Bacterial lipopolysaccharide decreases thrombomodulin expression in the sinusoidal endothelial cells of rats -- a possible mechanism of intrasinusoidal microthrombus formation and liver dysfunction.
OBJECTIVE
To elucidate the mechanism of liver dysfunction occurring in patients with sepsis, we evaluated the effect of bacterial lipopolysaccharide (LPS) on the expression of thrombomodulin (TM) in rat sinusoidal endothelial cells (SECs) and the therapeutic efficacy of exogenous recombinant TM.


METHODS
We induced endotoxemia in rats by bolus intraperitoneal injection of LPS. TM antigen levels within tissues were assessed by immunohistochemistry. We measured TM in cultured SECs by enzyme immunoassay, functional analysis and real-time polymerase chain reaction (PCR).


RESULTS
TM antigen and activity levels were significantly decreased in SECs isolated from LPS-treated rats after 3 and 6 h treatment, and recovered after 12 h treatment, correlating with immunohistochemical observations. In contrast, TM messenger RNA was decreased after 6 and 12 h treatment, and slightly recovered after 24 h treatment. TM expression in cultured SECs isolated from normal rats was also reduced after treatment with LPS and tumor necrosis factor (TNF)-alpha in vitro. The increased levels of serum fibrin degradation products (FDP), fibrin deposition within liver sinusoids, injury of SECs and liver dysfunction induced by LPS in our rat model was improved by recombinant TM treatment.


CONCLUSIONS
Decreased TM expression in SECs of LPS-treated rats may result in intrasinusoidal microthrombus formation and subsequent liver dysfunction during sepsis.
Kume
Masane
M
Department of Molecular Pathobiology, Mie University School of Medicine, Tsu-city, Mie 514-8507, Japan.
Hayashi
Tatsuya
T
Yuasa
Hiroyuki
H
Tanaka
Hitoshi
H
Nishioka
Junji
J
Ido
Masaru
M
Gabazza
Esteban C
EC
Kawarada
Yoshifumi
Y
Suzuki
Koji
K
D000818:Animals; D016207:Cytokines / Q000097:blood; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D004926:Escherichia coli; D007150:Immunohistochemistry; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008102:Liver Circulation; D008107:Liver Diseases / Q000209:etiology; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000494:pharmacology; D018180:Thrombomodulin / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D013927:Thrombosis / Q000209:etiology
D016207:Cytokines; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D011994:Recombinant Proteins; D018180:Thrombomodulin; D012313:RNA