RANKL inhibition reduces lesional cellularity and Gα s variant expression and enables osteogenic maturation in fibrous dysplasia.
Luis Fernandez de CastroJarred M WhitlockZachary MichelKristen PanJocelyn TaylorVivian SzymczukBrendan F BoyceDaniel MartinVardit KramRebeca GalisteoKamran MelikovLeonid V ChernomordikMichael T CollinsAlison M BoycePublished in: Bone research (2024)
Fibrous dysplasia (FD) is a rare, disabling skeletal disease for which there are no established treatments. Growing evidence supports inhibiting the osteoclastogenic factor receptor activator of nuclear kappa-B ligand (RANKL) as a potential treatment strategy. In this study, we investigated the mechanisms underlying RANKL inhibition in FD tissue and its likely indirect effects on osteoprogenitors by evaluating human FD tissue pre- and post-treatment in a phase 2 clinical trial of denosumab (NCT03571191) and in murine in vivo and ex vivo preclinical models. Histological analysis of human and mouse tissue demonstrated increased osteogenic maturation, reduced cellularity, and reduced expression of the pathogenic Gα s variant in FD lesions after RANKL inhibition. RNA sequencing of human and mouse tissue supported these findings. The interaction between osteoclasts and mutant osteoprogenitors was further assessed in an ex vivo lesion model, which indicated that the proliferation of abnormal FD osteoprogenitors was dependent on osteoclasts. The results from this study demonstrated that, in addition to its expected antiosteoclastic effect, denosumab reduces FD lesion activity by decreasing FD cell proliferation and increasing osteogenic maturation, leading to increased bone formation within lesions. These findings highlight the unappreciated role of cellular crosstalk between osteoclasts and preosteoblasts/osteoblasts as a driver of FD pathology and demonstrate a novel mechanism of action of denosumab in the treatment of bone disease.TRIAL REGISTRATION: ClinicalTrials.gov NCT03571191.
Keyphrases
- bone loss
- nuclear factor
- endothelial cells
- clinical trial
- mesenchymal stem cells
- bone mineral density
- poor prognosis
- bone marrow
- induced pluripotent stem cells
- randomized controlled trial
- single cell
- pluripotent stem cells
- postmenopausal women
- body composition
- replacement therapy
- open label
- climate change
- inflammatory response
- atomic force microscopy
- wild type