Inhibition of antigen presentation and T cell costimulation blocks PTH-induced bone loss

Brahmchetna Bedi, Jau Yi Li, Francesco Grassi, Hesham Tawfeek, M. Neale Weitzmann, Roberto Pacifici

Research output: Chapter in Book/Report/Conference proceedingConference contribution


T cells are required for continuous parathyroid hormone (cPTH) treatment to induce bone loss as they sensitize stromal cells to PTH through CD40 ligand (CD40L), a surface molecule of activated T cells. Since CD40L expression is a feature of activated T cells, we investigated whether antigen (Ag)-mediated T cell activation is required for PTH to exert its catabolic activity. We report that inhibition of Ag presentation through silencing of either class I or class II MHC-T cell receptor (TCR) interaction prevents the cortical bone loss induced by in vivo cPTH treatment. We also show that the bone loss and the stimulation of bone resorption induced by cPTH treatment are prevented by CTLA4-Ig, an inhibitor of T cell costimulation approved for the treatment of rheumatoid arthritis. Since inhibition of antigen-driven T cell activation by blockade of either TCR signaling or T cell costimulation is sufficient to silence the catabolic activity of cPTH, antigen-presenting cells and T lymphocyte interactions therefore play a critical role in the mechanism of action of PTH.

Original languageEnglish
Title of host publicationAnnals of the New York Academy of Sciences
Number of pages7
Publication statusPublished - Mar 2010

Publication series

NameAnnals of the New York Academy of Sciences
ISSN (Print)00778923
ISSN (Electronic)17496632


  • Bone loss
  • Bone resorption
  • Lymphocyte
  • Parathyroid hormone
  • T cell

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)


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