低剂量脂多糖通过 lncRNA MALAT1/Nrf2 轴调控自噬抑制脊髓损伤诱导的神经元凋亡。
Low-dose lipopolysaccharide inhibits spinal cord injury-induced neuronal apoptosis by regulating autophagy through the lncRNA MALAT1/Nrf2 axis.
机构信息
Orthopedic Surgery, The First People's Hospital of Yunnan Province, Affiliated Hospital of Kunming University of Science and Technology, Kunming, China.
Faculty of Medical Science, Kunming University of Science and Technology, Kunming, China.
出版信息
PeerJ. 2023 Aug 28;11:e15919. doi: 10.7717/peerj.15919. eCollection 2023.
BACKGROUND
Spinal cord injury (SCI) is a neurological disease associated with a high disability rate. Low-dose lipopolysaccharide (LPS) has been reported to activate cross-immune tolerance and alleviate the effects of various traumatic stimuli. The present study aimed to explore the effect of LPS on SCI and the potential molecular mechanism.
METHODS
Male Sprague-Dawley (SD) rats were used to established an SCI model and were intraperitoneally injected with lentivirus particles encoding a MALAT1 small interfering RNA (siRNA) on day 10 prior to SCI and with 0.2 mg/kg LPS 72 h prior to SCI. Basso, Beattie, and Bresnahan (BBB) scoring; HE staining; and TUNEL assay were used to assess neurological function and pathophysiological changes. Western blot and immunohistochemistry (IHC) were used to detect cell autophagy and Nrf2 nuclear translocation. PC12 cells were exposed to oxygen-glucose deprivation/reoxygenation (OGD/R) to establish an SCI model. SCI model cells were pretreated with LPS and transfected with siMALAT1 or MALAT1 overexpression plasmid aimed at knocking down MALAT1 or overexpressing MALAT1. The cell counting kit-8 (CCK-8) assay was used to measure the toxicity of LPS towards PC12 cells. Flow cytometry and immunofluorescence analysis were performed to investigate cell apoptosis and Nrf2 nuclear translocation.
RESULTS
SCI rats preconditioned with low-dose LPS had higher BBB scores, reduced SCI injury, increased MALAT1 expression and activated autophagy and Nrf2 nuclear translocation in the SCI model. In the SCI model, low-dose LPS treatment suppressed the apoptotic ratio of PC12 cells, increased MALAT1 expression, activated autophagy, and promoted Nrf2 nuclear translocation. Silencing MALAT1 exacerbated OGD/R injury and weakened the protective effect of low-dose LPS. Overexpression of MALAT1 inhibits OGD/R-induced apoptosis by inducing autophagy and promoting Nrf2 nuclear translocation. This was also been confirmed in animal experiments, silencing MALAT1 blocked the promotion of Nrf2 by low-dose LPS and the alleviated of SCI apoptosis.
CONCLUSIONS
Low-dose LPS exhibited a protective role on SCI by activating autophagy and suppressing nerve cell apoptosis via the lncRNA MALAT1/Nrf2 axis.
背景
脊髓损伤（SCI）是一种与高致残率相关的神经系统疾病。已有研究报道，低剂量脂多糖（LPS）可激活交叉免疫耐受，减轻各种创伤性刺激的影响。本研究旨在探讨 LPS 对 SCI 的作用及其潜在的分子机制。
方法
采用雄性 Sprague-Dawley（SD）大鼠建立 SCI 模型，在 SCI 前 10 天腹腔注射慢病毒颗粒转染 MALAT1 小干扰 RNA（siRNA），在 SCI 前 72 小时腹腔注射 0.2mg/kg LPS。采用 Basso，Beattie 和 Bresnahan（BBB）评分、苏木精-伊红（HE）染色和 TUNEL 检测评估神经功能和病理生理变化。Western blot 和免疫组织化学（IHC）检测细胞自噬和 Nrf2 核转位。将 PC12 细胞暴露于氧-葡萄糖剥夺/复氧（OGD/R）中建立 SCI 模型。用 LPS 预处理 SCI 模型细胞，并转染 siMALAT1 或 MALAT1 过表达质粒，以敲低 MALAT1 或过表达 MALAT1。采用细胞计数试剂盒-8（CCK-8）检测 LPS 对 PC12 细胞的毒性。流式细胞术和免疫荧光分析检测细胞凋亡和 Nrf2 核转位。
结果
经低剂量 LPS 预处理的 SCI 大鼠 BBB 评分较高，SCI 损伤减轻，SCI 模型中 MALAT1 表达增加，自噬和 Nrf2 核转位激活。在 SCI 模型中，低剂量 LPS 处理可抑制 PC12 细胞的凋亡率，增加 MALAT1 表达，激活自噬，促进 Nrf2 核转位。沉默 MALAT1 加重 OGD/R 损伤，并减弱低剂量 LPS 的保护作用。过表达 MALAT1 通过诱导自噬和促进 Nrf2 核转位抑制 OGD/R 诱导的细胞凋亡。这在动物实验中也得到了证实，沉默 MALAT1 阻断了低剂量 LPS 对 Nrf2 的促进作用，减轻了 SCI 细胞凋亡。
结论
低剂量 LPS 通过激活自噬和抑制神经细胞凋亡，通过 lncRNA MALAT1/Nrf2 轴发挥对 SCI 的保护作用。
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