Fas ligand plays an important role for the production of pro-inflammatory cytokines in intervertebral disc nucleus pulposus cells.

It is suggested that pro-inflammatory cytokines, which are produced by interaction of the intervertebral nucleus pulposus cells and macrophages, may be linked to the cause of pain of the intervertebral disc herniation. This study carries out the in vitro experiments to examine the mechanism, with the use of the co-culture of an immortalized cell line of nucleus pulposus of the human intervertebral disc and the macrophage cell line. As a result, it is found that the production of pro-inflammatory cytokines is significantly larger at the co-culture group than at the independent culture group. Also, at the co-culture group of macrophages and intervertebral nucleus pulposus cells with over-expression of fas ligand (FasL), the production of pro-inflammatory cytokines is found to be far larger. Furthermore, it is found that these pro-inflammatory cytokines are produced mainly by the intervertebral nucleus pulposus cells with over-expression of FasL, and that the expression of a disintegrin and metalloproteinase (ADAM) 10, which controls the expression of FasL and activates reverse signaling inside cells, also increases. From these findings, it is suggested that FasL and ADAM10 play an important role in the production of pro-inflammatory cytokines coming from interaction of the intervertebral nucleus pulposus cells and macrophages.