The role of osteoprotegerin in arthritis

Table 1 Outcome of arthritis in osteoclast-free mouse models

	Pettit et al. [11]	Redlich et al. [14]
Arthritis model	K/BxN (serum transfer)	hTNF transgenic
Osteoclast-deficiency model	RANKL^-/-	c-fos^-/-
Mechanism of arthritis	Immune complex driven	Cytokine overexpression
Mechanism of bone pathology	Stromal cell defect^a	Bone marrow cell defect^b
Effect on inflammation	No	No
Effect on cartilage damage	Partly^c	No
Effect on bone erosion	Yes	Yes
Presence of osteoclasts	No	No

^a Absent receptor-activator of nuclear factor kappa B ligand (RANKL) expression on stromal cells blocks osteoclastogenesis. Osteoclast precursor cells are normal and express receptor-activator of nuclear factor kappa B (RANK). ^b Blockade of osteoclastogenesis is downstream of RANK and is limited to the osteoclast lineage. RANKL expression by stromal cells is normal. ^c 0–50% inhibition of cartilage damage; positive effects predominantly found at the forefoot.

ISSN: 1478-6362