Increased prostaglandin E2 concentrations and cyclooxygenase-2 expression in asthmatic subjects with sputum eosinophilia

Prostaglandin E2 (PGE2) is known to be produced within human airways, but it is not clear whether in airway diseases it can play a deleterious or a beneficial role. Recently it has been reported that PGE2 can enhance eosinophil survival in vitro. To evaluate whether the concentrations of PGE2 in ast...

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Bibliographic Details
Published in:Journal of allergy and clinical immunology 2003-10, Vol.112 (4), p.709-716
Main Authors: PROFITA, Mirella, SALA, Angelo, VIGNOLA, Antonio M, BONANNO, Anna, RICCOBONO, Loredana, SIENA, Liboria, MELIS, Mario R, DI GIORGI, Rossana, MIRABELLA, Franco, GJOMARKAJ, Mark, BONSIGNORE, Giovanni
Format: Article
Language:English
Subjects:
Adult
Allergic diseases
Apoptosis - drug effects
Asthma
Asthma - metabolism
Asthma - pathology
Asthma - physiopathology
Bacterial infections
Biological and medical sciences
Blood Proteins - analysis
Cyclooxygenase 2
Cytokines
Dinoprostone - analysis
Dinoprostone - biosynthesis
Dinoprostone - pharmacology
Enzymes
Eosinophil Granule Proteins
Eosinophilia - pathology
Eosinophils
Female
Humans
Immunohistochemistry
Immunopathology
Isoenzymes - analysis
Leukocyte Count
Male
Medical sciences
Membrane Proteins
Metabolites
Middle Aged
Osmolar Concentration
Prostaglandin-Endoperoxide Synthases - analysis
Respiratory and ent allergic diseases
Ribonucleases - analysis
Rodents
Smooth muscle
Sputum - chemistry
Sputum - cytology
Sputum - metabolism
Statistical analysis
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Summary:Prostaglandin E2 (PGE2) is known to be produced within human airways, but it is not clear whether in airway diseases it can play a deleterious or a beneficial role. Recently it has been reported that PGE2 can enhance eosinophil survival in vitro. To evaluate whether the concentrations of PGE2 in asthmatic airways correlate with the number of eosinophils and can be responsible for eosinophil-enhanced survival and to identify the cyclooxygenase isoform contributing to the synthesis of PGE2 by cells present in asthmatic airways. Reversed-phase high-performance liquid chromatography and/or specific radioimmunoassay was used to measure PGE2 concentrations in induced sputum supernatants from 14 control and 30 asthmatic subjects. Correlations between concentrations of PGE2 and the number of eosinophils in induced sputum were evaluated. Expression of cyclooxygenase-2 (COX-2) in induced sputum cells was determined by immunocytochemistry, and the effect of COX-2 inhibition on PGE2 production was evaluated with the use of radiolabeled arachidonic acid. The effects on eosinophil apoptosis by PGE2 or induced sputum supernatants were studied by using peripheral blood eosinophils obtained by negative immunomagnetic selection. PGE2 concentrations resulted in elevated samples from asthmatic subjects and directly correlated with the percentage of eosinophils and the concentrations of eosinophilic cationic protein. Immunostaining for COX-2 showed enhanced expression in macrophages of asthmatic subjects when compared with control subjects, and the use of a specific COX-2 inhibitor provided evidence that PGE2 synthesis was the result of COX-2 enzymatic activity in asthma-induced sputum cells. Supernatant from induced sputum of asthmatic subjects with high eosinophil counts caused a decreased apoptosis of peripheral blood eosinophils when compared with control subjects, and immunoprecipitation of PGE2 significantly reverted this phenomenon, suggesting that PGE2 was present in biologically relevant concentrations in induced sputum. The results obtained suggest that COX-2 expression in alveolar macrophages from asthmatic subjects may contribute to enhanced eosinophil survival through an increased PGE2 production.
ISSN:0091-6749
1097-6825
DOI:10.1016/S0091-6749(03)01889-X