Dietary Neu5Ac Intervention Protects Against Atherosclerosis Associated With Human-Like Neu5Gc Loss-Brief Report.

Objective: Species-specific pseudogenization of the CMAH gene during human evolution eliminated common mammalian sialic acid N-glycolylneuraminic acid (Neu5Gc) biosynthesis from its precursor N-acetylneuraminic acid (Neu5Ac). With metabolic nonhuman Neu5Gc incorporation into endothelia from red meat, the major dietary source, anti-Neu5Gc antibodies appeared. Human-like Ldlr-/-Cmah-/- mice on a high-fat diet supplemented with a Neu5Gc-enriched mucin, to mimic human red meat consumption, suffered increased atherosclerosis if human-like anti-Neu5Gc antibodies were elicited. Approach and Results: We now ask whether interventional Neu5Ac feeding attenuates metabolically incorporated Neu5Gc-mediated inflammatory acceleration of atherogenesis in this Cmah-/-Ldlr-/- model system. Switching to a Neu5Gc-free high-fat diet or adding a 5-fold excess of Collocalia mucoid-derived Neu5Ac in high-fat diet protects against accelerated atherosclerosis. Switching completely from a Neu5Gc-rich to a Neu5Ac-rich diet further reduces severity. Remarkably, feeding Neu5Ac-enriched high-fat diet alone has a substantial intrinsic protective effect against atherosclerosis in Ldlr-/- mice even in the absence of dietary Neu5Gc but only in the human-like Cmah-null background. Conclusions: Interventional Neu5Ac feeding can mitigate or prevent the red meat/Neu5Gc-mediated increased risk for atherosclerosis, and has an intrinsic protective effect, even in the absence of Neu5Gc feeding. These findings suggest that similar interventions should be tried in humans and that Neu5Ac-enriched diets alone should also be investigated further.

12-Hydroxyeicosapentaenoic acid inhibits foam cell formation and ameliorates high-fat diet-induced pathology of atherosclerosis in mice.

Atherosclerosis is a chronic inflammatory disease associated with macrophage aggregate and transformation into foam cells. In this study, we sought to investigate the impact of dietary intake of ω3 fatty acid on the development of atherosclerosis, and demonstrate the mechanism of action by identifying anti-inflammatory lipid metabolite. Mice were exposed to a high-fat diet (HFD) supplemented with either conventional soybean oil or α-linolenic acid-rich linseed oil. We found that as mice became obese they also showed increased pulsatility and resistive indexes in the common carotid artery. In sharp contrast, the addition of linseed oil to the HFD improved pulsatility and resistive indexes without affecting weight gain. Histological analysis revealed that dietary linseed oil inhibited foam cell formation in the aortic valve. Lipidomic analysis demonstrated a particularly marked increase in the eicosapentaenoic acid-derived metabolite 12-hydroxyeicosapentaenoic acid (12-HEPE) in the serum from mice fed with linseed oil. When we gave 12-HEPE to mice with HFD, the pulsatility and resistive indexes was improved. Indeed, 12-HEPE inhibited the foamy transformation of macrophages in a peroxisome proliferator-activated receptor (PPAR)γ-dependent manner. These results demonstrate that the 12-HEPE-PPARγ axis ameliorates the pathogenesis of atherosclerosis by inhibiting foam cell formation.

Structures and anti-atherosclerotic effects of 1,6-α-glucans from Fructus Corni.

In this study, two homogeneous polysaccharides (PFC-1 and PFC-2) having anti-atherosclerotic activity were isolated from Fructus Corni. PFC-1 and PFC-2 were 1,6-α-glucans with the molecular weight of 4.4 kDa and 82.0 kDa, respectively. In the in vitro experiments, PFC-1 and PFC-2 showed significant inhibitory effects on the cholesterol accumulation in RAW264.7 macrophages induced by oxidized low-density lipoproteins (ox-LDL), and the inhibitory rate of PFC-2 was 81.62%. Apolipoprotein E-deficient (ApoE-/-) mice fed high-fat diet (HFD) were used to evaluate the anti-atherosclerotic effects of PFC-2 in vivo. The aortic root lipid area decreased by 55.01% in the PFC-2-administered group as compared to the model group. PFC-2 decreased the levels of serum low-density lipoprotein cholesterol, total cholesterol, triglycerides, and malondialdehyde, increased the superoxide dismutase activity, and reduced the contents of lipid and macrophages in the aortic sinus plaque in ApoE-/- mice fed with HFD. Furthermore, PFC-2 markedly inhibited the expression of type A1 scavenger receptor (SR-A1) and cluster of differentiation 36 (CD36) in ox-LDL-treated macrophages. Taken together, 1,6-α-glucans from Fructus Corni showed significant anti-atherogenic effect, and the mechanism is related to enhanced antioxidant activity of the ApoE-/- mice and down-regulated the expression of SR-A1 and CD36 proteins in macrophages.

Targeting foam cell formation and macrophage polarization in atherosclerosis: The Therapeutic potential of rhubarb.

Atherosclerosis, a chronic inflammatory disease associated with high morbidity and mortality, is characterized by the accumulation of foam cells in the arterial wall. It has long been acknowledged that the formation of foam cells is caused by excess lipid uptake and abnormal cholesterol metabolism function. And increasing evidence shows that inhibiting foam cell formation is a promising way to suppress the development of atherosclerotic lesions. In addition to excess foam cells accumulation, inflammation is another major contributor of atherosclerotic lesions. Recently, macrophage polarization has been demonstrated to play a vital role in the regulation of inflammatory response. Generally, macrophages mainly polarized into two phenotypes: either classically activated pro-inflammatory M1 or alternatively activated anti-inflammatory M2. And targeting macrophage polarization has been considered as a feasible approach to prevent the development of atherosclerosis. At present, the anti-atherosclerosis drugs mainly classified into two types: lipid-lowering drugs and anti-inflammatory drugs. A large part of those drugs belong to western medicine, and various side effects are unavoidable. Interestingly, in recent years, Traditional Chinese medicine has attracted growing attention because of its good efficacy and low negative effects. Rhubarb (called Da Huang in Chinese) is a famous folk medicine with a wide spectrum of pharmacological effects, such as lipid-lowering and anti-inflammatory effects. In this review, we summarized current findings about the regulatory effects of Rhubarb on foam cell formation and macrophage polarization, with emphasis on the molecular mechanisms of action that have been revealed during the past two decades, to better understand its pivotal role in the treatment and prevention of atherosclerosis.

Formononetin attenuates atherosclerosis via regulating interaction between KLF4 and SRA in apoE-/- mice.

Background and Purpose: Atherosclerosis is an underlying cause of coronary heart disease. Foam cell, a hallmark of atherosclerosis, is prominently derived from monocyte-differentiated macrophage, and vascular smooth muscle cells (VSMCs) through unlimitedly phagocytizing oxidized low-density lipoprotein (oxLDL). Therefore, the inhibition of monocyte adhesion to endothelium and uptake of oxLDL might be a breakthrough point for retarding atherosclerosis. Formononetin, an isoflavone extracted from Astragalus membranaceus, has exhibited multiple inhibitory effects on proatherogenic factors, such as obesity, dyslipidemia, and inflammation in different animal models. However, its effect on atherosclerosis remains unknown. In this study, we determined if formononetin can inhibit atherosclerosis and elucidated the underlying molecular mechanisms. Methods: ApoE deficient mice were treated with formononetin contained in high-fat diet for 16 weeks. After treatment, mouse aorta, macrophage and serum samples were collected to determine lesions, immune cell profile, lipid profile and expression of related molecules. Concurrently, we investigated the effect of formononetin on monocyte adhesion, foam cell formation, endothelial activation, and macrophage polarization in vitro and in vivo. Results: Formononetin reduced en face and aortic root sinus lesions size. Formononetin enhanced lesion stability by changing the composition of plaque. VSMC- and macrophage-derived foam cell formation and its accumulation in arterial wall were attenuated by formononetin, which might be attributed to decreased SRA expression and reduced monocyte adhesion. Formononetin inhibited atherogenic monocyte adhesion and inflammation. KLF4 negatively regulated the expression of SRA at transcriptional and translational level. Conclusions: Our study demonstrate that formononetin can substantially attenuate the development of atherosclerosis via regulation of interplay between KLF4 and SRA, which suggests the formononetin might be a novel therapeutic approach for inhibition of atherosclerosis.

Naoxintong Retards Atherosclerosis by Inhibiting Foam Cell Formation Through Activating Pparα Pathway.

BACKGROUNDS: We recently reported that Naoxintong (NXT), a China Food and Drug Administration (FDA)-approved cardiac medicine, could reduce the plaque size, but the underlying mechanism remains elusive now. OBJECTIVE: In this study, we investigated the effects of NXT on foam cell accumulation both in vivo and in vitro and explored related mechanisms. METHOD: THP-1 cells and bone marrow-derived macrophages were incubated with oxidized low-density lipoprotein (ox-LDL) with/without Naoxintong. ApoE-/- mice fed an atherogenic diet were administered to receive NXT for eight weeks. Macrophage-derived foam cell formation in plaques was measured by immunohistochemical staining. Expression of proteins was evaluated by Western blot. Lentivirus was used to knockdown PPARα in THP-1 cells. RESULTS: After NXT treatment, foam cell accumulation was significantly reduced in atherosclerotic plaques. Further investigation revealed that oxidized low-density lipoprotein (ox-LDL) uptake was significantly decreased and expression of scavenger receptor class A (SR-A) and class B (SR-B and CD36) was significantly downregulated post-NXT treatment. On the other hand, NXT increased cholesterol efflux and upregulated ATP-binding cassette (ABC) transporters (ABCA-1 and ABCG-1) in macrophages. Above beneficial effects of NXT were partly abolished after lentiviral knockdown of PPARα. CONCLUSION: Our findings suggest that NXT could retard atherosclerosis by inhibiting foam cell formation through reducing ox-LDL uptake and enhancing cholesterol efflux and above beneficial effects are partly mediated through PPARα pathway.

DBZ (Danshensu Bingpian Zhi), a Novel Natural Compound Derivative, Attenuates Atherosclerosis in Apolipoprotein E-Deficient Mice.

BACKGROUND: DBZ (Danshensu Bingpian Zhi), a synthetic derivative of a natural compound found in traditional Chinese medicine, has been reported to suppress lipopolysaccharide-induced macrophage activation and lipid accumulation in vitro. The aim of this study was to assess whether DBZ could attenuate atherosclerosis at early and advanced stages. METHODS AND RESULTS: The effects of DBZ on the development of atherosclerosis were studied using apolipoprotein E-deficient (apoE-/-) mice. For early treatment, 5-week-old apoE-/- mice were fed a Western diet and treated daily by oral gavage with or without DBZ or atorvastatin for 10 weeks. For advanced treatment, 5-week-old apoE-/- mice were fed a Western diet for 10 weeks to induce atherosclerosis, and then they were randomly divided into 4 groups and subjected to the treatment of vehicle, 20 mg/kg per day DBZ, 40 mg/kg per day DBZ, or 10 mg/kg per day atorvastatin for the subsequent 10 weeks. We showed that early treatment of apoE-/- mice with DBZ markedly reduced atherosclerotic lesion formation by inhibiting inflammation and decreasing macrophage infiltration into the vessel wall. Treatment with DBZ also attenuated the progression of preestablished diet-induced atherosclerotic plaques in apoE-/- mice. In addition, we showed that DBZ may affect LXR (liver X receptor) function and that treatment of macrophages with DBZ suppressed lipopolysaccharide-stimulated cell migration and oxidized low-density lipoprotein-induced foam cell formation. CONCLUSIONS: DBZ potentially has antiatherosclerotic effects that involve the inhibition of inflammation, macrophage migration, leukocyte adhesion, and foam cell formation. These results suggest that DBZ may be used as a therapeutic agent for the prevention and treatment of atherosclerosis.

Role of Vitamin D in Uremic Vascular Calcification.

The risk of cardiovascular death is 10 times higher in patients with CKD (chronic kidney disease) than in those without CKD. Vascular calcification, common in patients with CKD, is a predictor of cardiovascular mortality. Vitamin D deficiency, another complication of CKD, is associated with vascular calcification in patients with CKD. GFR decline, proteinuria, tubulointerstitial injury, and the therapeutic dose of active form vitamin D aggravate vitamin D deficiency and reduce its pleiotropic effect on the cardiovascular system. Vitamin D supplement for CKD patients provides a protective role in vascular calcification on the endothelium by (1) renin-angiotensin-aldosterone system inactivation, (2) alleviating insulin resistance, (3) reduction of cholesterol and inhibition of foam cell and cholesterol efflux in macrophages, and (4) modulating vascular regeneration. For the arterial calcification, vitamin D supplement provides adjunctive role in regressing proteinuria, reverse renal osteodystrophy, and restoring calcification inhibitors. Recently, adventitial progenitor cell has been linked to be involved in the vascular calcification. Vitamin D may provide a role in modulating adventitial progenitor cells. In summary, vitamin D supplement may provide an ancillary role for ameliorating uremic vascular calcification.

Pycnogenol attenuates atherosclerosis by regulating lipid metabolism through the TLR4-NF-κB pathway.

Atherosclerosis is a leading cause of death worldwide and is characterized by lipid-laden foam cell formation. Recently, pycnogenol (PYC) has drawn much attention because of its prominent effect on cardiovascular disease (CVD). However, its protective effect against atherosclerosis and the underlying mechanism remains undefined. Here PYC treatment reduced areas of plaque and lipid deposition in atherosclerotic mice, concomitant with decreases in total cholesterol and triglyceride levels and increases in HDL cholesterol levels, indicating a potential antiatherosclerotic effect of PYC through the regulation of lipid levels. Additionally, PYC preconditioning markedly decreased foam cell formation and lipid accumulation in lipopolysaccharide (LPS)-stimulated human THP-1 monocytes. A mechanistic analysis indicated that PYC decreased the lipid-related protein expression of adipose differentiation-related protein (ADRP) and adipocyte lipid-binding protein (ALBP/aP2) in a dose-dependent manner. Further analysis confirmed that PYC attenuated LPS-induced lipid droplet formation via ADRP and ALBP expression through the Toll-like receptor 4 (TLR4) and nuclear factor-κB (NF-κB) pathway, because pretreatment with anti-TLR4 antibody or a specific inhibitor of NF-κB (PDTC) strikingly mitigated the LPS-induced increase in ADRP and ALBP. Together, our results provide insight into the ability of PYC to attenuate bacterial infection-triggered pathological processes associated with atherosclerosis. Thus PYC may be a potential lead compound for the future development of antiatherosclerotic CVD therapy.

The anti-atherogenic effects of berberine on foam cell formation are mediated through the upregulation of sirtuin 1.

Berberine (BBR) is a botanical alkaloid that has been reported to have effects in cardiovascular diseases; however, the mechanisms involved are not yet fully understood. In the present study, the protective effects of BBR were evaluated, and the underlying molecular mechanisms were investigated. The effects of a combination of atorvastatin and BBR on foam cell formation were also investigated. THP-1-derived macrophages were pre-treated with BBR (5, 10 and 20 mg/l) for 2 h prior to the addition of oxidized low density lipoprotein (ox-LDL; 50 mg/l). Small interfering RNA (siRNA) targeting sirtuin 1 (SIRT1) and the adenosine 5'-monophosphate-activated protein kinase (AMPK) inhibitor, compound C, were used to investigate the mechanisms through which BBR exerts its effects. To determine the effect of a combination of atorvastatin and BBR, the macrophages were treated with atorvastatin and BBR separately or jointly for 2 h, and then treated with ox-LDL (50 mg/l) or lipopolysaccharide (LPS; 10 µM) for 12 h. Oil Red O staining was used to detect foam cell formation. Lipid amounts were assessed by high-performance liquid chromatography (HPLC). Gene and protein expression was evaluated by RT-qPCR, western blot analysis and enzyme-linked immunosorbent assay (ELISA) carried out separately or jointly. The results from Oil Red O staining and HPLC revealed that BBR effectively suppressed foam cell formation and lipid and cholesterol accumulation. Furthermore, BBR upregulated the expression of SIRT1 and AMPK and downregulated the expression of peroxisome proliferator-activated receptor-γ (PPAR-γ). Pre-treatment of the cells with SIRT1-siRNA or compound C attenuated the anti-atherosclerotic effects of BBR. The results obtained in the present study demonstrate that the combination of atorvastatin and BBR is more effective in inhibiting foam cell formation than using atorvastatin alone. These data suggest that BBR suppresses foam cell formation by activating the AMPK-SIRT1-PPAR-γ pathway and diminishing the uptake of ox-LDL. Combination therapy with BBR and atorvastatin was more effective in preventing atherosclerotic processes than atorvastatin alone.

Elevated microRNA-155 promotes foam cell formation by targeting HBP1 in atherogenesis.

AIM: MicroRNAs (miRNAs) play key roles in inflammatory responses of macrophages. However, the function of miRNAs in macrophage-derived foam cell formation is unclear. Here, we investigated the role of miRNAs in macrophage-derived foam cell formation and atherosclerotic development. METHODS AND RESULTS: Using quantitative reverse transcription-PCR (qRT-PCR), we found that the level of miR-155 expression was increased significantly in both plasma and macrophages from atherosclerosis (ApoE(-/-)) mice. We identified that oxidized low density lipoprotein (oxLDL) induced the expression and release of miR-155 in macrophages, and that miR-155 was required to mediate oxLDL-induced lipid uptake and reactive oxygen species (ROS) production of macrophages. Furthermore, ectopic overexpression and knockdown experiments identified that HMG box-transcription protein1 (HBP1) is a novel target of miR-155. Knockdown of HBP1 enhanced lipid uptake and ROS production in oxLDL-stimulated macrophages, and overexpression of HBP1 repressed these effects. Furthermore, bioinformatics analysis identified three YY1 binding sites in the promoter region of pri-miR-155 and verified YY1 binding directly to its promoter region. Detailed analysis showed that the YY1/HDAC2/4 complex negatively regulated the expression of miR-155 to suppress oxLDL-induced foam cell formation. Importantly, inhibition of miR-155 by a systemically delivered antagomiR-155 decreased clearly lipid-loading in macrophages and reduced atherosclerotic plaques in ApoE(-/-) mice. Moreover, we observed that the level of miR-155 expression was up-regulated in CD14(+) monocytes from patients with coronary heart disease. CONCLUSION: Our findings reveal a new regulatory pathway of YY1/HDACs/miR-155/HBP1 in macrophage-derived foam cell formation during early atherogenesis and suggest that miR-155 is a potential therapeutic target for atherosclerosis.

Effects of Alisma Decoction on lipid metabolism and inflammatory response are mediated through the activation of the LXRα pathway in macrophage-derived foam cells.

The liver X receptor α (LXRα)/ATP-binding cassette transporter A1 (ABCA1) pathway and LXR-modulated cytokines play an important role in macrophages which mediate lipid engulfment and the inflammatory response, and participate in the process of atherosclerosis. Therefore, lipid-lowering and anti-inflammatory therapy through the activation of the LXRα/ABCA1 pathway and LXRα-modulated cytokines may prove to be one of the main treatment strategies for atherosclerosis. Alisma Decoction (AD) has long been used in China to clinically treat cardiovascular and cerebral diseases; however, the precise mechanisms involved remain to be elucidated. In the present study, we evaluated the regulation of lipids and the anti-inflammatory effects exerted by AD and investigated the underlying molecular mechanisms using oxidized low-density lipoprotein (ox-LDL)-stimulated foam cells derived from rat peritoneal macrophages. We first found that AD markedly relieved lipid deposition in foam cells as it increased LXRα and ABCA1 expression and decreased the ox-LDL-induced expression of inflammatory cytokines, such as matrix metalloproteinase-9 and interleukin-1ß. Collectively, our findings suggest that blocking lipid deposition and inhibiting inflammatory response through the activation of the LXRα pathway may be one of the main mechanisms through which AD exerts its anti-atherosclerotic effects.

Tertiary-butylhydroquinone upregulates expression of ATP-binding cassette transporter A1 via nuclear factor E2-related factor 2/heme oxygenase-1 signaling in THP-1 macrophage-derived foam cells.

BACKGROUND: Tert-butylhydroquinone (tBHQ), a synthetic phenolic antioxidant, is commonly used as a food preservative because of its potent antilipid peroxidation activity. Several lines of evidence have demonstrated that dietary supplementation with antioxidants has an antiatherogenic function through reducing cholesterol uptake or promoting reverse cholesterol transport. In this study, we investigated whether tBHQ affects expression of ATP-binding cassette transporter A1 (ABCA1) and the potential subsequent effect on cellular cholesterol homeostasis. METHODS AND RESULTS: tBHQ increased ABCA1 protein levels and markedly enhanced cholesterol efflux from THP-1 macrophage-derived foam cells. Furthermore, tBHQ reduced calpain-mediated ABCA1 proteolysis via activation of nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1). Inhibition of HO-1 with a pharmacological inhibitor or siRNA and knockdown of Nrf2 suppressed the stimulatory effects of tBHQ on ABCA1 expression and calpain activity. CONCLUSIONS: Nrf2/HO-1 signaling is required for the regulation by tBHQ of ABCA1 expression and cholesterol efflux in macrophage-derived foam cells and an antiatherogenic role of tBHQ is suggested.

Sida rhomboidea.Roxb aqueous extract down-regulates in vivo expression of vascular cell adhesion molecules in atherogenic rats and inhibits in vitro macrophage differentiation and foam cell formation.

The present study evaluates efficacy of Sida rhomboidea.Roxb (SR) leaves extract in ameliorating experimental atherosclerosis using in vitro and in vivo experimental models. Atherogenic (ATH) diet fed rats recorded significant increment in the serum total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), very LDL (VLDL), autoantibody against oxidized LDL (Ox-LDL), markers of LDL oxidation and decrement in high-density lipoprotein (HDL) along with increment in aortic TC and TG. The ex vivo LDL oxidation assay revealed an increased susceptibility of LDL isolated from ATH rats to undergo copper mediated oxidation. These set of changes were minimized by simultaneous co-supplementation of SR extract to ATH diet fed rats. Histopathology of aorta and immunolocalization studies recorded pronounced atheromatous plaque formation, vascular calcification, significant elastin derangements and higher expression of macrophage surface marker (F4/80), vascular cell adhesion molecule-1 (VCAM-1) and p-selectin in ATH rats. Whereas, ATH+SR rats depicted minimal evidence of atheromatous plaque formation, calcium deposition, distortion/defragmentation of elastin and accumulation of macrophages along with lowered expression of VCAM-1 and P-selectin compared to ATH rats. Further, monocyte to macrophage differentiation and in vitro foam cell formation were significantly attenuated in presence of SR extract. In conclusion, SR extract has the potency of controlling experimental atherosclerosis and can be used as promising herbal supplement in combating atherosclerosis.

Antioxidant and anti-atherogenic activities of three Piper species on atherogenic diet fed hamsters.

Atherogenic diet is known to induce high plasma lipid concentration, oxidative stress and early atherosclerosis. Antioxidants have potentials to counter the effect of atherogenic diet. The present research aims at evaluating the antioxidant and anti-atherosclerotic activities of three Piper species (Piper guineense, Piper nigrum and Piper umbellatum) on atherogenic diet fed hamsters. Hamsters divided into 8 groups: normal control, atherosclerotic control and six test groups. The normal animals fed normal rodent chow, the atherosclerotic control animals fed the same rodent chow supplemented with 0.2% cholesterol and 10% coconut oil (high cholesterol diet). The 6 test groups' animals fed same diet as the atherosclerotic control group but with additional supplementation of 2 graded doses (1 and 0.25 mg/kg body weight, o.p.) of plant extracts for 12 weeks. The atherogenic diet induced a collapse of the erythrocyte antioxidant defense system (significant decrease in superoxide dismutase, catalase and glutathione peroxidase activities). Atherogenic diet also induced an increase in plasma total cholesterol, triglyceride, thiobarbituric acid reactive substances (TBARS), oxidation of low density lipoprotein cholesterol (LDL) and accumulation of foam cells in the aorta a hall mark for atherosclerosis. Administration of the Piper species prevented the collapse of the antioxidant system and the increase of plasma parameters maintaining them towards normality. The Piper species also prevented LDL oxidation by increasing the time (lag time) for its oxidation. The results suggest that these Piper species have significant antioxidant and anti-atherogenic effect against atherogenic diet intoxication.

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.

Poly(ADP-ribose) polymerase inhibition reduces atherosclerotic plaque size and promotes factors of plaque stability in apolipoprotein E-deficient mice: effects on macrophage recruitment, nuclear factor-kappaB nuclear translocation, and foam cell death.

BACKGROUND: Poly(ADP-ribose) polymerase (PARP) was suggested to play a role in endothelial dysfunction that is associated with a number of cardiovascular diseases. We hypothesized that PARP may play an important role in atherogenesis and that its inhibition may attenuate atherosclerotic plaque development in an experimental model of atherosclerosis. METHODS AND RESULTS: Using a mouse (apolipoprotein E [ApoE](-/-)) model of high-fat diet-induced atherosclerosis, we demonstrate an association between cell death and oxidative stress-associated DNA damage and PARP activation within atherosclerotic plaques. PARP inhibition by thieno[2,3-c]isoquinolin-5-one reduced plaque number and size and altered structural composition of plaques in these animals without affecting sera lipid contents. These results were corroborated genetically with the use of ApoE(-/-) mice that are heterozygous for PARP-1. PARP inhibition promoted an increase in collagen content, potentially through an increase in tissue inhibitor of metalloproteinase-2, and transmigration of smooth muscle cells to intima of atherosclerotic plaques as well as a decrease in monocyte chemotactic protein-1 production, all of which are markers of plaque stability. In PARP-1(-/-) macrophages, monocyte chemotactic protein-1 expression was severely inhibited because of a defective nuclear factor-kappaB nuclear translocation in response to lipopolysaccharide. Furthermore, PARP-1 gene deletion not only conferred protection to foam cells against H2O2-induced death but also switched the mode of death from necrosis to apoptosis. CONCLUSIONS: Our results suggest that PARP inhibition interferes with plaque development and may promote plaque stability, possibly through a reduction in inflammatory factors and cellular changes related to plaque dynamics. PARP inhibition may prove beneficial for the treatment of atherosclerosis.

The effects of Danggui-Buxue-Tang on blood lipid and expression of genes related to foam cell formation in the early stage of atherosclerosis in diabetic GK rats.

Danggui-Buxue-Tang (DBT) is a famous traditional Chinese formula. We determined the effects of DBT on blood lipid and expression of genes related to foam cell formation in the early stage of atherosclerosis in diabetic GK rats. DBT (3 or 6g/kg/day for 4 weeks) was orally administrated to the diabetic atherosclerosis rats, which were induced by nitric oxide inhibition (l-NAME in drinking water, 1mg/ml) plus high-fat diet. The total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C), and the mRNAs expression of monocyte chemoattractant protein (MCP)-1, intercellular adhesion molecule (ICAM)-1 and CD36 mRNA in aorta were determined. The results demonstrated that DBT could regulate blood lipid, inhibit the genes expression of MCP-1, ICAM-1 and CD36 in aorta.

Crocetin attenuates atherosclerosis in hyperlipidemic rabbits through inhibition of LDL oxidation.

Oxidation of low-density lipoprotein plays a crucial role in the pathogenesis of atherosclerosis, raising the possibility of using antioxidants as an inhibitor of atherosclerosis. However, studies with antioxidants have led to contradictory results. In the present study, we investigated the effect of crocetin, a carotenoid with potent antioxidant activity, on experimental atherosclerosis in rabbits. After 8 weeks of feeding on high lipid diet, rabbits developed severe atherosclerotic lesions in thoracic aortas (P < 0.01), together with a significant elevation of plasma lipids level, thiobarbituric acid reactive substances (TBARS), and oxidized low-density lipoprotein (P < 0.01). In contrast, supplementation with crocetin markedly reduced the progression of atherosclerotic lesions (P < 0.01) and plasma levels of Ox-LDL and TBARS, whereas plasma lipids level remained unchanged. Plasma total antioxidant capacity and superoxide dismutase activity were obviously increased in crocetin-treated rabbits. In vitro studies demonstrated that supplementation with crocetin significantly increased the resistance of LDL to cupric ion-induced oxidation. Regression analysis indicated that atherosclerotic areas correlated positively with plasma level of Ox-LDL and the susceptibility of LDL to in vitro oxidation. These findings suggest that suppression of LDL oxidation by crocetin contributes, at least partly, to the attenuation of atherosclerosis.