Relevance of chemokines in mobilizing γδ T cells in the biliary tract cancer microenvironment: potential for γδ T-cell–based adoptive cell therapy

Objective: Biliary tract cancer (BTC) has a poor prognosis with limited therapeutic options. γδ T cells represent an MHC-independent immune cell population; however, their therapeutic efficacy in solid tumors is constrained by insufficient tumor infiltration. Chemokine-mediated trafficking is fundamental to T lymphocyte recruitment; however, the chemokine landscape of the BTC tumor microenvironment (TME) remains uncharacterized. Using single-cell RNA sequencing of BTC tissues, we delineated chemokine ligand expression patterns, stratified chemokine producers by lineage, assessed γδ T-cell recruitment mechanisms, and identified chemokine-mediated immune escape.

Methods: We analyzed single-cell RNA sequencing data from 3 independent GEO cohorts (GSE210066, GSE201425, and GSE213452; 19 patients) to comprehensively delineate γδ T-cell mobilization-related chemokine expression across the BTC TME using the Seurat v5.0 pipeline in R.

Results: Analysis identified a multiaxis chemokine profile within the BTC TME. High expression of CCL5, CCL4, and CCL3 established predominant CCR5-mediated recruitment axes supporting Vγ9Vδ2 T-cell infiltration, whereas CCL2 and modest CXCL8 supported CCR2+ and CXCR1+ Vδ1 T-cell recruitment. Notably, CXCL16 expression supported epithelial γδ T-cell homing through CXCR6. However, critical deficiencies in CXCL9 and CXCL10 suppress the IFN-γ-driven immunity. Paradoxically, chemokine axes supporting γδ T-cell recruitment (CCL2-CCR2, CXCL8-CXCR1, CXCL12-CXCR4) simultaneously recruit immunosuppressive populations, such as myeloid-derived suppressor cells (MDSCs), regulatory T cells (Tregs), and tumor-associated macrophages (TAMs).

Conclusion: Comprehensive single-cell analysis identified selective chemokine recruitment signatures supporting γδ T-cell infiltration but revealed paradoxical corecruitment of immunosuppressive populations. Patient stratification through chemokine profiling, combined with γδ T-cell enrichment and targeted chemokine antagonism, represents a rational therapeutic strategy.