In vitro and in vivo prevention of human CD8+ CTL-mediated xenocytotoxicity by pig c-FLIP expression in porcine endothelial cells.
Overcoming cell-mediated immunity, especially of human CD8(+) CTLs, is important for the success of xenotransplantation. Our group has previously reported that the cytotoxicity of human CD8(+) CTLs against pig endothelial cells (PEC) is highly detrimental and mediated in major part by the Fas/FasL apoptotic pathway. Cellular FLICE inhibitory protein (c-FLIP) was originally identified as an inhibitor of death-receptor signaling through binding competition with caspase-8 for recruitment to Fas-associated via death domain (FADD). Two major c-FLIP variants result from alternative mRNA splicing: a short, 26-KDa protein (c-FLIP(S)) and a long, 55-KDa form (c-FLIP(L)). The cytoprotective effects of c-FLIP(S/L) in xenograft cells remain controversial. This study demonstrates that the overexpression of c-FLIP(S/L) genes markedly suppress human CD8(+) CTL-mediated xenocytotoxicity and, in addition, the cytoprotective effects of c-FLIP(L) appear to be significantly stronger than those of c-FLIP(S). Furthermore, to prove the prolonged effects of xenograft survival, PEC transfectants with c-FLIP(S/L) genes were transplanted under rat kidney capsules. Prolonged survival was elicited from FLIP(S/L) transfectants, whereas parental PEC was completely rejected through day 5, posttransplant. Thus, intracellular remodeling with the overexpression of c-FLIP(S/L) in xenograft cells may avoid innate cellular attacks against xenografts and facilitate long-term xenograft survival.
Tanemura
M
M
Department of Surgery (E1), Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan. tanemura@surg1.med.osaka-u.ac.jp
Saga
A
A
Kawamoto
K
K
Deguchi
T
T
Machida
T
T
Nishida
T
T
Sawa
Y
Y
Ito
T
T
D000818:Animals; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000235:genetics*; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D003602:Cytotoxicity, Immunologic; D053938:DNA Fragmentation; D004730:Endothelium, Vascular; D005822:Genetic Vectors; D006801:Humans; D017710:Lymphocyte Transfusion; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013552:Swine; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D014183:Transplantation, Heterologous / Q000276:immunology*
D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D020169:Caspases