Topographic mapping of the HCC microenvironment reveals an antitumor axis between CCL19+ fibroblasts and CXCR3+ B Cells

The tumor microenvironment (TME) plays a critical role in hepatocellular carcinoma (HCC) progression, yet the spatial interactions among its cellular components remain poorly understood. This study aimed to map the spatial gene expression signatures of primary HCC with or without portal vein tumor thrombus (PVTT) and to investigate the spatial crosstalk between cancer-associated fibroblasts (CAFs) and B cells, as well as its clinical relevance. Spatial transcriptomic sequencing was performed on primary HCC tissues from patients with or without PVTT to characterize regional heterogeneity and identify potential CAF-B cell interactions. Findings were validated using public single-cell RNA-seq datasets and a subcutaneous H22 hepatoma mouse model. We further established a fully murine CAF-derived CCL19 validation model by co-inoculating Hepa1-6 cells with JS1-Vector or JS1-mCCL19 fibroblasts, with or without anti-mouse CXCR3 blockade. Multiplex immunofluorescence staining and multi-center clinical cohorts were employed to assess the prognostic value of the identified interaction axis. Stromal and border regions of non-metastatic HCC exhibited heightened immune activity and enrichment of tertiary lymphoid structures. Spatial transcriptomics revealed co-localization of CAFs and B cells, with cell communication analysis identifying the CCL19–CXCR3 axis as a key mediator. In vivo, CAF-derived CCL19 promoted B cell infiltration and suppressed tumor growth in a CXCR3-dependent manner. In the JS1-mCCL19 model, fibroblast-derived CCL19 significantly inhibited tumor growth and increased tumor-infiltrating B cells, whereas CXCR3 blockade partly reversed both effects. Clinically, CCL19⁺ CAFs and CXCR3⁺ B cells infiltration were positively correlated, and their high co-infiltration predicted significantly longer overall survival in HCC patients. This study uncovers a novel spatial immunoregulatory module in which CAFs recruit CXCR3⁺ B cells via CCL19 to restrain HCC progression. These findings provide new insights into TME architecture and offer potential prognostic biomarkers and therapeutic targets for HCC.