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FTY720 prevents chronic rejection of rat heterotopic cardiac allografts
FTY720 Prevents Chronic Rejection of Rat Heterotopic Cardiac Allografts S.-C. Chueh, J.-R. Chen, J. Chen, and M.-K. Lai
F
TY720 is a novel immunosuppressant, isolated and chemically modified from the culture filtrate of the ascomycete Isaria sinclarii, and it has been shown to effectively prolong the survival of rat skin, heart, and liver allografts, and the survival of renal allografts in canine and subhuman primates.1,2 FTY720 also induces tolerance in rat cardiac allografts when combined with allochimeric class I MHC antigen3 and potentiates the immunosuppressive effects of cyclosporine (CsA) and/or sirolimus.4 A phase I clinical study with FTY720 in stable renal recipients is being evaluated [BD Kahan, personal communication], but its role in chronic rejection has not been explored before. This study tried to evaluate the effect of FTY720 in preventing chronic rejection of solid organ transplants in a rat model of heterotopic cardiac transplantation.
MATERIALS AND METHODS Animals Adult male inbred Lewis (donor, RT11) and F344 (recipient, RT11v) rats weighing 160 to 250 g were purchased and cared for under the treatment guidelines of the institutional Animal Welfare Committee. All operations were performed under aseptic condi-
From the Departments of Urology (S.-C.C., J.C., M.-K.L.) and Pathology (J.-R.C.), College of Medicine, National Taiwan University, Taipei, Taiwan. Supported by grants from National Science Council, R.O.C., National Taiwan University Hospital, and Chu’s Foundation. Address reprint requests to Shih-Chieh Chueh, MD, Suite 11–13, Clinical Research Building, National Taiwan University Hospital, No. 7, Chung-Shan South Road, Taipei, Taiwan.
Fig. 1. Effect of FTY720 in preventing chronic rejection plotted by Kaplan-Meier survival estimates. See text for detailed description and statistic comparisons.
0041-1345/01/$–see front matter PII S0041-1345(00)02132-1
© 2001 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
542
Transplantation Proceedings, 33, 542–543 (2001)
FTY720 PREVENTS CHRONIC REJECTION tions, and each animal’s postoperative condition was monitored daily.
Drugs The oral formulation of FTY720 powder was a generous gift from Yoshitomi Pharmaceutical Industries, Ltd. (Osaka, Japan). For in vivo use, the drug was dissolved in a buffered physiological saline to the desired concentration, stored at 4°C, and administered via oral gavage according to the protocol for each experimental group.
Cardiac Transplantation Heterotopic cardiac transplants were placed intra–abdominally into the aorta and vena cava by a modification of the method of Ono and Lindsey. Cold ischemia time was routinely less than 45 minutes. Cardiac activity was assessed daily by abdominal palpation. Rejection, the end–point of graft survival, was defined as the last day of palpable cardiac contraction. Data presented as mean survival times (MST) ⫾ SD were analyzed by the Kaplan–Meier technique and compared for statistical significance using the log– rank test with Bonferroni tests for comparisons among several groups. A value of P ⬍ .05 suggested statistical significance.
Grouping Rats in the control group were transplanted and gavaged with buffered saline (vehicle) only. The dosages of FTY720 in the treatment groups ranged from 0.25 to 2 mg/kg per day for 7 days, starting from the day of transplantation.
543
time (MST) to 46 to 58 days, modestly longer than that of the control group without any treatment (MST ⫽ 21.7 ⫾ 9.6 days, both P ⬍ .05). Increased dosages of FTY720 (1 or 2 mg/kg per day for 7 days) dramatically and significantly extended the MSTs to more than 100 days (both groups, P ⬍ .01). Pathologic examinations of the cardiac allografts sacrificed at day 14 and 21 after transplantation showed alleviation in the severity of vascular changes of chronic rejection in the groups treated with 1 or 2 mg/kg per day for 7 days of FTY720 as compared with those of the control group.
DISCUSSION
FTY720 has been shown to be powerful by itself or as an adjunct immunosuppressant in prolonging allograft survivals1– 4; however, its capacity in preventing chronic rejection has not been reported. Our results suggested that FTY720, a novel immunosuppressant, is effective in prevention of chronic rejection by using a well-established animal model (Lewis to Fisher 344 heterotopic cardiac transplant) of chronic rejection. In conclusion, FTY720 might play an important role in long–term acceptance of rat cardiac allografts. Its clinical applications may help prevent chronic rejection.
Pathological Evaluation Pathologic examinations of allografts were performed at scheduled time points in all groups. The parameters and severity of acute rejection were assessed according to a modified ISHLT grading system,5 and included lymphocytic infiltrations in cardiac myocytes and myocardial interstitium, the extent of endothelitis and vascular wall infiltration in coronary arteries.
REFERENCES
RESULTS
4. Wang ME, Tejpal N, Qu X, et al: Transplantation 65:899, 1998
The rats treated by minimal doses (0.25 or 0.5 mg/kg per day for 7 days) of FTY720 prolonged the mean survival
1. Suzuki S, Enosawa S, Kakefuda T, et al: Transplantation 61:200, 1996 2. Troncoso P, Stepkowski SM, Wang ME, et al: Transplantation 67:145, 1999 3. Chueh SC, Tian L, Wang M, et al: Transplantation 64:1407, 1997
5. Suvarna SK, et al: Heart 79:432, 1998
F
TY720 is a novel immunosuppressant, isolated and chemically modified from the culture filtrate of the ascomycete Isaria sinclarii, and it has been shown to effectively prolong the survival of rat skin, heart, and liver allografts, and the survival of renal allografts in canine and subhuman primates.1,2 FTY720 also induces tolerance in rat cardiac allografts when combined with allochimeric class I MHC antigen3 and potentiates the immunosuppressive effects of cyclosporine (CsA) and/or sirolimus.4 A phase I clinical study with FTY720 in stable renal recipients is being evaluated [BD Kahan, personal communication], but its role in chronic rejection has not been explored before. This study tried to evaluate the effect of FTY720 in preventing chronic rejection of solid organ transplants in a rat model of heterotopic cardiac transplantation.
MATERIALS AND METHODS Animals Adult male inbred Lewis (donor, RT11) and F344 (recipient, RT11v) rats weighing 160 to 250 g were purchased and cared for under the treatment guidelines of the institutional Animal Welfare Committee. All operations were performed under aseptic condi-
From the Departments of Urology (S.-C.C., J.C., M.-K.L.) and Pathology (J.-R.C.), College of Medicine, National Taiwan University, Taipei, Taiwan. Supported by grants from National Science Council, R.O.C., National Taiwan University Hospital, and Chu’s Foundation. Address reprint requests to Shih-Chieh Chueh, MD, Suite 11–13, Clinical Research Building, National Taiwan University Hospital, No. 7, Chung-Shan South Road, Taipei, Taiwan.
Fig. 1. Effect of FTY720 in preventing chronic rejection plotted by Kaplan-Meier survival estimates. See text for detailed description and statistic comparisons.
0041-1345/01/$–see front matter PII S0041-1345(00)02132-1
© 2001 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
542
Transplantation Proceedings, 33, 542–543 (2001)
FTY720 PREVENTS CHRONIC REJECTION tions, and each animal’s postoperative condition was monitored daily.
Drugs The oral formulation of FTY720 powder was a generous gift from Yoshitomi Pharmaceutical Industries, Ltd. (Osaka, Japan). For in vivo use, the drug was dissolved in a buffered physiological saline to the desired concentration, stored at 4°C, and administered via oral gavage according to the protocol for each experimental group.
Cardiac Transplantation Heterotopic cardiac transplants were placed intra–abdominally into the aorta and vena cava by a modification of the method of Ono and Lindsey. Cold ischemia time was routinely less than 45 minutes. Cardiac activity was assessed daily by abdominal palpation. Rejection, the end–point of graft survival, was defined as the last day of palpable cardiac contraction. Data presented as mean survival times (MST) ⫾ SD were analyzed by the Kaplan–Meier technique and compared for statistical significance using the log– rank test with Bonferroni tests for comparisons among several groups. A value of P ⬍ .05 suggested statistical significance.
Grouping Rats in the control group were transplanted and gavaged with buffered saline (vehicle) only. The dosages of FTY720 in the treatment groups ranged from 0.25 to 2 mg/kg per day for 7 days, starting from the day of transplantation.
543
time (MST) to 46 to 58 days, modestly longer than that of the control group without any treatment (MST ⫽ 21.7 ⫾ 9.6 days, both P ⬍ .05). Increased dosages of FTY720 (1 or 2 mg/kg per day for 7 days) dramatically and significantly extended the MSTs to more than 100 days (both groups, P ⬍ .01). Pathologic examinations of the cardiac allografts sacrificed at day 14 and 21 after transplantation showed alleviation in the severity of vascular changes of chronic rejection in the groups treated with 1 or 2 mg/kg per day for 7 days of FTY720 as compared with those of the control group.
DISCUSSION
FTY720 has been shown to be powerful by itself or as an adjunct immunosuppressant in prolonging allograft survivals1– 4; however, its capacity in preventing chronic rejection has not been reported. Our results suggested that FTY720, a novel immunosuppressant, is effective in prevention of chronic rejection by using a well-established animal model (Lewis to Fisher 344 heterotopic cardiac transplant) of chronic rejection. In conclusion, FTY720 might play an important role in long–term acceptance of rat cardiac allografts. Its clinical applications may help prevent chronic rejection.
Pathological Evaluation Pathologic examinations of allografts were performed at scheduled time points in all groups. The parameters and severity of acute rejection were assessed according to a modified ISHLT grading system,5 and included lymphocytic infiltrations in cardiac myocytes and myocardial interstitium, the extent of endothelitis and vascular wall infiltration in coronary arteries.
REFERENCES
RESULTS
4. Wang ME, Tejpal N, Qu X, et al: Transplantation 65:899, 1998
The rats treated by minimal doses (0.25 or 0.5 mg/kg per day for 7 days) of FTY720 prolonged the mean survival
1. Suzuki S, Enosawa S, Kakefuda T, et al: Transplantation 61:200, 1996 2. Troncoso P, Stepkowski SM, Wang ME, et al: Transplantation 67:145, 1999 3. Chueh SC, Tian L, Wang M, et al: Transplantation 64:1407, 1997
5. Suvarna SK, et al: Heart 79:432, 1998