H3K9 lactylation in malignant cells facilitates CD8⁺ T cell dysfunction and poor immunotherapy response

Histone lysine lactylation (Kla) is a post-translational modification, and its role in tumor immune escape remains unclear. Here, we find that increased histone lactylation is associated with poor response to immunotherapy in head and neck squamous cell carcinoma (HNSCC). H3K9la is identified as a specific modification site in HNSCC. Using cleavage under targets and tagmentation analyses, interleukin-11 (IL-11) is identified as a downstream regulatory gene of H3K9la. IL-11 transcriptionally activates immune checkpoint genes through JAK2/STAT3 signaling in CD8⁺ T cells. Additionally, IL-11 overexpression promotes tumor progression and CD8⁺ T cell dysfunction in vivo. Moreover, IL11 knockdown reverses lactate-induced CD8⁺ T cell exhaustion, and cholesterol-modified siIL11 restores CD8⁺ T cell killing activity and enhances immunotherapy efficacy. Clinically, H3K9la positively correlates with IL-11 expression and unfavorable immunotherapy responses in patients. This study reveals the crucial role of histone lactylation in immune escape, providing insights into immunotherapy strategies for HNSCC.