Infliximab Induces Apoptosis in Monocytes From Patients With Chronic Active Crohn's Disease by Using a Caspase-Dependent Pathway

Gastroenterology. 2001 Nov;121(5):1145-57. doi: 10.1053/gast.2001.28702.

Abstract

Background & aims: Treatment with a chimeric anti-tumor necrosis factor (TNF) antibody (infliximab) has been shown to be highly efficient for patients with steroid-refractory Crohn's disease (CD). However, the mechanism of action remains largely unknown. As monocytopenia is commonly observed after treatment with infliximab, we investigated the role of infliximab-induced monocyte apoptosis.

Methods: Peripheral blood monocytes from healthy volunteers and patients with chronic active CD (CDAI > 250) were isolated by density gradient centrifugation methods. Apoptosis was determined by annexin V staining DNA-laddering, and transmission electron microscopy. Activation of caspases and mitochondrial release of cytochrome C was determined by immunoblotting. Transcriptional activation of members of the Bcl-2 family have been analyzed by ribonuclease protection assay.

Results: Treatment with infliximab at therapeutic concentrations resulted in monocyte apoptosis in patients with chronic active CD in a dose-dependent manner. Infliximab-induced monocyte-apoptosis required the activation of members of the caspase-family since activation of caspase-8, -9, and -3 could be determined. Caspase activation was induced by a CD95/CD95L independent signaling pathway with mitochondrial release of cytochrome C. Cytochrome C release seemed to be triggered by transcriptional activation of Bax and Bak. Monocyte apoptosis in vivo as determined by annexin-V binding and caspase-3 activation could be shown in patients with chronic active CD as soon as 4 hours after treatment with infliximab.

Conclusions: Monocyte apoptosis induced by infliximab may be an important mechanism that could explain the powerful anti-inflammatory properties of infliximab in patients with chronic active CD.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Monoclonal / pharmacology*
  • Antibodies, Monoclonal / therapeutic use
  • Apoptosis / drug effects*
  • Caspases / physiology*
  • Cells, Cultured
  • Chronic Disease
  • Crohn Disease / blood
  • Crohn Disease / drug therapy*
  • Cytochrome c Group / metabolism
  • Enzyme Activation
  • Fas Ligand Protein
  • Gastrointestinal Agents / pharmacology*
  • Humans
  • Infliximab
  • Lipopolysaccharide Receptors / physiology
  • Membrane Glycoproteins / physiology
  • Membrane Proteins / genetics
  • Monocytes / drug effects*
  • Monocytes / physiology
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins c-bcl-2*
  • Transcriptional Activation
  • Tumor Necrosis Factor-alpha / antagonists & inhibitors*
  • Tumor Necrosis Factor-alpha / metabolism
  • bcl-2 Homologous Antagonist-Killer Protein
  • bcl-2-Associated X Protein

Substances

  • Antibodies, Monoclonal
  • BAK1 protein, human
  • BAX protein, human
  • Cytochrome c Group
  • FASLG protein, human
  • Fas Ligand Protein
  • Gastrointestinal Agents
  • Lipopolysaccharide Receptors
  • Membrane Glycoproteins
  • Membrane Proteins
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • Tumor Necrosis Factor-alpha
  • bcl-2 Homologous Antagonist-Killer Protein
  • bcl-2-Associated X Protein
  • Infliximab
  • Caspases