219 - Caffeine and/or Ibuprofen Effects on Biomarkers of Alveolarization and Microvascular Maturation in Neonatal Rat Lungs in the Saccular Stage of Development.

Publication Number: 219.4507

Raj Krishna Yadav, SUNY Downstate Health Sciences University, BROOKLYN, NY, United States; Charles L. Cai, SUNY Downstate, Brooklyn, NY, United States; Jacob V V. Aranda, State University of New York Downstate Medical Center College of Medicine, BROOKLYN, NY, United States; Kay Beharry, SUNY Downstate Health Sciences University, Brooklyn, NY, United States; Paris Acquaro, State University of New York Downstate Medical Center College of Medicine, Brooklyn, NY, United States; Matthew Marcelino, Children's Hospital Los Angeles, Los Angeles, CA, United States

Background: At birth, the newborn rat’s lungs are structurally immature and similar to preterm infants in the saccular stage of development who are at risk for oxidative injury. Caffeine citrate (Caff) and Ibuprofen lysine (Ibu) are used for apnea and closure of a symptomatic PDA, respectively. Both have anti-inflammatory and antioxidant properties. Alveolarization and microvascular maturation are major processes regulated by matrix metalloproteinases (MMPs) and vascular endothelial growth factor (VEGF) but affected by oxidative injury.

Objective: To test the hypothesis that early postnatal treatment with Caff and/or Ibu protects the immature lungs in the saccular stage against oxidative injury and preserves biomarkers of alveolarization and microvascular maturation.

Design/Methods: Neonatal rats (n=18/group) were exposed to intermittent hypoxia (IH), hyperoxia (Hx) only (50% O2), or room air (RA), from the first day of life (P0) to P14, during which they received: 1) Caff (20 mg/kg loading IP) on P0; and 5 mg/kg/day on P1-P14; 2) Ibu (10 mg/kg loading IP) on P0; and 5 mg/kg/day on P1 and P2; 3) Caff+Ibu; or 4) placebo saline (Sal) on P0-P14. Lungs were examined at P14 and P21 for histopathology: hypertension, apoptosis; biomarkers of alveolarization and angiogenesis. Data are mean±SEM.

Results: Hx and IH resulted in significant damage in the Sal groups with reductions in secondary crest formation (Hx:16.2±1.2; IH: 12.5±1.5 vs. RA: 22.1±1.8, p< 0.01). Radial alveolar counts were reduced and medial wall thickness (μm) increased in Hx (3.2±0.17 and 0.34±0.02, respectively, p< 0.01) and IH (3.2±0.21 and 0.35±0.02, respectively, p< 0.01) vs. RA (4.3±0.3 and 0.23±0.02). The effects of Hx and IH were improved with all treatments, although alveolar hemorrhage was noted with Ibu. Apoptosis intensity was increased with Hx (1550.2±192.5, p< 0.01) and IH (2898.3±181.5, p< 0.01) vs. Sal (769.7±100.9), and only Ibu effectively reduced it (Hx: 624.3±44.7; IH: 515.0±74.2, p< 0.01). MMP-2 and MMP-8 were decreased in Hx and IH, but MMP-9 was elevated in the Sal group. All treatments reversed these biomarker effects. Angiogenesis biomarkers were decreased with Sal in Hx and increased in IH, and only Ibu reversed those effects.

Conclusion(s): Immature lungs in the saccular stage are highly vulnerable to oxidative damage. Improvements in lung architecture and pulmonary outcomes with Caff may be due to its effects on biomarkers of alveolarization and microvascular maturation. While Ibu improved apoptosis and angiogenesis biomarkers, hemorrhage is a cause for concern.