Alterations in the vascular endothelium are hallmarks of periodontal inflammation. The clinical findings of erythema, edema, and bleeding on probing, have microanatomical correlates including morphologic evidence of endothelial cell 'activation', endothelial-leukocyte interactions, increased microvascular permeability, and alterations in the endothelium- associated extracellular matrix. Such findings suggest that significant changes occur in the functional properties of vascular endothelial cells (EC) at inflammatory foci in the periodontium. An understanding of the role of EC in inflammatory reactions should provide insights into the pathogenesis of the periodontal diseases. Specifically, we will test the effects of monokines derived from activated mononuclear cells during inflammation on EC in cell culture. Interleukin-1 beta (IL-1) and tumor necrosis factor-alpha (cachectin; TNF) are two monokines found to be important inflammatory mediators. Both IL-1 and TNF are also found at sites of periodontal inflammation. Monokine-induced alterations in EC synthesis of extracellular matrix components may occur at tissue sites of periodontal inflammation. Such alterations may in turn serve to further modulate EC and inflammatory cell function. We will determine the effects of IL-1 and TNF on cultured EC extracellular matrix synthesis by analyzing the a) quantitative changes in endothelial cell synthesis of collagens and proteoglycans, b) qualitative changes in the types of collagens and proteoglycans synthesized and secreted by endothelial cells in response to IL-1 and TNF, c) differences in the monokine-induced synthesis of these extracellular matrix components between confluent versus growing endothelial cell cultures, and d) functional properties of the extracellular matrix synthesized by endothelial cells treated with monokines. Cloned EC from strain 2 inbred guinea pigs will be used to compare responses of large vessel-derived and microvascular EC. Similar comparisons between macrovascular and microvascular EC from human tissue sources will also be carried out, including the use of human microvascular EC obtained from human gingiva and foreskin dermis. The methods of obtaining and culturing EC from various tissue sources from both humans and guinea pigs are well established in our laboratory, including the clonal growth of guinea pig EC. The work proposed will yield needed new information on the responses of endothelial cells to inflammatory mediators, and should help to clarify how EC respond during inflammatory reactions in vivo. Of particular novelty and importance will be the results of experiments on microvascular endothelial cell extracellular matrix synthesis in response to IL-1 and TNF. The prior research experience of our laboratory with microvascular EC, obtained from both guinea pig and human tissues, makes us ideally situated to carry out such experiments.
