Stress-driven reprogramming of plasmacytoid dendritic cells in intrahepatic cholangiocarcinoma defines a reversible targetable immunosuppressive state.

BACKGROUND

Plasmacytoid dendritic cells (pDCs) have been implicated in both restraining and promoting intrahepatic cholangiocarcinoma (iCCA), leaving their clinical relevance and therapeutic potential unresolved.

METHODS

Mendelian randomization was used to assess the causal association between circulating pDC levels and iCCA risk. Bulk and single-cell transcriptomic analyses were performed to characterize pDC-related programs and tumor-conditioned states, and multiplex immunofluorescence was used to define spatial distribution and clinical associations in iCCA tissues. To assess reversibility of stress-associated pDC features, IRE1α RNase activity was pharmacologically inhibited with 4µ8C under tumor-conditioned stress in vitro.

RESULTS

Genetically predicted higher circulating pDC levels were associated with lower iCCA risk, consistent with a systemic protective association. In bulk cohorts, higher expression of pDC markers (CLEC4C, NRP1, IL3RA) was associated with an immune-inflamed microenvironment and improved survival in early-stage disease. Single-cell analyses indicated that intratumoral pDCs acquired stress-associated transcriptional programs, including enrichment of endoplasmic reticulum stress and unfolded protein response pathways. In vitro, 4µ8C reduced IRE1α-dependent XBP1 splicing and partially restored type I interferon-linked activation and pDC immunogenic readouts under tumor-conditioned stress. Spatial profiling further showed that higher intratumoral CD303⁺IRF7⁺ pDC activation was associated with advanced stage and poorer overall survival, whereas higher activation in adjacent non-tumor tissues correlated with more favorable outcomes.

CONCLUSIONS

Together, these findings support a context-dependent, stress-associated pDC program in iCCA and provide a rationale for further evaluating the IRE1α-XBP1 stress axis as a potential approach to modulate pDC-associated immune states within the tumor microenvironment.