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The effect of stress in vivo on the function of mouse macrophages in vitro
H J Aarstad1, S O Kolset, R Seljelid
1Institute of Medical Biology, University of Tromsø, Norway.
Abstract:
Macrophages were harvested from home cage control (HCC) mice, and from mice which had been stressed by repeated brief exposures (3-8 min) to cold water at 10-15 degrees C twice daily for 8 or 14 days. Macrophages obtained from mice stressed 8 or 14 days compared to macrophages from HCC mice showed in vitro increased amounts of membrane-bound prothrombinase activity, whereas the thrombin degradation activity was unchanged. Furthermore, macrophages of mice stressed 8 days showed increased release of coagulation factor X/Xa to supernatant in vitro. These findings suggest an increased amount of prothrombinase complex enzymes on the surface of macrophages from mice stressed 8 days, and increased activity of the prothrombinase enzyme in macrophages from mice stressed 14 days. The synthesis of proteoglycans (PG) and glycosaminoglycans (GAG) was increased in macrophages from mice stressed 8 days compared to macrophages from HCC mice and mice stressed 14 days. When macrophages from mice stressed 8 days or HCC mice were stimulated in vitro with phorbol myristate acetate (PMA) and IL-1 or PMA and IL-2, a changed PG/GAG synthesis was observed only in macrophages from the HCC animals. Furthermore, both the tumour cytotoxicity and the released tumour necrosis factor (TNF) were decreased from macrophages from mice stressed 14 days compared to HCC mice. The results suggest that the macrophages of stressed mice have an altered mode of function more complex than a simple general suppression or activation.
Insights
Stress alters macrophage function, impacting blood clotting, proteoglycan synthesis, and anti-tumor activity. These findings reveal complex changes in immune cell behavior following stress exposure.
Area of Science:
- Immunology
- Cell Biology
- Physiology
Background:
- Stress can significantly impact immune cell function.
- Macrophages play a critical role in immune responses and coagulation.
- Understanding stress-induced changes in macrophages is crucial for comprehending overall health.
Purpose of the Study:
- To investigate the effects of chronic cold water stress on macrophage function in mice.
- To analyze changes in prothrombinase activity, coagulation factor release, and proteoglycan synthesis.
- To assess the impact of stress on macrophage-mediated tumor cytotoxicity and TNF release.
Main Methods:
- Macrophages were isolated from control mice and mice subjected to repeated cold water stress for 8 or 14 days.
- In vitro assays were used to measure membrane-bound prothrombinase activity, thrombin degradation, and coagulation factor X/Xa release.
- Proteoglycan (PG) and glycosaminoglycan (GAG) synthesis was quantified.
- Macrophage responses to stimulation with phorbol myristate acetate (PMA) and cytokines (IL-1, IL-2) were evaluated.
- Tumor cytotoxicity and tumor necrosis factor (TNF) release were measured.
Main Results:
- Macrophages from stressed mice exhibited increased membrane-bound prothrombinase activity and enhanced release of coagulation factor X/Xa.
- Proteoglycan and glycosaminoglycan synthesis was elevated in macrophages from mice stressed for 8 days.
- Stimulation with PMA and cytokines induced altered PG/GAG synthesis only in macrophages from control mice.
- Tumor cytotoxicity and TNF release were decreased in macrophages from mice stressed for 14 days.
Conclusions:
- Repeated stress exposure alters macrophage function in a complex manner, affecting coagulation, matrix synthesis, and immune effector functions.
- The observed changes suggest a nuanced response rather than simple activation or suppression of macrophages.
- These findings highlight the intricate interplay between stress and the immune system at the cellular level.