BCL-2 expression promotes immunosuppression in chronic lymphocytic leukemia by enhancing regulatory T cell differentiation and cytotoxic T cell exhaustion

Lu Liu; Xianfeng Cheng; Hui Yang; Senlin Lian; Yuegen Jiang; Jinhua Liang; Xiao Chen; Suo Mo; Yu Shi; Sishu Zhao; Jianyong Li; Runqiu Jiang; Dong-Hua Yang; Yujie Wu

doi:10.1186/s12943-022-01516-w

BCL-2 expression promotes immunosuppression in chronic lymphocytic leukemia by enhancing regulatory T cell differentiation and cytotoxic T cell exhaustion

Mol Cancer. 2022 Feb 22;21(1):59. doi: 10.1186/s12943-022-01516-w.

Authors

Lu Liu^#^{1

2}, Xianfeng Cheng^#³, Hui Yang^#^{1

2}, Senlin Lian^{4

5

6}, Yuegen Jiang³, Jinhua Liang^{1

2}, Xiao Chen^{1

2}, Suo Mo³, Yu Shi^{1

2}, Sishu Zhao^{1

2}, Jianyong Li^{1

2}, Runqiu Jiang^{7

8

9}, Dong-Hua Yang¹⁰, Yujie Wu^{11

12}

Affiliations

¹ Department of Hematology, the First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, 210029, China.
² Key Laboratory of Hematology of Nanjing Medical University, Nanjing, 210029, China.
³ Department of Clinical laboratory, Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing, 210042, China.
⁴ Jiangsu Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, 210093, China.
⁵ State Key Laboratory of Pharmaceutical Biotechnology, Medical School, Nanjing University, Nanjing, 210093, China.
⁶ Department of Hepatobiliary Surgery, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, 210008, China.
⁷ Jiangsu Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, 210093, China. jiangrq@nju.edu.cn.
⁸ State Key Laboratory of Pharmaceutical Biotechnology, Medical School, Nanjing University, Nanjing, 210093, China. jiangrq@nju.edu.cn.
⁹ Department of Hepatobiliary Surgery, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, 210008, China. jiangrq@nju.edu.cn.
¹⁰ Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, Queens, NY, 11439, USA. yangd1@stjohns.edu.
¹¹ Department of Hematology, the First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, 210029, China. wuyujie123456@163.com.
¹² Key Laboratory of Hematology of Nanjing Medical University, Nanjing, 210029, China. wuyujie123456@163.com.

^# Contributed equally.

Abstract

Background: Chronic lymphocytic leukemia (CLL) results in increased susceptibility to infections. T cell dysfunction is not associated with CLL in all patients; therefore, it is important to identify CLL patients with T cell defects. The role of B-cell lymphoma-2 (BCL-2) in CLL has been explored; however, few studies have examined its role in T cells in CLL patients. Herein, we have investigated the regulatory role of BCL-2 in T cells in the CLL tumor microenvironment.

Methods: The expression of BCL-2 in T cells was evaluated using flow cytometry. The regulatory roles of BCL-2 were investigated using single-cell RNA sequencing (scRNA-seq) and verified using multi-parameter flow cytometry on CD4 and CD8 T cells. The clinical features of BCL-2 expression in T cells in CLL were also explored.

Results: We found a significant increase in BCL-2 expression in the T cells of CLL patients (n = 266). Single cell RNA sequencing (scRNA-seq) indicated that BCL-2⁺CD4⁺ T cells had the gene signature of increased regulatory T cells (Treg); BCL-2⁺CD8⁺ T cells showed the gene signature of exhausted cytotoxic T lymphocytes (CTL); and increased expression of BCL-2 was associated with T cell activation and cellular adhesion. The results from scRNA-seq were verified in peripheral T cells from 70 patients with CLL, wherein BCL-2⁺CD4⁺ T cells were enriched with Tregs and had higher expression of interleukin-10 and transforming growth factor-β than BCL-2^-CD4⁺ T cells. BCL-2 expression in CD8⁺T cells was associated with exhausted cells (PD-1⁺Tim-3⁺) and weak expression of granzyme B and perforin. T cell-associated cytokine profiling revealed a negative association between BCL-2⁺ T cells and T cell activation. Decreased frequencies and recovery functions of BCL-2⁺T cells were observed in CLL patients in complete remission after treatment with venetoclax.

Conclusion: BCL-2 expression in the T cells of CLL patients is associated with immunosuppression via promotion of Treg abundance and CTL exhaustion.

Keywords: BCL-2; Chronic lymphocytic leukemia; Single-cell RNA sequencing; T cells.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Cell Differentiation / immunology
Humans
Immunosuppression Therapy
Leukemia, Lymphocytic, Chronic, B-Cell* / immunology
Leukemia, Lymphocytic, Chronic, B-Cell* / metabolism
Proto-Oncogene Proteins c-bcl-2* / biosynthesis
Proto-Oncogene Proteins c-bcl-2* / immunology
T-Lymphocytes, Cytotoxic* / immunology
T-Lymphocytes, Cytotoxic* / metabolism
Tumor Microenvironment

Substances

BCL2 protein, human
Proto-Oncogene Proteins c-bcl-2