Liu Yu, Wu Weiwei, Fu Di
Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha 410008.
Department of Anesthesiology, Second Xiangya Hospital, Central South University, Changsha 410011.
Zhong Nan Da Xue Xue Bao Yi Xue Ban. 2024 Nov 28;49(11):1777-1789. doi: 10.11817/j.issn.1672-7347.2024.240045.
Sepsis-associated encephalopathy (SAE) is a common complication of sepsis, which can lead to long-term cognitive impairment and anxiety in patients, and may even contribute to mortality in septic individuals. There is substantial individual variability in the incidence and severity and susceptibility of SAE, but the mechanisms regulating susceptibility remain unclear. Previous studies have shown that hippocampal damage is directly associated with cognitive and emotional disturbances in SAE. This study aims to explore the impact of hippocampal differentially expressed genes on SAE susceptibility in a mouse model.
Male specific pathogen-free (SPF)-grade C57BL/6 mice (6-8 weeks old) were randomly divided into a saline control group (Con group) and an SAE model group. SAE was induced by intraperitoneal injection of 10 mg/kg lipopolysaccharide (LPS), while control mice received an equivalent volume of saline. Cognitive and anxiety-like behaviors were assessed using the open field test (OFT), novel object recognition (NOR), and Y-maze test. Based on mean±standard deviation of behavioral results from the Con group, SAE mice were further classified into high-sensitivity (HS) and low-sensitivity (LS) subgroups. Immunohistochemistry was performed to detect the expression of immediate early gene c-Fos and neuronal marker neuronal nuclei (NeuN). Nissl staining was used to assess neuronal injury in the dentate gyrus (DG), cornu ammonis 1 (CA1), and cornu ammonis 3 (CA3) regions of the hippocampus. RNA sequencing (RNA-seq) was conducted on hippocampal tissues from HS and LS mice to identify differentially expressed genes, followed by pathway enrichment analysis.
No significant behavioral susceptibility differences were observed between the overall SAE group and controls. However, HS mice showed severer cognitive deficits and anxiety-like behavior compared to LS mice. Immunohistochemistry revealed significantly higher expression of c-Fos in the hippocampus of LS mice (<0.05), while Nissl and NeuN staining revealed milder neuronal damage in the hippocampus of LS mice than that of HS mice (both <0.05). RNA-seq analysis identified 130 upregulated and 142 downregulated DEGs in LS and HS mice, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that upregulated genes in LS mice were primarily involved in pluripotency regulation, cyclic adenosine monophosphate (cAMP) signaling, and Wnt signaling pathways, in contrast, the downregulated genes were mainly related to cell adhesion, neuroactive ligand-receptor interaction, and calcium signaling pathways.
Differential gene expression in the hippocampus may contribute to individual susceptibility to cognitive and emotional dysfunction in SAE, suggesting potential genetic targets for individualized intervention.
脓毒症相关性脑病（SAE）是脓毒症常见的并发症，可导致患者长期认知障碍和焦虑，甚至可能增加脓毒症患者的死亡率。SAE的发病率、严重程度和易感性存在显著个体差异，但调节易感性的机制仍不清楚。既往研究表明，海马损伤与SAE中的认知和情绪障碍直接相关。本研究旨在探讨海马差异表达基因对小鼠模型中SAE易感性的影响。
将雄性无特定病原体（SPF）级C57BL/6小鼠（6-8周龄）随机分为生理盐水对照组（Con组）和SAE模型组。通过腹腔注射10 mg/kg脂多糖（LPS）诱导SAE，而对照小鼠接受等量生理盐水。使用旷场试验（OFT）、新物体识别试验（NOR）和Y迷宫试验评估认知和焦虑样行为。根据Con组行为结果的平均值±标准差，将SAE小鼠进一步分为高敏（HS）和低敏（LS）亚组。进行免疫组织化学检测即刻早期基因c-Fos和神经元标志物神经元核（NeuN）的表达。采用尼氏染色评估海马齿状回（DG）、海马1区（CA1）和海马3区（CA3）的神经元损伤。对HS和LS小鼠的海马组织进行RNA测序（RNA-seq）以鉴定差异表达基因，随后进行通路富集分析。
SAE组与对照组之间未观察到明显的行为易感性差异。然而，与LS小鼠相比，HS小鼠表现出更严重的认知缺陷和焦虑样行为。免疫组织化学显示，LS小鼠海马中c-Fos的表达显著更高（<0.05），而尼氏染色和NeuN染色显示，LS小鼠海马中的神经元损伤比HS小鼠更轻（均<0.05）。RNA-seq分析分别在LS和HS小鼠中鉴定出130个上调和142个下调的差异表达基因（DEG）。京都基因与基因组百科全书（KEGG）通路分析显示，LS小鼠中上调的基因主要参与多能性调控、环磷酸腺苷（cAMP）信号通路和Wnt信号通路，相反，下调的基因主要与细胞黏附、神经活性配体-受体相互作用和钙信号通路相关。
海马中的差异基因表达可能导致个体对SAE中认知和情绪功能障碍的易感性，提示个性化干预的潜在遗传靶点。
