Shieh Chu-Hsin, Heinrich Annette, Serchov Tsvetan, van Calker Dietrich, Biber Knut
Department of Psychiatry and Psychotherapy, University Hospital of Freiburg, Freiburg, Germany; Faculty of Biology, University of Freiburg, Freiburg, Germany.
Glia. 2014 Apr;62(4):592-607. doi: 10.1002/glia.22628. Epub 2014 Jan 28.
ATP is an important regulator of microglia and its effects on microglial cytokine release are currently discussed as important contributors in a variety of brain diseases. We here analyzed the effects of ATP on the production of six inflammatory mediators (IL-6, IL-10, CCL2, IFN-γ, TNF-α, and IL-12p70) in cultured mouse primary microglia. Stimulation of P2X7 receptor by ATP (1 mM) or BzATP (500 µM) evoked the mRNA expression and release of proinflammatory cytokines IL-6, TNF-α, and the chemokine CCL2 in WT cells but not in P2X7(-/-) cells. The effects of ATP and BzATP were inhibited by the nonselective P2 receptor antagonists PPADs and suramin. Various selective P2X7 receptor antagonists blocked the P2X7-dependent release of IL-6 and CCL2, but, surprisingly, had no effect on BzATP-induced release of TNF-α in microglia. Calcium measurements confirmed that P2X7 is the main purine receptor activated by BzATP in microglia and showed that all P2X7 antagonists were functional. It is also presented that pannexin-1 hemichannel function and potential P2X4/P2X7 heterodimers are not involved in P2X7-dependent release of IL-6, CCL2, and TNF-α in microglia. How P2X7-specific antagonists only affect P2X7-dependent IL-6 and CCL2 release, but not TNF-α release is at the moment unclear, but indicates that the P2X7-dependent release of cytokines in microglia is differentially regulated.
三磷酸腺苷（ATP）是小胶质细胞的重要调节因子，目前其对小胶质细胞细胞因子释放的影响被认为是多种脑部疾病的重要促成因素。我们在此分析了ATP对培养的小鼠原代小胶质细胞中六种炎症介质（白细胞介素-6、白细胞介素-10、趋化因子配体2、干扰素-γ、肿瘤坏死因子-α和白细胞介素-12p70）产生的影响。ATP（1 mM）或2'-（3'-O-苯甲酰）-ATP（BzATP，500 µM）对P2X7受体的刺激可诱发野生型（WT）细胞中促炎细胞因子白细胞介素-6、肿瘤坏死因子-α以及趋化因子CCL2的mRNA表达和释放，但在P2X7基因敲除（P2X7(-/-)）细胞中则无此现象。ATP和BzATP的作用被非选择性P2受体拮抗剂吡哆醛磷酸盐（PPADs）和苏拉明所抑制。多种选择性P2X7受体拮抗剂可阻断P2X7依赖的白细胞介素-6和CCL2释放，但令人惊讶的是，对小胶质细胞中BzATP诱导的肿瘤坏死因子-α释放没有影响。钙测量证实P2X7是小胶质细胞中被BzATP激活的主要嘌呤受体，并表明所有P2X7拮抗剂均具有功能。研究还表明，小胶质细胞中白细胞介素-6、CCL2和肿瘤坏死因子-α的P2X7依赖释放不涉及泛连接蛋白-1半通道功能以及潜在的P2X4/P2X7异二聚体。目前尚不清楚P2X7特异性拮抗剂为何仅影响P2X7依赖的白细胞介素-6和CCL2释放，而不影响肿瘤坏死因子-α释放，但这表明小胶质细胞中细胞因子的P2X7依赖释放受到不同的调节。
