Intracellular glutathione in stretch‐induced cytokine release from alveolar type‐2 like cells

Abstract

Objective: Ventilator‐induced lung injury (VILI) is characterized by release of inflammatory cytokines, but the mechanisms are not well understood. We hypothesized that stretch‐induced cytokine production is dependent on oxidant release and is regulated by intracellular glutathione (GSH) inhibition of nuclear factor κB (NF‐κB) and activator protein‐1 (AP‐1) binding. Methodology: Type 2‐like alveolar epithelial cells (A549) were exposed to cyclic stretch at 15% strain for 4 h at 20 cycles/min with or without N‐acetylcysteine (NAC) or glutathione monoethylester (GSH‐e) to increase intracellular GSH, or buthionine sulfoximine (BSO), to deplete intracellular GSH. Results: Cyclic stretch initially caused a decline in intracellular GSH and a rise in the levels of isoprostane, a marker of oxidant injury. This was followed by a significant increase in intracellular GSH and a decrease in isoprostane. Stretch‐induced IL‐8 and IL‐6 production were significantly inhibited when intracellular GSH was further increased by NAC or GSH‐e ( P < 0.0001). Stretch‐induced IL‐8 and IL‐6 production were augmented when intracellular GSH was depleted by BSO ( P < 0.0001). NAC blocked stretch‐induced NF‐κB and AP‐1 binding and inhibited IL‐8 mRNA expression. Conclusions: We conclude that oxidant release may play a role in lung cell stretch‐induced cytokine release, and antioxidants, which increase intracellular GSH, may protect lung cells against stretch‐induced injury.