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Autophagic vacuoles produced in vitro. I. Studies on cultured macrophages exposed to chloroquine
Abstract:
Mouse macrophages exposed to 30 microg/ml of chloroquine in vitro develop autophagic vacuoles containing various cytoplasmic components and acid phosphatase. The early toxic vacuoles appear in the perinuclear region within 15 min; on electron microscopy, they show irregular shape, amorphous moderately dense content, apparent double membranes, and in some instances curved thin tubular extensions with a central, dark linear element. Cytoplasmic structures are probably transported into the vacuoles by invagination of the vacuolar membrane. After exposure to chloroquine for 1-4 hr, macrophages display large vacuoles containing degraded cytoplasmic structures, membranous whorls, and amorphous material. When chloroquine is removed by changing the culture medium after 4 hr, the cells survive and 24 hr later they exhibit no abnormality except for large cytoplasmic dense bodies packed with membrane lamellae. During recovery chloroquine disappears from the cells. 24 hr after exposure to chloroquine the macrophages have accumulated less hydrolases than control cells.
Insights
Chloroquine induces autophagic vacuoles in mouse macrophages, disrupting cellular processes. Recovery is possible after drug removal, though cellular changes persist.
Area of Science:
- Cell Biology
- Toxicology
Background:
- Chloroquine is an antimalarial drug with known effects on cellular processes.
- Autophagy is a fundamental cellular mechanism for degrading damaged components.
Purpose of the Study:
- To investigate the in vitro effects of chloroquine on mouse macrophages.
- To characterize the formation and ultrastructure of chloroquine-induced autophagic vacuoles.
- To examine the recovery process of macrophages after chloroquine exposure.
Main Methods:
- In vitro exposure of mouse macrophages to chloroquine (30 microg/ml).
- Electron microscopy to visualize vacuole formation and ultrastructure.
- Monitoring of cellular changes and drug clearance during recovery.
Main Results:
- Chloroquine rapidly induced autophagic vacuoles containing cytoplasmic components and acid phosphatase.
- Vacuoles exhibited irregular shapes, double membranes, and tubular extensions.
- Macrophages survived chloroquine removal, with residual dense bodies containing membrane lamellae after 24 hours.
- Hydrolase accumulation was reduced in macrophages 24 hours post-exposure.
Conclusions:
- Chloroquine induces significant alterations in macrophage autophagy, forming characteristic vacuoles.
- Macrophages can recover from chloroquine exposure, although persistent ultrastructural changes are observed.
- The study provides insights into chloroquine's cellular toxicity and the dynamics of autophagic vacuole formation.