Enterovirus in arteriosclerosis: a pilot study.

BACKGROUND: Various pathogens have been suspected to play a role in the initiation or amplification of the atherosclerotic lesions. Both experimental and epidemiological arguments plead for a possible role of enterovirus in this process. OBJECTIVE: To determine the prevalence of enterovirus genome in atherosclerotic plaques, in comparison with Chlamydia pneumoniae, human cytomegalovirus (hCMV) and herpes simplex virus. STUDY DESIGN: Pilot study on 18 patients who underwent artery resection. Five artery samples were tested for each patient and each pathogen by using PCR techniques whose sensitivity was evaluated for this kind of specimen. The quality of the extraction step was assessed by amplification of a fragment of the human aldolase A gene. RESULTS: The genome of at least one infectious agent was detected in artery samples from 7 of the 18 patients (38.9%). In all cases, only one of the five aliquots was found positive; a confirmation was done by sequencing the PCR product. With regards to enterovirus, four patients (22.2%) were detected positive (one of them being also positive for hCMV). CONCLUSIONS: These results suggest that small amounts of enterovirus genome are commonly found in lesions of patients with advanced arteriosclerosis. Further studies are needed to evaluate the clinical significance of this association.

A mouse model of arterial gene transfer: antigen-specific immunity is a minor determinant of the early loss of adenovirus-mediated transgene expression.

We developed a murine model of arterial gene transfer and used it to test the role of antigen-specific immunity in the loss of adenovirus-mediated transgene expression. Adenoviral vectors encoding either beta-galactosidase (beta-gal) or green fluorescent protein were infused to the lumen of normal common carotids of CD-1 and C57BL/6 mice and atherosclerotic carotids of Apoe(-/-) mice. At 3 days after gene transfer, significant reporter gene expression was detected in all strains. Transgene expression was transient, with expression undetectable at 14 days. Next, a beta-gal-expressing vector was infused into carotids of ROSA26 mice (transgenic for, and therefore tolerant of, beta-gal) and RAG-2(-/-) mice (deficient in recombinase-activating gene [RAG]-2 and therefore lacking in antigen-specific immunity). beta-Gal expression was again high at 3 days but declined substantially (>90%) by 14 days. In vivo labeling with bromodeoxyuridine revealed that carotid endothelial proliferation was increased dramatically by the gene-transfer procedure alone, likely leading to the loss of episomal adenoviral DNA. Gene transfer to normal and atherosclerotic mouse carotids can be accomplished; however, elimination of antigen-specific immune responses does not prevent the early loss of adenovirus-mediated transgene expression. Efforts to prolong adenovirus-mediated transgene expression in the artery wall must be redirected. These efforts will likely include strategies to avoid the consequences of increased cell turnover. Nevertheless, despite the brevity of expression, this mouse model of gene transfer to normal and severely atherosclerotic arteries will likely be useful for investigating the genetic basis of vascular disease and for developing gene therapies.

Change in atherosclerosis progression in HIV-infected patients: ANRS Aquitaine Cohort, 1999-2004.

This study reported the changes in carotid intima-media thickness (IMT) during a 36-month period in 233 HIV-infected patients. Median IMT increased in the first 12 months and then decreased by month 36. The prevalence of treatment with lipid-lowering agents and protease inhibitor-free highly active antiretroviral therapy regimens increased, whereas smoking prevalence decreased. The progression of atherosclerosis in HIV-infected patients can be controlled. The impact of individual measures to reduce the cardiovascular risk should be evaluated further.

Infections, immunity, and atherosclerosis: associations of antibodies to Chlamydia pneumoniae, Helicobacter pylori, and cytomegalovirus with immune reactions to heat-shock protein 60 and carotid or femoral atherosclerosis.

BACKGROUND: Atherogenesis involves inflammatory processes in which infections are incriminated as possible contributors. METHODS AND RESULTS: We evaluated cardiovascular risk factors as well as seropositivity to Chlamydia pneumoniae, Helicobacter pylori, and cytomegalovirus in a population-based study. A significant association between prevalence and severity of atherosclerosis in carotid and femoral arteries and IgA antibodies to C pneumoniae was demonstrated that was not substantially altered after adjustment for established risk factors. For anti-H pylori IgG antibodies, significant correlations to vascular disease were restricted to low social status and lesions in carotid arteries. In addition, the study design allowed us to monitor lesion progression over time. In this prospective analysis, C pneumoniae seropositivity emerged as a significant risk predictor. Antibody titers against cytomegalovirus were not a marker for prevalence or incidence of atherosclerosis in this population. Further infection parameters added to the predictive value of chlamydial serology in risk assessment: Mean odds ratios for the prevalence of carotid atherosclerosis were 4.2 and 6.3 for seropositive subjects with elevated C-reactive protein levels and clinical evidence for chronic respiratory infection, respectively. For subjects with all 3 infection parameters, the odds ratio of carotid atherosclerosis reached 10.3 (P<0.0001). Concomitantly, serum antibodies to mycobacterial heat-shock protein 65 (mHSP65) correlated with seropositivity to C pneumoniae and H pylori but not to cytomegalovirus. CONCLUSIONS: This prospective population-based study provides strong evidence for a potential atherogenic role of persistent bacterial infection, especially C pneumoniae, as indicated by serological and clinical data and demonstrates a correlation between immune reactions to mHSP65 and bacterial infections in atherogenesis.

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.

Cytomegalovirus aggravates intimal hyperplasia in rats by stimulating smooth muscle cell proliferation.

Epidemiological and animal studies suggest a role for cytomegalovirus (CMV) in restenosis. Previously, we demonstrated that proliferating smooth muscle cells (SMCs) in the injured arterial wall are particularly susceptible to CMV-induced effects. Therefore, we hypothesised that, depending on the time point of infection after vascular injury, CMV infection may affect cell proliferation either in the media or in the neointima, thereby aggravating the process of restenosis. In the present study, we focused on the individual layers of the arterial wall by evaluating, besides the neointima-to-media ratio, the medial and neointimal area and cellularity in the rat femoral artery. Vascular injury was photochemically induced in rat femoral arteries. Immediately or 14 days thereafter, rats were infected with rat CMV (RCMV) or mock infected. The presence of RCMV in the vascular wall was determined at 3, 5, 14 and 35 days after infection by quantitative real-time PCR. When rats were infected immediately after injury, a significant increase was seen only in the medial but not in the neointimal cross-sectional area. On the other hand, when rats were infected 14 days after the initial injury, a significant increase was only seen in the neointimal area, thereby confirming our hypothesis that RCMV infection primary affects proliferating SMCs. As the mean number of SMCs per microm2 in both cell layers was unchanged despite an increase in cross-sectional area, this implies that RCMV stimulated SMC proliferation. Furthermore, these vascular effects were observed without the virus being abundantly present in the vascular wall, suggesting that inflammatory and immune-mediated responses to RCMV infection are more important in aggravating the response to vascular injury than the virus itself.

Effects of MF-tricyclic, a selective cyclooxygenase-2 inhibitor, on atherosclerosis progression and susceptibility to cytomegalovirus replication in apolipoprotein-E knockout mice.

OBJECTIVES: We examined whether selective cyclooxygenase-2 (COX-2) inhibition in apolipoprotein-E (apoE) deficient mice reduces cytomegalovirus (CMV) replication, and determined whether COX-2 anti-inflammatory activity leads to decreased atherosclerosis. BACKGROUND: Evidence suggests that CMV infection contributes to atherosclerosis and that this occurs in part through inflammatory mechanisms. Cyclooxygenase-2 inhibitors are potent anti-inflammatory agents. They also inhibit CMV replication in vitro. METHODS: The apoE deficient mice were either treated or not treated with a selective COX-2 inhibitor, and either infected or not infected with CMV. Viral deoxyribonucleic acid load in salivary glands was determined by quantitative polymerase chain reaction. Atherosclerotic lesion analysis was performed by standard methods. RESULTS: In vivo COX-2 inhibition, unexpectedly increased viral load: in the CMV-infected animals viral load was 2.58 +/- 1.0 in the nontreated group, 4.74 +/- 1.38 in the group treated with 12 mg/kg/day MF-tricyclic, and 6.51 +/- 1.64 in the group treated with 24 mg/kg/day MF-tricyclic (p trend = 0.050). This increased viral load was paralleled by increased anti-CMV antibody titers. Most surprisingly, COX-2 inhibition significantly increased early atherosclerotic lesion area, independent of viral infection. CONCLUSIONS: Our study demonstrates that selective inhibition of COX-2 in vivo increases viral load. The finding that inhibition of COX-2 increases atherosclerosis development in apoE deficient mice suggests, unexpectedly, that this enzyme exerts antiatherosclerosis activity, at least in this model.

Detection of herpes simplex virus, cytomegalovirus and Epstein-Barr virus DNA in atherosclerotic plaques and in unaffected bypass grafts.

BACKGROUND: Herpes virus infections are suspected to be involved in the pathogenesis of atherosclerosis. OBJECTIVE AND METHOD: Viral DNA of herpes simplex virus (HSV), Epstein-Barr virus (EBV) and cytomegalovirus (CMV) was analyzed by real-time PCR on 48 biopsies from atherosclerotic plaques extracted by end-arterectomy (46 coronary arteries, 2 carotid arteries), and in tissue from non-atherosclerosis vessels from the same patient as controls (23 internal mammary arteries, 43 saphenous veins). RESULTS: HSV-1 DNA was detected significantly more frequently in plaques (35%) than in control veins (9%, P = 0.006). However, the frequency of HSV-1 DNA detection in the internal mammary artery grafts was as high as in plaques (22%, P = 0.28). CMV and EBV DNA were exclusively found in plaques but not in controls, with 10% for CMV (P = 0.06 versus veins, P = 0.17 versus graft arteries) and 2% for EBV (P = 1.0), respectively. HSV-2 was neither detected in plaques nor in controls. Herpes viral DNA was significantly associated only with arterial hypertension but not with other classical risk factors (P = 0.02), in accordance with the hypothesis that herpes viral infection may alter the vessel wall. CONCLUSION: We conclude that herpes viral infections may have a role in atherosclerosis and that the presence of herpes viral DNA in the grafts used for bypass surgery might constitute a potential risk for atherosclerosis or restenosis.

A study of arteriosclerosis in healthy subjects with HBV and HCV infection.

BACKGROUND: It is unclear whether infection with hepatitis B virus (HBV) or hepatitis C virus (HCV) affects arteriosclerosis. We performed a cross-sectional study to clarify the effect of HBV and HCV infection on arteriosclerosis. METHODS: The study subjects were 1806 healthy individuals who visited Shimane Environment and Health Public Corporation for routine medical check-ups. Serum levels of total cholesterol, high-density lipoprotein (HDL)-cholesterol, triglycerides, and blood glucose were investigated in all subjects. The degree of arteriosclerosis was assessed using systolic blood pressure, the bilateral ankle brachial index (ABI), the heart-carotid pulse wave velocity (HCPWV), and the heart-ankle PWV (HAPWV). These cardiovascular parameters were compared between control subjects and subjects with HBV and HCV infection, using analysis of covariance to adjust for confounding factors (sex, age, body mass index, and smoking and drinking). RESULTS: Of the 1806 subjects, 39 and 31 were diagnosed as positive for HBV and HCV infection, respectively. The remaining 1736 were considered to be the controls. Adjusted serum lipid levels in the subjects with HBV and those with HCV infection tended to be lower than those in the control subjects. Adjusted arteriosclerotic parameters in the subjects with HBV and HCV infection were similar to those in the control subjects, even after adjusting for serum lipid levels. CONCLUSIONS: Infection with HBV or HCV does not influence the severity of arteriosclerosis in healthy subjects.

Enhanced atherogenesis is not an obligatory response to systemic herpesvirus infection in the apoE-deficient mouse: comparison of murine gamma-herpesvirus-68 and herpes simplex virus-1.

Viral and bacterial infectious agents have been implicated in the etiology of atherosclerosis. We have previously shown that a gamma-herpesvirus can accelerate atherosclerosis in the apolipoprotein E-deficient (apoE-/-) mouse. To address whether a virally induced systemic immune response is sufficient to trigger enhanced atheroma formation, we infected apoE-/- mice with murine gamma-herpesvirus-68 (MHV-68) or herpes simplex virus-1 (HSV-1). In this study, we show that both viruses were able to induce a cell-mediated and humoral immune response in the apoE-/- mouse, which was sustained over a period of 24 weeks. Although intranasal or intraperitoneal infection with MHV-68 induced similar levels of virus-specific IgG1 and IgG2a antibodies in the serum of apoE-/- mice, those infected with HSV-1 showed higher anti-HSV-1 IgG2a compared with IgG1 antibody levels. In addition, viral message was not detected in the aortas of HSV-1-infected animals, whereas we have shown previously that MHV-68 mRNA can be detected in the aortas of infected mice as early as 5 days after infection. Compared with control mice, apoE-/- mice infected with MHV-68 showed accelerated atherosclerosis, whereas mice infected with HSV-1 did not. These data indicate that a systemic immune response to any particular infectious agent is insufficient to induce enhanced atherosclerosis in the apoE-/- mouse and point to specific infections or immune mechanisms that might be essential for virally enhanced atherogenesis.

Viral load of the human immunodeficiency virus could be an independent risk factor for endothelial dysfunction.

BACKGROUND: Recent reports of myocardial infarction in young persons infected with human immunodeficiency virus (HIV) who are receiving protease inhibitor therapy have raised concerns about premature coronary artery disease in this population. However, endothelial dysfunction, hypercoagulability, hypertriglyceridemia, and abnormal coronary artery pathology have been observed in association with HIV infection prior to the availability of protease inhibitor therapy. HYPOTHESIS: The study was undertaken to determine the association between endothelial function, viral load, CD4+ count, and other well-established risk factors for atherosclerosis. METHODS: This prospective, case-controlled study compared viral (HIV) load and the CD4+ T-lymphocyte count and endothelial function in 24 HIV-positive carriers. Brachial artery diameter, HIV viral load, and CD4 count were measured. RESULTS: We found that viral load correlated inversely with endothelial function; the higher the viral load, the worse the endothelial dysfunction (p < 0.005). CONCLUSION: High viral load appears to be associated with endothelial dysfunction in patients with HIV. This preliminary observation supports the infectious theory that viruses may play an important role in the pathogenesis of atherosclerosis.

Chlamydia pneumoniae seropositivity and systemic and renovascular atherosclerotic disease.

BACKGROUND: Patients with hypertension may be vulnerable to vascular Chlamydia pneumoniae and/or cytomegalovirus (CMV) infection because of increased expression of adhesion molecules. OBJECTIVE: To determine whether C pneumoniae or CMV is associated with the presence of atherosclerotic lesions in hypertensive patients. METHODS: Ninety-six angiographic studies on 100 consecutive patients with of clinical signs or symptoms suggestive of renovascular hypertension were reviewed for the presence or absence of atherosclerotic lesions at the level of the renal arteries as well and abdominal aorta. Also, the presence of a hemodynamically notable renal artery stenosis and antibodies to C pneumoniae (IgG and IgA) and CMV (IgG and IgM) was determined, and all classic risk factors were recorded. RESULTS: Atherosclerotic lesions were documented in 67 patients (70%), and in 49 patients (51%) such lesions were present at the level of the renal artery. In the univariate analysis, significant associations between IgG (odds ratio, 3.8; 95% confidence interval, 1.2-11.7; P =.02) as well as IgA (odds ratio, 2.6; 95% confidence interval, 1.1-6.7; P =.03) antibodies to C pneumoniae and the presence of atherosclerosis were found for both the aorta and the renal arteries. Seroprevalence (IgG) to C pneumoniae in the 23 patients with a hemodynamically notable renal artery stenosis was 100% and differed (P =.01) from those without a notable renal artery stenosis (78%). In the multivariate analysis, IgG seropositivity to C pneumoniae was significantly associated with atherosclerosis (odds ratio, 6.0; 95% confidence interval, 1.33-27.5; P =.02), and age. There was no association between CMV seropositivity and atherosclerosis. CONCLUSION: The presence of antibodies to C pneumoniae was significantly associated with atherosclerosis and renovascular disease in hypertensive patients in whom a renal artery stenosis was strongly suspected.

Chronic non-vascular cytomegalovirus infection: effects on the neointimal response to experimental vascular injury.

OBJECTIVE: Epidemiologic and mechanistic evidence implicates a role for cytomegalovirus (CMV) in atherogenesis. Recently, we demonstrated that CMV has the capacity to causally contribute to atherogenesis; acute infection of rats with rat CMV (RCMV) 1 day after carotid artery injury increased neointimal accumulation. Importantly, in the injured vessel infectious virus could not be detected and viral genome was present only transiently, suggesting that additional mechanisms play a role in the virus-induced exacerbation of the vascular injury response other than the changes caused by direct infection of vessel wall cells. The present investigation was designed to determine whether chronic persistent RCMV infection, more relevant to the clinical situation, also exacerbates the response to injury and, if so, whether similar mechanisms are operative. METHODS: Sixty 3-week-old male Spraque-Dawley rats received an i.p. injection of either 10(6) TCID50 RCMV (Priscott strain) or normal saline. The left carotid artery was balloon-injured 3 months after infection. Rats were killed 6 weeks later. This model produces persistent infection, as demonstrated by presence of infectious virus in the salivary glands at time of sacrifice. RESULTS: The neointima to media (N/M) ratio of the injured vessel was 41% greater in the RCMV-infected than in control rats (1.40 +/- 0.48 vs. 0.99 +/- 0.45; P = 0.003). The aorta never contained infectious RCMV, and exhibited RCMV DNA, detected by PCR, only transiently. The persistent infection of non-vascular tissues was associated with increased serum levels of IL-2, IL-4 and IFN-gamma. CONCLUSIONS: CMV infection of young rats causes persistent infection of non-vascular tissues and increased cytokine levels. The neointimal response to subsequent vascular injury is increased, despite absence of virus from the vessel wall. These findings, as in acute infection following vascular injury, suggest that inflammatory and immune responses to chronic persistent CMV infection contribute to an exaggerated response to vascular injury.

Atherosclerosis in Marek's disease virus infected hypercholesterolemic roosters is reduced by HMGCoA reductase and ACE inhibitor therapy.

OBJECTIVES: Accelerated atherosclerosis is associated with herpesviral infection both in transplant patients and after balloon angioplasty. Marek's disease virus (MDV) is a herpesvirus that induces accelerated atherosclerosis associated with the development of an invasive lymphoma in hyperlipemic roosters. We have examined the effects of pravastatin, a 3-hydroxy-3-methylglutaryl-coenzyme A (HMGCoA) reductase inhibitor and quinapril, an angiotensin converting enzyme (ACE) inhibitor, on atherosclerosis development in MDV infected, cholesterol fed rooster chicks. METHODS: The effects of these drugs on plaque growth after MDV infection were examined in two studies. In Study 1, MDV infected White Leghorn rooster chicks were divided into 4 groups assigned to normal or high cholesterol diet, and treated at three months of age with either pravastatin or saline. In Study 2, cholesterol fed rooster chicks infected with MDV were divided into 3 groups for treatment with either pravastatin, quinapril, or saline control. RESULTS: A significant decrease in plaque area was detected after 60 days of treatment with both pravastatin and quinapril in cholesterol fed chicks (P < 0.001). Lymphocyte infiltration into the arterial wall or target organs was not inhibited by treatment with either drug. CONCLUSIONS: (1) HMGCoA reductase inhibitor and ACE inhibitor therapy reduce atherosclerosis induced by virus infection and cholesterol diet, but this decrease in plaque growth is not due to a reduction in lymphocyte invasion. (2) MDV infection in cholesterol fed roosters provides a model for virus-induced arterial injury in atherogenesis.

HIV infection, highly active antiretroviral therapy and the cardiovascular system.

Cardiovascular complications in the course of human immunodeficiency virus (HIV) infection are multifactorial and may be caused by the virus itself or by the related opportunistic infections and neoplasms. Highly active antiretroviral therapy (HAART) has prolonged many patients' lives, but many cardiac sequelae of HIV are not affected by HAART and continue to develop even with treatment. In addition, HAART itself causes in a high proportion of patients a metabolic syndrome, characterized by lipodystrophy/lipoatrophy, dyslipidemia and insulin resistance that may be associated with an increase in peripheral artery and coronary artery diseases. Careful cardiovascular evaluation in the course of HIV disease can identify cardiac complications early enough to treat. All HIV-infected patients candidate to antiretroviral therapy and patients already under treatment should undergo an assessment that includes the evaluation of the cardiovascular risk with the available guidelines.

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.

Evidence for infectious agents in cardiovascular disease and atherosclerosis.

During the past decade, several novel risk factors for atherosclerosis, including inflammation and infections, have been reported. Seroepidemiological studies suggest an association between several microbes and coronary heart disease. Microbes or their structural components are found in atherosclerotic plaques, but the only intact microbes commonly present are herpes viruses and Chlamydia pneumoniae. These agents are able to initiate and accelerate atherosclerosis in animal models. If they cause persistent infection in the vessel wall, they can directly promote a proinflammatory, procoagulant, and proatherogenic environment. Microbes could also have a remote effect--e.g., bacterial heat shock proteins with high sequence homology with human counterpart could, in the presence of a chronic infection, induce autoimmunity against vascular cells, and lead to an atherosclerotic process. Several intervention trials with antibiotics are underway, and will hopefully shed new light on the role of bacteria in atherosclerosis. The causal relationship can be proved by use of vaccination to prevent infections.

Further evidence against the implication of active cytomegalovirus infection in vascular atherosclerotic diseases.

The possible contribution of cytomegalovirus (CMV) to pathogenetic events associated with atherosclerotic lesion establishment and progression is still controversial. We evaluated the possibility that active ongoing CMV infection could be correlated to evolution of unstable atheromatous lesion, by analyzing patients suffering from unstable angina (n=61), acute myocardial infarction (n=43), stable angina (n=26) and peripheral arteriopathy (n=22) as compared to healthy subjects (n=30). Particularly, we assessed: past exposure to CMV by evaluating anti-CMV IgG antibodies; ongoing CMV infection by evaluating anti-CMV IgM antibodies and circulating interleukin (IL)-8 in serum; and CMV DNAemia in peripheral blood mononuclear cells (PBMC). Mean IgG values were significantly increased in patients from all groups, as compared to healthy subjects. CMV-specific IgM, as well as CMV DNAemia, were undetectable in both controls and patients. Circulating IL-8, significantly elevated in a group of individuals experiencing active CMV infection, was not significantly higher in cardiovascular disease patients, as compared to control subjects. These findings confirm previous evidence from the increased exposure to CMV infection in patients with atheromatous lesions. However, they provide further evidence against a direct implication of active systemic CMV infection in the pathogenesis of cardiovascular diseases, particularly those involving plaque instability.

Expression of monocyte chemoattractant protein-1 cDNA in vascular smooth muscle cells: induction of the synthetic phenotype: a possible clue to SMC differentiation in the process of atherogenesis.

In the arterial wall, smooth muscle cells (SMC) normally exist in a quiescent, differentiated state, representing the contractile phenotype. During the development of atherosclerosis SMC change towards the synthetic phenotype going along with proliferation, chemotactic response and increased monocyte binding. Expression of monocyte chemoattractant protein-1 (MCP-1), a potent chemoattractant for monocytes, has been shown to be among the earliest events in atherogenesis. We investigated the effect of MCP-1 on differentiated and dedifferentiated SMC. Differentiation of SMC was induced using Matrigel as a matrix for cultivation. MCP-1 was expressed in SMC by means of a recombinant adenovirus. Expression of MCP-1 led to dedifferentiation of SMC as demonstrated by induction of cytokeratin 18, a marker for the synthetic phenotype. Concurrently, migration was only detectable in MCP-1 expressing cells, whereas SMC infected with a control virus, coding for the nuclear-targeted lacZ gene showed no migration. The expression of intercellular adhesion molecule-1 (ICAM-1) could be demonstrated in synthetic SMC and was induced after infection of differentiated cells with recombinant adenovirus, coding for MCP-1 (AdMCP-1). Expression of ICAM-1 was associated with a tenfold higher monocyte binding compared to lacZ infected cells. Our data suggest that MCP-1 plays an important role for SMC in the functional switch from the contractile to the synthetic phenotype in the course of atherogenesis.

IL-6 is produced by splenocytes derived from CMV-infected mice in response to CMV antigens, and induces MCP-1 production by endothelial cells: a new mechanistic paradigm for infection-induced atherogenesis.

Atherosclerosis is an inflammatory disease. One of the candidate inflammatory triggers is infection. To further characterize the interaction between infection, cytokine induction, and atherosclerosis, we tested the hypothesis that cytomegalovirus (CMV) infection induces the pro-inflammatory cytokine interleukin-6 (IL-6), which in turn induces "pro-atherosclerotic" changes in vascular endothelial cells (ECs). ELISA was used to determine the levels of monocyte chemoattractant protein-1 (MCP-1) in the supernatant of mouse and human ECs incubated with IL-6, and IL-6 levels in supernatants of splenocytes, derived from CMV-infected and uninfected mice, stimulated with mice CMV antigens. IL-6 induced, in a dose response fashion, MCP-1 expression in human ECs: 0, 2, 10, and 50 pg/ml IL-6 increased MCP-1 levels in EC conditioned medium from 1120+/-65 to 1148+/-105, 1395+/-40, and 2119+/-130 pg/ml, respectively (P<0.001). IL-6 also induced MCP-1 expression in mouse ECs (P<0.002). Importantly, IL-6 concentration in the supernatants of splenocytes stimulated with CMV antigens rose from undetectable levels in uninfected mice to 14.9+/-5 pg/ml in the infected mice (P<0.04). These results suggest a previously unrecognized, but potentially important mechanism whereby CMV, and other pathogens, contribute to atherogenesis: T lymphocytes, clonally expanded in response to antigens presented by CMV infection, home to sites of vascular injury and locally release IL-6 when presented with either pathogen antigens that may be present in the plaque, or when they cross-react with host peptides homologous to the relevant pathogen antigens; IL-6 then triggers ECs to release MCP-1, which recruits more monocytes and T-cells into the vessel wall and thereby exacerbates local inflammation, and thus atherogenesis.