Necroptosis-driven T cell activation promotes IL-6-mediated PD-L1 upregulation in cholangiocarcinoma cells: IL-6 gene signature as a biomarker for chemo-immunotherapy response.

BACKGROUND: Cholangiocarcinoma (CCA) is an aggressive malignancy with limited treatment options. Despite the approval of chemotherapy and immune checkpoint inhibitors (ICIs) in clinical practice, treatment outcomes remain poor, largely due to the poorly immunogenic tumor microenvironment associated with this type of carcinoma. Necroptosis, an inflammatory form of programmed cell death, has emerged as a promising therapeutic target for stimulating antitumor immunity. Our previous study linked necroptosis to increased CD8 + T cell infiltration and T cell-induced PD-L1 expression in CCA cells, suggesting its role in enhancing ICI efficacy. However, the underlying mechanisms by which necroptosis-activated T cells induce PD-L1 expression remain unclear. Here, we investigate how necroptosis in CCA cells influences T cell response, which subsequently promotes PD-L1 expression, thus providing insights for optimizing necroptosis-based therapies in combination with ICIs.

RESULTS: Conditioned medium from gemcitabine-induced necroptotic CCA cells triggers PBMC-derived T cell activation by upregulating the surface activation marker CD69 and promoting cytokine release, primarily IL-6 and IL-1β. This cytokine release subsequently induces PD-L1 expression in CCA cells via IL-6, as confirmed by IL-6 neutralizing antibodies. Furthermore, T cell killing assays demonstrated that pembrolizumab, an anti-PD-1 inhibitor, enhances T cell cytotoxicity against PD-L1-upregulated CCA cells. Additionally, bioinformatics analysis identified an IL-6 signaling-related gene signature associated with ICI responsiveness, suggesting potential biomarkers for personalized treatment strategies.

CONCLUSION: This study highlights that necroptosis shapes the tumor immune microenvironment by promoting T cell activation and IL-6-mediated PD-L1 upregulation in CCA cells. These findings support the integration of necroptosis-based therapies with ICIs as a sequential chemo-immunotherapy strategy. Additionally, the identified IL-6 signaling-related gene signature may serve as a biomarker for patient stratification and personalized treatment in CCA.