State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, No.7 Jinsui Road, Tianhe District, Guangzhou City, China.
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, No.7 Jinsui Road, Tianhe District, Guangzhou City, China.
Biomed Pharmacother. 2020 Aug;128:110273. doi: 10.1016/j.biopha.2020.110273. Epub 2020 May 24.
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-κB alpha (p-IκB-α) and the translocation of nuclear factor kappa B p65 (NF-κB 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-κB 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-κB p-65 to the nucleus in vivo. The downstream genes of NF-κB, such as the pro-inflammatory cytokines interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β), 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-κB signalling pathway.
眼内炎症是一系列视网膜退行性疾病的常见病理状况。川芎嗪（TMP），一种中药提取物，广泛用于东亚国家的几种眼部疾病的治疗。然而，TMP 与视力保护作用相关的确切机制尚未阐明。因此，本研究旨在探讨 TMP 在脂多糖（LPS）诱导的视网膜炎症中的抗炎活性的分子靶点，包括在体外和体内。原代培养的视网膜小胶质细胞用 TMP 预处理，然后用 LPS 激活。我们发现，TMP 预处理可显著抑制 LPS 诱导的单核小胶质细胞活化标志物 CD68 的上调。TMP 预处理还抑制了 LPS 诱导的形态变化。此外，TMP 预处理可显著下调 TLR4、磷酸化核因子κB 抑制物α（p-IκB-α）和核因子κB p65（NF-κB p65）的转位，表明 TMP 可能通过 TLR4/NF-κB 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 预处理抑制了小胶质细胞的活化、迁移和再生，特别是在神经节细胞层（GCL）。除了抑制 TLR4 外，TMP 还可显著抑制 NF-κB p65 向核内的转位。NF-κB 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-1β（IL-1β），也被 TMP 预处理显著下调。相应地，TMP 预处理显著减轻了视网膜中 cleaved caspase-3 的表达增加和 B 细胞淋巴瘤-2（Bcl-2）与 Bcl-2 相关 X 蛋白（Bax）比值的降低。TUNEL 检测也表明 TMP 对视网膜具有神经保护作用。因此，本研究阐明了 TMP 通过 TLR4/NF-κB 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。
