This project's long-range goal is to define the biological role of fibronectin (Fn), a plasma and tissue matrix protein, in inflammatory processes. This project addresses two subjecta: epithelial wound healing and macrophage activation. Fn mediates cell attachment to collagen and fibrin (Fg), binds and activates macrophages, and is chemotactic for several cell types. Epithelial cells migrate over a substrate matrix of Fn/Fg in healing corneal and skin wounds. We hypothesize that the melecular form of Fn critically influences these diverse biological effects. We are determining whether this provisional matrix promotes epithelial migration by studying the effects of local application of polyclonal and monoclonal Fab antibody fragments to Fn, Fg, and laminin in healing guinea pig corneal wounds in vivo and in vitro (organ culture). We are characterizing the molecular form of Fn and Fg in the matrix by SDS-PAGE autoradiography and by antibody blot techniques and using this information to construct substrates for testing epithelial cell attachment in vitro. We have obtained one monoclonal antibody that distinguishes solid-phase and liquid-phase fibronectin. Our preliminary trials have suggested that exogenous fibronectin can promote corneal epithelial healing for deep, but not superficial, cornea wounds. Monocytes or macrophages recognize, bind, and synthesize Fn, yet the biological control of these processes is unknown. Macrophage interaction with Fn is being characterized in three ways by analyzing the form of Fn recognized by the macrophage by in vivo and in vitro binding studies; the modulation of antigen presentation, collagenase, and PGE?2? production and tumor killing by different forms of Fn; and the control of Fn synthesis by lymphokines. These studies employ analytic gel techniques, immunoelectron microscopy, in vivo animal experimentation, and in vitro studies of human cells. We have shown that gamma-interferon increases the number and effectiveness of macrophage fibronectin receptors. We expect to learn which forms of Fn are most active in promotion of epithelial wound healing and macrophage activation, which may lead to more effective control of these vital processes in humans. (MB)
