The focus of this proposal is to develop a novel """"""""conditioning"""""""" approach that will replace myelotoxic agents to establish chimerism in NOD mice. We will induce immune deviation to promote host-versus-graft hyporesponsiveness, thereby giving the hematopoietic stem cell (HSC) an opportunity to engraft and establish subsequent self-perpetuating deletional tolerance to islet allografts. Our recent studies in a mouse model suggest that the primary role for conditioning for HSC transplantation is to suppress host-versus-graft alloreactivity, rather than to prepare vacant niches in the recipient's bone marrow compartment. This observation suggests that one could replace myelotoxic agents with antigen-specific approaches to induce host-versus-graft hyporeactivity or anergy at the time of HSC transplantation. As the mechanisms underlying T cell activation are defined, highly specific approaches to suppress this alloreactivity have emerged.
In AIM I. we will ESTABLISH CHIMERISM THROUGH IMMUNE DEVIATION OF THE RECIPIENT. We will immunomodulate the recipient: (a) targeting alloreactive cells in the host microenvironment; (b) inducing anergy and/or antigen-specific apoptosis of alloreactive host cells; and (c) through generation of regulatory T cells (Treg), and develop a novel nonmyeloablative conditioning regimen to induce antigen-specific hyporesponsiveness to the HSC and islet allografts. Cell-based therapies have great potential for inducing transplantation tolerance. Of greatest interest are the new subpopulations of bone marrow-derived dendritic cells (DC) that have recently been shown to be potently tolerogenic in vitro under certain circumstances. We are the first to demonstrate an in vivo engraftment-enhancing effect for precursor plasmacytoid DC (p-preDC). The exploitation of this discovery in vivo and its potential to reduce the need for myelotoxic conditioning has not yet been tested. Hematopoietic growth factors have also been used to drive the immune response to a tolerogenic T helper 2 (Th2) phenotype through production of p-preDC or other tolerance-promoting cells (graft facilitating cells {FC}) that in turn generate Treg.
In AIM II, we will USE PRE-TRANSPLANT IMMUNOMODULATION OF THE DONOR WITH HEMATOPOIETIC GROWTH FACTORS TO GENERATE TOLEROGENIC CELLS IN THE HSC ALLOGRAFT. We will use these factors and the cells they generate to modulate the tolerogenicity of the donor marrow inoculum in vivo to tip the immune milieu in favor of graft acceptance, enhancing bone marrow chimerism without myelotoxic conditioning. We will examine the mechanism by which this occurs and identify which cell types in the graft are critical to tolerance induction. P-preDC exposed to apoptotic donor antigens are potently tolerizing in vitro through generation of Treg. The therapeutic application of this approach has not been tested in vivo.
In AIM III, we will USE EX VIVO IMMUNOMODULATION OF THE MARROW to expand p-preDC and FC and induce a tolerogenic inoculum for HSC transplantation. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK069766-04
Application #
7488881
Study Section
Transplantation, Tolerance, and Tumor Immunology (TTT)
Program Officer
Appel, Michael C
Project Start
2005-09-01
Project End
2010-08-31
Budget Start
2008-09-01
Budget End
2009-08-31
Support Year
4
Fiscal Year
2008
Total Cost
$300,509
Indirect Cost
Name
University of Louisville
Department
Surgery
Type
Schools of Medicine
DUNS #
057588857
City
Louisville
State
KY
Country
United States
Zip Code
40292
Xu, Hong; Yan, Jun; Zhu, Ziqiang et al. (2013) A critical role for the TLR4/TRIF pathway in allogeneic hematopoietic cell rejection by innate immune cells. Cell Transplant 22:2367-80
Xu, Hong; Ramsey, Deborah M; Wu, Shengli et al. (2013) Simultaneous bone marrow and composite tissue transplantation in rats treated with nonmyeloablative conditioning promotes tolerance. Transplantation 95:301-8
Xu, Hong; Zhu, Ziqiang; Huang, Yiming et al. (2012) Innate and adaptive immune responses are tolerized in chimeras prepared with nonmyeloablative conditioning. Transplantation 93:469-76
Leventhal, Joseph; Huang, Yiming; Xu, Hong et al. (2012) Novel regulatory therapies for prevention of Graft-versus-host disease. BMC Med 10:48
Leventhal, Joseph; Abecassis, Michael; Miller, Joshua et al. (2012) Chimerism and tolerance without GVHD or engraftment syndrome in HLA-mismatched combined kidney and hematopoietic stem cell transplantation. Sci Transl Med 4:124ra28
Cardenas, Paul A; Huang, Yiming; Ildstad, Suzanne T (2011) The role of pDC, recipient T(reg) and donor T(reg) in HSC engraftment: Mechanisms of facilitation. Chimerism 2:65-70
Wu, Shengli; Xu, Hong; Chen, Bo et al. (2011) Sensitized recipients exhibit accelerated but not hyperacute rejection of vascularized composite tissue allografts. Transplantation 92:627-33
Bozulic, Larry D; Huang, Yiming; Xu, Hong et al. (2011) Differential outcomes in prediabetic vs. overtly diabetic NOD mice nonmyeloablatively conditioned with costimulatory blockade. Exp Hematol 39:977-85
Huang, Yiming; Bozulic, Larry D; Miller, Thomas et al. (2011) CD8α+ plasmacytoid precursor DCs induce antigen-specific regulatory T cells that enhance HSC engraftment in vivo. Blood 117:2494-505
Huang, Yiming; Enzmann, Volker; Ildstad, Suzanne T (2011) Stem cell-based therapeutic applications in retinal degenerative diseases. Stem Cell Rev 7:434-45

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