The effect of oxidized low density lipoprotein (oxLDL)-induced heme oxygenase-1 on LPS-induced inflammation in RAW 264.7 macrophage cells

Oxidation of low-density lipoprotein (LDL) plays a crucial role in the pathogenesis of atherosclerosis. Hemin (iron (III)-protoporphyrin IX) is a degradation product of hemoglobin that can be found in thalassemia patients. Hemin is a strong oxidant that can cause LDL oxidation and contributes to atherosclerosis in thalassemia patients. Lusianthridin from Dendrobium venustrum is a phenolic compound that possesses antioxidant activity. Hence, lusianthridin could be a promising compound to be used against hemin-induced oxidative stress. The major goal of this study is to evaluate the protective effect of lusianthridin on hemin-induced low-density lipoprotein oxidation (he-oxLDL). Here, various concentrations of lusianthridin (0.25, 0.5, 1, and 2 µM) were preincubated with LDL for 30 min, then 5 µM of hemin was added to initiate the oxidation, and oxidative parameters were measured at various times of incubation (0, 1, 3, 6, 12, 24 h). Lipid peroxidation of LDL was measured by thiobarbituric reactive substance (TBARs) assay and relative electrophoretic mobility (REM). The lipid composition of LDL was analyzed by using reverse-phase HPLC. Foam cell formation with he-oxLDL in RAW 264.7 macrophage cells was detected by Oil Red O staining. The results indicated that lusianthridin could inhibit TBARs formation, decrease REM, decrease oxidized lipid products, as well as preserve the level of cholesteryl arachidonate and cholesteryl linoleate. Moreover, He-oxLDL incubated with lusianthridin for 24 h can reduce the foam cell formation in RAW 264.7 macrophage cells. Taken together, lusianthridin could be a potential agent to be used to prevent atherosclerosis in thalassemia patients.

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Abstract 288: Atheroprotective Effect of Probucol Is Related to Its Heme Oxygenase 1 Activation and Subsequent Suppression of Oxidized Low-Density Lipoprotein--Induced Dendritic Cell Maturation

Circulation Research ◽

10.1161/res.111.suppl_1.a288 ◽

2012 ◽

Vol 111 (suppl_1) ◽

Author(s):

Aijun Sun ◽

Xueting Jin ◽

Jingjing Zhao ◽

Keqiang Wang ◽

Fang Xu ◽

...

Keyword(s):

Signaling Pathway ◽

Heme Oxygenase ◽

High Fat Diet ◽

Low Density Lipoprotein ◽

Density Lipoprotein ◽

Low Density ◽

Oxidized Low Density Lipoprotein ◽

High Fat ◽

Atherosclerotic Lesions

Aims: Probucol, an agent characterized by lipid-lowering and anti-oxidant property, retards atherosclerosis effectively. Our study aimed to test the hypothesis that probucol might act its anti-athersclerotic role by suppressing maturation of human monocyte-derived dendritic cells (h-monDC). Furthermore, we also used a LDLR-/- mice model fed a high-fat diet to detect whether probucol also perform its anti-atherosclerotic effect on suppressing DCs maturation in vivo. Methods: H-monDCs were derived by incubating purified human monocytes with GM-CSF and IL-4. H-monDCs were pre-incubated with or without probucol and stimulated by oxidized low-density lipoprotein (ox-LDL) in the presence or absence of heme oxygenase (HO-1) siRNA. In vivo studies, streptozotocin (STZ) induced LDLR-/- mice were fed either a high-fat (HF) diet or added with 0.5% probucol for 4 months. Expression of h-monDC membrane molecules and mice splenic CD11c+DC membrane molecules were analyzed by FACS, cytokines were measured by ELISA and the STAT1/CIITA associated signaling pathway was determined by Western blotting. Mice aortic lesions were observed by En face staining and the expression of CD11c+DCs within atherosclerotic plaques were shown under confocal microscopy. Results: Ox-LDL promoted h-monDC maturation and TNF-a production; and up-regulated STAT1 701 phosphorylation by activating HO-1 in STAT1/CIITA signaling pathway. These effects were inhibited by probucol. Knocking down HO-1 with specific siRNA blocked these effects of probucol. In LDLR-/- mice fed a high-fat diet, probucol treatment significantly regressed aortic atherosclerotic lesions, suppressed splenic CD11c+DCs maturation and IL-12p70 production; and resulted in absence of CD11c+DCs within atherosclerotic lesions. Conclusions: Our study indicated that probucol effectively suppressed maturation of h-monDC induced by ox-LDL through HO-1 activation, and retarded atherosclerosis at least partly through inhibiting maturations of CD11c+DCs in LDLR-/- mice.

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