Pitavastatin Downregulates Expression of the Macrophage Type B Scavenger Receptor, CD36

Sulforaphane Inhibits Foam Cell Formation and Atherosclerosis via Mechanisms Involving the Modulation of Macrophage Cholesterol Transport and the Related Phenotype

Sulforaphane (SFN), an isothiocyanate, is one of the major dietary phytochemicals found in cruciferous vegetables. Many studies suggest that SFN can protect against cancer and cardiometabolic diseases. Despite the proposed systemic and local vascular protective mechanisms, SFN's potential to inhibit atherogenesis by targeting macrophages remains unknown. In this study, in high fat diet fed ApoE-deficient (ApoE^-/-) mice, oral SFN treatment improved dyslipidemia and inhibited atherosclerotic plaque formation and the unstable phenotype, as demonstrated by reductions in the lesion areas in both the aortic sinus and whole aorta, percentages of necrotic cores, vascular macrophage infiltration and reactive oxygen species (ROS) generation. In THP-1-derived macrophages, preadministration SFN alleviated oxidized low-density lipoprotein (ox-LDL)-induced lipid accumulation, oxidative stress and mitochondrial injury. Moreover, a functional study revealed that peritoneal macrophages isolated from SFN-treated mice exhibited attenuated cholesterol influx and enhanced apolipoprotein A-I (apoA-I)- and high-density lipoprotein (HDL)-mediated cholesterol efflux. Mechanistic analysis revealed that SFN supplementation induced both intralesional and intraperitoneal macrophage phenotypic switching toward high expression of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) and ATP-binding cassette subfamily A/G member 1 (ABCA1/G1) and low expression of peroxisome proliferator-activated receptor γ (PPARγ) and cluster of differentiation 36 (CD36), which was further validated by the aortic protein expression. These results suggest that the regulation of macrophages' cholesterol transport and accumulation may be mainly responsible for SFN's potential atheroprotective properties, and the regulatory mechanisms might involve upregulating ABCA1/G1 and downregulating CD36 via the modulation of PPARγ and Nrf2.

Statins for primary cardiovascular disease prevention among people with HIV: emergent directions

PURPOSE OF REVIEW

While people with HIV (PWH) are living longer due to advances in antiretroviral therapy, recent data have demonstrated an increased risk of cardiovascular disease (CVD) among this population. This increased risk is thought to be due to both traditional (for example, smoking, diabetes) and HIV-specific (for example, inflammation, persistent immune activation) risk factors. This review focuses on the potential for statin therapy to mitigate this increased risk.

RECENT FINDINGS

Several randomized clinical trials have demonstrated that statins, a class of lipid-lowering medications, are effective as a primary CVD prevention strategy among people without HIV. Among PWH, statins have been shown to lower cholesterol, exert immunomodulatory effects, stabilize coronary atherosclerotic plaque, and even induce plaque regression.

SUMMARY

Prevention of CVD among the aging population of people with controlled, but chronic, HIV is vital. Data exploring primary prevention in this context are thus far limited. The Randomized Trial to Prevent Vascular Events in HIV (REPRIEVE) is ongoing; this trial will inform the field by investigating the effects of pitavastatin calcium as a primary prevention strategy for major adverse cardiovascular events among PWH on antiretroviral therapy (ART) at low-to-moderate traditional CVD risk.

High-Efficacy α,β-Dehydromonacolin S Improves Hepatic Steatosis and Suppresses Gluconeogenesis Pathway in High-Fat Diet-Induced Obese Rats

Isolated α,β-dehydromonacolin S (C5) from soil-derived fungus Aspergillus sclerotiorum PSU-RSPG178 was recently shown to exhibit an inhibitory effect against 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) activity in vitro. In this study, we investigated the effects of C5 on lipid-lowering, hepatic steatosis, and hepatic gluconeogenesis in vivo. The control rats received a daily dose of either vehicle or C5 at 10 mg/kg, while the high-fat diet-induced obese (HFD) rats were administered vehicle; 1, 3, or 10 mg/kg C5; or 10 mg/kg lovastatin (LO) for 6 weeks. C5 significantly improved dyslipidemia and diminished liver enzymes, HMGR activity, insulin resistance, and hepatic steatosis, comparable to LO without any hepatotoxicity and nephrotoxicity in HFD rats. A higher efficacy of C5 in lipid-lowering activity and anti-hepatic steatosis was associated with a significant decrease in genes involved in lipid metabolism including sterol regulatory element binding protein (SREBP) 1c, SREBP2, liver X receptor alpha (LXRα), and peroxisome proliferator-activated receptor (PPAR) gamma (PPARγ) together with an increase in the PPAR alpha (PPARα). Correspondingly, C5 was able to down-regulate the lipid transporters cluster of differentiation 36 (CD36) and Niemann-Pick C1 Like 1 (NPC1L1), increase the antioxidant superoxide dismutase gene expression, and decrease the proinflammatory cytokines, tumor necrosis factor alpha (TNFα) and interleukin 1 beta (IL-1β). Impairment of hepatic gluconeogenesis and insulin resistance in HFD rats was restored by C5 through down-regulation of the gluconeogenic genes phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase), and the activation of AMP-dependent kinase serine (AMPK) and serine/threonine protein kinase B (Akt). Collectively, this novel C5 may be a therapeutic option for treating dyslipidemia, hepatic steatosis, and reducing potential risk for diabetes mellitus.

Blockade of Macrophage CD147 Protects Against Foam Cell Formation in Atherosclerosis

The persistence of macrophage-derived foam cells in the artery wall fuels atherosclerosis development. However, the mechanism of foam cell formation regulation remains elusive. We are committed to determining the role that CD147 might play in macrophage foam cell formation during atherosclerosis. In this study, we found that CD147 expression was primarily increased in mouse and human atherosclerotic lesions that were rich in macrophages and could be upregulated by ox-LDL. High-throughput compound screening indicated that ox-LDL-induced CD147 upregulation in macrophages was achieved through PI3K/Akt/mTOR signaling. Genetic deletion of macrophage CD147 protected against foam cell formation by impeding cholesterol uptake, probably through the scavenger receptor CD36. The opposite effect was observed in primary macrophages isolated from macrophage-specific CD147-overexpressing mice. Moreover, bioinformatics results indicated that CD147 suppression might exert an atheroprotective effect via various processes, such as cholesterol biosynthetic and metabolic processes, LDL and plasma lipoprotein clearance, and decreased platelet aggregation and collagen degradation. Our findings identify CD147 as a potential target for prevention and treatment of atherosclerosis in the future.

CD36 in Atherosclerosis: Pathophysiological Mechanisms and Therapeutic Implications

PURPOSE OF REVIEW

Atherosclerosis is a chronic disease characterized by lipid retention and inflammation in the artery wall. The retention and oxidation of low-density lipoprotein (LDL) in sub-endothelial space play a critical role in atherosclerotic plaque formation and destabilization. Oxidized LDL (ox-LDL) and other modified LDL particles are avidly taken up by endothelial cells, smooth muscle cells, and macrophages mainly through several scavenger receptors, including CD36 which is a class B scavenger receptor and membrane glycoprotein.

RECENT FINDINGS

Animal studies performed on CD36-deficient mice suggest that deficiency of CD36 prevents the development of atherosclerosis, though with some debate. CD36 serves as a signaling hub protein at the crossroad of inflammation, lipid metabolism, and fatty acid metabolism. In addition, the level of soluble CD36 (unattached to cells) in the circulating blood was elevated in patients with atherosclerosis and other metabolic disorders. We performed a state-of-the-art review on the structure, ligands, functions, and regulation of CD36 in the context of atherosclerosis by focusing on the pathological role of CD36 in the dysfunction of endothelial cells, smooth muscle cells, monocytes/macrophages, and platelets. Finally, we highlight therapeutic possibilities to target CD36 expression/activity in atherosclerosis.

Oleacein and Foam Cell Formation in Human Monocyte-Derived Macrophages: A Potential Strategy Against Early and Advanced Atherosclerotic Lesions

Background: Oleacein is a secoiridoid group polyphenol found mostly in Olea europea L. and Ligustrum vulgare L. (Oleaceae). The aim of the present study was to investigate a potential role of oleacein in prevention of the foam cell formation. Materials and Methods: Oleacein was isolated from Ligustrum vulgare leaves. Human monocyte-derived macrophages were obtained from monocytes cultured with Granulocyte-macrophage colony-stimulating factor (GM-CSF). Then, cells were incubated with 20 μM or 50 μM of oleacein and with oxidized low-density lipoprotein (oxLDL) (50 μg/mL). Visualization of lipid deposition within macrophages was carried out using Oil-Red-O. Expression of CD36, Scavenger receptor A1 (SRA1) and Lectin-like oxidized low-density lipoprotein receptor 1 (LOX-1) was determined by Reverse transcription polymerase chain reaction (RT-PCR) and by flow cytometry. Apoptosis was determined by flow cytometry using Annexin V assay. STAT3 and Acyl-coenzyme A: cholesterol acyltransferase type 1 (ACAT1) levels were determined by ELISA. P-STAT3, P-JAK1, P-JAK2 expressions were determined by Western blot (WB). Results: Oleacein in dose-dependent manner significantly reduced lipid deposits in macrophages as well as their expression of selected scavenger receptors. The highest decrease of expression was found for CD36 and SRA1 receptors, from above 20% to more than 75% compared to oxLDL and the lowest for LOX-1 receptor, from approx. 8% to approx. 25% compared to oxLDL-stimulated macrophages. Oleacein significantly reduced (2.5-fold) early apoptosis of oxLDL-stimulated macrophages. Moreover, oleacein significantly increased the protein expression of JAK/STAT3 pathway and had no effect on ACAT1 level. Conclusions: Our study demonstrates, for the first time, that oleacein inhibits foam cell formation in human monocyte-derived macrophages and thus can be a valuable tool in the prevention of early and advanced atherosclerotic lesions.

Dynamically enhancing plaque targeting via a positive feedback loop using multifunctional biomimetic nanoparticles for plaque regression

A paradigm shift from preventive therapy to aggressive plaque regression and eventual eradication is much needed to address increasing atherosclerotic burden and risks. Herein, we report a biologically inspired dual-targeting multifunctional recombinant high-density lipoprotein (rHDL)-mimicking core-shell nanoplatform. It is composed of an ATP-responsive ternary polyplexes core for SR-A siRNA and catalase complexation, and a phosphatidylserine-modified rHDL-based outer shell for SR-BI and CD36 targeting, in which pitavastatin is packaged. We demonstrated that dual-targeting biomimetic core-shell nanoparticles dynamically enhanced macrophage CD36 targeting in the plaques by establishing a positive feedback loop via the reciprocal regulation of SR-A and CD36. Positive feedback-enabled accumulation of the nanoparticles in the atherosclerotic plaques increased by 3.3-fold following 4-week repeated administration. A 3-month dosage regimen of the dual-targeting rHDL-mimicking nanoparticles reduced plaque areas by 65.8%, and decreased macrophages by 57.3%. Collectively, this work shows that dynamically enhancing plaque targeting via a positive feedback loop and dual action of cholesterol deposition inhibition and efflux enhancement accomplished with our novel multifunctional biomimetic nanoparticles provides a new way to regress plaques and alleviate the atherosclerotic burden.

Rosuvastatin Reduces Aortic Sinus and Coronary Artery Atherosclerosis in SR-B1 (Scavenger Receptor Class B Type 1)/ApoE (Apolipoprotein E) Double Knockout Mice Independently of Plasma Cholesterol Lowering

Supplemental Digital Content is available in the text.

Objective—

Rosuvastatin has been widely used in the primary and secondary prevention of coronary heart disease. However, its antiatherosclerotic properties have not been tested in a mouse model that could mimic human coronary heart disease. The present study was designed to test the effects of rosuvastatin on coronary artery atherosclerosis and myocardial fibrosis in SR-B1 (scavenger receptor class B type 1) and apoE (apolipoprotein E) double knockout mice.

Approach and Results—

Three-week-old SR-B1^−/−/apoE^−/− mice were injected daily with 10 mg/kg of rosuvastatin for 2 weeks. Compared with saline-treated mice, rosuvastatin-treated mice showed increased levels of hepatic PCSK9 (proprotein convertase subtilisin/kexin type-9) and LDLR (low-density lipoprotein receptor) message, increased plasma PCSK9 protein but decreased levels of hepatic LDLR protein and increased plasma total cholesterol associated with apoB (apolipoprotein B) 48-containing lipoproteins. In spite of this, rosuvastatin treatment was associated with decreased atherosclerosis in both the aortic sinus and coronary arteries and reduced platelet accumulation in atherosclerotic coronary arteries. Cardiac fibrosis and cardiomegaly were also attenuated in rosuvastatin-treated SR-B1^−/−/apoE^−/− mice. Two-week treatment with rosuvastatin resulted in significant decreases in markers of oxidized phospholipids in atherosclerotic plaques. In vitro analysis showed that incubation of bone marrow-derived macrophages with rosuvastatin substantially downregulated cluster of differentiation (CD)36 and inhibited oxidized LDL-induced foam cell formation.

Conclusions—

Rosuvastatin protected SR-B1^−/−/apoE^−/− mice against atherosclerosis and platelet accumulation in coronary arteries and attenuated myocardial fibrosis and cardiomegaly, despite increased plasma total cholesterol. The ability of rosuvastatin to reduce oxidized phospholipids in atherosclerotic plaques and inhibit macrophage foam cell formation may have contributed to this protection.

Pitavastatin Differentially Modulates MicroRNA-Associated Cholesterol Transport Proteins in Macrophages

There is emerging evidence identifying microRNAs (miRNAs) as mediators of statin-induced cholesterol efflux, notably through the ATP-binding cassette transporter A1 (ABCA1) in macrophages. The objective of this study was to assess the impact of an HMG-CoA reductase inhibitor, pitavastatin, on macrophage miRNAs in the presence and absence of oxidized-LDL, a hallmark of a pro-atherogenic milieu. Treatment of human THP-1 cells with pitavastatin prevented the oxLDL-mediated suppression of miR-33a, -33b and -758 mRNA in these cells, an effect which was not uniquely attributable to induction of SREBP2. Induction of ABCA1 mRNA and protein by oxLDL was inhibited (30%) by pitavastatin, while oxLDL or pitavastatin alone significantly induced and repressed ABCA1 expression, respectively. These findings are consistent with previous reports in macrophages. miRNA profiling was also performed using a miRNA array. We identified specific miRNAs which were up-regulated (122) and down-regulated (107) in THP-1 cells treated with oxLDL plus pitavastatin versus oxLDL alone, indicating distinct regulatory networks in these cells. Moreover, several of the differentially expressed miRNAs identified are functionally associated with cholesterol trafficking (six miRNAs in cells treated with oxLDL versus oxLDL plus pitavastatin). Our findings indicate that pitavastatin can differentially modulate miRNA in the presence of oxLDL; and, our results provide evidence that the net effect on cholesterol homeostasis is mediated by a network of miRNAs.

Activation of Peroxisome Proliferator-activated Receptor γ (PPARγ) and CD36 Protein Expression: THE DUAL PATHOPHYSIOLOGICAL ROLES OF PROGESTERONE

Progesterone or its analog, one of components of hormone replacement therapy, may attenuate the cardioprotective effects of estrogen. However, the underlying mechanisms have not been fully elucidated. Expression of CD36, a receptor for oxidized LDL (oxLDL) that enhances macrophage/foam cell formation, is activated by the transcription factor peroxisome proliferator-activated receptor γ (PPARγ). CD36 also functions as a fatty acid transporter to influence fatty acid metabolism and the pathophysiological status of several diseases. In this study, we determined that progesterone induced macrophage CD36 expression, which is related to progesterone receptor (PR) activity. Progesterone enhanced cellular oxLDL uptake in a CD36-dependent manner. Mechanistically, progesterone increased PPARγ expression and PPARγ promoter activity in a PR-dependent manner and the binding of PR with the progesterone response element in the PPARγ promoter. Specific deletion of macrophage PPARγ (MφPPARγ KO) expression in mice abolished progesterone-induced macrophage CD36 expression and cellular oxLDL accumulation. We also determined that, associated with gestation and increased serum progesterone levels, CD36 and PPARγ expression in mouse adipose tissue, skeletal muscle, and peritoneal macrophages were substantially activated. Taken together, our study demonstrates that progesterone can play dual pathophysiological roles by activating PPARγ expression, in which progesterone increases macrophage CD36 expression and oxLDL accumulation, a negative effect on atherosclerosis, and enhances the PPARγ-CD36 pathway in adipose tissue and skeletal muscle, a protective effect on pregnancy.

The Role of CD36 in the Effect of Arginine in Atherosclerotic Rats

Background

The aim of this study was to investigate the effects of arginine in the development of atherosclerosis in rats fed a high-fat diet supplemented with arginine and to evaluate the role of CD36 in this process.

Material/Methods

A total of 40 Sprague-Dawley rats were randomly assigned to 4 groups: control group, fat diet group, simvastatin group, and arginine group. They were fed for 12 weeks and were then sacrificed. Immunohistochemical CD36 expression and pathology was investigated in the aorta; CD36 expression in mononuclear cells was detected by Western blot and RT-PCR.

Results

The thickness of the aortal intima, media, and I/M significantly decreased in the arginine group rats compared with those in the fat diet group (P<0.05). CD36 expression was up-regulated in rats in the fat diet group compared with the control group and was down-regulated in rats in the arginine group compared with rats in the fat diet group.

Conclusions

The addition of arginine has a significant effect on reducing rat atherosclerosis development, which may be attributed to both the down-regulation of CD36 expression in rat aortic endothelial and blood mononuclear cells and the NO pathway.

Kimchi methanol extract and the kimchi active compound, 3'-(4'-hydroxyl-3',5'-dimethoxyphenyl)propionic acid, downregulate CD36 in THP-1 macrophages stimulated by oxLDL

Macrophage foam cell formation by oxidized low-density lipoprotein (oxLDL) is a key step in the progression of atherosclerosis, which is involved in cholesterol influx and efflux in macrophages mediated by related proteins such as peroxisome proliferator-activated receptor γ (PPARγ), CD36, PPARα, liver-X receptor α (LXRα), and ATP-binding cassette transporter A1 (ABCA1). The aim of this study was to investigate the beneficial effects of kimchi methanol extract (KME) and a kimchi active compound, 3-(4'-hydroxyl-3',5'-dimethoxyphenyl)propionic acid (HDMPPA) on cholesterol flux in THP-1-derived macrophages treated with oxLDL. The effects of KME and HDMPPA on cell viability and lipid peroxidation were determined. Furthermore, the protein expression of PPARγ, CD36, PPARα, LXRα, and ABCA1 was examined. OxLDL strongly induced cell death and lipid peroxidation in THP-1-derived macrophages. However, KME and HDMPPA significantly improved cell viability and inhibited lipid peroxidation induced by oxLDL in THP-1-derived macrophages (P<.05). Moreover, KME and HDMPPA suppressed CD36 and PPARγ expressions, both of which participate in cholesterol influx. In contrast, KME and HDMPPA augmented LXRα, PPARα, and ABCA1 expression, which are associated with cholesterol efflux. Consequently, KME and HDMPPA suppressed lipid accumulation. These results indicate that KME and HDMPPA may inhibit lipid accumulation, in part, by regulating cholesterol influx- and efflux-related proteins. These findings will thus be useful for future prevention strategies against atherosclerosis.

Intermedin inhibits macrophage foam-cell formation via tristetraprolin-mediated decay of CD36 mRNA

AIMS

CD36-mediated uptake of oxidized low-density lipoprotein (oxLDL) plays a pivotal role in macrophage foam-cell formation and atherogenesis. Previously we reported on intermedin (IMD), a novel member of the calcitonin gene-related peptide family, in atherosclerotic plaque reducing atherogenesis in apolipoprotein E-deficient (apoE(-/-)) mice. Here, we studied the role of IMD in CD36-mediated macrophage foam-cell formation.

METHODS AND RESULTS

In apoE(-/-) mice, 6-week IMD infusion reduced oxLDL uptake, intracellular cholesterol content, and foam-cell formation in peritoneal macrophages and reduced protein and mRNA levels of CD36. These in vivo results agreed with in vitro observations in primary peritoneal macrophages. Reduced CD36 protein and mRNA levels were due to an IMD-accelerated decay of CD36 mRNA. Tristetraprolin (TTP), which binds to AU-rich elements in the 3' untranslated regions (UTRs) of mRNA and promotes its degradation, mediated CD36 mRNA destabilization. TTP knockdown by short-hairpin RNA increased and TTP overexpression reduced CD36 expression, and TTP knockdown rescued IMD-reduced CD36 expression. Moreover, IMD repressed TTP phosphorylation, thereby activating TTP, for increased TTP binding to the 3'-UTR of CD36 mRNA.

CONCLUSION

Thus, IMD attenuates macrophage foam-cell formation via TTP-mediated degradation of CD36 mRNA. Our findings reveal a new mechanism of the anti-atherogenic role of IMD and a novel pattern for regulation of CD36 expression in macrophages.

Electronegative low-density lipoprotein increases C-reactive protein expression in vascular endothelial cells through the LOX-1 receptor

Objectives

Increased plasma C-reactive protein (CRP) levels are associated with the occurrence and severity of acute coronary syndrome. We investigated whether CRP can be generated in vascular endothelial cells (ECs) after exposure to the most electronegative subfraction of low-density lipoprotein (LDL), L5, which is atherogenic to ECs. Because L5 and CRP are both ligands for the lectin-like oxidized LDL receptor-1 (LOX-1), we also examined the role of LOX-1.

Methods and Results

Plasma LDL samples isolated from asymptomatic hypercholesterolemic (LDL cholesterol [LDL-C] levels, 154.6±20 mg/dL; n = 7) patients and normocholesterolemic (LDL-C levels, 86.1±21 mg/dL; P<0.001; n = 7) control individuals were chromatographically resolved into 5 subfractions, L1-L5. The L5 percentage (L5%) and the plasma L5 concentration ([L5]  =  L5% × LDL-C) in the patient and control groups were 8.1±2% vs. 2.3±1% (P<0.001) and 12.6±4 mg/dL vs. 1.9±1 mg/dL (P<0.001), respectively. In hypercholesterolemic patients treated with atorvastatin for 6 months (10 mg/day), [L5] decreased from 12.6±4 mg/dL to 4.5±1.1 mg/dL (P = 0.011; n = 5), whereas both [L5] and L5% returned to baseline levels in 2 noncompliant patients 3 months after discontinuation. In cultured human aortic ECs (HAECs), L5 upregulated CRP expression in a dose- and time-dependent manner up to 2.5-fold (P<0.01), whereas the least electronegative subfraction, L1, had no effect. DiI-labeled L1, internalized through the LDL receptor, became visible inside HAECs within 30 seconds. In contrast, DiI-labeled L5, internalized through LOX-1, became apparent after 5 minutes. L5-induced CRP expression manifested at 30 minutes and was attenuated by neutralizing LOX-1. After 30 minutes, L5 but not L1 induced reactive oxygen species (ROS) production. Both L5-induced ROS and CRP production were attenuated by ROS inhibitor N-acetyl cysteine.

Conclusions

Our results suggest that CRP, L5, and LOX-1 form a cyclic mechanism in atherogenesis and that reducing plasma L5 levels with atorvastatin disrupts the vascular toxicity of L5.

The involvement of CD36 in monocyte activation by antiphospholipid antibodies

Background

CD36, known as a scavenger receptor, is a transmembrane glycoprotein expressed on monocytes, platelets and endothelial cells, recognizes multiple ligands, including phosphatidylserine, and regulates atherogenesis and thrombosis. The objective of this study is to investigate the possible involvement of CD36 in the pathophysiology of thrombosis in patients with antiphospholipid syndrome (APS).

Methods

First, rs3765187, a missense mutation linked to CD36 deficiency, was investigated by TaqMan polymerase chain reaction (PCR) genotyping method in 819 Japanese, including 132 patients with APS, 265 with systemic lupus erythematosus (SLE) in the absence of APS, and 422 healthy subjects. Then, the involvement of CD36 in antiphospholipid antibody (aPL)-induced tissue factor (TF) expression was examined using CD36-null mice or anti-CD36. Purified IgG from patients with APS and a monoclonal phosphatidylserine-dependent antiprothrombin antibody were used in these experiments. TF expression was tested by real-time PCR and flow cytometry.

Results

Minor allele carrier of rs3765187 was less frequent in patients with APS (3.8% p = 0.032), but not in patients with SLE in the absence of APS (7.9% p = 0.32), compared with healthy subjects (10.2%). The aPL-induced TF expression was significantly suppressed on peritoneal macrophages from CD36-null mice compared to wild type and significantly inhibited by anti-CD36 on human monocytes.

Conclusions

The gene mutation linked to CD36 deficiency was less frequent in patients with APS. The deficient or suppressed CD36 function significantly reduced aPL-induced TF expression in vitro. Taken together, in a susceptible background CD36 scavenger receptor function may be involved in the thrombotic pathophysiology in patients with APS.

Evidence for new targets and synergistic effect of metronomic celecoxib/fluvastatin combination in pilocytic astrocytoma

Background

Pilocytic astrocytomas occur predominantly in childhood. In contrast to the posterior fossa location, hypothalamo-chiasmatic pilocytic astrocytomas display a worse prognosis often leading to multiple surgical procedures and/or several lines of chemotherapy and radiotherapy to achieve long-term control. Hypothalamo-chiasmatic pilocytic astrocytomas and cerebellar pilocytic astrocytomas have a distinctive gene signature and several differential expressed genes (ICAM1, CRK, CD36, and IQGAP1) are targets for available drugs: fluvastatin and/or celecoxib.

Results

Quantification by RT-Q-PCR of the expression of these genes was performed in a series of 51 pilocytic astrocytomas and 10 glioblastomas: they were all significantly overexpressed in hypothalamo-chiasmatic pilocytic astrocytomas relative to cerebellar pilocytic astrocytomas, and CRK and ICAM1 were significantly overexpressed in pilocytic astrocytomas versus glioblastomas.

We used two commercially available glioblastoma cell lines and three pilocytic astrocytoma explant cultures to investigate the effect of celecoxib/fluvastatin alone or in combination. Glioblastoma cell lines were sensitive to both drugs and a combination of 100 μM celecoxib and 240 μM fluvastatin was the most synergistic. This synergistic combination was used on the explant cultures and led to massive cell death of pilocytic astrocytoma cells.

As a proof of concept, a patient with a refractory multifocal pilocytic astrocytoma was successfully treated with the fluvastatin/celecoxib combination used for 18 months. It was well tolerated and led to a partial tumor response.

Conclusion

This study reports evidence for new targets and synergistic effect of celecoxib/fluvastatin combination in pilocytic astrocytoma. Because it is non-toxic, this new strategy offers hope for the treatment of patients with refractory pilocytic astrocytoma.

The statin-iron nexus: anti-inflammatory intervention for arterial disease prevention

OBJECTIVES

We postulated the existence of a statin-iron nexus by which statins improve cardiovascular disease outcomes at least partially by countering proinflammatory effects of excess iron stores.

METHODS

Using data from a clinical trial of iron (ferritin) reduction in advanced peripheral arterial disease, the Iron and Atherosclerosis Study, we compared effects of ferritin levels versus high-density lipoprotein to low-density lipoprotein ratios (both were randomization variables) on clinical outcomes in participants receiving and not receiving statins.

RESULTS

Statins increased high-density lipoprotein to low-density lipoprotein ratios and reduced ferritin levels by noninteracting mechanisms. Improved clinical outcomes were associated with lower ferritin levels but not with improved lipid status.

CONCLUSIONS

There are commonalities between the clinical benefits of statins and the maintenance of physiologic iron levels. Iron reduction may be a safe and low-cost alternative to statins.

Pravastatin and simvastatin improves acetylsalicylic acid-mediated in vitro blood platelet inhibition

BACKGROUND

Insight into the pathophysiology of atherothrombosis indicates that an integrated risk factor approach, focusing particularly on the management of dyslipidaemia (with statins) and thrombosis (with ASA), may constitute an optimal therapeutic approach. We investigated whether pravastatin, simvastatin and atorvastatin may directly modulate under in vitro conditions the reactivity of blood platelets originating from healthy volunteers. In addition, we analysed the influence of statins on the platelet sensitivity to ASA under such conditions.

MATERIALS AND METHODS

We monitored collagen- or ADP-induced platelet aggregation, CD36, PAC-1 and CD62 expression on platelet surface and thromboxane generation after incubation with pravastatin, simvastatin, atorvastatin and/or ASA.

RESULTS

The incubation of whole blood with simvastatin and pravastatin significantly decreased CD36 expression. In the presence of 50 μM ASA, simvastatin and pravastatin significantly reduced the PAC-1 expression (30% reduction for simvastatin, P < 0·01, and 15% reduction for pravastatin, P < 0·01), platelet aggregation (20% reduction for both statins, P < 0·01) and thromboxane generation (35% reduction for simvastatin, P < 0·001, and 30% reduction for pravastatin, P < 0·001) compared to ASA alone. Atorvastatin changed neither baseline platelet aggregation nor ASA-mediated platelet inhibition.

CONCLUSIONS

Our results suggested that statins may directly interact with platelet membranes or may modulate a signalling pathway in platelets (the pleiotropic effects of statins). It is possible that the statin effect on CD36 and ASA-mediated protein acetylation can be reached by the modulation of a distribution or a function of membrane-associated proteins. Further studies are certainly needed to better elucidate the mechanism(s) underlying the statins' effects on platelet sensitivity to ASA.

Pleiotropic effects of pitavastatin

3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) are established first line treatments for hypercholesterolaemia. In addition to the direct effects of statins in reducing concentrations of atherogenic low density lipoprotein cholesterol (LDL-C), several studies have indicated that the beneficial effects of statins may be due to some of their cholesterol-independent, multiple (pleiotropic) effects which may differ between different members of the class. Pitavastatin is a novel synthetic lipophilic statin that has a number of pharmacodynamic and pharmacokinetic properties distinct from those of other statins, which may underlie its potential pleiotropic benefits in reducing cardiovascular risk factors. This review examines the principal pleiotropic effects of pitavastatin on endothelial function, vascular inflammation, oxidative stress and thrombosis. The article is based on a systematic literature search carried out in December 2010, together with more recent relevant publications where appropriate. The available data from clinical trials and in vitro and animal studies suggest that pitavastatin is not only effective in reducing LDL-C and triglycerides, but also has a range of other effects. These include increasing high density lipoprotein cholesterol, decreasing markers of platelet activation, improving cardiac, renal and endothelial function, and reducing endothelial stress, lipoprotein oxidation and, ultimately, improving the signs and symptoms of atherosclerosis. It is concluded that the diverse pleiotropic actions of pitavastatin may contribute to reducing cardiovascular morbidity and mortality beyond that achieved through LDL-C reduction.

Effects of pitavastatin on plasminogen activator inhibitor-1 in hyperlipidemic patients

The effects of statins on two platelet activation markers, plasiminogen activator inhibitor (PAI)-1 and adiponectin, were investigated in 68 patients with hyperlipidemia. The patients were treated with pitavastatin with a dosage of 2 mg daily. The plasma levels of platelet-derived microparticles (PDMP), soluble CD40 ligand (sCD40L), sP-selectin, PAI-1, and adiponectin were measured at baseline and after 6 months of treatment in both groups. In hyperlipidemic patients, the plasma levels were higher in PDMP, sCD40L, sP-selectin, and PAI-1, and lower in adiponectin, compared to the normolipidemic controls. Plasma PDMP and sCD40L were positively correlated, while plasma adiponectin was negatively correlated with the plasma levels of PAI-1. No significant differences were observed in the plasma levels of PDMP, sCD40L, sP-selectin, and PAI-1 before and after treatment. A significant increase in plasma adiponectin levels was observed after 6 months of treatment with pitavastatin. When the patients treated with pitavastatin were divided into two groups according to the adiponectin response to pitavastatin treatment, significant decreases in plasma PAI-1, PDMP, and sCD40L levels were observed after pitavastatin treatment in the responder group. These findings suggest that PDMP, sCD40L, and PAI-1 may participate in the development of atherothrombosis in patients with hyperlipidemia, and that pitavastatin may exert an adiponectin-dependent anti-atherothrombotic effect in hyperlipidemic patients.

Effects of Fufang Zhenzhu Tiaozhi Prescription (), A Chinese herbal preparation, on atherosclerosis in ApoE-/- mice and related mechanisms

OBJECTIVE: The present study was designed to observe the effects and the possible mechanisms of Fufang Zhenzhu Tiaozhi Prescription (, FZT), a Chinese herbal preparation, on atherosclerosis in apolipoprotein E deficient (ApoE-/-) mice. METHODS: ApoE-/- mice were randomized to groups orally administrated without or with FZT (4.5 and 9 g crude drug/kg body weight, respectively). Atherosclerotic plaques, lipids profifiles in serum, aortic cholesterol content, serum indices of oxidative stress were measured, and mRNA expressions of scavenger receptors CD36 and scavenger receptor-A (SR-A) in aorta were analyzed. RESULTS: FZT dose-dependently suppressed the atherosclerotic plaques and reduced the cholesterol contents in aorta (P<0.05, P<0.01). In addition, FZT decreased the levels of total cholesterol and triglyceride in serum (P<0.05, P<0.01), inhibited the production of oxidized low density lipoprotein and malonaldehyde, and increased the superoxide dismutase activity in serum (P<0.05 or P<0.01). Furthermore, FZT down-regulated the mRNA expressions of CD36 and SR-A in the aorta (P<0.05, P<0.01). CONCLUSIONS: FZT reduced the atherosclerotic formation in ApoE-/- mice. The mechanisms might be related to the decrease of serum lipid level, the improvement of oxidative stress and the down-regulated expressions of scavenger receptors CD36 and SR-A, consequently reducing the foam cell formation, the hallmark of early atherosclerosis.

Cytokines, macrophage lipid metabolism and foam cells: implications for cardiovascular disease therapy

Cardiovascular disease is the biggest killer globally and the principal contributing factor to the pathology is atherosclerosis; a chronic, inflammatory disorder characterized by lipid and cholesterol accumulation and the development of fibrotic plaques within the walls of large and medium arteries. Macrophages are fundamental to the immune response directed to the site of inflammation and their normal, protective function is harnessed, detrimentally, in atherosclerosis. Macrophages contribute to plaque development by internalizing native and modified lipoproteins to convert them into cholesterol-rich foam cells. Foam cells not only help to bridge the innate and adaptive immune response to atherosclerosis but also accumulate to create fatty streaks, which help shape the architecture of advanced plaques. Foam cell formation involves the disruption of normal macrophage cholesterol metabolism, which is governed by a homeostatic mechanism that controls the uptake, intracellular metabolism, and efflux of cholesterol. It has emerged over the last 20 years that an array of cytokines, including interferon-γ, transforming growth factor-β1, interleukin-1β, and interleukin-10, are able to manipulate these processes. Foam cell targeting, anti-inflammatory therapies, such as agonists of nuclear receptors and statins, are known to regulate the actions of pro- and anti-atherogenic cytokines indirectly of their primary pharmacological function. A clear understanding of macrophage foam cell biology will hopefully enable novel foam cell targeting therapies to be developed for use in the clinical intervention of atherosclerosis.

Pitavastatin: finding its place in therapy

Dyslipidaemia is a major risk factor for cardiovascular (CV) disease. Despite the widespread availability of effective lipid-lowering agents, an unacceptably large proportion of patients fail to attain their target low-density lipoprotein cholesterol (LDL-C) level in clinical practice. Reasons for this include undertreatment, poor adherence/persistence with therapy and failure to address non-LDL-C residual risk factors such as high levels of triglycerides, low high-density lipoprotein cholesterol (HDL-C) concentrations and raised apolipoprotein B: apolipoprotein A1 ratios. Pitavastatin is a novel, well-tolerated statin with a noninferior or superior lipid-lowering efficacy to comparable doses of atorvastatin, simvastatin, and prava-statin in a wide range of patients with hypercholesterolemia or combined dyslipidaemia. Compared with other statins, pitavastatin produces consistently greater increases in HDL-C levels that are sustained over the long term. In addition to pravastatin's potent effects on lipid profiles, a number of pleiotropic benefits have been identified that may contribute to a reduction in residual cardiovascular risk in people with dyslipidaemia and could partly account for pitavastatin's ability to regress coronary plaques in patients with acute coronary syndrome. Pitavastatin's unique metabolic profile results in a high efficacy at low (1-4 mg) doses and minimal drug interactions with cytochrome CYP3A4 substrates, making it an excellent choice for people requiring multiple medications. Although future trials are required to assess the impact of pitavastatin treatment on CV morbidity and mortality, studies to date suggest that pitavastatin will play an important role in the future management of dyslipidaemia and in the overall reduction of CV risk.

Synthesis and structure-activity relationship of N-(2-arylethyl) isoquinoline derivatives as human scavenger receptor CD36 antagonists

By using human scavenger receptor CD36 as the target, twenty-five N-(2-arylethyl) isoquinoline derivatives were designed, synthesized and evaluated for their antagonistic activities for CD36-oxidatively low density lipoprotein (oxLDL) binding. The primary analysis of structure-activity relationship (SAR) indicated a methoxyl at the 7-position and a hydroxyl at the 6- or 8-position could afford good activities. Among these analogs, compounds 7e and 7t showed the potential CD36 antagonistic activities with IC(50) values of 0.2 and 0.8 μg/mL, respectively. Furthermore, both of them could effectively inhibit oxLDL uptake in insect Sf9 cells overexpressing human CD36, and thus have been selected for further investigation. We consider N-(2-arylethyl) isoquinoline analogs to be a family of novel CD36 antagonists.

Pitavastatin for the treatment of primary hyperlipidemia and mixed dyslipidemia

Pitavastatin is a new, synthetic member of the statin class of lipid-lowering drugs. Compared with other available statins, it has a unique cyclopropyl group on its base structure that is believed to increase 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibition by a factor of five and to significantly increase the transcription and activity of LDL receptors. Pitavastatin is primarily metabolized via glucuronidation and is not a substrate for the cytochrome P450 3A4 enzyme, thus avoiding the potential for cytochrome P450-mediated drug-drug interactions. Clinical trials have shown that pitavastatin is comparable to atorvastatin and simvastatin in improving lipid measures, and more potent than pravastatin. Pitavastatin is effective in reducing triglycerides and increasing HDL-cholesterol, so it will be particularly beneficial in treating patients with mixed dyslipidemia. Its safety and adverse event profile is similar to that of other available statins, and it has an established history of use in Asia indicating tolerability and safety for treatment lasting up to 7 years.

Literature mining for the discovery of hidden connections between drugs, genes and diseases

The scientific literature represents a rich source for retrieval of knowledge on associations between biomedical concepts such as genes, diseases and cellular processes. A commonly used method to establish relationships between biomedical concepts from literature is co-occurrence. Apart from its use in knowledge retrieval, the co-occurrence method is also well-suited to discover new, hidden relationships between biomedical concepts following a simple ABC-principle, in which A and C have no direct relationship, but are connected via shared B-intermediates. In this paper we describe CoPub Discovery, a tool that mines the literature for new relationships between biomedical concepts. Statistical analysis using ROC curves showed that CoPub Discovery performed well over a wide range of settings and keyword thesauri. We subsequently used CoPub Discovery to search for new relationships between genes, drugs, pathways and diseases. Several of the newly found relationships were validated using independent literature sources. In addition, new predicted relationships between compounds and cell proliferation were validated and confirmed experimentally in an in vitro cell proliferation assay. The results show that CoPub Discovery is able to identify novel associations between genes, drugs, pathways and diseases that have a high probability of being biologically valid. This makes CoPub Discovery a useful tool to unravel the mechanisms behind disease, to find novel drug targets, or to find novel applications for existing drugs.

The biomedical literature is an important source of knowledge on the function of genes and on the mechanisms by which these genes regulate cellular processes. Several text mining approaches have been developed to leverage this rich source of information by automatically extracting associations between concepts such as genes, diseases and drugs from a large body of text. Here, we describe a new method that extracts novel, not yet recognized associations between genes, diseases, drugs and cellular processes from the biomedical literature. Our method is built on the assumption that even if two concepts do not have a direct connection in literature, they may be functionally related if they are both connected to an overlapping set of concepts. Using this approach we predicted several novel connections between genes, diseases, drugs and pathways. Our results imply that our method is able to predict novel relationships from literature and, most importantly, that these newly identified relationships are biologically relevant. Our method can aid the drug discovery process where it can be used to find novel drug targets, increase insight in mode of action of a drug or find novel applications for known drugs.

Serum soluble CD36, assessed by a novel monoclonal antibody-based sandwich ELISA, predicts cardiovascular mortality in dialysis patients

AIM

Accelerated atherosclerosis is a characteristic feature of chronic kidney disease (CKD). CD36 is a scavenger receptor which contributes to foam cell formation, an early crucial step in atherosclerosis development. Recently, a soluble form of CD36 (sCD36) has been discovered. The aim of the study was to develop an ELISA method for quantitative sCD36 evaluation and to measure it in a cohort of CKD stage 5 patients.

METHOD

A novel monoclonal antibody-based sandwich ELISA for sCD36 evaluation was developed and verified by repeated optimization procedures. Serum concentration of sCD36 was then analyzed in a cohort of 228 CKD stage 5 patients prior to dialysis initiation. Additionally, samples from a control group of 73 healthy, age and gender-matched subjects were evaluated.

RESULTS

The novel CD36 ELISA assay had a recovery of at least 90%, and intra- and inter-assay variability of 6 and 11%, respectively. Concentration of serum sCD36 in CKD patients was significantly increased as compared to controls, and associated with the use of HMG-CoA reductase inhibitors (statins) and the presence of diabetes mellitus (DM). Patients above the 75th percentile of sCD36 concentration were at increased risk of 3-year cardiovascular mortality, as compared to the rest of the cohort [HR 2.85 (1.09-7.59) p=0.03].

CONCLUSION

For the first time, sCD36 was assessed quantitatively in a group of patients and showed associations with DM, CKD, and statin use. Furthermore, the concentration of sCD36 predicted cardiovascular mortality in CKD stage 5 patients.

Atorvastatin downregulates monocyte CD36 expression, nuclear NFkappaB and TNFalpha levels in type 2 diabetes

AIM

Type 2 diabetes increases the risk for cardiovascular disease, and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) reduce cardiovascular events in these patients. The benefits of statin therapy cannot be explained only by the lipid-lowering effect. The aim of this study was to test the effect of atorvastatin therapy on CD36 scavenger receptor expression, nuclear factor-kappaB (NFkappaB) levels and markers of inflammation (C-reactive protein, CRP, Tumor Necrosis Factor-alpha, TNF-alpha) in circulating monocytes from diabetic patients.

METHODS

Twenty-two type 2 diabetic patients were treated for 8 weeks with atorvastatin (20 mg/day). At baseline and after treatment a blood sample was collected for measurement of glucose, lipid profile (total cholesterol, HDL, LDL cholesterol, triglycerides), glycated hemoglobin (HbA1c), CRP and for isolation of monocytes.

RESULTS

Atorvastatin decreased total (p<0.0001) and LDL (p<0.01), and incresased HDL choles-terol (p<0.02). CD36 surface protein expression (anti-CD36 fluorescein isothiocyanate-FITC) was reduced in circulating monocytes after atorvastatin therapy (p<0.02) while immunoblot analysis showed reduced nuclear and increased cytoplasm NFkappaB levels (p<0.05). Finally, TNFalpha production in lipopolysaccharide-activated monocytes from patients treated with atorvastatin was reduced (p<0.05).

CONCLUSION

These results suggest that atorvastatin therapy, beside lowering serum cholesterol levels, could exert anti-atherogenic and anti-inflammatory effects in type 2 diabetic patients.

oxHDL decreases the expression of CD36 on human macrophages through PPARgamma and p38 MAP kinase dependent mechanisms

CD36, belongs to class B scavenger receptor family, is a macrophage receptor for oxidized low-density lipoprotein (oxLDL) and has been proven to play a critical role in atherosclerotic foam cell formation. In addition, CD36 expression is regulated by many factors including oxLDL and HDL. A recent study suggests that CD36 can also bind with oxidized high-density lipoprotein (oxHDL). However, the direct role of oxHDL in atherosclerosis is still not clear and it is not known whether oxHDL has any influence on the expression of CD36 in macrophages. Here, we performed experiments to investigate the effect of oxHDL on the expression of CD36 on human peripheral blood monocytes-macrophages and the possible mechanisms. Our results suggest that the uptake of oxHDL by CD36 on macrophages accelerates foam cell formation. In addition, oxHDL can down-regulate both the mRNA and surface protein expression of CD36 on human peripheral macrophages in vitro. oxHDL increased the mRNA expression and protein phosphorylation of peroxisome proliferators-activated receptor-gamma (PPARgamma). Using different mitogen-activated protein kinase (MAPK) inhibitors, we demonstrated that oxHDL regulated CD36 and PPARgamma expression in a p38-MAP kinase dependent mechanism.

Inhibition of foam cell formation using a soluble CD68-Fc fusion protein

The appearance of lipid-rich foam cells is a major feature of vulnerable atherosclerotic plaque formation. The transformation of macrophages into foam cells results from excessive uptake of cholesterol-rich particles by scavenger receptors such as CD68. We cloned a CD68-Fc immunoadhesin, a fusion protein consisting of the extracellular domain of the human CD68 and a human Fc domain, and investigated the function in vitro. Specific binding of CD68-Fc to OxLDL with an affinity of 10 nmol/L was determined by surface plasmon resonance and increased binding to lipid-rich human and ApoE(-/-) mice plaque tissue. This was confirmed both by immunohistochemical staining of CD68-Fc-treated paraffin sections from human plaques and by ELISA-based quantification of CD68-Fc binding to human atherosclerotic plaque extracts. In an in vitro model of macrophage/foam cell formation, CD68-Fc reduced foam cell formation significantly. This was caused both by interference of CD68-Fc with OxLDL uptake into macrophages and platelets and by the inhibition of platelet/OxLDL phagocytosis. Finally, expression of metalloproteinases by macrophages/foam cells was inhibited by CD68-Fc. In conclusion, CD68-Fc seems to be a promising new tool for preventing macrophage/foam cell formation. Thus, CD68-Fc might offer a novel therapeutic strategy for patients with acute coronary syndrome by modulating the generation of vulnerable plaques.

Effects of pitavastatin on monocyte chemoattractant protein-1 in hyperlipidemic patients

The effects of statins on platelet activation markers, chemokines and adiponectin, were investigated in 135 patients with hyperlipidemia. Of the 135 hyperlipidemic patients, 63 were allocated to the simvastatin group, treated with simvastatin at the dose of 10 mg daily, and the remaining 72 were allocated to the pitavastatin group, treated with pitavastatin at the dose of 2 mg daily. Plasma levels of platelet-derived microparticles (PDMP), cell adhesion molecules (sCD40L and sP-selectin), chemokines [monocyte chemoattractant protein-1 (MCP-1) and regulated on activation normally T-cell expressed and secreted] and adiponectin were measured at the baseline and after 6 months of treatment in both the groups. In addition, we carried out a basic study to investigate the MCP-1-dependent induction of tissue factor expression on a histiocytic cell line (U937 cells). The plasma levels of PDMP, sCD40L, sP-selectin, regulated on activation normally T-cell expressed and secreted and MCP-1 were higher, whereas those of adiponectin were lower, in the hyperlipidemic patients than in the normolipidemic controls. Plasma PDMP and sCD40L were positively correlated, whereas plasma adiponectin was negatively correlated, with the plasma levels of MCP-1. No significant differences in the plasma levels of PDMP, sCD40L, sP-selectin, regulated on activation normally T-cell expressed and secreted and MCP-1 measured before and after treatment were observed in either the simvastatin or pitavastatin group. A significant increase of the plasma adiponectin levels was observed after 6 months of treatment with pitavastatin but not after an equal duration of treatment with simvastatin. When pitavastatin-treated patients were divided into two groups according to the adiponectin response to pitavastatin treatment, significant decreases of the plasma MCP-1, PDMP and sCD40L levels were observed after pitavastatin treatment in the responder group. In the aforementioned basic study, MCP-1 by itself did not induce the expression of tissue factor on the U937 cells. However, the recombinant sCD40L-induced expression of tissue factor on U937 was enhanced by the addition of MCP-1. These findings suggest that PDMP, sCD40L and MCP-1 may participate in the development of atherothrombosis in patients with hyperlipidemia and that pitavastatin may exert an adiponectin-dependent antiatherothrombotic effect in hyperlipidemic patients.

Critical appraisal of the role of pitavastatin in treating dyslipidemias and achieving lipid goals

Pitavastatin is a potent HMG-CoA reductase inhibitor and efficient hepatocyte low-density lipoprotein cholesterol (LDL-C) receptor inducer, producing robust reduction of the serum LDL-C levels, even at a low dose. Pitavastatin and its lactone form are minimally metabolized by CYP enzymes, and are therefore associated with minimal drug-drug interactions (DDIs). Pitavastatin 2 to 4 mg has potent LDL-C-reducing activity, equivalent to that of atorvastatin 10 to 20 mg; several clinical trials have revealed consistently superior high-density lipoprotein cholesterol (HDL-C) elevating activity of pitavastatin than that of atorvastatin. Pitavastatin-induced HDL-C elevation has been shown to be sustained, even incremental, in long-term clinical trials. Pitavastatin was as well-tolerated as atorvastatin or simvastatin in double-blind randomized clinical trials. Two-year long-term safety and effectiveness of pitavastain has been confirmed in a large-scale, prospective post-marketing surveillance. The safety and efficacy profile of pitavastatin is favorable for the treatment of dyslipidemia, especially in metabolic syndrome patients. In addition to control of LDL-C, adequate control of triglyceride (TG) and HDL-C, hypertension and hyperglycemia is also necessary in metabolic syndrome patients. Pitavastatin produces adequate control of LDL-C and TG, along with potent and incremental HDL-C elevation, with a low frequency of DDIs.

Pitavastatin prevents intestinal ischemia/reperfusion-induced bacterial translocation and lung injury in atherosclerotic rats with hypoadiponectinemia

BACKGROUND

Atherosclerosis with hypoadiponectinemia can be further aggravated by intestinal ischemia/reperfusion (II/R)-induced injuries, such as bacterial translocation and lung injury. We investigated the effect of statin administration on the risk of II/R-induced injury in atherosclerotic rats with hypoadiponectinemia.

METHODS

Wistar rats were divided into 4 groups: (1) the Normal group (normal diet), (2) the Chol group (2% high cholesterol diet), (3) the St-1w group, and (4) the St-2w group (Chol group plus pitavastatin administration for 1 or 2 weeks, respectively). The serum concentrations of lipids and adiponectin were measured preoperatively. After midline laparotomy (time, T0), the superior mesenteric artery was occluded with a microvascular clamp for 30 min, followed by 360 min of reperfusion (T1). Intestinal and lung nitric oxide (NO) concentrations were measured. Intestinal injury was assessed by microcirculatory flow, histology, and permeability. Bacterial translocation was assessed by analysis of serum peptidoglycan concentration. Lung injury was assessed by histologic examination, pulmonary permeability index, and wet/dry lung weight ratio.

RESULTS

The 2-week administration of statins with high-cholesterol feeding (St-2w group) improved hypoadiponectinemia to levels similar to those of the Normal group. Intestinal and lung NO concentrations were significantly lower at T1 in the Normal and St-2w groups than in the Chol group. Statin administration improved poor recovery of intestinal microcirculatory flow in the Chol group. At T1, intestinal and lung injuries were significantly aggravated and serum peptidoglycan concentration was significantly elevated in the Chol group compared with the Normal and St-2w groups. The 1-week administration of statins had no significant influence on serum adiponectin levels, tissue NO concentration, or tissue injury.

CONCLUSION

Administration of pitavastatin reduces the risk of II/R-induced injury in atherosclerotic rats with hypoadiponectinemia by improving hypoadiponectinemia and inhibiting inducible NO synthase-produced NO. Furthermore, preoperative improvement of hypoadiponectinemia may be important as an index of the protective effect of pitavastatin for II/R-induced injury in atherosclerotic rats with hypoadiponectinemia.

The effects of pitavastatin, eicosapentaenoic acid and combined therapy on platelet-derived microparticles and adiponectin in hyperlipidemic, diabetic patients

Platelet-derived microparticles (PDMP) play an important role in the pathogenesis of diabetic vasculopathy, and statins or eicosapentaenoic acid (EPA) have been shown to have a beneficial effect on atherosclerosis in hyperlipidemic patients. However, the influence of EPA and statins on PDMP and adiponectin in atherosclerosis is poorly understood. We investigated the effect of pitavastatin and EPA on circulating levels of PDMP and adiponectin in hyperlipidemic patients with type II diabetes. A total of 191 hyperlipidemic patients with type II diabetes were divided into three groups: group A received pitavastatin 2 mg once daily (n = 64), group B received EPA 1800 mg daily (n = 55) and group C received both drugs (n = 72). PDMP and adiponectin were measured by ELISA at baseline and after 3 and 6 months of drug treatment. Thirty normolipidemic patients were recruited as healthy controls. PDMP levels prior to treatment in hyperlipidemic patients with diabetes were higher than levels in healthy controls (10.4 +/- 1.9 vs. 3.1 +/- 0.4 U/ml, p < 0.0001), and adiponectin levels were lower than controls (3.20 +/- 0.49 vs. 5.98 +/- 0.42 microg/ml, p < 0.0001). PDMP decreased significantly in group B (before vs. 6M, 10.6 +/- 2.0 vs. 8.0 +/- 1.7 U/ml, p < 0.01), but not in group A (before vs. 6M, 9.4 +/- 1.9 vs. 9.6 +/- 1.7 U/ml, not significant). In contrast, group A exhibited a significant increase in adiponectin levels after treatment (before vs. 6M, 3.29 +/- 0.51 vs. 4.16 +/- 0.60 microg/ml, p < 0.001). Furthermore, group C exhibited significant improvement in both PDMP and adiponectin levels after treatment (PDMP, before vs. 6M, 11.2 +/- 2.0 vs. 4.5 +/- 2.7 U/ml, p < 0.001; adiponectin, before vs. 6M, 3.24 +/- 0.41 vs. 4.02 +/- 0.70 microg/ml, p < 0.001). Reductions of PDMP in combined therapy were significantly greater than those observed with EPA alone (p < 0.05 by ANOVA). In addition, soluble CD40 ligand exhibited almost the same change as PDMP in all therapy groups. These results suggest that pitavastatin possesses an adiponectin-dependent antiatherosclerotic effect, and this drug is able to enhance the anti-platelet effect of EPA. The combination therapy of pitavastatin and EPA may be beneficial for the prevention of vascular complication in hyperlipidemic patients with type II diabetes.

Pitavastatin suppresses mitogen activated protein kinase-mediated Erg-1 induction in human vascular smooth muscle cells

Statins have been demonstrated to elicit a broad range of cellular events resulting in an attenuation of the inflammatory response and enhanced protection to the components of the vessel wall. The present study was designed to examine the effect of pitavastatin on pathways associated with the proinflammatory gene, early growth response (Egr)-1, in human vascular smooth muscle cells. Pretreatment with pitavastatin resulted in a dose-dependent reduction in Egr-1 protein and suppressed Egr-1 mRNA expression in response to phorbol 12-myristate 13-acetate (PMA). A reduction in Egr-1 expression reduced the activation of NGFI-A binding protein (NAB)-2, an Egr-1-dependent gene. Furthermore, these events appeared to be dependent on the ability of pitavastatin to attenuate signaling cascades associated with extracellular regulated kinase (ERK) 1/2, but not p38 and c-Jun N-terminal kinase (JNK).

Effects of pitavastatin on adiponectin in patients with hyperlipidemia

The effects of treatment with pitavastatin on inflammatory and platelet activation markers and adiponectin in 117 patients with hyperlipidemia were investigated to determine whether pitavastatin may prevent the progression of atherosclerotic changes in hyperlipidemic patients. Adiponectin levels prior to pitavastatin treatment in hyperlipidemic patients with and without diabetes were lower than levels in normolipidemic controls. Both total cholesterol and the low-density lipoprotein cholesterol decreased significantly after pitavastatin administration. Additionally, hyperlipidemic patients with or without type 2 diabetes exhibited a significant increase in adiponectin levels 6 months after pitavastatin treatment (diabetes: 3.52 +/- 0.80 vs. 4.52 +/- 0.71 microg/ml, p < 0.001; no diabetes: 3.48 +/- 0.71 vs. 4.23 +/- 0.82 microg/ml, p < 0.05). However, high-sensitivity C-reactive protein, platelet-derived microparticle and soluble P-selectin did not exhibit any differences before or after pitavastatin administration. Levels of adiponectin significantly increased after pitavastatin administration in the group of lower soluble P-selectin (soluble P-selectin before pitavastatin treatment <200 ng/ml). These results suggest that pitavastatin possesses an adiponectin-increasing effect in patients with hyperlipidemia and this effect is influenced by intensive platelet activation.

Correlation between adiponectin and reduction of cell adhesion molecules after pitavastatin treatment in hyperlipidemic patients with type 2 diabetes mellitus

The aim of this study was to determine whether pitavastatin may prevent the progression of atherosclerotic changes in hyperlipidemic patients. Seventy-five hyperlipidemic patients with and without type 2 diabetes were enrolled to receive pitavastatin 2 mg daily. Cell adhesion molecules (sCD40L, sP-selectin, sE-selectin, and sL-selectin), chemokines (MCP-1 and RANTES) and adiponectin were measured at baseline and after 3 and 6 months of pitavastatin treatment. Adiponectin levels prior to pitavastatin treatment in hyperlipidemic patients with and without diabetes were lower than levels in normolipidemic controls. Both total cholesterol and the LDL-cholesterol (LDL-C) decreased significantly after pitavastatin administration. Additionally, hyperlipidemic patients with type 2 diabetes exhibited a significant increase in adiponectin levels after pitavastatin treatment (before vs. 3 months, 6 months, 2.81+/-0.95 vs. 3.84+/-0.84 microg/ml (p<0.01), 4.61+/-1.15 mug/ml (p<0.001)). Furthermore, hyperlipidemic diabetics exhibited significant decreases in sE-selectin and sL-selectin levels after 6 months of pitavastatin treatment (sE-selectin, before vs. 6 months, 74+/-21 vs. 51+/-10 ng/ml, p<0.05; sL-selectin, before vs. 6 months, 896+/-141 vs. 814+/-129 ng/ml, p<0.05). In addition, adiponectin showed significant correlation with sE-selectin and sL-selectin in diabetic hyperlipidemia. However, MCP-1, RANTES and sCD40L did not exhibit any differences before or after pitavastatin administration. These results suggest that pitavastatin possesses an adiponectin-dependent anti-atherosclerotic effect in hyperlipidemic patients with type 2 diabetes in addition to its lowering effects on total cholesterol and LDL-C.

Statins and foam cell formation: Impact on LDL oxidation and uptake of oxidized lipoproteins via scavenger receptors

The uptake of oxidized lipoproteins via scavenger receptors and the ensuing formation of foam cells are key events during atherogenesis. Foam cell formation can be reduced by treatment with 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins). The efficacy of statins is evidently due not only to their cholesterol-lowering properties, but also to lipid-independent pleiotropic effects. This review focuses on lipid-independent pleiotropic effects of statins that influence foam cell formation during atherogenesis, with special emphasis on oxidative pathways and scavenger receptor expression.

Endothelial lipase is increased by inflammation and promotes LDL uptake in macrophages

AIM

Endothelial lipase (EL) is a member of the lipoprotein lipase family that regulates HDL metabolism. EL is known to act as a bridging molecule for monocytes or lipoproteins in vascular endothelial cells. We investigated the role and regulatory mechanisms of EL expression in macrophages.

METHODS

Macrophages originating from wild-type (EL+/+) and EL-deficient (EL-/-) mice were stimulated with lipopolysaccharide (LPS). The expression of EL mRNA was evaluated by northern blotting. DiI-LDL was used to measure the uptake of native low-density lipoprotein (nLDL).

RESULTS

LPS increased EL mRNA levels by increasing intracellular oxidative stress in the macrophages. LPS did not affect EL expression in macrophages derived from Toll-like receptor 4 (TLR4) gene mutant mice, C3H/HeJ. The uptake of nLDL after LPS-treatment was significantly lower in macrophages from EL-/- mice than those from EL+/+ mice. Simvastatin suppressed the LPS-induced upregulation of EL expression and uptake of nLDL.

CONCLUSIONS

EL expression is upregulated by LPS via TLR4 and promotes the uptake of nLDL by macrophages. Simvastatin inhibits the LPS-induced up-regulation and uptake in macrophages. Thus, our findings provide a novel role for EL in lipoprotein metabolism and would expand the range of anti-atherogenic effects of statins.

CD36: implications in cardiovascular disease

CD36 is a broadly expressed membrane glycoprotein that acts as a facilitator of fatty acid uptake, a signaling molecule, and a receptor for a wide range of ligands, including apoptotic cells, modified forms of low density lipoprotein, thrombospondins, fibrillar beta-amyloid, components of Gram positive bacterial walls and malaria infected erythrocytes. CD36 expression on macrophages, dendritic and endothelial cells, and in tissues including muscle, heart, and fat, suggest diverse roles, and indeed, this is truly a multi-functional receptor involved in both homeostatic and pathological conditions. Despite an impressive increase in our knowledge of CD36 functions, in depth understanding of the mechanistic aspects of this protein remains elusive. This review focuses on CD36 in cardiovascular disease-what we know, and what we have yet to learn.