Fas ligand gene transfer prolongs rat renal allograft survival and down-regulates anti-apoptotic Bag-1 in parallel with enhanced Th2-type cytokine expression.
BACKGROUND
Fas ligand (FasL) induces apoptosis of cells bearing Fas receptor, and may play a role in the acquisition of immune privilege. We have previously shown that adenovirus (Ad)-mediated FasL gene transfer significantly prolongs survival in a strongly major histocompatibility complex-incompatible rat kidney allograft model. This study analyzes putative mechanisms of FasL-mediated effects, with particular emphasis on Th1 and Th2 immune activation and Bag-1 expression, a Bcl-2-binding anti-apoptotic protein.


METHODS
Kidney transplants were performed in Wistar-Furth to Lewis rat combination. Donor kidneys were perfused in situ with Ad-FasL or Ad-beta-Gal, and then transplanted. Kidney allografts were harvested at days 2, 7, and 56 and were evaluated by hematoxylin and eosin and immunohistochemical staining. The expression of FasL, Bag-1, and Th1/Th2 cytokine genes was assessed by Northern blots, Western blots, and competitive template reverse-transcriptase polymerase chain reaction, respectively.


RESULTS
Intragraft expression of FasL was enhanced, whereas that of anti-apoptotic Bag-1 gene was diminished throughout, in Ad-FasL-transduced well-functioning renal allografts, compared with Ad-beta-Gal-treated rejecting controls. In parallel, the expression of mRNA coding for IL-2 and IFN-gamma remained depressed, whereas that of IL-4 and IL-10 reciprocally and progressively increased in the Ad-FasL animal group.


CONCLUSIONS
Prolonged survival in Ad-FasL-transduced rat renal allograft model correlates with down-regulation of Bag-1, a novel anti-apoptotic gene, and preferential Th2-type cytokine elaboration profile at the graft site. Because Th1-like cells are sensitive to FasL-mediated cytotoxic effects, T-cell apoptosis may preferentially spare Th2-like cells, with resultant prolonged graft survival.
Ke
B
B
The Dumont-UCLA Transplant Center, Department of Surgery, UCLA School of Medicine, Los Angeles, California 90095, USA.
Coito
A J
AJ
Kato
H
H
Zhai
Y
Y
Wang
T
T
Sawitzki
B
B
Seu
P
P
Busuttil
R W
RW
Kupiec-Weglinski
J W
JW
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D002352:Carrier Proteins / Q000378:metabolism* / Q000502:physiology; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins; D015536:Down-Regulation / Q000502:physiology; D053222:Fas Ligand Protein; D015870:Gene Expression; D018014:Gene Transfer Techniques; D006085:Graft Survival; D007668:Kidney / Q000378:metabolism / Q000502:physiology; D016030:Kidney Transplantation; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism; D051381:Rats; D011917:Rats, Inbred Lew; D011920:Rats, Inbred WF; D018418:Th2 Cells / Q000378:metabolism*; D014157:Transcription Factors; D014184:Transplantation, Homologous
C091732:BCL2-associated athanogene 1 protein; D002352:Carrier Proteins; D016207:Cytokines; D004268:DNA-Binding Proteins; D053222:Fas Ligand Protein; C505662:Faslg protein, rat; D008562:Membrane Glycoproteins; D014157:Transcription Factors