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J Allergy Clin Immunol. 2008 Apr;121(4):893-902.e2. doi: 10.1016/j.jaci.2008.02.004.

Cell-specific activation profile of extracellular signal-regulated kinase 1/2, Jun N-terminal kinase, and p38 mitogen-activated protein kinases in asthmatic airways.

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1
Division of Allergy and Immunology, Department of Medicine, National Jewish Medical and Research Center, Denver, CO 80206, USA.

Abstract

BACKGROUND:

Many airway cells manifest signs of chronic activation in asthma. The mechanism of this chronic activation is unknown.

OBJECTIVES:

We sought to study the activation of the mitogen-activated protein kinase (MAPK) signaling pathway in airway cells.

METHODS:

Endobronchial biopsy specimens from patients with severe and mild asthma (n = 17 in each group) and healthy control subjects (n = 15) were analyzed for the phosphorylated MAPKs extracellular signal-regulated kinase (ERK) 1/2, p38, and Jun N-terminal kinase (JNK) and their downstream effectors by means of immunofluorescence staining. Airway epithelial activation of ERK1/2 and p38 was studied by using Western blotting. Epithelial function was studied by means of real-time PCR, ELISA, and the thymidine incorporation assay.

RESULTS:

We detected strong phospho-ERK1/2 staining in airway epithelium and smooth muscle cells in biopsy specimens from asthmatic patients. Fluorescent areas per image, as well as mean fluorescence intensity, were significantly (P < .0001) different among the 3 study groups (patients with severe asthma, patients with mild asthma, and healthy control subjects). Patients with severe asthma also demonstrated strong phospho-p38 staining, mostly in epithelial cells, which was significantly different from that in patients with mild asthma (P = .0001) and healthy control subjects (P = .02). Phospho-JNK primarily stained airway smooth muscle cells. Healthy subjects showed the highest intensity of phospho-JNK staining compared with that seen in patients with severe (P = .004) and mild asthma (P = .003). Inhibition of ERK1/2 and p38 in primary airway epithelial cells blocked their proliferation and expression of select, but not all, chemokines.

CONCLUSIONS:

Significant phosphorylation of ERK1/2 and p38 and their correlation with disease severity suggests that the foregoing signaling pathways play an important role in asthma. The ERK1/2 and p38 pathways regulate epithelial cell secretory function and proliferation.

PMID:
18395552
DOI:
10.1016/j.jaci.2008.02.004
[Indexed for MEDLINE]

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