L-4F, an Apolipoprotein A-1 Mimetic, Restores Nitric Oxide and Superoxide Anion Balance in Low-Density Lipoprotein-Treated Endothelial Cells

Endothelial cell dysfunction (ECD) is emerging as a common denominator for diverse cardiovascular abnormalities associated with inhibition of endothelial nitric oxide (NO) synthase (eNOS). Elevated levels of asymmetric dimethylarginine (ADMA), a potent eNOS inhibitor, are common in renal failure and may contribute to ECD. Through DNA microarray screening of genes modulated in human umbilical vein endothelial cells (HUVEC) by NG-nitro-l-arginine methyl ester (l-NAME), we found a 1.8-fold increase in low-density lipoprotein receptor-1 (LOX-1) expression. LOX-1 is a major endothelial receptor for oxidized low-density lipoproteins (OxLDL) and is assumed to play a role in the initiation and progression of atherosclerosis. Here, we confirmed the upregulation of LOX-1 mRNA and protein level by quantitative RT-PCR and Western blot analysis. Increased expression of LOX-1 was associated with the accumulation of DiI-labeled OxLDL (DiI-OxLDL) in ADMA- and l-NAME-pretreated HUVEC. To evaluate the contribution of LOX-1 in ADMA-induced accumulation of OxLDL by HUVEC, we used the competitive receptor inhibitor, soluble LOX-1. Treatment of HUVEC with soluble LOX-1 was associated with an approximately two- to threefold inhibition of DiI-OxLDL uptake in l-NAME- or ADMA-treated HUVEC. In conclusion, ADMA- or l-NAME-induced NO deficiency leads to the increased expression of LOX-1 mRNA and protein in HUVEC, which in turn results in the accumulation of OxLDL. Competition with LOX-1-soluble extracellular domain reduces OxLDL accumulation. In summary, elevated ADMA levels, i.e., in patients with renal failure, may be responsible for endothelial accumulation of OxLDL via upregulated LOX-1 receptor, thus contributing to endothelial lipidosis and dysfunction.

Download Full-text

Puerarin protects endothelial cells from oxidized low density lipoprotein induced injuries via the suppression of LOX-1 and induction of eNOS

Canadian Journal of Physiology and Pharmacology ◽

10.1139/cjpp-2013-0322 ◽

2014 ◽

Vol 92 (4) ◽

pp. 299-306 ◽

Cited By ~ 8

Author(s):

Mei-hua Bao ◽

Yi-wen Zhang ◽

Xiao-ya Lou ◽

Yan Xiao ◽

Yu Cheng ◽

...

Keyword(s):

Nitric Oxide ◽

Endothelial Cells ◽

Cell Viability ◽

Nuclear Translocation ◽

Low Density Lipoprotein ◽

Density Lipoprotein ◽

No Production ◽

Low Density ◽

Oxidized Low Density Lipoprotein ◽

Cox 2

Oxidized low density lipoprotein (oxLDL) induced injury of endothelial cells is considered to be the first step in the pathogenesis of atherosclerosis. This study aimed to investigate some of the effects and mechanisms of puerarin on oxLDL-induced endothelial injuries. We measured cell viability, and the release of lactate dehydrogenase (LDH), nitric oxide (NO), and interleukin-8 (IL-8) to evaluate the protective effects of puerarin. Intracellular reactive oxygen species (ROS) were detected using 2′,7′-dichlorofluorescein diacetate (DCFH-DA). The expression of lectin-like low-density lipoprotein receptor-1 (LOX-1), endothelial nitric oxide synthase (eNOS), cyclooxygenase 2 (COX-2), p38MAPK, and protein kinase B (PKB) phosphorylation, nuclear factor-κB (NF-κB) nuclear translocation, and inhibitor of κB (IκB) degradation were detected using quantitative real-time PCR or Western blot. The results showed that oxLDL significantly decreased cell viability, increased LDH and IL-8 release, inhibited NO production, and induced COX-2 expression. Pretreatment with puerarin led to a strong inhibition of these effects. OxLDL stimulated the expression of LOX-1, the overproduction of ROS, the phosphorylation of p38MAPK, the dephosphorylation of PKB, activation of NF-κB, and the degradation of IκB. These oxLDL-induced effects were suppressed after puerarin pretreatment. These results suggest that puerarin inhibits oxLDL-induced endothelial cell injuries, at least in part, via inhibition of the LOX-1-mediated p38MAPK–NF-κB inflammatory and the PKB–eNOS signaling pathways.

Download Full-text