Yukito Adachi

Pathogenic role of Kupffer cell activation in the reperfusion injury of cold-preserved liver.

The present study was designed to investigate the possible participation of Kupffer cells in the development of reperfusion injury of the cold-stored liver graft. In the cold preservation of Kupffer cells with Euro-Collins solution, the proportion of asialo-GM1-positive cells was significantly increased at 12 and 24 hr of storage, and the TNF alpha-producing activity in these cells was approximately fivefold greater than control. Northern blot analysis demonstrated that TNF alpha mRNA was remarkably elevated in the reperfusion of the cold-preserved liver, although that of the prereperfused graft was only slightly induced. The reperfusion experiments of the cold-stored liver graft showed that addition of anti-TNF alpha antibody to the perfusate suppressed the elevation of the effluent levels of GOT and LDH significantly, and that pretreatment with a Kupffer cell inhibitor, gadolinium chloride, inhibited the increase of these enzymes in the effluents almost completely. Histological study revealed deposition of a fibrinlike substance in the sinusoid and the central veins extensively in the reperfused liver graft, whereas no apparent deposition was observed in the gadolinium-pretreated liver. Thus, the present study showed that Kupffer cells were primed by cold preservation with Euro-Collins solution, and then activated when the reperfusion was done. It seems likely that the Kupffer cell activation induced by cold preservation/reperfusion plays a major role in reperfusion injury with sinusoidal microcirculatory disturbance, and that TNF alpha is responsible for the impairment of the reperfused liver graft.

Enhancement of hepatic macrophages in septic rats and their inhibitory effect on hepatocyte function

In the present study, the function of hepatic macrophages and the modulation of hepatocytes by sepsis-elicited hepatic macrophages were investigated in rats with induced sepsis. The functional state of hepatic macrophages was determined by the following indicators: phagocytic index, protein-synthesizing capacity, and superoxide (O2-) producing capacity. These indices of changes in hepatic macrophages were much higher in rats with sepsis than in healthy controls. Moreover, the activated hepatic macrophages had some biological properties which were different from those of the resident Kupffer cells. It was found that protein synthesis by cultured hepatocytes was inhibited in the co-culture system of hepatocytes and sepsis-elicited hepatic macrophages, and that the supernatant of hepatic macrophages from rats with sepsis also reduced the protein-synthesizing capacity of cultured hepatocytes. Thus, activated hepatic macrophages may play a role in inducing hepatic dysfunction in sepsis.

Depressed function of Kupffer cells in rats with CCl4-induced liver cirrhosis.

SummaryIn the present study, the Kupffer cell function of rats with CCl4-induced liver cirrhosis was tested by analyzing the changes in the host defense system. In rats without liver cirrhosis injected with CCl4 for 3 weeks concomitant with the high opsonic activity the endocytic index was significantly increased. Rats treated for 9 and 13 weeks developed cirrhosis, and their endocytic indices were not increased despite the rise in their opsonic activity. Particularly, the endocytic index of 13-week-treated rats with advanced liver cirrhosis was significantly lower than that of the other groups. The organic distribution of 51Cr-endotoxin injected intravenously exhibited characteristic changes in 9-week- and 13-week-treated rats: decreased hepatic uptake and increased splenic uptake. In contrast, pulmonary uptake was increased in all CCl4-treated rats. The superoxide production by Kupffer cells from 13-week-treated rats was greatly reduced, accompanied by the decreased superoxide dismutase activity of liver homogenate. Thus, results of this study suggest that Kupffer cell dysfunction is one of the main factors affecting host defenses in liver cirrhosis.

Hepatic macrophage malfunction in rats with obstructive jaundice and its biological significance

The present study was designed to investigate the pathophysiology of obstructive jaundice by analyzing the function of hepatic macrophages and their role in immune responses and homeostasis in rats. The phagocytic index, determined by the rate of disappearance of 51Cr-endotoxin from the peripheral blood after intravenous injection, was increased in obstructive jaundice 2 weeks after bile duct ligation. The superoxide production of isolated hepatic macrophages and peripheral blood monocytes, measured by the superoxide dismutase inhibitable ferricytochrome c reduction method, was increased. Prostaglandin E2 release, measured by RIA, was markedly increased in rats with obstructive jaundice, but there was no significant difference in interleukin-1 release between jaundiced and control rats. The flow-cytometric analysis of surface molecules of hepatic macrophages showed decreased expression of interleukin-2 receptor in rats with obstructive jaundice. Thus, the functions of hepatic macrophages in rats with obstructive jaundice were impaired. This malfunction may disturb the immunoregulatory network and metabolism, although the exact implications of the altered function of hepatic macrophages have not yet been clarified.

Enhancement and hepatocyte-modulating effect of chemical mediators and monokines produced by hepatic macrophages in rats with induced sepsis.

SummaryWe investigated the production of chemical mediators by hepatic macrophages from rats with sepsis and the modulation of hepatocyte function by these hepatic macrophages. The chemical mediators we measured were superoxide (O2−), TNF, IL-1, and PGE2. Production of these mediators by hepatic macrophages from rats with sepsis was significantly increased. Furthermore, protein synthesis by cultured hepatocytes was inhibited in a co-culture system of hepatocytes and hepatic macrophages from rats with sepsis, and it was even inhibited by the supernatant of cultured hepatic macrophages from septic rats. These results demonstrate that hepatic macrophages are activated in sepsis and may play a role in inducing hepatic dysfunction in sepsis.

Chemical mediator release and surface marker expression of hepatic macrophages in rats with CCl4-induced liver cirrhosis

The present study was performed to analyze possible functional alterations of hepatic macrophages (HM phi) in rats with carbon tetrachloride (CCl4)-induced liver cirrhosis. HM phi from rats injected with CCl4 for 13 weeks and cultured for 24 hours released less than normal amounts of prostaglandin E2 (PGE2) and tumor necrosis factor (TNF) and very large amounts of interleukin-1 (IL-1). In rats injected with CCl4 for 9 weeks, only PGE2 production was reduced. Interleukin-2 receptor (IL-2R), Ia antigen and asialo GM1 antigen expressions on HM phi from both the 9- and 13-week groups were significantly decreased. IL-2R and Ia antigen expressions showed larger decreases in the 13-week group. Thus, it is concluded that HM phi derived from CCl4-induced cirrhotic livers show a functional alteration in the release of cytokines (except for IL-1) and a decrease in surface marker expression, as cirrhosis advances. These results should provide a basis for further investigation into the host-compromised status in the presence of liver cirrhosis.

Effect of PGE2 on interleukin-1 and superoxide release from primary-cultured human hepatic macrophages

In order to learn more about how human hepatic macrophages function, we analyzed the effect of exogenous PGE2 on the amounts of interleukin-1 (IL-1) and superoxide (O2-) released from primary-cultured human hepatic macrophages (HHM phi). When endogenous PGE2 production was blocked by indomethacin, exogenous PGE2 reduced IL-1 release from HHM phi in a dose-dependent manner, whereas it tended to increase O2- release from HHM phi. These results may suggest the probable contribution of PGE2 in regulating HHM phi mediator release in vivo.

Enhancement of rat hepatic macrophages by treatment with interleukin-2 and streptococcal preparation OK432, with reference to antitumor activity, soluble factor production and Ia expression

SummaryThe effect of biological response modifiers, such as interleukin-2 (IL-2) and streptococcal preparation OK432, on the functions of hepatic macrophages was investigated. The macrophages, even with no exogenous stimulation, produced superoxide anion (O2-) and tumor necrosis factor (TNF), displayed cytotoxicity against K562 cells and cytostasis against P815 cells and expressed immune-region-associated antigen (Ia). IL-2 administered in vitro or in vivo enhanced O2- production by hepatic macrophages and the intravenous injection of OK432 also enhanced O2- production. Furthermore, IL-2 added to the culture medium of hepatic macrophages isolated from OK432-injected rats augmented O2- production even more. The TNF production and Ia expression of the macrophages were also increased by the intravenous injection of OK432. As with O2- production, the cytotoxicity of the cells was enhanced by OK432 injection or by IL-2 added to the culture medium and the combination of OK432 and IL-2 augmented their cytotoxicity even more. Thus, the present study suggested that IL-2 and OK432 induce the augmentation of the antitumor activity of hepatic macrophages, partly as a result of the increase in production of O2- and TNF and Ia expression.

Tumoricidal activity of Kupffer cells augmented by anticancer drugs

The effect of Mitomycin-C (MMC) and Adriamycin (ADM) on the antitumor-associated function of Kupffer cells was examined. MMC and ADM enhanced the production of superoxide by Kupffer cells in cultures at low concentrations likely to occur in clinical use. The expression of interleukin-2 receptor, Ia antigen and asialoGM1 antigen, measured by flowcytometry, was increased by contact with MMC. Growth inhibition of AH130, rat ascites hepatoma, and P815, murine mastocytoma, by Kupffer cells treated with anticancer drugs was greater than that by Kupffer cells alone or anticancer agent alone. These results show that MMC and ADM activate Kupffer cells, leading to synergistic antitumor activity. The results suggest that some anticancer agents act through immunological mechanisms as well as through direct antineoplastic activity.

Superoxide release by primary-cultured human hepatic macrophages and peripheral monocytes from patients with normal and cirrhotic livers

We analysed superoxide anion (O2-) release from primary-cultured human hepatic macrophages (HHM phi) and peripheral blood monocytes (MO) derived from patients with normal and cirrhotic livers. Primary cultured human hepatic macrophages and MO from cirrhotic patients released less O2- than cells from normal patients. Superoxide anion release by HHM phi showed a significant, positive correlation with the serum glutamate pyruvate transaminase (GPT) level, whereas O2- release by MO showed only a weak correlation with the GPT level. In conclusion, a significant reduction in O2- release was observed in HHM phi and MO cultured from cirrhotic patients. Primary-cultured human hepatic macrophages are probably more susceptible to environmental changes within the cirrhotic liver than MO, since they are found locally within the liver and correlate with serum GPT levels.