Zinc finger protein A20 promotes regeneration of small-for-size liver allograft and suppresses rejection and results in a longer survival in recipient rats.
BACKGROUND
Small-for-size liver allografts without immunosuppression have decreased survival compared with full-for-size grafts for the concomitant regeneration-induced accelerated rejection. This study was designed to examine the effect of zinc finger protein A20 on liver allograft regeneration and acute rejection using a high responder rat model (DA-->Lewis) of 30% partial liver transplantation.


METHODS
Adenovirus carrying the full length of A20 was introduced into liver grafts by ex vivo perfusion via the portal vein during preservation, physiological saline (PS), and empty Ad vector rAdEasy served as controls; then small-sized liver transplants were performed. Liver graft regeneration was assessed, as well as graft rejection, hepatocyte apoptosis, nuclear factor kappa B activation, and intercellular adhesion molecule-1 mRNA expression in liver graft sinusoidal endothelial cells (LSECs), infiltration of liver graft infiltrating mononuclear cells (LIMCs), and the subproportion of NK and NKT cells, activity of liver graft NK-like cells, interferon gamma (IFN-gamma) production, and animal survival.


RESULTS
Ex vivo transfer of the A20 gene resulted in overexpression of A20 protein in LSECs and hepatocytes 24 h after partial liver transplantation. Regeneration of the small-sized liver allograft was augmented by A20 overexpression, the DNA synthesis of hepatocytes on d 4 post-transplant was increased in A20 group compared with PS and rAdEasy groups (P < 0.01). Hepatocyte apoptosis was inhibited by A20 (P < 0.001). On d 4 after transplantation, histological examination revealed a more exiguous cellular infiltration and mild rejection in A20 group but a more vigorous cellular infiltration in the sinusoidal area and more severe rejection in PS and rAdEasy group. Nuclear factor kappa B activation and intercellular adhesion molecule-1 mRNA expression in LSECs were suppressed by A20 overexpression. Flow cytometry analysis showed a marked down-regulation of LIMCs number by A20, including more prominent decrease in the subproportion of NK and NKT cells. Activity of liver graft NK-like cells, IFN-gamma mRNA expression in LIMCs, and serum IFN-gamma protein level were also suppressed by A20 overexpression (P < 0.05), respectively. Survival days of A20 rats were longer than those of PS rats and rAdEasy rats (P < 0.01), whereas survival days of rAdEasy rats were shorter than those of PS rats (P < 0.01).


CONCLUSIONS
These data suggest that A20 overexpression could effectively promote small-sized liver allograft regeneration, suppress rejection, and prolong survival of recipient rat. These effects of A20 could be related to an inhibition of LSECs activation, suppression of infiltration of LIMCs, and the subpopulations such as NK and NKT cells into liver graft, and inhibition of hepatocyte apoptosis.
Xu
Ming-Qing
MQ
Liver Transplantation Division, Department of General Surgery, West China Hospital, Sichuan University, Chengdu, China.
Yan
Lu-Nan
LN
Gou
Xing-Hua
XH
Li
De-Hua
DH
Huang
Ying-Chun
YC
Hu
Hai-Yang
HY
Wang
Lan-Ying
LY
Han
Lei
L
D000256:Adenoviridae; D000818:Animals; D017209:Apoptosis; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation; D042783:Endothelial Cells / Q000378:metabolism; D018014:Gene Transfer Techniques; D015316:Genetic Therapy; D006084:Graft Rejection / Q000517:prevention & control*; D022781:Hepatocytes / Q000502:physiology; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D007371:Interferon-gamma / Q000378:metabolism; D008099:Liver / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D008115:Liver Regeneration; D016031:Liver Transplantation / Q000276:immunology / Q000473:pathology*; D008214:Lymphocytes / Q000502:physiology; D008297:Male; D016328:NF-kappa B / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011917:Rats, Inbred Lew; D016019:Survival Analysis; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3
D004268:DNA-Binding Proteins; D016328:NF-kappa B; D012333:RNA, Messenger; D018799:Intercellular Adhesion Molecule-1; D007371:Interferon-gamma; C000602677:TNFAIP3 protein, rat; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3