Department of Cardiothoracic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States.
Cancer Immunology and Immunotherapy Program, University of Pittsburgh Medical Center (UPMC) Hillman Cancer Center, Pittsburgh, PA, United States.
Front Immunol. 2022 Apr 27;13:830169. doi: 10.3389/fimmu.2022.830169. eCollection 2022.
Tumor-associated macrophages (TAMs) exert profound influence over breast cancer progression, promoting immunosuppression, angiogenesis, and metastasis. Neuropilin-2 (NRP2), consisting of the NRP2a and NRP2b isoforms, is a co-receptor for heparin-binding growth factors including VEGF-C and Class 3 Semaphorins. Selective upregulation in response to environmental stimuli and independent signaling pathways endow the NRP2 isoforms with unique functionality, with NRP2b promoting increased Akt signaling receptor tyrosine kinases including VEGFRs, MET, and PDGFR. Although NRP2 has been shown to regulate macrophage/TAM biology, the role of the individual NRP2a/NRP2b isoforms in TAMs has yet to be evaluated. Using transcriptional profiling and spectral flow cytometry, we show that NRP2 isoform expression was significantly higher in TAMs from murine mammary tumors. NRP2a/NRP2b levels in human breast cancer metastasis were dependent upon the anatomic location of the tumor and significantly correlated with TAM infiltration in both primary and metastatic breast cancers. We define distinct phenotypes of NRP2 isoform-expressing TAMs in mouse models of breast cancer and within malignant pleural effusions from breast cancer patients which were exclusive of neuropilin-1 expression. Genetic depletion of either NRP2 isoform in macrophages resulted in a dramatic reduction of LPS-induced IL-10 production, defects in phagosomal processing of apoptotic breast cancer cells, and increase in cancer cell migration following co-culture. By contrast, depletion of NRP2b, but not NRP2a, inhibited production of IL-6. These results suggest that NRP2 isoforms regulate both shared and unique functionality in macrophages and are associated with distinct TAM subsets in breast cancer.
肿瘤相关巨噬细胞（TAMs）对乳腺癌的进展有深远的影响，促进免疫抑制、血管生成和转移。神经纤毛蛋白-2（NRP2）由 NRP2a 和 NRP2b 两种同工型组成，是肝素结合生长因子（包括 VEGF-C 和 Class 3 Semaphorins）的共受体。NRP2 同工型对环境刺激的选择性上调和独立的信号通路赋予其独特的功能，NRP2b 促进 Akt 信号的增加，包括 VEGFR、MET 和 PDGFR。尽管 NRP2 已被证明可以调节巨噬细胞/TAM 生物学，但 NRP2a/NRP2b 同工型在 TAMs 中的作用尚未得到评估。通过转录谱分析和光谱流式细胞术，我们显示 NRP2 同工型在来自小鼠乳腺肿瘤的 TAMs 中的表达显著升高。人类乳腺癌转移中的 NRP2a/NRP2b 水平取决于肿瘤的解剖位置，并与原发性和转移性乳腺癌中的 TAM 浸润显著相关。我们在乳腺癌的小鼠模型中以及乳腺癌患者的恶性胸腔积液中定义了具有 NRP2 同工型表达的 TAMs 的不同表型，这些表型与神经纤毛蛋白-1 的表达无关。巨噬细胞中 NRP2 同工型的基因缺失导致 LPS 诱导的 IL-10 产生显著减少，对凋亡乳腺癌细胞的吞噬体处理缺陷，以及共培养后癌细胞迁移增加。相比之下，NRP2b 的缺失，而不是 NRP2a 的缺失，抑制了 IL-6 的产生。这些结果表明，NRP2 同工型调节巨噬细胞中的共享和独特功能，并与乳腺癌中的不同 TAM 亚群相关。
