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

The role of infection in the pathogenesis of cardiovascular disease

Atherosclerosis is a complex, multifactorial disease. Recently, research has intensified to identify the role of various infections in the pathogenesis of atherosclerosis. Specific agents have been proposed as direct initiators or accelerators of atherosclerosis, while other infectious agents have been proposed as accelerators of atherosclerosis through nonspecific stimulation of the inflammatory cascade. Recently, the total pathogen burden concept has suggested that while each specific infection contributes only slightly to the pathogenesis of atherosclerosis, the cumulative effects of infectious agents contribute greatly. Several randomized trials evaluating antibiotic therapy in the prevention of cardiovascular events have now been completed, although results have been conflicting. This manuscript summarizes current understanding of the role of infectious agents as a trigger of inflammation, as a contributor to atherosclerosis, and the potential role of antibiotic therapy in the treatment of atherosclerosis.

[Late T-lymphocyte and monocyte activation in coronary restenosis. Evidence for a persistent inflammatory/immune mechanism?]

AIMS

This study was made to determine if restenosis after percutaneous coronary angioplasty is associated with acute or chronic inflammatory/immunologic activity, and explored possible relationships with latent infection.

PATIENTS AND METHOD

Forty-six consecutive patients underwent elective PTCA and 6 months of angiographic follow-up. Peripheral venous blood samples were obtained at baseline, 24-48 h, and 4-6 months post-intervention. Flow-cytometric methods were used to measure early and late circulating leukocyte activation status. Il-6 and TNF-alpha cytokines, and Il-2 soluble receptor concentrations were determined in all plasma samples. Chlamydia pneumoniae and Cytomegalovirus antibody assays were performed to detect infectious disease.

RESULTS

Angiographic coronary stenosis developed in 27 out of 46 patients. At 6 months of follow-up, these patients showed a significant increase in circulating cytotoxic T-lymphocytes CD3+/CD56+ (18.8 7.1 vs 6.12 2.7%; p = 0.005) and activated monocytes (CD11b: 1,383 624 vs 990 484 MFI, p = 0.025; CD64: 76.0 28.7 vs 56.7 21.8 MFI; p = 0.014), with no apparent relation to increased cytokines or latent infectious disease.

CONCLUSIONS

Restenosis appears to be associated to inflammatory and immunological activity that persists 6 months after coronary intervention. No relationship was found with the infections studied. The presence of inflammatory activity 4-6 months after PTCA suggess that pharmacological therapeutic interventions to prevent restenosis should be maintained for months.

Targeting the cell cycle machinery for the treatment of cardiovascular disease

Cardiovascular disease represents a major clinical problem affecting a significant proportion of the world's population and remains the main cause of death in the UK. The majority of therapies currently available for the treatment of cardiovascular disease do not cure the problem but merely treat the symptoms. Furthermore, many cardioactive drugs have serious side effects and have narrow therapeutic windows that can limit their usefulness in the clinic. Thus, the development of more selective and highly effective therapeutic strategies that could cure specific cardiovascular diseases would be of enormous benefit both to the patient and to those countries where healthcare systems are responsible for an increasing number of patients. In this review, we discuss the evidence that suggests that targeting the cell cycle machinery in cardiovascular cells provides a novel strategy for the treatment of certain cardiovascular diseases. Those cell cycle molecules that are important for regulating terminal differentiation of cardiac myocytes and whether they can be targeted to reinitiate cell division and myocardial repair will be discussed as will the molecules that control vascular smooth muscle cell (VSMC) and endothelial cell proliferation in disorders such as atherosclerosis and restenosis. The main approaches currently used to target the cell cycle machinery in cardiovascular disease have employed gene therapy techniques. We will overview the different methods and routes of gene delivery to the cardiovascular system and describe possible future drug therapies for these disorders. Although the majority of the published data comes from animal studies, there are several instances where potential therapies have moved into the clinical setting with promising results.

Human cytomegalovirus infection in human renal arteries in vitro

Studies with animal cytomegaloviruses, epidemiological data from humans as well as in vitro studies suggest the involvement of the human cytomegalovirus (HCMV) in the development of atherosclerosis. Cell culture systems are insufficient for examination of the entire pathogenetic process and a satisfactory animal model for HCMV is not available. An organ culture model was established for HCMV infection of human renal arteries in vitro. After infection with three representative HCMV strains, infectious virus was recovered from supernatants until 144 days post-infection with a peak around day 30 due to a long-lasting productive HCMV infection in still vital cells. Differences in cell tropism and kinetics of infection were identified between the HCMV strains. Specifically, differences in infecting endothelial cells and virus penetration into the lamina media were observed. In infected artery segments, but also in some non-infected arteries from seropositive donors, HCMV DNA could be localized by in situ PCR. Nevertheless, HCMV early antigen was detected by immunohistochemistry exclusively in artery segments infected in vitro. The new organ culture model will permit the study of functional and molecular consequences of HCMV infection in a more physiological micro-environment.

C-reactive protein, Helicobacter pylori, Chlamydia pneumoniae, cytomegalovirus and risk for myocardial infarction

PURPOSE

C-reactive protein (CRP), Chlamydia pneumonia, Helicobacter pylori, and cytomegalovirus (CMV) have each been associated with atherosclerosis. We assessed how infection and CRP related to risk for subsequent myocardial infarction (MI).

METHODS

Using a nested case-control design, we assessed how these factors independently and jointly affected risk for myocardial infarction (MI). Cases of first MI (N = 121) were identified from among participants in a multiphasic health check-up cohort. Controls without MI (N = 204) were matched to cases by gender, age, race, and date of serum collection. Sera collected at enrollment were tested for antibodies to infection and for CRP.

RESULTS

In multivariate analysis (mean follow-up of 5.1 years), CRP was associated with MI only in subjects older than 51 years (p = 0.004). Although H. pylori infection increased risk for MI, this association was modest (OR = 1.90, 95% CI = 0.97-3.71) and was not evident in non-smokers or when adjusted for education. No association between C. pneumoniae or cytomegalovirus and MI was observed, nor was the association between CRP and MI explained by these infections.

CONCLUSIONS

Elevated CRP is a risk factor for subsequent MI in older individuals. The relationship between Hp and MI may be due to confounding or co-linearity with socioeconomic status.

Viral and bacterial DNA in carotid atherosclerotic lesions

Atherosclerosis is a major health problem in industrialised countries. Several studies have suggested an association exists between certain microorganisms and the development of atherosclerosis. The aim of the study presented here was to assess the presence of viral or bacterial DNA in carotid atherosclerotic lesions. Nucleic acids were extracted from 18 carotid atherosclerotic lesions that had been collected surgically. Polymerase chain reaction was used to screen for specific genomic DNA from Chlamydia pneumoniae, cytomegalovirus and herpes simplex virus types 1 and 2. An original approach, based on the amplification by PCR of conserved bacterial 16S rDNA nucleotide sequences was also used to detect any bacterial species. The amplification product was identified by sequencing. Chlamydia pneumoniae, cytomegalovirus and herpes simplex 2 DNA were not detected in any of the samples. Herpes simplex 1 DNA was detected in 3 of the 18 samples. Genes encoding bacterial 16S rRNA were amplified and sequenced in eight atherosclerotic lesions. DNA sequences were identified by comparison with sequences registered in the GenBank database. These eight carotid atherosclerotic lesions were shown to contain several bacterial species belonging to human flora or the environment. The exact role of these microorganisms in the genesis or development of the atherosclerotic lesions remains unclear, but they may increase the inflammatory process or be an epiphenomenon.

Effect of p53 deficiency on external vascular cuff-induced neointima formation

The p53 tumor suppressor gene may act as an inhibitor of vascular neointima formation in response to injury and in the present study the effects of p53 deficiency on external vascular cuff-induced neointima formation were evaluated. Vascular neointima formation was induced by an external vascular cuff; a polyethylene tube placed around a 2 mm segment of the left femoral artery ensheathed the adventitia, but avoided direct intraluminal injury. Two weeks after cuff placement, the cuff-sheathed and contralateral control arteries without cuff from wild-type (n=10) and p53 deficient (n=8) mice were harvested and analyzed by quantitative morphometry. The areas of the lumen, intima, and media were measured in 10 cross-sections from one edge to the other of the cuffed portion, and in the corresponding 2-mm segment of the contralateral control artery. The volume ratio of the intima to media (I/M) was calculated. The contralateral control arteries without a cuff did not have intima in either wild-type or p53 deficient mice. In the cuff-sheathed arteries, neointima formation of p53 deficient mice with an I/M of 93% was significantly greater than that of wild-type mice with an I/M of 50% (P=0.001). The absence of p53 is associated with increased neointima formation in response to cuff injury.

Multiple infections and subsequent cardiovascular events in the Heart Outcomes Prevention Evaluation (HOPE) Study

BACKGROUND

Limited prospective epidemiological data are available on the relation between exposure to Chlamydia pneumoniae, Helicobacter pylori, cytomegalovirus (CMV), and hepatitis A virus (HAV), individually or as a total pathogen score, and human cardiovascular (CV) disease.

METHODS AND RESULTS

We analyzed enrollment sera from 3168 Canadian patients in the Heart Outcomes Prevention Evaluation (HOPE) study for antibodies to C pneumoniae, H pylori, CMV, and HAV and measured the relation between serostatus and 494 adjudicated trial outcomes of myocardial infarction, stroke, or CV death over 4.5 years of follow-up. CV events were associated with CMV serostatus (covariate-adjusted hazard ratio [HR], 1.24; 95% CI, 1.01, 1.53). Neither C pneumoniae IgG (adjusted HR, 0.87; 95% CI, 0.68, 1.10), C pneumonia IgA (adjusted HR, 1.10; 95% CI, 0.90, 1.34), H pylori IgG (HR, 0.99; 95% CI, 0.82, 1.19), nor HAV IgG (HR, 1.01; 95% CI, 0.83, 1.24) predicted CV events. Total pathogen score was associated with CV events (adjusted HR for 4 versus 1 or 0=1.41; 95% CI, 1.02, 1.96).

CONCLUSIONS

Exposure to CMV but not to C pneumoniae, H pylori, or HAV was associated with a slight excess risk of subsequent myocardial infarction, stroke, or CV death in HOPE study patients, and total pathogen score based on these infections predicted a small increased hazard of CV events.

Statin therapy interacts with cytomegalovirus seropositivity and high C-reactive protein in reducing mortality among patients with angiographically significant coronary disease

BACKGROUND

Seropositivity to cytomegalovirus (CMV) and elevated C-reactive protein (CRP) may jointly predict increased mortality rates in patients with coronary artery disease (CAD). Therapy with statins reduces lipid levels but may also have other beneficial (eg, antiinflammatory) effects. This study prospectively evaluated the effect of statins on CMV-and CRP-associated death among patients with significant, angiographically defined CAD.

METHODS AND RESULTS

We monitored 2315 patients with angiographically significant CAD (stenosis > or =70%) for an average of 2.4 years (maximum, 5.8 years). Anti-CMV IgG antibody levels and CRP concentrations were measured at baseline, and statin prescription was recorded. As previously reported, mortality rate was higher for CMV seropositivity (+) with high CRP (hazard ratio [HR], 2.0) and lower for statins (HR, 0.50). Compared with CMV(-)/low CRP (mortality rate, 5% with statin versus 4% without statin), the protective effect of statin therapy was markedly greater for CMV(+)/low CRP (mortality rate, 2% versus 7%; HR, 0.44; 95% CI, 0.16 to 1.3), CMV negative (-)/high CRP (mortality rate, 1% versus 8%; HR, 0.16), and CMV(+)/high CRP (mortality rate, 6% versus 17%; HR, 0.42; 95% CI, 0.25 to 0.70). After adjustment, interactions were found for statin therapy with CMV(+)/low CRP (P for interaction=0.065), CMV(-)/high CRP (P for interaction=0.051), and CMV(+)/high CRP (P for interaction=0.024).

CONCLUSIONS

The survival benefit of statins interacted with CMV seropositivity and high CRP to significantly reduce mortality rates among patients with CAD. This finding supports the hypothesis that statins have beneficial, "lipid-independent," antiinflammatory effects. The mechanism of statin benefit associated with CMV seropositivity remains to be determined.

Synergistic induction of intercellular adhesion molecule-1 by the human cytomegalovirus transactivators IE2p86 and pp71 is mediated via an Sp1-binding site

Human cytomegalovirus (HCMV) infection of transplant recipients is frequently associated with allograft vasculopathy and rejection. One potential mechanism is vascular injury from HCMV-triggered, immunologically mediated processes. HCMV infection has been shown to increase the expression of intercellular adhesion molecule-1 (ICAM-1). The objective of this study was to determine the molecular basis of HCMV-enhanced ICAM-1 gene expression. Transient transfection experiments identified the IE2p86 protein as a potent activator of the ICAM-1 promoter. The tegument protein pp71 showed a strong synergistic effect on IE2p86-mediated ICAM-1 promoter activation. Mutagenesis experiments defined a DNA element from -110 to -42 relative to the transcription start site as responsive for IE2p86. Further point mutations within this DNA element identified an Sp1-binding site that was essential for strong synergistic activation by IE2p86 and pp71. To confirm the activation of ICAM-1 gene expression, human fibroblasts (HFF) as well as endothelial cells (HUVEC) were infected with recombinant IE2p86- and pp71-expressing baculoviruses, respectively. In FACS analysis, a synergistic induction of ICAM-1 was detectable when cells were co-infected with the two recombinant baculoviruses. These findings clearly demonstrate that IE2p86 and pp71 are crucial regulatory factors for HCMV-induced ICAM-1 upregulation.

T cells of atomic bomb survivors respond poorly to stimulation by Staphylococcus aureus toxins in vitro: does this stem from their peripheral lymphocyte populations having a diminished naïve CD4 T-cell content?

We found previously that the peripheral CD4 T-cell populations of heavily exposed A-bomb survivors contained fewer naïve T cells than we detected in the corresponding unexposed controls. To determine whether this demonstrable impairment of the CD4 T-cell immunity of A-bomb survivors was likely to affect the responsiveness of their immune systems to infection by common pathogens, we tested the T cells of 723 survivors for their ability to proliferate in vitro after a challenge by each of the Staphylococcus aureus toxins SEB, SEC-2, SEC-3, SEE and TSST-1. The results presented here reveal that the proliferative responses of T cells of A-bomb survivors became progressively weaker as the radiation dose increased and did so in a manner that correlated well with the decreasing CD45RA-positive (naïve) [but not CD45RA-negative (memory)] CD4 T-cell percentages that we found in their peripheral blood lymphocyte (PBL) populations. We also noted that the T cells of survivors with a history of myocardial infarction tended to respond poorly to several (or even all) of the S. aureus toxins, and that these same individuals had proportionally fewer CD45RA-positive (naïve) CD4 T cells in their PBL populations than we detected in survivors with no myocardial infarction in their history. Taken together, these results clearly indicate that A-bomb irradiation led to an impairment of the ability of exposed individuals to maintain their naïve T-cell pools. This may explain why A-bomb survivors tend to respond poorly to toxins encoded by the common pathogenic bacterium S. aureus.

Upregulation of CD40 expression on endothelial cells infected with human cytomegalovirus

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

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

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

Greater pathogen burden but not elevated C-reactive protein increases the risk of clinical restenosis after percutaneous coronary intervention

BACKGROUND

Restenosis after percutaneous coronary intervention (PCI) constitutes a serious complication in the treatment of cardiovascular disease, but known risk factors do not fully account for the observed restenosis risk. Preliminary studies of infection or inflammation in restenosis report varied results. We tested whether C-reactive protein (CRP) or pathogen burden (seropositivity to 0, 1, 2, or 3 pathogens, of Chlamydia pneumoniae [Cpn], cytomegalovirus [CMV], or Helicobacter pylori [Hpy]) predict clinical restenosis after percutaneous coronary intervention (PCI).

METHODS

Blood samples were collected from 415 patients undergoing PCI, and levels of plasma CRP and antibodies to Cpn, CMV, and Hpy were measured. The patient's medical history, demographics, and procedural data were recorded. Patient end points were determined for as long as 6 months as a means of evaluating the incidence of clinical restenosis and major adverse cardiac events.

RESULTS

The average patient age was 62 years, and 80% of patients were male. Fifty-eight patients (14%) experienced clinical restenosis, whereas 17 patients (4%) died or had an acute myocardial infarction. After adjusting for 19 possible predictors, we found the pathogen burden (P-trend =.04, adjusted odds ratio [OR] 1.5 per number of pathogens) and minimum luminal diameter (P =.003, OR 1.8 per mm decrease) to be significant predictors of clinical restenosis. Male sex was a nonsignificant predictor of restenosis (P =.06, OR 2.2), but CRP was not significant after adjustment (P-trend =.10, OR 0.73 per tertile).

CONCLUSION

Pathogen burden was associated with clinical coronary restenosis, an association that deserves further exploration and evaluation. CRP, a marker of inflammation, was not associated with an increased risk of restenosis.

Mapping the viral genetic determinants of endothelial cell tropism in human cytomegalovirus

Endothelial cells are natural sites of infection for human cytomegalovirus (HCMV) and are increasingly recognized to play an important role in viral dissemination, as well as provide access to underlying tissues and organs. However, the viral factors required for endothelial cell tropism are poorly defined. The goals of the project were to develop a system to study endothelial cell infectivity factors in HCMV, and map the viral genetic determinants required for these tropism functions. HCMV infection of primary aortic endothelial cells (AEC) was studied as a means to evaluate aspects relevant to both pathogenesis of acute infection and chronic vascular diseases. A series of HCMV virus strains was screened for endothelial tropism by comparing replication efficiencies on AEC. A virus strain that was efficient for replication (AD169varATCC), and a virus strain that was restricted for replication (Toledo), were selected for further analysis and characterization. We present evidence for a novel HCMV endothelial tropism factor that functioned following viral internalization across the endothelial cell plasma membrane and prior to nuclear entry. This factor may be involved in intracellular transport of the virion capsid-tegument structure. Complementation approaches using pseudotype virus infection of AEC demonstrated that the tropism defective strain could be rescued in trans. This supported the existence of a viral encoded tropism determinant. Using a gain of function approach, endothelial cell infectivity of the non-tropic HCMV strain Toledo was rescued with AD169 cosmid sequences. Tropism-specific viral genetic determinant(s) may be mapped to a region of the AD169 viral DNA encompassing UL48-56.

Genetic control of innate immune responses against cytomegalovirus: MCMV meets its match

Cytomegalovirus (CMV) is a widespread pathogen that is responsible for severe disease in immunocompromised individuals and probably, associated with vascular disease in the general population. There is increasing evidence that cells of the innate immune system play a key role in controlling this important pathogen. This is particularly evident in the experimental murine CMV (MCMV) model of infection which has revealed an important role for natural killer (NK) cells in controlling early viral replication after infection with MCMV. In this model, different strains of inbred mice exhibit striking differences in their level of susceptibility to MCMV infection. Genetic studies, performed almost 10 years ago, revealed that this pattern of susceptibility/resistance can be attributed to a single genetic locus termed Cmv1 and recently several groups that have been working on the mapping and identification of Cmv1 have met with success. Interestingly, Cmv1 is allelic to a member of the Ly49 gene family, which encode activating or inhibitory transmembrane receptors present on the surface of NK cells. All Ly49 receptors characterized to date interact with MHC class I molecules on potential target cells, resulting in the accumulation of signals to the NK to either 'kill' or 'ignore' the cell based upon the repertoire of MHC class I molecules expressed. The identification of Cmv1 as Ly49H, a stimulatory member of the Ly49 family, adds an interesting twist to the Ly49 story. Although the ligand of Ly49H is not yet known, there is already compelling evidence that the ligand is upregulated on virally infected cells, resulting in specific activation of Ly49H-expressing NK cells. This review provides an historical perspective of the MCMV infection model from its inception to the discovery of the gene responsible for the phenotype and provides a basis for further experiments aimed at understanding the role of NK cells, in general, and Ly49H, in particular, in mediating resistance to cytomegalovirus.

Serological examination of human herpesvirus 6 and 7 in patients with coronary artery disease

Fifty-three (96%) of 55 patients with coronary artery stenosis were positive for serum anti-HHV-6 IgG, and 50 (91%) of these patients had anti-HHV-7 IgG. The number of cases sero-positive for HHV-6 and -7 in the 54 age matched control volunteers was 52 (96%) and 53 (98%), respectively. No statistical difference in the sero-prevalence of the viruses existed between the patients and the control group. The mean geometric titer (log10) of anti-HHV-6 IgG in both the patients and controls were the same (1.4) (P = 0.845), whereas anti-HHV-7 titers were 1.4 and 1.5, respectively (P = 0.161). Ten (18%) of the 55 patients had anti-HHV-6 IgM; eight (15%) of the 54 control volunteers were also positive (P = 0.636). Three (5%) of the 55 patients had anti-HHV-7 IgM, whereas 3 (6%) of the 54 control volunteers had detectable serum antibody (P = 0.691). Forty-seven of the 55 patients were examined by follow-up angiographic evaluation to clarify the association between viral infection and restenosis following balloon angioplasty. Fifteen of these patients developed restenosis, as determined by angiography. The mean geometric titer (log10) of anti-HHV-6 IgG were 1.3 and 1.4 in patients with restenosis and those without restenosis, respectively (P = 0.724). The mean geometric titer (log10) of anti-HHV-7 IgG in patients with restenosis was not significantly higher (1.5) than in patients without restenosis (1.3) (P = 0.099). Three (20%) of the 15 patients affected by restenosis had anti-HHV-6 IgM; five (16%) of the 32 control patients also had the antibody (P = 0.965). One (7%) of the 15 patients with restenosis and 2 (6%) of the 32 patients without restenosis had anti-HHV-7 IgM (P = 0.558). The present study demonstrates that HHV-6 and -7 reactivation is not associated with the establishment of coronary artery stenosis and restenosis following balloon angioplasty.

[Atherosclerosis, multiple sclerosis, and Alzheimer's disease: what role for Herpesviridae?]

Herpesviridae are ubiquitous, and are commonly involved in well identified diseases as genital herpes, chickenpox and herpes zoster, infectious mononucleosis, exanthem subitum... They are responsible for latent and chronic infections after primary infection. Atherosclerosis, multiple sclerosis, Alzheimer's disease are diseases which are very different, and for which pathogenesis remains unknown. Several authors have hypothesized that Herpesviridae could play a role in such diseases. The present paper reviews arguments not only in favour but also against such hypothesis. Any formal conclusion is impossible, and more extensive studies are warranted.

Predisposition to atherosclerosis by infections: role of endothelial dysfunction

BACKGROUND

Several microorganisms have been implicated in the pathogenesis of atherosclerosis. We hypothesized that infections may predispose to atherosclerosis by inflicting endothelial injury.

METHODS AND RESULTS

Of 375 patients undergoing coronary angiography, 218 had assessment of endothelial function using intracoronary acetylcholine (ACH) and of endothelium-independent function with sodium nitroprusside and adenosine. Immunoglobulin-G antibody titers to cytomegalovirus, Chlamydia pneumoniae, Helicobacter pylori, hepatitis A virus, and herpes simplex virus-1 were measured. Pathogen burden was defined as the number of positive antibodies. Although positive serology to individual pathogens tended to be associated with increased incidence of coronary arteriosclerosis (CAD), the pathogen burden correlated with the presence of CAD, even after adjustment for risk factors (OR 1.3; 95% CI, 1.05 to 1.6, P=0.018). Moreover, the severity of CAD was independently associated with the pathogen burden (P=0.001). Pathogen burden was an independent predictor of endothelial dysfunction, determined as the percent change in coronary vascular resistance in response to ACH (P=0.009) but not the responses to sodium nitroprusside or adenosine. Pathogen burden was also an independent determinant of endothelial function in the subgroup with angiographically normal coronary arteries.

CONCLUSIONS

The immunoglobulin-G antibody response to multiple pathogens (pathogen burden) is an independent risk factor for endothelial dysfunction and the presence and severity of CAD. Endothelial dysfunction provides the crucial link by which pathogens may contribute to atherogenesis.

Infection of cells with human cytomegalovirus during S phase results in a blockade to immediate-early gene expression that can be overcome by inhibition of the proteasome

Cells infected with human cytomegalovirus (HCMV) after commencing DNA replication do not initiate viral immediate-early (IE) gene expression and divide before arresting. To determine the nature of this blockade, we examined cells that were infected 24 h after release from G(0) using immunofluorescence, laser scanning cytometry, and fluorescence-activated cell sorting (FACS) analysis. Approximately 40 to 50% of the cells had 2N DNA content, became IE(+) in the first 12 h, and arrested. Most but not all of the cells with >2N DNA content did not express IE antigens until after mitosis. To define the small population of IE(+) cells that gradually accumulated within the S and G(2)/M compartments, cells were pulsed with bromodeoxyuridine (BrdU) just prior to S-phase infection and analyzed at 12 h postinfection for IE gene expression, BrdU positivity, and cell cycle position. Most of the BrdU(+) cells were IE(-) and had progressed into G(2)/M or back to G(1). The majority of the IE(+) cells in S and G(2)/M were BrdU(-). Only a few cells were IE(+) BrdU(+), and they resided in G(2)/M. Multipoint BrdU pulse-labeling revealed that, compared to cells actively synthesizing DNA at the beginning of the infection, a greater percentage of the cells that initiated DNA replication 4 h later could express IE antigens and proceed into S. Synchronization of the cells with aphidicolin also indicated that the blockade to the activation of IE gene expression was established in cells soon after initiation of DNA replication. It appears that a short-lived protein in S-phase cells may be required for IE gene expression, as it is partially restored by treatment with the proteasome inhibitor MG132.

Human cytomegalovirus immediate early proteins and cell growth control

It is widely accepted that small DNA tumor viruses, such as adenovirus, simian virus 40 and papillomavirus, push infected cells into S-phase to facilitate the replication of their genome. Until recently, it was believed that the large DNA viruses (i.e. herpesviruses) functioned very differently in this regard by inducing a G(1) arrest in infected cells as part of their replication process. However, studies over the last 6-8 years have uncovered striking parallels (and differences) between the functions of the major immediate early (IE) proteins of at least one herpesvirus, human cytomegalovirus (HCMV) and IE equivalents encoded by small DNA tumor viruses, such as adenovirus. Similarities between the HCMV major IE proteins and adenovirus IE proteins include targeting of members of the RB and p53 families and an ability of these viral factors to induce S-phase in quiescent cells. However, unlike the small DNA tumor virus proteins, individual HCMV IE proteins target different RB family members. HCMV also encodes several other IE gene products as well as virion tegument proteins that act early during infection to prevent an infected cell from replicating its host genome and from undergoing apoptosis. Here, we review the specifics of several HCMV IE proteins, two virion components, and their functions in relation to cell growth control.

Influenza vaccine pilot study in acute coronary syndromes and planned percutaneous coronary interventions: the FLU Vaccination Acute Coronary Syndromes (FLUVACS) Study

BACKGROUND

Recent reports have detected an increase in the number of patients with acute coronary syndromes during the flu season. In addition, the World Health Organization recommended vaccination against influenza infection for the Southern hemisphere in the winter of 2001. We evaluated the preventive impact of vaccination on subsequent ischemic events in myocardial infarction patients and in subjects undergoing planned percutaneous coronary angioplasty.

METHODS AND RESULTS

We included 200 myocardial infarction patients admitted in the first 72 hours and 101 planned angioplasty/stent (PCI) patients without unstable coronary artery disease, prior bypass surgery, angioplasty, or tissue necrosis, in a prospective, multicenter log during the winter season. Infarct patients received a standard therapy and were then randomly allocated in a single-blind manner to either a unique intramuscular influenza vaccination or a control group. Similarly, PCI patients were allocated to either vaccination or control groups. Combined end points (death, reinfarction, and rehospitalization for ischemia) were assessed at 6 months' follow-up. The first primary outcome, cardiovascular death, occurred in 2% of the patients in the vaccine group compared with 8% in the control group (relative risk with vaccine as compared with controls, 0.25; 95% CI 0.07 to 0.86; P=0.01). The triple composite end point occurred in 11% of the patients in the vaccine group compared with 23% in controls (P=0.009).

CONCLUSIONS

Influenza vaccination may reduce the risk of death and ischemic events in patients suffering from infarction and those recovering from angioplasty during flu season. This response could be related to a humoral immune response with positive consequences during flu seasons.

Has cytomegalovirus infection any role in the development of atherosclerosis?

An interesting aspect of infection with several infectious agents is the possible association with some diseases apparently not associated with infections. One of the most exciting examples of this is the association of cardiovascular diseases with infection involving several different infectious agents. Cytomegalovirus (CMV) is one of the chief candidates that have been studied. Several epidemiologic reports indicate a possible association of various forms of vascular disease with the presence and titer of viral antibodies. Other studies show the presence of virus, viral antigens or nucleic acid in atherosclerotic lesions. Studies in animal models and cell-culture studies present attractive mechanisms by which the virus may play a role in the etiology of these diseases. However, negative results have also been reported, and more research is needed before the final verdict on this exciting question is presented.

Viable human cytomegalovirus recombinant virus with an internal deletion of the IE2 86 gene affects late stages of viral replication

Using bacterial artificial chromosome (BAC) technology, we have constructed and characterized a human cytomegalovirus recombinant virus with a mutation in the exon specific for the major immediate-early region 2 (IE2) gene product. The resulting IE2 86-kDa protein (IE2 86) has an internal deletion of amino acids 136 to 290 and is fused at the carboxy terminus to enhanced green fluorescent protein (EGFP). The deletion also removes the promoter and initiator methionine for the p40 form of IE2 and initiator methionine for the p60 form of the protein, and therefore, these late gene products are not produced. The mutant virus IE2 86 Delta SX-EGFP is viable but exhibits altered growth characteristics in tissue culture compared with a full-length wild-type (wt) IE2 86-EGFP virus or a revertant virus. When cells are infected with the mutant virus at a low multiplicity of infection (MOI), there is a marked delay in the production of infectious virus. This is associated with slower cell-to-cell spread of the virus. By immunofluorescence and Western blot analyses, we show that the early steps in the replication of the mutant virus are comparable to those for the wt. Although there is significantly less IE2 protein in the cells infected with the mutant, there is only a modest lag in the initial accumulation of IE1 72 and viral early proteins, and viral DNA replication proceeds normally. The mutation also has only a small effect on the synthesis of the viral major capsid protein. The most notable molecular defect in the mutant virus infection is that the steady-state levels of the pp65 (UL83) and pp28 (UL99) matrix proteins are greatly reduced. In the case of UL83, but not UL99, there is also a corresponding decrease in the amount of mRNA present in cells infected with the mutant virus.

Inflammation in acute coronary syndromes

Extensive evidence supports a pathogenic role for both local and systemic inflammation in acute coronary syndromes. However, several important questions remain unanswered. Is the observed inflammatory process a precursor or a consequence of coronary plaque rupture? Is the inflammatory component of unstable coronary disease a potential therapeutic target? Finally, do infectious agents have a pathogenic role in coronary atherosclerosis and acute coronary syndromes?

Iron chelation and hydroxyl radical scavenging reduce the inflammatory response of endothelial cells after infection with Chlamydia pneumoniae or influenza A

BACKGROUND

Chronic low-grade inflammation is associated with increased risk of vascular diseases. The source of inflammation is unknown but may well be chronic and/or repetitive infections with microorganisms. Direct infection of endothelial cells (ECs) may also be a starting point for atherogenesis by initiating endothelial procoagulant activity, increased monocyte adherence and increased cytokine production. We hypothesized that iron-mediated intracellular hydroxyl radical formation after infection is a key event in triggering the production of interleukin-6 (IL-6) by ECs in vitro.

METHODS

Cultured ECs were incubated with Fe(II) and Fe(III) or infected with Chlamydia pneumoniae or influenza A/H1N1/Taiwan/1/81 for 48 and 24 h, respectively. To determine the role of iron and reactive oxygen species, cells were coincubated with the H2O2 scavenger N-acetyl-l-cysteine, with the iron chelator deferoxamine (DFO) or with the intracellular hydroxyl radical scavenger dimethylthiourea (DMTU). After the incubation periods, supernatants were harvested for IL-6 determination.

RESULTS

Incubating ECs with Fe(II) and Fe(III) resulted in increased IL-6 production. Similarly, infection with C. pneumoniae and influenza A also induced an IL-6 response. Coincubating ECs with DFO or DMTU blocked this response. Nuclear factor-kappaB activity was increased after infection and blocked by coincubation with DFO or DMTU.

CONCLUSION

Cultured ECs respond to infection and iron incubation with increased production of IL-6. Iron, the generation of intracellular hydroxyl radical and NF-kappaB activity are essential in cellular activation, suggesting that reactive oxygen species generated in the Haber-Weiss reaction are essential in invoking an immunological response to infection by ECs.

Chronic infections and atherosclerosis/thrombosis

An emerging pathophysiologic paradigm implicates chronic inflammation in the initiation, progression, and destabilization of atherosclerotic vascular disease. Various potential contributors to the inflammatory response in the vessel wall include atherogenic lipids, mechanical stress and injury, hypertension and angiotensin II, cigarette smoking, immune response to neoantigens, and chronic infections with viruses and or bacteria (Table 1). The potential link between chronic infection and atherosclerosis/thrombosis is under extensive investigation in several laboratories around the world. Although indirect evidence and experimental data tend to support this link, definitive proof is still lacking. If such a link is eventually proven to be causal in nature, it will provide a novel target for preventive and therapeutic strategies (anti-infective drugs, vaccines, etc.) against a common disease that is the leading killer of people in Western nations. Results of ongoing, large-scale clinical trials are eagerly awaited.

Clinical aspects and management of cytomegalovirus infection

The previous article discussed recent advances in understanding the biology of HCMV infection. Here we discuss current approaches to the clinical management of HCMV disease, and how understanding the biology of the virus may affect these.

Cytomegalovirus infection accelerates inflammation in vascular tissue overexpressing monocyte chemoattractant protein-1

Cardiovascular disease is the leading cause of mortality in the United States. Atherosclerosis is responsible for most of this pathology and is an inflammatory disease with multiple cytokines and adhesion molecules expressed during atherogenesis. Cytomegalovirus (CMV), monocytes, and monocyte chemoattractant protein-1 (MCP-1) have all been implicated in human atherogenesis. A transgenic mouse overexpressing MCP-1 in the myocardium and pulmonary arteries develops myocarditis and pulmonary vascular inflammation. We infected MCP-1 transgenic mice with a sublethal dose of murine cytomegalovirus (MCMV) to look for evidence of accelerated inflammation in vascular tissues overexpressing MCP-1 to determine if MCMV could interact with monocytes and MCP-1 in a manner similar to what may occur in atherogenesis. MCMV infection of MCP-1 transgenic mice caused ascites, myocarditis, and pulmonary artery inflammation, which was not present in mock-infected MCP-1 or MCMV-infected wild-type mice. Inflammatory infiltrates in these tissues consisted of macrophages and T lymphocytes similar to the infiltrates seen in atherosclerosis. Virus presence in inflamed tissues was demonstrated by infecting transgenic mice with MCMV recombinant virus containing the gene sequence for the enhanced green fluorescent protein (EGFP). Human CMV could be involved in atherogenesis in a similar manner by interacting with monocytes and MCP-1 specifically expressed in vascular walls.

Immune mechanisms in atherosclerosis

Atherosclerosis is an inflammatory disease. Its lesions are filled with immune cells that can orchestrate and effect inflammatory responses. In fact, the first lesions of atherosclerosis consist of macrophages and T cells. Unstable plaques are particularly rich in activated immune cells, suggesting that they may initiate plaque activation. We have seen a rapid increase in the understanding of the mechanisms that govern the recruitment, differentiation, and activation of immune cells in atherosclerosis. Experimental research has identified several candidate antigens, and there are encouraging data suggesting that immune modulation as well as immunization can reduce the progression of the disease. This review provides an overview of our current understanding of the role of immune mechanisms in atherosclerosis.

[Implication and mode of action of infectious agents in the formation of atheromatous plaques. Infection and atherosclerosis]

Different kinds of infectious agents seem to be implied in the atherosclerotic process. Indeed, some bacteria and viruses have been identified in atherosclerotic lesions: Chlamydia pneumoniae, Helicobacter pylori, Streptococcus sanguis, Porphyromonas gingivalis, herpes simplex viruses type 1 and 2, coxsakievirus B and hepatitis virus A. By their ability to induce antigenic and functional changes in the cells of the vascular wall (endothelial cells, smooth muscle cells, monocytes/macrophages, and fibroblasts) and to stimulate immune response as well as oxidative stress, it is more and more tempting to speculate that infectious agents probably play key roles in the initiation and in the formation of atherosclerotic plaques in certain patients.

Treatment of periodontitis by local administration of minocycline microspheres: a controlled trial

BACKGROUND

Periodontitis is an inflammatory condition of tooth-supporting tissues that is usually treated by mechanical removal of plaque and microorganisms that adhere to teeth. This treatment, known as scaling and root planing, is not optimally effective. Adjunctive therapy with locally delivered antimicrobials has resulted in improved clinical outcomes such as probing depth reduction. This article reports on the efficacy and safety of locally administered microencapsulated minocycline.

METHODS

Seven hundred forty-eight (748) patients with moderate to advanced periodontitis were enrolled in a multi-center trial and randomized to 1 of 3 treatment arms: 1) scaling and root planing (SRP) alone; 2) SRP plus vehicle; or 3) SRP plus minocycline microspheres. The primary outcome measure was probing depth reduction at 9 months. Clinical assessments were performed at baseline and 1, 3, 6, and 9 months.

RESULTS

Minocycline microspheres plus scaling and root planing provided substantially more probing depth reduction than either SRP alone or SRP plus vehicle. The difference reached statistical significance after the first month and was maintained throughout the trial. The improved outcome was observed to be independent of patients' smoking status, age, gender, or baseline disease level. There was no difference in the incidence of adverse effects among treatment groups.

CONCLUSIONS

Scaling and root planing plus minocycline microspheres is more effective than scaling and root planing alone in reducing probing depths in periodontitis patients.

Accelerated intimal thickening in carotid arteries of balloon-injured rats after immunization against heat shock protein 70

OBJECTIVES

The goal of this study was to test the hypothesis that induction of an immune response to heat shock protein (Hsp) 70 would increase intimal thickening in a rat carotid-injury model.

BACKGROUND

Restenosis resulting from intimal thickening poses a major limitation to the long-term success of coronary angioplasty. Several studies have proposed that infectious agents increase restenosis. Heat shock proteins are highly conserved structures, produced by all cells in response to nonspecific forms of stress. Infectious agents are known to contain Hsp70, which is markedly immunogenic and can elicit a strong immune response.

METHODS

To investigate whether Hsp70 immunity can affect neointimal thickening, we immunized rats with either Hsp70 (n = 11), bovine serum albumin ([BSA] n = 9) or with a control adjuvant (n = 10). Three weeks later, rats were boosted using the same regimen to achieve a sustained immune response to Hsp70 after which carotid injury was applied to all animals.

RESULTS

Arterial injury was associated with upregulation of Hsp70, 3, 7 and 14 days after induction of the injury as evidenced by Western blotting and immunohistochemistry. Intimal area and intimal/medial ratio was significantly increased in Hsp70-immunized rats in comparison with BSA or control-injected rats.

CONCLUSIONS

Our results imply that upregulation of Hsp70 in balloon-injured arteries can serve as a target for anti-Hsp70 immune response, thereby facilitating enhanced intimal thickening. These observations may provide a possible mechanism that explains the accelerated intimal thickening that has been associated with the occurrence of infectious pathogens.

Cytomegalovirus disease is not a major risk factor for ischemic heart disease after renal transplantation

BACKGROUND

It has been suggested that cytomegalovirus infection increases the risk of ischemic heart disease. Both cytomegalovirus and ischemic heart disease are common after renal transplantation, suggesting a possible causal association in this population.

METHODS AND PATIENTS

We studied 1004 consecutive renal transplants with no prior history of ischemic heart disease and grafts that functioned at least 12 months. We performed univariate and multivariate analyses to examine the effect of cytomegalovirus disease and other risk factors (measured during the first posttransplant year) on the development of primary ischemic heart disease events after the first posttransplant year.

RESULTS

More than 1 year after transplantation, 116 patients (11.6%) experienced their first ischemic event (75 myocardial infarction, 12 percutaneous angioplasty, 18 bypass grafting, and 11 deaths). Patients with ischemic heart disease were more likely to have known risk factors (age, diabetes, smoking, hypercholesterolemia, systolic blood pressure, low serum albumin, and acute rejections). However, the incidence of cytomegalovirus disease was not different for those with or without ischemic heart disease (36.2% vs. 31.1%). Moreover, a similar proportion of those with and without ischemic heart disease (19.8% vs. 15.5%) had a rise in cytomegalovirus antibodies during follow-up. By multivariate analysis, risk factors for ischemic heart disease (P<0.05) were age, diabetes, smoking, low serum albumin, and two or more acute rejections during the first year. Cytomegalovirus disease was not associated with ischemic heart disease events: unadjusted relative risk=1.14 (95% confidence interval 0.78-1.67, P=0.485). After adjusting for multiple risk factors, the relative risk was 0.91 (0.60-1.37, P=0.657).

CONCLUSION

These data suggest that cytomegalovirus disease is not a significant risk factor for the development of primary ischemic heart disease after renal transplantation.

A novel nonnucleoside inhibitor specifically targets cytomegalovirus DNA maturation via the UL89 and UL56 gene products

3-Hydroxy-2,2-dimethyl-N-[4([[5-(dimethylamino)-1-naphthyl]sulfonyl]amino)-phenyl]propanamide (BAY 38-4766) is a novel selective nonnucleoside inhibitor of cytomegalovirus (CMV) replication with an excellent safety profile. This compound and structural analogues inhibit neither viral DNA synthesis nor viral transcription and translation. Accumulation of dense bodies and noninfectious enveloped particles coincides with inhibition of both concatemer processing and functional cleavage at intergenomic transitions, pointing to interference with viral DNA maturation and packaging of monomeric genome lengths. Resistant virus populations, including a murine CMV (MCMV) isolate with 566-fold-decreased drug sensitivity, were selected in vitro. Sequencing of the six open reading frames (ORFs) known to be essentially involved in viral DNA cleavage and packaging identified mutations in ORFs UL56, UL89, and UL104. Construction of MCMV recombinants expressing different combinations of murine homologues of mutant UL56, UL89, and UL104 and analysis of drug susceptibilities clearly demonstrated that mutant ORFs UL89 exon II (M360I) and M56 (P202A I208N) individually confer resistance to BAY 38-4766. A combination of both mutant proteins exhibited a strong synergistic effect on resistance, reconstituting the high-resistance phenotype of the in vitro mutant. These findings are consistent with genetic mapping of resistance to TCRB (2,5,6-trichloro-1-beta-D-ribofuranosyl benzimidazole) (P. M. Krosky et al., J. Virol. 72:4721-4728, 1998) and provide further indirect evidence that proteins encoded by UL89 and UL56 function as two subunits of the CMV terminase. While these studies also suggest that the molecular mechanism of BAY 38-4766 is distinct from that of benzimidazole ribonucleosides, they also offer an explanation for the excellent specificity and tolerability of BAY 38-4766, since mammalian DNA does not undergo comparable maturation steps.

Do pathogens accelerate atherosclerosis?

Infection with the pathogens human cytomegalovirus (HCMV) or Chlamydia pneumonia (CP) is linked to the development of vascular disease, including atherosclerosis. The role of pathogens in vasculopathies has been controversial. However, animal models have demonstrated a direct link between infection with CP and herpesviruses and the development of vascular disease. Clinical studies have shown a direct association of HCMV and CP with the acceleration of vascular disease. This article will review the evidence supporting the role for CP and HCMV in the development of vascular disease and will suggest a potential mechanism for HCMV acceleration of the disease process. Vascular diseases are the result of either mechanical or immune-related injury followed by inflammation and subsequent smooth muscle cell (SMC) proliferation and/or migration from the vessel media to the intima, which culminates in vessel narrowing. A number of in vitro and in vivo models have provided potential mechanisms involved in pathogen-mediated vascular disease. Recently, we have demonstrated that HCMV infection of arterial but not venous SMC results in significant cellular migration in vitro. Migration was dependent on expression of the HCMV-encoded chemokine receptors, US28, and the presence of the chemokines, RANTES or MCP-1. Migration involved chemotaxis and provided the first evidence that viruses may induce migration of SMC toward sites of chemokine production through the expression of a virally encoded chemokine receptor in infected SMC. Because SMC migration into the neointimal space is the hallmark of vascular disease, these observations provide a molecular link between HCMV and the development of vascular disease.

Previous cytomegalovirus infection and restenosis after coronary stent placement

BACKGROUND

Reactivated cytomegalovirus may promote neointima formation after percutaneous coronary interventions by facilitating cell cycle progression through inhibition of the eukariotic tumor suppressor protein p53. This prospective study sought to investigate the effect of previous cytomegalovirus infection on restenosis after coronary stenting.

METHODS AND RESULTS

In 551 consecutive patients with successful stent placement, we determined cytomegalovirus IgG titers. Primary and secondary end points were the rate of angiographic restenosis at 6 months and the rate of target vessel reintervention at 1 year, respectively. Three hundred forty patients (62%) had a positive cytomegalovirus IgG titer. We obtained angiographic follow-up in 82% of all patients. Angiographic restenosis rate was 28.7% in patients with positive cytomegalovirus titers and 34.6% in patients with negative titers (P=0.18). Between the groups with and without positive cytomegalovirus titers, there were no significant differences in late lumen loss (1.16+/-0.90 mm and 1.23+/-0.86 mm, respectively, P=0.44). Target vessel reintervention was performed in 16.8% of the patients with positive cytomegalovirus titers and in 17.5% of those without (P=0.82). Even after correction for potential confounding variables by multivariate analysis, positive cytomegalovirus titers did not manifest as a predictor of angiographic restenosis (adjusted odds ratio [95% confidence interval], 0.78 [0.52 to 1.19]).

CONCLUSIONS

Previous cytomegalovirus infection does not carry an increased risk of restenosis after stenting.

The growth suppressor p27(Kip1) protects against diet-induced atherosclerosis

The molecular basis of atherosclerosis is associated with excessive proliferation of vascular cells. Previous studies have suggested an inverse correlation between the expression of the growth suppressor p27(Kip1) (p27) and cellular proliferation within human atherosclerotic tissue. However, no causal link between diminished p27 expression and atherogenesis has been established. We investigated the effect of p27 inactivation on diet-induced atherogenesis. We find that p27-deficient mice challenged with a high-fat diet for 1 month remain normocholesterolemic and have essentially no visible atheromas. However, when generated in an apolipoprotein E-null genetic background that leads to severe hypercholesterolemia in response to the atherogenic diet, deletion of p27 enhances arterial cell proliferation (approximately fourfold) and accelerates atherogenesis (approximately sixfold) compared with apolipoprotein E-deficient mice with an intact p27 gene. Analysis of apolipoprotein E-null mice bearing only one p27 allele inactivated reveals that a moderate decrease in p27 protein expression in the setting of hypercholesterolemia is sufficient to predispose to atherogenesis. Thus, our study establishes a molecular link between decreased p27 protein expression and atherogenesis in hypercholesterolemic animals.

Discordant cellular and humoral immune responses to cytomegalovirus infection in healthy blood donors: existence of a Th1-type dominant response

Previous studies have documented discordant cellular and humoral immune responses to subjects exposed to HIV-1, and that the nature of such responses may determine susceptibility and resistance to disease. We determined whether there is a spectrum of cellular versus humoral immunodominant responses to cytomegalovirus (CMV) infection. Blood samples from 50 healthy blood donors were tested for anti-CMV IgG antibodies and for proliferative responses of peripheral blood mononuclear cells (PBMC) to CMV antigens. Four patterns of immune responses to CMV were found: no detectable response (30%, Ab(-)/Tc(-)), anti-CMV IgG only (28%, Ab(+)/Tc(-)), both anti-CMV IgG and T lymphocyte proliferation to CMV antigens (18%, Ab(+)/Tc(+)), and, interestingly, T lymphocyte proliferation to CMV only (24%, Ab(-)/Tc(+)). To determine whether these immunodominant phenotypes correlate with the ability of PBMC to secrete IL-2 and IFN-gamma in response to CMV antigens, we found that a greater percentage of individuals with a T cell proliferative response to CMV antigens (Ab(-)/Tc(+) and Ab(+)/Tc(+)) responded with increased IL-2 (P = 0.001) and IFN-gamma levels (P = 0.002), compared to those without a proliferative response (Ab(-)/Tc(-) and Ab(+)/Tc(-)). Our data therefore demonstrate that different individuals exhibit different immunodominant patterns of response to CMV. In particular, some individuals who are exposed to CMV fail to develop an antibody response but do develop cellular immunity. Whether these different patterns predict susceptibility or resistance to CMV-induced disease remains to be determined.

MCMV induces neointima in IFN-gammaR-/- mice: intimal cell apoptosis and persistent proliferation of myofibroblasts

BACKGROUND

CMV infections have been linked to vasculopathies like atherosclerosis and Scleroderma. CMV infects vascular endothelium with intermittent shedding of the virus and the development of latency.

METHODS

We adopted a model of arteritis, developed by Presti et al. (1998), triggered by murine cytomegalovirus (MCMV) infection. Our studies focused on neointima formation. Groups of mice include: 1) immunocompetent 129S, 2) immunocompetent 129S receiving whole body irradiation and MCMV, 3) IFN-gammaR-/- receiving MCMV, and 4) IFN-gammaR-/- receiving MCMV and whole body irradiation.

RESULTS

Mice were inoculated with MCMV (5 x 10(4) or 1 x 10(5) PFU's) by i.p. injection; hearts and abdominal aortas were collected and histopathology evaluated. Infected immunocompetent animals exhibited widespread perivascular inflammation, which subsided by 8 weeks. Intimal pathology was not observed in any control group. Immunocompetent animals receiving MCMV and irradiation developed mild to moderate intimal lesions associated with medial and adventitial inflammation. IFN-gammaR-/- mice infected for 4 months and receiving whole body irradiation 2 months after infection developed pathology characterized by extensive adventitial and medial infiltrate and significant neointima, suggesting that infection and immunosuppression were co-requisites of neointima formation. Immunohistochemical analysis revealed myofibroblasts as a major component of neointima. The disease is characterized by up-regulation of growth factors (TGF-beta1, PDGF-A and B). Apoptosis was detected in the intimal layer of affected aortas. Active proliferation of myofibroblasts and infiltrating cells was also detected.

CONCLUSION

These results indicate that CMV infections may lead to intimal injury that results in the formation of neointima characteristic of autoimmune vasculopathies.

Chlamydia pneumoniae and luminal narrowing after coronary angioplasty

OBJECTIVES

Numerous studies have linked Chlamydia pneumoniae with atherosclerotic vessel disease and a trend for an association of the bacteria with restenosis after percutaneous transluminal coronary angioplasty (PTCA) has also been observed. The aim of this study was to assess the role of Chlamydia pneumoniae in the luminal narrowing taking place after PTCA.

DESIGN

A noninterventional 6-month follow-up study.

SETTING

A university hospital.

SUBJECTS

A total of 122 patients with angiographically proven coronary heart disease (CHD) referred for PTCA.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

The degree of luminal narrowing in the coronary arteries following coronary angioplasty.

RESULTS

The levels of C. pneumoniae antibodies (IgG, IgA and IgM classes) and immune complexes were not associated with luminal narrowing after PTCA in multivariate analyses whilst smoking, plasma endothelin levels and diabetes were. The serologic parameters did not change during the follow up either.

CONCLUSIONS

These results do not support a role for C. pneumoniae in luminal narrowing following PTCA.

Smooth muscle cell apoptosis in arteriosclerosis

Arteriosclerosis, a paradigmatic age-related disease, encompasses (spontaneous) atherosclerosis, restenosis after percutaneous transluminal coronary angioplasty, autologous arterial or vein graft arteriosclerosis and transplant arteriosclerosis. In all types of arteriosclerosis, vascular smooth muscle cell (SMC) accumulation in the intima is a key event, but abundant evidence also indicates the importance of SMC apoptosis in the development of arteriosclerosis. Because SMC proliferation and apoptosis coincide in arteriosclerotic lesions, the balance between these two processes could be a determinant during vessel remodeling and disease development. Various stimuli, including oxidized lipoproteins, altered hemodynamic stress and free radicals, can induce SMC apoptosis in vitro. As risk factors for arteriosclerosis, these stimuli may also lead to vascular cell apoptosis in vivo. The presence of apoptotic cells in atherosclerotic and restenotic lesions could have potential clinical implications for atherogenesis and contributes to the instability of the lesion. Based on the progress in this field, this review focuses on the mechanism and impact of SMC apoptosis in the pathogenesis of arteriosclerosis and highlights the role of biomechanical stress in SMC apoptosis.

Cytomegalovirus infection with interleukin-6 response predicts cardiac mortality in patients with coronary artery disease

BACKGROUND

Prospective data relating previous exposure to cytomegalovirus (CMV) to the risk of cardiac mortality are controversial. We investigated the effect of previous exposure to CMV infection on the risk of future cardiac disease-related death in relation to an underlying inflammatory response.

METHODS AND RESULTS

coronary angiography was performed in 1134 subjects, and 989 patients with documented coronary artery disease were studied prospectively. CMV-IgG titers and interleukin (IL)-6 levels were measured before angiography. Increasing titers of CMV correlated with the elevation of IL-6 levels (P<0.001) after adjustment for possible confounders. All patients were followed up for a median of 3.1 years (maximum 4.3 years). During follow-up, 96 patients died, 70 of cardiac disease. Overall, CMV seropositivity was not related to cardiac mortality after adjustment for confounding variables (P=0.19). In contrast, in patients with elevated IL-6 levels (>/=11.9 pg/mL, median level), CMV seropositivity was independently associated with a 3.2-fold (95% CI 1.4 to 7.3, P=0.007) increase in risk of future cardiac death, whereas in individuals without IL-6 elevation, previous CMV infection had no effect on cardiac mortality.

CONCLUSIONS

MV seropositivity in patients with an inflammatory response is independently associated with future cardiac mortality, whereas this association is lost in patients who do not demonstrate an inflammatory response. These data support the hypothesis that the atherosclerotic effects of CMV are mediated through an underlying inflammatory response.

Renal Arterial Stenosis in Renal Allografts: Retrospective Study of Predisposing Factors and Outcome after Percutaneous Transluminal Angioplasty

PURPOSE

To determine the predisposing factors to transplant renal arterial stenosis (TRAS) and assess the outcome of percutaneous transluminal angioplasty (PTA) as the primary treatment.

MATERIALS AND METHODS

Of 831 renal allograft recipients (584 cadaveric, 247 living related) between January 1991 and December 1998, 72 had hypertension and/or renal dysfunction. All 72 underwent arteriography, and their medical charts were retrospectively reviewed.

RESULTS

Prevalence of TRAS was 3.1% (26 of 831). Technical success rate of PTA was 94% (16 of 17), and clinical success rate was 82% (14 of 17). Those with renal dysfunction had a mean pre-PTA creatinine value of 2.6 mg/dL (230 micromol/L) +/- 0.5 (SD) versus a 1-week post-PTA value of 1.7 mg/dL (150 micromol/L) +/- 0.3 (P <.001). Of those with hypertension, all but one had substantial improvement in mean diastolic blood pressure. At 26.9 months mean follow-up in 16 patients with successful PTA, two stenoses reoccurred, and two grafts were lost to chronic rejection. TRAS was present in 14 of 45 end-to-side anastomoses and 12 of 27 end-to-end anastomoses (P =.31), and TRAS was more prevalent in cadaveric grafts (24 of 584) than in living related grafts (two of 247). In cadaveric grafts, the mean cold ischemia time was 29.0 hours +/- 6.9 in those with TRAS (n = 24), as compared with 25.5 hours +/- 8.1 in those with no TRAS (n = 39; P = .35). Seven of 17 patients with acute rejection and six of 35 with chronic rejection had TRAS.

CONCLUSION

Primary treatment of TRAS with PTA has good intermediate-term results. TRAS is more prevalent in cadaveric allografts with long cold ischemia time.

Cytomegalovirus in renal transplantation

Cytomegalovirus (CMV) was first isolated from the salivary gland and kidney of two dying infants with cytomegalic inclusion bodies and reported in 1956 (1). Two other laboratories isolated CMV at approximately the same time. Thus, CMV was initially called "salivary gland virus" or "salivary gland inclusion disease virus". In 1960, Weller et al. (2) proposed the use of the term cytomegalovirus. Klemola and Kaarianinen (3) first described CMV mononucleosis, the principal presentation of previously healthy individuals, in 1965. CMV was first isolated in a renal transplant patient in 1965,

Virally encoded 7TM receptors

A number of herpes- and poxviruses encode 7TM G-protein coupled receptors most of which clearly are derived from their host chemokine system as well as induce high expression of certain 7TM receptors in the infected cells. The receptors appear to be exploited by the virus for either immune evasion, cellular reprogramming, tissue targeting or for cell entry. Through their efficient evolutionary machinery and through in vivo selection performed directly on the human cellular and molecular targets, virus have been able to optimize the encoded receptors for distinct pharmacological profiles to help in various parts of the viral life cyclus. Most of the receptors encoded by human pathogenic virus are still orphan receptors, i.e. the endogenous ligand is unknown. In the few cases where it has been possible to characterize these receptors pharmacologically, they have been found to bind a broad spectrum of either CC chemokines, US28 from human cytomegalovirus, or CXC chemokines, ORF74 from human herpesvirus 8. Nevertheless, US28 has been specifically optimized for recognition of the membrane bound chemokine, fractalkine, conceivably involved in cell-cell transfer of virus; whereas ORF74 among the endogenous CXC chemokines has selected angiogenic chemokines as agonists and angiostatic/modulatory chemokines as inverse agonists. ORF74 possess substantial cell-transforming properties and signals with high constitutive activity through the phospholipase C and MAP kinase pathways. Interestingly, transgenic expression of this single gene in certain lymphocyte cell lineages leads to the development of lesions which are remarkably similar to Kaposi's sarcoma, a human herpesvirus 8 associated disease. Thus, this and other virally encoded 7TM receptors appear to be attractive future drug targets.