Landscape of glioblastoma niches reveals the prognostic effects of tumor-infiltrating cells

Abstract A comprehensive characterization of non-tumor cells in the niches of primary glioblastoma is not fully established yet. This study aims to present an overview of tumor-infiltrating non-malignant cells in the complex microenvironment of glioblastoma with detailed characterizations of their prognostic effects. We curate 540 gene signatures covering a total of 64 non-tumor cell types. Cell type-specific expression patterns are interrogated by normalized enrichment score (NES) across four large gene expression profiling cohorts of glioblastoma with a total number of 967 cases. The GBMs in each cohort are hierarchically clustered into negative or positive immune response classes with significantly different overall survival. Our results show that astrocytes, macrophages, monocytes, NKTs, preadipocytes, smooth muscle cells, and MSC are risk factors, while CD8 T cells, CD8+ T cells, and plasma cells are protective factors. Moreover, we find that the immune system and organogenesis are uniformly enriched in negative immune response clusters, in contrast to the enrichment of nervous system in positive immune response clusters. Mesenchymal differentiation is also observed in the negative immune response clusters. High enrichment status of macrophages in negative immune response clusters are independently validated by analyzing scRNA-seq data from eight high-grade gliomas, revealing that negative immune response samples comprised 46.63% to 55.12% of macrophages, whereas positive immune response samples comprised only 1.70% to 8.12%, with IHC staining of samples from six short-term and six long-term survivors of GBMs confirming the results. Simple Summary The landscape of infiltrating non-tumor cells in glioblastoma niches remains unclear. In this study, we explore the enrichment status of a total of 64 non-tumor cell types predicted by applying 540 gene signatures curated from literature and normalized enrichment score (NES) across four large gene expression profiling cohorts of glioblastoma with 967 cases. Based on non-tumor cell type-based enrichment status, GBMs in each cohort are classified into positive or negative immune response clusters, showing a statistically significant different overall survival. Astrocytes, macrophages, monocytes, NKTs, preadipocytes, smooth muscle cells, and MSC are identified as risk factors, as well as protector factors of CD8 T cells, CD8+ T cells, and plasma cells. Our results also find that immune system- and organogenesis-related GO terms are uniformly enriched in negative immune response clusters, whereas positive immune response clusters are enriched with GO terms concerning the nervous system. The mesenchymal differentiation is observed in the negative immune response clusters. Particularly, the high presence of macrophages in the negative immune response clusters is further validated using scRNA-seq analysis and IHC staining of GBMs from independent cohorts.