The Effects of Amine-Carboxyborane Related Derivatives on UMR-106 Bone Metabolism

The amine-carboxyboranes and related derivatives have been shown to be potent anti-inflammatory and anti-osteoporosis agents. Their action in part appears to be mediated by the modulation of cytokines, e.g. TNFalpha or IL-1. Previous studies have demonstrated that LPS induced macrophages release of TNFalpha maximally at 60 to 90 min. and IL-1 from 5 to 8 hr. The amine-carboxyboranes reduced significantly the release of these cytokines but also blocked TNFalpha high affinity binding to UMR-106 receptor at 90 min. at 10 muM, and IL-1 high affinity binding at 5 hr. at 12.5 muM. In addition, the agents suppressed IL-8 binding to CHO K1 high affinity receptor at 24 hr. at 50 muM and IL-2 binding to HuT-8 receptors at 25 muM at 90 min. and 5 hr. Correlation of metabolic events associated with osteoporosis showed that at 90 min., when TNFalpha receptor binding was reduced by the agents, calcium uptake into UMR-106 cells was reduced at 10 muM as well as the acid and alkaline phosphatases, and the prostaglandin cyclo-oxygenase activities and adhesion of leukocytes and macrophages to UMR-106 cell monolayers. At 5hr. when the agents reduced IL-1 binding to UMR-106 receptors, calcitonin and 1,25-dihydrovitamin D(3) binding was reduced by the agents as was acid and alkaline phosphatase, and 5'-lipoxygenase activities and white blood cell adhesion. At this time calcium uptake and proline incorporation was increased significantly by the agents. At later times e.g. 18-48 hr. calcium uptake was still increased, and NAG activity was inhibited in the presence of the agents. These effects may be related more to the inhibition of other cytokine receptor binding, e.g. IL-8. Thus, many of the observed metabolic effects of amine-carboxyboranes as antiosteoporosis agents can be correlated with their inhibition of cytokine high affinity binding to target cell receptors.