In patients with chronic obstructive pulmonary disease (COPD), an imbalance between oxidants and antioxidants is acknowledged to result in disease development and progression. Cigarette smoke (CS) is known to deplete total glutathione (GSH + GSSG) in the airways. We hypothesized that components in the gaseous phase of CS may irreversibly react with GSH to form GSH derivatives that cannot be reduced (GSX), thereby causing this depletion. To understand this phenomenon, we investigated the effect of CS on GSH metabolism and identified the actual GSX compounds. CS and H(2)O(2) (control) deplete reduced GSH in solution [Delta = -54.1 +/- 1.7 microM (P < 0.01) and -39.8 +/- 0.9 microM (P < 0.01), respectively]. However, a significant decrease of GSH + GSSG was observed after CS (Delta = -75.1 +/- 7.6 microM, P < 0.01), but not after H(2)O(2). Exposure of A549 cells and primary bronchial epithelial cells to CS decreased free sulfhydryl (-SH) groups (Delta = -64.2 +/- 14.6 microM/mg protein, P < 0.05) and irreversibly modified GSH + GSSG (Delta = -17.7 +/- 1.9 microM, P < 0.01) compared with nonexposed cells or H(2)O(2) control. Mass spectrometry (MS) showed that GSH was modified to glutathione-aldehyde derivatives. Further MS identification showed that GSH was bound to acrolein and crotonaldehyde and another, yet to be identified, structure. Our data show that CS does not oxidize GSH to GSSG but, rather, reacts to nonreducible glutathione-aldehyde derivatives, thereby depleting the total available GSH pool.
Alveolar epithelial cell injury and recovery are important in the pathogenesis of oxidant-induced lung damage. The alveolar cell line A549 was used to study responses of proliferating and quiescent cells in culture to time-and dose-dependent hydrogen peroxide (H 2 O 2 ) challenges.Recovery was monitored after 24 h of incubation in fresh medium with 10% serum. The adherent cells were counted and the resistance and recovery of the attached cells was assessed by appearance, by measuring the number of viable, apoptotic and necrotic cells using fluorescentactivated cell sorting, and by determining the intracellular free thiol content.A549 cells recovered from a 1-h challenge with up to 1 mM H 2 O 2 but could not sustain a more prolonged challenge (6 or 24 h) with 0.5 mM or 1.0 mM H 2 O 2 . These more severe conditions resulted in: loss of cells by detachment from the plate surface; reduced numbers of viable cells primarily due to necrosis; and a strong reduction of the intracellular free thiol content.Quiescent cells proved to be more sensitive to oxidative stress than proliferating cells. Intracellular free thiol levels apparently play a decisive role in cell survival, preferentially protecting proliferating cells.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.