The Use of S-Adenosyl-L-Methionine in the Treatment of Cholestatic Disorders

Alcoholic liver fibrosis: detection and treatment

Alcohol consumption is one of the main risks to public health. Alcohol use disorders (AUDs) cause 80% of hepatotoxic deaths, and approximately 50% of cirrhosis is alcohol-related. The acceptable daily intake (ADI) for ethanol is 2.6 g/day, deduced from morbidity and mortality rates due to liver fibrosis. The relative risk of cirrhosis increases significantly for doses above 60 g/day for men and 20 g/day for women over a period of around 10 years. Twenty to 40% of steatosis cases will evolve into steatohepatitis/steatofibrosis, and 8 to 20% will evolve directly into liver cirrhosis. About 20 to 40% of steatohepatitis cases will evolve into cirrhosis, and 4 to 5% into hepatocellular carcinoma. This cascade of events evolves in 5 to 40 years, with the temporal variability caused by the subjects' genetic patterns and associated risk/comorbidity factors. Steatohepatitis should be considered "the rate limiting step:" usually, it can be resolved through abstinence, although for some patients, once this situation develops, it is not substantially modified by abstention and there is a risk of fibrotic evolution. Early detection of fibrosis, obtained by hepatic elastography, is a crucial step in patients with AUDs. Such strategy allows patients to be included in a detoxification program in order to achieve abstention. Drugs such as silybin, metadoxine, and adenosylmethionine can be used. Other drugs, with promising antifibrotic effects, are currently under study. In this review, we discuss clinical and pathogenetic aspects of alcohol-related liver fibrosis and present and future strategies to prevent cirrhosis.

Therapeutic use of cytoprotective agents in canine and feline hepatobiliary disease

Many medicinal, nutraceutical, and botanic extracts have been used as cytoprotective agents in liver disease. This article explains the mechanisms of action, pertinent pharmacokinetics, side effects, and clinical indications for the use of S-adenosylmethionine, N-acetylcysteine, ursodeoxycholic acid, silymarin, and vitamin E. The literature pertaining to in vitro studies, laboratory animal models, and human and veterinary clinical trials is reviewed with regards to the efficacy and use of these cytoprotective agents in hepatobiliary disease.

Evaluation of the influence of S-adenosylmethionine on systemic and hepatic effects of prednisolone in dogs

OBJECTIVE

To evaluate the influence of a 1,4-butanedisulfonate stable salt of S-adenosylmethionine (SAMe) administered orally on clinicopathologic and hepatic effects induced by long-term administration of prednisolone in dogs.

ANIMALS

12 healthy dogs.

PROCEDURE

Following a pilot study (4 dogs), 2 groups of 4 dogs received prednisolone (2.2 mg/kg) orally once daily (84-day trial). One group received SAMe (20 mg/kg/d divided in 2 doses) for 42 days and then a placebo for 42 days; the other group received treatments in the reverse order. Before and during the trial, numerous variables were monitored, including serum total alkaline phosphatase (ALP) and glucocorticoid-induced ALP (G-ALP) activities, serum haptoglobin concentration, and total and oxidized glutathione (TGSH and GSSG) and thiobarbiturate-reacting substances (TBARS) concentrations in erythrocytes and liver tissue (days 0, 42, and 84). Hepatic specimens also were examined microscopically.

RESULTS

The stable salt of SAMe was biologically available; plasma concentrations of SAMe or prednisolone were not affected by coadministration. Compared with baseline values, serum ALP and G-ALP activities and haptoglobin concentrations increased and erythrocyte GSSG and TBARS concentrations decreased with both treatments. Erythrocyte TGSH concentration decreased with the prednisolone-placebo treatment. Administration of SAMe appeared to conserve erythrocyte TGSH values and did not inhibit hepatocyte glycogen vacuolation but increased hepatic TGSH concentration and improved the hepatic tissue GSSG:TGSH ratio.

CONCLUSIONS AND CLINICAL RELEVANCE

In dogs, administration of 20 mg of SAMe/kg/d may mitigate the apparent pro-oxidant influences of prednisolone but did not block development of classic clinicopathologic or histologic features of vacuolar hepatopathy.

Demonstration and partial characterisation of phospholipid methyltransferase activity in bile canalicular membrane from hamster liver

BACKGROUND/AIMS

Methylation of phosphatidylethanolamine to phosphatidylcholine predominantly takes place in mitochondrial-associated membrane and the endoplasmic reticulum of the liver. The transport of the phospholipids from endoplasmic reticulum to the bile canalicular membrane is via vesicular and protein transporters. In the bile canalicular membrane a flippase enzyme helps to transport phosphatidylcholine specifically to the biliary leaflet. The phosphatidylcholine then enters the bile where it accounts for about 95% of the phospholipids. We postulated that the increased proportion of phosphatidylcholine in the bile canalicular membrane and the bile compared to the transport vesicles may be due to a methyltransferase activity in the bile canalicular membrane which, using s-adenosyl methionine as the substrate, converts phosphatidylethanolamine on the cytoplasmic leaflet to phosphatidylcholine, which is transported to the biliary leaflet. The aim of our study was to demonstrate and partially characterise methyltransferase activity in the bile canalicular membrane.

METHODS

Organelles were obtained from hamster liver by homogenisation and separation by sucrose gradient ultracentrifugation. These, along with phosphatidylethanolamine, were incubated with radiolabelled s-adenosyl methionine. Phospholipids were separated by thin-layer chromatography and radioactivity was counted by scintigraphy.

RESULTS

We demonstrated methyltransferase activity (nmol of SAMe converted/mg of protein/h at 37 degrees C) in the bile canalicular membrane of 0.442 (SEM 0.077, n=8), which is more than twice that found in the microsomes at 0.195 (SEM 0.013, n=8). The Km and pH optimum for the methyltransferase in the bile canalicular membrane and the microsomes were similar (Km 25 and 28 microM, respectively, pH 9.9 for both). The Vmax was different at 0.358 and 0.168 nmol of SAMe converted/mg of protein/h for the bile canalicular membrane and the microsomes, respectively.

CONCLUSION

The presence of the methyltransferase activity in the bile canalicular membrane may be amenable to therapeutic manipulation.

Oral S-adenosyl-L-methionine (SAMe) administration enhances bile salt conjugation with taurine in patients with liver cirrhosis

We investigated whether the oral administration of SAMe influences the hepatic availability of sulphur amino acids and the extent of bile salt amidation with taurine in liver cirrhosis. Ten patients with cirrhosis (eight Child-Pugh A and 2 B, aged 48-65 years), were studied before and 2 months after oral SAMe administration (800 mg per day). Bile was obtained using a string-test device (Entero-test), after gall-bladder contraction with caerulein. No significant changes were found in the per cent composition of biliary amino acids, except for an increase in glutamic acid (from 3.7 +/- 0.6% before to 6.1 +/- 1.1% after SAMe, p = 0.003) and taurine from 2.2 +/- 2.3% (range 0.4-6.8) to 7.2 +/- 9.2% (range 0.5-28.1), (NS). HPLC analysis showed a trend towards increased per cent tauroconjugation of all individual bile salts, with a significant rise in taurochenodeoxycholic acid (from 15.0 +/- 9.4% to 25.3 +/- 9.7%, p = 0.05) and a drop in glycocholic acid (from 39.1 +/- 15.3% to 25.3 +/- 9.8%, p = 0.05). These data suggest that in the cirrhotic liver exogenous SAMe is partially metabolized to taurine, which is used for bile salt amidation.