Laboratory of Comparative Pathology, Department of Clinical Sciences, Faculty of Veterinary Medicine, Hokkaido University, Kita 18 Nishi 9, Kita-ku, Sapporo, Hokkaido, 060-0818, Japan.
Department of Advanced Pharmaceutics, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido, 060-0818, Japan.
Sci Rep. 2022 Feb 8;12(1):2124. doi: 10.1038/s41598-022-06203-w.
Hemangiosarcoma (HSA) is a malignant tumor derived from endothelial cells. Tumor-associated macrophages are one of the major components of tumor microenvironment and crucial for cancer development. The presence and function of macrophages in HSA have not been studied because there is no syngeneic model for HSA. In this study, we evaluated two mouse HSA cell lines and one immortalized mouse endothelial cell line for their usefulness as syngeneic models for canine HSA. Our results showed that the ISOS-1 cell line developed tumors with similar morphology to canine HSA. ISOS-1 cells highly expressed KDM2B and had similar KDM2B target expression patterns with canine HSA. Moreover, we determined that in both ISOS-1 and canine HSA tumors, macrophages were present as a major constituent of the tumor microenvironment. These macrophages were positive for CD204, an M2 macrophage marker, and express PD-L1, an immune checkpoint molecule. Canine HSA with macrophages expressing PD-L1 had a smaller number of T-cells in tumor tissues than tumors with PD-L1 negative macrophages. ISOS-1-conditioned medium could induce M2 polarization and PD-L1 expression in RAW264.7 mouse macrophage cell line and mouse peritoneal macrophages. These results show that ISOS-1 can be used as a syngenic model for canine HSA and suggest that macrophages play an important role in immune evasion in HSA. Using the syngeneic mouse model for canine HSA, we can further study the role of immune cells in the pathology of HSA.
血管肉瘤（HSA）是一种来源于内皮细胞的恶性肿瘤。肿瘤相关巨噬细胞是肿瘤微环境的主要组成部分之一，对癌症的发展至关重要。由于没有 HSA 的同基因模型，因此尚未研究巨噬细胞在 HSA 中的存在和功能。在这项研究中，我们评估了两种小鼠 HSA 细胞系和一种永生化的小鼠内皮细胞系，以评估它们作为犬 HSA 同基因模型的有用性。我们的结果表明，ISOS-1 细胞系形成的肿瘤具有与犬 HSA 相似的形态。ISOS-1 细胞高表达 KDM2B，并具有与犬 HSA 相似的 KDM2B 靶基因表达模式。此外，我们确定在 ISOS-1 和犬 HSA 肿瘤中，巨噬细胞作为肿瘤微环境的主要成分存在。这些巨噬细胞呈 CD204 阳性，CD204 是 M2 巨噬细胞标志物，并且表达 PD-L1，这是一种免疫检查点分子。表达 PD-L1 的巨噬细胞存在于犬 HSA 中时，肿瘤组织中的 T 细胞数量比 PD-L1 阴性巨噬细胞存在于犬 HSA 中时要少。ISOS-1 条件培养基可在 RAW264.7 小鼠巨噬细胞系和小鼠腹腔巨噬细胞中诱导 M2 极化和 PD-L1 表达。这些结果表明 ISOS-1 可用于犬 HSA 的同基因模型，并表明巨噬细胞在 HSA 的免疫逃逸中起重要作用。使用犬 HSA 的同基因小鼠模型，我们可以进一步研究免疫细胞在 HSA 病理学中的作用。
