Role of Heat Shock Protein 70 in Lung Fibrosis

University Of Pittsburgh At Pittsburgh, Pittsburgh PA

Investigators

Abstract

DESCRIPTION (provided by applicant): IPF is a chronic, progressive disease characterized by extensive lung fibrosis. The pathogenesis of IPF is incompletely described, but includes activation of fibroblasts by TGFb-1, and deposition of collagen-matrix which creates parenchymal scarring. HSP-70, alternatively, is induced in eukaryotic cells in response to a variety of stresses and provides cytoprotection via anti-inflammatory and antiapoptotic effects. Recent experiments in our lab have identified HSP-70 as a potential regulator of fibroblast activity. Preliminary results show that, when stimulated with TGFb-1, MRC human fetal lung fibroblasts show inducible expression of HSP-70 in a time-dependent fashion. Also, there is increased in vitro expression of alpha-Smooth Muscle Actin, a marker of fibroblast activation, when TGFb-1 is given to lung fibroblasts in knock-out strains of mice lacking HSF-1, the transcription factor for HSP-70. Using HSF-1 KO mice and wild-type littermate controls, we will further describe the mechanisms of HSF-1 induction and HSP-70 expression in response to TGFb-1 stimulation. Using Western- and Northern-blot, we will analyze a variety of secondary signaling pathways, such as MAPK, JNK, CAMKII, and the generation of ROS. We hypothesize these factors to be involved in TGFb-1-induced activation of HSF-1, its binding to the heat shock promoter, and subsequent upregulation of HSP-70. We will investigate mechanisms of HSP-70 cytoprotection, through evaluating the effects of over-expressing HSP-70. This will be done via gene-vector transformation of HSP-70 into the lungs of HSF-1 KO mice, and observing the effects of HSP-70 upregulation on bleomycin-induced lung injury. Immunohistochemistry and confocal laser microscopy will then be used to evaluate changes in lung histology and the expression of fibroblastic markers of activation.