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Relative contribution of endothelial cell and polymorphonuclear neutrophil activation in their interactions in
1Department of Surgery, McGill University, Royal Victoria Hospital, Montreal, Quebec.
Objective:
To examine the relative contribution of polymorphonuclear neutrophil (PMN) vs endothelial cell (EC) activation on the adherence and subsequent killing of ECs by PMNs.
Design:
In vitro comparative studies of PMN-EC adherence and cytotoxicity.
Setting:
Research laboratory and the surgical intensive care unit of a tertiary-level university hospital.
Patients:
Patients with systemic inflammatory response syndrome admitted to the surgical intensive care unit and hospitalized preoperative noninfected surgical patients.
Intervention:
None.
Methods:
Polymorphonuclear neutrophils were isolated from 21 healthy volunteers, 22 preoperative patients, and 30 patients from the surgical intensive care unit with systemic inflammatory response syndrome. The PMNs were activated with lipopolysaccharide, 100 ng/mL (Escherichia coli 0111:b4), for 40 minutes at 37 degrees C before the adherence and cytotoxicity assays. Human umbilical vein endothelial monolayers were stimulated with tumor necrosis factor alpha, 25 ng/mL, and interleukin 1 beta, 15 U/mL, for 3 hours. The PMNs or EC cells were labeled with sodium chromate Cr 51 and used in a standard adherence or killing assay as required.
Results:
Control and preoperative patient PMN treatment with lipopolysaccharide produced a modest increase in adherence. The PMNs from patients with systemic inflammatory response syndrome showed moderately increased human umbilical vein endothelial cell adherence, and this could not be augmented further with lipopolysaccharide stimulation. There was a marked increase in PMN adherence to EC after EC activation in all study groups (P < .001). Similar to the adherence data, human umbilical vein endothelial cell cytotoxicity was significantly increased in all groups after human umbilical vein endothelial cell activation (P < .01) but not after PMN stimulation with lipopolysaccharide.
Conclusion:
These data suggest that stimulation of ECs is far more important in producing increased adherence and cytotoxicity of EC than PMN stimulation with lipopolysaccharide in all study groups. Therapeutic efforts in patients with systemic inflammatory response syndrome should be focused on the EC.
Insights
Endothelial cell activation significantly increases polymorphonuclear neutrophil adherence and cytotoxicity, suggesting ECs are key targets for therapy in systemic inflammatory response syndrome. PMN stimulation alone had minimal impact.
Area of Science:
- Immunology
- Cell Biology
- Critical Care Medicine
Background:
- Systemic inflammatory response syndrome (SIRS) involves complex immune cell interactions.
- Polymorphonuclear neutrophils (PMNs) and endothelial cells (ECs) play critical roles in inflammation and tissue damage.
Purpose of the Study:
- To compare the roles of PMN activation versus EC activation in PMN-EC adherence and EC cytotoxicity.
- To determine the primary driver of increased PMN-EC interactions in SIRS.
Main Methods:
- In vitro comparative study using isolated PMNs and human umbilical vein ECs.
- PMNs activated with lipopolysaccharide; ECs stimulated with TNF-α and IL-1β.
- Adherence and cytotoxicity assays using 51Cr-labeled cells.
Main Results:
- EC activation markedly increased PMN adherence and EC cytotoxicity across all study groups.
- PMN activation with lipopolysaccharide showed only a modest increase in adherence.
- PMNs from SIRS patients exhibited moderately increased adherence, not further enhanced by PMN stimulation.
Conclusions:
- Endothelial cell activation is the predominant factor driving PMN adherence and EC cytotoxicity.
- Therapeutic strategies for SIRS should prioritize targeting EC activation.