Chenjian Wang1, Tianzhen Xu2, Brittany Bolduc Lachance3, Xiqiang Zhong1, Guangjie Shen1, Tao Xu1, Chengxuan Tang4, Xiaofeng Jia5,6,7,8,9. 1. Department of Orthopaedics, The Third Affiliated Hospital of Wenzhou Medical University, Rui'an People's Hospital, Wenzhou, 325200, Zhejiang, China. 2. Department of Orthopaedics, Zhu'ji People's Hospital, Shaoxing, 311800, Zhejiang, China. 3. Program in Trauma, Department of Neurology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA. 4. Department of Orthopaedics, The Third Affiliated Hospital of Wenzhou Medical University, Rui'an People's Hospital, Wenzhou, 325200, Zhejiang, China. tangchengxuan@wmu.edu.cn. 5. Department of Neurosurgery, University of Maryland School of Medicine, 10 South Pine Street, MSTF Building 823, Baltimore, MD, 21201, USA. xjia@som.umaryland.edu. 6. Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD, 21201, USA. xjia@som.umaryland.edu. 7. Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA. xjia@som.umaryland.edu. 8. Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA. xjia@som.umaryland.edu. 9. Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA. xjia@som.umaryland.edu.
Abstract
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.
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.
Authors: Sergio E Alvarez; Kuzhuvelil B Harikumar; Nitai C Hait; Jeremy Allegood; Graham M Strub; Eugene Y Kim; Michael Maceyka; Hualiang Jiang; Cheng Luo; Tomasz Kordula; Sheldon Milstien; Sarah Spiegel Journal: Nature Date: 2010-06-24 Impact factor: 49.962
Authors: Fan Jiang; Mingjie Xia; Yanan Zhang; Jie Chang; Jiang Cao; Zhongkai Zhang; Zhanyang Qian; Lei Yang Journal: Front Immunol Date: 2022-09-26 Impact factor: 8.786