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R S Evely

Publications and source records attributed to R S Evely.

6 recordsLinked to original sources
PubMed1992

Leukaemia inhibitory factor and bone cell function.

A bone-resorbing product of mouse spleen cells found to have differentiation-inducing activity was most probably leukaemia inhibitory factor (LIF). This revealed that LIF is a cytokine active on bone, in addition to its several other sites of action. In organ culture of newborn mouse bone, recombinant LIF promoted bone resorption by a prostaglandin-dependent process. Resorption by isolated rat osteoclasts was also promoted by LIF through an initial action on osteoblasts which was receptor-mediated. Incorporation of [3H]thymidine into DNA was increased by LIF in cells (most probably osteoblasts) of the newborn mouse bones. Osteoblasts have been shown to produce LIF, and the amount is increased by treatment with retinoic acid or TNF-alpha. LIF also acts directly on osteoblasts to inhibit plasminogen activator activity, by stimulating the synthesis of plasminogen activator inhibitor 1 mRNA and protein. The latter actions are very similar to those of TGF-beta. Again like TGF-beta, LIF was ineffective in promoting bone resorption in vitro in fetal rat long bones. These results, together with the in vivo data showing that high circulating levels of LIF in the mouse are accompanied by a substantial increase in trabecular bone mass, indicate that LIF is another cytokine with potent actions on bone and potentially important interactions with other osteotrophic factors.

Animals↗
PubMed1992

An assessment of the ability of human bone marrow cultures to generate osteoclasts.

Several groups have successfully generated osteoclasts in cultures of murine haemopoietic cells. This approach would clearly be useful in the analysis of mechanisms of regulation of human osteoclast formation if analogous results could be obtained in cultures of human bone marrow. This communication describes independent attempts by three groups to generate unequivocally defined osteoclasts from bone marrow obtained from human iliac crest, femoral neck, rib, and from foetuses. The haemopoietic tissue was incubated using techniques described by others for production of osteoclast-like cells, and with variants of this technique using strategies based on our experiences with murine osteoclastogenesis. Haemopoietic cells were incubated with calcium regulating hormones, cytokines, osteoblastic supernatants, and osteoblastic or bone marrow stromal cell layers. Formation of cells capable of excavation of bone slices was rarely seen. Despite the paucity of bone resorbing cells, multinucleate cells (MNCs) developed with similar characteristics to the MNCs that have been interpreted as osteoclast-like in human bone marrow cultures. The MNCs were, however, calcitonin-receptor (CTR) negative, and did not show the typical pattern of reactivity with osteoclast-specific antibodies. They possessed instead an antigenic profile characteristic of macrophage polykaryons. We conclude that the MNCs which consistently generate in human bone marrow cultures do not possess phenotypic characteristics specific for osteoclasts and appear to be macrophage polykaryons. The conditions required for osteoclast generation in cultures of human haemopoietic cells remain to be defined.

Bone Marrow Cells↗
PubMed1991

Structural requirements for the action of parathyroid hormone-related protein (PTHrP) on bone resorption by isolated osteoclasts.

Parathyroid hormone-related protein (PTHrP) plays a major role in the syndrome of humoral hypercalcemia of malignancy (HHM) by its actions on bone and kidney. In this study an isolated osteoclast bone resorption assay was used to investigate the actions of this peptide and the structure-activity relationships for its resorption effect. As with PTH, neither synthetic nor recombinant PTHrP preparations stimulated resorption within highly purified osteoclast populations. Resorption was stimulated only in the presence of contaminating osteoblasts or in cocultures with the osteoblast-like cell line UMR-106. In the presence of osteoblasts PTHrP-(1-34) and PTHrP-(1-84) stimulated bone resorption in a dose-dependent manner with a potency comparable to that of PTH-(1-34) on a molar basis. The biologic activity of the PTHrP was shown to reside in the first 34 amino acids, and within that region the structural requirements for promotion of osteoclastic resorption resembled closely those for promotion of cyclic AMP formation in osteoblast-like cells. Using emulsion autoradiography with iodinated PTHrP-(1-34) and PTHrP-(1-84) on mixed bone cell preparations from neonatal rats, specific binding was demonstrated only to osteoblasts, not to osteoclasts. These results clearly demonstrate that PTHrP is a potent stimulator of bone resorption and that these effects are, like those of PTH, mediated by initial actions upon cells of the osteoblast lineage.

Animals↗
PubMed1990

Osteoblasts display receptors for and responses to leukemia-inhibitory factor.

Specific binding of leukemia-inhibitory factor (LIF) to osteoblasts, but not multinucleated osteoclasts, was demonstrated by receptor autoradiography by using cells isolated from newborn rat long bones. The clonal rat osteogenic sarcoma cells, UMR 106-06, which have several phenotypic properties of osteoblasts, expressed 300 LIF receptors per cell, with an apparent KD of 60 pM. Treatment of calvarial osteoblasts or UMR 106-01 cells with LIF resulted in a dose-dependent inhibition of plasminogen activator (PA) activity. Both calvarial osteoblasts and osteogenic sarcoma cells were shown by Western blotting and reverse fibrin autography to produce plasminogen activator inhibitor-1 (PAI-1), the production of which was increased by LIF treatment. Northern blot analysis revealed that LIF treatment resulted in a rapid (peak 1 hour), dose-dependent increase in mRNA for PAI-1. LIF treatment of the preosteoblast cell line, UMR 201, enhanced the alkaline phosphatase response of these cells to retinoic acid. Each of the osteoblast-like cell types (calvarial osteoblasts, UMR 106-06, and UMR 201) was shown to produce LIF by bioassay and, by using the polymerase chain reaction (PCR), was shown to express low levels of mRNA for LIF. These data establish that cells of the osteoblast lineage are targets for LIF action. The reported anabolic effects of this cytokine on bone formation in vivo could be related to inhibition of protease activity. LIF may be an important paracrine modulator in bone, or perhaps an autocrine one, based on the evidence for its production by osteoblasts and osteoblast-like cells.

Alkaline Phosphatase↗