Herpesvirus in atherosclerosis and thrombosis: etiologic agents or ubiquitous bystanders?

Fatal attractions that trigger inflammation and drive atherosclerotic disease

BACKGROUND

Atherosclerosis is the salient, underlying cause of cardiovascular diseases, such as arrhythmia, coronary artery disease, cardiomyopathy, pulmonary embolism and myocardial infarction. In recent years, atherosclerosis pathophysiology has evolved from a lipid-based to an inflammation-centric ideology.

METHODS

This narrative review is comprised of review and original articles that were found through the PubMed search engine. The following search terms or amalgamation of terms were used: "cardiovascular disease," "atherosclerosis," "inflammation," "GRP78," "Hsp60," "oxidative low-density lipoproteins," "aldehyde dehydrogenase," "β2-glycoprotein," "lipoprotein lipase A," "human cytomegalovirus." "SARS-CoV-2," "chlamydia pneumonia," "autophagy," "thrombosis" and "therapeutics."

RESULTS

Emerging evidence supports the concept that atherosclerosis is associated with the interaction between cell surface expression of stress response chaperones, including GRP78 and Hsp60, and their respective autoantibodies. Moreover, various other autoantigens and their autoantibodies have displayed a compelling connection with the development of atherosclerosis, including oxidative low-density lipoproteins, aldehyde dehydrogenase, β2-glycoprotein and lipoprotein lipase A. Atherosclerosis progression is also concurrent with viral and bacterial activators of various diseases. This narrative review will focus on the contributions of human cytomegalovirus as well as SARS-CoV-2 and chlamydia pneumonia in atherosclerosis development. Notably, the interaction of an autoantigen with their respective autoantibodies or the presence of a foreign antigen can enhance inflammation development, which leads to atherosclerotic lesion progression.

CONCLUSION

We will highlight and discuss the complex role of the interaction between autoantigens and autoantibodies, and the presence of foreign antigens in the development of atherosclerotic lesions in relationship to pro-inflammatory responses.

New Directions in Infection-Associated Ischemic Stroke

The relationship between infections and stroke has not been fully characterized, probably delaying the development of specific treatments. This narrative review addresses mechanisms of stroke linked to infections, including hypercoagulability, endothelial dysfunction, vasculitis, and impaired thrombolysis. SARS-CoV-2, the virus that causes COVID-19, may promote the development of stroke, which may represent its most severe neurological complication. The development of specific therapies for infection-associated stroke remains a profound challenge. Perhaps the most important remaining issue is the distinction between infections that trigger a stroke versus infections that are truly incidental. This distinction likely requires the establishment of appropriate biomarkers, candidates of which are elevated levels of fibrin D-dimer and anticardiolipin/antiphospholipid antibodies. These candidate biomarkers might have potential use in identifying pathogenic infections preceding stroke, which is a precursor to establishing specific therapies for this syndrome.

Coagulopathy in SARS-CoV-2 Infected Patients: Implication for the Management of COVID-19

COVID-19 disease has led to an extraordinary inclusive health crisis globally. Elevation of D-dimer is the major remarkable abnormal coagulation test in seriously ill COVID-19 patients. In nearly 50% of COVID-19 patients, the value of D-dimer was significantly enhancing. Recent literature indicated that COVID-19 patients were at higher risk of developing disseminated intravascular coagulation. Pro-inflammatory cytokines and chemokines are some of the factors leading to these conditions. The majority of COVID-19 patients showed a higher profile of pro-inflammatory cytokines and chemokines in severe clinical conditions. Tumor necrosis factor-α (TNF-α) and interleukins (ILs) elevated in COVID-19 infected patients. TNF-α, IL-6, and IL-1 are major cytokines vital for the inhibition of intrinsic anticoagulant pathways. COVID-19 becomes a higher complication with a significant effect on blood cell production and hemostasis cascades. Deep vein thrombosis and arterial thrombosis are common complications. Changes in hematological parameters are also frequently observed in COVID-19 patients. Especially, thrombocytopenia is an indicator for poor prognosis of the disease and is highly expected and aggravates the likelihood of death of SARS-CoV-2 infected individuals. Thrombopoiesis reduction in COVID-19 patients might be due to viral abuse of the bone marrow/the viral load may affect thrombopoietin production and function. In other ways, immune-inflammation-mediated destruction and increased consumption of platelets are also the possible proposed mechanisms for thrombocytopenia. Therefore, the counting of platelet cells is an easily accessible biomarker for disease monitoring. All SARS-CoV-2 infected patients should be admitted and identifying potential higher-risk patients. It is also obligatory to provide appropriate treatments with intensive care and strict follow-up. In addition, considerations of chronic diseases are essential for better prognosis and recovery. The current review discusses coagulopathy among SARS-CoV-2 infected individuals and its complication for the management of the disease.

Network analysis of host-pathogen protein interactions in microbe induced cardiovascular diseases

Large-scale visualization and analysis of HPIs involved in microbial CVDs can provide crucial insights into the mechanisms of pathogenicity. The comparison of CVD associated HPIs with the entire set of HPIs can identify the pathways specific to CVDs. Therefore, topological properties of HPI networks in CVDs and all pathogens was studied using Cytoscape3.5.1. Ontology and pathway analysis were done using KOBAS 3.0. HPIs of Papilloma, Herpes, Influenza A virus as well as Yersinia pestis and Bacillus anthracis among bacteria were predominant in the whole (wHPI) and the CVD specific (cHPI) network. The central viral and secretory bacterial proteins were predicted virulent. The central viral proteins had higher number of interactions with host proteins in comparison with bacteria. Major fraction of central and essential host proteins interacts with central viral proteins. Alpha-synuclein, Ubiquitin ribosomal proteins, TATA-box-binding protein, and Polyubiquitin-C &B proteins were the top interacting proteins specific to CVDs. Signaling by NGF, Fc epsilon receptor, EGFR and ubiquitin mediated proteolysis were among the top enriched CVD specific pathways. DEXDc and HELICc were enriched host mimicry domains that may help in hijacking of cellular machinery by pathogens. This study provides a system level understanding of cardiac damage in microbe induced CVDs.

MorCVD: A Unified Database for Host-Pathogen Protein-Protein Interactions of Cardiovascular Diseases Related to Microbes

Microbe induced cardiovascular diseases (CVDs) are less studied at present. Host-pathogen interactions (HPIs) between human proteins and microbial proteins associated with CVD can be found dispersed in existing molecular interaction databases. MorCVD database is a curated resource that combines 23,377 protein interactions between human host and 432 unique pathogens involved in CVDs in a single intuitive web application. It covers endocarditis, myocarditis, pericarditis and 16 other microbe induced CVDs. The HPI information has been compiled, curated, and presented in a freely accessible web interface (http://morcvd.sblab-nsit.net/About). Apart from organization, enrichment of the HPI data was done by adding hyperlinked protein ID, PubMed, gene ontology records. For each protein in the database, drug target and interactors (same as well as different species) information has been provided. The database can be searched by disease, protein ID, pathogen name or interaction detection method. Interactions detected by more than one method can also be listed. The information can be presented in tabular form or downloaded. A comprehensive help file has been developed to explain the various options available. Hence, MorCVD acts as a unified resource for retrieval of HPI data for researchers in CVD and microbiology.

Cerebral Venous Thrombosis as Rare Presentation of Herpes Simplex Virus Encephalitis

Herpes simplex virus 1 is a prevalent neurotropic pathogen that infects and establishes latency in peripheral sensory neurons. It can migrate into the central nervous system and cause encephalitis. The association between herpes simplex virus encephalitis and cerebral venous thrombosis is rare, with a very limited number of case reports described in the literature, despite the recognized thrombogenic effects of the virus. A 44-year-old man was brought to the emergency department with generalized tonic-clonic seizures requiring sedation and ventilation to control it. Initial brain computed tomography revealed cortical and subcortical edema on the left frontal lobe, and a subsequent contrast-enhanced exam showed absence of venous flow over the anterior half of the superior sagittal sinus. Cerebrospinal fluid polymerase chain reaction was positive for herpes simplex virus type 1, and the patient was started on acyclovir and anticoagulation, with clinical improvement. Acyclovir administration was maintained for 14 days and oral anticoagulation for one year, with no recurrence of thrombotic events or other complications. A well-timed treatment has a validated prognostic impact on herpes simplex encephalitis, making early recognition of its clinical aspects of main importance.

Comparison of cardiovascular outcomes and all-cause mortality in patients with chronic hepatitis B and C: A 13-year nationwide population-based study in Asia

BACKGROUND AND AIMS

Viral hepatitis infection has been linked to increased atherosclerosis. We therefore investigated cardiovascular outcomes in patients with hepatitis B virus (HBV) and hepatitis C virus (HCV) infection.

METHODS

Electronic medical records during 2000-2012 were retrieved from the Taiwan National Health Insurance Research Database. Exclusion criteria were age <18, history of coexisting HBV and HCV infection, acute coronary syndrome, coronary intervention, venous thromboembolism, peripheral artery disease, stroke, major or gastrointestinal bleeding, malignancy, and a follow-up period <180 days. Patients with HBV and HCV infection were propensity-matched then compared for outcomes. Primary outcomes were cardiovascular events at the 1-year follow-up, 3-year follow-up, 5-year follow-up, and at the end of follow-up.

RESULTS

41,554 patients with diagnosis of HBV or HCV were retrieved from 2000 to 2012. After exclusion criteria, 31,943 patients were eligible for analysis and propensity score matched. The study population consisted of 6030 patients with HBV infection and 6030 patients with HCV infection. Risk of composite arterial events (acute coronary syndrome, peripheral artery disease, and acute ischemic stroke) was significantly higher in patients with HCV infection compared with patients with HBV infection (p = 0.012 at 5-year follow-up and p = 0.003 at the end of follow-up). All-cause mortality was significantly higher in patients with HCV infection compared with patients with HBV infection (p < 0.001 at 3-year follow-up, 5-year follow-up, and at the end of follow-up).

CONCLUSIONS

In patients with chronic viral hepatitis, subjects with HCV infection had a significantly higher risk of composite arterial events and all-cause mortality compared with those with HBV infection.

Arterial thrombosis in the context of HCV-associated vascular disease can be prevented by protein C

Hepatitis C virus (HCV) infection is a major problem worldwide. HCV is not limited to liver disease but is frequently complicated by immune-mediated extrahepatic manifestations such as glomerulonephritis or vasculitis. A fatal complication of HCV-associated vascular disease is thrombosis. Polyriboinosinic:polyribocytidylic acid (poly (I:C)), a synthetic analog of viral RNA, induces a Toll-like receptor 3 (TLR3)-dependent arteriolar thrombosis without significant thrombus formation in venules in vivo. These procoagulant effects are caused by increased endothelial synthesis of tissue factor and PAI-1 without platelet activation. In addition to human umbilical endothelial cells (HUVEC), human mesangial cells (HMC) produce procoagulatory factors, cytokines and adhesion molecules after stimulation with poly (I:C) or HCV-containing cryoprecipitates from a patient with a HCV infection as well. Activated protein C (APC) is able to prevent the induction of procoagulatory factors in HUVEC and HMC in vitro and blocks the effects of poly (I:C) and HCV-RNA on the expression of cytokines and adhesion molecules in HMC but not in HUVEC. In vivo, protein C inhibits poly (I:C)-induced arteriolar thrombosis. Thus, endothelial cells are de facto able to actively participate in immune-mediated vascular thrombosis caused by viral infections. Finally, we provide evidence for the ability of protein C to inhibit TLR3-mediated arteriolar thrombosis caused by HCV infection.

Associations between excessive adiposity and seroprevalence of herpes simplex virus type 1 and type 2 among US adults: a population-based age-period-cohort analysis

OBJECTIVES

Evidence on the association between herpes simplex virus (HSV) and excessive adiposity, such as obesity (body mass index ≥30 kg/m2) and abdominal obesity (waist circumference (WC) >102 or 88 cm), has been inconsistent. We sought to examine whether age-period-cohort (APC) effects could explain for the observed heterogeneities.

DESIGN

Population-based cross-sectional study.

PARTICIPANTS

Adults aged 20-49 years with available serological data in the National Health and Nutrition Examination Survey (NHANES) in 1999-2012.

EXPOSURE MEASURES

Obesity and abdominal obesity.

RESULTS

In men, excessive adiposity was generally not associated with HSV1 or HSV2 (all p>0.05); however, there were positive correlations between HSV seroprevalence and excessive adiposity in certain age and birth cohort groups. Based on APC analysis, abdominally obese men aged 30-40 years showed a nearly 20% increase in risk for HSV1 seropositivity (adjusted prevalence ratio (aPR)=1.18; 95% CI 1.10 to 1.27) as compared with abdominally non-obese men of the same age; there was no such association in men of other age groups. Also, men of a large WC who were born before 1962 or after 1979 had a 28% higher risk for HSV2 seropositivity than those of a normal WC in the same birth cohorts (aPR=1.28, 95% CI 1.17 to 1.54); yet the association did not hold for men in other cohorts (aPR=0.86, 95% CI 0.64 to 1.17). In women, a large WC was correlated with a minimally increased HSV1 seroprevalence (aPR=1.07, 95% CI 1.01 to 1.13) but not with HSV2 seropositivity (aPR=1.13; 95% CI 0.99 to 1.28). Likewise, there were strong associations between abdominal obesity and HSV2 seropositivity in subgroups of women participating in the earliest survey cycle (aPR=1.41, 95% CI 1.12 to 1.78) but not in other survey periods (aPR=0.94, 95% CI 0.85 to 1.03).

CONCLUSIONS

There was no consistent evidence for strong associations between HSV seropositivity and excessive adiposity in adults. APC analysis results further cautioned the generalisability of previous reports based on 1 or 2 cycles of survey data.

Cytomegalovirus-Productive Infection Is Associated With Acute Coronary Syndrome

BACKGROUND

Although an association between human herpesvirus (HHV) infection and atherosclerosis has been suggested, the data supporting such an association are controversial and, in most cases, are based on serological evidence or on the presence of cell-associated HHV DNA, which do not report about actual viral replication. We quantified the DNA of all 8 types of HHVs in plasma, in which their presence is evidence of viral replication.

METHODS AND RESULTS

Using quantitative real-time polymerase chain reaction, we evaluated the presence of HHV DNA in blood samples obtained at the time of hospitalization from 71 patients with acute coronary syndrome, 26 patients with stable coronary artery disease, and 53 healthy volunteers and in atherosclerotic plaques of 22 patients with peripheral artery disease who underwent endarterectomy. HHV-5 (cytomegalovirus [CMV]) was the only HHV with a level that was higher in acute coronary syndrome patients than in the control group and that correlated with the level of high-sensitivity C-reactive protein. The numbers of effector memory T cells positively correlated with the numbers of CMV genome copies in carotid arteries plaques, whereas the numbers of central memory T cells negatively correlated with CMV copy numbers.

CONCLUSIONS

Of all HHV levels, only CMV was higher in patients with stable coronary artery disease and acute coronary syndrome than in the healthy group, and its load correlated with the level of high-sensitivity C-reactive protein. The level of CMV in atherosclerotic plaques correlated with the state of immunoactivation of lymphocytes in plaques, suggesting that the reactivation of CMV may contribute to the immune activation associated with the progression of atherosclerosis.

Herpes simplex virus 2 infects human endothelial ECV304 cells and induces cell apoptosis synergistically with ox-LDL

Virus infection has been shown to accelerate atherosclerosis. Serological studies indicate a link between the Herpes simplex virus (HSV) infection and atherosclerosis, which is initiated and progression of which is promoted by such factors as oxidized low-density lipoprotein (ox-LDL)-induced endothelial dysfunction. In order to recognize the direct role of HSV-2 in endothelial dysfunction, the present study investigated the infection of HSV-2 in endothelial ECV304 cells and the induction of cell apoptosis in the presence of ox-LDL. We firstly examined the HSV-2 infection by immunohistochemical assay for viral gB protein, quantitative PCR for viral ICP4 mRNA, or via virus growth determination. Then we investigated the regulation of HSV-2 infection on the cell viability and apoptosis, in the absence or presence of ox-LDL. In addition, we analyzed the apoptosis-associated molecules in the HSV-2-infected ECV304 cells. The results demonstrated that HSV-2 infected endothelial ECV304 cells and replicated efficiently, and the virus infection significantly reduced the cell viability and significantly induced cell apoptosis; particularly, cell viability reduction and cell apoptosis induction were aggravated by the ox-LDL presence. Moreover, the western blot assay confirmed the apoptosis induction; there was a significantly high level of released cytochrome c, activated caspase 3 and lyzed Poly (ADP-ribose) polymerase (PARP) by the activated caspase 3 in the HSV-2-infected ECV304 cells, particularly the cells subject to ox-LDL. Thus, we confirmed that HSV-2 infected endothelial ECV304 cells, induced cell apoptosis, which was aggravated by ox-LDL.

Seropositivity to herpes simplex virus type 2, but not type 1 is associated with premature cardiovascular diseases: a population-based cross-sectional study

OBJECTIVE

Thirty-five years after herpesviruses were suggested to induce atherosclerosis sero-epidemiological evidence on Herpes Simplex Viruses (HSV) remains sparse and controversial. We aimed to investigate the relationship between HSV-1 and HSV-2 infections and cardiovascular diseases (CVD).

METHODS AND RESULTS

A population-based cross-sectional study was conducted among 14,415 participants (mean age 34.3 years, range 20-49) of the National Health and Nutrition Examination Survey 1999-2010. Serum IgG-antibodies to HSV were measured by enzymatic immunodot assay and CVD were self-reported. CVD prevalence was 1.8%; 51.3% of participants were infected with HSV-1, 7.5% with HSV-2, and 15.2% with both. After adjusting for demographics, socioeconomic status, comorbidities, STD, and CVD risk factors, seropositivity to HSV-2 was positively associated with CVD (Odds ratio [OR] 1.56, 95% confidence interval [CI]: 1.09-2.21, P = 0.014), but not with HSV-1 (OR 1.13, 95% CI: 0.79-1.62).

CONCLUSION

HSV-2 may be associated with premature CVD, but not HSV-1.

Supra-additive expression of interleukin-6, interleukin-8 and basic fibroblast growth factor in vascular smooth muscle cells following coinfection with Chlamydia pneumoniae and cytomegalovirus as a novel link between infection and atherosclerosis

BACKGROUND

Chlamydia pneumoniae and human cytomegalovirus (HCMV) may be involved in the pathogenesis of atherosclerosis. Prospective studies indicate an increased risk for cardiovascular events in patients with evidence of multiple infections.

OBJECTIVE

To determine whether there is a synergistic effect of coinfection with C pneumoniae and HCMV on expression of selected growth factors and cytokines.

METHODS

The production of interleukin (IL)-6, IL-8, basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF), and 'regulated on activation normal T-cell expressed and secreted' (RANTES) was measured in coinfected aortic smooth muscle cells (AoSMC).

RESULTS

Using reverse transcription polymerase chain reaction and immunoassays, it was demonstrated that the expression of IL-6, IL-8, RANTES and bFGF was stimulated in a dose- and time-dependent fashion in C pneumoniae and also in HCMV-infected cultures. In contrast, the expression of PDGF-AA was only stimulated following HCMV infection. Coinfection with C pneumoniae and HCMV resulted in a supra-additive stimulation of IL-6 (30% increased expression, P≤0.05) at 48 h, IL-8 (137% increased expression, P≤0.001) at 24 h and bFGF (209% increased expression, P≤0.01) at 48 h following infection.

CONCLUSIONS

The findings of the present study show that C pneumoniae and HCMV are able to act in synergy in coinfected AoSMC. The supra-additive induction of AoSMC growth factors and cytokines indicates a novel molecular link between infection and vascular disease development.

Increased carotid intima-media thickness associated with antibody responses to varicella-zoster virus and cytomegalovirus in HIV-infected patients

Objective

We investigated the relationship of the Herpesviridiae with inflammation and subclinical atherosclerosis in HIV-infected patients.

Methods

Prospective study including virologically suppressed HIV-infected patients. IgG antibodies against herpesviruses, carotid intima-media thickness (cIMT), endothelial function through flow-mediated dilatation (FMD) of the brachial artery, and blood atherosclerosis biomarkers (hsCRP, TNF-α, IL-6, MCP-1, MDA, sCD14, sCD163, VCAM-1, ICAM-1, D-dimer, and PAI-1) were measured.

Results

136 patients with HIV viral load <200 copies/ml were included. 93.4% patients were infected with herpes simplex virus type-1, 55.9% with herpes simplex virus type-2, 97.1% with varicella-zoster virus, 65.4% with human herpesvirus-6, 91.2% with cytomegalovirus, and 99.3% with Epstein-Barr virus. Previous AIDS diagnosis was associated with higher cytomegalovirus IgG titers (23,000 vs 17,000 AU, P = 0.011) and higher varicella-zoster virus IgG titers (3.19 vs 2.88 AU, P = 0.047), and there was a positive correlation of the Framingham risk score with IgG levels against cytomegalovirus (Spearman's Rho 0.216, P = 0.016) and Herpes simplex virus-2 (Spearman's Rho 0.293, P = 0.001). IgG antibodies against cytomegalovirus correlated in adjusted analysis with the cIMT (P = 0.030). High seropositivity for varicella-zoster virus (OR 2.91, 95% CI 1.05–8.01, P = 0.039), and for cytomegalovirus (OR 3.79, 95% CI 1.20–11.97, P = 0.023) were predictors for the highest quartile of the cIMT in adjusted analyses. PAI-1 levels were independently associated with cytomegalovirus IgG titers (P = 0.041), IL-6 and ICAM-1 levels with varicella-zoster virus IgG (P = 0.046 and P = 0.035 respectively), and hsCRP levels with Herpes simplex virus-2 IgG (P = 0.035).

Conclusion

In virologically suppressed HIV-infected patients, antibody responses against herpesviruses are associated with subclinical atherosclerosis, and with increased inflammation and coagulation biomarkers.

Review: Viral infections and mechanisms of thrombosis and bleeding

Viral infections are associated with coagulation disorders. All aspects of the coagulation cascade, primary hemostasis, coagulation, and fibrinolysis, can be affected. As a consequence, thrombosis and disseminated intravascular coagulation, hemorrhage, or both, may occur. Investigation of coagulation disorders as a consequence of different viral infections have not been performed uniformly. Common pathways are therefore not fully elucidated. In many severe viral infections there is no treatment other than supportive measures. A better understanding of the pathophysiology behind the association of viral infections and coagulation disorders is crucial for developing therapeutic strategies. This is of special importance in case of severe complications, such as those seen in hemorrhagic viral infections, the incidence of which is increasing worldwide. To date, only a few promising targets have been discovered, meaning the implementation in a clinical context is still hampered. This review discusses non‐hemorrhagic and hemorrhagic viruses for which sufficient data on the association with hemostasis and related clinical features is available. This will enable clinicians to interpret research data and place them into a perspective. J. Med. Virol. 84:1680–1696, 2012. © 2012 Wiley Periodicals, Inc.

Herpesviruses enhance fibrin clot lysis

The incorporation of virus- and host-derived procoagulant factors initiates clotting directly on the surface of herpesviruses, which is an explanation for their correlation to vascular disease. The virus exploits the resulting thrombin to enhance infection by modulating the host cell through protease activated receptor (PAR) 1 signalling. Prior reports demonstrated that at least one herpesvirus expresses surface annexin A2 (A2), a cofactor for tissue plasminogen activator (tPA)-dependent activation of plasminogen to plasmin. Since plasmin is both a fibrinolytic protease and PAR agonist, we investigated whether herpesviruses enhance fibrinolysis and the effect of plasmin on cell infection. Herpes simplex virus types 1 (HSV1) and 2, and cytomegalovirus (CMV) purified from various cell lines each accelerated the proteolytic activation of plasminogen to plasmin by tPA. Ligand blots identified A2 as one of several plasminogen binding partners associated with the virus when compared to an A2-deficient virus. This was confirmed with inhibitory A2-antibodies. However, A2 was not required for virus-enhanced plasmin generation. HSV1, HSV2 and CMV accelerated tPA-dependent fibrin clot lysis by up to 2.8-fold. Modest plasmin generation and fibrinolysis was detected independent of exogenous tPA, which was inhibited by plasminogen activator inhibitor type-1 and ε-aminocaproic acid; however, the molecular basis remains speculative. Up to a ~6-fold enhancement of infection was provided by plasmin-mediated cell infection. Inhibitory antibodies revealed that plasmin increased HSV1 infection through a mechanism involving PAR2. Thus, virus-enhanced fibrinolysis may help explain the paradox of the highly procoagulant in vitro herpesvirus surface eliciting only relatively weak independent vascular disease risk.

Chlamydia in canine or feline coronary arteriosclerotic lesions

BACKGROUND

There are numerous reports linking Chlamydia infection to human coronary atherosclerosis. However, there is a lack of data regarding this correlation in dogs and cats, and there are no reports investigating coronary arteriosclerosis and Chlamydia in these species. The aim of the present study was to examine whether there is a correlation between canine and feline spontaneous atherosclerosis or arteriosclerosis and the presence of Chlamydia. Archived histopathological samples of dogs (n = 16) and cats (n = 13) with findings of atherosclerosis or arteriosclerosis in heart tissue were examined for the presence of Chlamydiaceae using real-time PCR, ArrayTube Microarray and immunohistochemistry. Additionally, arteriosclerotic lesions of all cases were histologically classified and graded.

RESULTS

Both canine atherosclerotic cases, and all 14 canine arteriosclerotic cases were negative for Chlamydia. Only one of the 13 arteriosclerotic feline cases was positive for Chlamydia by real-time PCR, revealing C. abortus by ArrayTube Microarray. To our knowledge, this is the first description of C. abortus in a cat. Overall, the type and grade of canine and feline arteriosclerotic lesions revealed similarities, and were predominantly moderate and hyperplastic.

CONCLUSIONS

These findings suggest that there is no obvious correlation between canine and feline coronary arteriosclerosis and the presence of Chlamydia. In order to draw final conclusions about the correlation between Chlamydia and canine atherosclerosis, examination of more samples is required.

Detection of human herpesvirus 6 DNA but not human herpesvirus 7 or 8 DNA in atherosclerotic and nonatherosclerotic vascular tissues

INTRODUCTION

Various viral infections are thought to play a role in the development of atherosclerosis. A number of studies suggest that certain viruses from the Herpesviridae family in particular may lead to atherosclerosis.

METHODS

We investigated the presence of human herpesvirus 6 (HHV-6), human herpesvirus 7 (HHV-7), and human herpesvirus 8 (HHV-8) DNA in carotid, iliac, and coronary artery specimens obtained from a group of adult autopsy cases by means of polymerase chain reaction (PCR) analysis and nested PCR techniques. A 28-subject study group with at least type IV atherosclerosis and a 25-subject control group with no visible atherosclerosis were enrolled.

RESULTS

HHV-6 DNA was found in the carotid artery specimen of 1 subject with atherosclerosis, in an iliac artery specimen of another subject, and in the iliac artery specimen of one of the control subjects. HHV-7 or HHV-8 DNA was not found in either the atherosclerosis or control cases.

CONCLUSIONS

This study is the first to demonstrate the presence of HHV-6 in atherosclerotic vascular tissues. HHV-7 and HHV-8 were not found in atherosclerotic tissues; however, further research on broader study groups and with different protocols is needed to determine whether these viruses play a role in the formation of atherosclerosis.

Prevalence of Chlamydophila pneumoniae is higher in aorta and coronary artery than in carotid artery of coronary artery disease patients

Coronary artery disease (CAD) is a public health problem accounting for an estimated one-third of deaths overall. A potential link between infectious agents and atherosclerosis has been suggested. Data obtained from several seroepidemiological studies have suggested that infection with Chlamydophila pneumoniae, Helicobacter pylori, cytomegalovirus and herpes simplex virus-1 can initiate or maintain the atherosclerotic process. However, there is no single study in which multiple infectious agents have been detected together in different vascular locations in the same population. This would help in determining if there is any leading pathogen in atheromatous plaques of CAD patients. Hence, we screened for C. pneumoniae, H. pylori, CMV and HSV-1 in different vascular locations of CAD patients using quantitative real-time (RT) PCR. We performed multiplex RT-PCR for detecting pathogens, viz. C. pneumoniae, H. pylori, CMV and HSV-1 in different vascular locations of CAD patients. Percent positivity scores for C. pneumoniae, H. pylori, CMV and HSV-1 in different vascular locations were as follows: aorta (64.7, 35.3, 11.7 and 11.7 respectively); carotid (27.2, 27.2, 9 and 0 respectively); coronary artery (58.3, 33.3, 16.6 and 8.3 respectively). Combined positivity for C. pneumoniae (C. pneumoniae IgA and RT-PCR for C. pneumoniae) was the highest compared with all other groups. Aorta and coronary artery were more susceptible to these pathogens as compared with carotid artery. Moreover, CAD patients' characteristics were associated with C. pneumoniae positivity (C. pneumoniae IgA and RT-PCR), suggesting thereby that C. pneumoniae may have caused chronic persistent infection in CAD.

Persistent pathogens linking socioeconomic position and cardiovascular disease in the US

BACKGROUND

Numerous studies have documented a strong inverse association between cardiovascular disease and socioeconomic position (SEP). Several infections are associated with both cardiovascular disease and SEP; hence infection may form an important link between SEP and cardiovascular disease. This study examines whether seropositivity to cytomegalovirus (CMV), to herpes simplex virus type-1 (HSV-1), and/or to both pathogens mediates the relationship between SEP and cardiovascular disease history in a nationally representative sample of the United States.

METHODS

We conducted a cross-sectional study of subjects > or =45 years of age, who were tested for seropositivity to CMV, HSV-1 or both pathogens and assessed for cardiovascular disease history in the National Health and Nutrition Examination Survey III. Cardiovascular disease history was defined as history of stroke, heart attack and/or congestive heart failure and SEP as education level.

RESULTS

SEP was associated with CMV, HSV-1 and seropositivity to both pathogens. CMV seropositivity was associated with cardiovascular disease history even after adjusting for confounders as well as SEP. The odds of reporting a history of cardiovascular disease for those with less than a high school education compared with those with more than a high school education decreased by 7.7% after adjusting for CMV (Sobel mediation test for CMV, P = 0.0006). In contrast, neither seropositivity to HSV-1 nor to both pathogens was associated with cardiovascular disease history after adjusting for SEP.

CONCLUSIONS

Persistent pathogens such as CMV infection may explain a portion of the relationship between SEP and cardiovascular disease in the United States. Further studies examining additional pathogens and sociobiological mechanisms are warranted.

The prediction of coronary atherosclerosis employing artificial neural networks

BACKGROUND

Atherosclerosis is a complex histopathologic process that is analogous to chronic inflammatory conditions. Several factors have been shown to correlate with the extent of atherosclerosis. Whereas hypertension, obesity, hyperlipidemia, diabetes, smoking, and family history are all well documented, recent literature points to additional associated factors. Thus, antibodies to oxidized low-density lipoprotein (oxLDL), cytomegalovirus (CMV), Chlamydia pneumonia, Helicobacter pylori, as well as homocysteine and C-reactive protein (CRP) levels have all been implicated as independent markers of accelerated atherosclerosis.

HYPOTHESIS

In the current study we attempted to formulate a system by which to predict the extent of coronary atherosclerosis as assessed by angiographic vessel occlusion.

METHODS

The 81 patients were categorized as having single-, double-, triple-, or no vessel involvement. The clinical data concerning the "classic" risk factors were obtained from clinical records, and sera were drawn from the patients for determination of the various parameters that are thought to be associated with atherosclerosis.

RESULTS

Using four artificial neural networks, we have found the most effective parameters predictive of coronary vessel involvement were (in decreasing order of importance) antibodies to oxLDL, to cardiolipin, to CMV, to Chlamydia pneumonia, and to beta 2-glycoprotein I (beta 2GPI). Although important in the prediction of vessel occlusion, hyperlipidemia, hypertension, CRP levels, and diabetes were less accurate.

CONCLUSION

The results of the current study, if reproduced in a larger population, may establish an integrated system based on the creation of artificial neural networks by which to predict the extent of atherosclerosis in a given subject fairly and noninvasively.

Inflammation at the molecular interface of atherogenesis: an anthropological journey

Despite the multifactorial nature of atherosclerosis, substantial evidence has established inflammation as an often surreptitious, yet critical and unifying driving force which promotes disease progression. To this end, research has defined molecular networks initiated by cytokines, growth factors and other pro-inflammatory molecules which promote hallmarks of atherosclerosis such as endothelial dysfunction, macrophage infiltration, LDL oxidation, cell proliferation and thrombosis. Although commonly associated with risk factors such as dyslipidemia, diabetes and hypertension, the global etiology of atherosclerosis may be alternatively attributed to underlying anthropological pressures. The agricultural, industrial and technological revolutions produced alterations in dietary, social and economic factors which have collectively exaggerated the exposure of the human genome to environmental stimuli. Furthermore, advances in sanitation, nutrition, and medicine have increased the lifespan of humans, effectively prolonging blood vessel exposure to these factors. As a result, the vasculature has become conditioned to respond to injury with what is arguably an overzealous immunological response; thus setting the stage for the prevalence of cardiovascular disease, including atherosclerotic plaque development in Western populations. Evidence suggests that each of these alterations can be linked to specific mediators in the inflammatory process. Integration of these factors with an inflammation-based hypothesis of atherosclerosis has yet to be extrapolated to observations in the realms of basic and clinical sciences and is the focus of this review.

Molecular basis of human CD36 gene mutations

CD36 is a transmembrane glycoprotein of the class B scavenger receptor family. The CD36 gene is located on chromosome 7 q11.2 and is encoded by 15 exons. Defective CD36 is a likely candidate gene for impaired fatty acid metabolism, glucose intolerance, atherosclerosis, arterial hypertension, diabetes, cardiomyopathy, Alzheimer disease, and modification of the clinical course of malaria. Contradictory data concerning the effects of antiatherosclerotic drugs on CD36 expression indicate that further investigation of the role of CD36 in the development of atherosclerosis may be important for the prevention and treatment of this disease. This review summarizes current knowledge of CD36 gene structure, splicing, and mutations and the molecular, metabolic, and clinical consequences of these phenomena.

Molecular basis of human CD36 gene mutations

CD36 is a transmembrane glycoprotein of the class B scavenger receptor family. The CD36 gene is located on chromosome 7 q11.2 and is encoded by 15 exons. Defective CD36 is a likely candidate gene for impaired fatty acid metabolism, glucose intolerance, atherosclerosis, arterial hypertension, diabetes, cardiomyopathy, Alzheimer disease, and modification of the clinical course of malaria. Contradictory data concerning the effects of antiatherosclerotic drugs on CD36 expression indicate that further investigation of the role of CD36 in the development of atherosclerosis may be important for the prevention and treatment of this disease. This review summarizes current knowledge of CD36 gene structure, splicing, and mutations and the molecular, metabolic, and clinical consequences of these phenomena.

Herpes simplex virus infection, massive pulmonary thromboembolism, and right atrial thrombi in a single patient: Case report

We report a 32-year-old man with herpes simplex virus encephalitis who developed massive pulmonary thromboembolism with mobile right atrial thrombi during treatment for this condition. It was not safe to use thrombolytic therapy because of the high risk of cerebral bleeding associated with encephalitis. The patient was initially treated at another center, but his condition deteriorated during nadroparin therapy and he was referred to our hospital. Nadroparin was discontinued, and a continuous infusion of unfractionated heparin was administered through a central venous catheter. The patient's general status improved over the next 24 hours, and all thrombi in the right atrium disappeared. There was immediate lysis of the thrombi after the continuous infusion of unfractionated heparin was initiated. We suggest that central-line infusion of this agent is preferable to peripheral infusion in such cases. Further research on the potential thrombolytic effect of heparin is needed.

Is Atherosclerosis a Multifactorial Disease or Is It Induced by a Sequence of Lipid Peroxidation Reactions?

The delivery of not only free cholesterol but also cholesterol esters to cells by low-density lipoprotein (LDL) has hitherto been unstudied. Minor compounds present in mammalian-derived food include cholesterol linoleate and arachidonate. Evidence is presented that these esters are directly incorporated into VLDL and are responsible for the deleterious effects of atherosclerosis. Cholesterol esterified with these polyunsaturated fatty acids (PUFAs) is readily oxidized at the PUFA residue during storage and heating. Apparently, the liver is unable to distinguish between nonoxidized and oxidized cholesterol PUFA esters and also incorporates the latter into VLDL, which is transformed to LDL. When this LDL is transferred to endothelial cells, the toxic products are liberated and induce cell damage. Cell damage is combined with structural changes that influence neighboring cells and cause an influx of Ca2+ ions and activation of phospholipases and lipoxygenases, resulting in production of lipid hydroperoxides (LOOHs). When the level of free PUFAs generated by phospholipases exceeds a certain limit, lipoxygenases commit suicide, causing liberation of iron ions. The latter react with LOOHs and thus induce a switch from enzymatic to nonenzymatic generation of lipid peroxidation (LPO) products. Although the LOO. radicals produced in enzymatic reactions are deactivated within the enzyme complex, LOO. radicals generated in nonenzymatic reactions are able to attack any biological compound, inducing severe damage. Apparently, iron ions and LOOH molecules at the surface of injured cells transfer the nonenzymatic LPO reactions to the phospholipid layer of bypassing lipoproteins, thus explaining why inflammatory diseases, such as diabetes, are combined with atherogenesis.

Demonstration of intracellular microorganisms (Rickettsia spp., Chlamydia pneumoniae, Bartonella spp.) in pathological human aortic valves by PCR

OBJECTIVES

Rickettsiae, which causes vasculitis, has not been linked to atherosclerotic cardiovascular disease in contrast to Chlamydia pneumoniae whose association with coronary artery disease and with sclerotic heart valves in patients undergoing aortic valve replacement is well established, even if causality is yet to unproven. In the search for any of these infectious agents, 84 pathological and 15 normal aortic heart valves of patients undergoing forensic autopsy were analysed by PCR and DNA-sequencing.

METHODS

Two to four pieces of all valves were examined by semi-nested PCR, with primers specific for 16S rDNA, citrate synthase (gltA) and 17 kDa outer membrane protein (OMP) genes.

RESULTS

Genetic material from Rickettsia spp. and C. pneumoniae was found in 17 (20.2%) and 22 (26.2%), respectively, of the 84 pathological aortic valves. In 35 (41.7%) of these 84 valves either C. pneumoniae or Rickettsia spp. were detected by PCR and in six cases (7.1%) these two organisms co-existed. In one case with Lambl's excrescences, previously considered as aseptic, presence of rickettsia-like organisms also was demonstrated by light microscopy, immunohistochemistry and sequencing of the amplified PCR product showing 100% homology with the published sequence for R. helvetica. In three of the 15 control valves, genetic material from only C. pneumoniae was detected compared to Rickettsia spp. that was significantly detected only in the pathological valves (Fisher's Exact test, 1-sided p = 0.046).

CONCLUSIONS

The findings suggest that Rickettsia spp. also have a role in the pathogenesis of aortic valve disease.

HIV-associated coronary artery disease

Cases, case series, and related articles on coronary artery disease in patients with human immunodeficiency virus (HIV) infection and acquired immunodeficiency syndrome (AIDS) identified through a comprehensive literature search were examined for clinical characteristics and angiographic findings of HIV-associated coronary artery disease. Among 129 identified cases, 91% were males. The mean age was 42.3 +/- 10.2 (SD) years (range, 23 to 77 years). The interval between the diagnosis of HIV infection and the diagnosis of coronary artery disease was 72 +/- 60 (SD) months. Degree of immunosuppression was variable (CD4 mean, 313 +/- 209 cells/mm3; range, 6-1070 cells/mm3). There was no correlation between the CD4 cell count and the development and progression of coronary artery disease. Similarly, the development and progression of coronary artery disease was independent of the presence of HIV-related opportunistic infections. Acute myocardial infarction was the initial presentation in 77% of patients. In 76 patients, information on diseased vessels was available: 36 (47%) patients had 3-vessel disease, 14 (18%) patients had 2-vessel disease, and 26 patients (35%) had 1-vessel disease. The left anterior descending artery was involved in 47 (62%) patients while the left circumflex and right coronary arteries were involved in 34 (45%) and 38 (50%) patients, respectively. Thirty-two (25%) patients underwent catheter-based or surgical revascularization. Data were not adequate to assess the prognosis following the acute coronary events or revascularization. The histologic characteristics unique to HIV-associated coronary arteriopathy were diffuse circumferential involvement of the vessel with an unusual proliferation of smooth muscle cells, mixed with abundant elastic fibers, resulting in endoluminal protrusions. Coronary artery disease was a late complication of AIDS.

Herpes viruses, cytokines, and altered hemostasis in vital exhaustion

OBJECTIVE

Infections with herpes viruses have been implicated in the pathogenesis of atherosclerosis. We tested the hypothesis that vital exhaustion (VE) is associated with multiple herpesvirus infections, such as herpes simplex virus, varicella-zoster virus, Epstein-Barr virus, and cytomegalovirus, and with an increase in pathogen burden (ie, the aggregated seropositivity to immunoglobulin G antibodies for herpes simplex virus, varicella-zoster virus, Epstein-Barr virus, and cytomegalovirus). In addition, we examined the association of VE and pathogen burden with measures of hemostasis and inflammation.

METHODS

Blood samples were drawn from 29 men with VE and 30 male control subjects, all healthy and nonsmokers, to assess serological evidence of infection and measures of hemostasis and inflammation.

RESULTS

VE is associated with a relatively high pathogen burden, altered hemostasis, and higher levels of cytokines, such as interleukin-6. Across all subjects, a relatively high pathogen burden was also associated with altered hemostasis but not with increased cytokine levels. The interaction of VE with pathogen burden revealed significant linear increases in measures of hemostasis and inflammation. Finally, immunoglobulin G antibody titer levels of individual herpesvirus infections were not associated with hemostatic measures or with cytokines.

CONCLUSIONS

We conclude that stress-related alterations in hemostasis and inflammation are not necessarily linked to one particular herpesvirus infection but rather to an increase in aggregated seropositivity to herpesvirus infections.

The relation between Helicobacter pylori and atherosclerosis cannot be explained by a high homocysteine concentration

BACKGROUND

Recent studies have suggested that a chronic infection with Helicobacter pylori might be an independent risk factor for atherosclerosis. However, a direct role in atherogenesis is not plausible, since the bacterium has not been isolated from atherosclerotic lesions. An indirect mechanism that could link H. pylori with atherosclerosis might be through an increase in plasma homocysteine concentration caused by deficiencies of vitamin B12 and folate in plasma.

MATERIALS AND METHODS

In 150 female patients with peripheral arterial disease (PAD) and in 412 healthy control women from a nation-wide population-based case-control study, blood samples were collected to determine the antibody titre against H. pylori and to measure plasma homocysteine, folate and vitamin B12 levels. First, the odds ratio for PAD in women with a positive antibody titre against H. pylori was calculated and adjusted for homocysteine level. Secondly, mean concentrations of vitamin B12, folate and homocysteine were compared in healthy controls with a positive or negative antibody titre against H. pylori. Thirdly, the relation between H. pylori and PAD in individuals with a normal or high homocysteine level was investigated.

RESULTS

A positive immunoglobulin G antibody titre against H. pylori was found in 42% of the PAD patients and in 27% of the controls. The age- and socio-economic-status (SES) adjusted odds ratio for PAD was 1.5 (95%CI; 1.0-2.2). Additional adjustment for homocysteine plasma concentration did not essentially change the odds ratio. Secondly, among the healthy controls, the homocysteine plasma concentration did not depend on the immunoglobulin G titre, neither did the folate plasma concentration. The concentration of vitamin B12 was slightly higher in women with a positive titre. Thirdly, H. pylori infection was a risk factor for PAD in subjects with a normal homocysteine concentration [OR 2.0 (95%CI 1.3-3.1)].

CONCLUSIONS

This study shows a relationship between a positive immunoglobulin G antibody titre against H. pylori and PAD in young women. Moreover, this study does not support the hypothesis that H. pylori infection is related to atherosclerosis via an increase in plasma homocysteine concentration.

Susceptibility of bovine umbilical cord endothelial cells to bovine herpesviruses and pseudocowpox virus

The purpose of the study was to determine the susceptibility of bovine umbilical cord endothelial (BUE) cells to bovine herpesvirus (BHV) 1, BHV2, BHV4 and BHV5, and to pseudocowpox virus. The detection limits and growth curves of these viruses in BUE cells were compared with those in Vero, Madin-Darby bovine kidney (MDBK). or bovine fetal diploid lung (BFDL) cells. Detection limits were determined by inoculating cell cultures with serial 10-fold dilutions of these viruses, and growth curves by titration of virus, harvested at various times after infecting cells at a multiplicity of infection of 0.1. The detection limits of BHV2 and BHV4 were lower in BUE cells than in Vero or MDBK cells, and cytopathic effects were observed earlier in BUE cells. In addition, BHV2 and BHV4 grew to higher titres in BUE cells than in Vero or MDBK cells. BUE cells appeared to be equally susceptible to BHV5, but less susceptible to BHV1.1 and BHVI.2 than MDBK cells. The study showed that BUE cells are highly susceptible to BHV2 and BHV4. and that the use of BUE cells can improve the laboratory diagnosis of these viruses. The use of BUE cells could also improve the isolation and growth of pseudocowpox virus.

Herpesvirus (HSV-1, EBV and CMV) infections in atherosclerotic compared with non-atherosclerotic aortic tissue

The viral nucleic acid of herpes simplex virus type 1 (HSV-1), Epstein-Barr virus (EBV) and cytomegalovirus (CMV) was studied by polymerase chain reaction (PCR), Southern blotting and in situ hybridization (ISH) in aortic tissues from 33 autopsies. In 23 cases involving persons who ranged from 23 weeks to 75 years of age at the time of death, the tissue was histologically non-atherosclerotic. Of these 23, aortic tissues tested positive for HSV-1 in 13%, for EBV in 13% and for CMV in 4%. In the other 10 cases involving persons who were 53-75 years old at death, atherosclerotic aortic tissue tested positive for HSV-1 in 80%, for EBV in 80% and for CMV in 40%. Neither double nor triple infections occurred in the non-atherosclerotic group, whereas six of 10 were positive for two viruses, and two of 10 were positive for three viruses in the atherosclerotic group. By in situ hybridization, the viruses were localized in cells morphologically consistent with endothelial cells and smooth muscle cells. We detected HSV-1, EBV and CMV DNA in cells in the upper portion of the non-atherosclerotic aortic wall, whereas viral DNA was detected more extensively in atherosclerotic lesions than in non-atherosclerotic tissue. We also are the first to show the existence of EBV DNA in the human aortic wall. In conclusion, we suggest that the high incidence and kinds of herpesviruses are related to the high incidence of atherosclerosis.

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.

Endogenous heparin activity deficiency: the 'missing link' in atherogenesis?

This paper reviews published studies since 1995 dealing with many atherogenic mechanisms where exogenous heparin was beneficial. In these areas endogenous heparin deficiency is likely to be harmful. Mechanisms included inflammatory factors, lower endogenous plasma heparin levels, lipoprotein lipase, chemokines, APOE e4, lipoprotein(a), among others. Demonstrated reduction of heparan sulfate proteoglycans (HSPG) and of endogenous plasma heparin was reviewed.

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.

Experimental infection with bovine herpesvirus-4 enhances atherosclerotic process in rabbits

An association of herpesvirus and atherosclerosis has been suggested by seroepidemiologic studies and detection of the virus in arterial tissues. To facilitate the studies of the pathogenic role of herpesvirus in atherosclerosis, we established a rabbit model of atherosclerosis with bovine herpesvirus type-4 (BHV-4). Forty New Zealand White rabbits were randomly divided into six groups. Groups 1, 2, and 3 were inoculated iv with BHV-4 and control Groups 4, 5, and 6 with normal saline. Groups 1 and 4 were fed a regular diet throughout the experiment; Groups 2 and 5 were fed a diet supplemented with 2% cholesterol for 3 weeks starting at 3 weeks postinoculation; and Groups 3 and 6 with a diet supplemented with 2% cholesterol for 6 weeks starting at 3 days postinoculation. Extensive atherosclerotic lesions in Groups 2, 3, and 6, and small lesions in two rabbits in Group 1 were observed, but no obvious lesions were observed in Groups 4 and 5. BHV-4 DNA was demonstrated by polymerase chain reaction and liquid hybridization in aortic sections, various tissue samples, and peripheral blood mononuclear cells of all infected rabbits. Our studies demonstrated that BHV-4 can accelerate the atherosclerotic process in rabbits, and that experimental infection of rabbits with BHV-4 can be a useful atherosclerosis model.

Moderate alcohol consumption: the gentle face of Janus

OBJECTIVES

The regular consumption of alcohol in moderate amounts (defined in North America as up to 2 drinks per day for men and 1 drink per day for females) has been recognized in the last decade as a negative risk factor for atherosclerosis and its clinical sequelae: coronary heart disease (CHD), ischemic stroke, and peripheral vascular disease. Mortality and morbidity attributable to CHD are 40-60% lower in moderate drinkers than among abstainers. Among the mechanisms accounting for these reductions, increased circulating concentrations of HDL-cholesterol and inhibition of blood coagulation appear to be paramount. Additional benefits are, in certain beverages, conferred by the presence of constituents other than alcohol (e.g., flavonoids and hydroxystilbenes), which prevent oxidative damage, free radical formation, and elements of the inflammatory response.

CONCLUSIONS

A number of other diseases appear to be beneficially modulated by moderate alcohol consumption based on epidemiologic surveys and, in some instances, experimental evidence. These include duodenal ulcer, gallstones, enteric infections, rheumatoid arthritis, osteoporosis, and diabetes mellitus (type II). Compared with abstainers, moderate drinkers exhibit improved mental status characterized by decreased stress and depression, lower absenteeism from work, and decreased incidence of dementia (including Alzheimer's disease). Although limits of safe drinking have been conservatively defined, it is regrettable that political considerations are hampering the clinical application of this knowledge and its dissemination to the lay public.

The contribution of inducible nitric oxide and cytomegalovirus to the stability of complex carotid plaque

BACKGROUND

Although the association between inflammation and atherosclerosis is well established, the biologic events that trigger the local inflammatory response within plaque are not fully understood. Cytotoxic free radicals and infectious agents, both of which are associated with an inflammatory response, have previously been implicated in the initiation and progression of atherosclerosis. In this study, we analyzed carotid plaque for evidence of oxidative vascular injury by determining the presence and distribution of inducible nitric oxide synthase (iNOS) expression and nitrotyrosine formation and for evidence of infection with cytomegalovirus.

METHODS

Carotid plaque from 51 patients who underwent endarterectomy for either primary (n = 37) or recurrent (n = 14) stenosis were examined histologically (hematoxylin-eosin staining and Masson's trichrome staining) and with immunohistochemistry with specific antibodies to alpha-smooth muscle actin, macrophages (CD68), T-lymphocytes (CD3), and T-cell activation (human leukocyte antigen-DR). Twenty-eight specimens from patients with primary (n = 15) and recurrent (n = 13) stenosis were examined for the presence of iNOS and nitrotyrosine with immunohistochemistry and in situ hybridization (iNOS). Twenty-three additional specimens (22 primary, and 1 recurrent) were analyzed with antibodies to p53, cytomegalovirus, and the polymerase chain reaction (cytomegalovirus, n = 8).

RESULTS

Primary atherosclerotic lesions were either complex heterogenous cellular plaques (n = 29) or relatively acellular fibrous plaques (n = 8). Ten of 14 recurrent plaques were either complex or fibrous lesions, and the remaining four were typical of myointimal thickening. CD68-positive staining cells were detected in all specimens regardless of their structural morphology. CD3-positive cells were interspersed between macrophages in all heterogeneous cellular plaques and only infrequently noted in fibrous plaques. iNOS and nitrotyrosine immunoreactivity were detected in macrophages and smooth muscle cells in all complex and fibrous plaques and in two of four myointimal plaques. The presence of iNOS and nitrotyrosine in plaque correlated with the existence of symptoms in 80% of primary and 62% of recurrent lesions. Cytomegalovirus was detected in only two of 23 carotid specimens (9%).

CONCLUSION

The association between ischemic cerebrovascular symptoms and iNOS and nitrotyrosine immunoreactivity in complex primary and recurrent carotid plaque and the infrequent occurrence of cytomegalovirus in primary carotid lesions suggests that ongoing free radical oxidative damage rather than viral infection may contribute to plaque instability in patients with complex and fibrous carotid plaques.