TREM2 Impedes Recovery After Spinal Cord Injury by Regulating Microglial Lysosomal Membrane Permeabilization-Mediated Autophagy

Abstract

Microglia, considered as the main immune responder, play an important role in regulating neuroinflammation in central nervous system (CNS) disorders. Our previous work found that TREM2 is highly expressed in microglia and is related to their functional state. However, the specific role of TREM2 in spinal cord injury has not yet been explored. To further investigate the potential mechanism of TREM2, we performed single-cell sequencing on wild-type (Wt) and Trem2^−/− mice before and after spinal cord injury. Compared to Wt mice, the lysosome, autophagy and membrane-related pathways are more strongly activated in Trem2^−/− mice, suggesting that TREM2 may exert its effects by influencing lysosomal membranes and autophagy. Mechanistically, we demonstrated that the knockout of Trem2 can reduce the nuclear translocation of TFEB by decreasing the phosphorylation of Syk. Furthermore, we validated that in vitro and in vivo silencing Trem2 can promote autophagy by repairing lysosomal membrane permeabilization. Through immunofluorescence, 3D gait analysis, motor evoked potential experiments, H&E staining and Masson staining, we demonstrated that the increased level of autophagy can rescue more microglia in vivo and promote both functional and histological recovery of spinal cord injury. Collectively, these results not only suggest that microglial lysosomal autophagy is regulated in a TREM2-dependent LMP manner, but also, more importantly, they provide a promising clinical translation strategy based on gene therapy for lysosome-related central nervous system disorders.

Keywords

autophagy / lysosomal membrane permeabilization / microglia / spinal cord injury / TREM2

References

[1] A. Alizadeh, S. M. Dyck, and S. Karimi-Abdolrezaee, “Traumatic Spinal Cord Injury: An Overview of Pathophysiology, Models and Acute Injury Mechanisms,” Frontiers in Neurology 10 (2019): 282, https://doi.org/10.3389/fneur.2019.00282.

[2] C. S. Ahuja, J. R. Wilson, S. Nori, et al., “Traumatic Spinal Cord Injury,” Nature Reviews Disease Primers 3 (2017): 17018, https://doi.org/10.1038/nrdp.2017.18.

[3] E. J. Bradbury and E. R. Burnside, “Moving Beyond the Glial Scar for Spinal Cord Repair,” Nature Communications 10, no. 1 (2019): 3879, https://doi.org/10.1038/s41467-019-11707-7.

[4] F. H. Brennan, Y. Li, C. Wang, et al., “Microglia Coordinate Cellular Interactions During Spinal Cord Repair in Mice,” Nature Communications 13, no. 1 (2022): 4096, https://doi.org/10.1038/s41467-022-31797-0.

[5] A. Deczkowska, A. Weiner, and I. Amit, “The Physiology, Pathology, and Potential Therapeutic Applications of the TREM2 Signaling Pathway,” Cell 181, no. 6 (2020): 1207-1217, https://doi.org/10.1016/j.cell.2020.05.003.

[6] V. E. B. Hipolito, E. Ospina-Escobar, and R. J. Botelho, “Lysosome Remodelling and Adaptation During Phagocyte Activation,” Cellular Microbiology 20, no. 4 (2018): e12824, https://doi.org/10.1111/cmi.12824.

[7] L. M. Milich, J. S. Choi, C. Ryan, et al., “Single-Cell Analysis of the Cellular Heterogeneity and Interactions in the Injured Mouse Spinal Cord,” Journal of Experimental Medicine 218, no. 8 (2021): e20210040, https://doi.org/10.1084/jem.20210040.

[8] Y. Feng, H. Fu, X. Zhang, S. Liu, and X. Wei, “Lysosome Toxicities Induced by Nanoparticle Exposure and Related Mechanisms,” Ecotoxicology and Environmental Safety 286 (2024): 117215, https://doi.org/10.1016/j.ecoenv.2024.117215.

[9] F. Wang, R. Gomez-Sintes, and P. Boya, “Lysosomal Membrane Permeabilization and Cell Death,” Traffic 19, no. 12 (2018): 918-931, https://doi.org/10.1111/tra.12613.

[10] L. Xiang, J. Lou, J. Zhao, et al., “Underlying Mechanism of Lysosomal Membrane Permeabilization in CNS Injury: A Literature Review,” Molecular Neurobiology 62 (2024): 626-642, https://doi.org/10.1007/s12035-024-04290-6.

[11] H. Zhang, Y. Chen, F. Li, et al., “Elamipretide Alleviates Pyroptosis in Traumatically Injured Spinal Cord by Inhibiting cPLA2-Induced Lysosomal Membrane Permeabilization,” Journal of Neuroinflammation 20, no. 1 (2023): 6, https://doi.org/10.1186/s12974-023-02690-4.

[12] T. Tanaka, B. M. Warner, D. G. Michael, et al., “LAMP3 Inhibits Autophagy and Contributes to Cell Death by Lysosomal Membrane Permeabilization,” Autophagy 18, no. 7 (2022): 1629-1647, https://doi.org/10.1080/15548627.2021.1995150.

[13] N. Meyer, L. Henkel, B. Linder, et al., “Autophagy Activation, Lipotoxicity and Lysosomal Membrane Permeabilization Synergize to Promote Pimozide- and Loperamide-Induced Glioma Cell Death,” Autophagy 17, no. 11 (2021): 3424-3443, https://doi.org/10.1080/15548627.2021.1874208.

[14] Y. Zuo, J. Ye, W. Cai, et al., “Controlled Delivery of a Neurotransmitter-Agonist Conjugate for Functional Recovery After Severe Spinal Cord Injury,” Nature Nanotechnology 18, no. 10 (2023): 1230-1240, https://doi.org/10.1038/s41565-023-01416-0.

[15] J. Lou, X. Wang, H. Zhang, et al., “Inhibition of PLA2G4E/cPLA2 Promotes Survival of Random Skin Flaps by Alleviating Lysosomal Membrane Permeabilization-Induced Necroptosis,” Autophagy 18, no. 8 (2022): 1841-1863, https://doi.org/10.1080/15548627.2021.2002109.

[16] H. Gao, J. Di, B. H. Clausen, et al., “Distinct Myeloid Population Phenotypes Dependent on TREM2 Expression Levels Shape the Pathology of Traumatic Versus Demyelinating CNS Disorders,” Cell Reports 42, no. 6 (2023): 112629, https://doi.org/10.1016/j.celrep.2023.112629.

[17] C. Li, Z. Wu, L. Zhou, et al., “Temporal and Spatial Cellular and Molecular Pathological Alterations With Single-Cell Resolution in the Adult Spinal Cord After Injury,” Signal Transduction and Targeted Therapy 7, no. 1 (2022): 65, https://doi.org/10.1038/s41392-022-00885-4.

[18] I. Arganda-Carreras, R. Fernandez-Gonzalez, A. Munoz-Barrutia, and C. Ortiz-De-Solorzano, “3D Reconstruction of Histological Sections: Application to Mammary Gland Tissue,” Microscopy Research and Technique 73, no. 11 (2010): 1019-1029, https://doi.org/10.1002/jemt.20829.

[19] Y. Xu, Y. Geng, H. Wang, et al., “Cyclic Helix B Peptide Alleviates Proinflammatory Cell Death and Improves Functional Recovery After Traumatic Spinal Cord Injury,” Redox Biology 64 (2023): 102767, https://doi.org/10.1016/j.redox.2023.102767.

[20] S. Taguwa, H. Kambara, N. Fujita, et al., “Dysfunction of Autophagy Participates in Vacuole Formation and Cell Death in Cells Replicating Hepatitis C Virus,” Journal of Virology 85, no. 24 (2011): 13185-13194, https://doi.org/10.1128/JVI.06099-11.

[21] C. Marx, J. M. Held, B. W. Gibson, and C. C. Benz, “ErbB2 Trafficking and Degradation Associated With K48 and K63 Polyubiquitination,” Cancer Research 70, no. 9 (2010): 3709-3717, https://doi.org/10.1158/0008-5472.CAN-09-3768.

[22] X. Sun, H. Liu, Z. Tan, et al., “Remodeling Microenvironment for Endogenous Repair Through Precise Modulation of Chondroitin Sulfate Proteoglycans Following Spinal Cord Injury,” Small 19, no. 6 (2023): e2205012, https://doi.org/10.1002/smll.202205012.

[23] S. J. Zhao, F. Q. Kong, W. Cai, et al., “GIT1 Contributes to Autophagy in Osteoclast Through Disruption of the Binding of Beclin1 and Bcl2 Under Starvation Condition,” Cell Death & Disease 9, no. 12 (2018): 1195, https://doi.org/10.1038/s41419-018-1256-8.

[24] M. Kosic, K. Arsikin-Csordas, V. Paunovic, et al., “Synergistic Anticancer Action of Lysosomal Membrane Permeabilization and Glycolysis Inhibition,” Journal of Biological Chemistry 291, no. 44 (2016): 22936-22948, https://doi.org/10.1074/jbc.M116.752113.

[25] C. Zhai, Z. Wang, J. Cai, et al., “Repeated Trans-Spinal Magnetic Stimulation Promotes Microglial Phagocytosis of Myelin Debris After Spinal Cord Injury Through LRP-1,” Experimental Neurology 379 (2024): 114844, https://doi.org/10.1016/j.expneurol.2024.114844.

[26] W. Huang, D. Wu, C. Cai, et al., “Inhibition of MST1 Ameliorates Neuronal Apoptosis via GSK3β/β-TrCP/NRF2 Pathway in Spinal Cord Injury Accompanied by Diabetes,” Redox Biology 71 (2024): 103104, https://doi.org/10.1016/j.redox.2024.103104.

[27] L. M. Milich, C. B. Ryan, and J. K. Lee, “The Origin, Fate, and Contribution of Macrophages to Spinal Cord Injury Pathology,” Acta Neuropathologica 137, no. 5 (2019): 785-797, https://doi.org/10.1007/s00401-019-01992-3.

[28] Y. Geng, J. Lou, J. Wu, et al., “NEMO-Binding Domain/IKKγ Inhibitory Peptide Alleviates Neuronal Pyroptosis in Spinal Cord Injury by Inhibiting ASMase-Induced Lysosome Membrane Permeabilization,” Advances in Science 11, no. 40 (2024): e2405759, https://doi.org/10.1002/advs.202405759.

[29] Y. Li, X. He, R. Kawaguchi, et al., “Microglia-Organized Scar-Free Spinal Cord Repair in Neonatal Mice,” Nature 587, no. 7835 (2020): 613-618, https://doi.org/10.1038/s41586-020-2795-6.

[30] C. Settembre, C. Di Malta, V. A. Polito, et al., “TFEB Links Autophagy to Lysosomal Biogenesis,” Science 332, no. 6036 (2011): 1429-1433, https://doi.org/10.1126/science.1204592.

[31] P. Saftig and J. Klumperman, “Lysosome Biogenesis and Lysosomal Membrane Proteins: Trafficking Meets Function,” Nature Reviews Molecular Cell Biology 10, no. 9 (2009): 623-635, https://doi.org/10.1038/nrm2745.

[32] D. Davalos, J. Grutzendler, G. Yang, et al., “ATP Mediates Rapid Microglial Response to Local Brain Injury In Vivo,” Nature Neuroscience 8, no. 6 (2005): 752-758, https://doi.org/10.1038/nn1472.

[33] I. G. Ju, S. Lee, H. Im, J. H. Kim, H. Eo, and M. S. Oh, “Artemisiae Iwayomogii Herba Mitigates Excessive Neuroinflammation and Aβ Accumulation by Regulating the Pro-Inflammatory Response and Autophagy-Lysosomal Pathway in Microglia in 5xFAD Mouse Model of Alzheimer's Disease,” Geroscience 47, no. 2 (2025): 1957-1972, https://doi.org/10.1007/s11357-024-01388-6.

[34] M. Colonna, “The Biology of TREM Receptors,” Nature Reviews Immunology 23, no. 9 (2023): 580-594, https://doi.org/10.1038/s41577-023-00837-1.

[35] K. Schlepckow, E. Morenas-Rodriguez, S. Hong, and C. Haass, “Stimulation of TREM2 With Agonistic Antibodies-An Emerging Therapeutic Option for Alzheimer's Disease,” Lancet Neurology 22, no. 11 (2023): 1048-1060, https://doi.org/10.1016/S1474-4422(23)00247-8.

[36] Z. Yin, S. Herron, S. Silveira, et al., “Identification of a Protective Microglial State Mediated by miR-155 and Interferon-γ Signaling in a Mouse Model of Alzheimer's Disease,” Nature Neuroscience 26, no. 7 (2023): 1196-1207, https://doi.org/10.1038/s41593-023-01355-y.

[37] A. P. Tsai, C. Dong, P. B. Lin, et al., “Genetic Variants of Phospholipase C-γ2 Alter the Phenotype and Function of Microglia and Confer Differential Risk for Alzheimer's Disease,” Immunity 56, no. 9 (2023): 2121-2136, https://doi.org/10.1016/j.immuni.2023.08.008.

[38] J. Rueda-Carrasco, D. Sokolova, S. E. Lee, et al., “Microglia-Synapse Engulfment via PtdSer-TREM2 Ameliorates Neuronal Hyperactivity in Alzheimer's Disease Models,” EMBO Journal 42, no. 19 (2023): e113246, https://doi.org/10.15252/embj.2022113246.

[39] S. Wang, R. Sudan, V. Peng, et al., “TREM2 Drives Microglia Response to Amyloid-β via SYK-Dependent and -Independent Pathways,” Cell 185, no. 22 (2022): 4153-4169, https://doi.org/10.1016/j.cell.2022.09.033.

[40] M. Cella, C. Buonsanti, C. Strader, T. Kondo, A. Salmaggi, and M. Colonna, “Impaired Differentiation of Osteoclasts in TREM-2-Deficient Individuals,” Journal of Experimental Medicine 198, no. 4 (2003): 645-651, https://doi.org/10.1084/jem.20022220.

[41] J. Paloneva, J. Mandelin, A. Kiialainen, et al., “DAP12/TREM2 Deficiency Results in Impaired Osteoclast Differentiation and Osteoporotic Features,” Journal of Experimental Medicine 198, no. 4 (2003): 669-675, https://doi.org/10.1084/jem.20030027.

[42] Z. Qi, W. Yang, B. Xue, et al., “ROS-Mediated Lysosomal Membrane Permeabilization and Autophagy Inhibition Regulate Bleomycin-Induced Cellular Senescence,” Autophagy 20, no. 9 (2024): 2000-2016, https://doi.org/10.1080/15548627.2024.2353548.

[43] Y. Chen, H. Zhang, L. Jiang, et al., “DADLE Promotes Motor Function Recovery by Inhibiting Cytosolic Phospholipase A(2) Mediated Lysosomal Membrane Permeabilization After Spinal Cord Injury,” British Journal of Pharmacology 181, no. 5 (2024): 712-734, https://doi.org/10.1111/bph.16255.

[44] Y. Li, J. W. Jones, H. Choi, et al., “cPLA2 Activation Contributes to Lysosomal Defects Leading to Impairment of Autophagy After Spinal Cord Injury,” Cell Death & Disease 10, no. 7 (2019): 531, https://doi.org/10.1038/s41419-019-1764-1.

[45] W. Li, J. Lin, Z. Shi, et al., “Clomiphene Citrate Induces Nuclear Translocation of the TFEB Transcription Factor and Triggers Apoptosis by Enhancing Lysosomal Membrane Permeabilization,” Biochemical Pharmacology 162 (2019): 191-201, https://doi.org/10.1016/j.bcp.2018.11.016.

[46] L. Yang, X. Gao, D. Tian, et al., “Resolvin D2 Activates Anti-Inflammatory Microglia via Restoring Autophagy Flux and Alleviate Neuropathic Pain Following Spinal Cord Injury in Rats,” Experimental Neurology 370 (2023): 114573, https://doi.org/10.1016/j.expneurol.2023.114573.

RIGHTS & PERMISSIONS

2025 The Author(s). Cell Proliferation published by Beijing Institute for Stem Cell and Regenerative Medicine and John Wiley & Sons Ltd.