Cathepsin B inactivation attenuates hepatocyte apoptosis and liver damage in steatotic livers after cold ischemia-warm reperfusion injury.
Hepatic steatosis predisposes the liver to cold ischemia-warm reperfusion (CI/WR) injury by unclear mechanisms. Because hepatic steatosis has recently been associated with a lysosomal pathway of apoptosis, our aim was to determine whether this cell-death pathway contributes to CI/WR injury of steatotic livers. Wild-type and cathepsin B-knockout (Ctsb(-/-)) mice were fed the methionine/choline-deficient (MCD) diet for 2 wk to induce hepatic steatosis. Mouse livers were stored in the University of Wisconsin solution for 24 h at 4 degrees C and reperfused for 1 h at 37 degrees C in vitro. Immunofluorescence analysis of the lysosomal enzymes cathepsin B and D showed a punctated intracellular pattern consistent with lysosomal localization in wild-type mice fed a standard diet after CI/WR injury. In contrast, cathepsin B and D fluorescence became diffuse in livers from wild-type mice fed MCD diet after CI/WR, indicating that lysosomal permeabilization had occurred. Hepatocyte apoptosis was rare in both normal and steatotic livers in the absence of CI/WR injury but increased in wild-type mice fed an MCD diet and subjected to CI/WR injury. In contrast, hepatocyte apoptosis and liver damage were reduced in Ctsb(-/-) and cathepsin B inhibitor-treated mice fed the MCD diet following CI/WR injury. In conclusion, these findings support a prominent role for the lysosomal pathway of apoptosis in steatotic livers following CI/WR injury.
Baskin-Bey
E S
ES
Mayo Clinic College of Medicine, 200 First St. SW, Rochester, Minnesota 55905, USA.
Canbay
A
A
Bronk
S F
SF
Werneburg
N
N
Guicciardi
M E
ME
Nyberg
S L
SL
Gores
G J
GJ
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002401:Cathepsin B / Q000037:antagonists & inhibitors / Q000502:physiology*; D002402:Cathepsin D / Q000502:physiology; D005234:Fatty Liver / Q000473:pathology / Q000503:physiopathology*; D022781:Hepatocytes / Q000502:physiology*; D008099:Liver / Q000473:pathology / Q000502:physiology; D008247:Lysosomes / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D015427:Reperfusion Injury / Q000473:pathology / Q000503:physiopathology*
D002401:Cathepsin B; D002402:Cathepsin D