Regenerative granulopoietic failure is common in patients infected by HIV-1, a phenomenon we and others have attributed to dysfunction of HIV-1-infected bone marrow accessory cells; microvascular endothelial cells and mononuclear phagocytes in particular.(1) We have found that HIV-1 infected bone marrow stromal cells (infected ex-vivo or in-vivo) are less supportive of granulocyte-macrophage progenitor cell (CFU-GM) survival in co-cultures and, after stimulation with IL-1 produce significantly lower amounts of IL-6, GM-CSF and G-CSF than do uninfected stromal cells. We have also found that while infected stromal cells have a reduced capacity to support granulopoiesis, they are more supportive of growth/survival of lymphoma cells with the germinal center phenotype. Using vesicular stomatitis virus-G (VSV-G) pseudotyped HIV-1 vectors with inactivating mutations of various HIV-1 regulatory/accessory genes to transduce normal bone marrow stromal cells, we have determined that the two suppressive effects of HIV-1 on granulopoietic support function require HIV-1 vpr.
The aims of this proposal are designed to test the hypothesis that HIV-1 vpr is necessary and sufficient to account for the observed changes in hematopoietic support function of bone marrow stroma.
Our first aim i s to identify the molecular points of suppression of GM-CSF, G-CSF, and IL-6 gene expression by HIV-1 and HIV-1 vpr and to determine whether induction of these factors by TNF-alpha and CD40 ligand (CD40L) is similarly suppressed.
Our second aim i s to test the cause-and-effect relationship between GM-CSF, IL-6 and G-CSF inhibition and the inhibitory effects of HIV-1-infected bone marrow stromal cells on survival of CFU-GM.
Our third aim i s to use both retroviral mediated gene transfer of and tet-responsive vectors expressing HIV-1 vpr and other accessory proteins to determine the sufficiency of HIV-1 vpr in; (a) blunting bone marrow stromal cell responses to IL-1 (and other inducing factors including CD40L and TNF-alpha), (b) reducing the capacity of stroma to support CFU-GM, and (c) enhancing the survival of lymphoma cells with the germinal center phenotype. Results of these studies should clarify the molecular pathogenesis of regenerative granulopoietic failure in HIV-1 seropositive patients and may also reveal determinants of lymphoma progression in this clinical context.
| Moses, A; Nelson, J; Bagby Jr, G C (1998) The influence of human immunodeficiency virus-1 on hematopoiesis. Blood 91:1479-95 |
| Moses, A V; Williams, S E; Strussenberg, J G et al. (1997) HIV-1 induction of CD40 on endothelial cells promotes the outgrowth of AIDS-associated B-cell lymphomas. Nat Med 3:1242-9 |
| Moses, A V; Williams, S; Heneveld, M L et al. (1996) Human immunodeficiency virus infection of bone marrow endothelium reduces induction of stromal hematopoietic growth factors. Blood 87:919-25 |
