic effect of erythropoietin, increasing evidence suggests that erythropoietin also exerts protective effects for cardiovascular diseases. However, the role of erythropoietin and its underlying mechanism in macrophage foam cell formation are poorly understood.

METHODS AND RESULTS

Compared with wild-type specimens, erythropoietin was increased in atherosclerotic aortas of apolipoprotein E-deficient (apoE(-/-)) mice, mainly in the macrophage foam cells of the lesions. Erythropoietin levels in culture medium and macrophages were significantly elevated in response to oxidized low-density lipoprotein in a dose-dependent manner. Furthermore, erythropoietin markedly attenuated lipid accumulation in oxidized low-density lipoprotein-treated macrophages, a result that was due to an increase in cholesterol efflux. Erythropoietin treatment significantly increased ATP-binding cassette transporters (ABC) A1 and ABCG1 mRNA and protein levels without affecting protein expression of scavenger receptors, including scavenger receptor-A, CD36, and scavenger receptor-BI. The upregulation of ABCA1 and ABCG1 by erythropoietin resulted from liver X receptor alpha activation, which was confirmed by its prevention on expression of ABCA1 and ABCG1 after pharmacological or small interfering RNA inhibition of liver X receptor alpha. Moreover, the erythropoietin-mediated attenuation on lipid accumulation was abolished by such inhibition. Finally, reduced lipid accumulation and marked increase in ABCA1 and ABCG1 were demonstrated in erythropoietin-overexpressed macrophages.

CONCLUSIONS

Our data suggest that erythropoietin suppresses foam cell formation via the liver X receptor alpha-dependent upregulation of ABCA1 and ABCG1.

Improved insulin sensitivity in high fat- and high cholesterol-fed Ldlr-/- mice with macrophage-specific transgenic expression of cholesteryl ester hydrolase: role of macrophage inflammation and infiltration into adipose tissue

Cellular cholesterol balance induces changes in the inflammatory status of macrophages, and low grade chronic inflammation is increasingly being recognized as one of the key steps in the development of atherosclerosis as well as insulin resistance. Cholesteryl ester hydrolase (CEH) catalyzes the hydrolysis of intracellular stored cholesteryl esters (CEs) and thereby enhances free cholesterol efflux and reduces cellular CE content. We have earlier reported reduced atherosclerosis and lesion necrosis in macrophage-specific CEH transgenic mice on a Ldlr(-/-) background. In the present study, we tested the hypothesis that reduced intracellular accumulation of CE in macrophages from CEH transgenic mice will attenuate expression of proinflammatory mediators, thereby reducing infiltration into adipose tissue, alleviating inflammation, and resulting in improved insulin sensitivity. Western diet fed Ldlr(-/-)CEH transgenic mice showed improved insulin sensitivity as assessed by glucose and insulin tolerance tests. Macrophages from CEH transgenic mice expressed significantly lower levels of proinflammatory cytokines (interleukin-1beta and interleukin-6) and chemokine (MCP-1; monocyte chemoattractant protein). Attenuation of NF-kappaB- and AP-1-driven gene expression was determined to be the underlying mechanism. Infiltration of macrophages into the adipose tissue that increases inflammation and impairs insulin signaling was also significantly reduced in Ldlr(-/-)CEH transgenic mice. In the OP-9 adipocyte peritoneal macrophage co-culture system, macrophages from CEH transgenic mice had a significantly reduced effect on insulin signaling as measured by Akt phosphorylation compared with nontransgenic macrophages. Taken together, these studies demonstrate that macrophage-specific overexpression of CEH decreases expression of proinflammatory mediators and attenuates macrophage infiltration into the adipose tissue, resulting in decreased circulating cytokines and improved insulin sensitivity.

Adenosine blocks IFN-gamma-induced phosphorylation of STAT1 on serine 727 to reduce macrophage activation

Macrophages are activated by IFN-gamma, a proinflammatory and proatherogenic cytokine that mediates its downstream effects primarily through STAT1. IFN-gamma signaling induces phosphorylation of two STAT1 residues: Tyr(701) (Y701), which facilitates dimerization, nuclear translocation, and DNA binding; and Ser(727) (S727), which enables maximal STAT1 transcription activity. Immunosuppressive molecules such as adenosine in the cellular microenvironment can reduce macrophage inflammatory and atherogenic functions through receptor-mediated signaling pathways. We hypothesized that adenosine achieves these protective effects by interrupting IFN-gamma signaling in activated macrophages. This investigation demonstrates that adding adenosine to IFN-gamma-stimulated murine RAW 264.7 and human THP-1 macrophages results in unique modulation of STAT1 serine and tyrosine phosphorylation events. We show that adenosine inhibits IFN-gamma-induced STAT1 S727 phosphorylation by >30% and phosphoserine-mediated transcriptional activity by 58% but has no effect on phosphorylation of Y701 or receptor-associated JAK tyrosine kinases. Inhibition of the adenosine A(3) receptor with a subtype-specific antagonist (MRS 1191 in RAW 264.7 cells and MRS 1220 in THP-1 cells) reverses this adenosine suppressive effect on STAT1 phosphoserine status by 25-50%. Further, RAW 264.7 A(3) receptor stimulation with Cl-IB-MECA reduces IFN-gamma-induced STAT1 transcriptional activity by 45% and STAT1-dependent gene expression by up to 80%. These data suggest that A(3) receptor signaling is key to adenosine-mediated STAT1 modulation and anti-inflammatory action in IFN-gamma-activated mouse and human macrophages. Because STAT1 plays a key role in IFN-gamma-induced inflammation and foam cell transformation, a better understanding of the mechanisms underlying STAT1 deactivation by adenosine may improve preventative and therapeutic approaches to vascular disease.

Candesartan inhibits Toll-like receptor expression and activity both in vitro and in vivo

INTRODUCTION

Toll-like receptors play an important role in the innate immune system and are found to be crucial in severe diseases like sepsis, atherosclerosis, and arthritis. TLR2 and TLR4 expression is upregulated in the inflammatory diseases. Angiotensin II in addition to stimulating vasoconstriction also induces an increase in ROS and a proinflammatory phenotype via AT(1)R. Angiotensin II type-1 receptor blocker (ARB), widely used as an antihypertensive drug, has been reported to also have anti-inflammatory effects. Thus, we investigated whether an ARB exerts anti-inflammatory effects via inhibiting TLR2 and TLR4 expression.

METHODS AND RESULTS

Monocytes were isolated from healthy human volunteers and treated with the synthetic lipoprotein Pam3CSK4 or LPS in the absence or presence of candesartan. Pretreatment of human monocytes with candesartan significantly decreased Pam3CSK4 or LPS induced TLR2 and TLR4 expression of both mRNA and protein levels (P<0.05 vs. control) along with decrease in the activity of NF-kappaB and the expression of IL-1beta, IL-6, TNF-alpha, and MCP-1. Furthermore, candesartan treated mice show decreased TLR2 and TLR4 expression compared to vehicle control mice.

CONCLUSION

Pam3CSK4 and LPS induced TLR2 and TLR4 expression at mRNA and protein levels are inhibited by candesartan both in vitro and in vivo. Thus, we define a novel pathway by which candesartan could induce anti-inflammatory effects.

Classical conditioning of the rabbit's nictitating membrane response is a function of the duration of dietary cholesterol

Modifying dietary cholesterol may improve learning and memory but very high cholesterol can cause pathophysiology and death. Rabbits fed 2% cholesterol for 8, 10 or 12 weeks with 0.12 ppm copper added to distilled water and rabbits fed a normal diet without copper added to distilled water (0 weeks) were given a difficult trace classical conditioning task and an easy delay conditioning task pairing tone with corneal air puff. The majority of cholesterol-fed rabbits survived the deleterious effects of the diet but survival was an inverse function of the diet duration. Compared to controls, the level of classical conditioning and conditioning-specific reflex modification were an inverted "U"-shaped function of diet duration. Highest levels of responding occurred in rabbits on cholesterol for 10 weeks and trace conditioning was negatively correlated with the number of hippocampal beta-amyloid-positive neurons. Rabbits on the diet for 12 weeks responded at levels comparable to controls. The data provide support for the idea that dietary cholesterol may facilitate learning and memory but there is an eventual trade off with pathophysiological consequences of the diet.

High dietary cholesterol facilitates classical conditioning of the rabbit's nictitating membrane response

Studies have shown that modifying dietary cholesterol may improve learning and that serum cholesterol levels can be positively correlated with cognitive performance. Rabbits fed a 0, 0.5, 1 or 2% cholesterol diet for eight weeks and 0.12 ppm copper added to their drinking water received trace and then delay classical conditioning pairing tone with corneal air puff during which movement of the nictitating membrane (NM) across the eye was monitored. We found that the level of classical conditioning and conditioning-specific reflex modification (CRM) as well as the number of beta amyloid-labeled neurons in the cortex and hippocampus were a function of the concentration of cholesterol in the diet. The data provide support for the idea that dietary cholesterol may facilitate learning and memory.

Effect of an enriched cholesterol diet during gestation on fatty acid synthase, HMG-CoA reductase and SREBP-1/2 expressions in rabbits

Pregnancy is associated with hyperlipidemia and hypercholesterolemia in humans. These changes take place to support fetal growth and development, and modifications of these maternal concentrations may influence lipids and cholesterol synthesis in the dam, fetus and placenta. Administration of a 0.2% enriched cholesterol diet (ECD) during rabbit gestation significantly increased cholesterol and triglyceride (TG) levels in maternal livers and decreased fetal weight by 15%. Here we used Western blot analysis to examine the impact of gestation and 0.2% ECD on the expression levels of fatty acid synthase (FAS), HMGR and SREBP-1/2, which are involved in either lipid or cholesterol synthesis. We confirmed that gestation modifies the hepatic and circulating lipid profile in the mother. Our data also suggest that the maternal liver mainly supports lipogenesis, while the placenta plays a key role in cholesterol synthesis. Thus, our data demonstrate a decrease in HMGR protein levels in dam livers by feeding an ECD. In the placenta, SREBPs are highly expressed, and the ECD supplementation increased nuclear SREBP-1/2 protein levels. In addition, our results show a decrease in FAS protein levels in non-pregnant liver and in the liver of offspring from ECD-treated animals. Finally, our data suggest that the placenta does not modify its own cholesterol synthesis in response to an increase in circulating cholesterol. However, the dam liver compensates for this increase by essentially decreasing the level of HMGR expression. Because HMGR and FAS expressions do not correlate with the circulating lipid profile, it would be interesting to find which genes are then targeted by SREBP-1/2 during gestation.

Renal artery calcium: relationship to systemic calcified atherosclerosis

In this study we tested the hypothesis that calcium due to atherosclerosis in the renal arteries would be significantly associated with calcium in multiple other vascular beds, independent of traditional risk factors for cardiovascular disease (CVD). Electron beam computed tomography was conducted in 1461 consecutive asymptomatic patients free of clinical CVD to determine the presence and extent of calcium in the renal arteries, coronary and non-coronary vasculature and the aortic and mitral annuli. The overall prevalence for calcium in either renal artery was 18.0%, with men having a significantly higher prevalence (20.2%) than women (15.0%) [p = 0.01]. Renal artery calcium (RAC) was significantly correlated with calcium located in the carotids, coronaries, thoracic aorta, abdominal aorta and iliac arteries and calcium in the mitral and aortic annuli (r range = 0.22-0.37). In a multi-variable model containing the traditional CVD risk factors, the presence of calcium in the renal arteries was significantly associated with age, male sex and a diagnosis of hypertension. After adjustment for these variables, the presence of calcium in the thoracic or abdominal aorta was significantly associated with RAC (OR = 2.1 and 2.0, respectively; p < 0.01 for both). The sensitivity for prevalent RAC was highest in those individuals with any calcium in the abdominal aorta (94.5%). In conclusion, calcium related to atherosclerosis in the renal arteries is highly associated with atherosclerotic calcification in other vascular beds, especially the aorta, and the valvular annuli. These relationships are independent of traditional CVD risk factors.

Adoptive Transfer of CD4 + T Cells Reactive to Modified Low-Density Lipoprotein Aggravates Atherosclerosis

Objective— Atherosclerosis is associated with immune responses to oxidized low-density lipoprotein (oxLDL). The presence of activated macrophages and T cells in lesions suggests that cell-mediated immune reactions are taking place during the disease process. However, the role of specific immune responses has remained unclear. We have previously shown that transfer of CD4 + T cells from apolipoprotein E knockout mice (apoE −/− ) into immunodeficient apoE −/− scid/scid mice accelerates disease.

Methods and Results— To test whether this effect is dependent on specific disease-associated antigens, purified CD4 + T cells from oxLDL-immunized mice were transferred into apoE −/− scid/scid mice. CD4 + T cells from mice immunized with a nonrelevant antigen, keyhole limpet hemocyanin (KLH), and naïve CD4 + T cells were used as controls. After 12 weeks, all mice that received T cells had larger lesions than untouched apoE −/− scid/scid controls. However, mice receiving CD4 + T cells from oxLDL immunized mice had substantially accelerated lesion progression compared with those receiving naive or KLH-primed T cells. Circulating levels of interferon-γ were increased in proportion to the acceleration of atherosclerosis.

Conclusion— These data show that adoptive transfer of purified CD4+ T cells from oxLDL-immunized mice accelerates atherosclerosis. They support the notion that Th1 cellular immunity is proatherogenic and identify oxLDL as a culprit autoantigen.

Mitral and Aortic Annular Calcification Are Highly Associated With Systemic Calcified Atherosclerosis

BACKGROUND

Atherosclerosis has been implicated as a cause of valvular calcification. The aim of this study was to determine whether atherosclerotic calcification in multiple vascular areas is significantly associated with aortic or mitral annular calcification independent of traditional risk factors.

METHODS AND RESULTS

A total of 1242 consecutive asymptomatic patients free of clinical coronary heart disease were studied by electron-beam computed tomography for the extent of calcium due to atherosclerosis in 5 distinct vascular beds and calcium in the aortic and mitral annuli. Nearly 24% had calcium in the aortic annulus, whereas 8% were found to have mitral annular calcification. Age and a history of hypertension were the only traditional cardiovascular risk factors that were independently associated with prevalent calcification in the aortic and mitral annuli. After adjustment for age, gender, and cardiovascular disease risk factors, subjects with calcium in the thoracic aorta had the highest odds for the presence of aortic annular calcium (OR=3.9, P<0.01), whereas those with calcium in the abdominal aorta had the highest odds for mitral annular calcification (OR=5.1, P=0.01). Standardized increases in calcium in the abdominal aorta (OR=2.0, P<0.01) and iliacs (OR=1.8, P=0.01) were significantly associated with calcium in the aortic annulus after adjustment for the extent of calcium in the other vascular beds, whereas the thoracic aorta was significantly associated (OR=1.4, P=0.02) with calcium in the mitral annulus.

CONCLUSIONS

This study supports the hypothesis that calcification of the mitral and aortic annuli is related to atherosclerosis in other vascular beds.

Molecular aspects of atherogenesis: new insights and unsolved questions

The development of atherosclerotic disease results from the interaction between environment and genetic make up. A key factor in atherogenesis is the oxidative modification of lipids, which is involved in the recruitment of mononuclear leukocytes to the arterial intima--a process regulated by several groups of adhesion molecules and cytokines. Activated leukocytes, as well as endothelial mitochondria, can produce reactive oxygen species (ROS) that are associated with endothelial dysfunction, a cause of reduced nitric oxide (NO) bioactivity and further ROS production. Peroxisome proliferator-activated receptors (PPAR) and liver X receptors (LXR) are nuclear receptors significantly involved in the control of lipid metabolism, inflammation and insulin sensitivity. Also, an emerging role has been suggested for G protein coupled receptors and for the small Ras and Rho GTPases in the regulation of the expression of endothelial NO synthase (eNOS) and of tissue factor, which are involved in thrombus formation and modulation of vascular tone. Further, the interactions among eNOS, cholesterol, oxidated LDL and caveola membranes are probably involved in some molecular changes observed in vascular diseases. Despite the relevance of oxidative processes in atherogenesis, anti-oxidants have failed to significantly improve atherosclerosis (ATS) prevention, while statins have proved to be the most successful drugs.

Novel serologic markers of cardiovascular risk

New serologic markers of cardiovascular risk continue to be amassed. Among the new markers, C-reactive protein, fibrinogen, and homocysteine have enjoyed the most acceptance, but newer concepts such as inflammatory cytokines, aspirin resistance, and antioxidant deficiency continue to emerge. Traditional cardiac risk factors are able to predict less than half of cardiovascular events, and the new array of markers have added little to clinical practice, with their use and significance remaining unclear. This article analyzes the new serologic markers of risk in light of the mechanistic, epidemiologic, and clinical data collected over the past decade, and in so doing provides a comprehensive understanding of their role.

Systemic Acyl-CoA:cholesterol acyltransferase inhibition reduces inflammation and improves vascular function in hypercholesterolemia

BACKGROUND

Circulating lipids may initiate and progress atherosclerosis by causing vascular inflammation. Monocytes and tissue macrophages are involved and regulate lipid metabolism in the vascular wall through acetylation of cholesterol by acyl-CoA:cholesterol acyltransferase (ACAT). ACAT inhibition reduces atherosclerosis in animal models by mechanisms that may be independent of their effects on circulating lipids. Because endothelial dysfunction is an important factor in atherosclerosis, we tested the hypothesis that systemic ACAT inhibition would improve endothelial function in hypercholesterolemic humans and assessed its effects on circulating lipids and markers of systemic inflammation.

METHODS AND RESULTS

We studied 21 hypercholesterolemic subjects in a double-blind, randomized-crossover, placebo-controlled trial with assessments of circulating lipids, markers of inflammation, resistance-vessel endothelial function (with venous occlusion plethysmography), and conduit-vessel vasoreactivity (brachial artery flow-mediated dilation at baseline and after placebo or treatment with avasimibe 750 mg QDS for 8 weeks. There was a small change in total cholesterol with treatment (326+/-25 to 311+/-22 mg/dL, P=0.04). Circulating tumor necrosis factor-alpha was significantly reduced (4.0+/-0.3 to 3.6+/-0.2 pg/mL, P=0.02); resistance vessel responses to acetylcholine, bradykinin, and verapamil were significantly enhanced; and responses to nitroglycerin and conduit-vessel vasoreactivity were unchanged after ACAT inhibition.

CONCLUSIONS

Systemic ACAT inhibition reduces circulating tumor necrosis factor-alpha levels in hypercholesterolemic subjects and improves resistance-vessel endothelial function, with small effects on circulating cholesterol. This may be a novel therapeutic strategy to target vascular inflammation and endothelial dysfunction in atherosclerosis.

Proteomic studies of macrophage-derived foam cell from human U937 cell line using two-dimensional gel electrophoresis and tandem mass spectrometry

SUMMARY

The authors have identified 37 proteins in the whole-cell extracts from human monoblastic leukemia (U937) cell and macrophage-derived foam cell. The in vitro foam cell model was established by incubating the human U937 cells with oxidized low-density lipoprotein. The global changes in protein expressions between U937 foam cell and normal U937 cells were measured with two-dimensional polyacrylamide gel electrophoresis, and some proteins were trypsin-digested and then identified through tandem mass spectrometry after capillary liquid chromatography separation. Some of the identified proteins were validated via Internet links to the U937 proteomic map provided on the Expasy proteomics server. The experimental data can provide potential markers for atherosclerotic studies.

Hematopoietic NF-kappaB1 deficiency results in small atherosclerotic lesions with an inflammatory phenotype

Atherosclerosis is a chronic inflammatory disease characterized by the accumulation of lipid-laden macrophages in the vessel wall. One of the major transcription factors in inflammation is nuclear factor kappaB (NF-kappaB), and we have studied its role in the development of atherosclerosis. Bone marrow from mice targeted in the NF-kappaB1 gene encoding for the p50 subunit was used to reconstitute irradiated LDLR(-/-) mice as a model for atherosclerosis. After feeding the mice a high-fat diet, those deficient in NF-kappaB1 had a 41% lower rate of atherosclerosis than control mice, as judged by the sizes of the lesions. Furthermore, in the absence of NF-kappaB1, the lesions were characterized by an inflammatory phenotype, contained increased numbers of small cells, and were almost devoid of normal foam cells. In vitro studies using bone marrow (BM)-derived macrophages showed that macrophages lacking p50 had a prolonged production of tumor necrosis factor (TNF) in response to lipopolysaccharide (LPS), and other cytokines were also affected. Interestingly, the uptake of oxidized low-density lipoprotein (LDL) was greatly reduced in activated p50-deficient macrophages, probably because of a reduction in the expression of scavenger receptor class A. The effects on atherosclerosis might have resulted from the changes in cytokine production and the uptake of modified lipoproteins, making p50 a pivotal regulator of atherogenesis.

Cardiovascular disorders associated with cocaine use: myths and truths

Cocaine produces a pattern of cardiovascular responses that are associated with apparent myocardial ischemia, arrhythmias, and other life-threatening complications in some individuals. Despite recent efforts to better understand the causes of cocaine-induced cardiovascular dysfunction, there remain a number of unanswered questions regarding the specific mechanisms by which cocaine elicits hemodynamic responses. This review will describe the actions of cocaine on the cardiovascular system and the evidence for the mechanisms by which cocaine elicits hemodynamic and pathologic responses in humans and animals. The emphasis will be on experimental data that provide the basis for our understanding of the mechanisms of cardiovascular toxicity associated with cocaine. More importantly, this review will identify several controversies regarding the causes of cocaine-induced cardiovascular toxicity that as yet are still debated. The evidence supporting these findings will be described. Finally, this review will outline the obvious deficits in our current concepts regarding the cardiovascular actions of cocaine in hope of encouraging additional studies on this grave problem in our society.

Anticytokine therapy--new approach to the treatment of autoimmune and cytokine-disturbance diseases

We pioneered the theory (Nature, 1974) that hyperproduced interferons (cytokines) can bring autoimmune diseases (AD) and neutralizing these cytokines can be therapeutic. In 1975 we first performed successful anticytokine therapy using anti-IFN-alpha antibodies in patients with rheumatoid arthritis (RA). In 1989 we proposed also treating AD including AIDS by removing TNF-alpha and IFN-alpha. Our theory has been widely confirmed: injections of IFN-alpha and -gamma can exacerbate AD, while antibodies to IFN-alpha and -gamma and TNF-alpha can be therapeutic. Anti-IFN-gamma may be a universal treatment for Th1 AD. We had good results using anti-IFN-gamma to treat RA, multiple sclerosis (MS), transplant rejection, alopecia areata, vitiligo, psoriatic arthritis, psoriasis and others. For Th1/Th2 diseases, antagonists to cortisol could prevent the Th1-Th2 shift and allow treatment as a Th1 disease. Anticytokine therapy can also be therapeutic in many neuropsychiatric diseases. Every disturbance of homeostasis may lead to cytokine disturbance. IL-10 may restore homeostasis by inhibiting the production of certain Th1 cytokines and could be used to treat some embryonic disturbances and AD including MS.

High-density lipoprotein regulates calcification of vascular cells

Accumulating evidence has suggested the protective role of HDL in cardiovascular disease processes. Calcification is a common feature of atherosclerotic lesions and contributes to cardiovascular complications due to the loss of aortic resilience and function. Recent studies have suggested that vascular calcification shares several features with skeletal bone formation at the cellular and molecular levels. These include the presence of osteoblast-like calcifying vascular cells in the artery wall that undergo osteoblastic differentiation and calcification in vitro. We hypothesized that HDL may also protect against vascular calcification by regulating the osteogenic activity of these calcifying vascular cells. When treated with HDL, alkaline phosphatase activity, a marker of osteogenic differentiation of osteoblastic cells, was significantly reduced in those cells. Prolonged treatment with HDL also inhibited calcification of these cells, further supporting the antiosteogenic differentiation property of HDL when applied to vascular cells. Furthermore, HDL inhibited the osteogenic activity that was induced by inflammatory cytokines interleukin (IL)-1beta and IL-6 as well as by minimally oxidized LDL. HDL also partially inhibited the IL-6-induced activation of signal transducer and activator of transcription 3 in calcifying vascular cells, suggesting that HDL may inhibit cytokine-induced signal transduction pathways. The inhibitory effects of HDL were mimicked by lipids extracted from HDL but not by HDL-associated apolipoproteins or reconstituted HDL. Furthermore, oxidation of HDL rendered it pro-osteogenic. Taken together, these results suggest that HDL regulates the osteoblastic differentiation and calcification of vascular cells and that vascular calcification may be another target of HDL action in the artery wall.

A pilot with pain in his leg: thigh abscess caused by Salmonella enterica serotype Brandenburg

Salmonella enterica serotype Brandenburg is one of the more uncommon serotypes isolated from patients with gastroenteritis. Few cases of extraintestinal infections with serotype Brandenburg have been documented. The first case of a serotype Brandenburg-dependent thigh abscess originating from an atherosclerotic pseudoaneurysm of the femoral artery is reported.

Cytokines, acute-phase proteins, and hormones: IL-1 and TNF-alpha production in contact-mediated activation of monocytes by T lymphocytes

The cytokine network is a homeostatic system that has to be perceived in an analogous fashion to the acid/base equilibrium. The level of any cytokine in biological fluids can be interpreted correctly only by taking into account the levels of other synergistic cytokines, of their respective inhibitors, and of each cytokine receptor. Due to their potent activities in many different processes (including cell growth and differentiation, development, and repair processes leading to the restoration of homeostasis), the cytokine activities have to be tightly controlled by natural inhibitory mechanisms. Since one of the main functions of cytokines is to mediate interactions between the immune and inflammatory system, it is thought that chronic immuno-inflammatory diseases might be caused in part by the uncontrolled production of cytokines. Depending on the stage of inflammation or the biological effect determined, the same cytokine might be pro- or anti-inflammatory. This applies, for instance, to IL-4, IL-10, and TGFbeta. An important mechanism that triggers the production of pro-inflammatory cytokines in chronic inflammatory diseases is the direct cellular contact between stimulated T cells and monocyte-macrophages. This mechanism is blocked at the systemic level by the "negative" acute-phase protein apolipoprotein A-I (apo A-I). The levels of expression of cytokines and cytokine inhibitors and acute-phase proteins are ruled by hormones. Estrogens as well as androgens inhibit the production of IL-1beta and TNF-alpha on monocyte-macrophages. However, androgens antagonize estrogen stimulatory effects on apo A-I synthesis by the liver. Other studies suggest that estradiol is more inhibitory to Thl cytokines (e.g., IFNgamma, IL-2), while testosterone is inhibitory to Th2 cytokines (e.g., IL-4). Cytokines also control the axis of the hypothalamic-hypophyseal-adrenal glands as well as the sexual hormones. The discrepancy between studies would suggest that the mechanisms are different in physiological and pathophysiological conditions.

Atherosclerosis and inflammation

The pathophysiology of coronary atherosclerosis is complex and multifactorial. The probability of the development of symptomatic coronary heart disease may be predicted by standard risk factor stratification involving hypertension, dyslipidemia, age, positive family history, and diabetes. However, risk factor stratification has been demonstrated to have significant limitations in the individual patient, which has generated a search for more specific and sensitive markers. Evidence is increasing that atherosclerosis is a disease characterized by inflammation, beginning with the earliest identifiable lesion (fatty streak) to the advanced vulnerable plaque. Clinical markers of inflammation, including C-reactive protein, modified low-density lipoprotein, homocysteine, tumor necrosis factor, and thermogenicity, have been identified as emerging risk factors that may add prognostic information in patient management. This review centers on inflammation as a potential pathogenetic factor in atherosclerosis and the role that clinical markers may play in the identification of patients at risk.