Mouse anti-RANKL antibody delays oral wound healing and increases TRAP-positive mononuclear cells in bone marrow.

Shinichiro Kuroshima,Junro Yamashita,Zeina Al-Salihi

doi:10.1007/s00784-015-1550-0

Shinichiro Kuroshima, Junro Yamashita + Show 1 more

Open Access

https://doi.org/10.1007/s00784-015-1550-0

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Abstract

ObjectivesDenosumab, a human monoclonal antibody (mAb) that neutralizes receptor activator for nuclear factor κB ligand (RANKL), is associated with osteonecrosis of the jaw. However, the effect of denosumab on oral wounds is unclear. The aim was to determine the effect of anti-RANKL mAb on oral wounds and bone marrow.Materials and methodsThe direct effect of the mAb on fibroblasts, macrophages, and osteoclasts were assessed in vitro. In vivo, mouse anti-RANKL mAb was administered to mice for 9 weeks prior to palatal bone denudation surgery. Mice were euthanized 3 weeks post-surgery, and wound healing was histomorphometrically analyzed. Long bones were assessed using micro-computed tomography, quantitative real-time polymerase chain reaction, and flow cytometry.ResultsThe mAb had no effect on macrophages and fibroblasts but significantly suppressed osteoclast proliferation in vitro. The mAb treatment significantly increased bone mass by suppressing osteoclasts in vivo. The expression of pro-osteoclastic genes was promoted in the bone marrow of the mAb-administered animals. Consistently, the mAb significantly induced the development of tartrate-resistant acid phosphatase (TRAP)-positive mononuclear cells (MNCs) but not osteoclasts in bone marrow. The mAb treatment had no effect on gross healing of the palatal wounds. However, significant inflammation was retained in the connective tissue facing the once denuded bone surface.ConclusionsRepair of the damaged palate was delayed, and significant inflammation was sustained in the connective tissue by anti-RANKL mAb treatment.Clinical relevanceDenosumab impairs osteoclastic bone repair. Care should be exercised to minimize osseous trauma when invasive procedures are performed on patients taking denosumab.

Highlights

Osteoclasts are multinucleated bone-resorbing cells derived from the myeloid lineage that play critical roles in skeletal growth/remodeling, hematopoiesis, bone fracture healing, and bone diseases such as osteoporosis, Paget’s disease of bone, and multiple myeloma
Repair of the damaged palate was delayed, and significant inflammation was sustained in the connective tissue by anti-RANKL monoclonal antibody (mAb) treatment
The anti-RANKL mAb treatment showed no effects on macrophage numbers (Fig. 2a), and consistently, no apoptosisassociated genes were regulated by the mAb treatment (Fig. 3a)

Summary

Introduction

Osteoclasts are multinucleated bone-resorbing cells derived from the myeloid lineage that play critical roles in skeletal growth/remodeling, hematopoiesis, bone fracture healing, and bone diseases such as osteoporosis, Paget’s disease of bone, and multiple myeloma. It has been demonstrated that long-term suppression of osteoclasts by bisphosphonate treatment increases non-attached osteoclasts in bone marrow, i.e., cells are not directly on bone surfaces [1,2,3]. We have found that long-term bisphosphonate treatment is associated with increased numbers of tartrate-resistant acid phosphatase (TRAP)-positive mononuclear cells (MNC) in mouse bone marrow [4]. It was further demonstrated that antiresorptive treatment with bisphosphonates has a negative impact on oral wound healing; bisphosphonate treatment increases inflammatory cell infiltration and reduces collagen apposition in wounds [5, 6]. Osteoclast suppression by potent bisphosphonates alters the cellular environment in bone marrow as well as in oral wound healing.

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