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Alveolar macrophage antioxidants prevent hydrogen peroxide-mediated lung damage
R J McDonald1, E M Berger, J E Repine
1Department of Pediatrics, University of California, Davis.
Abstract:
Since alveolar macrophages (AM) contain large amounts of antioxidants, we hypothesized that AM may be effective scavengers of H2O2 and reduce H2O2-mediated injury. We found that addition of AM to perfusates decreased lung weight gain in isolated rat lungs perfused with the H2O2-generating system of beta-D-glucose and glucose oxidase (G/GO) and that AM were as effective as the addition of erythrocytes or catalase in reducing injury. The ability of AM to protect isolated lungs corresponded with their ability to reduce H2O2 concentrations in vitro. By comparison, azide-treated AM had decreased catalase activity, did not prevent injury to lungs perfused with G/GO, and ineffectively decreased H2O2 in vitro. Mechanical disruption or stimulation of AM by phorbol myristate acetate or zymosan did not alter the AM H2O2-scavenging ability. We conclude that AM can scavenge H2O2 and limit oxidant-mediated injury.
Insights
Alveolar macrophages (AM) effectively scavenge hydrogen peroxide (H2O2), significantly reducing lung injury caused by oxidants. This antioxidant capacity protects lung tissue from H2O2-mediated damage.
Area of Science:
- Pulmonary Medicine
- Cellular Biology
- Biochemistry
Background:
- Alveolar macrophages (AM) possess abundant antioxidants.
- Hydrogen peroxide (H2O2) can cause significant tissue injury.
Purpose of the Study:
- To investigate the H2O2-scavenging capacity of AM.
- To determine if AM can mitigate H2O2-mediated lung injury.
Main Methods:
- Isolated rat lungs were perfused with a beta-D-glucose and glucose oxidase (G/GO) system to generate H2O2.
- The protective effects of AM were compared to erythrocytes and catalase.
- H2O2 concentrations were measured in vitro with and without AM.
Main Results:
- AM addition reduced lung weight gain in G/GO-perfused lungs, indicating decreased injury.
- AM demonstrated H2O2-scavenging ability in vitro, correlating with lung protection.
- Azide-treated AM, with reduced catalase activity, failed to protect lungs or reduce H2O2.
- AM stimulation or disruption did not affect their H2O2-scavenging ability.
Conclusions:
- Alveolar macrophages effectively scavenge H2O2.
- AM play a protective role against H2O2-mediated lung injury.