Chlamydia pneumoniae: risk factors for seropositivity and association with coronary heart disease

Endobiogeny: a global approach to systems biology (part 1 of 2)

Endobiogeny is a global systems approach to human biology that may offer an advancement in clinical medicine based in scientific principles of rigor and experimentation and the humanistic principles of individualization of care and alleviation of suffering with minimization of harm. Endobiogeny is neither a movement away from modern science nor an uncritical embracing of pre-rational methods of inquiry but a synthesis of quantitative and qualitative relationships reflected in a systems-approach to life and based on new mathematical paradigms of pattern recognition.

Statistical genetic analysis of serological measures of common, chronic infections in Alaska Native participants in the GOCADAN study

This paper describes genetic investigations of seroreactivity to five common infectious pathogens in the Genetics of Coronary Artery Disease in Alaska Natives (GOCADAN) study. Antibody titers and seroprevalence were available for 495 to 782 (depending on the phenotype) family members at two time points, approximately 15 years apart, for Chlamydophila pneumoniae, Helicobacter pylori, cytomegalovirus (CMV), herpes simplex virus 1 (HSV-1), and herpes simplex virus 2 (HSV-2). Seroprevalence rates indicate that infections with most of these pathogens are common (≥20% for all of them, >80% for H. pylori, CMV, and HSV-1). Seropositive individuals typically remain seropositive over time, with seroreversion rates of <1% to 10% over ∼15 years. Antibody titers were significantly heritable for most pathogens, with the highest estimate being 0.61 for C. pneumoniae. Significant genome-wide linkage evidence was obtained for C. pneumoniae on chromosome 15 (logarithm of odds, LOD score of 3.13). These results demonstrate that individual host genetic differences influence antibody measures of common infections in this population, and further investigation may elucidate the underlying immunological processes and genes involved.

TLR4 antagonist reduces early-stage atherosclerosis in diabetic apolipoprotein E-deficient mice

Although it has been reported that deficiency of toll-like receptor 4 (TLR4) is associated with reduced atherosclerosis in atherosclerosis-prone mice and attenuated pro-inflammatory state in diabetic mice, it remains undetermined whether treatment with a TLR4 antagonist reduces atherosclerosis in nondiabetic or diabetic mice that have TLR4 expression. In this study, we determined the effect of Rhodobacter sphaeroides lipopolysaccharide (Rs-LPS), an established TLR4 antagonist, on early-stage atherosclerosis in nondiabetic and streptozotocin-induced diabetic apolipoprotein E-deficient (Apoe(-/-)) mice. Analysis of atherosclerotic lesions of both en face aortas and cross sections of aortic roots showed that administration of Rs-LPS in 14-week-old diabetic Apoe(-/-) mice for 10 weeks significantly reduced atherosclerotic lesions. Although atherosclerotic lesions in nondiabetic Apoe(-/-) mice appeared to be decreased by Rs-LPS treatment, the difference was not statistically significant. Metabolic study showed that Rs-LPS significantly lowered serum levels of cholesterol and triglycerides in nondiabetic mice but not in diabetic mice. Furthermore, immunohistochemistry studies showed that Rs-LPS inhibited the expression of interleukin 6 and matrix metalloproteinase-9 and reduced the content of monocytes and macrophages in atherosclerotic plaques. Taken together, this study demonstrated for the first time that TLR4 antagonist inhibited vascular inflammation and atherogenesis in diabetic Apoe(-/-) mice and lowered serum cholesterol and triglyceride levels in nondiabetic Apoe(-/-) mice.

Human immunodeficiency virus, atherosclerosis and Chlamydophila pneumoniae

Chlamydophila pneumoniae (C. pneumoniae) is an obligate, intracellular bacterium associated with a wide variety of acute and chronic diseases. C. pneumoniae infection is characterized by persistence and immunopathological damage to host target tissues, including the lung. Over the past 20 years, a variety of studies have investigated a possible link between C. pneumoniae infection and atherosclerosis, because of its role in all stages of atherosclerosis, from initial inflammatory lesions to plaque rupture. In the current highly active antiretroviral therapy (HAART) era, many human immunodeficiency virus (HIV)-infected patients are experiencing health problems that accompany the aging process, mainly the risk of cardiovascular disease (CVD). There is renewed interest in a link between atherosclerotic CVD and as yet poorly defined environmental exposures, including infectious agents. On the one hand, the patient with HIV and lipodystrophy caused by HAART and exacerbated by C. pneumoniae infection could be a factor of risk for atherosclerosis. An assessment of the therapy against C. pneumoniae and HAART should always be conducted. It is advisable that HIV-acquired immune deficiency syndrome patients undergo a serological test to determine exposure to C. pneumoniae and to assess treatment options. On the other hand, in patients with a positive serology to C. pneumoniae, an increment of the body mass index has been found; therefore, it is probable that the recurrent infection may play an important role in creating adverse endothelial conditions allowing the infection by C. pneumoniae in its chronic form, to damage the endothelial surface. Vascular studies would be necessary for corroboration.

Seroprevalence of 13 common pathogens in a rapidly growing U.S. minority population: Mexican Americans from San Antonio, TX

Background

Infection risks vary among individuals and between populations. Here we present information on the seroprevalence of 13 common infectious agents in a San Antonio-based sample of Mexican Americans. Mexican Americans represent the largest and most rapidly growing minority population in the U.S., and they are also considered a health disparities population.

Methods

We analyzed 1227 individuals for antibody titer to Chlamydophila pneumoniae, Helicobacter pylori, Toxoplasma gondii, cytomegalovirus, Epstein-Barr virus, herpes simplex virus-1, herpes simplex virus-2 (HSV-2), human herpesvirus-6 (HHV-6), varicella zoster virus (VZV), adenovirus-36, hepatitis A virus, and influenza A and B. Seroprevalence was examined as a function of sex, age, household income, and education.

Results

Seroprevalence estimates ranged from 9% for T. gondii to 92% for VZV, and were similar in both sexes except for HSV-2, which was more prevalent in women. Many pathogens exhibited a significant seroprevalence change over the examined age range (15-94 years), with 7 pathogens increasing and HHV-6 decreasing with age. Socioeconomic status significantly correlated with serostatus for some pathogens.

Conclusions

Our findings demonstrate substantial seroprevalence rates of these common infections in this sample of Mexican Americans from San Antonio, Texas that suffers from high rates of chronic diseases including obesity and type-2 diabetes.

Persistent Chlamydia Pneumoniae serology is related to decline in lung function in women but not in men. Effect of persistent Chlamydia pneumoniae infection on lung function

BACKGROUND

Chlamydia pneumoniae (C pn) infection causes an acute inflammation in the respiratory system that may become persistent, but little is known about the long-term respiratory effects of C pn infections.

AIM

To estimate the long term respiratory effects of C pn with change in forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) as a main outcome variable.

METHODS

The study comprised of 1109 subjects (500 men and 609 women, mean age 28 ± 6 years) that participated in the Reykjavik Heart Study of the Young. Spirometry and blood samples for measurements of IgG antibodies for C pn were done at inclusion and at the end of the follow-up period (mean follow-up time 27 ± 4 years).

RESULTS

Having IgG against C pn at both examinations was significantly associated to a larger decrease in FEV1 (6 mL/year) and FVC (7 mL/year) in women but not in men. In women the association between C pn and larger FEV1 decline was only found in women that smoked at baseline where having C pn IgG was associated with 10 mL/year decline compared to smokers without C pn IgG. These results were still significant after adjustment for age, smoking and change in body weight.

CONCLUSION

Our results indicate that persistent C pn serology is related to increased decline in lung function in women but not in men. This effect was, however, primarily found in smoking women. This study is a further indication that the pathophysiological process leading to lung impairment may differ between men and women.

Chronic infection in the etiology of atherosclerosis--the case for Chlamydia pneumoniae

Established cardiovascular risk factors do not fully explain the variations in the prevalence and severity of coronary heart disease. Recent evidence suggests that common chronic infections may contribute, either by direct or indirect mechanisms, to the etiology and/or progression of coronary atherosclerosis. Of the candidate infectious agents implicated, Chlamydia pneumoniae has emerged as the most likely pathogen to have a causal role. Evidence for this is based on seroepidemiologic, pathologic, and laboratory-based evidence, in addition to recent small-scale antibiotic intervention studies. Concerted efforts are now focused on the design of large prospective trials with antibiotics active against C. pneumoniae in the secondary prevention of coronary heart disease.

Atypical pneumonias: current clinical concepts focusing on Legionnaires' disease

PURPOSE OF REVIEW

This review provides clinicians with an overview of the clinical features of the atypical pneumonias. Atypical community-acquired pneumonia pathogens cause systemic infections with pneumonia. The key to the clinical diagnosis of atypical pneumonias depends on recognizing the characteristic pattern of extrapulmonary organ involvement different for each pathogen. As Legionella is likely to present as severe pneumonia and does not respond to beta-lactams, it is important to presumptively diagnose Legionnaires' disease clinically so that Legionella coverage is included in empiric therapy. This study reviews the clinical features and nonspecific laboratory markers of atypical pathogens, focusing on Legionnaires' disease.

RECENT FINDINGS

Case reports/outbreaks increase our understanding of Legionnaires' disease transmission. Both Mycoplasma pneumoniae and Chlamydophilia pneumoniae may cause asthma. Antimicrobial therapy of Chlamydophilia pneumoniae/Mycoplasma pneumoniae is important to decrease person-to-person spread and to decrease potential long-term sequelae.

SUMMARY

Atypical pulmonary pathogens cause systemic infections accompanied by a variety of characteristic extrapulmonary features. Clinically, it is possible to differentiate Legionnaires' disease from the other typical/atypical pneumonias. Rapid clinical diagnosis of atypical pathogens, particularly Legionnaires' disease, is important in selecting effective empiric therapy and prompting definitive laboratory testing.

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.

Presence and severity of Chlamydia pneumoniae and Cytomegalovirus infection in coronary plaques are associated with acute coronary syndromes

Although an association between Chlamydia pneumoniae (Cpn) or Cytomegalovirus (CMV) infection and coronary atherosclerosis has been reported, such an association is less clear for acute coronary syndromes (ACS). The purpose of this study was to investigate the pathogenic roles of Cpn and CMV infection of coronary plaques in ACS. We divided 38 coronary plaque specimens obtained from 38 patients who underwent directional coronary atherectomy or thrombectomy into an ACS group (n = 21) and a non-ACS group (n = 17). Cpn and CMV in specimens were stained using immunohistochemical techniques and analyzed quantitatively. The detection rate for either Cpn- or CMV-positive cells in ACS patients was slightly higher compared with non-ACS patients. Detection rates for both Cpn- and CMV-positive cells were significantly higher in ACS patients than in non-ACS patients (P = 0.010). Furthermore, the density of Cpn- and CMV-positive cells in plaques was significantly higher in ACS patients than in non-ACS patients (P < 0.003). The results indicate that the presence and severity of Cpn and CMV infection in coronary plaques are greater in patients with ACS compared with non-ACS patients. We conclude that infection with Cpn and CMV in coronary plaques may be involved in the pathogenesis of ACS.

Relationship between periodontal infections and systemic disease

Oral conditions such as gingivitis and chronic periodontitis are found worldwide and are among the most prevalent microbial diseases of mankind. The cause of these common inflammatory conditions is the complex microbiota found as dental plaque, a complex microbial biofilm. Despite 3000 years of history demonstrating the influence of oral status on general health, it is only in recent decades that the association between periodontal diseases and systemic conditions such as coronary heart disease and stroke, and a higher risk of preterm low birth-weight babies, has been realised. Similarly, recognition of the threats posed by periodontal diseases to individuals with chronic diseases such as diabetes, respiratory diseases and osteoporosis is relatively recent. Despite these epidemiological associations, the mechanisms for the various relationships remain unknown. Nevertheless, a number of hypotheses have been postulated, including common susceptibility, systemic inflammation with increased circulating cytokines and mediators, direct infection and cross-reactivity or molecular mimicry between bacterial antigens and self-antigens. With respect to the latter, cross-reactive antibodies and T-cells between self heat-shock proteins (HSPs) and Porphyromonas gingivalis GroEL have been demonstrated in the peripheral blood of patients with atherosclerosis as well as in the atherosclerotic plaques themselves. In addition, P. gingivalis infection has been shown to enhance the development and progression of atherosclerosis in apoE-deficient mice. From these data, it is clear that oral infection may represent a significant risk-factor for systemic diseases, and hence the control of oral disease is essential in the prevention and management of these systemic conditions.

Azithromycin for the secondary prevention of coronary artery disease: a meta-analysis

PURPOSE

A meta-analysis of randomized, controlled trials that evaluated the effect of the macrolide antibiotic, azithromycin, on clinical outcomes in patients with coronary artery disease (CAD) was conducted.

METHODS

A systematic literature search of MEDLINE, EMBASE, Web of Science, and the Cochrane Database of Systematic Reviews was conducted using specific search terms. Randomized, controlled trials comparing azithromycin or placebo in secondary CAD patients with adequately reported data on mortality and clinical cardiac endpoints were included. A random-effects model was used.

RESULTS

Six studies (n=13,778) met the inclusion criteria. The trials varied in their design. On meta-analysis, azithromycin resulted in a nonsignificant reduction in mortality versus placebo (odds ratio [OR], 0.91; 95% confidence interval [CI], 0.77-1.09; p=0.31). Four trials reported the rate of nonfatal myocardial infarction (MI). Azithromycin did not have an effect on the rate of nonfatal MI versus placebo (OR, 0.95; 95% CI, 0.80-1.13; p=0.57). Five trials reported rates of hospitalization in which no significant difference was seen with azithromycin versus placebo (OR, 0.97; 95% CI, 0.80-1.17; p=0.76). Six trials were used to evaluate the composite cardiovascular endpoint. Again, no significant benefit was seen with azithromycin versus placebo (OR, 0.93; 95% CI, 0.84-1.03; p=0.218).

CONCLUSION

Meta-analysis showed that azithromycin does not appear to reduce the frequency of recurrent cardiac events in patients with CAD. Results from ongoing trials may clarify the role of azithromycin in the secondary prevention of coronary events.

Protective effect of doxycycline use on coronary artery disease?

OBJECTIVES

The potential role of Chlamydia pneumoniae infection in the pathogenesis of atherosclerosis has received increasing attention. The present study was conducted to test the hypothesis that use of doxycycline in doses prescribed in routine clinical practice for brucellosis, decreases the risk of coronary artery disease (CAD).

METHODS

A general practice (GP) database in Western Greece was used. One hundred and twenty-nine newly diagnosed patients with coronary artery disease from 2001 to 2003 were contrasted to 196 controls randomly selected from the same practice. General practice records were reviewed to confirm a diagnosis of incident CAD event and obtain information on other cardiovascular risk factors. CAD events were defined as: Stable/unstable angina, acute myocardial infarction or ischemic death.

RESULTS

The results indicate a significant association between doxycycline use and occurrence of CAD (OR: 0.37, 95% CI: 0.17-0.78).

CONCLUSIONS

These results persisted when adjustment for potential confounding factors was made. The findings should be interpreted cautiously because of lack of information about C. pneumoniae infection. However, the results suggest directions for future epidemiologic studies in this relatively uncharted field.

Association of HLA-DRB3*0202 and serum IgG antibodies to Chlamydia pneumoniae with essential hypertension in a highly homogeneous population from Majorca (Balearic Islands, Spain)

Separate studies investigating the relationship of essential hypertension (EH) with the HLA system and with Chlamydia pneumoniae (C. pneumoniae) infection have given conflicting results. Our aim was to clarify these relationships and determine whether the HLA system and C. pneumoniae infection interact with respect to the risk for EH. An association study (110 essential hypertensives and 107 controls) was conducted in a highly homogeneous population in the Balearic Island of Majorca (Spain). Molecular typing of HLA-B and HLA-DRB and quantification of serum levels of IgG antibodies to C. pneumoniae (sIgGa-Cp) were determined. Student's t-test, chi(2)-statistics, logistic regression analysis, and general linear model ANOVA were used for statistical analysis. The results showed that EH was related with HLA-DRB3*0202 in the whole study population, and with levels of sIgGa-Cp>63.5 BU/ml in the group of individuals with sIgGa-Cp>30 BU/ml (OR (95% CI) adjusted for obesity, familial history of EH and diabetes=2.06 (1.07-3.97), P=0.03, and =4.60 (1.06-19.90), P=0.04, respectively). The association between EH and sIgGa-Cp was observed in the DRB3*0202(+) individuals, but not in the DRB3*0202(-) subgroup (OR (95% CI)=11.14 (1.92-64.54), P=0.004, and =0.98 (0.22-4.43), P=0.64, respectively (P of the Mantel-Haenszel test for homogeneity of OR=0.06)). In our population, EH was positively associated with HLA-DRB3*0202 and with high levels of sIgGa-Cp. Moreover, a significant interaction of DRB3*0202 on the effect of sIgGa-Cp was observed, as the association of EH with these antibodies depended on the presence of DRB*0202.

Modulation of atherosclerosis in mice by Toll-like receptor 2

Epidemiologic evidence has established a relationship between microbial infection and atherosclerosis. Mammalian TLRs provide clues on the mechanism of this inflammatory cascade. TLR2 has a large ligand repertoire that includes bacterial-derived exogenous and possibly host-derived endogenous ligands. In atherosclerosis-susceptible low-density lipoprotein receptor-deficient (Ldlr-/-) mice, complete deficiency of TLR2 led to a reduction in atherosclerosis. However, with BM transplantation, loss of TLR2 expression from BM-derived cells had no effect on disease progression. This suggested that an unknown endogenous TLR2 agonist influenced lesion progression by activating TLR2 in cells that were not of BM cell origin. Moreover, with intraperitoneal administration of a synthetic TLR2/TLR1 agonist, Pam3CSK4, disease burden was dramatically increased in Ldlr-/- mice. A complete deficiency of TLR2 in Ldlr-/- mice, as well as a deficiency of TLR2 only in BM-derived cells in Ldlr-/- mice, led to striking protection against Pam3CSK4-mediated atherosclerosis, suggesting a role for BM-derived cell expression of TLR2 in transducing the effects of an exogenous TLR2 agonist. These studies support the concept that chronic or recurrent microbial infections may contribute to atherosclerotic disease. Additionally, these data suggest the presence of host-derived endogenous TLR2 agonists.

Chlamydia pneumoniae immunoreactivity in coronary artery plaques of patients with acute coronary syndromes and its relation with serology

BACKGROUND

An association between Chlamydia pneumoniae (Cpn) infection and coronary artery disease has been reported and examined by different techniques. However, its immunoreactivity in coronary artery plaques of patients with acute coronary syndrome (ACS) and its relation with serology are less well defined.

METHODS

We divided 40 coronary plaque specimens from 40 patients who underwent thrombectomy or directional coronary atherectomy into an ACS group (n = 22) and a non-ACS group (n = 18). Cpn in specimens was detected immunohistochemically and compared quantitatively. Serum immunoglobulin (Ig)A and IgG antibodies to Cpn and high-sensitivity C-reactive protein (hs-CRP) were measured. The relation between serology and immunohistochemical analysis was also investigated.

RESULTS

Cpn immunopositive cells per square millimeter (Cpn+ cells/mm2) in the ACS group were significantly more numerous than in the non-ACS group (median 7.44 vs 1.50, P = .0018). Cpn IgA seropositivity rates and titers in the ACS group were significantly higher than those in the non-ACS group (86.3% vs 22.2%, P = .0002; median titer 1.403 vs 0.545, P = .003). There were no differences in IgG antibodies between the 2 groups. The hs-CRP values (in milligrams per liter) in ACS group were significantly higher than in non-ACS group (median 2.8 vs 1.2, P = .0019). Serum IgA titers in patients with at least 5 Cpn+ cells/mm2 in the specimens were significantly higher than in patients with fewer Cpn+ cells (median 1.52 vs 0.86, P = .026). There was no difference in serum hs-CRP values in patients with more Cpn+ cells but a trend to an increase.

CONCLUSION

Immunohistology frequently detected Cpn in coronary plaques; Cpn+ cells were more prevalent in plaques associated with ACS, and Cpn IgA but not IgG titers were increased with ACS and with high densities of Cpn+ cells within plaque.

Lipoproteomics I: mapping of proteins in low-density lipoprotein using two-dimensional gel electrophoresis and mass spectrometry

The molecular mechanisms underlying the relationship between low-density lipoprotein (LDL) and the risk of atherosclerosis are not clear. Therefore, detailed information about the protein composition of LDL may contribute to reveal its role in atherogenesis and the mechanisms that lead to coronary disease in humans. Here, we sought to map the proteins in human LDL by a proteomic approach. LDL was isolated by two-step discontinuous density-gradient ultracentrifugation and the proteins were separated with two-dimensional gel electrophoresis and identified with peptide mass fingerprinting, using matrix assisted laser desorption/ionization-time of flight-mass spectrometry and with amino acid sequencing using electrospray ionization tandem mass spectrometry. These procedures identified apo B-100, apo C-II, apo C-III (three isoforms), apo E (four isoforms), apo A-I (two isoforms), apo A-IV, apo J and apo M (three isoforms not previously described). In addition, three proteins that have not previously been identified in LDL were found: serum amyloid A-IV (two isoforms), calgranulin A, and lysozyme C. The identities of apo M, calgranulin A, and lysozyme C were confirmed by sequence information obtained after collision-induced dissociation fragmentation of peptides characteristic for these proteins. Moreover, the presence of lysozyme C was further corroborated by demonstrating enriched hydrolytic activity in LDL against Micrococcus lysodeikticus. These results indicate that in addition to the dominating apo B-100, LDL contains a number of other apolipoproteins, many of which occur in different isoforms. The demonstration, for the first time, that LDL contains calgranulin A and lysozyme C raises the possibility that LDL proteins may play hitherto unknown role(s) in immune and inflammatory reactions of the arterial wall.

Persistent infection and vascular disease: a systematic review

More than 150 epidemiological or clinical studies have reported on associations between vascular disease and the presence of certain persistent bacterial and viral agents, or of clinical conditions (e.g., periodontal disease) that are associated with persistent infection. This article provides a review of such studies, particularly in relation to Helicobacter pylori, Chlamydia pneumoniae, dental disease and cytomegalovirus (CMV), as well as references to possible mechanisms. The association between coronary heart disease and H. pylori or between heart disease and dental disease may be accounted for by residual confounding. Although markers of C. pneumoniae infection are around twenty times more common in atherosclerotic plaques than in disease-free blood vessels, the sequence of infection and disease is uncertain. For CMV, a limited number of patients with classic atherosclerotic coronary heart disease have been investigated in seroepidemiological studies. For all such agents, better and larger seroepidemiological and pathology-based studies are needed to resolve these uncertainties, as well as - at some stage - large-scale, randomised intervention studies.

Pathohistological changes in diffuse coronary atherosclerosis and chronic infection caused by Chlamydia pneumonia

BACKGROUND AND PURPOSE: To investigate the histopathologic characteristics of atherosclerotic lessions in diffuse coronary artery disease and to evaluate the possible inflammatory role of chronic infection with Chlamydia pneumoniae (CP).MATERIALS AND METHODS: For 10 patients (males, mean age 61 years) who were surgically treated for grave diffuse coronary artery disease, histomorphological analyses of endarterectomized segments of the coronary arteries were performed. Serological analyses for the detection of CP antibodies in peripheral blood were done, preoperatively.RESULTS AND CONCLUSIONS: Diffuse and concentric atherosclerotic changes from VI to VIII stage according to the Stary classification were found. Immunohistochemical methods revealed infiltrates of T-lymphocytes (80% of cases), B-lymphocytes (40% of cases) and macrophages (80%). Using the nuclear marker for proliferation activity MIB-1, single MIB-1 positive cells were found in 40% of cases. Features of arteriologenesis and vasculitis of newly formed arterioles (as well as thickening of the wall of newly formed arterioles) were found in the vessel wall of 8 patients, 7 of them had chronic infection with CP (preoperative micro-immunofluorescent test results: 1:32<IgG ≥1:512 and IgA≥32), one had passed CP infection (1:32 ≤IgG<1:512, IgA negative). These features were absent in 2 patients, both recovered from CP infection and had not the chronic CP infection at the time of surgery. DNA of Chlamydia pneumoniae was detected using the polymerase chain reaction (PCR) method in the vessel wall of 3 patients who were chosen randomly for this method. This study suggests an inflammatory and proatherogenic role of CP in a high grade atherosclerotic coronary artery wall in diffuse coronary artery disease.

[Relationship between the peripheral arterial occlusive disease and the infection by Chlamydophila pneumoniae]

BACKGROUND AND OBJECTIVE

The relationship between peripheral arterial occlusive disease (PAOD) and Chlamydophila pneumoniae infection was studied by analyzing clinical samples from 95 patients with PAOD (cases) and 100 controls.

PATIENTS AND METHOD

The following investigations were conducted: IgG and IgA against lipopolysaccharide (LPS) and against purified C. pneumoniae-specific antigens from elementary bodies (EB) with ELISA; anti-EB IgG, with MIF; C. pneumoniae DNA in arterial biopsy and peripheral blood leukocyte cells (PBLCs) with heminested PCR; LPS with ELISA; and bacteria culture in HEp-2 cells from arterial biopsy.

RESULTS

The percentage of positive results in cases and controls groups for anti-LPS IgG was: 21% and 14%, respectively, with no differences; nor were there any differences with IgA (22 and 21%, respectively). However, differences were seen in the anti-EB IgG between cases (74% and 72%, for ELISA and MIF, respectively) and controls (31% and 34%). There were no differences in anti-EB IgA. Bacterial DNA was detected in 67% of atheromatous plaques (cases) vs. 12% of pudendal arteries (controls) (p = 0.0001). No C. pneumoniae DNA and LPS was detected in PBLCs and biopsic samples, respectively; and no C. pneumoniae strain could be recovered by cell culture from cases.

CONCLUSIONS

On the basis of our results, PAOD is significantly associated with C. pneumoniae infection through the detection of anti-EB IgG from serum and bacterial DNA from arterial biopsy.

Chlamydia Pneumoniae Seropositivity and Cardiovascular Risk Factors: The InCHIANTI Study

OBJECTIVES

To assess the prevalence of Chlamydia pneumoniae (CP) seropositivity and test the hypothesis that CP infection (CPI) is associated with cardiovascular (CV) risk factors and levels of inflammatory biomarkers.

DESIGN

Cross-sectional survey.

SETTING

Representative sample of the residents of Greve in Chianti and Bagno a Ripoli, two small towns located in the Chianti geographic area (Tuscany, Italy).

PARTICIPANTS

A total of 1,304 (age-range: 20-103, 79% aged> or =65) participants of the InCHIANTI study.

MEASUREMENTS

CP seropositivity was assessed using immunofluorescence. Previous CPI was defined as immunoglobulin (Ig) G > or =1/16 and <1/256, and recent CPI was defined as IgG > or =1/512 or IgM > or =1/16. Inflammatory markers included interleukin (IL)-6, soluble IL-6 receptor (sIL-6r), tumor necrosis factor-alpha (TNF-alpha), IL-1beta, IL-1 receptor antagonist (IL-1ra), iron, ferritin, and C-reactive protein (CRP). CV risk factors included smoking, body mass index (BMI), lipid profile, and hypertension.

RESULTS

The prevalence of CP seropositivity was 75%, increased with age, and was higher in men than in women (P<.01). CPI was not associated with IL-1beta, IL-1ra, iron, ferritin, CRP, BMI, lipids, and smoking. After adjusting for age and sex, previous or recent CPI was associated with higher TNF-alpha (P<.01), IL-6 (P<.03), sIL-6R (P<.01), and hypertension (P<.02). In additional age and sex-adjusted models, the associations between CPI and TNF-alpha, IL-6, sIL-6r, and hypertension appeared to be mutually independent.

CONCLUSION

CP seropositivity is highly prevalent in the older population and is a significant, independent correlate of hypertension and circulating levels of TNF-alpha, IL-6, and sIL-6r.

Histopathologic signs for the inflammatory role of Chlamydia pneumoniae in the high-grade atherosclerotic coronary artery wall

The aim of the study was to prove the long-lasting and continuously harmful effect of chronic Chlamydia pneumoniae (CPn) infection on vessel walls in patients with diffuse coronary artery disease (CAD). In surgically obtained endarterectomized atherosclerotic plaques grade VI-VIII (Stary classification) from 10 patients with diffuse coronary artery disease and chronic (7) or past (3) CPn infection, signs of inflammatory response of the vessel wall on infectious agents were studied. In all 10 endarterectomized plaque step serial sections, immunologic signs of vessel wall response were present (positive T- and B-lymphocytes, macrophages, and capillarogenesis). In 8 of 10 patients' atherosclerotic plaque, unique features of active vasculitis in the neoarteriolar wall as well as arteriologenesis, were found. Seven of these 8 patients had serologically proven chronic CPn infection, and 1 had past infection. Features of vasculitis as well as arteriologenesis were absent in 2 patients who recovered from CPn infection at the time of surgery. In the endarterectomized segments of 3 randomly chosen patients in this study, the polymerase chain reaction method revealed positive DNA of CPn. Two of these patients had chronic infection, but the third had only a past CPn infection. This study provides evidence that CPn infection has continuous and a long-lasting inflammatory response in the high-grade atherosclerotic coronary artery vessel wall.

Genomic, serologic, and clinical case-control study of Chlamydia pneumoniae and peripheral artery occlusive disease

OBJECTIVES

Chlamydia pneumoniae has been related to atherosclerotic disease in both seroepidemiologic and genomic studies. We performed a case-control study to determine seropositivity and DNA detection in arteries of patients with peripheral artery occlusive disease and of healthy subjects.

METHODS

The study included 64 patients with peripheral artery occlusive disease, and 50 control subjects who underwent varicose vein surgery, matched to the patient group for age, sex, and tobacco use. The fibrinogen level in all study subjects was measured as a marker of inflammation. Blood samples were taken from all subjects for determination of immunoglobulin (Ig) G elementary bodies (EB) against C pneumoniae with microimmunofluorescence (MIF) and enzyme-linked immunosorbent assay (ELISA), and of IgA EB with ELISA. The cutoff titers were 1:32 for MIF and 1.1 for ELISA. Biopsy specimens of arterial atheromatous plaque were obtained from patients, and of pudendal artery and saphenous vein from control subjects, and were studied with hemi-nested polymerase chain reaction.

RESULTS

There were no differences in fibrinogen level between patients and controls. The prevalence of IgG anti-EB with MIF was 78% in patients and 24% in control subjects (P =.0001; odds ratio [OR], 11.3; 95% confidence interval [CI], 4.7-27.2). Prevalence of IgG anti-EB with ELISA was 75% in patients and 16% in control subjects (P =.0001; OR, 15.7; 95% CI, 6.1-40). There were no differences in IgA anti-EB titers. Bacterial DNA was detected in 67% of atheromatous plaques versus 12% of pudendal arteries (P =.0001) and 4% of saphenous veins. A weak correlation was found between seropositivity and the presence of intravascular DNA.

CONCLUSIONS

Our results support the hypothesis that C pneumoniae is related to the pathogenesis of atherosclerotic peripheral artery occlusive disease.

CLINICAL RELEVANCE

This study explored the infectious hypothesis in the context of the pathogenesis of atherosclerosis. This hypothesis has been supported by findings that certain infectious agents can cause or accelerate the course of diseases in which the possibility of a microbial cause was not previously proposed, as in the case of peptic ulcer and spongiform encephalopathy. The present study demonstrated the presence of Chlamydia pneumoniae and seropositivity in atheromatous plaques in patients with peripheral artery occlusive disease. These results contribute to a body of research that is opening up the possibility of treating atherosclerotic disease with antibiotic agents, and preventing it with immunization.

Chlamydia pneumoniae and future risk in patients with coronary heart disease

AIM

To evaluate the association between previous exposure to Chlamydia pneumoniae and future coronary risk in patients with coronary heart disease.

METHODS

A prospective, nested, case-control design was used. The patient sample was derived from a trial study of bezafibrate for the treatment of coronary heart disease. Anti-Chlamydia pneumoniae antibodies (IgG and IgA) in the baseline sera of 136 patients who had coronary events during follow-up (mean 6.2 years) were compared with those in 136 age- and gender-matched patients from the same trial without subsequent coronary events.

RESULTS

Mean titers of IgG and IgA antibodies were similar in cases and controls. The relative odds of future coronary events in patients who were seropositive at baseline were 1.0 (95% CI, 0.54-1.84) for IgG and 0.74 (95% CI, 0.41-1.31) for IgA. The relative odds did not change after adjustment for multiple confounding variables. The risk of future coronary events did not increase with increasing anti-Chlamydia pneumoniae antibody titers.

CONCLUSIONS

Prior exposure to Chlamydia pneumoniae in patients with chronic coronary heart disease is not associated with increased risk of recurrent coronary events.

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.

Importance of methodology in determination of Chlamydia pneumoniae seropositivity in healthy subjects and in patients with coronary atherosclerosis

Enzyme immunoassays (EIAs) for the detection of Chlamydia pneumoniae antibodies were compared to the microimmunofluorescence (MIF) test, the reference method. Furthermore, we assessed the hypothesis that a possible relationship between Chlamydia pneumoniae immunoglobulin G (IgG) antibodies and coronary artery disease is dependent on the type of EIA. Sera from 112 healthy men (mean age, 50.1 years) were tested for antibodies against Chlamydia pneumoniae by five commercial test kits: Focus Chlamydia MIF IgG test, Labsystems Chlamydia pneumoniae IgG EIA (LS EIA), R-Biopharm Elegance Chlamydia pneumoniae IgG EIA (RB EIA), Medac Chlamydia pneumoniae IgG sandwich enzyme-linked immunosorbent assay ELISA (MCp sELISA) and Medac Chlamydia IgG recombinant enzyme-linked immunosorbent assay ELISA (MC rELISA). Sera from 106 consecutive male patients (mean age, 63.6 years) undergoing diagnostic coronary angiography were also examined using the Focus MIF, LS EIA, MCp sELISA, and MC rELISA techniques. The agreement between LS EIA (65 to 83% [controls-patients]) or MC rELISA (49 to 61%) and Focus MIF (78 to 83%) was average to fair (kappa = 0.597 and 0.234, respectively). MCp sELISA and RB EIA showed good agreement with MIF (kappa = 0.686 and 0.665, respectively), with 80 to 89 and 79% of individuals reacting positively. A significant difference in seroprevalence between patients and healthy subjects was observed with the LS EIA, while seropositivities in the two study groups appeared equal when the Focus MIF assay was applied. The MC rELISA and MCp sELISA gave statistically significant differences in antibody seroprevalence in patients with two-vessel disease or when the patient group combined individuals with a two- or a three-vessel disease, respectively. The concordance between MIF and other commonly used serological assays for C. pneumoniae IgG antibody detection is good to fair. The choice of serological assay has important implications for C. pneumoniae antibody seroprevalence, as well as for the relationship between C. pneumoniae seropositivity and coronary artery disease.

Joint effects of Chlamydia pneumoniae infection and classic coronary risk factors on risk of acute myocardial infarction

BACKGROUND

Although not in itself strongly predictive of coronary heart disease, Chlamydia pneumoniae infection could interact with classic risk factors in determining risk of acute myocardial infarction (AMI).

METHODS

We assessed C pneumoniae immunoglobulin (Ig) G and IgA titers and classic risk factors in 618 patients with AMI and in 967 controls.

RESULTS

IgG titers were not related to AMI, but a significant association was seen between IgA titers and AMI. Excess risk of AMI was noted mainly among patients with the highest IgA titers, such as those beyond 2.88 (the 95th percentile cutoff point in control subjects), showing a 1.8-fold increase in risk (odds ratio 1.75, 95% CI 1.04-2.92). Classic risk factors did not differ between subjects with IgA titers above and below the 95th percentile cutoff. However, in multivariate analyses, models incorporating both IgA titers and a classic risk factor such as obesity, hypercholesterolemia, or smoking predicted risk more effectively than single-parameter models. For example, the odds ratio for AMI among subjects with the highest IgA titers plus hypercholesterolemia was greater than the product of individual risks associated with these high IgA titers and with hypercholesterolemia.

CONCLUSIONS

Interactions with classic risk factors (ie, obesity, hypercholesterolemia, and smoking), increased the predictive value of C pneumoniae IgA antibody titers in determining risk of AMI.

Acute Chlamydia pneumoniae infection causes coronary endothelial dysfunction in pigs

BACKGROUND

Coronary endothelial dysfunction contributes to the pathogenesis of acute coronary syndromes (ACSs). Acute Chlamydia pneumoniae infection has been epidemiologically associated with ACS. In this study, we investigated whether acute C. pneumoniae infection could alter the endothelial vasomotor function of porcine coronary vessels.

METHODS AND RESULTS

Twenty pigs, 7-9 kg in weight, were inoculated intratracheally with C. pneumoniae (n=12) or saline (n=8), and investigated at 3 days (five infected/four non-infected) and 2 weeks (5+2 infected/four non-infected) after inoculation. The endothelium-dependent reactivity of coronary microcirculation was assessed at both time points by measuring peak coronary flow velocity (CFV) in response to bradykinin, before and after infusions with glutathione, an antioxidant, and L-arginine, a substrate for nitric oxide synthase (NOS). CFV after bradykinin was significantly decreased in infected animals at both time points. At 2 weeks, both glutathione and L-arginine significantly improved CFV after bradykinin. CFV after sodium nitroprusside (SNP) was similar in both groups. At 3 days, the relaxation responses of bradykinin-induced pre-contracted left anterior descending (LAD) coronary rings to bradykinin were significantly less in infected animals. N(G)-nitro-L-arginine-methyl-ester, an NOS inhibitor, had significantly greater inhibitory effect on bradykinin-induced relaxation in infected animals. Plasma nitrate-nitrite and fibrinogen, and NOS activity from LAD coronary samples were significantly increased in infected animals.

CONCLUSION

Acute C. pneumoniae infection causes endothelial dysfunction of both resistance and epicardial coronary vessels, and favours a pro-coagulant status. These effects could in part account for the epidemiologically suggested association between acute infection and ACS.

Chlamydia antibody response in healthy volunteers immunized with nonchlamydial antigens: a randomized, double-blind, placebo-controlled study

Serological analysis is often used for the diagnosis of chlamydial infections. However, an increase in Chlamydia antibodies has been reported in patients with parvovirus and Mycoplasma infections. Whether this antibody response is the result of dual infection or nonchlamydial antigen stimulation is unknown. In a randomized study, 48 healthy volunteers either were immunized against yellow fever, polio, diphtheria, and tetanus (the group receiving intervention with nonchlamydial antigen) or received saline injections (the placebo group). The change in antibody levels was compared between the 2 groups. The Chlamydia recombinant lipopolysaccharide enzyme-linked immunosorbent assay (Medac) showed an increase in the antibody titer in the intervention group, compared with that in the control group (for immunoglobulin M, P=.004; for immunoglobulin A, P=.038; and for immunoglobulin G, P=.056), but no differences between study groups was found when the C. pneumoniae enzyme immunoassay (EIA; ThermoLabsystems), the C. pneumoniae EIA (Medac), and the microimmunofluorescence test (MRL) were used. An increase in antibodies to Chlamydia organisms can be measured after exposure to nonchlamydial antigens, depending on the test used.

Chlamydia pneumoniae and coronary artery disease: the antibiotic trials

Parallel with the mounting evidence that atherosclerosis has a major inflammatory component, provoking agents that may initiate and drive this process have been sought. Infectious agents such as Chlamydia pneumoniae have been alleged to be activators of inflammation that may contribute to atherosclerosis and thus coronary artery disease (CAD) and its associated complications. A logical pneumoniae extension of this theory whether treating C pneumoniae infection with antibiotics and/or modulating inflammatory processes can affect CAD and its sequelae. This article discusses the potential role of C pneumoniae in atherosclerosis, its detection, and the rationale for antibiotics. Additionally, it summarizes the current randomized clinical trials of antichlamydial antibiotics in patients with CAD and draws conclusions based on the results.

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.

Increased prevalence of Chlamydophila pneumoniae but not Epstein-Barr antibodies in essential hypertensives

Conflicting data exist regarding the relationship between Chlamydophila pneunoniae (C. pneumoniae) and hypertension. In this study, both C. pneumoniae IgG and IgA titres and Epstein-Barr virus antibody levels were measured in 146 sustained hypertensives defined by 24 h ambulatory blood pressure monitoring (ABPM) and 54 normotensives. C. pneumoniae antibodies were measured by microimmunofluorescence test. IgG > or = 80 and IgA > or = 40 were defined as elevated antibody titres. Epstein-Barr antibodies were measured in order to investigate whether a possible association exists between hypertension and other, similarly widespread in the general population, intracellular microorganisms. All participants underwent casual blood pressure (BP) readings and 24 h ABPM. Subjects having mean 24 h systolic/diastolic ambulatory BP>125/80 mmHg, with or without antihypertensive medication were defined as hypertensives. Controls were free of any history or clinical evidence of hypertension, cardiovascular or pulmonary disease. Of the total participants, 77 hypertensives (52.7%) and 10 normotensives (18.5%) had IgA titres > or = 40 (crosstabs P < 0.000), whereas 76 hypertensives (52.1%) and 15 normotensives (27.8%) had IgG titres > or = 80, (crosstabs P < 0.002). No difference was found in Epstein-Barr antibodies, between hypertensives and normotensives. In conclusion, C. pneumoniae, but not Epstein-Barr, antibody levels were found significantly higher in sustained hypertensives, suggesting high frequency of chronic C. pneumoniae, infections in this specific group of patients.

[Chronic Chlamydia pneumoniae infection in patients with coronary disease. Relation with increased fibrinogen values]

BACKGROUND

A number of studies have suggested that infection with Chlamydia pneumoniae can play a role in development of atherosclerosis. The goal of this study was to know the prevalence of chronic C. pneumoniae infection, evaluated with IgG antibodies seropositivity, in Spanish patients with coronary disease and its association with inflammatory markers and cardiovascular risk factors.

PATIENTS AND METHOD

In 176 patients with coronary disease IgG and IgM antibodies to C. pneumoniae were determined by enzyme immunoassay. In addition, fibrinogen and C-reactive protein values were measured as inflammatory markers. Controls were 55 healthy subjects whose age was not different from patients. Seropositivity for C. pneumoniae was considered when indices of IgG and/or IgM antibodies were higher than mean plus two standard deviations of control values. Three patients with seropositivity for IgM were excluded.

RESULTS

In 126 patients and 2 controls a seropositivity against C. pneumoniae was proved (72.8% vs 4.2%; p < 0.001). Cardiovascular risk factors were not different in seropositive and seronegative groups of patients. Prevalence of hyperfibrinogenemia was higher in the former group (38.8% vs 19.1%; p = 0.01). The number of the patients with increased values of C-reactive protein was similar in both groups, although these values could be modified by treatment with statins. In multivariate analysis an association between seropositivity for C. pneumoniae and hyperfibrinogenemia was found (odds ratio [OR] = 2.42; 95% confidence interval, 1.07-5.48; p = 0.03) after adjusting for age, gender, smoking, hypertension, hypercholesterolemia and diabetes.

CONCLUSIONS

Chronic infection with C. pneumoniae in patients with coronary disease is very prevalent, and it is associated with increased fibrinogen values.

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

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

Detection and differentiation of chlamydiae by fluorescence in situ hybridization

Chlamydiae are important pathogens of humans and animals but diagnosis of chlamydial infections is still hampered by inadequate detection methods. Fluorescence in situ hybridization (FISH) using rRNA-targeted oligonucleotide probes is widely used for the investigation of uncultured bacteria in complex microbial communities and has recently also been shown to be a valuable tool for the rapid detection of various bacterial pathogens in clinical specimens. Here we report on the development and evaluation of a hierarchic probe set for the specific detection and differentiation of chlamydiae, particularly C. pneumoniae, C. trachomatis, C. psittaci, and the recently described chlamydia-like bacteria comprising the novel genera Neochlamydia and PARACHLAMYDIA: The specificity of the nine newly developed probes was successfully demonstrated by in situ hybridization of experimentally infected amoebae and HeLa 229 cells, including HeLa 229 cells coinfected with C. pneumoniae and C. trachomatis. FISH reliably stained chlamydial inclusions as early as 12 h postinfection. The sensitivity of FISH was further confirmed by combination with direct fluorescence antibody staining. In contrast to previously established detection methods for chlamydiae, FISH was not susceptible to false-positive results and allows the detection of all recognized chlamydiae in one single step.

Lipopolysaccharide down regulates both scavenger receptor B1 and ATP binding cassette transporter A1 in RAW cells

Lipopolysaccharide (LPS) has recently been shown to facilitate macrophage foam cell formation and has been suggested to be a proatherogenic factor. The mechanism of LPS induced cholesterol accumulation, however, is unclear. In this report, using the macrophage-like RAW 264.7 cell line, we provide experimental evidence that LPS's proatherogenic effects may at least in part reflect altered cholesterol metabolism. Data presented demonstrate that in a dose-dependent manner, LPS is able to down regulate the mRNA expression of the two primary high-density lipoprotein (HDL) receptors, scavenger receptor B1 (SR-B1) and ATP binding cassette A1 (ABCA1), with a 50% inhibitory concentration of less than 0.2 ng/ml, as well as to decrease SR-B1 protein expression by 80%. We also found that LPS treatment resulted in a significant decrease (to 20% of the control level) of the specific (125)I-HDL binding as well as in 50% inhibition of the HDL-mediated cholesterol efflux compared to untreated cells. In addition, we compared the potencies of various modified LPS preparations and demonstrated that the phosphorylated lipid A portion of LPS, which is highly conserved among gram-negative microorganisms, including Chlamydia, is primarily responsible for the effects of LPS on SR-B1 and ABCA1 expression. Inhibitors of NF-kappaB activation were observed to efficiently block the suppressive effect of LPS on SR-B1 and ABCA1, suggesting a mechanism involving NF-kappaB. These data indicate that the LPS effects on cholesterol metabolism may contribute to the proatherogenic properties of LPS.

Implication of natural killer T cells in atherosclerosis development during a LPS-induced chronic inflammation

Atherosclerosis has many features of a chronic inflammatory disease. To evaluate the role of lipopolysaccharide (LPS), mimicking a systemic infection, we administered the endotoxin to apolipoprotein E (apoE)-deficient mice. LPS injections increase the atherosclerotic lesion size and the titer of plasma autoantibodies directed against oxidized low-density lipoprotein. We found that Th1 and Th2 T cells help the activation of B cells in the autoimmune response. The number of interleukin-4 producing natural killer T cells is highly increased in peripheral blood, liver, spleen and thymus cells, as well as in the atherosclerotic plaque of the LPS-treated mice. Finally, an important adventitial infiltrate of activated lymphocytes, sign of an advanced atherosclerosis, is observed only in the LPS-treated mice. Our results demonstrate that LPS administration aggravates atherosclerosis in apoE-deficient mice. LPS-injected apoE-deficient mice appear to be an excellent animal model to analyze the implementation of new therapeutic approaches in the treatment of atherosclerosis by manipulating immunological effectors.

Hyperhomocyst(e)inemia and Chlamydia pneumoniae IgG seropositivity in patients with coronary artery disease

Elevated levels of homocyst(e)ine and infection by Chlamydia pneumoniae have been hypothesized individually to play a role in coronary artery disease (CAD), but the mechanisms are unclear. Data on a possible association are not available. We investigated the correlation between IgG antibody titers against C. pneumoniae and fasting plasma homocyst(e)ine in 234 consecutive male patients with CAD. Chlamydial antibodies to a recombinant genus-specific lipopolysaccharide (LPS) were measured with ELISA. Total homocyst(e)ine (tHcy) concentrations were measured by high-performance liquid chromatography (HPLC). Thirty-seven subjects were classified hyperhomocyst(e)inemic (fasting homocyst(e)ine>14 micromol/l, group A), and 197 subjects were below cut-off (tHcy<14 micromol/l, group B). Prevalence of IgG seropositivity against C. pneumoniae was significantly higher in group A (68%) as compared to group B (39%, P=0.002). Antibody titers were also significantly higher in hyperhomocyst(e)inemic subjects than in cases with low homocyst(e)ine levels (P=0.002). Overall titers correlated significantly with tHcy levels (r(2)=0.222, P=0.001). Hyperhomocyst(e)inemia was associated with arterial hypertension (P=0.003), intake of lipid lowering drugs (P=0.022) and quite not with low folate concentration (P=0.052). No association was seen for IgG seropositivity or homocyst(e)ine and age, body mass index, smoking, diabetes, vitamin B(6) and B(12), cholesterol and triglycerides. These data indicate an association between elevated plasma homocyst(e)ine concentrations and chlamydial IgG antibody titers in patients with CAD.

Review of evidence for a connection between Chlamydia pneumoniae and atherosclerotic disease

BACKGROUND

Established risk factors account for no more than 50% of coronary artery disease cases; therefore, the search continues for other modifiable risk factors. In recent years, there has been renewed interest in the infectious theory of atherosclerosis. Chlamydia pneumoniae has been implicated as a potential cause of atherosclerotic disease.

OBJECTIVE

This review discusses possible mechanisms of C pneumoniae involvement in atherosclerosis, summarizes the case-control studies and antibiotic trials completed, and identifies remaining questions about future therapy.

METHODS

Published data were identified by a MEDLINE search of the English-language literature from 1966 through 2001 using the terms Chlamydia, atherosclerosis, and coronary artery disease. Relevant conference presentations and book chapters were also included.

RESULTS

C pneumoniae antibodies are found in approximately 50% of middle-aged adults world-wide. These antibodies have been detected in atherosclerotic tissue by various methods, including microimmunofluorescence, and several studies have linked high antibody titers with increased risk of cardiovascular events. A few possible mechanisms for this perceived increase in risk have been proposed, such as induction of atheroma through damage to the endothelium, expression of procoagulant factor leading to thrombus formation, and production of cytokines resulting in increased inflammatory response. Results of animal studies suggest that early antibiotic treatment may reduce cardiovascular risk, but the first human studies have not produced conclusive results.

CONCLUSIONS

Although a connection has been suggested, the precise mechanism by which C pneumoniae affects atherosclerosis has not yet been identified. Large-scale trials are needed to determine whether eradication of C pneumoniae reduces the incidence of cardiovascular events in humans.

Chlamydia pneumoniae seropositivity and the risk of nonarteritic ischemic optic neuropathy

OBJECTIVE

To determine whether IgG antibodies to Chlamydia pneumoniae are associated with nonarteritic ischemic optic neuropathy (NAION).

DESIGN

Retrospective case-control study.

PARTICIPANTS

The study cohort consisted of 71 consecutive patients with NAION and 71 controls matched for age and gender.

MAIN OUTCOME MEASURES

Serum immunoglobulin G (IgG) antibody titers to Chlamydia pneumoniae.

RESULTS

Patients with NAION had significantly higher IgG antibody titers to C. pneumoniae compared with control subjects (IgG titer > or =1:128: 29 patients versus 15 controls, P = 0.017). The odds ratio for patients with an IgG titer > or =1:128 was 2.56 (95% confidence interval [CI], 1.2-5.5). Adjustment for arterial hypertension, diabetes mellitus, and myocardial infarction resulted in an odds ratio of 3.48 (95% CI, 1.3-9.6).

CONCLUSIONS

Our results suggest that elevated titers of IgG antibodies to C. pneumoniae are associated with NAION.

Antibodies to 60-kilodalton heat shock protein and outer membrane protein 2 of Chlamydia pneumoniae in patients with coronary heart disease

Evidence linking Chlamydia pneumoniae infection to atherosclerosis and to atherothrombotic events has recently emerged. A primary candidate implicated in these pathogenetic events is the 60-kDa chlamydial heat shock protein (HSP60). Another putative candidate to activate a potential proinflammatory mechanism is the chlamydial outer membrane protein 2 (OMP2). We have generated both HSP60 and OMP2 recombinant antigens in a nondenatured form and shown that (i) the two antigens were highly immunogenic in mice and (ii) murine antisera thus generated recognized the native C. pneumoniae proteins. We measured by enzyme linked immunosorbent assay (ELISA) and immunoblot assay antibody titers to the recombinant antigens in samples from 219 patients with coronary heart disease (CHD), 179 patients with unstable angina (UA), 40 patients with acute myocardial infarction (AMI), and 100 age-, sex-, and risk factor-matched healthy controls. We also examined whether anti-HSP60 and/or anti-OMP2 antibodies correlated with anti-C. pneumoniae antibodies assessed by a commercial microimmunofluorescence (MIF) assay. Immunoglobulin G (IgG), but neither IgA nor IgM, antibodies against the two recombinant proteins were detected by ELISA. In particular, anti-HSP60 antibodies were detected in >99% of CHD patients versus 0% of the controls, whereas the proportions of anti-OMP2 positive subjects were >70 and 27%, respectively. Nonetheless, among CHD patients, similar frequencies of positive subjects and titers of anti-HSP60 or anti-OMP2 antibodies were present in UA and AMI subjects. The anti-OMP2, but not the anti-HSP60, antibodies showed high specificity. Consistently, high serological correlation was observed between IgG MIF titers and IgG ELISA reactivity to OMP2 but not to HSP60. Overall, the results of this study demonstrate a strong correlation between CHD and anti-HSP60 IgG levels, as measured by our in-house ELISA. They also suggest that recombinant OMP2 ELISA, because of its high specificity and strong correlation with MIF assay, could be a candidate diagnostic marker for C. pneumoniae infection, which would be of potential usefulness for its specificity and nonsubjective nature.