Chlamydia pneumoniae Infection of Vascular Smooth Muscle and Endothelial Cells Activates NF-κB and Induces Tissue Factor and PAI-1 Expression

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Abstract
Background —Recent reports link C. pneumoniae infection of arteriosclerotic lesions to the precipitation of acute coronary syndromes, which also feature tissue factor and plasminogen activator inhibitor 1 (PAI-1) overexpression. We investigated whether or not C. pneumoniae can induce thrombogenicity by upregulation of procoagulant proteins. Methods and Results —Human vascular endothelial and smooth muscle cells were infected with a strain of C. pneumoniae isolated from an arteriosclerotic coronary artery. Tissue factor, PAI-1, and interleukin-6 expression was increased in infected cells. Concomitantly, NF-κB was activated and IκBα degraded. p50/p65 heterodimers were identified as the components responsible for the NF-κB activity. Conclusions —These data provide evidence that C. pneumoniae infection can induce procoagulant protein and proinflammatory cytokine expression. This cellular response is accompanied by activation of NF-κB. Our results demonstrate how C. pneumoniae infection may initiate acute coronary syndromes.