BACKGROUND Immune checkpoint inhibitor (ICI) usage has resulted in immune-related adverse events in patients with cancer, such as accelerated atherosclerosis. Of immune cells involved in atherosclerosis, the role of CCR2+ (CC motif chemokine receptor 2-positive) proinflammatory macrophages is well documented. However, there is no noninvasive approach to determine the changes of these cells in vivo following ICI treatment and explore the underlying mechanisms of immune-related adverse events. Herein, we aim to use a CCR2 (CC motif chemokine receptor 2)-targeted radiotracer and positron emission tomography (PET) to assess the aggravated inflammatory response caused by ICI treatment in mouse atherosclerosis models and explore the mechanism of immune-related adverse events. METHODS Apoe-/- mice and Ldlr-/- mice were treated with an ICI, anti-PD1 (programmed cell death protein 1) antibody, and compared with those injected with either isotype control IgG or saline. The radiotracer 64Cu-DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid)-ECL1i (extracellular loop 1 inverso) was used for PET imaging of CCR2+ macrophages. Atherosclerotic arteries were collected for molecular characterization. RESULTS CCR2 PET revealed significantly higher radiotracer uptake in both Apoe-/- and Ldlr-/- mice treated with anti-PD1 compared with the control groups. The increased expression of CCR2+ cells in Apoe-/- and Ldlr-/- mice was confirmed by immunostaining and flow cytometry. Single-cell RNA sequencing revealed elevated expression of CCR2 in myeloid cells. Mechanistically, IFNγ (interferon gamma) was essential for aggravated inflammation and atherosclerotic plaque progression following anti-PD1 treatment. CONCLUSIONS Accelerated atherosclerotic plaque inflammation triggered by anti-PD1 treatment can be noninvasively detected by 64Cu-DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid)-ECL1i (extracellular loop 1 inverso) PET. Aggravated plaque inflammation is time- and dose-dependent and predominately mediated by IFNγ signaling. This study warrants further investigation of CCR2 PET as a noninvasive approach to visualize atherosclerotic plaque inflammation and explore the underlying mechanism following ICI treatment.

中文翻译：

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可视化动脉粥样硬化中免疫检查点抑制剂衍生的炎症。


背景 免疫检查点抑制剂 （ICI） 的使用导致癌症患者发生免疫相关不良事件，例如加速动脉粥样硬化。在参与动脉粥样硬化的免疫细胞中，CCR2 + （CC 基序趋化因子受体 2 阳性） 促炎巨噬细胞的作用已得到充分证明。然而，没有无创的方法来确定 ICI 治疗后这些细胞在体内的变化并探索免疫相关不良事件的潜在机制。在此，我们旨在使用 CCR2 （CC 基序趋化因子受体 2） 靶向放射性示踪剂和正电子发射断层扫描 （PET） 来评估小鼠动脉粥样硬化模型中 ICI 治疗引起的加重炎症反应，并探索免疫相关不良事件的机制。方法 Apoe-/-小鼠和 Ldlr-/-小鼠用 ICI 抗 PD1 （程序性细胞死亡蛋白 1） 抗体处理，并与注射同种型对照 IgG 或生理盐水的小鼠进行比较。放射性示踪剂 64Cu-DOTA （1,4,7,10-四氮杂环十二烷-1,4,7,10-四乙酸） -ECL1i （细胞外环 1 inverso） 用于 CCR2 + 巨噬细胞的 PET 成像。收集动脉粥样硬化动脉进行分子表征。结果 CCR2 PET 显示，与对照组相比，接受抗 PD1 治疗的 Apoe-/- 和 Ldlr-/- 小鼠的放射性示踪剂摄取量显着升高。通过免疫染色和流式细胞术证实 Apoe-/- 和 Ldlr-/- 小鼠中 CCR2 + 细胞表达增加。单细胞 RNA 测序显示髓系细胞中 CCR2 的表达升高。从机制上讲，IFNγ （干扰素 γ） 对于抗 PD1 治疗后加重的炎症和动脉粥样硬化斑块进展至关重要。 结论抗 PD1 治疗引发的加速动脉粥样硬化斑块炎症可通过 64Cu-DOTA （1,4,7,10-四氮杂环十二烷-1,4,7,10-四乙酸） -ECL1i （细胞外环 1 inverso） PET 无创检测。加重的斑块炎症是时间和剂量依赖性的，主要由 IFNγ 信号介导。这项研究需要进一步研究 CCR2 PET 作为一种无创方法，以可视化动脉粥样硬化斑块炎症并探索 ICI 治疗后的潜在机制。