Tmic-03. targeting the collagen receptor ddr1 promotes anti-glioma immunity by remodeling collagen fiber architecture

Abstract Glioblastoma (GBM), characterized by its aggressive nature and profound immunosuppression, poses a significant therapeutic challenge with limited treatment options. We previously demonstrated that targeting Col1α1 eradicates oncostreams and improves survival in murine models. However, the underlying mechanisms by which collagen reshapes the glioma tumor microenvironment (TME) remain unknown. Through RNA-seq analysis we identified that DDR1, a collagen receptor, is overexpressed in genetically engineered glioma mouse models (GEMMs) including NPA (NRAS/shp53/shATRX), and NPD (NRAS/shp53/PDGFβ), compared to healthy brain tissue. Pharmacological inhibition of DDR1 enhanced radiosensitivity, disrupted oncostreams in vitro, and ex vivo, imaged with time-lapse confocal microscopy. GEMMs of DDR1 knockdown (NRAS/shp53/shATRX/shDDR1) using the Sleeping Beauty transposase system significantly increased median survival by over 50%. Gene Ontology analysis of differentially expressed genes between wild-type and DDR1 knockdown gliomas revealed enrichment in immune reactivity, cytokine-chemokine activity, and extracellular matrix. Inhibition of DDR1 enhanced intratumoral infiltration of CD45+, CD8+, and CD3+ immune cells, accompanied by a decrease in the abundance of immune-suppressive cells, suggesting that gliomas exploit DDR1-mediated mechanisms to promote immunosuppression and facilitate tumor growth. We hypothesize that DDR1 in glioma impedes immune surveillance by promoting collagen fiber alignment, as evaluated using collagen-specific second-harmonic generation microscopy. Furthermore, analysis of human datasets demonstrated a negative correlation between DDR1 expression and CD8, suggesting DDR1’s role as a key regulator of immune surveillance in gliomas. Interestingly, when DDR1 knockdown gliomas were implanted in immune deficient mouse models, NSG (NOD-scid-IL2Rγnull) or CD8−/− immune-deficient mice, no significant differences in survival were observed, indicating DDR1 expression in glioma cells dampens anti-glioma immunity. In conclusion, we propose that DDR1 within glioma cells induces an immune-inhibitory TME, reprograms cytokine and chemokine profiles, and promotes collagen fiber alignment, thus inhibiting anti-glioma immunity. Our data highlight DDR1 as a promising therapeutic target, providing a novel avenue for GBM treatment with significant potential.