Chondrocytes differentiation and immune cells interactions of Endplate Cells in Human Intervertebral Disc Degeneration

We performed the single-cell RNA-sequencing analysis (scRNA-seq) of the cells focusing on degenerative human endplates. By unsupervised clustering of the 8,534 single-cell based on the gene expression, we identified nine distinct cell types. We employed Gene ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways analysis, and the single-cell regulatory network inference and clustering (SCENIC) to determine the enriched pathways and transcriptional activities across seven chondrocyte subpopulations. Furthermore, two cell fates of chondrocyte differentiation were found by trajectory analysis, one was enriched in inflammation-related genes, and the other was related to extracellular matrix (ECM). Additionally, the intercellular interactions of MAs and chondrocytes, T/NK cells and chondrocytes were examined by ligand-receptor pairs analysis, showing the important regulative function of FN1 from MAs and CD74 from T/NK cells during endplate degeneration. Overall design: Cartilage endplate tissue was obtained from two patients diagnosed with modic changes at the levels of L3-L4 or L4-L5, who were undergoing surgery for disc herniation, and analyzed using scRNA-seq. The patients were a 58-year-old female and a 66-year-old male, respectively. All participants included were confirmed with MRI images before surgery.

本研究针对退行性人终板细胞开展了单细胞RNA测序（single-cell RNA-sequencing, scRNA-seq）分析。基于基因表达谱对8534个单细胞进行无监督聚类后，我们共鉴定出9种不同的细胞类型。我们采用基因本体论（Gene Ontology, GO）分析、京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes, KEGG）通路分析，以及单细胞调控网络推断与聚类（single-cell regulatory network inference and clustering, SCENIC），对7个软骨细胞亚群的富集通路与转录活性进行了解析。此外，通过轨迹分析我们鉴定出软骨细胞分化的两种细胞命运：其中一种富集炎症相关基因，另一种则与细胞外基质（extracellular matrix, ECM）密切相关。本研究还通过配体-受体对分析，探究了MAs与软骨细胞、T/NK细胞与软骨细胞之间的细胞间相互作用，结果显示MAs来源的FN1以及T/NK细胞来源的CD74在终板退行性变过程中发挥了关键调控功能。【实验设计】本研究从2名因椎间盘突出症接受手术治疗的患者处获取软骨终板组织，两名患者分别在L3-L4或L4-L5节段存在椎体终板Modic改变；其中1例为58岁女性，另1例为66岁男性。所有入组受试者术前均经磁共振成像（Magnetic Resonance Imaging, MRI）检查确认病情。