基于辛酰基肉碱介导TRPA1通道的活化研究膝痹宁治疗膝骨关节炎疼痛的作用机理

Pain is the main clinical manifestation of knee osteoarthritis (KOA) and a difficult problem needs to be solved urgently. TRPA1 channel-mediated mechanical pain and cold pain are coincided with the characteristics of KOA pain in terms of “to pain in the cold, but get comfortable in warm; to pain when tired, but get relief if rest were taken.” Our previous study revealed the pathophysiological mechanism of TRPA1 channel involved in KOA pain and the good clinical effect of Xibining in relieving KOA pain. It has been reported that activated TRPA1 channel regulate lipid metabolism and some lipid metabolites activate TRPA1 channel. In the field of KOA, lipid metabolism disorder not only causes KOA pain by low-grade inflammation, but also increases mechanical load of obesity induced by lipid metabolism. It is also a high risk factor of KOA pain. Therefore, the regulation of lipid metabolism is expected to be an effective way to control KOA pain. It was found that the expression of octanoyl-carnitine was directly related to the function of TRPA1 channel and was an effective target of Xibining in our pre-experiment. In combination with the interaction between TRPA1 channel and lipid metabolism, we put forward the scientific hypothesis that lipid metabolism disorder is an important factor to start KOA pain, maintain mechanical pain and cold pain of KOA, Xibining has a good control effect on this link.

疼痛是膝骨关节炎（KOA）的主要临床表现和亟待解决的难题，TRPA1通道介导的机械痛、冷痛与KOA“遇寒则痛，得温则舒；遇劳则痛，休息缓解”的疼痛特点契合。前期研究初步揭示了TRPA1通道参与KOA疼痛的病理机制及膝痹宁缓解KOA疼痛的良好临床疗效。文献研究发现：活化的TRPA1通道调节脂质代谢，部分脂类代谢物又能激活TRPA1通道。在KOA研究领域，脂质代谢紊乱不仅通过低度炎症引起KOA疼痛，其诱导肥胖而增加的机械负荷，同样是KOA疼痛的高危因素。因此，调控脂质代谢有望成为控制KOA疼痛的有效途径。预实验中发现：辛酰基肉碱的表达量与TRPA1功能直接相关，并且是膝痹宁的有效靶点。结合TRPA1通道与脂质代谢的联动效应，我们提出科学假说：脂质代谢紊乱是启动KOA疼痛的重要因素，辛酰基肉碱介导TRPA1通道的活化，启动KOA疼痛，维持KOA的机械痛、冷痛；膝痹宁对此环节具有良好的调控效应。

膝骨关节炎（knee osteoarthritis，KOA）患者常常因为持续的疼痛就医，疼痛也成为KOA首要临床症状和亟待解决的难题。KOA作为一种混合型疼痛，控制外周痛敏在KOA疼痛治疗中尤为关键。研究KOA疼痛的机制发现，背根神经节（dorsal root ganglion，DRG）膜上瞬时受体电位A1离子通道（transient receptor potential A1 channel，TRPA1）激活可导致Ca2+内流，引起痛觉过敏，成为有效药效靶点筛选的关键途径。TRPA1通道介导的机械痛敏、冷痛敏也与KOA“遇寒则痛，得温则舒；遇劳则痛，休息缓解”的疼痛特点契合。基于KOA的疼痛特点，南京中医药大学附属医院骨伤科研制了中药复方——膝痹宁，由制狗脊等11味中药组成，且已获国家专利，在临床上主要用于治疗骨关节退行性疾病导致的慢性疼痛，疗效显著。本课题组前期研究发现，膝痹宁可改善KOA模型大鼠滑膜纤维化和疼痛，但具体作用机制尚不明确。.本研究初步揭示了：膝痹宁可能通过CPT1调控滑膜细胞氧化还原稳态，进而影响DRG细胞膜上TRPA1的Ca2+内流及减少疼痛因子的分泌，发挥减轻KOA疼痛的作用；②膝痹宁对冷痛敏/机械痛敏存在抑制作用，以缓解KOA疼痛；③通过对KOA人群与正常人群的血清代谢差异物分析，揭示左旋肉碱在KOA人群中含量降低，可能通过影响肉碱穿梭调节的脂肪酸β-氧化，参与KOA病程进展；④明确CPT1B在软骨细胞中的细胞器定位，探明左旋肉碱对KOA软骨中AMPK-CPT1B路径的干预作用；⑤左旋肉碱通过AMPK-ACC-CPT1信号通路调节脂质积累和线粒体功能减轻KOA滑膜炎症；⑥利用UPLC-Q-Orbitrap MS/MS技术，探索膝痹宁的药物活性成分，并结合代谢组学分析，表明膝痹宁对KOA大鼠的血清代谢组学存在影响；⑦膝痹宁通过干预AMPK-CPT1B途径发挥KOA软骨保护效应。总之，本研究对于科学阐释膝痹宁方治疗KOA相关新靶点提供了有益的思路。