CYTOMEGALOVIRUS ACTIVATION OF VASCULAR CELL SIGNALING

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Vascular injury is an important element in a number of lung disorders such as the acute respiratory distress syndrome (ARDS). Enhanced proliferation of vascular smooth muscle is a characteristic feature in diseases associated with pulmonary hypertension, as well as in atherosclerosis. More subtle forms of sublethal injury to the vasculature may occur with viral infections. Viral infection of vascular cells by herpesviruses, such as cytomegalovirus (CMV), may represent a unique way of activating these cells to participate in the organ-specific recruitment of inflammatory cells via expression of adhesion molecules and cytokines, the amplification of local tissue injury and stimulation of smooth muscle cell proliferation via the release of growth factors. This project is designed to test the hypothesis that herpesviral infection of vascular cells in vitro results in the intracellular activation of specific signal transduction pathways such as nuclear factor NF-kB and/or the activity of tyrosine kinases. The consequences of signal transduction activation on the expression of cellular genes for proinflammatory cytokines such as IL-1, IL-6, and TNF-a and growth factors such as basic FGF will be assessed via Northern blotting nd luciferase assays. The production of specific protein products will be measured by ELISA. The biological activity of these species in the conditioned of specific media of virally-infected vascular cells will be measured in bioassays such as mitogenesis of target smooth muscle cells, and effects on adhesion of monocyte/macrophages and neutrophils to virally-infected endothelial cells. The expression of cellular adhesion molecules on CMV-infected endothelial cells will be evaluated by flow cytometry. The pattern of cytokine activation will be compared with the production of cytokines by alveolar macrophages recovered from bronchoalveolar lavage fluid of bone marrow transplant patients with pneumonitis, with and without CMV infections, as well as to normal alveolar macrophages infected with CMV in vitro to develop an understanding of the interplay between he vasculature and inflammatory cells. These data will help to define the molecular mechanisms of vascular activation induced by viral infection, which may be important in understanding clinical disorders such as CMV pneumonitis in bone marrow transplant recipients.