Pulmonary granulomatous diseases possess a common set of pathologic events which appear to be due, in part, to the recruitment and activation of leukocytes. Although the initiating insult may vary, as in the eitiology of sarcoidosis, tuberculosis, or beryllosis, the subsequent immune response, characterized by infiltrating mononuclear cells, is often similar. While the exact mechanism(s) by which leukocytes are elicited to the granuloma are not known, it is likely that the local production of specific chemotactic factors is critically important. This application will focus on the role of a novel chemotactic cytokine, Monocyte Chemoattractant Protein-1 (MCP), in the initiation and maintenance of granulomatous inflammation. The working hypothesis of this application is that the expression of MCP during the initiation and maintenance of pulmonary granulomatous inflammation is one of the major mechanisms for the recruitment of blood born monocytes to the developing lesion. Accumulating evidence suggests that the expression of MCP during the development of an inflammatory lesion is influenced by a cytokine network, involving proximal mediators which can induce MCP expression by resident stromal and parenchymal cells. Thus, non-immune cells may play a key role in the initiation of the local immune response by synthesizing specific chemotactic factors. The following questions will be addressed: What is the time course in the expression of MCP during the development of a pulmonary granulomatous response? What is the contribution of MCP to the initiation and maintenance of the granulomatous lesion? What are the cytokine networks which can either positively or negatively influence the expression of MCP by immune and non-immune cells? What are the molecular mechanisms which regulate the expression of MCP? Two well established models will be utilized. Highly active, T cell /macrophage mediated pulmonary granulomas will be established by embolizing Schistosoma mansoni eggs to the lungs of mice, resulting in a characteristic Delayed-Type Hypersensitivity (DTH) response. Foreign body-type lung granulomas will be induced by the embolization of sized Sephadex beads. In addition, lung granulomas will be studied in animals receiving Sephadex beads impregnated with specific cytokines to induce MCP production. The role of MCP in the initiation and maintenance of granulomatous inflammation will be studied at the whole organ, cellular, and molecular levels. Techniques used include: bioassays for monocyte chemotaxis, ELISAs for MCP quantitation, immunohistochemistry for antigen localization, and Northern blot, mRNA stability, in situ hybridization, and nuclear transcriptional analysis for assessing the expression and regulation of MCP mRNA. Studies contained in this proposal will provide novel information regarding the recruitment phase of granulomatous inflammation, will determine cellular and molecular mechanisms of MCP expression and regulation (using both animal and cell culture models), and will address a phase of granulomatous inflammation which may be amenable to therapeutic intervention.
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