Resistance of quiescent and proliferating airway epithelial cells to H₂O₂ challenge

¹ Dept of Analytical Biochemistry, University Centre for Pharmacy; and Laboratory for Allergology and Pulmonology, University Medical Centre Groningen
² Laboratory for Allergology and Pulmonology, University Medical Centre Groningen
³ Dept of Analytical Biochemistry, University Centre for Pharmacy
⁴ Groningen University Institute for Drug Exploration, University Medical Centre Groningen, The Netherlands

^* To whom correspondence should be addressed. E-mail: Henk.Kauffman{at}inter.nl.net.

	Abstract

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 (H₂O₂) challenges.

Recovery was monitored after 24h 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 Fluorescent Activated Cell Sorting (FACS), and by determining the intracellular free thiol content.

A549 cells recovered from a 1h challenge with up to 1mM H₂O₂ but could not sustain a more prolonged challenge (6 or 24h) with 0.5 mM or 1.0 mM H₂O₂. 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.

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