In silicon desinging of RANKL-targeting vaccine for protection of osteoporosis based on the epitope of Denosumab

•RANKL-Denosumab binding peptide (RANKL220–245) was firstly identified.•DR3 vaccine was constructed by three copies of RANKL220–245 and diphtheria toxin T domain.•DR3 vaccine could activate T and B lymphocytes to produce high levels of antibodies and cytokines like IFN- γ, IL-2 and etc.•DR3 vaccine was aroused to benefit the prevention and treatment of osteoporosis. Life quality of osteoporosis patients is affected significantly due to the severely complications of fracture and pain. RANKL, indicated as the key mediator of osteoporosis, plays a pathogenic role of osteoclasts induction. To target this program, two medications, bisphosphonate and Denosumab, were developed and achieved remarkable advantages in clinics. Unfortunately, fracture-related side-effects always emerge unavoidably, after either long-term administration of bisphosphonates or Denosumab withdrawing. To address these challenges, vaccine-based approach has been adopted to achieve sustainable protection through induction and maintenance of effective antibodies in mild level over decades. A Denosumab binding peptide was firstly identified as the basic component of vaccine. This peptide was then fused with diphtheria toxin T domain, a widely used adjuvant protein. Its capabilities to penetrate the autologous tolerance and induce the immune responses was then demonstrated with in-silicon evaluation. Finally, the efficacy of the DR3 vaccine was assessed through immunization on the human RANKL transgenic mice model of osteoporosis. The DTT-RANKL(220–245)3 vaccine, termed as DR3, were predicted as highly antigenic and non-allergenicity. This molecule was comprised of 46.5 % of helix, 8.5 % strand and 45.1 % coil, the optimized Z-value of the tertiary structure was 6.39, and the favored area in the Ramachandran plot was 96.1 % after refinement. Molecular docking showed a tight binding of DR3 vaccine to TLR2 (−9.2 kcal/mol) and TLR4 (−9.5 kcal/mol). In addition, the immune stimulation indicated robust responses post administration of DR3 vaccine, including high level production of of antibodies and cytokines, activated T and B lymphocytes, and the long-last immune memory. In agree with the simulation, vaccinated mice generated high titers anti-hRANKL antibodies and elevated levels of IL-4 and IL-10 at 7th week post immunization. DR3 vaccine was aroused to benefit the prevention and treatment of osteoporosis, and other bone-resorptive diseases potentially.