Inflammatory cytokines cause coronary arteriosclerosis-like changes and alterations in the smooth-muscle phenotypes in pigs

Mechanisms of Coronary Artery Spasm

Recent clinical trials have highlighted that percutaneous coronary intervention in patients with stable angina provides limited additional benefits on top of optimal medical therapy. This has led to much more attention being paid to coronary vasomotion abnormalities regardless of obstructive or non-obstructive arterial segments. Coronary vasomotion is regulated by multiple mechanisms that include the endothelium, vascular smooth muscle cells (VSMCs), myocardial metabolic demand, autonomic nervous system and inflammation. Over the years, several animal models have been developed to explore the central mechanism of coronary artery spasm. This review summarises the landmark studies on the mechanisms of coronary vasospasm demonstrating the central role of Rho-kinase as a molecular switch of VSMC hypercontraction and the important role of coronary adventitial inflammation for Rho-kinase upregulation in VSMCs.

The Emerging Role of Rho Guanine Nucleotide Exchange Factors in Cardiovascular Disorders: Insights Into Atherosclerosis: A Mini Review

Atherosclerosis is a leading cause of cardiovascular disease, and atherosclerotic cardiovascular disease accounts for one-third of global deaths. However, the mechanism of atherosclerosis is not fully understood. It is well-known that the Rho GTPase family, especially Rho A, plays a vital role in the development and progression of arteriosclerosis. Rho guanine nucleotide exchange factors (Rho GEFs), which act upstream of Rho GTPases, are also involved in the atheromatous pathological process. Despite some research on the role of Rho GEFS in the regulation of atherosclerosis, the number of studies is small relative to studies on the essential function of Rho GEFs. Some studies have preliminarily revealed Rho GEF regulation of atherosclerosis by experiments in vivo and in vitro. Herein, we review the advances in research on the relationship and interaction between Rho GEFs and atheroma to provide a potential reference for further study of atherosclerosis.

TNFα and Reactive Oxygen Signaling in Vascular Smooth Muscle Cells in Hypertension and Atherosclerosis

Hypertension and atherosclerosis, the predecessors of stroke and myocardial infarction, are chronic vascular inflammatory reactions. Tumor necrosis factor alpha (TNFα), the "master" proinflammatory cytokine, contributes to both the initiation and maintenance of vascular inflammation. TNFα induces reactive oxygen species (ROS) production which drives the redox reactions that constitute "ROS signaling." However, these ROS may also cause oxidative stress which contributes to vascular dysfunction. Mice lacking TNFα or its receptors are protected against both acute and chronic cardiovascular injury. Humans suffering from TNFα-driven inflammatory conditions such as rheumatoid arthritis and psoriasis are at increased cardiovascular risk. When treated with highly specific biologic agents that target TNFα signaling (Etanercept, etc.) they display marked reductions in that risk. The ability of TNFα to induce endothelial dysfunction, often the first step in a progression toward serious vasculopathy, is well recognized and has been reviewed elsewhere. However, TNFα also has profound effects on vascular smooth muscle cells (VSMCs) including a fundamental change from a contractile to a secretory phenotype. This "phenotypic switching" promotes proliferation and production of extracellular matrix proteins which are associated with medial hypertrophy. Additionally, it promotes lipid storage and enhanced motility, changes that support the contribution of VSMCs to neointima and atherosclerotic plaque formation. This review focuses on the role of TNFα in driving the inflammatory changes in VSMC biology that contribute to cardiovascular disease. Special attention is given to the mechanisms by which TNFα promotes ROS production at specific subcellular locations, and the contribution of these ROS to TNFα signaling.

Association of matrix metalloproteinase 3 and endogenous inhibitors with inflammatory markers in mitral valve disease and calcification

Calcific mitral valve stenosis (MVS) is a common disease characterized by extensive remodeling of the extracellular matrix via matrix metalloproteinases (MMPs). The mechanism of calcification due to extensive matrix remodeling remains unclear. In this study, we investigated the relationship between MMP-3, tissue inhibitors of metalloproteinases (TIMPs) as well as pro-inflammatory cytokines and the phenomenon of calcification in MVS. 212 patients having rheumatic mitral stenosis (RMS) and 155 healthy control subjects were recruited in the Cardiology Department of La Rabta Hospital University. Levels of MMP-3, TIMPs, IL-6 and TNF-α were measured by ELISA sandwich assay, hs-CRP was measured by immunoturbidimetry. Plasma levels of MMP-3, TIMP-1 and MMP-3/TIMP-2 ratio were lower only in RMS women in comparison to the control group. Calcification degree correlated positively with MMP-3 in women and men. In addition, calcification was correlated positively with MMP-3/TIMPs ratio in women patients. The inflammatory parameters were positively associated with extracellular matrix turnover biomarkers in men patients. In patients, the level of MMP-3 was increased in men and women with a calcification score ≥ 5. In addition, MMP-3 level predicted the occurrence of calcification. At ROC curves analysis, the cut-off MMP-3 level was in women was 9.21 ng/ml (sensitivity 51.1%, specificity 89.3%) and in men was 12.84 ng/ml (sensitivity 78.6%, specificity 77.8%). The high levels of MMP-3 and the biomarkers of inflammation contribute to valvular remodeling and calcification of the mitral valve.

Prevalence of Panoramically Imaged Carotid Atheromas in Alcoholic Patients With Chronic Pancreatitis and Comorbid Diabetes

PURPOSE

Men with alcohol-related chronic pancreatitis (ARCP) resulting in type 3c diabetes mellitus (DM) are at a uniquely elevated risk of adverse ischemic events given the role of inflammation in both the underlying disease processes and atherosclerosis. We hypothesized that their panoramic images would show a prevalence of calcified carotid artery atheromas (calcified carotid artery plaques [CCAPs]) significantly more often than a general population of similarly aged men.

PATIENTS AND METHODS

We implemented a retrospective observational study. The sample was composed of male patients older than 30 years having panoramic images. The predictor variable was a diagnosis of ARCP-DM, and the outcome variable was the prevalence rate of CCAPs. The prevalence of CCAPs among the patients with ARCP-DM was then compared with that of a historical general population composed of similarly aged men. Descriptive and bivariate statistics were computed, and the P value was set at .05.

RESULTS

Of the 32 men (mean age, 61.7 ± 11.2 years) with ARCP-DM, 8 (25%) (mean age, 63.3 ± 4.80 years) had atheromas (CCAPs). There was a statistically significant (P < .05) association between a diagnosis of ARCP-DM and the presence of an atheroma on the panoramic image in comparison with the 3% rate manifested by the historical general-population cohort. The presence or absence of classic atherogenic risk factors within the ARCP-DM cohort failed to distinguish between individuals with and individuals without atheroma formation on their panoramic images.

CONCLUSIONS

The results of this study suggest that CCAP, a risk indicator for future adverse cardiovascular events, is frequently seen on the panoramic images of male patients with ARCP-DM. Dentists treating male patients with the disorder must be uniquely vigilant for the presence of these lesions.

Catastrophic catheter-induced coronary artery vasospasm successfully rescued using intravascular ultrasound imaging guidance

A 46-year-old man underwent coronary angiography for stable angina. He developed inferior ST-segment myocardial infarction during the angiography. Intravascular ultrasound (IVUS) findings suggested coronary vasospasm. Intracoronary administration of isosorbide dinitrate restored the coronary flow. This case illustrates the essential role IVUS imaging played in establishing the diagnosis of catheter-induced coronary vasospasm.

Interleukin-1β is associated with coronary endothelial dysfunction in patients with mTOR-inhibitor-eluting stent implantation

Implantation of mammalian target of rapamycin (mTOR)-inhibitor drug-eluting stents (DESs) impairs coronary endothelial function. There are no known non-invasive biomarkers of coronary endothelial dysfunction. We aimed to assess the association between serum interleukin-1beta (IL-1β) and coronary endothelial dysfunction in patients with mTOR-inhibitor DES implantation and to investigate the association between the mTOR pathway and IL-1β. We enrolled 35 patients who had implanted DESs for coronary artery disease. At a 10-month follow-up, peripheral venous blood samples were collected to measure IL-1β levels. Coronary endothelial dysfunction was evaluated by intracoronary infusion of incremental doses of acetylcholine. Serum IL-1β levels were significantly associated with the magnitude of vasoconstriction to acetylcholine at the segment distal (P < 0.05) but not proximal to the stent. Serum IL-1β levels were positively correlated with stent length (P < 0.05). To examine the direct effects of mTOR inhibition on IL-1β release, sirolimus was incubated in cultured human umbilical vein endothelial cells (HUVECs) or coronary artery smooth muscle cells (CASMCs). Sirolimus directly increased IL-1β mRNA expression (P < 0.01) and enhanced IL-1β release into the culture media (P < 0.01) in CASMCs, but not in HUVECs. Inhibition of mTOR triggers IL-1β release through transcriptional activation in CASMCs. Serum IL-1β levels are a potential biomarker for mTOR-inhibitor DES-associated coronary endothelial dysfunction.

Augmentation index (AI) in a dose-response relationship with smoking habits in males: The Tanushimaru study

We investigated the relationship between augmentation index (AI) and smoking habits in community-dwelling Japanese.This cross-sectional study enrolled 1926 subjects (769 males and 1157 females) aged 40 to 95 years who underwent a health check-up in a Japanese cohort of the Seven Countries Study, in Tanushimaru, a typical farming town in Kyushu Island in 2009. The subjects' medical history, alcohol intake, smoking habit, and current medications for hypertension, dyslipidemia, and diabetes were ascertained by questionnaire. Radial arterial pressure wave analysis was used to obtain AI. We analyzed the data stratified by gender.Age-adjusted means of AI in males showed a clear dose-response relationship in 4 categories of smoking habits (P = 0.010). There was no significant relationship between AI and smoking habits in females (P = 0.127). The significant dose-response relationship (P = 0.036) in males between AI and 4 categories of smoking habits still remained even after adjustment for age, body mass index, systolic blood pressure, estimated glomerular filtration rate, glucose, hypertensive medication, and alcohol intake.The present study demonstrated that AI values were significantly associated with smoking habits in a dose-dependent manner in Japanese males.

Stress cardiomyopathy: Is it limited to Takotsubo syndrome? Problems of definition

In 2006, Takotsubo syndrome (TTC) was described as a distinct type of stress-induced cardiomyopathy (stress cardiomyopathy). However, when thinking about Takotsubo cardiomyopathy from the viewpoints of the AHA and ESC classifications, 2 possible problems may arise. The first potential problem is that a forecast of disease outcome is lacking in the ESC classification, whereas the AHA only states that 'outcome is favorable with appropriate medical therapy'. However, based on the literature data, one can make a general conclusion that occurrence of myocardial lesions in TTC (i.e., myocardial fibrosis and contraction-band necrosis) causes the same effects as in other diseases with similar levels of myocardial damage and should not be considered to have a lesser impact on mortality. To summarise, TTC can cause not only severe complications such as pulmonary oedema, cardiogenic shock, and dangerous ventricular arrhythmias, but also damage to the myocardium, which can result in the development of potentially fatal conditions even after the disappearance of LV apical ballooning. The second potential problem arises from the definition of TTC as a stress cardiomyopathy in the AHA classification. In fact, the main factors leading to TTC are stress and microvascular anginas, since, as has been already discussed, coronary spasm can cause myocardium stunning, resulting in persistent apical ballooning. Thus, based on this review, 3 distinct types of stress cardiomyopathies exist (variant angina, microvascular angina, and TTC), with poor prognosis. Adding these diseases to the classification of cardiomyopathies will facilitate diagnosis and preventive prolonged treatment, which should include intensive anti-stress therapy.

RhoA/Rho-Kinase in the Cardiovascular System

Twenty years ago, Rho-kinase was identified as an important downstream effector of the small GTP-binding protein, RhoA. Thereafter, a series of studies demonstrated the important roles of Rho-kinase in the cardiovascular system. The RhoA/Rho-kinase pathway is now widely known to play important roles in many cellular functions, including contraction, motility, proliferation, and apoptosis, and its excessive activity induces oxidative stress and promotes the development of cardiovascular diseases. Furthermore, the important role of Rho-kinase has been demonstrated in the pathogenesis of vasospasm, arteriosclerosis, ischemia/reperfusion injury, hypertension, pulmonary hypertension, and heart failure. Cyclophilin A is secreted by vascular smooth muscle cells and inflammatory cells and activated platelets in a Rho-kinase-dependent manner, playing important roles in a wide range of cardiovascular diseases. Thus, the RhoA/Rho-kinase pathway plays crucial roles under both physiological and pathological conditions and is an important therapeutic target in cardiovascular medicine. Recently, functional differences between ROCK1 and ROCK2 have been reported in vitro. ROCK1 is specifically cleaved by caspase-3, whereas granzyme B cleaves ROCK2. However, limited information is available on the functional differences and interactions between ROCK1 and ROCK2 in the cardiovascular system in vivo. Herein, we will review the recent advances about the importance of RhoA/Rho-kinase in the cardiovascular system.

In vivo treatment of rat arterial adventitia with interleukin‑1β induces intimal proliferation via the JAK2/STAT3 signaling pathway

Previous studies have indicated that adventitial inflammation is involved in the development of atherosclerosis. The aim of this study was to investigate the effect of arterial adventitia inflammation induced by interleukin (IL)-1β on intimal proliferation and the mechanisms involved in this process. The left common carotid artery adventitia of male rats in the experimental and control groups (25 rats/group) was wrapped with agar containing or without a sustained-release suspension of 2.5 µg IL-1β, respectively. Five animals in each group were randomly selected for sacrifice at 2 h, 8 h, 24 h, 48 h, and 1 week post-treatment. Hematoxylin and eosin staining was performed for to analyze the morphology of the adventitia. The expression of janus kinase (JAK)2, signal transducer and activator of transcription (STAT)3, phosphorylated (p-)JAK2 and p-STAT3 were detected by western blot analysis or immunohistochemistry staining. A model of adventitial inflammation was successfully created by wrapping IL-1β around the rat carotid artery. IL-1β treatment induced vascular smooth muscle cell proliferation and migration as well as intimal proliferation. In addition, the expression of p-JAK2 and p-STAT3 increased after IL-1β treatment. Furthermore, an inhibitor of JAK2/STAT3 pathway, AG490, suppressed IL-1β-induced intimal proliferation and phosphorylation of JAK2 and STAT3. Thus, the JAK2/STAT3 signaling pathway is involved in intimal proliferation caused by vascular adventitial inflammation. Inhibiting the JAK2/STAT3 signaling pathway may be a novel method for the clinical treatment of artery atherosclerosis.

Targeting local vascular and systemic consequences of inflammation on vascular and cardiac valve calcification

INTRODUCTION

Cardiac valve calcification and vascular calcification (VC) are associated with cardiovascular mortality in the general population and in patients with chronic kidney disease (CKD). CKD, diabetes mellitus, and atherosclerosis are among the causes of systemic inflammation that are associated with VC.

AREAS COVERED

This review collates clinical and experimental evidence that inflammation accelerates VC progression. Specifically, we review the actions of key pro-inflammatory cytokines and inflammation-related transcription factors on VC, and the role played by senescence. Inflammatory cytokines, such as the TNF superfamily and IL-6 superfamily, and inflammation-related transcription factor NF-κB promote calcification in cultured vascular smooth muscle cells, valvular interstitial cells, or experimental animal models through direct effects, but also indirectly by decreasing circulating Fetuin A or Klotho levels.

EXPERT OPINION

Experimental evidence suggests a causal link between inflammation and VC that would change the clinical approach to prevention and treatment of VC. However, the molecular basis remains unclear and little is known about VC in humans treated with drugs targeting inflammatory cytokines. The effect of biologicals targeting TNF-α, RANKL, IL-6, and other inflammatory mediators on VC, in addition to the impact of dietary phosphate in patients with chronic systemic inflammation, requires study.

2014 Williams Harvey Lecture: importance of coronary vasomotion abnormalities-from bench to bedside

Coronary vasomotion abnormalities play important roles in the pathogenesis of ischaemic heart disease, in which endothelial dysfunction and coronary artery spasm are substantially involved. Endothelial vasodilator functions are heterogeneous depending on the vessel size, with relatively greater role of nitric oxide (NO) in conduit arteries and predominant role of endothelium-derived hyperpolarizing factor (EDHF) in resistance arteries, where endothelium-derived hydrogen peroxide serves as an important EDHF. The functions of NO synthases in the endothelium are also heterogeneous with multiple mechanisms involved, accounting for the diverse functions of the endothelium in vasomotor as well as metabolic modulations. Cardiovascular abnormalities and metabolic phenotypes become evident when all three NO synthases are deleted, suggesting the importance of both NO and EDHF. Coronary artery spasm plays important roles in the pathogenesis of a wide range of ischaemic heart disease. The central mechanism of the spasm is hypercontraction of vascular smooth muscle cells (VSMCs), but not endothelial dysfunction, where activation of Rho-kinase, a molecular switch of VSMC contraction, plays a major role through inhibition of myosin light-chain phosphatase. The Rho-kinase pathway is also involved in the pathogenesis of a wide range of cardiovascular diseases and new Rho-kinase inhibitors are under development for various indications. The registry study by the Japanese Coronary Spasm Association has demonstrated many important aspects of vasospastic angina. The ongoing international registry study of vasospastic angina in six nations should elucidate the unknown aspects of the disorder. Coronary vasomotion abnormalities appear to be an important therapeutic target in cardiovascular medicine.

Emerging regulators of vascular smooth muscle cell function in the development and progression of atherosclerosis

After a period of relative senescence in the field of vascular smooth muscle cell (VSMC) research with particular regards to atherosclerosis, the last few years has witnessed a resurgence, with extensive research re-assessing potential molecular mechanisms and pathways that modulate VSMC behaviour within the atherosclerotic-prone vessel wall and the atherosclerotic plaque itself. Attention has focussed on the pathological contribution of VSMC in plaque calcification; systemic and local mediators such as inflammatory molecules and lipoproteins; autocrine and paracrine regulators which affect cell-cell and cell to matrix contacts alongside cytoskeletal changes. In this brief focused review, recent insights that have been gained into how a myriad of recently identified factors can influence the pathological behaviour of VSMC and their subsequent contribution to atherosclerotic plaque development and progression has been discussed. An overriding theme is the mechanisms involved in the alterations of VSMC function during atherosclerosis.

Genetic inactivation of IL-1 signaling enhances atherosclerotic plaque instability and reduces outward vessel remodeling in advanced atherosclerosis in mice

Clinical complications of atherosclerosis arise primarily as a result of luminal obstruction due to atherosclerotic plaque growth, with inadequate outward vessel remodeling and plaque destabilization leading to rupture. IL-1 is a proinflammatory cytokine that promotes atherogenesis in animal models, but its role in plaque destabilization and outward vessel remodeling is unclear. The studies presented herein show that advanced atherosclerotic plaques in mice lacking both IL-1 receptor type I and apolipoprotein E (Il1r1⁻/⁻Apoe⁻/⁻ mice) unexpectedly exhibited multiple features of plaque instability as compared with those of Il1r1⁺/⁺Apoe⁻/⁻ mice. These features included reduced plaque SMC content and coverage, reduced plaque collagen content, and increased intraplaque hemorrhage. In addition, the brachiocephalic arteries of Il1r1⁻/⁻Apoe⁻/⁻ mice exhibited no difference in plaque size, but reduced vessel area and lumen size relative to controls, demonstrating a reduction in outward vessel remodeling. Interestingly, expression of MMP3 was dramatically reduced within the plaque and vessel wall of Il1r1⁻/⁻Apoe⁻/⁻ mice, and Mmp3⁻/⁻Apoe⁻/⁻ mice showed defective outward vessel remodeling compared with controls. In addition, MMP3 was required for IL-1-induced SMC invasion of Matrigel in vitro. Taken together, these results show that IL-1 signaling plays a surprising dual protective role in advanced atherosclerosis by promoting outward vessel remodeling and enhancing features of plaque stability, at least in part through MMP3-dependent mechanisms.

Hypertension promotes phosphorylation of focal adhesion kinase and proline-rich tyrosine kinase 2 in rats: implication for the pathogenesis of hypertensive vascular disease

Atherosclerosis is initiated by adhesion and infiltration of inflammatory leukocytes into the intima, where non-receptor protein tyrosine kinases, such as focal adhesion kinase (FAK) and proline-rich tyrosine kinase 2 (PYK2), play important roles as intracellular messengers of mechanical and biochemical signals. In the present study, we examined whether FAK and PYK2 are up-regulated by elevated blood pressure or circulating humoral factors in hypertension. We used a rat model of abdominal aortic banding that allows separate evaluation of elevated blood pressure (upper body) and circulating humoral factors (lower body). We obtained the proximal and distal aortas of the banding site, 6 hours, 3 days, and 1 and 4 weeks after the banding procedure, for evaluation of phosphorylation of FAK and PYK2 by Western blotting. Arterial pressure was significantly elevated only in the upper body throughout the experimental period. The expression of FAK and the FAK phosphorylation were significantly increased at 1 and 4 weeks only in the proximal aorta. This was also the case for the expression of total PYK2 and the PYK2 phosphorylation. In contrast, there was no significant change in FAK or PYK2 phosphorylation in the distal aorta, whereas plasma levels of angiotensin II were systemically elevated. In sham-operated rats, no change in FAK or PYK2 phoshorylation was noted in the proximal and distal aortas. These results indicate that phosphorylation of FAK and PYK2 is upregulated by elevated blood pressure but not by humoral factors in the rat aorta, demonstrating novel aspects of atherogenesis in hypertension.

Tumor necrosis factor-alpha increases alkaline phosphatase expression in vascular smooth muscle cells via MSX2 induction

Vascular calcification is implicated in many diseases including atherosclerosis and diabetes. Tumor necrosis factor-alpha (TNF-alpha) has been shown to promote vascular calcification both in vitro and in vivo. However, the molecular mechanism of TNF-alpha-mediated vascular calcification has not yet been fully defined. Therefore, in this study, we aimed to investigate whether MSX2 acts as a crucial regulator in TNF-alpha-induced vascular calcification and to define the regulatory mechanism of MSX2 induction in human vascular smooth muscle cells (VSMCs). TNF-alpha increased the expression of osteogenic marker genes including RUNX2, osterix, alkaline phosphatase (ALP), and bone sialoprotein, and it also promoted matrix mineralization in VSMCs. In addition, TNF-alpha enhanced MSX2 expression in a dose- and time-dependent manner. MSX2 over-expression alone induced ALP expression, whereas knockdown of MSX2 with small interfering RNA completely blocked TNF-alpha-induced ALP expression. New protein synthesis was dispensable for MSX2 induction by TNF-alpha, and the inhibition of NF-kappaB by BAY-11-7082 or by dominant negative IkappaBalpha abolished the TNF-alpha-directed induction of MSX2 expression. However, inhibition of NADPH oxidase did not affect MSX2 expression. In conclusion, our study suggests that TNF-alpha directly induces MSX2 expression through the NF-kappaB pathway, which in turn induces expression of ALP, a key molecule in mineralization, in VSMCs.

Cytokines and the early vein graft: strategies to enhance durability

This brief review focuses on experimental studies linking the proinflammatory cytokine tumor necrosis factor-alpha to accelerated vein graft failure in the broader historical context of vein graft research. From some perspectives, the field appears ripe for transfer of cytokine knowledge and therapeutic approaches that have evolved in other systems to vascular surgery problems. However, the complexity of vein graft disease suggests that more robust research approaches, such as broadening of the scope beyond focus on single mediators and neointimal hyperplasia, will be necessary to reach translatable strategies to prolong human vein graft durability.

Interleukin-1 beta-induced Id2 gene expression is mediated by Egr-1 in vascular smooth muscle cells

OBJECTIVE

Id2 (inhibitor of DNA-binding 2), a member of the helix-loop-helix family of transcription regulators, plays important roles in cell proliferation and differentiation. Recent reports have documented that Id2 is up-regulated during vascular lesion formation and overexpression of Id2 promotes vascular smooth muscle cell (VSMC) proliferation. However, the transcriptional regulation of Id2 gene expression in VSMC remains unexplored.

METHODS AND RESULTS

Using Northern- and Western-blot analyses, we documented that interleukin-1beta (IL-1beta) induced Id2 gene expression in VSMC in a time- and dose-dependent manner. Overexpression of early growth response-1 (Egr-1) in VSMC induced Id2 expression while IL-1beta-induced Id2 expression was abrogated in VSMC by the Egr-1 repressor, NGFI-A binding protein 2 (NAB2), expressed from an adenovirus. Overexpression of Egr-1 transactivated the Id2 promoter in reporter assays dependent on the presence of intact putative Egr-1 binding sites as determined by mutagenesis. Finally, electrophoretic mobility shift assays (EMSA) demonstrated that the Egr-1 protein can bind the Egr-1 sites derived from the human Id2 promoter in vitro and chromatin immunoprecipitation identified the putative Egr-1 site between -723 to -712 as the functional Egr-1 binding site in vivo.

CONCLUSIONS

Our data demonstrate that IL-1beta-induced Id2 expression in VSMC is mediated by the transcription factor Egr-1 in VSMC.

Effect of chronic IL-6 infusion on acute pressor responses to vasoconstrictors in mice

Interleukin (IL)-6 has been implicated as a contributing factor in the pathogenesis of hypertension, although the mechanisms involved are unclear. Studies conducted in vitro suggest that IL-6 may have a direct effect on vascular tone and may modulate constrictor responses to agonists. Whether this effect can be observed in vivo is unknown. Therefore, mice were treated with either IL-6 (16 ng/h sc) or vehicle for 14 days, and the acute blood pressure and heart rate responses to endothelin (ET)-1, angiotensin II (ANG II), and phenylephrine (PE) were assessed under isoflurane anesthesia. Blood pressure responses to ET-1 were identical in vehicle- and IL-6-infused mice, both in the presence and the absence of ganglion blockade with chlorisondamine. The fall in heart rate during ET-1 responses was significantly attenuated in IL-6-infused mice with autonomic reflexes intact (vehicle vs. IL-6, P < 0.05 at 1 and 3 nmol/kg of ET-1), but this difference was not observed after ganglionic blockade. Both blood pressure and heart rate responses to ANG II were indistinguishable between IL-6- and vehicle-infused mice, as were responses to PE except for a significant increase in the blood pressure response and decrease in the heart rate response in IL-6-infused mice observed only at the highest dose of PE (300 microg/kg; P < 0.05). These findings show that, despite what might be predicted from studies conducted in vitro, chronic exposure to elevated plasma IL-6 concentrations in itself does not predispose the mouse to enhanced responsiveness to vasoconstrictors in vivo.

Psoriasis: a possible risk factor for development of coronary artery calcification

BACKGROUND

Psoriasis is a chronic inflammatory skin disorder affecting about 2% of white-skinned individuals. Epidemiological data on the prevalence and degree of coronary artery calcification (CAC) as an indicator for cardiovascular diseases in patients with psoriasis are contradictory.

OBJECTIVES

To study the prevalence and degree of CAC as an indicator for cardiovascular diseases in 32 patients with psoriasis matched for age, sex and risk factors to an equally sized control population.

METHODS

Noncontrast-enhanced 16-row spiral computed tomography was performed in patients and controls.

RESULTS

We found a significantly increased prevalence (59.4% vs. 28.1%, P = 0.015) and severity (CAC score according to Agatston 3.7 vs. 0.0, P = 0.019) of CAC in patients with psoriasis. Multiple linear regression calculations identified psoriasis as a likely independent risk factor for CAC.

CONCLUSIONS

Our results point towards the potentially systemic nature of the inflammatory processes underlying the pathogenesis of psoriasis, which may therefore be considered a potentially severe systemic disease.

Inflammation, endothelial cell activation, and coronary microvascular dysfunction in women with chest pain and no obstructive coronary artery disease

BACKGROUND

Coronary artery microvascular dysfunction is prevalent in women with chest pain in the absence of obstructive coronary artery disease (CAD) and is manifested by attenuated coronary flow reserve (CFR). Markers of inflammation and endothelial cell activation have been found to be elevated in patients with chest pain but without CAD. The relationship between inflammation, endothelial activation, and CFR is not known.

METHODS

Ninety-four women with chest pain in the absence of obstructive angiographic CAD underwent catheterization-based assessment of CFR and measurement of levels of inflammatory markers (n = 78) and endothelial cell activation in the NHLBI WISE study.

RESULTS

Coronary flow reserve did not correlate with levels of C-reactive protein (high-sensitivity C-reactive protein) (rs = -0.07, P = .53), interleukin (IL)-6 (rs = -0.12, P = .31), IL-18 (rs = 0.14, P = .23), tumor necrosis factor alpha (rs = -0.09, P = .43), transforming growth factor beta1 (rs = 0.02, P = .84), and soluble intracellular adhesion molecule-1 (rs = 0.04, P = .68). Median levels of markers of inflammation and endothelial cell activation did not differ between the 57 women with abnormal CFR (< 2.5) and the 37 women with normal coronary microvascular function (high-sensitivity C-reactive protein 0.32 vs 0.25 mg/dL, P = .80; IL-6 2.89 vs 2.39 pg/mL, P = .63; IL-18 218 vs 227 pg/mL, P = .59; tumor necrosis factor alpha 2.7 vs 2.4 pg/mL, P = .43; transforming growth factor beta1 9928 vs 12436 pg/mL, P = .76; soluble intracellular adhesion molecule-1 286 vs 287 pg/mL, P = .95). Multivariable models demonstrated no evidence of associations between markers of inflammation and of endothelial cell activation and CFR.

CONCLUSIONS

Coronary microvascular dysfunction is not associated with markers of inflammation and endothelial cell activation in women with chest pain in the absence of obstructive CAD. These results suggest that inflammation and endothelial cell activation may not play a pathophysiological role in coronary microvascular dysfunction.

Role of histamine produced by bone marrow-derived vascular cells in pathogenesis of atherosclerosis

To clarify the role of histamine-producing cells and its origin in atherosclerosis, we investigated histidine decarboxylase (HDC; histamine-producing enzyme) expression in murine arteries with vascular injuries after the animal had received transplanted bone marrow (BM) from green fluorescent protein (GFP)-transgenic mice. The neointima in the ligated carotid arteries contained BM-derived HDC+ cells that expressed macrophage (Mac-3) or smooth muscle cell antigen (alpha-SMA). In contrast, the HDC+ BM-derived cells, which were positive for Mac-3, were mainly located in the adventitia in the cuff replacement model. In apolipoprotein E-knockout mice on a high cholesterol diet, BM-derived cells expressing Mac-3 in the atheromatous plaques were also positive for HDC. In comparison with wild-type mice, HDC-/- mice showed reduced neointimal thickening and a decreased intima-to-media ratio after ligation and cuff replacement. These results indicate that histamine produced from BM-derived progenitor cells, which could transdifferentiate into SMC- or macrophage-like cells, are important for the formation of neointima and atheromatous plaques.

Inflammatory regulation of extracellular matrix remodeling in calcific aortic valve stenosis

BACKGROUND

Calcific aortic stenosis (AS), the most frequent heart valve disorder in developed countries, leads to the calcification and fibrous thickening of the valve. While several studies have addressed the process of valvular calcification, the molecular pathomechanisms of the extensive matrix remodeling remain unclear. Because inflammation is present in stenotic valves, we hypothesized that the proinflammatory cytokine tumor necrosis factor alpha (TNFalpha) might influence cell proliferation and regulate the expression and activation of matrix metalloproteinases (MMPs)--enzymes that are thought to be involved in calcific AS.

METHODS

Immunohistochemistry for leukocytes, TNFalpha, MMP-1, and the endogenous MMP inhibitor tissue inhibitor of metalloproteinase (TIMP)-1 was performed on human stenotic (n = 19) and control (n = 8) valves. Primary cultures of human aortic valve myofibroblasts were incubated with and without TNFalpha, and cell proliferation was assessed. The expression and activation of MMP-1 were detected by Western blotting and a specific MMP-1 activity assay.

RESULTS

Control valves showed scattered macrophages and low expression of TNFalpha, MMP-1, and TIMP-1. In stenotic valves, leukocyte infiltration and a strong, colocalized expression of TNFalpha and MMP-1 were present, while TIMP-1 remained unchanged. Double-label immunofluorescence localized TNFalpha mainly to macrophages. In cultured human aortic valve myofibroblasts, TNFalpha stimulated proliferation and induced a time-dependent increase in MMP-1 expression and activation, while TIMP-1 remained unchanged.

CONCLUSION

The results indicate that matrix remodeling in calcific AS involves the expression and activation of MMPs. Activated leukocytes, by the secretion of TNFalpha, may stimulate valvular myofibroblasts to proliferate and express MMPs, thus regulating actively the matrix remodeling in calcific AS.

TNFα increases the inflammatory response to vascular balloon injury without accelerating neointimal formation

There is now clear evidence for a contributory role of inflammatory processes to restenosis following vascular balloon injury and stent implantation. The aim of the present study was to study the effects of TNFalpha, administered locally in vivo immediately following balloon angioplasty, on the leukocyte adhesive response and extent of neointimal formation in a rabbit model of subclavian artery injury. Initial in vitro studies were performed with normal isolated artery rings to assess the vascular adhesive response to TNFalpha or IL-1beta. Pre-incubation with either cytokine prior to addition of (51)Cr-labelled leukocytes enhanced the adhesion of leukocytes to the artery in both a time- and concentration-dependent manner. Although both cytokines induced an increase in the expression of the adhesion molecules ICAM-1 and VCAM-1, only antibodies to ICAM-1 blocked the enhanced adhesion induced by the cytokines. In artery segments retrieved from rabbits that had previously undergone subclavian artery angioplasty either 24 h or 8 days previously, there was an injury-induced increase in adhesion of leukocytes assessed ex vivo. In segments obtained from rabbits that received a 15 min local infusion of TNFalpha (2 ng/min) to the injured artery immediately after the angioplasty procedure, leukocyte adhesion assessed ex vivo was further significantly enhanced. The pro-adhesive effect of TNFalpha was associated with an increased expression of both ICAM-1 and VCAM-1. However, TNFalpha administration did not alter the extent of neointimal formation observed 8 days after injury. These findings suggest that while TNFalpha may play a role following vascular injury, it does not act alone to induce neointimal formation. Thus anti-inflammatory strategies targeted at multiple cytokines may be more appropriate than targeting a single cytokine to reduce the response to vascular injury.

Inflammatory triggers of lymphangiogenesis

Inflammation is the common denominator to the postnatal events that overlap with lymphatic vessel growth, or lymphangiogenesis. Undoubtedly, inflammation and accompanying fluid overload are cardinal factors in wound healing, lymphedema, the pathogenesis of some forms of lymphangiomatosis, and solid tumor lymphangiogenesis. The assertion that inflammation actually triggers lymphangiogenesis lies in the evidence set forth below that inflammation is the usual precursor to tissue repair and regeneration. Moreover, the panel of pro-inflammatory and anti-inflammatory molecules that orchestrates the inflammatory response abounds with cytokines and chemokines that foster survival, migration, and proliferation of lymphatic endothelial cells. Finally, both interstitial fluid overload and increased demand for removal of leukocytes can benefit from lymphangiogenesis, although the mechanisms controlling the exit of leukocytes from tissues via the lymphatics are practically unknown. The pertinent question actually is how and why inflammation presents with formation of new lymph vessels in liver fibrosis but not in rheumatoid arthritis. One possible explanation is that organ-specific histological and functional properties of the lymphatic endothelium gauge their response to death, survival, and proliferative factors. Alternatively, the decision to remain quiescent, proliferate or regress resides within the stroma microenvironment.

Interleukin-1 Receptor Signaling Mediates Atherosclerosis Associated With Bacterial Exposure and/or a High-Fat Diet in a Murine Apolipoprotein E Heterozygote Model

BACKGROUND

Current data demonstrate that progressive atherosclerosis is associated with activation of the inflammatory process, as evidenced by systemic elevations of molecules such as tumor necrosis factor, interleukin (IL)-6, and IL-1. It has been postulated that inflammatory events within an atherogenic lesion are induced by oxidized LDL. Recent evidence suggests that infectious agents, including those that cause periodontal disease, may also play an important role. Studies presented here tested the hypothesis that IL-1 receptor (IL-1R1) signaling plays a crucial role in bacteria- and/or high-fat diet (HFD)-enhanced atherogenesis.

METHODS AND RESULTS

Ten-week-old ApoE+/- mice lacking either 1 IL-1R1 allele (ApoE+/-/IL-1R1+/-) or 2 IL-1R1 alleles (ApoE+/-/IL-1R1-/-) fed either an HFD or regular chow were inoculated intravenously with live Porphyromonas gingivalis (P gingivalis) (10(7) CFU), an important periodontal pathogen, or vehicle once per week for 14 or 24 consecutive weeks. Histomorphometry of plaque cross-sectional area in the proximal aortas, en face measurement of plaque area over the aortic trees, and ELISA for systemic proinflammatory mediators were performed. Atherosclerotic lesions of proximal aortas and aortic tree were substantially reduced in ApoE+/-/IL-1R1-/- mice than in ApoE+/-/IL-1R1+/- mice challenged with P gingivalis. At 24 weeks after P gingivalis inoculation, proximal aortic lesion size quantified by histomorphometry was 5-fold-reduced in chow-fed ApoE+/-/IL-1R1-/- mice than in ApoE+/-/IL-1R1+/- mice (P<0.05). In the HFD group, ApoE+/-/IL-1R1-/- mice exhibited marked attenuation of the progression of atherosclerotic lesions (78% to 97%), with and without P gingivalis inoculation (P<0.05).

CONCLUSIONS

Ablation of IL-1R1 under P gingivalis challenge and/or an HFD reduced the progression of atherosclerotic plaques. These results indicate that IL-1 plays a crucial role in bacteria- and/or HFD-enhanced atherogenesis.

Cytokine-induced down-regulation of zfm1/splicing factor-1 promotes smooth muscle cell proliferation

One hallmark of inflammation is the proliferation of bystander cells such as vascular smooth muscle cells (SMC), a process governed by growth factors and cytokines. Whereas cytokine induction of gene products promoting inflammation and proliferation is well characterized, little is known about the concomitant down-regulation of potentially counter-regulatory gene products in these cells. By employing the suppression subtractive hybridization-PCR technique, RNA isolated from rat aortic SMC treated with the cytokines interleukin-1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF alpha) was subtracted from RNA of control cells. Eleven genes were identified, the expression of which fell by 44-77%. One, the transcriptional repressor splicing factor-1 or zfm1, was characterized further. Antisense oligonucleotide suppression of zfm1 protein synthesis mimicked the stimulatory effects of IL-1 beta and TNF alpha on SMC proliferation and expression of the chemokine MCP-1 and the vascular cell adhesion molecule-1. Moreover, in an in vivo mouse model of atherosclerosis, zfm1 abundance was decreased in proliferating arterial SMC. These findings suggest a role for zfm1 in controlling both proliferation and expression of pro-inflammatory gene products in SMC. Therefore, cytokine-induced down-regulation of zfm1 expression may contribute to the pathogenesis of hyperproliferative inflammatory diseases.

Interleukin-10 fails to modulate low shear stress-induced neointimal hyperplasia

INTRODUCTION

Overexpression of the anti-inflammatory cytokine interleukin-10 (IL-10) blocks atherosclerotic events in vivo, and IL-10 has been recently hailed as an "immunologic scalpel" for atherosclerosis. Alternatively, mice lacking IL-10 receiving atherogenic diets have increased occlusive lesions. It remains unclear whether such IL-10 modulation broadly applies to other forms of occlusive arterial remodeling. We hypothesized that lack of IL-10 would exacerbate, and exogenous or overexpression of IL-10 would abrogate low shear stress-induced neointimal hyperplasia (NIH).

METHODS

Wild-type (WT) and IL-10-deficient (IL-10-/-) mice underwent unilateral common carotid artery (CCA) ligation. Low shear stress in the patent ligated artery results in remodeling and formation of neointima containing BrdU and SMC alpha-actin-positive cells. Additional groups of WT mice underwent CCA ligation and were treated daily with intraperitoneal saline or 1 microg of human IL-10. Chronic delivery gene therapy approaches were also utilized to define the role of IL-10 signaling. WT mice were treated adventitially with 1 x 10(10) adenovirus/green fluorescent protein (Ad/gfp) and an Ad/empty control to confirm the veracity of adventitial delivery. Then, Ad viral IL-10 (vIL-10), Ad/empty, and virus buffer alone were applied directly to the adventitia of the CAA immediately following ligation. In separate experiments, 1 x 10(10) Ad/empty or Ad/vIL-10 was injected intramuscularly. CCAs were perfusion fixed 28 days postligation, the time at which NIH is near maximum.

RESULTS

IL-10-/- mice developed identical NIH areas compared to WT controls. Mice receiving IL-10 demonstrated NIH equivalent to saline controls. Mice receiving intramuscular or adventitial Ad/IL-10 developed high serum levels of IL-10 yet formed NIH areas similar to those of controls. Serum IL-10 levels were significantly higher (P = 0.04) with adventitial delivery. Mice treated adventitially with Ad/gfp showed reliable transfection of cells within the adventitia of CAA. No antibody to human IL-10 was found in the sera of intraperitoneal IL-10-treated mice, which failed to attenuate NIH.

CONCLUSION

Under the conditions of this experiment, lack of IL-10 does not exacerbate low shear stress-induced NIH, nor does exogenous administration or overexpression of IL-10 attenuate it. Despite high serum levels of vIL-10 in mice treated with ad/vIL-10 adventitially, there appears to be no therapeutic effect despite the confirmed transfection of adventitial cells. Discrepancies between these findings and previous research may be related to IL-10 dosing, inflammation induced by the adenoviral vector, or disparities between the NIH models.

Inflammation as a key event in the development of neointima following vascular balloon injury

1. The present review discusses the current evidence to implicate leucocytes as key players in the development of neointima in arteries that have been subjected to balloon angioplasty injury. 2. There is substantial clinical evidence that leucocytes are activated after angioplasty, as determined by increased plasma levels of both leucocyte granulation products and soluble leucocyte and endothelial cell adhesion molecules. 3. Experimental evidence to implicate leucocytes in neointimal formation comes from studies that demonstrate leucocyte accumulation occurs within the vascular wall soon after injury and that induction of leukopenia prevents neointimal formation. 4. The evidence implicating specific adhesion molecules and cytokines in the key events leading to neointimal formation is discussed.

Adenovirus-mediated transfer of dominant-negative rho-kinase induces a regression of coronary arteriosclerosis in pigs in vivo

Small GTPase Rho and its target Rho-kinase/ROK/ROCK play an important role in various cellular functions, including smooth muscle contraction, actin cytoskeleton organization, and cell adhesion and migration, all of which may be involved in the pathogenesis of arteriosclerosis. Here, we show that adenovirus-mediated transfer of dominant-negative Rho-kinase (DNRhoK) induces a marked regression of coronary constrictive remodeling and abolishes coronary vasospastic activity in vivo. Porcine coronary segments were chronically treated with interleukin-1beta, which resulted in the development of constrictive remodeling and vasospastic responses to serotonin, as previously reported. Adenovirus-mediated transfer of DNRhoK, but not that of beta-galactosidase, into the interleukin-1beta-treated coronary segment caused a marked regression of the constrictive remodeling and abolished the vasospastic activity in 3 weeks. Western blot analysis showed that the phosphorylation of adducin and the ezrin/radixin/moesin family, the target proteins of Rho-kinase, were upregulated at the coronary lesions and were significantly suppressed by the transfer of DNRHOK: These results indicate that Rho-kinase is substantially involved in coronary constrictive remodeling and vasospastic responses, both of which can be reversed by the selective inhibition of the molecule in our porcine model in vivo.

Role of cytokines in the pathogenesis of restenosis after percutaneous transluminal coronary angioplasty

BACKGROUND

Inflammatory cytokines play an important role in mediating inflammatory/proliferative responses including atherosclerosis. However, their role in the pathogenesis of restenosis after percutaneous transluminal coronary angioplasty (PTCA) remains to be clarified.

OBJECTIVE

To determine plasma levels of inflammatory cytokines as well as cytokine-generation capacities of monocytes before PTCA and after the follow-up period.

METHODS

Plasma levels of cytokines in 34 consecutive patients before and 3-6 months after PTCA were measured by enzyme-linked immunosorbent assay. We measured the plasma levels of macrophage-colony-stimulating factor (MCSF) and transforming growth factor-beta. Cytokine-generation capacities of monocytes were also measured by a whole-blood induction method with lipopolysaccharide. The levels of cytokines measured for assessment of the capacities included those of interleukin-1alpha, interleukin-1beta, interleukin-6, granulocyte-colony-stimulating factor, tumor necrosis factor-alpha and interferon-gamma.

RESULTS

Plasma levels of MCSF in patients without restenosis (n = 20) decreased significantly (from 1460+/-138 microg/ml before PTCA to 1039+/-125 microg/ml after the follow-up period, P < 0.01), whereas those in patients with restenosis (n = 14) increased significantly (from 1107+/-105 microg/ml before PTCA to 1039+/-125 microg/ml after the follow-up period, P < 0.05). We noted a positive correlation between the increase in plasma levels of MCSF and the extent of loss of lumen by restenosis. Cytokine-generation capacities of monocytes for interleukin-1alpha and interleukin-1beta of patients with restenosis significantly increased but those of patients without restenosis did not. Furthermore, plasma levels of C-reactive protein decreased significantly only in patients without restenosis after the follow-up period.

CONCLUSIONS

These results suggest that inflammatory changes mediated by cytokines may be involved in the pathogenesis of restenosis after PTCA.

Quantitative analysis of gene expressions related to inflammation in canine spastic artery after subarachnoid hemorrhage

BACKGROUND AND PURPOSE

The possible role of inflammatory reaction of the cerebral artery in the pathogenesis of cerebral vasospasm has been noted in recent studies. We quantitatively measured the levels of expression of genes related to inflammation in the spastic artery in a canine double-hemorrhage model.

METHODS

Twenty dogs were assigned to 4 groups: group D0, control; group D2, dogs killed 2 days after cisternal injection of blood; group D7, dogs given double cisternal injections of blood and killed 7 days after the first injection; and group D14. Angiography was performed twice: on the first day and before the animals were killed. Total RNA was extracted from the basilar artery. The expressions of interleukin (IL)-1alpha, IL-6, IL-8, IL-10, tumor necrosis factor-alpha, E-secretin, fibronectin, intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule-1, transforming growth factor-ss, basic fibroblast growth factor, and collagen types I, III, and IV were examined with TaqMan real-time quantitative reverse transcription-polymerase chain reaction.

RESULTS

Prolonged arterial narrowing peaking on 7 day was observed. There was a significant difference in vessel caliber between D0, D2, D7, and D14 groups (P:<0.0001). There were significant differences in mRNA expression in the basilar artery for IL-1alpha, IL-6, IL-8, ICAM-1, and collagen type I between D0, D2, D7, and D14 groups (P:=0.0079, 0. 0196, 0.0040, 0.0017, and <0.0001, respectively). The average level of mRNA was highest in D7 for IL-1alpha, IL-6, IL-8, and ICAM-1 (17-, 16-, 131-, and 1.7-fold compared with those of D0, respectively) and in D14 for collagen type I (10.9-fold).

CONCLUSIONS

Increased expression of genes related to inflammation in the spastic artery suggests that inflammatory reaction of the cerebral artery is associated with sustained contraction.

Restenosis after balloon angioplasty of coarctation: relationship with ductus arteriosus

BACKGROUND

Recently, balloon angioplasty (BA) has been used for the treatment of coarctation of the aorta (CoA) and the effectiveness of this treatment has been reported. However, the restenosis rate following BA in native CoA in the infant is high and the cause may be related to tissue properties at the origin of the ductus arteriosus (DA). However, the mechanisms responsible for restenosis remain uncertain.

METHODS/RESULTS

The present study was designed to examine transformation of the smooth muscle cell (SMC) phenotypes using immunohistologic studies and to investigate the cause of restenosis of CoA following BA. A CoA model was surgically created in 15 newborn pigs (10-14-days-old; 2.4-4.1 kg). Balloon angioplasty was performed 1 month after the initial operation. One or 3 months after BA, animals were killed and immunohistologic studies on smooth muscle cell (SMC) antibodies against SM1, SM2 and SMemb of the myosin heavy chain (MHC) isoform were performed in the aorta at the CoA and DA. In the neointima, only SMemb was positive. In the SMC layer of the DA, only SM2 was positive. One month after BA, the external layer of the tunica media was strongly positive for SM2 only in the area around the origin of the DA.

CONCLUSIONS

The first cause of restenosis is obstructive neointimal formation caused by the proliferation of undifferentiated SMC into the subendothelial tissue. This proliferation seems to be triggered by BA. The distribution of SM2 1 month after balloon angioplasty showed a similar pattern of proliferation of SMC in the external layer around the DA. This may represent a second mechanism of restenosis.

Tumor necrosis factor-alpha promotes in vitro calcification of vascular cells via the cAMP pathway

BACKGROUND

Vascular calcification is an ectopic calcification that commonly occurs in atherosclerosis. Because tumor necrosis factor-alpha (TNF-alpha), a pleiotropic cytokine found in atherosclerotic lesions, is also a regulator of bone formation, we investigated the role of TNF-alpha in in vitro vascular calcification.

METHODS AND RESULTS

A cloned subpopulation of bovine aortic smooth muscle cells previously shown capable of osteoblastic differentiation was treated with TNF-alpha, and osteoblastic differentiation and mineralization were assessed. Treatment of vascular cells with TNF-alpha for 3 days induced an osteoblast-like morphology. It also enhanced both activity and mRNA expression of alkaline phosphatase, an early marker of osteoblastic differentiation. Continuous treatment with TNF-alpha for 10 days enhanced matrix mineralization as measured by radiolabeled calcium incorporation in the matrix. Pretreatment of cells with a protein kinase A-specific inhibitor, KT5720, attenuated cell morphology, the alkaline phosphatase activity, and mineralization induced by TNF-alpha. Consistent with this, the intracellular cAMP level was elevated after TNF-alpha treatment. Electrophoretic mobility shift assay demonstrated that TNF-alpha enhanced DNA binding of osteoblast specific factor (Osf2), AP1, and CREB, transcription factors that are important for osteoblastic differentiation.

CONCLUSIONS

These results suggest that TNF-alpha enhances in vitro vascular calcification by promoting osteoblastic differentiation of vascular cells through the cAMP pathway.

Rho-kinase is involved in macrophage-mediated formation of coronary vascular lesions in pigs in vivo

We have previously shown that long-term treatment with an inflammatory cytokine from the adventitia causes the development of coronary vascular lesions, with the accumulation of macrophages. Recent studies in vitro have suggested that small G-protein Rho and its effector, Rho-kinase/ROK/ROCK, may be the key molecules for various cellular functions, including cell adhesion and movement. In this study, we examined whether adventitia-derived macrophages cause the formation of coronary vascular lesions in vivo and, if so, whether Rho-kinase is involved in the process. Porcine coronary segments from the adventitia were chronically treated with monocyte chemoattractant protein-1 alone, oxidized low density lipoprotein alone, or both. Vascular lesion formation (neointimal formation and development of vascular remodeling) was mostly enhanced at the coronary segment cotreated with monocyte chemoattractant protein-1 and oxidized low density lipoprotein, where the phosphorylation of myosin binding subunit of myosin phosphatase was increased, indicating an increased activity of Rho-kinase in vivo. Histological examination demonstrated that macrophages were accumulated at the adventitia and thereafter migrated into the vascular wall. Long-term oral treatment with fasudil, which is metabolized to a specific Rho-kinase inhibitor (hydroxyfasudil) after oral absorption, markedly inhibited the myosin binding subunit phosphorylation, the macrophage accumulation and migration, and the coronary lesion formation in vivo. These results indicate that Rho-kinase is involved in macrophage-mediated formation of coronary vascular lesions in our porcine model in vivo.

Direct evidence for cytokine involvement in neointimal hyperplasia

BACKGROUND

Tumor necrosis factor-alpha (TNF-alpha) and interleukin 1 (IL-1) are proximal inflammatory cytokines that stimulate expression of adhesion molecules and induce synthesis of other proinflammatory cytokines. In addition, TNF-alpha and IL-1 influence vascular smooth muscle cell migration and proliferation in vitro. In view of the inflammatory nature of neointimal hyperplasia (NIH), we tested the hypothesis that endogenous TNF-alpha and IL-1 modulate low shear stress-induced NIH.

METHODS AND RESULTS

Mice underwent unilateral common carotid artery (CCA) ligation. Low shear stress in the patent ligated CCA has previously been shown to result in remodeling and NIH. Reverse transcriptase-polymerase chain reaction for TNF-alpha and IL-1alpha mRNA demonstrated both TNF-alpha and IL-1alpha mRNA in ligated CCAs, whereas normal and sham-operated CCAs had none. Mice lacking functional TNF-alpha (TNF-/-) developed 14-fold less neointimal area than WT controls (P:<0.05). p80 IL-1 type I receptor knockout (IL-1RI-/-) mice tended to develop less (7-fold, P:>0.05) neointimal area than WT controls. Furthermore, no IL-1alpha mRNA expression was detected in CCAs from TNF-/- mice; however, TNF-alpha mRNA expression was found in the IL-1RI-/- mice. Mice that overexpress membrane-bound TNF-alpha but produce no soluble TNF-alpha display an accentuated fibroproliferative response to low shear stress (P:<0.05).

CONCLUSIONS

These results directly demonstrate that TNF-alpha and IL-1 modulate NIH induced by low shear stress. NIH can proceed by way of soluble TNF-alpha-independent mechanisms. Specific anti-TNF-alpha and anti-IL-1 therapies may lessen NIH.

Specific cellular features of atheroma associated with development of neointima after carotid endarterectomy: the carotid atherosclerosis and restenosis study

BACKGROUND

The purpose of this study was to investigate whether some cellular and molecular features of tissue retrieved at carotid endarterectomy are associated with the extent of neointima formation at ultrasound follow-up.

METHODS AND RESULTS

One hundred fifty patients were studied. Endarterectomy specimens were tested by immunocytochemistry with the use of (1) monoclonal antibodies that identify smooth muscle cells (SMCs) and fetal-type SMCs on the basis of smooth muscle and nonmuscle myosin content, (2) the anti-macrophage HAM 56, and (3) the anti-lymphocyte CD45RO. The maximum intima-media thickness (M-IMT) of the revascularized vessel was assessed by the use of B-mode ultrasonography 6 months after surgery. The M-IMT values were related positively to the number of SMCs (r=0.534, P<0.0005) and negatively to that of macrophages and lymphocytes (r=-0.428, P<0.0005, and -0.538, P=0.001, respectively). Patients were classified as class 1 (M-IMT </=1.0 mm), class 2 (1. 0<M-IMT</=1.3 mm), and class 3 (M-IMT >1.3 mm). An abundance of SMCs, mostly of fetal type, was found in the plaque of class 3 patients, whereas lesions from class 1 patients were rich in macrophages and lymphocytes. In the multivariate analysis, factors related to M-IMT were the number of SMCs and the percentage of fetal-type SMCs present in the plaque.

CONCLUSIONS

Although the classic risk factors did not play a role, an abundance of SMCs and a scarcity of macrophages characterized the primary lesion of patients in whom neointima developed after surgery. In patients in whom neointima did not develop, lesions were rich in macrophages and lymphocytes. This approach can be useful in defining patients at risk of restenosis.

Gene transfer of dominant negative Rho kinase suppresses neointimal formation after balloon injury in pigs

Restenosis after angioplasty still remains a major problem for which neointimal formation appears to play an important role. Recent studies in vitro suggested that Rho kinase, a target protein of Rho, is important in various cellular functions. We thus examined whether Rho kinase is involved in the restenotic changes after balloon injury. In vivo gene transfer was performed immediately after balloon injury in both sides of the porcine femoral arteries with adenoviral vector encoding either a dominant negative form of Rho kinase (AdDNRhoK) or beta-galactosidase (AdLacZ) as a control. One week after the transfer, immunohistochemistry confirmed the successful gene expression in the vessel wall, whereas 2 wk after the transfer, Western blotting showed the functional upregulation of Rho kinase at the AdLacZ site and its suppression at the AdDNRhoK site. Angiography showed the development of a stenotic lesion at the AdLacZ site where histological neointimal formation was noted, whereas those changes were significantly suppressed at the AdDNRhoK site. These results indicate that Rho kinase is involved in the pathogenesis of neointimal formation after balloon injury in vivo.