Immune cell niches are microenvironments that support the survival of specific hematopoietic cells. The size of a given niche is dependent on survival and proliferation signals provided. Modulation of niche size can be a useful therapeutic tool, and a better understanding of the factors that control the size of immune cell niches can lead to more targeted therapies. Here bone marrow and thymic niches were modulated with tyrosine kinase inhibition to achieve increased engraftment following stem cell transplantation (SCT). SCT resulting in mixed chimerism is curative for several benign blood diseases, but toxicities associated with myeloablative and cytotoxic conditioning regimens limit the application of SCT. Sunitinib inhibits multiple tyrosine kinases including KIT, an essential survival signal within the hematopoietic stem cell and thymic progenitor niches. Sunitinib therapy diminishes hematopoietic and thymic progenitor cells in mice and enhances accessibility of marrow and thymic niches to transplanted bone marrow. This provides a novel, non-cytotoxic approach to accomplish mixed hematopoietic chimerism. The observation that T cells undergo increased proliferation and accumulate in IL-7R deficient mice compared to other lymphopenic hosts raised questions about the factors that control the size of the T cell niche. Understanding these factors is useful in designing therapeutics to increase T cell responses for treatment of many diseases including cancer. Dendritic cells (DCs) are well known for their ability to modulate T cell responses; however, very little is known about the role of IL-7R signaling on DCs. The data presented here show that bone marrow derived DCs treated with IL-7 were less able to induce T cell proliferation in coculture. In vivo systems using CD11cDTR mice showed a role for IL-7 signaling on CD11c+ cells in T cell homeostasis. Together these data suggest that IL-7R signaling on DCs is important for regulating the size of the T cell niche.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:588400 |
| Date | January 2012 |
| Creators | Fewkes, Natasha Marie |
| Contributors | Powrie, Fiona; Mackall, Crystal L. |
| Publisher | University of Oxford |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://ora.ox.ac.uk/objects/uuid:cdd4e490-3b49-4f7e-839e-3a48ae34aafe |
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