Can degenerative aortic valve stenosis be related to persistent Chlamydia pneumoniae infection?

Is the degeneration of aortic valve bioprostheses similar to that of native aortic valves? Insights into valvular pathology

Aortic stenosis (AS) is the most common valvular disease requiring valve replacement with a prevalence of 2-4% in adults greater than or equal to 65 years of age. There is increasing evidence that AS is an active inflammatory process that is highly regulated, displaying multiple hallmarks of atherosclerosis. Clinically, the definite therapy of advanced AS is prosthetic valve replacement. Herein, bioprosthetic tissue valves (BPs) possess superior thromboresistant and hemodynamic properties compared with mechanical valves. However, cusp degeneration and calcification also limit their long-term outcome. The pathogenesis of BP calcification as well as that of native valves is still poorly understood. Recent studies suggest a similar valvular pathology, that underlies both types of valvular degeneration, but also an even more important role of inflammatory and repair processes in the case of BP degeneration.

Presence of Chlamydophila pneumoniae DNA but not mRNA in stenotic aortic heart valves

BACKGROUND

The pathogenesis of aortic valve stenosis may involve inflammation and we have previously demonstrated Chlamydophila pneumoniae (C. pneumoniae) DNA in stenotic aortic heart valves. Dissemination of these bacteria is probably mediated by alveolar macrophages. Bacterial DNA alone does not indicate whether the bacteria are viable and replicating. This study aimed to investigate the presence of C. pneumoniae mRNA, a marker of replicating bacteria, and C. pneumoniae DNA in stenotic aortic valves and the prevalence of C. pneumoniae in peripheral blood mononuclear cells (PBMC).

METHODS

DNA was extracted from heart valves and PBMC and mRNA from heart valves from 76 patients undergoing aortic valve replacement surgery. C. pneumoniae DNA and mRNA were measured by real-time PCR targeting the ompA gene.

RESULTS

C. pneumoniae DNA was demonstrated in 22% of heart valves and in 5% of PBMC. C. pneumoniae mRNA was not detected in any valve. Patients positive for C. pneumoniae in the valve underwent coronary artery by-pass grafting more often (p=0.01) and suffered from angina pectoris (p=0.02) and arterial hypertension (p=0.03) more often than patients negative for C. pneumoniae in the valve.

CONCLUSIONS

These findings support a role for C. pneumoniae in the pathogenesis of aortic valve stenosis and indicate that the bacteria disseminate from the respiratory tract long before the patients were in need of surgery and that the valve infection thereafter entered into a persistent and non-replicative state. Moreover, patients positive for C. pneumoniae in the valve more often needed by-pass grafting because of more advanced coronary disease.

Established and emerging vascular risk factors and the development of aortic stenosis: an opportunity for prevention?

BACKGROUND

Aortic stenosis (AS) is the commonest valvular heart disease in the developed world. It is becoming increasingly accepted that the pathogenesis of AS and of its preceding abnormalities, aortic valve sclerosis (AVS) and aortic valve calcification (AVC), shares many characteristics with the atherosclerotic process.

OBJECTIVE

To assess the contribution of established and emerging vascular risk factors in the development of AS and to evaluate the potential of pharmacological intervention to modify the natural history of AS.

METHODS

We reviewed the epidemiological data that link AS and atherosclerosis and studies of vasculoprotective agents in patients with AS.

RESULTS/CONCLUSIONS

AS, AVS and AVC share many common risk factors with atherosclerosis and are possible markers of preclinical vascular disease. Statins appear to delay the progression of AS. However, more studies are needed before introducing such pharmacologic treatment for AS. The future may point towards targeted prevention of AS.

Aortic valve stenosis: an active atheroinflammatory process

PURPOSE OF REVIEW

To summarize the current understanding of the pathobiology of aortic valve stenosis and portray the major advances in this field.

RECENT FINDINGS

Stenotic aortic valves are characterized by atherosclerosis-like lesions, consisting of activated inflammatory cells, including T lymphocytes, macrophages, and mast cells, and of lipid deposits, calcific nodules, and bone tissue. Active mediators of calcification and cells with osteoblast-like activity are present in diseased valves. Extracellular matrix remodeling, including collagen synthesis and elastin degradation by matrix metalloproteinases and cathepsins, contributes to leaflet stiffening. In experimental animals, hypercholesterolemia induces calcification and bone formation in aortic valves, which can be inhibited by statin treatment. The potential of statins to retard progression of aortic valve stenosis has also been recognized in clinical studies; however, further prospective trials are needed. Angiotensin II-forming enzymes are upregulated in stenotic valves. Angiotensin II may participate in profibrotic progression of aortic valve stenosis and may serve as a possible therapeutic target.

SUMMARY

Recent findings regarding the interaction of inflammatory cells, lipids, mediators of calcification, and renin-angiotensin system in stenotic valves support the current opinion of aortic valve stenosis being an actively regulated disease, potentially amenable to targeted molecular therapy. Evidence from prospective clinical studies is eagerly awaited.

Degeneration of native and tissue prosthetic valve in aortic position: do statins play an effective role in prevention?

Degenerative aortic valve stenosis is a common disease in western countries. When it becomes severe, it confers significant morbidity and mortality. Aortic stenosis has been recognized as a complex inflammatory and highly regulated process with histological and immunochemical similarities with the process of atherosclerosis. Hypertension, smoking and diabetes mellitus have consistently been linked to the development of aortic stenosis. Endothelial injury or other processes that contribute to coronary disease may play a role in calcific aortic stenosis. Several observational studies suggests that the key factors of aortic stenosis are lipoproteins and that medical therapies with cholesterol lowering drugs may retard its progression. Similarly, it has been suggested that the process of degeneration of the tissue heart valve has been associated with the same risk factors of atherosclerosis and shares many histological and molecular characteristics. Assuming all this concept, and evaluating the results of a retrospective study it has been suggested to use statin also as medical therapy able to prevent tissue valve degeneration. Randomized controlled clinical trials will be needed to demonstrate the role of lipid intervention to prevent the progression of aortic stenosis and the degeneration of tissue heart valves.

Chlamydia pneumoniae in foci of "early" calcification of the tunica media in arteriosclerotic arteries: an incidental presence?

Only a few previous works investigated the involvement of Chlamydia pneumoniae (Chlamydophila pneumoniae) in arterial calcification. The present study investigated a possible association between C. pneumoniae and medial calcification. Carotid artery segments obtained by endarterectomy from 60 patients were examined by PCR and immunohistochemistry to identify the presence of C. pneumoniae. Arterial specimens showing double-positive (n = 17), double-negative (n = 22), and single-positive results (n = 21) were further analyzed by a combination of histology, immunohistochemistry, and electron microscopy. Medial calcification occurred in 10 of 17 (58.8%) C. pneumoniae double-positive arterial specimens, but no medial calcification was observed in any of 22 C. pneumoniae double-negative arterial specimens. Electron microscopy indicated C. pneumoniae in smooth muscle cells (SMCs) in foci of medial calcification. Medial SMCs showing damage to the cytoplasm and basement membrane contained the structures with the appearance of elementary, reticulate, and aberrant bodies of C. pneumoniae. The presence of C. pneumoniae in SMCs was confirmed by electron-microscopic immunocytochemistry. In the extracellular matrix, calcification was observed in C. pneumoniae aberrant bodies that exited the SMCs. The findings offer a new hypothesis of arterial calcification: they suggest that C. pneumoniae infection of medial SMCs may be associated with the pathophysiological events of arteriosclerotic calcification of the tunica media.

Density of Chlamydia pneumoniae is increased in fibrotic and calcified areas of degenerative aortic stenosis

BACKGROUND

The process of aortic degeneration associated with calcified aortic stenosis shares many similarities with coronary artery atherosclerosis. Inflammation and infection are involved in both diseases. Chlamydia pneumoniae has been identified in atherosclerotic plaques. However, the studies about the presence of C. pneumoniae in degenerative aortic stenotic valves are not conclusive.

OBJECTIVE

We investigated whether an association exists between the density of C. pneumoniae and fibrosis or calcification in aortic stenosis.

DESIGN

Autopsy and surgical specimens were divided into 3 groups: Normal, 11 normal autopsy valves Atherosclerosis, 10 autopsy valves from patients with systemic atherosclerosis and no aortic stenosis and Aortic stenosis, 14 surgical specimens of aortic valves replaced due to aortic stenosis.

SETTING

Heart Institute (InCor), University of São Paulo Medical School.

PATIENTS

Aortic valves from patients aged 52+/-16 years, 69+/-9 years, and 71+/-8 years.

INTERVENTION

Specimens were evaluated by immunohistochemical technique (to detect C. pneumoniae antigens), in situ hybridization, and electron microscopy (to quantify the density of C. pneumoniae in the valves).

MEASUREMENTS

The aortic stenosis group was analyzed according to 3 subregions: aortic stenosis-preserved, peripheral preserved regions; aortic stenosis-fibrosis, peri-calcified fibrotic tissue; and aortic stenosis-calcification, calcified nodules.

RESULTS

The median values of C. pneumoniae antigens were 0.09, 0.30, 0.18, 1.33, and 3.3 in groups Normal, Atherosclerosis, Aortic stenosis-preserved, Aortic stenosis-fibrosis, and Aortic stenosis-calcification, respectively. The amount of C. pneumoniae was greater in the Atherosclerosis and Aortic stenosis-calcification groups than in the Normal group (P<0.05). C. pneumoniae was greater in the Aortic stenosis group in the calcified and fibrotic regions than in preserved region (P<0.05).

CONCLUSION

An association was found between the higher density of C. pneumoniae and fibrosis/calcification in stenotic aortic valves.

Atherosclerosis-like lesions of the aortic valve are common in adults of all ages: a necropsy study

OBJECTIVE

To determine the presence and size of atherosclerosis-like lesions in aortic valves of unselected adults of all ages.

DESIGN

Necropsy study.

SETTING

Departments of Forensic Medicine and Pathology at the University of Oulu and the Oulu University Hospital in Finland.

SUBJECTS

48 consecutive unselected adult subjects (15 subjects aged 20-40 years, 17 aged 41-60, and 16 aged >or= 61) undergoing necropsy.

MAIN OUTCOME MEASURES

Detection of the presence of atherosclerosis-like lesions and mineralisation in aortic valves, and morphometrical measurement of the size of lesions.

RESULTS

None of the necropsy subjects had aortic stenosis and only two subjects had macroscopic calcification of the aortic valve. Of 48 subjects, however, 45 had an atherosclerosis-like subendothelial thickening above the elastic lamina on the aortic side of at least one of the valve leaflets. Of 15 young subjects aged 20-40 years, eight had a lesion in the right coronary cusp of the aortic valve and 12 had a lesion in at least one of the three aortic valve leaflets. Of 17 middle aged subjects, 16 had an early lesion in the right coronary cusp and all had a lesion in at least one of the valve leaflets. In the oldest age group, all 16 subjects had a lesion in every valve leaflet. The mean lesion area in the three valve leaflets varied from 0.1-0.2 mm(2) in young subjects, 0.5-0.8 mm(2) in middle aged, and 1.3-2.3 mm(2) in elderly subjects (p < 0.001). Microscopic calcification in the right coronary cusp of the aortic valve was observed in 12 of 17 middle aged and 14 of 16 elderly subjects but only in one young subject.

CONCLUSIONS

Atherosclerosis-like lesions in the aortic valve are prevalent in adults of all age groups, including young subjects aged 20-40 years, suggesting that the disease process leading to aortic stenosis is common, often beginning in early adulthood.

Inflammation, infection, and aortic valve sclerosis

Atherosclerosis-related mechanisms, including inflammation and possibly infection, are likely to be involved in the pathogenesis of calcific aortic valve disease. The purpose of this study was to examine whether systemic inflammatory markers and Chlamydia pneumoniae seropositivity are associated with aortic valve sclerosis (AVS) in a sample of the general population. Transesophageal echocardiography was performed in 381 subjects (median age: 67 years, range: 51-101; 52% men), a sample of the adult population in Olmsted County, Minnesota. The associations between systemic inflammatory markers (blood counts, including white blood cells differential counts, fibrinogen, and high-sensitivity C-reactive protein [hs-CRP]), C. pneumoniae immunoglobulin G (IgG) antibody titers, and AVS were examined. AVS was present in 140 subjects (37% of the population). After adjustment for age, sex, and smoking status: (1). hs-CRP was associated with AVS (odds ratio: 1.20 per two-fold increase in hs-CRP; 95% confidence interval: 1.01-1.43; P = 0.04) but this association was not significant after adjustment for additional risk factors for AVS, including body mass index (P = 0.52). (2). Blood counts and fibrinogen were not associated with AVS (P-values >0.30). (3). C. pneumoniae IgG antibody titers (low [1:16-1:32], intermediate [1:64-1:128], or high [>or=1:256] titers, compared with titers <1:16) were not associated with AVS (P = 0.21). In conclusion, hs-CRP is weakly associated with AVS, an association that is not independent of other AVS risk factors. Blood counts, fibrinogen, and C. pneumoniae seropositivity are not associated with AVS. These findings suggest that other non-inflammatory non-infectious mechanisms are likely to have a role in the pathogenesis of calcific aortic valve disease.

Role of oral bacterial flora in calcific aortic stenosis: an animal model

BACKGROUND

Calcific aortic stenosis is a major public health problem in the United States. The mechanism of calcification remains unclear. The hypothesis that low grade chronic or recurrent bacterial endocarditis with specific calcifiable bacteria is a cause of calcification of the aortic valves was investigated using an animal model. Such bacteria are typically present as part of the normal human oral flora.

METHODS

Forty New Zealand white rabbits were divided into four groups: group 1, control (1 ml of normal saline); group 2, Corynebacterium matruchotti 100,000 colonies; group 3, Streptococcus sanguis II 10 colonies; and group 4, C matruchotti 100,000 colonies plus S sanguis II 10 colonies. Animals were inoculated with bacteria through a flexible catheter placed through the aortic valve through a right carotid cut down. Inoculations were repeated every 3 days the first 2 weeks and then twice a week thereafter. At postmortem examination the aortic valves were harvested, embedded in paraffin, and stained with von Kossa stain. They were also examined by scanning and transmission electron micrography.

RESULTS

Group 4 had 93.3% large calcifications (confluent calcium densities that are easily recognized with minimal magnification) and 6.6% small microcalcifications (dustlike microscopic particles requiring a compound microscope to appreciate) of the aortic valves. Group 3 exhibited large calcification in 20% and small in 40% of the aortic valves. Group 1 and group 2 had no evidence of calcification.

CONCLUSIONS

These results suggest that recurrent low-grade endocarditis from calcifying oral bacteria, particularly when occurring with synergistic strains, may be one cause of calcific aortic stenosis.

Diagnosis of aortic stenosis in the elderly: role of echocardiography

Doppler echocardiography provides accurate hemodynamic information for the diagnosis, assessment and follow-up of patients with aortic stenosis, making diagnostic cardiac catheterization redundant in most cases. Considering the rapid growth of the aging population and the high incidence of aortic stenosis, as the most common valvular heart disease in the age group, the authors have described the utility of the Doppler technique with a brief discussion of the clinical evaluation of these patients. Close observation of patients with asymptomatic aortic stenosis has been emphasized. Decision-making about the appropriate timing for aortic valve replacement is of immense clinical significance, which may be facilitated and achieved by the periodic follow-up and the use of this noninvasive method. Following a comprehensive echo-Doppler evaluation, the patient would only need coronary arteriography prior to surgery. The utility of hemodynamic and anatomic information by echocardiography in this type of surgery is emphasized.

Failure to detect Chlamydia pneumoniae in senile calcific aortic stenosis or calcified congenital bicuspid aortic valve by immunofluorescence, polymerase chain reaction and electron microscopy

INTRODUCTION

Chlamydia pneumoniae has been identified in arterial atherosclerosis. Aortic valves affected by senile calcific aortic stenosis (SCAS) or calcification of a congenital bicuspid valve (CCBAV) may have interior environments similar to atherosclerosis. This study aimed to detect C. pneumoniae within either SCAS or CCBAV.

METHODS

60 valves showing either SCAS (n=36) or CCABV (n=22) and control valves (n=2) were studied for the presence of C. pneumoniae by the following three techniques: (1) indirect immunofluorescence (IF) was performed on 36 SCAS valves, 22 CCBAV valves and 2 control aortic valves using a HEp-2 cell line infected with C. pneumoniae as a positive control. Negative controls comprised duplicate slides of the same valves with omission of the primary antibody step. A section of human stomach was also used as a negative control. A semiquantitative scoring method was used to grade positive IF staining. (2) Polymerase chain reaction (PCR) was performed on 30 SCAS valves, 20 CCBAV valves and 1 control valve using C. pneumoniae as a positive control and negative controls comprised a Ureaplasma sp. and human DNA from peripheral blood mononuclear cells. (3) Electron microscopy (EM) was performed upon 13 SCAS, 8 CCBAV and 2 control valves.

RESULTS

All three methods failed to detect the presence of C. pneumoniae in any of the 60 aortic valves examined. False positive IF staining was encountered in 81% of test valves and in 76% of negative control valve sections (positive in calcified material due to nonspecific binding of FITC-conjugated secondary antibody). No staining was observed in the negative control stomach sections.

CONCLUSIONS

This study failed to detect C. pneumoniae within aortic valves showing SCAS or CCBAV. Studies using IF alone to detect C. pneumoniae in calcified tissues should be interpreted with caution, since nonspecific binding of FITC-conjugated secondary antibody by calcium in the cusps may be misinterpreted as evidence of Chlamydia. The use of appropriate controls and ancillary methods for the identification of C. pneumoniae are important in this regard.

Monocyte/macrophage regulation of vascular calcification in vitro

BACKGROUND

Calcification is a common complication of atherosclerosis and other chronic inflammatory processes that involves infiltration of monocytes and accumulation of macrophages.

METHODS AND RESULTS

To determine whether these cells modulate vascular calcification in vitro, calcifying vascular cells (CVCs), a subpopulation of osteoblast-like cells derived from the artery wall, were cocultured with human peripheral blood monocytes for 5 days. Results showed that alkaline phosphatase (ALP) activity, a marker of osteoblastic differentiation, was significantly greater in cocultures than in cultures of CVCs or monocytes alone. Both ALP activity and matrix mineralization increased in proportion to the number of monocytes added. Activation of monocyte/macrophages (M/Ms) by oxidized LDL further increased ALP activity in cocultures. However, neither conditioned medium from oxidized-LDL-activated M/Ms or transwell coculture had this effect on CVCs, which suggests a need for cell-to-cell contact. In contrast, conditioned medium from lipopolysaccharide-activated M/Ms increased ALP activity of CVCs. ELISA showed that lipopolysaccharide-activated M/Ms secreted tumor necrosis factor-alpha, and neutralizing antibody to tumor necrosis factor-alpha attenuated the induction of ALP activity by the conditioned media.

CONCLUSIONS

These results suggest that M/Ms enhance in vitro vascular calcification via 2 independent mechanisms: cell-cell interaction and production of soluble factors such as tumor necrosis factor-alpha.

Effect of hydroxymethylglutaryl coenzyme a reductase inhibitors on the progression of calcific aortic stenosis

BACKGROUND

Recent studies have supported the hypothesis that calcific aortic stenosis is the product of an active inflammatory process, with similarities to atherosclerosis. We sought to determine whether therapy with hydroxymethylglutaryl coenzyme A reductase inhibitors (statins) might slow the progression of aortic stenosis.

METHODS AND RESULTS

A retrospective study of 174 patients (mean age 68+/-12 years) with mild to moderate calcific aortic stenosis was conducted. Patients required normal left ventricular function, </=2+ aortic regurgitation, and >/=2 echocardiograms performed at least 12 months apart. Fifty-seven patients (33%) received treatment with a statin; the remaining 117 (67%) did not. The statin group was older and had a higher prevalence of hypertension, diabetes mellitus, and coronary disease. During a mean follow-up of 21 months, patients treated with statin had a smaller increase in peak and mean gradient and a smaller decrease in aortic valve area. When annualized, the decrease in aortic valve area for the nonstatin group was 0.11+/-0.18 cm(2) compared with 0.06+/-0.16 cm(2) for those treated with a statin (P=0.03). In multivariate analysis, statin usage was a significant independent predictor of a smaller decrease in valve area (P=0.01) and a lesser increase in peak gradient (P=0.02).

CONCLUSIONS

Statin-treated patients, despite a higher risk profile for progression, had reduced aortic stenosis progression compared with those not treated with a statin. These data provide justification for a prospective randomized trial to substantiate whether statin therapy slows the progression of aortic stenosis.

C-reactive protein is increased in patients with degenerative aortic valvular stenosis

OBJECTIVES

The goal of this study was to assess the presence of systemic inflammation in degenerative aortic valvular stenosis.

BACKGROUND

Local inflammatory changes, resembling those observed in atherosclerosis, have been recently reported in degenerative aortic valvular stenosis. It is presently unknown whether systemic signs of inflammation, similar to those observed in atherosclerosis, may be present in this disorder.

METHODS

C-reactive protein (CRP) was measured by enzyme immunoassay in 141 subjects: 62 with trileaflet degenerative valvular aortic stenosis and 79 volunteers with similar demographic and clinical characteristics. IgG antibodies against Helicobacter pylori (enzyme-linked immunosorbant assay) and Chlamydia pneumoniae (microimmunofluorescence assay) were also measured.

RESULTS

C-reactive protein levels (mg/dl, mean +/- SD) were 0.848 +/- 1.42 in patients and 0.394 +/- 0.50 in controls (p = 0.0001, Mann-Whitney U test). Seroprevalence of H. pylori was 68.7% in patients and 79.7% in controls (p = NS), whereas seroprevalence of C. pneumoniae infection was higher in patients than it was in controls (59.7% vs. 33%, p = 0.003; chi-square test). After adjustment for various covariates in multiple logistic regression, the odds ratio for degenerative aortic stenosis was 3.41 for C. pneumoniae infection (95% confidence intervals [CI]: 1.60 to 7.30) and 2.76 for CRP (95% CI: 1.08 to 7.05). There was no significant difference in patients or controls in CRP levels according to the serostatus for C. pneumoniae.

CONCLUSIONS

Systemic signs of inflammation, similar to those found in atherosclerosis, are present in patients with degenerative aortic valve stenosis. They do not seem to be linked to C. pneumoniae or H. pylori infection.

The evolving relationship between Chlamydia pneumoniae and atherosclerosis

A body of evidence supports an association between Chlamydia pneumoniae and atherosclerosis. Recent prospective, seroepidemiologic studies have refined estimations of relative risk. Advances in diagnostic testing with the polymerase chain reaction have created a potential opportunity to screen for infected individuals. New insights into the pathogenesis of infection with C. pneumoniae have been reported, many of which are relevant to the development of atherosclerotic plaque. Clinical trials have now been initiated and should provide guidance as to the utility of antibiotics in the treatment or prevention of coronary artery disease.

Predictors of cerebrovascular events and death among patients with valvular heart disease: A population-based study

BACKGROUND AND PURPOSE

There is little population-based information on cerebrovascular events and survival among valvular heart disease patients. We used the Kaplan-Meier product-limit method and the Cox proportional hazards model to determine rates and predictors of cerebrovascular events and death among valve disease patients.

METHODS

This population-based historical cohort study in Olmsted County, Minnesota, reviewed residents with a first echocardiographic diagnosis of mitral stenosis (n=19), mitral regurgitation (n=528), aortic stenosis (n=140), and aortic regurgitation (n=106) between 1985 and 1992.

RESULTS

During 2694 person-years of follow-up, 98 patients developed cerebrovascular events and 356 died. Compared with expected numbers, these observations are significantly elevated, with standardized morbidity ratio of 3.2 (95% CI, 2.6 to 3.8) and 2. 5 (95% CI, 2.2 to 2.7), respectively. Independent predictors of cerebrovascular events were age, atrial fibrillation, and severe aortic stenosis. The risk ratio of severe aortic stenosis was 3.5 (95% CI, 1.4 to 8.6), with atrial fibrillation conferring greater risk at younger age. Predictors of death were age, sex, cerebrovascular events, ischemic heart disease, and congestive heart failure, the greatest risk being among those with both congestive heart failure and cerebrovascular events (risk ratio=8.8; 95% CI, 5. 8 to 13.4). Valve disease type and severity were not independent determinants of death.

CONCLUSIONS

The risk of cerebrovascular events and death among patients with valve disease remains high. Age, atrial fibrillation, and severe aortic stenosis are independent predictors of cerebrovascular events, and age, sex, cerebrovascular events, congestive heart failure, and ischemic heart disease are independent predictors of death in these patients.

Helicobacter pylori, Chlamydia pneumoniae, and cytomegalovirus: chronic infections and coronary heart disease

We conducted a MEDLINE search of the English-language literature from 1966-1999 on the association of chronic infections with Helicobacter pylori, Chlamydia pneumoniae, and cytomegalovirus (CMV) with coronary heart disease (CHD); additional literature was retrieved from references of selected articles. All human studies were included. Abstracts were excluded because of limited data. Chronic infections in CHD are speculated to be due to serum antibody concentrations of one or more of the three organisms. Data for H. pylori and CMV are difficult to interpret due to the confounding factor of childhood poverty and studies conducted in transplant recipients, respectively. Chlamydia pneumoniae data appear stronger with elevated IgG antibody titers (> or = 64) as a risk factor. Larger prospective studies are warranted to determine an association with CHD before universal prophylaxis or treatment of these chronic infections.

Genitourinary chlamydial infection: a reappraisal and hypothesis

Our understanding of genitourinary chlamydial infection and disease remains limited. That natural defences and/or apparently adequate treatments leave some patients with latent disease is suspected. There is, however, no consensus as to its nature. Furthermore, many patients, most obviously males, presenting with similar or identical symptoms and signs remain unexplained in microbiological terms; this in spite of many years of dedicated research endeavour. The recent trend towards an impasse has coincided with a growing acquaintance with the immunobiology and immunopathology of chlamydial infections. The time would seem to have arrived for a reappraisal of available clinical and laboratory observations. A hypothesis with research suggestions is presented for discussion.

Circulating Chlamydia pneumoniae DNA as a predictor of coronary artery disease

OBJECTIVE

To determine whether current vascular Chlamydia pneumoniae (CPn) infection as diagnosed by circulating CPn DNA is more common in subjects with coronary artery disease (CAD).

BACKGROUND

Serological, pathological and animal studies have associated CPn with CAD and preliminary trials suggest antibiotics may prevent adverse coronary events. C. pneumoniae is thought to disseminate systemically within macrophages. We therefore detected CPn DNA in blood to determine whether its presence was a predictor of CAD.

METHODS

One thousand, two hundred and five subjects attending for diagnostic and interventional coronary arteriography were recruited. The mononuclear cell layer and platelets were separated from collected blood and the polymerase chain reaction (PCR) was used to detect CPn DNA.

RESULTS

Circulating CPn DNA was found in 8.8% of 669 men with CAD compared with 2.9% of 135 men with normal coronary arteries (odds ratio [OR] 3.2, 95% confidence interval [CI] 1.1-8.9). In men with CAD, those with CPn DNA had higher mean platelet counts than those without CPn DNA. Monocyte counts and indirect fibrinogen levels were also raised but not significantly so. By contrast, no association of circulating CPn DNA and CAD was seen in women.

CONCLUSIONS

Circulating CPn DNA is a predictor of CAD in men. Unlike serology, it is a specific indicator of current infection and is a means of identifying subjects who may potentially benefit from antichlamydial therapy.

Factors leading to progression of valvular aortic stenosis

The rate of progression of aortic stenosis (AS) in adults is variable. To determine whether clinical or echocardiographic variables are associated with more rapid hemodynamic progression, we identified 91 AS patients (initial valve area < or = 2.0 cm2) with 2 technically adequate studies separated by > or = 6 months. From the first study, left ventricular dimensions and AS severity were measured by standard Doppler-echocardiographic methods. Each aortic valve was graded for severity of calcification and degree of restricted leaflet motion; the sum of these grades provided a severity index reflecting leaflet pathology. Clinical and electrocardiographic variables were abstracted from medical records. Mean age was 68 years (range 29 to 89) and 61 were women. Initial AS severity ranged from an aortic valve area of 0.6 to 2.0 cm2 (median 1.3 cm2). During a mean follow-up of 1.8 years the aortic valve area decreased 0.04 cm2/year. The patient group with more rapid progression (decrease in aortic valve area > or = 0.1 cm2/year) had a larger proportion of men (p <0.01) and patients with an elevated serum creatinine (p = 0.04), a higher left ventricular mass index (p = 0.01), and a higher severity index (p <0.001). Multivariable regression analysis identified the severity index (direct relation) and the initial aortic valve area (inverse relation) as the only independent variables associated with more rapid progression. In conclusion, the rate of AS progression, although highly variable, is more rapid when leaflet calcification is more marked.

Cogan's syndrome

Work originating in the 1940s led to the characterization of a rare, chronic inflammatory disorder with a unique predilection for the cornea and vestibuloauditory apparatus, now called Cogan's syndrome (CS) after the ophthalmologist who first described it. CS occurs primarily in young adults and typically presents with interstitial keratitis (IK) and Ménière's-like episodes developing within several months of each other. The inflammatory process may target other ocular sites, and the disease itself may be accompanied by aortitis or a Takayasu's-like or medium-sized vessel vasculitis. Morbidity in CS results from deafness and complications from cardiovascular disease. Most evidence suggests that the ocular and vestibuloauditory manifestations are not a consequence of vasculitis but rather mediated by other immunologic mechanisms, possibly organ-specific autoimmunity. The cornerstone of treatment in CS is corticosteroids, topically for IK and systemically for inner ear dysfunction. Early corticosteroid therapy appears to be critical for reversing hearing loss. Cochlear implants can partially restore auditory function and have been a salvation for patients who suffer from deafness as a result of permanent cochlear damage.

Is vasculitis a significant component of atherosclerosis?

Although atherosclerosis was linked to infections many decades ago, only recently there has been a renewed interest to study this association further. These research endeavors have provided a substantial amount of knowledge concerning the mechanisms that may link inflammation, immunity, and infections to the molecular and cellular events in the arterial wall leading to atherosclerotic lesions.