Oral Presentation ESA-SRB-ANZBMS 2024 in conjunction with ENSA

Intra-amniotic antenatal ciclesonide matures the preterm sheep lung (#95)

Kathryn L Gatford 1 2 , Stacey L Holman 3 , Mitchell C Lock 3 , Jack RT Darby 4 , Michael D Wiese 5 , Ashley S Meakin 6 , Vicki L Clifton 7 , Andrew Tai 1 8 , Megan J. Wallace 9 10 , Michael J. Stark 11 12 , Janna L Morrison 3
  1. Robinson Research Institute, The University of Adelaide, Adelaide, SA(AUS), Australia
  2. School of Biomedicine, The University of Adelaide, Adelaide, SA(AUS), Australia
  3. Early Origins of Adult Health Research Group, University of South Australia, Adelaide, SA(AUS), Australia
  4. Early Origins of Adult Health Research Group, University of South Australia, Adelaide, SA(AUS), Australia
  5. Centre for Pharmaceutical Innovation, University of South Australia, Adelaide, SA(AUS), Australia
  6. Early Origins of Adult Health Research Group, University of South Australia, Adelaide, SA(AUS), Australia
  7. Mater Medical Research Institute, University of Queensland, Brisbane, QLD
  8. Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
  9. Hudson Institute of Medical Research, Melbourne, VIC
  10. Department of Obstetrics & Gynaecology, Monash University, Clayton, VIC, Australia
  11. Robinson Research Institute, University of Adelaide, Adelaide, SA, Australia
  12. Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia

Antenatal corticosteroids (ACS) stimulate lung maturation, reducing risks of respiratory diseases and death for preterm babies. However, ACS act in all fetal tissues, with impacts on brain and neurodevelopment of increasing concern. The aim of this study was to identify a dose and route of administration or antenatal ciclesonide, a glucocorticoid prodrug with tissue-specific activation, that stimulates lung maturation in preterm sheep. Pregnant ewes were randomised to antenatal treatment with saline (CON), betamethasone (BETA, standard clinical care, 11.4 mg/dose) or maternal ciclesonide (MAT-CIC, 11.2 mg/dose), given i.m. 48 and 24 h before delivery, or ciclesonide (1 or 0.5 mg/kg estimated fetal weight 48 h before delivery, 1 IA-CIC and 0.5 IA-CIC respectively, delivered intra-amniotically to avoid placental activation). Lambs (9-12/group) were delivered preterm by C-section at 130 gestational days (term ~150d), ventilated for 60 minutes (target volume 7 ml/kg, ETCO2 45-50 mmHg), then humanely killed for tissue collection. Gene expression of surfactant protein B was higher in newborn lungs from lambs exposed to BETA (P=0.001) or 1 IA-CIC (P=0.013), but not MAT-CIC or 0.5 IA-CIC, compared to CON. Similarly, the density of type II epithelial cells was higher in newborn lungs from lambs exposed to BETA or 1 IA-CIC (each P<0.001), but not MAT-CIC or 0.5 IA-CIC, compared to CON. Ventilation outcomes were highly variable – similar proportions of lambs in each group required supplemental oxygen after 60 minutes of ventilation (CON: 70%, BETA: 50%, MAT-CIC: 60%, 0.5 IA-CIC: 78%, 1 IA-CIC: 40%). Our data to date demonstrate that 1 mg/kg intra-amniotic ciclesonide has similar efficacy as current antenatal betamethasone treatments in maturing the lung of preterm lambs. Maternally-delivered ciclesonide was less effective than BETA, demonstrating non dose-equivalence. Planned assessment of brain and long-term outcomes are critical to establish safety as well as efficacy of this intervention.