title: Elevated serum soluble CD200 and CD200R as surrogate markers of bone loss under bed rest conditions.
abstract: CD200 is a transmembrane protein that belongs to the immunoglobulin family of proteins and is ubiquitously expressed on a variety of cell types. Upon interaction with its receptors (CD200Rs) expressed on myeloid-derived cells and T lymphocytes, an immunoregulatory signal is delivered to receptor-expressing cells. Previous studies have implicated a role for CD200:CD200R in the regulation of the expression of mRNA markers of osteoclastogenesis/osteoblastogenesis, following interaction of CD200 (on osteoblast precursors) with CD200R1 (on osteoclast precursors). Signaling of CD200R1 is hypothesized to attenuate osteoclastogenesis. We have investigated whether levels of soluble forms of CD200 and/or CD200R1 (sCD200, sCD200R1) are altered in volunteers undergoing 6° head down tilt bed rest to mimic conditions of microgravity known to be associated with preferential osteoclastogenesis and whether countermeasures, reported to be beneficial in attenuation of bone loss under microgravity conditions, would lead to altered sCD200 and sCD200R1 levels. Our data suggest that, as predicted, sCD200 levels fall under bed rest conditions while sCD200R1 levels rise. In subjects undergoing 30-minute per day continuous centrifugation protocols, as a countermeasure to attenuate changes which may lead to bone loss, these alterations in sCD200 and sCD200R1 levels seen under conditions of bed rest were abolished or attenuated. Our results suggest that measurement of sCD200 and/or sCD200R1 may prove a useful and rapid means of monitoring subjects at risk of bone loss and/or accessing the efficacy of treatment regimes designed to counter bone loss.
authors: Transplant Research Division, Toronto Hospital and University Health Network, 101 College St., Toronto, ON M5G1L7, Canada. Electronic address: okos@uhnres.utoronto.ca.
authors: O
authors: O
authors: Kos
authors: Schlegel-University of Waterloo, Research Institute for Aging, Faculty of Applied Health Sciences, University of Waterloo, Waterloo, ON N2L3G1, Canada. Electronic address: hughson@uwaterloo.ca.
authors: R L
authors: RL
authors: Hughson
authors: McCaig Institute for Bone & Joint Health, 3330 Hospital Drive NW, Calgary, AB T2N4N1, Canada. Electronic address: hartd@ucalgary.ca.
authors: D A
authors: DA
authors: Hart
authors: International Space University, 1 rue Jean-Dominique Cassini, Illkirch-Graffenstaden F-67400, France. Electronic address: clement@isunet.edu.
authors: G
authors: G
authors: Clément
authors: Institute for Aerospace Medicine, German Aerospace Center (DLR), Linder Höhe, Cologne D-51147, Germany. Electronic address: Petra.Frings-Meuthen@dlr.de.
authors: P
authors: P
authors: Frings-Meuthen
authors: Royal Institute of Technology, Stockholm SE-100 44, Sweden. Electronic address: Dag.Linnarsson@ki.se.
authors: D
authors: D
authors: Linnarsson
authors: University of Houston, 3855 Holman St., Rm 104, Garrison Houston, TX 77204-6015, USA. Electronic address: wpaloski@mail.coe.uh.edu.
authors: W H
authors: WH
authors: Paloski
authors: Institute for Aerospace Medicine, German Aerospace Center (DLR), Linder Höhe, Cologne D-51147, Germany; Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Manchester M1 5GD, UK. Electronic address: Joern.Rittweger@dlr.de.
authors: J
authors: J
authors: Rittweger
authors: Antwerp University Research Centre for Equilibrium and Aerospace, Middelheimcampus G.U.336, Groenenborgerlaan 171, Antwerpen B-2020, Belgium. Electronic address: floris.wuyts@ua.ac.be.
authors: F
authors: F
authors: Wuyts
authors: Institute for Aerospace Medicine, German Aerospace Center (DLR), Linder Höhe, Cologne D-51147, Germany. Electronic address: Jochen.Zange@dlr.de.
authors: J
authors: J
authors: Zange
authors: Transplant Research Division, Toronto Hospital and University Health Network, 101 College St., Toronto, ON M5G1L7, Canada. Electronic address: gorczyns@uhnresearch.ca.
authors: R M
authors: RM
authors: Gorczynski
mesh_terms: D000328:Adult; D000469:Alkaline Phosphatase / Q000097:blood; D000596:Amino Acids / Q000097:blood / Q000652:urine; D015703:Antigens, CD / Q000097:blood*; D000954:Antigens, Surface / Q000097:blood*; D001510:Bed Rest; D015415:Biomarkers / Q000097:blood; D001862:Bone Resorption / Q000097:blood* / Q000652:urine; D001842:Bone and Bones / Q000378:metabolism / Q000473:pathology; D002118:Calcium / Q000097:blood; D024042:Collagen Type I / Q000652:urine; D006801:Humans; D008297:Male; D064446:Orexin Receptors; D010446:Peptide Fragments / Q000097:blood; D010455:Peptides / Q000652:urine; D011347:Procollagen / Q000097:blood; D053245:RANK Ligand / Q000097:blood; D011956:Receptors, Cell Surface / Q000097:blood*; D012995:Solubility; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
chemical_list: D000596:Amino Acids; D015703:Antigens, CD; D000954:Antigens, Surface; D015415:Biomarkers; C477337:CD200R1 protein, human; D024042:Collagen Type I; D064446:Orexin Receptors; D010446:Peptide Fragments; D010455:Peptides; D011347:Procollagen; D053245:RANK Ligand; D011956:Receptors, Cell Surface; D014409:Tumor Necrosis Factor-alpha; C052929:collagen type I trimeric cross-linked peptide; C047202:procollagen Type I N-terminal peptide; C036020:deoxypyridinoline; D000469:Alkaline Phosphatase; D002118:Calcium; C042739:antigens, CD200
keywords: Artificial gravity; Bed rest Study; CD200; CD200R