BACKGROUND The major mast cell prostanoid PGD2 is targeted for therapy of asthma and other diseases because the biological actions include bronchoconstriction, vasodilation and regulation of immune cells mediated by three different receptors. It is not known if the alternative to selectively inhibit the biosynthesis of PGD2 affects release of other prostanoids in human mast cells. OBJECTIVES To determine the biochemical consequences of inhibition of the hematopoietic prostaglandin D synthase (hPGDS) PGD2 in human mast cells. METHODS Four human mast cell models, LAD2, cord blood derived mast cells (CBMC), peripheral blood derived mast cells (PBMC) and human lung mast cells (HLMC), were activated by anti-IgE or ionophore A23187. Prostanoids were measured by UPLC-MS/MS. RESULTS All mast cells almost exclusively released PGD2 when activated by anti-IgE or A23187. The biosynthesis was in all four cell types entirely initiated by COX-1. When pharmacologic inhibition of hPGDS abolished formation of PGD2 , PGE2 was detected and release of TXA2 increased. Conversely, when the thromboxane synthase was inhibited, levels of PGD2 increased. Adding exogenous PGH2 confirmed predominant conversion to PGD2 under control conditions, and increased levels of TXB2 and PGE2 when hPGDS was inhibited. However, PGE2 was formed by non-enzymatic degradation. CONCLUSIONS Inhibition of hPGDS effectively blocks mast cell dependent PGD2 formation. The inhibition was associated with redirected use of the intermediate PGH2 and shunting into biosynthesis of TXA2 . However, the levels of TXA2 did not reach those of PGD2 in naïve cells. It remains to determine if this diversion occurs in vivo and has clinical relevance.

中文翻译：

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选择性抑制人肥大细胞中前列腺素 D 2 的生物合成以克服对多种受体拮抗剂的需求：生化后果

背景技术主要的肥大细胞前列腺素PGD2被靶向用于治疗哮喘和其他疾病，因为其生物学作用包括由三种不同受体介导的支气管收缩、血管舒张和免疫细胞调节。目前尚不清楚选择性抑制 PGD2 生物合成的替代方案是否会影响人类肥大细胞中其他前列腺素的释放。目的 确定抑制人类肥大细胞中造血前列腺素 D 合酶 (hPGDS) PGD2 的生化后果。方法 四种人肥大细胞模型，LAD2、脐血来源肥大细胞 (CBMC)、外周血来源肥大细胞 (PBMC) 和人肺肥大细胞 (HLMC)，由抗 IgE 或离子载体 A23187 激活。通过 UPLC-MS/MS 测量前列腺素。结果当被抗IgE或A23187激活时，所有肥大细胞几乎全部释放PGD2。生物合成在所有四种细胞类型中完全由 COX-1 启动。当 hPGDS 的药理学抑制消除了 PGD2 的形成时，检测到 PGE2 并且 TXA2 的释放增加。相反，当血栓素合酶被抑制时，PGD2 水平升高。添加外源 PGH2 证实在对照条件下主要转化为 PGD2，并且当 hPGDS 被抑制时增加了 TXB2 和 PGE2 的水平。然而，PGE2 是通过非酶降解形成的。结论 抑制 hPGDS 可有效阻断肥大细胞依赖性 PGD2 的形成。这种抑制与中间体 PGH2 的重新使用和分流到 TXA2 的生物合成有关。然而，在幼稚细胞中，TXA2 的水平没有达到 PGD2 的水平。