Department of Neurosurgery, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Department of Microbiology & Immunology, Dodson Interdisciplinary Immunotherapy Institute, Sylvester Comprehensive Cancer Center, University of Miami, Miami, Florida, USA.
J Clin Invest. 2019 Jan 2;129(1):137-149. doi: 10.1172/JCI121266. Epub 2018 Nov 19.
Glioblastoma is highly enriched with macrophages, and osteopontin (OPN) expression levels correlate with glioma grade and the degree of macrophage infiltration; thus, we studied whether OPN plays a crucial role in immune modulation. Quantitative PCR, immunoblotting, and ELISA were used to determine OPN expression. Knockdown of OPN was achieved using complementary siRNA, shRNA, and CRISPR/Cas9 techniques, followed by a series of in vitro functional migration and immunological assays. OPN gene-deficient mice were used to examine the roles of non-tumor-derived OPN on survival of mice harboring intracranial gliomas. Patients with mesenchymal glioblastoma multiforme (GBM) show high OPN expression, a negative survival prognosticator. OPN is a potent chemokine for macrophages, and its blockade significantly impaired the ability of glioma cells to recruit macrophages. Integrin αvβ5 (ITGαvβ5) is highly expressed on glioblastoma-infiltrating macrophages and constitutes a major OPN receptor. OPN maintains the M2 macrophage gene signature and phenotype. Both tumor-derived and host-derived OPN were critical for glioma development. OPN deficiency in either innate immune or glioma cells resulted in a marked reduction in M2 macrophages and elevated T cell effector activity infiltrating the glioma. Furthermore, OPN deficiency in the glioma cells sensitized them to direct CD8+ T cell cytotoxicity. Systemic administration in mice of 4-1BB-OPN bispecific aptamers was efficacious, increasing median survival time by 68% (P < 0.05). OPN is thus an important chemokine for recruiting macrophages to glioblastoma, mediates crosstalk between tumor cells and the innate immune system, and has the potential to be exploited as a therapeutic target.
胶质母细胞瘤富含巨噬细胞，骨桥蛋白（OPN）的表达水平与胶质瘤的分级和巨噬细胞浸润程度相关；因此，我们研究了 OPN 是否在免疫调节中发挥关键作用。采用定量 PCR、免疫印迹和 ELISA 来确定 OPN 的表达水平。通过互补 siRNA、shRNA 和 CRISPR/Cas9 技术敲低 OPN，然后进行一系列体外功能迁移和免疫学检测。使用 OPN 基因缺失小鼠来研究非肿瘤来源的 OPN 对携带颅内胶质瘤的小鼠存活的作用。间充质型多形性胶质母细胞瘤（GBM）患者的 OPN 表达较高，是生存预后不良的指标。OPN 是巨噬细胞的有效趋化因子，其阻断显著削弱了胶质瘤细胞招募巨噬细胞的能力。整合素 αvβ5（ITGαvβ5）在浸润到胶质母细胞瘤中的巨噬细胞上高表达，是 OPN 的主要受体。OPN 维持 M2 巨噬细胞的基因特征和表型。肿瘤来源和宿主来源的 OPN 对胶质瘤的发展都至关重要。固有免疫或胶质瘤细胞中 OPN 的缺失导致 M2 巨噬细胞的显著减少和浸润到胶质瘤中的 T 细胞效应活性的增加。此外，胶质瘤细胞中 OPN 的缺失使它们对 CD8+T 细胞的细胞毒性更敏感。在小鼠中系统给予 4-1BB-OPN 双特异性适体是有效的，使中位存活时间延长了 68%（P < 0.05）。因此，OPN 是招募巨噬细胞到胶质母细胞瘤的重要趋化因子，介导肿瘤细胞与固有免疫系统之间的串扰，并具有作为治疗靶点的潜力。
