[脑脊液外泌体亚型的分离与蛋白质组学分析]
[Isolation and proteomics analysis of cerebrospinal fluid exosome subtypes].
作者信息
Chen Xiao-Fei, Liu Wei, Zhang Wen-Jia, Li Yan-Peng, Wang Zhi-Hua, Gao Ming-Xia, Zhang Xiang-Min
机构信息
Department of Chemistry, Fudan University, Shanghai 200438, China.
Shanghai Pudong Hospital, Shanghai 201399, China.
出版信息
Se Pu. 2025 May;43(5):518-528. doi: 10.3724/SP.J.1123.2024.10014.
Exosomes are small extracellular vesicles 30-200 nm in diameter that contain many bioactive macromolecules, including proteins, lipids, and nucleic acids; consequently, they play important roles in many physiological and pathological processes and are classified into various property-dependent subtypes. Research into exosome heterogeneity helps broaden our understanding of the physiological and pathological mechanisms associated with exosomes. Exosomes exist in many human biological fluids, with those derived from cerebrospinal fluid (CSF) regarded as potential disease biomarkers. Despite this, few studies have focused on their proteomics, and little research into CSF-derived exosome subtypes has been reported. Traumatic brain injury (TBI) is a major public health issue characterized by a large number of patients and complex pathological processes. While a comprehensive understanding of the pathophysiological processes that underpin TBI is essential for developing therapeutic interventions, proteomic studies into CSF-derived exosomes in patients with TBI are limited. Herein, we designed a tandem size-exclusion chromatography protocol for isolating and profiling the proteins of CSF-derived exosome subtypes from patients with TBI using nanoscale liquid chromatography and trapped-ion mobility spectrometry time-of-flight mass spectrometry (nanoLC-TIMS-TOF-MS). We first centrifuged the collected CSF to remove cells and cell debris, after which it was concentrated by ultrafiltration to increase the exosome concentration and remove small proteins and peptides. A mini-size exclusion chromatography (Mini-SEC) column was then used to separate the exosomes from large amounts of interfering proteins, after which high performance liquid-SEC (HPL-SEC) was used to further separate exosomes according to size. The entire extracellular-vesicle-subset separation and purification process takes approximately 1 h for a single CSF sample. Four differently sized exosome subtypes were successfully isolated and are referred to as S1, S2, S3, and S4 in order of descending size. The S1 subtype exhibited the highest exosome purity according to the particle-to-protein ratio. Multiple characterization methods, including transmission electron microscopy (TEM), Western blotting (WB), and nanoparticle tracking analysis (NTA), confirmed that the exosome subtypes had been successfully acquired. NanoLC-TIMS-TOF-MS, combined with database searching were then used to characterize the proteins. A total of 739 proteins were identified, of which 79% and 72% matched all proteins and the top 100 proteins in the Vesiclepedia database, respectively. Moreover, gene ontology analysis revealed that the identified proteins are mainly located in extracellular exosomes, and that the isolated exosome subtypes are closely related to multiple biological processes, including cell signaling, coagulation, and immune responses. Hierarchical cluster analysis revealed that samples from the same exosome subset are grouped first. Principal-component and Pearson's correlation coefficient analyses revealed that the proteins expressed in the CSF-derived exosome subtypes are heterogeneous. Interestingly, the proteins identified in the S1 subtype varied greatly between samples, highlighting the potential applicability of this subtype to formulating precise therapeutic regimens for different patients. We also analyzed the highly expressed proteins in the exosome subtypes, which revealed that the enrichment pathway of the S1 subtype involves Vitamin B12 metabolism and the regulation of protein catabolic processes, while the specific enrichment pathway of the S2 subtype includes binding and ligand uptake by scavenger receptors, heme scavenging from plasma, and an inflammatory response. In contrast, the unique enrichment pathway of the S3 subtype contains complementary and coagulation cascades and acute-phase responses, while that of the S4 subtype includes post-translational protein phosphorylation. Furthermore, STRING-based protein-association analysis predicted multiple interactions among proteins in the various exosome subtypes. In conclusion, the developed tandem size-exclusion chromatography method was used to isolate cerebrospinal fluid exosome subtypes. This study enriches knowledge regarding cerebrospinal fluid exosomes in patients with TBI based on proteomics.
外泌体是直径为30 - 200 nm的小型细胞外囊泡,包含许多生物活性大分子,包括蛋白质、脂质和核酸;因此,它们在许多生理和病理过程中发挥重要作用,并被分为各种依赖特性的亚型。对外泌体异质性的研究有助于拓宽我们对与外泌体相关的生理和病理机制的理解。外泌体存在于许多人体生物流体中,其中源自脑脊液(CSF)的外泌体被视为潜在的疾病生物标志物。尽管如此,很少有研究关注其蛋白质组学,关于CSF衍生外泌体亚型的研究报道也很少。创伤性脑损伤(TBI)是一个重大的公共卫生问题,其特点是患者数量众多且病理过程复杂。虽然全面了解支撑TBI的病理生理过程对于开发治疗干预措施至关重要,但对TBI患者CSF衍生外泌体的蛋白质组学研究有限。在此,我们设计了一种串联尺寸排阻色谱方案,使用纳米级液相色谱和阱式离子淌度质谱飞行时间质谱(nanoLC - TIMS - TOF - MS)从TBI患者中分离和分析CSF衍生外泌体亚型的蛋白质。我们首先对收集的CSF进行离心以去除细胞和细胞碎片,然后通过超滤进行浓缩以增加外泌体浓度并去除小蛋白质和肽。然后使用微型尺寸排阻色谱(Mini - SEC)柱从大量干扰蛋白中分离外泌体,之后使用高效液相SEC(HPL - SEC)根据大小进一步分离外泌体。单个CSF样品的整个细胞外囊泡亚群分离和纯化过程大约需要1小时。成功分离出四种不同大小的外泌体亚型,按照大小降序依次称为S1、S2、S3和S4。根据颗粒与蛋白质的比例,S1亚型表现出最高的外泌体纯度。多种表征方法,包括透射电子显微镜(TEM)、蛋白质印迹(WB)和纳米颗粒跟踪分析(NTA),证实已成功获得外泌体亚型。然后使用NanoLC - TIMS - TOF - MS结合数据库搜索来表征蛋白质。总共鉴定出739种蛋白质,其中分别有79%和72%与Vesiclepedia数据库中的所有蛋白质和前100种蛋白质匹配。此外,基因本体分析表明,鉴定出的蛋白质主要位于细胞外囊泡中,并且分离出的外泌体亚型与多种生物过程密切相关,包括细胞信号传导、凝血和免疫反应。层次聚类分析表明,来自同一种外泌体亚群的样品首先聚类在一起。主成分分析和皮尔逊相关系数分析表明,CSF衍生外泌体亚型中表达的蛋白质是异质的。有趣的是,在S1亚型中鉴定出的蛋白质在不同样品之间差异很大,突出了该亚型在为不同患者制定精确治疗方案方面的潜在适用性。我们还分析了外泌体亚型中高表达的蛋白质,结果表明S1亚型的富集途径涉及维生素B12代谢和蛋白质分解代谢过程的调节,而S2亚型的特定富集途径包括清道夫受体的结合和配体摄取、从血浆中清除血红素以及炎症反应。相比之下,S3亚型的独特富集途径包含补体和凝血级联反应以及急性期反应,而S4亚型的富集途径包括蛋白质翻译后磷酸化。此外,基于STRING的蛋白质关联分析预测了各种外泌体亚型中蛋白质之间的多种相互作用。总之,所开发的串联尺寸排阻色谱方法用于分离脑脊液外泌体亚型。本研究基于蛋白质组学丰富了关于TBI患者脑脊液外泌体的知识。