Association of Carotid Plaque Lp-PLA2 with Macrophages and Chlamydia pneumoniae Infection among Patients at Risk for Stroke
نویسندگان
چکیده
BACKGROUND We previously showed that the burden of Chlamydia pneumoniae in carotid plaques was significantly associated with plaque interleukin (IL)-6, and serum IL-6 and C-reactive protein (CRP), suggesting that infected plaques contribute to systemic inflammatory markers in patients with stroke risk. Since lipoprotein-associated phospholipase A2 (Lp-PLA(2)) mediates inflammation in atherosclerosis, we hypothesized that serum Lp-PLA(2) mass and activity levels and plaque Lp-PLA(2) may be influenced by plaque C. pneumoniae infection. METHODOLOGY/PRINCIPAL FINDINGS Forty-two patients underwent elective carotid endarterectomy. Tissue obtained at surgery was stained by immunohistochemistry for Lp-PLA(2) grade, macrophages, IL-6, C. pneumoniae and CD4+ and CD8+ cells. Serum Lp-PLA(2) activity and mass were measured using the colorimetric activity method (CAM) and ELISA, respectively. Serum homocysteine levels were measured by HPLC. Eleven (26.2%) patients were symptomatic with transient ischemic attacks. There was no correlation between patient risk factors (smoking, coronary artery disease, elevated cholesterol, diabetes, obesity, hypertension and family history of genetic disorders) for atherosclerosis and serum levels or plaque grade for Lp-PLA(2). Plaque Lp-PLA(2) correlated with serum homocysteine levels (p = 0.013), plaque macrophages (p<0.01), and plaque C. pneumoniae (p<0.001), which predominantly infected macrophages, co-localizing with Lp-PLA(2). CONCLUSIONS The significant association of plaque Lp-PLA(2) with plaque macrophages and C. pneumoniae suggests an interactive role in accelerating inflammation in atherosclerosis. A possible mechanism for C. pneumoniae in the atherogenic process may involve infection of macrophages that induce Lp-PLA(2) production leading to upregulation of inflammatory mediators in plaque tissue. Additional in vitro and in vivo research will be needed to advance our understanding of specific C. pneumoniae and Lp-PLA(2) interactions in atherosclerosis.
منابع مشابه
Distribution of Chlamydia pneumoniae infection in the athersclerotic carotid artery.
BACKGROUND AND PURPOSE Chlamydia pneumoniae infection has recently become noteworthy in relation to atherosclerosis. We investigated by immunohistochemistry the distribution of C pneumoniae infection in the atherosclerotic carotid artery. METHODS Twenty carotid atherosclerotic lesions that were resected during carotid endarterectomy were investigated. Parallel sections were stained immunohist...
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Background and Purpose—Chlamydia pneumoniae infection has recently become noteworthy in relation to atherosclerosis. We investigated by immunohistochemistry the distribution of C pneumoniae infection in the atherosclerotic carotid artery. Methods—Twenty carotid atherosclerotic lesions that were resected during carotid endarterectomy were investigated. Parallel sections were stained immunohistoc...
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