Work

TNF-α induces osteoclastogenesis by direct stimulation of macrophages exposed to permissive levels of RANK ligand

Year: 2000

Type: article

Abstract: While TNF-alpha is pivotal to the pathogenesis of inflammatory osteolysis, the means by which it recruits osteoclasts and promotes bone destruction are unknown. We find that a pure population of murine osteoclast precursors fails to undergo osteoclastogenesis when treated with TNF-alpha alone. In contrast, the cytokine dramatically stimulates differentiation in macrophages primed by less than one percent of the amount of RANKL (ligand for the receptor activator of NF-kappaB) required to induce osteoclast formation. Mirroring their synergistic effects on osteoclast differentiation, TNF-alpha and RANKL markedly potentiate NF-kappaB and stress-activated protein kinase/c-Jun NH(2)-terminal kinase activity, two signaling pathways essential for osteoclastogenesis. In vivo administration of TNF-alpha prompts robust osteoclast formation in chimeric animals in which ss-galactosidase positive, TNF-responsive macrophages develop within a TNF-nonresponsive stromal environment. Thus, while TNF-alpha alone does not induce osteoclastogenesis, it does so both in vitro and in vivo by directly targeting macrophages within a stromal environment that expresses permissive levels of RANKL. Given the minuscule amount of RANKL sufficient to synergize with TNF-alpha to promote osteoclastogenesis, TNF-alpha appears to be a more convenient target in arresting inflammatory osteolysis.

Source: Journal of Clinical Investigation

DOI: 10.1172/jci11176

Authors: Jonathan Lam, Sunao Takeshita, Jane E. Barker, Osami Kanagawa, F. Patrick Ross, Steven L. Teitelbaum

Institutions: Washington University in St. Louis, Barnes-Jewish Hospital, Jackson Laboratory

Language: English

Topic: Bone Metabolism and Diseases

Subfield: Molecular Biology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

SDG: Good health and well-being

Open Access status: bronze

Funders: National Institutes of Health, National Institute of General Medical Sciences, National Institute of Diabetes and Digestive and Kidney Diseases, National Institute of Arthritis and Musculoskeletal and Skin Diseases