Li Hongbo, Zhu Chunhui, Wang Baoying, Zhu Wenhua, Feng Yan, Du Fangying, Wang Shaolan, Hu Chenghu, Ma Jie, Yu Xiaorui
The Department of Biochemistry and Molecular Biology, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, 710061, China.
The Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Medical University, Xi'an, Shaanxi, 710021, China.
J Mol Neurosci. 2016 Oct;60(2):195-204. doi: 10.1007/s12031-016-0794-8. Epub 2016 Sep 5.
The excessive apoptosis of retinal nerve cells (RNCs) could cause a variety of retinal neurodegenerative diseases which could result in the irreversible blindness. In this study, the experiment models of H2O2 and light-induced oxidative insult in the retina of Sprague-Dawley (SD) rat were used. We demonstrated the role of toll-like receptor 2 (TLR2) in apoptosis and immune-inflammation induced by oxidative stress insult. Meanwhile, we also tried to elucidate the modulating mechanism of 17β-estradiol (E2) resistant to TLR2 induced by oxidative stress insult. The cell apoptosis induced by oxidative stress was examined by annexin V-FITC/propidium iodide (PI) assay using flow cytometry and the expressions of TLR2 and inflammatory cytokines were determined by real-time PCR and western blotting. Peptidoglycan (PGN) as the ligand of TLR2 and small interfering RNAs of TLR2 (siTLR2) were used to determine the role of TLR2. From the results, firstly, we demonstrated that E2 could reduce the expressions of TLR2 and inflammatory cytokines including TNF-ɑ, IFN-γ, and IL-1β induced by oxidative stress; secondly, the phosphoinositide 3-kinase (PI3K) could not influence the effect of E2 on reducing TLR2 expression induced by H2O2 in RNCs; thirdly, PGN could promote the damage effect of H2O2 by transforming RNCs from late apoptosis to necrosis, however, E2 could decrease the cell apoptosis mediated by PGN; and finally, the apoptosis of RNCs and the expressions of the inflammatory cytokines induced by H2O2 administration were significantly inhibited after TLR2 interference. In summary, E2 reduces the TLR2-mediated immune-inflammation, thereby protecting RNCs against oxidative stress-induced apoptosis via a PI3K-independent signaling pathway. The present results provide evidence that inhibiting of TLR2-mediated immune-inflammation might be a possible therapeutic way to exert auxiliary role on E2 neuroprotection.
视网膜神经细胞（RNCs）的过度凋亡会引发多种视网膜神经退行性疾病，进而导致不可逆的失明。在本研究中，使用了Sprague-Dawley（SD）大鼠视网膜的H2O2和光诱导氧化损伤实验模型。我们证明了Toll样受体2（TLR2）在氧化应激损伤诱导的凋亡和免疫炎症中的作用。同时，我们还试图阐明17β-雌二醇（E2）对氧化应激损伤诱导的TLR2的调节机制。通过流式细胞术使用膜联蛋白V-异硫氰酸荧光素/碘化丙啶（PI）检测法检测氧化应激诱导的细胞凋亡，并通过实时PCR和蛋白质印迹法测定TLR2和炎性细胞因子的表达。使用肽聚糖（PGN）作为TLR2的配体和TLR2的小干扰RNA（siTLR2）来确定TLR2的作用。结果显示，首先，我们证明E2可以降低氧化应激诱导的TLR2和炎性细胞因子（包括TNF-α、IFN-γ和IL-1β）的表达；其次，磷酸肌醇3-激酶（PI3K）不影响E2对RNCs中H2O2诱导的TLR2表达降低的作用；第三，PGN可通过将RNCs从晚期凋亡转变为坏死来促进H2O2的损伤作用，然而，E2可减少PGN介导的细胞凋亡；最后，TLR2干扰后，H2O2给药诱导的RNCs凋亡和炎性细胞因子表达显著受到抑制。总之，E2减少TLR2介导的免疫炎症，从而通过不依赖PI3K的信号通路保护RNCs免受氧化应激诱导的凋亡。目前的结果提供了证据，表明抑制TLR2介导的免疫炎症可能是一种对E2神经保护发挥辅助作用的可能治疗方法。
