The effect of statin on the aortic gene expression profiling

Pathways linking aging and atheroprotection in Mif-deficient atherosclerotic mice

Atherosclerosis is a chronic inflammatory condition of our arteries and the main underlying pathology of myocardial infarction and stroke. The pathogenesis is age-dependent, but the links between disease progression, age, and atherogenic cytokines and chemokines are incompletely understood. Here, we studied the chemokine-like inflammatory cytokine macrophage migration inhibitory factor (MIF) in atherogenic Apoe^-/- mice across different stages of aging and cholesterol-rich high-fat diet (HFD). MIF promotes atherosclerosis by mediating leukocyte recruitment, lesional inflammation, and suppressing atheroprotective B cells. However, links between MIF and advanced atherosclerosis across aging have not been systematically explored. We compared effects of global Mif-gene deficiency in 30-, 42-, and 48-week-old Apoe^-/- mice on HFD for 24, 36, or 42 weeks, respectively, and in 52-week-old mice on a 6-week HFD. Mif-deficient mice exhibited reduced atherosclerotic lesions in the 30/24- and 42/36-week-old groups, but atheroprotection, which in the applied Apoe^-/- model was limited to lesions in the brachiocephalic artery and abdominal aorta, was not detected in the 48/42- and 52/6-week-old groups. This suggested that atheroprotection afforded by global Mif-gene deletion differs across aging stages and atherogenic diet duration. To characterize this phenotype and study the underlying mechanisms, we determined immune cells in the periphery and vascular lesions, obtained a multiplex cytokine/chemokine profile, and compared the transcriptome between the age-related phenotypes. We found that Mif deficiency promotes lesional macrophage and T-cell counts in younger but not aged mice, with subgroup analysis pointing toward a role for Trem2⁺ macrophages. The transcriptomic analysis identified pronounced MIF- and aging-dependent changes in pathways predominantly related to lipid synthesis and metabolism, lipid storage, and brown fat cell differentiation, as well as immunity, and atherosclerosis-relevant enriched genes such as Plin1, Ldlr, Cpne7, or Il34, hinting toward effects on lesional lipids, foamy macrophages, and immune cells. Moreover, Mif-deficient aged mice exhibited a distinct plasma cytokine/chemokine signature consistent with the notion that mediators known to drive inflamm'aging are either not downregulated or even upregulated in Mif-deficient aged mice compared with the corresponding younger ones. Lastly, Mif deficiency favored formation of lymphocyte-rich peri-adventitial leukocyte clusters. While the causative contributions of these mechanistic pillars and their interplay will be subject to future scrutiny, our study suggests that atheroprotection due to global Mif-gene deficiency in atherogenic Apoe^-/- mice is reduced upon advanced aging and identifies previously unrecognized cellular and molecular targets that could explain this phenotype shift. These observations enhance our understanding of inflamm'aging and MIF pathways in atherosclerosis and may have implications for translational MIF-directed strategies.

Association Study Between Polymorphic Loci in Cholesterol Metabolism Pathway and Gallstone in the Tibetan Population

Background: The incidence of gallstones in the Tibetan population is increasing rapidly. Previous studies indicated that genetic variation located in the cholesterol metabolism pathway may be associated with the incidence of gallstones.

Methods: By recruiting 132 Tibetan gallstone patients and 52 normal Tibetan controls, we performed next-generation sequencing for 508 genes in the cholesterol metabolism pathway. Additionally, by integrating the sequence data of 41 normal Tibetan subjects in the public database, we finally obtained 93 normal Tibetan controls. Single nucleotide polymorphisms (SNPs) calling were performed by using the GATK pipeline. The quality control criteria for SNPs were: missing rate <0.05; minor allele frequency (MAF) > 0.01; and p value >0.001 in the Hardy-Weinberg Equilibrium (HWE) test. To eliminate the influence of population heterogeneity, Principal Component Analysis (PCA) was carried out by using the smartpca software. Association analyses were performed by Plink software. Multiple tests were adjusted by the false discovery rate (FDR) method.

Results: A total of 2,401 SNPs were obtained by analyzing 508 genes, and 2,011 SNPs left after quality control. After adjusting the eigen vectors, we found that 10 SNPs (SNV05997, rs80145081, rs80005560, rs79074685, rs748546375, rs201880593, rs142559357, rs750769471, rs869789 and rs4072341) were significantly associated with gallstone. Subsequently, by comparing the case group with our control group and the public database control group separately, we further found that the SNP rs869789 was consistently significantly associated with gallstone (p = 9.04 × 10^–3 in cases vs. our controls and 5.73 × 10^–3 in cases vs. public controls, respectively).

Conclusion: By systematically analyzed SNPs in the cholesterol metabolism pathway, we identified one polymorphic locus rs869789 significantly associated with the pathogenesis of gallstone in the Tibetan population. This study will provide clue for further mechanism study of gallstone in the Tibetan population.

Diabetogenic effect of pravastatin is associated with insulin resistance and myotoxicity in hypercholesterolemic mice

Background

HMG-CoA reductase inhibitors (statins) are cholesterol-lowering drugs widely used to treat hypercholesterolemia and prevent cardiovascular disease. Statins are generally well tolerated, but adverse reactions may occur, particularly myopathy and new onset of diabetes. The exact mechanism of statin-induced myopathy and diabetes has not been fully elucidated. We have previously shown that treatment of hypercholesterolemic (LDLr^−/−) mice with pravastatin for 2 months decreased pancreatic islet insulin secretion and increased oxidative stress and cell death, but no glucose intolerance was observed. The purpose of the current work was to study long-term pravastatin effects on glucose homeostasis, insulin sensitivity, muscle protein turnover and cell viability.

Methods

LDLr^−/− mice were treated with pravastatin for 3, 6 and 10 months. Glucose tolerance, insulin resistance and glucose-stimulated insulin secretion were evaluated. The rates of protein synthesis and degradation were determined in gastrocnemius muscle after 10 months of treatment. Insulin signalling, oxidative stress and cell death were analysed in vitro using C2C12 myotubes.

Results

After 6 and 10 months of treatment, these mice became glucose intolerant, and after 10 months, they exhibited marked insulin resistance. Reduced islet glucose-stimulated insulin secretion was observed after the 3rd month of treatment. Mice treated for 10 months showed significantly decreased body weight and increased muscle protein degradation. In addition, muscle chymotrypsin-like proteasomal activity and lysosomal cathepsin were markedly elevated. C2C12 myotubes exposed to increasing concentrations of pravastatin presented dose-dependent impairment of insulin-induced Akt phosphorylation, increased apoptotic markers (Bax protein and cleaved caspase-3) and augmented superoxide anion production.

Conclusions

In addition to reduced insulin secretion, long-term pravastatin treatment induces insulin resistance and muscle wasting. These results suggest that the diabetogenic effect of statins is linked to the appearance of myotoxicity induced by oxidative stress, impaired insulin signalling, proteolysis and apoptosis.

Effects of simvastatin on the PXR signaling pathway and the liver histology in Mugilogobius abei

Simvastatin is one of the most commonly cholesterol-lowering prescribed drugs all over the world. With the increase of consumption of these pharmaceuticals and subsequent their discharge into the aquatic environment in recent years, they are present at detectable levels in most sewage effluents. Unfortunately, limited information is provided about their potential impacts on aquatic organisms, especially on the detoxification-related metabolism in fish. In the present study, one local native benthic fish (Mugilogobius abei) in southern China was employed as test species and exposed to SV (0.5 μg L^-1, 5 μg L^-1, 50 μg L^-1 and 500 μg L^-1) for 72 h. The transcriptional expression of nucleus transcriptional factor pregnane X receptor (PXR) and its downstream targeted genes including multixenobiotics resistance protein or permeability glycoprotein (P-gp), cytochrome 1A (CYP1A), cytochrome P450 3A (CYP3A), glutathione-S-transferase (GST) and the expression of associated microRNA such as miR-27, miR-34 and miR-148 in Mugilogobius abei were investigated. Result showed that the expressions of P-gp, CYP 1A, CYP 3A, GST and PXR were induced to some extend under simvastatin exposure for 72 h. A positive correlation was observed between PXR and CYP1A, CYP3A and P-gp. While for microRNA, a negative relationship was found between miR-34a and CYP3A, CYP1A. The expression of miR-148a was significantly induced under the exposure of SV (50 μg L^-1), which was positive related to the transcriptional expression of PXR. For enzyme activity, erythromycin N-demethylase (ERND) significantly increased at 24 h and the activity of catalase (CAT) and superoxide dismutase (SOD) exhibited different trends. CAT was slightly inhibited at 24 h exposure but SOD was significantly induced in high concentration. Glutathione-S-transferase (GST) activity was significant inhibited after 72 h exposure. The reductive small molecule glutathione (GSH) content showed obvious decrease, while the quantity of malondialdehyde (MDA) increased significantly in high concentrations of SV exposure. GSH and MDA showed a typical negative correlation to some degree. Moreover, simvastatin caused histological changes in the liver tissues of M. abei, especially the size of adipocyte significantly decreased. The present study indicated that environmentally relevant concentration SV may affect the PXR signaling pathway in M. abei and pose potential ecological risks to non-target organisms like fish.

Maternal Metabolism and Vascular Adaptation in Pregnancy: The PPAR Link

Current therapies for pregnancy-related hypertension and its complications remain inadequate, although an increasing role for maternal susceptibility is becoming evident. Systemic vascular dysfunction in response to imbalances in angiogenic, inflammatory, and constricting factors is implicated in the pathogenesis of gestational hypertension, and growing evidence now links these factors with maternal metabolism. In particular, the crucial role of peroxisome proliferator-activated receptors (PPARs) in maternal vascular adaptation provides further insights into how obesity and gestational diabetes may be linked to pregnancy-induced hypertension and preeclampsia. This is especially important given the rapidly growing prevalence of obesity during pregnancy, and highlights a new approach to treat pregnancy-related hypertension and its complications.

Statins as regulators of redox state in the vascular endothelium: beyond lipid lowering

SIGNIFICANCE

Endothelial dysfunction and the imbalance between nitric oxide (NO) and reactive oxygen species production in the vascular endothelium are important early steps in atherogenesis, a major socioeconomic health problem. Statins have well-established roles in primary and secondary prevention of cardiovascular disease (CVD), due to both their lipid-lowering capacity and their pleiotropic properties. It is therefore important to understand the mechanisms by which statins can modify endothelial function and affect atherogenesis.

RECENT ADVANCES

In the last decade, the concept of statin pleiotropy has been reinforced by a large number of cell culture, animal, and translational studies. Statins have been shown to suppress the activity of pro-oxidant enzymes (such as NADPH oxidase) and pro-inflammatory transcriptional pathways in the endothelium. At the same time, they enhance endothelial NO synthase expression and activity while they also improve its enzymatic coupling. This leads to increased NO bioavailability and improved endothelial function.

CRITICAL ISSUES

Despite significant recent advances, the exact mechanisms of statin pleitropy are still only partially understood. The vast majority of the published literature relies on animal studies, while the actual mechanistic studies in humans are limited.

FUTURE DIRECTIONS

The success of statins as endothelium redox-modifying agents with a direct impact on clinical outcome highlights the importance of the endothelium as a therapeutic target in CVD. Better understanding of the mechanisms that underlie endothelial dysfunction could lead to the design of novel therapeutic strategies that target the vascular endothelium for the prevention and treatment of CVD.

Pharmacogenomics in the development and characterization of atheroprotective drugs

Atherosclerosis is the main cause of cardiovascular disease (CVD) and can lead to stroke, myocardial infarction, and death. The clinically available atheroprotective drugs aim mainly at reducing the levels of circulating low-density lipoprotein (LDL), increasing high-density lipoprotein (HDL), and attenuating inflammation. However, the cardiovascular risk remains high, along with morbidity, mortality, and incidence of adverse drug events. Pharmacogenomics is increasingly contributing towards the characterization of existing atheroprotective drugs, the evaluation of novel ones, and the identification of promising, unexplored therapeutic targets, at the global molecular pathway level. This chapter presents highlights of pharmacogenomics investigations and discoveries that have contributed towards the elucidation of pharmacological atheroprotection, while opening the way to new therapeutic approaches.

Heart failure entails significant changes in human nucleocytoplasmic transport gene expression

BACKGROUND

Heart failure (HF) induces alterations in nucleocytoplasmic transport, which is essential to the cardiomyocyte biology. The objective of this study was to analyze the changes in gene expression in human HF, particularly focusing on nucleocytoplasmic transport-related genes.

METHODS AND RESULTS

29 RNA heart samples from dilated cardiomyopathy (DCM, n = 12) and ischemic cardiomyopathy (ICM, n = 12) patients undergoing heart transplantation and control donors (CNT, n = 5) were extracted to perform a microarray profiling using Affymetrix Human Gene® 1.0 ST arrays. We focused on the study of 5 nucleocytoplasmic transport-related genes, since this functional category has not previously been studied in HF. XPO1, GABPB2, and RANBP17 were upregulated, while KALRN was downregulated in both DCM and ICM, and XPO5 only in DCM. Validation of the results by RT-qPCR increasing the total heart samples up to 41 showed a high degree of consistency with microarray results. Moreover, we observed a strong relationship between the XPO1 mRNA and robust left ventricular function parameters in ICM: left ventricular end-systolic (r = 0.81, p<0.0001) and end-diastolic diameters (r = 0.80, p<0.0001), and ejection fraction (r = -0.57, p<0.05).

CONCLUSIONS

We show that the expression of nucleocytoplasmic transport-related genes is altered in HF. Furthermore, XPO1 mRNA level is closely related with robust left ventricular function parameters in ICM patients. These changes may help to distinguish DCM and ICM in HF at the level of the transcriptome and provide a base for novel therapeutic approaches.

Statins cause profound effects on gene expression in human cancer cells in vitro: the role of membrane microdomains

There is increasing evidence that statin treatment can be beneficial in certain cancer patients. To determine if these benefits are a direct result of the cholesterol-lowering effects of statins or a result of secondary, protein transcription effects, the impacts of pravastatin and a cholesterol sequestrating agent methyl-beta-cyclodextrin (MbetaCD) on mRNA expression in the breast cancer cell MDA-MB-231 and the lung carcinoma cell Calu-1 have been compared by microarray techniques. The effects of these agents on cholesterol-rich rafts and caveolae, which have significance in cancer signaling, have also been examined. Both treatments caused a general downregulation of not only signal transduction including cancer pathway proteins, but also apoptosis and chemokine pathways, with statins impacting 35 genes by twofold or greater in MDA-MB-231 and > 300 genes in Calu-1. These manifold dysregulations could also explain the various side effects reportedly caused by statins. MbetaCD produced far fewer statistical events than pravastatin in the breast cancer line but many more in the lung cell line. Pravastatin increased expression of CAV1 but caveolae density decreased and overall raft density was unaffected. MbetaCD also caused an increase in CAV1 expression and reduced the prevalence of both rafts and caveolae. It is proposed that sequestration of cholesterol from the membrane by MbetaCD is not equivalent to blockade of the cholesterol pathway and causes different effects on microdomain-mediated signal transduction dependant on the cell line. The profound effects of statins on mRNA expression can be explained by the failure of caveolin-1 to properly complex with cholesterol in an altered sterol environment, with caveolae acting as the main loci for signaling directed towards those transcription processes unaffected by MbetaCD. Targeted inhibition of the postmevalonate pathway could offer an opportunity to specifically reduce caveolae-based signaling in cancer cells. The observed impact of pravastatin on gene expression may explain the pleiotropic effects of statins when they are used as adjuvants in chemotherapy and suggests impact on gene expression as a possible cause of side effects from statin use.

The role of the blood transcriptome in innate inflammation and stroke

Cerebrovascular disease is a major cause of death and disability, with a poorer outcome in patients having select risk factors including diabetes and hypertension. Risk factors and the state of cerebral ischemia-reperfusion associated with cerebrovascular occlusion are known to cause inflammatory changes. These events and the inflammatory state are reflected by transcript changes in various components of the blood and can be specifically measured. By defining these changes, new insight into cerebrovascular disease and its therapeutics is being achieved.

RGS proteins: identifying new GAPs in the understanding of blood pressure regulation and cardiovascular function

Understanding the mechanisms that underlie BP (blood pressure) variation in humans and animal models may provide important clues for reducing the burden of uncontrolled hypertension in industrialized societies. High BP is often associated with increased signalling via G-protein-coupled receptors. Three members of the RGS (regulator of G-protein signalling) superfamily RGS2, RGS4 and RGS5 have been implicated in the attenuation of G-protein signalling pathways in vascular and cardiac myocytes, as well as cells of the kidney and autonomic nervous system. In the present review, we discuss the current state of knowledge regarding their differential expression and function in cardiovascular tissues, and the likelihood that one or more of these alleles are candidate hypertension genes. Together, findings from the studies described herein suggest that development of methods to modulate the expression and function of RGS proteins may be a possible strategy for the treatment and prevention of hypertension and cardiovascular disease.

Growth predictors and prognosis of small abdominal aortic aneurysms

OBJECTIVE

Evidence regarding the influence of cardiovascular risk factors, comorbidities, and patient characteristics on the growth of small abdominal aortic aneurysms (AAA) is limited. We assessed, in an observational cohort study, rupture rates, risks of mortality, and the effects of cardiovascular risk factors and patient demographics on growth rates of small AAAs.

METHODS

Between September 1996 and January 2005, 5057 patients with manifest arterial vascular disease or cardiovascular risk factors were included in the Second Manifestation of ARTerial disease (SMART) study. Measurements of the abdominal aortic diameter were performed in all patients. All patients with an initial AAA diameter between 30 and 55 mm were selected for this study. All AAA measurements during follow-up until August 2007 were collected. Multivariate regression analysis was performed to calculate the effects of demographic patient characteristics, initial AAA diameter, and cardiovascular risk factors on AAA growth.

RESULTS

Included were 230 patients, with a mean age of 66 years and 90% were male. Seven AAA ruptures (six fatal) occurred in 755 patient years of follow-up (rupture rate 0.9% per patient-year). In 147 patients, AAA measurements were performed for a period of more than 6 months. The median follow-up time was 3.3 years (mean 4.0, range 0.5 to 11.1 years, standard deviation (SD) 2.5). Mean AAA diameter was 38.8 mm (SD 6.8) and mean expansion rate 2.5 mm/y. Patients using lipid-lowering drugs had a 1.2 mm/y (95% confidence interval [CI] -2.34 to -0.060 mm/y) lower AAA growth rate compared to nonusers of these drugs. Initial AAA diameter was associated with a 0.09 mm/y (95% CI 0.01 to 0.18 mm/y) higher growth rate per millimetre increase of the diameter. No other factors, including blood lipid values, were independently associated with AAA growth.

CONCLUSIONS

Lipid-lowering drug treatment and initial AAA diameter appear to be independently associated with lower AAA growth rates. The risk of rupture of these small abdominal aortic aneurysms was low, which pleads for watchful waiting.

PPARdelta regulates multiple proinflammatory pathways to suppress atherosclerosis

Lipid homeostasis and inflammation are key determinants in atherogenesis, exemplified by the requirement of lipid-laden, foam cell macrophages for atherosclerotic lesion formation. Although the nuclear receptor PPARdelta has been implicated in both systemic lipid metabolism and macrophage inflammation, its role as a therapeutic target in vascular disease is unclear. We show here that orally active PPARdelta agonists significantly reduce atherosclerosis in apoE(-/-) mice. Metabolic and gene expression studies reveal that PPARdelta attenuates lesion progression through its HDL-raising effect and anti-inflammatory activity within the vessel wall, where it suppresses chemoattractant signaling by down-regulation of chemokines. Activation of PPARdelta also induces the expression of regulator of G protein signaling (RGS) genes, which are implicated in blocking the signal transduction of chemokine receptors. Consistent with this, PPARdelta ligands repress monocyte transmigration and macrophage inflammatory responses elicited by atherogenic cytokines. These results reveal that PPARdelta antagonizes multiple proinflammatory pathways and suggest PPARdelta-selective drugs as candidate therapeutics for atherosclerosis.