The overall objective of this proposal is to study the regulation and function of connective tissue growth factors (CTGF) and elucidate its autocrine/paracrine effects on airway smooth muscle cells (SMC). (CTGF, a novel cysteine-rick peptide that exhibits platelet-derived growth factor (PDGF) like actions, is the most abundant growth factor found in the lung to date. Transforming growth factor beta (TGF-beta) specifically induces the CTGF mRNA in human skin fibroblasts and vascular endothelial cells. I have previously shown that two other growth factors, endothelin (ET) and PDGF stimulate the migration and growth of airway SMC. These airway cells can constitutively express ET-1 mRNA and produce ET-1. In preliminary studies, I have shown that airway SMC also produce ad respond to CTGF. In the present proposal, I hypothesize that growth factors such as CTGF, are involved in the increased contractility, hyperplasia, and hypertrophy of airway SMC that are characteristic features of bronchial asthma. SMC, isolated from ovine trachealis muscle, will be stimulated with TGF-beta and other cytokines and the RNA isolated and subjected to Northern analysis. The effects of recombinant CTGF on airway SMC behavior will be studies using receptor, proliferation, chemotaxis, and contractility assays. Finally, immunohistochemical techniques using polyclonal CTGF antibodies will be used to determine the localization of CTGF in sheep airway and in situ hybridization utilized to identify cells responsible for CTGF synthesis. Thr proposed studies will broaden our understanding of airway smooth muscle regulation by growth factors.
