Barcoded viral tracing identifies immunosuppressive astrocyte–glioma interactions

Although glioblastoma (GBM) is notoriously resistant to immunotherapy, the specific cellular mechanisms governing immunosuppression within the tumor microenvironment (TME) remain poorly understood. While tumor-associated macrophages and other myeloid cells have been extensively studied, the role of astrocytes—the most abundant glial cells in the brain—in suppressing anti-tumor immunity in GBM is less clear. This study sought to identify novel molecular communication pathways between astrocytes and malignant glioma cells that drive immune evasion.

The researchers developed an innovative viral barcode tracing technique, termed patient-tissue RABID-seq (ptRABID-seq) and tumor-anchored RABID-seq (taRABID-seq), to map cell-cell interactions at single-cell resolution. By using glycoprotein-deficient, pseudotyped rabies viruses, the team could identify and sequence cells physically interacting with one another in both human patient-derived organotypic cultures and mouse orthotopic models. This enabled the identification of specific gene expression signatures and signaling pathways enriched in interacting cell pairs.

Using this barcoding approach, the study identified that astrocytes expressing the protein ANXA1 (Annexin A1) exhibit frequent interactions with GBM cells. The researchers discovered that ANXA1 acts as a ligand for the formyl peptide receptor 1 (FPR1) on GBM cells. This bidirectional communication suppresses the anti-inflammatory properties of astrocytes while simultaneously inhibiting immunogenic necroptosis in tumor cells. When researchers inactivated ANXA1 in astrocytes or blocked FPR1 on GBM cells, they observed a significant increase in the activation of dendritic cells and CD8+ T cells, along with reduced T-cell exhaustion and improved survival in mouse models. Essentially, the ANXA1–FPR1 axis serves as a checkpoint that helps the tumor evade immune destruction.