PDF(Pubmed)
Abstract：
Antimicrobial resistance poses a serious threat to human health worldwide and its incidence continues to increase owing to the overuse of antibiotics and other factors. Macrolide antibiotics such as erythromycin (EM) have immunomodulatory effects in addition to their antibacterial activity. Long-term, low-dose administration of macrolides has shown clinical benefits in treating non-infectious inflammatory respiratory diseases. However, this practice may also increase the emergence of drug-resistant bacteria. In this study, we synthesized a series of EM derivatives, and screened them for two criteria: (i) lack of antibacterial activity and (ii) ability to suppress tumor necrosis factor-α (TNF-α) production in THP-1 cells stimulated with lipopolysaccharide. Among the 37 synthesized derivatives, we identified a novel 12-membered ring macrolide EM982 that lacked antibacterial activity against Staphylococcus aureus and suppressed the production of TNF-α and other cytokines. The effects of EM982 on Toll-like receptor 4 (TLR4) signaling were analyzed using a reporter assay and Western blotting. The reporter assay showed that EM982 suppressed the activation of transcription factors, NF-κB and/or activator protein 1 (AP-1), in HEK293 cells expressing human TLR4. Western blotting showed that EM982 inhibited the phosphorylation of both IκB kinase (IKK) β and IκBα, which function upstream of NF-κB, whereas it did not affect the phosphorylation of p38 mitogen-activated protein kinase, extracellular signal-regulated kinase, and c-Jun N-terminal kinase, which act upstream of AP-1. These results suggest that EM982 suppresses cytokine production by inhibiting phosphorylation of IKKβ and IκBα, resulting in the inactivation of NF-κB.
摘要：
抗菌素耐药性对全球人类健康构成严重威胁，由于抗生素的过度使用和其他因素，其发病率继续增加。大环内酯类抗生素如红霉素(EM)除具有抗菌活性外还具有免疫调节作用。长期的,低剂量大环内酯类药物在治疗非感染性炎症性呼吸道疾病方面已显示出临床益处。然而,这种做法也可能增加耐药细菌的出现。在这项研究中,我们合成了一系列EM衍生物，并筛选了两个标准：（i）缺乏抗菌活性和（ii）抑制脂多糖刺激的THP-1细胞中肿瘤坏死因子-α（TNF-α）产生的能力。在合成的37种衍生物中，我们鉴定了一种新型的12元环大环内酯EM982,它缺乏对金黄色葡萄球菌的抗菌活性,并且抑制了TNF-α和其他细胞因子的产生.使用报告基因测定和蛋白质印迹分析EM982对Toll样受体4(TLR4)信号传导的影响。报告基因检测显示EM982抑制转录因子的激活,NF-κB和/或激活蛋白1（AP-1），在表达人TLR4的HEK293细胞中。蛋白质印迹显示EM982抑制IκB激酶(IKK)β和IκBα的磷酸化,在NF-κB的上游起作用，而它不影响p38丝裂原活化蛋白激酶的磷酸化，细胞外信号调节激酶，和c-Jun氨基末端激酶，它在AP-1的上游起作用。这些结果表明，EM982通过抑制IKKβ和IκBα的磷酸化来抑制细胞因子的产生，导致NF-κB失活。
