Impaired calcium mobilization in natural killer cells from chronic fatigue syndrome/myalgic encephalomyelitis patients is associated with transient receptor potential melastatin 3 ion channels

Clin Exp Immunol. 2017 Feb;187(2):284-293. doi: 10.1111/cei.12882. Epub 2016 Nov 23.

Abstract

Transient receptor potential melastatin subfamily 3 (TRPM3) ion channels play a role in calcium (Ca2+ ) cell signalling. Reduced TRPM3 protein expression has been identified in chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) patients. However, the significance of TRPM3 and association with intracellular Ca2+ mobilization has yet to be determined. Fifteen CFS/ME patients (mean age 48·82 ± 9·83 years) and 25 healthy controls (mean age 39·2 ± 12·12 years) were examined. Isolated natural killer (NK) cells were labelled with fluorescent antibodies to determine TRPM3, CD107a and CD69 receptors on CD56dim CD16+ NK cells and CD56bright CD16dim/- NK cells. Ca2+ flux and NK cytotoxicity activity was measured under various stimulants, including pregnenolone sulphate (PregS), thapsigargin (TG), 2-aminoethoxydiphenyl borate (2APB) and ionomycin. Unstimulated CD56bright CD16dim/- NK cells showed significantly reduced TRPM3 receptors in CFS/ME compared with healthy controls (HC). Ca2+ flux showed no significant difference between groups. Moreover, PregS-stimulated CD56bright CD16dim/- NK cells showed a significant increase in Ca2+ flux in CFS/ME patients compared with HC. By comparison, unstimulated CD56dim CD16+ NK cells showed no significant difference in both Ca2+ flux and TRPM3 expression. PregS-stimulated CD56dim CD16+ NK cells increased TRPM3 expression significantly in CFS/ME, but this was not associated with a significant increase in Ca2+ flux. Furthermore, TG-stimulated CD56dim CD16+ NK cells increased K562 cell lysis prior to PregS stimulation in CFS/ME patients compared with HC. Differential expression of TRPM3 and Ca2+ flux between NK cell subtypes may provide evidence for their role in the pathomechanism involving NK cell cytotoxicity activity in CFS/ME.

Keywords: cell surface molecules; inhibitory/activating receptors; natural killer cells.

MeSH terms

  • Adult
  • CD56 Antigen / metabolism
  • Calcium Signaling
  • Cytotoxicity, Immunologic
  • Fatigue Syndrome, Chronic / genetics*
  • Female
  • Humans
  • K562 Cells
  • Killer Cells, Natural / physiology*
  • Male
  • Middle Aged
  • Pregnenolone / metabolism
  • Receptors, IgG / metabolism
  • TRPM Cation Channels / genetics*
  • Thapsigargin / metabolism

Substances

  • CD56 Antigen
  • Receptors, IgG
  • TRPM Cation Channels
  • TRPM3 protein, human
  • pregnenolone sulfate
  • Thapsigargin
  • Pregnenolone