Immunoglobulin G (IgG)-Based Imaging Probe Accumulates in M1 Macrophage-Infiltrated Atherosclerotic Plaques Independent of IgG Target Molecule Expression
Immunoglobulin G (IgG)-Based Imaging Probe Accumulates in M1 Macrophage-Infiltrated Atherosclerotic Plaques Independent of IgG Target Molecule Expression
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DOI：
10.1007/s11307-016-1036-8
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发表时间：
2017-08-01
影响因子：
3.1
通讯作者：
Kuge, Yuji
中科院分区：
文献类型：
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作者：
Shimizu, Yoichi;Hanzawa, Hiroko;Kuge, Yuji
易损斑块是缺血性疾病的关键因素。因此，它们的精确检测对于此类疾病的诊断是必要的。已经开发了基于免疫球蛋白G（IgG）的成像探针，用于对与斑块形成相关的生物分子进行成像，以诊断动脉粥样硬化。然而，IgG在动脉粥样硬化区域非特异性蓄积，其蓄积机制尚未详细阐明。因此，我们探索IgG在动脉粥样硬化病变中的积聚机制，并检查用于诊断动脉粥样硬化的放射性标记IgG的图像。给ApoE（-/-）或C57 BL/6 J小鼠静脉注射[Tc-99 m]IgG，24 h后切除睾丸。放射性测量后，对连续主动脉切片进行放射自显影和组织病理学检查。将RAW264.7巨噬细胞极化为M1或M2，然后用[Tc-99 m]IgG处理。孵育1小时后测量细胞中的放射性。在用抗Fc γ受体（Fc γ R）抗体预处理后，还评价了M1巨噬细胞中的[Tc-99 m]IgG摄取。通过蛋白质印迹分析测量细胞中Fc γ R的表达水平。apoE（-/-）小鼠的胸腺中[Tc-99 m]IgG蓄积水平显著高于C57 BL/6 J小鼠（5.1 +/- A 1.4 vs 2.8 +/- A 0.5% ID/g，p < 0.05）。放射自显影图像显示聚集区域与巨噬细胞浸润区域高度相关。M1巨噬细胞的[Tc-99 m]IgG水平显著高于M2或M0（非极化）巨噬细胞[2.2 +/- A 0.3（M1）vs 0.5 +/- A 0.1（M2），0.4 +/- A 0.1（M0）%剂量/mg蛋白，p < 0.01]，Fc γ RI和Fc γ RII表达水平也较高。抗Fc γ R抗体预处理可抑制[Tc-99 m]IgG在M1巨噬细胞中的蓄积[2.2 +/- A 0.3（未预处理）vs 1.2 +/- A 0.2（预处理）%ID/mg蛋白，p < 0.01]。IgG通过动脉粥样硬化病变中的Fc γ R在促炎性M1巨噬细胞中蓄积。因此，在使用基于IgG的探针诊断动脉粥样硬化时，应考虑活性炎症的靶生物分子独立成像。
Vulnerable plaques are key factors for ischemic diseases. Thus, their precise detection is necessary for the diagnosis of such diseases. Immunoglobulin G (IgG)-based imaging probes have been developed for imaging biomolecules related to plaque formation for the diagnosis of atherosclerosis. However, IgG accumulates nonspecifically in atherosclerotic regions, and its accumulation mechanisms have not yet been clarified in detail. Therefore, we explored IgG accumulation mechanisms in atherosclerotic lesions and examined images of radiolabeled IgG for the diagnosis of atherosclerosis.Mouse IgG without specificity to biomolecules was labeled with technetium-99m via 6-hydrazinonicotinate to yield [Tc-99m]IgG. ApoE(-/-) or C57BL/6J mice were injected intravenously with [Tc-99m]IgG, and their aortas were excised 24 h after injection. After radioactivity measurement, serial aortic sections were autoradiographically and histopathologically examined. RAW264.7 macrophages were polarized into M1 or M2 and then treated with [Tc-99m]IgG. The radioactivities in the cells were measured after 1 h of incubation. [Tc-99m]IgG uptake in M1 macrophages was also evaluated after the pretreatment with an anti-Fc gamma receptor (Fc gamma R) antibody. The expression levels of Fc gamma Rs in the cells were measured by western blot analysis.[Tc-99m]IgG accumulation levels in the aortas were significantly higher in apoE(-/-) mice than in C57BL/6J mice (5.1 +/- A 1.4 vs 2.8 +/- A 0.5 %ID/g, p < 0.05). Autoradiographic images showed that the accumulation areas highly correlated with the macrophage-infiltrated areas. M1 macrophages showed significantly higher levels of [Tc-99m]IgG than M2 or M0 (nonpolarized) macrophages [2.2 +/- A 0.3 (M1) vs 0.5 +/- A 0.1 (M2), 0.4 +/- A 0.1 (M0) %dose/mg protein, p < 0.01] and higher expression levels of Fc gamma RI and Fc gamma RII. [Tc-99m]IgG accumulation in M1 macrophages was suppressed by pretreatment with the anti-Fc gamma R antibody [2.2 +/- A 0.3 (nonpretreatment) vs 1.2 +/- A 0.2 (pretreatment) %ID/mg protein, p < 0.01].IgG accumulated in pro-inflammatory M1 macrophages via Fc gamma Rs in atherosclerotic lesions. Thus, the target biomolecule-independent imaging of active inflammation should be taken into account in the diagnosis of atherosclerosis using IgG-based probes.