Effect of FTY720 and ex vivo graft irradiation in rat small bowel transplantation: apoptosis of crypt cells and lymphocytes.
OBJECTIVE
We investigated the extent of apoptosis in crypt cells and Peyer's patches (PPs) during small bowel allograft rejection in rats to examine the effect of FTY720 and ex vivo graft irradiation during rejection.


METHODS
Orthotopic small bowel transplantations (SBT) were performed from Brown Norway (BN) rats to Lewis (LEW) rats. Four groups of SBT animals were studied on days 3, 5, and 7 after operations: untreated allograft, allograft with FTY720, allograft with irradiation, and allograft with FTY720+irradiation. Cryostat sections were prepared from the grafts, including PPs. An in situ end-labeling (ISEL) technique was used to detect apoptotic cells. Indirect immunoperoxidase staining was also performed using monoclonal antibodies against rat Fas/FasL.


RESULTS
The graft survival was prolonged in the FTY720-treated groups. In the FTY720-treated group, the number of ISEL-positive enterocytes was significantly down-regulated on days 3, 5, and 7 compared with the untreated allograft group. The number of ISEL-positive mononuclear cells was also significantly down-regulated compared with the untreated allograft group. The FTY720 the radiation and the FTY720+irradiation treated groups showed significantly down-regulated numbers of Fas/FasL-positive enterocytes on day 7 compared with the untreated allograft group. Fas/FasL-positive mononuclear cells were also significantly down-regulated in the allograft compared with the untreated allograft group.


CONCLUSIONS
FTY720 and ex vivo graft irradiation prevented up-regulation of the number of apoptotic enterocytes, lymphocytes, and Fas/FasL-positive lymphocytes, and also prolonged small bowel allograft survival. Combination FTY720 and ex vivo graft irradiation did not affect graft survival and apoptotic cell expression compared with the FTY720 only group. These findings suggest that FTY720 may prevent both rejection-associated and sepsis-induced apoptosis during the late phase of small bowel graft rejection.
Sugito
K
K
Department of Pediatric Surgery, Nihon University, Tokyo, Japan. Ksugito@hotmail.com
Inoue
M
M
Ikeda
T
T
Hagiwara
N
N
Koshinaga
T
T
Kusafuka
T
T
D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000528:radiation effects; D000068876:Fingolimod Hydrochloride; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D007421:Intestine, Small / Q000187:drug effects / Q000473:pathology / Q000528:radiation effects* / Q000637:transplantation*; D008214:Lymphocytes / Q000166:cytology* / Q000187:drug effects / Q000528:radiation effects; D011409:Propylene Glycols / Q000627:therapeutic use*; D051381:Rats; D011914:Rats, Inbred BN; D011917:Rats, Inbred Lew; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D016019:Survival Analysis; D014184:Transplantation, Homologous / Q000473:pathology*
D007166:Immunosuppressive Agents; D011409:Propylene Glycols; D000068876:Fingolimod Hydrochloride; D013110:Sphingosine