Overexpressed exogenous IL-4 And IL-10 paradoxically regulate allogenic T-cell and cardiac myocytes apoptosis through FAS/FASL pathway.
BACKGROUND
The authors' previous study has shown that liposome-mediated ex vivo intracoronary interleukin (IL)-4 and IL-10 combined gene therapy suppressed the allo-immune responses and prolonged the cardiac allograft survival by 15 folds. However, the mechanism for promoting long-term allograft survival remains unknown.


METHODS
This study tested the hypothesis that this combined cytokine gene targeting may promote alloreactive T-cell apoptosis or prevent apoptosis of cardiac allograft myocytes through Fas/Fas ligand (FasL) pathway. A rabbit functional cervical heterotopic heart transplantation model was used, and plasmid human recombinant IL-4 and IL-10 gene complexed with cationic liposome (GAP/DLRIE) was delivered into cardiac allografts by intracoronary infusion ex vivo.


RESULTS
This liposome-mediated IL-4 and IL-10 combined gene therapy significantly increased apoptotic T cells detected by TUNEL staining. The caspase-8 or caspase-3 expressing T cells were also significantly increased. The Fas+ apoptotic T cells dominated in the population of apoptotic CD4+ T cells, but FasL+ CD4+ T-cell population was less effected in the combined gene therapy group. The effect of combined gene therapy on the infiltrative Fas+ CD8+ T-cell population is much less than that on Fas+ CD4+ cells, and there was almost no effect on the FasL+ CD8+ T-cell population. Furthermore, localized IL-4 and IL-10 combined gene therapy protected cardiac allograft myocytes by down-regulating its FasL expression, but not Fas.


CONCLUSIONS
These results suggest that this combined gene targeting strategy which induced localized overexpression of exogenous IL-4 and IL-10 may promote alloreactive T-cell apoptosis and prevent myocytes apoptosis through Fas/FasL cell surface interaction, therefore inducing cardiac allograft tolerance.
Furukawa
Hiroshi
H
Division of Cardiothoracic Surgery, Department of Surgery, UCLA Medical Center, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-1679, USA.
Oshima
Kiyohiro
K
Tung
Thomas
T
Cui
Guanggen
G
Laks
Hillel
H
Sen
Luyi
L
D000818:Animals; D017209:Apoptosis; D053222:Fas Ligand Protein / Q000378:metabolism*; D005786:Gene Expression Regulation; D015316:Genetic Therapy; D006085:Graft Survival / Q000276:immunology; D016027:Heart Transplantation; D006801:Humans; D016753:Interleukin-10 / Q000235:genetics / Q000378:metabolism*; D015847:Interleukin-4 / Q000235:genetics / Q000378:metabolism*; D008297:Male; D032383:Myocytes, Cardiac / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D011817:Rabbits; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000166:cytology / Q000378:metabolism*; D013997:Time Factors; D014184:Transplantation, Homologous / Q000276:immunology; D019014:fas Receptor / Q000378:metabolism*
D053222:Fas Ligand Protein; D019014:fas Receptor; D016753:Interleukin-10; D015847:Interleukin-4