Cyclooxygenase-2 in newborn hyperoxic lung injury

Area of Science:

• Neonatal physiology
• Pulmonary medicine
• Inflammation research

Background:

• Bronchopulmonary dysplasia (BPD) is a chronic lung disease in preterm infants, often caused by supraphysiological oxygen concentrations and mechanical ventilation.
• Hyperoxia exposure in newborn mice mimics BPD, leading to inflammation and impaired alveolarization.
• Pulmonary cyclooxygenase-2 (COX-2) expression is elevated in hyperoxia-exposed newborn mice.

Purpose of the Study:

• To investigate the role of COX-2 in hyperoxia-induced lung injury in newborn mice.
• To test the hypothesis that inhibiting COX-2 activity would reduce inflammation and improve alveolarization.

Main Methods:

• Newborn mice were treated with vehicle, aspirin, or celecoxib (COX-2 inhibitors) or used as wild-type, heterozygous, or homozygous COX-2 knockout models.
• Mice were exposed to room air or 85% oxygen for 14 days.
• Inflammatory markers, including monocyte chemoattractant protein-1 (MCP-1) and macrophage counts, were assessed in bronchoalveolar lavage fluid and lung tissue.

Main Results:

• Aspirin and COX-2 knockout mice showed reduced MCP-1 levels in bronchoalveolar lavage fluid.
• Aspirin and celecoxib treatments decreased macrophage infiltration and attenuated hyperoxia-induced COX activity.
• Despite reduced inflammation, COX-2 inhibition did not prevent hyperoxia-induced lung developmental deficits.

Conclusions:

• Increased COX-2 activity contributes to inflammatory responses, such as macrophage chemotaxis, during hyperoxia exposure.
• Modulating COX-2 activity may be a potential therapeutic strategy to mitigate hyperoxia-induced inflammation in preterm infants at risk for BPD.
• COX-2 inhibition alone does not fully prevent the lung structural damage associated with hyperoxia.