Netrin 1 was initially identified as an axon guidance factor, and recent studies indicate that it
inhibits chemokine-directed monocyte migration. Despite its importance as a neuroimmune
guidance cue, the role of netrin 1 in osteoclasts is largely unknown. Here we detected high
netrin 1 levels in the synovial fluid of rheumatoid arthritis patients. Netrin 1 is potently
expressed in osteoblasts and synovial fibroblasts, and IL-17 robustly enhances netrin 1
expression in these cells. The binding of netrin 1 to its receptor UNC5b on osteoclasts …