Investigation of Chlamydia Pneumoniae Specific Effects on eNOS Trafficking and NO Production in Aortic Endothelial Cells.

Chlamydia pneumoniae is an obligate intracellular parasite infecting primarily the human respiratory tract. However, this pathogen has also been associated with a variety of chronic diseases including atherosclerosis. Unlike any other chlamydial species, C. pneumoniae displays a tropism towards cardiovascular tissue as this microorganism has been detected in more than 50% of atherosclerotic lesions. The relevance of C. pneumoniae in the pathogenesis of atherosclerosis has also been previously supported by data obtained from studies of C. pneumoniae infected mice and rabbits where the infection with the microorganism led to acceleration in the development of atherosclerotic plaque. However, the role of this pathogen in atherogenesis is still unknown. In this study I propose to demonstrate a species-specific interaction between the microorganism and the endothelial nitric oxide synthase (eNOS) in C. pneumoniae infected primary human aortic endothelial cells (HAECs). In these cells, C. pneumoniae appear to intercept trafficking of the enzyme from the Golgi apparatus to the cytoplasmic membrane. eNOS is a constitutively expressed nitric oxide synthase which undergoes a series of co-translational as well as post-translational modifications essential for an adequate function of the enzyme. Typically, eNOS is trafficked from the Golgi apparatus to the plasmalemmal caveolae where it binds to caveolin-1. Failure of eNOS to recycle between the Golgi apparatus and the cytoplasmic membrane leads to inability of the enzyme to produce NO. I hypothesize that infection of endothelial cells with C. pneumoniae leads to chronic mislocation of eNOS into the cytoplasmic compartment and the inability of the enzyme to respond to the stimulation with agonists which results in impaired NO production of the infected endothelium. Lack of NO generation by eNOS has been linked to an activation of endothelial cells which is manifested by up-regulation and expression of surface adhesive molecules mediating an attachment of platelets, leukocytes and monocytes to the endothelium. Thus, I further propose that the infection of endothelial cells with C. pneumoniae leads to up-regulation of these surface receptors. Data from this proposal will elucidate the possibility of including an infection with C. pneumoniae to the list of risk factors contributing to the pathogenesis of atherosclerosis.