Anti-RANKL antibodies decrease CGRP expression in dorsal root ganglion neurons innervating injured lumbar intervertebral discs in rats

作者：Sato Masashi; Inage Kazuhide; Sakuma Yoshihiro; Sato Jun; Orita Sumihisa; Yamauchi Kazuyo; Eguchi Yawara; Ochiai Nobuyasu; Kuniyoshi Kazuki; Aoki Yasuchika; Nakamura Junichi; Miyagi Masayuki; Suzuki Miyako; Kubota Gou; Sainoh Takeshi; Fujimoto Kazuki; Shiga Yasuhiro; Abe Koki; Kanamoto Hiroto; Inoue Gen; Takahashi Kazuhisa; Ohtori Seiji^*

来源：European Spine Journal, 2015, 24(9): 2017-2022.

DOI：10.1007/s00586-015-4058-z

• Pain
• Nerve
• Intervertebral disc
• RANKL
• CGRP

Nuclear factor-kappa B (NF-kappa B), receptor activator of NF-kappa B (RANK), and RANK ligand (RANKL) are transcriptional regulators of inflammatory cytokines. RANKL expression in dorsal root ganglion (DRG) neurons is elevated in animal models of pain or intervertebral disc herniation. We sought to evaluate the effect of anti-RANKL antibodies on sensory nerves innervating injured intervertebral discs.
We labeled DRG neurons innervating L5-6 discs with FluoroGold (FG). The L5-6 discs of 36 rats were punctured using a 23-gage needle and 18 rats underwent sham surgery without disc puncture. The puncture group was evenly subdivided into a group in which 10 mu l saline was administered to the injured disc and a group in which 10 mu l of anti-RANKL antibody was administered. Seven and 14 days postsurgery, DRGs at L2 level were harvested, sectioned, and immunostained for calcitonin gene-related peptide (CGRP). The proportion of CGRP-immunoreactive (IR) DRG neurons of all FG-positive neurons was determined. Amount of tumor necrosis factor (TNF)-alpha and interleukin(IL)-6 was measured within the intervertebral discs in each group at 7 and 14 days after surgery using an enzyme-linked immunosorbent assay (ELISA).
The proportion of CGRP-IR DRG neurons to total FG-labeled neurons innervating injured intervertebral discs and amount of TNF-alpha and IL-6 in the injured discs in the saline control group was significantly increased compared with that found in rats from the sham surgery group (P < 0.05). However, application of anti-RANKL antibody to the injured discs significantly decreased the proportion of CGRP-IR DRG neurons to total FG-labeled neurons and amount of TNF-alpha and IL-6 in the injured discs (P < 0.05).
TNF-alpha and IL-6 in the injured discs increased and CGRP expression increased in DRG neurons innervating injured discs, and antibodies to RANKL could suppress this increased TNF-alpha, IL-6, and CGRP expression. RANKL may be a therapeutic target for pain control in patients with lumbar disc degeneration.

• 出版日期2015-9