Background: Chorioamnionitis induces fetal inflammatory response syndrome including a local inflammatory response in the fetal lungs, resulting in elevated levels of pro-inflammatory cytokines accompanied by increased oxidative stress from influx of neutrophils. Targeting inflammation and oxidative stress in the fetal lungs is therefore essential to improve respiratory outcomes in preterm infants. Creatine is an organic acid that has direct anti-oxidant effects. An increased tissue creatine level is protective against pro-inflammatory insults from lipopolysaccharide (LPS), including reduction in pro-inflammatory cytokine release. Creatine is thus an adjuvant therapy to counter antenatal inflammation to improve respiratory outcomes in preterm infants. We propose a PhD plan that will investigate the effects of fetal creatine loading to reduce inflammation and oxidative stress in the fetal lungs arising from a pro-inflammatory stimulus in utero. We hypothesise that fetal lambs exposed to LPS will show lung maturation accompanied by inflammation and oxidative stress. We further hypothesise that fetal creatine loading prior to LPS exposure will reduce inflammation and oxidative damage in-utero without adverse effects on lung maturation.
Methods: Date mated pregnant ewes underwent hysterotomy for catheterisation of the fetal axillary vein at 90 d gestation. After 3 days of recovery, creatine (6mg/kg/h, creatine monohydrate) or saline was given for 17 days as continuous intravenous infusion. Intra-amniotic LPS (1mg) or saline was administered 7 days prior to delivery (111 d gestation) to initiate chorioamnionitis. Initially, each treatment group will be phenotyped based on oxidative stress (protein carbonyl measurement) and inflammatory response (immunohistochemistry). Each hypothesised mechanisms of creatine will then be investigated in-vitro using cell culture, followed by validation with tissue samples using targeted PCR/RNAseq analysis.
Significance: Establishing the mechanisms and efficacy of fetal creatine loading in protecting the fetal lungs from adverse effects of chorioamnionitis may highlight potential benefits of this therapy and inform development of clinical trials.