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Soluble ICAM-1 (sICAM-1) provokes PMN elastase release
C C Barnett1, E E Moore, F A Moore
1Department of Surgery, Denver General Hospital and the University of Colorado Health Sciences Center, USA.
Abstract:
Elevated levels of soluble intercellular adhesion molecule-1 have been shown predictive of post-injury multiple organ failure. We hypothesized that sICAM-1 augments distant organ injury via its affect on the PMN and; thus, have examined neutrophil elastase and superoxide production in response to sICAM-1. To obtain soluble ICAM-1, Chinese Hamster Ovarian (CHO) cells were transfected with human ICAM-1 (cDNA vector CD1.8), lysed and centrifuged at 150,000g for 1 hr; supernatant was passed over an ICAM-1 affinity gradient, eluted with 0.1 mM glycine x HCl, and concentrated using an Amicon Spin-X filter. PMNs were incubated for 1 hr with sICAM-1 at 37 degrees C. Quiescent and PMA-activated PMNs served as negative and positive controls respectively. Elastase activity was measured by the cleavage of methoxy-succinyl-alalyl-alalyl-prolyl-valyl-p-nitroanilide. Superoxide production was determined by superoxide dismutase inhibitive ferricytochrome C reduction over a 5-60 min incubation. PMN incubation with sICAM-1 provoked marked increase in elastase release 10.43 +/- 2.90 (10(-6) U/hr) compared to control 1.64 +/- 0.57, and was equivalent to PMA-activated PMN elastase release 11.60 +/- 1.50 (10(-6) U/hr). In contrast, sICAM-1 alone did not promote spontaneous PMN superoxide production beyond buffer treated PMNs (0.25 +/- 0.09 nmole/2.5 x 10(5) PMN/min). In sum, sICAM-1 stimulates PMN elastase release in vitro. Clinically, this may represent a mechanism by which sICAM-1 participates in the genesis of post-injury multiple organ failure.
Insights
Soluble intercellular adhesion molecule-1 (sICAM-1) significantly increases neutrophil elastase release in vitro. This finding suggests a potential mechanism linking sICAM-1 to the development of multiple organ failure after injury.
Area of Science:
- Biochemistry
- Immunology
- Cell Biology
Background:
- Elevated soluble intercellular adhesion molecule-1 (sICAM-1) levels are linked to post-injury multiple organ failure.
- The precise mechanism by which sICAM-1 contributes to organ injury is not fully understood.
- Neutrophil (PMN) activation, involving elastase and superoxide release, is implicated in inflammatory processes and organ damage.
Purpose of the Study:
- To investigate the hypothesis that sICAM-1 augments distant organ injury by affecting neutrophils.
- To examine the effect of sICAM-1 on neutrophil elastase and superoxide production in vitro.
Main Methods:
- Soluble ICAM-1 was isolated from transfected Chinese Hamster Ovarian (CHO) cells.
- Neutrophils were incubated with sICAM-1, and elastase activity was measured using a specific substrate.
- Superoxide production was quantified by measuring ferricytochrome C reduction.
Main Results:
- Incubation with sICAM-1 significantly increased neutrophil elastase release compared to controls.
- The elastase release induced by sICAM-1 was comparable to that of PMA-activated neutrophils.
- sICAM-1 alone did not stimulate spontaneous neutrophil superoxide production.
Conclusions:
- Soluble ICAM-1 directly stimulates neutrophil elastase release in an in vitro setting.
- This action of sICAM-1 on neutrophils may represent a key mechanism in the pathogenesis of post-injury multiple organ failure.