Lipopolysaccharide down-regulates the thrombomodulin expression of peripheral blood monocytes: effect of serum on thrombomodulin expression in the THP-1 monocytic cell line.
Thrombomodulin has a central role in the regulation of coagulation through its abilities to promote generation of the potent anticoagulant activated protein C. Because little is known about monocyte thrombomodulin expression and its regulatory mechanism by lipopolysaccharide, we investigated the effect of lipopolysaccharide on monocyte's thrombomodulin expression. Lipopolysaccharide reduced the surface thrombomodulin expression of human peripheral blood monocytes in a dose-dependent and time-dependent manner, regardless of the addition of serum. The surface thrombomodulin activity was comparably decreased in monocytes incubated with lipopolysaccharide. Blocking nuclear factor-kappaB by MG132 or aurine tricarboxylic acid effectively inhibited the lipopolysaccharide-induced surface thrombomodulin down-regulation of monocytes. Lipopolysaccharide inactivation by polymyxin B in the supernatants from the lipopolysaccharide-stimulated cultures still reduced the surface thrombomodulin expression of monocytes, suggesting a role for soluble mediators in the down-regulation of thrombomodulin. The lipopolysaccharide-induced thrombomodulin surface expression and the mRNA levels of the monocytic leukemic cell line (THP-1) were decreased in serum-depleted culture, while they were increased in medium containing 10% serum. We conclude that lipopolysaccharide down-regulates the thrombomodulin expression of monocytes and that nuclear factor-kappaB is a critical mediator of the repression of thrombomodulin by lipopolysaccharide. Regulation of the THP-1 thrombomodulin expression by lipopolysaccharide depends on the presence of serum.
Kim
Hyun Kyung
HK
Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea.
Kim
Ji-Eun
JE
Chung
Junho
J
Kim
Young Tae
YT
Kang
Seong-Ho
SH
Han
Kyou-Sup
KS
Cho
Han-Ik
HI
D001773:Blood Cells; D002460:Cell Line; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects*; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology*; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism*; D016328:NF-kappa B / Q000037:antagonists & inhibitors; D012333:RNA, Messenger / Q000032:analysis; D044967:Serum; D018180:Thrombomodulin / Q000235:genetics*
D016895:Culture Media, Serum-Free; D008070:Lipopolysaccharides; D016328:NF-kappa B; D012333:RNA, Messenger; D018180:Thrombomodulin