Mycoplasma Fermentans Inhibits Tumor Necrosis Factor Alpha-Induced Apoptosis in the Human Myelomonocytic U937 Cell Line

Cell Death Differ. 2004 Nov;11(11):1204-12. doi: 10.1038/sj.cdd.4401482.

Abstract

Mycoplasma fermentans (M. fermentans) was shown to be involved in the alteration of several eukaryotic cell functions (i.e. cytokine production, gene expression), and was suggested as a causative agent in arthritic diseases involving impaired apoptosis. We investigated whether M. fermentans has a pathogenic potential by affecting tumor necrosis factor (TNF)alpha-induced apoptosis in the human myelomonocytic U937 cell line. A significant reduction in the TNFalpha-induced apoptosis (approximately 60%) was demonstrated upon either infection with live M. fermentans or by stimulation with non-live M. fermentans. To investigate the mechanism of M. fermentans antiapoptotic effect, the reduction of mitochondrial transmembrane potential (DeltaPsim) and the protease activity of caspase-8 were measured. In the infected cells, the reduction of DeltaPsim was inhibited (approximately 75%), and an approximately 60% reduction of caspase-8 activity was measured. In conclusion, M. fermentans significantly inhibits TNFalpha-induced apoptosis in U937 cells, and its effect is upstream of the mitochondria and upstream of caspase-8.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis*
  • Caspase 8
  • Caspases / metabolism
  • Cell Cycle
  • Cell Separation
  • Enzyme-Linked Immunosorbent Assay
  • Flow Cytometry
  • Humans
  • Membrane Potentials
  • Microscopy, Confocal
  • Mitochondria / pathology
  • Monocytes / microbiology
  • Monocytes / pathology
  • Mycoplasma fermentans / metabolism*
  • Necrosis
  • Time Factors
  • Tumor Necrosis Factor-alpha / antagonists & inhibitors*
  • Tumor Necrosis Factor-alpha / metabolism*
  • U937 Cells

Substances

  • Tumor Necrosis Factor-alpha
  • CASP8 protein, human
  • Caspase 8
  • Caspases