An immunosuppressed microenvironment distinguishes lateral ventricle–contacting glioblastomas

Abstract

Radiographic contact of glioblastoma (GBM) tumors with the lateral ventricle and adjacent stem cell niche correlates with poor patient prognosis, but the cellular basis of this difference is unclear. Here, we reveal and functionally characterize distinct immune microenvironments that predominate in subtypes of GBM distinguished by proximity to the lateral ventricle. Mass cytometry analysis of isocitrate dehydrogenase wild-type human tumors identified elevated T cell checkpoint receptor expression and greater abundance of a specific CD32 + CD44 + HLA-DR hi macrophage population in ventricle-contacting GBM. Multiple computational analysis approaches, phospho-specific cytometry, and focal resection of GBMs validated and extended these findings. Phospho-flow quantified cytokine-induced immune cell signaling in ventricle-contacting GBM, revealing differential signaling between GBM subtypes. Subregion analysis within a given tumor supported initial findings and revealed intratumor compartmentalization of T cell memory and exhaustion phenotypes within GBM subtypes. Collectively, these results characterize immunotherapeutically targetable features of macrophages and suppressed lymphocytes in GBMs defined by MRI-detectable lateral ventricle contact.

Single Cell Profiling Distinguishes Leukemia-Selective Chemotypes

“…The goal of this experiment was to identify chemotypes with exceptional leukemia cell bioactivity. Exceptional activity following treatment with a compound or signaling input can be measured by phospho-flow in different ways, including exceptional potency (i.e., activity at nM or lower concentration) 38 , bioactivity (i.e., orders of magnitude greater responses in a measured proteins; e.g., high per-cell γH2AX indicating exceptionally strong DNA damage response) 16,18,38,39 , pathway selectivity or signature profile (i.e., a specific combination of activities per cell, such as activation of γH2AX without inhibition of p-4EBP1, indicating a DNA damage response without a halt to protein synthesis) 38,39 , and/or exceptional selectivity (i.e., targeting a specific subpopulation of cells, such as targeting cancer cells without targeting healthy cells) 16,38,[40][41][42] . Here, the order of evaluation was first on bioactivity and selectivity, then on profile, and finally on evaluation of potency.…”

IL-8 Instructs Macrophage Identity in Lateral Ventricle Contacting Glioblastoma

“…To determine whether M_GBM_TCM macrophages model the generation of previously described GAMs, we performed Marker Enrichment Modeling (MEM) analysis 37,54 using published cytometry data from primary human GBM macrophages 15 and newly generated data from macrophages subjected to different stimulatory conditions, including TCM, M2 cytokines IL-6 and IL-4, and M1 control cytokine IFNγ 33 . Following MEM, a ΔMEM analysis 55 , which subtracts two MEM labels to identify differentially enriched features, was performed to quantify and compare changes in protein expression between macrophages.…”

“…High dimensional immune cell profiling in GBM recently identified a subset of CD32 + HLA-DR hi monocyte derived macrophages that were distinguished by a potentiated response to inflammatory cytokine signaling via p-STAT3. The abundance of CD32 + GBM associated macrophages (GAMs) independently stratified patient survival, and these GAMs predominated in the microenvironment of tumors that contacted the lateral ventricles, the location of the ventricular-subventricular zone (V-SVZ) stem cell niche 15 . V-SVZ contact by GBM tumors is established as closely associated with poorer clinical outcomes for patients 16,17 .…”

Single-nucleus and spatial landscape of the sub-ventricular zone in human glioblastoma

“…Given the limited efficacy of current treatments for GBM patients, our results provides evidence of novel potential therapeutic opportunities to target the T_SVZ microenvironment. Previous work identified associations between GBMmes and MDM, and between GBMac and microglia 75 , as well as a more abundant specific MDM population in GBM with radiographic contact to the ventricle, whereas microglia are enriched in GBM showing no ventricular contact 76 . However, none of these studies was performed on tissues sampled directly from the SVZ of GBM patients.…”