American journal of respiratory cell and molecular biology
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Am. J. Respir. Cell Mol. Biol. · Dec 2005
Comparative StudyLocalization and upregulation of cysteinyl leukotriene-1 receptor in asthmatic bronchial mucosa.
We have tested the hypothesis that the CysLT(1) receptor is expressed by a variety of bronchial mucosal immune cells and that the numbers of these cells increase in asthma, when stable and in exacerbations. We have applied in situ hybridization and immunohistochemistry to endobronchial biopsy tissue to identify and count inflammatory cells expressing CysLT(1) receptor mRNA and protein, respectively, and used double immunohistochemistry to identify the specific cell immunophenotypes expressing the receptor. Double-labeling demonstrated that bronchial mucosal eosinophils, neutrophils, mast cells, macrophages, B-lymphocytes, and plasma cells, but not T-lymphocytes, expressed the CysLT(1) receptor. ⋯ Compared with stable asthma, there were further significant increases in subjects hospitalized for a severe exacerbation of their asthma (mRNA: median = 113 and protein: 156 mm(-2); n = 15; P < 0.002). For the combined data of both asthma subgroups, there were strong positive correlations between the increased numbers of CD45+ leukocytes and the greater numbers of cells expressing CysLT(1) receptor (mRNA: r = 0.60, P < 0.001; protein: r = 0.73, P < 0.0001). In conclusion, a variety of immunohistologically distinct inflammatory cells express the CysLT(1) receptor in the bronchial mucosa and both these and the total number of leukocytes increase in mild stable disease and increase further when there is a severe exacerbation of asthma.
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Am. J. Respir. Cell Mol. Biol. · Jul 2005
Regulation of interleukin-5-induced beta2-integrin adhesion of human eosinophils by phosphoinositide 3-kinase.
We examined the role of phosphoinositide 3-kinase (PI3K) in integrin-mediated eosinophil adhesion. Deltap85, a dominant-negative form of the class IA PI3K adaptor subunit, was fused to an HIV-TAT protein transduction domain (TAT-Deltap85). Recombinant TAT-Deltap85 inhibited interleukin (IL)-5-stimulated phosphorylation of protein kinase B, a downstream target of PI3K. beta(2)-Integrin-dependent adhesion caused by IL-5 to the plated intracellular adhesion molecule-1 surrogate, bovine serum albumin, was inhibited by TAT-Deltap85 in a concentration-dependent manner. ⋯ IL-5 caused translocation of PKCdelta from the cytosol to cell membrane; inhibition of PI3K by wortmannin blocked translocation of PKCdelta. Western blot analysis demonstrated that extracellular signal-regulated kinase phosphorylation, a critical intermediary in adhesion elicited by IL-5, was blocked by inhibition of either PI3K or PKC-delta. These data suggest that extracellular signal-regulated kinase-mediated adhesion of beta(2)-integrin caused by IL-5 is mediated in human eosinophils by a class IA PI3K through activation of a PKCdelta pathway.
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Am. J. Respir. Cell Mol. Biol. · May 2005
Role of hypoxia-inducible factor-1alpha in hypoxia-induced apoptosis of primary alveolar epithelial type II cells.
Hypoxia affects alveolar homeostasis and may induce epithelial injury, which has been implicated in lung diseases such as fibrosis. The underlying cellular and molecular mechanisms are, however, largely unknown. Primary rat alveolar epithelial type II cells (ATII) exposed to graded hypoxia for 24 and 48 h caused a dose-dependent induction of cell cycle arrest and suppression of proliferation, which were comparable to the effects of angiotensin II, a potent inducer of ATII cell death. ⋯ In line with these data, overexpression of HIF-1alpha by transient transfection enhanced the hypoxia-induced apoptosis. Thus, we conclude that hypoxia suppresses alveolar epithelial cell proliferation and enhances ATII apoptosis through activation of the HIF-1alpha/HRE axis and a mechanism that involves Bnip3L. Targeting HIF-1alpha may represent a new strategy that could impede the alveolar denudation that is observed in several lung diseases.
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Am. J. Respir. Cell Mol. Biol. · Apr 2005
Interleukin-1beta causes pulmonary inflammation, emphysema, and airway remodeling in the adult murine lung.
The production of the inflammatory cytokine interleukin (IL)-1 is increased in lungs of patients with chronic obstructive pulmonary disease (COPD) or asthma. To characterize the in vivo actions of IL-1 in the lung, transgenic mice were generated in which human IL-1beta was expressed in the lung epithelium with a doxycycline-inducible system controlled by the rat Clara cell secretory protein (CCSP) promoter. Induction of IL-1beta expression in the lungs of adult mice caused pulmonary inflammation characterized by neutrophil and macrophage infiltrates. ⋯ Decreased immunostaining for the winged helix transcription factor FOXA2 was associated with goblet cell hyperplasia in IL-1beta-expressing mice. The production of the neutrophil attractant CXC chemokines KC (CXCL1) and MIP-2 (CXCL2), and of matrix metalloproteases MMP-9 and MMP-12, was increased by IL-1beta. Chronic production of IL-1beta in respiratory epithelial cells of adult mice causes lung inflammation, enlargement of distal airspaces, mucus metaplasia, and airway fibrosis in the adult mouse.
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Am. J. Respir. Cell Mol. Biol. · Nov 2004
Cigarette smoke induces persisting increases of vasoactive mediators in pulmonary arteries.
The pathogenesis of cigarette smoke-induced pulmonary hypertension is not understood. We previously reported that a single smoke exposure acutely but transiently upregulated gene expression of the vasoconstrictor/vasoproliferative agents endothelin (ET) and vascular endothelial growth factor in pulmonary arteries from rat lungs. To determine whether similar changes occurred with chronic smoke exposure, we exposed Hartley guinea pigs, an outbred strain that develops pulmonary hypertension, to smoke for 2, 4, or 12 wk. ⋯ Protein levels of these mediators were also elevated by immunohistochemical staining and correlated with increases in gene expression levels. We conclude that, in some animals, cigarette smoke induces persisting and marked vascular production of mediators that control vascular muscularization and contraction/dilation. These changes may be important in the development of smoke-induced pulmonary hypertension.