Balance between activating NKG2D, DNAM-1, NKp44 and NKp46 and inhibitory CD94/NKG2A receptors determine natural killer degranulation towards rheumatoid arthritis synovial fibroblasts

Immunology. 2014 Aug;142(4):581-93. doi: 10.1111/imm.12271.

Abstract

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation and synovial hyperplasia leading to progressive joint destruction. Fibroblast-like synoviocytes (FLS) are central components of the aggressive, tumour-like synovial structure termed pannus, which invades the joint space and cartilage. A distinct natural killer (NK) cell subset expressing the inhibitory CD94/NKG2A receptor is present in RA synovial fluid. Little is known about possible cellular interactions between RA-FLS and NK cells. We used cultured RA-FLS and the human NK cell line Nishi, of which the latter expresses an NK receptor repertoire similar to that of NK cells in RA synovial fluid, as an in vitro model system of RA-FLS/NK cell cross-talk. We show that RA-FLS express numerous ligands for both activating and inhibitory NK cell receptors, and stimulate degranulation of Nishi cells. We found that NKG2D, DNAM-1, NKp46 and NKp44 are the key activating receptors involved in Nishi cell degranulation towards RA-FLS. Moreover, blockade of the interaction between CD94/NKG2A and its ligand HLA-E expressed on RA-FLS further enhanced Nishi cell degranulation in co-culture with RA-FLS. Using cultured RA-FLS and the human NK cell line Nishi as an in vitro model system of RA-FLS/NK cell cross-talk, our results suggest that cell-mediated cytotoxicity of RA-FLS may be one mechanism by which NK cells influence local joint inflammation in RA.

Keywords: CD94/NKG2A; NKG2D; fibroblast-like synoviocytes; natural killer cytotoxicity.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antigens, Differentiation, T-Lymphocyte / immunology*
  • Antigens, Differentiation, T-Lymphocyte / metabolism
  • Arthritis, Rheumatoid / immunology*
  • Arthritis, Rheumatoid / metabolism
  • Arthritis, Rheumatoid / pathology
  • Cell Degranulation / immunology*
  • Cell Line
  • Female
  • Fibroblasts / immunology*
  • Fibroblasts / metabolism
  • Fibroblasts / pathology
  • Histocompatibility Antigens Class I / biosynthesis
  • Histocompatibility Antigens Class I / immunology
  • Humans
  • Killer Cells, Natural / immunology*
  • Killer Cells, Natural / metabolism
  • Killer Cells, Natural / pathology
  • Male
  • NK Cell Lectin-Like Receptor Subfamily C / immunology*
  • NK Cell Lectin-Like Receptor Subfamily C / metabolism
  • NK Cell Lectin-Like Receptor Subfamily D / immunology*
  • NK Cell Lectin-Like Receptor Subfamily D / metabolism
  • NK Cell Lectin-Like Receptor Subfamily K / immunology*
  • NK Cell Lectin-Like Receptor Subfamily K / metabolism
  • Natural Cytotoxicity Triggering Receptor 1 / immunology*
  • Natural Cytotoxicity Triggering Receptor 1 / metabolism
  • Natural Cytotoxicity Triggering Receptor 2 / immunology*
  • Natural Cytotoxicity Triggering Receptor 2 / metabolism
  • Synovial Membrane / immunology*
  • Synovial Membrane / metabolism
  • Synovial Membrane / pathology
  • Up-Regulation / immunology

Substances

  • Antigens, Differentiation, T-Lymphocyte
  • CD226 antigen
  • HLA-E antigen
  • Histocompatibility Antigens Class I
  • KLRD1 protein, human
  • KLRK1 protein, human
  • NCR1 protein, human
  • NCR2 protein, human
  • NK Cell Lectin-Like Receptor Subfamily C
  • NK Cell Lectin-Like Receptor Subfamily D
  • NK Cell Lectin-Like Receptor Subfamily K
  • Natural Cytotoxicity Triggering Receptor 1
  • Natural Cytotoxicity Triggering Receptor 2