Cardiovascular inflammation and lesion cell apoptosis: a novel connection via the interferon-inducible immunoproteasome

Arterioscler Thromb Vasc Biol. 2009 Aug;29(8):1213-9. doi: 10.1161/ATVBAHA.109.189407. Epub 2009 May 14.


Objective: Increasing evidence suggests that chronic inflammation contributes to atherogenesis, and that acute inflammatory events cause plaque rupture, thrombosis, and myocardial infarction. The present studies examined how inflammatory factors, such as interferon-gamma (IFNgamma), cause increased sensitivity to apoptosis in vascular lesion cells.

Methods and results: Cells from the fibrous cap of human atherosclerotic lesions were sensitized by interferon-gamma (IFNgamma) to Fas-induced apoptosis, in a Bcl-X(L) reversible manner. Microarray profiling identified 72 INFgamma-induced transcripts with potential relevance to apoptosis. Half could be excluded because they were induced by IRF-1 overexpression, which did not sensitize to apoptosis. IFNgamma treatment strongly reduced Mcl-1, phospho-Bcl-2 (ser70), and phospho-Bcl-X(L) (ser62) protein levels. Candidate transcripts were modulated by siRNA, overexpression, or inhibitors to assess the effect on IFNgamma-induced Fas sensitivity. Surprisingly, siRNA knockdown of PSMB8 (LMP7), an "immunoproteasome" component, reversed IFNgamma-induced sensitivity to Fas ligation and prevented Fas/IFNgamma-induced degradation of Mcl-1, but did not protect p-Bcl-2 or p-Bcl-X(L). Proteasome inhibition markedly increased Mcl-1, p-Bcl-2, and p-Bcl-X(L) levels after IFNgamma treatment.

Conclusions: Although critical for antigen presentation, the immunoproteasome appears to be a key link between inflammatory factors and the control of vascular cell apoptosis and may thus be an important factor in plaque rupture and myocardial infarction.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects
  • Apoptosis / physiology*
  • Atherosclerosis / genetics
  • Atherosclerosis / metabolism
  • Atherosclerosis / pathology*
  • Blotting, Western
  • Carotid Arteries / metabolism
  • Carotid Arteries / pathology
  • Cells, Cultured
  • Gene Expression Regulation
  • Humans
  • Interferon-gamma / pharmacology*
  • Multienzyme Complexes / antagonists & inhibitors
  • Multienzyme Complexes / biosynthesis
  • Multienzyme Complexes / genetics*
  • Proteasome Endopeptidase Complex
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • RNA, Small Interfering / genetics*
  • Reverse Transcriptase Polymerase Chain Reaction
  • STAT1 Transcription Factor / metabolism
  • Transcription, Genetic*
  • bcl-X Protein / biosynthesis
  • bcl-X Protein / genetics


  • Multienzyme Complexes
  • Proto-Oncogene Proteins c-bcl-2
  • RNA, Small Interfering
  • STAT1 Transcription Factor
  • STAT1 protein, human
  • bcl-X Protein
  • Interferon-gamma
  • LMP7 protein
  • Proteasome Endopeptidase Complex