ABSTRACT
BACKGROUND: It is well known that harmonious interactions among adhesion molecules and stromal cell-derived factor-1 (SDF-1)-mediated chemoattraction signalling via CXCR4 are needed for bone marrow homing of hematopoietic stem cells and progenitor cells. The aim of this study was to define the role of interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), and transforming growth factor-beta 1 (TFG-beta1), known as hematopoiesis-inhibitory cytokines, in the regulation of the molecules in relation to the homing. METHODS: We investigated the effects of these cytokines on the expression of CXCR4 and adhesion molecules and the production of SDF-1 in bone marrow cells including CD34+ cells, bone marrow endothelial cells (BMEC-1 cells), and bone marrow stromal cells (BMSCs). We also examined whether the cytokines influence in vitro transmigration of hematopoietic progenitors. RESULTS: None of the cytokines influenced CXCR4 expression on CD34+ cells or SDF-1- mediated chemotaxis of the cells. IFN-gamma and TNF-alpha, but not TGF-beta up-regulated the expression of L-selectin, ICAM-1, and VLA-4 on CD34+ cells. However, the up-regulation was not translated into the enhanced transendothelial migration. IFN-gamma and TNF-alpha up-regulated the expression of VCAM-1 and ICAM-1 on BMEC-1 cells, and rendered the endothelium more suitable for transendothelial migration of hematopoietic progenitors. IFN-gamma and TNF-alpha also up-regulated the expression of VCAM-1 and ICAM-1 on primary human BMSCs. All three cytokines significantly attenuated SDF-1 production from primary BMSCs, and TNF-alpha diminished SDF-1 production from BMEC-1 cells. CONCLUSION: These data indicate that IFN-gamma, TNF-alpha, and TGF-beta1 play a role in the regulation of bone marrow homing of hematopoietic cells via up-regulation of adhesion molecule expression and down-modulation of SDF-1 production in bone marrow cells.