Increased osteoclast formation and activity by peripheral blood mononuclear cells in chronic liver disease patients with osteopenia

Osteoporosis is a common complication of chronic liver disease, and the underlying mechanisms are not understood. We aimed to determine if osteoclasts develop from osteoclast precursors in peripheral blood mononuclear cells (PBMCs) of chronic liver disease patients with osteopenia compared with controls. PBMCs were isolated and fluorescence-activated cell sorting was performed to quantify the activated T lymphocyte population and receptor activator of nuclear factor kappa beta ligand (RANKL) expression. The activated T lymphocyte populations were comparable for all 3 groups, and RANKL was not detectable. The percentage of CD14+CD11b+ cells containing osteoclast precursors was comparable between the 3 groups. To assess the formation and functional activity of osteoclasts formed from circulating mononuclear cells, PBMCs were cultured (1) without addition of cytokines, (2) with macrophage colony stimulating factor (M-CSF), (3) with M-CSF and osteoprotegerin, and (4) with M-CSF and RANKL. The number of tartrate-resistant acid phosphatase-positive multinucleated cells and bone resorption was assessed. PBMCs from chronic liver disease patients with ostcopenia formed more osteoclast-like cells, which, when cultured in the presence of M-CSF and RANKL resorbed more bone than controls. The number of osteoclast-like cells and the amount of bone resorption correlated with lumbar bone densities. Addition of M-CSF increased numbers of osteoclast-like cells formed in healthy controls; however, this was not observed in either of the chronic liver disease groups. Plasma levels of M-CSF were elevated in both patient groups compared with healthy controls. Conclusion: Circulating mononuclear cells from chronic liver disease patients with osteopenia have a higher capacity to become osteoclasts than healthy controls or chronic liver disease patients without osteopenia. This could partially be due to priming with higher levels of M-CSF in the circulation

Evidence for carrier-mediated uptake of triiodothyronine in cultured anterior pituitary cells of euthyroid rats

T3 uptake and TSH secretion were investigated in anterior pituitary cells isolated from adult fed Wistar rats and cultured for 3 days in medium containing 10% fetal calf serum. TSH release during culture increased linearly with the number of cells in the range of 80, 000800, 000 cells/well. Uptake and incubation experiments were performed at 37 C in medium containing 0.5% BSA. Incubation with TRH (0.1 μm) for 2 h stimulated TSH release 2.6-fold, and this effect was partly (-45%) suppressed by preexposure for 2 h to T3 (0.01-1 μm) or T4(1 μM). Similar concentrations of T3 and T4reduced the cellular uptake of [125I]T3 (50 pM) during 1 h of incubation by 55%. After 15 min of incubation, [125I]T3uptake (percent dose) amounted to 1.26 ± 0.05% (mean ± SE; n = 9)/500, 000 cells. The major part (75%) of the [125I]T3 was found in the extranuclear fraction. Simultaneous incubation with unlabeled T3 (1 or 10 μm) reduced [125I]T3 uptake by 43% (n = 3; P &lt; 0.001) and 52% (n = 6; P &lt; 0.001), respectively. Reduction of the temperature to 20 C diminished the T3-suppressible fraction of [l26I]T3uptake approximately 3-fold. After preincubation (30 min) and incubation (15 min) with monodansylcadaverine (100 μM), the uptake of [125I]T3was reduced by 32% (n = 3; P &lt; 0.01). When the Na+ gradient was reduced by preincubation and incubation with ouabain (0.5 mM) or monensin (10 or 100 μm), T3 uptake was inhibited by 25% (n = 5; P &lt; 0.01), 37% (n = 6; P &lt; 0.001), and 61% (n = 3; P &lt; 0.001), respectively. It is concluded that 1) T3 is taken up by the pituitary by a carrier-mediated mechanism, and 2) this uptake is at least partly dependent on the Na+ gradient.</p

Evidence for carrier-mediated uptake of triiodothyronine in cultured anterior pituitary cells of euthyroid rats

T3 uptake and TSH secretion were investigated in anterior pituitary cells isolated from adult fed Wistar rats and cultured for 3 days in medium containing 10% fetal calf serum. TSH release during culture increased linearly with the number of cells in the range of 80, 000800, 000 cells/well. Uptake and incubation experiments were performed at 37 C in medium containing 0.5% BSA. Incubation with TRH (0.1 μm) for 2 h stimulated TSH release 2.6-fold, and this effect was partly (-45%) suppressed by preexposure for 2 h to T3 (0.01-1 μm) or T4(1 μM). Similar concentrations of T3 and T4reduced the cellular uptake of [125I]T3 (50 pM) during 1 h of incubation by 55%. After 15 min of incubation, [125I]T3uptake (percent dose) amounted to 1.26 ± 0.05% (mean ± SE; n = 9)/500, 000 cells. The major part (75%) of the [125I]T3 was found in the extranuclear fraction. Simultaneous incubation with unlabeled T3 (1 or 10 μm) reduced [125I]T3 uptake by 43% (n = 3; P &lt; 0.001) and 52% (n = 6; P &lt; 0.001), respectively. Reduction of the temperature to 20 C diminished the T3-suppressible fraction of [l26I]T3uptake approximately 3-fold. After preincubation (30 min) and incubation (15 min) with monodansylcadaverine (100 μM), the uptake of [125I]T3was reduced by 32% (n = 3; P &lt; 0.01). When the Na+ gradient was reduced by preincubation and incubation with ouabain (0.5 mM) or monensin (10 or 100 μm), T3 uptake was inhibited by 25% (n = 5; P &lt; 0.01), 37% (n = 6; P &lt; 0.001), and 61% (n = 3; P &lt; 0.001), respectively. It is concluded that 1) T3 is taken up by the pituitary by a carrier-mediated mechanism, and 2) this uptake is at least partly dependent on the Na+ gradient.</p