American journal of physiology. Lung cellular and molecular physiology
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Am. J. Physiol. Lung Cell Mol. Physiol. · Dec 2010
Inflammation in fetal sheep from intra-amniotic injection of Ureaplasma parvum.
Bronchopulmonary dysplasia is associated with chorioamnionitis and fetal lung inflammation. Ureaplasma species are the bacteria most frequently isolated from chorioamnionitis. Very chronic ureaplasma colonization of amniotic fluid causes low-grade lung inflammation and functional lung maturation in fetal sheep. ⋯ CD3-positive cells in the posterior mediastinal lymph node increased in ureaplasma-exposed animals at 3, 7, and 14 days (P = 0.002). Focal elastin depositions decreased in alveolar septa at 14 days (P = 0.002), whereas α-SMA increased in arteries and bronchioli. U. parvum induced a mild acute inflammatory response and changed elastin and α-SMA deposition in the lung, which may affect lung structure and subsequent development.
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Am. J. Physiol. Lung Cell Mol. Physiol. · Dec 2010
MicroRNA-21 plays a role in hypoxia-mediated pulmonary artery smooth muscle cell proliferation and migration.
Hypoxia stimulates pulmonary artery smooth muscle cell (PASMC) proliferation. Recent studies have implicated an important role for microRNAs (miRNAs) in hypoxia-mediated responses in various cellular processes, including cell proliferation. In this study, we investigated the role of microRNA-21 (miR-21) in hypoxia-induced PASMC proliferation and migration. ⋯ Protein expression of miR-21 target genes, specifically programmed cell death protein 4 (PDCD4), Sprouty 2 (SPRY2), and peroxisome proliferator-activated receptor-α (PPARα), was decreased in hypoxia and in PASMC overexpressing miR-21 in normoxia and increased in hypoxic cells in which miR-21 was knocked down. In addition, PPARα 3'-untranslated region (UTR) luciferase-based reporter gene assays demonstrated that PPARα is a direct target of miR-21. Taken together, our findings indicate that miR-21 plays a significant role in hypoxia-induced pulmonary vascular smooth muscle cell proliferation and migration by regulating multiple gene targets.
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Am. J. Physiol. Lung Cell Mol. Physiol. · Dec 2010
Moderate postnatal hyperoxia accelerates lung growth and attenuates pulmonary hypertension in infant rats after exposure to intra-amniotic endotoxin.
To determine the separate and interactive effects of fetal inflammation and neonatal hyperoxia on the developing lung, we hypothesized that: 1) antenatal endotoxin (ETX) causes sustained abnormalities of infant lung structure; and 2) postnatal hyperoxia augments the adverse effects of antenatal ETX on infant lung growth. Escherichia coli ETX or saline (SA) was injected into amniotic sacs in pregnant Sprague-Dawley rats at 20 days of gestation. Pups were delivered 2 days later and raised in room air (RA) or moderate hyperoxia (O₂, 80% O₂ at Denver's altitude, ∼65% O₂ at sea level) from birth through 14 days of age. ⋯ In contrast, severe hyperoxia (≥95% O₂ at Denver's altitude) further reduced lung vessel density after intra-amniotic ETX exposure. We conclude that intra-amniotic ETX induces fetal pulmonary hypertension and causes persistent abnormalities of lung structure with sustained pulmonary hypertension in infant rats. Moreover, moderate postnatal hyperoxia after antenatal ETX restores lung growth and prevents pulmonary hypertension during infancy.