With a high incidence of vascular disease, an understanding of the mechanisms underlying atherosclerosis and the formation of new vessels will be important in improving the quality of life in our elderly population. Angiogenesis is an important process in tumor growth, wound healing, atherosclerosis, ischemic heart disease, retinopathies, and rheumatoid arthritis. We are investigating aspects of angiogenesis in an in vitro model where proliferating human and bovine endothelial cells differentiate into a capillary-like structure on a mixture of basement membrane matrix proteins (Matrigel) or collagen gel. With the addition of TGF-B1, the endothelial cells within the capillary-like network will undergo programmed cell death (apoptosis). In order to understand the molecular mechanisms involved in this process, we are introducing genes into these cells that ma increase and other genes that may inhibit apoptosis. The ability to revers or inhibit vascularization has implications in the treatment of tumors and in fibroproliferative diseases such as atherosclerosis. We are also studying vascular smooth muscle cells (VSMC) that through migration and proliferation are important components of atherosclerosis and restenosis after angioplasty. While the involvement of inflammatory cells is well established as an early event in human atherosclerosis, a basic understanding of the interactions between inflammatory cells and VSMC is lacking. Gamma interferon secreted by activated T cells induces class II antigens, inhibits smooth muscle proliferation and extracellular matrix synthesis, and activates macrophages. We found in VSMC that gamma interferon increased the expression of a nuclear transcription factor - p91 a chemoattractant for monocytes - JE, and a nitric oxide synthesizing enzym iNOS. Additionally, gamma interferon treatment of quiescent vascular smoot muscle cells for 18 hr dramatically increased the random migration of the cells in the Boyden Chamber assay. We also found that the product of gamma interferon, p91, is translocated to the nucleus likely from sites associate with the cytoskeleton of VSMC within minutes after the addition of PDGF-BB. Since atherosclerotic lesions are sites of gamma interferon release from inflammatory cells at an early time, gamma interferon's direct action on smooth muscle cells and the indirect action of modifying the signalling of other factors (e.g. p91) may be important to our understanding of atherosclerosis.
