Disruption of the CXCR4/CXCL12 chemotactic interaction during hematopoietic stem cell mobilization induced by GCSF or cyclophosphamide
Jean-Pierre Lévesque, … , Paul J. Simmons, Linda J. Bendall
Jean-Pierre Lévesque, … , Paul J. Simmons, Linda J. Bendall
Published January 15, 2003
Citation Information: J Clin Invest. 2003;111(2):187-196. https://doi.org/10.1172/JCI15994.
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Article Hematology

Disruption of the CXCR4/CXCL12 chemotactic interaction during hematopoietic stem cell mobilization induced by GCSF or cyclophosphamide

Abstract

Hematopoietic progenitor cells (HPCs) normally reside in the bone marrow (BM) but can be mobilized into the peripheral blood (PB) after treatment with GCSF or chemotherapy. In previous studies, we showed that granulocyte precursors accumulate in the BM during mobilization induced by either GCSF or cyclophosphamide (CY), leading to the accumulation of active neutrophil proteases in this tissue. We now report that mobilization of HPCs by GCSF coincides in vivo with the cleavage of the N-terminus of the chemokine receptor CXCR4 on HPCs resident in the BM and mobilized into the PB. This cleavage of CXCR4 on mobilized HPCs results in the loss of chemotaxis in response to the CXCR4 ligand, the chemokine stromal cell–derived factor-1 (SDF-1/CXCL12). Furthermore, the concentration of SDF-1 decreased in vivo in the BM of mobilized mice, and this decrease coincided with the accumulation of serine proteases able to directly cleave and inactivate SDF-1. Since both SDF-1 and its receptor, CXCR4, are essential for the homing and retention of HPCs in the BM, the proteolytic degradation of SDF-1, together with that of CXCR4, could represent a critical step leading to the mobilization of HPCs into the PB in response to GCSF or CY.

Authors

Jean-Pierre Lévesque, Jean Hendy, Yasushi Takamatsu, Paul J. Simmons, Linda J. Bendall

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Figure 4

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BM extracellular fluids from mobilized mice contain proteases cleaving e...
BM extracellular fluids from mobilized mice contain proteases cleaving exogenous human synthetic CXCL12α. (a–c) Aliquots of exogenous synthetic human CXCL12α were incubated overnight at 37°C in the presence of an equal volume of BM extracellular fluids taken from mice mobilized with either GCSF alone (a), CY alone (b), or CY in combination with GCSF (c). The remaining chemotactic activity of exogenous CXCL12α was measured by performing transmigration assays with CD34+ cells freshly isolated from normal human BM. Nil indicates that PBS was added instead of BM extracellular extracts. In b and c, Sal represents the BM extracellular fluid from mice injected with saline for 6 days. Black bars show transmigration in the presence of digested CXCL12α, whereas white bars show controls in which exogenous CXCL12α was omitted. Data represent means ± SD of duplicates. Representative data from three independent experiments are shown. (d) The same samples of synthetic human CXCL12α incubated with BM extracellular fluids (as in a) were electrophoresed on a 20% polyacrylamide Tris-Trycine-SDS gel and analyzed by Western blotting with a goat anti-human CXCL12α antibody. A representative experiment from three performed is shown.