Inhibition of caspase activity prevents CD95-mediated hepatic microvascular perfusion failure and restores Kupffer cell clearance capacity.
Using a murine model, we studied the effect of agonistic anti-CD95 antibodies (aCD95) on sinusoidal lining cells and a potential protection by caspase inhibition. C3H/HeN mice were intravenously administered aCD95 (10 microgram/mouse) or unspecific IgG (control) in the presence or absence of the caspase inhibitor z-VAD-fmk. Analysis of hepatic microcirculation using intravital fluorescence microscopy revealed severe (P<0.01) sinusoidal perfusion failure and reduced (P<0.05) phagocytic activity of Kupffer cells (KC) within 2 h. Transmission electron micrographs demonstrated loss of integrity of sinusoidal endothelial cells as early as 1 h after aCD95 application, whereas histological manifestation of hepatocellular apoptosis and hemorrhagic necrosis was most pronounced at 6 h. Blocking of caspase activity attenuated (P<0.01) both hepatic microvascular perfusion failure and KC dysfunction. Accordingly, full protection of the liver from apoptotic damage and intact microarchitecture was observed in histological sections after z-VAD-fmk treatment. Mortality rate was 40% 6 h after aCD95 administration, whereas all animals survived in the z-VAD-fmk group (P<0.05). The activation of caspases through CD95 may primarily lead to damage of sinusoidal endothelial cells and hepatic microvascular perfusion failure. Moreover, reduced phagocytic capacity of KC may contribute to accumulation of toxic metabolites released by dying cells at the local site of inflammation, further aggravating liver injury.
Wanner
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GA
Division of Trauma Surgery and Department of Pathology, University Hospital Zurich, CH-8091 Zurich, Switzerland. guido.wanner@chi.usz.ch
Mica
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Wanner-Schmid
E
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Kolb
S A
SA
Hentze
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H
Trentz
O
O
Ertel
W
W
D000410:Alanine Transaminase / Q000097:blood; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D001219:Aspartate Aminotransferases / Q000097:blood; D053148:Caspase 3; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D007728:Kupffer Cells / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology; D007962:Leukocytes / Q000166:cytology; D008099:Liver / Q000098:blood supply / Q000166:cytology / Q000201:enzymology; D008102:Liver Circulation / Q000187:drug effects*; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008854:Microscopy, Electron; D010587:Phagocytosis / Q000187:drug effects; D019014:fas Receptor / Q000187:drug effects* / Q000276:immunology
D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D019014:fas Receptor; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase; C505409:Casp3 protein, mouse; D053148:Caspase 3