Chronic infection and coronary artery disease

Maxillary Sinus Lobular Capillary Hemangioma in a 15-Year-Old Boy

Lobular capillary hemangioma (LCH) is a benign capillary proliferation with a microscopically distinctive lobular architecture, composed of small to medium-sized vessels of capillary type. Rarely, it originates from the mucosa of the nasal cavity, most frequently from the anterior nasal septum, turbinates, and nasal vestibule. Etiology is unclear, but previous investigations suggest that this lesion is associated with injury, hormonal factors, some viral infections, and therapy with some drugs. We present a case of LCH arising from the medial wall of the maxillary sinus in a 15-year-old boy, which was completely excised by preoperative embolization and endoscopic sinus surgery. To our knowledge, this is the second reported case of an LCH originating from the maxillary antrum. Etiology, pathogenesis, diagnosis, and treatment modalities of LCH were also discussed.

The Time Course of Serum C-Reactive Protein is More Predictive of Mortality than its Baseline Level in Peritoneal Dialysis Patients

Background

Several recent studies reported that a high baseline serum C-reactive protein (CRP) is a powerful predictor of mortality in dialysis patients. However, the acute-phase response is intermittent and not a continuous feature in an individual patient. The aim of this prospective study was to determine whether serial analysis of serum CRP during follow-up allows better prediction of mortality and echocardiographic cardiac disease than a single baseline measurement in peritoneal dialysis (PD) patients.

Methods

97 PD patients were monitored for 3 years from the beginning of the treatment. We evaluated the effect of demographic features, comorbidity, blood pressure, blood biochemistry, including CRP, residual renal function, and indices of dialysis adequacy, on mortality and left ventricular hypertrophy (LVH). Cox regression analysis using both the baseline and the averaged values of the study parameters was carried out to determine factors predicting mortality. Logistic regression analysis was performed to determine which factors were independently predictive for LVH and the type of time course of serum CRP.

Results

Baseline serum CRP was elevated in 29 patients (29.9%). While serum CRP exhibited a stable course (normal or high) in 55 patients (56.7%), it varied considerably over time in 42 patients (43.2%). In the Cox models, both the averaged serum CRP and the type of variability of CRP were predictors of mortality. On the contrary, baseline CRP did not affect adjusted survival. The averaged CRP was also an independent factor affecting LVH, but baseline CRP was not. Age, comorbidity index, instilled dialysate glucose concentration, and Kt/V urea were independently associated with the type of time course of serum CRP.

Conclusion

The averaged value of serum CRP is more predictive of prognosis compared to the baseline value in PD patients. Determining serum CRP on a regular basis may be helpful to detect early signs of tissue damage or asymptomatic inflammation.

Multiple cerebral arterial stenosis associated with hepatitis B virus infection

Background

There are conflicting findings regarding the association between hepatitis B (HB) virus (HBV) infection and atherosclerosis.

Case Report

A 34-year-old man was admitted for transient dysarthria and facial palsy. Ten years previously he had been diagnosed with HBV infection and treated with lamivudine (100 mg/day). Reactivation of HBV was detected 6 months before this recent admission. Serologic tests revealed that he was positive for HB early antigen, HB surface antigen, and anti-HB core. Brain magnetic resonance images were normal, but magnetic resonance angiograms revealed severe stenosis of the right middle cerebral artery, both external carotid arteries, and the basilar artery.

Conclusions

This case report reveals that a young patient with reactivated HBV developed multiple arterial stenoses even though he had no risk factors for this disease.

Endothelial function and cardiovascular risk stratification in menopausal women

BACKGROUND

Peripheral arterial, endothelium-dependent, flow-mediated reactive hyperemia is reduced in individuals with atherosclerosis. This study tested the hypothesis that digital tonometry, as a surrogate of endothelial function, is useful to stratify cardiovascular risk in recently menopausal women who are asymptomatic for cardiovascular disease.

METHODS

Women undergoing screening for the Kronos Early Estrogen Prevention Study (KEEPS) were evaluated for conventional risk factors, flow-mediated reactive hyperemia by digital tonometry (RHI), carotid intima-media thickness (CIMT) by ultrasound, and coronary arterial calcium (CAC) by 64-slice CT scanner.

RESULTS

One hundred and two non-diabetic Caucasian women (53.0 +/- 2.3 years old, 18.0 +/- 9.0 months past their last menses) participated; 72% were never-smokers. Fourteen women had positive CAC scores (range 0.5-133 Agatston units); CIMT ranged from 0.57 to 1.06 mm. RHI ranged from 1.26 to 5.44. RHI did not correlate with time past menopause, CAC, CIMT, total cholesterol or low density lipoprotein cholesterol. The significant negative correlation of RHI with body mass index (r = -0.21, p = 0.031) was lost in non-smokers (r = - 0.17, p = 0.14). There was also a negative correlation of high density lipoprotein cholesterol with CAC, both in the overall group and non-smokers (rho = -0.20, p = 0.05 and rho = -0.27, p = 0.02, respectively).

CONCLUSIONS

RHI varies widely in healthy women within the first 3 years of menopause. RHI was not associated with standard risk assessment algorithms, CAC or CIMT. RHI may indicate an additional, independent component and non-invasive tool to further stratify cardiovascular risk in recently menopausal women. As KEEPS continues, data on RHI will provide information regarding hormonal therapy, endovascular biology and atherosclerotic risk.

Markers of Inflammation and Infection Influence the Outcome of Patients With Baseline Asymptomatic Carotid Lesions

BACKGROUND AND PURPOSE

It is still in debate whether the evaluation of markers of infection and inflammation may be of importance for cerebrovascular and cardiovascular prevention, and we aimed to investigate this field in a prospective 5-year clinical follow-up study in patients with early stages of atherosclerosis.

METHODS

We studied 668 subjects divided in 3 groups according to the results of carotid ultrasound examination: (1) normal subjects, if intima-media thickness (IMT) was <0.9 mm; (2) with IMT, if IMT was between 0.9 and 1.5 mm; and (3) with asymptomatic carotid plaque, if IMT was >1.5 mm. Traditional cardiovascular risk factors were investigated, and laboratory analysis included measurement of plasma lipids, fibrinogen, C-reactive protein, IgG antibodies for helicobacter pylori (HP), cytotoxic HP, cytomegalovirus, and chlamydia pneumoniae.

RESULTS

Cerebrovascular or cardiovascular events were registered in 18% of patients during the follow-up, and at multivariate analysis we found that the high levels of fibrinogen (P<0.0001) and C-reactive protein (P=0.014), the seropositivity to cytotoxic HP (P=0.001) and chlamydia pneumoniae (P=0.026), the presence of IMT or asymptomatic carotid plaque (P<0.0001), and the total burden of infections (P<0.0001) were the variables predictive of the clinical events.

CONCLUSIONS

Beyond traditional cardiovascular risk factors, markers of inflammation and infections seem to significantly influence the occurrence of cerebrovascular and cardiovascular events in patients with baseline asymptomatic carotid lesions.

Detection of Chlamydia pneumoniae and Helicobacter pylori in atherosclerotic plaques of carotid artery by polymerase chain reaction

OBJECTIVES

A possible role of some microorganisms has been proposed in the pathogenesis of atherosclerosis, but it is still an unresolved issue. We investigated the presence of Chlamydia pneumoniae and Helicobacter pylori DNA in carotid artery atherosclerotic plaques by using PCR.

METHODS

One hundred and four patients with atherosclerotic diseases were included. The study group consisted of 52 atherosclerotic plaque specimens obtained from the carotid arteries of patients who had carotid endarterectomy and the control group consisted of 52 specimens obtained from the macroscopically healthy regions of ascending aorta in patients who had undergone coronary artery bypass grafting. The presence of C. pneumoniae and H. pylori DNA in endarterectomy specimens were demonstrated by PCR.

RESULTS

C. pneumoniae DNA was detected in 16 of 52 (30.8%) atherosclerotic plaques and 1 of 52 (1.9%) macroscopically healthy ascending aorta wall specimens (P < 0.001). H. pylori DNA was detected in 9 of 52 (17.3%) atherosclerotic plaques and none of the controls (P = 0.003).

CONCLUSIONS

The higher incidence of C. pneumoniae and H. pylori DNA in atherosclerotic plaques suggests that these microorganisms may play a role in the pathogenesis of atherogenesis.

Systemic antibodies to the leukotoxin of the oral pathogen Actinobacillus actinomycetemcomitans correlate negatively with stroke in women

BACKGROUND

Chronic infections and associated inflammatory markers are suggested risk factors for cardiovascular diseases (CVD) and stroke. The proinflammatory cytokine interleukin (IL)-1beta is suggested to play a role in the regulation of local inflammatory responses in both CVD and periodontitis. The leukotoxin from the periodontal pathogen Actinobacillus actinomycetemcomitans has recently been shown to cause abundant secretion of IL-1beta from macrophages. The aim of the present study was to compare the prevalence of systemic antibodies to A. actinomycetemcomitans leukotoxin in stroke cases (n = 273) and matched controls (n = 546) in an incident case-control study nested within the Northern Sweden MONICA and Vasterbotten Intervention cohorts.

METHODS

Antibodies to A. actinomycetemcomitans leukotoxin were analyzed in a bioassay with HL-60 cells (leukocytes), purified A. actinomycetemcomitans leukotoxin, and plasma. Plasma samples which inhibited lactate dehydrogenase release from leukotoxin-lysed cells by > or =50% were classified as antibody positive.

RESULTS

Antibodies to A. actinomycetemcomitans leukotoxin were detected in 18.8% of the women and 15.2% of the men. Women with those antibodies had a significantly decreased risk for stroke (OR = 0.28, 95% CI: 0.13-0.59), but not men (OR = 0.88, 95% CI: 0.52-1.51).

CONCLUSION

The immunoreactivity to A. actinomycetemcomitans leukotoxin correlates negatively with a future stroke in woman, but not in men. Further studies are needed to explain the underlying mechanisms, as well as the biological relevance of this finding.

Hepatitis B virus infection and coronary atherosclerosis: Results from a population with relatively high prevalence of hepatitis B virus

AIM: To investigate the possible association between hepatitis B virus (HBV) infection and angiographically proven coronary artery disease (CAD) in a population with relatively high prevalence of HBV.

METHODS: Sera from 434 patients who underwent coronary angiography were tested for HBV antigens (HBsAg, HBeAg) and antibodies (Anti-HBs, Anti-HBc and Anti-HBe) by ELISA.

RESULTS: Seventy-seven percent (224/291) of the patients with CAD and 73.4% (105/143) of the patients without angiographic evidence of atherosclerosis were seropositive for HBV (P>0.05). However, C-reactive protein (CRP) levels were significantly higher in patients with CAD (P = 0.008), while lower in HBV seropositive population (P = 0.043 and P = 0.021 after adjustment for conventional risk factors).

CONCLUSION: Our results suggested HBV infection negatively correlates with CRP levels, but seems not to be associated with coronary atherosclerosis.

Effect of chronic Pseudomonas aeruginosa infection on the development of atherosclerosis in a rat model

In order to investigate the possible relationship between atherosclerosis and chronic Pseudomonas aeruginosa infection, 66 Wistar rats were given five separate intratracheal inoculations of either P. aeruginosa or sterile saline at 4-week intervals. The rats were divided into four groups: group 1 was infected with P. aeruginosa and fed a diet containing cholesterol 1% w/v; group 2 was infected with P. aeruginosa and fed a normal diet; group 3 was not infected and was fed a diet containing cholesterol 1% w/v; and group 4 (the control group) was not infected and was fed a normal diet. One month after the final inoculation, the rats were killed humanely; computerised image analysis was used to evaluate sections of the aorta and heart, and the maximal wall thickness of the aorta and coronary artery. The aortic wall thickness was significantly greater for group 1 (329.53 +/- 58.06 microm) compared to groups 2 (190.59 +/- 27.81 microm; p < 0.0001), 3 (262.90 +/- 61.12 microm; p < 0.0004) and 4 (158.00 +/- 30.30 microm; p < 0.0001). Similarly, the coronary artery wall thickness was significantly greater for group 1 (72.96 +/- 10.67 microm) compared to groups 2 (35.07 +/- 8.53 microm; p < 0.0001), 3 (41.45 +/- 10.22 microm; p < 0.0001) and 4 (32.30 +/- 5.27 microm; p < 0.0001). These findings strengthen the hypothesis that chronic infection plays a role in the pathogenesis of atherosclerosis.

Chlamydia pneumoniae and Atherosclerosis: No Way-Out or Long Way?

Recently, Chlamydia pneumoniae is the microorganism frequently implicated in the infection-based inflammatory atherogenous hypothesis. Although in vitro experimental data and initial sero-epidemiologic, pathology-based studies and antibiotic trials supported this interesting hypothesis, later data are conflicting. Some confounding factors are the causes of uncertainty; lacking of standard methods for C. pneumoniae detection, co-existence of other atherosclerotic risk factors and anti-inflammatory effects of antibiotics used in clinical trials seem to be the principal ones. Standardization of methodology used, antibiotic trials with a different orientation-design and a vaccine preparation that eventually will be tested in clinical trials with a long follow-up, should provide a definite answer regarding the probability C. pneumoniae to be a main, a secondary or an irrelevant factor to atherosclerosis. Studies linking C. pneumoniae to inflammation and accelerated atherosclerosis in renal failure patients are accumulated but limitations are similar to the above mentioned.

Hepatitis B and C virus infection and the risk of atherosclerosis in a general population

BACKGROUND

The development of atherosclerosis has an inflammatory component. Currently it is not clear, whether hepatitis B and C virus infections are associated with the risk of atherosclerosis. The aim of the present analysis was to investigate those relationships in a population sample.

METHODS AND RESULTS

The study of health in Pomerania (SHIP) is a cross-sectional study of the adult population in the northeast of Germany. HBs antigen (HBsAg) and IgG antibodies against hepatitis B and C virus (anti-HBs and anti-HCV) were determined by enzyme linked immunosorbent assays. Fifteen subjects (0.4%) were positive for HBsAg, and 21 subjects (0.5%) were positive for anti-HCV. Among the persons who had no history of anti-hepatitis B vaccination, 213 individuals (5.0%) were found to be as positive for anti-HBs. These individuals and those with prevalent anti-HCV antibodies were regarded as cases (n = 233). The control group comprised of 4033 individuals. Multivariable analyses revealed that there was no independent association between anti-HBs and anti-HCV antibody seropositivity and atherosclerotic end-points such as prevalent myocardial infarction, stroke, carotid intima-media thickness (IMT), carotid plaques and stenoses.

CONCLUSION

There is no association between serological markers for hepatitis B and C virus infection and the risk of atherosclerosis in this population sample.

Leukocyte count as an independent predictor of recurrent ischemic events

BACKGROUND AND PURPOSE

Inflammatory markers predict first-time ischemic events. We investigated whether leukocyte and differential counts predict recurrent events and ischemic events in high-risk populations, and whether such events are preceded by acutely exacerbated inflammation.

METHODS

We studied 18 558 patients with ischemic stroke, myocardial infarction, or peripheral arterial disease who participated in the trial of Clopidogrel versus Aspirin in Patients at Risk of Ischemic Events (CAPRIE), a study that compared the occurrence of ischemic stroke, myocardial infarction, or vascular death under randomized treatment with aspirin or clopidogrel. Leukocyte counts were frequently assessed during followup.

RESULTS

Compared with the quartile with lowest leukocyte counts at baseline (<5.9x10(9)/L), patients in the top quartile (>8.2x10(9)/L) had higher risks for ischemic stroke (relative risk 1.30; P=0.007), myocardial infarction (relative risk 1.56, P<0.001), and vascular death (relative risk 1.51; P<0.001) after adjustment for other risk factors. Neutrophil counts contributed most to increased risk. Assessments of regression dilution effects based on replicate measurements show that these risk associations may underestimate the real associations by 30 to 50%. Treatment with aspirin or clopidogrel did not influence predictive effects by leukocytes. In the week before a recurrent event, but not at earlier time points, the leukocyte count was significantly increased over baseline levels (n=211; mean difference +0.46x10(9)/L; P=0.005).

CONCLUSIONS

Leukocyte counts and mainly neutrophil counts are independently associated with ischemic events in these high-risk populations. An increase of leukocyte counts over baseline levels heralds a period of increased risk lasting about one week.

Antibiotic treatment of atherosclerosis

PURPOSE OF REVIEW

Several lines of evidence have demonstrated an association between a variety of chronic bacterial infections and atherosclerotic cardiovascular disease. This has led to the proposal that antibiotic therapy might be helpful in the secondary prevention of atherosclerosis. A variety of smaller pilot studies have been reported testing this hypothesis and several large multicenter trials are also underway. The purpose of this review is to summarize the results of these studies and comment on their implications for the treatment of atherosclerosis.

RECENT FINDINGS

Most of the antibiotic studies to date have been secondary prevention studies that have targeted patients exposed to Chlamydia pneumoniae. Most have used either azithromycin or roxithromycin with treatment courses ranging from a few days to 3 months. Several small studies of coronary artery disease patients have shown significant promise for reducing cardiovascular events such as death, myocardial infarction, or admission for unstable angina. However, other studies have not been so positive. Weekly Intervention with Zithromax for Atherosclerosis and its Related Disorders, WIZARD, the largest study to date, in which stable post-myocardial infarction patients were randomized to receive a 3-month course of azithromycin or placebo, demonstrated a significant reduction in death and myocardial infarction by 6 months, but this benefit was not sustained throughout the remaining course of follow-up. The Azithromycin and Coronary Events (ACES) and Pravastatin or Atorvastatin Evaluation and Infection Therapy (PROVE-IT) trials are ongoing and are testing the effect of more prolonged treatment duration.

SUMMARY

A variety of antibiotic trials for the secondary prevention of atherosclerosis have been performed. Several pilot studies have shown significant positive clinical effects, but, thus far, no large randomized trial has confirmed those findings. Some concerns over the antibiotics chosen and the duration of treatment have been raised. Other trials are underway to address some of those concerns. In the meantime, no recommendation for the use of antibiotic therapy for the secondary prevention of atherosclerosis can yet be made.

Hepatitis A IgG seropositivity and coronary atherosclerosis assessed by angiography

BACKGROUND

Infectious agents, in particular intracellular pathogens that can establish long-term, persistent infection, may play an important role in atherogenesis. We tested the hypothesis that hepatitis A virus (HAV) could be associated with significant coronary artery disease.

METHODS

The possible association between HAV infection and angiographically proven coronary artery disease (CAD) was studied. Blood from 218 patients undergoing coronary angiography was tested for serum IgG antibodies to HAV.

RESULTS

Of the 218 patients, 178 (81.7%) had anti-HAV IgG antibodies. CAD prevalence was 66.3% in HAV seropositive and 57.5% in HAV seronegative patients (P=0.385). In contrast, the number of infectious pathogens to which an individual has been exposed correlates with CAD. Four or more of the six seromarkers tested for particular infections (HAV, Chlamydia pneumoniae, Helicobacter pylori, cytomegalovirus, influenza type A and type B) were positive in 48.8% of patients with CAD and in 31.2% of patients in patients without CAD (P=0.02).

CONCLUSIONS

This analysis demonstrated that HAV seropositivity is not a predictor of risk for CAD. HAV infection, therefore, seems not to be associated with CAD. The number of infectious agents to which an individual has been exposed ('infectious burden') correlates with CAD.

C-reactive protein, lipoprotein(a), homocysteine, and male sex contribute to carotid atherosclerosis in peritoneal dialysis patients

BACKGROUND

In patients with end-stage renal disease, the morbidity and mortality of cardiovascular disease are substantially greater than in the general population. Advancement in understanding the pathogenesis of atherosclerotic vascular disease suggests a central role of inflammation in atherogenesis. However, clinical data evaluating the role of inflammation in atherogenesis are sparse in peritoneal dialysis (PD) patients.

METHODS

We measured serum C-reactive protein (CRP), intact parathyroid hormone, lipoprotein(a) [Lp(a)], interleukin-1 receptor antagonist (IL-1Ra), tumor necrosis factor soluble receptor (TNF-sR), fibrinogen, and plasma homocysteine (Hcy), as well as intima-media thickness (IMT) and number of atherosclerotic plaques (plaque score [PS]) in the carotid arteries by means of carotid B-mode ultrasonography in 59 PD patients (35 men, 24 women; mean age, 52.4 years; average dialysis period, 36 months). All patients had chronic glomerulonephritis.

RESULTS

Sixty-eight percent of PD patients had at least 1 plaque. Serum CRP level was greater than the upper limit of the normal range in 52.5% of patients. Compared with PD patients with normal CRP levels, concentrations of such proinflammatory cytokines as IL-1Ra and TNF-sR, Lp(a), and Hcy were increased in PD patients with elevated CRP levels. However, no differences in plasma fibrinogen and intact parathyroid hormone levels were found between PD patients with increased and normal CRP levels. In a multiple regression model, age, male sex, CRP level, and Lp(a) level were independent predictors of IMT. Similarly, male sex, CRP level, Lp(a) level, and Hcy level were independent correlates of PS.

CONCLUSION

This study suggests that Lp(a) and Hcy levels and male sex, and especially CRP level, have an important role in carotid atherosclerosis in PD patients.

Chlamydophila pneumoniae induces ICAM-1 expression in human aortic endothelial cells via protein kinase C-dependent activation of nuclear factor-kappaB

Chlamydophila pneumoniae has an epidemiological link with atherosclerosis and acute cardiovascular events. One mechanism that may explain such a link is the increased expression of intracellular adhesion molecule-1 (ICAM-1) in C pneumoniae-infected endothelial cells. Upregulation of ICAM-1 by C pneumoniae is well recognized and has been extensively studied, but the signaling pathways involved are not yet defined. Because upregulation of ICAM-1 by cytokines and other stimuli has been shown to be mediated by either mitogen-activated protein kinase, protein kinase C (PKC), or nuclear factor-kappaB (NF-kappaB) pathways, we examined whether these pathways were involved in the ICAM-1 upregulation induced by C pneumoniae. Our data show a time-dependent phosphorylation of p44/p42 and SAPK/JNK pathways in C pneumoniae-infected cells. However, inhibition of the classic mitogen-activated protein kinase pathway using the PD98059 and U0126 inhibitors and inhibition of SAPK/JNK pathway did not suppress C pneumoniae-induced ICAM-1 expression. C pneumoniae also activates the NF-kappaB pathway at 30 minutes after infection. Treatment of human aortic endothelial cells (HAECs) with the NF-kappaB inhibitors BAY117085 and caffeic acid phenethyl ester led to a concentration-dependent inhibition of C pneumoniae-induced ICAM-1 upregulation. Finally, C pneumoniae-infected HAECs show membrane translocation of total PKC 30 minutes after cell infection. Calphostin C, a general PKC inhibitor, blocked both C pneumoniae-induced ICAM-1 expression and C pneumoniae-induced NF-kappaB translocation. In conclusion, we demonstrated that C pneumoniae-induced ICAM-1 expression in HAECs requires NF-kappaB and PKC activation and that NF-kappaB activation is PKC dependent.

Antibiotics in primary prevention of myocardial infarction among elderly patients with hypertension

BACKGROUND

Given the premise that certain bacteria (such as Chlamydia pneumoniae) may play a role in the etiology of atherosclerosis, subjects treated with antibiotics that have antibacterial activity against C pneumoniae may be at lower risk for the development of an acute myocardial infarction (MI) than untreated subjects.

METHODS

A case-control design, nested within a cohort of 29,937 elderly subjects in whom antihypertensive therapy was initiated (1982-1995) was used, in which each subject who was hospitalized with a primary discharge diagnosis of MI between 1987 and 1995 (n = 1047) was matched on calendar time to 5 randomly selected control subjects for exposure contrasts. Conditional logistic regression analyses were conducted to adjust for predisposing factors for MI.

RESULTS

Although no clear consistent effect of antibiotics use was found in relation to MI, a trend was observed for a decreased risk of acute MI in patients receiving a prescription for antichlamydial antibiotics in the preceding 3 months (odds ratio 0.68, 95% CI 0.46-1.00). Antibiotics without antichlamydial activity showed no benefit in MI risk.

CONCLUSION

The beneficial effect of certain antichlamydial antibiotics in reducing the risk of MI cannot be excluded on the basis of this representative cohort of elderly patients in a routine clinical care setting. Larger prospective studies are required to confirm the usefulness of antibiotics in the primary prevention of MI.

Role of antibiotics for the prevention of cardiovascular disease

OBJECTIVE

To evaluate the data regarding the use of antibiotic therapy for the prevention of cardiovascular events.

DATA SOURCES

Pertinent literature was identified through a MEDLINE search (1966-September 2001) and through other secondary literature databases and/or bibliographies of pertinent articles.

DATA SYNTHESIS

Cardiovascular disease is a common cause of morbidity and mortality among the general population, with well-defined risk factors (e.g., diabetes, hypertension, hyperlipidemia, cigarette smoking, genetic predisposition). Clinical data evaluating the association between the aforementioned risk factors and the development of atherosclerosis and subsequent cardiovascular disease are substantial; however, these risk factors may only partially explain the high prevalence of cardiovascular disease. The presence of Chlamydia pneumoniae within atherosclerotic lesions has been documented and may be an additional risk factor for the development and progression of cardiovascular disease.

CONCLUSIONS

The results of primary and secondary prevention trials have shown conflicting evidence with regard to the beneficial effects of antibiotic therapy to reduce cardiovascular events. Currently, the lack of certainty in published data does not support the use of antibiotics for the prevention of cardiovascular disease. Clinicians should continue to emphasize interventions proven to reduce adverse cardiovascular events such as smoking cessation, reduction of hyperlipidemia, and control of hypertension.

Genetic Polymorphisms in Cytokine and Adhesion Molecule Genes in Coronary Artery Disease

Both inflammation and genetics play an important role in the pathogenesis of atherosclerosis and coronary artery disease. Epidemiological studies have investigated the association between coronary artery disease (CAD) and gene polymorphisms of the inflammatory molecules tumor necrosis factors (TNF) alpha and beta, transforming growth factors (TGF) beta-1 and beta-2, interleukin (IL)-1 and its receptor antagonist (IL-1ra), CD14 (the receptor for lipopolysaccharide), P- and E-selectins, and platelet endothelial cell adhesion molecule (PECAM)-1. Current evidence suggests that the TNF polymorphisms explored so far are not linked to CAD. The majority of studies conducted showed no significant association between TGFbeta-1 and coronary atherosclerosis, but the data currently available are somewhat controversial. Some polymorphisms may increase the risk of myocardial infarction (MI) within specific ethnic groups or in certain populations. The association between the IL-1 system and atherosclerosis is complex and may vary as a result of a number of factors, such as stage of disease, clinical phenotype, and possibly population characteristics. The E-selectin gene (SELE) Arg128, 98T, and Phe554 alleles may increase the risk of atherosclerosis, but not necessarily the risk of MI. This association seems to be more pronounced in younger patients. The PECAM1 Leu125Val and Ser563Asn polymorphisms may increase the risk of atherosclerosis but not necessarily of MI. This association may be especially important in patients with a low risk for developing atherosclerosis. Current data indicate that screening for CD14-260C/T genotypes is unlikely to be a useful tool for risk assessment and it remains unclear whether CD14 polymorphisms significantly increase the risk of MI. The associations between candidate gene polymorphisms and CAD are complex as a consequence of pleiotropy, variations with age, selection due to the high lethality of the disease, and interactions with other genes and environmental factors. Nonetheless, although the current data is preliminary and partly conflicting, it does provide some evidence that alterations in the genetics of the inflammatory system may modify the risk of CAD.

Influenza A and B IgG seropositivity and coronary atherosclerosis assessed by angiography

Infectious agents, in particular intracellular pathogens that can establish long-term, persistent seropositivity, may play an important role in atherogenesis. The possible association between influenza type A and B infection and angiographically proven coronary artery disease (CAD) and the effect of the aggregate pathogen burden on CAD was studied by testing blood from 218 patients undergoing coronary angiography for serum IgG antibodies to influenza A and B, and for antibodies to four other pathogens (hepatitis A, Chlamydia pneumoniae, Helicobacter pylori, and cytomegalovirus). This analysis demonstrates that although influenza (A and B) seropositivity represents no predictor of risk for CAD, infectious burden is independently associated with coronary atherosclerosis.

Chlamydophila pneumoniae infection of human aortic endothelial cells induces the expression of FC gamma receptor II (FcgammaRII)

Chronic endothelial infection is believed to be one of the factors able to cause endothelial cell damage and trigger the onset of human atherosclerosis. Chlamydophila pneumoniae infects endothelial cells and has received special attention because of both epidemiological and experimental evidence supporting its role as a risk factor for atherosclerosis. It is also possible that otherwise independent risk factors for atherosclerosis may have synergistic effects. Immune phenomena, such as the formation of circulating immune complexes (IC) containing modified LDL and corresponding antibodies, have been linked to the development of coronary artery disease. The antibodies involved in the immune response to modified lipoproteins are predominantly of the pro-inflammatory IgG1 and IgG3 subclasses. However, it is difficult to understand how circulating IC could cause endothelial damage and initiate the atherosclerotic process, unless they were formed in the subendothelial space or immobilized by endothelial cells. The last hypothesis would be possible if endothelial cells expressed Fcgamma receptors. Healthy endothelial cells do not express Fcgamma receptors, but endothelial cells infected by a variety of infectious agents do. Thus we decided to investigate whether infection of endothelial cells with C. pneumoniae is also able to cause the expression of Fcgamma receptors. The expression of Fcgamma receptors (CD64, 32, and 16) on human aortic endothelial cells infected with C. pneumoniae for 4, 24, 36, and 48 h was studied by flow cytometry. Twenty-four hours after infection 30-40% of the endothelial cells had detectable inclusion bodies, 8-9% of the total number of cells (approximately 25% of the infected cells) expressed FcgammaRII, and about 1.5-2% (5% of infected cells) expressed FcgammaRI and FcgammaRIII. Double-staining studies confirmed that the expression of FcgammaRII was limited to C. pneumoniae-infected endothelial cells. We conclude that C. pneumoniae infection induces primarily the expression of FcgammaRII by endothelial cells and this may be a significant link between two proposed pathogenic mechanisms involved in the pathogenesis of human atherosclerosis.

Cerebral aneurysms in a child with acquired immune deficiency syndrome during rapid immune reconstitution

A 12-year-old boy with perinatally acquired human immunodeficiency virus infection an d Centers for Disease Control and Prevention class C3 disease presented with acute onset of confusion and a right-sided movement disorder 5 months after beginning a new antiretroviral regimen. His CD4 count had been below 50 cells/microL for 4 years but had abruptly risen to more than 250 cells/microL. Computed tomographic and magnetic resonance imaging scans showed cerebral aneurysms and new cerebral lesions consistent with ischemic strokes. The presentation during immune reconstitution suggests that cerebral aneurysms in pediatric patients with acquired immune deficiency syndrome can result from an immune-mediated response to chronic vascular infection.

Secondary prevention of coronary artery disease with antimicrobials: current status and future directions

Over the past several decades, coronary artery disease (CAD) has become the major health problem in the Western world with more than 50% of deaths attributed to its complications. The exact causes of atherosclerosis are not clearly known, although multiple risk factors (e.g. hypertension, hyperlipidemia, diabetes mellitus, family history, and smoking) have been well described. However, these risk factors account for only about 50% of the total risk of CAD. Consequently, an ongoing search is under way to discover new risk factors for atherosclerosis as well as the basic underlying causes of progression. Although the evidence is not yet definitive, recent studies have shown that chronic infection by such bacterial organisms as Chlamydia pneumoniae, Helicobacter pylori, and a variety of dental pathogens may play a causative role in atherosclerosis. If this is true, then antimicrobial therapy may be helpful in the secondary prevention of CAD. Indeed, several small studies have already been completed testing this hypothesis. This article reviews the evidence associating these bacterial pathogens to CAD and presently available information regarding the use of antibiotics in the setting. At present, most studies evaluating the potential efficacy antimicrobials in the secondary prevention of CAD have tested the use of macrolide antibodies. Although several small preliminary studies have reported promising results favoring a clinical benefit from even short (<3 months) courses of antimicrobial therapy, the first large clinical trial, the Weekly Intervention with Zithromax for Atherosclerosis and its Related Disorders (WIZARD) study, did not show a statistically significant beneficial effect of a 3 month course of azithromycin over placebo by the end of up to 4 years follow-up. However, a statistically significant (p = 0.03) 33% reduction in death and myocardial infarction was found at 6 months, 3 months after the discontinuation of antibiotics. This robust clinical benefit, however, was not sustained over the ensuing 3.5 years of follow-up. These disappointing long-term outcomes of short-term therapy with antimicrobials may be explained by the recently discovered difficulty found in eradicating chronic vascular infections such as C. pneumoniae. It remains possible that longer term antimicrobial therapy or short-term use of more potent single agents or combinations, capable of effectively eradicating the offending organisms might provide added clinical benefit in the fight against CAD. Further studies are ongoing or planned to evaluate this potential. In the meantime, it is not presently recommended that antimicrobials be routinely prescribed for the secondary prevention of CAD.

T-cell immunity in acute coronary syndromes

Acute coronary syndromes (ACS) are complications of atherosclerotic vascular disease that are triggered by the sudden rupture of an atheroma. Atherosclerotic plaque stability is determined by multiple factors, of which immune and inflammatory pathways are critical. Unstable plaque is characterized by an infiltrate of T cells and macrophages, thereby resembling a delayed hypersensitivity reaction. On activation, T cells secrete cytokines that regulate the activity of macrophages, or the T cells may differentiate into effector cells with tissue-damaging potential. Constitutive stimulation of T cells and macrophages in ACS is not limited to the vascular lesion but also involves peripheral immune cells, suggesting fundamental abnormalities in homeostatic mechanisms that control the assembly, turnover, and diversity of the immune system as a whole. This review gives particular attention to the emergence of a specialized T-cell subset, natural killer T cells, in patients with ACS. Natural killer T cells have proinflammatory properties and the capability of directly contributing to vascular injury.

Establishment of Porphyromonas gingivalis-specific T-cell lines from atherosclerosis patients

Porphyromonas gingivalis-specific T-cell lines were established from atherosclerotic lesions from two patients. T-cell lines were found to be a mixture of CD4+ and CD8+ T-cells producing variable amount of interferon-gamma, interleukin-4 and interleukin-10. The two patients have had a periodontal disease whose anti-P. gingivalis immunoglobulin G titers were significantly elevated, and P. gingivalis was the one of the predominantly cultivable microorganisms. This is the first report of the successful establishment of P. gingivalis-specific T-cell lines from atherosclerotic patients.

Chlamydia pneumoniae infection and its association with coronary heart disease and cardiovascular risk factors in a sample South Asian population

Recent studies have suggested that a chronic infection with Chlamydia pneumoniae (C. pneumoniae) may be associated with the risk of developing coronary heart disease (CHD). A case control study was conducted to investigate the association between C. pneumoniae infection and coronary heart disease and coronary risk factors in a sample South Asian population. C. pneumoniae specific IgG antibody was measured by microimmunofluorescence. Among controls 56.6% were seropositive (> or =1/32) compared to 58.5% of acute myocardial infarction (AMI) patients (n=41, odds ratio 1.08, CI 0.37--3.12, P=0.93) and 73.3% of stable coronary heart disease (SCHD) patients (n=30, odds ratio 2.1, CI 0.63--7.19, P=0.27). The highest geometric mean titre of control subjects (n=30) was significantly lower (74.7) compared to AMI patients (101.5, P<0.05) and SCHD patients (138.6, P<0.05). Patients who were non-smokers had higher odds ratios for CHD than smokers when seropositive at IgG antibody titres of 1/32, 1/64 and 1/128, suggesting an association between smoking and C. pneumoniae infection. In patients with CHD there was a significant association between diabetes mellitus and seropositivity (P=0.008) in those over 50 years of age. Non-smoking CHD patients with high cholesterol/HDL-C ratio had a higher trend for seropositivity. Other risk factors (smoking, systolic and diastolic blood pressure, waist/hip ratio, triglycerides) showed no association when controlled for age. In the control group, smokers with high cholesterol/HDL-C ratio had a higher trend for seropositivity. These results do not provide strong support for the hypothesis that C. pneumoniae infection is a risk factor for clinical CHD in this South Asian population. Results suggest that C. pneumoniae infection may be linked to CHD through its interaction with some of the known risk factors such as blood lipids, diabetes and smoking.

Chlamydia pneumoniae does not increase atherosclerosis in the aortic root of apolipoprotein E-deficient mice

In epidemiological studies, an association between cardiovascular disease and Chlamydia pneumoniae (C pneumoniae) infection has been observed. Although C pneumoniae has been shown to be present in atherosclerotic lesions, a causal relationship between C pneumoniae infection and atherosclerosis has not been demonstrated. To study this question, we used 2 strains of apolipoprotein (apo) E-deficient mice. Eight-week-old mice on an FVB background that were maintained on either a low- or a high-fat diet were infected 3 times at 1-week intervals with C pneumoniae, and atherosclerotic lesions were measured in the aortic root at 10 weeks after the primary infection. In each of the diet groups, no difference in the extent of atherosclerosis could be observed between the C pneumoniae-infected and control animals. In further studies, 2 strains of apoE-deficient mice (FVB or C57BL/6J background) were infected 4 times at 3- to 4-week intervals, and the extent of atherosclerosis was analyzed 18 weeks later. The mice were kept on either a low- or a high-fat diet. The high-fat diet increased atherosclerosis, and a difference in atherosclerosis susceptibility between the mouse strains was observed. However, C pneumoniae infection did not influence lesion size in either mouse strain. On the other hand, C pneumoniae could not be demonstrated by polymerase chain reaction in any of the atherosclerotic lesions of the infected animals studied. A small decrease in serum cholesterol and triglyceride levels 3 days after the primary infection occurred, but after that no differences in serum lipid levels compared with those in noninfected animals were evident. In the myocardium of C pneumoniae-infected mice, no inflammatory signs could be observed. We conclude that under the experimental conditions used, C pneumoniae infection does not accelerate atherogenic changes in the aortic root of apoE-deficient mice.

Is C-reactive protein a useful predictor of outcome in peritoneal dialysis patients?

An elevated C-reactive protein (CRP) has recently been shown to be strongly predictive of mortality in hemodialysis patients. However, its predictive value in peritoneal dialysis (PD) patients has not been assessed. A cohort of 50 PD patients was followed prospectively for a 3-yr period, after initial determination of CRP. Patients with an elevated CRP (>6 mg/L; n = 29) had significantly reduced plasma prealbumin (0.36 +/- 0.02 versus 0.44 +/- 0.03 g/L; P: < 0.05), decreased total weekly creatinine clearance (C(Cr); 52.5 +/- 2.3 versus 63.1 +/- 3.2 L/1.73 m(2); P: < 0.01), and increased left ventricular thickness (1.24 +/- 0.05 versus 1.08 +/- 0.06 cm; P: < 0.05) at baseline compared with those who had a normal CRP (< or =6 mg/L; n = 21). Baseline CRP (log-transformed) correlated weakly with baseline Kt/V, C(Cr), and pre-albumin. With the use of a multivariate Cox's proportional hazards model to adjust for potential confounding factors, an elevated CRP was predictive of myocardial infarction (adjusted hazard ratio, 4.8; 95% confidence interval [CI], 1.0 to 23; P: = 0.048) and tended to be predictive of fatal myocardial infarction (adjusted hazard ratio, 6.0; 95% CI, 0.8 to 43; P: = 0.07). However, CRP was not significantly associated with all-cause mortality (adjusted hazard ratio, 2.1; 95% CI,0.8 to 5.4; P: = 0.15). In conclusion, CRP elevation occurs in a substantial proportion of PD patients and is independently predictive of future myocardial infarction. Such patients may warrant closer monitoring and attention to modifiable cardiovascular risk factors.

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.

The association of infection and coronary artery disease: an update

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