Hiroshi Kuboi

Effects of the polysaccharide chain of lipopolysaccharide in an experimental massive hepatic cell necrosis model

When a small amount (1 μg) of lipopolysaccharide (LPS) purified from Salmonella minnesota wild, Salmonella minnesota R60, and Salmonella minnesota R345 was intravenously injected into mice 7 days after heat-killed Propionibacterium acnes was intravenously injected, massive hepatic cell necrosis was induced and most of the mice died within 24 hours. However, when LPS from Salmonella minnesota R5 and Salmonella minnesota R7 and lipid A from Salmonella minnesota R595 were administered, the survival rate was much higher and no histological changes in the liver such as necrosis could be seen in any of the mice. In each of the LPS used in this study, the structure of the polysaccharide chain was different, and it decreased in the following order: Salmonella minnesota wild → Salmonella minnesota R60 → Salmonella minnesota R345 → Salmonella minnesota R5 → Salmonella minnesota R7 → Salmonella minnesota R595. This suggested that the polysaccharide chain of LPS played an important role in the induction of massive hepatic cell necrosis in this experimental model.

The protective effect of cyclosporin a on experimentally-induced acute hepatic injury in mice

SummaryWhen heat-killedPropionibacterium acnes (P. acnes) and a small amount of endotoxin lipopolysaccharide (LPS) were intravenously injected into mice at a week’s interval, most of them died of massive hepatic cell necrosis. This experimentally-induced acute liver injury was significantly inhibited by cyclosporin A (CsA), resulting in a remarkable improvement of the survival rate. This protective effect of CsA on acute liver injury was also histopathologically confirmed. To study the mechanism by which CsA protected the mice from fatal hepatic injury, adherent cells prepared from the murine liver 7 days afterP. acnes injection were incubated with LPS in the presence of CsA, and the effect of CsA on the production of the cytotoxic factor from the adherent cells was estimated. As a result, CsA inhibited the activation of liver adherent cells and suppressed the release of the cytotoxic factor.

An experimentally-induced acute hepatic failure model in various strains of mice

SummaryWhen BALB/cAJcl mice are intravenously injected with heat-killedPropionibacterium acnes (P. acnes) followed by an intravenous injection of lipopolysaccharide (LPS) 7 days later, massive necrosis is induced in the liver tissue and most of the mice die within 24 hours of LPS injection. Using this experimental model, acute hepatic failure was induced in various strains of mice and the difference in the response was studied. As a result, as in BALB/cAJcl mice, acut hepatic failure was also induced in BALB/ cAJcl-nu, AKR/J, C3H/HeNJcl, C57BL/6NJcl and DDy mice. However, as an exception, hepatic cell necrosis was hardly seen and the survival rate was remarkable high in C3H/HeJ mice, which genetically do not respond to LPS stimulation. These results indicate that for this experimental induction of acute hepatic failure, macrophages must be activated by the two-step stimulation ofP. acnes and LPS.

Effects of the polysaccharide chain of lipopolysaccharide in an experimental massive hepatic cell necrosis model.

When small amounts (1 microgram) of lipopolysaccharide (LPS) purified from Salmonella minnesota (SM) wild, SM R60 and SM R345 were intravenously injected into mice 7 days after heat-killed Propionibacterium acnes was intravenously injected, massive hepatic cell necrosis was induced and most of the mice died within 24 hours. However, when LPS from SM R345 treated galactosidase, SM R5 and SM R7 and lipid A from SM R595 were administered, the survival rate was much higher and no histological changes of the liver such as necrosis could be seen in any of the mice. In each of the LPS used in this study, the structure of the polysaccharide chain was different and it was shorter in the following order: SM wild----SM R60----SM R345----SM R345 treated with galactosidase----SM R5----SM R7----SM R595. This suggests that the polysaccharide chain of LPS plays an important role in the induction of massive hepatic cell necrosis in this experimental model.

Effects of the polysaccharide chain of lipopolysaccharide in D-galactosamine induced hepatic injury.

D-ガラクトサミン肝細胞障害発生におけるエンドトキシンの関与について検討した.Wistar系雄性ラットをpolymixin Bで処置し,その後にD-ガラクトサミンを投与しても肝細胞障害は誘導できなかった.しかし,同時にlipopolysaccharide (LPS)を投与すると著明な肝細胞障害が誘導できた.次にLPSの糖鎖構造と肝細胞障害の誘導に及ぼす影響について検討した.(1) Salmonella minnesota wild, (2) Salmonella minnesota R60, (3) Salmonella minnesota R345由来のLPS静注群では,ラットの生存率は20%以下であった.それに対して(4) Salmonnella minnesota R5, (5) Salmonella minnesota R7由来のLPSまたは(6) Salmonella minnesota R595由来のlipid Aをそれぞれ静注したラットではほとんど死亡しなかった.以上のことから,D-ガラクトサミン肝細胞障害の発生には大腸の腸内細菌叢,これに由来するエンドトキシン,さらにLPSの多糖鎖が重要な役割を果たすことが示唆された.

Release of leukotriene B4 from rat kupffer cells.

In order to examine the production of leukotriene B4 (LTB4) from Kupffer cells, Kupffer cells isolated from the normal rat liver were incubated with calcium ionophore A23187, opsonized zymosan, or platelet activating factor (PAF), and the amount of LTB4 in the culture supernatant was determined by the combined technique of reverse-phase high-performance liquid chromatography and radioimmunoassay. As a result, when activated in vitro with calcium ionophore A23187, Kupffer cells generated LTB4. When Kupffer cells were stimulated with calcium ionophore after 10-min preincubation with AA861, a selective 5-lipoxygenase inhibitor, the release of LTB4 from Kupffer cells was markedly suppressed. PAF, which is a phospholipid mediator having a wide spectrum of biological activities, significantly enhanced the release of LTB4 from Kupffer cells stimulated with calcium ionophore or opsonized zymosan. Even when the Kupffer cell were not stimulated with calcium ionophore or opsonized zymosan, LTB4 production was significantly increased by PAF. Thus, our studies indicate that Kupffer cells could generate LTB4 as well as polymorphonuclear leukocytes and macrophages. In addition, it is suggested that Kupffer cells may be able to modify inflammatory and immunological events in the liver tissue by the release of LTB4.

The protective effect of prostaglandin E1 on experimentally-induced acute hepatic failure.

Propionibacterium acnes (P.acnes)加熱死菌をマウスに静注し,7日後に少量のグラム陰性菌由来のlipopolysaccharide (LPS)を静注すると,ほとんどのマウスは広範な肝壊死を起こして死亡する.しかし,このような実験的肝障害を誘導する際に,prostaglandin (PG)E1を投与すると,マウスの生存率は高くなり,肝の組織学的変化も著明に改善される.このPGE1の肝障害抑制機構を明らかにするため,著者らは肝障害を誘導する肝粘着性細胞の活性化に及ぼすPG E1の影響を検討するとともに粘着性細胞由来の肝細胞障害因子に対するPG E1の肝細胞防御作用をしらべた.その結果,PG E1は肝粘着性細胞の活性化を抑制して細胞障害因子の遊離を抑制するぼかりでなく,肝細胞に直接作用して肝細胞を障害因子の作用から防御することが明らかとなった.