Chlamydia pneumoniae and atherosclerosis

Chlamydia pneumoniae antibodies in various subtypes of ischemic stroke in Indian patients

BACKGROUND

As infections occur more frequently in developing countries, we carried out this prospective case-control study, to establish the association, if any, between C. pneumoniae antibodies and ischemic stroke particularly in relation to its subtypes.

DESIGN

Antibodies (IgG and IgA) to C. pneumoniae in serum were measured by microimmunofluorescence test in 200 consecutive ischemic stroke patients and 200 age and sex matched controls.

RESULTS

Seventy two out of 200 ischemic stroke patients (36%) had positive C. pneumoniae antibodies (IgG or IgA), compared to 35 out of 200 controls (17.5%) (p<0.0001). IgG antibody was positive in 64/200 (32%) ischemic stroke patients, compared to 34/200(17%) controls (p<0.0001) and IgA was positive in 20/200(10%) ischemic stroke patients compared to 1/200(0.5%) controls (p<0.0001). Logistic regression analysis showed statistically significant association between C. pneumoniae antibody positivity and ischemic stroke, thereby establishing it as an independent risk factor. Prevalence of C. pneumoniae antibodies was significantly higher in all stroke subtypes (except the stroke of undetermined etiology) compared to controls.

CONCLUSION

Significant and independent association was found between C. pneumoniae antibodies and ischemic stroke in this sample of south Indian population. The association was found in all ischemic stroke subtypes, except stroke of undetermined etiology.

Secretory phospholipase A2 of group IIA: Is it an offensive or a defensive player during atherosclerosis and other inflammatory diseases?

Since its discovery in the serum of patients with severe inflammation and in rheumatoid arthritic fluids, the secretory phospholipase A2 of group IIA (sPLA2-IIA) has been chiefly considered as a proinflammatory enzyme, the result of which has been very intense interest in selective inhibitors of sPLA2-IIA in the hope of developing new and efficient therapies for inflammatory diseases. The recent discovery of the antibacterial properties of sPLA2-IIA, however, has raised the question of whether the upregulation of sPLA2-IIA during inflammation is to be considered uniformly negative and the hindrance of sPLA2-IIA in every instance beneficial. The aim of this review is for this reason, along with the results of various investigations which argue for the proinflammatory and proatherogenic effects of an upregulation of sPLA2-IIA, also to array data alongside which point to a protective function of sPLA2-IIA during inflammation. Thus, it could be shown that sPLA2-IIA, apart from the bactericidal effects, possesses also antithrombotic properties and indeed plays a possible role in the resolution of inflammation and the accelerated clearance of oxidatively modified lipoproteins during inflammation via the liver and adrenals. Based on these multipotent properties the knowledge of the function of sPLA2-IIA during inflammation is a fundamental prerequisite for the development and establishment of new therapeutic strategies to prevent and treat severe inflammatory diseases up to and including sepsis.

Cytomegalovirus and Chlamydia pneumoniae as predictors for adverse events and angina pectoris after percutaneous coronary intervention

BACKGROUND

The aim of our study was to investigate the influence of prior cytomegalovirus (CMV) or Chlamydia pneumoniae (CP) infection on prognosis after percutaneous coronary intervention (PCI).

METHODS

Using the enzyme-linked immunosorbent assay technique preprocedural anti-CMV immunoglobulin G and anti-CP immunoglobulin A (CP IgA), immunoglobulin M, and immunoglobulin G antibodies were measured. Repeat anginal complaints and major adverse clinical events (MACE), including PCI, coronary artery bypass grafting, myocardial infarction, and death, were recorded at 8-month follow-up.

RESULTS

Six hundred consecutive patients were included after successful PCI. Sixty-four percent of the patients were stented. The mean age was 61.6 years, and 68.9% were male. The rate of seropositivity for CP IgA in patients with MACE as compared with patients without MACE was 50.9% versus 35.4% (P =.0276). In patients with repeat anginal complaints, CP IgA seropositivity was 41.6% versus 34.6% in patients without repeat angina (P =.1057). The negative effect of CP on prognosis was confirmed after calculating the odds ratios for MACE (1.9, 95% CI 1.1-3.3). The rates of seropositivity for anti-CMV immunoglobulin G were not significantly different between both groups, although we found an association between infectious burden and repeat angina pectoris (odds ratio 1.8, 95% CI 1.1-3.0).

CONCLUSIONS

We conclude that preprocedural seropositivity of CP IgA is a risk factor for MACE and angina pectoris after PCI. Although no such relation was found for CMV alone, the cumulative infectious burden was also related to these clinical manifestations of restenosis.

Chlamydophila pneumoniae infection of human aortic endothelial cells induces the expression of FC gamma receptor II (FcgammaRII)

Chronic endothelial infection is believed to be one of the factors able to cause endothelial cell damage and trigger the onset of human atherosclerosis. Chlamydophila pneumoniae infects endothelial cells and has received special attention because of both epidemiological and experimental evidence supporting its role as a risk factor for atherosclerosis. It is also possible that otherwise independent risk factors for atherosclerosis may have synergistic effects. Immune phenomena, such as the formation of circulating immune complexes (IC) containing modified LDL and corresponding antibodies, have been linked to the development of coronary artery disease. The antibodies involved in the immune response to modified lipoproteins are predominantly of the pro-inflammatory IgG1 and IgG3 subclasses. However, it is difficult to understand how circulating IC could cause endothelial damage and initiate the atherosclerotic process, unless they were formed in the subendothelial space or immobilized by endothelial cells. The last hypothesis would be possible if endothelial cells expressed Fcgamma receptors. Healthy endothelial cells do not express Fcgamma receptors, but endothelial cells infected by a variety of infectious agents do. Thus we decided to investigate whether infection of endothelial cells with C. pneumoniae is also able to cause the expression of Fcgamma receptors. The expression of Fcgamma receptors (CD64, 32, and 16) on human aortic endothelial cells infected with C. pneumoniae for 4, 24, 36, and 48 h was studied by flow cytometry. Twenty-four hours after infection 30-40% of the endothelial cells had detectable inclusion bodies, 8-9% of the total number of cells (approximately 25% of the infected cells) expressed FcgammaRII, and about 1.5-2% (5% of infected cells) expressed FcgammaRI and FcgammaRIII. Double-staining studies confirmed that the expression of FcgammaRII was limited to C. pneumoniae-infected endothelial cells. We conclude that C. pneumoniae infection induces primarily the expression of FcgammaRII by endothelial cells and this may be a significant link between two proposed pathogenic mechanisms involved in the pathogenesis of human atherosclerosis.

Stroke prevention therapy beyond antithrombotics: unifying mechanisms in ischemic stroke pathogenesis and implications for therapy: an invited review

BACKGROUND

It is estimated that about half of cardiovascular disease risk is explained by conventional risk factors. The realization that atherosclerosis is an inflammatory disease has led to a search for new stroke and cardiovascular disease risk factors and treatments. As such, the vulnerable atherosclerotic plaque has become the main focus for new medical strategies for plaque stabilization and stroke prevention.

SUMMARY OF REVIEW

In this invited review, I discuss inflammation as a possible risk factor for stroke, unifying mechanisms in ischemic stroke pathogenesis, and new avenues for stroke prevention---statin agents, angiotensin-converting enzyme inhibitors, and vitamins. These new stroke prevention therapies may help to reduce inflammation, serve to stabilize the atherosclerotic plaque, or act by other protective mechanisms.

CONCLUSION

Beyond the traditional antithrombotic agents, statin agents, angiotensin-converting enzyme inhibitors, and vitamins may prove to be important additions to our armamentarium for stroke prevention.