title: T-cell cytokine induction of BMP-2 regulates human mesenchymal stromal cell differentiation and mineralization.
abstract: How T-cells, attracted to local sites of inflammation in arthritides, affect heterotopic ossification is presently unknown. Here, we tested the hypothesis that T-cell cytokines play a role in the differentiation of human mesenchymal stromal cells (HMSC) into the osteoblast phenotype by inducing autologous BMP-2, providing a possible mechanism for heterotopic ossification. HMSC from multiple donor bones were treated with either activated T-cell conditioned medium (ACTTCM) or physiological concentrations of the major inflammatory cytokines, TNF-alpha, TGF-beta, IFN-gamma, and IL-17 (TTII), individually or in combinations. ACTTCM induced BMP-2 protein in a time-dependent manner over a 48 h period and alkaline phosphatase (AlkP) within 7 days. In combination, TTII, like ACTTCM, induced AlkP and synergistically induced BMP-2 protein. Either individually, or in combinations of up to three, the T-cell cytokines failed to induce BMP-2 above control levels while a combination of all four cytokines synergistically induced BMP-2 10-fold as assessed by ELISA. TTII induced mineralized matrix as effectively as dexamethasone. Inhibition of p38 MAPK completely inhibited TTII-induced BMP-2 production and matrix mineralization. Real time RT-PCR analysis demonstrated a striking early (within 4 h) increase in BMP-2 gene expression by TTII, which was suppressed by p38 MAP kinase inhibition. In localized chronic inflammatory diseases, T-cell cytokines released at localized sites of inflammation may be the driving force for differentiation of local mesenchymal stromal cells into the osteoblast phenotype thereby playing a significant role in the heterotopic ossification observed in these diseases.
authors.affiliation: Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri 63110, USA. Rifas_L@kids.wustl.edu
authors.forename: Leonard
authors.initials: L
authors.lastname: Rifas
mesh_terms: D001168:Arthritis / Q000201:enzymology / Q000473:pathology; D001854:Bone Marrow Cells / Q000201:enzymology / Q000473:pathology; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000096:biosynthesis*; D002114:Calcinosis / Q000201:enzymology* / Q000473:pathology; D002454:Cell Differentiation; D002465:Cell Movement; D002478:Cells, Cultured; D017077:Culture Media, Conditioned; D016207:Cytokines / Q000378:metabolism*; D006801:Humans; D007249:Inflammation / Q000201:enzymology / Q000473:pathology; D015398:Signal Transduction; D017154:Stromal Cells / Q000201:enzymology / Q000473:pathology; D013601:T-Lymphocytes / Q000378:metabolism* / Q000473:pathology; D014019:Tissue Donors; D016212:Transforming Growth Factor beta / Q000096:biosynthesis*
chemical_list: C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D017077:Culture Media, Conditioned; D016207:Cytokines; D016212:Transforming Growth Factor beta