osteoprotegerin and Cherubism

Cherubism is a rare autosomal dominant disorder of the jaws caused by mutation of the SH3BP2 gene. The bone is replaced by a fibrous granuloma containing multinucleated giant cells. Cells of the cherubism granuloma have never been systematically analyzed. Hence, the aim of this study was to characterize the cells in human cherubism granulomas, to determine the osteoclastic characteristics of the multinucleated giant cells and to investigate the potential role of TNF-α in human cherubism.. Seven granulomas were analyzed in pathology, molecular biology and immunohistochemistry. Granulomas were composed mainly of macrophages or osteoclasts within a fibroblastic tissue, with few lymphoid cells. Myeloid differentiation and nuclear NFATc1 localization were both associated with disease aggressiveness. OPG and RANKL immunohistochemical expression was unexpected in our specimens. Five granuloma cells were cultured in standard and osteoclastogenic media. In culture, cherubism cells were able to differentiate into active osteoclasts, in both osteoclastogenic and standard media. IL-6 was the major cytokine present in the culture supernatants.. Multinucleated giant cells from cherubism granulomas are CD68 positive cells, which differentiate into macrophages in non-aggressive cherubism and into osteoclasts in aggressive cherubism, stimulated by the NFATc1 pathway. This latter differentiation appears to involve a disturbed RANK-L/RANK/OPG pathway and be less TNF-α dependent than the cherubism mouse model.

Topics: Adaptor Proteins, Signal Transducing; Adolescent; Adult; Cell Differentiation; Cherubism; Child; Female; Humans; Immunohistochemistry; Interleukin-6; Leukocytes, Mononuclear; Male; Middle Aged; Mutation; NFATC Transcription Factors; Osteoclasts; Osteogenesis; Osteoprotegerin; RANK Ligand; Receptors, Tumor Necrosis Factor, Type I; Tumor Cells, Cultured; Vimentin; Young Adult

Cherubism is a rare genetic disorder characterized by extensive growth of a bilateral granuloma of the jaws, resulting in facial disfigurement. Cherubism is caused by gain-of-function mutations in the SH3BP2 gene, leading to overactivation of nuclear factor of activated T cells, cytoplasmic 1 (NFATc1)-dependent osteoclastogenesis. Recent findings in human and mouse cherubism have suggested that calcineurin inhibitors might be drug candidates in cherubism medical treatment. A 4-year-old boy with aggressive cherubism was treated with the calcineurin inhibitor tacrolimus for 1 year, and clinical, radiological, and molecular data were obtained. Immunohistologic analysis was performed to compare preoperative and postoperative NFATc1 staining and tartrate resistant acid phosphatase (TRAP) activity. Real-time PCR was performed to analyze the relative expression levels of OPG and RANKL. After tacrolimus therapy, the patient showed significant clinical improvement, including stabilization of jaw size and intraosseous osteogenesis. Immunohistologic analyses on granuloma showed that tacrolimus caused a significant reduction in the number of TRAP-positive osteoclasts and NFATc1 nuclear staining in multinucleated giant cells. Molecular analysis showed that tacrolimus treatment also resulted in increased OPG expression. We present the first case of effective medical therapy in cherubism. Tacrolimus enhanced bone formation by stimulating osteogenesis and inhibiting osteoclastogenesis.

Topics: Acid Phosphatase; Calcineurin Inhibitors; Cell Count; Cherubism; Child, Preschool; Humans; Isoenzymes; Male; Models, Biological; NFATC Transcription Factors; Osteoclasts; Osteogenesis; Osteoprotegerin; Radiography; RANK Ligand; Tacrolimus; Tartrate-Resistant Acid Phosphatase

Osteoporosis results from an imbalance in skeletal remodeling that favors bone resorption over bone formation. Bone matrix is degraded by osteoclasts, which differentiate from myeloid precursors in response to the cytokine RANKL. To gain insight into the transcriptional regulation of bone resorption during growth and disease, we generated a conditional knockout of the transcription factor nuclear factor of activated T cells c1 (Nfatc1). Deletion of Nfatc1 in young mice resulted in osteopetrosis and inhibition of osteoclastogenesis in vivo and in vitro. Transcriptional profiling revealed NFATc1 as a master regulator of the osteoclast transcriptome, promoting the expression of numerous genes needed for bone resorption. In addition, NFATc1 directly repressed osteoclast progenitor expression of osteoprotegerin, a decoy receptor for RANKL previously thought to be an osteoblast-derived inhibitor of bone resorption. "Cherubism mice", which carry a gain-of-function mutation in SH3-domain binding protein 2 (Sh3bp2), develop osteoporosis and widespread inflammation dependent on the proinflammatory cytokine, TNF-alpha. Interestingly, deletion of Nfatc1 protected cherubism mice from systemic bone loss but did not inhibit inflammation. Taken together, our study demonstrates that NFATc1 is required for remodeling of the growing and adult skeleton and suggests that NFATc1 may be an effective therapeutic target for osteoporosis associated with inflammatory states.

Topics: Animals; Bone Diseases, Metabolic; Cherubism; Inflammation; Mice; Mice, Knockout; Mice, Transgenic; NFATC Transcription Factors; Osteoclasts; Osteoprotegerin

The nature and the mechanism involved in the formation of the multinucleated giant cells (MGCs) in various giant cell-containing lesions of the jaws are not fully understood. The aim of this study is to clarify the osteoclastic features of the MGCs in central giant cell granuloma (CGCG), peripheral giant cell granuloma (PGCG), cherubism, and aneurysmal bone cyst (ABC), and the mechanism underlying the interrelations between cellular components in the formation of the MGCs.. Immunohistochemical study with a panel of antibodies including vacuolar H+-ATPase (V-ATPase), carbonic anhydrase II (CA II), Cathepsin K, matrix metalloproteinases-9 (MMP-9), CD68, and proliferating cell nuclear antigen (PCNA), and enzyme histochemical staining for tartarate-resistant acid phosphatase (TRAP) were applied on a total number of 53 cases of giant cell-containing lesions including CGCG (n = 34), PGCG (n = 6), cherubism (n = 7), and ABC (n = 6). In situ hybridization was also carried out to detect the mRNA expression of the receptor activator of NF-kappaB ligand (RANKL), a newly identified cytokine that is shown to be essential in the osteoclastogenesis, its receptor RANK (receptor activator of NF-kappaB ligand), and its decoy receptor OPG (osteoprotegerin) in these four types of lesions.. Immunohistochemical and enzyme histochemical studies showed that both the MGCs and a fraction of mononuclear cells in these lesions were strongly positive for TRAP, V-ATPase, CA II, Cathepsin K, MMP-9, and CD68, while the spindle-shaped mononuclear cells were positive for PCNA. The results with in situ hybridization indicated that RANKL mRNA was mainly expressed in the spindle mononuclear cells while OPG was extensively distributed in both the MGCs and the mononuclear cells. RANK mRNA was expressed in the MGCs and some round mononuclear cells.. These results suggest that MGCs in the four types of giant cell-containing lesions of the jaws show characteristics of the osteoclast phenotype. The mononuclear stromal cells, which show TRAP positively, may be the precursors of the MGCs. RANKL, OPG, and RANK expressed in these lesions may play important roles in the formation of the MGCs. The similar characteristics and mechanisms in the differentiation of MGCs in these lesions also suggest that there might be a similar kind of pathogenesis involved in the formation of the MGCs in these lesions

Topics: Bone Cysts, Aneurysmal; Carrier Proteins; Cell Differentiation; Cherubism; Gene Expression Regulation, Developmental; Giant Cells; Glycoproteins; Granuloma, Giant Cell; Humans; Immunohistochemistry; In Situ Hybridization; Jaw Diseases; Membrane Glycoproteins; Osteoclasts; Osteoprotegerin; Phenotype; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; RNA, Messenger