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    Arthritis Res Ther. 2008;10(2):R37. Epub 2008 Mar 27.

    TNF inhibits production of stromal cell-derived factor 1 by bone stromal cells and increases osteoclast precursor mobilization from bone marrow to peripheral blood.

    Zhang Q, Guo R, Schwarz EM, Boyce BF, Xing L.

    Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, 601 Elmwood Avenue, Box 626, Rochester, NY 14642, USA. qianzhang@urmc.rochester.edu

    INTRODUCTION: The objective of the present study was to investigate the role of the stromal cell-derived factor 1 (SDF-1)/CXCR4 axis in TNF-induced mobilization of osteoclast precursors (OCPs) from bone marrow. METHODS: OCPs were generated from bone marrow cells of TNF-transgenic mice or wild-type mice treated with TNF or PBS. The percentage of CD11b+/Gr-1-/lo OCPs was assessed by fluorescence-activated cell sorting. OCP migration to the SDF-1 gradient and the osteoclast forming potency were assessed in chemotaxis/osteoclastogenic assays. SDF-1 expression was assessed by real-time RT-PCR, ELISA and immunostaining in primary bone marrow stromal cells, in the ST2 bone marrow stromal cell line, and in bones from TNF-injected mice. RESULTS: OCPs generated in vitro from wild-type mice migrated to SDF-1 gradients and subsequently gave rise to osteoclasts in response to RANKL and macrophage colony-stimulating factor. TNF reduced SDF-1 expression by ST2 cells. Bone marrow stromal cells from TNF-transgenic mice produced low levels of SDF-1. TNF treatment of wild-type mice decreased the SDF-1 concentration in bone marrow extracts and decreased the SDF-1 immunostaining of bone marrow stromal cells, and it also increased the circulating OCP numbers. The percentage of bone marrow CXCR4+ OCPs was similar in TNF-transgenic mice and wild-type littermates and in TNF-treated and PBS-treated wild-type mice. CONCLUSION: Systemically elevated TNF levels inhibit bone marrow stromal cell production of SDF-1 and increase the release of bone marrow OCPs to the peripheral blood. Disruption of the SDF-1/CXCR4 axis by TNF may play an important role in mediating OCP mobilization from the bone marrow cavity in chronic inflammatory arthritis.

    PMID: 18371213 [PubMed - indexed for MEDLINE]

    PMCID: 2453755

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