title: Rapamycin combined with anti-CD45RB mAb and IL-10 or with G-CSF induces tolerance in a stringent mouse model of islet transplantation.
abstract: BACKGROUND
  A large pool of preexisting alloreactive effector T cells can cause allogeneic graft rejection following transplantation. However, it is possible to induce transplant tolerance by altering the balance between effector and regulatory T (Treg) cells. Among the various Treg-cell types, Foxp3(+)Treg and IL-10-producing T regulatory type 1 (Tr1) cells have frequently been associated with tolerance following transplantation in both mice and humans. Previously, we demonstrated that rapamycin+IL-10 promotes Tr1-cell-associated tolerance in Balb/c mice transplanted with C57BL/6 pancreatic islets. However, this same treatment was unsuccessful in C57BL/6 mice transplanted with Balb/c islets (classified as a stringent transplant model). We accordingly designed a protocol that would be effective in the latter transplant model by simultaneously depleting effector T cells and fostering production of Treg cells. We additionally developed and tested a clinically translatable protocol that used no depleting agent.
  
  
  RESULTS
  Diabetic C57BL/6 mice were transplanted with Balb/c pancreatic islets. Recipient mice transiently treated with anti-CD45RB mAb+rapamycin+IL-10 developed antigen-specific tolerance. During treatment, Foxp3(+)Treg cells were momentarily enriched in the blood, followed by accumulation in the graft and draining lymph node, whereas CD4(+)IL-10(+)IL-4(-) T (i.e., Tr1) cells localized in the spleen. In long-term tolerant mice, only CD4(+)IL-10(+)IL-4(-) T cells remained enriched in the spleen and IL-10 was key in the maintenance of tolerance. Alternatively, recipient mice were treated with two compounds routinely used in the clinic (namely, rapamycin and G-CSF); this drug combination promoted tolerance associated with CD4(+)IL-10(+)IL-4(-) T cells.
  
  
  CONCLUSIONS
  The anti-CD45RB mAb+rapamycin+IL-10 combined protocol promotes a state of tolerance that is IL-10 dependent. Moreover, the combination of rapamycin+G-CSF induces tolerance and such treatment could be readily translatable into the clinic.
authors.affiliation: San Raffaele Diabetes Research Institute, San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Gagliani
authors.forename: Silvia
authors.initials: S
authors.lastname: Gregori
authors.forename: Tatiana
authors.initials: T
authors.lastname: Jofra
authors.forename: Andrea
authors.initials: A
authors.lastname: Valle
authors.forename: Angela
authors.initials: A
authors.lastname: Stabilini
authors.forename: David M
authors.initials: DM
authors.lastname: Rothstein
authors.forename: Mark
authors.initials: M
authors.lastname: Atkinson
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Roncarolo
authors.forename: Manuela
authors.initials: M
authors.lastname: Battaglia
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D015704:CD4 Antigens / Q000378:metabolism; D004359:Drug Therapy, Combination; D000939:Epitopes / Q000276:immunology; D005260:Female; D051858:Forkhead Transcription Factors / Q000378:metabolism; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D007108:Immune Tolerance / Q000187:drug effects*; D016753:Interleukin-10 / Q000494:pharmacology*; D053645:Interleukin-2 Receptor alpha Subunit / Q000378:metabolism; D016381:Islets of Langerhans Transplantation; D017493:Leukocyte Common Antigens / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D023421:Models, Animal; D020123:Sirolimus / Q000494:pharmacology*; D013154:Spleen / Q000187:drug effects / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors; D014184:Transplantation, Homologous
chemical_list: D000911:Antibodies, Monoclonal; D015704:CD4 Antigens; D000939:Epitopes; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D053645:Interleukin-2 Receptor alpha Subunit; D016753:Interleukin-10; D016179:Granulocyte Colony-Stimulating Factor; D017493:Leukocyte Common Antigens; D020123:Sirolimus