American journal of respiratory cell and molecular biology
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Am. J. Respir. Cell Mol. Biol. · Dec 2012
Increased surfactant protein D fails to improve bacterial clearance and inflammation in serpinB1-/- mice.
Previously, we described the protective role of the neutrophil serine protease inhibitor serpinB1 in preventing early mortality of Pseudomonas aeruginosa lung infection by fostering bacterial clearance and limiting inflammatory cytokines and proteolytic damage. Surfactant protein D (SP-D), which maintains the antiinflammatory pulmonary environment and mediates bacterial removal, was degraded in infected serpinB1-deficient mice. Based on the hypothesis that increased SP-D would rescue or mitigate the pathological effects of serpinB1 deletion, we generated two serpinB1(-/-) lines overexpressing lung-specific rat SP-D and inoculated the mice with P. aeruginosa. ⋯ SP-D of infected wild-type mice was intact in 43-kD monomers by reducing SDS-PAGE. By contrast, proteolytic fragments of 35, 17, and 8 kD were found in infected SP-D(low)serpinB1(-/-), SP-D(high) serpinB1(-/-) mice, and serpinB1(-/-) mice. Thus, although therapies to increase lung concentration of SP-D may have beneficial applications, the findings suggest that therapy with SP-D may not be beneficial for lung inflammation or infection if the underlying clinical condition includes excess proteolysis.
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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.