Centro de Investigação Translacional em Oncologia, Instituto do Câncer do Estado de São Paulo, Faculdade de Medicina, Universidade de São Paulo, São Paulo, São Paulo, Brazil.
Departamento de Radiofarmacia, Centro de Investigaciones Nucleares, Facultad de Ciencias Universidad de la República, Montevideo, Uruguay.
PLoS One. 2020 Oct 13;15(10):e0240455. doi: 10.1371/journal.pone.0240455. eCollection 2020.
The presence of a high number of macrophages within solid tumors is often significantly associated with poor prognosis and predict treatment failure for chemotherapy and radiotherapy. Macrophages are innate immune cells capable of performing diverse functions depending on the different signals from the microenvironment. The classically activated macrophage is commonly present during the early stages of tumor development while alternatively activated macrophages are associated with more advanced tumors. The distinction of the antitumoral macrophages from the pro-tumoral macrophages is not absolute. However, they have different cell surface markers such as mannose receptor (MRC1 or CD206) abundantly expressed by macrophages treated with interleukin-4 (IL-4). The important roles of macrophages in cancers suggest that it is important to develop novel therapies that target these cells. In the present study, we designed a probe using Polyamidoamine (PAMAM) fifth-generation (G5) dendrimers conjugated with mannose, Cyanine 7 (Cy7), and hydrazinonicotinamide (HYNIC) for target macrophages with high expression of MRC1 in the tumor. The intracellular uptake of 99mTc-HYNIC-dendrimer-mannose-Cy7 through the interaction with MRC1 in bone marrow-derived macrophages (BMDMs) untreated or treated with lipopolysaccharides (LPS) + interferon (IFN)γ or IL-4 was analyzed. Our results show that high-density mannose dendrimers are preferentially bound by macrophages treated by IFNγ and LPS that express lower levels of MRC1 than for macrophages treated by IL-4 that express high levels of MRC1. Furthermore, the intracellular 99mTc-HYNIC-dendrimer-mannose-Cy7 uptake in BMDMs was not inhibited in the presence of free mannose or glucose. This result suggests that 99mTc-HYNIC-dendrimer-mannose-Cy7 is not internalized via macrophage MRC1. Based on these findings, we concluded that MRC1 expression does not determine the uptake of high-density mannose dendrimers.
肿瘤组织中存在大量巨噬细胞通常与预后不良显著相关，并预示着化疗和放疗治疗失败。巨噬细胞是先天免疫细胞，能够根据微环境中的不同信号执行多种功能。经典激活的巨噬细胞通常存在于肿瘤早期发展阶段，而替代激活的巨噬细胞则与更晚期的肿瘤相关。抗肿瘤巨噬细胞与促肿瘤巨噬细胞之间的区别并不是绝对的。然而，它们具有不同的细胞表面标志物，如巨噬细胞经白细胞介素 4（IL-4）处理后大量表达的甘露糖受体（MRC1 或 CD206）。巨噬细胞在癌症中的重要作用表明，开发针对这些细胞的新型治疗方法非常重要。在本研究中，我们设计了一种探针，使用聚酰胺胺（PAMAM）第五代（G5）树枝状聚合物与甘露糖、Cy7 和肼基烟酰胺（HYNIC）缀合，用于靶向肿瘤中高表达 MRC1 的巨噬细胞。通过与骨髓来源的巨噬细胞（BMDMs）中未处理或用脂多糖（LPS）+干扰素（IFN）γ或 IL-4 处理的 MRC1 相互作用，分析了 99mTc-HYNIC-树枝状聚合物-甘露糖-Cy7 的细胞内摄取。我们的结果表明，高浓度甘露糖树枝状聚合物优先与经 IFNγ和 LPS 处理的巨噬细胞结合，这些巨噬细胞表达的 MRC1 水平低于经 IL-4 处理的巨噬细胞，后者表达高水平的 MRC1。此外，在存在游离甘露糖或葡萄糖的情况下，BMDMs 中 99mTc-HYNIC-树枝状聚合物-甘露糖-Cy7 的细胞内摄取没有被抑制。这一结果表明，99mTc-HYNIC-树枝状聚合物-甘露糖-Cy7 不是通过巨噬细胞 MRC1 内化的。基于这些发现，我们得出结论，MRC1 表达并不决定高密度甘露糖树枝状聚合物的摄取。
