Structure-based development of an osteoprotegerin-like glycopeptide that blocks RANKL/RANK interactions and reduces ovariectomy-induced bone loss in mice

Osteoporosis is a metabolic bone disease characterized by low bone mass and micro-architectural deterioration of bone, for which the underlying mechanism is an imbalance between bone resorption and bone remodeling. The protein-protein interactions between receptor activator of nuclear factor-κB ligand (RANKL), RANK (its receptor), and osteoprotegerin (OPG), are known to mediate the development and activation of osteoclasts in bone remodeling, and are regarded as a pivotal therapeutic target for the treatment of osteoporosis. Herein, we disclose the successful development of a novel glycopeptide (OM-2), the structure of which is based on the key interacting sites of the reported RANKL and OPG crystal structure. OM-2 exhibited potent binding affinity with RANKL and resistance to degradation by protease enzymes. It also blocked RANKL/RANK interactions, and inhibited osteoclastogenesis in vitro. In vivo studies confirmed that OM-2 could effectively reduce bone loss and inhibit osteoclast activation in ovariectomized (OVX) mice at a dosage of 20.0 mg/kg/day. Accordingly, OM-2 is suggested as a therapeutic candidate for postmenopausal osteoporosis (PMOP) and osteoclastogenesis-related diseases like rheumatoid arthritis (RA). More importantly, its identification validates our structure-based strategy for the development of drugs that target the RANKL/RANK/OPG system.