基于OATPs-Pgp/Mrps转运通路探究阿奇霉素治疗儿童支原体肺炎疗效个体差异的机制

Azithromycin,a first-line medicine for mycoplasma pneumonia in children, has been reported to be highly variable in clinical efficacy among different children. It is a meaningful effort both in theory and practice to investigate the inner mechanism. . From a pharmacokinetic perspective, the efficacy of azithromycin is highly related to its concentration in peripheral bloodphagocytes based on the fact that azithromycin is mainly accumulated and transported by phagocytes before it could effect. In our previous study, we focused on azithromycin concentration in phagocytes in vivo, which significant differences were found in children dosed azithromycin. Also, Uptake study of azithromycin in j774 cells were conducted, with significant change of intracellular concentration were seen in the presence of P-gp, Mrps or OATPs inhibitor, indicating transporter play a vital role on azithromycin transport in phagocytes. . In this project, we plan to investigate the specific transport mechanism of azithromycin in phagocyte, and evaluate the relationship among the transporter activity, intracellular concentration as well as clinical efficacy based on a series of cell and animal studies. Furthermore, with the combination of the ontogeny and genetic polymorphism in children, we aim to construct transporter mechanistic population pharmacokinetics of azithromycin and reveal the reason of significant differences of azithromycin efficacy. Thus, we can not only provide theory evidence and clinical data for the rational administration of azithromycin in children, but also open up a new perspective for the study of antibiotic efficacy.

阿奇霉素是儿童支原体肺炎主要用药，但其疗效存在显著个体差异，研究该差异的机制具有重要理论意义和应用价值。. 阿奇霉素是浓度依赖性抗生素，主要经吞噬细胞蓄积、传递发挥作用，胞内浓度是影响临床疗效的关键因素。我们前期研究表明儿童给药后阿奇霉素在吞噬细胞中浓度个体差异明显，抑制P-gp、Mrps和OATPs等转运体功能显著影响其胞内浓度。故推测转运体决定阿奇霉素在吞噬细胞的浓度，胞内浓度差异可能是疗效不同的重要原因。. 为验证该推测，拟采用细胞和动物模型，研究阿奇霉素在吞噬细胞的转运通路，揭示转运体活性-细胞药物浓度-疗效的变化规律；在此基础上，构建基于转运机制的群体药代模型，表征转运体基因多态性和儿童生长发育对阿奇霉素胞内浓度的影响，预测儿童给药剂量和临床疗效。. 本研究既可从转运角度阐释抗生素疗效差异的机理，也可为优化儿童支原体肺炎治疗方案提供数据支持。

阿奇霉素是儿童支原体肺炎主要用药，但其疗效存在显著个体差异，研究该差异的机制具有重要的理论意义和应用价值。阿奇霉素是浓度依赖性抗生素，主要经吞噬细胞蓄积、传递发挥作用，细胞内浓度是影响临床疗效的关键。转运体可能是决定阿奇霉素在吞噬细胞浓度及个体差异的重要因素。本研究（1）构建了广泛表达且可能介导阿奇霉素转运的OATP1B1、OATP1B3、OATP2B1、OCT1、OAT2、ABCB1、ABCG2、ABCC2，以及表达在吞噬细胞上的OATP1A2、OATP3A1、OATP4C1、ABCC10转运体质粒。在MDCK和HEK293t细胞上进行了相应质粒的细胞转染，建立了各转运体高表达的转染细胞。（2）开展了阿奇霉素在转染细胞中的摄取和外排实验，筛选出了OATP4C1和ABCB1对阿奇霉素有显著的转运作用；通过时间依赖性、浓度依赖性及抑制剂抑制实验表征了OATP4C1/ABCB1对阿奇霉素的转运。（3）开展了阿奇霉素在人淋巴母细胞系（Jurkat）中的诱导实验，表明了长期使用阿奇霉素，对ABCC2、ABCC5等吞噬细胞上转运体的显著诱导作用。（4）纳入104名2-12岁儿童肺炎患者，开展多中心研究，完成了阿奇霉素在儿童中的群体药代动力学分析。（5）检测了ABCB1的基因多态性位点，发现ABCB1位点活性改变对阿奇霉素在肺炎儿童患者中的清除率的影响。（6）在肺炎儿童群体中，明确了肝功能异常患者的阿奇霉素清除率显著低于肝功能正常的儿童患者，并基于此进行蒙特卡洛剂量模拟，对阿奇霉素的剂量进行了优化。通过对不同给药剂量和给药频次组合的模拟结果表明，对于肝功能正常的肺炎儿童患者（ALT≤40），15mg/kg的负荷剂量和10mg/kg的维持剂量分别可以获得给药第一天55.2%和稳态53.2%的达标率。对于肝功能损伤的儿童患者（ALT＞40），负荷剂量和维持剂量分别降低15%，可以在该人群中产生约50%的达标率。本项研究基于机制研究和临床观察，首次提出了在儿童肺炎患者中应给予15mg/kg阿奇霉素负荷剂量，从而使阿奇霉素在儿童体内及时达到有效的治疗浓度并发挥药效。项目按既定目标完成任务，在国际药代及药理领域权威期刊发表SCI论文5篇。