Current, new and future treatments in dyslipidaemia and atherosclerosis

Floralozone attenuates atherosclerotic vascular injury by regulating AMPKα/SREBP-1c pathway and down-regulating miR-33-5p

BACKGROUND

Severe disruption of lipid metabolism in vivo is one of the central mechanisms in the development of atherosclerotic vascular injury (AVI). Reverse cholesterol transport (RCT) plays a pivotal role in eliminating excess cholesterol, preventing lipid deposition in the aorta, and reducing plaque formation associated with AVI. Floralozone (FL) reduces endothelial cell injury in AVI rats by regulating sphingosine-1-phosphate (S1P) expression. However, FL's potential to prevent AVI by modulating cholesterol metabolism remains unknown.

METHODS

In this study, network pharmacology and molecular docking predicted FL's potential targets in AVI protection. AVI rats were induced with a high-sugar, high-fat diet and vitamin D3 injection. FL intervention's effects on aortic pathology and lipid levels were assessed. The expression levels of SREBP-1c, PPARγ, ABCA1, and ABCG1 were evaluated. Raw264.7 macrophages were induced to form foam cells with ox-LDL, and FL's effects on the AMPKα/SREBP-1c pathway and miR-33-5p were investigated.

RESULTS

FL reduced lipid levels and SREBP-1c expression, increased HDL-C, promoted ABCA1- and ABCG1-mediated cholesterol efflux, and reduced aortic cholesterol accumulation. The AMPKα inhibitor dorsomorphin blocked FL's inhibition of intracellular cholesterol accumulation and SREBP1 down-regulation in foam cells. FL decreased miR-33-5p expression but up-regulated PPARγ, promoting ABCA1- and ABCG1-mediated cholesterol efflux. However, miR-33-5p mimic reduced FL-induced cholesterol efflux, while miR-33-5p inhibitor increased it.

CONCLUSION

FL may promote foam cell cholesterol efflux by modifying the AMPKα/SREBP-1c pathway and down-regulating miR-33-5p, which targets cholesterol metabolism genes (PPARγ, ABCA1, and ABCG1). These findings provide a new insight into the protective effect of FL on AVI.

A cross-tissue transcriptome-wide association study identifies WDPCP as a potential susceptibility gene for coronary atherosclerosis

Background

Coronary atherosclerosis (CAS) is a complex chronic inflammatory disease with significant genetic and environmental contributions. While genome-wide association studies (GWAS) have pinpointed many risk loci, over 75 % are in non-coding regions, complicating functional analysis and understanding gene-disease mechanisms.

Methods

We conducted a cross-tissue transcriptome-wide association study (TWAS) using data from the GWAS Catalog (16,041 cases, 440,307 controls) and the Genotype-Tissue Expression (GTEx) v8 eQTL dataset. Initially, we used the Unified Test for Molecular Signatures (UTMOST) for analysis, followed by validation with Functional Summary-based Imputation (FUSION) and conditional and joint (COJO) analyses. Candidate genes were further refined using Multi-marker Analysis of Genomic Annotation (MAGMA). Causal relationships were assessed through Summary Data-Based Mendelian Randomization (SMR), colocalization analysis (COLOC), and Mendelian Randomization (MR). GeneMANIA was used to identify interacting genes, and Phenome-Wide Association Study (PheWAS) was employed to enhance the results.

Results

UTMOST identified 33 susceptibility genes for CAS. Out of these, 17 met stringent criteria in both UTMOST and FUSION analyses. Combining results from UTMOST, FUSION, and MAGMA, we identified four critical candidate genes. WDPCP was the only gene to pass SMR, COLOC, and MR analyses, confirming its causal role in CAS. GeneMANIA revealed additional interacting genes, and PheWAS validated WDPCP's role as a susceptibility gene.

Conclusion

WDPCP is a potential novel susceptibility gene for CAS, influencing endothelial function, lipid metabolism, and coronary artery development. This study extends GWAS findings, highlighting WDPCP's potential as a therapeutic target and its consistent expression across different tissues. Further validation studies are warranted.

Non-alcoholic fatty liver disease: a metabolic burden promoting atherosclerosis

Non-alcoholic fatty liver disease (NAFLD) has become the fastest growing chronic liver disease, with a prevalence of up to 25% worldwide. Individuals with NAFLD have a high risk of disease progression to cirrhosis, hepatocellular carcinoma (HCC), and liver failure. With the exception of intrahepatic burden, cardiovascular disease (CVD) and especially atherosclerosis (AS) are common complications of NAFLD. Furthermore, CVD is a major cause of death in NAFLD patients. Additionally, AS is a metabolic disorder highly associated with NAFLD, and individual NAFLD pathologies can greatly increase the risk of AS. It is increasingly clear that AS-associated endothelial cell damage, inflammatory cell activation, and smooth muscle cell proliferation are extensively impacted by NAFLD-induced systematic dyslipidemia, inflammation, oxidative stress, the production of hepatokines, and coagulations. In clinical trials, drug candidates for NAFLD management have displayed promising effects for the treatment of AS. In this review, we summarize the key molecular events and cellular factors contributing to the metabolic burden induced by NAFLD on AS, and discuss therapeutic strategies for the improvement of AS in individuals with NAFLD.

Modulatory effects of curcumin on the atherogenic activities of inflammatory monocytes: Evidence from in vitro and animal models of human atherosclerosis

Atherosclerosis is a complex and long-lasting disorder characterized by chronic inflammation of arteries that leads to the initiation and progression of lipid-rich plaques, in which monocytes/macrophages play the central role in endothelial inflammation and taking up these lipids. Circulating monocytes can adopt a long-term proinflammatory phenotype leading to their atherogenic activities. During atherogenic condition, inflammatory monocytes adhere to the surface of the activated endothelial cells and then transmigrate across the endothelial monolayer into the intima, where they proliferate and differentiate into macrophages and take up the lipoproteins, forming foam cells that derive atherosclerosis progression. Therefore, modulating the atherogenic activities of inflammatory monocytes can provide a valuable therapeutic approach for atherosclerosis prevention and treatment. Curcumin is a naturally occurring polyphenolic compound with numerous pharmacological activities and shows protective effects against atherosclerosis; however, underlying mechanisms are not clearly known yet. In the present review, on the basis of a growing body of evidence, we show that curcumin can exert antiatherosclerotic effect through inhibiting the atherogenic properties of monocytes, including inflammatory cytokine production, adhesion, and transendothelial migration, as well as intracellular cholesterol accumulation.

CTRP3 Alleviates Ox-LDL-Induced Inflammatory Response and Endothelial Dysfunction in Mouse Aortic Endothelial Cells by Activating the PI3K/Akt/eNOS Pathway

C1q/tumor necrosis factor-related protein-3 (CTRP3) is a novel, certified, adipokine that beneficially regulates metabolism and inflammation in the cardiovascular system. Atherosclerotic plaque rupturing and secondary thrombosis cause vascular disorders, such as myocardial infarction and unstable angina. However, the underlying role of CTRP3 in atherosclerosis remains unclear. In this study, we aimed to elucidate whether and how CTRP3 ameliorates inflammation and endothelial dysfunction caused by oxidized low-density lipoprotein (ox-LDL). We first confirmed that CTRP3 expression was inhibited in ApoE-/- mice, compared to normal mice. Then, pcDNA-CTRP3 and siCTRP3 were transfected into mouse aortic endothelial cells after ox-LDL stimulation, and we observed that enhanced CTRP3 remarkably downregulated CRP, TNF-α, IL-6, CD40, and CD40L. We also observed that overexpression of CTRP3 elevated cell activity and decreased lactated hydrogenase release, accompanied by a marked reduction in cell apoptosis induced by ox-LDL. Meanwhile, overexpressed CTRP3 caused a decrease in Ang II, ICAM-1, and VCAM-1 expression, and it restored the balance between ET-1 and NO. Mechanism analysis confirmed that incremental CTRP3 upregulated p-PI3K, p-Akt, and p-eNOS expression, indicating that CTRP3 facilitated activation of the PI3K/Akt/eNOS pathway. On the contrary, siCTRP3 exerted the opposite effect to this activation. Blocking these pathways using LY294002 or L-NAME attenuated the protective role of CTRP3. Overall, these results suggest that CTRP3 can efficiently inhibit the inflammatory response and endothelial dysfunction induced by ox-LDL in mouse aortic endothelial cells, perhaps by activating the PI3K/Akt/eNOS pathway, indicating a promising strategy against atherosclerosis.

Therapeutic effect of nanoliposomal PCSK9 vaccine in a mouse model of atherosclerosis

BACKGROUND

Proprotein convertase subtilisin/kexin 9 (PCSK9) is an important regulator of low-density lipoprotein receptor (LDLR) and plasma levels of LDL cholesterol (LDL-C). PCSK9 inhibition is an efficient therapeutic approach for the treatment of dyslipidemia. We tested the therapeutic effect of a PCSK9 vaccine on dyslipidemia and atherosclerosis.

METHODS

Lipid film hydration method was used to prepare negatively charged nanoliposomes as a vaccine delivery system. An immunogenic peptide called immunogenic fused PCSK9-tetanus (IFPT) was incorporated on the surface of nanoliposomes using DSPE-PEG-maleimide lipid (L-IFPT) and adsorbed to Alhydrogel® (L-IFPTA+). The prepared vaccine formulation (L-IFPTA+) and empty liposomes (negative control) were inoculated four times with bi-weekly intervals in C57BL/6 mice on the background of a severe atherogenic diet and poloxamer 407 (thrice weekly) injection. Antibody titers were evaluated 2 weeks after each vaccination and at the end of the study in vaccinated mice. Effects of anti-PCSK9 vaccination on plasma concentrations of PCSK9 and its interaction with LDLR were determined using ELISA. To evaluate the inflammatory response, interferon-gamma (IFN-γ)- and interleukin (IL)-10-producing splenic cells were assayed using ELISpot analysis.

RESULTS

L-IFPTA+ vaccine induced a high IgG antibody response against PCSK9 peptide in the vaccinated hypercholesterolemic mice. L-IFPTA+-induced antibodies specifically targeted PCSK9 and decreased its plasma consecration by up to 58.5% (- 164.7 ± 9.6 ng/mL, p = 0.0001) compared with the control. PCSK9-LDLR binding assay showed that generated antibodies could inhibit PCSK9-LDLR interaction. The L-IFPTA+ vaccine reduced total cholesterol, LDL-C, and VLDL-C by up to 44.7%, 51.7%, and 19.2%, respectively, after the fourth vaccination booster, compared with the control group at week 8. Long-term studies of vaccinated hypercholesterolemic mice revealed that the L-IFPTA+ vaccine was able to induce a long-lasting humoral immune response against PCSK9 peptide, which was paralleled by a significant decrease of LDL-C by up to 42% over 16 weeks post-prime immunization compared to control. Splenocytes isolated from the vaccinated group showed increased IL-10-producing cells and decreased IFN-γ-producing cells when compared with control and naive mice, suggesting the immune safety of the vaccine.

CONCLUSIONS

L-IFPTA+ vaccine could generate long-lasting, functional, and safe PCSK9-specific antibodies in C57BL/6 mice with severe atherosclerosis, which was accompanied by long-term therapeutic effect against hypercholesterolemia and atherosclerosis.

Design, synthesis and biological evaluation of hypolipidemic compounds based on BRD4 inhibitor RVX-208

Bromodomain-containing protein 4 (BRD4) is a new therapeutic target for the treatment of diseases including cardiovascular diseases, cancer, inflammation and central nervous system (CNS) disorders. In this study, we introduced the pharmacophore of fibrates to a BRD4 inhibitor, RVX-208, to design dual-active hypolipidemic compounds, and found that some of new analogues showed favorable hypolipidemic activities. Synthetic accessibility towards this class of compounds optimized RVX-208 as well as would supply more thoughts on hypolipidemic drugs.

Beneficial effects of green cardamom on serum SIRT1, glycemic indices and triglyceride levels in patients with type 2 diabetes mellitus: a randomized double-blind placebo controlled clinical trial

BACKGROUND

Cardamom has antioxidant and anti-inflammatory effects which may help to remedy diseases. Studies on the health benefits of cardamom in diabetic patients are very limited. Thus, this study is designed to determine the effect of cardamom supplementation on blood lipids and glycemic indices in type 2 diabetic patients. To investigate the mechanism of cardamom effect on blood glucose and lipid levels, serum sirtuin-1 (SIRT1) was assessed.

RESULTS

In a parallel, double-blind randomized, placebo-controlled clinical trial, 83 overweight or obese type 2 diabetic patients were randomly allocated into an intervention (n = 41) or a control group (n = 42). The intervention and the placebo group received 3 g of green cardamom or rusk powder, respectively for 10 weeks. Physical activity level, dietary intake, anthropometric measurements (weight, height and waist circumference), glycemic indices [glucose, insulin, hemoglobin A1c (HbA1c)], blood lipids [triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-c) and low-density lipoprotein cholesterol (LDL-c)] and SIRT1 levels were measured. Body mass index and homeostasis model assessment as an index of insulin resistance (HOMA-IR) were calculated before and after intervention. Compared to the control group, a significant decrease in serum HbA1C (-0.4%), insulin (-2.8 µIU dL^-1 ), HOMA-IR (-1.7) and TG (-39.9 mg dL^-1 ), and an increase in SIRT1 (2.3 ng mL^-1 ) was observed in cardamom group. There were no significant changes in serum TC, HDL-c and LDL-c levels between the two groups before and after adjustment for potential confounders including glyclaside dose, duration of disease and weight.

CONCLUSION

Our results showed that cardamom can decrease HbA1c, insulin level, HOMA-IR and TG level via increase in SIRT1 concentration in type 2 diabetes mellitus patients. © 2019 Society of Chemical Industry.

The AT04A vaccine against proprotein convertase subtilisin/kexin type 9 reduces total cholesterol, vascular inflammation, and atherosclerosis in APOE*3Leiden.CETP mice

Aims

Proprotein convertase subtilisin/kexin type 9 (PCSK9) has emerged as a promising therapeutic target for the treatment of hypercholesterolaemia and atherosclerosis. PCSK9 binds to the low density lipoprotein receptor and enhances its degradation, which leads to the reduced clearance of low density lipoprotein cholesterol (LDLc) and a higher risk of atherosclerosis. In this study, the AT04A anti-PCSK9 vaccine was evaluated for its therapeutic potential in ameliorating or even preventing coronary heart disease in the atherogenic APOE*3Leiden.CETP mouse model.

Methods and results

Control and AT04A vaccine-treated mice were fed western-type diet for 18 weeks. Antibody titres, plasma lipids, and inflammatory markers were monitored by ELISA, FPLC, and multiplexed immunoassay, respectively. The progression of atherosclerosis was evaluated by histological analysis of serial cross-sections from the aortic sinus. The AT04A vaccine induced high and persistent antibody levels against PCSK9, causing a significant reduction in plasma total cholesterol (−53%, P < 0.001) and LDLc compared with controls. Plasma inflammatory markers such as serum amyloid A (SAA), macrophage inflammatory protein-1β (MIP-1β/CCL4), macrophage-derived chemokine (MDC/CCL22), cytokine stem cell factor (SCF), and vascular endothelial growth factor A (VEGF-A) were significantly diminished in AT04A-treated mice. As a consequence, treatment with the AT04A vaccine resulted in a decrease in atherosclerotic lesion area (−64%, P = 0.004) and aortic inflammation as well as in more lesion-free aortic segments (+119%, P = 0.026), compared with control.

Conclusions

AT04A vaccine induces an effective immune response against PCSK9 in APOE*3Leiden.CETP mice, leading to a significant reduction of plasma lipids, systemic and vascular inflammation, and atherosclerotic lesions in the aorta.

Hybrids of coumarin–indole: design, synthesis and biological evaluation in Triton WR-1339 and high-fat diet induced hyperlipidemic rat models

Lipid lowering activity of novel coumarin–indole hybrids has been demonstrated.

Peptide-based anti-PCSK9 vaccines - an approach for long-term LDLc management

BACKGROUND

Low Density Lipoprotein (LDL) hypercholesterolemia, and its associated cardiovascular diseases, are some of the leading causes of death worldwide. The ability of proprotein convertase subtilisin/kexin 9 (PCSK9) to modulate circulating LDL cholesterol (LDLc) concentrations made it a very attractive target for LDLc management. To date, the most advanced approaches for PCSK9 inhibition are monoclonal antibody (mAb) therapies. Although shown to lower LDLc significantly, mAbs face functional limitations because of their relatively short in vivo half-lives necessitating frequent administration. Here, we evaluated the long-term efficacy and safety of PCSK9-specific active vaccines in different preclinical models.

METHODS AND FINDING

PCSK9 peptide-based vaccines were successfully selected by our proprietary technology. To test their efficacy, wild-type (wt) mice, Ldlr+/- mice, and rats were immunized with highly immunogenic vaccine candidates. Vaccines induced generation of high-affine PCSK9-specific antibodies in all species. Group mean total cholesterol (TC) concentration was reduced by up to 30%, and LDLc up to 50% in treated animals. Moreover, the PCSK9 vaccine-induced humoral immune response persisted for up to one year in mice, and reduced cholesterol levels significantly throughout the study. Finally, the vaccines were well tolerated in all species tested.

CONCLUSIONS

Peptide-based anti-PCSK9 vaccines induce the generation of antibodies that are persistent, high-affine, and functional for up to one year. They are powerful and safe tools for long-term LDLc management, and thus may represent a novel therapeutic approach for the prevention and/or treatment of LDL hypercholesterolemia-related cardiovascular diseases in humans.

Having excess levels of PCSK9 is not sufficient to induce complex formation between PCSK9 and the LDL receptor

Proprotein convertase subtilisin/kexin-9 (PCSK9) acts mainly by forming complexes with the LDL receptor at the cell surface, which are then degraded in the lysosome. Studies were performed to determine whether excess levels of PCSK9 was sufficient to induce PCSK9/LDL receptor complex formation in human hepatocyte-like C3A cells. It was demonstrated using ELISA that instead of considering the overall levels of PCSK9 protein that is produced in response to certain treatment, what is critical is how much PCSK9 is actually capable of forming complexes. Despite the high levels, most of the PCSK9 produced as a result of incubating cells with a medium supplemented with BD™ MITO+ serum extender (MITO+ medium) appeared to be inhibited by a secreted factor. Having lower levels of PCSK9/LDL receptor complexes did not prevent an increase in the degradation rate of LDL receptors in MITO+ medium as compared to fetal bovine serum (FBS) containing medium (Regular medium), an effect that did not correlate with an increase in protein levels of the inducible degrader of LDL receptors (IDOL), as demonstrated using Western blotting analysis. Additional studies are required to determine the exact mechanism(s) for the degradation of the LDL receptor and/or to identify the secreted inhibitor of PCSK9.

A mechanism-based pharmacological evaluation of efficacy of Trigonella foenum graecum (fenugreek) seeds in regulation of dyslipidemia and oxidative stress in hyperlipidemic rats

: Alcoholic extract of Trigonella foenum graecum seeds [fenugreek seed extract (FSE)] was studied in triton-induced and high-fat diet-induced hyperlipidemia to evaluate antidyslipidemic effect. Plasma cholesterol (26.19%) and triglycerides (36.6%) were found to be lowered by FSE maximum at a dose of 200 mg/kg body weight in triton-treated hyperlipidemic rats. Chronic feeding of FSE (200 mg/kg body weight) caused lowering in plasma and hepatic lipid levels by activating lecithin-cholesterol acyltransferase (47%), postheparin lipolytic activity (35%), triglyceride lipase (34%), lipoprotein lipase (20.8%), and increased excretion of fecal bile acids (36%-45%). The FSE shows potent antioxidant activity in both in vitro and in vivo systems. It inhibited generation of superoxide anion and hydroxyl free radicals in both enzymatic and nonenzymatic systems significantly at 200 µM concentration. Furthermore, FSE normalizes the activities of antioxidant enzymes, that is, superoxide dismutase and catalase, and reduces plasma lipid peroxidation (33.9%), hepatic 4-hydroxynonenal (27%), and isoprostanes (28%). Data of the present study demonstrated that the T. foenum graecum seed extract has both antidyslipidemic and antioxidant properties.

Laser capture microdissection for analysis of macrophage gene expression from atherosclerotic lesions

Coronary artery disease, resulting from atherosclerosis, is the leading cause of death in the Western world. Most previous studies have subjected atherosclerotic arteries, a tissue of mixed cellular composition, to homogenization in order to identify the factors in plaque development, thereby obscuring information relevant to specific cell types. Because macrophage foam cells are critical mediators in atherosclerotic plaque advancement, we reasoned that performing gene analysis on those cells would provide specific insight in novel regulatory factors and potential therapeutic targets. We demonstrated for the first time in vascular biology that foam cell-specific RNA can be isolated by laser capture microdissection (LCM) of plaques. As expected, compared to whole tissue, a significant enrichment in foam cell-specific RNA transcripts was observed. Furthermore, because regression of atherosclerosis is a tantalizing clinical goal, we developed and reported a transplantation-based mouse model. This involved allowing plaques to form in apoE-/- mice and then changing the plaque's plasma environment from hyperlipidemia to normolipidemia. Under those conditions, rapid regression ensued in a process involving emigration of plaque foam cells to regional and systemic lymph nodes. Using LCM, we were able to show that under regression conditions, there was decreased expression in foam cells of inflammatory genes, but an up-regulation of cholesterol efflux genes. Interestingly, we also found that increased expression of chemokine receptor CCR7, a known factor in dendritic cell migration, was required for regression. In conclusion, the LCM methods described in this chapter, which have already lead to a number of striking findings, will likely further facilitate the study of cell type-specific gene expression in animal and human plaques during various stages of atherosclerosis, and after genetic, pharmacologic, and environmental perturbations.

Beneficial Effects of Pentanema vestitum Linn. Whole Plant on the Glucose and Other Biochemical Parameters of Alloxan Induced Diabetic Rabbits

The residents of Lower Dir and Malakand agency, Khyber Pakhtunkhwa, Pakistan, use the dry powder of whole plant of Pentanema vestitum for the treatment of asthma and diabetes. No documented reports are available about the therapeutic action of Pentanema vestitum. The present study was aimed to explore the antihyperglycemic effect of 70% methanol extract of Pentanema vestitum whole plant in glucose-induced nondiabetic hyperglycemic and alloxan-induced diabetic rabbits. During this study, the effects of plant extract on the serum lipid profile, GPT, ALP, bilirubin and creatinine of diabetic rabbits were also studied. The extract of Pentanema vestitum whole plant exhibited significant (P < 0.05) antihyperglycemic activity in glucose-induced hyperglycemic rabbits. Treatment of alloxan-induced diabetic rabbits with extract significantly (P < 0.05) reduced the elevated levels of serum glucose, GPT, ALP, bilirubin and creatinine. During the study of lipid profile, the extract proved to be antihyperlipidemic and HDL boosting in diabetic rabbit models. From the finding of the present research, it was concluded that the 70% methanol extract of Pentanema vestitum whole plant has beneficial effects on serum levels of glucose, lipid profile, GPT, ALP, bilirubin, and creatinine of diabetic rabbits.

The effect of pumpkin (Cucurbita pepo L) seeds and L-arginine supplementation on serum lipid concentrations in atherogenic rats

The present study aimed to examine the effect of pumpkin (Cucurbita pepo L.) seeds supplementation on atherogenic diet-induced atherosclerosis. Rat were divided into two main groups , normal control and atherogenic control rats , each group composed of three subgroups one of them supplemented with 2% arginine in drinking water and the other supplemented with pumpkin seeds in diet at a concentration equivalent to 2% arginine. Supplementation continued for 37 days. Atherogenic rats supplemented with pumpkin seeds showed a significant decrease (p<0.001) in their serum concentrations of total cholesterol and LDL - C as they dropped from 4.89 mmol / L to 2.55 mmol /L and from 3.33 mmol / L to 0.70 mmol / L respectively. Serum concentrations of HDL-C were also significantly elevated in the same group. Although, atherogenic rats supplemented with 2% arginine showed significant increase in serum concentration of HDL-C, no significant changes were observed in their serum concentrations of total cholesterol and LDL-C. Our results showed that treatment of atherogenic rats with pumpkin seeds significantly decreased serum concentrations of TC and LDL-C. Our findings suggest that pumpkin seeds supplementation has a protective effect against atherogenic rats and this protective effect was not attributed to the high arginine concentrations in pumpkin seeds.

Modulatory effects of garlic, ginger, turmeric and their mixture on hyperglycaemia, dyslipidaemia and oxidative stress in streptozotocin-nicotinamide diabetic rats

Spices which show hypoglycaemic, hypolipidaemic and antioxidant activities may have a role in the treatment of diabetes and its complications. The present study aimed to compare the modulatory effects of garlic, ginger, turmeric and their mixture on the metabolic syndrome and oxidative stress in streptozotocin (STZ)-nicotinamide diabetic rats. Diabetes was induced in overnight fasted rats by a single intraperitoneal injection of STZ (65 mg/kg body weight) and nicotinamide (110 mg/kg body weight, 15 min before STZ injection). Diabetic rats orally received either distilled water (as vehicle) or 200 mg/kg body weight of garlic bulb, ginger rhizome or turmeric rhizome powder suspension separately or mixed together (GGT mixture) for twenty-eight consecutive days. The results showed that these spices and their mixture significantly alleviated (80-97 %, P < 0·05-0·001) signs of the metabolic syndrome (hyperglycaemia and dyslipidaemia), the elevation in atherogenic indices and cellular toxicity in STZ-nicotinamide diabetic rats by increasing the production of insulin (26-37 %), enhancing the antioxidant defence system (31-52 %, especially GSH) and decreasing lipid peroxidation (60-97 %). The greatest modulation was seen in diabetic rats that received garlic and the GGT mixture (10-23 % more than that in the ginger and turmeric groups). In conclusion, garlic or the mix including garlic appears to have an impact on each of the measures more effectively than ginger and turmeric and may have a role in alleviating the risks of the metabolic syndrome and cardiovascular complications.

Antidyslipidaemic activity of Glycyrrhiza glabra in high fructose diet induced dsyslipidaemic Syrian golden hamsters

The root of Glycyrrhiza glabra is a traditional medicine used mainly for the treatment of peptic ulcer, hepatitis C, pulmonary and skin diseases, although clinical and experimental studies suggest that it has several other useful pharmacological properties such as antiinflammatory, antiviral, antimicrobial, antioxidative, anticancer activities, immunomodulatory, hepatoprotective and cardioprotective effects. Glycyrrhizinic acid, a major component of licorice, has antiulcer effect by raising the local concentration of prostaglandins that promote mucous secretion and cell proliferation in the stomach. Glycyrrhizin shows hepatoprotective effect by preventing changes in cell membrane permeability, inhibiting phospholipase A(2) (PLA(2)) and increasing survival rate of hepatocytes. Glabridin has effect in melanogenesis and inflammation by inhibiting the tyrosinase activity of melanocytes. α-glycyhrritinic acid exhibits anti-inflammatory activity by inhibiting glucocorticoid metabolism. In present study ethanolic (95%) extract of root of Glycyrrhiza glabra and its fractions were investigated for its antidyslipidaemic activity on HFD induced dyslipidaemic hamsters. Ethanolic extract and its ethyl acetate soluble, water soluble and hexane soluble fractions decreased serum level of total cholesterol by 25.9, 38.0, 39.0 and 26.3%, respectively. On the other hand ethanolic extract, ethyl acetate soluble, water soluble and hexane soluble fraction increased the serum HDL-cholesterol level by 14.8, 34.3, 27.3 and 17.2%, respectively. Ethanolic extract, ethyl acetate fraction, aqueous fraction and hexane fraction decreased triglyceride level by 31.3, 37.2, 41.2 and 28.9%, respectively. The reduction in LDL-cholesterol level by ethanolic extract, ethyl acetate soluble fraction and water soluble fraction were 43.9, 31.0, 33.4 and 24.6%, respectively.

Lipid-lowering properties of 6-benzoyl-2(3H)-benzothiazolone and structurally related compounds

Fifteen compounds derived from the 2(3H)-benzothiazolone template with an acyl side-chain in position-6 were evaluated for their lipid-lowering action in mice. Among these compounds, 6-benzoyl-2(3H)-benzothiazolone was found to be the most potent one both in mice models receiving a hypercholesterolemic diet (for 15 days) or a standard diet (for 21 days). 6-Benzoyl-2(3H)-benzothiazolone compares favorably with fenofibrate, the standard drug, both in terms of HDL-C/Chol (High Density Lipoprotein-Cholesterol/Total Cholesterol) ratio and absence of liver hepatomegaly.

Structure-based drug design of a novel family of chalcones as PPARalpha agonists: virtual screening, synthesis, and biological activities in vitro

AIM

To design and synthesize a novel class of peroxisome proliferator-activated receptors (PPAR)alpha agonists, which is obtained by the combination of the classical fibrate "head group", a linker with appropriate length and a chalcone.

METHODS

Thirty seven compounds were designed and identified employing the virtual screening approach. Six compounds were then selected for synthesis and bioassay according to the virtual screening results, structural similarity, and synthetic complexity.

RESULTS

Six new compounds (4b and 4d-h) were synthesized and bioassayed. All were found to be potent PPARalpha agonists, compound 4 h being the most prominent with a 50% effective concentration value of 0.06 micromol/L.

CONCLUSION

This study provides a promising novel family of chalcones with a potential hypolipidemic effect.

Synthesis and identification of [1,2,4]thiadiazole derivatives as a new series of potent and orally active dual agonists of peroxisome proliferator-activated receptors alpha and delta

Cardiovascular disease is the most common cause of morbidity and mortality in developed nations. To effectively target dyslipidemia to reduce the risk of cardiovascular disease, it may be beneficial to activate the peroxisome proliferator-activated receptors (PPARs) PPARalpha and PPARdelta simultaneously through a single molecule. Replacement of the methylthiazole of 5 (the PPARdelta selective agonist) with [1,2,4]thiadiazole gave compound 13, which unexpectedly displayed submicromolar potency as a partial agonist at PPARalpha in addition to the high potency at PPARdelta. Optimization of 13 led to the identification of 24 as a potent and selective PPARalpha/delta dual agonist. Compound 24 and its close analogs represent a new series of PPARalpha/delta dual agonists. The high potency, significant gene induction, excellent PK profiles, and good in vivo efficacies in three animal models may render compound 24 as a valuable pharmacological tool in elucidating the complex roles of PPARalpha/delta dual agonists and as a potential treatment of the metabolic syndrome.

Design, synthesis, and structure–activity relationship of carbamate-tethered aryl propanoic acids as novel PPARα/γ dual agonists

We have developed a new class of PPARalpha/gamma dual agonists, which show excellent agonistic activity in PPARalpha/gamma transactivation assay. In particular, (R)-9d was identified as a potent PPARalpha/gamma dual agonist with EC(50)s of 0.377 microM in PPARalpha and 0.136 microM in PPARgamma, respectively. Interestingly, the structure-activity relationship revealed that the stereochemistry of the identified PPARalpha/gamma dual agonists significantly affects their agonistic activities in PPARalpha than in PPARgamma.

Evaluation of efficacy and safety of fixed dose lovastatin and niacin(ER) combination in asian Indian dyslipidemic patients: a multicentric study

Asian Indian dyslipidemia is characterized by: borderline high low-density lipoprotein (LDL) cholesterol and apolipoprotein (apo) B; high triglycerides, low high-density lipoprotein (HDL) cholesterol and apoA1; and high lipoprotein(a) (lp[a]). We performed a controlled multicentric trial in India to evaluate the efficacy and safety of a fixed dose combination of lovastatin and niacin extended release (niacin^ER) formulation in patients with moderate to severe dyslipidemia. Consecutive subjects that satisfied the selection criteria, agreed to an informed consent, and with no baseline presence of liver/renal disease or heart failure were enrolled in the study. After a 4-week run-in period there were 142 patients with LDL levels ≥130 mg/dL. Eleven patients were excluded because of uncontrolled hyperglycemia and 131 patients were recruited. After baseline evaluation of clinical and biochemical parameters all subjects were administered lovastatin (20 mg) and niacin^ER (500 mg) combination once daily. Dose escalation was done on basis of lipid parameters at 8 weeks and in 11 patients increased to lovastatin (20 mg) and niacin^ER (1000 mg). An intention-to-treat analysis was performed and data was analyzed using nonparametric Wilcoxon signed rank test. Thirteen patients (10%) were lost to follow-up and 4 (3%) withdrew because of dermatological adverse effects: flushing, pruritus, and rash. The mean values of various lipid parameters (mg/dL) at baseline, and at weeks 4, 12, and 24 respectively were: total cholesterol 233.9 ± 27, 206.3 ± 27, 189.8 ± 31, and 174.9 ± 27 mg/dL; LDL cholesterol 153.4 ± 22, 127.3 ± 21, 109.2 ± 27, and 95.1 ± 23 mg/dL; triglycerides 171.1 ± 72, 159.5 ± 75, 149.2 ± 45, and 135.2 ± 40 mg/dL; HDL cholesterol 45.6 ± 7, 48.9 ± 7, 51.6 ± 9, and 53.9 ± 10 mg/dL; lp(a) 48.5 ± 26, 40.1 ± 21, 35.4 ± 21, and 26.9 ± 19 mg/dL; and apoA1/apoB ratio 0.96 ± 0.7, 1.04 ± 0.4, 1.17 ± 0.5, and 1.45 ± 0.5 (p < 0.01). The percentage of decline in various lipids at 4, 12, and 24 weeks was: total cholesterol 11.8%, 18.8%, and 25.2%; LDL cholesterol 17.0%, 28.8%, and 38.0%; triglyceride 6.8%, 12.8%, and 21.0%; lp(a) 17.5%, 26.9%, and 44.5% respectively (p < 0.01). HDL cholesterol and apoA1/apoB increased by 7.2%, 13.1%, and 18.2%; and 7.9%, 21.9%, and 51.6% respectively (p < 0.01). Target LDL levels (<100 mg/dL in subjects with manifest coronary heart disease or diabetes; <130 mg/dL in subjects with >2 risk factors) were achieved in 92 (80.7%) patients. No significant changes were observed in systolic or diastolic blood pressure, blood creatinine, transaminases, or creatine kinase. A fixed dose combination of lovastatin and niacin^ER significantly improved cholesterol lipoprotein lipids as well as lp(a) and apoA1/apoB levels in Asian Indian dyslipidemic patients. Satisfactory safety and tolerability profile in this population was also demonstrated.

Correction of patient results for Beckman Coulter LX-20 assays affected by interference due to hemoglobin, bilirubin or lipids: a practical approach

The influence of interference by hemolysis, icterus and lipemia on the results of routine chemistries may lead to wrong interpretations. On Synchron LX-20 instruments (Beckman Coulter) serum or plasma indices can be used as reliable semi-quantitative measures of the magnitude of such interference. In an article recently published in this journal, we presented the results of a multicenter study carried out in Dutch hospitals in which we determined cutoff indices for analytes above which analytically significant interference exists. Clinically significant interference cutoff indices were also derived for these analytes. In this article, we describe the handling of patient samples with clinically significant interference by hemolysis, icterus or lipemia. We investigated several possible approaches for correction of the result: dilution of the interference; mathematical correction in the case of hemolysis; treatment with ferrocyanide to destroy bilirubin; and removal of lipids in lipemic patient samples. We concluded, that mathematical correction of potassium or lactate dehydrogenase results in hemolytic samples can only be carried out if intravascular hemolysis is ruled out. Hemoglobin quantification in serial patient samples, combined with measurement of haptoglobin, represents a useful tool to rule out in vivo hemolysis. We derived an algorithm for this situation. We do not simply recommend mathematical correction, unless it is clinically acceptable. We present formulas for potassium and lactate dehydrogenase: corrected potassium=measured potassium-(hemolytic index increment x 0.14); corrected lactate dehydrogenase=measured lactate dehydrogenase-(hemolytic index increment x 75). The dilution studies indicated that dilution is only applicable for bilirubin, C-reactive protein and iron. The results of treatment with ferrocyanide were poor, and we do not recommend this method. Removal of lipids using high-speed centrifugation or LipoClear (StatSpin Inc.), a non-toxic and non-ionic polymer, is a very effective approach, although C-reactive protein, creatine kinase-MB (CK-MB) and cholesterol cannot be removed using LipoClear. For all interferants (hemoglobin, bilirubin, lipids), relatively simple algorithms are derived that can easily be implemented in the clinical laboratory.

Bioanalysis and pharmacokinetics of chitosan ester in rabbit serum by HPLC with postcolumn fluorescence derivatization

Interest in antiatherosclerotic activity of chitosan ester (PS916) with a new form of sulfate amino polysaccharide derived from marine chitin has necessitated the development of a sensitive and specific method to study its pharmacokinetics. A sensitive and reproducible high-performance liquid chromatography (HPLC) with postcolumn fluorescence derivatization method was developed and validated for the determination of PS916 in rabbit serum. Chromatography was carried out using a C8 reversed-phase column with an isocratic mobile phase consisting of methanol-water (20:80, v/v) at a flow rate of 0.2 ml/min. The derivatization procedure involved postcolumn reaction with guanidine hydrochloride in an alkaline medium at 110 degrees C. The fluorometric detector was operated at 250 nm (excitation) and 435 nm (emission). The assay was linear over the concentration range of 5-100 microg/ml. The lower limit of detection (LLOD) was found to be 1.0 microg/ml. The proposed method was successfully applied for a pharmacokinetic study of PS916 in rabbits.

Therapeutic targets: progress of their exploration and investigation of their characteristics

Modern drug discovery is primarily based on the search and subsequent testing of drug candidates acting on a preselected therapeutic target. Progress in genomics, protein structure, proteomics, and disease mechanisms has led to a growing interest in and effort for finding new targets and more effective exploration of existing targets. The number of reported targets of marketed and investigational drugs has significantly increased in the past 8 years. There are 1535 targets collected in the therapeutic target database compared with approximately 500 targets reported in a 1996 review. Knowledge of these targets is helpful for molecular dissection of the mechanism of action of drugs and for predicting features that guide new drug design and the search for new targets. This article summarizes the progress of target exploration and investigates the characteristics of the currently explored targets to analyze their sequence, structure, family representation, pathway association, tissue distribution, and genome location features for finding clues useful for searching for new targets. Possible "rules" to guide the search for druggable proteins and the feasibility of using a statistical learning method for predicting druggable proteins directly from their sequences are discussed.

Cost effectiveness of adding ezetimibe to atorvastatin therapy in patients not at cholesterol treatment goal in Canada

INTRODUCTION

This analysis compared the cost effectiveness of adding ezetimibe to atorvastatin therapy versus atorvastatin titration or adding cholestyramine (a resin) for patients at high risk of a coronary artery disease (CAD) event who did not reach target cholesterol levels on their current atorvastatin dosage. The primary analysis focused on 65-year-old patients with low-density lipoprotein cholesterol (LDL-C) levels of 3.1 or 3.6 mmol/L with a treatment goal of <2.5 mmol/L, classified as very high risk according to the 2000 Canadian Guidelines for Management and Treatment of Hyperlipidaemia.

METHODS

A previously developed Markov model was utilised to capture the cost and clinical consequences of lipid-lowering therapy in primary and secondary prevention of CAD. Comparisons between treatment strategies were made using ICERs (cost per QALY) from a Canadian Ministry of Health perspective. The effects of lipid-lowering therapies were based on clinical trial data. The risks of CAD events were estimated using Framingham Heart Study risk equations. Treatment costs and the costs of acute and long-term care for CAD events were included in the analysis. Costs (Canadian dollar, 2002 values) and outcomes were discounted at 5% per annum.

RESULTS

Ezetimibe added to atorvastatin therapy compared with treatment with the most common fixed atorvastatin daily dosage (10 mg) or with common atorvastatin titration strategies (up to 20 mg daily; up to 40 mg daily) resulted in cost per QALY estimates ranging from 25,344 to 44,332 Canadian dollars. The addition of ezetimibe to atorvastatin therapy was less costly and more effective than the addition of cholestyramine (dominant).

CONCLUSION

Our analysis suggests that adding ezetimibe to atorvastatin for patients not achieving treatment goals with their current atorvastatin dose produces greater clinical benefits than treatment with a fixed-dose atorvastatin or atorvastatin titration at an increased overall cost. The cost-effectiveness ratios provide strong evidence for the adoption of ezetimibe within the Canadian healthcare system.

Determination of the absolute configuration and solution conformation of a novel disubstituted pyrrolidine acid A by vibrational circular dichroism

Compound A, a novel disubstituted pyrrolidine acid, is a member of a new class of agents that are potentially useful for the treatment of diabetes and dyslipidemia. The absolute configuration of this compound was determined by using vibrational circular dichroism (VCD). The results are in agreement with the assignments based on both X-ray analysis and the stereo-selective chemical synthesis. During VCD analysis, the solution conformation for a portion of compound A in CDCl(3) was also established. The compound is found to associate as an H-bonded carboxylic acid "dimer" in CDCl(3) solution, and VCD calculations on a model dimer fragment were required to establish the absolute configuration.

Novel 2,3-Dihydrobenzofuran-2-carboxylic Acids: Highly Potent and Subtype-Selective PPARα Agonists with Potent Hypolipidemic Activity

The design and synthesis of a novel class of 2,3-dihydrobenzofuran-2-carboxylic acids as highly potent and subtype-selective PPARalpha agonists are reported. Systematic study of structure-activity relationships has identified several key structural elements within this class for maintaining the potency and subtype selectivity. Select compounds were evaluated in animal models of dyslipidemia using Syrian hamsters and male Beagle dogs, and all these compounds displayed excellent cholesterol- and triglyceride-lowering activity at dose levels that were much lower than the marketed weak PPARalpha agonist fenofibrate.

Effect of ethanolic extract of Zingiber officinale on dyslipidaemia in diabetic rats

The lipid lowering and antioxidant potential of ethanolic extract of Zingiber officinale Roscoe (family, Zingiberaceae) was evaluated in streptozotocin (STZ)-induced diabetes in rats. Ethanolic extract of Zingiber officinale (200 mg/kg) fed orally for 20 days produced, significant antihyperglycaemic effect (P < 0.01) in diabetic rats. Further, the extract treatment also lowered serum total cholesterol, triglycerides and increased the HDL-cholesterol levels when compared with pathogenic diabetic rats (P < 0.01). STZ-treatment also induced a statistically significant increase in liver and pancreas lipid peroxide levels (P < 0.01) as compared to normal healthy control rats. Zingiber officinale extract treatment lowered the liver and pancreas thiobarbituric acid reactive substances (TBARS) values (P < 0.01) as compared to pathogenic diabetic rats. The results of test drug were comparable to gliclazide (25 mg/kg, orally), a standard antihyperglycaemic agent. The results indicate that ethanolic extract of Zingiber officinale Roscoe can protect the tissues from lipid peroxidation. The extract also exhibit significant lipid lowering activity in diabetic rats. The present study is the first pilot study to assess the potential of Zingiber officinale in diabetic dyslipidaemia.

Apolipoprotein B and apolipoprotein A-I: risk indicators of coronary heart disease and targets for lipid-modifying therapy

Although LDL cholesterol (LDL-C) is associated with an increased risk of coronary heart disease, other lipoproteins and their constituents, apolipoproteins, may play an important role in atherosclerosis. Elevated levels of apolipoprotein (apo) B, a constituent of atherogenic lipoproteins, and reduced levels of apo A-I, a component of anti-atherogenic HDL, are associated with increased cardiac events. Apo B, apo A-I and the apo B/apo A-I ratio have been reported as better predictors of cardiovascular events than LDL-C and they even retain their predictive power in patients receiving lipid-modifying therapy. Measurement of these apolipoproteins could improve cardiovascular risk prediction.

Design and Synthesis of a Potent and Selective Triazolone-Based Peroxisome Proliferator-Activated Receptor α Agonist

A new series of hPPARalpha agonists containing a 2,4-dihydro-3H-1,2,4-triazol-3-one (triazolone) core is described leading to the discovery of 5 (LY518674), a highly potent and selective PPARalpha agonist.

What’s New in Lipid Management?

Statins are the principal agents for managing hyperlipidemia because of their ability to reduce low-density lipoprotein cholesterol (LDL) and triglyceride levels, increase high-density lipoprotein cholesterol (HDL) levels slightly, and decrease clinical events. Nevertheless, not all patients can tolerate the statins or achieve their treatment goals with these drugs. In addition, available statins have only modest effects on HDL, and clinical events still occur despite the best current lipid-lowering agents. Thus, new lipid-lowering agents are required to improve clinical outcomes. These recently or soon to be released agents are stanol esters, which can be incorporated into spreads and other foods and reduce LDL levels up to 15%; colesevelam, a new bile acid sequestrant with a higher potency, fewer adverse effects, and less drug interactions than those of older agents in this class; rosuvastatin, a new statin that reduces LDL levels and increases HDL levels at least more effectively than atorvastatin; and a new class of agents that inhibit cholesterol absorption and are likely to be used in combination with statins. Low-density lipoprotein cholesterol apheresis is another, nonpharmacologic option for patients with severe hyperlipidemia despite maximal medical therapy.

Update on the National Cholesterol Education Program Adult Treatment Panel III Guidelines: Getting to Goal

Considerable data on the pathophysiology, epidemiology, and treatment of dyslipidemia-induced coronary heart disease (CHD) have accumulated in recent years. These data have been assessed and incorporated into the guidelines of the National Cholesterol Education Program Expert Panel on the Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel [ATP] III). A major focus of the new guidelines is the assessment of the near-term (i.e., 10-yr) risk of experiencing a CHD event and matching the intensity of treatment to this risk. Patients with diabetes and those with a greater than 20% 10-year risk of experiencing a CHD event have been elevated to the risk level of CHD equivalent. The ATP III guidelines also modify several lipid and lipoprotein classifications. A low-density lipoprotein cholesterol (LDL) level below 100 mg/dl is now considered optimum for all individuals. In addition, high-density lipoprotein cholesterol (HDL) and triglyceride cutoff points have been modified to reflect more accurately the risk associated with abnormalities in these lipoproteins. As with the previous guidelines, the primary target of therapy remains LDL. Therapeutic lifestyle changes consisting of diet, weight reduction, and increased physical activity should be included in all treatment regimens. Based on their potent LDL-lowering properties and their proven ability to decrease mortality in a variety of patient populations, statins are generally the first choice for pharmacologic therapy. A secondary target of therapy includes non-HDL goals for patients with high triglyceride levels and the metabolic syndrome, which is characterized by abdominal obesity, elevated triglyceride levels, low HDL levels, and insulin resistance. Management of these secondary targets includes weight reduction and increased physical activity, and treatment of the lipid and nonlipid risk factors. Overall, ATP III represents an aggressive approach to treating dyslipidemia, greatly extending the number of individuals who qualify for treatment.

Lipoprotein(a): an emerging cardiovascular risk factor

Lipoprotein(a) is a cholesterol-enriched lipoprotein, consisting of a covalent linkage joining the unique and highly polymorphic apolipoprotein(a) to apolipoprotein B100, the main protein moiety of low-density lipoproteins. Although the concentration of lipoprotein(a) in humans is mostly genetically determined, acquired disorders might influence synthesis and catabolism of the particle. Raised concentration of lipoprotein(a) has been acknowledged as a leading inherited risk factor for both premature and advanced atherosclerosis at different vascular sites. The strong structural homologies with plasminogen and low-density lipoproteins suggest that lipoprotein(a) might represent the ideal bridge between the fields of atherosclerosis and thrombosis in the pathogenesis of vascular occlusive disorders. Unfortunately, the exact mechanisms by which lipoprotein(a) promotes, accelerates, and complicates atherosclerosis are only partially understood. In some clinical settings, such as in patients at exceptionally low risk for cardiovascular disease, the potential regenerative and antineoplastic properties of lipoprotein(a) might paradoxically counterbalance its athero-thrombogenicity, as attested by the compatibility between raised plasma lipoprotein(a) levels and longevity.

Peroxisome proliferator-activated receptor agonists, hyperlipidaemia, and atherosclerosis

Dyslipidaemia is a major risk factor in the development of atherosclerosis, and lipid lowering is achieved clinically using fibrate drugs and statins. Fibrate drugs are ligands for the fatty acid receptor peroxisome proliferator-activated receptor (PPAR)alpha, and the lipid-lowering effects of this class of drugs are mediated by the control of lipid metabolism, as directed by PPARalpha. PPARalpha ligands also mediate potentially protective changes in the expression of several proteins that are not involved in lipid metabolism, but are implicated in the pathogenesis of heart disease. Clinical studies with bezafibrate and gemfibrozil support the hypothesis that these drugs may have a significant protective effect against cardiovascular disease. The thiazolidinedione group of insulin-sensitising drugs are PPARgamma ligands, and these have beneficial effects on serum lipids in diabetic patients and have also been shown to inhibit the progression of atherosclerosis in animal models. However, their efficacy in the prevention of cardiovascular-associated mortality has yet to be determined. Recent studies have found that PPARdelta is also a regulator of serum lipids. However, there are currently no drugs in clinical use that selectively activate this receptor. It is clear that all three forms of PPARs have mechanistically different modes of lipid lowering and that drugs currently available have not been optimised on the basis of PPAR biology. A new generation of rationally designed PPAR ligands may provide substantially improved drugs for the prevention of cardiovascular disease.

Laser capture microdissection analysis of gene expression in macrophages from atherosclerotic lesions of apolipoprotein E-deficient mice

Macrophage foam cells are integral in the development of atherosclerotic lesions. Gene expression analysis of lesional macrophage foam cells is complicated by the cellular heterogeneity of atherosclerotic plaque and the presence of lesions of various degrees of severity. To overcome these limitations, we tested the ability of laser capture microdissection (LCM) and real-time quantitative reverse transcription PCR to selectively analyze RNA from lesional macrophages of apolipoprotein E (apoE)-deficient mice. Proximal aortic tissue sections were immunostained for macrophagespecific CD68/macrosialin by a rapid (approximately 15-min) protocol. Alternating sections from each animal were used to isolate RNA either from entire sections (analogous to isolation from whole tissue) or by LCM selection of CD68-positive cells. We measured the mRNA levels of CD68, a macrophage-specific marker, alpha-actin, a smooth muscle cell marker, and cyclophilin A, a control gene. Compared with whole sections, CD68 mRNA levels were greatly enriched (33.6-fold) in the laser-captured lesional macrophages. In contrast to whole sections, LCM-derived RNA had undetectable levels of alpha-actin. To illustrate the ability of this method to measure changes in lesional macrophage gene expression, we injected 100 microg of lipopolysaccharide i.p. into apoE-deficient mice and detected in laser-captured lesional macrophages increased mRNA expression for vascular cell adhesion molecule-1, intercellular cell adhesion molecule-1, and monocyte chemoattractant protein-1 (11.9-, 32.5-, and 31.0-fold, respectively). By selectively enriching foam cell RNA, LCM provides a powerful approach to study the in situ expression and regulation of atherosclerosis-related genes. This approach will allow the study of macrophage gene expression under various conditions of plaque formation, regression, and response to genetic and environmental perturbations.

Beyond LDL-C--the importance of raising HDL-C

Epidemiological studies have established that low levels of high-density lipoprotein cholesterol (HDL-C) are associated with an increased risk of coronary heart disease (CHD). Recent studies have demonstrated that low HDL-C levels, and high triglycerides and total cholesterol levels are independent predictors of CHD, and that the combination of these lipid abnormalities increases the risk of coronary events. In lipid-modifying intervention studies, agents that raise HDL-C levels have been shown to reduce the incidence of major coronary events. The VA-HIT study consisted of patients with low-density lipoprotein cholesterol (LDL-C) levels similar to those recommended by several guidelines but with low levels of HDL-C. This trial demonstrated that raising HDL-C levels with gemfibrozil reduced the risk of CHD-related events. While the mechanisms by which HDL-C exerts its anti-atherogenic effects have yet to be fully elucidated, its role in the reverse transport of cholesterol and the beneficial effects on endothelial function are plausible explanations for these actions. Although LDL-C reduction is the primary goal in the treatment of dyslipidaemia, current guidelines recognise low HDL-C levels as a major risk factor for CHD. Indeed, the NCEP ATP III guidelines suggest that the treatment of isolated low HDL-C levels in CHD patients or individuals with CHD risk equivalents should be considered. The differing abilities of statins to raise HDL-C levels may be an important factor when making treatment decisions. New lipid-modifying drugs with beneficial effects on both HDL-C and LDL-C levels would be desirable additions to the currently available therapeutic options.

SCAP ligands are potent new lipid-lowering drugs

Upregulation of low-density lipoprotein receptor (LDLr) is a key mechanism to control elevated plasma LDL-cholesterol levels. Here we identify a new class of compounds that directly binds to the sterol regulatory element-binding protein (SREBP) cleavage-activating protein (SCAP). We show that a 14C-labeled, photo-activatable analog specifically labeled both SCAP and a truncated form of SCAP containing the sterol-sensing domain. When administered to hyperlipidemic hamsters, SCAP ligands reduced both LDL cholesterol and triglycerides levels by up to 80% with a three-fold increase in LDLr mRNA in the livers. Using human hepatoma cells, we show that these compounds act through the sterol-responsive element of the LDLr promoter and activate the SCAP/SREBP pathway, leading to increased LDLr expression and activity, even in presence of excess of sterols. These findings have led to the identification of a class of compounds that represent a promising new class of hypolipidemic drugs.

A comparison of clinical outcome studies among cholesterol-lowering agents

OBJECTIVE

To review and compare clinical trials of cholesterol-lowering agents that evaluated clinical end points as the primary outcome measure; specifically, to determine whether all agents that decrease cholesterol impact clinical outcomes similarly.

DATA SOURCES

Primary articles were identified through a MEDLINE search (1966-February 2001) and through secondary sources.

STUDY SELECTION AND DATA EXTRACTION

All of the articles identified from the data sources were evaluated. Articles that included clinical end points as the primary outcome measure were included in this review.

DATA SYNTHESIS

Clinical trials were assessed according to study population (primary vs. secondary prevention of coronary artery disease), baseline and follow-up lipid profiles, and clinical outcome data. Both cardiac and noncardiac morbidity and mortality were evaluated. The differences in study populations, study methods, and changes in lipid values were compared and contrasted between trials to evaluate their effect on outcomes.

CONCLUSIONS

Niacin and bile acid sequestrants should be considered as add-on therapy when therapeutic goals cannot be attained with a hydroxymethyl glutaryl-coenzyme A reductase inhibitor (stain). Estrogen therapy cannot be recommended solely for cardioprotection. Fibrates are most effective in patients with high baseline triglycerides, low baseline high-density lipoprotein cholesterol, and low to average low-density lipoprotein cholesterol (LDL). Statins are considered first line for the treatment of elevated LDL in both the primary and secondary prevention of coronary heart disease. They are well tolerated, have the strongest data to support their use, and have been shown to decrease total mortality.

[Implication and mode of action of infectious agents in the formation of atheromatous plaques. Infection and atherosclerosis]

Different kinds of infectious agents seem to be implied in the atherosclerotic process. Indeed, some bacteria and viruses have been identified in atherosclerotic lesions: Chlamydia pneumoniae, Helicobacter pylori, Streptococcus sanguis, Porphyromonas gingivalis, herpes simplex viruses type 1 and 2, coxsakievirus B and hepatitis virus A. By their ability to induce antigenic and functional changes in the cells of the vascular wall (endothelial cells, smooth muscle cells, monocytes/macrophages, and fibroblasts) and to stimulate immune response as well as oxidative stress, it is more and more tempting to speculate that infectious agents probably play key roles in the initiation and in the formation of atherosclerotic plaques in certain patients.