Department of Orthopaedic Surgery, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu, Mie, 514-8507, Japan.
Calcif Tissue Int. 2019 Jun;104(6):658-666. doi: 10.1007/s00223-019-00521-4. Epub 2019 Jan 21.
The aim of this study was to evaluate skeletal pain associated with osteoporosis and examine the inhibitory effect of interleukin-6 (IL-6) on pain in ovariectomized (OVX) mice. The mechanism of osteoporotic pain in OVX mice was evaluated by examining pain-related behavior and immunohistochemistry. The effects of IL-6 receptor inhibitor (IL-6i) on these parameters were also assessed. Eight-week-old female ddY mice were ovariectomized and assigned to three groups: OVX mice treated with vehicle (OVX); OVX mice treated with alendronate (OVX-ALN); and OVX mice treated with anti-IL-6 receptor (anti-IL-6R) antibody (OVX-IL6i). Sham-operated mice were treated with vehicle. Immediately after surgery, vehicle, ALN, or anti-IL-6R antibody was injected subcutaneously. After a 4-week treatment, mechanical sensitivity was examined using von Frey filaments. The bilateral distal femoral metaphyses and proximal tibial metaphyses were analyzed three-dimensionally with micro-computed tomography. Calcitonin gene-related peptide (CGRP) expression in L3-L5 dorsal root ganglion (DRG) neurons was examined using immunohistochemistry. Ovariectomy induced bone loss and mechanical hyperalgesia in the hindlimbs with upregulation of CGRP expression in the DRG neurons innervating the hindlimbs. ALN treatment prevented bone loss, but anti-IL-6R antibody treatment had no effect on bone morphometry compared with that of the OVX group. However, mechanical hyperalgesia and CGRP expression were significantly decreased in the OVX-IL6i and OVX-ALN groups compared with those in the OVX group. Although anti-IL-6R antibody treatment had no effect on ovariectomy-induced bone loss, the treatment prevented ovariectomy-induced mechanical hyperalgesia in the hindlimbs and suppressed CGRP expression in DRG neurons. The results suggest that IL-6 is one of the causes of postmenopausal osteoporotic pain, and anti-IL-6R antibody might preserve bone health and decrease osteoporotic pain.
本研究旨在评估与骨质疏松症相关的骨骼疼痛，并研究白细胞介素-6（IL-6）对去卵巢（OVX）小鼠疼痛的抑制作用。通过观察疼痛相关行为和免疫组织化学，评估 OVX 小鼠骨质疏松性疼痛的机制。还评估了 IL-6 受体抑制剂（IL-6i）对这些参数的影响。将 8 周龄雌性 ddY 小鼠去卵巢并分为三组：用载体（OVX）处理的 OVX 小鼠；用阿仑膦酸钠（OVX-ALN）处理的 OVX 小鼠；和用抗白细胞介素-6 受体（抗 IL-6R）抗体（OVX-IL6i）处理的 OVX 小鼠。假手术组用载体处理。手术后立即皮下注射载体、ALN 或抗 IL-6R 抗体。经过 4 周的治疗，使用 von Frey 纤维检查机械敏感性。使用 micro-CT 对双侧股骨远端和胫骨近端进行三维分析。使用免疫组织化学检查支配后肢的 L3-L5 背根神经节（DRG）神经元中降钙素基因相关肽（CGRP）的表达。卵巢切除导致后肢骨丢失和机械性痛觉过敏，并上调支配后肢的 DRG 神经元中 CGRP 的表达。ALN 治疗可预防骨丢失，但与 OVX 组相比，抗 IL-6R 抗体治疗对骨形态计量学无影响。然而，与 OVX 组相比，OVX-IL6i 和 OVX-ALN 组的机械性痛觉过敏和 CGRP 表达显著降低。虽然抗 IL-6R 抗体治疗对卵巢切除引起的骨丢失没有影响，但该治疗可预防后肢卵巢切除引起的机械性痛觉过敏，并抑制 DRG 神经元中 CGRP 的表达。结果表明，IL-6 是绝经后骨质疏松性疼痛的原因之一，抗 IL-6R 抗体可能有助于维持骨骼健康并减轻骨质疏松性疼痛。
