Department of Biotechnology, Konkuk University, Chungju 380-701, Korea.
Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Korea.
Int J Mol Sci. 2020 Nov 2;21(21):8195. doi: 10.3390/ijms21218195.
Microglia-mediated neuroinflammation is one of the key mechanisms involved in acute brain injury and chronic neurodegeneration. This study investigated the inhibitory effects of 2-hydroxy-4-methylbenzoic anhydride (HMA), a novel synthetic derivative of HTB (3-hydroxy-4-trifluoromethylbenzoic acid) on neuroinflammation and underlying mechanisms in activated microglia in vitro and an in vivo mouse model of Parkinson's disease (PD). In vitro studies revealed that HMA significantly inhibited lipopolysaccharide (LPS)-stimulated excessive release of nitric oxide (NO) in a concentration dependent manner. In addition, HMA significantly suppressed both inducible NO synthase and cyclooxygenase-2 (COX-2) at the mRNA and protein levels in LPS-stimulated BV-2 microglia cells. Moreover, HMA significantly inhibited the proinflammatory cytokines such as interleukin (IL)-1beta, IL-6, and tumor necrosis factor-alpha in LPS-stimulated BV-2 microglial cells. Furthermore, mechanistic studies ensured that the potent anti-neuroinflammatory effects of HMA (0.1, 1.0, and 10 μM) were mediated by phosphorylation of nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IκBα) in LPS-stimulated BV-2 cells. In vivo evaluations revealed that intraperitoneal administration of potent neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, 20 mg/kg, four times a 1 day) in mice resulted in activation of microglia in the brain in association with severe behavioral deficits as assessed using a pole test. However, prevention of microglial activation and attenuation of Parkinson's disease (PD)-like behavioral changes was obtained by oral administration of HMA (30 mg/kg) for 14 days. Considering the overall results, our study showed that HMA exhibited strong anti-neuroinflammatory effects at lower concentrations than its parent compound. Further work is warranted in other animal and genetic models of PD for evaluating the efficacy of HMA to develop a potential therapeutic agent in the treatment of microglia-mediated neuroinflammatory disorders, including PD.
小胶质细胞介导的神经炎症是急性脑损伤和慢性神经退行性变的关键机制之一。本研究探讨了 2-羟基-4-甲基苯酐（HMA），即 HTB（3-羟基-4-三氟甲基苯甲酸）的新型合成衍生物，对体外激活的小胶质细胞中的神经炎症及其潜在机制以及帕金森病（PD）的体内小鼠模型的抑制作用。体外研究表明，HMA 以浓度依赖的方式显著抑制脂多糖（LPS）刺激的过量一氧化氮（NO）释放。此外，HMA 还显著抑制 LPS 刺激的 BV-2 小胶质细胞中诱导型一氧化氮合酶和环氧化酶-2（COX-2）的 mRNA 和蛋白水平。此外，HMA 还显著抑制 LPS 刺激的 BV-2 小胶质细胞中促炎细胞因子如白细胞介素（IL）-1β、IL-6 和肿瘤坏死因子-α。此外，机制研究确保 HMA（0.1、1.0 和 10 μM）的强效抗炎作用是通过 LPS 刺激的 BV-2 细胞中核因子κ轻肽基因增强子 B 细胞抑制剂，α（IκBα）的磷酸化介导的。体内评估表明，腹腔内给予强效神经毒素 1-甲基-4-苯基-1,2,3,6-四氢吡啶（MPTP，20 mg/kg，四次每天）会导致小鼠大脑中小胶质细胞的激活，并伴有严重的行为缺陷，如通过极试验评估。然而，通过口服 HMA（30 mg/kg）14 天可以预防小胶质细胞的激活并减轻 PD 样行为变化。考虑到整体结果，我们的研究表明，HMA 在低于其母体化合物的浓度下表现出强烈的抗炎作用。在其他 PD 动物和遗传模型中进一步研究 HMA 的疗效对于开发治疗小胶质细胞介导的神经炎症疾病（包括 PD）的潜在治疗剂是必要的。
