Exposure to sulfur (SM) or nitrogen (NM) mustard can cause severe acute and chronic, potentially lethal,
pulmonary injury. NM and SM are chemical warfare agents that have been used repeatedly since the early 20th
century. To date no clinical antidote is available against the chronic sequels of exposure to SM or NM and to the
most dangerous, irreversible and potentially lethal of these effects, namely pulmonary fibrosis. Exposure to SM
or NM triggers oxidative stress, a macrophage-rich inflammatory response and stimulation of pro-fibrotic
pathways that lead to fibroblast activation, extracellular matrix deposition and pulmonary fibrosis. Recently, it
was reported that inhibitors of the pro-inflammatory heat shock protein 90 (HSP90) prevent bleomycin-induced
pulmonary fibrosis. We therefore hypothesized that HSP90 inhibitors, already in clinical trials as anti-cancer
agents, may prove useful as countermeasures against mustard-induced chronic lung injury and pulmonary
fibrosis. Our preliminary studies demonstrate that a single intra-tracheal instillation of the NM, melphalan,
produces biochemically and histologically evident pulmonary fibrosis characterized by peribronchial and
parenchymal collagen deposition, upregulation of HSP90 and aSMA and consequent airway dysfunction at 30
days after NM instillation. Post-treatment (beginning 24 hours after NM administration) with the clinically used
HSP90 inhibitor, AUY-922, effectively blocks the development of collagen deposition, pulmonary fibrosis and
aSMA upregulation. In this R21 application, we propose to expand on our initial findings in two areas: establish
the murine model of NM-induced chronic lung injury and pulmonary fibrosis and provide proof of concept for the
antidotal properties of the HSP90 inhibitor, AUY-922. We will achieve this through the following two specific
aims: 1) we will establish the mouse model of NM-induced chronic lung injury and pulmonary fibrosis, with
specific quantifiable and reproducible biomarkers, demonstrate dose-response relationships and identify key
pathologic signaling pathways; 2) we will investigate the effectiveness of the HSP90 inhibitor, AUY-922, in
blocking NM-induced pulmonary fibrosis, lung dysfunction and the upregulation of key pro-fibrotic pathways, in
mice. Results from these studies will provide proof of concept for the further development of HSP90 inhibitors
as antidotes against mustard-induced lung fibrosis and chronic lung dysfunction.