Biomedical Engineering Reference
In-Depth Information
transcription of both molecules was upregulated at 4 and 8 hr, and then decreased
at later time points.
In another study, the VSMC were tested for the induction of the expression
of ICAM-1 and VCAM-1 adhesion molecules by cLDL (Asci
et al.
). For this,
human coronary artery VSMC were treated with cLDL or nLDL and expression of
ICAM-1 and VCAM-1 was evaluated by cell ELISA. h e data suggested that, unlike
endothelial cells, cLDL-treated VSMC overexpress mostly VCAM-1 and to a lesser
extent ICAM-1. However, because both adhesion molecules are overexpressed in
vascular endothelial and smooth muscle cells, we may conclude that both ICAM-1
and VCAM-1 overexpression is likely to be a unique specii c response from the
vascular system to cLDL impact.
Role of ICAM-1 and VCAM-1 in cLDL-induced Monocyte
Adhesion
Two approaches were applied to determine whether cLDL-induced ICAM-1 and/
or VCAM-1 overexpression cause the adhesion of monocytes to endothelial cells.
In the i rst, the functions of ICAM-1 and VCAM-1 were abolished by antibodies,
and in the second, the expression of the adhesion molecules was silenced using
specii c siRNA.
Because of the superi cial location of adhesion molecules in endothelium, the
antibodies to these proteins are widely used as a tool for determining the role
of adhesion molecules. h ese studies showed that the inhibition of ICAM-1
caused a signii cant reduction of monocyte adhesion to endothelial cells, while
the inhibition of VCAM-1 had only a minor and non-signii cant ef ect
(Fig. 5)
.
In the same experimental setting, simultaneous pretreatment of endothelial cells
with both anti-ICAM-1 and anti-VCAM-1 antibodies caused the most signii cant
inhibition of monocyte adhesion. Rabbit gamma-immunoglobulins, which were
used as a negative control, did not have signii cant ef ect on monocyte adhesion
regardless of the treatment.
h e introduction of specii c siRNAs resulted in the signii cant inhibition of
ICAM-1 or VCAM-1 expression in modii ed LDL-treated cells as determined
using real-time RT-PCR. At er the application of siRNAs to HCAECs for 48 hr,
the cells were treated for an additional 16 hr with vehicle, cLDL or nLDL and
monocyte adhesion was measured. h e data presented in Fig. 6 show that cLDL
caused accelerated monocyte adhesion to endothelial cells, and it was signii cantly
suppressed by anti-ICAM-1 siRNA. Anti-VCAM-1 siRNA had only a partial ef ect
while simultaneously using anti-ICAM-1, while anti-VCAM-1 siRNAs caused
the most prominent and signii cant suppression of monocyte adhesion. It did
not reach the level of cells treated with the vehicle or nLDL, but it was consistent
with the transfection ei ciency observed in this experiment. Although nLDL did
not accelerate monocyte adhesion, it was slightly suppressed by specii c siRNAs.
