Humanitas Clinical and Research Center IRCCS, Department of Innate Immunity and Inflammation, via Manzoni 56, 20089, Rozzano, Milan, Italy.
Humanitas University, Via A. Manzoni 113, 20089, Rozzano, Milan, Italy.
Eur J Immunol. 2019 May;49(5):801-811. doi: 10.1002/eji.201847888. Epub 2019 Feb 28.
Macrophage plasticity is the ability of mononuclear phagocytes to change phenotype, function, and genetic reprogramming upon encounter of specific local stimuli. In the tumor microenvironment, Tumor-Associated Macrophages (TAMs) acquire an immune-suppressive and tumor-promoting phenotype. With the aim to re-educate TAMs to antitumor effectors, in this study, we used two immunestimulatory compounds: the TLR7 agonist Imiquimod (IMQ) and the TLR3 agonist Poly(I:C). To better mimic in vitro the response of TAMs, we used Tumor-Conditioned Macrophages (TC-Mϕ) differentiated in the presence of tumor cell supernatants. Our results show that TC-Mϕ respond differently from conventional M2-polarized macrophages. Upon stimulation with IMQ, TC-Mϕ did not upregulate major histocompatibility complex (MHC II) molecules and unexpectedly expressed increased CD206. With both compounds, TC-Mϕ produced higher levels of inflammatory cytokines than M2 macrophages. IMQ and Poly(I:C) differed in the types of regulated genes and secreted mediators. Reflecting their signaling pathways, only IMQ significantly induced IL-1β and IL-6, while only Poly(I:C) stimulated CXCL10, and both upregulated CCL5. Of note, using a novel cytotoxicity assay, Poly(I:C), but not IMQ, was effective in triggering the cytotoxic activity of TC-Mϕ against cancer cells. Overall, the results demonstrate that Poly(I:C) stimulation of TC-Mϕ is superior than IMQ in terms of macrophage re-education toward antitumor effectors.
巨噬细胞可塑性是指单核吞噬细胞在遇到特定的局部刺激时改变表型、功能和遗传重编程的能力。在肿瘤微环境中，肿瘤相关巨噬细胞（TAMs）获得了免疫抑制和促进肿瘤的表型。为了使 TAMs 重新获得抗肿瘤效应，本研究采用了两种免疫刺激化合物：TLR7 激动剂咪喹莫特（IMQ）和 TLR3 激动剂聚肌苷酸（Poly(I:C)）。为了更好地模拟 TAMs 的体外反应，我们使用了在肿瘤细胞上清液存在下分化的肿瘤条件化巨噬细胞（TC-Mϕ）。我们的结果表明，TC-Mϕ 的反应不同于传统的 M2 极化巨噬细胞。用 IMQ 刺激时，TC-Mϕ 并未上调主要组织相容性复合体（MHC II）分子，出人意料地表达了更高水平的 CD206。用这两种化合物刺激时，TC-Mϕ 产生的炎症细胞因子水平均高于 M2 巨噬细胞。IMQ 和 Poly(I:C) 在调节基因和分泌介质的类型上有所不同。反映其信号通路，只有 IMQ 显著诱导了 IL-1β 和 IL-6 的表达，而只有 Poly(I:C) 刺激了 CXCL10 的表达，两者均上调了 CCL5 的表达。值得注意的是，使用一种新型细胞毒性测定法，仅 Poly(I:C)而不是 IMQ 能有效触发 TC-Mϕ 对癌细胞的细胞毒性活性。总体而言，结果表明，在将 TC-Mϕ 重编程为抗肿瘤效应细胞方面，Poly(I:C)刺激 TC-Mϕ 的效果优于 IMQ。
