Association between prior cytomegalovirus infection and the risk of restenosis after coronary atherectomy

Independent and joint effects of antibodies to human heat-shock protein 60 and Chlamydia pneumoniae infection in the development of coronary atherosclerosis

BACKGROUND

Studies have suggested that the prevalence of antibodies against heat-shock proteins (HSPs), Chlamydia pneumoniae (CPN), and cytomegalovirus (CMV) is associated with coronary artery disease (CAD), but the independent or joint effects of human (h) HSP60 antibodies and these pathogens in patients have not been fully elucidated.

METHODS AND RESULTS

A total of 405 subjects (276 patients with CAD and 129 control individuals) were tested for serum antibodies to hHSP60, CPN, and CMV immediate-early-1 (IE1) antigens. Patients were also assessed for serum cholesterol, triglyceride levels, and smoking habit. Significantly elevated levels of antibodies to hHSP60 and CPN but not to CMV-IE1 antigens were documented in CAD patients. Multiple logistic regression analysis and subanalyses of selected subjects showed that these associations were independent of age, sex, smoking, and serum lipid levels. Antibodies to hHSP60 and CPN did not correlate quantitatively; however, the relative risk of disease development was substantially increased in subjects with high antibody levels to both hHSP60 and CPN:, reaching an odds ratio of 82.0 (95% CI 10.6 to 625.0).

CONCLUSIONS

High levels of antibodies to hHSP60 and CPN: are independent risk factors for coronary atherosclerosis, but their simultaneous presence substantially increases the risk for disease development.

Cytomegalovirus, Chlamydia pneumoniae, and Helicobacter pylori IgG antibodies and restenosis after stent implantation: an angiographic and intravascular ultrasound study

OBJECTIVE

To determine the impact of previous infection with cytomegalovirus, Chlamydia pneumoniae, and Helicobacter pylori on neointimal proliferation after coronary angioplasty with stent implantation.

DESIGN

The study population was made up of 180 patients who had stent implantation in a native coronary artery with systematic angiographic and intravascular ultrasound (IVUS) follow up at six months. Quantitative coronary angiography was used to assess the late lumen loss. The mean area of neointimal tissue within the stent and the ratio of neointimal tissue to stent area were assessed from IVUS images. Previous cytomegalovirus, C pneumoniae, and H pylori infection was identified by IgG antibody determination.

RESULTS

Previous cytomegalovirus infection was detected in 50% of the population, previous C pneumoniae in 18%, and previous H pylori in 33%. Mean (SD) reference diameter was 2.94 (0.48) mm and mean minimum lumen diameter after stent implantation was 2.45 (0.42) mm. At six months, the mean late loss was 0.74 (0.50) mm, the mean neointimal tissue area was 3.8 (1.7) mm(2), and the average ratio of neointimal tissue area to stent area was 45 (18)%. None of these variables of restenosis was linked to any of the three infectious agents. By multivariate analysis, lesion length was the variable best correlated with mean neointimal tissue area, the ratio of neointimal tissue to stent area, and late loss, explaining respectively 31%, 39%, and 8% of their variability.

CONCLUSIONS

Previous infection with cytomegalovirus, C pneumoniae, or H pylori was not a contributing factor in the process of restenosis after stent implantation.

Preemptive therapy versus universal prophylaxis with ganciclovir for cytomegalovirus in solid organ transplant recipients

Whether preemptive therapy or universal prophylaxis with ganciclovir is the optimal approach against cytomegalovirus (CMV) remains unresolved. Controversy abounds with respect to the efficacy of preemptive therapy, the reliability of preemptive therapy tools, the logistical difficulties in conducting surveillance monitoring for CMV, the cost of prophylaxis, the effect of prophylaxis on indirect sequelae of CMV and epidemiology of CMV, and the potential for emergence of ganciclovir-resistant CMV. Although neither approach is wholly adequate, a discussion of the relative merits and limitations of the 2 approaches may guide the selection of a rational approach toward prevention of CMV infection in organ transplant recipients.

Infectious agents in coronary lesions obtained by endatherectomy: pattern of distribution, coinfection, and clinical findings

BACKGROUND

Cytomegalovirus (CMV), Chlamydia pneumoniae (C. pneumoniae), and Helicobacter pylori (H. pylori) have been implicated in atherosclerosis and restenosis after angioplasty. The patterns of distribution within coronary lesions and possible coinfections of these pathogens in the coronary vasculature had not previously been evaluated.

DESIGN

A prospective, observational clinical study.

METHODS

Large coronary specimens (9-105 mm long) were obtained by endatherectomy of 53 patients undergoing aortocoronary bypass surgery. Samples were taken from two different sites of every lesion, resulting in a total of 106 probes. Presence of each pathogen was determined by polymerase chain reaction, subsequent hybridization, and DNA sequencing.

RESULTS

Cytomegalovirus and C. pneumoniae were detected in 30 and 32% of the samples, respectively; H. pylori was not detectable. The pathogens were not homogeneously distributed. A concurrent infection with both pathogens was observed in five of 106 (5%) lesions and five of 53 (9%) patients. Restenotic lesions were more often found in specimens in which cytomegalovirus was detected (five of 16 versus two of 37). Patients with C. pneumoniae-positive coronary lesions more commonly presented with unstable angina.

CONCLUSIONS

Inhomogeneous infections with cytomegalovirus and C. pneumoniae of coronary atherosclerotic lesions are found to be prevalent when serial analysis is performed. Concurrent infection with both pathogens occurs coincidentally; however, possible clinical implications of this new observation and the pathogenic impact on atherosclerosis need further investigation.

Constitutive signaling of the human cytomegalovirus-encoded chemokine receptor US28

Previously it was shown that the HHV-8-encoded chemokine receptor ORF74 shows considerable agonist-independent, constitutive activity giving rise to oncogenic transformation (Arvanitakis, L., Geras-Raaka, E., Varma, A., Gershengorn, M. C., and Cesarman, E. (1997) Nature 385, 347-350). In this study we report that a second viral-encoded chemokine receptor, the human cytomegalovirus-encoded US28, also efficiently signals in an agonist-independent manner. Transient expression of US28 in COS-7 cells leads to the constitutive activation of phospholipase C and NF-kappaB signaling via G(q/11) protein-dependent pathways. Whereas phospholipase C activation is mediated via Galpha(q/11) subunits, the activation of NF-kappaB strongly depends on betagamma subunits with a preference for the beta(2)gamma(1) dimer. The CC chemokines RANTES (regulated on activation, normal T cell expressed and secreted) and MCP-1 (monocyte chemotactic protein-1) act as neutral antagonists at US28, whereas the CX(3)C chemokine fractalkine acts as a partial inverse agonist with IC(50) values of 1-5 nm. Our data suggest that a high level of constitutive activity might be a more general characteristic of viral G protein-coupled receptors and that human cytomegalovirus might exploit this G protein-coupled receptor property to modulate the homeostasis of infected cells via the early gene product US28.

Prospective study of pathogen burden and risk of myocardial infarction or death

BACKGROUND

We previously demonstrated that the risk of coronary artery disease (CAD) increased in relation to the number of pathogens (the "pathogen burden") in a cross-sectional study. In the present prospective study with a different patient cohort, we evaluated the effect of pathogen burden on the risk of myocardial infarction (MI) or death among CAD patients.

METHODS AND RESULTS

IgG antibodies to cytomegalovirus (CMV), hepatitis A virus (HAV), herpes simplex virus type 1 (HSV1), HSV type 2 (HSV2), Chlamydia pneumoniae and Helicobacter pylori, and C-reactive protein (CRP) levels were tested in baseline blood samples from 890 patients who had significant CAD on angiography. The mean follow-up period was 3 years. The baseline prevalence of antibodies directed against CMV, HAV, HSV1, or HSV2, but not C pneumoniae and H pylori, was significantly higher among patients who subsequently developed MI or death than among control subjects. After adjustment for traditional risk factors, number of diseased vessels, and clinical presentation, relative hazards (95% confidence limits) for MI or death were 2.0 (1. 4 to 3.2) for CMV, 1.6 (1.1 to 2.3) for HAV, and 1.5 (1.0 to 2.2) for HSV2. Increasing pathogen burden was significantly associated with increasing risk of MI or death in a dose-response fashion. Adjusted relative hazards of MI or death associated with pathogen burden were significant among individuals with low or high CRP levels.

CONCLUSIONS

The results suggest that infection plays an important role in incident MI or death and that the risk posed by infection is independently related to the pathogen burden.

Potential infectious etiologies of atherosclerosis: a multifactorial perspective

Coronary heart disease (CHD) contributes substantially to illness and death worldwide. Experimental studies demonstrate that infection can stimulate atherogenic processes. This review presents a spectrum of data regarding the link between CHD and infection. In addition, the need for improved diagnostic tools, the significance of multiple pathogens, and potential intervention strategies are discussed.

T-cell responses to mitogens in atomic bomb survivors: a decreased capacity to produce interleukin 2 characterizes the T cells of heavily irradiated individuals

Significant decreases in the fraction of lymphocytes that are CD4(+) and increases in serum levels of some classes of immunoglobulin have been reported to occur in atomic bomb (A-bomb) survivors and in victims of the Chernobyl nuclear plant accident. To investigate the long-term effects of nuclear radiation on cellular immunity in more detail, we used limiting dilution assays with peripheral blood mononuclear cell preparations to analyze the T-cell responses of 251 A-bomb survivors exposed to less than 0.005 Gy and 159 survivors exposed to more than 1.5 Gy. The percentages of CD2-positive cells that were capable of proliferating in response to phytohemagglutinin (PHA) in the presence of exogenous interleukin 2 (IL2) did not differ substantially between distally exposed and more heavily exposed survivors. The heavily exposed survivors appeared to possess fewer T cells that were capable of proliferating in response to concanavalin A (Con A) or of producing interleukin 2. Assuming that CD4 T cells were the ones primarily responsible for producing IL2 in response to Con A, we were able to estimate how many cells in any given CD4 T-cell population were actually producing IL2. The results indicated that peripheral blood samples from heavily exposed survivors contained significantly fewer IL2-producing CD4 T cells than did similar samples from distally exposed survivors, indicating that significant exposure to A-bomb radiation may have a long-lasting negative effect on the capacity of CD4 T-cell populations to produce IL2.

Association of influenza vaccination and reduced risk of recurrent myocardial infarction

BACKGROUND

Numerous studies have suggested that microbial agents may promote atherosclerosis. A smaller body of research has suggested that acute respiratory infection may be a risk factor for myocardial infarction (MI). We hypothesized that influenza vaccine might reduce the risk of recurrent MI in patients with documented coronary heart disease (CHD).

METHODS AND RESULTS

A case-control study was performed on 218 CHD patients seen at Memorial Hermann Hospital during the influenza season of October 1997 through March 1998. Patients who experienced new MI were included in the case group, and those who did not experience new MI or unstable angina were assigned to the control group. Data were collected by structured review of patients' charts and through a subsequent telephone survey. Adjusted for history of influenza vaccination in previous years, multivariate logistic regression revealed risk of MI to be associated with current hypertension (OR 4.96, 95% CI 2.06 to 11.96, P<0.0001), hypercholesterolemia (OR 4.08, 95% CI 1.67 to 9.99, P=0.002), smoking (OR 3.75, 95% CI 1.76 to 7.98, P=0.001), and influenza vaccination (OR 0.33, 95% CI 0.13 to 0.82, P=0.017). Despite significant association in univariate analysis, multivitamin therapy and physical exercise were not associated with risk of reinfarction in multivariate analysis.

CONCLUSIONS

In this study in patients with chronic CHD, vaccination against influenza was negatively associated with the development of new MI during the same influenza season. However, to address causal inference, examination of prospective data sets will be needed.

The association of infection and coronary artery disease: an update

Numerous studies have reported an association of coronary atherosclerosis and restenosis with certain bacterial and viral infections. This article reviews the pathophysiology of atherosclerosis, the role of infectious agents (cytomegalovirus, Chlamydia pneumoniae and Helicobacter pylori) in atherogenesis and studies supporting the potential beneficial effects of antibiotics or antiviral agents in the management of atherosclerotic disease. The interactions of cytomegalovirus and the arterial wall have been extensively studied. However, despite the successful preliminary therapeutic trials with the use of macrolides in augmenting possible C. pneumoniae-induced cardiovascular events, the exact mechanisms of how C. pneumoniae enters the arterial wall remains unknown at this point. For H. pylori, regardless of the large number of studies performed to assess the association between H. pylori and coronary artery disease, no definitive conclusion could be made at this time, due to contradictory results. Before one can widely adopt the use of antibiotics or antiviral agents as treatment for atherosclerosis, further studies must be designed to address some important issues. In vivo animal models need to be established to further examine the various hypotheses regarding the interaction of infectious agents and atherosclerosis and restenosis. Large-scale prospective cohort studies should be designed to relate evidence of infection to future risk of cardiovascular diseases. Confounding variables, such as other cardiovascular risk factors and socio-economic status, should be controlled in order to strengthen the association. Further interventional studies are also required to establish the best antibiotic or antiviral regimen to maximise efficacy and minimise side effects.

Lesion-to-lesion relationship of the restenosis process after placement of coronary stents

The interrelation between multiple stented lesions within one patient in the restenosis process is only partially understood. From 492 patients with follow-up angiograms after coronary stent placement, 115 patients underwent multilesion procedures involving 233 lesions. In randomly chosen 39 patients with 79 lesions, additional intravascular ultrasound (IVUS) studies were performed to measure intimal hyperplasia cross-sectional area (CSA) and thickness. A general linear model with intraclass correlation was used to calculate the coefficient of correlation rho (rho = 1.0 indicates perfect correlation; rho = 0.0 indicates no correlation) of late loss, late loss index, intimal hyperplasia CSA, and intimal hyperplasia thickness. Multivariate analysis showed restenosis in the companion lesion (odds ratio 4.68, 95% confidence interval 1. 68-12.92, P = 0.003) and small minimal lumen diameter preintervention (odds ratio 0.28, 95% confidence interval 0.11-0.73, P = 0.009) to be predictors of restenosis. There was a weak correlation between multiple lesions within the same patient for late lumen loss rho = 0.28 (95% confidence interval 0.10-0.46, P < 0. 001) and late loss index. IVUS analysis demonstrated correlation of intimal hyperplasia CSA rho = 0.40 (95% confidence interval 0.06-0. 74, P = 0.009) and of intimal hyperplasia thickness. In conclusion, late loss and intimal hyperplasia demonstrate a correlation between multiple stented lesions within one patient. In addition to known lesion related factors, restenosis in a companion lesion is a predictor for restenosis. Cathet. Cardiovasc. Intervent. 51:266-272, 2000.

Cytomegalovirus seropositivity and C-reactive protein have independent and combined predictive value for mortality in patients with angiographically demonstrated coronary artery disease

BACKGROUND

The role of inflammation in coronary artery disease (CAD) is being increasingly recognized. Markers of inflammation (eg, C-reactive protein [CRP]) and infection (eg, seropositivity to Chlamydia pneumoniae, cytomegalovirus [CMV], and Helicobacter pylori) have been proposed as risk factors for CAD, but these associations require further evaluation.

METHODS AND RESULTS

We prospectively tested whether CRP levels and IgG seropositivity to C pneumoniae, CMV, and H pylori are predictors of subsequent mortality in 985 consecutive patients with angiographically demonstrated CAD (stenosis >/=70%). Patients were followed for an average of 2.7 years (range 1.5 to 4.0 years). Patients averaged 65 years of age; 77% were men; and 110 (11.2%) died during follow-up. CRP levels were significantly elevated in nonsurvivors compared with survivors (mean CRP 3.1 mg/dL versus 1.5 mg/dL, P:=0.003). After controlling for all known baseline variables, the 2nd and 3rd tertiles of CRP compared with the 1st produced a Cox hazard ratio (HR) for mortality of 2.4 (P:=0.001). Of the 3 infectious markers tested, only seropositivity to CMV (HR=1.9, P:<0.05) was predictive of mortality. The majority of mortality risk associated with elevated CRP or CMV seropositivity occurred when both risk factors were present (P: for trend <0.0001). Other independent predictors of increased risk of mortality were age (HR=1.07 per year, P:<0.0001), left ventricular ejection fraction (HR=0.97 per percent, P:<0.0001), and diabetes mellitus (HR=1.7, P:=0.02).

CONCLUSIONS

CMV seropositivity and elevated CRP, especially when in combination, are strong, independent predictors of mortality in patients with CAD. This suggests an interesting hypothesis that a chronic, smoldering infection (CMV) might have the capacity to accelerate the atherothrombotic process.

Role of human cytomegalovirus immediate-early proteins in cell growth control

Human cytomegalovirus (HCMV) is a ubiquitous herpesvirus that has been implicated in several disorders, including an association between HCMV reactivation and the overproliferation of arterial smooth muscle cells observed in restenosis. Although HCMV can mediate a growth-arrest phenotype in infected cells, the virus can also promote an environment conducive to proliferation. Here, we present evidence that the HCMV immediate-early (IE) proteins, IE1-72 and IE2-86, may be responsible for inducing this proliferative environment by altering cell cycle control. We find that expression of either of these IE proteins can alter the cell cycle distribution of randomly cycling cells towards S and G(2)/M phases. Additionally, we find that expression of IE2-86, but not IE1-72, induces quiescent cells into S phase and delays cell cycle exit. In the absence of p53, IE1-72 expression can induce S phase and delay cell cycle exit. We also demonstrate that p53 protein levels increase in fibroblasts following the expression of IE1-72. The observed accumulation of p53 protein in IE1-72-expressing cells may account for the inability of IE1-72 to induce S phase and delay cell cycle exit. Our data suggest that expression of HCMV IE1-72 and IE2-86 is sufficient to alter the cell cycle to generate an environment conducive to proliferation.

Are morphological or functional changes in the carotid artery wall associated with Chlamydia pneumoniae, Helicobacter pylori, cytomegalovirus, or herpes simplex virus infection?

BACKGROUND AND PURPOSE

Chronic infection with Chlamydia pneumoniae, Helicobacter pylori, cytomegalovirus (CMV), and herpes simplex virus (HSV) has been implicated in the pathogenesis of atherosclerosis. The carotid intima-media thickness (IMT) can be taken to indicate early atherosclerosis, the presence of a carotid stenosis is a marker of a manifest carotid atherosclerosis, and an increase in arterial stiffness is used as marker of structural and functional changes in an atherosclerotic vessel wall.

METHODS

In 504 patients (75% men; mean age 62.9 [SD 10] years), we measured the IMT and the elastic pressure modulus (EP; n=445) of the common carotid artery and the prevalence of a internal or external carotid artery stenosis. Blood samples were taken, and antibodies against C pneumoniae, H pylori, CMV, and HSV types 1 and 2 were evaluated. Statistical evaluation was performed with regression procedures and multivariate logistic regression analyses.

RESULTS

Seropositivity for C pneumoniae was an independent predictor for a combined end point of highest category of IMT and carotid artery stenosis (OR 1.8, 95% CI 1.1 to 3.1; adjusted) for IgG titers. Independently, CMV increased the risk for the combined end point (OR 1.7, 95% CI 1.1 to 2.8; adjusted) for IgG titers and for IgA titers (OR 2.3, 95% CI 1.1 to 4. 9; adjusted). We found a significant correlation between IgG antibodies against CMV and EP; HSV type 2 IgG titers were associated with IMT and carotid stenosis, but the latter results were no longer significant after adjustment. There was no association with H pylori or HSV type 1.

CONCLUSIONS

We found a significant association of IgG antibodies against C pneumoniae and CMV with early and advanced carotid atherosclerosis. CMV was also correlated to functional changes of the carotid artery, but this could not be confirmed after adjustment.

Inflammation, depressive symptomtology, and coronary artery disease

OBJECTIVE

Many patients feel exhausted or depressed before the onset of an acute coronary event, but little is known about the origin of these feelings. We tested the hypothesis that the depressive symptomatology is associated with a reactivation of latent viruses and inflammation of a coronary vessel.

METHODS

A blood sample was drawn and a biopsy sample was obtained from the coronary lesion of 15 exhausted and 15 nonexhausted patients treated with directional coronary angioplasty because of severe angina. Blood samples were analyzed to measure antibody titers against Chlamydia pneumoniae, cytomegalovirus, and the cytokines interleukin (IL)-1beta, IL-6, and tumor necrosis factor (TNF)-alpha. The biopsy sample was analyzed for the presence of IL-1beta and TNF-alpha.

RESULTS

Exhausted/depressed patients had higher antibody titers against cytomegalovirus, higher levels of C. pneumoniae immunoglobulin G, and higher levels of IL-1beta and TNF-alpha. No associations between the mental state of a patient and cytokine mRNA in the biopsy sample were found.

CONCLUSIONS

The findings indicate that the mental state of angioplasty patients is positively associated with serological markers of inflammation. It remains to be seen whether the inflammation causes feelings of exhaustion, whether exhaustion and depression set the stage for inflammation, or whether existing feelings of exhaustion are amplified by the inflammation.

Prior cytomegalovirus infection does not predict clinical outcome after percutaneous transluminal coronary angioplasty

BACKGROUND

A direct association between human cytomegalovirus (HCMV) infection and the development of restenosis after coronary angioplasty has been suggested. The aim of this prospective study was to evaluate the value of HCMV serology in predicting the clinical outcome after percutaneous transluminal coronary angioplasty (PTCA).

METHODS AND RESULTS

112 patients undergoing elective PTCA were included in the study. HCMV antibody levels were measured by ELISA. Cardiac events within a follow-up period of 6 months after PTCA were defined as (1) progression or recurrence of anginal complaints and/or a positive exercise test; (2) restenosis that required repeat revascularization. 73% of PTCA patients were seropositive for HCMV. Successful PTCA was achieved in a total of 94 patients, who were followed for 6 months. In 31/94 patients (33%) cardiac events occurred and in 15/94 (16%), this could be related to restenosis. We found no statistically significant difference between seropositive and negative patients with respect to anginal complaints or the need for revascularization. There was no evidence of acute reactivation, since titers of anti-HCMV antibodies did not increase after PTCA.

CONCLUSION

This study shows that the clinical outcome after PTCA is not related to the HCMV serostatus of the patient. Therefore, our data do not support the hypothesis that serological markers of HCMV infection are of clinical importance for the assessment of a patient's individual risk after PTCA. This does not preclude a role for local reactivation of HCMV at the site of angioplasty.

Effect of prior exposure to Chlamydia pneumoniae, Helicobacter pylori, or cytomegalovirus on the degree of inflammation and one-year prognosis of patients with unstable angina pectoris or non-Q-wave acute myocardial infarction

Inflammation and chronic infections may be important features in the pathogenesis of acute coronary syndromes. We describe 6 systemic markers of inflammation in patients with unstable angina or non-Q-wave myocardial infarction and the relations between these markers, seropositivity to chronic infections, and prognosis. C-reactive protein (CRP), serum amyloid A protein (SAA), fibrinogen, interleukin-6 (IL-6), neopterin, procalcitonin, and serum antibody levels to Chlamydia pneumoniae, Helicobacter pylori, and cytomegalovirus were measured on admission and 48 hours later. One-year clinical follow-up was performed. Plasma levels of acute phase reactants were all elevated on admission and increased further at 48 hours: CRP from 10.1 +/- 2.1 mg/L at baseline to 26.6 +/- 5.1 mg/L at 48 hours (p <0.001); SAA from 27.3 +/- 8.5 to 93.1 +/- 23.2 mg/dl (p <0.005); fibrinogen from 3.2 +/- 0.1 to 3.8 +/- 0.1 g/L (p <0.0001); whereas initial high levels of IL-6 tended also to increase from 9.8 +/- 2 to 15.3 +/- 3.1 pg/ml (p = NS). In contrast, neopterin and procalcitonin remained unchanged. We found no association between levels of each inflammatory marker and the serologic status. Furthermore, levels of inflammatory proteins in patients seronegative to all 3 agents were comparable to those of patients seropositive to 2 or 3 infectious agents. The composite end points of death, myocardial infarction, recurrent angina, or revascularization at 1-year follow-up did not differ according to the serologic status. Thus, in patients with acute coronary syndromes, the acute phase proteins increased over the first 2 days of hospitalization. This initial inflammatory reaction as well as the 1-year clinical outcome did not differ according to the initial serologic status of Chlamydia pneumoniae, Helicobacter pylori, or cytomegalovirus.

Herpesvirus infection accelerates atherosclerosis in the apolipoprotein E-deficient mouse

BACKGROUND

Human herpesviruses have been implicated but not proven to be involved in the etiology of atherosclerosis. To determine whether there is a causal relationship, the effect of herpesvirus infection on the development of atherosclerosis was assessed in the apolipoprotein E-deficient (apoE-/-) mouse.

METHODS AND RESULTS

In the present study, 3- to 4-week-old apoE-/- mice were infected with murine gamma-herpesvirus-68 (MHV-68). Atheroma formation was accelerated over a 24-week period in infected apoE-/- mice compared with control uninfected apoE-/- mice. Acceleration of atherosclerosis was reduced by antiviral drug administration. Histological analysis of the atheromatous plaques showed no difference between lesions of infected and control mice. Viral mRNA was present in the aortas of infected mice before lesion development on day 5 after infection. This suggests that the virus may initiate endothelial injury, which is believed to be an early event in the development of atherosclerosis. Therefore, the virus may play a direct role in atherosclerosis rather than be an "innocent bystander."

CONCLUSIONS

These data demonstrate that a gamma-herpesvirus can accelerate atherosclerosis in the apoE-/- mouse. This study provides the first report of a murine model in which to study the causative role of herpesvirus infection in the development of atherosclerosis.

Increased incidence of cardiac complications in kidney transplant recipients with cytomegalovirus disease

BACKGROUND

The transplant literature has not shown cytomegalovirus (CMV) disease to be a significant risk factor for posttransplant cardiac complications. A large number of nontransplant studies have, however, reported an association between coronary heart disease (CHD) and CMV disease. Pathology studies have demonstrated a high incidence of CMV in atheromatous plaques from the coronary circulation.

METHODS

We performed multivariate analysis to determine if posttransplant CMV disease was a significant risk factor for cardiac complications in kidney transplant recipients. We also performed univariate analysis to determine which cardiac complications were more common in the recipients with CMV disease.

RESULTS

Between January 1, 1984 and June 30, 1997, 1859 adults underwent kidney transplants at our institution. Of these, 377 developed one of the following cardiac complications posttransplant: myocardial infarction, angina, arrhythmia, congestive heart failure, and angiographic vessel occlusion. By multivariate analysis, significant risk factors for one of the above cardiac complications were recipient age >50 years [odds ratio (OR)=2.5, P=0.0001], diabetes (OR=1.99, P=0.0001), a history of cardiac disease pretransplant (OR= 1.34, P=0.04), and CMV disease (OR=1.5, P=0.01). Univariate analysis demonstrated that recipients with CMV disease had a higher overall incidence of cardiac complications. Arrhythmias, congestive heart failure, and vessel occlusion were more common in those with CMV disease. The incidence of myocardial infarction, angina, and cardiac arrest did not differ between the two groups (recipients with versus without CMV disease).

CONCLUSIONS

CMV disease is associated with an increased risk of cardiac complications in kidney transplant recipients. In our series, angiographic vessel occlusion was more common in recipients with CMV disease. This interesting finding may support the theory that CMV plays some role in the pathogenesis of CHD.

Infections and atherosclerosis

More than a century ago, inflammation and infection were considered to have atherogenic effects. During last century, however, this hypothesis was completely abandoned, and the old idea that coronary heart disease (CHD) possibly has an infectious etiology has only re-emerged in recent years. Both viral and bacterial pathogens have been proposed to be associated with the inflammatory changes found in atherosclerosis. Herpes group viruses, especially cytomegalovirus (CMV) and herpes simplex virus type 1 (HSV1), have been associated with both atherosclerosis and restenosis. Helicobacter pylori and dental infections have also been linked to CHD, but the evidence is strongest for a respiratory tract bacterium, Chlamydia pneumoniae. The association was originally found in seroepidemiological studies, but the presence of organisms in atherosclerotic lesions, the first animal studies and preliminary successful intervention trials with antibiotics suggest that C. pneumoniae may have a pathogenetic role in the disease. The causal relationship has not yet been proven, but ongoing large intervention trials and research on pathogenetic mechanisms may lead to the use of antimicrobial agents in the treatment of CHD in the future.

A novel link between stress and human cytomegalovirus (HCMV) infection: sympathetic hyperactivity stimulates HCMV activation

Recently, inflammatory mediators such as TNFalpha were identified as triggering active human cytomegalovirus (HCMV) infection. Here, we demonstrate that a highly stressful event in the absence of systemic inflammation, as observed in patients with acute myocardial infarction, leads to the development of an active HCMV infection in latently infected patients. Elucidating the molecular mechanism of virus activation, we could show that catecholamines directly stimulate the HCMV immediate-early (IE) enhancer/promoter in monocytic cells via beta-2 adrenergic receptors. Subsequent activation of the cAMP/PK-A-signaling pathway results in enhanced synthesis and binding of the transcription factor CREB-1/ATF-1 to the cAMP-responsive elements within the IE enhancer. Epinephrine also enhanced HCMV gene expression in infected THP-1 cells by about 50% in three of four experiments. These data suggest that HCMV, like HSV-1 and VZV, can be (re)activated under stress conditions.

Ehrlichiosis associated vasculitis

OBJECTIVE

To test the hypothesis that some cases of primary vasculitis are caused by ehrlichiosis.

DESIGN

A retrospective case study and serological analysis of stored sera.

SETTING

University hospital.

SUBJECTS

Fifty-five patients discharged with any type of vasculitis over a 6-year period.

MAIN OUTCOME MEASURES

Serology for human monocytic ehrlichiosis, and the human granulocytic ehrlichiosis agent, and polymerase chain reaction (PCR) analysis of biopsy specimens.

RESULTS

Three patients (5.5%) had titres of 1 : 128 or higher against E. chaffeensis; none was positive for the human granulocytic ehrlichiosis agent. Skin biopsies of these patients showed lesions compatible with polyarteritis nodosa, allergic purpura and unspecified vasculitis. PCR analysis of the biopsies was unrevealing.

CONCLUSIONS

Infection with human monocytic ehrlichiosis may underlie some forms of vasculitis. If confirmed, these findings may help identify patients with vasculitis who would benefit from antibiotic treatment.

Infection and atherosclerosis: potential roles of pathogen burden and molecular mimicry

Infection has been implicated as a cause of atherosclerosis since the first half of the 19th century. Over the years, sporadic publications have appeared in the literature reflecting a persistent but relatively low level of research activity in this area. In the last decade, however, publications relating to this topic have increased markedly. And very recently, new epidemiological and mechanistic data relating infection to several different diseases, including atherosclerosis, have appeared, stimulating the emergence of important paradigm shifts in how we think about the causes of chronic disease. The following article reviews some of these newer concepts as they relate to a possible role of infection in atherosclerosis.

Prior cytomegalovirus, Chlamydia pneumoniae or Helicobacter pylori infection and the risk of restenosis after percutaneous transluminal coronary angioplasty

We investigated a possible correlation between the serologic status concerning Cytomegalovirus (CMV), Chlamydia pneumoniae (CP) and Helicobacter pylori (HP) and the occurrence of restenosis in patients undergoing percutaneous transluminal coronary angioplasty for symptomatic coronary artery disease. Tests for anti-CMV IgG, anti-Chlamydia pneumoniae IgG and IgA and HP IgG and IgA were performed with an enzyme-linked immunosorbent assay (ELISA). Restenosis was defined as >/=50% stenosis at follow-up angiography in a vessel with less than 50% stenosis immediately after PTCA. Of 148 patients, 112 (75.7%) were seropositive for CMV, 75 (50.7%) were seropositive for CP and 78 (52.7%) were seropositive for HP. Restenosis occured in 31.8% of patients. CMV seropositivity was established in 74.5% of patients with restenosis versus 76.2% without restenosis (P=0.82), CP seropositivity was established in 44. 7% of patients with restenosis versus 53.5% without restenosis (P=0. 32), HP seropositivity was established in 53.2% of patients with restenosis versus 52.5% without restenosis (P=0.94). In contrast to some earlier studies CMV or HP seropositivity could not be found to be associated with the risk of restenosis after coronary intervention. An association between the serological status of CP and restenosis could also not be established.

Infectious complications in renal transplant recipients

Infectious complications present major challenges to physicians caring for renal transplant recipients. The high rate of infection reflects the net state of immunosuppression associated with end-stage renal disease, transplantation, donor and environmental exposure. An understanding of the factors that affect the patients' overall state of immunosuppression is essential to prevent and treat infectious complications, which may lead to significant morbidity, graft dysfunction, or mortality. Familiarity with the various pathogens, clinical presentation, diagnostic options, treatment, and prophylaxis is important to care for renal transplant patients. The authors present their approach, based on review of current literature, to these issues.

Transfection of antisense p53 tumor suppressor gene oligodeoxynucleotides into rat carotid artery results in abnormal growth of vascular smooth muscle cells

BACKGROUND

Although loss of activity of an antioncogene, the p53 tumor suppressor gene product, has been postulated in the pathogenesis of human restenosis, little is known about the role of p53 in the regulation of vascular smooth muscle cell (VSMC) growth. In this study, to clarify the role of p53 in the pathogenesis of restenosis, we examined transfection of antisense p53 oligodeoxynucleotides (ODN) into VSMC in vitro and rat carotid artery in vivo.

METHODS AND RESULTS

The specificity of antisense p53 ODN was confirmed by a significant decrease in p53 protein. Transfection of antisense p53 ODN into VSMC resulted in a significant increase in DNA synthesis and cell number as compared with sense and scrambled ODN (P<0.01). Importantly, transfection of antisense p53 ODN into rat intact carotid artery resulted in a significant increase in the ratio of neointima to medial area at 2 and 4 weeks after transfection, accompanied by a significant decrease in p53 protein (P<0.01). Moreover, cotransfection of wild-type p53 plasmid completely abolished neointimal formation induced by antisense p53 ODN. The sustained effect of a single antisense ODN administration was confirmed by the kinetics of ODN in the vessel wall with the use of FITC-labeled ODN.

CONCLUSIONS

Overall, the present study demonstrated that loss of p53 by antisense p53 ODN resulted in an abnormal VSMC growth in vitro and in vivo. These results demonstrated the potential contribution of p53 to the pathogenesis of restenosis.

Cytomegalovirus infection of vascular cells induces expression of pro-inflammatory adhesion molecules by paracrine action of secreted interleukin-1beta

BACKGROUND

Infection with human cytomegalovirus (HCMV) has been associated with vascular disease processes such as vascular allograft rejection, transplantation vasculopathy, restenosis after angioplasty, and native atherosclerosis. To elucidate underlying pathomechanisms, the effect of acute HCMV infection on the expression of pro-inflammatory adhesion molecules on human umbilical vein endothelial cells (HUVEC) and human vascular smooth muscle cells (hvSMC) was examined.

METHODS AND RESULTS

Cells were infected in vitro with clinical strains of HCMV and the resulting changes in adhesion molecule expression were quantified by histology and flow cytometric analysis. On HUVEC, surface expression of vascular cell adhesion molecule-1 and E-selectin was induced de novo on HCMV infection and intercellular adhesion molecule-1 expression was increased by >200%. On hvSMC, intercellular adhesion molecule-1 surface expression induced de novo, although vascular cell adhesion molecule-1 and E-selectin were not changed. Expression of major histocompatibility complex (MHC) class II, lymphocyte-function associated antigen 3 (LFA-3; CD58), and CD40 was not altered by HCMV infection in either cell type. In partially infected cultures, up-regulation of surface molecules also occurred on noninfected cells, suggesting a paracrine mechanism via a soluble factor. Expression of surface molecules could be enhanced in noninfected HUVEC and hvSMC by incubation with virus-free conditioned supernatant from HCMV-infected cells or by coincubation in transwells with infected cells. The responsible agent could be identified as IL- interleukin- (IL) 1beta by detection of de novo secretion of IL-1beta by HCMV-infected cells and by prevention of adhesion molecule up-regulation after addition of an IL-1-converting enzyme inhibitor or IL-1 receptor antagonist. Surface molecule up-regulation could be suppressed by UV inactivation of virus, but not by treatment of cell cultures with inhibitors of viral replication (ganciclovir).

CONCLUSION

We propose that HCMV infection induces IL-1beta release and subsequent up-regulation of pro-inflammatory adhesion molecules on noninfected neighboring cells through a paracrine mechanism. This may lead to local potentiation of the inflammatory effects of HCMV infection, not amenable to current therapeutic antiviral strategies.

Exploitation of cellular signaling and regulatory pathways by human cytomegalovirus

Human cytomegalovirus is a ubiquitous human pathogen that is the leading viral cause of birth defects. It also causes significant morbidity and mortality in both chemically and virally immunosuppressed individuals. Recent studies have begun to elucidate the interplay between this virus and its host cell on a molecular level. The interactions begin upon contact with the cell membrane, involve multiple processes including cell signaling, cell-cycle control and immune response mechanisms, and culminate in a productive infection.

Human cytomegalovirus harbors its own unique IL-10 homolog (cmvIL-10)

We identified a viral IL-10 homolog encoded by an ORF (UL111a) within the human cytomegalovirus (CMV) genome, which we designated cmvIL-10. cmvIL-10 can bind to the human IL-10 receptor and can compete with human IL-10 for binding sites, despite the fact that these two proteins are only 27% identical. cmvIL-10 requires both subunits of the IL-10 receptor complex to induce signal transduction events and biological activities. The structure of the cmvIL-10 gene is unique by itself. The gene retained two of four introns of the IL-10 gene, but the length of the introns was reduced. We demonstrated that cmvIL-10 is expressed in CMV-infected cells. Thus, expression of cmvIL-10 extends the range of counter measures developed by CMV to circumvent detection and destruction by the host immune system.

The possible role of human cytomegalovirus (HCMV) in the origin of atherosclerosis

BACKGROUND

The biological properties of some herpesviruses such as the ability of latent persistency in the host cells and the presence of viral DNA in atherosclerotic lesions, suggest the possible role of herpesviruses in the development of atherosclerosis. Although many authors proved the presence of viral DNA in arterial wall tissue, the role of herpesviruses in the origin and progress of atherogenesis still remains unclear.

OBJECTIVES

The aim of this study was to confirm the presence of viral DNA in arterial wall and to associate the presence of these viruses with the development of atherosclerosis in patients with ischemic heart disease (IHD).

STUDY DESIGN

A possible role of HCMV, EBV and HHV6 in the development of atherosclerosis was tested in 244 IHD patients and 87 coronarographically negative controls. The presence of viral DNA in aortic and venous walls, as well as in a peripheral blood samples was tested by the use of polymerase chain reaction (PCR) accompanied by, immunological tests for anti-virus antibodies IgM and IgG types for all experimental groups.

RESULTS

The genomic DNA of HCMV was found in 76 and 59%, DNA of EBV in 59 and 50%, and DNA of HHV6 in 0.08 and 0.0%, of arterial walls of IHD patients and non-ischemic control group, respectively. No viral DNA was found in venous samples. Significant association (P < 0.01) has been proved between CMV infection and IHD.

CONCLUSIONS

Our results suggest that HCMV and EBV can be found in the arterial wall, so that the arterial wall could be a potential site of persistency of those viruses. We also proved a significant association between the presence of HCMV DNA in aortic walls and atherosclerosis. Despite of the high genetic and biological similarity between CMV and HHV6 no substantial role of HHV6 in atherosclerosis has been proved.

CMV and transplant-related coronary atherosclerosis: an immunohistochemical, in situ hybridization, and polymerase chain reaction in situ study

Accelerated graft coronary atherosclerosis is the main obstacle to long-term survival in patients who have had a heart transplant. A possible involvement of the human cytomegalovirus (HCMV) in this type of coronary atherosclerosis has been postulated by many authors but has not been definitively demonstrated. In an attempt to clarify the role of HCMV infection in the pathogenesis of this complication, we looked for in situ antigens or DNA of HCMV in 30 coronary artery segments obtained at necropsy from patients who had undergone orthotopic cardiac transplantation at the São Paulo Heart Institute. We tried to correlate these HCMV markers with the presence of inflammation and/or atherosclerosis in histologic sections. The patients were grouped as follows: GI, less than 170 days of graft survival and absent/mild atherosclerosis; GII, more than 170 days of graft survival and absent/mild atherosclerosis; GIII, more than 170 days of graft survival and severe/moderate atherosclerosis (170 days was the shortest graft survival time associated with atherosclerosis). The search for HCMV genome and antigens in the coronary artery sections was performed using immunohistochemistry, in situ hybridization, and polymerase chain reaction in situ techniques. Immunohistochemistry and in situ hybridization revealed no evidence of HCMV in all 30 cases. Polymerase chain reaction in situ revealed scarce HCMV-positive lymphocytes in two cases (one each from GI and GIII) located in the adventitial layer. These findings preclude a direct role for the HCMV in the pathogenesis of accelerated graft coronary atherosclerosis. However, the possibility of an indirect effect of the virus, such as an immune-mediated inflammatory response by the host that increases the expression of histocompatibility antigens, leading to tissue injury, cannot be excluded.

Inflammation, infection and atherosclerosis: do antibacterials have a role in the therapy of coronary artery disease?

Since the recent publication of 3 studies on the use of antibacterials in patients with coronary artery disease (CAD), there has been a phenomenal interest in the role of infection in the genesis of CAD. It is now generally accepted that inflammation accompanies atherosclerosis from its initiation to the evolution of end-events. Inflammation may occur in response to traditional risk factors, such as hyperlipidaemia, smoking and diabetes mellitus. There is a recent resurgence of the concept that inflammation may have an infectious basis. This concept is based on the identification of microorganisms in the atherosclerotic plaque and seropositivity. The data on eradication of the offending organism with antibiotics and prevention of atherosclerosis-related events have, however, been inconsistent. This may reflect lack of precise understanding of steps leading to atherosclerosis and the evolution of acute ischaemic events. Further work in this area may help identify subsets of patient populations within which infection may play a causative role in the genesis of CAD. Targeted therapy then may be considered logical.

Infections, inflammation, and the risk of coronary heart disease

BACKGROUND

The role of infections and inflammation in the pathophysiology of coronary heart disease is emerging. We studied the independent and joint effects of these 2 components on coronary risk.

METHODS AND RESULTS

We measured baseline levels of C-reactive protein (CRP) and antibodies to adenovirus, enterovirus, cytomegalovirus, and herpes simplex virus as well as to Chlamydia pneumoniae (Cpn) and Helicobacter pylori in 241 subjects who suffered either myocardial infarction or coronary death during the 8.5-year trial in the Helsinki Heart Study, a coronary primary prevention trial. The 241 controls in this nested case-control study were subjects who completed the study without coronary events. Antibody levels to herpes simplex type I (HSV-1) and to Cpn were higher in cases than in controls, whereas the distributions of antibodies to other infectious agents were similar. Mean CRP was higher in cases (4.4 versus 2.0 mg/L; P<0.001), and high CRP increased the risks associated with smoking and with high antimicrobial antibody levels. The odds ratios in subjects with high antibody and high CRP levels were 25.4 (95% CI 2.9-220.3) for HSV-1 and 5.4 (95% CI 2.4-12.4) for Cpn compared with subjects with low antibody levels and low CRP. High antibody levels to either HSV-1 or to Cpn increased the risk independently of the other, and their joint effect was close to additive.

CONCLUSIONS

Two chronic infections, HSV-1 and Cpn, increase the risk of coronary heart disease. The effect is emphasized in subjects with ongoing inflammation, denoted by increased CRP levels.

Effects of total pathogen burden on coronary artery disease risk and C-reactive protein levels

Infection and inflammation have been suggested to play roles in coronary artery disease (CAD). We hypothesized that: (1) CAD risk is associated with the aggregate number of pathogens (pathogen burden), and (2) increased pathogen burden is associated with elevated levels of C-reactive protein (CRP), a marker of inflammation. We evaluated 233 patients for CAD. Blood samples from each patient were tested for immunoglobulin-G (IgG) antibodies to cytomegalovirus (CMV), Chlamydia pneumoniae, hepatitis A virus (HAV), herpes simplex virus type 1 (HSV-1) and HSV type 2 (HSV-2), and for the CRP levels. Of the 233 study subjects, 68% had evidence of CAD by coronary angiography. Although the prevalence of seropositivity for each pathogen tended to be higher in the patients with CAD than those without, only the association between CAD and seropositivity to HAV was significant in multivariate analysis. Over 75% of study subjects had been exposed to > or =3 of the 5 pathogens tested, and analysis determined that increasing pathogen burden was significantly associated with increasing CAD risk, even after adjustment for traditional CAD risk factors. The prevalence of CAD was 48%, 69%, and 85% in individuals with antibodies to < or =2 pathogens, to 3 or 4 pathogens, and to 5 pathogens, respectively. A similar association between increasing pathogen burden and CRP levels was also found. The pathogen burden remained a significant predictor of CRP levels after multivariate analysis. Our data suggest that infection does play a role in the genesis of atherosclerosis. However, the risk posed by infection is related to the pathogen burden that may contribute to CAD through inflammatory responses.

Previous cytomegalovirus infection and risk of coronary thrombotic events after stent placement

BACKGROUND

Cytomegalovirus (CMV) infection induces upregulation of tissue factor and loss of anticoagulants, including thrombomodulin, prostacyclin, and tissue plasminogen activator. CMV infection may thereby increase the procoagulant properties of coronary artery plaques. This prospective study investigated the effect of previous CMV infection on the early hazard of coronary stent placement.

METHODS AND RESULTS

In 551 consecutive patients with successful coronary stent placement, we determined CMV IgG titers. The end point was the composite rate of death, nonfatal Q-wave myocardial infarction, and urgent reintervention during 30-day follow-up. The study population represented the entire spectrum of coronary stenting; an acute coronary syndrome was present in 50% of the patients. A positive CMV IgG titer (>/=1/230) was found in 340 patients (62%). Of these, 10 reached the end point during 30-day follow-up (2 deaths, 4 infarctions, 4 urgent reinterventions). In the group with negative CMV titer, thrombotic events did not occur (P=0.014 versus group with positive CMV titers). After correction for pertinent covariables, a significant relation between positive CMV titer and the 30-day end point prevailed (P<0.001).

CONCLUSIONS

Previous CMV infection may increase the risk of coronary thrombotic events after stent placement.

Chronic infection and coronary artery disease

On a variety of fronts, chronic infection has been found to be significantly associated with the development of atherosclerosis and the clinical complications of unstable angina, myocardial infarction, and stroke. For the most part, these are still just associations. Specific causative relationships on par with that determined between H. pylori and peptic ulcer disease have not yet been established. Potential mechanisms whereby chronic infections may play a role in atherogenesis are myriad. In the case of C. pneumoniae, the effect may result from direct vessel wall colonization, which may damage the vessel directly or indirectly by initiating immunologic responses. In other cases, the effect may simply be that of enhancing the preexisting chronic inflammatory response of the body to standard risk factors, such as hyperlipidemia. Even though the infectious agent may not directly infect the vessel wall, it may perform its critical role from afar. Chronic infection might also influence preexisting plaque by enhancing T cell activation or other inflammatory responses that may participate in the destabilization of the intimal cap. Chronic infection may play a role in the initiation, progression, or destabilization of atherosclerotic plaques. The infectious agents with the most evidence to support a causative role in atherosclerosis include C. pneumoniae and cytomegalovirus. Evidence is mounting for a variety of other potential agents, including H. pylori, various periodontal agents, and even hepatitis A. Future studies are expected to elucidate further the pathophysiologic relationship between chronic infection and atherosclerosis and to evaluate the potential of a variety of treatment approaches, including antibiotics.

Cloning and epitope mapping of a functional partial fusion receptor for human cytomegalovirus gH

A cDNA clone encoding a partial putative human cytomegalovirus (HCMV) gH fusion receptor (CMVFR) was previously identified. In this report, the cDNA sequence of CMVFR was determined and the role of this CMVFR in HCMV/cell fusion was confirmed by rendering fusion-incompetent MOLT-4 cells susceptible to fusion following transfection with receptor cDNA. Blocking experiments using recombinant gH or either of two MAbs (against recombinant gH or purified viral gH:gL) provided additional evidence for the role of gH binding to this protein in virus fusion. An HCMV-binding domain of 12 aa in the middle hydrophilic region of CMVFR was identified by fusion blocking studies using synthetic receptor peptides. The 1368 bp cDNA of CMVFR contained a predicted ORF of 345 aa with two potential membrane-spanning domains and several possible nuclear localization signals. A search of sequence databases indicated that CMVFR is a novel protein. Further characterization of this cell membrane protein that confers susceptibility to fusion with the viral envelope should provide important information about the mechanism by which HCMV infects cells.

Association of endotoxemia with carotid atherosclerosis and cardiovascular disease: prospective results from the Bruneck Study

OBJECTIVES

Focus of the current study was on the significance of bacterial endotoxin, which shows a variety of pro-atherogenic properties and may occur at high concentration in the circulation of infected subjects.

BACKGROUND

The possibility of an infectious risk factor in atherogenesis and cardiovascular disease has stimulated research interest, but the nature of such process remains obscure.

METHODS

We measured plasma endotoxin levels (LAL assay) in a random population of 516 men and women 50 to 79 years old at the 1990 baseline evaluation (Bruneck Study). End points of this prospective survey were incident (early) atherosclerosis in the carotid arteries as assessed with high-resolution Duplex ultrasound (five-year follow-up rate, 98%) and incident cardiovascular disease (follow-up rate, 100%).

RESULTS

Median endotoxin concentration amounted to 14.3 pg/ml (range, 6.0 to 209.2 pg/ml). Subjects with levels beyond 50 pg/ml (90th percentile) faced a threefold risk of incident atherosclerosis (odds ratio [95% confidence interval] 2.9 [1.4-6.3]; p < 0.01). The risk associated with high endotoxin was most pronounced in subjects with chronic infections and in current and ex-smokers. Notably, smokers with low endotoxin levels and nonsmokers did not differ in their atherosclerosis risk, whereas smokers with high levels almost invariably developed new lesions. All findings emerged as independent of vascular risk factors. Similar results were obtained for incident cardiovascular disease.

CONCLUSIONS

The current study yields first epidemiologic evidence that endotoxemia constitutes a strong risk factor of early atherogenesis in subjects with chronic or recurrent bacterial infections and a link in the association between cigarette smoking and atherosclerotic disease.

The human cytomegalovirus chemokine receptor US28 mediates vascular smooth muscle cell migration

Human cytomegalovirus (HCMV) infection of smooth muscle cells (SMCs) in vivo has been linked to a viral etiology of vascular disease. In this report, we demonstrate that HCMV infection of primary arterial SMCs results in significant cellular migration. Ablation of the chemokine receptor, US28, abrogates SMC migration, which is rescued only by expression of the viral homolog and not a cellular G protein-coupled receptor (GPCR). Expression of US28 in the presence of CC chemokines including RANTES or MCP-1 was sufficient to promote SMC migration by both chemokinesis and chemotaxis, which was inhibited by protein tyrosine kinase inhibitors. US28-mediated SMC migration provides a molecular basis for the correlative evidence that links HCMV to the acceleration of vascular disease.

Cytomegalovirus in the pathogenesis of atherosclerosis: the role of inflammation as reflected by elevated C-reactive protein levels

OBJECTIVES

We hypothesized that cytomegalovirus (CMV) infection: 1) stimulates an inflammatory response, reflected by elevated C-reactive protein (CRP) levels, and 2) predisposes to coronary artery disease (CAD), in part, through CMV-induced inflammation.

BACKGROUND

Although some studies show an association between CMV and atherosclerosis, others do not. We believed that CMV exerted an atherogenic effect by inducing inflammation, and the disparate results may derive partly from individual variability in the capacity to control CMV inflammatory activity.

METHODS

Blood samples were tested for CMV seropositivity and CRP levels from 238 individuals being evaluated for CAD by coronary angiography.

RESULTS

An elevated CRP level (>0.5 mg/dl) was a significant CAD determinant even after adjustment for traditional CAD risk factors (odds ratio [OR] = 2.4; p = 0.02). Moreover, CMV seropositivity was significantly associated with increased CRP levels (p = 0.04 after adjustment for CAD risk factors), suggesting that CMV could evoke a subclinical inflammatory response. However, considerable host variation existed in this response to CMV. When adjusted for CAD risk factors, the OR for CAD were 1.3 in the subgroup with CMV seropositivity alone (p = 0.7), 2.3 in the subgroup with elevated CRP levels alone (p = 0.2), and 4.3 in the subgroup with combined CMV seropositivity and elevated CRP levels (p = 0.01).

CONCLUSIONS

Our results suggest that 1) CMV elicits a subclinical inflammatory response, but only in certain individuals, and 2) individuals with an inflammatory response appear susceptible to the atherogenic effects of CMV, whereas those without appear resistant. These results may partly explain the disparate results of studies attempting to relate CMV to atherogenesis.

Induction of syncytia by neuropathogenic murine leukemia viruses depends on receptor density, host cell determinants, and the intrinsic fusion potential of envelope protein

Infection by the neuropathogenic murine leukemia virus (MLV) TR1.3 results in hemorrhagic disease that correlates directly to in vivo syncytium formation of brain capillary endothelial cells (BCEC). This phenotype maps to amino acid 102 in the envelope (Env) protein of TR1.3. Substitution of glycine (G) for tryptophan (W) at this position (W102G Env) in the nonpathogenic MLV FB29 induces both syncytium formation and neurologic disease in vivo. Using an in vitro gene reporter cell fusion assay, we showed that fusion either with murine NIH 3T3 cells or with nonmurine target cells that expressed receptors at or below endogenous murine levels mirrored that seen in BCEC in vivo. In these instances only TR1.3 and W102G Env induced cell fusion. In contrast, when receptor levels on nonmurine cells were raised above endogenous murine levels, FB29 Env was as fusogenic as the neuropathogenic TR1.3 and W102G Env. These results indicate that TR1.3 Env and W102G Env are intrinsically more fusogenic than FB29 Env, that the induction of fusion requires a threshold number of receptors that is greater for FB29 Env than for TR1.3 or W102G Env, and that receptor density on murine NIH 3T3 cells and BCEC is below the threshold for FB29-dependent fusion. Surprisingly, receptor density on NIH 3T3 cells could not be increased by stable expression of exogenous receptors, and FB29-dependent fusion was not observed in NIH 3T3 cells that transiently expressed elevated receptor numbers. These results suggest that an additional undefined host cell factor(s) may limit both receptor expression and fusion potential in murine cells.

C-reactive protein (CRP) in cerebro-vascular events

BACKGROUND AND PURPOSE

C-reactive protein (CRP) is a useful prognostic factor in coronary heart disease. It has not been previously studied in acute cerebro-vascular events, which was the topic of the present study.

METHODS

Patients admitted to the hospital for an acute cerebro-vascular event were prospectively investigated. C-reactive protein was determined nephelometrically. Infection or inflammation were excluded clinically and with an erythrocyte sedimentation rate <30 mm/h. Computed tomography or nuclear magnetic resonance imaging of the brain was performed.

RESULTS

According to initial brain imaging and the clinical course the 138 patients were divided into five groups: 20 with transient ischemic attack, 20 with reversible neurological deficit lasting less than 2 weeks, 61 with completed stroke and restitution, 16 with stroke without restitution and 21 with cerebral hemorrhage. Median CRP values (range) were 3.2 (2.4-13.5), 3.3 (2.4-39.4), 4.2 (2.4-73. 4), 3.4 (3.2-44.0) and 3.5 (2.4-104.0 mg/l), respectively with no significant differences between groups in a non-parametric test (Kruskal-Wallis). Risk factors for vascular disease in general and stroke in particular had no visible influence on CRP levels. No relationship was found between time interval since onset of symptoms and CRP measurement, suggesting that an acute cerebro-vascular event has little influence on CRP values.

CONCLUSION

CRP is not a useful marker to predict the outcome of an acute cerebro-vascular event on hospital admission. This is in contrast to acute coronary events.

Accelerated transplant coronary artery disease and massive silent acute myocardial infarction in a heart transplant patient--a case report and brief review of literature

This case report describes an aggressive form of accelerated atherosclerosis predicted early after transplant by dobutamine stress echocardiography in a patient who died of massive myocardial infarction 32 months after transplantation. The main objective finding of this event was markedly increased cardiac filling pressures during an elective cardiac catheterization and coronary angiography. The literature is briefly reviewed.

Cytomegalovirus infection of rats increases the neointimal response to vascular injury without consistent evidence of direct infection of the vascular wall

BACKGROUND

Previous studies suggest that infection may play a role in restenosis and atherogenesis; cytomegalovirus (CMV) is one of the implicated pathogens. To determine a potential causal role of CMV in these disease processes, we assessed whether CMV infection increases the neointimal response to injury of the rat carotid artery.

METHODS AND RESULTS

Carotid injury was performed on 60 rats; immediately thereafter, 30 rats were infected with rat CMV, and the other 30 were mock-infected. Six weeks later, rats were euthanized, and the salivary glands, spleen, and carotid arteries were harvested. CMV infection was associated with significant exacerbation of the neointimal response to injury (neointimal to medial ratio 0.81+/-0. 59 versus 0.31+/-0.38 in CMV-infected versus control rats; P<0.0001). This occurred despite absence of infectious virus from vascular tissues and detection of CMV DNA by polymerase chain reaction in the injured artery only at day 3 after infection. Persistent distant infection, associated with systemic cytokine response, was evidenced by isolation of infectious virus from homogenates of both salivary glands and spleen and by higher serum levels of interleukin (IL)-2 and IL-4 (but not interferon-gamma and tumor necrosis factor-alpha) in infected versus noninfected rats.

CONCLUSIONS

CMV infection of immunocompetent adult rats increases the neointimal response to vascular injury, suggesting that CMV may play a causal role in atherosclerosis/restenosis. Importantly, this CMV-induced response occurs even without the presence of virus in the vascular wall, suggesting that inflammatory and immune responses to infection of nonvascular tissues may contribute to the vascular response to injury.

Clinical trials in interventional cardiology

Several well-designed, randomized trials and registries have recently been completed in patients undergoing percutaneous coronary intervention (PCI) for the treatment of symptomatic coronary artery disease. These studies have further clarified the value of newer pharmacologic and mechanical approaches to patients with atherosclerotic disease and have resulted in improved clinical outcomes in patients undergoing PCI. As a result, many of the older paradigms of lesion-specific device selection have been revised to include the intricate balance of devices and drugs, tailored to the specific clinical presentation and lesion morphology in patients undergoing PCI. This article reviews several recent clinical trials and discusses their impact on early and late outcomes in patients undergoing PCI for symptomatic coronary artery disease.