Anti-apoptotic mechanism and reduced expression of phospholipase D in spontaneous and Fas-stimulated apoptosis of human neutrophils

Eur J Immunol. 2004 Oct;34(10):2760-70. doi: 10.1002/eji.200425117.

Abstract

Neutrophil apoptosis is a constitutive process that can be enhanced or delayed by signals triggered by various stimuli. In this work, we investigated the action mechanism of phospholipase D (PLD) and its expression in the inhibition of spontaneous and Fas-mediated apoptosis. Anti-Fas antibody-stimulated apoptosis of neutrophils was significantly blocked by the exogenous addition of bacterial PLD from Streptomyces chromofuscus (scPLD), and neutrophils cultured for 24 h in the presence of anti-Fas antibody showed lower agonist-stimulated PLD activity compared to untreated cells. The amount of PLD1a protein reduced time-dependently in cultured neutrophils, but was recovered by treating with LPS or GM-CSF. The reduction in PLD1a protein level was blocked by caspase inhibitors. The exogenous addition of scPLD blocked the up-regulation of Fas-associated death domain expression, mitochondrial permeability, and the cleavages of procaspase-8, procaspase-3, and protein kinase C-delta. We also found that the protein level of apoptosis-inducing factor was increased in cultured neutrophils but its expression was reduced by scPLD. However, sulfasalazine-induced apoptosis and change of protein expression were not blocked by scPLD. Taken together, the activity and protein levels of PLD play a role as an anti-apoptotic factor by acting at multiple levels of the apoptotic cascade in neutrophils.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects
  • Apoptosis / physiology*
  • Apoptosis Inducing Factor
  • Blotting, Western
  • Carrier Proteins / drug effects
  • Carrier Proteins / metabolism
  • Caspases / drug effects
  • Caspases / metabolism
  • Cells, Cultured
  • Co-Repressor Proteins
  • Dose-Response Relationship, Drug
  • Flavoproteins / drug effects
  • Flavoproteins / metabolism
  • Flow Cytometry
  • Humans
  • Intracellular Signaling Peptides and Proteins / drug effects
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Membrane Proteins / drug effects
  • Membrane Proteins / metabolism
  • Microscopy, Confocal
  • Mitochondria / metabolism
  • Molecular Chaperones
  • Neutrophils / drug effects
  • Neutrophils / immunology*
  • Nuclear Proteins / drug effects
  • Nuclear Proteins / metabolism
  • Phospholipase D / metabolism*
  • Phospholipase D / pharmacology
  • Time Factors
  • fas Receptor / metabolism*

Substances

  • AIFM1 protein, human
  • Apoptosis Inducing Factor
  • Carrier Proteins
  • Co-Repressor Proteins
  • Daxx protein, mouse
  • Flavoproteins
  • Intracellular Signaling Peptides and Proteins
  • Membrane Proteins
  • Molecular Chaperones
  • Nuclear Proteins
  • fas Receptor
  • Phospholipase D
  • Caspases