Department of Anesthesiology, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710004, Shaanxi, China.
Department of Anesthesiology and Perioperative Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an, 710032, Shaanxi, China.
J Neuroinflammation. 2023 Nov 15;20(1):264. doi: 10.1186/s12974-023-02942-3.
Lipid metabolism has a crucial role in neural repair in neurodegenerative diseases. We recently revealed that lipogenesis-mediated interleukin-33 (IL-33) upregulation lead to blood-brain barrier (BBB) repair after ischemic stroke. However, manipulating the key enzyme fatty acid synthase (FASN) to enhance lipogenesis was very challenging. Glyceryl triacetate (GTA) was used as a donor of acetate and precursor of acetyl coenzyme A, the key substrate for de novo lipogenesis catalyzed by FASN. Therefore, we hypothesized that GTA would promote lipogenesis the peri-infarct after ischemic stroke and contribute to the BBB repair through IL-33.
Middle cerebral artery occlusion (MCAO) was performed on C57BL mice and GTA was gavage administrated (4 g/kg) on day 2 and 4 after MCAO. Lipogenesis was evaluated by assessment of the protein level of FASN, lipid droplets, and fatty acid products through liquid chromatography-mass spectrometry in the peri-infarct area on day 3 after MCAO, respectively. BBB permeability was determined by extravasation of Evans blue, IgG and dextran, and levels of tight junction proteins in the peri-infarct area on day 7 after MCAO, respectively. Infarct size and neurological defects were assessed on day 7 after MCAO. Brain atrophy on day 30 and long-term sensorimotor abilities after MCAO were analyzed as well. The inhibitor of FASN, C75 and the virus-delivered FASN shRNA were used to evaluate the role of FASN-driven lipogenesis in GTA-improved BBB repair. Finally, the therapeutic potential of recombinant IL-33 on BBB repair and neurological recovery was evaluated.
We found that treatment with GTA increased the lipogenesis as evidenced by lipid droplets level and lauric acid content, but not the FASN protein level. Treatment with GTA increased the IL-33 level in the peri-infarct area and decreased the BBB permeability after MCAO. However, infarct size and neurological defect score were unchanged on day 7 after MCAO, while the long-term recovery of sensorimotor function and brain atrophy were improved by GTA. Inhibition of lipogenesis using C75 or FASN shRNA reversed the beneficial effect of GTA. Finally, exogenous IL-33 improved BBB repair and long-term functional recovery after stroke.
Collectively, we concluded that treatment with GTA improved the BBB repair and functional recovery after ischemic stroke, probably by the enhancement of lipogenesis and IL-33 expression.
脂质代谢在神经退行性疾病中的神经修复中起着关键作用。我们最近发现，脂肪生成介导的白细胞介素 33（IL-33）上调导致缺血性中风后血脑屏障（BBB）修复。然而，操纵关键酶脂肪酸合酶（FASN）来增强脂肪生成是非常具有挑战性的。甘油三乙酸酯（GTA）可用作乙酰乙酸盐的供体和乙酰辅酶 A 的前体，乙酰辅酶 A 是 FASN 催化的从头脂肪生成的关键底物。因此，我们假设 GTA 将促进缺血性中风后梗死周围的脂肪生成，并通过 IL-33 促进 BBB 修复。
在 C57BL 小鼠中进行大脑中动脉闭塞（MCAO），并在 MCAO 后第 2 天和第 4 天给予 GTA 灌胃（4g/kg）。通过液相色谱-质谱法分别评估 MCAO 后第 3 天梗死周围区 FASN、脂滴和脂肪酸产物的蛋白水平来评估脂肪生成。通过 Evans 蓝、IgG 和葡聚糖的外渗以及 MCAO 后第 7 天梗死周围区紧密连接蛋白的水平来分别确定 BBB 通透性。MCAO 后第 7 天评估梗死面积和神经缺陷。还分析了 MCAO 后第 30 天的脑萎缩和长期感觉运动能力。使用 FASN 抑制剂 C75 和病毒递送的 FASN shRNA 评估 GTA 改善 BBB 修复中 FASN 驱动的脂肪生成的作用。最后，评估了重组 IL-33 对 BBB 修复和神经恢复的治疗潜力。
我们发现，GTA 处理增加了脂肪生成，表现为脂滴水平和月桂酸含量增加，但 FASN 蛋白水平不变。GTA 处理后，梗死周围区的 IL-33 水平增加，MCAO 后 BBB 通透性降低。然而，MCAO 后第 7 天梗死面积和神经缺陷评分无变化，而 GTA 可改善长期感觉运动功能和脑萎缩的恢复。使用 C75 或 FASN shRNA 抑制脂肪生成可逆转 GTA 的有益作用。最后，外源性 IL-33 改善了中风后的 BBB 修复和长期功能恢复。
总之，我们的结论是，GTA 治疗可改善缺血性中风后的 BBB 修复和功能恢复，可能是通过增强脂肪生成和 IL-33 表达。
