MicroRNA regulation in human CD8+ T cell subsets--cytokine exposure alone drives miR-146a expression

J Transl Med. 2014 Oct 21;12:292. doi: 10.1186/s12967-014-0292-0.

Abstract

Background: microRNAs (miRNAs) are emerging as key regulators of the immune system, but their role in CD8+ T cell differentiation is not well explored. Some evidence suggests that signals from cell surface receptors influence the expression of miRNAs in CD8+ T cells, and may have consequent effects on cell phenotype and function. We set out to investigate whether common gamma chain cytokines modulated human CD8+ T cell expression of miR-146a, which previous studies have associated with different stages of CD8+ differentiation. We also investigated how changes in miR-146a related to other miRNAs that alter with CD8+ differentiation status.

Methods: We treated human CD8+ T cells with the cytokines IL-2, IL-7 or IL-15 either at rest or after stimulation with anti-CD3 and anti-CD28. For some experiments we also purified human CD8+ T cell subsets ex vivo. Flow cytometry was used in parallel to assess cell surface memory marker expression. Total RNA from these cells was subjected to microarray analysis and real-time PCR for miRNA expression. Nucleofection studies were performed to assess potential mRNA targets of miR-146a.

Results: We find that miR-146a is up-regulated in naïve CD8+ T cells exposed to IL-2 or IL-15, even in the absence of an activating T cell receptor stimulus, but not when IL-7 is also present. miR-146a expression correlates with a memory phenotype in both ex vivo and in vitro cultured cells although in our hands overexpression of miR-146a was not sufficient alone to drive a full memory phenotype. In ex vivo analysis, miR-146a was one of a small number of miRNAs that was differentially expressed between naïve and memory CD8+ T cells.

Conclusions: miR-146a is emerging as a critical regulator of immune system. Our data shows that miR-146a expression is strongly influenced by the cytokine milieu even in the absence of a T cell receptor stimulus. Our results have implications for studies designed to assess the function of miR-146a, help to define a fingerprint of miRNA expression in CD8+ T cell subsets and may be useful when designing optimal protocols for T cell expansion as efficacy of T cell immunotherapy is correlated with an 'early' memory phenotype.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antigens / metabolism
  • CD8-Positive T-Lymphocytes / drug effects
  • CD8-Positive T-Lymphocytes / metabolism*
  • Cytokines / pharmacology*
  • Fas-Associated Death Domain Protein / metabolism
  • Gene Expression Profiling
  • Gene Expression Regulation / drug effects*
  • Humans
  • Immunologic Memory
  • Interleukin-15 / pharmacology
  • Interleukin-2 / pharmacology
  • Interleukin-7 / pharmacology
  • MicroRNAs / genetics*
  • MicroRNAs / metabolism
  • Phenotype
  • Receptors, Antigen, T-Cell / metabolism
  • Receptors, CCR7 / metabolism
  • T-Lymphocyte Subsets / drug effects
  • T-Lymphocyte Subsets / metabolism*
  • TNF Receptor-Associated Factor 6 / metabolism
  • Up-Regulation / drug effects

Substances

  • Antigens
  • CCR7 protein, human
  • Cytokines
  • FADD protein, human
  • Fas-Associated Death Domain Protein
  • Interleukin-15
  • Interleukin-2
  • Interleukin-7
  • MIRN146 microRNA, human
  • MicroRNAs
  • Receptors, Antigen, T-Cell
  • Receptors, CCR7
  • TNF Receptor-Associated Factor 6