American journal of respiratory cell and molecular biology
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Am. J. Respir. Cell Mol. Biol. · Nov 2012
Regulation of Rela/p65 and endothelial cell inflammation by proline-rich tyrosine kinase 2.
We investigated the role of proline-rich tyrosine kinase 2 (Pyk2) in the mechanism of NF-κB activation and endothelial cell (EC) inflammation induced by thrombin, a procoagulant serine protease released in high amounts during sepsis and other inflammatory conditions. Stimulation of ECs with thrombin resulted in a time-dependent activation of Pyk2. RNA interference knockdown of Pyk2 attenuated thrombin-induced activity of NF-κB and expression of its target genes, vascular cell adhesion molecule-1 and monocyte chemoattractant protein-1. ⋯ Depletion of IKKα or IKKβ each impaired RelA/p65 phosphorylation. Taken together, these data identify Pyk2 as a critical regulator of EC inflammation by virtue of engaging IKK to promote the release and the transcriptional capacity of RelA/p65, and, additionally, by its ability to facilitate the nuclear translocation of the released RelA/p65. Thus, specific targeting of Pyk2 may be an effective anti-inflammatory strategy in vascular diseases associated with EC inflammation and intravascular coagulation.
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Am. J. Respir. Cell Mol. Biol. · Nov 2012
CD11c(+)/CD11b(+) cells are critical for organic dust-elicited murine lung inflammation.
Organic dust exposure in the agricultural industry results in significant lung disease. Macrophage infiltrates are increased in the lungs after organic dust exposures, yet the phenotype and functional importance of these cells remain unclear. Using an established intranasal inhalation murine model of dust-induced lung inflammation, animals were treated once or daily for 3 weeks with swine confinement organic dust extract (DE). ⋯ In contrast, after repetitive 3-week exposure to DE, airway lavage fluid and lung tissue neutrophils were significantly increased in clodronate liposome-treated mice compared with control mice. A histological examination of lung tissue demonstrated striking increases in alveolar and bronchiolar inflammation, as well as in the size and distribution of cellular aggregates in clodronate-liposome versus saline-liposome groups repetitively exposed to DE. These studies demonstrate that DE elicits activated CD11c(+)/CD11b(+) macrophages in the lung, which play a critical role in regulating the outcome of DE-induced airway inflammation.
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Am. J. Respir. Cell Mol. Biol. · Nov 2012
TGF-β1 induces tissue factor expression in human lung fibroblasts in a PI3K/JNK/Akt-dependent and AP-1-dependent manner.
The disturbance of hemostatic balance, associated with increased tissue factor (TF) expression and activity, occurs in the lungs of patients with idiopathic pulmonary fibrosis (IPF). However, the molecular mechanisms responsible for the regulation of TF expression under profibrotic conditions have not been assessed. We found that transforming growth factor-β1 (TGF-β1) markedly enhanced TF expression in primary human lung fibroblasts (HLFs), whereas platelet-derived growth factor (PDGF)-BB and IGF (insulin-like growth factor)-1 showed only a moderate effect, and PDGB-CC exerted no effect. ⋯ Moreover, strong immunoreactivity for phosphorylated Akt and JNK as well as c-Fos and JunD was observed in fibroblasts and myofibroblasts in IPF lungs. In conclusion, PI3K/JNK/Akt and AP-1 synergize to induce TF expression in HLFs after TGF-β1 challenge. Our findings provide new insights into the molecular mechanisms responsible for the regulation of TF expression, and open new perspectives on the treatment of pulmonary fibrosis and other diseases characterized by the inappropriate expression of this cell-surface receptor.
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Am. J. Respir. Cell Mol. Biol. · Nov 2012
Sphingosine-1-phosphate receptor-3 is a novel biomarker in acute lung injury.
The inflamed lung exhibits oxidative and nitrative modifications of multiple target proteins, potentially reflecting disease severity and progression. We identified sphingosine-1-phosphate receptor-3 (S1PR3), a critical signaling molecule mediating cell proliferation and vascular permeability, as a nitrated plasma protein in mice with acute lung injury (ALI). We explored S1PR3 as a potential biomarker in murine and human ALI. ⋯ In vitro EC exposure to barrier-disrupting agents induced S1PR3 nitration and the shedding of S1PR3-containing microparticles, which significantly reduced TER, consistent with increased permeability. These changes were attenuated by reduced S1PR3 expression (small interfering RNAs). These results suggest that microparticles containing nitrated S1PR3 shed into the circulation during inflammatory lung states, and represent a novel ALI biomarker linked to disease severity and outcome.
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Am. J. Respir. Cell Mol. Biol. · Nov 2012
Actin filament reorganization is a key step in lung inflammation induced by systemic inflammatory response syndrome.
Acute lung injury (ALI) induced by systemic inflammatory response syndrome (SIRS) is characterized by deterioration in pulmonary function and leukocyte-associated lung inflammation. Actin fragment (F-actin) reorganization is required for leukocyte activation, adhesion, and transcription of inflammatory factors. We tested the hypothesis that F-actin plays a central role in SIRS-induced ALI. ⋯ In addition, after LPS challenge, we observed F-actin reorganization and the up-regulation of inflammatory factors in pulmonary monocytes, which could also be blocked by CB pretreatment. F-actin reorganization initiates lung inflammation via increased blood neutrophil adhesion and migration, and by the production of inflammatory factors by pulmonary monocytes. Thus, blocking F-actin reorganization may potentially prevent and treat SIRS-induced ALI.