Platelet expression profiling and clinical validation of myeloid-related protein-14 as a novel determinant of cardiovascular events.
BACKGROUND
Platelets participate in events that immediately precede acute myocardial infarction. Because platelets lack nuclear DNA but retain megakaryocyte-derived mRNAs, the platelet transcriptome provides a novel window on gene expression preceding acute coronary events.


RESULTS
We profiled platelet mRNA from patients with acute ST-segment-elevation myocardial infarction (STEMI, n=16) or stable coronary artery disease (n=44). The platelet transcriptomes were analyzed and single-gene models constructed to identify candidate genes with differential expression. We validated 1 candidate gene product by performing a prospective, nested case-control study (n=255 case-control pairs) among apparently healthy women to assess the risk of future cardiovascular events (nonfatal myocardial infarction, nonfatal stroke, and cardiovascular death) associated with baseline plasma levels of the candidate protein. Platelets isolated from STEMI and coronary artery disease patients contained 54 differentially expressed transcripts. The strongest discriminators of STEMI in the microarrays were CD69 (odds ratio 6.2, P<0.001) and myeloid-related protein-14 (MRP-14; odds ratio 3.3, P=0.002). Plasma levels of MRP-8/14 heterodimer were higher in STEMI patients (17.0 versus 8.0 microg/mL, P<0.001). In the validation study, the risk of a first cardiovascular event increased with each increasing quartile of MRP-8/14 (Ptrend<0.001) such that women with the highest levels had a 3.8-fold increase in risk of any vascular event (P<0.001). Risks were independent of standard risk factors and C-reactive protein.


CONCLUSIONS
The platelet transcriptome reveals quantitative differences between acute and stable coronary artery disease. MRP-14 expression increases before STEMI, and increasing plasma concentrations of MRP-8/14 among healthy individuals predict the risk of future cardiovascular events.
Healy
Aileen M
AM
Millennium Pharmaceuticals, Inc, Cambridge, MA, USA.
Pickard
Michael D
MD
Pradhan
Aruna D
AD
Wang
Yunmei
Y
Chen
Zhiping
Z
Croce
Kevin
K
Sakuma
Masashi
M
Shi
Can
C
Zago
Alexandre C
AC
Garasic
Joseph
J
Damokosh
Andrew I
AI
Dowie
Tracy L
TL
Poisson
Louis
L
Lillie
James
J
Libby
Peter
P
Ridker
Paul M
PM
Simon
Daniel I
DI