- Email: [email protected]
Administration of exogenous interleukin-2 enhances obliterative airway disease in cyclosporine-treated rats following tracheal allografts
Administration of Exogenous Interleukin-2 Enhances Obliterative Airway Disease in Cyclosporine-Treated Rats Following Tracheal Allografts M. Takao, Y. Gu, A. Shimamoto, K. Adachi, S. Namikawa, and I. Yada
T
HE PATHOGENESIS of obliterative bronchiolitis (OB) following lung transplantation may involve an immune-mediated injury of the airway wall, and therapy frequently includes augmentation of immunosuppression.1 However, long-term follow-up of experimental rat lung allograft recipients treated with a short course of cyclosporine (CsA) fails to reproduce OB.2,3 We hypothesized that administration of exogenous interleukin-2 (IL-2) would induce immune-mediated injury in the long-term lung allografts that mimics OB. To evaluate this, we administered exogenous IL-2 in a heterotopic tracheal transplant model in rats following treatment with CsA. MATERIALS AND METHODS LEW (RT-1l) rats were recipients of BN (RT-1n) tracheal segments transplanted into the omentum by a modification of a technique previously performed in mice.4
Fig 1. Tracheal allografts treated with CsA (25 mg/kg, IM) on days 2 and 3 after transplantation (Tx). (a) Killed 4 weeks after transplant. (b) Killed 4 months after transplant.
Experiment 1 CsA (25 mg/kg, intramuscularly [IM]) was given on days 2 and 3 following transplantation (Tx), and the rats (n 5 10) were killed at weekly intervals from 1 week to 5 weeks and 4 months following transplant. As a control, three recipients were not treated with CsA.
gressed following CsA withdrawal. However, the pathologic findings in these tracheal luminal obstructions are different from the typical ones observed in human lung transplants (Fig 1).
Experiment 2
Experiment 2
CsA (25 mg/kg on days 2 and 3, followed by 5 mg/kg on days 4 to 27 after transplant, IM) with or without IL-2 (90,000 IU on days 15 to 19 and 22 to 26 after transplant, intraperitoneally [IP]) was given and the rats (n 5 13) were killed at 4, 6, 8, and 10 weeks following transplant (ie, 0, 2, 4, and 6 weeks after CsA withdrawal). Tracheal grafts were fixed in 10% neutral buffered formalin solution for hematoxylin-eosin staining. They were vertically cut into three sections and examined semiquantitatively for the mean percent of airway narrowing and extent of peritracheal lymphocyte infiltration.
Airway narrowing was observed 4 weeks after CsA withdrawal and increased afterwards in the group not given IL-2. IL-2 induced significant peritracheal lymphocyte infiltration and accelerated the process of intraluminal fibrosis, which was observed from 2 to 4 weeks after CsA withdrawal (Fig 2). At 4 weeks the tracheal lumen was almost com-
RESULTS Experiment 1
Complete obstruction of the tracheal lumen was observed 4 weeks following transplant in rats not treated with CsA. Although CsA reduced airway narrowing in heterotopic tracheal allografts, obstruction of the airway lumen pro0041-1345/99/$–see front matter PII S0041-1345(98)01492-4
From the Department of Thoracic Surgery, Mie University, Mie, Japan. Supported in part by Grants-in-Aid for Scientific Research from the Ministry of Education, Science and Culture of Japan (C-07671461, 09877258). Address reprint requests to Dr Motoshi Takao, Department of Thoracic Surgery, School of Medicine, Mie University, 2-174 Edobashi, Tsu, Mie 514-8507, Japan. E-mail: takao@clin. medic.mie-u.ac.jp. © 1999 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
180
Transplantation Proceedings, 31, 180–181 (1999)
EXOGENOUS IL-2 ADMINISTRATION
181
after CsA withdrawal. In addition, administration of exogenous IL-2 enhanced peritracheal lymphocyte infiltration and obstructive airway disease in CsA-treated tracheal allografts. These luminal obstructions are more similar to the typical findings observed in OB patients following lung transplant. These luminal obstructions in allotransplanted trachea appear to reflect immune-mediated injury of the airway wall, because isografted trachea (BN to BN) do not demonstrate any obstruction, and administration of exogenous IL-2 dose induces peritracheal mononuclear cell infiltration, but not luminal narrowing (data was not shown). These results suggest that obstructive airway disease following transplantation is immune mediated in allografts accepted long term and that the OB lesion can be reproduced in the rat lung allograft model after administration of exogenous IL-2. Fig 2. Tracheal allografts treated with CsA (25 mg/kg on days 2 and 3 followed by 5 mg/kg on days 4 to 27 after transplant, IM) killed at 6 weeks after transplant (ie, 2 weeks after CsA withdrawal). (a) Without IL-2. (b) With IL-2 (90,000 IU on days 15 to 19 and 22 to 26 after transplant, IP).
ACKNOWLEDGMENTS
pletely occluded. Peritracheal lymphocyte infiltration was followed by intraluminal narrowing in both groups.
REFERENCES
DISCUSSION
A short course of CsA into tracheal allotransplanted rats failed to prevent luminal obstruction (experiment 1). Even prolonged 4-week CsA administration after transplant (experiment 2) did not prevent obstruction of the airway lumen
IL-2 (human recombinant interleukin-2, Immunase) was a kind gift from Shionogi Pharmaceuticals (Osaka, Japan).
1. Sharples LD, Tamm M, McNeil K, et al: Transplantation 61:560, 1996 2. Uyama T, Winter JB, Groen G, et al: Transplantation 54:809, 1992 3. Winter JB, Gouw ASH, Groen M, et al: Transplantation 57:418, 1994 4. Hertz MI, Jessurun J, King MB, et al: Am J Pathol 142:1945, 1993
T
HE PATHOGENESIS of obliterative bronchiolitis (OB) following lung transplantation may involve an immune-mediated injury of the airway wall, and therapy frequently includes augmentation of immunosuppression.1 However, long-term follow-up of experimental rat lung allograft recipients treated with a short course of cyclosporine (CsA) fails to reproduce OB.2,3 We hypothesized that administration of exogenous interleukin-2 (IL-2) would induce immune-mediated injury in the long-term lung allografts that mimics OB. To evaluate this, we administered exogenous IL-2 in a heterotopic tracheal transplant model in rats following treatment with CsA. MATERIALS AND METHODS LEW (RT-1l) rats were recipients of BN (RT-1n) tracheal segments transplanted into the omentum by a modification of a technique previously performed in mice.4
Fig 1. Tracheal allografts treated with CsA (25 mg/kg, IM) on days 2 and 3 after transplantation (Tx). (a) Killed 4 weeks after transplant. (b) Killed 4 months after transplant.
Experiment 1 CsA (25 mg/kg, intramuscularly [IM]) was given on days 2 and 3 following transplantation (Tx), and the rats (n 5 10) were killed at weekly intervals from 1 week to 5 weeks and 4 months following transplant. As a control, three recipients were not treated with CsA.
gressed following CsA withdrawal. However, the pathologic findings in these tracheal luminal obstructions are different from the typical ones observed in human lung transplants (Fig 1).
Experiment 2
Experiment 2
CsA (25 mg/kg on days 2 and 3, followed by 5 mg/kg on days 4 to 27 after transplant, IM) with or without IL-2 (90,000 IU on days 15 to 19 and 22 to 26 after transplant, intraperitoneally [IP]) was given and the rats (n 5 13) were killed at 4, 6, 8, and 10 weeks following transplant (ie, 0, 2, 4, and 6 weeks after CsA withdrawal). Tracheal grafts were fixed in 10% neutral buffered formalin solution for hematoxylin-eosin staining. They were vertically cut into three sections and examined semiquantitatively for the mean percent of airway narrowing and extent of peritracheal lymphocyte infiltration.
Airway narrowing was observed 4 weeks after CsA withdrawal and increased afterwards in the group not given IL-2. IL-2 induced significant peritracheal lymphocyte infiltration and accelerated the process of intraluminal fibrosis, which was observed from 2 to 4 weeks after CsA withdrawal (Fig 2). At 4 weeks the tracheal lumen was almost com-
RESULTS Experiment 1
Complete obstruction of the tracheal lumen was observed 4 weeks following transplant in rats not treated with CsA. Although CsA reduced airway narrowing in heterotopic tracheal allografts, obstruction of the airway lumen pro0041-1345/99/$–see front matter PII S0041-1345(98)01492-4
From the Department of Thoracic Surgery, Mie University, Mie, Japan. Supported in part by Grants-in-Aid for Scientific Research from the Ministry of Education, Science and Culture of Japan (C-07671461, 09877258). Address reprint requests to Dr Motoshi Takao, Department of Thoracic Surgery, School of Medicine, Mie University, 2-174 Edobashi, Tsu, Mie 514-8507, Japan. E-mail: takao@clin. medic.mie-u.ac.jp. © 1999 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
180
Transplantation Proceedings, 31, 180–181 (1999)
EXOGENOUS IL-2 ADMINISTRATION
181
after CsA withdrawal. In addition, administration of exogenous IL-2 enhanced peritracheal lymphocyte infiltration and obstructive airway disease in CsA-treated tracheal allografts. These luminal obstructions are more similar to the typical findings observed in OB patients following lung transplant. These luminal obstructions in allotransplanted trachea appear to reflect immune-mediated injury of the airway wall, because isografted trachea (BN to BN) do not demonstrate any obstruction, and administration of exogenous IL-2 dose induces peritracheal mononuclear cell infiltration, but not luminal narrowing (data was not shown). These results suggest that obstructive airway disease following transplantation is immune mediated in allografts accepted long term and that the OB lesion can be reproduced in the rat lung allograft model after administration of exogenous IL-2. Fig 2. Tracheal allografts treated with CsA (25 mg/kg on days 2 and 3 followed by 5 mg/kg on days 4 to 27 after transplant, IM) killed at 6 weeks after transplant (ie, 2 weeks after CsA withdrawal). (a) Without IL-2. (b) With IL-2 (90,000 IU on days 15 to 19 and 22 to 26 after transplant, IP).
ACKNOWLEDGMENTS
pletely occluded. Peritracheal lymphocyte infiltration was followed by intraluminal narrowing in both groups.
REFERENCES
DISCUSSION
A short course of CsA into tracheal allotransplanted rats failed to prevent luminal obstruction (experiment 1). Even prolonged 4-week CsA administration after transplant (experiment 2) did not prevent obstruction of the airway lumen
IL-2 (human recombinant interleukin-2, Immunase) was a kind gift from Shionogi Pharmaceuticals (Osaka, Japan).
1. Sharples LD, Tamm M, McNeil K, et al: Transplantation 61:560, 1996 2. Uyama T, Winter JB, Groen G, et al: Transplantation 54:809, 1992 3. Winter JB, Gouw ASH, Groen M, et al: Transplantation 57:418, 1994 4. Hertz MI, Jessurun J, King MB, et al: Am J Pathol 142:1945, 1993