Monocyte-endothelial interaction and its modulation by
chemokines play a key role in
atherogenesis and
inflammation. We examined the potential effects of stromal cell-derived factor (SDF-1) and
azelnidipine, a novel
dihydropyridine derivative, toward monocyte-endothelial interaction. Human monocytes were prepared from peripheral blood mononuclear cells obtained from healthy volunteers and pretreated with
azelnidipine (1 microM) for 48 h, after which their adhesion to
interleukin-1beta (IL-1beta)-activated human umbilical vein endothelial cells (HUVECs) was analyzed using an in vitro flow apparatus with a shear stress of 1 dyn/cm(2). In some experiments, monocytes were incubated in the presence of stromal cell-derived factor (SDF-1), a
chemokine, just prior to the assay. Pre-incubation of monocytes with SDF-1 enhanced their adhesion to activated HUVECs. When monocytes were pre-incubated in the presence of
azelnidipine, baseline levels as well as SDF-1-induced monocyte adhesion levels were reduced. Interestingly, the surface expressions of the adhesion molecules CD11a, CD11b, and CD36, were not changed by
azelnidipine treatment. Western blotting analysis revealed that activation of
protein kinase C (PKC)alpha was inhibited by
azelnidipine treatment, while it also reduced the SDF-1-induced increase in intracellular
calcium concentration ([Ca(2+)](i)). Further, pre-incubation of monocytes with
Go6976, a potent inhibitor of PKCalpha, significantly reduced monocyte adhesion to HUVECs. Our results demonstrated an inhibitory action of
azelnidipine toward adhesive interactions of monocytes to HUVECs, which involves inhibition of PKCalpha and a reduction in [Ca(2+)](i). These findings imply a protective role of
azelnidipine against
inflammation in
atherosclerosis.