Neutrophil Senescence Induced by Tumor-Derived HMGB1 Promotes Hepatocellular Carcinoma Progression through Neutrophil Extracellular Trap-Mediated Suppression of CD8+ T Cell Immunity.

Background: Immune cells are essential components of the tumor microenvironment. Among them, neutrophils have gained increasing interest due to their marked heterogeneity. This study focused on aged neutrophils, aiming to uncover their mechanistic contribution to hepatocellular carcinoma (HCC) progression and evaluate their potential clinical importance. Methods: This study included analyses of 2 public datasets (GSE149614 and GSE189903) as well as a clinical cohort comprising 105 patients with HCC and 41 healthy controls. The abundance of aged neutrophils and CD8+ T cells as well as their clinical correlation were assessed, and their potential clinical value was explored. In vitro cellular experiments were used to dissect the molecular mechanisms responsible for CD8+ T cell suppression by aged neutrophils and the progression of neutrophil senescence. In addition, a variety of in vitro and in vivo experiments were performed to evaluate the involvement of aged neutrophils in HCC progression. Results: Peripheral blood and tumor tissues from HCC patients exhibited a marked accumulation of aged neutrophils, which was inversely correlated with CD8+ T cell abundance. Aged neutrophils released excessive neutrophil extracellular traps (NETs) via a caspase-3-dependent mechanism, thereby impairing CD8+ T cell proliferation and activation. Functionally, this suppression of CD8+ T cell activity promoted malignant behaviors of HCC cells, including enhanced proliferation, reduced apoptosis, and increased angiogenesis. In vivo, accumulation of aged neutrophils accelerated HCC progression through CD8+ T cell dysfunction, with minimal impact on distant metastasis. Mechanistically, HCC cell-derived high-mobility group box 1 (HMGB1) induced neutrophil senescence via activation of the Toll-like receptor 4 (TLR4) signaling pathway. Clinically, integrating circulating aged neutrophil with α-fetoprotein (AFP) substantially improved early HCC detection, while the CD8+ T cell-to-aged neutrophil ratio demonstrated strong potential for malignant risk stratification. Conclusion: These findings identify HCC cell-derived HMGB1 as a driver of neutrophil senescence and reveal that aged neutrophils promote HCC progression by inducing CD8+ T cell dysfunction through NET release. More importantly, aged neutrophils represent a robust noninvasive candidate marker for both HCC detection and assessment of malignant risk.