Experimental Hematology Unit
Contributions
Type: Oral Presentation
Presentation during EHA20: From 13.06.2015 16:00 to 13.06.2015 16:15
Location: Room Lehar 3 + 4
Background
In spite of the efficacy of allogeneic Hematopoietic Stem Cell Transplantation (allo-HSCT) in curing Acute Myeloid Leukemia (AML), post-transplantation relapse remain a major issue. According to the “leukemia immunoediting” hypothesis relapse may be due to the outgrowth of immune-resistant leukemic variants upon the selective pressure of the transplanted immune system. Immunodeficient mouse models might represent a precious tool to provide insights into the immunobiology of this phenomenon.
Aims
In the present study, we set up a novel mouse-human chimeric model to characterize the biology of AML engraftment into mice and to model its interactions with adoptively transferred human T cells.
Methods
AML samples harvested at diagnosis from 26 patients were purified and infused into non-irradiated immunodeficient NOD/SCID γ-chain null (NSG) mice. Upon leukemia engraftment mice were sacrificed and purified leukemic cells were reinfused in serial recipients. To mimic immune pressure, mice received serial infusions of human T cells, either autologous or allogeneic (HLA-identical, HLA-matched, HLA-haploidentical or HLA-disparate) to the AML. At sacrifice, leukemic cells were FACS-purified and gene expression profile was analyzed using Illumina microarray. Deregulated genes were identified by pairwise LIMMA analysis. Gene Ontology and Gene Set Enrichment Analysis curated databases were interrogated to identify deregulated processes.
Results
Twelve out of 26 primary samples (46%) generated AML xenografts. Engraftment into mice significantly correlated with poor patient prognosis, and in particular with relapse after allo-HSCT (p=0.005). Infused leukemic cells reproducibly engrafted and exponentially expanded in mice, displaying a stable gene expression profile amongst littermates and upon serial transfer. Noticeably, serially transplanted AML exhibited an accelerated and more aggressive growth kinetic, with selective deregulation of genes involved in cell proliferation, myeloid differentiation and sister chromathide organization during mythosis.
Four selected AML xenografts were challenged in vivo with serial injection of T cells. We observed rapid and complete eradication of AML after treatment with HLA-disparate and HLA-haploidentical T cells from 20/20 treated mice. In all the cases, HLA matched cells harvested from unrelated donors were effective in controlling disease outgrowth. On the contrary HLA-identical T cells granted only temporary control in 6/10 mice, while autologous T cells were completely inefficacious in 14/14 mice.
Leukemic blasts subjected to T cell-mediated immune pressure showed a specific and reproducible gene signature, with selective deregulation of genes involved in immune processes. Among the top-ranked upregulated genes we identified those related to response to interferons, comprising proteasome and immunoproteasome subunits, as well as molecules involved in antigen processing and presentation, comprising HLA Class I and II molecules. This data were further validated in vivo, observing in real-time the activation of this transcriptional program during the antileukemic immune response. Interestingly, in several experiments upon initial eradication we documented AML recurrence, with patterns which were highly reminiscent of post-transplantation relapses in human.
Summary
The model we set up represents a precious asset to mimic and decipher the complex dynamics of allo-HSCT, and thus to provide novel insights into the mechanisms of graft-versus-leukemia effect and relapse.
Keyword(s): Allogeneic hematopoietic stem cell transplant, AML, Gene expression profile, Mouse model
Session topic: Stem cell transplantation: Experimental
Type: Oral Presentation
Presentation during EHA20: From 13.06.2015 16:00 to 13.06.2015 16:15
Location: Room Lehar 3 + 4
Background
In spite of the efficacy of allogeneic Hematopoietic Stem Cell Transplantation (allo-HSCT) in curing Acute Myeloid Leukemia (AML), post-transplantation relapse remain a major issue. According to the “leukemia immunoediting” hypothesis relapse may be due to the outgrowth of immune-resistant leukemic variants upon the selective pressure of the transplanted immune system. Immunodeficient mouse models might represent a precious tool to provide insights into the immunobiology of this phenomenon.
Aims
In the present study, we set up a novel mouse-human chimeric model to characterize the biology of AML engraftment into mice and to model its interactions with adoptively transferred human T cells.
Methods
AML samples harvested at diagnosis from 26 patients were purified and infused into non-irradiated immunodeficient NOD/SCID γ-chain null (NSG) mice. Upon leukemia engraftment mice were sacrificed and purified leukemic cells were reinfused in serial recipients. To mimic immune pressure, mice received serial infusions of human T cells, either autologous or allogeneic (HLA-identical, HLA-matched, HLA-haploidentical or HLA-disparate) to the AML. At sacrifice, leukemic cells were FACS-purified and gene expression profile was analyzed using Illumina microarray. Deregulated genes were identified by pairwise LIMMA analysis. Gene Ontology and Gene Set Enrichment Analysis curated databases were interrogated to identify deregulated processes.
Results
Twelve out of 26 primary samples (46%) generated AML xenografts. Engraftment into mice significantly correlated with poor patient prognosis, and in particular with relapse after allo-HSCT (p=0.005). Infused leukemic cells reproducibly engrafted and exponentially expanded in mice, displaying a stable gene expression profile amongst littermates and upon serial transfer. Noticeably, serially transplanted AML exhibited an accelerated and more aggressive growth kinetic, with selective deregulation of genes involved in cell proliferation, myeloid differentiation and sister chromathide organization during mythosis.
Four selected AML xenografts were challenged in vivo with serial injection of T cells. We observed rapid and complete eradication of AML after treatment with HLA-disparate and HLA-haploidentical T cells from 20/20 treated mice. In all the cases, HLA matched cells harvested from unrelated donors were effective in controlling disease outgrowth. On the contrary HLA-identical T cells granted only temporary control in 6/10 mice, while autologous T cells were completely inefficacious in 14/14 mice.
Leukemic blasts subjected to T cell-mediated immune pressure showed a specific and reproducible gene signature, with selective deregulation of genes involved in immune processes. Among the top-ranked upregulated genes we identified those related to response to interferons, comprising proteasome and immunoproteasome subunits, as well as molecules involved in antigen processing and presentation, comprising HLA Class I and II molecules. This data were further validated in vivo, observing in real-time the activation of this transcriptional program during the antileukemic immune response. Interestingly, in several experiments upon initial eradication we documented AML recurrence, with patterns which were highly reminiscent of post-transplantation relapses in human.
Summary
The model we set up represents a precious asset to mimic and decipher the complex dynamics of allo-HSCT, and thus to provide novel insights into the mechanisms of graft-versus-leukemia effect and relapse.
Keyword(s): Allogeneic hematopoietic stem cell transplant, AML, Gene expression profile, Mouse model
Session topic: Stem cell transplantation: Experimental