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Abstract：
T cell immunoglobulin and mucin domain-containing-3 (TIM-3) is an immune checkpoint expressed mainly on CD4+ and CD8+ T cells. In addition to negatively regulating inflammatory T cell function, TIM-3 is a promising immunotherapy target. Herein, the aim is to develop an immuno-positron emission tomography (immunoPET) probe for noninvasively characterizing TIM-3 expression. Flow cytometry is used to detect the expression levels of TIM-3 in B16F10 cells. RMT3-23, a rat antimouse TIM-3-specific monoclonal antibody, is radiolabeled with 64Cu and the performance of 64Cu-NOTA-RMT3-23 is interrogated by immunoPET in murine melanoma models before and after radiation therapies. Biodistribution and immunofluorescent staining studies are carried out after the immunoPET imaging studies. TIM-3 is negatively expressed in B16F10 cells, and its expression is not induced by radiation therapies. ImmunoPET imaging with 64Cu-NOTA-RMT3-23 precisely tracks the unique distribution of TIM-3-positive lymphocytes in immunocompetent melanoma models, and tumor uptake of the radiotracer is not affected by either single-dose or fractionated radiation therapies. The 64Cu-NOTA-RMT3-23 immunoPET imaging results are further mirrored by the immunofluorescent staining studies. These results demonstrate the feasibility of 64Cu-NOTA-RMT3-23 immunoPET in tracking TIM-3 and highlight a new opportunity to optimize TIM-3-targeted immunotherapies with this novel imaging strategy.
摘要：
T细胞免疫球蛋白和含粘蛋白结构域-3(TIM-3)是主要在CD4+和CD8+T细胞上表达的免疫检查点。除了负调节炎性T细胞功能外，TIM-3是一个有前途的免疫治疗靶点。在这里，目的是开发一种用于非侵入性表征TIM-3表达的免疫正电子发射断层扫描（免疫PET）探针。流式细胞术用于检测TIM-3在B16F10细胞中的表达水平。RMT3-23，一种大鼠抗小鼠TIM-3特异性单克隆抗体，用64Cu放射性标记,并且64Cu-NOTA-RMT3-23的性能在放射疗法之前和之后在鼠黑素瘤模型中通过免疫PET进行询问。在免疫PET成像研究之后进行生物分布和免疫荧光染色研究。TIM-3在B16F10细胞中呈阴性表达,它的表达不是由放射治疗引起的。使用64Cu-NOTA-RMT3-23的免疫PET成像精确跟踪TIM-3阳性淋巴细胞在免疫活性黑色素瘤模型中的独特分布，并且放射性示踪剂的肿瘤摄取不受单剂量或分次放射疗法的影响。64Cu-NOTA-RMT3-23免疫PET成像结果进一步通过免疫荧光染色研究得到反映。这些结果证明了64Cu-NOTA-RMT3-23免疫PET在追踪TIM-3中的可行性，并强调了使用这种新型成像策略优化TIM-3靶向免疫疗法的新机会。
