PEGylation of an osteoclast inhibitory peptide: suitable candidate for the treatment of osteoporosis.

Osteoporosis is a condition of bone loss due to excessive osteoclastic activity. Several protein factors, such as receptor activator of nuclear factor kappa-B (RANK), receptor activator of nuclear factor kappa-B ligand (RANKL), osteoprotegerin (OPG), have been identified that are important in the pathogenesis of osteoporosis. RANKL binds to RANK and activates the NF-κB pathway by interaction of its cytoplasmic domain with an intracellular adapter protein, TNF receptor associated factors 6 (TRAF 6). This interaction can be inhibited by cell-permeable peptides that prevent RANK-TRAF 6 interaction. However, similar to the peptides/proteins used in clinical setting, the effective application of this TRAF 6 Inhibitory peptide as a therapeutic agent is marred by several limitations for instance short half-life, rapid renal clearance and immunogenicity. In the present study, we have developed PEGylated TRAF 6 Inhibitory peptide by conjugating TRAF 6 Inhibitory peptide to linear PEG backbone that exhibits longer bioavailability in plasma in the animal model. Besides, it has an enhanced uptake at its site of action, i.e., bone marrow.