Serological Evidence of Chronic Chlamydia pneumoniae Infection in Coronary Artery Disease

Bacterial Infections and Atherosclerosis – A Mini Review

Atherosclerosis is the most challenging subsets of coronary artery disease in humans, in which risk factors emerge from childhood, and its prevalence increases with age. Experimental research demonstrates that infections due to bacteria stimulate atherogenic events. Atherosclerosis has complex pathophysiology that is linked with several bacterial infections by damaging the inner arterial wall and heart muscles directly and indirectly by provoking a systemic pro-inflammation and acute-phase protein. Repeated bacterial infections trigger an inflammatory cascade that triggers immunological responses that negatively impact cardiovascular biomarkers includes triglycerides, high-density lipoprotein, C-reactive protein, heat shock proteins, cytokines, fibrinogen, and leukocyte count. Herein, we intended to share the role of bacterial infection in atherosclerosis and evaluate existing evidence of animal and human trials on the association between bacterial infections and atherosclerosis on update.

Association of Chlamydia trachomatis, C. pneumoniae, and IL-6 and IL-8 Gene Alterations With Heart Diseases

Atherosclerosis is a progressive disease characterized by chronic inflammation of the arterial walls, associated with genetic and infectious factors. The present study investigated the involvement of Chlamydia trachomatis and Chlamydia pneumoniae infections and immunological markers (C-reactive protein, CRP, TNF-α, IL-6, IL-8, and IL-10) in the process of atherosclerosis. The evaluation included 159 patients for surgical revascularization (CAD) and 71 patients for surgical heart valve disease (HVD) at three hospitals in Belém, Brazil. The control group (CG) comprised 300 healthy individuals. Blood samples collected before surgery were used for antibodies detection (enzyme immunoassay), CRP (immunoturbidimetry) and IL-6 levels (enzyme immunoassay). Tissue fragments (atheroma plaque, heart valve and ascending aorta) were collected during surgery and subjected to qPCR for detection of bacterial DNA. Promoter region polymorphisms of each marker and relative quantification of TNF-α, IL-8, and IL-10 gene expression were performed. Demography and social information were similar to the general population involved with both diseases. Antibody prevalence to C. trachomatis was 30.6, 20.3, and 36.7% (in the CAD, HVD, and CG, respectively) and to C. pneumoniae was 83.6, 84.5, and 80.3% (in the CAD, HVD, and CG, respectively). C. trachomatis cryptic plasmid DNA was detected in 7.4% of the samples. Frequency of IL6−174G>C polymorphism was higher in CAD and HVD than in CG regardless of previous exposure to Chlamydia. Previous C. trachomatis infection showed involvement in HVD and CAD. Significant association between disease and previous C. pneumoniae infection was found only among HVD. GG genotype of IL6−174G>C is apparently a risk factor for heart disease, whereas AT genotype of IL8−251A>T was mainly involved in valvulopathies, including patients with prior exposure to C. pneumoniae.

Prevalence of Helicobacter pylori, cytomegalovirus, and Chlamydia pneumoniae immunoglobulin seropositivity in coronary artery disease patients and normal individuals in North Indian population

BACKGROUND

In present day atherosclerosis is perceived as a chronic inflammatory vascular condition and infectious diseases are believed to contribute to its pathophysiology. In this context, the microorganisms which are believed to play a role in the pathophysiology include Chlamydia pneumoniae, cytomegalovirus (CMV), and Helicobacter pylori.

METHOD

A case control study (retrospective) was conducted over a two-year period. The study population was divided into two groups with 200 individuals in each group. The first group comprised cases of coronary artery disease (CAD) and the second comprised healthy controls selected from the general population after matching for age and sex. Enzyme-linked immunosorbent assay (ELISA) was done for immunoglobulin (IgG) antibodies to H. pylori, C. pneumonia, and CMV. They were also evaluated for conventional risk factors including hypertension, diabetes, obesity, and dyslipidaemia. Epi Info™ version 6 six software was used for analysis of data. Odds ratio, χ(2) for trend and multiple logistic regression analysis were used to find out statistically significant results.

RESULTS

Seropositivity for H. pylori was present in 119 patients of CAD (59.5%) but it was present in only 76 controls (38%) (P = 0.001). There was a statistically significant association between seropositivity for H. pylori and CAD. There was no statistically significant association between C. pneumoniae and CMV seropositivity with CAD. Multiple logistic regression analysis was done with CAD as the outcome (dependent variable). The predictor covariates (independent) variables were seropositivity to H. pylori, C. pneumoniae, and CMV, hypertension, obesity, diabetes, and dyslipidaemia. It was found that seropositivity to H. pylori, hypertension, obesity, and dyslipidaemia were significant risk factors for CAD.

CONCLUSION

Our study shows an association between IgG antibody response to H. pylori and CAD. Multiple logistic regression analysis showed that this association was retained even on comparison with the other risk factors.

Seroprevalence of Chlamydia pneumoniae antibodies in stroke in young

BACKGROUND

Younger patients, aged below 45 years, usually lack the conventional risk factors of stroke whereas infections, especially in developing countries, may play a role. There have been many reports in the last decade about the association of Chlamydia pneumoniae (C. pneumoniae) and atherosclerosis involving cerebral vessels.

OBJECTIVE

To investigate the seroprevalence of C. pneumoniae IgG and IgA antibodies in patients aged below 45 years with acute ischemic stroke.

METHODS

This study was done at a tertiary care hospital in South India between January 2004 and December 2006 where we recruited consecutive patients aged less than 45 years with acute ischemic stroke. Age and sex matched controls were recruited from the outpatient department with non stroke diagnosis. All stroke patients underwent CT (Computerized Tomography), MRI (Magnetic Resonance Image), MRA (Magnetic Resonance Angiography), Transthoracic Echocardiography and Carotid Doppler for stroke sub group diagnosis. We measured C. pneumoniae antibodies IgG and IgA by microimmunofluorescence technique in all patients and controls.

RESULTS

A total of 120 patients and 120 controls were studied over a period of two years. We found C. pneumoniae antibodies in 29.1% (35/120) stroke patients and in 12.5% (15/120) control subjects (p=0.002). C. pneumoniae IgG antibodies were found in 27.5 % (33/120) of stroke patients and 12.5% (15/120) of controls (p=0.006). IgA antibodies were observed in 5% (6/120) of strokes and none in control group (p=0.03). After adjustment of all risk factors C. pneumoniae IgG seropositivity showed odds ratio of 2.6; 95% Confidence Interval 1.2-5.6.

CONCLUSIONS

C. pneumoniae IgG antibodies were found to be associated with ischemic stroke in young.