Related Experiment Videos
Early effects of smoke inhalation on alveolar macrophage functions
A Bidani1, C Z Wang, T A Heming
1Department of Internal Medicine, University of Texas Medical Branch, Galveston, USA.
Abstract:
Alveolar macrophage (AM) dysfunctions have been implicated in the pathogenesis of smoke inhalation lung injury. We investigated the early (within 70 min) effects of smoke inhalation on AM. The cells were recovered by bronchoalveolar lavage from rabbits ventilated with cotton smoke for 5 min followed by O2/room air for 60 min (smoke-exposed) or with room air in place of smoke (control). Smoke injury caused arterial blood carboxyhaemoglobin levels to increase 11-fold and reduced arterial blood PO2 (measured approximately 1 h postinjury) by 25 per cent. Scanning electron micrographs revealed denudation of plasmalemmal pseudopods in smoke-exposed AM. Smoke exposure suppressed both AM adherence to plastic and phagocytosis of opsonized bacteria. Basal superoxide (O2-) production was elevated in smoke-exposed AM, compared with controls, whereas PMA-stimulated O2- production was unaffected. Smoke-exposed AM had reduced basal secretion of tumour necrosis factor-alpha (TNF-alpha), but displayed a greater TNF response to stimulation with LPS than did control cells. LPS-stimulated TNF-alpha releases from control and smoke-exposed AM were suppressed by phosphodiesterase inhibitors pentoxifylline and theophylline, and were enhanced by the lipoxygenase inhibitor, MK886. The early responses of AM to smoke inhalation lung injury are consistent with activation of O2- production and priming of TNF-alpha release, concurrent with a functional down regulation of phagocytosis.
Insights
Early smoke inhalation impairs alveolar macrophage (AM) function, reducing phagocytosis and altering tumor necrosis factor-alpha (TNF-alpha) release. These AM dysfunctions contribute to smoke inhalation lung injury pathogenesis.
Area of Science:
- Pulmonary Medicine
- Immunology
- Toxicology
Background:
- Alveolar macrophages (AMs) play a crucial role in lung defense.
- Dysfunction of AMs is implicated in the pathogenesis of smoke inhalation lung injury.
Purpose of the Study:
- To investigate the early effects of smoke inhalation on AM function within 70 minutes.
- To understand the initial impact of smoke exposure on AM cellular responses.
Main Methods:
- Rabbits were exposed to cotton smoke or room air (control).
- Alveolar macrophages were collected via bronchoalveolar lavage.
- AM adherence, phagocytosis, superoxide (O2-) production, and tumor necrosis factor-alpha (TNF-alpha) secretion were assessed.
Main Results:
- Smoke exposure significantly increased carboxyhaemoglobin and decreased arterial PO2.
- AMs showed reduced adherence and phagocytosis, with elevated basal superoxide production.
- Basal TNF-alpha secretion was reduced, but LPS-stimulated TNF-alpha release was enhanced in smoke-exposed AMs.
Conclusions:
- Early smoke inhalation activates AM superoxide production and primes TNF-alpha release.
- Functional downregulation of AM phagocytosis occurs rapidly after smoke exposure.
- These early AM alterations contribute to the pathogenesis of smoke inhalation lung injury.