Osteoclast-activating system in cosmonauts after long-term international space station missions

Abstract

The results of studying the system of the osteoprotegerin/receptor activator of nuclear factor kappa-B ligand (OPG/RANKL) in 22 Russian cosmonauts after long-term (124–199 days) International Space Station missions are presented. It was found that early readaptation period is associated with changes in the serum concentrations of OPG and RANKL and the production rate of OPG and RANKL in phytohemagglutinin (PHA)-stimulated and non-stimulated mononuclear cells of peripheral blood in vitro. The extent of these changes varied in different subjects. Our data suggest that the OPG/RANKL cytokine system takes part in the processes of bone remodeling in cosmonauts after long-term missions.