基于条件性损伤后轴突再生的分子机制发现脊髓损伤的治疗靶点。

BACKGROUND: Preinjury of peripheral nerves triggers dorsal root ganglia (DRG) axon regeneration, a biological change that is more pronounced in young mice than in old mice, but the complex mechanism has not been clearly explained. Here, we aim to gain insight into the mechanisms of axon regeneration after conditioning lesion in different age groups of mice, thereby providing effective therapeutic targets for central nervous system (CNS) injury. METHODS: The microarray GSE58982 and GSE96051 were downloaded and analyzed to identify differentially expressed genes (DEGs). The protein-protein interaction (PPI) network, the miRNA-TF-target gene network, and the drug-hub gene network of conditioning lesion were constructed. The L4 and L5 DRGs, which were previously axotomized by the sciatic nerve conditioning lesions, were harvested for qRT-PCR. Furthermore, histological and behavioral tests were performed to assess the therapeutic effects of the candidate drug telmisartan in spinal cord injury (SCI). RESULTS: A total of 693 and 885 DEGs were screened in the old and young mice, respectively. Functional enrichment indicates that shared DEGs are involved in the inflammatory response, innate immune response, and ion transport. QRT-PCR results showed that in DRGs with preinjury of peripheral nerve, Timp1, P2ry6, Nckap1l, Csf1, Ccl9, Anxa1, and C3 were upregulated, while Agtr1a was downregulated. Based on the bioinformatics analysis of DRG after conditioning lesion, Agtr1a was selected as a potential therapeutic target for the SCI treatment. In vivo experiments showed that telmisartan promoted axonal regeneration after SCI by downregulating AGTR1 expression. CONCLUSION: This study provides a comprehensive map of transcriptional changes that discriminate between young and old DRGs in response to injury. The hub genes and their related drugs that may affect the axonal regeneration program after conditioning lesion were identified. These findings revealed the speculative pathogenic mechanism involved in conditioning-dependent regenerative growth and may have translational significance for the development of CNS injury treatment in the future.

背景：外周神经损伤会引发背根神经节（DRG）轴突再生，这种生物学变化在年轻小鼠中比在老年小鼠中更为明显，但复杂的机制尚未得到明确解释。在这里，我们旨在深入了解不同年龄组小鼠在条件性损伤后轴突再生的机制，从而为中枢神经系统（CNS）损伤提供有效的治疗靶点。

方法：下载并分析 microarray GSE58982 和 GSE96051 以鉴定差异表达基因（DEGs）。构建条件性损伤的蛋白质-蛋白质相互作用（PPI）网络、miRNA-TF-靶基因网络和药物-关键基因网络。以前通过坐骨神经条件性损伤切断 L4 和 L5 DRG 神经，用于 qRT-PCR。此外，进行组织学和行为学测试以评估候选药物替米沙坦在脊髓损伤（SCI）中的治疗效果。

结果：在老年和年轻小鼠中分别筛选出 693 和 885 个 DEGs。功能富集表明，共享 DEGs 参与炎症反应、固有免疫反应和离子转运。qRT-PCR 结果显示，在有周围神经预先损伤的 DRG 中，Timp1、P2ry6、Nckap1l、Csf1、Ccl9、Anxa1 和 C3 上调，而 Agtr1a 下调。基于 DRG 条件性损伤后的生物信息学分析，选择 Agtr1a 作为 SCI 治疗的潜在治疗靶点。体内实验表明，替米沙坦通过下调 AGTR1 表达促进 SCI 后轴突再生。

结论：本研究提供了一个全面的转录变化图谱，可区分年轻和老年 DRG 对损伤的反应。确定了可能影响条件性损伤后轴突再生程序的关键基因及其相关药物。这些发现揭示了与条件依赖性再生性生长相关的推测发病机制，可能对未来 CNS 损伤治疗的发展具有转化意义。