Chongqing Key Laboratory of Nutrition and Food Safety, Research Center of Nutrition and Food Safety, Institute of Military Preventive Medicine, Third Military Medical University, Chongqing, 400038, People's Republic of China.
Biofactors. 2018 Mar;44(2):123-136. doi: 10.1002/biof.1395. Epub 2017 Nov 29.
Increasing evidence demonstrates that pyroptosis, pro-inflammatory programmed cell death, is linked to atherosclerosis; however, the underlying mechanisms remain to be elucidated. Dihydromyricetin (DHM), a natural flavonoid, was reported to exert anti-oxidative and anti-inflammatory bioactivities. However, the effect of DHM on atherosclerosis-related pyroptosis has not been studied. In the present study, palmitic acid (PA) treatment led to pyroptosis in human umbilical vein endothelial cells (HUVECs), as evidenced by caspase-1 activation, LDH release, and propidium iodide-positive staining; enhanced the maturation and release of proinflammatory cytokine IL-1β and activation of the NLRP3 inflammasome; and markedly increased intracellular reactive oxygen species (ROS) and mitochondrial ROS (mtROS) levels. Moreover, NLRP3 siRNA transfection or treatment with inhibitors efficiently suppressed PA-induced pyroptosis, and pretreatment with total ROS scavenger or mtROS scavenger attenuated PA-induced NLRP3 inflammasome activation and subsequent pyroptosis. However, DHM pretreatment inhibited PA-induced pyroptotic cell death by increasing cell viability, decreasing LDH and IL-1β release, improving cell membrane integrity, and abolishing caspase-1 cleavage and subsequent IL-1β maturation. We also found that DHM pre-treatment remarkably reduced the levels of intracellular ROS and mtROS and activated the Nrf2 signaling pathway. Moreover, knockdown of Nrf2 by siRNA abrogated the inhibitory effects of DHM on ROS generation and subsequent PA-induced pyroptosis. Together, these results indicate that the Nrf2 signaling pathway plays a role, as least in part, in the DHM-mediated improvement in PA-induced pyroptosis in vascular endothelial cells, which implies the underlying medicinal value of DHM targeting immune/inflammatory-related diseases, such as atherosclerosis. © 2017 BioFactors, 44(2):123-136, 2018.
越来越多的证据表明，细胞焦亡，即促炎的程序性细胞死亡，与动脉粥样硬化有关；然而，其潜在机制仍有待阐明。二氢杨梅素（DHM），一种天然黄酮类化合物，据报道具有抗氧化和抗炎的生物活性。然而，DHM 对动脉粥样硬化相关细胞焦亡的影响尚未被研究。在本研究中，棕榈酸（PA）处理导致人脐静脉内皮细胞（HUVEC）发生细胞焦亡，证据为半胱氨酸天冬氨酸蛋白酶-1（caspase-1）的激活、乳酸脱氢酶（LDH）的释放和碘化丙啶阳性染色；增强促炎细胞因子白细胞介素-1β（IL-1β）的成熟和释放以及 NOD 样受体热蛋白结构域 3（NLRP3）炎症小体的激活；并显著增加细胞内活性氧（ROS）和线粒体 ROS（mtROS）水平。此外，NLRP3 siRNA 转染或用抑制剂处理可有效抑制 PA 诱导的细胞焦亡，而用总 ROS 清除剂或 mtROS 清除剂预处理可抑制 PA 诱导的 NLRP3 炎症小体激活和随后的细胞焦亡。然而，DHM 预处理通过增加细胞活力、降低 LDH 和 IL-1β释放、改善细胞膜完整性以及阻断半胱氨酸天冬氨酸蛋白酶-1（caspase-1）的切割和随后的 IL-1β成熟，抑制 PA 诱导的细胞焦亡性细胞死亡。我们还发现，DHM 预处理可显著降低细胞内 ROS 和 mtROS 水平，并激活核因子红细胞 2（Nrf2）信号通路。此外，用 siRNA 敲低 Nrf2 可消除 DHM 对 ROS 生成和随后的 PA 诱导的细胞焦亡的抑制作用。综上所述，这些结果表明，Nrf2 信号通路至少部分参与了 DHM 介导的改善血管内皮细胞中 PA 诱导的细胞焦亡，这暗示了 DHM 针对免疫/炎症相关疾病（如动脉粥样硬化）的潜在药用价值。
