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Chorioamnionitis is a common antecedent of preterm birth and induces inflammation and oxidative stress in the fetal lungs. Reducing inflammation and oxidative stress in the fetal lungs may improve respiratory outcomes in preterm infants. Creatine is an organic acid with known anti-inflammatory and antioxidant properties. The objective of the study was to evaluate the efficacy of direct fetal creatine supplementation to reduce inflammation and oxidative stress in fetal lungs arising from an in utero proinflammatory stimulus. Fetal lambs ( n = 51) were instrumented at 90 days gestation to receive a continuous infusion of creatine monohydrate (6 mg·kg -1 ·h -1 ) or saline for 17 days. Maternal chorioamnionitis was induced with intra-amniotic lipopolysaccharide (LPS; 1 mg, O55:H6) or saline 7 days before delivery at 110 days gestation. Tissue creatine content was assessed with capillary electrophoresis, and inflammatory markers were analyzed with Luminex Magpix and immunohistochemistry. Oxidative stress was measured as the level of protein thiol oxidation. The effects of LPS and creatine were analyzed using a two-way ANOVA. Fetal creatine supplementation increased lung creatine content by 149% ( P Cr  < 0.0001) and had no adverse effects on lung morphology. LPS-exposed groups showed increased levels of interleukin-8 in the bronchoalveolar lavage ( P LPS  < 0.0001) and increased levels of CD45 + leukocytes ( P LPS  < 0.0001) and MPO + ( P LPS  < 0.0001) cells in the lung parenchyma. Creatine supplementation significantly reduced the levels of CD45 + ( P Cr  = 0.045) and MPO + cells ( P Cr  = 0.012) in the lungs and reduced thiol oxidation in plasma ( P Cr  < 0.01) and lung tissue ( P Cr  = 0.02). In conclusion, fetal creatine supplementation reduced markers of inflammation and oxidative stress in the fetal lungs arising from chorioamnionitis. NEW & NOTEWORTHY We evaluated the effect of antenatal creatine supplementation to reduce pulmonary inflammation and oxidative stress in the fetal lamb lungs arising from lipopolysaccharide (LPS)-induced chorioamnionitis. Fetal creatine supplementation increased lung creatine content and had no adverse effects on systemic fetal physiology and overall lung architecture. Importantly, fetuses that received creatine had significantly lower levels of inflammation and oxidative stress in the lungs, suggesting an anti-inflammatory and antioxidant benefit of creatine.

Mechanical ventilation from birth with normal tidal volumes (V T ) causes lung injury and systemic responses in preterm sheep. The addition of budesonide to surfactant therapy decreases these injury markers. Budesonide and surfactant will decrease the injury from injurious V T ventilation in preterm sheep. Lambs at 126 ± 1 day gestational age were ventilated from birth with either: 1) Normal V T [surfactant 200 mg/kg before ventilation, positive end expiratory pressure (PEEP) 5 cmH 2 O, V T 8 mL/kg] or 2) Injury V T (high pressure, 100% oxygen, no PEEP) for 15 min, then further randomized to surfactant + saline or surfactant + 0.25 mg/kg budesonide with Normal V T for 6 h. Lung function and lung, liver, and brain tissues were evaluated for indicators of injury. Injury V T + saline caused significant injury and systemic responses, and Injury V T + budesonide improved lung physiology. Budesonide decreased lung inflammation and decreased pro-inflammatory cytokine mRNA in the lung, liver, and brain to levels similar to Normal V T + saline. Budesonide was present in plasma within 15 min of treatment in both ventilation groups, and less than 5% of the budesonide remained in the lung at 6 h. mRNA sequencing of liver and periventricular white matter demonstrated multiple pathways altered by both Injury V T and budesonide and the combination exposure. In lambs receiving Injury V T , the addition of budesonide to surfactant improved lung physiology and decreased pro-inflammatory cytokine responses in the lung, liver, and brain to levels similar to lambs receiving Normal V T .

Mechanical ventilation with normal tidal volumes (V T ) causes lung and systemic inflammation in preterm sheep. Mechanical ventilation is associated with bronchopulmonary dysplasia (BPD) in preterm infants, and the addition of budesonide to surfactant decreases BPD in clinical trials. Budesonide with surfactant will decrease the lung injury from mechanical ventilation for 24 h in preterm sheep. Lambs at 126 ± 1 day gestational age were delivered and randomized to either: 1 ) surfactant (200 mg/kg) or 2 ) surfactant mixed with budesonide (0.25 mg/kg) before mechanical ventilation with V T of 7-8 ml/kg for 2, 6, or 24 h ( n = 6 or 7/group). Lung physiology and budesonide levels in the plasma and the lung were measured. Lung tissue, bronchoalveolar lavage fluid (BALF), liver, and brain tissues were evaluated for indicators of injury. High initial budesonide plasma levels of 170 ng/ml decreased to 3 ng/ml at 24 h. Lung tissue budesonide levels were less than 1% of initial dose by 24 h. Although physiological variables were generally similar, budesonide-exposed lambs required lower mean airway pressures, had higher hyperoxia responses, and had more stable blood pressures. Budesonide decreased proinflammatory mRNA in the lung, liver, and brain. Budesonide also decreased total protein and proinflammatory cytokines in BALF, and decreased inducible nitric oxide synthase activation at 24 h. In ventilated preterm lambs, most of the budesonide left the lung within 24 h. The addition of budesonide to surfactant improved physiology, decreased markers of lung injury, and decreased systemic responses in liver and brain.

Experimental studies that are relevant to human pregnancy rely on the selection of appropriate animal models as an important element in experimental design. Consideration of the strengths and weaknesses of any animal model of human disease is fundamental to effective and meaningful translation of preclinical research. Studies in sheep have made significant contributions to our understanding of the normal and abnormal development of the fetus. As a model of human pregnancy, studies in sheep have enabled scientists and clinicians to answer questions about the etiology and treatment of poor maternal, placental, and fetal health and to provide an evidence base for translation of interventions to the clinic. The aim of this review is to highlight the advances in perinatal human medicine that have been achieved following translation of research using the pregnant sheep and fetus.

Mechanical ventilation causes lung injury and systemic inflammatory responses in preterm sheep and is associated with bronchopulmonary dysplasia (BPD) in preterm infants. Budesonide added to surfactant decreased BPD by 20% in infants. We wanted to determine the effects of budesonide and surfactant on injury from high tidal volume (V T ) ventilation in preterm lambs. Ewes at 125 ± 1 days gestational age had fetal surgery to expose fetal head and chest with placental circulation intact. Lambs were randomized to 1) mechanical ventilation with escalating V T to target 15 ml/kg by 15 min or 2) continuous positive airway pressure (CPAP) of 5 cmH 2 O. After the 15-min intervention, lambs were given surfactant 100 mg/kg with saline, budesonide 0.25 mg/kg, or budesonide 1 mg/kg. The fetuses were returned to the uterus for 24 h and then delivered and ventilated for 30 min to assess lung function. Budesonide levels were low in lung and plasma. CPAP groups had improved oxygenation, ventilation, and decreased injury markers compared with fetal V T lambs. Budesonide improved ventilation in CPAP lambs. Budesonide decreased lung weights and lung liquid and increased lung compliance and surfactant protein mRNA. Budesonide decreased proinflammatory and acute-phase responses in lung. Airway thickness increased in animals not receiving budesonide. Systemically, budesonide decreased monocyte chemoattractant protein-1 mRNA and preserved glycogen in liver. Results with 0.25 and 1 mg/kg budesonide were similar. We concluded that budesonide with surfactant matured the preterm lung and decreased the liver responses but did not improve lung function after high V T injury in fetal sheep.