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Cigarette smoke and phagocyte function: effect of chronic exposure in vivo and acute exposure in vitro
Abstract:
Phagocytic function was studied in mice chronically exposed to cigarette smoke, and the effects of in vitro exposure to cigarette smoke on macrophage activity were also assessed. Cultures of radiolabeled Pseudomonas aeruginosa were employed to investigate phagocyte activity in vivo and in vitro. Mice were exposed on weekdays to fresh cigarette smoke for periods up to 37 weeks and the bactericidal and clearance activity of their lungs was measured. Both pulmonary clearance and bactericidal activity was impaired. The clearance of intravenously injected bacteria from the blood of smoke-exposed mice occurred at the same rate as in control mice, but the accumulation of radiolabel by the liver was decreased. In addition, the rate of elimination of radiolabel from the liver was less than the controls. Macrophages exposed to cigarette smoke in vitro initially had a depressed phagocytic rate, but if phagocytosis over a prolonged period was measured it was eventually enhanced over the rate of control macrophages. The vapor phase of cigarette smoke could also transiently inhibit and then enhance the phagocytic activity.
Insights
Chronic cigarette smoke exposure impairs lung antibacterial defenses in mice. While initial macrophage phagocytosis is reduced, prolonged exposure leads to enhanced activity, suggesting complex immune responses to smoke.
Area of Science:
- Immunology
- Pulmonary Medicine
- Toxicology
Background:
- Cigarette smoke is a major environmental toxin affecting respiratory health.
- Phagocytic cells, like macrophages, are crucial for clearing bacterial infections in the lungs.
- The impact of chronic cigarette smoke exposure on macrophage function remains incompletely understood.
Purpose of the Study:
- To investigate the effects of chronic cigarette smoke exposure on in vivo phagocytic function in mice.
- To assess the impact of in vitro cigarette smoke exposure on macrophage phagocytic activity.
- To elucidate the mechanisms underlying altered immune cell function in response to cigarette smoke.
Main Methods:
- Mice were chronically exposed to cigarette smoke for up to 37 weeks.
- Pulmonary bactericidal and clearance activity was measured using radiolabeled Pseudomonas aeruginosa.
- In vitro studies assessed macrophage phagocytic rates following exposure to cigarette smoke and its vapor phase.
Main Results:
- Chronic smoke exposure impaired both pulmonary clearance and bactericidal activity in mice.
- While blood bacterial clearance was unaffected, liver accumulation and elimination of radiolabel were altered.
- In vitro, cigarette smoke initially inhibited, but subsequently enhanced, macrophage phagocytic activity.
Conclusions:
- Chronic cigarette smoke exposure compromises the lung's innate immune defenses against bacterial pathogens.
- Macrophages exhibit a biphasic response to cigarette smoke, with initial inhibition followed by enhanced phagocytosis.
- These findings highlight the complex immunomodulatory effects of cigarette smoke on macrophage function.