• BMB Reports
• /
• v.48 no.1
• /
• pp.48-53
• /
• 2015

Oxidized LDL (oxLDL) performs critical roles in atherosclerosis by inducing macrophage foam cell formation and promoting inflammation. There have been reports showing that oxLDL modulates macrophage cytoskeletal functions for oxLDL uptake and trapping, however, the precise mechanism has not been clearly elucidated. Our study examined the effect of oxLDL on non-muscle myosin heavy chain IIA (MHC-IIA) in macrophages. We demonstrated that oxLDL induces phosphorylation of MHC-IIA (Ser1917) in peritoneal macrophages from wild-type mice and THP-1, a human monocytic cell line, but not in macrophages deficient for CD36, a scavenger receptor for oxLDL. Protein kinase C (PKC) inhibitor-treated macrophages did not undergo the oxLDL-induced MHC-IIA phosphorylation. Our immunoprecipitation revealed that oxLDL increased physical association between PKC and MHC-IIA, supporting the role of PKC in this process. We conclude that oxLDL via CD36 induces PKC-mediated MHC-IIA (Ser1917) phosphorylation and this may affect oxLDL-induced functions of macrophages involved in atherosclerosis.

• Proceedings of the PSK Conference
• /
• 2001.10a
• /
• pp.109-113
• /
• 2001

Oxidized low-density lipoprotein (oxLDL) has been shown to modulate transactivations by the peroxisome proliferator activated receptor (PPAR)$\gamma$ and nuclear factor-kappa B (NF$\kappa$B). In this study, the oxLDL signaling pathways involved with the NF$\kappa$B transactivation were investigated by utilizing a reporter construct driven by three upstream NF$\kappa$B binding sites, and various pharmacological inhibitors. OxLDL and its constituent lysophophatidylcholine (lysoPC) induced a rapid and transient increase of intracellular calcium and stimulated the NF-KB transactivation in resting RAW264.7 macrophage cells in an oxidation-dependent manner. The NF$\kappa$B activation by oxLDL or lysoPC was inhibited by protein kinase C inhibitors or an intracellular calcium chelator. Tyrosine kinase or PI3 kinase inhibitors did not block the NF$\kappa$B transactivation. Furthermore, the oxLDL-induced NF$\kappa$B activity was abolished by the PPAR$\gamma$ ligands. When the endocytosis of oxLDL was blocked by cytochalasin B, the NF$\kappa$B transactivation by oxLDL was synergistically increased, while PPAR transactivation was blocked. These results suggest that oxLDL activates NF-$\kappa$B in resting macrophages via protein kinase C- and/or calcium-dependent pathways, which does not involve the endocytic processing of oxLDL. The endocytosis-dependent PPAR$\gamma$ activation by oxLDL may function as an inactivation route of the oxLDL induced NF$\kappa$B signal. Short heterodimer partner (SHP), specifically expressed in liver and a limited number of other tissues, is an unusual orphan nuclear receptor that lacks the conventional DNA-binding domain. In this work, we found that SHP expression is abundant in murine macrophage cell line RAW 264.7 but suppressed by oxLDL and its constituent I3-HODE, a ligand for peroxisome proliferator-activated receptor y. Furthermore, SHP acted as a transcription coactivator of nuclear factor-$\kappa$B (NF$\kappa$B) and was essential for the previously described NF$\kappa$B transactivation by lysoPC, one of the oxLDL constituents. Accordingly, NF$\kappa$B, transcriptionally active in the beginning, became progressively inert in oxLDL-treated RAW 264.7 cells, as oxLDL decreased the SHP expression. Thus, SHP appears to be an important modulatory component to regulate the transcriptional activities of NF$\kappa$B in oxLDL-treated, resting macrophage cells.

• Journal of Periodontal and Implant Science
• /
• v.50 no.3
• /
• pp.135-145
• /
• 2020

Purpose: The aim of this study was to evaluate the serum levels of oxidized low-density lipoprotein (oxLDL), anti-oxLDL, and myeloperoxidase (MPO) in hyperlipidemic patients with periodontal disease. Methods: This study included 123 patients with hyperlipidemia categorized based on metabolic control as mild to moderate (H1) (n=66) or poor (H2) (n=57), as well as systemically healthy controls (C) (n=68). Serum levels of lipids, oxLDL, anti-oxLDL, and MPO were evaluated, along with clinical periodontal parameters. Results: The percentage of bleeding on probing (BOP%) and the clinical attachment level were significantly higher in the H2 group than in the C group. Patients with hyperlipidemia had a relatively high risk of developing periodontal disease. The oxLDL and anti-oxLDL levels were higher in H2 patients with periodontitis than in the control or H1 patients with periodontitis. In the H1 and H2 groups, the ratio of total cholesterol to high-density lipoprotein was significantly correlated with gingival index, BOP%, and oxLDL levels. Conclusions: Our findings indicate that the lipoprotein-associated inflammatory mediators of oxLDL, anti-oxLDL, and MPO may play an important role in the relationship between periodontal disease and hyperlipidemia.

• Journal of Society of Preventive Korean Medicine
• /
• v.4 no.2
• /
• pp.205-213
• /
• 2000

The oxidative modification of low density lipoprotein(LDL) has been implicated in the development of atherosclerosis . Oxidized LDL(oxLDL) are found in macrophage foam cell , and it can induce an macrophage proliferation in atherosclerotic plaque. In this study, we investigated the hypothesis that Tokhwalkisaengtang(TK) may reduce atherosclerosis by lowering the oxidizability of LDL, To achieve this goal, we examined the effect of TK on LDL oxidation, nitric oxide production in murine macrophage cell line , and the effect of TK on cupuric sulfate-induced cytotoxicity. LDH release, and macrophage activity TK inhibited the generation of oxLDL from native LDL in macrophage cell culture, and decreased the release of LDH from cupric sulfate-stimulated macrophage. In other experiments, TK activated macrophase cell, and increased the survival rate, and enhanced nitric oxide production in macrophage.

• The Journal of Internal Korean Medicine
• /
• v.24 no.2
• /
• pp.203-212
• /
• 2003

Objective : As a link in chain of research to confirm the oriental medical prescription which has the anti-atherosclerosis effects, this research evaluated the effects on the macrophage-related factors by using KanghwalSokdantang(KS). Methods : In order to perform this research, we have evaluated the effects on the oxLDL formation from the macrophages, the nitric oxide formation, and the oxidation of macrophages. Thus, with this evaluation, we have investigated the applicapability on the artherosclerosis. Results : KanghwalSokdantang has showed a noticeable reduction of protein oxidation in the process of oxLDL formation, has remarkably restrained phospholipid peroxidation, an index to estimated the phospholipid oxidation and reduction that are formed in the process of macrophage's oxLDL formation, and has increased the nitrite concentration noticeably in the LDL-dealing macrophages. By increasing the survival rate of macrophages, KanghwalSokdantang has restrained the cellular damages. KanghwalSokdantang is ineffective on the LDH outflow from damaged cells. $1{\mu}g/ml$ KanghwalSokdantang sample has increased acid phosphatase activity remarkably. Conclusion : KanghwalSokdantang has the possibility to be used in the prevention and treatment of atherosclerosis, which is formed by the oxLDL formation of macrophages.

• Journal of Nutrition and Health
• /
• v.36 no.9
• /
• pp.908-917
• /
• 2003

It has been proposed that oxidative modification of LDL (oxLDL) plays a significant role in the pathogenicity of atherogenesis. We tested the hypothesis that chitin and chitosan may function as antioxidants with respect to 0.1 mg cholesterol/ml LDL incubated with 5 $\mu$ M Cu$^2$$^{+}$alone or in the P338Dl mouse macrophage system using L-ascorbic acid as a standard classical antioxidant. The degree of oxLDL formation was ascertained by the relative electrophoretic mobility (rEM) in the combination of thiobarbituric acid reactive substances (TBARS) levels, and the cytotoxicity of oxLDL was detected by macrophage viability. The oxLDL uptake and foam cell formation of macrophages were measured by Oil Red O staining. Incubation with Cu$^2$$^{+}$and macrophages increased rEM of LDL and stimulated TBARS formation. Culture of macrophages with LDL in the presence 5 $\mu$ M Cu$^2$$^{+}$induced macrophage death. In cell-free system 200 $\mu$g/ml water-soluble chitosan and chitosan-oligosaccharide blocked oxLDL formation. Water-soluble chitosan and chitosan-oligosaccharide blocked oxLDL formation near-completely relative to L-ascorbic acid, whereas water-soluble chitin and chitin-oligosaccharide had no measurable antioxidant effect. In macrophage system water-soluble chitosan and chitosan-oligosaccharide blocked oxidation of LDL with a significant increase in cell viability, and decreased TBARS in medium. As for the inhibitory effect on macrophage foam cell formation, chitosan and its oligosaccharide, but not watersoluble chitin, revealed the effectiveness. The endothelial expression of lectin-like oxLDL receptor-1 (LOX-1) was tested by Western blot analysis, and chitosan, chitosan-oligosaccharide and chitin-oligosaccharide blocked LOX-1 expression. These results indicate that water-soluble chitosan and its oligosaccharide showed the inhibitory effect on Cu$^2$$^{+}$-induced LDL oxidation of macrophages, and chitosan, chitosan-oligosaccharide and chitin-oligosaccharide had blocking effect on oxLDL receptor expression in the human umbilical vein endothelial system. Thus, water-soluble chitosan and its oligosaccharides possess anti-atherogenic potentials possibly through the inhibition of macrophage LDL oxidation or endothelial oxLDL receptor expression depending on chemical types.l types.

• Journal of Microbiology and Biotechnology
• /
• v.32 no.11
• /
• pp.1406-1415
• /
• 2022

The formation of macrophage foam cells stimulated by oxidized low-density lipoprotein (ox-LDL) is deemed an important cause of atherosclerosis. Transcription factor Yin Yang 1 (YY1), which is a universally expressed multifunctional protein, is closely related to cell metabolism disorders such as lipid metabolism, sugar metabolism, and bile acid metabolism. However, whether YY1 is involved in macrophage inflammation and lipid accumulation still remains unknown. After mouse macrophage cell line RAW264.7 cells were induced by ox-LDL, YY1 and proprotein convertase subtilisin/kexin type 9 (PCSK9) expressions were found to be increased while low-density lipoprotein receptor (LDLR) expression was lowly expressed. Subsequently, through reverse transcription-quantitative polymerase chain reaction (RT-qPCR), Western blot analysis, Oil Red O staining and cholesterol quantification, it turned out that silencing of YY1 attenuated the inflammatory response and lipid accumulation in RAW264.7 cells caused by ox-LDL. Moreover, results from the JASPAR database, chromatin immunoprecipitation (ChIP) assay, luciferase reporter assay and Western blot analysis suggested that YY1 activated PCSK9 by binding to PCSK9 promoter and modulated the expression of LDLR in the downstream of PCSK9. In addition, the results of functional experiments demonstrated that the inhibitory effects of YY1 interference on ox-LDL-mediated macrophage inflammation and lipid accumulation were reversed by PCSK9 overexpression. To sum up, YY1 depletion inhibited its activation of PCSK9, thereby reducing cellular inflammatory response, cholesterol homeostasis imbalance, and lipid accumulation caused by ox-LDL.

• Journal of Society of Preventive Korean Medicine
• /
• v.16 no.2
• /
• pp.113-124
• /
• 2012

The oxidative modification of low density lipoprotein(LDL) has been implicated in the development of atherosclerosis. Oxidized LDL(oxLDL) is captured into macrophage and stimulates to form macrophage foam cell. And it can induce an inflammation and smooth muscle proliferation in atherosclerotic plaque. Objective : In this study, we aimed to investigate the effect of Bupleuri radix(SH) on the foam cell formation, a critical initiation stage of atherosclerosis. Methods : To achieve the goal, we examined the effect of SH on LDL oxidation, nitric oxide production in RAW264.7, and the effect of SH on cupuric sulfate-induced cytotoxicity, LDH release, and macrophage activity. Results : SH inhibited the formation of oxidized LDL from native LDL in RAW264.7 cell culture, and decreased the release of LDH from cupric sulfate-stimulated RAW264.7 cell. In other experiments, SH activated RAW264.7 cell, and prolonged the survival time, and inhibited foam cell formation induced by oxLDL in Raw 264.7 cells. Conclusion : These results showed that SH might prevent atherosclerosis by controlling the early stages of foam cell formation.

• Journal of Life Science
• /
• v.20 no.11
• /
• pp.1595-1602
• /
• 2010

Oxidation of low density lipoprotein (LDL) has been recognized as an important role in the initiation and progression of atherosclerosis. In this study, effects of allylmercaptan, a major metabolite compound of garlic, was studied on endothelial cell injury induced by oxidized low density lipoprotein (ox-LDL). The antioxidative activity of allylmercaptan was investigated by monitoring a thiobarbituric acid substance (TBARS). Allylmercaptan inhibited LDL oxidation induced by $Cu^{2+}$ at concentrations of 0.1, 1 and 10 mM in a dose dependent manner. Lactate dehydrogenase (LDH) release, as an index of cell injury, and intracellular glutathione levels were determined. Pulmonary artery endothelial cells were preincubated with allylmercaptan at $37^{\circ}C$ and 5% $CO_2$ for 24 hr, washed, and then exposed to 0.1 mg/ml oxidized LDL for 24 hr. Preincubation of endothelial cells with allylmercaptan significantly prevented the LDH release and depletion of GSH. Peroxides were measured directly in 24 well plates using a fluorometric assay. Allylmercaptan inhibited release of peroxides induced by ox-LDL in pulmonary artery endothelial cells. In a free system, allylmercaptan was shown to scavenge hydrogen peroxide. The data indicate that allylmercaptan can protect pulmonary artery endothelial cells from injury caused by oxidized LDL, and suggest that allylmercaptan may be useful for the prevention of atherosclerosis.