Extracellular vesicles containing PD-L1 contribute to CD8+ T-cell immune suppression and predict poor outcomes in
Xiaoyan Dou1, Yan Hua1, Zhaowu Chen1
1Department of Laboratory Diagnostics, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.
Abstract:
Programmed death ligand-1 (PD-L1) is expressed on the surface of tumor cells and binds to programmed cell death protein-1 (PD1) on the surface of T cells, leading to cancer immune evasion via inhibition of T-cell function. One of the characteristics of small cell lung cancer (SCLC) is its ineffective anti-tumor immune response and highly immunosuppressive status in the tumor microenvironment. SCLC cells have been shown to generate extracellular vesicles (EVs), which may play an important role in tumor progression. We thus hypothesized that SCLC EVs may be important mediators of immunosuppression and that PD-L1 could play a role. Herein, we showed that PD-L1 was expressed on the surface of SCLC-derived EVs, with the potential to directly bind to PD1. Experimentally, we further showed that EVs secreted by SCLC cells can inhibit CD8+ T-cell activation and cytokine production in vitro in response to T-cell receptor stimulation. Importantly, an anti-PD-L1 blocking antibody significantly reversed the EV-mediated inhibition of CD8+ T-cell activation. Furthermore, we performed a retrospective study of patients with SCLC to determine the prognostic value of PD-L1 harvested from plasm circulating EVs. The results showed that EVs containing PD-L1 was an independent prognostic factor and significantly correlated with progression-free survival. Together, these results indicate that EVs containing PD-L1 can be served as a diagnostic biomarker for predicting the effectiveness of therapy, as well as a new strategy to enhance T-cell-mediated immunotherapy against SCLC cancers.
Insights
Small cell lung cancer (SCLC) extracellular vesicles (EVs) carrying programmed death ligand-1 (PD-L1) suppress T-cell activity. PD-L1 on EVs is a prognostic biomarker and a therapeutic target for SCLC immunotherapy.
Area of Science:
- Immunology
- Oncology
- Cell Biology
Background:
- Small cell lung cancer (SCLC) exhibits an immunosuppressive tumor microenvironment, hindering effective anti-tumor immunity.
- Tumor cells, including SCLC, release extracellular vesicles (EVs) that can influence tumor progression and immune evasion.
- Programmed death ligand-1 (PD-L1) binding to programmed cell death protein-1 (PD1) inhibits T-cell function, contributing to cancer immune evasion.
Purpose of the Study:
- To investigate the role of PD-L1 on SCLC-derived EVs in immune suppression.
- To determine if PD-L1-expressing EVs are a prognostic biomarker in SCLC patients.
- To explore the potential of targeting PD-L1 on EVs for SCLC immunotherapy.
Main Methods:
- Characterization of PD-L1 expression on SCLC-derived EVs.
- In vitro assessment of SCLC EV effects on CD8+ T-cell activation and cytokine production.
- Evaluation of anti-PD-L1 blocking antibody efficacy in reversing EV-mediated T-cell inhibition.
- Retrospective analysis of PD-L1 levels in circulating EVs from SCLC patients and correlation with progression-free survival.
Main Results:
- PD-L1 was confirmed on the surface of SCLC-derived EVs, capable of binding to PD1.
- SCLC EVs inhibited CD8+ T-cell activation and cytokine production in vitro.
- Anti-PD-L1 antibody treatment reversed the immunosuppressive effects of SCLC EVs on T-cells.
- Elevated PD-L1 levels in circulating EVs correlated significantly with poorer progression-free survival in SCLC patients.
Conclusions:
- SCLC-derived EVs carrying PD-L1 contribute to immune suppression by inhibiting T-cell function.
- PD-L1 on circulating EVs serves as an independent prognostic biomarker for SCLC.
- Targeting PD-L1 on EVs represents a potential therapeutic strategy to enhance T-cell-mediated immunotherapy for SCLC.
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