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Differential secretion of plasminogen activator activity by postsurgical activated macrophages
Abstract:
Macrophage functions during postsurgical tissue repair include secretion of neutral proteases like plasminogen activator. Accordingly, we studied the differential secretion of plasminogen activator by postsurgical macrophages. Rabbits underwent resection and reanastomosis of their small bowel (three rabbits/time group). Postoperatively (up to 28 days), they underwent a second laparotomy for collection of ascites cells by lavage. Cells were incubated with culture medium containing 10% acid-treated fetal calf serum. After 2 days, the medium was removed (1-2 days media, M1) and replaced for 2 more days (3-4 days media, M2). Plasminogen activator activity of the medium (M1 and M2) was determined using a modified indirect solid-phase radioassay. The specific plasminogen activator activity (plasminogen-dependent-plasminogen-independent activator activity) in M1 was 43 mPU/10(6) cells in nonsurgical control rabbits. Exudative cells on Day 1 had less activity than control, and by Day 5, the activity significantly increased to 290% of control levels, reaching peak value on Day 14 (360%). The specific plasminogen activator activity in M2 was 310 mPU/10(6) cells in nonsurgical control media. Exudative cells on Day 1 had less activity than control, while, on Days 3-7, they were the same as control. By day 10, specific activity significantly increased to peak levels 188% of control and then gradually decreased. Since a marked increase in the number of macrophages parallels the increase in these metabolic activities through postsurgical Day 10, postsurgical activated macrophages appear to play an important role in peritoneal healing.
Insights
Postsurgical macrophages significantly increase plasminogen activator secretion, aiding peritoneal healing. This study tracks this key macrophage function during tissue repair after bowel surgery in rabbits.
Area of Science:
- Cell Biology
- Immunology
- Surgical Research
Background:
- Macrophages are crucial for tissue repair, secreting enzymes like plasminogen activator.
- Understanding macrophage activity post-surgery is vital for optimizing healing.
Purpose of the Study:
- To investigate the differential secretion of plasminogen activator by macrophages following small bowel surgery.
- To analyze the temporal changes in macrophage-derived plasminogen activator activity during postsurgical peritoneal healing.
Main Methods:
- Rabbits underwent small bowel resection and reanastomosis.
- Ascites cells were collected via lavage at various postoperative time points (up to 28 days).
- Plasminogen activator activity in collected cell media was quantified using a radioassay.
Main Results:
- Macrophage plasminogen activator activity was initially lower than controls on Day 1 but increased significantly by Day 5 (290% of control).
- Peak activity was observed on Day 14 (360% of control) in the early media collection (M1).
- Later media collection (M2) showed a significant increase by Day 10 (188% of control), correlating with macrophage numbers.
Conclusions:
- Postsurgical activated macrophages exhibit significantly elevated plasminogen activator secretion.
- The temporal pattern of plasminogen activator release suggests a key role for macrophages in peritoneal healing.
- These findings highlight macrophage-mediated enzymatic activity as a critical component of postsurgical tissue repair.