Protective effects of a selective neutrophil elastase inhibitor (sivelestat) on lipopolysaccharide-induced acute dysfunction of the pulmonary microcirculation.
OBJECTIVE
The purpose of this study was to evaluate the effect of a neutrophil elastase inhibitor, sivelestat, on lipopolysaccharide-induced acute lung injury through analysis of hemodynamic changes in the pulmonary microcirculation.


METHODS
Randomized animal study.


METHODS
Medical school laboratory.


METHODS
Twenty-seven Wistar rats (15 rats for microspectroscopic observations, 12 rats for measurements of neutrophil elastase activity and wet-to-dry ratio).


METHODS
Thoracosternotomy was performed on male Wistar rats under continuous anesthesia and mechanical ventilation. Rats were divided into three groups (n = 5 each groups) on the basis of the reagent used: lipopolysaccharide group (100 microg/kg lipopolysaccharide intravenously), sivelestat group (10 mg/kg sivelestat; 100 microg/kg lipopolysaccharide intravenously), and control group (saline only, intravenously).


RESULTS
We measured morphologic changes and hemodynamic variables, including tissue blood flow, erythrocyte velocity, erythrocyte count, thickness of interalveolar septa, and leukocyte adhesion in the pulmonary microcirculation, with a video-rate (33 msec/frame) dual-spot microspectroscopy system (DSMSS) and a laser-Doppler flowmeter. Blood-free wet-to-dry ratio and neutrophil elastase activity in bronchoalveolar lavage fluid, serum, and supernatant of lung homogenate were measured in another set of experiments (n = 4 for each group). Sixty minutes after lipopolysaccharide administration, severe thickening of the interalveolar septa was observed in the lipopolysaccharide but not the sivelestat group. In the lipopolysaccharide group, DSMSS measurements of erythrocyte velocity and hemoglobin oxygenation in single capillaries were decreased significantly (vs. control p < .05, vs. sivelestat p < .01), whereas tissue blood flow and erythrocyte velocity measurements from laser-Doppler flowmeter were increased significantly (vs. control p < .05, vs. sivelestat p < .01). The number of adherent leukocytes was increased significantly in the lipopolysaccharide group at 30, 45, and 60 mins after lipopolysaccharide administration (vs. control p < .01, vs. sivelestat p < .05). The number of adherent leukocytes did not increase in the sivelestat group. The wet-to-dry ratio was significantly higher in the lipopolysaccharide group than in control (p < .05) and sivelestat (p < .05) groups. Neutrophil elastase activities in the bronchoalveolar lavage fluid, serum, and lung tissue were all significantly lower in the sivelestat group than in the lipopolysaccharide group (p < .05).


CONCLUSIONS
Lipopolysaccharide induces leukocyte adhesion in the pulmonary microcirculation, resulting in decreased tissue hemoglobin oxygen and alveolar and interstitial edema. The selective neutrophil elastase inhibitor sivelestat reduces neutrophil elastase activity and attenuates acute changes in the pulmonary microcirculation.
Inoue
Yoshiaki
Y
Department of Traumatology and Acute Critical Medicine, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
Seiyama
Akitoshi
A
Tanaka
Hiroshi
H
Ukai
Isao
I
Akimau
Pavel
P
Nishino
Masato
M
Shimazu
Takeshi
T
Sugimoto
Hisashi
H
D000704:Analysis of Variance; D000818:Animals; D002448:Cell Adhesion; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology; D006439:Hemodynamics; D019272:Leukocyte Elastase / Q000037:antagonists & inhibitors*; D007962:Leukocytes; D008070:Lipopolysaccharides; D008297:Male; D008833:Microcirculation; D008859:Microscopy, Polarization / Q000379:methods; D018715:Microscopy, Video; D015591:Microspectrophotometry / Q000379:methods; D011652:Pulmonary Circulation / Q000187:drug effects*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D012128:Respiratory Distress Syndrome / Q000188:drug therapy* / Q000503:physiopathology; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology*; D013449:Sulfonamides / Q000494:pharmacology*
D008070:Lipopolysaccharides; D015842:Serine Proteinase Inhibitors; D013449:Sulfonamides; C069195:sivelestat; D019272:Leukocyte Elastase; D005998:Glycine