Protective role of biliary cholesterol and phospholipid lamellae against bile acid-induced cell damage.
BACKGROUND/AIMS: Bile salts (BS) are cytotoxic agents, but cell damage is not observed in the hepatobiliary system. We hypothesized that biliary lipid vesicles (unilamellae and multilamellae) could have a protective role against BS-induced cytotoxicity. METHODS: Biliary lipid lamellar secretion was induced by feeding rats with 0.5% diosgenin. Cytoprotection was assessed in bile duct-obstructed rats and by incubating human erythrocytes with sodium taurocholate. RESULTS: Biliary cholesterol concentration increased > 300% in diosgenin-fed rats; electron microscopic examination showed a great abundance of lipid lamellar vesicles in bile and within the canaliculi. After bile duct obstruction, serum hepatic enzyme activities were significantly lower in diosgenin-fed rats. Histologically severe and confluent hepatocellular necrosis was only observed in control rats. Biliary lamellar lipid material significantly reduced the BS-induced hemolytic effect in vitro in a concentration-dependent manner. This protective effect correlated to a progressive decrease in the intermicellar BS concentration. Phosphatidylcholine or cholesterol, alone or as lamellar structures, also showed cytoprotective effect in vitro but always less than native biliary lamellae. CONCLUSIONS: These results support the concept that native biliary cholesterol phospholipid lamellae represent an important cytoprotective factor for hepatocytes and biliary epithelial cells against BS-induced damage.[1]References
- Protective role of biliary cholesterol and phospholipid lamellae against bile acid-induced cell damage. Puglielli, L., Amigo, L., Arrese, M., Núñez, L., Rigotti, A., Garrido, J., González, S., Mingrone, G., Greco, A.V., Accatino, L. Gastroenterology (1994) [Pubmed]
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