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Modulation of postsurgical macrophage function by early postsurgical polymorphonuclear leukocytes
S Kuraoka1, J D Campeau, R M Nakamura
1Livingston Reproductive Biology Laboratory, Department of Obstetrics and Gynecology, University of Souther California School of Medicine, Los Angeles 90033.
Abstract:
Surgical trauma to the peritoneum, in the absence of infection, elicits a rapid and transient influx of polymorphonuclear leukocytes (PMNs) into the peritoneal cavity prior to the accumulation of macrophages. The aim of this study was to characterize the effects of these PMNs on macrophage function in the early postsurgical period. Rabbits underwent intestinal reanastomosis and peritoneal exudate cells were collected at various times after surgery. Macrophage-enriched preparations were incubated with spent media from cultures of PMNs obtained at the corresponding times after surgery. Superoxide anion (O2-) release by macrophages in response to phorbol myristate acetate was determined by cytochrome c reduction. Fibrinolytic and protease inhibitory activities in macrophage-spent media were also evaluated. The release of O2- had already increased at 2 hr, reached peak levels at 6 hr, and decreased by 24 hr after surgery. Spent media from PMNs harvested 6 hr after surgery suppressed, whereas spent media from postsurgical 12- or 24-hr PMNs increased O2- release from macrophages harvested at 6 and 12 hr after surgery. PMN-spent media had no effect on the secretion of plasminogen activator (PA) from macrophages harvested within 12 hr after surgery. In contrast, PA activity in the spent media from macrophages harvested 24 hr after surgery was elevated after exposure to PMN-spent media. PA inhibitory activity was reduced in macrophage-spent media at 2 hr after surgery and increased by 24 hr, while PMN-spent media had no effect on the level of PA inhibitory activity. Thus, soluble factors secreted into the culture medium by PMNs modulate macrophage function as soon as 6-12 hr after surgery.
Insights
Surgical trauma triggers polymorphonuclear leukocytes (PMNs) that modulate macrophage function early post-surgery. PMN-secreted factors influence macrophage superoxide release and plasminogen activator activity, impacting peritoneal healing.
Area of Science:
- Immunology
- Surgical Inflammation
Background:
- Surgical trauma induces peritoneal polymorphonuclear leukocytes (PMNs) before macrophage accumulation.
- Understanding early immune cell interactions is crucial for postsurgical recovery.
Purpose of the Study:
- To investigate the impact of early postsurgical PMNs on macrophage function.
- To characterize the effects of PMN-secreted factors on macrophage activity.
Main Methods:
- Rabbits underwent intestinal reanastomosis; peritoneal exudate cells were collected.
- Macrophage-enriched cells were incubated with PMN-conditioned media.
- Superoxide anion release, fibrinolytic, and protease inhibitory activities were assessed.
Main Results:
- PMN-conditioned media modulated macrophage superoxide anion release in a time-dependent manner.
- Early PMN media suppressed, while later PMN media enhanced, macrophage superoxide release.
- PMN factors influenced plasminogen activator activity in later-harvested macrophages.
Conclusions:
- Soluble factors secreted by PMNs significantly modulate macrophage function post-surgery.
- These interactions occur as early as 6-12 hours after surgical insult.
- PMN-derived factors play a key role in the early inflammatory response to surgical trauma.