PROJECT SUMMARY It is increasingly recognized that oxidative stress is an important feature in pathophysiology of chronic pulmonary diseases, including asthma, COPD and pulmonary fibrosis. Yet, in spite of some successes in animal studies, clinical trials using antioxidants have been largely ineffective in improving lung function in patients with lung disease, and have not yielded new drugs. Despite these negative clinical trials, it has now become well accepted that oxidants are molecules that carry out important biological functions. My laboratory has discovered that protein S-glutathionylation (PSSG), a redox-based modification of reactive cysteines, plays a critical role in airways remodeling and lung fibrosis. We identified that this process is catalyzed by glutathione S transferase P (GSTP), and reversed by the deglutathionylating enzyme, glutaredoxin-1 (Glrx1) induced de-glutathionylation. The intriguing observations around the GSTP-PSSG-Glrx1 redox axis have formed the foundation for a number of research directions that will be pursued herein. We propose to do so in the setting of interstitial fibrosis and fibrotic remodeling associated with allergic airways disease. The conceptual framework for this R35 over the next seven years consists of five separate goals that include: 1) Identification of redox scaffolds and redox-relay circuits harnessed by scaffolding complexes that encompass peroxiredoxin-4 (Prdx4), GSTP and client proteins that are S-glutathionylated via a redox relay, 2) Avenues to combat protein S-glutathionylation (PSSG) in a target-specific manner by focusing on new avenues for inhibition of GSTP, 3) Understanding mechanisms of cellular uptake/secretion of Glrx1, approaches to modify stability of and deliver Glrx1 to specific cellular compartments to enhance its de-glutathionylating function, 4) Address whether altered inflammatory/immune responses contribute to the diminished fibrogenic response upon attenuation of S-glutathionylation, and 5) Elucidate targets for PSSG in epithelial cells from asthmatics and lung tissues from patients with IPF and address whether strategies to attenuate PSSG diminish pro-inflammatory/pro-remodeling responses in epithelial cells from patients with asthma: The project areas identified have the strong potential to advance our knowledge of how biological oxidations, specifically PSSG, are controlled, with the goal to identify strategies to intervene with protein cysteine oxidations in a target- or compartment-specific manner. The anticipated outcomes will be molecules that are therapeutically applicable and overcome the lack of efficacy observed with the use of non- specific generic antioxidants in the treatment of pulmonary diseases. This research program has the potential to be paradigm-shifting as it changes conventional thinking of how oxidants contribute to lung disease (oxidative stress) toward a paradigm wherein oxidants transduce signals via highly scaffolded “electrical circuits”.