Distribution of Chlamydia pneumoniae infection in the athersclerotic carotid artery

Novel Therapeutic Approaches to Prevent Atherothrombotic Ischemic Stroke in Patients with Carotid Atherosclerosis

Atherothrombotic stroke represents approximately 20% of all ischemic strokes. It is caused by large-artery atherosclerosis, mostly in the internal carotid artery, and it is associated with a high risk of early recurrence. After an ischemic stroke, tissue plasminogen activator is used in clinical practice, although it is not possible in all patients. In severe clinical situations, such as high carotid stenosis (≥70%), revascularization by carotid endarterectomy or by stent placement is carried out to avoid recurrences. In stroke prevention, the pharmacological recommendations are based on antithrombotic, lipid-lowering, and antihypertensive therapy. Inflammation is a promising target in stroke prevention, particularly in ischemic strokes associated with atherosclerosis. However, the use of anti-inflammatory strategies has been scarcely studied. No clinical trials are clearly successful and most preclinical studies are focused on protection after a stroke. The present review describes novel therapies addressed to counteract inflammation in the prevention of the first-ever or recurrent stroke. The putative clinical use of broad-spectrum and specific anti-inflammatory drugs, such as monoclonal antibodies and microRNAs (miRNAs) as regulators of atherosclerosis, will be outlined. Further studies are necessary to ascertain which patients may benefit from anti-inflammatory agents and how.

Biomarkers of non-communicable chronic disease: an update on contemporary methods

Chronic diseases constitute a major global burden with significant impact on health systems, economies, and quality of life. Chronic diseases include a broad range of diseases that can be communicable or non-communicable. Chronic diseases are often associated with modifications of normal physiological levels of various analytes that are routinely measured in serum and other body fluids, as well as pathological findings, such as chronic inflammation, oxidative stress, and mitochondrial dysfunction. Identification of at-risk populations, early diagnosis, and prediction of prognosis play a major role in preventing or reducing the burden of chronic diseases. Biomarkers are tools that are used by health professionals to aid in the identification and management of chronic diseases. Biomarkers can be diagnostic, predictive, or prognostic. Several individual or grouped biomarkers have been used successfully in the diagnosis and prediction of certain chronic diseases, however, it is generally accepted that a more sophisticated approach to link and interpret various biomarkers involved in chronic disease is necessary to improve our current procedures. In order to ensure a comprehensive and unbiased coverage of the literature, first a primary frame of the manuscript (title, headings and subheadings) was drafted by the authors working on this paper. Second, based on the components drafted in the preliminary skeleton a comprehensive search of the literature was performed using the PubMed and Google Scholar search engines. Multiple keywords related to the topic were used. Out of screened papers, only 190 papers, which are the most relevant, and recent articles were selected to cover the topic in relation to etiological mechanisms of different chronic diseases, the most recently used biomarkers of chronic diseases and finally the advances in the applications of multivariate biomarkers of chronic diseases as statistical and clinically applied tool for the early diagnosis of chronic diseases was discussed. Recently, multivariate biomarkers analysis approach has been employed with promising prospect. A brief discussion of the multivariate approach for the early diagnosis of the most common chronic diseases was highlighted in this review. The use of diagnostic algorithms might show the way for novel criteria and enhanced diagnostic effectiveness inpatients with one or numerous non-communicable chronic diseases. The search for new relevant biomarkers for the better diagnosis of patients with non-communicable chronic diseases according to the risk of progression, sickness, and fatality is ongoing. It is important to determine whether the newly identified biomarkers are purely associations or real biomarkers of underlying pathophysiological processes. Use of multivariate analysis could be of great importance in this regard.

Inflammation and Stroke Risk: A New Target for Prevention

New therapeutic approaches are required for secondary prevention of residual vascular risk after stroke. Diverse sources of evidence support a causal role for inflammation in the pathogenesis of stroke. Randomized controlled trials of anti-inflammatory agents have reported benefit for secondary prevention in patients with coronary disease. We review the data from observational studies supporting a role for inflammation in pathogenesis of stroke, overview randomized controlled trials of anti-inflammatory therapy in cardiac disease and discuss the potential implications for stroke prevention therapy.

A review of microscopy-based evidence for the association of Propionibacterium acnes biofilms in degenerative disc disease and other diseased human tissue

PURPOSE

Recent research shows an increasing recognition that organisms not traditionally considered infectious in nature contribute to disease processes. Propionibacterium acnes (P. acnes) is a gram-positive, aerotolerant anaerobe prevalent in the sebaceous gland-rich areas of the human skin. A ubiquitous slow-growing organism with the capacity to form biofilm, P. acnes, recognized for its role in acne vulgaris and medical device-related infections, is now also linked to a number of other human diseases. While bacterial culture and molecular techniques are used to investigate the involvement of P. acnes in such diseases, definitive demonstration of P. acnes infection requires a technique (or techniques) sensitive to the presence of biofilms and insensitive to the presence of potential contamination. Fortunately, there are imaging techniques meeting these criteria, in particular, fluorescence in situ hybridization and immunofluorescence coupled with confocal laser scanning microscopy, as well as immunohistochemistry.

METHODS

Our literature review considers a range of microscopy-based studies that provides definitive evidence of P. acnes colonization within tissue from a number of human diseases (acne vulgaris, degenerative disc and prostate disease and atherosclerosis), some of which are currently not considered to have an infectious etiology.

RESULTS/CONCLUSION

We conclude that P. acnes is an opportunistic pathogen with a likely underestimated role in the development of various human diseases associated with significant morbidity and, in some cases, mortality. As such, these findings offer the potential for new studies aimed at understanding the pathological mechanisms driving the observed disease associations, as well as novel diagnostic strategies and treatment strategies, particularly for degenerative disc disease. These slides can be retrieved under Electronic Supplementary Material.

Chlamydia trachomatis Seroprevalence and Ultrasound-Diagnosed Uterine Fibroids in a Large Population of Young African-American Women

Reproductive tract infections have long been hypothesized to increase the risk of uterine fibroids. Few studies have been conducted, even for the common infection genital Chlamydia trachomatis (gCT), and only with self-reported gCT data. Our investigation used micro-immunofluorescence serology for gCT to characterize past exposure. We used cross-sectional enrollment data from a prospective fibroid study carried out in the Detroit, Michigan, area; ultrasound examinations systematically screened for fibroids. Participants were African-American women aged 23-34 years (recruited in 2010-2012). Age- and multivariable-adjusted logistic regression models were used to estimate odds ratios. A total of 1,587 women (94% of participants) had unequivocal gCT serology results; 22% had fibroids. Those who were seropositive for gCT were less likely to have fibroids (age-adjusted odds ratio = 0.68, 95% confidence interval: 0.54, 0.87; multivariable-adjusted odds ratio = 0.80, 95% confidence interval: 0.62, 1.03). Inverse associations were similar across categories of fibroid size, number, and total volume. Participant groups likely to have had multiple or severe infections (multiple serovar groups, more sex partners, clinically diagnosed chlamydia) all showed statistically significantly reduced odds of fibroids. A protective association of gCT with fibroids was unexpected but plausible. gCT infection might increase immune surveillance and eliminate early lesions. Further investigation on the relationship between fibroid development and reproductive tract infections is needed.

Is Chlamydia Pneumoniae a Risk Factor for Peripheral Atherosclerosis?

Seroepidemiological studies have shown a relationship between Chlamydia pneumoniae and coronary atherosclerosis. It is not clear whether Chlamydia pneumoniae is also a risk factor for peripheral atherosclerosis. Chlamydia pneumoniae antibodies were measured by a microimmunofluorescence method in 75 patients who underwent surgery for peripheral atherosclerosis, and the seroprevalence was compared with that in the normal population. Chlamydia pneumoniae immunoglobulin-G seroprevalence was 80% in the study group vs. 40% in controls. More foam cells were noted on light microscopy in atherosclerotic plaques from the infected patients. The 60 infected patients were divided into: group A ( n = 35) given both anti-chlamydial and antiplatelet agents for 1 year; and group B ( n = 25) given antiplatelet therapy only. The groups were compared on the basis of clinical findings, ankle-brachial index, and antibody titers. Decreasing Chlamydia pneumoniae immunoglobulin-G seroprevalence in group A correlated significantly with increasing ankle-brachial index and improvement in clinical findings. It was concluded that Chlamydia pneumoniae may be a risk factor for peripheral atherosclerosis.

Chlamydia pneumoniae Infection and Inflammatory Diseases

Chlamydia pneumoniae, an obligate intracellular bacterial pathogen, has long been investigated as a potential developmental or exacerbating factor in various pathologies. Its unique lifestyle and ability to disseminate throughout the host while persisting in relative safety from the immune response has placed this obligate intracellular pathogen in the crosshairs as a potentially mitigating factor in chronic inflammatory diseases. Many animal model and human correlative studies have been performed to confirm or deny a role for C. pneumoniae infection in these disorders. In some cases, antibiotic clinical trials were conducted to prove a link between bacterial infections and atherosclerosis. In this review, we detail the latest information regarding the potential role that C. pneumoniae infection may have in chronic inflammatory diseases.

C-reactive protein, cardiovascular disease and stroke: new roles for an old biomarker

Stroke is a leading cause of death and disability worldwide. A new and exciting development in cardiovascular disease is the recognition of the role of inflammation in atherosclerosis. C-reactive protein, an acute phase reactant, appears to be a promising biomarker for cardiovascular disease, possibly more predictive than cholesterol and also may play an etiological role. C-reactive protein also appears to be predictive of stroke risk, although less so in the elderly. Although the number of studies on stroke (apart from cardiovascular disease) is limited, there is a significant graded increase in stroke risk within the low-to-high normal range of C-reactive protein. C-reactive protein is readily amenable to treatment with anti-inflammatory drugs, such as aspirin and statins. New and increasingly available high-sensitivity assays may make C-reactive protein a standard screening tool for cardiovascular disease.

Chlamydia pneumoniae infection acts as an endothelial stressor with the potential to initiate the earliest heat shock protein 60-dependent inflammatory stage of atherosclerosis

We identified increased expression and redistribution of the intracellular protein 60-kDa human heat shock protein (hHSP60) (HSPD1) to the cell surface in human endothelial cells subjected to classical atherosclerosis risk factors and subsequent immunologic cross-reactivity against this highly conserved molecule, as key events occurring early in the process of atherosclerosis. The present study aimed at investigating the role of infectious pathogens as stress factors for vascular endothelial cells and, as such, contributors to early atherosclerotic lesion formation. Using primary donor-matched arterial and venous human endothelial cells, we show that infection with Chlamydia pneumoniae leads to marked upregulation and surface expression of hHSP60 and adhesion molecules. Moreover, we provide evidence for an increased susceptibility of arterial endothelial cells for redistribution of hHSP60 to the cellular membrane in response to C. pneumoniae infection as compared to autologous venous endothelial cells. We also show that oxidative stress has a central role to play in endothelial cell activation in response to chlamydial infection. These data provide evidence for a role of C. pneumoniae as a potent primary endothelial stressor for arterial endothelial cells leading to enrichment of hHSP60 on the cellular membrane and, as such, a potential initiator of atherosclerosis.

Chlamydia pneumoniae induces a pro-inflammatory phenotype in murine vascular smooth muscle cells independently of elevating reactive oxygen species

  NADPH oxidases (Nox) are reactive oxygen species (ROS)-generating enzymes that play important physiological roles in host defence and redox signalling. However, Nox activity is upregulated in the vascular wall during atherosclerosis and contributes to plaque formation by promoting oxidative stress and inflammation.   The bacterium Chlamydia pneumoniae has been detected in vascular smooth muscle cells (VSMC) of human atheroma. We hypothesized that C. pneumoniae infection of VSMC causes Nox activation, which initially limits infection but ultimately causes oxidative stress, activation of pro-inflammatory pathways and an atherogenic phenotype.   Chlamydia pneumoniae infection of mouse cultured VSMC significantly increased ROS production by twofold but did not upregulate mRNA expression of Nox1 or Nox4. Chlamydia pneumoniae did increase Nox2 mRNA levels significantly by threefold, but this did not translate to elevated Nox2 protein expression.   The Nox inhibitor gp91ds-tat had no effect on C. pneumoniae-induced ROS production. In contrast, apocynin significantly reduced ROS levels by 75% in C. pneumoniae-infected VSMC, an effect most likely attributable to its direct anti-oxidant action.   Although apocynin had no effect on C. pneumoniae-induced expression of inflammatory markers, bacteria recovered from apocynin-treated VSMC displayed a higher degree of infectivity in HEp-2 cells.   In conclusion, C. pneumoniae infection increases ROS production in VSMC independently of Nox activity. Although elevated ROS production appears to serve a protective role by limiting the spread of infection, we speculate that this response will be detrimental over the long term by causing oxidative stress and a smouldering inflammatory response by maintaining C. pneumoniae persistence within the cell.

Chlamydophila pneumoniae infection leads to smooth muscle cell proliferation and thickening in the coronary artery without contributions from a host immune response

Chlamydophila pneumonia (C. pneumonia) infection has been associated with the progression of atherosclerosis. It remains unclear, however, whether C. pneumoniae in the absence of an immune response can alone initiate atherogenic events within a complex vessel environment. Left anterior descending coronary arteries isolated from porcine hearts were dissected and placed in culture medium for 72 hours before infection with C. pneumoniae. C. pneumoniae replicated within the arterial wall for the duration of the experiment (up to 10 days). A significant increase in chlamydial-HSP60 protein expression from day 2 to 10 post-infection (pi) indicated the presence of metabolically active C. pneumonia within infected vessels. Significant arterial thickening in infected coronary segments was observed by a considerable decrease in the ratio of lumen to total vessel area (48 +/- 3% at day 4 pi versus 23 +/- 3% at day 10 pi) and a significant increase in the ratio of media to luminal area (113 +/- 16% at day 4 pi versus 365 +/- 65% at day 10 pi). Structural changes were accompanied by an up-regulation of host HSP60 and proliferating cell nuclear antigen expression levels. Immunohistochemical staining confirmed proliferating cell nuclear antigen expression to be primarily localized within smooth muscle cells of the medial area. These results demonstrate that C. pneumoniae infection can stimulate arterial thickening in a complex vessel environment without the presence of a host immune response and further supports the involvement of HSP60 in this action.

Association between Histoplasma exposure and stroke

BACKGROUND AND PURPOSE

The rate of cerebrovascular events within the stroke belt, a geographic area defined in the Southeastern United States, exceeds that of the rest of the nation. Despite evaluation of multiple risk factors for this disparity, specific causes for the stroke belt have not been elucidated. More than 45 years ago, the US Public Health Service and US Navy cooperative skin-testing program (1958-1965) documented adolescent exposure to Histoplasma capsulatum. Our purpose was to evaluate the association between exposure to Histoplasma capsulatum and subsequent development of stroke.

METHODS

A cross-sectional study of stroke in a cohort of US Navy veterans was designed to assess our hypothesis. Medical records from 23,795 men who participated in the cooperative skin-testing program and who received medical care at Veterans Administration Hospitals and Clinics were reviewed. A logistic regression model was used to estimate the odds ratio of stroke while controlling for multiple covariates. Because of the large number of possible risk factors for stroke, propensity scores were used to reduce bias.

RESULTS

The adjusted odds ratio for stroke in veterans exposed to Histoplasma capsulatum during adolescence was 1.34 (95% confidence interval: 1.1-1.6; P = .0033). The increased risk was independent of traditional cerebrovascular event risk factors. Less frequent risk factors (atrial fibrillation, coronary heart disease, rheumatic heart disease, and prosthetic cardiac valvular replacement) were not controlled in this model.

CONCLUSION

Exposure to Histoplasma capsulatum during adolescence was associated with an increased risk of stroke.

Amalgamation of Chlamydia pneumoniae inclusions with lipid droplets in foam cells in human atherosclerotic plaque

Chlamydia pneumoniae (Chlamydophila pneumoniae) infect macrophages and accelerates foam cell formation in in vitro experiments, but whether this might occur in human atherosclerosis is unknown. In the present study, we examined 17 carotid artery segments, obtained by endarterectomy, in which the presence of C. pneumoniae was confirmed by both polymerase chain reaction and immunohistochemistry. Electron microscopy demonstrated the presence of structures with the appearance of elementary, reticulate and aberrant bodies of C. pneumoniae in the cytoplasm of macrophage foam cells. The volume of the cytoplasm that was free from vacuoles and lipid droplets in C. pneumoniae-infected foam cells was dramatically reduced, and a phenomenon of the amalgamation of C. pneumoniae inclusions with lipid droplets was detected. Double immunohistochemistry showed that C. pneumoniae-infected foam cells contained a large number of oxidized low-density lipoproteins. The observations provide support to the hypothesis that C. pneumoniae could affect foam cell formation in human atherosclerosis.

Microbial risk factors of cardiovascular and cerebrovascular diseases: potential therapeutical options

Infection and inflammation may have a crucial role in the pathogenesis of atherosclerosis. This hypothesis is supported by an increasing number of reports on the interaction between chronic infection, inflammation, and atherogenesis. Assessment of serological and inflammatory markers of infection may be useful adjuncts in identifying those patients who are at a higher risk of developing vascular events, and in whom more aggressive treatments might be warranted.

Role of Chlamydia pneumoniae in atherosclerosis

Cardiovascular disease, resulting from atherosclerosis, is a leading cause of global morbidity and mortality. Genetic predisposition and classical environmental risk factors explain much of the attributable risk for cardiovascular events in populations, but other risk factors for the development and progression of atherosclerosis, which can be identified and modified, may be important therapeutic targets. Infectious agents, such as Chlamydia pneumoniae, have been proposed as contributory factors in the pathogenesis of atherosclerosis. In the present review, we consider the experimental evidence that has accumulated over the last 20 years evaluating the role of C. pneumoniae in atherosclerosis and suggest areas for future research in this field.

Severity of carotid atherosclerosis unrelated to Chlamydia pneumoniae infection in acute ischemic stroke patients: a clinicopathological study

BACKGROUND

Both clinical and pathological alterations of the carotid arteries were correlated with Chlamydia pneumoniae infection in 67 acute ischemic stroke patients with severe neurological symptoms.

METHODS

In the clinical study, intima-media thickness (IMT) of the common carotid arteries was determined in vivo by B-mode ultrasound measurement and C. pneumoniae-specific IgG and IgA responses were detected. In the pathological study, the absolute wall thickness of the common, internal and external carotid arteries was measured postmortem in specimens obtained at the autopsy of patients who died due to complications of acute stroke. In the atherosclerotic plaques of the autopsy specimens, C. pneumoniae genomic DNA was detected by polymerase chain reaction amplification.

RESULTS

The Spearman's rho correlation coefficient of IMT with the average wall thickness of the common, internal and external carotid arteries was 0.51 (p = 0.002), 0.34 (p = 0.052) and 0.58 (p < 0.001), respectively. Anti-C. pneumoniae IgG and IgA antibodies were detected in 43 (73%) and 29 (49%) patients, but neither antibody marker correlated with IMT (median: 0.91 mm in IgG positives vs. 0.90 mm in IgG negatives, p = 0.86; 0.88 mm in IgA positives vs. 0.90 mm in IgA negatives, p = 0.53). The presence of C. pneumoniae DNA was detected in the carotid plaques of 21 (54%) of the 39 tested patients, independently of either IMT values or the average wall thickness of all carotid arteries.

CONCLUSIONS

In acute ischemic stroke patients, C. pneumoniae infection was frequently detected in the arteriosclerotic plaques of the carotid arteries but it did not correlate with the severity of carotid arteriosclerosis.

Chlamydia pneumoniae is a likely risk factor for ischemic stroke in young patients

Recently, Chlamydia pneumoniae has been identified as a risk factor for atherosclerosis, cardiovascular disease, and stroke. In young patients the causes of stroke are more diverse, and remain unknown in about 30% of cases, despite thorough investigations. To find a possible relationship between C. pneumoniae infection and stroke at young age, we investigated C. pneumoniae antibody titers in 41 patients with ischemic stroke who were younger than 50 years old and in 55 healthy control subjects. A positive IgA antibody titer to C. pneumoniae was significantly associated with stroke (crude odds ratio 2.1; 90% confidence interval 1.1-9.5; P = .04). After adjusting for hypertension, smoking, and hypercholesterolemia, positive Chlamydia antibodies remained associated with stroke (adjusted odds ratio 2.8; 90% confidence interval 1.1-7.1; P = .04). No significant association between positive IgG antibodies and stroke was found. Because a positive IgA antibody titer may reflect a persistent infection, these data indicate that persistent C. pneumoniae infection may be an independent risk factor for stroke at young age.

Lack of association between infectious burden and carotid atherosclerosis in Japanese patients

Several infectious agents, such as Chlamydia pneumoniae, cytomegalovirus (CMV), herpes simplex virus (HSV), and Helicobacter pylori, have been implicated in the pathogenesis of atherosclerosis; however, but the contribution of infection may vary among races and geographic conditions. The present study investigates the association between the presence of these pathogens and carotid atherosclerosis and examines the relevance of an infectious burden during atherogenesis in Japanese patients undergoing carotid endarterectomy. We investigated a total of 50 carotid atherosclerotic plaques resected during carotid endarterectomy by polymerase chain reaction (PCR) for C. pneumoniae, CMV, HSV, and H. pylori and by immunocytochemistry (ICC) for C. pneumoniae. We also examined the presence of antibodies to IgG and/or IgA for each pathogen in blood samples. We detected HSV DNA in 2 specimens (4%) and positive ICC for C. pneumoniae in 8 (16%). The results of PCR, ICC, or serum antibodies, as well as the number of seropositive antibodies, did not correlate with severely stenotic, ulcerative, or symptomatic plaques. Our findings indicate that the detection rate of infectious agents within atherosclerotic plaques was significantly lower in our patients than that in other studies. Thus, an inflammatory mechanism might not correlate with the pathogenesis of carotid atherosclerosis among Japanese patients with severe carotid artery stenosis.

Anti-P. gingivalis response correlates with atherosclerosis

Significant associations between atherosclerosis and both Porphyromonas gingivalis, a major periodontopathogen, and the respiratory pathogen, Chlamydia pneumoniae, have been shown. Many individuals with evidence of atherosclerosis demonstrate seropositivity to these pathogens. The aim of the present study was to examine the atherogenic effect of repeated immunizations with either or both of these agents, and to determine if molecular mimicry of bacterial heat-shock protein (HSP), termed GroEL, and host (h) HSP60 was involved. Atherogenesis was examined in apolipoprotein-E-deficient (-/-) mice following intraperitoneal immunizations with P. gingivalis, C. pneumoniae, P. gingivalis, and C. pneumoniae or vehicle. Lesion area in the proximal aorta and levels of serum antibodies to P. gingivalis, C. pneumoniae, and GroEL were measured. The increased pathogen burden of P. gingivalis, but not of C. pneumoniae, enhanced atherosclerosis. hHSP60 was detected in lesions, and in P. gingivalis-immunized mice, lesion development was correlated with anti-GroEL antibody levels, supporting the involvement of molecular mimicry between GroEL and hHSP60.

Inflammation, heat shock proteins and periodontal pathogens in atherosclerosis: an immunohistologic study

BACKGROUND

Inflammation is a significant component of atherosclerosis lesions. Bacteria, including periodontopathogens, have been demonstrated in atherosclerotic plaques and cross-reactivity of the immune response to bacterial GroEL with human heat shock protein 60 has been suggested as a link between infections and atherosclerosis.

METHODS

In this study, the nature of the inflammatory infiltrate and the presence of human heat shock protein 60 and GroEL were examined in 31 carotid endarterectomy specimens. Additionally, monoclonal antibodies were used to detect the presence of six bacteria, including those implicated in periodontal disease.

RESULTS

The inflammatory cell infiltrate of the lesions was dominated by CD14(+) macrophages and CD4(+) T cells. Most cells of the infiltrate as well as the endothelium were HLA-DR(+), indicating activation; however, there was an absence of CD25 expression, demonstrating that the activated T cells were not proliferating. Few CD1a(+) and CD83(+) cells were noted. Human heat shock protein 60 expression was evident on endothelial cells and cells with the appearance of smooth muscle cells and lymphocytes. GroEL and bacteria were detected within intimal cells. Chlamydia pneumoniae, Porphyromonas gingivalis, Fusobacterium nucleatum, Tannerella forsythia, Prevotella intermedia, and Actinobacillus actinomycetemcomitans were found in 21%, 52%, 34%, 34%, 41%, and 17% of arteries, respectively.

CONCLUSION

These results give evidence for a specific immune response associated with atherosclerosis. Whether bacteria initiate the observed inflammation in atherosclerotic lesions is not clear; however, the present study shows that maintenance of inflammation may be enhanced by the presence of periodontopathic bacteria.

Chlamydia pneumoniae, heat shock proteins 60 and risk of secondary cardiovascular events in patients with coronary heart disease under special consideration of diabetes: a prospective study

BACKGROUND

There have been suggestions of an association between Chlamydia pneumoniae, chlamydial heat shock protein (Ch-hsp) 60 and human heat shock protein (h-hsp) 60 infection sero-status and development of secondary cardiovascular events. Patients with diabetes might be at higher risk since they are prone to infections. The objective of this study was to investigate prospectively the role of Chlamydia pneumoniae (CP), chlamydial heat shock protein (Ch-hsp) 60 and a possible intermediate role of human heat shock protein (h-hsp) 60 sero-status in the development of secondary cardiovascular disease (CVD) events in patients with coronary heart disease (CHD) under special consideration of diabetes mellitus.

METHODS

Patients aged 30-70 undergoing an in-patient rehabilitation program after acute manifestation of coronary heart disease (International Classification of Disease, 9th Rev. pos. 410-414) between January 1999 and May 2000 in one of two participating rehabilitation clinics in Germany were included in this analysis. Chlamydia pneumoniae (CP), chlamydial heat shock protein (Ch-hsp) 60 and human heat shock protein (h-hsp) 60 status at baseline were measured by serum immunoglobulin G and A antibodies. Secondary CVD events (myocardial infarction, stroke, and cardiovascular death) were recorded during a mean follow-up period of 33.5 months (response = 87%).

RESULTS

Among the 1052 subjects 37.4% and 39.3% were sero-positive to CP IgA and IgG respectively, 22.2% were sero-positive to Ch-hsp 60 IgG and 8.4% were positive to h-hsp 60 IgG at baseline. During follow-up, secondary CVD events occurred among 71 (6.8%) participants. Occurrence of a secondary CVD event was more common among CP (IgA) and CP (IgG) sero-positive than among sero-negative patients (p-values 0.04 and 0.1, respectively). The risk of secondary CVD events was increased among patients with both a positive CP sero-status and diabetes compared to infection negative, non-diabetic patients and in general, sero-positivity added a hazard to diabetes. The interaction term between infection sero-status and diabetes was not statistically significant. We were not able to show an intermediate role of human heat shock protein (h-hsp) 60 sero-status in the development of secondary CVD events in patients with CHD.

CONCLUSION

Results from this cohort of 1052 patients with pre-existing CHD cannot exclude a possible moderate increase in risk of secondary CVD events among patients with a positive infection sero-status. However, our study showed no intermediate role of human heat shock protein (h-hsp) 60 sero-status in the development of secondary CVD events in patients with CHD. Larger studies or meta-analysis of multiple studies are needed to address the interaction between infection sero-status and diabetes with adequate power.

Chlamydophila pneumoniae and human cytomegalovirus in atherosclerotic carotid plaques--combined presence and possible interactions

The aim of our study was to investigate the combination of Chlamydophila pneumoniae and human cytomegalovirus (HCMV) as a pathogenic factor in atherosclerosis. Accordingly, we tested by means of PCR and immunohistochemistry the presence of these pathogens in the same atherosclerotic carotid specimen. The histology of the samples and the patients' antibodies against these pathogens were evaluated. Further, we examined the impact of C. pneumoniae and HCMV infection on the gene expression of the human monocytic cell line U937. Six of the 22 samples contained only C. pneumoniae, 4 contained only HCMV, 7 contained both C. pneumoniae DNA and/or antigens of both pathogens, and 5 samples were negative. No correlation was found between the presence of these microbes and either the cellular structure of the plaques, or the serostatus of the patients. The infection of U937 cells with HCMV and especially C. pneumoniae induced inflammation and atherosclerosis-related genes. Furthermore, the doubly-infected cells produced higher levels of the mRNA of pro-platelet basic protein and fatty acid binding protein 4. In conclusion, C. pneumoniae is often present in combination with HCMV in atherosclerotic carotid lesions. The in vitro coinfection model reveals that the doubly-infected monocytes are potent expressors of proatherosclerotic genes, suggesting that this coinfected population may accelerate the process of atherosclerosis.

Place of drug therapy in the treatment of carotid stenosis

Carotid stenosis is an important cause of transient ischaemic attacks and stroke. The cause of carotid stenosis is most often atherosclerosis; contributing to the pathogenesis of the lesion are endothelial injury, inflammation, lipid deposition, plaque formation, fibrin, platelets and thrombin. Carotid stenosis accounts for 10-20% of cases of brain infarction, depending on the population studied. Despite successful treatment of selected patients who have had an acute ischaemic stroke with tissue plasminogen activator and the promise of other experimental therapies, prevention remains the best approach to reducing the impact of ischaemic stroke. High-risk or stroke-prone patients can be identified and targeted for specific interventions. At this juncture, treatment of carotid stenosis is a well established therapeutic target and a pillar of stroke prevention. There are two main strategies for the treatment of carotid stenosis. The first approach is to stabilise or halt the progression of the carotid plaque through risk factor modification and medication. Hypertension, diabetes mellitus, smoking, obesity and high cholesterol levels are closely associated with carotid stenosis and stroke; control of these factors may decrease the risk of plaque formation and progression. The second approach is to eliminate or reduce carotid stenosis through carotid endarterectomy or carotid angioplasty and stenting. Carotid endarterectomy, which is the mainstay of therapy for severe carotid stenosis, is beyond the scope of this review. Anticoagulants seem to play little role (if any) in the medical (i.e. non-surgical) treatment of carotid stenosis. Adoption of a healthy lifestyle combined with the reduction of risk factors has been shown to lead to a reduction in the extent of carotid stenosis. The medical treatment of carotid stenosis should be based on the triad of the reduction of risk factors, patient education, and use of antiplatelet agents.

Characterization of heat shock protein-specific T cells in atherosclerosis

A role for infection and inflammation in atherogenesis is widely accepted. Arterial endothelium has been shown to express heat shock protein 60 (HSP60) and, since human (hHSP60) and bacterial (GroEL) HSP60s are highly conserved, the immune response to bacteria may result in cross-reactivity, leading to endothelial damage and thus contribute to the pathogenesis of atherosclerosis. In this study, GroEL-specific T-cell lines from peripheral blood and GroEL-, hHSP60-, and Porphyromonas gingivalis-specific T-cell lines from atherosclerotic plaques were established and characterized in terms of their cross-reactive proliferative responses, cytokine and chemokine profiles, and T-cell receptor (TCR) Vbeta expression by flow cytometry. The cross-reactivity of several lines was demonstrated. The cytokine profiles of the artery T-cell lines specific for GroEL, hHSP60, and P. gingivalis demonstrated Th2 phenotype predominance in the CD4 subset and Tc0 phenotype predominance in the CD8 subset. A higher proportion of CD4 cells were positive for interferon-inducible protein 10 and RANTES, with low percentages of cells positive for monocyte chemoattractant protein 1 and macrophage inflammatory protein 1alpha, whereas a high percentage of CD8 cells expressed all four chemokines. Finally, there was overexpression of the TCR Vbeta5.2 family in all lines. These cytokine, chemokine, and Vbeta profiles are similar to those demonstrated previously for P. gingivalis-specific lines established from periodontal disease patients. These results support the hypothesis that in some patients cross-reactivity of the immune response to bacterial HSPs, including those of periodontal pathogens, with arterial endothelial cells expressing hHSP60 may explain the apparent association between atherosclerosis and periodontal infection.

Chlamydia pneumoniae Infection as a Risk Factor for Subarachnoid Hemorrhage

Many risk factors for subarachnoid hemorrhage (SAH), such as hypertension and recent infection, have already been established. Chlamydia pneumoniae is a common respiratory pathogen that has been implicated as a potential risk factor for hypertension and atherosclerotic diseases. The purpose of the case-control study presented here was to examine the causative relationship between C. pneumoniae infection and SAH. Serum C. pneumoniae IgG and IgA antibodies were measured using an enzyme-linked immunosorbent assay in 52 patients with SAH and in 104 healthy age-matched control subjects. Multivariate analysis revealed a significant association between SAH and both a strong seropositivity for IgG and/or IgA antibodies against C. pneumoniae (odds ratio, OR, 3.62; 95% confidence intervals, CI, 1.06-12.39; p = 0.040), which indicates the presence of acute C. pneumoniae infection, and hypertension (OR, 2.91; 95% CI, 1.42-5.96; p = 0.0035). These results provide evidence that infection with C. pneumoniae may be a risk factor for SAH from a ruptured intracranial aneurysm.

Detection of Chlamydophila pneumoniae in dendritic cells in atherosclerotic lesions

Dendritic cells (DCs) populate atherosclerotic lesions and might be involved in the regulation of immune reactions in atherosclerosis. The present work was undertaken to examine a possible association of DCs with Chlamydophila pneumoniae in human atherosclerotic plaques obtained by endarterectomy. C. pneumoniae was identified in 17 of 60 (28%) atherosclerotic plaques by a combination of immunohistochemistry and polymerase chain reaction (PCR). Double immunohistochemistry identified the presence of C. pneumoniae within S100(+) DCs that were localised predominantly in the deep layer of the intima under the necrotic core. Quantitative analysis showed that there were no differences in the numbers of DCs between C. pneumoniae(+) and C. pneumoniae(-) groups of atherosclerotic specimens. There were also no differences in the expression of Lag-antigen and HLA-DR by DCs between the groups of specimens. Markers of DC activation CD80 and CD86 were absent from both groups of specimens. Flow cytometry analysis of the effects of C. pneumoniae infection on immature monocyte-derived DCs in vitro showed no changes in the expression of CD1a, MHC class II, CD80 and CD86. The results of this study demonstrate that C. pneumoniae might infect DCs within the atherosclerotic intima but whether the presence of C. pneumoniae in DCs affects the intensity of immune reactions in atherosclerosis needs further clarification.

Chlamydia pneumoniae in coronary bypass grafts of redo patients. The concept of the ‘adventitial baseline infection’

The pathogenic role of Chlamydia pneumoniae in late coronary bypass graft failure has not yet been extensively investigated. We examined failed and new arterial/venous bypass grafts using immunohistochemistry, polymerase chain reaction (PCR), and serology. Thirty-four long-term failed grafts and 28 new grafts were examined in 21 patients undergoing redo coronary artery bypass grafting (CABG). Immunohistochemically, 28 (82%) failed grafts were positive in the intimal-medial compartment, and 33 grafts (97%) were positive for C. pneumoniae in the adventitia. Thirteen (46%) and 27 (96%) new grafts showed infection in the intima-media and in the adventitia, respectively (p < 0.05). Immunohistochemically, the overall presence of C. pneumoniae in all vessels examined was 66% in the intima-media and 97% in the adventitia (p < 0.05). C. pneumoniae was detected by PCR in 19 (31%) of all the vessels examined. C. pneumoniae seems to be frequently present in grafts of patients considered for redo CABG in Hungary. The adventitia of both failed, and new grafts particularly often contained C. pneumoniae. The results suggest that there exists an adventitial baseline infection from which infection of the inner wall layers develops, depending on local microenvironmental conditions. This is the first study to evaluate chlamydial infection in arterial/venous coronary grafts by immunohistochemistry, PCR, and serology.

Chlamydia pneumoniae decreases smooth muscle cell proliferation through induction of prostaglandin E2 synthesis

Chlamydia pneumoniae may modulate the proliferation of smooth muscle cells (SMC) in atherosclerotic plaques. Conditioned medium from C. pneumoniae-infected SMC decreased the proliferation of uninfected SMC. Treatment of infected cells with the cyclooxygenase-2 inhibitor NS-398 [N-[2-(cyclohexyloxy)-4-nitrophenyl]-methanesulfonamide] suppressed the up-regulation of prostaglandin E(2) (PGE(2)) and abolished the antimitogenic effect of conditioned medium, suggesting that C. pneumoniae can decrease SMC proliferation via stimulation of PGE(2) synthesis.

Chlamydia pneumoniae and atherosclerosis following carotid endarterectomy

BACKGROUND

Seroepidemiological studies have shown an association between raised antibody titres against Chlamydia pneumoniae, and carotid atherosclerosis or stroke. However, direct evidence for a causal link between arterial infection with C. pneumoniae and carotid disease remains weak. We hypothesized that long-term follow-up of patients with pathologically-proven arterial C. pneumoniae infection might provide further insight into the role of C. pneumoniae in carotid atherosclerosis.

METHODS

We followed a cohort of 70 carotid endarterectomy patients for ipsilateral restenosis, contralateral progression, and all-cause mortality (four year median follow-up period). All patients had presence or absence of C. pneumoniae in their carotid plaques documented by immunohistochemistry after endarterectomy. A survival function was generated and the log-rank test was used to assess the difference in survival between subjects with and without documented chlamydial infection in their plaque.

RESULTS

Baseline demographic and cardiovascular risk factors were similar between the two groups, and survival analysis demonstrated no difference (p>0.05) in all-cause mortality, or all-cause mortality combined with restenosis and progression.

CONCLUSIONS

Our data finds no causal role for C. pneumoniae in restenosis or progression of carotid disease or mortality in this patient population with advanced carotid atherosclerosis.

Chronic infection and coronary artery disease

On a variety of fronts, chronic infection has been found to be significantly associated with the development of atherosclerosis and the clinical complications of unstable angina, myocardial infarction, and stroke. For the most part, these relationships are still just associations. Failure to confirm initial reports of serologic associations also has been common. Specific causative relationships on par with that determined between H pylori and peptic ulcer disease have not yet been established. Potential mechanisms whereby chronic infections may play a role in atherogenesis are myriad. In the case of C pneumoniae, the effect may result from direct vessel wall colonization that may damage the vessel either directly or indirectly by initiating immunologic responses. In other cases the effect may simply be that of enhancing the pre-existing chronic inflammatory response of the body to standard risk factors such as hyperlipidemia. Even though the infectious agent may not directly infect the vessel wall, it may perform its critical role from afar. Chronic infection might also influence pre-existing plaque by enhancing T-cell activation or other inflammatory responses that may participate in the destabilization of the intimal cap. Hence chronic infection may play a role either in the initiation, progression, or the destabilization of atherosclerotic plaques. The infectious agents with the most evidence to support an etiologic role in atherosclerosis include C pneumoniae and cytomegalovirus. Evidence is mounting for a variety of other potential agents including other herpes viruses, influenza, other specific bacteria (such as M pneumoniae), and chronic infections with common bacterial agents (periodontal disease, chronic bronchitis, and chronic urinary tract infection, among others) [191]. Future studies are expected to elucidate further the pathophysiologic relationship between chronic infection and atherosclerosis and to evaluate further the potential of a variety of treatment approaches, including antibiotics.

Increased production of matrix metalloproteinases 1 and 3 by smooth muscle cells upon infection with Chlamydia pneumoniae

Atherosclerosis has been linked to Chlamydia pneumoniae infection. In atherosclerotic arteries chlamydiae infect macrophages, endothelial cells, and smooth muscle cells (SMC). It has been suggested that the proteolysis of the extracellular matrix by matrix metalloproteinases (MMPs) is involved in the destabilisation and rupture of atherosclerotic plaques. In this study we investigated the expression of several MMPs and tissue inhibitors of MMP (TIMPs) in C. pneumoniae-infected SMC using reverse transcription-polymerase chain reaction analysis. Chlamydial infection of SMC up-regulated the mRNA levels of MMP-1 (interstitial collagenase) and MMP-3 (stromelysin) but did not affect the expression of MMP-2 and -9 (gelatinases). Additionally, the levels of TIMP-1 and -2 mRNA remained unchanged upon infection. Cells infected with C. pneumoniae secreted increased quantities of MMP-1 and -3 proteins as demonstrated by enzyme-linked immunosorbent assays. The ability of C. pneumoniae to stimulate the production of MMP-1 and -3 by SMC may be important for its pathogenic role in the progression of atherosclerotic disease.

Chronic Chlamydophila pneumoniae infection in lung cancer, a risk factor: a case-control study

The relationship between chronic Chlamydophila (formerly Chlamydia) pneumoniae infection and lung carcinoma was investigated. A total of 123 patients who were smokers and diagnosed with lung carcinoma based on clinical and laboratory (radiological, cytological) findings were examined. Of these patients, 70 had small-cell, 28 squamous-cell and seven large-cell carcinomas, while 18 had adenocarcinoma. A total of 123 healthy persons matching patients in age, sex, duration of smoking and locality were chosen as controls. Blood samples (5 ml) were withdrawn at the time of diagnosis and 1 month later. The values between IgG >/= 512 and IgA >/= 40 were set as the criteria for chronic Chlamydophila pneumoniae infections. In male patients with lung carcinoma, Chlamydophila pneumoniae IgG antibody titres of >/= 512 and IgA antibody titres of >/= 40 were found at a higher rate than in the control group. This ratio was not significant for the female patients. In chronic Chlamydophila pneumoniae infections, Chlamydophila pneumoniae antibody titres with values IgG >/= 512 and IgA >/= 40 were found in a total of 62 (50.4 %) cases. Chronic Chlamydophila pneumoniae infections were seen statistically more often in male patients with carcinoma who were aged 55 years or younger. This study supports the idea that chronic Chlamydophila pneumoniae infection increases the risk of lung carcinoma.

Evidence of an association between Chlamydia pneumoniae and cerebrovascular accidents

The authors report results of a retrospective pilot study showing a strong association between patients with stroke/TIA and the presence of circulating IgG and IgA antibodies to Chlamydia pneumoniae. These results support the hypothesis that chronic active or persistent infection may play a role in the mechanism of thrombosis. The risk for stroke associated with Chlamydial circulating antibodies appeared to be independent of other risk factors such as diabetes and hypercholesterolemia.

Aspirin inhibits Chlamydia pneumoniae-induced NF-kappa B activation, cyclo-oxygenase-2 expression and prostaglandin E2 synthesis and attenuates chlamydial growth

Infection with Chlamydia pneumoniae has been implicated as a potential risk factor for atherosclerosis. This study was designed to investigate the mechanisms of the anti-chlamydial activity of aspirin. A reporter gene assay for NF-kappa B activity, immunoblot analysis for cyclo-oxygenase (COX)-2 and radioimmunoassay for prostaglandin E(2) (PGE(2)) were performed. Following infection of HEp-2 cells with C. pneumoniae, NF-kappa B was activated, COX-2 was induced and PGE(2) was elevated. Aspirin inhibited NF-kappa B activation at a concentration of 0.1 mM, partially inhibited COX-2 induction and blocked PGE(2) synthesis completely. In addition, high doses of aspirin (1 and 2 mM) inhibited chlamydial growth in HEp-2 cells, decreasing the number and size of inclusion bodies; this effect could be overcome by adding tryptophan to the culture. Indomethacin also blocked the synthesis of PGE(2), but had no effect on COX-2 expression or chlamydial growth. These results indicate that aspirin not only has an anti-inflammatory activity through prevention of NF-kappa B activation but also has anti-chlamydial activity at high doses, possibly through depletion of tryptophan in HEp-2 cells.

Detection of Chlamydia pneumoniae but not of Helicobacter pylori in symptomatic atherosclerotic carotids associated with enhanced serum antibodies, inflammation and apoptosis rate

BACKGROUND AND PURPOSE

Numerous seroepidemiological and pathological studies linked Chlamydia pneumoniae and Helicobacter pylori with atherosclerosis. However, analyses of these infectious agents in the pathogenesis of stroke are either lacking or contradictory. Therefore, we evaluated the detection rate of C. pneumoniae and H. pylori in normal carotids vs. atherosclerotic carotids and compared these findings with serology, plaque morphology, inflammatory cell infiltrates and apoptosis rate.

METHODS

The study was performed on 40 morphological normal carotids from autopsy and 20 advanced atherosclerotic carotids from endarterectomy after stroke. Serum IgG antibody titre was measured by enzyme immunoassay (H. pylori) and microimmunofluorescence (MIF) technique (C. pneumoniae). Immunohistochemistry (IHC) and Western blotting were performed to identify C. pneumoniae, H. pylori, to characterize plaque morphology (macrophages and smooth muscle cells) and the inflammatory infiltrate (T- and B cells) and to detect apoptosis (TUNEL staining).

RESULTS

C. pneumoniae was found significantly more frequently in atherosclerotic than in normal carotids (P=0.001), which correlated with elevated C. pneumoniae IgG-antibody titres (P=0.048). Although H. pylori was not detected in carotids, elevated H. pylori antibody titres were significantly associated with the degree of atherosclerosis (P=0.001). The C. pneumoniae infected carotids displayed a slightly enhanced infiltrate of T cells and apoptosis rate, but no morphological changes.

CONCLUSION

C. pneumoniae but not H. pylori, was detected by IHC primarily in symptomatic carotids, without specific morphological differences. Correlation of C. pneumoniae in-situ-detection and IgG antibodies suggested a possible connection between respiratory-tract and endovascular infection. The C. pneumoniae associated T-lymphocytes and apoptosis rate indicate an immune-mediated inflammatory process, involving vascular walls.

Role of Chlamydia pneumoniae-infected macrophages in atherosclerosis developments of the carotid artery

Chlamydia pneumoniae (C. pneumoniae) infection has been recently accepted as an important cause of atherosclerosis. However, the precise mechanisms remain unclear. The present study was aimed to clarify the distribution link among C. pneumoniae, chlamydial HSP 60, and activated macrophages. Atheromatous carotid plaques were obtained from 40 consecutive carotid endarterectomies (CEA). The specimens were prepared for HE and elastica-van Gieson staining. Parallel sections were stained immunocytochemically with monoclonal antibodies for a C. pneumoniae-specific antigen, chlamydial HSP 60, activated macrophages, and smooth muscle cells. Immunoreactivity for the C. pneumoniae-specific antigen was observed within the endothelial cells, activated macrophages, and smooth muscle cells in 36 of 40 specimens (90%). Chlamydial HSP 60 was found in all specimens positive for the C. pneumoniae-specific antigen, and mainly co-localized with the C. pneumoniae-specific antigen within the activated macrophages. The present results suggest that C. pneumoniae is a key microbial organ that causes atheroma developments in the carotid artery. Chlamydia pneumoniae-infected macrophages may come into the arterial intima and mediate inflammatory and autoimmune processes through the production of chlamydial HSP 60, leading to atherosclerosis.

Chlamydial LPS antibodies, intima-media thickness and ischemic events in patients with established atherosclerosis

BACKGROUND

Chlamydia pneumoniae has been associated with cardiovascular disease. However, studies on the presence of chlamydial antibodies and intima-media thickness (IMT) or future ischemic events are inconclusive. We examined the relation between circulating antibodies to chlamydial lipopolysaccharide (cLPS Ab), IMT and the occurrence of ischemic events during follow-up in patients with manifest atherosclerotic disease.

METHODS

IgG and IgA antibodies against cLPS were determined in 273 out of 307 consecutive patients with a recent ischemic stroke (IS, n=90), a recent myocardial infarction (MI, n=87) or peripheral arterial disease (PAD, n=96). B-mode ultrasound IMT measurement of carotid and femoral arteries was performed and ischemic events, IS or MI, during follow-up were registered.

RESULTS

IgG and IgA were found in 66 and 46% of the patients, respectively. We did not detect any difference in IMT between patients with or without antibodies: IgA-0.97(0.28) mm versus IgA+0.95(0.26) mm, P=0.63, IgG-0.96(0.28) mm versus IgG+0.96(0.26) mm, P=0.98. During follow-up with a mean duration of 3.5 years the combined endpoint, MI or IS, was similar in patients with or without antibodies (IgA-24% vs. IgA+19%, IgG-23% vs. IgG+22%). However, a lower frequency of MI was observed in IgA positive patients (IgA-13% vs. IgA+8%). The number of ischemic events in the 12 patients who used anti-chlamydial antibiotics was similar compared with those who did not use antibiotics.

CONCLUSION

In patients with manifest atherosclerotic disease no association between the presence of cLPS Ab and IMT could be detected. In addition, no influence of cLPS Ab on the number of ischemic events was observed, the frequency of MI during follow-up in IgA positive patients was even lower.

Inflammation and infection in clinical stroke

Stroke has enormous clinical, social, and economic implications, and demands a significant effort from both basic and clinical science in the search for successful therapies. Atherosclerosis, the pathologic process underlying most coronary artery disease and the majority of ischemic stroke in humans, is an inflammatory process. Complex interactions occur between the classic risk factors for atherosclerosis and its clinical consequences. These interactions appear to involve inflammatory mechanisms both in the periphery and in the CNS. Central nervous system inflammation is important in the pathophysiologic processes occurring after the onset of cerebral ischemia in ischemic stroke, subarachnoid hemorrhage, and head injury. In addition, inflammation in the CNS or in the periphery may be a risk factor for the initial development of cerebral ischemia. Peripheral infection and inflammatory processes are likely to be important in this respect. Thus, it appears that inflammation may be important both before, in predisposing to a stroke, and afterwards, where it is important in the mechanisms of cerebral injury and repair. Inflammation is mediated by both molecular components, including cytokines, and cellular components, such as leukocytes and microglia, many of which possess pro- and/or antiinflammatory properties, with harmful or beneficial effects. Classic acute-phase reactants and body temperature are also modified in stroke, and may be useful in the prediction of events, outcome, and as therapeutic targets. New imaging techniques are important clinically because they facilitate dynamic evaluation of tissue damage in relation to outcome. Inflammatory conditions such as giant cell arteritis and systemic lupus erythematosus predispose to stroke, as do a range of acute and chronic infections, principally respiratory. Diverse mechanisms have been proposed to account for inflammation and infection-associated stroke, ranging from classic risk factors to disturbances of the immune and coagulation systems. Considerable opportunities therefore exist for the development of novel therapies. It seems likely that drugs currently used in the treatment of stroke, such as aspirin, statins, and modulators of the renin-angiotensin-aldosterone system, act at least partly via antiinflammatory mechanisms. Newer approaches have included antimicrobial and antileukocyte strategies. One of the most promising avenues may be the use of cytokine antagonism, for example, interleukin-1 receptor antagonist.

Chlamydia pneumoniae in different coronary artery segments in the young

Chlamydia pneumoniae has emerged as the most likely pathogen to have a causative role in the development and/or for progression of atherosclerosis. Evidence for this is based on epidemiological and pathological studies. In an effort to better understand the significance of finding C. pneumoniae in atheromata, we examined coronary artery segments of young adults (15-34 years) with and without atherosclerosis. Left anterior descending coronary arteries (LAD) of 74 young adults who died suddenly were examined histologically and for the presence of C. pneumoniae by immunohistochemistry. C. pneumoniae was identified in advanced lesions (Stary types III to VI) in 17 of 32 cases (53%), and in early lesions (Stary type I-II) in 8 of 37 cases (21%), mainly at the proximal segments of the LAD. C. pneumoniae was not found in the intimal and medial layer of normal-appearing coronary arteries. C. pneumoniae was detected in the adventitia in 51 (67%) coronary arteries: in 27 of normal arteries and early lesions (64%), and in 24 of atherosclerotic lesions (75%). C. pneumoniae was found most often in macrophages, less offen in smooth muscle cells. We also observed a correlation between C. pneumoniae positivity and cigarette smoking.

IN CONCLUSION

C. pneumoniae may relate to the severity of atherosclerosis in young people, and it may thus initiate atherosclerotic injury or facilitate its progression with other risk factors.

Association between seropositivity to Chlamydia pneumoniae and acute ischaemic stroke

Recent studies suggest an association between Chlamydia pneumoniae infection with atherosclerosis, including cerebrovascular disease. We investigated the prevalence of Chlamydial seropositivity in patients with acute ischaemic stroke syndrome compared with age- and sex-matched control subjects. Specific antibodies (IgA) to C. pneumoniae were measured by microimmunofluorescence in both the clinical group (n=91) and the control group (n=112). Forty patients (43.9%) and 34 controls (30.3%) had positive IgA titres (P < 0.05). The pooled data from this and previous series yielded 45% of seropositivity in cerebrovascular patients vs. 19% in control subjects (P < 0.001). In conclusion, we suggest an association between chronic infection by C. pneumoniae and acute ischaemic stroke.

New perspectives on macrolide antibiotics

Macrolides are not used exclusively for the treatment of community-acquired respiratory tract infections. Their ability to penetrate cells makes them highly suitable for the treatment of diseases caused by intracellular pathogens, such as non-gonococcal urethritis and trachoma. Azithromycin is approved for these indications. Clinical studies have also been conducted, or are currently being carried out, to assess the use of macrolides in the treatment of atherosclerosis, eradication of Helicobacter pylori and the management of life-threatening gastrointestinal diseases, cystic fibrosis and malaria.

Chlamydia pneumoniae and atherosclerosis: critical assessment of diagnostic methods and relevance to treatment studies

A number of studies have found that inflammation of the vessel wall plays an essential role in both the initiation and progression of atherosclerosis and erosion and fissure and the eventual rupture of plaques. Chlamydia pneumoniae is one of the infectious agents that have been investigated as possible causes of this inflammation. Initial studies of the association of C. pneumoniae and cardiovascular disease (CVD) were seroepidemiologic, and these were followed by studies in which the organism was identified in vascular tissue from patients with CVD by electron microscopy, PCR and immunocytochemical staining (ICC). C. pneumoniae has also been isolated by culture from vascular tissue in a small number patients. However, no single serologic, PCR, or ICC assay has been used consistently across all studies. The assays used are also not standardized. Recent studies of serologic and PCR assays for diagnosis of C. pneumoniae infection have suggested that there may be substantial interlaboratory variation in the performance of these tests. It now appears that some of the inconsistency of results from study to study may be due, in part, to lack of standardized methods. Although initial seroepidemiologic studies demonstrated a significantly increased risk of adverse cardiac outcome in patients who were seropositive, subsequent prospective studies found either small or no increased risk. In addition to the lack of consistent serologic criteria, recent evaluations have demonstrated inherent problems with performance of the most widely used serologic methods. Most importantly, we do not have a reliable serologic marker for chronic or persistent C. pneumoniae infection.

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

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

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.

Interferon-beta induction by Chlamydia pneumoniae in human smooth muscle cells

Clinical studies have suggested a causal or contributory role of Chlamydia pneumoniae infection in asthma and atherosclerosis. The activation of synthetic functions of smooth muscle cells (SMC) including the production of cytokines and growth factors plays a major role in the formation of fibrous atherosclerotic plaques as well as in structural remodelling of the airway wall in chronic asthma. In this study we demonstrated that C. pneumoniae induced the production of low levels of interferon (IFN)-beta in bronchial and vascular SMC when infected cells were treated with tumour necrosis factor-alpha (TNF-alpha). IFN-beta production was analysed by reverse transcription-PCR and enzyme-linked immunosorbent assay. The upregulation of IFN-beta was paralleled by an increase in mRNA levels of interferon regulatory factor-1 and interferon-stimulated gene factor 3gamma, two transcription factors activating the expression of the IFN-beta gene. In addition, C. pneumoniae infection enhanced the mRNA level of indoleamine 2,3-dioxygenase, an IFN-inducible factor mediating the restriction of intracellular chlamydial growth, in TNF-alpha-stimulated SMC. C. pneumoniae-induced IFN-beta production by SMC may modulate inflammation and tissue remodelling during respiratory and vascular infection.