Altered phenotypic and metabolic characteristics of FOXP3⁺CD3⁺CD56⁺ natural killer T (NKT)-like cells in human malignant pleural effusion

ABSTRACT

Malignant pleural effusion (MPE) is a functional ‘cold’ tumor microenvironment in which the antitumor activity of CD8⁺ T cells and natural killer T (NKT)-like cells is suppressed and the function of regulatory T (T_reg) cells is enhanced. Using flow cytometry and immunofluorescence staining, we detected a distinct subset of NKT-like cells expressing FOXP3 in MPE. Through single-cell RNA sequencing (scRNA-seq) analysis, we found that the glycolysis pathway and pyruvate metabolism were highly activated in FOXP3⁺ NKT-like cells. Similar to T_reg cells, FOXP3⁺ NKT-like cells highly expressed monocarboxylate transporter 1 (MCT1) and lactate dehydrogenase B to uptake and utilize lactate, thereby maintaining their immunosuppressive function and hyperlactylation in MPE. Furthermore, we found that MCT1 small molecule inhibitor 7ACC2 significantly reduced FOXP3 expression and histone lactylation levels in NKT-like cells in vitro. In conclusion, we reveal for the first time the altered phenotypic and metabolic features of FOXP3⁺ NKT-like cells in human MPE.

Graphical Abstract

KEYWORDS:

• Malignant pleural effusion
• NKT-like cell
• FOXP3
• MCT1
• lactylation
• scRNA-seq

Acknowledgments

We would like to thank Prof. Weng, Xiu-Fang and Dr. Cheng, Xue for the experimental instructions.

Disclosure statement

We declare no competing interests.

Author contributions

Concept and design: ZQ, WZH, PWB; experiments: WZH, ZP; data collection: WSX, ZSY, XX, NYR, XQQ, WHL; data analysis and interpretation: WZH, PWB; manuscript writing: WZH, ZQ. All authors approve publishing the final manuscript.

Data availability statement

The single-cell RNA sequencing data are available in Gene Expression Omnibus database (GSE99254 and GSE185058).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/2162402X.2022.2160558

Ethics statement

The trial was conducted in accordance with the Declaration of Helsinki (as revised in 2013). This study was approved by the ethics committee of Union Hospital, Tongji Medical College, Huazhong University of Science and Technology (2019-S809). Informed consent was given by all patients.

Additional information

Funding

This work was supported by grants from the National Natural Science Foundation of China (No. 81973990 and No. 82170105).