Cytomegalovirus replication is not a cause of instability in unstable angina

Human cytomegalovirus-IgM seropositivity is not associated with atherogenic alterations of lipid profiles and inflammatory status in ischemic stroke patients: a preliminary study

BACKGROUND

Past exposure to human cytomegalovirus has been suggested to participate in the pathogenetic events associated with atherosclerotic lesion establishment and progression. However, whether ongoing human cytomegalovirus infection is related to plaque instability, and subsequent acute cerebral ischemia, is relatively unknown. The purpose of this study was to evaluate the potential relationships between active human cytomegalovirus infection and ischemic stroke, especially in regard to metabolism and inflammation.

METHODS

Ninety-nine acute ischemic stroke patients, associated with large artery atherosclerosis, were divided into two groups based on the presence or absence of human cytomegalovirus immunoglobulin M (IgM) (human cytomegalovirus-IgM-positive/human cytomegalovirus-IgM-negative = 33:66). Baseline clinical characteristics, inflammatory factors, and biochemical assessments were compared in both groups. Then, all patients and human cytomegalovirus-IgM-positive patients were divided into quartiles according to their high-sensitivity C-reactive protein levels, respectively, and risk factors were compared. Finally, correlations between inflammatory factors (high-sensitivity C-reactive protein and white blood cell count) and other atherosclerosis risk factors in both human cytomegalovirus-IgM-positive and -negative subjects were evaluated.

RESULTS

An association between human cytomegalovirus-IgM seropositivity and atherogenic modification of metabolism and inflammatory status were not found in this study. Both age and white blood cell count increased across quartiles of high-sensitivity C-reactive protein in all subjects (P = 0.001), while age and low-density lipoprotein cholesterol increased across quartiles of high-sensitivity C-reactive protein in the human cytomegalovirus-IgM-positive group (P = 0.02 and 0.007, respectively). Multivariate linear regression analysis showed that high-sensitivity C-reactive protein was associated with age in human cytomegalovirus-IgM-positive group (P = 0.002), while no other factor was associated with white blood cell count in these subjects.

CONCLUSION

Our study provided no evidence for the direct implication of active systemic human cytomegalovirus infection, represented by human cytomegalovirus-IgM positivity, in the pathogenesis of acute ischemic strokes, particularly those involving plaque instability and metabolic disorders.

Cytomegalovirus localization in atherosclerotic plaques is associated with acute coronary syndromes: report of 105 patients

It has been shown that cytomegalovirus (CMV) is present in coronary atherosclerotic plaques, but the clinical relevance of this presence remains to be elucidated. In this study we sought to examine CMV infection in atherosclerosis patients defined by different methods and to identify the clinical significance of CMV replication in the atherosclerotic plaques. The study included 105 consecutive patients who were admitted to our department and underwent coronary artery bypass grafting (CABG) surgical interventions. Coronary atherosclerotic specimens as well as 53 specimens from the mamillary artery of these same patients were analyzed. Enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) methods were used for evaluations. The CMV PCR test result was positive for 28 (26.7%) of patients with coronary artery atherosclerosis. After adjusting for other risk factors, coronary artery disease patients with a history of acute coronary syndrome were more likely to be positive for CMV PCR test (P=0.027; odds ratio: 4.2; 95% CI: 1.18-15.0). They were also more likely to have a positive family history for cardiovascular diseases (CVD). This study confirms previous evidence about the replication of CMV virus in the atherosclerotic plaques of coronary arteries and brings clinical significance to this observation by showing a higher prevalence of acute coronary syndromes in those patients with CMV-infected plaques. Our study also suggests a familial vulnerability to CMV replication in the coronary artery walls.

Chronic infection in the etiology of atherosclerosis--the case for Chlamydia pneumoniae

Established cardiovascular risk factors do not fully explain the variations in the prevalence and severity of coronary heart disease. Recent evidence suggests that common chronic infections may contribute, either by direct or indirect mechanisms, to the etiology and/or progression of coronary atherosclerosis. Of the candidate infectious agents implicated, Chlamydia pneumoniae has emerged as the most likely pathogen to have a causal role. Evidence for this is based on seroepidemiologic, pathologic, and laboratory-based evidence, in addition to recent small-scale antibiotic intervention studies. Concerted efforts are now focused on the design of large prospective trials with antibiotics active against C. pneumoniae in the secondary prevention of coronary heart disease.

In vivo reduction of the nuclear factor-kappaB activity using synthetic cis-element decoy oligonucleotides suppresses intimal hyperplasia in the injured carotid arteries in rabbits

PURPOSE

Nuclear factor-kappaB (NF-kappaB) plays a critical role in inflammation-related reactions, and is also found in the injured arterial wall. The purpose of this study was to introduce synthetic double-stranded cis-element "decoy" oligonucleotides (ODNs) into the arterial wall using the hemagglutinating virus of Japan (HVJ) liposome, and to investigate the inhibitory potential of decoy ODN against balloon injury-induced intimal hyperplasia by reducing NF-kappaB activity.

METHODS

Fluorescein isothiocyanate (FITC)-labeled decoy ODNs using the HVJ-liposome method were tranfected in balloon-injured rabbit carotid arteries. We then performed electrophoretic mobility shift assay to examine NF-kappaB activity using balloon-injured arteries, and we introduced NF-kappaB decoy into balloon-injured arteries.

RESULTS

Transfection of FITC-labeled decoy ODNs by using the HVJ-liposome method demonstrated highly efficient protein expression with diffuse, frequent, and widespread nuclear signals over the entire medial layer, while the same amount of naked ODNs showed much less efficiency with scattered distribution of fluorescence in balloon-injured carotid arteries. Electrophoretic mobility shift assay showed activation of NF-kappaB in balloon-injured arteries. In vivo transfection of decoy ODNs mediated by HVJ liposome abolished the NF-kappaB activity in injured arteries with specific binding affinity to NF-kappaB protein. Intimal hyperplasia of carotid artery after balloon injury was reduced by approximately 50% by NF-kappaB decoy transfection compared with buffer treatment or scrambled decoy transfection.

CONCLUSION

Our results demonstrated involvement of NF-kappaB in intimal formation after arterial injury, and indicated that NF-kappaB can be an appropriate molecular target for anti-restenosis therapy.

Persistent infection and vascular disease: a systematic review

More than 150 epidemiological or clinical studies have reported on associations between vascular disease and the presence of certain persistent bacterial and viral agents, or of clinical conditions (e.g., periodontal disease) that are associated with persistent infection. This article provides a review of such studies, particularly in relation to Helicobacter pylori, Chlamydia pneumoniae, dental disease and cytomegalovirus (CMV), as well as references to possible mechanisms. The association between coronary heart disease and H. pylori or between heart disease and dental disease may be accounted for by residual confounding. Although markers of C. pneumoniae infection are around twenty times more common in atherosclerotic plaques than in disease-free blood vessels, the sequence of infection and disease is uncertain. For CMV, a limited number of patients with classic atherosclerotic coronary heart disease have been investigated in seroepidemiological studies. For all such agents, better and larger seroepidemiological and pathology-based studies are needed to resolve these uncertainties, as well as - at some stage - large-scale, randomised intervention studies.

The mechanisms by which infectious agents may contribute to atherosclerosis and its clinical manifestations

Three infectious agents have recently gained considerable interest as potential pathogens in atherosclerosis and in its clinical manifestations: herpes simplex virus, cytomegalovirus, and Chlamydia pneumoniae. Chronic and often asymptomatic infections with these agents occur widely in the general population. These pathogens may affect atherosclerosis either directly or indirectly. Direct effects on vascular wall cells might include cell lysis, transformation, lipid accumulation, proinflammatory changes, and augmentation of procoagulant activity. Indirect systemic effects may involve induction of acute-phase proteins, establishment of a prothrombotic state, hemodynamic stress caused by tachycardia, increased cardiac output, or a regional inflammatory activation in response to systemic endotoxemia and cytokinemia. The effects of microbial infection, usually in combination with other risk factors (for example, smoking, hyperlipidemia, family history), might promote atherogenesis and eventually trigger acute coronary events.

Upregulation of CD40 expression on endothelial cells infected with human cytomegalovirus

CD40 has been identified as an important molecule for a number of processes, such as immune responses, inflammation, and the activation of endothelia. We investigated CD40 in endothelial cells (EC) following infection with an endotheliotropic strain of human cytomegalovirus (HCMV). Between 8 and 72 h postinfection, we observed a significant increase in CD40 levels on the surface of infected EC, as measured by fluorescence-activated cell sorting analysis. As a consequence of CD40 upregulation, increased levels of E-selectin were found on infected EC after stimulation with CD154-expressing T cells. Enhanced expression of CD40 was specific for EC, since infection of fibroblasts did not result in the upregulation of CD40. The addition of neutralizing antibodies as well as UV inactivation of virus completely prevented the upregulation of CD40 on EC. Also, laboratory-adapted HCMV strain AD169 was not able to induce CD40 on EC. De novo protein synthesis was necessary for the increased surface expression. At early times (4 to 24 h) postinfection, this change was not accompanied by increased levels of CD40 protein or mRNA. At late times (48 to 96 h) postinfection, increased amounts of CD40 protein and mRNA were detected. Immunohistochemical analysis of infected tissues demonstrated elevated levels of CD40 on HCMV-infected EC in vivo. Thus, infection of EC by HCMV may result in the activation of endothelia and in the augmentation of inflammatory processes.

Inflammation and immune system response against unstable angina and its relationship with coronary angiographic findings

The aim of this study was to assess the relations between inflammation, immune response, and coronary angiographic findings in patients with unstable angina pectoris (UAP). Recent studies suggest a role for inflammation in the pathophysiology of UAP. Although activation of neutrophils, monocytes and lymphocytes has been shown in UAP, no studies have correlated the activation findings with clinical and angiographic features of patients with UAP. Seventy-three patients undergoing coronary angiography were classified according to their ischaemic syndrome, stable angina pectoris (SAP) (n = 25) and UAP (n = 48). Patients with UAP were classified using the Braunwald classification; UAP class I (n = 15), UAP class II (n = 15), and UAP class III (n = 18). Patients with UAP were also classified into a progression to myocardial infarction (MI (+)) group (n = 15) and a non-progression to myocardial infarction (MI(-)) group (n = 33). Venous blood samples were taken from all patients. Cell surface receptors (CD4, CD8, CD3, CD14, CD45, CD56+16, and HLA-DR) were detected by flow cytometry using monoclonal antibodies tagged with fluorescent markers and serum levels of C-reactive protein (CRP) were measured. The serum levels of CRP and the percentages of HLA-DR, CD14, and CD16+56 were higher in UAP than SAP. The serum levels of CRP and percentages of HLA-DR, CD14, and CD16+56 were higher in UAP class II than UAP class I. The serum levels of CRP and percentages of HLA-DR, CD14, and CD16+56 were higher in UAP class III than UAP class II and UAP class I. The serum levels of CRP and percentages of CD16+56 were higher in the MI(+) group than the MI(-) group. The CRP levels in serum and the percentages of cell surface antigens had no correlation with extent of coronary artery disease (no differences among one, two or three vessels) but Type C lesion had significantly higher percentages of HLA-DR, CD14, CD16+56 and the serum levels of CRP than Type A and Type B lesions. This investigation shows that inflammatory and immunologial components may be detectable in UAP and were correlated with the clinical severity, progression to myocardial infarction, and lesion morphology, but were not correlated with the extent of coronary artery disease.

Chronic infection in the aetiology of atherosclerosis--focus on Chlamydia pneumoniae

An inflammatory basis to atherosclerosis is now accepted. It remains plausible (but unproven) that common infectious agents may contribute to the inflammatory signal, and hence the development (and/or progression of atherosclerosis and its clinical sequelae. Of the candidate microorganisms implicated, Chlamydia pneumoniae has emerged as the most likely pathogen to have a casual role. Evidence for this is based on sero-epidemiological, pathological and laboratory-based evidence, in addition to early animal models and small-scale antibiotic studies. A past decade of research has now culminated in prospective antibiotic intervention trials in coronary heart disease to be conducted. The results of these studies should help to finally determine whether infection with C. pneumoniae is a pathogenetic factor in atherosclerosis, and whether antibiotic therapy has a role in the secondary prevention of coronary heart disease.

Immune system activation follows inflammation in unstable angina: pathogenetic implications

OBJECTIVES

The aim of this study was to assess the relations between inflammation, specific immune response and clinical course in unstable angina (UA).

BACKGROUND

Several studies suggest that either inflammation and/or T-cell activation might have a pathogenetic role in UA, but neither their potential reciprocal connection nor their relation to the clinical course is known.

METHODS

Serum levels of C-reactive protein (CRP) (inflammation), IgG, IgA, IgM, C3, C4 (humoral immunity), IL-2 and the percentage of CD4+, CD8+ and CD3+/DR+ T-cells (cell-mediated immunity) were measured in 35 patients with UA and 35 patients with chronic stable angina (CSA) during a period of 6 months.

RESULTS

The CRP levels and the main specific immune markers (CD4+ and CD3+/DR+ cells, IL-2 and IgM) were higher in unstable than in stable angina. In UA, the serum levels of IgM and IL-2 and the percentage of double positive CD3+/DR+ significantly increased at 7 to 15 days, and returned to baseline at 6 months. The increment of circulating activated T cells (CD3+/ DR+) in UA was inversely related to the admission levels of CRP (r=-0.63, p=0.003) and associated with a better outcome.

CONCLUSIONS

Our data suggest that the inflammatory component systemically detectable in UA may be antigen-related and that the magnitude of the immune response correlates with the clinical outcome of instability.

Interferon gamma regulates acute and latent murine cytomegalovirus infection and chronic disease of the great vessels

To define immune mechanisms that regulate chronic and latent herpesvirus infection, we analyzed the role of interferon gamma (IFN-gamma) during murine cytomegalovirus (MCMV) infection. Lethality studies demonstrated a net protective role for IFN-gamma, independent of IFN-alpha/beta, during acute MCMV infection. Mice lacking the IFN-gamma receptor (IFN-gammaR-/-) developed and maintained striking chronic aortic inflammation. Arteritis was associated with inclusion bodies and MCMV antigen in the aortic media. To understand how lack of IFN-gamma responses could lead to chronic vascular disease, we evaluated the role of IFN-gamma in MCMV latency. MCMV-infected IFN-gammaR-/- mice shed preformed infectious MCMV in spleen, peritoneal exudate cells, and salivary gland for up to 6 mo after infection, whereas the majority of congenic control animals cleared chronic productive infection. However, the IFN-gammaR was not required for establishment of latency. Using an in vitro explant reactivation model, we showed that IFN-gamma reversibly inhibited MCMV reactivation from latency. This was at least partly explained by IFN-gamma- mediated blockade of growth of low levels of MCMV in tissue explants. These in vivo and in vitro data suggest that IFN-gamma regulation of reactivation from latency contributes to control of chronic vascular disease caused by MCMV. These studies are the first to demonstrate that a component of the immune system (IFN-gamma) is necessary to regulate MCMV-associated elastic arteritis and latency in vivo and reactivation of a herpesvirus from latency in vitro. This provides a new model for analysis of the interrelationships among herpesvirus latency, the immune system, and chronic disease of the great vessels.

Is there an infective aetiology to atherosclerosis?

Conventional cardiovascular risk factors fail to completely explain the observed variations in the prevalence and severity of coronary heart disease (CHD). Common chronic infections may have an aetiological role in the development of atherosclerosis and CHD, either independently or by interacting with traditional atherogenic risk factors. The evidence for Chlamydia pneumoniae as a potential causative agent is strongest, and is based on findings of numerous sero-epidemiological studies, examination of atheromatous plaque specimens, in vitro animal models and, recently, pilot antichlamydial antibiotic intervention trials. However, the complete natural history of C. pneumoniae, its mechanisms of damage in atherosclerotic disease, and the temporal sequence of infection and CHD remain unclear. Confirmation of true causality for the link between C. pneumoniae and CHD could come after the results of large-scale prospective antibiotic trials, which are to be conducted over the next few years. A proven association could have important implications for public health worldwide, potentially leading to novel and relatively inexpensive therapeutic measures in the secondary prevention of CHD--broad-spectrum antibiotics.

Role of inflammation in the pathogenesis of unstable coronary artery disease

In this article, the clinical, angiographic, and postmortem features of unstable angina are reviewed and its pathogenesis is discussed. Coronary plaque inflammation may play a key role in the pathogenesis of unstable angina and the evidence for this assertion is examined. Finally, the therapeutic implications of the involvement of inflammation in acute coronary syndromes are outlined.

Chronic infections and coronary heart disease: is there a link?

A large number of studies have reported on associations of human coronary heart disease (CHD) and certain persistent bacterial and viral infections. We review the epidemiological and clinical evidence on CHD and Helicobacter pylori, Chlamydia pneumoniae, and cytomegalovirus (CMV), as well as possible mechanisms. The association between CHD and H pylori may be accounted for by residual confounding from risk factors. Although the association between C pneumoniae and CHD is stronger, the sequence of infection and disease is uncertain. As regards CMV, a limited number of patients with classic atherosclerotic coronary artery disease have been studied. Further studies are needed to resolve these uncertainties.

The immediate early gene of human cytomegalovirus stimulates vascular smooth muscle cell proliferation in vitro and in vivo

Cytomegalovirus (CMV) infection has been carefully studied regarding the relationship with the vascular smooth muscle cell (VSMC) proliferation in either atherosclerosis or post-angioplasty restenosis, but its role in the vessel wall has yet to be elucidated. To clarify the pathogenic ability of CMV in the vessel wall, we transduced the immediate early (IE) gene of CMV into the VSMCs and endothelial cells (ECs) by hemagglutinating virus of Japan-liposome method. The in vitro IE gene transfer demonstrated that the conditioned medium of IE gene transferred ECs enhanced [3H]-thymidine uptake of VSMCs. The enhanced proliferation of the IE gene transferred VSMCs was observed after the stimulation by basic fibroblast growth factor. The in vivo IE gene transfer showed neointimal thickening while the control arteries did not. These findings thus suggest that the expression of CMV-IE gene in the vessel wall may play a role in the fibrocellular neointimal formation or progression of atherosclerosis in vivo.