N-acetyl-cysteine suppresses amniotic fluid and placenta inflammatory cytokine responses to lipopolysaccharide in rats.

OBJECTIVE: Maternal infections may induce placental, amniotic and, potentially, fetal inflammatory responses. As cytokine responses may be mediated by oxidative stress, we determined whether the antioxidant N-acetyl-cysteine (NAC), can attenuate maternally induced amniotic and placental cytokine responses to maternal infection (modeled by lipopolysaccharide [LPS]). STUDY DESIGN: Gestation day 18 pregnant rats were (1) treated with LPS (100 microg/kg, body weight; intraperitoneally) alone; (2) pretreated with NAC (300 mg/kg body weight; intraperitoneally) 30 minutes before LPS; (3) posttreated with NAC 120 minutes after LPS; or (4) treated with NAC 30 minutes before and 120 minutes after LPS. Six hours after LPS administration, maternal serum and amniotic fluid interleukin-6 (IL-6) and IL-10 levels, and placental IL-6 messenger RNA levels were determined. RESULTS: LPS increased maternal serum IL-6 (50 +/- 25 to 3444 +/- 584 pg/mL) and IL-10 (40 +/- 20 to 958 +/- 339 pg/mL) and amniotic fluid IL-6 (59 +/- 25 to 891 +/- 128 pg/mL). Pretreatment and/or posttreatment with NAC attenuated IL-6 in the maternal serum and amniotic fluid and IL-10 in the amniotic fluid. LPS also induced placental IL-6 messenger RNA that was inhibited by treatment with NAC before and after LPS. CONCLUSION: NAC inhibition of inflammatory responses may protect the fetus from potential long-term sequelae.

Maternal LPS induces cytokines in the amniotic fluid and corticotropin releasing hormone in the fetal rat brain.

Perinatal infections are a risk factor for fetal neurological pathologies, including cerebral palsy and schizophrenia. Cytokines that are produced as part of the inflammatory response are proposed to partially mediate the neurological injury. This study investigated the effects of intraperitoneal injections of lipopolysaccharide (LPS) to pregnant rats on the production of cytokines and stress markers in the fetal environment. Gestation day 18 pregnant rats were treated with LPS (100 microg/kg body wt i.p.), and maternal serum, amniotic fluid, placenta, chorioamnion, and fetal brain were harvested at 1, 6, 12, and 24 h posttreatment to assay for LPS-induced changes in cytokine protein (ELISA) and mRNA (real-time RT-PCR) levels. We observed induction of proinflammatory cytokines interleukin (IL)-1 beta, IL-6, and tumor necrosis factor-alpha (TNF-alpha) as well as the anti-inflammatory cytokine IL-10 in the maternal serum within 6 h of LPS exposure. Similarly, proinflammatory cytokines were induced in the amniotic fluid in response to LPS; however, no significant induction of IL-10 was observed in the amniotic fluid. LPS-induced mRNA changes included upregulation of the stress-related peptide corticotropin-releasing factor in the fetal whole brain, TNF-alpha, IL-6, and IL-10 in the chorioamnion, and TNF-alpha, IL-1 beta, and IL-6 in the placenta. These findings suggest that maternal infections may lead to an unbalanced inflammatory reaction in the fetal environment that activates the fetal stress axis.