Tetramethylpyrazine attenuates endotoxin-induced retinal inflammation by inhibiting microglial activation via the TLR4/NF-κB signalling pathway
Tetramethylpyrazine attenuates endotoxin-induced retinal inflammation by inhibiting microglial activation via the TLR4/NF-κB signalling pathway
复制标题
四甲基吡嗪通过 TLR4/NF-kappa B 信号通路抑制小胶质细胞活化，减轻内毒素诱导的视网膜炎症
DOI：
10.1016/j.biopha.2020.110273
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发表时间：
2020-08-01
影响因子：
7.5
通讯作者：
Yu, Keming
中科院分区：
文献类型：
--
作者：
Han, Xiaokun;Chen, Xi;Yu, Keming
眼部炎症是一系列视网膜变性疾病的共同病理状态。川芎嗪（TMP）是一种中草药提取物，在东方国家被广泛用于治疗多种眼部疾病。然而，与TMP的视力保护作用相关的确切机制尚未阐明。因此，本研究的目的是研究TMP的分子靶点在内毒素脂多糖（LPS）诱导的视网膜炎症在体外和体内的抗炎活性。原代培养的视网膜小胶质细胞经TMP预处理后，再经LPS激活。我们发现TMP预处理显著抑制LPS诱导的单核小胶质细胞活化标志物CD 68的上调。川芎嗪预处理可抑制LPS诱导的细胞形态学改变。TMP预处理后，视网膜小胶质细胞Toll样受体4（TLR 4）、NF-κ B α抑制剂（p-I kappa B-alpha）磷酸化和核因子κ B p65（NF-kappa B p65）转位均显著下调，提示TMP可能通过TLR 4/NF-kappa B信号通路抑制LPS诱导的视网膜小胶质细胞活化。这些结果在体内得到了证实。TMP预处理可抑制小胶质细胞的活化、迁移和再生，尤其是在神经节细胞层（GCL）。除了抑制TLR 4外，TMP在体内还显著抑制NF-κ B p-65向细胞核的移位。在视网膜中，TMP预处理显著下调NF-κ B B的下游基因，如促炎细胞因子白细胞介素-6（IL-6）、肿瘤坏死因子α（TNF-α）和白细胞介素-1 β（IL-1 β）。因此，TMP显著减弱了裂解的caspase-3表达的增加和B细胞淋巴瘤-2（Bcl-2）与Bcl-2相关的X蛋白（Bax）的比率的降低。TUNEL法也证实TMP对视网膜有神经保护作用。因此，本研究阐明了TMP通过TLR 4/NF-κ B信号通路抑制小胶质细胞活化来抑制视网膜炎症的新机制。
Ocular inflammation is a common pathological condition of a series of retinal degenerative diseases. Tetramethylpyrazine (TMP), a Chinese herbal extraction, is widely used in the treatment of several ocular diseases in Eastern countries. However, the exact mechanisms correlating the vision protective effects of TMP have not been elucidated. Thus, this study aimed to investigate TMP's molecular targets in anti-inflammatory activity in endotoxin lipopolysaccharide (LPS)-induced retinal inflammation both in vitro and in vivo. The primary cultured retinal microglial cells were pretreated with TMP and then activated by LPS. We found pretreatment with TMP significantly inhibited LPS-induced upregulation of CD68, a marker of mononuclear microglia activation. The morphological changes induced by LPS were also inhibited by the TMP pretreatment. Moreover, Toll like receptor 4 (TLR4), phosphorylation of inhibitor of NF-kappa B alpha (p-I kappa B-alpha) and the translocation of nuclear factor kappa B p65 (NF-kappa B p65) were significantly downregulated in retinal microglial cells with TMP pretreatment, which indicated that TMP might suppress LPS-induced retinal microglial activation through TLR4/NF-kappa B signalling pathway. And these results were confirmed in vivo. Pretreatment with TMP inhibited microglial activation, migration and regeneration, especially in ganglion cell layer (GCL). In addition to the inhibition of TLR4, TMP significantly inhibited the translocation of NF-kappa B p-65 to the nucleus in vivo. The downstream genes of NF-kappa B, such as the pro-inflammatory cytokines interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta), were significantly downregulated by TMP pretreatment in the retina. Accordingly, the increased expression of cleaved caspase-3 and the decreased ratio of B-cell lymphoma-2 (Bcl-2) to Bcl-2 associated X Protein (Bax) were significantly attenuated by TMP. TUNEL assay also demonstrated that TMP exerted neuroprotective effects in the retina. Therefore, this study elucidated a novel mechanism that TMP inhibits retinal inflammation by inhibiting microglial activation via a TLR4/NF-kappa B signalling pathway.