a Department of Pain Pharmacology , Institute of Pharmacology, Polish Academy of Sciences , Krakow , Poland.
Pharm Biol. 2018 Dec;56(1):275-286. doi: 10.1080/13880209.2018.1457061.
Accumulating evidence has demonstrated that Toll-like receptors (TLRs), especially TLR4 localized on microglia/macrophages, may play a significant role in nociception.
We examine the role of TLR4 in a neuropathic pain model. Using behavioural/biochemical methods, we examined the influence of TLR4 antagonist on levels of hypersensitivity and nociceptive factors whose contribution to neuropathy development has been confirmed.
Behavioural (von Frey's/cold plate) tests were performed with Wistar male rats after intrathecal administration of a TLR4 antagonist (LPS-RS ULTRAPURE (LPS-RSU), 20 μG: lipopolysaccharide from Rhodobacter sphaeroides, InvivoGen, San Diego, CA) 16 H and 1 h before chronic constriction injury (cci) to the sciatic nerve and then daily for 7 d. three groups were used: an intact group and two cci-exposed groups that received vehicle or LPS-RSU. tissue [spinal cord/dorsal root ganglia (DRG)] for western blot analysis was collected on day 7.
The pharmacological blockade of TLR4 diminished mechanical (from ca. 40% to 16% that in the INTACT group) and thermal (from ca. 51% to 32% that in the INTACT group) hypersensitivity despite the enhanced activation of IBA-1-positive cells in DRG. Moreover, LPS-RSU changed the ratio between IL-18/IL-18BP and MMP-9/TIMP-1 in favour of the increase of antinociceptive factors IL-18BP (25%-spinal; 96%-DRG) and TIMP-1 (15%-spinal; 50%-DRG) and additionally led to an increased IL-6 (40%-spinal; 161%-DRG), which is known to have analgesic properties in neuropathy.
Our results provide evidence that LPS-RSU influences pain through the expression of TLR4. TLR4 blockade has analgesic properties and restores the balance between nociceptive factors, which indicates its engagement in neuropathy development.
越来越多的证据表明 Toll 样受体（TLRs），特别是位于小胶质细胞/巨噬细胞上的 TLR4，可能在痛觉过敏中发挥重要作用。
我们研究 TLR4 在神经病理性疼痛模型中的作用。使用行为/生化方法，我们研究了 TLR4 拮抗剂对过敏和痛觉因子水平的影响，这些因子的作用已被证实对神经病变的发展有贡献。
在慢性缩窄性坐骨神经损伤（CCI）前 16 小时和 1 小时鞘内给予 TLR4 拮抗剂（LPS-RS ULTRAPURE（LPS-RSU），20 μG：Rhodobacter sphaeroides 的脂多糖，InvivoGen，圣地亚哥，CA）后，对 Wistar 雄性大鼠进行行为（von Frey's/冷板）测试，然后每天进行 7 天。使用了三组：完整组和两组 CCI 暴露组，分别给予载体或 LPS-RSU。第 7 天收集用于 Western blot 分析的组织（脊髓/背根神经节（DRG））。
尽管 DRG 中 IBA-1 阳性细胞的激活增强，但 TLR4 的药理学阻断减少了机械（从约 40%减少到 INTACT 组的 16%）和热（从约 51%减少到 INTACT 组的 32%）过敏。此外，LPS-RSU 改变了 IL-18/IL-18BP 和 MMP-9/TIMP-1 的比例，有利于增加抗痛觉因子 IL-18BP（25%-脊髓；96%-DRG）和 TIMP-1（15%-脊髓；50%-DRG），并额外导致 IL-6 增加（40%-脊髓；161%-DRG），已知其在神经病变中具有镇痛作用。
我们的结果提供了证据表明 LPS-RSU 通过 TLR4 的表达影响疼痛。TLR4 阻断具有镇痛作用，并恢复了痛觉因子之间的平衡，这表明其参与了神经病变的发展。
