Journal of Nutrition OpenSOurce Diets- www.ResearchDiets.com

Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Purchase Article
Right arrow View Shopping Cart
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Ide, N.
Right arrow Articles by Weiss, N.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ide, N.
Right arrow Articles by Weiss, N.
© 2006 American Society for Nutrition J. Nutr. 136:755S-758S, March 2006

Supplement: Significance of Garlic and Its Constituents in Cancer and Cardiovascular Disease

Aged Garlic Extract Inhibits Homocysteine-Induced CD36 Expression and Foam Cell Formation in Human Macrophages1–3,

Nagatoshi Ide, Christiane Keller and Norbert Weiss4

Medical Policlinic, City Campus, University of Munich Medical Center, D-80336 Munich, Germany

4 To whom correspondence should be addressed. E-mail: Norbert.Weiss{at}med.uni-muenchen.de.


   ABSTRACT
TOP
 ABSTRACT
MATERIAL AND METHODS
 RESULTS
 DISCUSSION
 LITERATURE CITED
 
Elevated plasma homocysteine (Hcy) levels have been recognized as an independent risk factor for atherosclerotic vascular disease. During formation of early atherosclerotic lesions, expression of CD36, a class B scavenger receptor on macrophages, is crucially involved in the uptake of oxidized low-density lipoprotein (OxLDL) and foam-cell formation. We therefore determined the effects of Hcy on CD36 expression and foam cell formation in human monocytes/macrophages (THP-1) using flow cytometry, and the effects of aged garlic extract (AGE) on this process. Incubation of THP-1 cells with Hcy (200 µmol/L) for 72 h in the presence of phorbol 12-myristate 13-acetate (PMA) (10 nmol/L) caused a 37.8 ± 5.2% increase in CD36 expression compared with PMA-stimulated cells without Hcy (P < 0.01). Coincubation with AGE (5 g/L) significantly suppressed CD36 expression by 61.8 ± 13.9%, compared with control conditions, and by 48.6 ± 9.0% compared with Hcy-incubated cells (P < 0.01). THP-1 cells in the presence of PMA (10 nmol/L) were incubated with Hcy or AGE for 72 h followed by incubation with 1,1'-dioctadecyl-3,3,3'3'-tetra-methylindocyanide percholorate (DiI)-labeled OxLDL for 3 h, and fluorescence intensity was measured by flow cytometry. AGE also inhibited DiI-labeled OxLDL uptake into PMA-stimulated THP-1 cells by 85.6 ± 2.8% (P < 0.01), but Hcy had no effects on it. Our data indicate that AGE inhibits CD36 expression and OxLDL uptake in macrophages and suggest that the extract could modulate the formation of early atherosclerotic lesions.

KEY WORDS: • aged garlic extract • hyperhomocysteinemia • macrophages • scavenger receptor CD36 • foam cells

Hyperhomocysteinemia, or elevated plasma homocysteine (Hcy)5, is an independent risk factor for atherosclerotic vascular disease and atherothrombosis (1–4). The mechanisms by which Hcy exerts its proatherogenic effects are still not completely understood. However, many biological events associated with the development of atherosclerosis have been reported to be promoted by hyperhomocysteinemia. In particular, hyperhomocysteinemia can cause the induction of endothelial dysfunction and activation (5,6), proliferation of vascular smooth muscle cells (7), promotion of lipoprotein oxidation, platelet activation (8), monocyte chemoattractant protein-1 (9) and vascular endothelial growth factor expression (10), and activation of the coagulation (8) and the protein kinase C (PKC)/c-fos signaling pathway (11). All these events participate in the initiation and progression of atherosclerotic lesion and thrombus formation.

During formation of early atherosclerotic lesions, differentiation of macrophages and expression of CD36, a class B scavenger receptor, are crucially involved in the uptake of oxidized low-density lipoprotein (OxLDL) and in foam-cell formation (12,13). CD36 is an 88kDa glycoprotein expressed on platelets, monocytes, macrophages, capillary endothelial cells, and adipocytes (14). The receptor recognizes a variety of ligands, including modified LDL, anionic phospholipids, and long-chain fatty acids (15). It has been shown that CD36 is upregulated by OxLDL via the peroxisome proliferator-activated receptor-{gamma} (PPAR{gamma}) pathway (16) and via PKC (15). These findings suggest that CD36 plays an important role in foam-cell formation in atherosclerotic lesions and is therefore an important receptor to modulate.

Garlic (Allium sativum) is one of the oldest plants used as medicine. Aged garlic extract (AGE) is a garlic preparation that has an original manufacturing process leading to enrichment in water soluble cysteinyl moieties and loss of the typical garlic odor. More than 300 articles have been published on the chemical and biological properties of AGE. In particular, AGE and its constituents are claimed to possess beneficial effects for the prevention of various aspects of cancer (17,18) and cardiovascular disease (19–25) that are thought to be at least partly due to its antioxidant and thiol-modifying properties (26,27).

We determined the effects of Hcy on scavenger receptor CD36 expression and foam-cell formation in human monocytes/macrophages (THP-1) using flow cytometry and the effects of AGE on this process. Hcy enhances CD36 expression whereas AGE suppresses it. AGE also inhibits OxLDL uptake into macrophages. Our data suggest that the extract could modulate the formation of early atherosclerotic lesions and therefore may be useful for the prevention of atherosclerosis.


   MATERIAL AND METHODS
TOP
 ABSTRACT
 MATERIAL AND METHODS
RESULTS
 DISCUSSION
 LITERATURE CITED
 
    Chemicals. AGE was provided by Wakunaga Pharmaceuticals. We purchased {alpha}-tocopherol, barbital buffer, dimethyl sulfoxide, dexamethasone, ethylenediaminetetraacetic acid (EDTA), DL-homocysteine (Hcy), and phorbol 12-myristate 13-acetate (PMA) from Sigma-Aldrich. Accutase and RPMI-1640 medium were obtained from PAA Laboratories. Fetal bovine serum, penicillin-streptomycin solution, and 1,1'-dioctadecyl-3,3,3'3'-tetra-methylindocyanide percholorate (DiI) were obtained from Invitrogen. Econo-Pac 10 DG columns and DC protein-assay kits were purchased from Bio-Rad Laboratories. Millex-GP sterilizing filter units (0.22 µm) were obtained from Millipore. Cupric sulfate pentahydrate (CuSO4 5H2O) came from Merck. Fluorescein isothiocyanate (FITC)-conjugated antibody against CD36 came from Immunotech. FITC-conjugated mouse immunoglobulin (Ig)G1 isotypic control was purchased from Beckman Coulter.

    AGE. AGE, manufactured under a license issued by the Japanese Ministry of Health, Labor, and Welfare, was formulated by dipping sliced raw garlic into aqueous ethanol and extracting over 10 mo at room temperature. An analysis of AGE showed the following composition (calculated as dry weight): S-allylcysteine (1.6–2.4 mg/g), alliin (1.7 mg/g), allicin (<0.01 mg/g), and ajoene (<0.01 mg/g) (28).

    Cell culture. Human THP-1 cells were obtained from the American Type Culture Collection. Cells were grown in RPMI-1640 medium supplemented with 10% heat-inactivated fetal bovine serum, 200 units/mL penicillin, and 0.2 g/L streptomycin. Cultures were incubated at 37°C in a humidified 5% CO2 atmosphere for 3–4 d before being used for experiments. Viability of cells used throughout the experiment was >95% as determined by trypan blue exclusion.

    Isolation and modification of LDL. LDL (1.019–1.063 g/mL) was isolated from EDTA plasma of fasting healthy volunteers by sequential ultracentrifugation, desalted through a column (Econo-Pac 10 DG), and sterilized with filtration through a 0.22 µm pore-sized filter. Protein concentration was determined by DC protein-assay kit.

OxLDL was prepared by incubating LDL (0.5 mg/L) with 10 µmol/L CuSO4 overnight at 37°C as described previously (29). The extent of oxidative modified LDL was evaluated by examining relative electrophoretic mobility in an agarose gel and by measuring conjugated dienes at 234 nm as described (29).

OxLDL was labeled using the fluorescent probe DiI according to the methods described by Innerarity et al. (30). Briefly, OxLDL was incubated overnight at 37°C with 50 µL of DiI in dimethyl sulfoxide (3 g/L) for each mg of LDL protein. The labeled OxLDL was then reisolated by ultracentrifugation.

    Flow cytometry analysis for CD36 expression. THP-1 cells (1 x 106 cells in a 6-well plate) in the presence of PMA (10 nmol/L) were incubated with D,L-Hcy (10, 50, or 200 µmol/L) and/or AGE (5 g/L) for 72 h. D,L-Hcy was freshly added to the system every 24 h. After incubation for 72 h, cells were washed with phosphate buffered saline (PBS) 3 times, and detached from the culture plate using accutase at 37°C for 10 min. Floating cells were collected and centrifuged at 2000 x g for 5 min at 4°C, washed with ice-cold PBS, and centrifuged again. The pellet was resuspended in PBS containing 1% bovine serum albumin, and incubated on ice for 50 min with a FITC-conjugated antibody against CD36, or the respective isotype control. The cells were then washed with ice-cold PBS to remove the unbound antibody, and fixed using 2% paraformaldehyde. The samples were analyzed on a Becton Dickinson FACScan (FACS), using CellQuest software. Dexamethasone, an inhibitor of macrophage differentiation, was used as a negative control.

    DiI-OxLDL uptake into macrophages. THP-1 cells (1 x 106 cells in a 6-well plate) in the presence of PMA (10 nmol/L) were incubated with D,L-Hcy (200 µmol/L) or AGE (5 g/L) for 72 h. Cells were washed with PBS 3 times and incubated with DiI-OxLDL (50 mg/L) for 3 h. After incubation, cells were washed with PBS, detached from the culture plate as described above, and fixed using 2% paraformaldehyde. The fluorescence was measured by FACS. {alpha}-Tocopherol, an antioxidant known to inhibit oxidized-LDL uptake, was used as a negative control.

    Statistical analysis. Results were expressed as the mean ± SEM. Data were analyzed using one-tailed Student's t test (Microsoft Excel). Differences were considered significant at P < 0.05.


   RESULTS
TOP
 ABSTRACT
 MATERIAL AND METHODS
 RESULTS
DISCUSSION
 LITERATURE CITED
 
    Effects of Hcy or AGE on CD36 expression. THP-1 cells in the presence of PMA (10 nmol/L) were incubated with different concentrations of Hcy for 72 h, and CD36 expression was measured by FACS. Hcy incubation (10, 50, or 200 µmol/L) for 72 h led to a dose-dependent increase in CD36 expression up to 141.2% compared with the control at the highest concentration; that significantly differed from control conditions at Hcy concentrations of 50 and 200 µmol/L (Table 1). In a second set of experiments, the effects of coincubation with AGE on CD36 expression in control cells and Hcy-stimulated cells was tested (Table 2). Incubation of THP-1 cells with Hcy (200 µmol/L) for 72 h in the presence of PMA again increased CD36, to 137.8 ± 5.2%, compared with PMA-stimulated cells without Hcy (P < 0.01). Coincubation with AGE (5 g/L) significantly suppressed CD36 expression in control cells to 44.3 ± 2.94% and to 61.8 ± 13.9% compared with Hcy-incubated cells (P < 0.01). Dexamethasone, used as a negative control, markedly suppressed CD36 expression.


View this table:
[in this window]
[in a new window]
  		TABLE 1 Effects of homocysteine on CD36 expression in THP-1–derived macrophages1

 

View this table:
[in this window]
[in a new window]
  		TABLE 2 Effects of homocysteine and/or AGE on CD36 expression in THP-1–derived macrophages1

 
    Effects of Hcy or AGE on OxLDL uptake into macrophages. THP-1 cells in the presence of PMA (10 nmol/L) were incubated with Hcy or AGE for 72 h; the cells were then incubated with DiI-labeled OxLDL for 3 h, and fluorescence intensity was measured by FACS. Hcy did not increase OxLDL uptake. AGE treatment slightly inhibited OxLDL uptake into macrophages to 85.6 ± 2.8% of control conditions (Table 3). {alpha}-Tocopherol, used as a negative control, markedly decreased OxLDL uptake.


View this table:
[in this window]
[in a new window]
  		TABLE 3 Effects of Hcy or AGE on DiI-labeled oxidized LDL (50 mg/L) uptake in THP-1–derived macrophages1

 

   DISCUSSION
TOP
 ABSTRACT
 MATERIAL AND METHODS
 RESULTS
 DISCUSSION
LITERATURE CITED
 
Hyperhomocysteinemia is an independent risk factor for atherosclerotic vascular disease and atherothrombosis (1–4). It has been shown to induce several functional changes in vascular cells, leading to endothelial cell dysfunction and activation (5,6), smooth-muscle cell proliferation (7), monocyte attraction (9), and monocyte adhesion to endothelial cells (4).

In addition, homocysteine has been shown to increase atherosclerotic lesion size and complexity in atherosclerosis-prone mouse models like the apolipoprotein E-deficient mouse (31,32). The adhesion of peripheral blood monocytes to the vascular endothelium, followed by their migration into the vessel wall and differentiation into cholesterol-scavenging macrophages, is crucially involved in these processes. We studied whether Hcy promotes monocyte differentiation and CD36 scavenger receptor expression, and whether AGE has any impact on this.

We demonstrated that Hcy could enhance CD36 expression in PMA-stimulated THP-1 cells in a dose-dependent manner. CD36 is a class-B scavenger receptor and is expressed by monocytes and/or macrophages, platelets, and microvascular endothelial cells (14). It plays an important role in the uptake of OxLDL and foam-cell formation (33). Expression of CD36 has been shown to be regulated through the PPAR{gamma} pathway and to be directly correlated with the maturational stage of the cell. PMA (a common protein kinase C activator), interleukin-4, and macrophage-colony–stimulating factor, induce monocyte expression of CD36 through activation of PPAR{gamma} (34). In addition, PKC agonists like PMA activate the mitogen-activated protein (MAP) kinase signal transduction pathway. MAP kinases induce the extracellular signal-regulated kinases 1 and 2 as well as the stress-induced kinases Jun NH2-terminal kinase and p38. It has been demonstrated that Hcy regulates activation of PKC in macrophages, the Jun NH2-terminal kinase signal pathway in human endothelial cells (35), and extracellular signal-regulated kinase-1 and -2 phosphorylation in smooth-muscle cells (36).

Hcy-induced production of free radicals has been indicated as one of the mechanisms causing cell damage in the vascular wall (37). Superoxide dismutase, an Formula scavenger, might be able to eliminate the cytotoxic effect of Hcy caused by the cellular Formula formation (37). Oxidative stress due to the overproduction of Formula has been proposed to play a role in Hcy-induced endothelial cell injury and monocytes differentiation into macrophages (4,5,37). These findings suggest that oxidative stress caused by overproduction of reactive oxygen species and/or activation of the PKC-MAP kinase pathway through PPAR{gamma} activation might be the mechanism by which Hcy contributes to the activation of CD36 and formation of atherosclerotic lesions.

AGE and its constituents have been previously reported to have several biological activities, including antioxidant properties (26–29), inhibition of carcinogenesis (17,18), and prevention of cardiovascular diseases (19–25). AGE as compared with a placebo can inhibit the rate of progression of coronary calcification as measured by electron-beam tomography in patients with coronary artery disease (25). We demonstrated that AGE inhibited Hcy-induced CD36 expression, and the extract also slightly inhibited OxLDL uptake into macrophages. However, our data also showed that the inhibitory effects of AGE on CD36 expression and OxLDL uptake did not completely parallel.

PPARs regulate the cellular uptake pathways of oxidized lipoproteins, modulate signaling pathways activated by these particles, and potently influence cholesterol homeostasis in macrophages. PPAR{alpha} and {gamma} regulate scavenger receptors such as CD36 and scavenger receptor class A in an opposite manner and as such, do not promote foam-cell formation (38).

However, PPAR{alpha} and {gamma} agonists stimulate cholesterol efflux from macrophage-derived foam cells by upregulating CLA-1 and /or scavenger receptor class B type I and ATP-binding cassette transporter A1, two proteins involved in the first steps of reverse cholesterol transport (38). These suggest that CD36 is a major and important scavenger receptor, however, the mechanisms of foam-cell formation could be complicated, and AGE might show some multiple effects on the formation of early atherosclerotic lesions.

Additional preliminary data indicate that AGE inhibits monocyte differentiation into macrophages as indicated by decreased expression of CD11b, a marker of macrophage differentiation. AGE treatment of THP-1 cells also inhibits CD36 expression induced by troglitazone, a PPAR{gamma} agonist (data not shown). The extract and its constituents are also reported to minimize intracellular oxidative stress in endothelial cells and macrophages (27,39). The data suggest that AGE has multiple effects on the formation of early atherosclerotic lesions, and it could inhibit monocyte differentiation into macrophages, CD36 expression, and OxLDL uptake into macrophages, as a PKC inhibitor or PPAR{gamma} antagonist (Fig. 1).


Figure 1
View larger version (27K):
[in this window]
[in a new window]
  		FIGURE 1  Mechanisms by which Hcy upregulates and AGE downregulates CD36 expressions. Hcy enhances CD36 expression in THP-1–derived macrophages, presumably through the activation of the PPAR{gamma} pathway. AGE inhibits monocytes differentiation into macrophages, CD36 expression, OxLDL uptake into macrophages, and reverses CD36 expression induced by troglitazone, a PPAR{gamma} agonist. AGE works as a PKC inhibitor or PPAR{gamma} antagonist, and may thereby show multiple effects on the formation of early atherosclerotic lesions.

 
In conclusion, we demonstrated that Hcy induces CD36 expression and that AGE suppresses it. In addition, AGE slightly inhibits OxLDL uptake into macrophages. Our data suggest that the extract could modulate the formation of early atherosclerotic lesions and may be useful for the prevention of atherosclerotic vascular diseases.


   FOOTNOTES
 
1 Published in a supplement to The Journal of Nutrition. Presented at the symposium "Significance of Garlic and Its Constituents in Cancer and Cardiovascular Disease" held April 9–11, 2005 at Georgetown University, Washington, DC. The symposium was sponsored by Strang Cancer Prevention Center, affiliated with Weill Medical College of Cornell University, and Harbor-UCLA Medical Center, and co-sponsored by American Botanical Council, American Institute for Cancer Research, American Society for Nutrition, Life Extension Foundation, General Nutrition Centers, National Nutritional Foods Association, Society of Atherosclerosis Imaging, Susan Samueli Center for Integrative Medicine at the University of California, Irvine. The symposium was supported by Alan James Group, LLC, Agencias Motta, S.A., Antistress AG, Armal, Birger Ledin AB, Ecolandia Internacional, Essential Sterolin Products (PTY) Ltd., Grand Quality LLC, IC Vietnam, Intervec Ltd., Jenn Health, Kernpharm BV, Laboratori Mizar SAS, Magna Trade, Manavita B.V.B.A., MaxiPharm A/S, Nature's Farm, Naturkost S. Rui a.s., Nichea Company Limited, Nutra-Life Health & Fitness Ltd., Oy Valioravinto Ab, Panax, PT. Nutriprima Jayasakti, Purity Life Health Products Limited, Quest Vitamins, Ltd., Sabinco S.A., The AIM Companies, Valosun Ltd., Wakunaga of America Co. Ltd., and Wakunaga Pharmaceutical Co., Ltd. Guest editors for the supplement publication were Richard Rivlin, Matthew Budoff, and Harunobu Amagase. Guest Editor Disclosure: R. Rivlin has been awarded research grants from Wakunaga of America, Ltd. and received an honorarium for serving as co-chair of the conference; M. Budoff has been awarded research grants from Wakunaga of America, Ltd. and received an honorarium for serving as co-chair of the conference; and Harunobu Amagase is employed by Wakunaga of America, Ltd. Back

2 Author disclosure: No relationships to disclose. Back

3 Supported by Wakunaga of America, Mission Viejo, CA. Back

5 Abbreviations used: AGE, aged garlic extract; CD36, cluster determinant 36; DiI, 1,1'-dioctadecyl-3,3,3'3'-tetra-methylindocyanide percholorate; FACS, Becton Dickinson FACscan; FITC, fluorescein isothiocyanate; Hcy, homocysteine; MAP, mitogen-activated protein; OxLDL, oxidized low-density lipoprotein; PBS, phosphate buffered saline; PKC, protein kinase C; PMA, phorbol 12-myristate 13-acetate; PPAR, peroxisome proliferator-activated receptor{gamma}; THP-1, human monocytic leukemia cell line. Back


   LITERATURE CITED
TOP
 ABSTRACT
 MATERIAL AND METHODS
 RESULTS
 DISCUSSION
 LITERATURE CITED
 

1. Duell PB, Mailinow MR. Homocyst(e)ine: an important risk factor for atherosclerotic vascular diseases. Curr Opin Lipidol. 1997;8:28–34.[Medline]

2. Refsum H, Ueland PM, Nygard O, Vollset SE. Homocysteine and cardiovascular disease. Annu Rev Med. 1998;49:31–62.[Medline]

3. Weiss N, Keller C, Hoffmann U, Loscalzo J. Endothelial dysfunction and atherothrombosis in mild hyperhomocysteinemia. Vasc Med. 2002;7:227–39.[Abstract/Free Full Text]

4. Weiss N. Mechanisms of increased vascular oxidant stress in hyperhomocysteinemia and its impact on endothelial function. Curr Drug Metab. 2005;6:27–36.[Medline]

5. Zhang X, Li H, Jin H, Ebin Z, Brodsky S, Goligorsky MS. Effects of homocysteine on endothelial nitric oxide production. Am J Physiol Renal Physiol. 2000;279:F671–678.[Abstract/Free Full Text]

6. Weiss N, Zhang YY, Heydrick S, Bierl C, Loscalzo J. Overexpression of cellular glutathione peroxidase rescues homocyst(e)ine-induced endothelial dysfunction. Proc Natl Acad Sci USA. 2001;98:12503–8.[Abstract/Free Full Text]

7. Tsai JC, Perrella MA, Yoshizumi M, Hsieh CM, Haber E, Schlegel R, Lee ME. Promotion of vascular smooth muscle cell growth by homocysteine: a link to atherosclerosis. Proc Natl Acad Sci U S A. 1994;91:6369–73.[Abstract/Free Full Text]

8. Durand P, Lussier-Cacan S, Blache D. Acute methionine load-induced hyperhomocysteinemia enhances platelet aggregation, thromboxane biosynthesis, and macrophage-derived tissue factor activity in rats. FASEB J. 1997;11:1157–68.[Abstract]

9. Wang G, Siow YL, O K. Homocysteine stimulates nuclear factor kappaB activity and monocyte chemoattractant protein-1 expression in vascular smooth-muscle cells: a possible role for protein kinase C. Biochem J. 2000;352:817–26.

10. Maeda M, Yamamoto I, Fujio Y, Azuma J. Homocysteine induces vascular endothelial growth factor expression in differentiated THP-1 macrophages. Biochim Biophys Acta. 2003;1623:41–6.[Medline]

11. Dalton ML, Gadson PF, Jr., Wrenn RW, Rosenquist TH. Homocysteine signal cascade: production of phospholipids, activation of protein kinase C, and the induction of c-fos and c-myb in smooth muscle cells. FASEB J. 1997;11:703–11.[Abstract]

12. Schaffner T, Taylor K, Bartucci J, Fischer-Dzoga K, Beeson JH, Glagov S, Wissler RW. Arterial foam cells with distinctive immunomorphologic and histochemical features of macrophages. Am J Pathol. 1980;100:57–80[Abstract]

13. Endemann G, Stanton LW, Madden KS, Bryant CM, White RT, Protter AA. CD36 is a receptor for oxidized low density lipoprotein. J Biol Chem. 1993;268:11811–6.[Abstract/Free Full Text]

14. Greenwalt DE, Lipsky RH, Ockenhouse CF, Ikeda H, Tandon NN, Jamieson GA. Membrane glycoprotein CD36: a review of its roles in adherence, signal transduction, and transfusion medicine. Blood. 1992;80:1105–15.[Free Full Text]

15. Feng J, Han J, Pearce SF, Silverstein RL, Gotto AM Jr, Hajjar DP, Nicholson AC. Induction of CD36 expression by oxidized LDL and IL-4 by a common signaling pathway dependent on protein kinase C and PPAR-gamma. J Lipid Res. 2000;41:688–96.[Abstract/Free Full Text]

16. Nagy L, Tontonoz P, Alvarez JG, Chen H, Evans RM. OxLDL regulates macrophage gene expression through ligand activation of PPAR gamma. Cell. 1998;93:229–40.[Medline]

17. Nishino H, Iwashima A, Itakura Y, Matsuura H, Fuwa T. Antitumor-promoting activity of garlic extracts. Oncology. 1989;46:277–80.[Medline]

18. Tanaka S, Haruma K, Kunihiro M, Nagata S, Kitadai Y, Manabe N, Sumii M, Yoshihara M, Kajiyama G, Chayama K. Effects of aged garlic extract (AGE) on colorectal adenomas: a double-blinded study. Hiroshima J Med Sci. 2004;53:39–45.[Medline]

19. Ide N, Nelson AB, Lau BH. Aged garlic extract and its constituents inhibit Cu2+-induced oxidative modification of low density lipoprotein. Planta Med. 1997;63:263–4.[Medline]

20. Ide N, Lau BH. Garlic compounds protect vascular endothelial cells from oxidized low density lipoprotein-induced injury. J Pharm Pharmacol. 1997;49:908–11.[Medline]

21. Efendy JL, Simmons DL, Campbell GR, Campbell JH. The effect of the garlic extract, ‘Kyolic’, on the development of experimental atherosclerosis. Atherosclerosis. 1997;132:37–42.[Medline]

22. Lau BH. Suppression of LDL oxidation by garlic. J Nutr. 2001;131:985S–8S.[Abstract/Free Full Text]

23. Rahman K, Billington D. Dietary supplementation with aged garlic extract inhibits ADP-induced platelet aggregation in humans. J Nutr. 2000;130:2662–5.[Abstract/Free Full Text]

24. Steiner M, Khan AH, Holbert D, Lin RI. A double-blind crossover study in moderately hypercholesterolemic men that compared the effect of aged garlic extract and placebo administration on blood lipids. Am J Clin Nutr. 1996;64:866–70.[Abstract/Free Full Text]

25. Budoff MJ, Takasu J, Flores FR, Niihara Y, Lu B, Lau BH, Rosen RT, Amagase H. Inhibiting progression of coronary calcification using Aged Garlic Extract in patients receiving statin therapy: a preliminary study. Prev Med. 2004;39:985–91.[Medline]

26. Wei Z, Lau BH. Garlic inhibits free radical generation and augments antioxidant enzyme activity in vascular endothelial cells. Nutr Res. 1998;18:61–70.

27. Ide N, Lau BH. Aged garlic extract attenuates intracellular oxidative stress. Phytomedicine. 1999;6:125–31.[Medline]

28. Imai J, Ide N, Nagae S, Moriguchi T, Matsuura H, Itakura Y. Antioxidant and radical scavenging effects of aged garlic extract and its constituents. Planta Med. 1994;60:417–20.[Medline]

29. Jialal I, Fuller CJ, Huet BA. The effect of alpha-tocopherol supplementation on LDL oxidation. A dose-response study. Arterioscler Thromb Vasc Biol. 1995;15:190–8.[Abstract/Free Full Text]

30. Innerarity TL, Pitas RE, Mahley RW. Lipoprotein receptor interactions. Methods Enzymol. 1986;129:542–65.[Medline]

31. Hofmann MA, Lalla E, Lu Y, Gleason MR, Wolf BM, Tanji N, Ferran LJ Jr, Kohl B, Rao V, et al. Hyperhomocysteinemia enhances vascular inflammation and accelerates atherosclerosis in a murine model. J Clin Invest. 2001;107:675–83.[Medline]

32. Wang H, Jiang X, Yang F, Gaubatz JW, Ma L, Magera MJ, Yang X, Berger PB, Durante W, et al. Hyperhomocysteinemia accelerates atherosclerosis in cystathionine beta-synthase and apolipoprotein E double knock-out mice with and without dietary perturbation. Blood. 2003;357:233–40.

33. Nicholson AC. Expression of CD36 in macrophages and atherosclerosis: the role of lipid regulation of PPAR{gamma} signaling. Trends Cardiovasc Med. 2004;14:8–12.[Medline]

34. Huang JT, Welch JS, Ricote M, Binder CJ, Willson TM, Kelly C, Witztum JL, Funk CD, Conrad D, Glass CK. Interleukin-4-dependent production of PPAR-gamma ligands in macrophages by 12/15-lipoxygenase. Nature. 1999;400:378–82.[Medline]

35. Cai Y, Zhang C, Nawa T, Aso T, Tanaka M, Oshiro S, Ichijo H, Kitajima S. Homocysteine-responsive ATF3 gene expression in human vascular endothelial cells: activation of c-Jun NH2-terminal kinase and promoter response element. Blood. 2000;96:2140–8.[Abstract/Free Full Text]

36. Woo DK, Dudrick SJ, Sumpio BE. Homocystiene stimulates MAP kinase in bovine aortic smooth muscle cells. Surgery. 2000;128:59–66.[Medline]

37. Loscalzo J. The oxidant stress of hyperhomocysteinemia. J Clin Invest. 1996;98:5–7.[Medline]

38. Duval C, Chinetti G, Trottein F, Frucart JC, Staels B. The role of PPARs in atherosclerosis. Trends Mol Med. 2002;8:422–30.[Medline]

39. Ide N, Lau BH. Garlic compounds minimize intracellular oxidative stress and inhibit nuclear factor-kB activation. J Nutr. 2001;131:1020S–6S.[Abstract/Free Full Text]





This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Purchase Article
Right arrow View Shopping Cart
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Ide, N.
Right arrow Articles by Weiss, N.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ide, N.
Right arrow Articles by Weiss, N.

Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
Copyright © 2006 by American Society for Nutrition