Fig. 6

CXCR3 PET imaging using [¹⁸F]1 and their corresponding cardiovascular tissues obtained from the ApoE KO mice. A Region I (red arrows) is a [¹⁸F]1-positive region, and the corresponding aorta tissue was tested for expression levels of CXCR3 protein, co-stained with cell-type markers. Adjacent cross sections of the region I (I-a; hematoxylin and eosin (H&E) stain) were subjected to immunofluorescent staining identifying CXCR3 (I-b–I-e; green), CD3 (I-c, red; T cell marker), Mac3 (I-d, red; macrophage marker), and αSMA (I-e, red; SMC marker), counterstained with 4′,6-diamidino-2-phenylindole (DAPI, blue; nuclei). Panels I-c–I-e are magnified views of atherosclerotic plaque indicated on I-a by a rectangle. Region II (blue arrows) has a significant atherosclerotic plaque. Nevertheless, it is a [¹⁸F]1-negative region of PET imaging. Adjacent cross sections of the region II (II-a; H&E stain) were also assessed for expression levels of CXCR3 (II-b–II-e; green), co-stained with CD3 (II-c, red), Mac3 (II-d, red), and αSMA (II-e, red) and counterstained with DAPI (blue). Panels II-c–II-e are magnified views of atherosclerotic plaque indicated on II-a by a rectangle. Scale bar = 200 µm. B Region III (red arrows) is a [¹⁸F]1-positive region, and the corresponding aorta tissue was tested for expression levels of CXCR3 protein, co-stained with cell-type markers. Region III also indicated [¹⁸F]1-positivity, and subsequent histologic analysis revealed a significant atherosclerotic plaque with high CXCR3 expression levels (III-b–III-e; green detection in the fluorescence images), consistent with CXCR3 expression-dependent detection by the radiotracer. Adjacent cross sections of the region III (III-a; H&E stain) were CD3 (III-c, red), Mac3 (III-d, red), and αSMA (III-e, red), counterstained with DAPI (blue). Panels III-c–III-e were magnified views of atherosclerotic plaque indicated on III-a by a rectangle. Scale bar = 200 µm