Hacking macrophage-associated immunosuppression for regulating glioblastoma angiogenesis

Abstract

Glioblastoma (GBM) is the most lethal primary adult brain tumor and its pathology is hallmarked by distorted neovascularization, diffuse tumor-associated macrophage infiltration, and potent immunosuppression. Reconstituting organotypic tumor angiogenesis models with biomimetic cell heterogeneity and interactions, pro-/anti-inflammatory milieu and extracellular matrix (ECM) mechanics is critical for preclinical anti-angiogenic therapeutic screening. However, current in vitro systems do not accurately mirror in vivo human brain tumor microenvironment. Here, we engineered a three-dimensional (3D), microfluidic angiogenesis model with controllable and biomimetic immunosuppressive conditions, immune-vascular and cell-matrix interactions. We demonstrate in vitro, GL261 and CT-2A GBM-like tumors steer macrophage polarization towards a M2-like phenotype for fostering an immunosuppressive and proangiogenic niche, which is consistent with human brain tumors. We distinguished that GBM and M2-like immunosuppressive macrophages promote angiogenesis, while M1-like pro-inflammatory macrophages suppress angiogenesis, which we coin "inflammation-driven angiogenesis." We observed soluble immunosuppressive cytokines, predominantly TGF-β1, and surface integrin (αβ) endothelial-macrophage interactions are required in inflammation-driven angiogenesis. We demonstrated tuning cell-adhesion receptors using an integrin (αβ)-specific collagen hydrogel regulated inflammation-driven angiogenesis through Src-PI3K-YAP signaling, highlighting the importance of altered cell-ECM interactions in inflammation. To validate the preclinical applications of our 3D organoid model and mechanistic findings of inflammation-driven angiogenesis, we screened a novel dual integrin (αβ) and cytokine receptor (TGFβ-R1) blockade that suppresses GBM tumor neovascularization by simultaneously targeting macrophage-associated immunosuppression, endothelial-macrophage interactions, and altered ECM. Hence, we provide an interactive and controllable GBM tumor microenvironment and highlight the importance of macrophage-associated immunosuppression in GBM angiogenesis, paving a new direction of screening novel anti-angiogenic therapies.

A Photoresponsive Hyaluronan Hydrogel Nanocomposite for Dynamic Macrophage Immunomodulation

“…To examine the requirements of integrins for macrophage polarization, we generated M1 and M2 phenotypes with RAW 264.7 macrophages using lipopolysaccharide (LPS) for M1 phenotype induction and IL‐10 for M2 phenotype induction (details in the Experimental Section) with well‐established protocols . We first examined surface αvβ3 integrin expressions of inactivated M0 macrophages and prepolarized M1 and M2 macrophages embedded in 3D HA hydrogels.…”

Targeting Tumor Associated Macrophages to Overcome Conventional Treatment Resistance in Glioblastoma

“…Gliomas overexpressing VEGF were correlated with an increase in the expression of MHCI and MHCII on macrophages. Endothelial cells and TAMs interaction leads to angiogenesis through the expression of TGF-b1 and integrin avb3, which induces the activation of the SRC-PI3K-YAP signaling (Cui et al, 2018) ( Figure 1). The pro-angiogenic properties of TAMs are mediated by the protein CRCR1.…”

Designer Biomaterials to Model Cancer Cell Invasion In Vitro: Predictive Tools or Just Pretty Pictures?

“…There are few in vitro mechanistic studies of metastasis involving interactions among tumor associated macrophages and cancer cells. Recently, Cui et al used a microfluidic model to probe the influence of macrophage polarization on angiogenesis in the context of glioblastoma 66. In this study, RAW264.7 cells were treated with conditioned media from mouse glioma cell lines GL261 or CT‐2A.…”

“…a) In RGD‐modified collagen I, macrophages treated with glioma cell (GL261 or CT‐2A) conditioned media promote endothelial cell (EC) sprouting. Sprouting is not promoted with M0/M1 coculture 66. b) HUVEC vessel coculture promotes glioblastoma cell (GB3) invasion from spheroids and is dependent on CXCR4 66,68…”