Heme oxygenase-1 alleviates ischemia/reperfusion injury in aged liver.
OBJECTIVE
To investigate if ischemia/reperfusion (I/R) injury in aged liver could be alleviated by heme oxygenase-1 (HO-1).


METHODS
Three groups of SD rats (16 mo old) were studied. Group 1: control donors received physiological saline 24 h before their livers were harvested; group 2: donors were pretreated with hemin 24 h before their livers were harvested; and group 3: donors received hemin 24 h before their livers were harvested and zinc protoporphyrin (ZnPP, HO-1 inhibitor) was given to recipients at reperfusion. The harvested livers were stored in University of Wisconsin solution (4 degrees) for 6 h, and then transplanted to syngeneic rats. Serum glutamic oxaloacetic transaminase (SGOT), apoptotic cells, and apoptotic gene were measured 3, 6, 12, 24, 48 h after reperfusion. We measured the apoptotic index by TUNEL, determined the expression of antiapoptotic Bcl-2 and proapoptotic (caspase-3) gene products by Western blot.


RESULTS
After 3, 6, 12, 24, and 48 h of reperfusion, the SGOT levels (584.4+/-85.8 u/L, 999.2+/-125.2 u/L, 423.4+/-161.3 u/L, 257.8+/-95.8 u/L, and 122.4+/-26.4 u/L) in hemin group were significantly (all P<0.05) lower than those in saline group (1082.2+/-101.2 u/L, 1775.2+/-328.3 u/L, 840.4+/-137.8 u/L, 448.6+/-74.3 u/L, and 306.2+/-49.3 u/L). Liver HO-1 enzymatic activity correlated with beneficial effects of hemin and deleterious effects of adjunctive ZnPP treatment. Markedly less apoptotic (TUNEL+) liver cells 3, 6, 12, 24, and 48 h after reperfusion (5.16+/-0.73, 10.2+/-0.67, 9.28+/-0.78, 7.14+/-1.12, and 4.78+/-0.65) (P<0.05) could be detected in hemin liver grafts, as compared to controls (7.82+/-1.05, 15.94+/-1.82, 11.67+/-1.59, 8.28+/-1.09, and 6.36+/-0.67). We detected the increased levels of Bcl-2 (1.5-fold) expression and compared with saline controls. These differences were most pronounced at 12 h after transplantation. In contrast, an active form of proapoptotic caspase-3 (p20) protein was found to be 2.9-fold lower at 24 h in hemin-pretreated group, as compared to saline liver transplant controls.


CONCLUSIONS
HO-1 overexpression can provide potent protection against cold I/R injury. This effect depends, at least in part, on HO-1-mediated inhibition of antiapoptotic mechanism.
Wang
Xue-Hao
XH
Liver Transplantation Center of the First Affiliated Hospital, Nanjing Medical University, 300 Guangzhou Road, Nanjing 210029, Jiangsu province, China.
Wang
Ke
K
Zhang
Feng
F
Li
Xiang-Cheng
XC
Li
Jun
J
De
Wei
W
Guo
Jun
J
Qian
Xiao-Feng
XF
Fan
Ye
Y
D000375:Aging / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D003080:Cold Temperature; D004789:Enzyme Activation / Q000187:drug effects; D006085:Graft Survival; D006360:Heat-Shock Proteins / Q000378:metabolism*; D006419:Heme Oxygenase (Decyclizing); D006427:Hemin / Q000494:pharmacology; D008099:Liver / Q000201:enzymology / Q000473:pathology; D008107:Liver Diseases / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D016031:Liver Transplantation; D008297:Male; D010105:Oxygenases / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*
D006360:Heat-Shock Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D006427:Hemin; D010105:Oxygenases; D006419:Heme Oxygenase (Decyclizing); C491523:Hmox1 protein, rat; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases