RANKL Inhibitors Induce Osteonecrosis of the Jaw in Mice With Periapical Disease

Abstract

Antiresorptive medications are essential in treating diseases of pathologic osteoclastic bone resorption, including bone cancer and osteoporosis. Bisphosphonates (BPs) are the most commonly used antiresorptives in clinical practice. Although inhibition of bone resorption is important in regulating unwanted malignant and metabolic osteolysis, BP treatment is associated with potential side effects, including osteonecrosis of the jaws (ONJ). Recently, non-BP antiresorptive medications targeting osteoclastic function and differentiation, such as denosumab, have entered the clinical arena. Denosumab treatment results in a similar rate of ONJ as BPs. Animal models of ONJ, using high-dose BP treatment in combination with tooth extraction or dental disease, provide valuable tools and insight in exploring ONJ pathophysiology. However, the ability of other antiresorptives to induce ONJ-like lesions in animal models has not been explored. Such studies would be beneficial in providing support for the role of osteoclast inhibition in ONJ pathogenesis versus a direct BP effect on oral tissues. Here, we tested the ability of the receptor activator of NF-kB ligand (RANKL) inhibitors RANK-Fc (composed of the extracellular domain of RANK fused to the fragment crystallizable [Fc] portion of immunoglobulin G [IgG]) and OPG-Fc (composed of the RANKL-binding domains of osteoprotegerin [OPG] linked to the Fc portion of IgG) to induce ONJ in mice in the presence of periapical disease, but in the absence of dental extractions. We demonstrate radiographic evidence of ONJ in RANK-Fc–treated and OPG-Fc–treated mice, including inhibition of bone loss, increased bone density, lamina dura thickening, and periosteal bone deposition. These findings closely resembled the radiographic appearance of an ONJ patient on denosumab treatment. Histologic examination revealed that RANK-Fc treatment and OPG-Fc treatment resulted in absence of osteoclasts, periosteal bone formation, empty osteocytic lacunae, osteonecrosis, and bone exposure. In conclusion, we have successfully induced ONJ in mice with periapical disease, using potent osteoclast inhibitors other than BPs. Our findings, coupled with ONJ animal models using high-dose BPs, suggest that osteoclast inhibition is pivotal to the pathogenesis of ONJ.

Impaired Bone Resorption and Woven Bone Formation Are Associated with Development of Osteonecrosis of the Jaw-Like Lesions by Bisphosphonate and Anti–Receptor Activator of NF-κB Ligand Antibody in Mice

“…Interestingly, ONJ was developed in the absence of mature osteoclasts in the DRONJ model (Figures 2 and 4A), which is consistent with a recent finding, 24 suggesting that the aberrant behaviors of BP-affected osteoclasts (eg, osteoclasts undergoing apoptosis) may not be associated with ONJ development. Rather, unresorbed bone surfaces due to impaired osteoclast functions or formation by BPs or Dmab are directly associated with ONJ development.…”

Antiresorptive agent-related osteonecrosis of the jaw: Position Paper 2017 of the Japanese Allied Committee on Osteonecrosis of the Jaw

“…Animal models in which ONJ is induced by administration of BP or RANKL inhibitors, followed by tooth extraction, have recently been developed in mice, rats, dogs and pigs [29][30][31]. It is expected that these animal models allow us to determine the pathophysiology and mechanism of ARONJ and develop new therapeutic interventions for ARONJ.…”

“…Several animal models of ARONJ have been developed over the last several years and have significantly advanced our understanding of the pathophysiology of ARONJ [29][30][31]. However, these animal models only partially represent the pathologic conditions of human ARONJ and clinical relevance of these animal models is yet far satisfactory.…”

Bisphosphonate Uptake in Areas of Tooth Extraction or Periapical Disease

“…For tooth extraction, the left maxillary first and second molars were removed, and the right maxillary molars were kept intact. For experimental periapical disease, the right first and second mandibular molar crowns were drilled to induce pulp exposure, avoiding furcal perforation, 19,20 and the left molars were kept intact.…”