异常应力调控成骨细胞分泌NGF介导膝骨关节炎疼痛敏化的作用机制及右归饮的干预研究

膝骨性关节炎（KOA）是骨伤科最常见的关节疾病，疼痛是KOA患者最突出的症状，然而目前对于KOA的疼痛机制并不明确。研究发现KOA疼痛期与骨形成活跃期高度吻合，这提示成骨细胞极有可能是参与介导疼痛的关键细胞。有研究报道异常应力可刺激骨膜的成骨细胞分泌NGF，作用于感觉神经TrkA受体介导疼痛。而KOA的发病与异常应力密切相关，同时，前期研究发现在KOA发病过程中软骨下骨区域的NGF分泌增加，而补肾经方“右归饮”可显著抑制NGF的表达，基于此，申请人提出科学假说“右归饮通过抑制软骨下骨成骨细胞分泌NGF改善膝骨关节炎疼痛敏化”。本研究拟借助特异性靶标成骨细胞的荧光报告小鼠、成骨细胞特异性NGF基因敲除小鼠、感觉神经特异性TrkA基因敲除小鼠等，探究KOA发病中成骨细胞分泌NGF介导疼痛敏化的作用机制，同时基于“肾主骨生髓”理论，阐明右归饮调控成骨细胞抑制NGF表达，缓解KOA疼痛的潜在机制。

Knee osteoarthritis (KOA) is a common joint disease in clinic and pain is the most prominent symptom of KOA patients. However, the mechanism of KOA pain is still unclear. Since the phase of KOA pain was highly consistent with the phase of abnormal subchondral bone formation, it is suggested that osteoblasts may be the key cells involved in mediating KOA pain. Studies have reported that abnormal stress can stimulate osteoblasts in periosteum to secrete NGF, which acts on sensory nerve TrkA receptor and mediated pain sensitization. The onset of KOA is closely related to the abnormal stress, at the same time, our preliminary study found the NGF expression in subchondral bone is increased with KOA pathogenesis. Importantly, Youguiyin could significantly improve abnormal bone remodeling and suppressed NGF expression in subchondral bone. Based on this, we put forward a hypothesis that Youguiyin could inhibit NGF secretion derived from osteoblast in subchondral bone and improve knee osteoarthritis pain sensitization. This study, we firstly intends to investigate the NGF secretion derived from osteoblast with OC-Cre;tdTomato mice in the pathogenetic process of KOA. We also resort to OC-Cre;NGFflox/flox and Advillin-Cre;TrkAflox/flox conditional knockout mice to illuminate the role of NGF/TrkA axis in pain sensitization in subchondral bone. In the meantime, based on the theory of “Kidney governs the bones and engenders marrow”, we plan to explore the potential mechanism of Youguiyin in regulating NGF expression derived from osteoblast and relieving KOA pain.