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Investigation of the component of Propionibacterium acnes (Corynebacterium parvum) responsible for macrophage
Abstract:
Mouse peritoneal macrophages, activated with Propionibacterium acnes (Corynebacterium parvum) in vivo, exhibited altered morphological characteristics, increased acid phosphatase activity, and release of [EH]thymidine-labeled DNA from tumor cells in vitro. Comparison with macrophages from mice injected with a control organism, P. jensenii, showed that the morphological changes, but not acid phosphatase, correlated with the development of tumoricidal activity. Investigation of the microbial component responsible for this activity indicated it was heat stable and refractory to extraction by methanol-chloroform, dilute acid, butanol, or a serial combination of extraction procedures. When the cells were disrupted by mechanical breakage, no activity could be found in the cell wall, soluble cytoplasm, or particulate cytoplasm. These results suggest that intact organisms are required for macrophage activation, and they may resolve conflicting reports on the nature of the immunostimulating activity of P. acnes.
Insights
Propionibacterium acnes (Corynebacterium parvum) activates mouse macrophages for tumor cell killing. Intact bacteria are essential for this immunostimulating activity, not just their cellular components.
Area of Science:
- Immunology
- Microbiology
- Cancer Research
Background:
- Propionibacterium acnes (Corynebacterium parvum) is known to modulate the immune system.
- Macrophage activation is a key component of anti-tumor immunity.
- Previous studies on the immunostimulating properties of P. acnes have yielded conflicting results.
Purpose of the Study:
- To investigate the effects of P. acnes on mouse peritoneal macrophages in vitro.
- To identify the microbial component responsible for P. acnes-induced macrophage activation and tumoricidal activity.
- To clarify the mechanism of P. acnes-mediated immunostimulation.
Main Methods:
- Activation of mouse peritoneal macrophages with P. acnes in vivo.
- Assessment of macrophage morphology, acid phosphatase activity, and tumor cell DNA release in vitro.
- Extraction and fractionation of microbial components to determine the active moiety.
Main Results:
- P. acnes-activated macrophages showed altered morphology and increased acid phosphatase activity.
- Macrophage-mediated release of thymidine-labeled DNA from tumor cells was observed.
- Morphological changes correlated with tumoricidal activity, while acid phosphatase did not.
- The immunostimulating activity was heat-stable and resistant to various extraction methods.
- Activity was lost upon mechanical disruption of the bacteria, indicating the requirement for intact organisms.
Conclusions:
- Intact Propionibacterium acnes organisms are required for effective macrophage activation and tumoricidal activity.
- The study resolves conflicting reports by highlighting the necessity of whole bacterial cells for immunostimulation.
- Findings suggest a specific mechanism for P. acnes-mediated immune modulation relevant to cancer therapy.