The Dichotomous Role of Tertiary Lymphoid Structures in Hepatocellular Carcinoma: From Spatial Location to Clinical Implications.

Background: Tertiary lymphoid structures (TLSs) function as ectopic immune centers in non-lymphoid tissues and are a key area of research in tumor immunology, particularly in hepatocellular carcinoma (HCC). However, the role of TLSs in HCC shows significant heterogeneity; intratumoral TLSs (iTLSs) are linked to favorable outcomes and immune therapy responses, while peritumoral TLSs may be dysfunctional or promote tumor progression. This spatial paradox is a core scientific question for understanding and leveraging TLSs in HCC treatment. The liver's unique immunosuppressive and fibrotic microenvironment, influenced by hepatic stellcell-derived cancer-associated fibroblasts (CAFs) and local signals like tryptophan metabolism, profoundly regulates TLSs formation and functional polarization.

Methods: This review integrates current research on TLSs in HCC, focusing on their functional heterogeneity based on spatial localization and the regulatory mechanisms involving the liver's microenvironment. It identifies major bottlenecks in TLSs clinical translation, including inconsistent assessment standards and the lack of non-invasive dynamic monitoring methods. Cutting-edge technological paradigms such as spatial multi-omics, AI-driven computational pathology, and multi-modal liquid biopsy are explored as feasible pathways for precise decoding and standardized assessment of TLSs functional states.

Results: Existing evidence highlights the differential impact of iTLSs (favorable outcomes, improved immunotherapy response) versus peritumoral TLSs (dysfunctional or pro-tumorigenic) in HCC. The regulation of TLSs is shown to be deeply intertwined with the liver's unique microenvironment, particularly CAFs and tryptophan metabolism. The analysis points to the potential for integrating advanced technologies to overcome current assessment and monitoring challenges, paving the way for a more precise understanding of TLSs functional states.

Conclusion: Addressing the functional paradox of TLSs based on spatial localization in HCC is crucial for guiding treatment. Overcoming current assessment and monitoring bottlenecks through the integration of spatial multi-omics, AI-driven computational pathology, and multi-modal liquid biopsy offers a pathway for precise decoding and standardized evaluation of TLSs functional states. Future research should shift towards active therapeutic interventions targeting TLSs function and location to optimize personalized immunotherapy strategies for HCC patients.