Lauro Clotilde, Di Angelantonio Silvia, Cipriani Raffaela, Sobrero Fabrizia, Antonilli Letizia, Brusadin Valentina, Ragozzino Davide, Limatola Cristina
Istituto Pasteur-Fondazione Cenci Bolognetti & Dipartimento di Fisiologia Umana e Farmacologia, Centro di Eccellenza BEMM, Università Sapienza, Roma.
J Immunol. 2008 Jun 1;180(11):7590-6. doi: 10.4049/jimmunol.180.11.7590.
The chemokine fractalkine (CX(3)CL1) is constitutively expressed by central neurons, regulating microglial responses including chemotaxis, activation, and toxicity. Through the activation of its own specific receptor, CX(3)CR1, CX(3)CL1 exerts both neuroprotection against glutamate (Glu) toxicity and neuromodulation of the glutamatergic synaptic transmission in hippocampal neurons. Using cultured hippocampal neuronal cell preparations, obtained from CX(3)CR1(-/-) (CX(3)CR1(GFP/GFP)) mice, we report that these same effects are mimicked by exposing neurons to a medium conditioned with CX(3)CL1-treated mouse microglial cell line BV2 (BV2-st medium). Furthermore, CX(3)CL1-induced neuroprotection from Glu toxicity is mediated through the adenosine receptor 1 (AR(1)), being blocked by neuronal cell preparations treatment with 1,3-dipropyl-8-cyclopentylxanthine (DPCPX), a specific inhibitor of AR(1), and mimicked by both adenosine and the specific AR(1) agonist 2-chloro-N(6)-cyclopentyladenosine. Similarly, experiments from whole-cell patch-clamped hippocampal neurons in culture, obtained from CX(3)CR1(+/+) mice, show that CX(3)CL1-induced depression of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid- (AMPA-) type Glu receptor-mediated current (AMPA-current), is associated with AR(1) activity being blocked by DPCPX and mimicked by adenosine. Furthermore, BV2-st medium induced a similar AMPA-current depression in CX(3)CR1(GFP/GFP) hippocampal neurons and this depression was again blocked by DPCPX. We also report that CX(3)CL1 induced a significant release of adenosine from microglial BV2 cells, as measured by HPLC analysis. We demonstrate that (i) CX(3)CL1, along with AR(1), are critical players for counteracting Glu-mediated neurotoxicity in the brain and (ii) AR(1) mediates neuromodulatory action of CX(3)CL1 on hippocampal neurons.
趋化因子fractalkine（CX(3)CL1）由中枢神经元组成性表达，调节小胶质细胞反应，包括趋化性、激活和毒性。通过激活其自身的特异性受体CX(3)CR1，CX(3)CL1对谷氨酸（Glu）毒性发挥神经保护作用，并对海马神经元中的谷氨酸能突触传递进行神经调节。使用从CX(3)CR1(-/-)（CX(3)CR1(GFP/GFP)）小鼠获得的培养海马神经元细胞制剂，我们报告称，将神经元暴露于用CX(3)CL1处理的小鼠小胶质细胞系BV2（BV2-st培养基）条件培养的培养基中，可模拟这些相同的效应。此外，CX(3)CL1诱导的针对Glu毒性的神经保护作用是通过腺苷受体1（AR(1)）介导的，用AR(1)的特异性抑制剂1,3 - 二丙基 - 8 - 环戊基黄嘌呤（DPCPX）处理神经元细胞制剂可阻断该作用，腺苷和特异性AR(1)激动剂2 - 氯 - N(6) - 环戊基腺苷均可模拟该作用。同样，来自CX(3)CR1(+/+)小鼠的培养全细胞膜片钳海马神经元实验表明，CX(3)CL1诱导的α - 氨基 - 3 - 羟基 - 5 - 甲基 - 4 - 异恶唑丙酸（AMPA）型Glu受体介导电流（AMPA电流）的抑制与AR(1)活性相关，DPCPX可阻断该活性，腺苷可模拟该活性。此外，BV2-st培养基在CX(3)CR1(GFP/GFP)海马神经元中诱导了类似的AMPA电流抑制，且该抑制再次被DPCPX阻断。我们还报告称，通过高效液相色谱分析测量，CX(3)CL1诱导小胶质细胞BV2细胞显著释放腺苷。我们证明：（i）CX(3)CL1与AR(1)一起，是对抗大脑中Glu介导的神经毒性的关键因素；（ii）AR(1)介导CX(3)CL1对海马神经元的神经调节作用。
