Involvement of Chlamydia pneumoniae in atherosclerosis: more evidence for lack of evidence

A Hidden Organism, Chlamydia in the Age of Atherosclerosis

Atherosclerosis is a chronic inflammatory disease. It is still the leading cause of mortality and morbidity in the world. Inflammation in the vessels plays the most important role in the pathogenesis of atherosclerosis. Many studies have been emphasized that Chlamydia pneumoniae triggers inflammation in the vessels and associated with atherosclerosis. It is stated that most of the chlamydial infections are asymptomatic and around 40% of adult individuals are infected. Chlamydia has different subgroups. It was thought to be a virus due to its intracellular pathogenicity, but it was included in the bacteria genus because it contains DNA and RNA chromosomes and has enzymatic activity. Chlamidya can easily be transmitted through the respiratory tract and sexual transmission. Seroepidemiological and pathological studies of atherosclerotic plaques showed the presence of Chlamydia in the plaque. This section will provide relationship between Chlamydia and atherosclerosis on the recent researces and current information will be discussed.

Current status of stroke in Qatar: Including data from the BRAINS study

BACKGROUND

Qatar is located on the north-eastern coast of the Arabian Peninsula. Qatari natives account for less than 15% of the population while the largest migrant group comprising 60% derives from South Asia. Despite projections that stroke burden in Qatar will increase with population ageing, epidemiological studies focusing on stroke in Qatar are relatively scarce.

METHOD

We reviewed the available epidemiological publications relating to Qatar. In addition, we have added to this knowledge by incorporating Qatari data from the on-going Bio-Repository of DNA in Stroke, an independent multinational database of stroke patients.

RESULTS

Qatar has low reported incidence and mortality rates of 58 and 9.17 per 100,000 per year, respectively, which may be explained by its middle-aged migrant worker majority population. Correspondingly, South Asian migrants in Qatar suffered younger strokes than Qatari natives (48.7 vs 63.4 years, P < 0.001). Among the most common risk factors identified in stroke patients were hypertension (77.9%), diabetes (43.8%) and hypercholesterolemia (28.5%). Ischaemic stroke was the most frequent subtype amongst migrant South Asians (71.1%). The majority of stroke cases had computed tomography and/or magnetic resonance imaging scans, but only 11.1% of ischaemic strokes were thrombolysed. Qataris on one-year follow up were more often found to have died (6.5% vs 0.3%) and had further stroke/transient ischaemic attack events (17.4% vs 6.4%, P = 0.009) compared to South Asians.

CONCLUSION

The burden of stroke is increasing in Qatar, and considerable disparities are observed between the native and migrant populations which likely will require different approaches to management by its healthcare system.

Discovery of Human-Specific Immunodominant Chlamydia trachomatis B Cell Epitopes

Current serological assays for species-specific detection of anti-Chlamydia species antibodies suffer from well-known shortcomings in specificity and ease of use. Due to the high prevalences of both anti-C. trachomatis and anti-C. pneumoniae antibodies in human populations, species-specific serology is unreliable. Therefore, novel specific and simple assays for chlamydial serology are urgently needed. Conventional antigens are problematic due to extensive cross-reactivity within Chlamydia spp. Using accurate B cell epitope prediction and a robust peptide ELISA methodology developed in our laboratory, we identified immunodominant C. trachomatis B cell epitopes by screening performed with sera from C. trachomatis-infected women. We discovered 38 novel human host-dependent antigens from 20 immunodominant C. trachomatis proteins, in addition to confirming 10 host-independent mouse serum peptide antigens that had been identified previously. This extended set of highly specific C. trachomatis peptide antigens can be used in simple ELISA or multiplexed microarray formats and will provide high specificity and sensitivity to human C. trachomatis serodiagnosis.

Chlamydia species-specific serology is compromised by cross-reactivity of the gold standard microimmunofluorescence (MIF) or commercial enzyme-linked immunosorbent assays (ELISAs). This study was conducted to discover novel C. trachomatis-specific peptide antigens that were recognized only by the antibody response of the natural human host. We evaluated a library of 271 peptide antigens from immunodominant C. trachomatis proteins by reactivity with 125 C. trachomatis antibody-positive sera from women with PCR-confirmed C. trachomatis infection and 17 C. trachomatis antibody-negative sera from low-risk women never diagnosed with C. trachomatis infection. These C. trachomatis peptide antigens had been predicted in silico to contain B cell epitopes but had been nonreactive with mouse hyperimmune sera against C. trachomatis. We discovered 38 novel human host-dependent antigens from 20 immunodominant C. trachomatis proteins (PmpD, IncE, IncG, CT529, CT618, CT442, TarP, CT143, CT813, CT795, CT223, PmpC, CT875, CT579, LcrE, IncA, CT226, CT694, Hsp60, and pGP3). Using these human sera, we also confirmed 10 C. trachomatis B cell epitopes from 6 immunodominant C. trachomatis proteins (OmpA, PmpD, IncE, IncG, CT529, and CT618) as host species-independent epitopes that had been previously identified by their reactivity with mouse hyperimmune sera against C. trachomatis. ELISA reactivities against these peptides correlated strongly with the C. trachomatis microimmunofluorescence (MIF) text results (Pearson’s correlation coefficient [R] = 0.80; P < 10⁻⁶). These C. trachomatis peptide antigens do not cross-react with antibodies against other Chlamydia species and are therefore suitable for species-specific detection of antibodies against C. trachomatis. This study identified an extended set of peptide antigens for simple C. trachomatis-specific ELISA serology.

IMPORTANCE Current serological assays for species-specific detection of anti-Chlamydia species antibodies suffer from well-known shortcomings in specificity and ease of use. Due to the high prevalences of both anti-C. trachomatis and anti-C. pneumoniae antibodies in human populations, species-specific serology is unreliable. Therefore, novel specific and simple assays for chlamydial serology are urgently needed. Conventional antigens are problematic due to extensive cross-reactivity within Chlamydia spp. Using accurate B cell epitope prediction and a robust peptide ELISA methodology developed in our laboratory, we identified immunodominant C. trachomatis B cell epitopes by screening performed with sera from C. trachomatis-infected women. We discovered 38 novel human host-dependent antigens from 20 immunodominant C. trachomatis proteins, in addition to confirming 10 host-independent mouse serum peptide antigens that had been identified previously. This extended set of highly specific C. trachomatis peptide antigens can be used in simple ELISA or multiplexed microarray formats and will provide high specificity and sensitivity to human C. trachomatis serodiagnosis.

Immune dysregulation mediated by the oral microbiome: potential link to chronic inflammation and atherosclerosis

Cardiovascular disease is an inflammatory disorder characterized by the progressive formation of plaque in coronary arteries, termed atherosclerosis. It is a multifactorial disease that is one of the leading causes of death worldwide. Although a number of risk factors have been associated with disease progression, the underlying inflammatory mechanisms contributing to atherosclerosis remain to be fully delineated. Within the last decade, the potential role for infection in inflammatory plaque progression has received considerable interest. Microbial pathogens associated with periodontal disease have been of particular interest due to the high levels of bacteremia that are observed after routine dental procedures and every day oral activities, such as tooth brushing. Here, we explore the potential mechanisms that may explain how periodontal pathogens either directly or indirectly elicit immune dysregulation and consequently progressive inflammation manifested as atherosclerosis. Periodontal pathogens have been shown to contribute directly to atherosclerosis by disrupting endothelial cell function, one of the earliest indicators of cardiovascular disease. Oral infection is thought to indirectly induce elevated production of inflammatory mediators in the systemic circulation. Recently, a number of studies have been conducted focusing on how disruption of the gut microbiome influences the systemic production of proinflammatory cytokines and consequently exacerbation of inflammatory diseases such as atherosclerosis. It is clear that the immune mechanisms leading to atherosclerotic plaque progression, by oral infection, are complex. Understanding the immune pathways leading to disease progression is essential for the future development of anti-inflammatory therapies for this chronic disease.

Association of Chlamydia pneumoniae Infection With Atherosclerotic Plaque Formation

Atherosclerosis is a complex multifactorial disorder. Studies show that infectious microbial agents may play an important role in the development of atherosclerosis; however, these findings are conflicting. This study investigated the presence of Chlamydia pneumoniae DNA in atherosclerotic plaques of patients suffering from coronary artery disease. In a cross-sectional study, 85 patients (43 females and 42 males with mean age of 61±9.5, range 42-82 years) referred for coronary artery bypass grafting (CABG) and thoracic biopsy as the control groups were enrolled for this study. Standard questionnaires, including demographic and clinical evaluation were administered. Obtained specimens were processed and then nested polymerase chain reaction with primers for Pst1 fragment was carried out to detect Chlamydia pneumoniae DNA. Statistical analysis was done using the SPSS software. Of note, in 25 out of the 85 patients (29.4%), C. pneumoniae was detected within atherosclerotic plaques, whereas, 5 out of the 85 thoracic biopsy (5.9%) were positive for the presence of the mentioned bacteria in internal thoracic artery. There was a statistically significant association between atherosclerotic plaque (study group) and thoracic biopsy (control group) in terms of C. pneumoniae positivity (P=0.0001). The findings of this study support the hypothesis that C. pneumoniae is associated with atherosclerosis.

Infection of human monocytes by Chlamydia pneumoniae and Chlamydia trachomatis: an in vitro comparative study

Background

An increasing number of studies suggest that chlamydiae can infect immune cells. The altered immune cell function could contribute to the progression of several chronic inflammatory diseases.

The aim of this study was to comparatively evaluate Chlamydia pneumoniae (CP) and Chlamydia trachomatis (CT) interactions with in vitro infected human blood monocytes.

Results

Fresh isolated monocytes were infected with viable CP and CT elementary bodies and infectivity was evaluated by recultivating disrupted monocytes in permissive epithelial cells.

The production of reactive oxygen and nitrogen species was studied in the presence of specific fluorescent probes. Moreover, TNF-α, INF-α, INF-β and INF-γ gene expression was determined.

CT clearance from monocytes was complete at any time points after infection, while CP was able to survive up to 48 hours after infection. When NADPH oxydase or nitric oxide synthase inhibitors were used, CT infectivity in monocytes was restored, even if at low level, and CT recovery’s rate was comparable to CP one.

CT-infected monocytes produced significantly higher levels of reactive species compared with CP-infected monocytes, at very early time points after infection. In the same meanwhile, TNF-α and INF-γ gene expression was significantly increased in CT-infected monocytes.

Conclusions

Our data confirm that CP, but not CT, is able to survive in infected monocytes up to 48 hours post-infection. The delay in reactive species and cytokines production by CP-infected monocytes seems to be crucial for CP survival.

Impact of viral and bacterial infections in coronary artery disease patients

Atherosclerosis is becoming an alarming disease for the existence of healthy human beings in the 21^st century. There are a growing number of agents, either modernized life style generated, competitive work culture related or infection with some bacterial or viral agents, documented every year. These infectious agents do not have proper diagnostics or detection availability in many poor and developing countries. Hence, as active medical researchers, we summarize some aspects of infectious agents and their related mechanisms in this review which may be beneficial for new beginners in this field and update awareness in the field of cardiovascular biology.

Chlamydophila pneumoniae infection and cardiovascular disease

Atherosclerosis is a multifactorial vascular inflammatory process; however, the inciting cause for inflammation remains unclear. Two decades ago, Chlamydophila pneumoniae (formerly Chlamydia pneumoniae) infection was proposed as a putative etiologic agent. We performed a PubMed search using the keywords Chlamydia and atherosclerosis in a Boolean query to identify published studies on C. pneumoniae and its role in atherogenesis, and to understand research interest in this topic. We found 1,652 published articles on this topic between 1991 and 2011. We analyzed relevant published studies and found various serological, molecular, and animal modeling studies in the early period. Encouraged by positive results from these studies, more than a dozen antibiotic clinical-trials were subsequently conducted, which did not find clinical benefits of anti-Chlamydophila drug therapy. While many researchers believe that the organism is still important, negative clinical trials had a similar impact on overall research interest. With many novel mechanisms identified for atherogenesis, there is a need for newer paradigms in Chlamydophila-atherosclerosis research.

Atherosclerosis and infection: is the jury still not in?

Atherosclerosis is a chronic inflammatory process accounting for increased cardiovascular and cerebrovascular morbidity and mortality. A wealth of recent data has implicated several infectious agents, mainly Chlamydophila pneumoniae, Helicobacter pylori, CMV and periodontal pathogens, in atherosclerosis. Thus, we sought to comprehensively review the available data on the topic, exploring in particular the pathogenetic mechanisms, and discuss anticipated future directions.

Chronic Pharyngitis: Role of Atypical Organisms

Background

Bacteria including Chlamydophila pneumoniae, Mycoplasma pneumoniae, and anaerobic bacteria such as Fusobacterium necrophorum have been implicated as etiological agents of chronic pharyngitis in Western literature. Because there are no data regarding this from India, the authors undertook this study.

Study Design

Prospective case-control study.

Setting

Tertiary-level medical college and hospital.

Method

In total, 343 consecutive adults with persistent throat pain and/or irritation (duration ≥3 months) were screened for known causes of pharyngitis by a thorough clinical and endoscopic examination. In 71 patients, the evaluation performed was unable to determine any cause, and these were considered cases. An enzyme-linked immunosorbent assay test to detect IgA and IgG antibodies to C pneumoniae and M pneumoniae was performed on 66 of these cases and 62 controls. The posterior pharyngeal swabs taken from both the cases and controls were subjected to aerobic and anaerobic culture.

Results

Individuals with chronic pharyngitis had a 3.43 times odds of being seropositive for C pneumoniae as compared with controls ( P = .001; odds ratio = 3.43). Aerobic organisms and M pneumoniae did not seem to be significant etiological agents for chronic pharyngitis. On the contrary, isolation of Fusobacterium spp was found to be significantly more in controls as compared with cases.

Conclusion

This study suggests an association between IgA antibodies to C pneumoniae and chronic pharyngitis. Further studies using more specific tests combined with long-term follow-up are needed to confirm these findings.

Assessment of some inflammatory biomarkers as predictors of outcome of acute respiratory failure on top of chronic obstructive pulmonary disease and evaluation of the role of bacteria

Objective. To study the value of the inflammatory markers (interleukin-6 (IL-6), interleukin-8 (IL-8), and C-reactive protein (CRP)) in predicting the outcome of noninvasive ventilation (NIV) in the management of acute respiratory failure (ARF) on top of chronic obstructive pulmonary disease (COPD) and the role of bacteria in the systemic inflammation. Methods. Thirty three patients were subjected to standard treatment plus NIV, and accordingly, they were classified into responders and nonresponders. Serum samples were collected for IL-6, IL-8, and CRP analysis. Sputum samples were taken for microbiological evaluation. Results. A wide spectrum of bacteria was revealed; Gram-negative and atypical bacteria were the most common (31% and 28% resp.; single or copathogen). IL-8 and dyspnea grade was significantly higher in the non-responder group (P = 0.01 and 0.023 resp.). IL-6 correlated positivity with the presence of infection and type of pathogen (P = 0.038 and 0.034 resp.). Gram-negative bacteria were associated with higher significant IL-6 in comparison between others (196.4 ± 239.1 pg/dL; P = 0.011) but insignificantly affected NIV outcome (P > 0.05). Conclusions. High systemic inflammation could predict failure of NIV. G-ve bacteria correlated with high IL-6 but did not affect the response to NIV.

Periodontal disease and atherosclerotic vascular disease: does the evidence support an independent association?: a scientific statement from the American Heart Association

A link between oral health and cardiovascular disease has been proposed for more than a century. Recently, concern about possible links between periodontal disease (PD) and atherosclerotic vascular disease (ASVD) has intensified and is driving an active field of investigation into possible association and causality. The 2 disorders share several common risk factors, including cigarette smoking, age, and diabetes mellitus. Patients and providers are increasingly presented with claims that PD treatment strategies offer ASVD protection; these claims are often endorsed by professional and industrial stakeholders. The focus of this review is to assess whether available data support an independent association between ASVD and PD and whether PD treatment might modify ASVD risks or outcomes. It also presents mechanistic details of both PD and ASVD relevant to this topic. The correlation of PD with ASVD outcomes and surrogate markers is discussed, as well as the correlation of response to PD therapy with ASVD event rates. Methodological issues that complicate studies of this association are outlined, with an emphasis on the terms and metrics that would be applicable in future studies. Observational studies to date support an association between PD and ASVD independent of known confounders. They do not, however, support a causative relationship. Although periodontal interventions result in a reduction in systemic inflammation and endothelial dysfunction in short-term studies, there is no evidence that they prevent ASVD or modify its outcomes.

Chronic infections & coronary artery disease with special reference to Chalmydia pneumoniae

BACKGROUND & OBJECTIVES

Studies on cardiovascular diseases (CVD) in India have shown about 10-20 per cent of cases with no obvious risk factors, raising a suspicion of infections as a cause. There is a paucity of data on this possible role of infections. This study was, therefore, undertaken to find out the association between infection due to Chlamydia pneumoniae and other organisms and coronary artery disease (CAD).

METHODS

Patients with CAD were selected in group I (acute myocardial infarction, AMI) and group III (patients undergoing coronary artery bypass graft (CABG) surgery), and normal controls in group II. Routine biochemical, haematological and inflammatory tests [C-reactive protein (CRP), total leucocyte count (TLC), fibrinogen, ESR], serodiagnostic tests for IgA and IgG antibodies to C. pneumoniae, Helicobacter pylori, cytomegalovirus (CMV), Mycoplasma pneumoniae and Parvovirus B-19 by ELISA kits, C. pneumoniae antigen by microimmunofluorescence and PCR from endothelial tissue obtained at CABG were carried out. Aortic punch biopsies were done in patients who underwent CABG.

RESULTS

Acute MI patients had a significantly higher association with accepted cardiac risk factors, lipid profile, inflammatory and thrombogenic tests. IgG and IgA antibodies levels against C. pneumoniae were not significantly different in the controls as against the AMI group. However, C. pneumoniae antigen seropositive group had significant association with HDL cholesterol, lipid tetrad index (P<0.001) and with triglycerides. Parvovirus B antigen was detected in 8.3 per cent of tissue specimens by PCR and of 44 patients with AMI (6.8%) were also positive for parvovirus B-19 IgG antibodies.

INTERPRETATION & CONCLUSIONS

There was no direct evidence of the involvement of C. pneumoniae and other infective agents and viruses in CAD. It is possible that such infections produce an indirect adverse effect on the lipid profile.

Chlamydia pneumoniae heat shock protein 60 enhances expression of ERK, TLR-4 and IL-8 in atheromatous plaques of coronary artery disease patients

Chlamydia pneumoniae heat shock protein (cHSP) 60 is produced during chronic chlamydial infection and activate innate immune and inflammatory responses thereby contributing to atherogenesis. However, to date there is no apparent signaling cascade delineated in human atherosclerotic plaques in C. pneumoniae positive coronary artery disease (CAD) patients. Atherosclerotic plaques were obtained from 40 CAD patients (28 men, 12 women) attending Department of Cardio Thoracic and Vascular Surgery Safdarjung Hospital, New Delhi. Atherosclerotic plaques were used for gene expression studies at RNA level by real-time PCR and to study expression of ERK1/2, JNK1/2, NF-kB, IkkB and MCP-1 at protein level by immunoblotting. Significantly higher (p < 0.001) RNA expression was found for IL-8, TLR-2/4, TGF-β, ICAM1, VCAM1 and MAPKinase genes, whereas significantly lower (p < 0.001) RNA expression for SMAD4, IkkB, BRCA1 and IL-10 was detected in cHSP60-positive atheromatous plaque of CAD patients. Moreover, at proteins level pERK1/2 (p = 0.05), NF-kB (p = 0.017), MCP-1 (p = 0.011) was higher and IkkB expression was lower (p = 0.038) in cHSP60-positive atheromatous plaque of CAD patients. This study by using human atheromatous plaques at RNA and protein levels demonstrated higher expression of TLR-2/4, IL-8, ICAM1, VCAM1, ERK1/2 and NF-kB in cHSP60-positive CAD patients.

Chlamydia in canine or feline coronary arteriosclerotic lesions

BACKGROUND

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

RESULTS

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

CONCLUSIONS

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

Non-detectable Chlamydophila pneumoniae DNA in peripheral leukocytes in type 2 diabetes mellitus patients with and without carotid atherosclerosis

BACKGROUND AND OBJECTIVE

To study Chlamydophila pneumoniae DNA (CP-DNA) in leukocytes measured by real-time polymerase chain reaction (PCR) in patients with type 2 diabetes mellitus (DM2) with different degrees of atherosclerosis, a cross-sectional protocol was performed.

PATIENTS AND METHODS

We included 135 patients with DM2. Clinical, metabolic and inflammatory variables were measured. Previous clinical macrovascular disease was recorded and carotid ultrasound and real-time PCR for CP-DNA were performed.

RESULTS

Mean age was 62 (7) years and mean diabetes duration 16 (9) years; 40.7% of patients presented clinical atherosclerosis, 32.5% subclinical atherosclerosis and 26.6% no evidence of atherosclerosis. Anthropometric data were homogeneous in the three groups. Patients with clinical atherosclerosis had greater carotid intima-media thickness compared to the other two groups. No CP-DNA was detected in any patient.

CONCLUSIONS

The lack of detection of CP-DNA in blood leukocytes suggests that C. pneumoniae plays no active, systemic role in the pathogenesis of atherosclerosis in DM2 patients and is not a reliable marker of atherosclerosis in high-risk patients.

Chlamydophila pneumoniae attachment and infection in low proteoglycan expressing human lymphoid Jurkat cells

This study investigated the proteoglycan (PG)-dependent mechanism of Chlamydophila pneumoniae attachment to lymphocytic cells. Lymphoid Jurkat cells and epithelial HEp-2 cells were statically infected with C. pneumoniae (TW183). Transmission electron microscopy and assessment of inclusion-forming units indicated that the bacteria grew normally in Jurkat cells and were capable of producing secondary infection; however, they grew at a slower rate than in HEp-2 cells. RT-PCR analysis indicated that HEp-2 cells strongly expressed PG-core protein encoding genes, thereby sustaining glycosaminoglycans (GAGs), such as heparin, on the cellular surface. Similar gene expression levels were not observed in Jurkat cells, with the exception of glypican-1. Immunofluorescence analysis also supported strong heparin expression in HEp-2 cells and minimal expression in Jurkat cells, although heparan sulfate pretreatment significantly inhibited bacterial attachment to both cell types. Immunofluorescent co-staining with antibodies against chlamydial LPS and heparin did not identify bacterial and heparin co-localization on Jurkat cells. We also confirmed that when C. pneumoniae was statically infected to human CD4(+) peripheral blood lymphocytes known not expressing detectable level of heparin, the bacteria attached to and formed inclusion bodies in the cells. Thus, the attachment mechanism of C. pneumoniae to Jurkat cells with low PG expression is unique when compared with HEp-2 cells and potentially independent of GAGs such as heparin.

Impact of seropositivity to Chlamydia pneumoniae and anti-hHSP60 on cardiovascular events in hemodialysis patients

Autoimmunity to heat shock protein 60 (HSP60) has been related to atherosclerosis. Chlamydia pneumoniae (CP), the most studied infectious agent implicated in promoting atherosclerosis, produces a form of HSP60, which can induce an autoimmune response, due to high antigenic homology with human HSP60 (hHSP60). In this study, we evaluated the correlations among anti-hHSP60 antibodies, CP infection, and cardiovascular disease (CVD) in a high-risk population, such as patients undergoing hemodialysis (HD). Thirty-two patients (67.9 ± 13.9 years; male/female, 23:9) on regular HD were enrolled. Global absolute cardiovascular risk (GCR) was assessed using the Italian CUORE Project's risk charts, which evaluate age, gender, smoking habits, diabetes, systolic blood pressure, and serum cholesterol. The occurrence of cardiovascular events during a 24-month follow-up was recorded. Seropositivity to CP and the presence of anti-hHSP60 antibodies were tested by specific enzyme-linked immunosorbent assays. Inflammation was assessed by measurement of C-reactive protein (CRP) serum levels. Fifteen healthy sex and age-matched (61.9 ± 9.5 years; male/female, 11:4) subjects were the control group. Fifteen of 32 patients resulted seropositive for CP. CP + patients were older than CP-, while they did not differ for GCR, CRP, and dialytic parameters. CVD incidence was significantly higher in CP+ (9 CP+ vs 2 CP-, p < 0.05). Cox analysis recognized that the incidence of CVD was independently correlated with seropositivity to CP (HR, 7.59; p = 0.01; 95% CI = 1.63-35.4). On the other hand, there were no significant differences in anti-hHSP60 levels among CP+, CP- and healthy subjects: 18.11 μg/mL (14.8-47.8), 31.4 μg/mL (23.2-75.3), and 24.72 μg/mL (17.7-41.1), respectively. Anti-hHSP60 did not correlate to GCR, CRP, and incidence of CVD. In conclusion, our data suggest that anti-hHSP60 autoimmune response is not related to CP infection and CP-related CVD risk in HD patients.

Antibiotic resistance in Chlamydiae

There are few documented reports of antibiotic resistance in Chlamydia and no examples of natural and stable antibiotic resistance in strains collected from humans. While there are several reports of clinical isolates exhibiting resistance to antibiotics, these strains either lost their resistance phenotype in vitro, or lost viability altogether. Differences in procedures for chlamydial culture in the laboratory, low recovery rates of clinical isolates and the unknown significance of heterotypic resistance observed in culture may interfere with the recognition and interpretation of antibiotic resistance. Although antibiotic resistance has not emerged in chlamydiae pathogenic to humans, several lines of evidence suggest they are capable of expressing significant resistant phenotypes. The adept ability of chlamydiae to evolve to antibiotic resistance in vitro is demonstrated by contemporary examples of mutagenesis, recombination and genetic transformation. The isolation of tetracycline-resistant Chlamydia suis strains from pigs also emphasizes their adaptive ability to acquire antibiotic resistance genes when exposed to significant selective pressure.

Serological diagnosis of Chlamydia pneumoniae infection: limitations and perspectives

Chlamydia pneumoniae is an obligate intracellular human pathogen responsible for a wide range of acute and chronic human diseases, including pneumonia and other respiratory diseases. Serological methods for the diagnosis of C. pneumoniae infection vary widely, and several authors have reported significant inter- and intra-laboratory variability in diagnostic methods and criteria. Over the past 10 years, numerous studies have focused on the identification of specific antigens for application in serodiagnosis, including the diagnosis of persistent infections. The use of proteomics may enable the development of serological diagnosis kits that offer reliable sensitivity and specificity and might even differentiate between the various stages of infection with this pathogen.

Chlamydia pneumoniae infection and Alzheimer's disease: a connection to remember?

Alzheimer's disease (AD) is the most common cause of dementia in the elderly, whereby it is customary to distinguish between early familial FAD and late-onset AD (LOAD). The development of LOAD, the most prevalent form of AD, is believed to be a multifactorial process that may also involve infections with bacterial or viral pathogens. After the first report on the presence of Chlamydia pneumoniae (Cpn) in brains of patients with AD appeared in 1998, this bacterium has most often been implicated in AD pathogenesis. However, while some studies demonstrate a clear association between Cpn infection and AD, others have failed to confirm these findings. This might be due to heterogeneity of the specimens analyzed and lack of standardized detection methods. Additionally, non-availability of suitable chlamydial infection models severely hampers research in the field. In this review, we will critically discuss the possible role of Cpn in the pathogenesis of LOAD in light of the available data. We will also present three mutually non-exclusive hypotheses how Cpn might contribute to the pathogenesis of AD.

Chlamydia pneumoniae-induced memory CD4+ T-cell activation in human peripheral blood correlates with distinct antibody response patterns

Chlamydia pneumoniae is a frequent pathogen of the respiratory tract, and persistent infections with this obligate intracellular bacterium have been associated with different severe sequelae. Although T-cell activation during acute C. pneumoniae infections has been described, little is known about the frequency or the role of the C. pneumoniae-specific memory T cells that reside in the human body after the resolution of the infection. In the present study, the C. pneumoniae-induced T-cell responses in peripheral blood mononuclear cells of 56 healthy volunteers were analyzed and compared to the donor's serum antibody reactivity toward whole C. pneumoniae as well as recombinant C. pneumoniae antigens. Following short-term stimulation with C. pneumoniae, both gamma interferon (IFN-gamma)- and interleukin-2 (IL-2)-producing CD4(+) T-cell responses could be detected in 16 of 56 healthy individuals. C. pneumoniae-activated CD4(+) T cells expressed CD154, a marker for T-cell receptor-dependent activation, and displayed a phenotype of central memory T cells showing dominant IL-2 production but also IFN-gamma production. Interestingly, individuals with both IFN-gamma- and IL-2-producing responses showed significantly decreased immunoglobulin G reactivity toward C. pneumoniae RpoA and DnaK, antigens known to be strongly upregulated during chlamydial persistence, compared to IgG reactivity of seropositive individuals with no T-cell response or CD4(+) T-cell responses involving the production of a single cytokine (IFN-gamma or IL-2). Our results demonstrate that memory CD4(+) T cells responding to C. pneumoniae stimulation can be detected in the circulation of healthy donors. Furthermore, among seropositive individuals, the presence or the absence of dual IFN-gamma- and IL-2-producing T-cell responses was associated with distinct patterns of antibody responses toward persistence-associated C. pneumoniae antigens.

Chlamydophila pneumoniae Infection and Its Role in Neurological Disorders

Chlamydophila pneumoniae is an intracellular pathogen responsible for a number of different acute and chronic infections. The recent deepening of knowledge on the biology and the use of increasingly more sensitive and specific molecular techniques has allowed demonstration of C. pneumoniae in a large number of persons suffering from different diseases including cardiovascular (atherosclerosis and stroke) and central nervous system (CNS) disorders. Despite this, many important issues remain unanswered with regard to the role that C. pneumoniae may play in initiating atheroma or in the progression of the disease. A growing body of evidence concerns the involvement of this pathogen in chronic neurological disorders and particularly in Alzheimer's disease (AD) and Multiple Sclerosis (MS). Monocytes may traffic C. pneumoniae across the blood-brain-barrier, shed the organism in the CNS and induce neuroinflammation. The demonstration of C. pneumoniae by histopathological, molecular and culture techniques in the late-onset AD dementia has suggested a relationship between CNS infection with C. pneumoniae and the AD neuropathogenesis. In particular subsets of MS patients, C. pneumoniae could induce a chronic persistent brain infection acting as a cofactor in the development of the disease. The role of Chlamydia in the pathogenesis of mental or neurobehavioral disorders including schizophrenia and autism is uncertain and fragmentary and will require further confirmation.

Atherosclerosis, inflammation and Chlamydia pneumoniae

Coronary heart disease is the single most common cause of illness and death in the developed world. Coronary atherosclerosis is by far the most frequent cause of ischemic heart disease, and plaque disruption with superimposed thrombosis is the main cause of the acute coronary syndromes of unstable angina, myocardial infarction, and sudden death. Atherosclerosis is the result of a complex interaction between blood elements, disturbed flow, and vessel wall abnormality, involving several pathological processes: inflammation, with increased endothelial permeability, endothelial activation, and monocyte recruitment; growth, with smooth muscle cell proliferation, migration, and matrix synthesis; degeneration, with lipid accumulation; necrosis, possibly related to the cytotoxic effect of oxidized lipid; calcification/ossification, which may represent an active rather than a dystrophic process; and thrombosis, with platelet recruitment and fibrin formation. In this review we discuss these processes and the possible pathological effects of Chlamydia infection and the ensuing phlogosis.

Chlamydial lipopolysaccharide (cLPS) is present in atherosclerotic and aneurysmal arterial wall--cLPS levels depend on disease manifestation

BACKGROUND

The role of Chlamydia pneumoniae in peripheral atherosclerosis disease and abdominal aortic aneurysm (AAA) remains unclear. Chlamydial lipopolysaccharide (cLPS) detection is a method used conventionally in routine chlamydial diagnosis of gynecological or ophthalmic samples.

METHODS

We compared cLPS concentrations, as well as other markers of bacterial load, in plaques and sera of patients operated on for carotid artery stenosis (n=110), aorto-occlusive disease (n=22), or AAAs (n=50) at the Helsinki University Central Hospital.

RESULTS

The median levels of cLPS in plaques were 2.28, 0.80, and 0.29 ng/ml in AAA, aorto-occlusive disease, and carotid artery stenosis patients, respectively (P<.001, Kruskal-Wallis). cLPS in serum correlated with LPS binding protein levels (Spearman's rho=0.52, P<.001), suggesting that the presence of chlamydiae is sufficient to produce an innate immune response reaction in these patients. Serum inflammatory markers interleukin 6 and highly sensitive C-reactive protein also correlate with cLPS (Spearman's rho=0.42 and 0.51, respectively, P<.001).

CONCLUSIONS

cLPS is present in arterial disease, and the potential role of C. pneumoniae in the pathogenesis of both peripheral atherosclerosis disease and AAA should not be forgotten. cLPS has a positive correlation with serum inflammatory markers, but this is no proof of a causal association.

Host cell cytokines induced by Chlamydia pneumoniae decrease the expression of interstitial collagens and fibronectin in fibroblasts

Chlamydia pneumoniae infection has been associated with chronic obstructive airway disease (COPD), asthma, and atherosclerosis. Inflammation and airway remodeling in asthma and COPD result in subepithelial fibrosis that is characterized by the deposition of interstitial collagens and fibronectin. The progression of atherosclerosis is also accompanied by an increased production of interstitial collagens in the intima. As shown by reverse transcription-PCR and immunoblotting, infection of human fibroblasts and smooth muscle cells by C. pneumoniae TW-183 downregulated the expression of type I and III collagen and fibronectin, whereas the level of type IV collagen remained unchanged. Conditioned medium from infected fibroblasts as well as epithelial WISH cells also reduced the expression of interstitial collagens and fibronectin in uninfected cells. In experiments using blocking antibodies, beta interferon was found to contribute to the inhibitory effects of conditioned medium collected from infected fibroblasts. In contrast, downregulation of matrix protein expression by conditioned medium from epithelial cells was caused by interleukin-1alpha, which was not secreted from fibroblasts following chlamydial infection. C. pneumoniae-mediated inhibition of collagen and fibronectin expression was diminished following transfection of fibroblasts with specific small interfering RNA targeting the transcription factor CCAAT/enhancer-binding protein beta. The downregulation of interstitial collagens and fibronectin by the Chlamydia-induced host cell cytokine response may modulate tissue remodeling processes in airway diseases. In atherosclerosis the inhibition of collagen synthesis by C. pneumoniae infection may promote plaque vulnerability, thereby increasing the risk of plaque rupture.

Inhibition of lymphocyte CD3 expression by Chlamydophila pneumoniae infection

Since lymphocytes are a major immune cell besides macrophages in the development of atherosclerosis, interaction between lymphocytes and Chlamydophila pneumoniae may contribute to the pathogenesis of chronic inflammatory diseases associated with C. pneumoniae. In this regard, we examined a possible alteration of CD3 expression of human lymphocyte Molt-4 cells by C. pneumoniae infection. The expression levels of CD3 molecules of lymphocyte Molt-4 cells were significantly decreased by C. pneumoniae infection. In contrast, heat-killed C. pneumoniae as well as mock (cell lysates) did not cause any alteration of CD3 expression of the cells. Treatment of the infected cells with NS-398 (cyclo-oxyganase-2 inhibitor) or AH-23848 (EP(4) prostanoid receptor antagonist) abolished the inhibition of CD3 expression. The enhanced prostaglandin E(2) (PGE(2)) productions in the culture supernatants of infected cells were confirmed by competitive enzyme-immunosorbent assay (ELISA). C. pneumoniae infection of enriched lymphocytes from human peripheral blood mononuclear cells also induced a decrease of CD3 expression. Thus, C. pneumoniae infection of lymphocytes induces a decrease of CD3 expression mediated by possibly PGE(2) production.

Immunoproteomic identification and serological responses to novel Chlamydia pneumoniae antigens that are associated with persistent C. pneumoniae infections

The controversial discussion about the role of Chlamydia pneumoniae in atherosclerosis cannot be solved without a reliable diagnosis that allows discrimination between past and persistent infections. Using a proteomic approach and immunoblotting with human sera, we identified 31 major C. pneumoniae Ags originating from 27 different C. pneumoniae proteins. More than half of the proteins represent Chlamydia Ags not described previously. Using a comparative analysis of spot reactivity Pmp6, OMP2, GroEL, DnaK, RpoA, EF-Tu, as well as CpB0704 and CpB0837, were found to be immunodominant. The comparison of Ab-response patterns of sera from subjects with and without evidence for persisting C. pneumoniae, determined by multiple PCR analysis of PBMC and vasculatory samples, resulted in differential reactivity for 12 proteins, which is not reflected by reactivity of the sera in the microimmunofluorescence test, the current gold standard for serodiagnosis. Although reactivity of sera from PCR-positive donors was increased toward RpoA, MOMP, YscC, Pmp10, PorB, Pmp21, GroEL, and Cpaf, the reactivity toward YscL, Rho, LCrE, and CpB0837 was decreased, reflecting the altered protein expression of persisting C. pneumoniae in vitro. Our data provide the first evidence of a unique Ab-response pattern associated with persistent C. pneumoniae infections, which is a prerequisite for the serological determination of persistently infected patients.

A meta-analysis of antibiotic use for the secondary prevention of cardiovascular diseases

BACKGROUND

A number of clinical trials have examined whether antibiotics decrease the incidence of adverse events in patients with cardiovascular diseases. However, results have occasionally been conflicting, and a meta-analysis may provide additional clarification.

OBJECTIVE

To address whether antibiotic use can reduce the risk of future cardiac events among patients with established cardiovascular diseases.

METHODS

PubMed and the Cochrane Central Register of Controlled Trials were searched using the key words "antibiotic" and "cardiovascular diseases". Only randomized, placebo-controlled trials of patients with established cardiovascular disease and reporting cardiovascular outcomes were included. A random effects model was used and a fixed model was applied for sensitivity analysis.

RESULTS

A total of 393 papers published between January 1, 1994, and April 31, 2006, were initially identified. Thirteen trials (12,491 patients in the treatment group and 12,518 patients in the control group) were retained and included in the present meta-analysis. The pooled RR for the composite event end point, including death, myocardial infarction admission and unplanned revascularization procedures, was 0.96 (95% CI 0.90 to 1.04). No associations were seen for the individual outcomes of mortality (RR 1.07, 95% CI 0.96 to 1.19) or myocardial infarction/unstable angina (RR 0.96, 95% CI 0.85 to 1.07). Subgroup analyses based on patient populations (stable or unstable), type of antibiotics, or restricted to those with immunoglobulin G Chlamydia pneumoniae antibodies were also negative for a beneficial treatment effect. Similar results were found using a fixed effects model.

CONCLUSIONS

The meta-analysis did not provide evidence of an association between antibiotic use and the secondary prevention of cardiac events. Further research in this area does not appear to be promising.

Comparison of polymerase chain reaction methods, in situ hybridization, and enzyme immunoassay for detection of Chlamydia pneumoniae in atherosclerotic carotid plaques

Chlamydia pneumoniae has been associated with cardiovascular diseases and has been shown by different methods to be present in atherosclerotic lesions. However, not all studies have found C. pneumoniae in atherosclerotic tissues. We compared polymerase chain reaction (PCR) methods, in situ hybridization (ISH), and measurement of chlamydial lipopolysaccharide (cLPS) by enzyme immunoassay (EIA) from homogenized atherosclerotic tissue in the detection of C. pneumoniae. In a study population of 110 patients with carotid artery disease, cLPS was found in 22.2%, and DNA by PCR was found in 34.3% and by ISH in 39.4% of the samples. Poor repeatability was shown to complicate PCR, and the technical problems inherent in ISH were not insignificant. In contrast, the cLPS EIA test was fast and easy to perform. If the sensitivity could be increased, for example, by testing multiple tissue pieces, cLPS EIA might provide a standardized commercial method for the detection of chlamydia in tissue samples, and it, thus, merits further characterization and validation in different patient populations.

Chlamydophila pneumoniae derived from inclusions late in the infectious cycle induce aponecrosis in human aortic endothelial cells

BACKGROUND

Atherosclerosis is still the leading cause of death in the western world. Besides known risk factors studies demonstrating Chlamydophila pneumoniae (C. pneumoniae) to be implicated in the progression of the disease, little is known about C. pneumoniae infection dynamics. We investigated whether C. pneumoniae induce cell death of human aortic endothelial cells, a cell type involved in the initiation of atherosclerosis, and whether chlamydial spots derive from inclusions.

RESULTS

Lactate dehydrogenase release revealed host cell death to be dependent on the amounts of Chlamydia used for infection. The morphology of lysed human aortic endothelial cells showed DNA strand breaks simultaneously with cell membrane damage exclusively in cells carrying Chlamydia as spots. Further ultrastructural analysis revealed additional organelle dilation, leading to the definition as aponecrotic cell death of endothelial cells. Exclusive staining of the metabolic active pathogens by chlamydial heat shock protein 60 labelling and ceramide incorporation demonstrated that the bacteria responsible for the induction of aponecrosis had resided in former inclusions. Furthermore, a strong pro-inflammatory molecule, high mobility group box protein 1, was shown to be released from aponecrotic host cells.

CONCLUSION

From the data it can be concluded that aponecrosis inducing C. pneumoniae stem from inclusions, since metabolically active bacterial spots are strongly associated with aponecrosis late in the infectious cycle in vascular endothelial cells and metabolic activity was exclusively located inside of inclusions in intact cells. Vice versa initial spot-like infection with metabolically inert bacteria does not have an effect on cell death induction. Hence, C. pneumoniae infection can contribute to atherosclerosis by initial endothelial damage.

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.

Implications of antibodies to heat-shock proteins in ischemic heart disease

OBJECTIVE

Experimental studies illustrate that priming with infectious agents, like Chlamydia pneumoniae, is involved in plaque formation and progression based on molecular mimicry with host heat-shock proteins (HSP). We have here evaluated the hypothesis that C. pneumoniae contributes to atherosclerotic disease progression via anti-HSP antibodies.

METHODS

The blood circulation of 151 consecutive patients with ischemic heart disease was screened for antibodies against human and Chlamydia HSP60 and C. pneumoniae IgG. Antibody levels were associated with the angiographic extent of coronary atherosclerosis, with clinical symptoms of ischemic heart disease and with biochemical and functional endothelial dysfunction markers.

RESULTS

Positive serology to human (11%) or Chlamydia HSP60 (22%) was not associated with the presence and extent of atherosclerosis, neither was it related with endothelial dysfunction. Patients with acute myocardial infarction had significantly lower Chlamydia HSP60 antibody levels (median OD 0.12, range: 0.02-0.75) than patients with stable (median OD 0.22, range: 0.02-2.67) or unstable angina pectoris (median OD 0.24, range: 0-2.48) (p=0.032). Subjects with positive C. pneumoniae IgG serology (if measured at a titre of 1:128) showed reduced flow-mediated vasodilation (p=0.024), but vasodilation responses did not differ in single-, two- or three-vessel disease.

CONCLUSION

Overall, antibody responses to C. pneumoniae IgG, human or Chlamydia HSP60 are not associated with endothelial dysfunction and presence and severity of coronary artery disease, arguing against the suggestion that infection contributes to disease progression and supplying additional proof that C. pneumoniae is an unlikely major risk factor of coronary atherosclerosis.

A multiplex PCR assay for the detection of respiratory bacteriae in nasopharyngeal smears from children with acute respiratory disease

To elucidate the frequency of infections with pathogenic respiratory bacteriae during an inter-epidemic period a multiplex PCR assay was used to screen nasopharyngeal smears for the presence of DNA specific for Bordetella pertussis, Bordetella parapertussis, Chlamydophila pneumoniae and Mycoplasma pneumoniae. 187 samples from children aged 2-14 y were analysed with this method in addition to classical bacteriology and compared to results obtained with commercially available PCR kits for each single parameter. From 82 samples positive by bacteriology, 8 (4.3%) were also positive by PCR, whereas from 105 negative samples, 12 (6.4%) were positive only by PCR. From the total of 20 samples positive by PCR, 4 were found to be positive for M. pneumoniae, 6 for B. pertussis, 3 for B. parapertussis and 7 for both B. pertussis and B. parapertussis. Multiplex PCR is a very useful approach for the diagnosis of bacterial infections not detectable by classical bacteriology. In some patients, PCR was the only method giving a positive result, and in others double infections were diagnosed only because of the PCR contribution. Combination of classical bacteriology with multiplex PCR allows a precise diagnosis of infections in the upper respiratory tract, resulting in a more effective therapy.

Endothelial cells are protected against phagocyte-transmitted Chlamydophila pneumoniae infections by laminar shear stress Gueinzius: Shear stress protects from C. pneumoniae infection

The respiratory pathogen Chlamydophila pneumoniae can be detected in atherosclerotic vessels, but the mechanism of dissemination from lung to vasculature remains unknown. Disturbance of vascular shear stress is a risk factor for atherosclerosis. We investigated whether polymorphonuclear neutrophils (PMN) might serve as carriers, transmitting C. pneumoniae to endothelial cells and how this is affected by shear stress. PMN were prepared from blood and incubated with C. pneumoniae. Real-time PCR and Pathfinder staining showed that after 1h, 20% of C. pneumoniae were ingested and started to form inclusions. When infected PMN were co-incubated with HUVEC for 96h, 10% of PMN-ingested C. pneumoniae were transmitted to HUVEC as shown by PCR and confocal microscopy. Infection of HEp-2 cells with C. pneumoniae harvested from HUVEC resulted in C. pneumoniae replication and confirmed that the bacteria remained infective. Exposure to laminar shear stress in a rotating cone-and-plate apparatus did not affect the transmission of C. pneumoniae from PMN to HUVEC, but led to a 75% reduction of inclusion formation. This can explain the focal distribution of C. pneumoniae in the vasculature and links two risk factors of atherosclerosis, i.e. the lack of laminar flow and infection.

Lack of association between Chlamydophila pneumoniae seropositivity and abdominal aortic aneurysm

Chronic Chlamydophila pneumoniae infection has been suggested as a possible contributing factor for the development and expansion of abdominal aortic aneurysm (AAA). The relevance of C pneumoniae involved in the processes underlying aneurysmal rupture is unknown. The aim of this study was to examine the relationship between C pneumoniae seropositivity and AAA rupture. In a case-control study, 119 patients with AAA and 36 matched controls were prospectively investigated with C pneumoniae serology. Patients with ruptured AAA have similar levels of IgG antibodies against C pneumoniae as patients with an electively operated AAA, a small AAA, and controls. In conclusion, this study fails to demonstrate a connection between C pneumoniae seropositivity and AAA rupture.

Environmental vascular risk factors: new perspectives for stroke prevention

Despite intensive evaluation of acute stroke patients, perhaps only half of the attributable stroke risk is usually identified. In addition to traditional and non-traditional vascular risk factors-including most recently homocysteine, inflammation, and alterations of coagulation-a number of environmental risk factors for stroke have been identified in the last decade. In this update we review the following: lower education and poor socioeconomic status (probable surrogates for exposure to traditional high-risk behaviors such as smoking, poor nutrition, lack of prenatal control, absence of preventive medical and dental care, and non-compliance of treatment of conditions such as hypertension); depression, stress and affective disorders; obstructive sleep apnea; passive smoking and environmental pollution; infections, in particular periodontal diseases that increase C-reactive protein (CRP); raised body mass index (obesity); exercise, and diet. The possible role of high-fructose corn syrup in the epidemic of obesity in the USA is reviewed. Protective diets include higher consumption of fish, olive oil, grains, fruits and vegetables (Mediterranean diet), as well as probiotic bacteria in yogurt and dairy products. Careful attention should be given to the patient's environment looking for modifiable factors. The effects of clean environmental air and water, adequate diet and appropriate nutrition, healthy teeth, exercise, and refreshing sleep in the prevention of stroke and cardiovascular disease appear to be quite compelling. Although some of these modifiable risk factors lack evidence-based information, judicious clinical sense should be used to counteract the potentially damaging effects of adverse environmental vascular risk factors.

No detectable Chlamydia pneumoniae and cytomegalovirus DNA in leukocytes in subjects with echolucent and echogenic carotid artery plaques

BACKGROUND

Controversy exists whether persistent Chlamydia pneumoniae or cytomegalovirus infections cause initiation or progression of atherosclerosis. C. pneumoniae DNA in peripheral blood mononuclear cells (PBMC) has been proposed to be a more reliable marker of cardiovascular risk than are C. pneumoniae antibodies. Reported prevalences of C. pneumoniae DNA among cardiovascular patients vary greatly, indicating methodological limitations. There is an increasing concern that published results may have been biased by extensive use of less specific polymerase chain reaction (PCR) technology.

METHODS

C. pneumoniae DNA and cytomegalovirus DNA were determined by probe-based real-time PCR technology in PBMCs among subjects with echolucent (n=29) or echogenic (n=28) carotid artery plaques, and in controls without carotid plaques (n=38), all recruited from a population-based study. Samples were examined in multiple repeats with PCR assays targeting two different sequences of the genome for both microorganisms.

RESULTS AND CONCLUSION

IgG seropositivity was frequent in all three groups, confirming previous exposure, but C. pneumoniae DNA or cytomegalovirus DNA was not detected in a single PBMC sample by means of probe-based, highly sensitive, and specific real-time PCR assays. Our results indicate that persistent C. pneumoniae or CMV infection is not a common phenomenon in subjects with carotid atherosclerosis.

Chlamydiae and Atherosclerosis: Can Psittacine Cases Support the Link?

Atherosclerosis is a common disease in pet birds, particularly in psittacines. Little is known about the role of risk factors predisposing birds to this disease. In our study, we tried to detect chlamydiae in formalin-fixed and paraffin-embedded atherosclerotic tissue from 103 pet birds to clarify their role in atherosclerosis. Methods used were polymerase chain reaction (PCR), sequencing, and immunohistochemistry. Histopathologic examination served to classify the extent of atherosclerotic lesions. In the PCR, 4 (3.9%) of 103 cases, all of them with advanced stages of atherosclerosis, were positive. Subsequent sequence analysis revealed high identities (94%-100%) with Chlamydophila psittaci in three cases. Interestingly, two of these birds came from C. psittaci-infected populations. Because of the low incidence (3.9%), the occurrence only in advanced stages, and the association with C psittaci-infected avian populations, a causal relationship between chlamydiae and atherosclerosis in pet birds is rather improbable.

NF-kappaB and inhibitor of apoptosis proteins are required for apoptosis resistance of epithelial cells persistently infected with Chlamydophila pneumoniae

Infection with Chlamydophila pneumoniae (Cpn) renders host cells resistant to apoptosis induced by a variety of stimuli. While modulation of apoptosis has been extensively studied in cells acutely infected with Cpn, very little is known on how persistent chlamydial infection influences host cell survival. Here we show that epithelial cells persistently infected with Cpn resist apoptosis induced with TNFalpha or staurosporine. Cpn induced the activation of nuclear factor kappa B (NF-kappaB) and inhibition of NF-kappaB with a chemical inhibitor or by silencing expression of the p65 subunit sensitized infected cells for apoptosis induction by staurosporine or TNFalpha. Persistent infection resulted in the upregulation of the NF-kappaB regulated inhibitor of apoptosis protein 2 (cIAP-2) but not inhibitor of apoptosis protein 1 (cIAP-1). Interestingly, silencing of either cIAP-1 or cIAP-2 sensitized infected cells, suggesting that IAPs play an important role in the apoptosis resistance of persistently infected cells.

Iron enhances endothelial cell activation in response to Cytomegalovirus or Chlamydia pneumoniae infection

BACKGROUND

Chronic inflammation has been implemented in the pathogenesis of inflammatory diseases like atherosclerosis. Several pathogens like Chlamydia pneumoniae (Cp) and cytomegalovirus (CMV) result in inflammation and thereby are potentially artherogenic. Those infections could trigger endothelial activation, the starting point of the atherogenic inflammatory cascade. Considering the role of iron in a wide range of infection processes, the presence of iron may complicate infection-mediated endothelial activation.

MATERIALS AND METHODS

Endothelial intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and endothelial selectin (E-selectin) expression were measured using flow cytometry, as an indication of endothelial activation. Cytotoxicity was monitored using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Immunostaining was applied to measure Cp and CMV infectivity to endothelial cells.

RESULTS

An increased number of infected endothelial cells in a monolayer population leads to a raised expression of adhesion molecules of the whole cell population, suggesting paracrine interactions. Iron additively up-regulated Cp-induced VCAM-1 expression, whereas synergistically potentiated Cp-induced ICAM-1 expression. Together with CMV, iron also enhanced ICAM-1 and VCAM-1 expression. These iron effects were observed without modulation of the initial infectivity of both microorganisms. Moreover, the effects of iron could be reversed by intracellular iron chelation or radical scavenging, conforming modulating effects of iron on endothelial activation after infections.

CONCLUSIONS

Endothelial response towards chronic infections depends on intracellular iron levels. Iron status in populations positive for Cp or CMV infections should be considered as a potential determinant for the development of atherosclerosis.