Molecular fingerprint of interferon-gamma signaling in unstable angina.
BACKGROUND
Activation of circulating monocytes in patients with acute coronary syndromes may reflect exposure to bacterial products or stimulation by cytokines such as IFN-gamma. IFN-gamma induces phosphorylation and nuclear translocation of transcription factor STAT-1, which initiates a specific program of gene induction. To explore whether monocyte activation is IFN-gamma driven, patients with unstable (UA) or stable angina (SA) were compared for nuclear translocation of STAT-1 complexes and upregulation of IFN-gamma-inducible genes CD64 and IP-10.


RESULTS
Peripheral blood mononuclear cells were stained for expression of CD64 on CD14(+) monocytes and analyzed by PCR for transcription of IP-10. Expression of CD64 was significantly increased in patients with UA. Monocytes from UA patients remained responsive to IFN-gamma in vitro, with accelerated transcriptional competency of CD64. IP-10-specific sequences were spontaneously detectable in 82% of the UA patients and 15% of SA patients (P<0.001). Most importantly, STAT-1 complexes were found in nuclear extracts prepared from freshly isolated monocytes of patients with UA, which provides compelling evidence for IFN-gamma signaling in vivo.


CONCLUSIONS
Monocytes from UA patients exhibit a molecular fingerprint of recent IFN-gamma triggering, such as nuclear translocation of STAT-1 complexes and upregulation of IFN-gamma-inducible genes CD64 and IP-10, which suggests that monocytes are activated, at least in part, by IFN-gamma. IFN-gamma may derive from stimulated T lymphocytes, which implicates specific immune responses in the pathogenesis of acute coronary syndromes.
Liuzzo
G
G
Department of Medicine, Mayo Clinic and Foundation, Rochester, Minnesota, USA.
Vallejo
A N
AN
Kopecky
S L
SL
Frye
R L
RL
Holmes
D R
DR
Goronzy
J J
JJ
Weyand
C M
CM
D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D000368:Aged; D000789:Angina, Unstable / Q000378:metabolism* / Q000473:pathology; D054357:Chemokine CXCL10; D019743:Chemokines, CXC / Q000096:biosynthesis* / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000187:drug effects* / Q000378:metabolism; D017452:Receptors, IgG / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D050794:STAT1 Transcription Factor; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
D054357:Chemokine CXCL10; D019743:Chemokines, CXC; D004268:DNA-Binding Proteins; D017452:Receptors, IgG; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D015534:Trans-Activators; D007371:Interferon-gamma