Apolipoprotein CIII induces expression of vascular cell adhesion molecule-1 in vascular endothelial cells and increases adhesion of monocytic cells.
BACKGROUND
Activation of vascular endothelial cells (ECs) plays an important role in atherogenesis and plaque instability. Lipoproteins containing apolipoprotein CIII (apoCIII) predict coronary heart disease (CHD). We recently reported that apoCIII has a proinflammatory effect on human monocytes. In this study, we looked for a direct effect of apoCIII on EC expression of adhesion molecules, leading to monocytic cell adhesion.


RESULTS
Treatment of ECs with apoCIII or apoCIII-rich VLDL caused human monocytic THP-1 cells to adhere to them under static condition or under laminar sheer stress (1.0 dyne/cm2). ApoCIII increased EC expression of vascular cell adhesion molecule-1 (VCAM-1) protein and intercellular cell adhesion molecule-1 (ICAM-1) protein (4.9 +/- 1.5-fold and 1.4 +/- 0.5-fold versus control, respectively). Furthermore, apoCIII remarkably increased membrane-bound protein kinase C (PKC) beta in ECs, indicating activation. A selective inhibitor of PKCbeta prevented the rise in VCAM-1 and THP-1 cell adhesion to ECs. Moreover, exposure of ECs to apoCIII induced nuclear factor-kappaB (NF-kappaB) activation. PKCbeta inhibition abolished apoCIII-induced NF-kappaB activation, and NF-kappaB inhibition reduced expression of VCAM-1, each resulting in reduced THP-1 cell adhesion. ApoCIII-rich VLDL also activated PKCbeta and NF-kappaB in ECs and increased expression of VCAM-1. Pretreatment of ApoCIII-rich VLDL with anti-apoCIII neutralizing antibody abolished its effect on PKCbeta activation.


CONCLUSIONS
Our findings provide the first evidence that apoCIII increases VCAM-1 and ICAM-1 expression in ECs by activating PKCbeta and NF-kappaB, suggesting a novel mechanism for EC activation induced by dyslipidemia. Therefore, apoCIII-rich VLDL may contribute directly to atherogenesis by activating ECs and recruiting monocytes to them.
Kawakami
Akio
A
Department of Nutrition, Harvard School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA.
Aikawa
Masanori
M
Alcaide
Pilar
P
Luscinskas
Francis W
FW
Libby
Peter
P
Sacks
Frank M
FM
D053305:Apolipoprotein C-III; D001056:Apolipoproteins C / Q000502:physiology*; D050197:Atherosclerosis / Q000503:physiopathology; D002448:Cell Adhesion / Q000187:drug effects; D002460:Cell Line; D002478:Cells, Cultured; D015243:Cholesterol, VLDL / Q000097:blood / Q000494:pharmacology; D050171:Dyslipidemias / Q000150:complications; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D019012:Integrin beta1 / Q000502:physiology; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D009000:Monocytes / Q000166:cytology / Q000187:drug effects*; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000502:physiology; D011493:Protein Kinase C / Q000502:physiology; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism*
D053305:Apolipoprotein C-III; D001056:Apolipoproteins C; D015243:Cholesterol, VLDL; D020672:I-kappa B Proteins; D019012:Integrin beta1; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D019010:Vascular Cell Adhesion Molecule-1; D018799:Intercellular Adhesion Molecule-1; D000072000:NF-KappaB Inhibitor alpha; D011493:Protein Kinase C