Department of Public Health, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan.
Graduate School of Medicine, Henan Polytechnic University, Jiaozuo, 454000, China.
Apoptosis. 2019 Apr;24(3-4):290-300. doi: 10.1007/s10495-019-01518-y.
Dihydromyricetin (DMY) is a traditional herbal medicine, with a wide range of biological activities. Extreme hyperthermia (HT) can suppress the immune system; thus, protection of the immune system is beneficial in heat-related diseases, including heatstroke. In our study, we revealed the protective effect of DMY against HT-induced apoptosis and analysed the underlying molecular mechanisms. We incubated human myelomonocytic lymphoma U937 cells at 44 °C for 30 min with or without DMY and followed by further incubation for 6 h at 37 °C. Cell viability was determined by the CCK-8 assay. DMY did not cause any cytotoxic effects in U937 cells even at high doses. HT treatment alone induced significant apoptosis, which was detected by DNA fragmentation and Annexin V/PI double staining. Mitochondrial dysfunction was identified by loss of mitochondrial membrane potential (MMP) during heat stimulation. Apoptotic related proteins were involved, truncated Bid and caspase-3 were upregulated, and Mcl-1 and XIAP were downregulated. We also identified the related signalling pathways, such as the MAPK and PI3K/AKT pathways. However, changes in HT were dramatically reversed when the cells were pretreated with DMY before exposure to HT. Overall, MAPKs and PI3K/AKT signalling, mitochondrial dysfunction, and caspase-mediated pathways were involved in the protective effect of DMY against HT-induced apoptosis in U937 cells, which was totally reversed by DMY pretreatment. These findings indicate a new clinical therapeutic strategy for the protection of immune cells during heatstroke.
二氢杨梅素（DMY）是一种传统的草药，具有广泛的生物活性。极度高热（HT）会抑制免疫系统；因此，保护免疫系统对于与热相关的疾病（包括中暑）有益。在我们的研究中，我们揭示了 DMY 对 HT 诱导的细胞凋亡的保护作用，并分析了潜在的分子机制。我们将人髓单核白血病 U937 细胞在 44°C 下孵育 30 分钟，有或没有 DMY，并在 37°C 下进一步孵育 6 小时。通过 CCK-8 测定法测定细胞活力。即使在高剂量下，DMY 也不会在 U937 细胞中引起任何细胞毒性作用。单独的 HT 处理会诱导明显的细胞凋亡，这可以通过 DNA 片段化和 Annexin V/PI 双重染色来检测。在热刺激期间线粒体膜电位（MMP）的丧失鉴定出线粒体功能障碍。凋亡相关蛋白参与其中，截断的 Bid 和 caspase-3 上调，Mcl-1 和 XIAP 下调。我们还确定了相关的信号通路，如 MAPK 和 PI3K/AKT 通路。然而，当细胞在暴露于 HT 之前用 DMY 预处理时，HT 的变化被明显逆转。总体而言，MAPKs 和 PI3K/AKT 信号通路、线粒体功能障碍和 caspase 介导的途径参与了 DMY 对 U937 细胞 HT 诱导的细胞凋亡的保护作用，DMY 预处理完全逆转了这种作用。这些发现为中暑期间免疫细胞的保护提供了一种新的临床治疗策略。
