Functional Reprogramming of Neutrophils within the Brain Tumor Microenvironment by Hypoxia-Driven Histone Lactylation.

Despite functional heterogeneity, the high frequency of intratumoral neutrophils predicts poor clinical outcomes. The tumor microenvironment reprograms neutrophils into immunosuppressive subsets that hinder anticancer immunity, thereby contributing to tumor growth and resistance to immunotherapies. However, the mechanisms underlying neutrophil reprogramming remain elusive. In this study, we report that the immunosuppressive ability of brain tumor-infiltrating neutrophils was restricted to a highly glycolytic and long-lived subset expressing CD71, which acquired immunosuppressive properties in response to hypoxia. Mechanistically, hypoxia boosted glucose metabolism in CD71+ neutrophils, leading to high lactate production. Lactate caused histone lactylation, which subsequently regulated arginase-1 expression, required for T-cell suppression. Targeting histone lactylation with the antiepileptic drug isosafrole blocked CD71+ neutrophil immunosuppressive ability, delayed tumor progression, and sensitized brain tumors to immunotherapy. A distinctive gene signature characterizing immunosuppressive CD71+ neutrophils correlated with adverse clinical outcomes across diverse human malignancies. This study identifies histone lactylation as a potential therapeutic target to counteract neutrophil-induced immunosuppression within tumors. SIGNIFICANCE: Neutrophils are critical contributors to the immunosuppressive microenvironment that restricts the effects of promising immunotherapies in glioblastoma. Our study identifies hypoxia-driven histone lactylation as a potential target to block immunosuppressive neutrophils and boost the effects of immunotherapy in glioblastoma and in other cancer settings beyond brain tumors.