N-Acetyl-Cysteine Inhibits Phospholipid Metabolism, Proinflammatory Cytokine Release, Protease Activity, and Nuclear Factor- B Deoxyribonucleic Acid-Binding Activity in Human Fetal Membranes in Vitro

The production of reactive oxygen species (ROS), prostaglandins (PGs), proinflammatory cytokines, and proteases has been implicated in the pathogenesis of term and preterm labor. The nuclear factorB (NFB) transcription pathway is activated by ROS and is a key regulator of PGs, proinflammatory cytokine release, and protease activity. N-Acetylcysteine (NAC) is an antioxidant that through its ability to scavenger ROS suppresses NFB DNA-binding activity and resultant gene expression. The aim of this study was to elucidate the effect of NAC on NFB DNA-binding activity, phospholipid metabolism, cytokine release, and protease activity from human fetal membranes. Human amnion and choriodecidua (n 9 separate placentas) were treated with 0 (control), 5, 10, or 15 mM NAC in the presence of 10 g/ml lipopolysaccharide. After 6-h incubation, the tissues were collected, NFB DNA binding activity was assessed by gel shift binding assays, and matrix metalloproteinase-9 and urokinase-type plasminogen activator activity were determined by zymography. The incubation medium was collected and assayed for type II phospholipase A2 tissue content, IL-6, IL-8, TNF , and 8-isoprostane release by ELISA. The release of PGF2 was measured by RIA. Treatment of fetal membranes with NAC significantly suppressed lipopolysaccharide-stimulated type II phospholipase A2 release and content; PGF2 , IL-6, IL-8, TNF , and 8-isoprostane release; and matrix metalloproteinase-9 and urokinase-type plasminogen activator enzyme activity and suppressed NFB DNA-binding activity (by ANOVA, P < 0.05). The data presented in this study demonstrate that NAC inhibits an NFB-activated pathway and subsequent phospholipid metabolism, proinflammatory cytokine release, and protease activity in human fetal membranes. (J Clin Endocrinol Metab 88: 1723–1729, 2003)