Glioblastoma-instructed microglia transition to heterogeneous phenotypic states with phagocytic and dendritic cell-like features in patient tumors and patient-derived orthotopic xenografts

Abstract

BackgroundGlioblastoma (GBM) evades the immune system by creating an immune-suppressive tumor microenvironment (TME), where GBM-associated myeloid cells are geared towards tumor-supportive roles. However, it is unclear whether recruited myeloid cells are phenotypically and functionally identical. Here, we aim to understand the TME heterogeneity in GBM patients recapitulated in patient-derived orthotopic xenografts (PDOXs) and systematically characterize myeloid cell type identities at the molecular and functional level.MethodsWe applied single-cell RNA-sequencing and spatial transcriptomics, multicolor flow cytometry, immunohistochemistry and functional assays to examine the heterogeneity of the TME in GBM. Various GBM PDOXs representing different tumor phenotypes were analyzed and compared to the patient tumors, normal brain and mouse GL261 glioma model.ResultsPDOX models recapitulate the major components of the TME detected in human GBM, where tumor cells reciprocally interact with host cells to create a GBM-specific TME. We detect the most prominent transcriptomic adaptations in myeloid cells, which are largely of microglial origin. We reveal intra-tumoral heterogeneity of microglia and identify diverse phenotypic states across distinct GBM landscapes and tumor niches. GBM-educated microglia acquire dendritic cell-like features, displaying increased migration and phagocytosis. We further find novel microglial states expressing astrocytic and endothelial markers. Lastly, we show that temozolomide (TMZ) treatment leads to transcriptomic plasticity of both GBM tumor cells and adjacent TME components.ConclusionsOur data provide insight into the phenotypic adaptation of the heterogeneous TME instructed by GBM. We uncover that GBM-educated microglia are represented by various concomitant states, both in patients and recapitulated in PDOXs, displaying different pro- or anti-tumoral properties that are modulated by anti-neoplastic treatments, such as TMZ.KEY POINTSGBM-educated tumor microenvironment is faithfully recapitulated and modulated in PDOX modelsMicroglia represent an essential myeloid cell population in the GBM microenvironmentGBM-educated microglia acquire heterogeneous transcriptomic states across distinct tumor nichesGBM-educated microglia subsets display phagocytic and dendritic cell-like gene expression programs, which are modulated upon TMZ treatmentIMPORTANCE OF THE STUDYThis manuscript addresses tumor-immune interactions in GBM, focusing on the molecular changes of the myeloid compartment. We find that myeloid cells, the most abundant immune cell population in brain tumors, undergo the most prominent transcriptional adaptation in the TME. Resident microglia represent the main myeloid cell population in the cellular tumor, while peripheral-derived myeloid cells appear to infiltrate the brain at sites of blood-brain barrier disruption. We identify reactive dendritic cell-like gene expression programs associated with enhanced phagocytic and antigen-presentation features in GBM-educated microglia subsets that might be harnessed for novel immunotherapeutic approaches. Overall, PDOX models faithfully recapitulate the major components of the GBM-educated TME and allow assessment of phenotypic changes in the GBM ecosystem upon treatment.

RETRACTED: Characterization of therapeutic effects in Glioblastoma through integrated spatial single-cell multiome profiling of longitudinal samples: unveiling clinically relevant subtypes of pathological changes

“…previously associated with an activated state sharing some antigen presentation properties92,93 We see a relevant increase of CD11c+ MG in the STS patients compared to the MTS/LTS subgroups, which is in line with an immunosuppressive role of MG in neurodegenerative disorders (figS8e).…”

Magnetic resonance imaging-guided intracranial resection of glioblastoma tumors in patient-derived orthotopic xenografts leads to clinically relevant tumor recurrence

“…PDOXs faithfully preserve the genetic, epigenetic, transcriptomic, metabolomic and stem cell-like profiles of human gliomas [23,[28][29][30][31]. Human tumor cells further reciprocally interact with the mouse brain to create a clinically relevant tumor microenvironment [32]. While longitudinal PDOXs derived from the same patient at different time points of the clinical treatment protocol allow for monitoring long-term tumor evolution, preclinical testing requires direct treatment in mice.…”

“…PDOXs faithfully preserve the genetic, epigenetic, transcriptomic, metabolomic and stem cell-like pro les of human GBMs (18,(20)(21)(22)(23). Human GBM cells further reciprocally interact with the mouse brain to create a clinically relevant tumor microenvironment (24).…”

Glioblastoma-instructed microglia transition to heterogeneous phenotypic states with phagocytic and dendritic cell-like features in patient tumors and patient-derived orthotopic xenografts

“…LIH cohort of PDOX models with associated molecular characterization are available via the PDCM finder [90] and are part of the EuroPDX consortium collection [91]. The scRNA-seq data from the PDOX models have been deposited in the Gene Expression Omnibus repository with accession numbers GSE226468 [92] (mouse TME) and GSE128195 [93] (human tumor cells). Codes used to analyze data in this paper are available at the Github repository [94].…”