Pancreatic ductal adenocarcinoma (PDAC) is a grim disease with high mortality rates. Increased macrophage influx in PDAC is a common hallmark and associated with poor prognosis. Macrophages have high cellular plasticity, which can differentiate into both anti- and pro-tumorigenic properties. Here, we investigated how naïve (M0) macrophages differ from other macrophages in their anti-tumorigenic activities. In vitro BrdU proliferation and Annexin V cell death analyses were performed on PANC-1 and MIA PaCa-2 PDAC cell lines exposed to conditioned medium of different macrophage subsets. Macrophage secreted factors were measured by transcript analysis and ELISA. Therapeutic antibodies were used to functionally establish the impact of the identified cytokine on PDAC proliferation. Proliferation and cell death assays revealed that only M0 macrophages harbor anti-tumorigenic activities and that M1, M2, and TAMs do not. mRNA analysis and ELISA results suggested TNF-α as a potential candidate to mediate M0 macrophage induced cell death. To demonstrate the importance of TNF-α in M0 macrophage-induced cell death, PANC-1 and MIA PaCa-2 cell-lines were exposed to M0 macrophage conditioned medium in the presence of the TNF-α inhibitor Infliximab, which effectively diminished the anti-tumor activities of M0 macrophages. Newly tumor-infiltrated naive M0 macrophages exert anti-tumorigenic activities via TNF-α secretion. Their subsequent differentiation into either M1, M2, or TAM subsets reduces TNF-α levels, thereby abolishing their cytotoxic activity on PDAC cells. These data suggest that reestablishing TNF-α secretion in differentiated macrophages might yield a therapeutic benefit.

中文翻译：

---

早期巨噬细胞浸润通过TNF-α分泌损害胰腺癌细胞的生长

胰腺导管腺癌（PDAC）是一种死亡率很高的严峻疾病。PDAC中巨噬细胞流入的增加是一个普遍现象，并与预后不良有关。巨噬细胞具有很高的细胞可塑性，可以分化为抗肿瘤和促肿瘤作用。在这里，我们研究了天真的（M0）巨噬细胞在抗肿瘤发生活性方面与其他巨噬细胞的区别。在暴露于不同巨噬细胞亚群条件培养基的PANC-1和MIA PaCa-2 PDAC细胞系上进行了体外BrdU增殖和膜联蛋白V细胞死亡分析。通过转录本分析和ELISA测量巨噬细胞分泌因子。使用治疗性抗体来功能确定已确定的细胞因子对PDAC增殖的影响。增殖和细胞死亡试验表明，只有M0巨噬细胞具有抗肿瘤活性，而M1，M2和TAM则没有。mRNA分析和ELISA结果表明TNF-α是介导M0巨噬细胞诱导的细胞死亡的潜在候选者。为了证明TNF-α在M0巨噬细胞诱导的细胞死亡中的重要性，在TNF-α抑制剂英夫利昔单抗的存在下，将PANC-1和MIA PaCa-2细胞系暴露于M0巨噬细胞条件培养基中，这有效地降低了抗巨噬细胞的肿瘤活动。新近被肿瘤浸润的原始M0巨噬细胞通过TNF-α分泌发挥抗肿瘤活性。它们随后分化为M1，M2或TAM子集可降低TNF-α水平，从而消除其对PDAC细胞的细胞毒活性。