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A controlled study of oxygen metabolite release by alveolar macrophages from children with interstitial lung disease
A Clement1, K Chadelat, J Masliah
1Departement de Pediatrie, Hôpital Trousseau, Paris, France.
Abstract:
The ability of alveolar macrophages (AM) to release O2 metabolites was studied in 8 children with interstitial lung disease (ILD), and in 11 children without lung parenchyma disorder. AM were collected by bronchoalveolar lavage. The experiments were performed on unstimulated AM and on AM stimulated by phorbol myristate acetate (PMA) or zymosan. Our results indicated that, with or without triggering agent, the amount of O2 metabolites release was a linear function pattern with time. The accumulation of superoxide anion (O2-) and hydrogen peroxide (H2O2) into the extracellular medium differed depending on the triggering agent used: with PMA, the amount of O2- released was threefold the amount of H2O2 detected in the medium, whereas with zymosan the O2- accumulation was tenfold higher than the amount of H2O2 measured. In patients with ILD, a significant increase in the amount of H2O2 release was observed for both unstimulated and stimulated AM (p less than 0.001). In this group, the measurement was repeated after a 2-month steroid treatment: prednisone had markedly improved the clinical, radiologic, and functional status of the patients, and this improvement was in good correlation with the decrease of O2 metabolite production. The amount of H2O2 release in each case was within the range of control values. Evaluation of O2 metabolite release by AM could be a useful parameter in the assessment of the activity of ILD.
Insights
Alveolar macrophages in children with interstitial lung disease (ILD) release more hydrogen peroxide. Steroid treatment reduced this production, suggesting O2 metabolite release can assess ILD activity.
Area of Science:
- Pulmonary Medicine
- Immunology
- Biochemistry
Background:
- Alveolar macrophages (AM) play a crucial role in lung immunity.
- Oxygen (O2) metabolite production by AM is a key indicator of inflammatory processes.
- Interstitial lung disease (ILD) involves chronic inflammation of lung tissue.
Purpose of the Study:
- To investigate O2 metabolite release by AM in children with ILD.
- To assess the impact of steroid treatment on AM O2 metabolite production in ILD patients.
- To determine if AM O2 metabolite release can serve as a biomarker for ILD activity.
Main Methods:
- Collected AM via bronchoalveolar lavage from children with and without ILD.
- Measured superoxide anion (O2-) and hydrogen peroxide (H2O2) release from unstimulated and stimulated (PMA, zymosan) AM.
- Re-evaluated H2O2 production after 2-month prednisone treatment in ILD patients.
Main Results:
- O2 metabolite release followed a linear time-dependent pattern.
- Superoxide anion release was significantly higher than hydrogen peroxide release, especially with zymosan stimulation.
- Children with ILD showed significantly increased H2O2 release from AM (p < 0.001).
- Prednisone treatment improved ILD status and normalized H2O2 production by AM.
Conclusions:
- Increased H2O2 release by AM is characteristic of ILD in children.
- O2 metabolite production by AM correlates with ILD activity and treatment response.
- Evaluating AM O2 metabolite release may be a valuable tool for assessing ILD activity.