THE mTOR KINASE INHIBITOR RAPAMYCIN ENHANCES THE EXPRESSION AND RELEASE OF PRO-INFLAMMATORY CYTOKINE INTERLEUKIN 6 MODULATING THE ACTIVATION OF HUMAN MICROGLIAL CELLS
THE mTOR KINASE INHIBITOR RAPAMYCIN ENHANCES THE EXPRESSION AND RELEASE OF PRO-INFLAMMATORY CYTOKINE INTERLEUKIN 6 MODULATING THE ACTIVATION OF HUMAN MICROGLIAL CELLS
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DOI：
10.17179/excli2019-1715
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发表时间：
2019-01-01
期刊：
影响因子：
4.6
通讯作者：
Dello Russo, Cinzia
中科院分区：
文献类型：
--
作者：
Cappoli, Natalia;Mezzogori, Daniele;Dello Russo, Cinzia
新出现的证据表明，雷帕霉素可能用于治疗几种神经疾病。这种药物很容易通过血脑屏障，并可能在大脑内发挥直接的免疫调节作用。小胶质细胞是大脑的主要先天免疫细胞，因此在这一水平的炎症过程的启动和发展中起关键作用。然而，关于雷帕霉素对小胶质细胞炎症反应的药理作用，来自啮齿动物的研究数据相互矛盾。考虑到啮齿动物小胶质细胞与人小胶质细胞在生化和药理学上的差异，本研究在人小胶质细胞的实验模型--人小胶质细胞克隆3(HMC3)细胞系中研究了雷帕霉素的作用。雷帕霉素在基础条件下和由促炎细胞因子鸡尾酒激活的细胞中进行了NM范围的测试，该鸡尾酒由干扰素-伽马和白细胞介素β(II)的混合物组成。该药物显著增加了II对HMC3细胞中IL-6的表达和释放的刺激作用，同时减少了基础条件下和II激活的细胞中氧自由基(ROS)的产生。与已知的分子作用机制一致，雷帕霉素降低了所谓的雷帕霉素复合体1(MTORC1)激酶的激活程度和细胞内蛋白质总量。与啮齿动物细胞相比，雷帕霉素不会改变人小胶质细胞的活性，也不会抑制细胞的增殖。此外，雷帕霉素对HMC3细胞的形态无明显影响。综上所述，这些数据表明，雷帕霉素抑制人小胶质细胞中mTORC1的表达会导致复杂的免疫调节作用，包括显著增加促炎因子IL-6的表达和释放。
Emerging evidence suggests the potential use of rapamycin in treatment of several neurological disorders. The drug readily crosses the blood brain barrier and may exert direct immunomodulatory effects within the brain. Microglia are the main innate immune cells of the brain, thus critically involved in the initiation and development of inflammatory processes at this level. However, there are conflicting data from rodent studies about the pharmacological effects of rapamycin on microglial inflammatory responses. Considering that rodent microglia display relevant biochemical and pharmacological differences compared to human microglia, in the present study we studied the effects of rapamycin in an experimental model of human microglia, the human microglial clone 3 (HMC3) cell line. Rapamycin was tested in the nM range both under basal conditions and in cells activated with a pro-inflammatory cytokine cocktail, consisting in a mixture of interferon-gamma and interleukin-beta (II). The drug significantly increased II stimulatory effect on interleukin-6 (IL-6) expression and release in the HMC3 cells, while reducing the production of free oxygen radicals (ROS) both under basal conditions and in cells activated with II. Consistently with its known molecular mechanism of action, rapamycin reduced the extent of activation of the so-called 'mechanistic' target of rapamycin complex 1 (mTORC1) kinase and the total amount of intracellular proteins. In contrast to rodent cells, rapamycin did not alter human microglial cell viability nor inhibited cell proliferation. Moreover, rapamycin did not exert any significant effect on the morphology of the HMC3 cells. All together these data suggest that the inhibition of mTORC1 in human microglia by rapamycin results in complex immunomodulatory effects, including a significant increase in the expression and release of the pro-inflammatory IL-6.