Glioblastoma (GBM) is a lethal brain tumor containing a subpopulation of GBM stem cells (GSCs) that interaction with surrounding cells, including infiltrating tumor-associated macrophages and microglia (TAMs). While GSCs and TAMs are in close proximity and likely interact to coordinate tumor growth, a limited number of mechanisms have been identified that support their communication. Here, we identified glycoprotein NMB (GPNMB) as a key factor mediating a unique bidirectional interaction between GSCs and TAMs in GBM. Specifically, GSCs educated macrophages and microglia to preferentially express GPNMB in the GBM tumor microenvironment. As a result, TAM-secreted GPNMB interacted with its receptor CD44 on GSCs to promote their glycolytic and self-renewal abilities via activating the PYK2/RSK2 signaling axis. Disrupting GPNMB-mediated GSC-TAM interplay suppressed tumor progression and self-renewal in GBM mouse models. Our study found a protumor function of GPNMB-mediated GSC-TAM bidirectional communication and supports GPNMB as a promising therapeutic target for GBM.

Tumor-associated macrophages (TAMs) are the most prominent immune cell population in the glioblastoma (GBM) tumor microenvironment and play critical roles in promoting tumor progression and immunosuppression. Here we identified that TAM-derived legumain (LGMN) exhibited a dual role in regulating the biology of TAMs and GBM cells. LGMN promoted macrophage infiltration in a cell-autonomous manner by activating the GSK3β/STAT3 pathway. Moreover, TAM-derived LGMN activated integrin αv/AKT/p65 signaling to drive GBM cell proliferation and survival. Targeting of LGMN-directed macrophage (inhibiting GSK3β and STAT3) and GBM cell (inhibiting integrin αv) mechanisms resulted in an antitumor effect in immunocompetent GBM mouse models that was further enhanced by combination with anti-PD-1 therapy. Our study reveals a paracrine and autocrine mechanism of TAM-derived LGMN that promotes GBM progression and immunosuppression, providing effective therapeutic targets to improve immunotherapy in GBM.

Gamma delta (γδ) T cells, which reside in mucosal and epithelial tissues, are integral to immune responses and are involved in various cancers, autoimmune, and infectious diseases. To study human γδ T cells to a translational level, we developed γδ humanized TCR-T1 (HuTCR-T1) mice using our TruHumanization platform. We compared the metabolomic profiles from plasma samples of wild-type (WT), γδ HuTCR-T1 mice, and humans using UHPLC-MS/MS. Untargeted metabolomics and lipidomics were used to screen all detectable metabolites. Principal component analysis revealed that the metabolomic profiles of γδ HuTCR-T1 mice closely resemble those of humans, with a clear segregation of metabolites between γδ HuTCR-T1 and WT mice. Most humanized γδ metabolites were classified as lipids, followed by organic compounds and amino acids. Pathway analysis identified significant alterations in the metabolism of tryptophan, tyrosine, sphingolipids, and glycerophospholipids, shifting these pathways towards a more human-like profile. Immunophenotyping showed that γδ HuTCR-T1 mice maintained normal proportions of both lymphoid and myeloid immune cell populations, closely resembling WT mice, with only a few exceptions. These findings demonstrate that the γδ HuTCR-T1 mouse model exhibits a metabolomic profile that is remarkably similar to that of humans, highlighting its potential as a relevant model for investigating the role of metabolites in disease development and progression. This model also offers an opportunity to discover therapeutic human TCRs.
© 2024. The Author(s).

Tumor-associated macrophages and microglia (TAMs) are critical for tumor progression and therapy resistance in glioblastoma (GBM), a type of incurable brain cancer. We previously identified lysyl oxidase (LOX) and olfactomedin like-3 (OLFML3) as essential macrophage and microglia chemokines, respectively, in GBM. Here, single-cell transcriptomics and multiplex sequential immunofluorescence followed by functional studies demonstrate that macrophages negatively correlate with microglia in the GBM tumor microenvironment. LOX inhibition in PTEN-deficient GBM cells upregulates OLFML3 expression via the NF-κB-PATZ1 signaling pathway, inducing a compensatory increase of microglia infiltration. Dual targeting macrophages and microglia via inhibition of LOX and the CLOCK-OLFML3 axis generates potent antitumor effects and offers a complete tumor regression in more than 60% of animals when combined with anti-PD1 therapy in PTEN-deficient GBM mouse models. Thus, our findings provide a translational triple therapeutic strategy for this lethal disease.

Abundant macrophage infiltration and altered tumor metabolism are two key hallmarks of glioblastoma. By screening a cluster of metabolic small-molecule compounds, we show that inhibiting glioblastoma cell glycolysis impairs macrophage migration and lactate dehydrogenase inhibitor stiripentol emerges as the top hit. Combined profiling and functional studies demonstrate that lactate dehydrogenase A (LDHA)-directed extracellular signal-regulated kinase (ERK) pathway activates yes-associated protein 1 (YAP1)/ signal transducer and activator of transcription 3 (STAT3) transcriptional co-activators in glioblastoma cells to upregulate C-C motif chemokine ligand 2 (CCL2) and CCL7, which recruit macrophages into the tumor microenvironment. Reciprocally, infiltrating macrophages produce LDHA-containing extracellular vesicles to promote glioblastoma cell glycolysis, proliferation, and survival. Genetic and pharmacological inhibition of LDHA-mediated tumor-macrophage symbiosis markedly suppresses tumor progression and macrophage infiltration in glioblastoma mouse models. Analysis of tumor and plasma samples of glioblastoma patients confirms that LDHA and its downstream signals are potential biomarkers correlating positively with macrophage density. Thus, LDHA-mediated tumor-macrophage symbiosis provides therapeutic targets for glioblastoma.
© 2024. The Author(s).