Crosstalk between SPP1+ macrophages and ITGA5+ fibroblasts promotes hepatocellular carcinoma metastasis.

[BACKGROUND] Hepatocellular carcinoma (HCC) develops from chronic inflammatory conditions to malignancy, with the immune microenvironment playing a significant role in this progression. However, the changes in the dynamic immune microenvironment during the transition from hepatitis to HCC remain poorly understood. Systematic analysis of stage-specific immune microenvironment alterations is essential for identifying therapeutic targets and creating precision strategies for HCC.

[METHODS] Using single-cell RNA sequencing (scRNA-seq), we created dynamic transcriptome maps of the immune microenvironment across healthy liver, hepatitis, cirrhosis, and HCC stages. Cell-cell communication, trajectory, and enrichment analyses were utilized to characterize relationships between clusters. TCGA-LIHC data were used to validate gene expression and its prognosis. The spatial distribution of ligand-receptor complexes in HCC was confirmed by spatial transcriptomics and multiplexed immunofluorescence. The effects of the tumor microenvironment on cancer cell behavior were examined using co-immunoprecipitation and cell co-culture assays. Finally, the impact of the immune microenvironment on in vivo tumor progression was evaluated using a mouse transplantation model.

[RESULTS] We identified specific immune cell clusters across HCC progression and revealed significant correlations between the abundance of immune cells (macrophages, B cells)and fibroblasts with disease severity. Crosstalk between SPP1+ macrophages and ITGA5+ fibroblasts was observed explicitly in HCC. In vitro and in vivo data demonstrated that the SPP1-ITGA5 interaction triggered the secretion of MMP2 by fibroblasts, thereby promoting malignant progression in HCC.

[CONCLUSIONS] We present a dynamic transcriptional profile of immune microenvironment evolution during HCC development, aiding in the refinement of diagnostics and the optimization of therapy strategies.