Effect of nasopharyngeal carcinoma-derived exosomes on human regulatory T cells

J Natl Cancer Inst. 2014 Dec 12;107(1):363. doi: 10.1093/jnci/dju363. Print 2015 Jan.

Abstract

Background: Regulatory T cells (Treg) and tumor-exosomes are thought to play a role in preventing the rejection of malignant cells in patients bearing nasopharyngeal carcinoma (NPC).

Methods: Treg recruitment by exosomes derived from NPC cell lines (C15/C17-Exo), exosomes isolated from NPC patients' plasma (Patient-Exo), and CCL20 were tested in vitro using Boyden chamber assays and in vivo using a xenograft SCID mouse model (n = 5), both in the presence and absence of anti-CCL20 monoclonal antibodies (mAb). Impact of these NPC exosomes (NPC-Exo) on Treg phenotype and function was determined using adapted assays (FACS, Q-PCR, ELISA, and MLR). Experiments were performed in comparison with exosomes derived from plasma of healthy donors (HD-Exo). The Student's t test was used for group comparisons. All statistical tests were two-sided.

Results: CCL20 allowed the intratumoral recruitment of human Treg. NPC-Exo also facilitated Treg recruitment (3.30 ± 0.34 fold increase, P < .001), which was statistically significantly inhibited (P < .001) by an anti-CCL20 blocking mAb. NPC-Exo also recruited conventional CD4(+)CD25(-) T cells and mediated their conversion into inhibitory CD4(+)CD25(high) cells. Moreover, NPC-Exo enhanced (P = .0048) the expansion of human Treg, inducing the generation of Tim3(Low) Treg with increased expression of CD25 and FOXP3. Finally, NPC-Exo induced an overexpression of cell markers associated with Treg phenotype, properties and recruitment capacity. For example, GZMB mean fold change was 21.45 ± 1.75 (P < .001). These results were consistent with a stronger suppression of responder cells' proliferation and the secretion of immunosuppressive cytokines (IL10, TGFB1).

Conclusion: Interactions between NPC-Exo and Treg represent a newly defined mechanism that may be involved in regulating peripheral tolerance by tumors and in supporting immune evasion in human NPC.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blotting, Western
  • CD4-Positive T-Lymphocytes / immunology
  • CD4-Positive T-Lymphocytes / metabolism
  • Carcinoma / immunology
  • Carcinoma / metabolism*
  • Cell Line, Tumor
  • Cell Proliferation
  • Chemokine CCL20 / metabolism
  • Exosomes / immunology
  • Exosomes / metabolism*
  • Flow Cytometry
  • Forkhead Transcription Factors / metabolism
  • Gene Expression Regulation, Neoplastic
  • Heterografts
  • Humans
  • Interleukin-10 / immunology
  • Interleukin-2 Receptor alpha Subunit / metabolism
  • Mice
  • Mice, SCID
  • Nasopharyngeal Neoplasms / immunology
  • Nasopharyngeal Neoplasms / metabolism*
  • Real-Time Polymerase Chain Reaction
  • T-Lymphocytes / immunology
  • T-Lymphocytes / metabolism
  • T-Lymphocytes, Regulatory / immunology*
  • T-Lymphocytes, Regulatory / metabolism*
  • Transforming Growth Factor beta1 / immunology

Substances

  • CCL20 protein, human
  • CCL20 protein, mouse
  • Chemokine CCL20
  • FOXP3 protein, human
  • Forkhead Transcription Factors
  • Foxp3 protein, mouse
  • IL10 protein, human
  • IL10 protein, mouse
  • IL2RA protein, human
  • Interleukin-2 Receptor alpha Subunit
  • Transforming Growth Factor beta1
  • Interleukin-10