Wang Jingyu, Xu Lintao, Peng Deqing, Zhu Yongjian, Gu Zhaowen, Yao Ying, Li Heyangzi, Cao Xi, Fu Chun-Yan, Zheng Mingzhi, Song Xinghui, Ding Yueming, Shen Yueliang, Zhong Jinjie, Chen Ying-Ying, Hu Jue, Wang Lin-Lin
Department of Neurosurgery, Second Affiliated Hospital of Zhejiang University School of Medicine, Key Laboratory of Precise Treatment and Clinical Translational Research of Neurological Diseases, Hangzhou, 310009, China.
Department of Neurosurgery, Center for Rehabilitation Medicine, Zhejiang Provincial People's Hospital (Affiliated People's Hospital Hangzhou Medical College), Hangzhou, Zhejiang, China.
Inflamm Regen. 2023 Feb 13;43(1):12. doi: 10.1186/s41232-023-00263-9.
Spinal cord injury (SCI) causes nearly all patients to suffer from protracted disabilities. An emerging therapeutic strategy involving the recruitment of endogenous neural stem cells (NSCs) has been developed. However, endogenous NSCs in the adult spinal cord differentiate into mostly astrocytes after traumatic injury, forming glial scars, which is a major cause of regeneration failure in SCI. Thus, understanding which factors drive the activation and differentiation of endogenous NSCs after SCI is critical for developing therapeutic drugs.
The infiltration, state, and location of CD8 T cells in spinal cord after traumatic injury were analyzed by flow cytometry and immunofluorescence (IF) staining. The Basso Mouse Scale (BMS) scores and rotarod testing were used for motor behavioral analysis. NSCs were co-cultured with CD8 T cells. EdU assay was used to detect proliferative cells. Western blotting was used to analyze the expression levels of STAT1, p-STAT1, and p27. ChIP-seq and ChIP-qRT-PCR analyses were used to detect the downstream of STAT1. Nestin-CreERT2::Ai9 transgenic mice were used to genetic lineage tracing of Nestin NSCs after SCI in vivo.
A prolonged increase of activated CD8 T cells occurs in the injured spinal cords. The behavioral analysis demonstrated that the administration of an anti-CD8 antibody promotes the recovery of locomotor function. Then, we discovered that CD8 T cells suppressed the proliferation of NSCs and promoted the differentiation of NSCs into astrocytes by the IFN-γ-STAT1 pathway in vitro. ChIP-seq and ChIP-qRT-PCR analysis revealed that STAT1 could directly bind to the promoters of astrocyte marker genes GFAP and Aldh1l1. Genetic lineage tracing of Nestin NSCs demonstrated that most NSCs differentiated into astrocytes following SCI. Depleting CD8 T cells reduced the differentiation of NSCs into astrocytes and instead promoted the differentiation of NSCs into oligodendrocytes.
In conclusion, CD8 T cells suppressed the proliferation of NSCs and promoted the differentiation of NSCs into astrocytes by the IFN-γ-STAT1-GFAP/Aldhl1l axis. Our study identifies INF-γ as a critical mediator of CD8 T-cell-NSC cross talk and a potential node for therapeutic intervention in SCI.
脊髓损伤（SCI）几乎使所有患者都遭受长期残疾之苦。一种涉及募集内源性神经干细胞（NSCs）的新兴治疗策略已被开发出来。然而，成年脊髓中的内源性神经干细胞在创伤性损伤后大多分化为星形胶质细胞，形成胶质瘢痕，这是脊髓损伤再生失败的主要原因。因此，了解脊髓损伤后哪些因素驱动内源性神经干细胞的激活和分化对于开发治疗药物至关重要。
通过流式细胞术和免疫荧光（IF）染色分析创伤性损伤后脊髓中CD8 T细胞的浸润、状态和位置。使用Basso小鼠评分（BMS）和转棒试验进行运动行为分析。将神经干细胞与CD8 T细胞共培养。使用EdU检测法检测增殖细胞。使用蛋白质免疫印迹法分析STAT1、p-STAT1和p27的表达水平。使用ChIP-seq和ChIP-qRT-PCR分析来检测STAT1的下游。使用Nestin-CreERT2::Ai9转基因小鼠对脊髓损伤后体内Nestin神经干细胞进行遗传谱系追踪。
在损伤的脊髓中，活化的CD8 T细胞出现持续增加。行为分析表明，给予抗CD8抗体可促进运动功能的恢复。然后，我们发现CD8 T细胞在体外通过IFN-γ-STAT1途径抑制神经干细胞的增殖并促进神经干细胞向星形胶质细胞的分化。ChIP-seq和ChIP-qRT-PCR分析表明，STAT1可直接结合星形胶质细胞标志物基因GFAP和Aldh1l1的启动子。对Nestin神经干细胞的遗传谱系追踪表明，大多数神经干细胞在脊髓损伤后分化为星形胶质细胞。耗尽CD8 T细胞可减少神经干细胞向星形胶质细胞的分化，转而促进神经干细胞向少突胶质细胞的分化。
总之，CD8 T细胞通过IFN-γ-STAT1-GFAP/Aldhl1l轴抑制神经干细胞的增殖并促进神经干细胞向星形胶质细胞的分化。我们的研究确定INF-γ是CD8 T细胞与神经干细胞相互作用的关键介质，也是脊髓损伤治疗干预的潜在靶点。
