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Ultrastructural alterations in macrophages after phagocytosis of acrylic microspheres
Abstract:
The effect of microparticles on the survival of cultured mouse peritoneal macrophages was investigated using doses of 0.01-0.1 mg of lyophilized particles/ml of medium and 5 X 10(5) cells, corresponding to approximately 4000-40,000 particles per cell. The lowest dose did not significantly change the survival time as compared with the controls, while approximately 75% of the cells were lost during the first 48 h on exposure to the highest dose. High doses of particles induce cellular damage. The morphology and stability of the lysosomal apparatus was followed with electron microscopy, acid phosphatase cytochemistry, and acridine orange uptake. Alteration of the lysosomal vacuome was characterized by a greatly enhanced rate of autophagocytosis, the formation of huge secondary lysosomes containing microparticles, and labilization of the vacuome with loss of acidity and a tendency to leak acid phosphatase into the cell sap.
Insights
High doses of microparticles significantly reduce mouse macrophage survival and damage cellular lysosomes. Lower doses showed no significant effect, indicating a dose-dependent toxicity impacting cell viability and lysosomal function.
Area of Science:
- Cell Biology
- Toxicology
- Immunology
Background:
- Macrophages are crucial immune cells involved in phagocytosis and cellular debris clearance.
- Microparticles can be environmental or endogenous and their biological effects require investigation.
- Lysosomes are key organelles for cellular degradation and recycling.
Purpose of the Study:
- To investigate the impact of varying microparticle doses on the survival of cultured mouse peritoneal macrophages.
- To elucidate the cellular mechanisms underlying microparticle-induced toxicity, focusing on lysosomal integrity and function.
Main Methods:
- Cultured mouse peritoneal macrophages were exposed to a range of microparticle doses (0.01-0.1 mg/ml).
- Cell survival was assessed over 48 hours.
- Lysosomal morphology and function were evaluated using electron microscopy, acid phosphatase cytochemistry, and acridine orange uptake.
Main Results:
- High microparticle doses (0.1 mg/ml) led to a significant loss of macrophage viability (approx. 75% loss within 48 hours).
- Low microparticle doses (0.01 mg/ml) did not significantly affect cell survival compared to controls.
- Microparticle exposure induced lysosomal alterations, including increased autophagocytosis, formation of large secondary lysosomes containing particles, and lysosomal membrane labilization.
Conclusions:
- High concentrations of microparticles induce significant cellular damage and mortality in macrophages.
- Microparticle toxicity is mediated through disruption of lysosomal function, leading to impaired cellular homeostasis.
- These findings highlight the potential cytotoxic effects of microparticles on immune cells.
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