This proposal is designed to continue our work on the mechanisms through which selected peptide growth factors mediate interstitial pulmonary fibrosis (IPF). We showed that mice with both receptors for TNF-alpha knocked out exhibited reduced TGF-beta1 expression and failed to develop IPF consequent to exposure to asbestos, bleomycin, and silica. New data from our laboratory show that the disease process can be reestablished in these mice by treating the animals with an adenovirus vector (AdV) transducing the expression of active TGF-beta1. In addition, the 129 inbred mouse strain similarly exhibits reduced TGF-beta1 expression and significantly reduced disease consequent to asbestos exposure and treatment with the adenovector transducing TGF-beta1. TGF-beta1 is a key molecule mediating interstitial pulmonary fibrosis. While this has been made clear in many experiments, the role that TGF-beta1 plays in IPF and the mechanisms through which TGF-beta1 mediates its well-known effects remain undefined. Thus, in this competitive renewal of our work, we put forth the Hypothesis: that 1) TGF- beta1 induced by TNF-alpha and expressed by alveolar epithelial and mesenchymal cells is activated from the latent form by reactive oxygen species; that 2) the biologically active TGF-beta1 limits epithelial proliferation in vivo; that 3) TGF-beta1 induces the signal transduction molecules MAPK and IkappaB leading to AP-1 and NF-kappaB activation in the TNF-alphaRKO mice thus inducing inflammation and disease in these fibrogenic-resistant animals; and that 4) an antisense cRNA to TGF-beta1 will block the disease process, provide a """"""""proof of principle"""""""" and a potential therapeutic approach for IPF. To test this hypothesis, we propose the following Aims:
Aim 1) To confirm our preliminary observations showing that TNF-alphaRKO mice transducing TGF-beta1 expression from the AdV exhibit more severe and prolonged interstitial fibrogenesis than normal background mice, and that proliferation of the bronchiolar-alveolar epithelium is inhibited by TGF-beta1 in these mice and in the 129 strain.
Aim 2) To determine whether or not reactive oxygen species activate TGF-beta1 from the latent form in cell culture experiments and in vivo in mice treated with the AdV- TGF-beta1 construct and exposed to asbestos.
Aim 3) To determine, in primary lung fibroblasts from TNF-alphaRKO mice, TGF-beta1 -induced MAPK and IkappaB signal transduction pathways leading to AP1 and NF-kappaB activation, thus explaining the inflammation and disease observed in these fibrogenic-resistant animals.
Aim 4) To develop anti-sense cRNAs, against TGF-beta1 and TNF-alpha that can be used in an adenovector system as therapeutic agents to block the development of IPF in our animal models.
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