Ultrastructural study of development of hepatic necrosis induced by TNF-alpha and D-galactosamine.

Recent studies have suggested an association between tumor necrosis factor-alpha (TNF-alpha) and the development and progression of acute liver failure. To investigate the role of TNF-alpha in the mechanism of massive hepatic necrosis, we studied a mouse model of TNF-alpha and D-galactosamine (GalN) -induced hepatic necrosis by ultrastructural analysis. Administration of GalN caused edema of hepatocellular microvilli and widening of sinusoidal endothelial fenestrae (SEF); administration of TNF-alpha caused only a widening of the SEF. Massive hepatic necrosis with hemorrhage was seen 6 hr after concomitant administration of TNF-alpha and GalN. In the ultrastructural analysis, edema of the hepatocellular microvilli, widening of the SEF, and transmigration of red blood cells (RBC) and platelets to the space of Disse without exfoliation and necrosis of the sinusoidal endothelial cells were observed. Fibrin deposits were seen in areas adjacent to injured hepatocytes. The diameter of the SEF was significantly greater than in the nontreated group and the groups treated with TNF-alpha or GalN alone. These results suggest that as a consequence of the increase in diameter of the SEF, transmigration of RBCs and platelets to the space of Disse may have resulted in massive hepatic necrosis due to occlusion of the microcirculation.