Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
Biochim Biophys Acta Mol Cell Res. 2020 Oct;1867(10):118766. doi: 10.1016/j.bbamcr.2020.118766. Epub 2020 Jun 3.
Amlexanox, an anti-inflammatory agent, is widely used for treating aphthous ulcers. Recently, amlexanox has received considerable attention because of its efficacy in mitigating metabolic inflammation via directly suppressing IKKε/TBK1. However, because the knockdown of IKKε/TBK1 has no anti-inflammatory effect on lipopolysaccharide (LPS)-primed RAW264.7 cells, the mechanism of amlexanox against classical inflammation is independent of IKKε/TBK1. In this study, we aim to examine the effects of amlexanox on LPS-treated macrophages and in a mouse model of endotoxemia. We found that amlexanox significantly inhibited the production of pro-inflammatory mediators, both in vitro and in vivo, while increased interleukin-10 level in LPS-activated macrophages. Mechanistically, amlexanox down-regulated nuclear factor κB and extracellular signal-regulated kinase/activator protein-1 signaling by elevating intracellular 3',5'-cyclic adenosine monophosphate (cAMP) level and subsequently activating protein kinase A. Molecular docking along with fluorescence polarization and enzyme inhibition assays revealed that amlexanox bound directly to phosphodiesterase (PDE) 4B to inhibit its activity. The anti-inflammatory effects of amlexanox could be abolished by the application of cAMP antagonist or PDE4B siRNA. In addition to PDE4B, the activities of PDE1C, 3A, and 3B were directly inhibited by amlexanox. Our results provide mechanistic insight into the clinical utility of amlexanox for the treatment of inflammatory disorders and might contribute to extending the clinical indications of amlexanox.
氨来呫诺是一种抗炎剂，广泛用于治疗口腔溃疡。最近，氨来呫诺因其通过直接抑制 IKKε/TBK1 减轻代谢性炎症的功效而受到广泛关注。然而，由于 IKKε/TBK1 的敲低对脂多糖 (LPS) 预刺激的 RAW264.7 细胞没有抗炎作用，因此氨来呫诺对抗经典炎症的机制独立于 IKKε/TBK1。在这项研究中，我们旨在研究氨来呫诺对 LPS 处理的巨噬细胞和内毒素血症小鼠模型的影响。我们发现，氨来呫诺在体外和体内均显著抑制促炎介质的产生，同时增加 LPS 激活的巨噬细胞中白细胞介素-10 的水平。在机制上，氨来呫诺通过提高细胞内 3'，5'-环磷酸腺苷 (cAMP) 水平并随后激活蛋白激酶 A，下调核因子 κB 和细胞外信号调节激酶/激活蛋白-1 信号通路。分子对接以及荧光偏振和酶抑制测定表明，氨来呫诺直接与磷酸二酯酶 (PDE) 4B 结合以抑制其活性。cAMP 拮抗剂或 PDE4B siRNA 的应用可消除氨来呫诺的抗炎作用。除 PDE4B 外，氨来呫诺还直接抑制 PDE1C、3A 和 3B 的活性。我们的研究结果为氨来呫诺治疗炎症性疾病的临床应用提供了机制上的见解，并可能有助于扩大氨来呫诺的临床适应证。
