Modifiable and Non-Modifiable Risk Factors for Premature Coronary Heart Disease (PCHD): Systematic Review and Meta-Analysis

AIM

We aimed to compare the prevalence of modifiable and non-modifiable coronary heart disease (CHD) risk factors among those with premature CHD and healthy individuals.

METHODS

PubMed, CINAHL, Embase, and Web of Science databases were searched (review protocol is registered in PROSPERO CRD42020173216). The quality of studies was assessed using the National Heart, Lung and Blood Institute tool for cross-sectional, cohort and case-control studies. Meta-analyses were performed using Review Manager 5.3. Effect sizes for categorical and continuous variables, odds ratio (OR) and mean differences (MD)/standardised mean differences (SMD) with 95% confidence intervals (CI) were reported.

RESULTS

A total of n=208 primary studies were included in this review. Individuals presenting with premature CHD (PCHD, age ≤65 years) had higher mean body mass index (MD 0.54 kg/m2, 95% CI 0.24, 0.83), total cholesterol (SMD 0.27, 95% CI 0.17, 0.38), triglycerides (SMD 0.50, 95% CI 0.41, 0.60) and lower high-density lipoprotein cholesterol (SMD 0.79, 95% CI: -0.91, -0.68) compared with healthy individuals. Individuals presenting with PCHD were more likely to be smokers (OR 2.88, 95% CI 2.51, 3.31), consumed excessive alcohol (OR 1.40, 95% CI 1.05, 1.86), had higher mean lipoprotein (a) levels (SMD 0.41, 95% CI 0.28, 0.54), and had a positive family history of CHD (OR 3.65, 95% CI 2.87, 4.66) compared with healthy individuals. Also, they were more likely to be obese (OR 1.59, 95% CI 1.32, 1.91), and to have had dyslipidaemia (OR 2.74, 95% CI 2.18, 3.45), hypertension (OR 2.80, 95% CI 2.28, 3.45), and type 2 diabetes mellitus (OR 2.93, 95% CI 2.50, 3.45) compared with healthy individuals.

CONCLUSION

This meta-analysis confirms current knowledge of risk factors for PCHD, and identifying these early may reduce CHD in young adults.

Individual and Joint Effects of Influenza-Like Illness and Vaccinations on Stroke in the Young: A Case-Control Study

BACKGROUND:

Influenza-like illness (ILI) is an acute trigger for stroke, although joint effects of vaccinations and ILI have not yet been explored.

METHODS:

Data for our case-control study was obtained from MarketScan Commercial Claims and Encounters between 2008 and 2014. Patients 18 to 65 years old who experienced a stroke were matched on age and admission date to a control, defined as patients with head trauma or ankle sprain at an inpatient or emergency department visit. Exposures were ILI in the prior 30 days, and any type of vaccination during the year prior. Our outcome was ischemic and intracerebral hemorrhagic strokes identified using International Classification of Diseases, Ninth Revision (ICD-9 ) codes. Logistic regression models estimated adjusted odds ratios (aORs) controlling for preventive care visits, diabetes, valvular heart disease, smoking, alcohol abuse, obesity, and hypertension.

RESULTS:

We identified and matched 24 103 cases 18 to 44 years old and 141 811 45 to 65 years old. Those aged 18 to 44 years had increased stroke risk 30 days after ILI (aOR, 1.68 [95% CI, 1.51–1.86]) and reduced risk with any vaccination in the year prior (aOR, 0.92 [95% CI, 0.87–0.99]). Joint effects indicate that ILI was associated with increased stroke risk among those with (aOR, 1.41 [95% CI, 1.08–1.85]) and without (aOR, 1.73 [95% CI, 1.55–1.94]) vaccinations in the prior year ( P interaction =0.16). Among those aged 45 to 65 years, adjusted analyses indicate increased stroke risk for those with ILI (aOR, 1.32 [95% CI, 1.26–1.38]), although there was no effect of vaccinations (aOR, 1.00 [95% CI, 0.97–1.02]). Joint effects indicate that ILI was not associated with stroke among those with any vaccination (aOR, 1.07 [95% CI, 0.96–1.18]) but was associated with increased risk among those without vaccinations ([aOR, 1.39 [95% CI, 1.32–1.47]; P interaction <0.001).

CONCLUSIONS:

ILI was associated with increased stroke risk in the young and middle-aged, while vaccinations of any type were associated with decreased risk among the young. Joint effects of ILI and vaccinations indicate vaccinations can reduce the effect of ILI on stroke.

Human Cytomegalovirus and Risk of Incident Cardiovascular Disease in United Kingdom Biobank

BACKGROUND

Previous studies have yielded conflicting results on the association between human cytomegalovirus (HCMV) and cardiovascular disease (CVD). This study examined associations between HCMV and incident CVD, ischaemic heart disease (IHD) and stroke.

METHODS

This study included 8531 women and men of predominantly white ethnic background, aged 40-69 without prevalent CVD from the population-based UK Biobank study, recruited between 2006-2010 with HCMV antibody levels measured. CVD was ascertained via linkage to health administrative records collected until 2020. Multivariate Cox proportional-hazards models were used to determine associations between HCMV seropositivity and incident CVD, IHD and stroke. HCMV seropositive antibody levels in tertiles were used to assess dose-response associations.

RESULTS

Over a mean follow-up period of 10.2 years, HCMV seropositivity was not significantly associated with CVD (Cases = 626, Hazard Ratio [HR] =1.01, 95% confidence interval [CI], .86-1.20), IHD (Cases = 539, HR=1.03, 95% CI, .87-1.24) or stroke (Cases = 144, HR = 0.96, 95% CI, .68-1.36). There was no evidence of dose-response associations with any outcome.

CONCLUSIONS

We found no significant association between HCMV seropositivity and risk of CVD, IHD or stroke. Further research within understudied populations, such as those of non-white ethnicity, and CVD subtypes is warranted.

Th1 cells are dispensable for primary clearance of Chlamydia from the female reproductive tract of mice

Protective immune responses to Chlamydia infection within the female reproductive tract (FRT) are incompletely understood. MHC class II-restricted CD4 Th1 responses are believed to be vital for bacterial clearance due to their capacity to secrete IFN-γ, but an essential requirement for T-bet-expressing Th1 cells has yet to be demonstrated in the mouse model of Chlamydia infection. Here, we investigated the role of T-bet and IFN-γ in primary clearance of Chlamydia after FRT infection. Surprisingly, IFN-γ producing CD4 T cells from the FRT expressed low levels of T-bet throughout infection, suggesting that classical T-bet-expressing Th1 cells are inefficiently generated and therefore unlikely to participate in bacteria clearance. Furthermore, mice deficient in T-bet expression or with a CD4-specific T-bet deficiency cleared FRT infection similarly to wild-type controls. T-bet-deficient mice displayed significant skewing of FRT CD4 T cells towards Th17 responses, demonstrating that compensatory effector pathways are generated in the absence of Th1 cells. In marked contrast, IFN-γ-, and IFN-γR-deficient mice were able to reduce FRT bacterial burdens, but suffered systemic bacterial dissemination and 100% mortality. Together, these data demonstrate that IFN-γ signaling is essential to protect mice from fatal systemic disease, but that classical T-bet-expressing Th1 cells are non-essential for primary clearance within the FRT. Exploring the protective contribution of Th1 cells versus other CD4 effector lineages could provide important information for the generation of new Chlamydia vaccines.

The production of IFN-γ by CD4 Th1 cells is thought to be critical for the clearance of Chlamydia from the female reproductive tract (FRT), but this has not been formally tested. Here we demonstrate that T-bet+ Th1 cells are not essential for effective Chlamydia clearance. Furthermore, the impact of IFN-γ deficiency or depletion is largely observed as a failure to control bacterial dissemination, rather than clearance from the FRT. Together, these data suggest that different immunological mechanisms are responsible for restraining systemic spread of bacteria versus FRT control. Defining alternative non-Th1 CD4 effector mechanisms that are responsible for controlling Chlamydia replication within the FRT could be foundational for future vaccine development.

Risk of stroke and myocardial infarction after influenza-like illness in New York State

Background

Influenza may be associated with increased stroke and myocardial infarction (MI) risk. We hypothesized that risk of stroke and MI after influenza-like illness (ILI) would be higher in patients in New York State. We additionally assessed whether this relationship differed across a series of sociodemographic factors.

Methods

A case-crossover analysis of the 2012–2014 New York Statewide Planning and Research Cooperative System (SPARCS) was used to estimate odds of ischemic stroke and MI after ILI. Each patient’s case window (the time period preceding event) was compared to their control windows (same dates from the previous 2 years) in conditional logistic regression models used to estimate odds ratios and 95% confidence intervals (OR, 95% CI). We varied the case windows from 15 to 365 days preceding event as compared to control windows constructed using the same dates from the previous 2 years. Analyses were stratified by sex, race, and urban-rural status based on residential zip code.

Results

A total of 33,742 patients were identified as having ischemic stroke and 53,094 had MI. ILI events in the 15 days prior were associated with a 39% increase in odds of ischemic stroke (95% CI 1.09–1.77), increasing to an almost 70% increase in odds when looking at ILI events over the last year (95% CI 1.56, 1.83). In contrast, the effect of ILI hospitalization on MI was strongest in the 15 days prior (OR = 1.24, 95% CI 1.06–1.44). The risk of ischemic stroke after ILI was higher among individuals living in rural areas in the 90 days prior to stroke and among men in the year prior to event. In contrast, the association between ILI and MI varied only across race with whites having significantly higher ILI associated MI.

Conclusion

This study highlights risk period differences for acute cardiovascular events after ILI, indicating possible differences in mechanism behind the risk of stroke after ILI compared to the risk of MI. High risk populations for stroke after ILI include men and people living in rural areas, while whites are at high risk for MI after ILI. Future studies are needed to identify ways to mitigate these risks.

Association between age and infection in patients with acute ST-elevation myocardial infarction

Background

ST-elevation myocardial infarction (STEMI) in young patients has a unique risk profile. We aimed to detect bacteria in aspirate of infarct artery in young versus old patients.

Results

Aspirates of consecutive 140 patients who underwent a primary coronary intervention were taken for bacteriological, microscopical, and immunohistochemical (for bacterial pneumolysin) examinations. Their results were calculated in young (≤ 50 years) versus old (> 50 years) patients. Median age (interquartile range) was 45 (38–48) years in young (60 patients) and 59 (55–65) years in old (80 patients) patients, p < 0.0001. Both groups had similar baseline data except age, males, diabetes, hyperlipidemia, family history, lesion length, and ectatic vessel. Different bacteria were cultured in 11.3% of all patients involving 22.6% of young and 2.8% of old patients [hazard ratio 8.03 (95% CI 1.83–51.49), p = 0.002]. By multivariate analyses, age groups and leukocytic count were independent predictors of infection (bacteria and pneumolysin), p = 0.027 and p < 0.0001, respectively. Optimal cutoff value of leukocytic count was 12,250 cells/μl [ROC curve sensitivity 85.7%, specificity 86.4%, and AUC 0.97 (95% CI 0.95–1.0), p < 0.001]. Infection was an independent predictor of STEMI in young versus old patients, p < 0.001. Nevertheless, in-hospital events occurred insignificantly different and neither age groups nor infection was predictor of in-hospital events.

Conclusions

Young patients had significantly higher percentage of bacteria in their infarcted artery than old patients. High leukocytic count in patients below 50 predicts infection that causes acute myocardial infarction. Antibacterial trials directed toward this group are required for secondary prevention.

Differences in healthcare visit frequency and type one year prior to stroke among young versus middle-aged adults

Background

The incidence and prevalence of stroke among the young are increasing in the US. Data on healthcare utilization prior to stroke is limited. We hypothesized those < 45 years were less likely than those 45–65 years old to utilize healthcare in the 1 year prior to stroke.

Methods

Patients 18–65 years old who had a stroke between 2008 and 2013 in MarketScan Commercial Claims and Encounters Databases were included. We used descriptive statistics and logistic regression to examine healthcare utilization and risk factors between age groups 18–44 and 45–65 years. Healthcare utilization was categorized by visit type (no visits, inpatient visits only, emergency department visits only, outpatient patient visits only, or a combination of inpatient, outpatient or emergency department visits) during the year prior to stroke hospitalization.

Results

Of those 18–44 years old, 14.1% had no visits in the year prior to stroke compared to 11.2% of individuals aged 45–65 [OR = 1.30 (95% CI 1.25,1.35)]. Patients 18–44 years old had higher odds of having preventive care procedures associated with an outpatient visit and lower odds of having cardiovascular procedures compared to patients aged 45–65 years. Of stroke patients aged 18–45 and 45–65 years, 16.8 and 13.2% respectively had no known risk for stroke.

Conclusions

Patients aged 45–65 were less commonly seeking preventive care and appeared to be seeking care to manage existing conditions more than patients aged 18–44 years. However, as greater than 10% of both age groups had no prior risk, further exploration of potential risk factors is needed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-021-06064-5.

Seasonality of Influenza-Like-Illness and Acute Cardiovascular Events Are Related Regardless of Vaccine Effectiveness

Background

Influenza has been identified as a trigger for stroke and myocardial infarction (MI) with prior studies demonstrating that influenza vaccination may decrease risk of stroke and MI.

Methods and Results

We used data from the New York Department of Health Statewide Planning and Research Cooperative System to evaluate whether annual variability in influenza vaccination effectiveness (VE) would be associated with cardiovascular events. Daily and monthly counts of outpatient and inpatient visits for influenza‐like illness (ILI), stroke, and MI were identified using International Classification of Diseases, Ninth Revision (ICD‐9) codes; VE data for each year are publicly available. We identified pertinent lags between ILI, stroke, and MI using prewhitening cross‐correlation functions and applied them to autoregressive integrated moving average time series regression models. Time series forecasting systems assessed correlations among ILI, stroke, and MI, and the effect of VE on these relationships. Cross‐correlation functions indicated stroke events increased 1 month after increases in ILI rates; MIs increased immediately. Accounting for seasonality and lag, peaks in ILI rates were significantly related to peaks in stroke (P=0.04) and MI (P=0.01). Time forecasting analyses indicated no relationship between VE and cardiovascular events.

Conclusions

We identified that seasonality of cardiovascular events may be associated with seasonality in ILI, though VE did not modify this relationship.

Hepatitis C virus and cumulative infections are associated with atherogenic cardiovascular events in HIV-infected subjects

OBJECTIVES

to analyze the association between HCV coinfection and cumulative infections with the development of a cardiovascular disease in HIV-infected subjects.

METHODS

HIV-infected subjects attended at Virgen del Rocio University Hospital, between January 1982 and March 2018, were considered if fulfilled the following criteria: at least two visits to the HIV clinic, clinical records with data about VZV reactivation and bacterial infections, available data on HCV coinfection status. Atherogenic cardiovascular events were registered. To analyze factors associated with the development of cardiovascular event, a logistic regression analysis was performed.

RESULTS

823 subjects were included in the study. During the observational period, 58/823 (7.05%) developed a cardiovascular event. Advanced age at HIV-1 diagnosis, a low T-CD4 nadir, HCV coinfection and the burden of infections were independently associated with the risk of developing a cardiovascular event, apart from lipid levels and diabetes.

CONCLUSIONS

both HCV and the burden of infections are associated with an increased risk of cardivascular event in HIV-infected patients, together with other cardiovascular risk factors. Therapeutic strategies such as HCV erradication or VZV immunization could ameliorate cardiovascular risk in these subjects.

Molecular characterisation of Chlamydia pneumoniae associated to atherosclerosis

Chlamydia pneumoniae is a respiratory pathogen associated with chronic inflammatory diseases such as asthma and atherosclerosis, and its detection in human carotid and coronary atheroma suggests some support for its involvement in atherogenesis. The main objective of our study was to evaluate the association between Chlamydia pneumoniae and atherosclerosis in Moroccan patients through a case-control approach and detected strain genotyping. A total of 137 cases and 124 controls were enrolled, nested PCR was performed for Chlamydia pneumoniae screening of the peripheral blood mononuclear cells (PBMCs) of both cases and controls as well as atheroma plaques from 37 cases, and positive samples were subjected to sequencing for genotyping and phylogenetic analysis. The results showed 54% and 18%, respectively, for positivity in cases and control PBMCs and 86.5% in atheroma plaques, the difference being significant between the two groups (P < 0.001, ORa = 8.580, CI, 95% [3.273-22.491]). Strain sequence analyses showed more than 98% similarity with human reference strains, and revealed various genotypes. This study supports the involvement of Chlamydia pneumoniae in atherosclerosis in the studied population and genotyping revealed that detected strains were identical to human strains circulating worldwide.

Association between influenza vaccination and reduced risks of major adverse cardiovascular events in elderly patients

BACKGROUND

This study was conducted to determine the protective effect of influenza vaccine against primary major adverse cardiovascular events (MACEs) in elderly patients, especially those with influenza-like illness (ILI).

METHODS

This retrospective, population-based case-control study of an elderly population (age≥65 years) was conducted using Taiwan's National Health Insurance Research Database (2000-2013). One control was selected for each MACE case (n=80,363 each), matched according to age, year of study entry, and predisposing factors for MACEs. ILI and MACEs (myocardial infarction [MI] and ischemic stroke) were defined according to the International Classification of Diseases, Ninth Revision, Clinical Modification. Odds ratios (ORs) were calculated for the association between MACEs and vaccination.

RESULTS

Influenza vaccination received in the previous year was associated with reduced risks of primary MACEs overall (adjusted OR [aOR] 0.80, 95% CI 0.78-0.82, P<.001), MI (aOR 0.80, 95% CI 0.76-0.84, P<.001), and ischemic stroke (aOR 0.80, 95% CI 0.77-0.82, P<.001). ILI diagnosed in the previous year was associated with increased risks of MACEs (aOR 1.24, 95% CI 1.18-1.29, P<.001), MI (aOR 1.46, 95% CI 1.34-1.59, P<.001), and ischemic stroke (aOR 1.16, 95% CI 1.10-1.22, P<.001). Vaccination attenuated the heightened risks associated with ILI (MACEs: aOR 0.99, 95% CI 0.92-1.07, P=.834; MI: aOR 1.05, 95% CI 0.92-1.21, P=.440; ischemic stroke: aOR 0.96, 95% CI 0.89-1.05, P=.398).

CONCLUSIONS

Results of this study suggest that influenza vaccination is associated with reduced primary MACE risks in the elderly population, including those with ILI.

Increased risk of acute coronary syndrome among leptospirosis patients: A nationwide cohort analysis

BACKGROUND

Studies on the association between leptospirosis and acute coronary syndrome (ACS) are lacking. Therefore, this study identifies the effects of leptospirosis on the risks of developing ACS with a nationwide retrospective cohort study.

METHODS

We identified adult patients aged ≥20 years who were newly diagnosed with leptospirosis. We also randomly selected a comparison cohort from the general population by using a propensity score matching method. We analyzed the risks of ACS by using Cox proportional hazard regression models.

RESULTS

Among the 23.74 million people in the cohort, 3690 patients with leptospirosis (68% men, mean age of 52.2 years) and 3690 controls were followed for 13,677 and 15,652 person-years, respectively. The overall incidence of ACS was higher in the leptospirosis cohort than in the nonleptospirosis cohort (4.68 vs 3.71 per 1000 person-years), with a hazard ratio (HR) of 1.69 (95% confidence interval [CI]=1.12-2.56). Men exhibited a 1.88-fold greater HR of ACS than women did (95% CI=1.20-2.94). The risk of developing ACS was highest for leptospirosis patients aged ≥65 years (HR=7, 51% CI=4.35-12.9) compared with patients aged ≤49 years.

CONCLUSION

Leptospirosis is not a previously identified risk factor for ACS. The findings of this nationwide retrospective cohort study indicate that leptospirosis may become an independent risk factor for ACS. Future research to investigate the mechanism is warranted.

Higher immunoglobulin G antibody levels against cytomegalovirus are associated with incident ischemic heart disease in the population-based EPIC-Norfolk cohort

BACKGROUND

Cytomegalovirus (CMV) is associated with ischemic heart disease (IHD) among organ transplant recipients. The relationship between the levels of antibody for CMV with IHD in immunocompetent individuals is uncertain.

METHODS

We measured baseline CMV immunoglobulin G (IgG) levels in 12,574 participants without IHD from the population-based EPIC-Norfolk cohort, aged 40-70 years old at recruitment in 1993-1997. Underlying causes of death or hospitalization until 31 March 2008 were abstracted from death certificates and a database of hospital admissions, respectively.

RESULTS

Of the participants, 58% were seropositive for CMV. After a mean follow-up of 12 years (standard deviation, 2.2 years), 1356 first-time IHD events occurred. After adjustment for classic IHD risk factors, belonging to the highest antibody group was associated with an increased risk of incident IHD, compared with seronegativity (hazard ratio, 1.22; 95% confidence interval, 1.05-1.42). After additional adjustment for measures of social class, inflammation, and possible confounders, this association was unchanged (hazard ratio, 1.21; 95% confidence interval, 1.04-11.41).

CONCLUSIONS

This is the first population study to show that CMV IgG antibody levels are related to incident IHD compared to seronegativity. Studies correlating CMV antibody levels with direct measurements of active infection will be necessary.

Hepatitis C virus infection and risk of coronary artery disease: a systematic review of the literature

BACKGROUND

Several chronic infections have been associated with cardiovascular diseases, including Chlamydia pneumoniae, human immunodeficiency virus and viral hepatitis. This review evaluates the literature on the association between chronic hepatitis C virus (HCV) infection and the risk of coronary artery disease (CAD).

METHODS

Studies were identified using several databases. Only studies on CAD in patients with HCV infection were included. A set of criteria for evaluating potential biases was made, based on known confounders and biases in observational research. Data were not synthesized because of the large heterogeneity in the included studies.

RESULTS

Twelve eligible references were identified. Nine did not comply with our criteria of minimizing bias, and six studies were evaluated as potentially heavily biased. The studies of the highest quality showed a trend towards association of HCV with CAD. Five studies showed this association (three studies significantly), while one showed that HCV was a protective factor against CAD.

CONCLUSION

Our findings suggest an increased risk of CAD in HCV-infected individuals. Further studies are needed to confirm this and to evaluate the magnitude of the association. Clinicians should be aware of this and strive to reduce CAD risk factors in patients with chronic HCV infection.

Cytomegalovirus infection and coronary heart disease risk: a meta-analysis

The chronic inflammatory process including cytomegalovirus (CMV) infection has been hypothesized to induce the progression of atherosclerosis in coronary heart disease (CHD). Numbers studies were conducted to analyze the association between CMV infection and risk of CHD, but no clear consensus had been reached. To assess this relationship more precisely, a meta-analysis was performed. The electronic databases PubMed, Embase, and CNKI were searched; data were extracted and analyzed independently by two investigators. Ultimately, 55 studies, involving 9,000 cases and 8,608 controls from six prospective studies (all with a nested case-control design) and 49 retrospective case-control studies were included. Overall, people exposed to CMV infection had an odds ratio (OR) of 1.67 (95% CI, 1.56-1.79) for CHD risk, relative to those not exposed. CMV infection was clearly identified as a risk factor for CHD in both prospective studies (OR, 1.31; 95% CI, 1.132-1.517) and retrospective studies (OR, 1.79; 95% CI, 1.659-1.939), and in both Asian group (OR, 2.69; 95% CI, 2.304-3.144) and non-Asian group (OR, 1.48; 95% CI, 1.371-1.600). Interestingly, in the subgroup analyses by detection methods of CMV, the increased risk (OR, 8.121) was greater among studies using polymerase chain reaction than the risk (OR, 1.561) among studies using enzyme-linked immunosorbent assay. In conclusion, this meta-analysis suggested that CMV infection is associated with an increased risk for CHD, especially among Asian populations.

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.

Chlamydia pneumoniae IgG and IgA antibody titers and prognosis in patients with coronary heart disease: results from the CLARICOR trial

The association observed between coronary heart disease (CHD) and Chlamydia (Chlamydophila) pneumoniae antibodies prompted, during the 1990s, several primary and secondary prevention trials with various antibiotics. In our CLARICOR trial, a randomized placebo-controlled trial in 4372 patients with stable CHD, a brief clarithromycin regimen was followed, unexpectedly, by increased long-term mortality. We now compare C. pneumoniae antibody levels at entry with population levels, with the patients' individual histories, and with their subsequent outcomes. IgG antibody levels were somewhat raised, but elevated IgA and IgG titers were unrelated to entry data (including prior acute myocardial infarction), except for an association with smoking and with not using statins. Hazards of mortality and of other outcomes tended to slightly increase with IgA and decrease with IgG titers, but the unfavorable clarithromycin effect was unrelated to antibody levels and remains unexplained. Smoking-related lung disease probably underlies the link between heart disease and increased IgG titers.

The autoimmune origin of atherosclerosis

Atherosclerosis is a chronic inflammatory disease. Many studies and observations suggest that it could be caused by an immune reaction against autoantigens at the endothelial level, the most relevant of which are oxidized LDL and heat shock proteins (HSP) 60/65. Endothelial dysfunction plays a fundamental role. The first antigen is related to the increased leakage and oxidation of LDL; the second to cellular reaction to stress. Experimental and clinical observations confirm the pathogenetic role of these antigens. Both innate and adaptive immunity and impaired regulatory mechanisms of the autoimmune reaction are involved. Different triggering factors are examined: infectious agents, smoking, air pollution, diabetes and hypercholesterolemia. Analogies and differences between systemic atherosclerosis and transplant-related coronary atherosclerosis help to understand their respective nature. Immune mechanisms might be responsible for the passage from stable plaque to unstable and rupture-prone plaque. Finally, prospects of treatment and prevention are linked to the induction of tolerance to responsible antigens, activation of immune regulatory response and the use of immunomodulatory drugs.

Simvastatin Reduces Chlamydophila pneumoniae –Mediated Histone Modifications and Gene Expression in Cultured Human Endothelial Cells

Inflammatory activation of the endothelium by Chlamydophila pneumoniae infection has been implicated in the development of chronic vascular lesions and coronary heart disease by seroepidemiological and animal studies. We tested the hypothesis that C pneumoniae induced inflammatory gene expression is regulated by Rho-GTPase–related histone modifications. C pneumoniae infection induced the liberation of proinflammatory interleukin-6, interleukin-8, granulocyte colony-stimulating factor, macrophage inflammatory protein-1β, granulocyte/macrophage colony-stimulating factor, and interferon-γ by human endothelial cells. Cytokine secretion was reduced by simvastatin and the specific Rac1 inhibitor NSC23766 but was synergistically enhanced by inhibitors of histone deacetylases trichostatin A and suberoylanilide hydroxamic acid. Infection of endothelial cells with viable C pneumoniae , but not exposure to heat-inactivated C pneumoniae or infection with C trachomatis , induced acetylation of histone H4 and phosphorylation and acetylation of histone H3. Pretreatment of C pneumoniae –infected cells with simvastatin or NSC23766 reduced global histone modifications as well as specific modifications at the il8 gene promoter, as shown by chromatin immunoprecipitation. Reduced recruitment of nuclear factor κB p65/RelA as well as of RNA polymerase II was observed in statin-treated cells. Taken together, Rac1-mediated histone modifications seem to play an important role in C pneumoniae –induced cytokine production by human endothelial cells.

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.

No prognostic significance of chronic infection with Chlamydia pneumoniae in acute coronary syndromes: insights from the Global Utilization of Strategies to Open Occluded Arteries IV Acute Coronary Syndromes trial

BACKGROUND

Although relationships between chronic Chlamydia pneumoniae (Cpn) infection and the risk of coronary events in stable coronary artery disease patients have been reported, a similar link in acute coronary syndrome (ACS) patients has not been consistently observed.

METHODS

In a nested case-control substudy of the Global Utilization of Strategies to Open Occluded Arteries IV Acute Coronary Syndromes trial, 295 cases (30-day death/myocardial infarction [MI]) were matched by age, sex, baseline creatine kinase-myocardial kinase, and smoking status with 295 control subjects. To test the hypothesis on 1-year mortality, another subset (n = 276) was drawn from the 590-patient cohort; 138 patients who died at 1 year plus the matching controls who survived at 1 year. We measured Cpn IgG and IgA antibody titers in baseline serum with microimmunofluorescence. Conditional logistic regression was used to quantify the prognostic relevance seropositivity (IgG > or = 1:32; IgA > or = 1:16) and elevated titer levels.

RESULTS

The prevalence of Cpn IgG and IgA was similar between cases and controls (30-day death/MI: IgG, 80% vs 85%, P = .126; IgA, 45% vs 37%, P = .079), and were not statistically significant predictors of 30-day death/MI after baseline adjustment. Likewise, the 1-year death cohort had comparable proportions of Cpn IgG and IgA among cases and controls (86% vs 91% [P = .265] and 49% vs 43% [P = .334], respectively), and did not add prognostic value.

CONCLUSIONS

These findings are in concert with study results suggesting that chronic Cpn infection is not associated with 30-day death/MI or 1-year mortality in non-ST elevation ACS.

Chlamydia pneumoniae antibody levels before coronary events in the Helsinki Heart Study as measured by different methods

The lack of specific tests for the diagnosis of chronic Chlamydia pneumoniae infection has led to the use of enzyme immunoassay (EIA) instead of the gold standard, that is, microimmunofluorescence (MIF), in the measurement of C. pneumoniae antibodies. We assessed the predictive values of C. pneumoniae antibody levels and seroconversions measured by MIF and EIA for coronary events in the prospective Helsinki Heart Study. Sera from 239 cases with coronary events and 239 controls were available at the baseline and data from 210 cases and 211 controls before and after the event. The agreement between MIF and EIA antibody levels was best in high antibody titers. In conditional logistic regression analysis, only high IgA MIF titers (>/=40) at the baseline predicted future coronary events, and the participants with MIF seroconversion between consecutive sera had a higher (nonsignificant) risk for coronary events than the controls. The difference in the kinetics of EIA and MIF antibodies demonstrated that MIF should remain the gold standard.

A Microbial TLR2 Agonist Imparts Macrophage-Activating Ability to Apolipoprotein A-1

There is increasing epidemiologic evidence implying a role for chronic infection in atherosclerosis and that microbial TLR agonists may contribute to this disease. Mycoplasma arthritidis is an agent of acute and chronic inflammatory disease in rodents, and has been used extensively as a model for defining the mechanisms involved in arthritis and other inflammatory diseases. We have purified a 28-kDa, apolipoprotein A-1 (apoA-1)-like TLR2-dependent macrophage-activating moiety from a culture of a virulent strain of M. arthritidis. ApoA-1 similarly isolated from uninoculated mycoplasma medium was without bioactivity. The activity of the mycoplasma-derived molecule was resistant to heat and to digestion with proteinase K, but was susceptible to alkaline hydrolysis and H(2)O(2) oxidation. Infrared profiles of normal apoA-1 and that derived from mycoplasma were distinct. Unlike the activity of other mycoplasmal TLR2 agonists such as macrophage-activating lipopeptide-2, activity of the M. arthritidis-derived 28-kDa component was dependent upon CD14, a coreceptor for LPS. Finally, we showed that bioactive lipopeptides prepared from M. arthritidis grown in serum-free medium and also from a 41-kDa known bioactive lipoprotein of M. arthritidis, avidly bound to purified apoA-1 that separated out by SDS-PAGE, induced TNF-alpha and IL-12p40 both in vitro and in vivo. ApoA-1 is a key functional component of the high-density lipoprotein cholesterol complex by scavenging and removing unwanted lipids. Our finding that this molecule can acquire macrophage-activating properties from microbial TLR2-dependent agonists suggests a novel mechanism whereby some microbial agents might reverse the protective role of apoA-1, thus contributing to the genesis of atherosclerosis.

Detection by broad-range real-time PCR assay of Chlamydia species infecting human and animals

BACKGROUND

Tests available for molecular diagnosis of chlamydial infections detect Chlamydiatrachomatis, but do not find other Chlamydia species associated with genital, ophthalmic, cardiovascular, respiratory or neurological diseases. The routine detection of all Chlamydia species would improve the prognosis of infected people and guide therapeutic choices.

AIM

To design and validate a sensitive, specific, reproducible, inexpensive and easy-to-perform assay to quantify most Chlamydia species.

METHODS

Primers and probe were selected using the gene coding for the 16S rRNA. The detection limits were assessed for suspensions of Chlamydia trachomatis, Chlamydia psittaci and Chlamydia pneumoniae. The performance of this test was compared with that of two commercial kits (Amplicor-Roche and Artus) on 100 samples obtained from children with trachoma.

RESULTS

The detection capacities for Chlamydia trachomatis of the broad-range real-time polymerase chain reaction (PCR) were similar or slightly better than those obtained with commercial kits (0.2 copies of DNA/microl). Only the broad-range PCR identified specimens containing Chlamydia psittaci and Chlamydia pneumoniae. The commercial kits and the broad-range assay detected Chlamydia species in 5% and in 11%, respectively, of samples from children with trachoma.

CONCLUSIONS

This new real-time PCR offers a sensitive, reproducible assay that produces results in <3 h. With panels of quantified Chlamydia species, this real-time PCR can be run with all real-time PCR equipment. Larger trials are needed to confirm the utility of this test in diagnosis and for therapeutic follow-up.

No association between hepatitis C virus seropositivity and acute myocardial infarction

Recent studies have linked hepatitis C virus (HCV) infection with carotid atherosclerosis. We investigated the association between HCV seropositivity and acute myocardial infarction using a well-established cohort of young men in the US military and found no evidence to support this association.

Chlamydia pneumoniae and vascular disease: an update

Exposure to Chlamydia pneumoniae is extremely common, and its incidence increases with age. C pneumoniae infection is strongly associated with coronary artery disease, as well as with atherosclerosis of the carotid artery, aorta, and peripheral arteries. This association has been shown in seroepidemiologic studies and by direct detection of the organism in atherosclerotic lesions by immunohistochemistry, polymerase chain reaction, electron microscopy, and tissue culture. Animal models of atherosclerosis have been used to study the role of C pneumoniae in the initiation and progression of atherosclerotic disease. The association of this organism with cardiovascular complications has inspired many human trials of antibiotics for the secondary prevention of atherosclerosis. C pneumoniae can infect several types of cells, including circulating macrophages, arterial smooth muscle cells, and vascular endothelial cells, causing the secretion of proinflammatory cytokines and procoagulants by endothelial cells and foam cell formation by infected macrophages. This report reviews the role of C pneumoniae in atherogenesis in light of recent, large antibiotic treatment trials, animal studies, and in vitro studies. The role of Chlamydia heat shock protein as a potential mediator of this harmful effect is also reviewed.

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.