Bikunin suppresses lipopolysaccharide-induced lethality through down-regulation of tumor necrosis factor- alpha and interleukin-1 beta in macrophages.
BACKGROUND
Lipopolysaccharide (LPS) is the primary mediator of gram-negative sepsis; it induces the production of macrophage-derived cytokines. It has been shown that bikunin, a Kunitz-type protease inhibitor, inhibits LPS-induced cytokine expression.


METHODS
To explore the role of bikunin, bikunin knockout (Bik(-/-)) mice were used for in vitro cytokine experiments and in vivo animal models.


RESULTS
We show that a higher level of LPS-mediated death was induced in Bik(-/-), compared with wild-type (wt), mice; the administration of bikunin caused a significant reduction in LPS-induced lethality; LPS significantly increased tumor necrosis factor (TNF)- alpha and interleukin-1 beta levels in Bik(-/-), relative to wt, mice after LPS challenge; concomitant administration of bikunin inhibited the LPS-induced plasma levels of these cytokines; bikunin suppressed the LPS-induced up-regulation of cytokine expression through the suppression of the phosphorylation of ERK1/2, JNK, and p38 in macrophages; and LPS-induced up-regulation of TNF- alpha expression was not enhanced in Bik(-/-) macrophages without endogenous bikunin.


CONCLUSIONS
These data allow us to speculate that the increased sensitivity of Bik(-/-) mice to LPS-induced death in vivo is due to a lack of circulating bikunin in plasma. Bikunin may play a role as a potent anti-inflammatory agent.
Wakahara
Kiyoshi
K
NetForce Co., Ltd., Aichi, Japan.
Kobayashi
Hiroshi
H
Yagyu
Tatsuo
T
Matsuzaki
Hidenori
H
Kondo
Toshiharu
T
Kurita
Noriyuki
N
Sekino
Hideo
H
Inagaki
Kiyokazu
K
Suzuki
Mika
M
Kanayama
Naohiro
N
Terao
Toshihiko
T
D000818:Animals; D002478:Cells, Cultured; D015536:Down-Regulation; D007249:Inflammation / Q000188:drug therapy / Q000401:mortality*; D007375:Interleukin-1 / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008262:Macrophage Activation; D017737:Macrophages, Peritoneal / Q000276:immunology* / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000008:administration & dosage / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D015842:Serine Proteinase Inhibitors / Q000008:administration & dosage / Q000235:genetics / Q000494:pharmacology; D014360:Trypsin Inhibitor, Kunitz Soybean / Q000008:administration & dosage / Q000235:genetics / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D007375:Interleukin-1; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; C109148:SPINT2 protein, human; D015842:Serine Proteinase Inhibitors; D014409:Tumor Necrosis Factor-alpha; D014360:Trypsin Inhibitor, Kunitz Soybean