R406, an orally available spleen tyrosine kinase inhibitor blocks Fc receptor signaling and reduces immune complex-mediated inflammation
R406, an orally available spleen tyrosine kinase inhibitor blocks Fc receptor signaling and reduces immune complex-mediated inflammation
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DOI：
10.1124/jpet.106.109058
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发表时间：
2006-12-01
影响因子：
3.5
通讯作者：
Masuda, Esteban S.
中科院分区：
文献类型：
--
作者：
Braselmann, Sylvia;Taylor, Vanessa;Masuda, Esteban S.
最近令人信服的证据已经导致重新关注抗体和免疫复合物在几种自身免疫性疾病如类风湿性关节炎的发病机制中的作用。这些由自身抗原的自身抗体组成的免疫复合物可以主要通过结合和激活免疫球蛋白Fc受体（FcR）来介导炎症反应。使用基于细胞的结构活性关系与培养的人肥大细胞，我们已经确定了小分子R406 [N4（2，2-二甲基-3-氧代-4H-吡啶[1，4]恶嗪-6-基）-5-氟-N2-（3，4，5-三甲氧基苯基）-2，4-嘧啶二胺]作为免疫球蛋白E（IgE）和IgG介导的Fc受体信号传导激活的强效抑制剂（脱粒的EC 50 = 56 - 64 nM）。在这里，我们表明，R406的主要目标是脾酪氨酸激酶（Syk），它在激活Fc受体和B细胞受体（BCR）的信号传导中起着关键作用。R406抑制用于活化肥大细胞中的T细胞和B细胞中的B细胞连接蛋白/SLP 65的Syk底物连接蛋白的磷酸化。R406与Syk的ATP结合口袋结合并作为ATP竞争性抑制剂抑制其激酶活性（Ki = 30 nM）。此外，R406阻断Syk依赖性FcR介导的单核细胞/巨噬细胞和中性粒细胞的活化以及BCR介导的B淋巴细胞的活化。R406是选择性的，如使用代表特异性和一般信号传导途径的大组Syk非依赖性基于细胞的测定所评估的。与Syk抑制一致，在反向被动Arthus反应和两种抗体诱导的关节炎模型中，对小鼠口服R406减少了免疫复合物介导的炎症。最后，我们报告了第一个非人的研究表明，R406是口服生物利用度，实现曝光能够抑制Syk依赖性IgE介导的嗜碱性粒细胞活化。总的来说，结果显示R406在人类疾病中调节Syk活性的潜力。
Recent compelling evidence has lead to renewed interest in the role of antibodies and immune complexes in the pathogenesis of several autoimmune disorders, such as rheumatoid arthritis. These immune complexes, consisting of autoantibodies to self-antigens, can mediate inflammatory responses largely through binding and activating the immunoglobulin Fc receptors (FcRs). Using cell-based structure activity relationships with cultured human mast cells, we have identified the small molecule R406 [N4(2,2-dimethyl-3- oxo-4H-pyrid[1,4]oxazin-6-yl)-5-fluoro-N2-( 3,4,5-trimethoxyphenyl)-2,4-pyrimidinediamine] as a potent inhibitor of immunoglobulin E (IgE)- and IgG-mediated activation of Fc receptor signaling (EC50 for degranulation = 56 - 64 nM). Here we show that the primary target for R406 is the spleen tyrosine kinase ( Syk), which plays a key role in the signaling of activating Fc receptors and the B-cell receptor (BCR). R406 inhibited phosphorylation of Syk substrate linker for activation of T cells in mast cells and B-cell linker protein/SLP65 in B cells. R406 bound to the ATP binding pocket of Syk and inhibited its kinase activity as an ATP-competitive inhibitor (K-i = 30 nM). Furthermore, R406 blocked Syk-dependent FcR-mediated activation of monocytes/ macrophages and neutrophils and BCR-mediated activation of B lymphocytes. R406 was selective as assessed using a large panel of Syk-independent cell-based assays representing both specific and general signaling pathways. Consistent with Syk inhibition, oral administration of R406 to mice reduced immune complex-mediated inflammation in a reverse-passive Arthus reaction and two antibody-induced arthritis models. Finally, we report a first-inhuman study showing that R406 is orally bioavailable, achieving exposures capable of inhibiting Syk-dependent IgE-mediated basophil activation. Collectively, the results show R406 potential for modulating Syk activity in human disease.