title: Down-regulation of purinergic P2X7 receptor expression and intracellular calcium dysregulation in peripheral blood mononuclear cells of patients with amyotrophic lateral sclerosis.
abstract: BACKGROUND
  Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder associated with intracellular Ca(2+) dysregulation. The P2X receptor family is comprised of ligand-gated ion channels that respond to extracellular adenosine triphosphate (ATP) and increases permeability of calcium into the cell. The underlying mechanisms of purinergic signalling on peripheral blood mononuclear cells (PBMCs) in ALS remain unclear. Herein, we studied the expression of P2X4/P2X7 receptors and calcium homeostasis in blood cells of ALS patients.
  
  
  METHODS
  We used PBMCs from 42 ALS patients and 19 controls. Purinergic receptors P2X4 (P2X4R) and P2X7 (P2X7R) were examined using western blot analysis. The effect of exogenous ATP on intracellular Ca(2+) homeostasis in monocytes was measured using fluorimetry by Fura-2 on a single-cell level.
  
  
  RESULTS
  Western blot analysis revealed stable P2X4R expression in patients and controls. P2X7R expression was significantly reduced (p=0.012) in ALS patients. Repetitive long-term ATP stimulation caused a sustained decrease in Ca(2+) levels in the ALS group as measured by the area under the curve, peak amplitude and peak height.
  
  
  CONCLUSIONS
  These results confirm our hypothesis that Ca(2+) abnormalities in ALS are measurable in immune cells. These findings suggest that the reduction of P2X7 receptor expression on PBMCs leads to intracellular calcium dysregulation. Our study improves the understanding of ALS pathophysiology and proposes PBMCs as a non-invasive source to study ALS.
authors.affiliation: Hans Berger Department of Neurology, Jena University Hospital, Erlanger Allee 101, 07747 Jena, Germany.
authors.forename: Jingyu
authors.initials: J
authors.lastname: Liu
authors.affiliation: Hans Berger Department of Neurology, Jena University Hospital, Erlanger Allee 101, 07747 Jena, Germany. Electronic address: Tino.Prell@med.uni-jena.de.
authors.forename: Tino
authors.initials: T
authors.lastname: Prell
authors.affiliation: Hans Berger Department of Neurology, Jena University Hospital, Erlanger Allee 101, 07747 Jena, Germany.
authors.forename: Beatrice
authors.initials: B
authors.lastname: Stubendorff
authors.affiliation: Hans Berger Department of Neurology, Jena University Hospital, Erlanger Allee 101, 07747 Jena, Germany.
authors.forename: Silke
authors.initials: S
authors.lastname: Keiner
authors.affiliation: Hans Berger Department of Neurology, Jena University Hospital, Erlanger Allee 101, 07747 Jena, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Ringer
authors.affiliation: Hans Berger Department of Neurology, Jena University Hospital, Erlanger Allee 101, 07747 Jena, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Gunkel
authors.affiliation: Hans Berger Department of Neurology, Jena University Hospital, Erlanger Allee 101, 07747 Jena, Germany.
authors.forename: Vedrana
authors.initials: V
authors.lastname: Tadic
authors.affiliation: Hans Berger Department of Neurology, Jena University Hospital, Erlanger Allee 101, 07747 Jena, Germany.
authors.forename: Nadine
authors.initials: N
authors.lastname: Goldhammer
authors.affiliation: Hans Berger Department of Neurology, Jena University Hospital, Erlanger Allee 101, 07747 Jena, Germany.
authors.forename: Ayse
authors.initials: A
authors.lastname: Malci
authors.affiliation: Hans Berger Department of Neurology, Jena University Hospital, Erlanger Allee 101, 07747 Jena, Germany.
authors.forename: Otto W
authors.initials: OW
authors.lastname: Witte
authors.affiliation: Hans Berger Department of Neurology, Jena University Hospital, Erlanger Allee 101, 07747 Jena, Germany.
authors.forename: Julian
authors.initials: J
authors.lastname: Grosskreutz
mesh_terms: D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000097:blood* / Q000378:metabolism*; D020013:Calcium Signaling; D015536:Down-Regulation; D005260:Female; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D058848:Receptors, Purinergic P2X4 / Q000378:metabolism; D058486:Receptors, Purinergic P2X7 / Q000378:metabolism*
chemical_list: D058848:Receptors, Purinergic P2X4; D058486:Receptors, Purinergic P2X7
keywords: Amyotrophic lateral sclerosis; Calcium homeostasis; Peripheral blood mononuclear cells; Purinergic receptors