Sichuan Key Medical Laboratory of New Drug Discovery and Druggability Evaluation, Luzhou Key Laboratory of Activity Screening and Druggability Evaluation for Chinese Materia Medica, School of Pharmacy, Southwest Medical University, Luzhou, China; Department of Neurosurgery Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610000, China.
Sichuan Key Medical Laboratory of New Drug Discovery and Druggability Evaluation, Luzhou Key Laboratory of Activity Screening and Druggability Evaluation for Chinese Materia Medica, School of Pharmacy, Southwest Medical University, Luzhou, China.
Free Radic Biol Med. 2022 Feb 1;179:76-94. doi: 10.1016/j.freeradbiomed.2021.12.263. Epub 2021 Dec 20.
Activation of the NLRP3 inflammasome and its mediated neuroinflammation are implicated in neurodegenerative diseases, while mitophagy negatively regulates NLRP3 inflammasome activation. SHP-2, a protein-tyrosine phosphatase, is critical for NLRP3 inflammasome regulation and inflammatory responses. In this study, we investigated whether triterpenoid saponins in Radix Polygalae inhibit the NLRP3 inflammasome via mitophagy induction. First, we isolated the active fraction (polygala saponins (PSS)) and identified 17 saponins by ultra-performance liquid chromatography coupled with diode-array detection and tandem quadrupole time-of-flight mass spectrometry (UHPLC-DAD-Q/TOF-MS). In microglial BV-2 cells, PSS induced mitophagy as evidenced by increased co-localization of LC3 and mitochondria, as well as an increased number of autophagic vacuoles surrounding the mitochondria. Furthermore, the mechanistic study found that PSS activated the AMPK/mTOR and PINK1/parkin signaling pathways via the upregulation of SHP-2. In Aβ(1-42)-, A53T-α-synuclein-, or Q74-induced BV-2 cells, PSS significantly inhibited NLRP3 inflammasome activation, which was attenuated by bafilomycin A1 (an autophagy inhibitor) and SHP099 (an SHP-2 inhibitor). In addition, the co-localization of LC3 and ASC revealed that PSS promoted the autophagic degradation of the NLRP3 inflammasome. Moreover, PSS decreased apoptosis in conditioned medium-induced PC-12 cells. In APP/PS1 mice, PSS improved cognitive function, ameliorated Aβ pathology, and inhibited neuronal death. Collectively, the present study, for the first time, shows that PSS inhibit the NLRP3 inflammasome via SHP-2-mediated mitophagy in vitro and in vivo, which strongly suggests the therapeutic potential of PSS in various neurodegenerative diseases.
NLRP3 炎性体的激活及其介导的神经炎症与神经退行性疾病有关，而线粒体自噬则负调控 NLRP3 炎性体的激活。SHP-2 是一种蛋白酪氨酸磷酸酶，对 NLRP3 炎性体的调节和炎症反应至关重要。在本研究中，我们研究了远志中的三萜皂苷是否通过诱导线粒体自噬来抑制 NLRP3 炎性体。首先，我们分离出活性部分（远志皂苷（PSS）），并通过超高效液相色谱-二极管阵列检测-串联四极杆飞行时间质谱联用（UHPLC-DAD-Q/TOF-MS）鉴定了 17 种皂苷。在小胶质细胞 BV-2 细胞中，PSS 诱导线粒体自噬，表现为 LC3 和线粒体的共定位增加，以及线粒体周围的自噬小泡数量增加。此外，机制研究发现，PSS 通过上调 SHP-2 激活 AMPK/mTOR 和 PINK1/parkin 信号通路。在 Aβ(1-42)-、A53T-α-突触核蛋白-或 Q74 诱导的 BV-2 细胞中，PSS 显著抑制 NLRP3 炎性体的激活，而自噬抑制剂巴弗洛霉素 A1 和 SHP-2 抑制剂 SHP099 则减弱了这一作用。此外，LC3 和 ASC 的共定位表明 PSS 促进了 NLRP3 炎性体的自噬降解。此外，PSS 降低了条件培养基诱导的 PC-12 细胞中的凋亡。在 APP/PS1 小鼠中，PSS 改善了认知功能，减轻了 Aβ 病理，抑制了神经元死亡。总之，本研究首次表明，PSS 通过 SHP-2 介导的线粒体自噬在体外和体内抑制 NLRP3 炎性体，这强烈表明 PSS 在各种神经退行性疾病中有治疗潜力。
