Induction of dendritic cell-mediated T-cell activation by modified but not native low-density lipoprotein in humans and inhibition by annexin a5: involvement of heat shock proteins

Arterioscler Thromb Vasc Biol. 2015 Jan;35(1):197-205. doi: 10.1161/ATVBAHA.114.304342. Epub 2014 Nov 13.

Abstract

Objective: Atherosclerosis is an inflammatory disease, where activated immunocompetent cells, including dendritic cells (DCs) and T cells are abundant in plaques. Low-density lipoprotein modified either by oxidation (oxLDL) or by human group X-secreted phospholipase A2 (LDLx) and heat shock proteins (HSP), especially HSP60 and 90, have been implicated in atherosclerosis. We previously reported that Annexin A5 inhibits inflammatory effects of phospholipids, decreases vascular inflammation and improves vascular function in apolipoprotein E(-/-) mice. Here, we focus on the LDLx effects on human DCs and T cells.

Approach and results: Human DCs were differentiated from peripheral blood monocytes, stimulated by oxLDL or LDLx. Naive autologous T cells were cocultured with pretreated DCs. oxLDL and LDLx, in contrast to LDL, induced DC-activation and T-cell proliferation. T cells exposed to LDLx-treated DCs produced interferon-γ, interleukin (IL)-17 but not IL-4 and IL-10. Annexin A5 abrogated LDLx effects on DCs and T cells and increased production of transforming growth factor-β and IL-10. Furthermore, IL-10 producing T cells suppressed primary T-cell activation via soluble IL-10, transforming growth factor-β, and cell-cell contact. Lentiviral-mediated shRNA knock-down HSP60 and 90 in DCs attenuated the effect of LDLx on DCs and subsequent T-cell proliferation. Experiments on DC and T cells derived from carotid atherosclerotic plaques gave similar results.

Conclusions: Our data show that modified forms of LDL such as LDLx but not native LDL activate human T cells through DCs. HSP60 and 90 contribute to such T-cell activation. Annexin A5 promotes induction of regulatory T cells and is potentially interesting as a therapeutic agent.

Keywords: LDL cholesterol; T cells; annexin A5; atherosclerosis; heat shock proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Annexin A5 / metabolism*
  • Carotid Artery Diseases / immunology
  • Carotid Artery Diseases / metabolism
  • Carotid Artery Diseases / pathology
  • Cell Communication*
  • Cell Differentiation
  • Cell Proliferation
  • Cells, Cultured
  • Chaperonin 60 / genetics
  • Chaperonin 60 / metabolism*
  • Coculture Techniques
  • Cytokines / metabolism
  • Dendritic Cells / immunology
  • Dendritic Cells / metabolism*
  • Group X Phospholipases A2 / metabolism
  • HSP90 Heat-Shock Proteins / genetics
  • HSP90 Heat-Shock Proteins / metabolism*
  • Humans
  • Inflammation Mediators / metabolism
  • Lipoproteins, LDL / metabolism*
  • Lymphocyte Activation*
  • Mitochondrial Proteins / genetics
  • Mitochondrial Proteins / metabolism*
  • Plaque, Atherosclerotic
  • RNA Interference
  • Signal Transduction
  • T-Lymphocyte Subsets / immunology
  • T-Lymphocyte Subsets / metabolism*
  • Transfection

Substances

  • Annexin A5
  • Chaperonin 60
  • Cytokines
  • HSP90 Heat-Shock Proteins
  • HSPD1 protein, human
  • Inflammation Mediators
  • Lipoproteins, LDL
  • Mitochondrial Proteins
  • oxidized low density lipoprotein
  • Group X Phospholipases A2