Islet transplantation in the discordant tilapia-to-mouse model: a novel application of alginate microencapsulation in the study of xenograft rejection

Background. Tilapia islet xenograft rejection is characterized by infiltration with macrophages (M&phgr;s), eosinophils (E&phgr;s), and T lymphocytes. The presence of these cells indicates they contribute to rejection; therefore, an attempt was made to assess their role through host immunomodulation. Methods. Tilapia islet cells were transplanted under the kidney capsule of streptozotocin diabetic Balb/c mice, which were then treated with one of several immunomodulatory regimes targeting M&phgr;s, E&phgr;s, or T cells. M&phgr;s were depleted using either silica or liposome-entrapped Cl2MDP. E&phgr; migration was blocked using monoclonal antibodies (mAbs) targeting interleukin (IL)-4 or IL-5. T-cell function was altered with mAbs targeting CD3, CD4, or CD8. Finally, T helper (Th)1 and Th2 activity was altered by depleting essential Th1 or Th2 cytokines with mAbs or by promoting a Th1 response with the injection of exogenous IL-12. The effects of antibody-mediated immunomodulation on graft survival were initially screened by cotransplanting alginate-encapsulated, mAb-secreting hybridoma cells into the peritoneal cavity at the time of islet transplantation. Significant prolongation was then confirmed using purified antibodies injected at the time of islet transplantation. Rejected grafts were examined histologically, and immunohistochemistry was used to assess the cellular infiltrates for each of the treatment groups. Results. Modulation of M&phgr;s and E&phgr;s alone did not significantly delay functional rejection of tilapia islet grafts (maximal mean graft survival time [mGST]=7.1±1.7 and 9.4±3.4, respectively) compared with untreated controls (mGST=8.2±1.0). Treatment of transplanted animals with antibodies against CD3 or CD4 significantly promoted graft survival (maximal mGST=16.3±5.8 and 34.0±11.6, respectively), whereas targeting CD8 and Th1 and Th2 cytokines showed no prolonging effect (maximal mGST=7.8±2.9 and 9.5±4.3, respectively). Conclusion. Our results indicate that rejection in the tilapia-to-mouse model follows a pattern similar to other models of discordant islet cell xenotransplantation.

[1]  I. G. Young,et al.  Immune mechanisms associated with the rejection of fetal murine proislet allografts and pig proislet xenografts: comparison of intragraft cytokine mRNA profiles. , 1999, Transplantation.

[2]  G. Karupiah,et al.  Analysis of the Th1/Th2 Paradigm in Transplantation: Interferon-γ Deficiency Converts Th1-Type Proislet Allograft Rejection to a Th2-Type Xenograft-Like Response , 1999, Cell transplantation.

[3]  P. Lacy,et al.  Low-temperature culture of human islets or in vivo treatment with L3T4 antibody produces a marked prolongation of islet human-to-mouse xenograft survival. , 1987, Proceedings of the National Academy of Sciences of the United States of America.

[4]  H. Ljunggren,et al.  Xenograft rejection of porcine islet-like cell clusters in normal and natural killer cell-depleted mice. , 1996, Transplantation.

[5]  J. Wright,et al.  Cell Therapy for Diabetes Using Piscine Islet Tissue , 2001, Cell transplantation.

[6]  M. Barna,et al.  IL-12 promotes enhanced recovery from vesicular stomatitis virus infection of the central nervous system. , 1995, Journal of immunology.

[7]  O. Korsgren,et al.  THE MAIN INFILTRATING CELL IN XENOGRAFT REJECTION IS A CD4+ MACROPHAGE AND NOT A T LYMPHOCYTE , 1995, Transplantation.

[8]  J. Chapman,et al.  The cytokine and histological response in islet xenograft rejection is dependent upon species combination. , 1997, Transplantation.

[9]  N. Van Rooijen,et al.  Elimination, blocking, and activation of macrophages: three of a kind? , 1997, Journal of leukocyte biology.

[10]  R. Ceredig,et al.  Role of CD4+ T-Lymphocytes in Rejection by Mice of Fetal Pig Proislet Xenografts , 1989, Diabetes.

[11]  P. Morel,et al.  Crossregulation between Th1 and Th2 cells. , 1998, Critical reviews in immunology.

[12]  C. Morris,et al.  Intragraft expression of cytokine transcripts during pig proislet xenograft rejection and tolerance in mice. , 1995, Journal of immunology.

[13]  H. Yang,et al.  Islet allograft rejection in rats: a time course study characterizing adhesion molecule expression, MHC expression, and infiltrate immunophenotypes. , 1998, Cell transplantation.

[14]  P. Lacy,et al.  Prolongation of islet xenograft survival without continuous immunosuppression. , 1980, Science.

[15]  G. Papaccio,et al.  Macrophages and antioxidant status in the NOD mouse pancreas , 1998, Journal of cellular biochemistry.

[16]  L. Harrison,et al.  Evidence that macrophages are required for T-cell infiltration and rejection of fetal pig pancreas xenografts in nonobese diabetic mice. , 1998, Transplantation.

[17]  R. Gill,et al.  Rejection of pancreatic islet xenografts does not require CD8+ T-lymphocytes. , 1992, Transplantation proceedings.

[18]  J. Kovarik,et al.  Expression of both Th1 and Th2 cytokines correlates with the histological rejection of MHC‐matched and MHC‐mismatched foetal pancreas allografts in mice , 1997, Immunology and cell biology.

[19]  M. Zand,et al.  On histocompatibility barriers, Th1 to Th2 immune deviation, and the nature of the allograft responses. , 1998, Journal of immunology.

[20]  S. Gordon,et al.  Transfer of diabetes in mice prevented by blockade of adhesion-promoting receptor on macrophages , 1990, Nature.

[21]  R. Gill,et al.  Donor antigen-presenting cell-independent rejection of islet xenografts. , 1995, Transplantation.

[22]  O. Korsgren,et al.  Xenograft rejection of porcine islet-like cell clusters in normal, interferon-gamma, and interferon-gamma receptor deficient mice. , 1997, Transplantation.

[23]  H. Kolb,et al.  Administration of silica or monoclonal antibody to Thy-1 prevents low-dose streptozotocin-induced diabetes in mice. , 1986, Immunology letters.

[24]  A. Sher,et al.  Diversity of Cytokine Synthesis and Function of Mouse CD4+ T Cells , 1991, Immunological reviews.

[25]  R. Gill,et al.  CD4+ T cells are both necessary and sufficient for islet xenograft rejection. , 1994, Transplantation proceedings.

[26]  T. Mandel,et al.  Pancreatic islet xenotransplantation: the potential for tolerance induction. , 2000, Immunology today.

[27]  C. Simeonovic.  Xenogeneic islet transplantation , 1999, Xenotransplantation.

[28]  H. Yang,et al.  A method for mass harvesting islets (Brockmann bodies) from teleost fish. , 1995, Cell transplantation.

[29]  O. Korsgren,et al.  Pig islet xenograft rejection is markedly delayed in macrophage‐depleted mice: a study in streptozotocin diabetic animals , 2000, Xenotransplantation.

[30]  P. Weller,et al.  CD4-mediated stimulation of human eosinophils: lymphocyte chemoattractant factor and other CD4-binding ligands elicit eosinophil migration , 1991, The Journal of experimental medicine.

[31]  P. Lacy,et al.  Effect of transplantation site and alpha L3T4 treatment on survival of rat, hamster, and rabbit islet xenografts in mice. , 1989, Transplantation.

[32]  M. Koulmanda,et al.  The effect of a depleting anti-CD4 monoclonal antibody on T cells and fetal pig islet xenograft survival in various strains of mice. , 1995, Transplant immunology.

[33]  O. Korsgren,et al.  Interleukin-6 in islet xenograft rejection , 2001, Transplant international : official journal of the European Society for Organ Transplantation.

[34]  N. Arai.  Modulation of systemic cytokine levels by implantation of alginate encapsulated cells , 2002 .

[35]  P. Marchetti,et al.  T-helper 1 and 2 activation with fresh or cultured allo- or xenoislets. , 1997, Transplantation proceedings.

[36]  A. Ramsay,et al.  Eosinophils are not required for the rejection of neovascularized fetal pig proislet xenografts in mice. , 1997, Journal of immunology.