anti-Fas Antibody-induced Hepatitis Research Articles

Chemical Aspects of Coumarin Compounds for the Prevention of Hepatocellular Carcinomas

The normalization of plasma alanine aminotransferase (ALT) has been proved to be a strategy for preventing the development of hepatocellular carcinoma (HCC) in hepatitis C virus (HCV)-infection. Glycyrrhizin, a plant medicine, normalizes plasma ALT and prevents HCC. However, glycyrrhizin is administered intravenously and thereby chemical which is effective on oral administration is required. Coumarin compounds are active components of herbs used for the treatment of various diseases. The ability of coumarin compounds to lower plasma ALT were examined using mice concanavalin A-induced hepatitis and mice anti-Fas antibody-induced hepatitis. Furanocoumarins pd-Ia, pd-II and pd-III lower plasma ALT, but they are large molecules that are hardly absorbed on oral administration. Furocoumarin effectively lowers plasma ALT, but the safety range between the effective and toxic dosages is narrow. In contrast, osthole, a simple coumarin, causes strong reduction of plasma ALT and also inhibits caspase-3 activation. Furthermore, this chemical is quite safe upon large dose administration. In the structure of osthole, the methoxy group at position-7 and the 3-methyl-2-butenyl group at position-8 were elucidated to be essential for the beneficial effect of this chemical. We conclude that osthole will become a leading chemical for synthesizing a compound which prevents HCC on oral administration.

Osthole prevents anti-Fas antibody-induced hepatitis in mice by affecting the caspase-3-mediated apoptotic pathway

Fas (Apo-1/CD95) ligand, which is a type II membrane protein, is a major inducer of apoptosis. Osthole is a coumarin derivative present in medicinal plants. The effect of osthole on hepatitis induced by anti-Fas antibody in mice was studied. Pretreatment of mice with osthole (10, 50, and 100 mg/kg, i.p.) prevented the elevation of plasma alanine aminotransferase (ALT) caused by anti-Fas antibody (175 μg/kg, i.v.). Administration of osthole to mice even at a dose of 10 mg/kg significantly inhibited of anti-Fas antibody-induced elevation of plasma ALT. Capase-3 is a cysteine protease, and treatment of mice with anti-Fas antibody caused an elevation of caspase-3 activity at 3.5 and 6 hr. Pretreatment of mice with osthole (100 mg/kg, i.p.) inhibited the elevation of caspase-3 activity caused by anti-Fas antibody. However, the addition of osthole (up to 10 −4 M) to a liver cytosol fraction isolated from mice treated with anti-Fas antibody did not inhibit caspase-3 activity in vitro. Thus, treatment of mice with osthole inhibited caspase-3 activity by an effect upstream of caspase-3 activation. The livers of mice treated with anti-Fas antibody contained apoptotic and dead cells; osthole attenuated the development of this apoptosis and cell death. The present results show that osthole prevented anti-Fas antibody-induced hepatitis by inhibiting the Fas-mediated apoptotic pathway.

Prevention of concanavalin A-induced mice hepatitis by molsidomine.

Molsidomine is effective in reducing portal hypertension in cirrhosis, but its effect on hepatitis is not known. In the present study, the effect of molsidomine on hepatitis was examined using mouse concanavalin A (Con A)-induced hepatitis and mouse anti-Fas antibody-induced hepatitis. Treatment of mice with Con A caused elevation of plasma alanine aminotransferase (ALT) at 8 and 24 h (n=4). Pretreatment of mice with molsidomine (3, 10, 30 and 100 mg/kg, i.p.) prevented Con A-induced hepatitis. Treatment of mice with anti-Fas antibody (150 microg/kg, i.v.) caused elevation of plasma ALT at 3.5 h. Pretreatment mice with molsidomine (10 mg/kg, i.p.) showed only 47% inhibition of anti-Fas antibody caused elevation of plasma ALT. The present results showed effectiveness of molsidomine in preventing Con A-induced mice hepatitis.

Inhibition of anti-Fas antibody-induced mice hepatitis by furocoumarin derivatives.

The effects of imperatorin and its synthetic derivative, Y355, on anti-Fas antibody-induced mice hepatitis were studied. Pretreatment of mice by intraperitoneal administration of imperatorine or Y355 at 30 mg/kg inhibited more than 80% of the anti-Fas antibody (150 microg/kg, i.v.)-induced elevation of plasma alanine aminotransferase activity. Furthermore, oral administration of imperatorin or Y355 at 100 mg/kg also had an inhibitory effect on anti-Fas antibody-induced hepatitis. Both compounds inhibited anti-Fas antibody (250 microg/kg)-induced caspase-1 and caspase-3 activities. The present results showed the inhibition of anti-Fas antibody-induced hepatitis by imperatorin and Y355, which might be a result of inhibition of caspase activities.

Suppressive effect of caffeine on hepatitis and apoptosis induced by tumor necrosis factor-alpha, but not by the anti-Fas antibody, in mice.

Tumor necrosis factor (TNF)-alpha-induced hepatitis and apoptosis, as respectively assessed by serum enzyme activities and hepatic DNA fragmentation were effectively suppressed by a single force-feeding of caffeine (100 mg/kg) 1.5 h before injecting the drug. In contrast, caffeine had no significant effect on anti-Fas antibody-induced hepatitis and apoptosis. These results suggest that caffeine differentially affected TNF-alpha receptor- and Fas-mediated hepatitis and apoptosis.

Minimal effect of cytokine-independent hepatitis induced by anti-Fas antibodies on hepatic cytochrome P450 gene expression in mice.

The effect of cytokine-independent hepatitis on cytochrome P450 (CYP) gene expression remains unknown. Treatment of mice with anti-Fas antibodies (150 microg/kg, i.v.) caused elevated plasma alanine aminotransferase activity at 4 and 24 h after treatment. Under normal reverse-transcription polymerase chain reaction (RT-PCR) amplification conditions, no effect of anti-Fas antibody-induced hepatitis on hepatic CYP 2E1 and 3A gene expression was observed. But lower cycle RT-PCR amplification revealed slight suppression of hepatic CYP 2E1 gene expression. The present results showed that cytokine-independent hepatitis induced by anti-Fas anti-bodies had only a minimal effect on the suppression of CYP gene expression in the liver.

Inhibition of anti-Fas antibody-induced hepatitis by aminoguanidine in mice

Aminoguanidine is an inhibitor of inducible nitric oxide synthase (iNOS) and is of potential clinical usefulness. Treatment of mice with anti-Fas antibodies (150 μg/kg, i.v.) induced elevation of plasma alanine aminotransferase activity at 4 h and this elevation was inhibited by pretreatment of mice with aminoguanidine (3, 10 and 30 mg/kg, i.p.). The anti-Fas antibody-induced elevation of caspase-3 activity was inhibited by aminoguanidine (30 mg/kg, i.p.), but the addition of aminoguanidine to the cytosol up to 10 −4 M did not inhibit the caspase-3 activity in vitro. Thus, aminoguanidine prevents anti-Fas antibody-induced hepatitis by affecting the apoptotic pathway upstream of caspase-3 activation.

The protective effect of glycyrrhizin on anti-Fas antibody-induced hepatitis in mice

Fas ligand, which is a type II membrane protein, is a major inducer of apoptosis. The effect of glycyrrhizin on anti-Fas antibody-induced hepatitis in mice was studied. Pretreatment of mice with glycyrrhizin (100, 200 and 400 mg/kg, i.p.) inhibited the anti-Fas antibody (150 μg/kg, i.v.)-induced elevation of plasma aminotransferase activity in a dose-dependent manner. CPP32 is a cystein protease and CPP32-like activity induced by anti-Fas antibody injection was inhibited by glycyrrhizin (200 mg/kg). However, the addition of glycyrrhizin (up to 10 −4 M) to a liver cytosol fraction isolated from mice treated with anti-Fas antibodies (150 μg/kg, i.v.) did not inhibit the CPP32-like activity in vitro. The present results clearly show that glycyrrhizin inhibited anti-Fas antibody-induced hepatitis by acting upstream of CPP32-like protease activation.

Pentoxifylline inhibits anti-Fas antibody-induced hepatitis by affecting downstream of CPP32-like activity in mice.

The effect of pentoxifylline on anti-Fas antibody-induced hepatitis was studied. The administration of anti-Fas antibodies (250 microg/kg, i.v.) to mice elevated plasma alanine aminotransferase (ALT) activity at 3 h. This anti-Fas antibody-induced elevation of ALT was inhibited by treatment with pentoxifylline at the doses of 10 and 100 mg/kg (i.p.). Anti-Fas antibody administration also elevated the CPP32-like protease activity in the liver at 3 h. Although pentoxifylline at 100 mg/kg, i.p., inhibited the anti-Fas antibody-induced elevation of plasma ALT, this treatment did not significantly inhibit the anti-Fas antibody-induced elevation of CPP32-like activity. The present results clearly showed that treatment with pentoxifylline inhibited anti-Fas antibody-induced hepatitis, at least in part, by affecting a reaction downstream of CPP32-like protease activation.

The Protective Effect of Cyclosporine A on Anti-Fas Antibody-Induced Hepatitis in Mice

The effect of cyclosporine A (CsA) on anti-Fas antibody-induced hepatitis was studied. The administration of anti-Fas antibody (250 μg/kg) to mice elevated plasma alanine aminotransferase (ALT) activity at 3 hr. This anti-Fas antibody-induced elevation of ALT was inhibited by treatment with CsA (10, 30 and 100 mg/kg) in a dose-dependent manner. Anti-Fas antibody administration elevated CPP32-like protease activity at 3 hr in mouse liver, and this elevation of CPP32-like activity was inhibited by treatment with CsA. The present results show that CsA treatment inhibits the anti-Fas antibody-induced apoptotic process of hepatitis, at least in part, by affecting a reaction upstream of CPP32-like protease activation.