Functionalized Virus Nanoparticles Alleviates Osteoporosis via Targeting the Function of RANK-Specific Motifs

Osteoporosis is a common skeletal disease characterized by excessive osteoclast-induced bone loss. RANKL/RANK signaling pathway is essential for osteoclastogenesis and is a key target for osteoporosis. However, regarding the fact that RANKL/RANK also functions beyond bone, the total block of RANKL/RANK will have unwanted impact on other organs. Our previous study revealed that mutation of RANK-specific motifs inhibited osteoclastogenesis without effects on other organs in mice. However, the instability and low cellular uptake efficiency limited the application of the therapeutic peptide originating from the amino acid sequence of RANK-specific motifs (RM). To this end, in this study, the peptide RM (SRPVQEQGGA (C to N terminal)) was chemically modified onto the surface of the plant virus-based nanoparticles cowpea chlorotic mottle virus (CCMV). Subsequent experiments showed that the novel virus nanoparticles RM-CCMV had excellent biocompatibility and stability, which ultimately facilitated its cellular uptake efficiency and improved its inhibitive effects on osteoclastogenesis. Moreover, RM-CCMV achieved bone enrichment and suppressed bone resorption by inhibiting osteoclastogenesis and improving the parameters of bone histomorphology in murine femurs. To be mentioned, the effective dose of CCMV conjugated RM was only 6.25% of free RM. In summary, these results have provided a promising therapeutic strategy for osteoporosis.