Histone Lactylation Drives CD8 T Cell Metabolism and Function.

The activation and functional differentiation of CD8 T cells are linked to metabolic pathways that result in the production of lactate. Lactylation is a lactate-derived histone post-translational modification (hPTM); however, the relevance of histone lactylation in the context of CD8 T cell activation and function is not known. Here, we show the enrichment of H3K18-lactylation (H3K18la) and H3K9-lactylation (H3K9la) in human and murine CD8 T cells which act as transcription initiators of key genes regulating CD8 T cell phenotype and function. Further, we note distinct impacts of H3K18la and H3K9la on CD8 T cell subsets linked to their specific metabolic profiles. Importantly, we demonstrate that modulation of H3K18la and H3K9la by targeting metabolic and epigenetic pathways regulates CD8 T cell effector function including anti-tumor immunity in preclinical models. Overall, our study uncovers the unique contributions of H3K18la and H3K9la in modulating CD8 T cell phenotype and function intricately associated with metabolic state.

Myeloid-specific KDM6B inhibition sensitizes glioblastoma to PD1 blockade.

Glioblastoma (GBM) tumors are enriched in immune-suppressive myeloid cells and are refractory to immune checkpoint therapy (ICT). Targeting epigenetic pathways to reprogram the functional phenotype of immune-suppressive myeloid cells to overcome resistance to ICT remains unexplored. Single-cell and spatial transcriptomic analyses of human GBM tumors demonstrated high expression of an epigenetic enzyme-histone 3 lysine 27 demethylase (KDM6B)-in intratumoral immune-suppressive myeloid cell subsets. Importantly, myeloid cell-specific Kdm6b deletion enhanced proinflammatory pathways and improved survival in GBM tumor-bearing mice. Mechanistic studies showed that the absence of Kdm6b enhances antigen presentation, interferon response and phagocytosis in myeloid cells by inhibition of mediators of immune suppression including Mafb, Socs3 and Sirpa. Further, pharmacological inhibition of KDM6B mirrored the functional phenotype of Kdm6b-deleted myeloid cells and enhanced anti-PD1 efficacy. This study thus identified KDM6B as an epigenetic regulator of the functional phenotype of myeloid cell subsets and a potential therapeutic target for enhanced response to ICT.