The microglial activation plays an important role in neurodegenerative diseases by producing several proinflammatory cytokines and nitric oxide (NO). We found that three types of isoflavones and their metabolites that are transformed by the human intestinal microflora suppress lipopolysaccharide (LPS)-induced release of NO and tumor necrosis factor (TNF)-α in primary cultured microglia and BV2 microglial cell lines. The inhibitory effect of the isoflavone metabolites (aglycon form) was more potent than that of isoflavones (glycoside form). The RNase protection assay showed that the isoflavone metabolites regulated inducible nitric oxide synthase (iNOS) and the cytokines at either the transcriptional or post-transcriptional level. A further molecular mechanism study was performed for irisolidone, a metabolite of kakkalide, which had the most potent anti-inflammatory effect among the six isoflavones tested. Irisolidone significantly inhibited the DNA binding and transcriptional activity of nuclear factor (NF)-κB and activator protein-1. Moreover, it repressed the LPS-induced extracellular signal-regulated kinase (ERK) phosphorylation without affecting the activity of c-Jun N-terminal kinase or p38 mitogen-activated protein kinase. The level of NF-κB inhibition by irisolidone correlated with the level of iNOS, TNF-α, and interleukin (IL)-1β suppression in LPS-stimulated microglia, whereas the level of ERK inhibition correlated with the level of TNF-α and IL-1β repression. Overall, the repression of proinflammatory cytokines and iNOS gene expression in activated microglia by isoflavones such as irisolidone might have therapeutic potential for various neurodegenerative diseases including ischemic cerebral disease.
小胶质细胞激活通过产生多种促炎细胞因子和
一氧化氮 (NO) 在神经退行性疾病中发挥重要作用。我们发现,在原代培养的小胶质细胞和 BV2 小胶质
细胞系中,由人类肠道菌群转化的三种异
黄酮及其代谢物可抑制脂
多糖 (LPS) 诱导的 NO 和肿瘤坏死因子 (TNF)-α 的释放。异
黄酮代谢物(苷元形式)的抑制作用比异
黄酮(糖苷形式)更有效。 RNase 保护测定表明,异
黄酮代谢物在转录或转录后
水平调节诱导型
一氧化氮合酶 (iNOS) 和细胞因子。对 irisolidone(kakkalide 的一种代谢物)进行了进一步的分子机制研究,它在测试的六种异
黄酮中具有最有效的抗炎作用。 Irisolidone 显着抑制核因子 (NF)-κB 和激活蛋白-1 的 DNA 结合和转录活性。此外,它还能抑制 LPS 诱导的细胞外信号调节激酶 (ERK)
磷酸化,而不影响 c-Jun N 末端激酶或 p38 丝裂原激活蛋白激酶的活性。伊立索酮对 NF-κB 的抑制
水平与 LPS 刺激的小胶质细胞中 iNOS、TNF-α 和白细胞介素 (IL)-1β 的抑制
水平相关,而 ERK 抑制
水平与 TNF-α 和 IL 的
水平相关-1β抑制。总体而言,异
黄酮(如伊立索酮)对激活的小胶质细胞中促炎细胞因子和 iNOS
基因表达的抑制可能对包括缺血性脑病在内的各种神经退行性疾病具有治疗潜力。