Feng Xiaofei, Li Yongchao, Su Qihang, Tan Jun
School of Medicine, Tongji University, Shanghai, China.
Department of Orthopedics, Shanghai Tenth People's Hospital, Shanghai, China.
Front Mol Biosci. 2022 Mar 14;9:835976. doi: 10.3389/fmolb.2022.835976. eCollection 2022.
Intervertebral disc (IVD) degeneration is a complex multifactorial disease model, which pathogenesis has not been fully defined. There are few studies on the information interaction between nucleus pulposus (NP) cells and cartilage endplate (CEP) cells. Exosomes, as a carrier of information communication between cells, have become a research hotspot recently. The purpose of this study was to explore whether degenerative NP cells-derived exosomes promoted CEP cells apoptosis and aggravated IVD degeneration. The degenerative NP cells model was induced by TNFα. NPC exosomes were isolated from the supernatant of the NP cell culture medium. The viability of NP cells and CEP cells was examined by CCK-8 assays. The exosomes were identified by TEM, NTA, and western blot. Extracellular matrix (ECM) metabolism was measured by cellular immunofluorescence and qRT-PCR. Apoptosis was detected by flow cytometry and TUNEL. X-ray and magnetic resonance imaging (MRI), as well as hematoxylin-eosin (H&E), Safranine O-Green staining was adopted to evaluate IVD degeneration grades. TNFα had a minor impact on NPC viability but inhibited ECM synthesis and promoted ECM degradation. TNFα-NPC-Exo had less effect on CEPC proliferation but promoted CEPC apoptosis and affect ECM metabolism, inhibiting aggrecan and collagen II expression and enhancing MMP-3 expression. TNFα-NPC-Exo aggravates IVD degeneration in a rat model and promoted CEPC apoptosis. In conclusion, this study demonstrated that degenerated NPC-exosome could induce apoptosis of CEPCs, inhibit ECM synthesis, and promote ECM degradation. In addition, it was proved that degenerated NPC-exosome aggravates IVD degeneration.
椎间盘（IVD）退变是一种复杂的多因素疾病模型，其发病机制尚未完全明确。关于髓核（NP）细胞与软骨终板（CEP）细胞之间信息交互的研究较少。外泌体作为细胞间信息交流的载体，近来已成为研究热点。本研究旨在探讨退变的NP细胞来源的外泌体是否会促进CEP细胞凋亡并加重IVD退变。退变的NP细胞模型由肿瘤坏死因子α（TNFα）诱导产生。从NP细胞培养基的上清液中分离出NPC外泌体。通过CCK-8法检测NP细胞和CEP细胞的活力。通过透射电子显微镜（TEM）、纳米颗粒跟踪分析（NTA）和蛋白质免疫印迹法对外泌体进行鉴定。通过细胞免疫荧光和定量逆转录聚合酶链反应（qRT-PCR）检测细胞外基质（ECM）代谢情况。通过流式细胞术和TUNEL法检测细胞凋亡情况。采用X射线和磁共振成像（MRI）以及苏木精-伊红（H&E）染色、番红O-固绿染色来评估IVD退变程度。TNFα对NPC活力影响较小，但抑制ECM合成并促进ECM降解。TNFα-NPC-Exo对CEPC增殖影响较小，但促进CEPC凋亡并影响ECM代谢，抑制聚集蛋白聚糖和Ⅱ型胶原蛋白表达并增强基质金属蛋白酶-3（MMP-3）表达。TNFα-NPC-Exo加重大鼠模型中的IVD退变并促进CEPC凋亡。总之，本研究表明退变的NPC外泌体可诱导CEPC凋亡，抑制ECM合成并促进ECM降解。此外，还证实退变的NPC外泌体加重IVD退变。
