Summary
The role of individual monocyte subsets in inflammation and recovery post-myocardial
infarction (MI) is insufficiently understood. It was the objective of this study to
evaluate the dynamics of monocyte expression of receptors to vascular cell adhesion
molecule (VCAM-1r), intercellular adhesion molecule (ICAM-1r), and interleukin-6 (IL-6r)
following MI and their relation to inflammatory cytokines, fibrinolytic factors and
annexin V-binding microparticles. Expression of VCAM-1r, ICAM-1r, IL-6r on CD14++CD16–(Mon1),
CD14++CD16+(Mon2), CD14+CD16++(Mon3) monocyte subsets were quantified by flow cytometry
in patients with ST-elevation MI (STEMI, n=50), non-STEMI (n=48) and stable coronary
artery disease (n=40). In STEMI, parameters were measured on days 1, 3, 7, 30. On
admission with STEMI, VCAM-1r expression was reduced on Mon1 (p=0.007), Mon2 (p=0.036),
Mon3 (p=0.005), whilst in NSTEMI there was significant up-regulation of expression
by Mon2 (p=0.024) and Mon3 (p=0.049). VCAM-1r on Mon1 correlated positively with plasma
IL-1β levels (p=0.001). IL-6r was reduced on Mon2 in acute STEMI, with upregulation
of the receptor on Mon1 and Mon2 during follow-up. IL-6r density correlated negatively
with plasma levels of tissue-type plasminogen activator (p=0.0005 for Mon1, p=0.001
for Mon2 and Mon3), and positively with annexin V-binding microparticles (p=0.03 for
Mon1, p=0.005 for Mon2 and p=0.005 for Mon3). There was no change in monocyte ICAM-1r
expression. In conclusion, expression of IL-6r and VCAM-1r is reduced on circulating
monocyte subsets involved in inflammatory responses in STEMI. This may represent a
regulatory feed-back mechanism aiming to re-balance the marked inflammation which
is typically present following acute MI or selective homing of monocytes with high
receptor expression to damaged myocardium.
Note: The review process for this manuscript was fully handled by Christian Weber,
Editor in Chief.
Keywords
Monocytes - monocyte subsets - myocardial infarction - interleukin-6 receptor - intercellular
cell adhesion molecule - vascular cell adhesion molecule
