Effects of lycopene on the induction of foam cell formation by modified LDL

Effects of Dietary Lycopene on the Growth Performance, Antioxidant Capacity, Meat Quality, Intestine Histomorphology, and Cecal Microbiota in Broiler Chickens

The experiment aimed to investigate the effects of dietary lycopene on the growth performance, antioxidant capacity, meat quality, intestine histomorphology, and cecal microbiota in broiler chickens. We randomly divided five hundred and seventy-six one-day-old male broilers into four groups each with six replicates and 24 chickens in each replicate. The control group (CG) was fed the basal diet, and the other groups were given powder lycopene of 10, 20, and 30 mg/kg lycopene (LP10, LP20, and LP30, respectively). Compared with the control group, (1) the dietary lycopene increased (p = 0.001) the average daily gain and decreased (p = 0.033) the feed conversion ratio in the experimental groups; (2) the glutathione peroxidase enzyme contents in LP20 were higher (p =< 0.001) in myocardium; (3) the crude protein contents were higher (p = 0.007) in the group treated with 30 mg/kg dietary lycopene; (4) the jejunum villous height was higher (p = 0.040) in LP20; (5) the Unclassified-f-Ruminococcaceae relative abundance was significantly higher (p = 0.043) in LP20. In this study, adding 20 mg/kg dietary lycopene to the broiler chickens' diets improved the growth performance, antioxidant capacity, meat quality, intestine histomorphology, and cecal microbiota in broiler chickens.

Beneficial Effects of Olive Oil Enriched with Lycopene on the Plasma Antioxidant and Anti-Inflammatory Profile of Hypercholesterolemic Patients

Olive oil and lycopene are foods that have potent antioxidant activity. The objective was to determine the effects of consumption of olive oil enriched with lycopene on oxidative stress biomarkers in hypercholesterolemic subjects. We examined the effects of oil enriched with lycopene extract daily intake during 1 month on plasma antioxidant capacity, lipids profile (triacylgycerols, total cholesterol, cHDL; cLDL, ox-LDL), biomarkers of oxidative stress, and inflammatory markers related with atherosclerosis risk (C-reactive protein (CRP), IL-6; sDC4L) in subjects hypercholesteremics (cholesterol > 220 mg/dL). In the group consuming olive oil-lycopene, significant increases (p < 0.05) in the levels of plasma lycopene concentration (0.146 ± 0.03 versus 0.202 ± 0.04 (µmol/L)), α-carotene (0.166 ± 0.064 versus 0.238 ± 0.07) and in β-carotene (0.493 ± 0.187 versus 0.713 ± 0.221) were observed. These results are linked with the increases of plasma antioxidants and decreases biomarkers of oxidative stress (carbonyl groups, malondialdehyde and 8-hydroxy-deoxiguanosine) observed in hypercholesterolemic group. In relation to lipid profile, a significant decrease was observed in the levels of ox-LDL (781 ± 302 versus 494 ± 200), remaining unchanged the levels of TG, cholesterol, HDL and LDL-c. Regarding inflammatory biomarkers, the levels of CRP and IL-6 decreased significantly. The positive results obtained in this study support the use of olive oil enriched with lycopene to reduce the risk of coronary disease.

Trained immunity in monocyte/macrophage: Novel mechanism of phytochemicals in the treatment of atherosclerotic cardiovascular disease

Atherosclerosis (AS) is the pathology of atherosclerotic cardiovascular diseases (ASCVD), characterized by persistent chronic inflammation in the vessel wall, in which monocytes/macrophages play a key role. It has been reported that innate immune system cells can assume a persistent proinflammatory state after short stimulation with endogenous atherogenic stimuli. The pathogenesis of AS can be influenced by this persistent hyperactivation of the innate immune system, which is termed trained immunity. Trained immunity has also been implicated as a key pathological mechanism, leading to persistent chronic inflammation in AS. Trained immunity is mediated via epigenetic and metabolic reprogramming and occurs in mature innate immune cells and their bone marrow progenitors. Natural products are promising candidates for novel pharmacological agents that can be used to prevent or treat cardiovascular diseases (CVD). A variety of natural products and agents exhibiting antiatherosclerotic abilities have been reported to potentially interfere with the pharmacological targets of trained immunity. This review describes in as much detail as possible the mechanisms involved in trained immunity and how phytochemicals of this process inhibit AS by affecting trained monocytes/macrophages.

The Effect of Dietary Lycopene Supplementation on Drip Loss during Storage of Lamb Meat by iTRAQ Analysis

This study was designed to investigate the impact of dietary lycopene (antioxidant extracted from tomato) supplementation on postmortem antioxidant capacity, drip loss and protein expression profiles of lamb meat during storage. Thirty male Hu lambs were randomly divided into three treatment groups and housed in individual pens and received 0, 200 or 400 mg·kg⁻¹ lycopene in their diet, respectively. All lambs were slaughtered after 3 months of fattening, and the longissimus thoracis (LT) muscle was collected for analyses. The results indicated that drip loss of LT muscle increased with storage days (P < 0.05). After storage for 7 days, significantly lower drip loss of meat was found in fed the lycopene-supplemented diet (P < 0.05). Dietary lycopene supplementation increased the activity of antioxidant enzymes (total antioxidant capacity (T-AOC), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT)) (P < 0.05) and decreased the thiobarbituric acid reactive substance (TBARS) and carbonyl contents (P < 0.05). During the storage period (days 0, 5 and 7), a number of differentially abundant proteins (DAPs), including oxidases, metabolic enzymes, calcium channels and structural proteins, were identified based on iTRAQ data, with roles predominantly in carbon metabolism, oxidative phosphorylation, cardiac muscle contraction and proteasome pathways, and which contribute to decreased drip loss of lamb meat during storage. It can be concluded that dietary lycopene supplementation increased antioxidant capacity after slaughter, and the decreased drip loss during postmortem storage might occur by changing the expression of proteins related to enzyme activity and cellular structure in lamb muscle.

Lycopene in protection against obesity and diabetes: A mechanistic review

Lycopene, a natural pigment that mainly exists in the mature fruit of tomatoes, has gained increasing attention due to its protective effects against obesity and diabetes. The aim of this review is to summarize the potential mechanisms in which lycopene exerts protection against obesity and diabetes, along with highlighting its bioavailability, synthesis and safety. Literature sources used in this review were from the PubMed Database, China Knowledge Resource Integrated Database, China Science and Technology Journal Database, National Science and Technology Library, Wanfang Data, and the Web of Science. For the inquiries, keywords such as lycopene, properties, synthesis, diabetes, obesity, and safety were used in various combinations. About 200 articles and reviews were evaluated. Lycopene exhibits anti-obesity and anti-diabetic activities in different organs and/or tissues, including adipose tissue, liver, kidney, pancreas, brain, ovaries, intestine, and eyes. The underlying mechanism may be attributed to its anti-oxidant and anti-inflammatory properties and through its ability to regulate of AGE/RAGE, JNK/MAPK, PI3K/Akt, SIRT1/FoxO1/PPARγ signaling pathways and AchE activity. The epidemiological investigations support that lycopene consumption may contribute to lowering the risk of obesity and diabetes. The cis-isomers of lycopene are more bioavailable and better absorbed than trans-lycopene, and mainly distribute in liver and adipose tissue. Lycopene exhibits a good margin of safety and can be obtained by plant extraction, chemical synthesis and microbial fermentation. In summary, lycopene consumption beneficially contributes to protecting against diabetes and obesity in animal studies and epidemiological investigations, which supports the potential of this compound as a preventive/therapeutic agent against these disorders. Well-designed, prospective clinical studies are warranted to evaluate the potential therapeutic effect of lycopene against common metabolic diseases.

Targeting Foam Cell Formation in Atherosclerosis: Therapeutic Potential of Natural Products

Foam cell formation and further accumulation in the subendothelial space of the vascular wall is a hallmark of atherosclerotic lesions. Targeting foam cell formation in the atherosclerotic lesions can be a promising approach to treat and prevent atherosclerosis. The formation of foam cells is determined by the balanced effects of three major interrelated biologic processes, including lipid uptake, cholesterol esterification, and cholesterol efflux. Natural products are a promising source for new lead structures. Multiple natural products and pharmaceutical agents can inhibit foam cell formation and thus exhibit antiatherosclerotic capacity by suppressing lipid uptake, cholesterol esterification, and/or promoting cholesterol ester hydrolysis and cholesterol efflux. This review summarizes recent findings on these three biologic processes and natural products with demonstrated potential to target such processes. Discussed also are potential future directions for studying the mechanisms of foam cell formation and the development of foam cell-targeted therapeutic strategies.

Lycopene and Vascular Health

Lycopene is a lipophilic, unsaturated carotenoid, found in red-colored fruits and vegetables, including tomatoes, watermelon, papaya, red grapefruits, and guava. The present work provides an up to date overview of mechanisms linking lycopene in the human diet and vascular changes, considering epidemiological data, clinical studies, and experimental data. Lycopene may improve vascular function and contributes to the primary and secondary prevention of cardiovascular disorders. The main activity profile of lycopene includes antiatherosclerotic, antioxidant, anti-inflammatory, antihypertensive, antiplatelet, anti-apoptotic, and protective endothelial effects, the ability to improve the metabolic profile, and reduce arterial stiffness. In this context, lycopene has been shown in numerous studies to exert a favorable effect in patients with subclinical atherosclerosis, metabolic syndrome, hypertension, peripheral vascular disease, stroke and several other cardiovascular disorders, although the obtained results are sometimes inconsistent, which warrants further studies focusing on its bioactivity.

Cardiovascular benefits of lycopene: fantasy or reality?

Epidemiological evidence indicates that high consumption of tomatoes and tomato-based products reduces the risk of chronic diseases such as CVD and cancer. Such potential benefits are often ascribed to high concentrations of lycopene present in tomato products. Mainly from the results of in vitro studies, potential biological mechanisms by which carotenoids could protect against heart disease and cancer have been suggested. These include cholesterol reduction, inhibition of oxidation processes, modulation of inflammatory markers, enhanced intercellular communication, inhibition of tumourigenesis and induction of apoptosis, metabolism to retinoids and antiangiogenic effects. However, with regard to CVD, results from intervention studies gave mixed results. Over fifty human intervention trials with lycopene supplements or tomato-based products have been conducted to date, the majority being underpowered. Many showed some beneficial effects but mostly on non-established cardiovascular risk markers such as lipid peroxidation, DNA oxidative damage, platelet activation and inflammatory markers. Only a few studies showed improvement in lipid profiles, C reactive protein and blood pressure. However, recent findings indicate that lycopene could exert cardiovascular protection by lowering HDL-associated inflammation, as well as by modulating HDL functionality towards an antiatherogenic phenotype. Furthermore, in vitro studies indicate that lycopene could modulate T lymphocyte activity, which would also inhibit atherogenic processes and confer cardiovascular protection. These findings also suggest that HDL functionality deserves further consideration as a potential early marker for CVD risk, modifiable by dietary factors such as lycopene.

Effects of recombinant lycopene dietary supplement on the egg quality and blood characteristics of laying quails

This study was conducted to determine the effect of dietary supplement of bacterial lycopene (BL) produced by Escherichia coli on the egg quality and blood characteristics of laying quails. The antioxidant activity measurement showed that BL exhibited 100% 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging capacity at a concentration of 4.65 μg/ml, which was more effective than butylated hydroxytoluene (BHT) and commercial lycopene (CL). Moreover, seven dietary groups of laying quails consisting of 10 100-day-old quails (Coturnix coturnix japonica) each were fed with the basal diet supplemented with BL, CL or canthaxanthin (CA) for 4 weeks. Consequently, the triglyceride content of yolk was significantly lower in the group with BL and CL supplement. The serum malondialdehyde (MDA) level of the BL- and CA-supplemented groups at 18 mg/kg was lower than the control group. In conclusion, BL has a high antioxidant activity and is promising as a feed additive in the diet of laying quails.

Effects of Dietary Lycopene Supplementation on Plasma Lipid Profile, Lipid Peroxidation and Antioxidant Defense System in Feedlot Bamei Lamb

Lycopene, a red non-provitamin A carotenoid, mainly presenting in tomato and tomato byproducts, has the highest antioxidant activity among carotenoids because of its high number of conjugated double bonds. The objective of this study was to investigate the effect of lycopene supplementation in the diet on plasma lipid profile, lipid peroxidation and antioxidant defense system in feedlot lamb. Twenty-eight Bamei male lambs (90 days old) were divided into four groups and fed a basal diet (LP0, 40:60 roughage: concentrate) or the basal diet supplemented with 50, 100, and 200 mg/kg lycopene. After 120 days of feeding, all lambs were slaughtered and sampled. Dietary lycopene supplementation significantly reduced the levels of plasma total cholesterol (p<0.05, linearly), total triglycerides (TG, p<0.05) and low-density lipoprotein cholesterol (LDL-C, p<0.05), as well as atherogenic index (p<0.001), whereas no change was observed in high-density lipoprotein cholesterol (p>0.05). The levels of TG (p<0.001) and LDL-C (p<0.001) were decreased with the feeding time extension, and both showed a linear trend (p<0.01). Malondialdehyde level in plasma and liver decreased linearly with the increase of lycopene inclusion levels (p<0.01). Dietary lycopene intake linearly increased the plasma antioxidant vitamin E level (p<0.001), total antioxidant capacity (T-AOC, p<0.05), and activities of catalase (CAT, p<0.01), glutathione peroxidase (GSH-Px, p<0.05) and superoxide dismutase (SOD, p<0.05). The plasma T-AOC and activities of GSH-Px and SOD decreased with the extension of the feeding time. In liver, dietary lycopene inclusion showed similar antioxidant effects with respect to activities of CAT (p<0.05, linearly) and SOD (p<0.001, linearly). Therefore, it was concluded that lycopene supplementation improved the antioxidant status of the lamb and optimized the plasma lipid profile, the dosage of 200 mg lycopene/kg feed might be desirable for growing lambs to prevent environment stress and maintain normal physiological metabolism.

The inhibition of macrophage foam cell formation by 9-cis β-carotene is driven by BCMO1 activity

Atherosclerosis is a major cause of morbidity and mortality in developed societies, and begins when activated endothelial cells recruit monocytes and T-cells from the bloodstream into the arterial wall. Macrophages that accumulate cholesterol and other fatty materials are transformed into foam cells. Several epidemiological studies have demonstrated that a diet rich in carotenoids is associated with a reduced risk of heart disease; while previous work in our laboratory has shown that the 9-cis β-carotene rich alga Dunaliella inhibits atherogenesis in mice. The effect of 9-cis β-carotene on macrophage foam cell formation has not yet been investigated. In the present work, we sought to study whether the 9-cis β-carotene isomer, isolated from the alga Dunaliella, can inhibit macrophage foam cell formation upon its conversion to retinoids. The 9-cis β-carotene and Dunaliella lipid extract inhibited foam cell formation in the RAW264.7 cell line, similar to 9-cis retinoic acid. Furthermore, dietary enrichment with the algal powder in mice resulted in carotenoid accumulation in the peritoneal macrophages and in the inhibition of foam cell formation ex-vivo and in-vivo. We also found that the β-carotene cleavage enzyme β-carotene 15,15’-monooxygenase (BCMO1) is expressed and active in macrophages. Finally, 9-cis β-carotene, as well as the Dunaliella extract, activated the nuclear receptor RXR in hepa1-6 cells. These results indicate that dietary carotenoids, such as 9-cis β-carotene, accumulate in macrophages and can be locally cleaved by endogenous BCMO1 to form 9-cis retinoic acid and other retinoids. Subsequently, these retinoids activate the nuclear receptor RXR that, along with additional nuclear receptors, can affect various metabolic pathways, including those involved in foam cell formation and atherosclerosis.

Lycopene, a powerful antioxidant, significantly reduces the development of the adhesion phenotype

Postoperative adhesions are a common medical complication of gynecologic and other pelvic surgeries resulting in persistent pelvic pain, obstruction of the intestines, and even infertility. The molecular mechanisms of postoperative adhesion development remain to be elucidated. We have recently described a role for reactive oxygen species, specifically superoxide, in the development of postoperative adhesions. In this study, we sought to determine whether lycopene, a potent antioxidant, reduces markers characteristic of the adhesion phenotype. Primary fibroblast cultures from normal peritoneum and adhesion tissues were utilized to determine mRNA levels of adhesion phenotype markers type I collagen, transforming growth factor-beta 1 (TGF-β1), and vascular endothelial growth factor (VEGF) in response to lycopene (24 hours, 10 μM) treatment. There was a 2 (p < 0.003), 4.7 (p < 0.004), and 1.6 fold (p < 0.004) increase in mRNA levels of type I collagen, TGF-β1, and VEGF, respectively, in adhesion as compared to normal peritoneal fibroblasts. Lycopene treatment led to a 6.8 and a 12.4 fold decrease in type I collagen mRNA levels, in normal peritoneal and adhesion fibroblasts, respectively (p < 0.005). Lycopene treatment led to a 4.2 (p < 0.03) and a 4.6 (p < 0.05) fold decrease in VEGF mRNA levels, in normal peritoneal and adhesion fibroblasts, respectively. Lycopene treatment led to a 7.0 fold decrease in TGF-β1 mRNA levels, in adhesion fibroblasts (p < 0.03). A 1.9 fold decrease in TGF-β1 mRNA was observed in normal peritoneal fibroblasts in response to treatment, although it was not significant. Lycopene substantially reduced levels of adhesion phenotype markers in normal peritoneal and adhesion fibroblasts and whether it will reduce postoperative adhesions needs to be further investigated.

Potential beneficial effects of ixmyelocel-T in the treatment of atherosclerotic diseases

Introduction

Advanced atherosclerotic lesions are characterized by lipid accumulation, inflammation, and defective efferocytosis. An ideal therapy should address all aspects of this multifactorial disease. Ixmyelocel-T therapy, an expanded autologous multicellular therapy showing clinical promise in the treatment of diseases associated with advanced atherosclerosis, includes a novel population of M2-like macrophages. Here, we examine the macrophages of ixmyelocel-T and determine their ability to influx modified cholesterol in an atheroprotective manner, maintaining cholesterol homeostasis and preventing cellular dysfunction and death, ultimately promoting reverse cholesterol efflux.

Methods

Approximately 50 ml of whole bone marrow was obtained from healthy donors and shipped overnight. Bone marrow mononuclear cells (BMMNCs) were produced by using density gradient separation and cultured for approximately 12 days to generate ixmyelocel-T. CD14+ cells were isolated from ixmyelocel-T via positive selection for analysis. Ixmyelocel-T and human leukemia monocyte (THP-1) cells were loaded with acetylated low-density lipoprotein (Ac-LDL) for analysis. Flow cytometry and immunofluorescence were used to examine Ac-LDL uptake, expression of cytokines was analyzed by enzyme-linked immunofluorescence assay (ELISA), and quantitative real-time PCR was used to analyze expression of cholesterol-transport genes. Both the in vitro cholesterol efflux assay and in vivo reverse cholesterol transport assay were used to examine cholesterol transport.

Results

Ixmyelocel-T macrophages take up acetylated low-density lipoprotein and express the scavenger receptors CD36 and scavenger receptor-B1 (SR-B1). Ixmyelocel-T did not become apoptotic or proinflammatory after lipid loading. The cholesterol transporter genes ABAC1 and ABCG1 were both statistically significantly upregulated when ixmyelocel-T macrophages were loaded with cholesterol. Ixmyelocel-T also exhibited enhanced apolipoprotein A-I (ApoAI)-mediated cholesterol efflux. In addition, in vivo reverse cholesterol-transport assay demonstrated that ixmyelocel-T was able to efflux cholesterol in this model.

Conclusions

Ixmyelocel-T macrophages influx modified cholesterol, remained anti-inflammatory in the face of lipid loading and inflammatory challenge, and displayed enhanced cholesterol efflux capabilities. These combined features suggest that this autologous multicellular therapy may exert beneficial effects in atherosclerotic diseases.

Dynamic action of carotenoids in cardioprotection and maintenance of cardiac health

Oxidative stress has been considered universally and undeniably implicated in the pathogenesis of all major diseases, including those of the cardiovascular system. Oxidative stress activate transcriptional messengers, such as nuclear factor-κB, tangibly contributing to endothelial dysfunction, the initiation and progression of atherosclerosis, irreversible damage after ischemic reperfusion, and even arrhythmia, such as atrial fibrillation. Evidence is rapidly accumulating to support the role of reactive oxygen species (ROS) and reactive nitrogen species (RNS) as intracellular signaling molecules. Despite this connection between oxidative stress and cardiovascular disease (CVD), there are currently no recognized therapeutic interventions to address this important unmet need. Antioxidants that provide a broad, "upstream" approach via ROS/RNS quenching or free radical chain breaking seem an appropriate therapeutic option based on epidemiologic, dietary, and in vivo animal model data. Short-term dietary intervention trials suggest that diets rich in fruit and vegetable intake lead to improvements in coronary risk factors and reduce cardiovascular mortality. Carotenoids are such abundant, plant-derived, fat-soluble pigments that functions as antioxidants. They are stored in the liver or adipose tissue, and are lipid soluble by becoming incorporated into plasma lipoprotein particles during transport. For these reasons, carotenoids may represent one plausible mechanism by which fruits and vegetables reduce the risk of chronic diseases as cardiovascular disease (CVD). This review paper outlines the role of carotenoids in maintaining cardiac health and cardioprotection mediated by several mechanisms including redox signaling.

Molecular mechanisms for anti-aging by natural dietary compounds

Aging is defined as a normal decline in survival with advancing age; however, the recent researches have showed that physiological functions of the body change during the aging process. Majority of the changes are often subject to a higher risk of developing diseases, such as cardiovascular disease, type II diabetes, Alzheimer's disease, Parkinson's disease, as well as the dysregulated immune and inflammatory disorders. Aging process is controlled by a complicated and precise signaling network that involved in energy homeostasis, cellular metabolism and stress resistance. Over the past few decades, research in natural dietary compounds by various organism and animal models provides a new strategy for anti-aging. Natural dietary compounds act through a variety mechanisms to extend lifespan and prevent age-related diseases. This review summarizes the current understanding on signaling pathways of aging and knowledge and underlying mechanism of natural dietary compounds that provide potential application on anti-aging and improve heath in human.

Lycopene inhibits NF-kB-mediated IL-8 expression and changes redox and PPARγ signalling in cigarette smoke-stimulated macrophages

Increasing evidence suggests that lycopene, the major carotenoid present in tomato, may be preventive against smoke-induced cell damage. However, the mechanisms of such a prevention are still unclear. The aim of this study was to investigate the role of lycopene on the production of the pro-inflammatory cytokine IL-8 induced by cigarette smoke and the possible mechanisms implicated. Therefore, human THP-1 macrophages were exposed to cigarette smoke extract (CSE), alone and following a 6-h pre-treatment with lycopene (0.5–2 µM). CSE enhanced IL-8 production in a time- and a dose-dependent manner. Lycopene pre-treatment resulted in a significant inhibition of CSE-induced IL-8 expression at both mRNA and protein levels. NF-kB controlled the transcription of IL-8 induced by CSE, since PDTC prevented such a production. Lycopene suppressed CSE-induced NF-kB DNA binding, NF-kB/p65 nuclear translocation and phosphorylation of IKKα and IkBα. Such an inhibition was accompanied by a decrease in CSE-induced ROS production and NOX-4 expression. Lycopene further inhibited CSE-induced phosphorylation of the redox-sensitive ERK1/2, JNK and p38 MAPKs. Moreover, the carotenoid increased PPARγ levels which, in turn, enhanced PTEN expression and decreased pAKT levels in CSE-exposed cells. Such effects were abolished by the PPARγ inhibitor GW9662. Taken together, our data indicate that lycopene prevented CSE-induced IL-8 production through a mechanism involving an inactivation of NF-kB. NF-kB inactivation was accompanied by an inhibition of redox signalling and an activation of PPARγ signalling. The ability of lycopene in inhibiting IL-8 production, NF-kB/p65 nuclear translocation, and redox signalling and in increasing PPARγ expression was also found in isolated rat alveolar macrophages exposed to CSE. These findings provide novel data on new molecular mechanisms by which lycopene regulates cigarette smoke-driven inflammation in human macrophages.

Hydrogen sulfide inhibits macrophage-derived foam cell formation

Recent evidence indicates that hydrogen sulfide (H(2)S) exerts an antiatherogenic effect, but the mechanism is unclear. Formation of macrophage-derived foam cells is a crucial event in the development of atherosclerosis. Thus, we explore the effect of H(2)S on the formation of macrophage-derived foam cells. Incubation of monocyte-derived macrophages with oxidized LDL (oxLDL) alone caused significant increases both in intracellular lipids revealed by Oil-red O staining and in intracellular total cholesterol (TC) and esterified cholesterol (EC) concentrations assessed by high-performance liquid chromatography. Sodium hydrosulfide (NaHS, an H(2)S donor) remarkably abrogated oxLDL-induced intracellular lipid accumulation, and attenuated TC and EC concentrations and EC/TC ratio, whereas dl-propargylglycine (PPG) (a H(2)S-generating enzyme cystathionine gamma lyase inhibitor) exacerbated lipid accumulation and augmented TC and EC concentrations and EC/TC ratio. Incubation of 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI)-oxLDL led to lipoprotein binding and uptake of macrophages, which was blunted by NaHS, but enhanced by PPG. Furthermore, OxLDL markedly induced CD36, scavenger receptor A (SR-A) and acyl-coenzyme A:cholesterol acyltransferase-1 (ACAT-1) expressions in macrophages, which was suppressed by NaHS (50-200 μmol/L). Finally, the down-regulations of TC and EC concentrations as well as CD36 and ACAT-1 expressions by NaHS were suppressed by glibenclamide, a K(ATP) channel blocker, but facilitated by PD98059, an extracellular signal-regulated kinases 1 and 2 (ERK1/2) inhibitor. These results suggested that H(2)S inhibits foam cell formation by down-regulating CD36, SR-A and ACAT1 expressions via the K(ATP)/ERK1/2 pathway in human monocyte-derived macrophages.

Carbamylated LDL

Nonenzymatic modification of protein by cyanate, that is, carbamylation, has received new attention due to its apparent relevance in atherosclerosis. For example, carbamylation of low-density lipoprotein (LDL) is an important mechanism that potentially impacts high-risk atherosclerotic individuals with increased urea (renal insufficiency) or thiocyanate (tobacco smoking). Carbamylated LDL (cLDL) is increased in patients with end-stage kidney disease, especially those with atherosclerosis. In addition, cLDL exhibits distinct cytotoxic effects when tested in vitro on endothelial cells, induces the expression of adhesion molecules, and aggravates the monocyte adhesion to endothelial cells. It also facilitates the proliferation of vascular smooth-muscle cell (VSMC). Studies of potential pharmacological interruption of these processes in vivo may lead to discoveries of novel therapies for atherosclerosis.

EGb761 ameliorates the formation of foam cells by regulating the expression of SR-A and ABCA1: role of haem oxygenase-1

AIMS

Accumulation of foam cells in the intima is a hallmark of early-stage atherosclerotic lesions. Ginkgo biloba extract (EGb761) has been reported to exert anti-oxidative and anti-inflammatory properties in atherosclerosis, yet the significance and the molecular mechanisms of action of EGb761 in the formation of macrophage foam cells are not fully understood.

METHODS AND RESULTS

Treatment with EGb761 resulted in a dose-dependent decrease in oxidized low-density lipoprotein (oxLDL)-mediated cholesterol accumulation in macrophages, a consequence that was due to a decrease in cholesterol uptake and an increase in cholesterol efflux. Additionally, EGb761 significantly down-regulated the mRNA and protein expression of class A scavenger receptor (SR-A) by decreasing expression of activator protein 1 (AP-1); however, EGb761 increased the protein stability of ATP-binding cassette transporter A1 (ABCA1) by reducing calpain activity without affecting ABCA1 mRNA expression. Small interfering RNA (siRNA) targeting haem oxygenase-1 (HO-1) abolished the EGb761-induced protective effects on the expression of AP-1, SR-A, ABCA1, and calpain activity. Accordingly, EGb761-mediated suppression of lipid accumulation in foam cells was also abrogated by HO-1 siRNA. Moreover, the lesion size of atherosclerosis was smaller in EGb761-treated, apolipoprotein E-deficient mice compared with the vehicle-treated mice, and the expression of HO-1, SR-A, and ABCA1 in aortas was modulated similar to that observed in macrophages.

CONCLUSION

These findings suggest that EGb761 confers a protection from the formation of foam cells by a novel HO-1-dependent regulation of cholesterol homeostasis in macrophages.