HO-1调控髓核细胞自噬治疗椎间盘退变的机制研究

Intervertebral disc degeneration (IDD) resulted from nucleus pulposus cell (NPC) degeneration is the main cause of a series of spinal degenerative diseases. The inflammatory imbalance and metabolism disorder in extracellular matrix (ECM) of NPC caused by the deposition of pro-inflammatory cytokines in NP is the pathological base of NPC degeneration. However, the outcome of anti-inflammatory treatments for IDD are unfavorable. Recent studies revealed that cell autophagy has a potential anti-inflammatory and cytoprotection effect. However, there is few reports address the role of autophagy in the anti-inflammatory treatments of IDD. Our previous studies have shown that the expression of autophagy markers were lower in IDD clinical samples using high-throughput sequencing technique (RNA-Seq). In bioinformatic studies, we also found that heme oxygenase-1 (HO-1) was a potential activator of autophagy. Based on these results, we propose that HO-1 might be a key regulator of autophagy in NPC and activation of autophagy by HO-1 could raise the anti-inflammatory ability of NPC, thus could alleviate ECM metabolism disorder and the process of IDD. In this study, the pathological mechanism HO-1 regulated NPC autophagy and its influence on IDD pathogenetic process will be elucidated at molecule, cell, transgenetic animal model and histopathology levels. This study contributes to further clarify the pathogenesis and to explore novel therapeutic targets of IDD.

髓核细胞(NPC)退变引致的椎间盘退变(IDD)是一系列脊柱退变性疾病重要病因。其中NPC细胞外基质(ECM)中炎症因子累积导致炎症失衡及代谢紊乱是NPC退变的病理基础。目前以椎间盘抗炎为靶向的治疗效果并不理想。近年研究证实，细胞自噬参与机体抗炎及细胞保护过程，但其在椎间盘抗炎治疗中的作用尚缺乏研究。本课题组前期通过转录组测序证实自噬相关基因在IDD中表达下调，进一步通过生物信息学分析发现IDD中血红素加氧酶-1(HO-1)为NPC自噬潜在激活因子。基于前期研究我们提出以下假设：通过HO-1途径调控NPC自噬水平，可上调NPC抗炎能力，拮抗ECM代谢紊乱，延缓甚至逆转IDD病变进程。本课题拟通过分子、细胞、转基因动物实验等方法揭示HO-1调控NPC自噬的机制及其对IDD病理进程的影响。本研究有助于进一步阐明IDD发病机制，为IDD治疗开拓新途径。

本项目延续自申请人前两项国家自然科学基金项目（30400452、81171752），针对椎间盘退变（IDD）进行病因机制研究。根据前期研究中发现的在椎间盘中存在严重的炎症反应失衡且HO-1可在其中起缓解作用这一现象，进一步探索HO-1以及自噬在拮抗椎间盘退变中过度炎症反应的具体机制，通过明确该机制对揭示如何通过在HO-1调控自噬中干预相关分子靶点起到拮抗椎间盘退变中过度炎症反应的作用，从而缓解甚至逆转椎间盘退变的发生发展。通过本项目的实施，课题组在前期研究基础上针对IDD及正常椎间盘HO-1及自噬相关基因表达量进行多种分子生物学手段进行的多层次对比研究在国际上未见报道，首次发现HO-1及自噬相关基因在IDD髓核组织中表达下调。通过进一步研究，发现氧化应激通路位于HO-1自噬轴上游，且该调控是通过Nrf2转录因子介导的；发现激活HO-1自噬轴可抑制髓核细胞氧化应激带来的细胞外基质代谢紊乱；发现HO-1可活化通过ATG7活化自噬通路，并通过自噬通路Keap1/Nrf2/p62调控细胞外基质基因表达。此外在转化应用方面，利用该数据结合临床样本对HO-1、Nrf2、ATG7等基因表达检测，提示HO-1自噬轴中关键基因对IDD同样具有诊断价值。课题组在本项目实施中共发表SCI论著7篇，为后续针对IDD发病机制的进一步深入研究打下了重要的理论基石，也为今后IDD的生物治疗带来新的路径。