Differential effects of anti-RANKL monoclonal antibody and zoledronic acid on necrotic bone in a murine model of Staphylococcus aureus-induced osteomyelitis.

Abstract

Osteomyelitis is characterized by progressive inflammatory bone destruction accompanied by severe pain and disability. However, with the exception of antibiotic therapies, there is no established therapy to protect the bone from infectious osteolysis. The anti-receptor activator of nuclear factor-kB ligand (RANKL) monoclonal antibody (anti-RANKL Ab) is a potential drug based on its proven effectiveness in preventing joint bone erosion in rheumatoid arthritis; however, the efficacy and adverse effects of anti-RANKL Ab in osteomyelitis remain to be investigated. In this study, we investigated the effects of anti-mouse RANKL Ab on acute osteomyelitis and compared them with those of zoledronic acid (ZA) using a murine model. Mice were inoculated with bioluminescent Staphylococcus aureus (Xen 29) on their left femur and then treated with ZA, anti-RANKL Ab, or phosphate-buffered saline as control. A 21-day longitudinal observational study using microcomputed tomography showed that both anti-RANKL Ab and ZA had an osteoprotective effect against infectious osteolysis. However, it was also demonstrated through bioluminescence imaging that ZA delayed the spontaneous reduction of bacterial load and through histology that it increased the amount of necrotic bone, while anti-RANKL Ab did not. Findings from histopathological and in vitro studies suggest that an intense inflammatory response around the necrotic bone could induce osteoclasts in a RANKL-independent manner, leading to the removal of necrotic bone, even after administration of the anti-RANKL Ab therapy. Collectively, anti-RANKL Ab may exert an osteoprotective effect without hampering the removal of the necrotic bone, which serves as a nidus for infection in osteomyelitis.

• Authors: Hideyuki Kobayashi, Ryo Fujita, Shigeto Hiratsuka, Tomohiro Shimizu, Dai Sato, Hiroki Hamano, Norimasa Iwasaki, Masahiko Takahata
• Journal: Journal of orthopaedic research : official publication of the Orthopaedic Research Society (J Orthop Res) Vol. 40 Issue 3 Pg. 614-623 (03 2022) ISSN: 1554-527X [Electronic] United States
• PMID: 33990977 (Publication Type: Journal Article, Observational Study, Research Support, Non-U.S. Gov't)
• Copyright: © 2021 Orthopaedic Research Society. Published by Wiley Periodicals LLC.

Chemical References

• Antibodies, Monoclonal
• Bone Density Conservation Agents
• Ligands
• RANK Ligand
• Zoledronic Acid

Topics

• Animals
• Antibodies, Monoclonal (pharmacology)
• Bone Density Conservation Agents (pharmacology, therapeutic use)
• Disease Models, Animal
• Ligands
• Mice
• Osteoclasts
• Osteolysis (drug therapy, pathology)
• Osteomyelitis (microbiology)
• Osteonecrosis
• RANK Ligand (pharmacology)
• Staphylococcal Infections (complications, drug therapy, pathology)
• Staphylococcus aureus
• X-Ray Microtomography
• Zoledronic Acid (pharmacology, therapeutic use)