Itsuro Ogata

Provocation of massive hepatic necrosis by endotoxin after partial hepatectomy in rats

When rats received endotoxin 48 hours after two-thirds liver resection, 50% of them died within 12 hours with massive hepatic necrosis at a dose that did not affect sham-operated rats. In the hepatic sinusoids, fibrin deposition and endothelial cell destruction occurred 5 hours after endotoxin administration. When antithrombin III concentrate was infused concomitantly with endotoxin administration, all rats survived 12 hours, and the extent of hepatic necrosis and the deranged serum glutamic pyruvic transaminase values were significantly attenuated at 5 hours compared with those in the control rats. Similar improvements in the incidence of mortality and liver injury were observed after treatment with gum arabic before hepatectomy. The stimulatory state of Kupffer cells based on the ability to produce superoxide anions estimated by formazan deposition after liver perfusion with nitro blue tetrazolium and phorbol myristate acetate was increased between 24 and 72 hours after operation. This increase disappeared after gum arabic treatment. It is concluded that massive hepatic necrosis can occur as a result of sinusoidal fibrin deposition provoked by endotoxin in partially hepatectomized rats. Activated Kupffer cells may contribute to this provocation.

Sinusoidal endothelial cell damage by activated macrophages in rat liver necrosis

BACKGROUND Massive hepatic necrosis caused by fibrin deposition in the hepatic sinusoids develops with hepatic macrophage activation in rats given endotoxin after administration of heat-killed Corynebacterium parvum. Targeted cells of such macrophages were investigated. METHODS In C. parvum-treated rats, the pathological appearance of liver cells was serially measured in serum following endotoxin administration and compared with the appearance in the perfusate during closed liver perfusion with endotoxin. RESULTS Serum activities of tumor necrosis factor, purine nucleoside phosphorylase present in both hepatocytes and sinusoidal endothelial cells, and levels of alanine aminotransferase were higher after 30 minutes, 1 hour, and 3 hours, respectively. Pretreatment of rats with gadolinium chloride, an inhibitor of macrophage function, reduced this liver injury. Although alanine aminotransferase activity remained almost unchanged in the liver perfusate, purine nucleoside phosphorylase activity increased. This increase was reduced when rats were pretreated with gadolinium chloride. There was sinusoidal endothelial cell damage around hepatic macrophages in the liver perfused with endotoxin. CONCLUSIONS Activated hepatic macrophages may cause sinusoidal endothelial cell damage leading to hepatocyte necrosis in rats given C. parvum and endotoxin.

Transforming Growth Factor α Levels in Liver and Blood Correlate Better than Hepatocyte Growth Factor with Hepatocyte Proliferation during Liver Regeneration

Transforming growth factor α (TGFα) and hepatocyte growth factor (HGF) are mitogens for hepatocytes in vitro and in vivo , produced by hepatocytes or nonparenchymal cells such as stellate cells in the liver. It is still uncertain whether TGFα and HGF are essential for liver regeneration. To assess the role of these growth factors in liver regeneration, their circulating and hepatic levels were studied in various rat models of liver regeneration. Hepatic and plasma HGF levels were increased with increased number of mitotic hepatocytes in rats after partial hepatectomy or carbon tetrachloride intoxication. However, hepatic HGF levels were decreased despite an increased number of mitotic hepatocytes and increased or unchanged plasma HGF levels in rats given phenobarbital and in rats after dimethylnitrosamine intoxication, which can induce hepatic necrosis after apoptosis of hepatic stellate cells. In contrast, hepatic and serum TGFα levels were increased in all of the models. In sham-operated rats with no increased number of mitotic hepatocytes, hepatic and circulating levels of HGF were increased, whereas those levels of TGFα were unchanged. The results indicate that TGFα levels in liver and blood more closely correlate with hepatocyte mitogenesis than HGF levels.

Benefit of Transcatheter Arterial Embolization for Ruptured Hepatocellular Carcinoma Complicating Liver Cirrhosis

In 6 patients with spontaneous rupture of hepatocellular carcinoma complicating liver cirrhosis, but with no occlusion of the main portal trunk, transcatheter arterial embolization was performed within 7 days of the rupture. All 6 patients were thought to be inoperable because of shock state or severe hepatic dysfunction. In all 6 patients, the progressive decrease in the hematocrit ceased soon after the embolization. Five patients survived for 31-168 days after the embolization; 1 patient who developed septicemia died 10 days later. We conclude that transcatheter arterial embolization is beneficial as a procedure of first choice for ruptured hepatocellular carcinoma when the portal blood flow is maintained.

Intravascular coagulation in the development of massive hepatic necrosis induced by Corynebacterium parvum and endotoxin in rats

When Escherichia coli endotoxin was intravenously injected into rats given killed Corynebacterium parvum 6 days previously, fibrin deposition and endothelial cell injury occurred in hepatic sinusoids at 1.5 h and were intensified thereafter. Serum alanine aminotransferase values were increased along with prothrombin time and decreased plasma levels of antithrombin III and coagulation factor VIII:C at 5 h. Antithrombin III concentrate (plus heparin) or superoxide dismutase infused concurrently with injection of endotoxin significantly attenuated the derangements of these variables and the histologic extent of liver injury at 5 h. Intravascular coagulation, probably developing through the action of superoxide anion, may contribute to the development of massive hepatic necrosis induced by C. parvum and endotoxin in rats.

Transcatheter arterial embolization for hepatocellular carcinoma. Benefits and limitations for unresectable cases with liver cirrhosis evaluated by comparison with other conservative treatments

Transcatheter arterial embolization (TAE) for unresectable hepatocellular carcinoma (HCC) was performed in cirrhotic patients with nonoccluded main portal trunk and total bilirubin levels less than 5 mg/dl. In 48 patients with tumor response to TAE, its benefit was evaluated by comparing their survival with that in 28 patients after conservative treatments, matched by clinical data. In TAE‐treated patients, tumor findings on computerized tomography and angiogram were significantly different between those dying within 3 months and those surviving over 18 months. In cases of tumors occluding the first‐ or second‐order portal branches or occupying more than 20% of the liver, or relatively hypovascular tumors with unclear boundaries, survival was not different between TAE‐ and non‐TAE‐treated patients, whereas it was significantly improved by TAE in cases without these findings. These results suggest that TAE is beneficial in cases of unresectable HCC complicating liver cirrhosis, but its benefit is limited under certain conditions.

Functional diversity between Rho-kinase- and MLCK-mediated cytoskeletal actions in a myofibroblast-like hepatic stellate cell line.

Using a rat myofibroblast-like hepatic stellate cell line, we studied the actomyosin-based cytoskeletal actions mediated by Rho-kinase and/or myosin light chain kinase (MLCK). Calmodulin/MLCK inhibitors W-7 and ML-7 attenuated cell migration dose-relatedly at concentrations from 10(-6) to 10(-4)M and collagen gel-contraction by the cells at 10(-4)M, respectively. Rho-kinase inhibitors Y-27632 and HA1077 attenuated the gel-contraction at concentrations from 10(-6) to 10(-4) M, respectively. These Rho-kinase inhibitors attenuated cell migration at 10(-7)M but enhanced the migration at 10(-4)M, respectively. They altered cell morphology showing prominent peripheral actin bundles and sparse central stress fibers, in comparison with the calmodulin/MLCK inhibitors. Both ML-7 and Y-27632 attenuated phosphorylation of myosin regulatory light chain and cell attachment to extracellular substrate. ML-7 attenuated the activation of GTP-binding protein Rac, while Y-27632 did not. These findings suggest that the actomyosin-based cytoskeletal actions can be functionally diverse depending on the Rho-kinase-mediated pathway and the MLCK-mediated pathway.

The Mitogenic Activity of Hepatocyte Growth Factor on Rat Hepatocytes Is Dependent upon Endogenous Transforming Growth Factor-α

Both transforming growth factor-alpha (TGF-alpha) and hepatocyte growth factor (HGF) induce DNA synthesis in hepatocytes in vitro and in vivo. Hepatic and circulating levels of HGF have been reported to increase before an increase in TGF-alpha levels in several rat models of liver regeneration. In addition, serum TGF-alpha levels increase after an increase in serum HGF levels in patients with either partial hepatectomy or acute hepatitis. In this study, we investigate the significance of TGF-alpha in hepatocyte proliferation. TGF-alpha contents and DNA synthesis in cultured rat hepatocytes increased in response to HGF addition to the culture medium in a dose-related manner. These increases were suppressed by the addition of anti-sense TGF-alpha mRNA oligonucleotide. Furthermore, the addition of anti-TGF-alpha rabbit IgG suppressed the increase in DNA synthesis. When the anti-TGF-alpha antibody was administered to rats after partial hepatectomy, the number of mitotic hepatocytes was reduced in comparison to rats treated with normal rabbit IgG. These results were observed even though hepatic HGF levels were increased equally in rats given either anti-TGF-alpha antibody or normal rabbit IgG. Our results suggest that HGF stimulates TGF-alpha production in rat hepatocytes, and that the mitogenic activity of HGF depends on endogenous TGF-alpha activity.

Blood coagulation equilibrium in rat liver microcirculation as evaluated by endothelial cell thrombomodulin and macrophage tissue factor

The regulatory mechanisms of microcirculation might differ in the liver from other organs, because macrophages are resident in the hepatic sinusoids and sinusoidal endothelial cells are unique in shape and function. Thrombomodulin expression in endothelial cells and tissue factor activity in isolated macrophages were studied in the liver and lung of rats. In normal rats, the thrombomodulin expression was minimal in hepatic sinusoids, but prominent in pulmonary capillaries, while the tissue factor activity in the presence of endotoxin was higher in pulmonary macrophages than in Kupffer cells, although the levels in the absence of endotoxin were comparable in both cells. The tissue factor activity in hepatic macrophages was increased after priming of the cells with Corynebacterium parvum or after induction of liver necrosis or cirrhosis with carbon tetrachloride. In the necrotic or cirrhotic liver, increased thrombomodulin expression was seen along capillaries extending in necrotic areas and regenerating nodules, but this increase was minimal in the Corynebacterium parvum-treated rat liver. Blood coagulation equilibrium in microcirculation regulated by endothelial cells and macrophages may differ between the liver and lung. Such equilibrium in the liver may vary depending on pathological status.

Gut-derived substances in activation of hepatic macrophages after partial hepatectomy in rats

When liver perfusion with nitro blue tetrazolium and phorbol myristate acetate was performed in rats 24 h after two-thirds liver resection, there were marked deposits of formazan converted from nitro blue tetrazolium in hepatic macrophages throughout the liver, indicating macrophage activity. The extent of the deposits was significantly reduced when perfusion was performed following oral administration of polymyxin B sulfate, a non-absorbable bacteriocidal agent against gram-negative bacilli which can also bind endotoxin lipopolysaccharides. Polymyxin B sulfate administration also attenuated the derangements of SGPT and the histological liver injury provoked by endotoxin administration after partial hepatectomy. These results suggests that gut-derived substances sensitive to polymyxin B sulfate may contribute to activation of hepatic macrophages after partial hepatectomy in rats.