Computationally informed discovery of scavenging-sparing inhibitors of CC chemokine receptor 2

G 蛋白偶联 CC 趋化因子受体 2 (CCR2) 在循环单核细胞上表达并驱动其 招募到受感染和受损的组织，单核细胞分化为浸润性巨噬细胞 并促进炎症促纤维化环境的形成。因为这个过程是关键 许多炎症性疾病（类风湿性关节炎、多发性硬化症、神经性疼痛和 纤维化等），CCR2 几十年来一直被视为治疗靶点。然而，没有抗CCR2 迄今为止，治疗方法已进入临床，但大多数都因缺乏疗效而失败。 矛盾的是，所有已知的 CCR2 拮抗剂都会导致 CCR2 激动剂血浆水平显着升高 趋化因子 CCL2，它们最初的设计目的就是抑制 CCL2。这样做的治疗效果 尚不清楚：升高可能是所需的（通过趋化因子梯度和迁移反应的钝化）或 一种不需要的（通过“抑制剂的抑制”）现象。非迁移性带来了额外的复杂性 CCL2 的功能例如调节白细胞分化。值得关注的是，拮抗剂诱导的 CCL2 升高 当拮抗剂本身的血浆浓度减弱时达到峰值。因此，这种副作用可能 损害抗 CCR2 临床候选药物的安全性和有效性。不幸的是，系统调查 由于缺乏适当的药理学工具，这种现象在体内目前是不可能的。 申请人的长期目标是破译 CCR2 信号传导的复杂性并开发临床成功的药物 CCR2 靶向剂。申请人最近发现了拮抗剂诱导的CCL2的基础 升高，并证明它是通过抑制重要但未被充分认识的调节功能而发生的 CCR2 的作用，它清除组织中组成型产生的 CCL2，并将其从血浆中清除。扫荡是 抑制是因为所有已知的拮抗剂都会阻止趋化因子与 CCR2 结合。这些发现概述了 CCR2 介导的迁移拮抗剂的概念可能性，该拮抗剂不会导致 CCL2 升高，通过 避免趋化因子与 CCR2 结合，从而避免其被清除。本提案的目标是发现 通过计算引导的方法来实现此类拮抗剂，并追求两个具体目标：(1) Via in silico 针对 CCR2:CCL2 复杂模型集合进行化合物库筛选，识别化学物质 同时结合 CCR2 和 CCL2，并表征它们的体外药理学。 (2) 通过计算阐明 CCR2 与 CCL2 复合物的动力学，并鉴定 G 蛋白 VLS 中具有富集清除保留抑制剂潜力的不相容状态。 拟议工作的结果将是发现第一个具有新颖药理学的化学探针 与 CCR2 的关系：CCR2 介导的细胞迁移抑制剂，可避免 CCL2 清除。这些分子 将协助申请人的团队和其他人对拮抗剂诱导的 CCL2 体内升高进行研究。的 研究结果还将为未来针对 CCR2 治疗炎症和癌症的努力提供信息。

The G protein-coupled CC chemokine receptor 2 (CCR2) is expressed on circulating monocytes and drives their recruitment to infected and damaged tissues, where the monocytes differentiate into infiltrating macrophages and promote the formation of an inflammatory pro-fibrotic environment. Because this process is key to the pathogenesis of many inflammatory diseases (rheumatoid arthritis, multiple sclerosis, neuropathic pain, and fibrosis, among others), CCR2 has been pursued for decades as a therapeutic target. However, no anti-CCR2 therapeutics have so far made it to the clinic, with most failing for lack of efficacy. Paradoxically, all known CCR2 antagonists cause a profound elevation in plasma levels of CCR2 agonist chemokine CCL2, which they were designed to inhibit in the first place. The therapeutic consequences of this are not clear: the elevation may be a desired (via blunting of chemokine gradients and migratory responses) or an unwanted (via “inhibition of an inhibitor”) phenomenon. Additional complexity arises from non-migratory functions of CCL2 in e.g. regulating leukocyte differentiation. Concerningly, antagonist-induced CCL2 elevation reaches its peak when the plasma concentration of the antagonist itself wanes. Therefore, this side effect may compromise the safety and efficacy of anti-CCR2 clinical candidates. Unfortunately, systematic investigation of this phenomenon in vivo is currently impossible, for the lack of proper pharmacological tools. The applicants’ long-term goal is to decipher the intricacies of CCR2 signaling and to develop clinically successful CCR2-targeting agents. The applicants have recently discovered the basis for antagonist-induced CCL2 elevation, and demonstrated that it occurs via inhibition of an important but underappreciated regulatory function of CCR2 where it scavenges CCL2 constitutively produced by tissues, and clears it from plasma. Scavenging is inhibited because all known antagonists prevent chemokine binding to CCR2. These findings outline the conceptual possibility of an antagonist of CCR2-mediated migration that does not cause CCL2 elevation, by sparing chemokine binding to CCR2 and hence its scavenging. The goal of the present proposal is to discover such antagonists via a computationally guided approach, by pursuing two Specific Aims: (1) Via in silico compound library screening against an ensemble of CCR2:CCL2 complex models, identify chemicals that bind CCR2 concurrently with CCL2, and characterize their pharmacology in vitro. (2) Computationally elucidate the dynamics of CCR2 in complex with CCL2, and identify G-protein- incompatible states with the potential to enrich for scavenging-sparing inhibitors in VLS. The outcome of the proposed work will be the discovery of the first chemical probes with novel pharmacology in relation to CCR2: the inhibitors of CCR2-mediated cell migration that spare CCL2 scavenging. These molecules will assist investigations of antagonist-induced CCL2 elevation in vivo by the applicant’s group and others. The findings will also inform future efforts of therapeutic targeting of CCR2 for inflammation and cancer.