Amelioration of meconium-induced acute lung injury by parecoxib in a rabbit model.

Cyclooxygenase-2 (COX-2) plays important roles in various inflammatory conditions and is significantly increased in meconium-induced lung injury. We investigated the effects of parecoxib on meconium-induced acute lung injury (ALI) in rabbits. Twenty-four rabbits were randomized into sham, control, and parecoxib groups. Rabbits in the control and parecoxib groups underwent tracheal instillation of meconium, followed by intravenous injection of saline or parecoxib and 4 h of ventilation. The airway pressure, dynamic compliance, and ratio of partial pressure of oxygen in arterial blood to fraction of inspired oxygen (PaO2/FiO2 ratio) were recorded at baseline (T0) and 4 h after instillation (T1-T4). The lung tissue wet-to-dry weight ratio; neutrophil percentage; and total protein, tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-8, prostaglandin E2, and malondialdehyde levels in bronchoalveolar lavage fluid (BALF) were evaluated. The myeloperoxidase activity, COX-2 expression, and degree of histopathologic injury in lung tissue were also analyzed. The airway pressure, compliance, and PaO2/FiO2 ratio were significantly improved by parecoxib after meconium instillation. The lung wet-to-dry weight ratio, total protein level, and neutrophil percentage in BALF were lowest in the parecoxib group. The TNF-α, IL-1β, IL-8, prostaglandin E2, and malondialdehyde levels in the BALF were lowest in the parecoxib group. The COX-2 expression and myeloperoxidase activity in lung tissue were significantly reduced by parecoxib. The degree of lung injury was also reduced. In conclusions: Parecoxib effectively ameliorates respiratory function and attenuates meconium-induced ALI. These effects are correlated with prostaglandin E2 and COX-2 inhibition.