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Published on: January 3, 2013
Exosomal B7H3 drives immunosuppression and serves as a biomarker for PD-1 blockage response in head and neck squamous
Wen Wang1, Chulong Xie2,3, Juncong Luo1
1Department of Oncology, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai 519000, China.
Objective:
Patients with head and neck squamous cell carcinoma (HNSCC) display a remarkably low response rate to immune checkpoint inhibitor (ICI) therapy. Currently, there is an urgent unmet need for reliable non-invasive biomarkers capable of predicting clinical therapeutic outcomes. This study sought to elucidate the role of exosomal B7H3 in the HNSCC immune microenvironment and evaluate the potential utility of B7H3 as a predictive biomarker for ICI therapy.
Methods:
Exosomal B7H3 was characterized via transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA). The biological functions and regulatory mechanisms underlying exosomal B7H3 were explored using Western blot, ELISA, flow cytometry, and immunofluorescence staining. In vivo animal studies and immunohistochemical (IHC) analyses of clinical tissue specimens were further performed to verify the in vitro findings.
Results:
In the present study secretion of exosomal B7H3 was significantly elevated in HNSCC. Functional assays confirmed that HNSCC-derived exosomal B7H3 mediates robust immunosuppression both in vitro and in vivo. Notably, HNSCC cells exhibited a mutually exclusive pattern of B7H3 and PD-L1 expression. Specifically, high B7H3 expression was closely associated with resistance to anti-PD-1 therapy. A significant negative correlation was detected between circulating exosomal B7H3 and exosomal PD-L1 levels. Furthermore, HNSCC patients with high circulating exosomal B7H3 levels exhibited poorer responses to anti-PD-1 treatment compared to HNSCC patients with low exosomal B7H3 expression.
Conclusions:
The findings herein demonstrated that exosomal B7H3 exerts potent immunosuppressive effects and displays a mutually exclusive expression pattern with PD-L1, thereby contributing to anti-PD-1 immunotherapy resistance in HNSCC. These results provide a solid theoretical basis for using exosomal B7H3 as a non-invasive predictive biomarker and highlight a promising novel therapeutic target for HNSCC patients.
Insights
Elevated exosomal B7H3 in head and neck squamous cell carcinoma (HNSCC) drives immune suppression and predicts poor response to anti-PD-1 therapy. This finding supports exosomal B7H3 as a biomarker for immunotherapy outcomes.
Area of Science:
- Immunology
- Oncology
- Biomarker Discovery
Background:
- Head and neck squamous cell carcinoma (HNSCC) patients show low response rates to immune checkpoint inhibitor (ICI) therapy.
- There is a critical need for non-invasive biomarkers to predict treatment outcomes in HNSCC.
- Exosomal B7H3's role in the HNSCC immune microenvironment and its potential as a predictive biomarker for ICI therapy require investigation.
Purpose of the Study:
- To investigate the role of exosomal B7H3 in the HNSCC immune microenvironment.
- To evaluate exosomal B7H3 as a predictive biomarker for immune checkpoint inhibitor (ICI) therapy response in HNSCC.
- To understand the functional mechanisms of exosomal B7H3 in mediating immunosuppression.
Main Methods:
- Characterization of exosomal B7H3 using transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA).
- Exploration of biological functions and regulatory mechanisms via Western blot, ELISA, flow cytometry, and immunofluorescence staining.
- Validation through in vivo animal studies and immunohistochemical (IHC) analyses of clinical tissue specimens.
Main Results:
- Exosomal B7H3 secretion was significantly elevated in HNSCC, mediating potent immunosuppression in vitro and in vivo.
- A mutually exclusive expression pattern between B7H3 and PD-L1 was observed in HNSCC cells.
- High exosomal B7H3 levels correlated with resistance to anti-PD-1 therapy and poorer patient response.
Conclusions:
- Exosomal B7H3 contributes to anti-PD-1 immunotherapy resistance in HNSCC through immunosuppression and a mutually exclusive expression with PD-L1.
- Exosomal B7H3 serves as a promising non-invasive predictive biomarker for ICI therapy in HNSCC.
- Targeting exosomal B7H3 represents a potential novel therapeutic strategy for HNSCC patients.
