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/TANK binding kinase 1 (TBK1). However, because the knockdown of IKKε/TBK1 had 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 can 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.

Amlexanox，一种抗炎药，被广泛用于治疗口疮。近来，氨来那昔因其通过直接抑制IKKε/ TANK结合激酶1（TBK1）减轻代谢炎症的功效而受到了广泛的关注。但是，由于IKKε/ TBK1的敲除对脂多糖（LPS）引发的RAW264.7细胞没有抗炎作用，因此氨纶抗经典炎症的机制独立于IKKε/ TBK1。在这项研究中，我们旨在检查氨甲ano呤对脂多糖治疗的巨噬细胞和内毒素血症小鼠模型的影响。我们发现氨lexanox在体外和体内均显着抑制促炎性介质的产生，而LPS激活的巨噬细胞中白介素10水平升高。从机理上讲，氨lexanox通过升高细胞内3'，5'-环磷酸腺苷（cAMP）水平并随后激活蛋白激酶A来下调核因子κB和细胞外信号调节的激酶/激活蛋白1信号传导。分子对接以及荧光偏振酶抑制试验表明，氨蝶呤直接与磷酸二酯酶（PDE）4B结合以抑制其活性。通过使用cAMP拮抗剂或PDE4B siRNA，可以消除氨来那昔的抗炎作用。除PDE4B外，氨纶还可以直接抑制PDE1C，3A和3B的活性。