长链非编码RNA Mirt2靶向CCR1通路缓解创伤性脑损伤后的继发性神经炎症

Alleviation of Secondary Neuroinflammation after Traumatic Brain Injury by Long‑Chain Non‑Coding RNA Mirt2 via Targeting the CCR1 Pathway

摘要: 目的：长链非编码RNA (lncRNA)的表达失调在创伤性脑损伤(TBI)引发的继发性病理损害与组织修复过程中发挥关键作用。本研究旨在探讨lncRNA心肌梗死相关转录因子2 (Mirt2)在TBI后的生物学功能，并阐明其调控小胶质细胞介导的神经炎症的潜在分子机制。方法：通过构建小鼠控制性皮质撞击(CCI)体内TBI模型及脂多糖(LPS)诱导的原代小胶质细胞体外炎症模型，系统评估Mirt2对神经炎症的调控作用。采用转录组测序(RNA-Seq)筛选下游靶基因，并通过蛋白质印迹法(Western Blot)与实时荧光定量PCR (RT-qPCR)对关键信号通路进行验证。结果：体内与体外实验均证实，TBI或LPS刺激可显著下调Mirt2的转录表达。RNA-Seq结合定量分析表明，敲低Mirt2可打破小胶质细胞的转录稳态，导致趋化因子受体CCR1及其衔接蛋白TPR1异常上调，进而激活下游ERK1/2信号通路，显著增加促炎细胞因子IL-1β和IL-6的释放。结论：LncRNA Mirt2是TBI后小胶质细胞介导神经炎症的关键负调控因子。Mirt2下调可通过激活CCR1/TPR1/ERK信号通路促进促炎因子释放；上调Mirt2可抑制小胶质细胞过度活化，本研究完善了TBI继发神经炎症的分子调控网络，为相关基础机制探究提供实验支撑。

Abstract: Objective: Dysregulation of long non-coding RNAs (lncRNAs) plays a vital role in secondary pathological injury and tissue repair after traumatic brain injury (TBI). This study aimed to investigate the biological function of lncRNA myocardial infarction-associated transcript 2 (Mirt2) following TBI, and to elucidate its potential molecular mechanism in regulating microglia-mediated neuroinflammation. Methods: A controlled cortical impact (CCI)-induced TBI mouse model in vivo and a lipopolysaccharide (LPS)-stimulated primary microglial inflammatory model in vitro were established to systematically evaluate the regulatory effect of Mirt2 on neuroinflammation. RNA sequencing (RNA-Seq) was performed to screen downstream target genes, and Western Blotting and real-time quantitative PCR (RT-qPCR) were used to verify the key signaling pathways. Results: Both in vivo and in vitro experiments verified that TBI or LPS stimulation markedly downregulated the transcriptional level of Mirt2. Combined RNA-Seq and quantitative analyses revealed that Mirt2 knockdown disrupted the transcriptional homeostasis of microglia, abnormally upregulated chemokine receptor CCR1 and its adaptor protein TPR1, further activated the downstream ERK1/2 signaling pathway, and drastically boosted the secretion of pro-inflammatory cytokines IL-1β and IL-6. Conclusion: LncRNA Mirt2 acts as a crucial negative regulator of microglia-mediated neuroinflammation post TBI. Downregulation of Mirt2 promotes the release of pro-inflammatory cytokines via activating the CCR1/TPR1/ERK signaling axis, while upregulating Mirt2 can suppress excessive microglial activation. This study enriches the molecular regulatory network of secondary neuroinflammation after TBI and provides experimental evidence for relevant basic mechanistic research.