MiR-16 regulates mouse peritoneal macrophage polarization and affects T-cell activation

J Cell Mol Med. 2016 Oct;20(10):1898-907. doi: 10.1111/jcmm.12882. Epub 2016 May 31.

Abstract

MiR-16 is a tumour suppressor that is down-regulated in certain human cancers. However, little is known on its activity in other cell types. In this study, we examined the biological significance and underlying mechanisms of miR-16 on macrophage polarization and subsequent T-cell activation. Mouse peritoneal macrophages were isolated and induced to undergo either M1 polarization with 100 ng/ml of interferon-γ and 20 ng/ml of lipopolysaccharide, or M2 polarization with 20 ng/ml of interleukin (IL)-4. The identity of polarized macrophages was determined by profiling cell-surface markers by flow cytometry and cytokine production by ELISA. Macrophages were infected with lentivirus-expressing miR-16 to assess the effects of miR-16. Effects on macrophage-T cell interactions were analysed by co-culturing purified CD4(+) T cells with miR-16-expressing peritoneal macrophages, and measuring activation marker CD69 by flow cytometry and cytokine secretion by ELISA. Bioinformatics analysis was applied to search for potential miR-16 targets and understand its underlying mechanisms. MiR-16-induced M1 differentiation of mouse peritoneal macrophages from either the basal M0- or M2-polarized state is indicated by the significant up-regulation of M1 marker CD16/32, repression of M2 marker CD206 and Dectin-1, and increased secretion of M1 cytokine IL-12 and nitric oxide. Consistently, miR-16-expressing macrophages stimulate the activation of purified CD4(+) T cells. Mechanistically, miR-16 significantly down-regulates the expression of PD-L1, a critical immune suppressor that controls macrophage-T cell interaction and T-cell activation. MiR-16 plays an important role in shifting macrophage polarization from M2 to M1 status, and functionally activating CD4(+) T cells. This effect is potentially mediated through the down-regulation of immune suppressor PD-L1.

Keywords: CD4+ T cells; PD-L1; macrophage polarization; miR-16.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • B7-H1 Antigen / metabolism
  • Base Sequence
  • CD4-Positive T-Lymphocytes / drug effects
  • CD4-Positive T-Lymphocytes / metabolism
  • Cell Polarity* / drug effects
  • Cells, Cultured
  • Cytokines / pharmacology
  • Lymphocyte Activation / drug effects
  • Lymphocyte Activation / immunology*
  • Macrophages, Peritoneal / cytology*
  • Macrophages, Peritoneal / drug effects
  • Macrophages, Peritoneal / metabolism*
  • Mice, Inbred C57BL
  • MicroRNAs / genetics
  • MicroRNAs / metabolism*
  • Phenotype
  • T-Lymphocytes / immunology*

Substances

  • B7-H1 Antigen
  • Cd274 protein, mouse
  • Cytokines
  • MicroRNAs
  • Mirn16 microRNA, mouse