MG通过表观遗传学介导Nav1.6上调在化疗药硼替佐米诱导中枢敏化和痛觉过敏的作用及机制

Chronic pain induced by bortezomib (BTZ) treatment is an important clinical trouble. Currently the underlying mechanism remains unclear. Recently, we found that the level of methylglyoxal (MG) in the cerebrospinal fluid was increased and the level of MG in the blood was positive related to the grade of pain in the patients with BTZ treatment, and scavenging of methylglyoxal in spinal cord of rats by aminoguanidine significantly inhibited the mechanical allodynia and upregulation of RAGE in spinal dorsal horn after BTZ treatment. Studies indicated that BTZ treatment significantly downregulated Glutathione (GSH) which played an important role in the metabolism of MG, and RAGE participated in the synapses plasticity of hippocampus via activating the transcript factor STAT3. Our pilot experiment further showed that local application of Nav1.6 siRNA prevented the spinal LTP induced by HFS and mechanical allodynia induced by BTZ, and four potential binding sites for STAT3 were predicted on the Nav1.6 promoter region. These data suggested that the accumulation of MG which mediated by GSH downregulation, activated the RAGE/STAT3 signal pathway and induced the transcript of Nav1.6, thereby leading to the central sensitization and mechanical allodynia induced by BTZ. In this project, we will explore: 1) the role of GSH/MG/Nav1.6 pathway in the central sensitization and mechanical allodynia induced by bortezomib; 2) the epigenetic mechanism of MG-mediated Nav1.6 upregulation. The objective of the research will provide new targets for clinical prevention and treatment of bortezomib-induced pathological pain.

硼替佐米（BTZ）所致的痛觉过敏严重影响了肿瘤患者的治疗及生活质量，机制不清。我们发现：BTZ化疗后患者脑脊液中丙酮醛（MG）显著增加，且血液中MG含量与疼痛程度呈正相关；清除大鼠脊髓MG抑制BTZ诱导的触诱发痛及糖代谢终末产物受体（RAGE）上调。研究显示：BTZ可抑制代谢MG关键物-还原性谷胱甘肽（GSH）的合成；RAGE通过激活转录因子STAT3参与调节海马突触传递效率。我们也发现：脊髓局部应用Nav1.6 siRNA抑制脊髓背角LTP及BTZ诱导的触诱发痛，且STAT3与Nav1.6启动子区域有潜在结合位点。提示BTZ通过GSH上调MG，激活RAGE/STAT3通路，促进Nav1.6转录，介导痛觉过敏，相关内容未见报道。本项目将：1）明确脊髓GSH介导MG上调在BTZ诱导痛觉过敏中的作用及机制；2）探讨MG介导Nav1.6上调的表观遗传学机制，为防治化疗药诱导的痛觉过敏提供新靶点。

硼替佐米作为一种一线化疗药物，广泛应用于多发性骨髓瘤和其他非实体恶性肿瘤。虽然硼替佐米引起的持续性疼痛在临床上易于诊断，但其发病机制尚不清楚。该项目通过连续5天全身腹腔注射硼替佐米的大鼠模型研究该科学问题。与我们之前的研究一致，我们发现硼替佐米治疗可显著诱导大鼠机械性痛觉异常。此外，我们首次发现硼替佐米能显著地诱导大鼠脊髓背角丙酮醛（MG）的上调。在正常大鼠脊髓局部应用MG也可引起机械性痛觉超敏和中枢敏化此外，硼替佐米增加了晚期糖基化终产物受体（RAGE）和磷酸化STAT3（p-STAT3）在背角的表达。重要的是，鞘内注射二甲双胍，一种已知的MG清除剂，能显著地减弱MG和RAGE在背角的上调，抑制硼替佐米治疗引起的中枢敏化和机械性痛觉过敏，阻断RAGE也能阻止p-STAT3的上调、硼替佐米诱导的中枢敏化和机械性痛觉过敏。此外，S3I-201抑制STAT3活性减弱了硼替佐米诱导的机械性痛觉过敏和中枢敏化。局部敲除STAT3也改善了硼替佐米引起的机械性痛觉过敏。我们的研究表明，MG的积累可能激活背角RAGE/STAT3信号通路，参与硼替佐米引起的脊髓中枢敏化和持续性疼痛的发生。这一研究为化疗药物所致持续性疼痛的治疗提供了新的选择。