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Bronchoalveolar Lavage of Murine Lungs to Analyze Inflammatory Cell Infiltration
Published on: May 4, 2017
Single-cell transcriptome sequencing reveals the immune microenvironment in bronchoalveolar lavage fluid of
Linpeng Zheng1, Fenglin Lin1, Dingqin Cai1,2
1Cancer Institute, Xinqiao Hospital, Army Medical University, Chongqing, China.
Background And Objectives:
Immune checkpoint inhibitors (ICIs) bring cancer patients tumor control and survival benefits, yet they also trigger immune-related adverse effects (irAEs), notably checkpoint inhibitor-related pneumonitis (CIP), affecting about 5% of patients among whom 1-2% experiencing severe grade 3 or higher pneumonitis. Current research points to potential links with T cell subset dysfunction and autoantibody increase, but the specific mechanisms underlying different grades of CIP are understudied.
Methods:
Herein, we employed single-cell RNA sequencing (scRNA-seq) on bronchoalveolar lavage fluid (BALF) from CIP patients across varying severity levels, aiming to elucidate underlying immune environment and mechanisms of CIP progression at cellular and molecular levels.
Findings:
Totally, 121,409 high qualified cells from BALF of 11 patients were annotated and categorized into five major cell types. Severe CIP (CIP-S) cases have a significant increase in the percentage of unreported epithelial cells in their bronchoalveolar lavage fluid compared with mild CIP (CIP-M) cases. These cells were defined as aberrant basaloid cells. They upregulated SOX9, increased the expression of CXCL3/5, recruited neutrophils, and activated the immune system. Additionally, macrophages in the CIP-S group had stronger antigen-presenting abilities and resulted in more CD8 + effective T cells infiltrated.
Conclusions:
Utilizing single-cell sequencing of BALF, we discovered an enriched population of aberrant basaloid cells in CIP-S patients, which had not been previously reported. Aberrant basaloid cells may upregulate SOX9 via CXCL3/5-CXCR2 to recruit and activate neutrophils, and further activate the immune system, resulting in CIP-S. This finding could identify new targets for stratified treatment of CIP patients, holding promise of a novel approach for clinical guidance.
Insights
Immune checkpoint inhibitors can cause severe pneumonitis. This study identified aberrant basaloid cells in severe cases, suggesting a new mechanism and potential therapeutic targets for this immune-related adverse effect.
Area of Science:
- Immunology
- Oncology
- Pulmonology
Background:
- Immune checkpoint inhibitors (ICIs) improve cancer outcomes but can cause immune-related adverse effects (irAEs), including checkpoint inhibitor-related pneumonitis (CIP).
- Severe CIP (grade 3+) affects 1-2% of patients, with underlying mechanisms for different severity grades remaining understudied.
- Existing research suggests links to T cell dysfunction and autoantibodies, but cellular and molecular drivers of CIP severity are unclear.
Purpose of the Study:
- To investigate the cellular and molecular mechanisms underlying different grades of checkpoint inhibitor-related pneumonitis (CIP).
- To identify novel cellular populations and pathways associated with severe CIP using single-cell RNA sequencing.
Main Methods:
- Single-cell RNA sequencing (scRNA-seq) was performed on bronchoalveolar lavage fluid (BALF) from patients with varying CIP severity.
- Analysis focused on identifying distinct cell types and their molecular profiles in mild CIP (CIP-M) versus severe CIP (CIP-S) cases.
Main Results:
- A significant increase in aberrant basaloid epithelial cells was observed in severe CIP (CIP-S) patients compared to mild CIP (CIP-M) patients.
- These aberrant basaloid cells upregulate SOX9 and CXCL3/5, potentially recruiting and activating neutrophils via the CXCL3/5-CXCR2 axis.
- Macrophages in CIP-S patients exhibited enhanced antigen-presenting capabilities, correlating with increased infiltration of CD8+ effective T cells.
Conclusions:
- A novel, enriched population of aberrant basaloid cells in severe CIP (CIP-S) patients was discovered using scRNA-seq of BALF.
- Aberrant basaloid cells may drive CIP-S pathogenesis by recruiting and activating neutrophils, further activating the immune system.
- These findings offer potential new targets for stratified treatment strategies in CIP patients, paving the way for improved clinical guidance.
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