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Hyperoxia Exacerbates Postnatal Inflammation-Induced Lung Injury in Neonatal BRP-39 Null Mutant Mice Promoting the M1 Macrophage Phenotype

2013; Hindawi Publishing Corporation; Volume: 2013; Linguagem: Inglês

10.1155/2013/457189

1466-1861

Mansoor Ali Syed, Vineet Bhandari,

Respiratory Support and Mechanisms

Rationale . Hyperoxia exposure to developing lungs—critical in the pathogenesis of bronchopulmonary dysplasia—may augment lung inflammation by inhibiting anti-inflammatory mediators in alveolar macrophages. Objective . We sought to determine the O 2 -induced effects on the polarization of macrophages and the role of anti-inflammatory BRP-39 in macrophage phenotype and neonatal lung injury. Methods . We used RAW264.7, peritoneal, and bone marrow derived macrophages for polarization (M1/M2) studies. For in vivo studies, wild-type (WT) and BRP-39 −/− mice received continuous exposure to 21% O 2 (control mice) or 100% O 2 from postnatal (PN) 1 to PN7 days, along with intranasal lipopolysaccharide (LPS) administered on alternate days (PN2, -4, and -6). Lung histology, bronchoalveolar lavage (BAL) cell counts, BAL protein, and cytokines measurements were performed. Measurements and Main Results . Hyperoxia differentially contributed to macrophage polarization by enhancing LPS induced M1 and inhibiting interleukin-4 induced M2 phenotype. BRP-39 absence led to further enhancement of the hyperoxia and LPS induced M1 phenotype. In addition, BRP-39 −/− mice were significantly more sensitive to LPS plus hyperoxia induced lung injury and mortality compared to WT mice. Conclusions . These findings collectively indicate that BRP-39 is involved in repressing the M1 proinflammatory phenotype in hyperoxia, thereby deactivating inflammatory responses in macrophages and preventing neonatal lung injury.