Remnant lipoprotein particles induce apoptosis in endothelial cells by NAD(P)H oxidase-mediated production of superoxide and cytokines via lectin-like oxidized low-density lipoprotein receptor-1 activation - Prevention by cilostazol

Background - Remnant lipoprotein particles ( RLPs), products of lipolytic degradation of triglyceride- rich lipoprotein derived from VLDL, exert atherogenesis. In this study, we observed how RLPs induced cytotoxicity in human umbilical vein endothelial cells ( HUVECs) and cilostazol prevented cell death. Methods and Results - RLPs were isolated from the plasma of hyperlipidemic patients by use of an immunoaffinity gel mixture of anti - apolipoprotein A- 1 and anti - apolipoprotein B- 100 monoclonal antibodies. RLPs ( 50 mu g/ mL) significantly increased superoxide formation in HUVECs associated with elevated gp91phox mRNA and protein expression and Rac1 translocation, accompanied by increased production of tumor necrosis factor ( TNF)-alpha and interleukin-1beta, DNA fragmentation, and cell death. Cilostazol ( 1 to 100 mumol/ L) significantly suppressed not only NAD( P)H oxidase - dependent superoxide production but also TNF-alpha and interleukin-1beta release and restored viability. RLPs activated a lectin- like oxidized low- density lipoprotein receptor- 1 ( LOX- 1), which was not inhibited by cilostazol. Treatment of HUVECs with monoclonal antibody for LOX- 1 attenuated RLP- mediated production of superoxide, TNF-alpha, and interleukin-1beta and DNA fragmentation. Conclusions - RLPs stimulated NAD( P) H oxidase - dependent superoxide formation and induction of cytokines in HUVECs via activation of LOX- 1, consequently leading to reduction in cell viability with DNA fragmentation, and cilostazol exerts a cell- protective effect by suppressing these variables.