Department of Orthopaedics, Renmin Hospital of Wuhan University, Wuhan, China.
Eur Rev Med Pharmacol Sci. 2019 Aug;23(16):6767-6773. doi: 10.26355/eurrev_201908_18714.
To study the potential mechanism of let-7 in participating in the regulation of inflammatory response in spinal cord injury (SCI).
A total of 40 male Sprague-Dawley rats were randomly divided into four groups: group A (Sham, n=10), group B (SCI+NC, n=10), group C (SCI+antagomir, n=10), and group D (SCI+mimics, n=10). The SCI model was established via operation in all groups. After successful modeling, let-7-antagomir negative control (80 mg/kg) was intraperitoneally injected in SCI+NC group at 5 d, an equal amount of let-7-antagomir was intraperitoneally injected in SCI+antagomir group at 5 d, and an equal amount of let-7-mimics was intraperitoneally injected in SCI+mimics group at 5 d. The inflammatory cells in experimental groups and control group were observed via hematoxylin-eosin (HE) staining. At the same time, the expression of let-7 in the four groups was detected via Reverse Transcription-Polymerase Chain Reaction (RT-PCR), the expressions of phosphatidylinositol 3-hydroxy kinase (PI3K) and protein kinase B (Akt) in all groups were detected via Western blotting, and the inflammatory index levels in each group were detected via enzyme-linked immunosorbent assay (ELISA).
In Sham group, it was observed via HE staining that there were only a few bleeding or inflammatory cells. In SCI+NC group, bleeding and inflammatory cells basically tended to be stable. There were a large number of inflammatory cells in SCI+mimics group, while there were some inflammatory cells in SCI+antagomir group, but showing a decreasing trend compared with SCI+NC group. It was found in the RT-PCR detection of let-7 expression level in all groups that the expression of let-7 significantly declined in SCI+antangomir group compared with that in Sham group and SCI+NC group, and there were significant differences (p<0.01). The expression of let-7 was significantly increased in SCI+mimics group compared with that in Sham group and SCI+NC group, and there were significant differences (p<0.01). The results of Western blotting revealed that the PI3K and Akt protein expressions were significantly decreased in SCI+mimics group compared with those in SCI+antagomir group, SCI+NC group, and Sham group (p<0.05). The ELISA results showed that the levels of inflammatory factors in SCI+mimics group, SCI+antagomir group, and SCI+NC group were significantly higher than those in Sham group. In SCI+mimics group, the levels of inflammatory factors were abnormally high and reached extremely significant levels (p<0.05), indicating that let-7 promotes the inflammatory response after SCI.
Let-7 participates in the regulation of inflammatory response in SCI through the PI3K/Akt signaling pathway.
研究 let-7 参与调控脊髓损伤（SCI）中炎症反应的潜在机制。
40 只雄性 Sprague-Dawley 大鼠随机分为 4 组：A 组（假手术，n=10）、B 组（SCI+NC，n=10）、C 组（SCI+antagomir，n=10）和 D 组（SCI+mimics，n=10）。所有组均通过手术建立 SCI 模型。建模成功后，在 SCI+NC 组中，于第 5 天经腹腔注射 let-7-antagomir 阴性对照（80mg/kg），在 SCI+antagomir 组中，于第 5 天经腹腔注射等量的 let-7-antagomir，在 SCI+mimics 组中，于第 5 天经腹腔注射等量的 let-7-mimics。通过苏木精-伊红（HE）染色观察各组实验动物的炎症细胞。同时，通过逆转录-聚合酶链反应（RT-PCR）检测四组中 let-7 的表达，通过 Western blot 检测各组中磷酸肌醇 3-羟激酶（PI3K）和蛋白激酶 B（Akt）的表达，通过酶联免疫吸附试验（ELISA）检测各组的炎症指标水平。
在 Sham 组中，通过 HE 染色观察到仅有少量出血或炎症细胞。在 SCI+NC 组中，出血和炎症细胞基本趋于稳定。在 SCI+mimics 组中存在大量炎症细胞，而在 SCI+antagomir 组中存在一些炎症细胞，但与 SCI+NC 组相比呈下降趋势。在所有组的 let-7 表达水平的 RT-PCR 检测中，与 Sham 组和 SCI+NC 组相比，SCI+antangomir 组中 let-7 的表达明显下降，差异有统计学意义（p<0.01）。与 Sham 组和 SCI+NC 组相比，SCI+mimics 组中 let-7 的表达明显增加，差异有统计学意义（p<0.01）。Western blot 结果显示，与 SCI+antagomir 组、SCI+NC 组和 Sham 组相比，SCI+mimics 组中 PI3K 和 Akt 蛋白表达明显降低（p<0.05）。ELISA 结果显示，SCI+mimics 组、SCI+antagomir 组和 SCI+NC 组的炎症因子水平明显高于 Sham 组。在 SCI+mimics 组中，炎症因子水平异常升高，达到极显著水平（p<0.05），表明 let-7 促进了 SCI 后的炎症反应。
let-7 通过 PI3K/Akt 信号通路参与调控 SCI 中的炎症反应。
