Osteopontin mediates glioblastoma-associated macrophage infiltration and is a potential therapeutic target
Jun Wei, … , Shulin Li, Amy B. Heimberger
Jun Wei, … , Shulin Li, Amy B. Heimberger
Published January 2, 2019; First published October 11, 2018
Citation Information: J Clin Invest. 2019;129(1):137-149. https://doi.org/10.1172/JCI121266.
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Categories: Research Article Immunology

Osteopontin mediates glioblastoma-associated macrophage infiltration and is a potential therapeutic target

Abstract

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.

Authors

Jun Wei, Anantha Marisetty, Brett Schrand, Konrad Gabrusiewicz, Yuuri Hashimoto, Martina Ott, Zacharia Grami, Ling-Yuan Kong, Xiaoyang Ling, Hillary Caruso, Shouhao Zhou, Y. Alan Wang, Gregory N. Fuller, Jason Huse, Eli Gilboa, Nannan Kang, Xingxu Huang, Roel Verhaak, Shulin Li, Amy B. Heimberger

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Figure 5

GSC OPN–mediated migration of GIMs requires ITGαvβ5.

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GSC OPN–mediated migration of GIMs requires ITGαvβ5. (A) An integrin exp...
(A) An integrin expression panel was used to screen the preferential integrin expression of GIMs relative to the same GBM patient’s peripheral blood monocytes and those of a normal non-tumor-bearing donor. (B) Flow cytometry verifying the expression of ITGαvβ5 on the surface of GIMs. Representative FACS data are shown from 3 independent experiments. (C) Representative flow cytometry histogram demonstrating that M0- and M2-skewed macrophages have enhanced expression of ITGαvβ5. MFI is shown. Representative FACS data from 3 independent experiments are shown. (D) Transwell migration assay of M0 and M2 macrophages pretreated with ITGαvβ5-blocking antibody or its matched isotype antibody (10 μg/ml) and then exposed to 10 ng/ml OPN. Original magnification, ×100 (scale bars: 100 μm). Avg, average. (E) Transwell migration assay of M0 macrophages pretreated with ITGαvβ5-blocking antibody or its matched isotype antibody (10 μg/ml) and then exposed to GSC conditioned medium. Similar results were obtained with M2 macrophages. Original magnification, ×100. Data indicate mean ± SD and are representative of 3 independent experiments.