Rice bran derivatives alleviate microglia activation: possible involvement of MAPK pathway.
Rice bran derivatives alleviate microglia activation: possible involvement of MAPK pathway.
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DOI：
10.1186/s12974-016-0615-6
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发表时间：
2016-06-14
影响因子：
9.3
通讯作者：
Fiebich BL
中科院分区：
文献类型：
--
作者：
Bhatia HS;Baron J;Hagl S;Eckert GP;Fiebich BL
小胶质细胞的过度激活被认为是脑炎症的一个关键标志，在调节神经炎症事件中起着关键作用。小胶质细胞的神经炎症反应是各种神经退行性疾病的主要危险因素之一。保护大脑和减缓这些神经退行性疾病进展的策略之一是食用富含抗氧化剂和多酚的饮食。因此，本研究旨在评估米糠提取物（RBE）对初级大鼠小胶质细胞的抗炎作用，RBE是维生素E形式（生育酚和生育三烯醇）和γ -米二醇的丰富来源之一。采用高效液相色谱（HPLC）法对其维生素E谱进行定量分析。在RBE存在或不存在的情况下，用脂多糖（LPS）刺激小胶质细胞。用酶免疫分析法（EIA）测定前列腺素（前列腺素（PG） E2、8-异-前列腺素F2α(8-异- pgf2 α)）的释放量。采用western blot、ELISA和实时荧光定量PCR检测PGE2合成相关的蛋白水平和基因（环氧化酶-2 （COX-2）、微粒体前列腺素E合成酶-1 (mPGES-1)）以及各种促炎性和抗炎性细胞因子（TNF-α、IL-1β、IL-6和IL-10）。此外，为了阐明RBE的分子靶点，我们研究了各种丝裂原活化蛋白激酶（MAPK）信号分子（p38 MAPK、ERK 1/2和JNK）的磷酸化状态和NF-kB通路的激活情况。RBE显著抑制lps激活的原代小胶质细胞中PGE2的释放和自由基形成（8-iso-PGF2α）。RBE对PGE2的抑制依赖于小胶质细胞中COX-2和mPGES-1免疫反应性的降低。有趣的是，用RBE治疗活化的小胶质细胞进一步增强了小胶质细胞M2标记物IL-10的基因表达，降低了促炎M1标记物（TNF-α, IL-1β）的表达。进一步的机制研究表明RBE通过干扰MAPK信号通路的重要步骤来抑制小胶质细胞的激活。此外，LPS激活小胶质细胞导致IkB-α降解，这一过程不受RBE预处理的影响。综上所述，我们的数据表明RBE能够通过干扰重要的炎症通路来影响小胶质细胞的激活。这些体外研究结果进一步证明了RBE作为一种营养保健品的潜在价值，可以预防与神经炎性疾病（包括阿尔茨海默病）相关的小胶质细胞功能障碍。本文的在线版本（doi:10.1186/s12974-016-0615-6）包含补充材料，可供授权用户使用。
Hyperactivation of microglia is considered to be a key hallmark of brain inflammation and plays a critical role in regulating neuroinflammatory events. Neuroinflammatory responses in microglia represent one of the major risk factors for various neurodegenerative diseases. One of the strategies to protect the brain and slow down the progression of these neurodegenerative diseases is by consuming diet enriched in anti-oxidants and polyphenols. Therefore, the present study aimed to evaluate the anti-inflammatory effects of rice bran extract (RBE), one of the rich sources of vitamin E forms (tocopherols and tocotrienols) and gamma-oryzanols, in primary rat microglia. The vitamin E profile of the RBE was quantified by high-performance liquid chromatography (HPLC). Microglia were stimulated with lipopolysaccharide (LPS) in the presence or absence of RBE. Release of prostaglandins (prostaglandin (PG) E2, 8-iso-prostaglandin F2α (8-iso-PGF2α)) were determined with enzyme immunoassay (EIA). Protein levels and genes related to PGE2 synthesis (Cyclooxygenase-2 (COX-2), microsomal prostaglandin E synthase-1 (mPGES-1)) and various pro- and anti-inflammatory cytokines (TNF-α, IL-1β, IL-6, and IL-10), were assessed by western blot, ELISA, and quantitative real-time PCR. Furthermore, to elucidate the molecular targets of RBE, the phosphorylated state of various mitogen-activated protein kinase (MAPK) signaling molecules (p38 MAPK, ERK 1/2, and JNK) and activation of NF-kB pathway was studied. RBE significantly inhibited the release of PGE2 and free radical formation (8-iso-PGF2α) in LPS-activated primary microglia. Inhibition of PGE2 by RBE was dependent on reduced COX-2 and mPGES-1 immunoreactivity in microglia. Interestingly, treatment of activated microglia with RBE further enhanced the gene expression of the microglial M2 marker IL-10 and reduced the expression of pro-inflammatory M1 markers (TNF-α, IL-1β). Further mechanistic studies showed that RBE inhibits microglial activation by interfering with important steps of MAPK signaling pathway. Additionally, microglia activation with LPS leads to IkB-α degradation which was not affected by the pre-treatment of RBE. Taken together, our data demonstrate that RBE is able to affect microglial activation by interfering in important inflammatory pathway. These in vitro findings further demonstrate the potential value of RBE as a nutraceutical for the prevention of microglial dysfunction related to neuroinflammatory diseases, including Alzheimer’s disease. The online version of this article (doi:10.1186/s12974-016-0615-6) contains supplementary material, which is available to authorized users.