鞘氨醇激酶 1 在脊髓损伤后神经炎症和神经元损伤中的关键作用。
Critical roles of sphingosine kinase 1 in the regulation of neuroinflammation and neuronal injury after spinal cord injury.
机构信息
Department of Orthopaedics, The Third Affiliated Hospital of Wenzhou Medical University, Rui'an People's Hospital, Wenzhou, 325200, Zhejiang, China.
Department of Orthopaedics, Zhu'ji People's Hospital, Shaoxing, 311800, Zhejiang, China.
出版信息
J Neuroinflammation. 2021 Feb 18;18(1):50. doi: 10.1186/s12974-021-02092-4.
BACKGROUND
The pathological process of traumatic spinal cord injury (SCI) involves excessive activation of microglia leading to the overproduction of proinflammatory cytokines and causing neuronal injury. Sphingosine kinase 1 (Sphk1), a key enzyme responsible for phosphorylating sphingosine into sphingosine-1-phosphate (S1P), plays an important role in mediating inflammation, cell proliferation, survival, and immunity.
METHODS
We aim to investigate the mechanism and pathway of the Sphk1-mediated neuroinflammatory response in a rodent model of SCI. Sixty Sprague-Dawley rats were randomly assigned to sham surgery, SCI, or PF543 (a specific Sphk1 inhibitor) groups. Functional outcomes included blinded hindlimb locomotor rating and inclined plane test.
RESULTS
We discovered that Sphk1 is upregulated in injured spinal cord tissue of rats after SCI and is associated with production of S1P and subsequent NF-κB p65 activation. PF543 attenuated p65 activation, reduced inflammatory response, and relieved neuronal damage, leading to improved functional recovery. Western blot analysis confirmed that expression of S1P receptor 3 (S1PR3) and phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK) are activated in microglia of SCI rats and mitigated by PF543. In vitro, we demonstrated that Bay11-7085 suppressed NF-κB p65 and inhibited amplification of the inflammation cascade by S1P, reducing the release of proinflammatory TNF-α. We further confirmed that phosphorylation of p38 MAPK and activation of NF-κB p65 is inhibited by PF543 and CAY10444. p38 MAPK phosphorylation and NF-κB p65 activation were enhanced by exogenous S1P and inhibited by the specific inhibitor SB204580, ultimately indicating that the S1P/S1PR3/p38 MAPK pathway contributes to the NF-κB p65 inflammatory response.
CONCLUSION
Our results demonstrate a critical role of Sphk1 in the post-traumatic SCI inflammatory cascade and present the Sphk1/S1P/S1PR3 axis as a potential target for therapeutic intervention to control neuroinflammation, relieve neuronal damage, and improve functional outcomes in SCI.
背景
创伤性脊髓损伤（SCI）的病理过程涉及小胶质细胞的过度激活，导致促炎细胞因子的过度产生，并导致神经元损伤。鞘氨醇激酶 1（Sphk1）是一种将鞘氨醇磷酸化为鞘氨醇-1-磷酸（S1P）的关键酶，在介导炎症、细胞增殖、存活和免疫中发挥重要作用。
方法
我们旨在研究 Sphk1 介导的 SCI 啮齿动物模型中的神经炎症反应的机制和途径。60 只 Sprague-Dawley 大鼠随机分为假手术、SCI 或 PF543（一种特定的 Sphk1 抑制剂）组。功能结果包括盲法后肢运动评分和斜面试验。
结果
我们发现，SCI 后大鼠损伤脊髓组织中 Sphk1 上调，与 S1P 的产生及其随后的 NF-κB p65 激活有关。PF543 减弱了 p65 激活，减少了炎症反应，减轻了神经元损伤，从而改善了功能恢复。Western blot 分析证实，SCI 大鼠小胶质细胞中 S1P 受体 3（S1PR3）表达和 p38 丝裂原激活蛋白激酶（p38 MAPK）磷酸化被激活，并被 PF543 减轻。在体外，我们证明 Bay11-7085 抑制 NF-κB p65 并抑制 S1P 对炎症级联的放大，减少促炎 TNF-α的释放。我们进一步证实，PF543 和 CAY10444 抑制 p38 MAPK 磷酸化和 NF-κB p65 激活。外源性 S1P 增强 p38 MAPK 磷酸化和 NF-κB p65 激活，而特异性抑制剂 SB204580 抑制其激活，最终表明 S1P/S1PR3/p38 MAPK 途径参与 NF-κB p65 炎症反应。
结论
我们的结果表明 Sphk1 在创伤后 SCI 炎症级联中起关键作用，并提出 Sphk1/S1P/S1PR3 轴作为治疗干预的潜在靶点，以控制神经炎症、减轻神经元损伤并改善 SCI 的功能结果。
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