CD4⁺ T cells expressing latency-associated peptide and Foxp3 are an activated subgroup of regulatory T cells enriched in patients with colorectal cancer.

Jayashri Mahalingam,Po-Jung Su,Jy-Ming Chiang,Yung-Chang Lin,Yu-Yi Chu,Hsin-Yi Lai,Jian-He Fang,Ching-Tai Huang,Chun-Yen Lin,Derya Unutmaz

doi:10.1371/journal.pone.0108554

Jayashri Mahalingam, Po-Jung Su + Show 8 more

Open Access

https://doi.org/10.1371/journal.pone.0108554

Copy DOI

Journal: PloS one	Publication Date: Sep 30, 2014
Citations: 35	License type: CC BY 4.0

Affiliation: Chang Gung University, Chang Gung Memorial Hospital

Abstract

Latency-associated peptide (LAP) - expressing regulatory T cells (Tregs) are important for immunological self-tolerance and immune homeostasis. In order to investigate the role of LAP in human CD4+Foxp3+ Tregs, we designed a cross-sectional study that involved 42 colorectal cancer (CRC) patients. The phenotypes, cytokine-release patterns, and suppressive ability of Tregs isolated from peripheral blood and tumor tissues were analyzed. We found that the population of LAP-positive CD4+Foxp3+ Tregs significantly increased in peripheral blood and cancer tissues of CRC patients as compared to that in the peripheral blood and tissues of healthy subjects. Both LAP+ and LAP− Tregs had a similar effector/memory phenotype. However, LAP+ Tregs expressed more effector molecules, including tumor necrosis factor receptor II, granzyme B, perforin, Ki67, and CCR5, than their LAP− negative counterparts. The in vitro immunosuppressive activity of LAP+ Tregs, exerted via a transforming growth factor-β–mediated mechanism, was more potent than that of LAP− Tregs. Furthermore, the enrichment of LAP+ Treg population in peripheral blood mononuclear cells (PBMCs) of CRC patients correlated with cancer metastases. In conclusion, we found that LAP+ Foxp3+ CD4+ Treg cells represented an activated subgroup of Tregs having more potent regulatory activity in CRC patients. The increased frequency of LAP+ Tregs in PBMCs of CRC patients suggests their potential role in controlling immune response to cancer and presents LAP as a marker of tumor-specific Tregs in CRC patients.

Highlights

Immunosuppressive functions of a specialized subset of T cells are vital for immune regulation
The immunomodulatory function of activated or effector Tregs related to the expression of a variety of molecules such as chemokine receptors CCR6 and CCR5, cytotoxic T lymphocyte antigen-4 (CTLA-4), and tumor necrosis factor receptor (TNFR) II was investigated in chronic inflammatory diseases, graftversus-host disease, and tumors [8,9,10,11,12,13,14,15]
The reliability of Latency-associated peptide (LAP) staining was confirmed by isotype control monoclonal and recombinant LAP monoclonal antibodies. (Figure S1) The comparison between colorectal cancer (CRC) patients and healthy donors (HD) revealed that LAP expression in CD4+Foxp3+ T cells isolated from peripheral blood mononuclear cells (PBMCs) was significantly increased in cancer patients (CRC: 18.8%69.2% vs. HD: 7.8%63.3%; Fig. 1A and B)

Summary

Introduction

Immunosuppressive functions of a specialized subset of T cells are vital for immune regulation. Huehn et al were the first to demonstrate the existence of distinct subsets of Tregs, naıve Tregs and effector memory Tregs, based on the expression of CD103, a receptor of aE integrin that guides T cells to inflamed sites [7]. Sakaguchi et al further delineated the role of Foxp3+ CD4+ Tregs based on the expression of CD45RA and Foxp and divided CD4+ Foxp3+ Tregs into three phenotypically and functionally distinct subgroups, namely non-suppressive, resting, and activated Tregs; the latter are believed to act as suppressors of immune response and mediators of immune hemostasis [16]. Given the differential regulatory activity of human Tregs, it is necessary to separate Foxp3+ Tregs into functional subgroups and to target a specific Treg subpopulation in order to ensure successful immunotherapy

Methods

Results

Conclusion