Inhibition of p53 protects liver tissue against endotoxin-induced apoptotic and necrotic cell death.
There is increasing evidence that apoptotic and necrotic hepatocyte death following endotoxin-induced liver injury act as signals for leukocyte sequestration in the liver vasculature. p53 has been implicated to promote apoptosis through trans-activation and down-regulation of specific pro- and anti-apoptotic genes. Here, we report that inhibition of p53 decreases apoptotic and necrotic tissue injury as well as inflammatory cell response. Sprague-Dawley rats were injected intraperitoneally with 2.2 mg/kg pifithrin-alpha (PFT), a p53-inactivating agent, or the vehicle DMSO 30 min before intravenous exposure to lipopolysaccharide (LPS). In vehicle-pretreated animals, LPS induced significant apoptosis and necrosis of hepatocytes, which was associated with intrahepatic leukocyte recruitment, microvascular dysfunction, and enzyme release. Inhibition of p53 effectively attenuated (P<0.05) hepatocellular apoptosis and necrosis, but also reduced leukocyte recruitment and microvascular dysfunction. Western blot analysis revealed that PFT lowered the nuclear-to-cytoplasmic p53 ratio and reduced both activation of NF-kappaB and cleavage of procaspase 3 (P<0.05). In parallel, immunohistochemistry of PFT-pretreated, but not vehicle-pretreated, endotoxic animals exhibited nuclear p53 exclusion and reduced NF-kappaB p65 staining. This indicates that p53 mediates, at least in part, LPS-associated apoptosis and contributes to inflammatory endotoxic tissue injury through leukocyte activation and intraorgan sequestration.
Schäfer
T
T
Institute for Clinical and Experimental Surgery, University of Saarland, D-66421 Homburg/Saar, Germany.
Scheuer
C
C
Roemer
K
K
Menger
M D
MD
Vollmar
B
B
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D052160:Benzothiazoles; D015153:Blotting, Western; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D005260:Female; D007150:Immunohistochemistry; D008070:Lipopolysaccharides / Q000008:administration & dosage; D008099:Liver / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008297:Male; D008856:Microscopy, Fluorescence / Q000379:methods; D016328:NF-kappa B / Q000378:metabolism; D009336:Necrosis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013844:Thiazoles / Q000494:pharmacology*; D014050:Toluene / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000637:Transaminases / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors* / Q000378:metabolism
D052160:Benzothiazoles; D008070:Lipopolysaccharides; D016328:NF-kappa B; D013844:Thiazoles; D016159:Tumor Suppressor Protein p53; D014050:Toluene; C121565:pifithrin; D000637:Transaminases; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases