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Induction of prostaglandin production by hyperthermia in murine peritoneal exudate macrophages
Abstract:
In response to inflammatory stimuli, macrophages synthesize and secrete prostaglandins (PGE) along with other potent inflammatory mediators. We have studied the effect of hyperthermia on the production of PGE by murine mononuclear phagocytes. Exposure to high temperature induced PGE production by cultured C3H/HeJ exudate macrophages in a time- and temperature-dependent manner. Increase in PGE production was detected when macrophages were treated at 41 degrees C and above for 1 h with a much greater increase at 42 and 43 degrees C. The secretion of PGE into culture supernatants by heat-treated macrophages reached a maximum approximately 24 h after heat treatment. The production of PGE by macrophages after hyperthermia was inhibited either by the addition of 5 X 10(-7) M indomethacin or by the subsequent incubation at 4 degrees C, suggesting that the elevated PGE production by macrophages is mediated through the activation of cyclooxygenase. Heat treatment under the same conditions failed to stimulate the production of PGE by either a human monocyte-like tumor cell line (U-937) or a mouse fibroblast cell line (L-929).
Insights
Hyperthermia, or high temperature, significantly increases prostaglandin E (PGE) production in mouse macrophages. This heat-induced PGE release is mediated by cyclooxygenase activation.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Macrophages are key immune cells involved in inflammatory responses.
- Prostaglandin E (PGE) is a potent inflammatory mediator synthesized by macrophages.
- Understanding cellular responses to thermal stress is crucial in inflammation research.
Purpose of the Study:
- To investigate the impact of hyperthermia on PGE production in macrophages.
- To determine the temperature and time dependency of hyperthermia-induced PGE synthesis.
- To elucidate the mechanism underlying heat-induced PGE production.
Main Methods:
- Cultured C3H/HeJ exudate macrophages were exposed to varying temperatures (41-43°C) for 1 hour.
- PGE levels in culture supernatants were measured over a 24-hour period post-treatment.
- Experiments included the use of indomethacin (a cyclooxygenase inhibitor) and cold incubation (4°C).
- Human U-937 and mouse L-929 cell lines were used as controls.
Main Results:
- Hyperthermia induced a time- and temperature-dependent increase in PGE production by macrophages.
- Significant PGE elevation was observed at 41°C and above, with maximal production at 42-43°C.
- Peak PGE secretion occurred approximately 24 hours after heat exposure.
- Indomethacin and cold incubation inhibited heat-induced PGE production.
- No significant PGE induction was observed in U-937 or L-929 cell lines under similar conditions.
Conclusions:
- Hyperthermia stimulates PGE production in murine macrophages.
- The elevated PGE production is mediated by the activation of cyclooxygenase.
- Macrophages exhibit a specific sensitivity to hyperthermia-induced inflammatory mediator release, unlike other cell types.