Exosomal USP13 derived from microvascular endothelial cells regulates immune microenvironment and improves functional recovery after spinal cord injury by stabilizing IκBα

Xuhui Ge; Zheng Zhou; Siting Yang; Wu Ye; Zhuanghui Wang; Jiaxing Wang; Chenyu Xiao; Min Cui; Jiawen Zhou; Yufeng Zhu; Rixiao Wang; Yu Gao; Haofan Wang; Pengyu Tang; Xuhui Zhou; Ce Wang; Weihua Cai

doi:10.1186/s13578-023-01011-9

Exosomal USP13 derived from microvascular endothelial cells regulates immune microenvironment and improves functional recovery after spinal cord injury by stabilizing IκBα

Cell Biosci. 2023 Mar 13;13(1):55. doi: 10.1186/s13578-023-01011-9.

Authors

Xuhui Ge^#¹, Zheng Zhou^#², Siting Yang^#³, Wu Ye¹, Zhuanghui Wang¹, Jiaxing Wang¹, Chenyu Xiao⁴, Min Cui⁴, Jiawen Zhou⁵, Yufeng Zhu¹, Rixiao Wang¹, Yu Gao¹, Haofan Wang¹, Pengyu Tang¹, Xuhui Zhou⁶, Ce Wang⁷, Weihua Cai⁸

Affiliations

¹ Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, Jiangsu, China.
² Department of Emergency Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, Jiangsu, China.
³ Department of Anesthesiology and Nursing, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, Jiangsu, China.
⁴ Department of Human Anatomy, Nanjing Medical University, Nanjing, 211166, Jiangsu, China.
⁵ Department of Pharmacology, China Pharmaceutical University, Nanjing, 211198, China.
⁶ Department of Orthopedics, Second Affiliated Hospital of Naval Medical University, Shanghai, 200003, China.
⁷ Department of Orthopedics, Second Affiliated Hospital of Naval Medical University, Shanghai, 200003, China. cowwang_111@163.com.
⁸ Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, Jiangsu, China. caiwhspine@njmu.edu.cn.

^# Contributed equally.

Abstract

Spinal cord injury (SCI) can result in irreversible sensory and motor disability with no effective treatment currently. After SCI, infiltrated macrophages accumulate in epicenter through destructed blood-spinal cord barrier (BSCB). Further, great majority of macrophages are preferentially polarized to M1 phenotype, with only a few transient M2 phenotype. The purpose of this study was to explore roles of vascular endothelial cells in microglia/macrophages polarization and the underlying mechanism. Lipopolysaccharide (LPS) was used to pretreat BV2 microglia and RAW264.7 macrophages followed by administration of conditioned medium from microvascular endothelial cell line bEnd.3 cells (ECM). Analyses were then performed to determine the effects of exosomes on microglia/macrophages polarization and mitochondrial function. The findings demonstrated that administration of ECM shifted microglia/macrophages towards M2 polarization, ameliorated mitochondrial impairment, and reduced reactive oxygen species (ROS) production in vitro. Notably, administration of GW4869, an exosomal secretion inhibitor, significantly reversed these observed benefits. Further results revealed that exosomes derived from bEnd.3 cells (Exos) promote motor rehabilitation and M2 polarization of microglia/macrophages in vivo. Ubiquitin-specific protease 13 (USP13) was shown to be significantly enriched in BV2 microglia treated with Exos. USP13 binds to, deubiquitinates and stabilizes the NF-κB inhibitor alpha (IκBα), thus regulating microglia/macrophages polarization. Administration of the selective IκBα inhibitor betulinic acid (BA) inhibited the beneficial effect of Exos in vivo. These findings uncovered the potential mechanism underlying the communications between vascular endothelial cells and microglia/macrophages after SCI. In addition, this study indicates exosomes might be a promising therapeutic strategy for SCI treatment.

Keywords: Exosomes; Microglia/macrophages polarization; Mitochondria; Spinal cord injury; USP13/ IκBα.

Abstract

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