BACKGROUND: A major mechanism underlying warm ischemia/reperfusion (I/R) injury during liver transplantation is the activation of the caspase chain, which leads to apoptosis. Recently, it was demonstrated that the release of cathepsin B, a cysteine protease, from the cytosol in liver injury induces mitochondrial release of cytochrome c and the activation of caspase-3 and -9, thereby leading to apoptosis. The aim of this study was to ascertain if cathepsin B inactivation attenuates the apoptotic injury due to I/R in mouse liver. METHODS: A model of segmental (70%) hepatic ischemia was used. Eighteen mice were anesthetized and randomly divided into three groups: (1) CONTROL GROUP: sham operation (laparotomy); (2) Ischemic group: midline laparotomy followed by occlusion of all structures in the portal triad to the left and median lobes for 60 min (ischemic period); (3) STUDY GROUP: like group 2, but with intraperitoneal administration of a pharmacological inhibitor of cathepsin B (4 mg/100 g) 30 min before induction of ischemia. Serum liver enzyme levels were measured by biochemical analysis, and intrahepatic caspase-3 activity was measured by fluorometric assay; apoptotic cells were identified by morphological criteria, the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) fluorometric assay, and immunohistochemistry for caspase-3. RESULTS: Showed that at 6 h of reperfusion, there was a statistically significant reduction in liver enzyme levels in the animals pretreated with cathepsin B inhibitor (p<0.05). On fluorometric assay, caspase-3 activity was significantly decreased in group 3 compared to group 2 (p<0.0001). The reduction in postischemic apoptotic hepatic injury in the cathepsin B inhibitor -treated group was confirmed morphologically, by the significantly fewer apoptotic hepatocyte cells detected (p<0.05); immunohistochemically, by the significantly weaker activation of caspase-3 compared to the ischemic group (p<0.05); and by the TUNEL assay (p<0.05). CONCLUSION: The administration of cathepsin B inhibitor before induction of ischemia can attenuate postischemic hepatocyte apoptosis and thereby minimize liver damage. Apoptotic hepatic injury seems to be mediated through caspase-3 activity. These findings have important implications for the potential use of cathepsin B inhibitors in I/R injury during liver transplantation.
BACKGROUND: A major mechanism underlying warm ischemia/reperfusion (I/R) injury during liver transplantation is the activation of the caspase chain, which leads to apoptosis. Recently, it was demonstrated that the release of cathepsin B, a cysteine protease, from the cytosol in liver injury induces mitochondrial release of cytochrome c and the activation of caspase-3 and -9, thereby leading to apoptosis. The aim of this study was to ascertain if cathepsin B inactivation attenuates the apoptotic injury due to I/R in mouse liver. METHODS: A model of segmental (70%) hepatic ischemia was used. Eighteen mice were anesthetized and randomly divided into three groups: (1) CONTROL GROUP: sham operation (laparotomy); (2) Ischemic group: midline laparotomy followed by occlusion of all structures in the portal triad to the left and median lobes for 60 min (ischemic period); (3) STUDY GROUP: like group 2, but with intraperitoneal administration of a pharmacological inhibitor of cathepsin B (4 mg/100 g) 30 min before induction of ischemia. Serum liver enzyme levels were measured by biochemical analysis, and intrahepatic caspase-3 activity was measured by fluorometric assay; apoptotic cells were identified by morphological criteria, the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) fluorometric assay, and immunohistochemistry for caspase-3. RESULTS: Showed that at 6 h of reperfusion, there was a statistically significant reduction in liver enzyme levels in the animals pretreated with cathepsin B inhibitor (p<0.05). On fluorometric assay, caspase-3 activity was significantly decreased in group 3 compared to group 2 (p<0.0001). The reduction in postischemic apoptotic hepatic injury in the cathepsin B inhibitor -treated group was confirmed morphologically, by the significantly fewer apoptotic hepatocyte cells detected (p<0.05); immunohistochemically, by the significantly weaker activation of caspase-3 compared to the ischemic group (p<0.05); and by the TUNEL assay (p<0.05). CONCLUSION: The administration of cathepsin B inhibitor before induction of ischemia can attenuate postischemic hepatocyte apoptosis and thereby minimize liver damage. Apoptotic hepatic injury seems to be mediated through caspase-3 activity. These findings have important implications for the potential use of cathepsin B inhibitors in I/R injury during liver transplantation.
Authors: Weihong He; Charlotte S McCarroll; Katrin Nather; Kristopher Ford; Kenneth Mangion; Alexandra Riddell; Dylan O'Toole; Ali Zaeri; David Corcoran; David Carrick; Mathew M Y Lee; Margaret McEntegart; Andrew Davie; Richard Good; Mitchell M Lindsay; Hany Eteiba; Paul Rocchiccioli; Stuart Watkins; Stuart Hood; Aadil Shaukat; Lisa McArthur; Elspeth B Elliott; John McClure; Catherine Hawksby; Tamara Martin; Mark C Petrie; Keith G Oldroyd; Godfrey L Smith; Keith M Channon; Colin Berry; Stuart A Nicklin; Christopher M Loughrey Journal: Cardiovasc Res Date: 2022-05-06 Impact factor: 13.081