Department of Otolaryngology Head and Neck Surgery, The Affiliated Huaian No.1 People's Hospital of Nanjing Medical University, Huaian, 223300, Jinagsu Province, China.
Department of Otolaryngology Head and Neck Surgery, The Affiliated Huaian No.1 People's Hospital of Nanjing Medical University, Huaian, 223300, Jinagsu Province, China.
Biochem Biophys Res Commun. 2018 Sep 5;503(2):665-670. doi: 10.1016/j.bbrc.2018.06.058. Epub 2018 Jun 18.
Ischemia and oxidative stress play crucial roles in the pathophysiology of sudden sensorineural hearing loss (SSNHL). Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine and serves an important role in hearing function. The present study was designed to evaluate the effect of MIF on oxygen-glucose deprivation (OGD)-induced ototoxicity and to elucidate its molecular mechanism. In HEI-OC1 auditory cells, OGD reduced cell viability and increased supernatant lactate dehydrogenase (LDH) and MIF in a time-dependent manner. However, the reduced cell viability exerted by OGD was attenuated by antioxidant and MIF. Luciferase reporter assay demonstrated that MIF could activate NF-E2-related factor 2 (Nrf2), and real-time PCR showed increased mRNA expressions of Nrf2 and two Nrf2-responsive genes, including heme oxygenase-1 (HO-1) and NAD(P)H:quinone oxidoreductase 1 (NQO1). MIF also suppressed oxidative stress induced by OGD, as demonstrated by decreased MDA and increased GSH in cellular supernatant. Inhibition of Nrf2 using siRNA suppressed HO-1 protein expression, the protective effect on OGD-induced injury and decrease in oxidative stress by MIF. Moreover, MIF prevented OGD-induced reduction of Akt1 phosphorylation at Ser473. LY294002, an inhibitor of PI3K/Akt signaling, attenuated the enhancement of Nrf2 protein and protective effect of MIF in OGD-treated cochlear cells. We demonstrate that MIF protects cochlear cells against OGD-induced injury through activation of Akt-Nrf2-HO-1 pathway.
缺血和氧化应激在突发性聋（SSNHL）的病理生理学中起着至关重要的作用。巨噬细胞移动抑制因子（MIF）是一种促炎细胞因子，在听力功能中起着重要作用。本研究旨在评估 MIF 对氧葡萄糖剥夺（OGD）诱导的耳毒性的影响，并阐明其分子机制。在 HEI-OC1 听觉细胞中，OGD 以时间依赖性方式降低细胞活力并增加上清液乳酸脱氢酶（LDH）和 MIF。然而，OGD 降低细胞活力的作用被抗氧化剂和 MIF 减弱。荧光素酶报告基因测定表明，MIF 可以激活核因子-E2 相关因子 2（Nrf2），实时 PCR 显示 Nrf2 和两个 Nrf2 反应基因（包括血红素加氧酶-1（HO-1）和 NAD（P）H：醌氧化还原酶 1（NQO1）的 mRNA 表达增加。MIF 还抑制 OGD 诱导的氧化应激，如细胞上清液中 MDA 减少和 GSH 增加所示。使用 siRNA 抑制 Nrf2 抑制了 HO-1 蛋白表达，MIF 对 OGD 诱导的损伤和氧化应激的保护作用减弱。此外，MIF 防止 OGD 诱导的 Akt1 在 Ser473 处的磷酸化减少。PI3K/Akt 信号通路的抑制剂 LY294002 减弱了 Nrf2 蛋白的增强和 MIF 在 OGD 处理的耳蜗细胞中的保护作用。我们证明 MIF 通过激活 Akt-Nrf2-HO-1 通路来保护耳蜗细胞免受 OGD 诱导的损伤。
