American journal of physiology. Lung cellular and molecular physiology
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Am. J. Physiol. Lung Cell Mol. Physiol. · Apr 2012
Deregulated Stat3 signaling dissociates pulmonary inflammation from emphysema in gp130 mutant mice.
Interleukin (IL)-6 is a potent immunomodulatory cytokine that is associated with emphysema, a major component of chronic obstructive pulmonary disease (COPD). IL-6 signaling via the gp130 coreceptor is coupled to multiple signaling pathways, especially the latent transcription factor signal transducer and activator of transcription (Stat)3. However, the pathological role of endogenous gp130-dependent Stat3 activation in emphysema is ill defined. ⋯ Furthermore, COPD lung tissue displayed increased levels of IL-6 and apoptotic alveolar cells, supporting our previous observation that increased endogenous IL-6 expression in the lungs of gp130(F/F) mice contributes to emphysema by promoting alveolar cell apoptosis. Collectively, our data suggest that IL-6 promotes emphysema via upregulation of Stat3-independent apoptosis, whereas IL-6 induction of lung inflammation occurs via Stat3. We propose that while discrete targeting of Stat3 may alleviate pulmonary inflammation, global targeting of IL-6 potentially represents a therapeutically advantageous approach to combat COPD phenotypes where emphysema predominates.
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Am. J. Physiol. Lung Cell Mol. Physiol. · Apr 2012
N-acetylcysteine prevents pulmonary edema and acute kidney injury in rats with sepsis submitted to mechanical ventilation.
Sepsis is a common cause of acute kidney injury (AKI) and acute lung injury. Oxidative stress plays as important role in such injury. The aim of this study was to evaluate the effects that the potent antioxidant N-acetylcysteine (NAC) has on renal and pulmonary function in rats with sepsis. ⋯ In CLP + NAC rats, α-ENaC expression was upregulated, whereas that of NKCC1 was downregulated, although the difference was not significant. In the CLP + NAC group, oxidative stress was significantly lower and survival rates were significantly higher than in the CLP group. The protective effects of NAC (against kidney and lung injury) are likely attributable to the decrease in oxidative stress, suggesting that NAC can be useful in the treatment of sepsis.
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Am. J. Physiol. Lung Cell Mol. Physiol. · Mar 2012
BMP type II receptor deficiency confers resistance to growth inhibition by TGF-β in pulmonary artery smooth muscle cells: role of proinflammatory cytokines.
Mutations in the bone morphogenetic protein (BMP) type II receptor (BMPR-II) underlie most cases of heritable pulmonary arterial hypertension (HPAH) and a significant proportion of sporadic cases. Pulmonary artery smooth muscle cells (PASMCs) from patients with pulmonary arterial hypertension (PAH) not only exhibit attenuated growth suppression by BMPs, but an abnormal mitogenic response to transforming growth factor (TGF)-β1. We sought to define the mechanism underlying this loss of the antiproliferative effects of TGF-β1 in BMPR-II-deficient PASMCs. ⋯ This study establishes that BMPR-II deficiency leads to failed growth suppression by TGF-β1 in PASMCs. This effect is Smad-independent but is associated with inappropriately altered NF-κB signaling and enhanced induction of IL-6 and IL-8 expression. Our study provides a rationale to test anti-interleukin therapies as an intervention to neutralize this inappropriate response and restore the antiproliferative response to TGF-β1.
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Am. J. Physiol. Lung Cell Mol. Physiol. · Mar 2012
Apocynin improves oxygenation and increases eNOS in persistent pulmonary hypertension of the newborn.
NADPH oxidase is a major source of superoxide anions in the pulmonary arteries (PA). We previously reported that intratracheal SOD improves oxygenation and restores endothelial nitric oxide (NO) synthase (eNOS) function in lambs with persistent pulmonary hypertension of the newborn (PPHN). In this study, we determined the effects of the NADPH oxidase inhibitor apocynin on oxygenation, reactive oxygen species (ROS) levels, and NO signaling in PPHN lambs. ⋯ Apocynin decreased the interaction between NADPH oxidase subunits p22(phox) and p47(phox) and decreased the expression of Nox2 and p22(phox) in ventilated PPHN lungs. These findings were associated with decreased superoxide and 3-nitrotyrosine levels in the PA of apocynin-treated PPHN lambs. eNOS protein expression, endothelial NO levels, and tetrahydrobiopterin-to-dihydrobiopterin ratios were significantly increased in PA from apocynin-treated lambs, although cGMP levels did not significantly increase and phosphodiesterase-5 activity did not significantly decrease. NADPH oxidase inhibition with apocynin may improve oxygenation, in part, by attenuating ROS-mediated vasoconstriction and by increasing NOS activity.
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Am. J. Physiol. Lung Cell Mol. Physiol. · Mar 2012
miR-21 regulates chronic hypoxia-induced pulmonary vascular remodeling.
Chronic hypoxia causes pulmonary vascular remodeling leading to pulmonary hypertension (PH) and right ventricle (RV) hypertrophy. Aberrant expression of microRNA (miRNA) is closely associated with a number of pathophysiologic processes. However, the role of miRNAs in chronic hypoxia-induced pulmonary vascular remodeling and PH has not been well characterized. ⋯ We found that sequestration of miR-21, either before or after hypoxia exposure, diminished chronic hypoxia-induced PH and attenuated hypoxia-induced pulmonary vascular remodeling, likely through relieving the suppressed expression of miR-21 targets in the lungs of hypoxia-exposed mice. Overexpression of miR-21 enhanced, whereas downregulation of miR-21 diminished, the proliferation of human PASMCs in vitro and the expression of cell proliferation associated proteins, such as proliferating cell nuclear antigen, cyclin D1, and Bcl-xL. Our data suggest that miR-21 plays an important role in the pathogenesis of chronic hypoxia-induced pulmonary vascular remodeling and also suggest that miR-21 is a potential target for novel therapeutics to treat chronic hypoxia associated pulmonary diseases.