title: Acute hematopoietic stress in mice is followed by enhanced osteoclast maturation in the bone marrow microenvironment.
abstract: Osteoclasts are components of hematopoietic stem cell (HSC) niches, but their role as contributors to the HSC homeostasis and release are still controversial. We aimed to investigate whether an acute blood loss of 10% of total blood content, along with the consequent intense hematopoiesis, would affect osteoclast differentiation and activity. Isolated peripheral blood, spleen, and bone marrow (BM) cells from bones of hind limbs were investigated for the presence of specific subpopulations of osteoclast precursors: B220(-)CD3(-)NK1.1(-)CD11b(-/low)CD115(+)CD117(+) cells in BM, and B220(-)CD3(-)NK1.1(-)Gr-1(-)CD11b(+)CD115(+) cells in peripheral blood and spleen as well as the receptor activator of nuclear factor κ-B(+) cycle-arrested quiescent osteoclast precursors. Expression of osteoclastogenesis-related genes CD115, receptor activator of nuclear factor κ-B, and cathepsin K, the potential of BM cells to form osteoclast-like cells in vitro, and osteoclast activity in vivo were also evaluated. We observed an increase in spleen cellularity and myelopoiesis during week 1 following blood loss, without any significant effects on BM cellularity or BM myeloid precursors, including cells with high osteoclastogenic potential. However, at 1 week postbleeding, hematopoiesis significantly promoted the expression of cathepsin K, interleukin-34, and bone morphogenetic protein-6. Quiescent osteoclast precursors increased significantly in spleen 2 days following bleeding, whereas osteoclast activity remained unchanged up to 2 weeks postbleeding. Osteoclast-dependent B-cell differentiation was affected at the pre-B stage of maturation in BM, whereas the Lin(-)Sca-1(+)c-kit(+) population expanded in BM and spleen after 2 days postbleeding. Our data demonstrate that an acute blood loss promotes differentiation and maturation of osteoclasts at 1 week but does not enhance osteoresorption at 2 weeks postbleeding. Our data also identify osteoclast differentiation as a consequent and important event in establishing HSC homeostasis following hematopoietic stress.
authors: Laboratory for Molecular Immunology, University of Zagreb School of Medicine, Zagreb, Croatia.
authors: Sania
authors: S
authors: Kuzmac
authors: Laboratory for Molecular Immunology, University of Zagreb School of Medicine, Zagreb, Croatia; Department of Physiology and Immunology, University of Zagreb School of Medicine, Zagreb, Croatia.
authors: Danka
authors: D
authors: Grcevic
authors: Laboratory for Molecular Immunology, University of Zagreb School of Medicine, Zagreb, Croatia; Department of Physiology and Immunology, University of Zagreb School of Medicine, Zagreb, Croatia.
authors: Alan
authors: A
authors: Sucur
authors: Laboratory for Molecular Immunology, University of Zagreb School of Medicine, Zagreb, Croatia; Department of Physiology and Immunology, University of Zagreb School of Medicine, Zagreb, Croatia.
authors: Sanja
authors: S
authors: Ivcevic
authors: Laboratory for Molecular Immunology, University of Zagreb School of Medicine, Zagreb, Croatia; Department of Anatomy, University of Zagreb School of Medicine, Zagreb, Croatia. Electronic address: vkatavic@mef.hr.
authors: Vedran
authors: V
authors: Katavic
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism; D000950:Antigens, Ly / Q000235:genetics / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D001853:Bone Marrow / Q000378:metabolism*; D055418:Bone Morphogenetic Protein 6 / Q000235:genetics / Q000378:metabolism; D056657:Cathepsin K / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation; D049109:Cell Proliferation; D005260:Female; D015870:Gene Expression; D006410:Hematopoiesis / Q000235:genetics*; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000378:metabolism; D007378:Interleukins / Q000235:genetics / Q000378:metabolism; D008214:Lymphocytes / Q000166:cytology / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D010010:Osteoclasts / Q000166:cytology* / Q000378:metabolism; D018962:Phlebotomy; D061251:Primary Cell Culture; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics / Q000378:metabolism; D053246:Receptor Activator of Nuclear Factor-kappa B / Q000235:genetics / Q000378:metabolism; D013154:Spleen / Q000166:cytology / Q000378:metabolism; D013312:Stress, Physiological
chemical_list: D015703:Antigens, CD; D000950:Antigens, Ly; D015415:Biomarkers; D055418:Bone Morphogenetic Protein 6; D007378:Interleukins; C074650:Ly6a protein, mouse; D008565:Membrane Proteins; D053246:Receptor Activator of Nuclear Factor-kappa B; C552364:interleukin-34, mouse; D019009:Proto-Oncogene Proteins c-kit; D056657:Cathepsin K; C534132:Ctsk protein, mouse