Intrapulmonary application of a 5-lipoxygenase inhibitor using surfactant as a carrier reduces lung edema in a piglet model of airway lavage

Leukotriene-generated effects on microvascular integrity and polymorphonuclear leukocytes (PMNL) play a key role in the inflammatory process of the alveolar-capillary unit in neonatal acute respiratory distress syndrome. We asked if intrapulmonary application of MK886, a 5-lipoxygenase inhibitor, and the use of a porcine surfactant preparation (Curosurf (TM)) as a carrier substance would improve lung function in a neonatal piglet model of airway lavage. Anesthetized, mechanically ventilated newborn piglets (n=19) underwent repeated airway lavage to induce acute lung injury. Piglets then received either surfactant alone (S, n=6), or MK886 admixed with surfactant (S+MK, n=7), or an air-bolus injection as control (C, n=6). Measurements of gas exchange, lung function, extravascular lung water (EVLW), cell counts, and leukotriene B-4 (LTB4) concentrations in bronchoalveolar lavage fluid (BAL) were performed during 6 hr of mechanical ventilation. Arterial oxygen partial pressure (PaO2) (S, 13.8 +/- 4.2 kPa, vs. S+MK, 20 +/- 6.6; P < 0.05), functional residual capacity (S,15.1 +/- 6.8 ml/kg, vs. S + MK, 18.8 +/- 3.7 ml/kg; P < 0.05), and EVLW (S, 29 +/- 14 ml/kg, vs. S + MK 24 +/- 4 ml/kg; P < 0.05) were significantly improved in the MK886 group. This clinical effect was linked with a decrease in LTB4 concentration in BAL (S, 3.5 (1.9-5.4) pg/ml, vs. S + MK, 1.6 (0.7-4.7) pg/ml; P < 0.05) and an increase in IL-8 (S, 2,103 (8524,243) pg/ml, vs. S + MK, 3,815 (940-26,187) pg/ml; P < 0.05). PMNL counts in BAL were reduced (S, 570 +/- 42 cells/ml, vs. 275 +/- 35 cells/ml; P < 0.05). In conclusion, intrapulmonary application of the 5-lipoxygenase inhibitor MK886 with surfactant as a carrier improves lung function by decreasing EVLW as the main response to LTB4 reduction.