title: Neutrophil-derived MMP-9 mediates synergistic mobilization of hematopoietic stem and progenitor cells by the combination of G-CSF and the chemokines GRObeta/CXCL2 and GRObetaT/CXCL2delta4.
abstract: Mobilized peripheral blood stem cells (PBSCs) are widely used for transplantation, but mechanisms mediating their release from marrow are poorly understood. We previously demonstrated that the chemokines GRObeta/CXCL2 and GRObetaT/CXCL2Delta4 rapidly mobilize PBSC equivalent to granulocyte colony-stimulating factor (G-CSF) and are synergistic with G-CSF. We now show that mobilization by GRObeta/GRObetaT and G-CSF, alone or in combination, requires polymorphonuclear neutrophil (PMN)-derived proteases. Mobilization induced by GRObeta/GRObetaT is associated with elevated levels of plasma and marrow matrix metalloproteinase 9 (MMP-9) and mobilization and MMP-9 are absent in neutrophil-depleted mice. G-CSF mobilization correlates with elevated neutrophil elastase (NE), cathepsin G (CG), and MMP-9 levels within marrow and is partially blocked by either anti-MMP-9 or the NE inhibitor MeOSuc-Ala-Ala-Pro-Val-CMK. Mobilization and protease accumulation are absent in neutrophil-depleted mice. Synergistic PBSC mobilization observed when G-CSF and GRObeta/GRObetaT are combined correlates with a synergistic rise in the level of plasma MMP-9, reduction in marrow NE, CG, and MMP-9 levels, and a coincident increase in peripheral blood PMNs but decrease in marrow PMNs compared to G-CSF. Synergistic mobilization is completely blocked by anti-MMP-9 but not MeOSuc-Ala-Ala-Pro-Val-CMK and absent in MMP-9-deficient or PMN-depleted mice. Our results indicate that PMNs are a common target for G-CSF and GRObeta/GRObetaT-mediated PBSC mobilization and, importantly, that synergistic mobilization by G-CSF plus GRObeta/GRObetaT is mediated by PMN-derived plasma MMP-9.
authors.affiliation: Department of Microbiology and Immunology and the Walther Oncology Center, Indianapolis, IN 46202, USA. lpelus@iupui.edu
authors.forename: Louis M
authors.initials: LM
authors.lastname: Pelus
authors.forename: Huimin
authors.initials: H
authors.lastname: Bian
authors.forename: Andrew G
authors.initials: AG
authors.lastname: King
authors.forename: Seiji
authors.initials: S
authors.lastname: Fukuda
mesh_terms: D000818:Animals; D019743:Chemokines, CXC / Q000008:administration & dosage; D003114:Colony-Forming Units Assay; D004357:Drug Synergism; D005260:Female; D016179:Granulocyte Colony-Stimulating Factor / Q000008:administration & dosage; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009504:Neutrophils / Q000201:enzymology; D011994:Recombinant Proteins
chemical_list: D019743:Chemokines, CXC; D011994:Recombinant Proteins; D016179:Granulocyte Colony-Stimulating Factor; D020780:Matrix Metalloproteinase 9