Correlation of Peroxisome Proliferator-Activated Receptor-gamma (PPAR-gamma) and Retinoid X Receptor-alpha (RXR-alpha) expression with clinical risk factors in patients with advanced carotid atherosclerosis

The Interplay of WNT and PPARγ Signaling in Vascular Calcification

Vascular calcification (VC), the ectopic deposition of calcium phosphate crystals in the vessel wall, is one of the primary contributors to cardiovascular death. The pathology of VC is determined by vascular topography, pre-existing diseases, and our genetic heritage. VC evolves from inflammation, mediated by macrophages, and from the osteochondrogenic transition of vascular smooth muscle cells (VSMC) in the atherosclerotic plaque. This pathologic transition partly resembles endochondral ossification, involving the chronologically ordered activation of the β-catenin-independent and -dependent Wingless and Int-1 (WNT) pathways and the termination of peroxisome proliferator-activated receptor γ (PPARγ) signal transduction. Several atherosclerotic plaque studies confirmed the differential activity of PPARγ and the WNT signaling pathways in VC. Notably, the actively regulated β-catenin-dependent and -independent WNT signals increase the osteochondrogenic transformation of VSMC through the up-regulation of the osteochondrogenic transcription factors SRY-box transcription factor 9 (SOX9) and runt-related transcription factor 2 (RUNX2). In addition, we have reported studies showing that WNT signaling pathways may be antagonized by PPARγ activation via the expression of different families of WNT inhibitors and through its direct interaction with β-catenin. In this review, we summarize the existing knowledge on WNT and PPARγ signaling and their interplay during the osteochondrogenic differentiation of VSMC in VC. Finally, we discuss knowledge gaps on this interplay and its possible clinical impact.

Opposite regulation of piRNAs, rRNAs and miRNAs in the blood after subarachnoid hemorrhage

Multiple classes of small RNAs (sRNAs) are expressed in the blood and are involved in the regulation of pivotal cellular processes. We aimed to elucidate the expression patterns and functional roles of sRNAs in the systemic response to intracranial aneurysm (IA) rupture. We used next-generation sequencing to analyze the expression of sRNAs in patients in the acute phase of IA rupture (first 72 h), in the chronic phase (3-15 months), and controls. The patterns of alterations in sRNA expression were analyzed in the context of clinically relevant information regarding the biological consequences of IA rupture. We identified 542 differentially expressed sRNAs (108 piRNAs, 99 rRNAs, 90 miRNAs, 43 scRNAs, 36 tRNAs, and 32 snoRNAs) among the studied groups with notable differences in upregulated and downregulated sRNAs between the groups and sRNAs categories. piRNAs and rRNAs showed a substantial decrease in RNA abundance that was sustained after IA rupture, whereas miRNAs were largely upregulated. Downregulated sRNA genes included piR-31080, piR-57947, 5S rRNA, LSU-rRNA, and SSU-rRNA s. Remarkable enrichment in the representation of transcription factor binding sites was revealed in genomic locations of the regulated sRNA. We found strong overrepresentation of glucocorticoid receptor, retinoid x receptor alpha, and estrogen receptor alpha binding sites at the locations of downregulated piRNAs, tRNAs, and rRNAs. This report, although preliminary and largely proof-of-concept, is the first to describe alterations in sRNAs abundance levels in response to IA rupture in humans. The obtained results indicate novel mechanisms that may constitute another level of control of the inflammatory response. KEY MESSAGES: A total of 542 sRNAs were differentially expressed after aneurysmal SAH comparing with controls piRNAs and rRNAs were upregulated and miRNAs were downregulated after IA rupture The regulated sRNA showed an enrichment in the representation of some transcription factor binding sites piRNAs, tRNAs, and rRNAs showed an overrepresentation for GR, RXRA, and ERALPHA binding sites.

Risk Factors for Recurrent Carotid-Artery Stenosis Following Stenting Treatment

BACKGROUND Carotid artery stenting (CAS) has been regarded as a reliable treatment approach for carotid artery stenosis. However, recurrent carotid artery stenosis after CAS affects long-term outcomes. In this study, we aimed to investigate the potential risk factors for carotid restenosis. MATERIAL AND METHODS We retrospectively analyzed the clinical data of patients diagnosed with carotid artery stenosis who underwent CAS implantation at our department from September 2012 to July 2015. Each included study patient was followed up with serial duplex ultrasound scanning. Kaplan-Meier estimates were used to evaluate freedom from restenosis and potential risk factors were analyzed. RESULTS There were 33 patients enrolled in our study. The mean age was 65.5±11.5 years. The technique was successfully achieved in all patients. No death or major stroke occurred after stenting. There were 2 events of minor stroke and one myocardial infarction within 30 days after stent implantation. All the patients were followed up for 3 years. Cumulative rates of freedom from recurrent stenosis at 1, 2, and 3 years were 87.4%, 74.6%, and 68.3% respectively. Cox multivariate regression analysis revealed that male sex, smoking and hyperlipidemia were independent risk factors associated with restenosis. CONCLUSIONS In this study, we identified that CAS was a reliable approach for carotid artery stenosis. Male sex, smoking, and hyperlipidemia were independent risk factors associated with restenosis. Thus, hyperlipidemia should be monitored and routine follow-up with ultrasonography are recommended especially for male patients with current or history of smoking.

Human Plasma Metabolomics Implicates Modified 9-cis-Retinoic Acid in the Phenotype of Left Main Artery Lesions in Acute ST-Segment Elevated Myocardial Infarction

The detection of left main coronary artery disease (LMCAD) is crucial before ST-segment elevated myocardial infarction (STEMI) or sudden cardiac death. The aim of this study was to identify characteristic metabolite modifications in the LMCAD phenotype, using the metabolomics technique. Metabolic profiles were generated based on ultra-performance liquid chromatography and mass spectrometry, combined with multivariate statistical analysis. Plasma samples were collected prospectively from a propensity-score matched cohort including 44 STEMI patients (22 consecutive LMCAD and 22 non-LMCAD), and 22 healthy controls. A comprehensive metabolomics data analysis was performed with Metaboanalyst 3.0 version. The retinol metabolism pathway was shown to have the strongest discriminative power for the LMCAD phenotype. According to biomarker analysis through receiver-operating characteristic curves, 9-cis-retinoic acid (9cRA) dominated the first page of biomarkers, with area under the curve (AUC) value 0.888. Next highest were a biomarker panel consisting of 9cRA, dehydrophytosphingosine, 1H-Indole-3-carboxaldehyde, and another seven variants of lysophosphatidylcholines, exhibiting the highest AUC (0.933). These novel data propose that the retinol metabolism pathway was the strongest differential pathway for the LMCAD phenotype. 9cRA was the most critical biomarker of LMCAD, and a ten-metabolite plasma biomarker panel, in which 9cRA remained the weightiest, may help develop a potent predictive model for LMCAD in clinic.

Natural products as modulators of the nuclear receptors and metabolic sensors LXR, FXR and RXR

Nuclear receptors (NRs) represent attractive targets for the treatment of metabolic syndrome-related diseases. In addition, natural products are an interesting pool of potential ligands since they have been refined under evolutionary pressure to interact with proteins or other biological targets. This review aims to briefly summarize current basic knowledge regarding the liver X (LXR) and farnesoid X receptors (FXR) that form permissive heterodimers with retinoid X receptors (RXR). Natural product-based ligands for these receptors are summarized and the potential of LXR, FXR and RXR as targets in precision medicine is discussed.

The endocannabinoid system in cardiovascular function: novel insights and clinical implications

RATIONALE

Cardiovascular disease is now recognized as the number one cause of death in the world, and the size of the population at risk continues to increase rapidly. The dysregulation of the endocannabinoid (eCB) system plays a central role in a wide variety of conditions including cardiovascular disorders. Cannabinoid receptors, their endogenous ligands, as well as enzymes conferring their synthesis and degradation, exhibit overlapping distributions in the cardiovascular system. Furthermore, the pharmacological manipulation of the eCB system has effects on blood pressure, cardiac contractility, and endothelial vasomotor control. Growing evidence from animal studies supports the significance of the eCB system in cardiovascular disorders.

OBJECTIVE

To summarize the literature surrounding the eCB system in cardiovascular function and disease and the new compounds that may potentially extend the range of available interventions.

RESULTS

Drugs targeting CB1R, CB2R, TRPV1 and PPARs are proven effective in animal models mimicking cardiovascular disorders such as hypertension, atherosclerosis and myocardial infarction. Despite the setback of two clinical trials that exhibited unexpected harmful side-effects, preclinical studies are accelerating the development of more selective drugs with promising results devoid of adverse effects.

CONCLUSION

Over the last years, increasing evidence from basic and clinical research supports the role of the eCB system in cardiovascular function. Whereas new discoveries are paving the way for the identification of novel drugs and therapeutic targets, the close cooperation of researchers, clinicians and pharmaceutical companies is needed to achieve successful outcomes.

Cerebral Vascular Disease and Neurovascular Injury in Ischemic Stroke

The consequences of cerebrovascular disease are among the leading health issues worldwide. Large and small cerebral vessel disease can trigger stroke and contribute to the vascular component of other forms of neurological dysfunction and degeneration. Both forms of vascular disease are driven by diverse risk factors, with hypertension as the leading contributor. Despite the importance of neurovascular disease and subsequent injury after ischemic events, fundamental knowledge in these areas lag behind our current understanding of neuroprotection and vascular biology in general. The goal of this review is to address select key structural and functional changes in the vasculature that promote hypoperfusion and ischemia, while also affecting the extent of injury and effectiveness of therapy. In addition, as damage to the blood-brain barrier is one of the major consequences of ischemia, we discuss cellular and molecular mechanisms underlying ischemia-induced changes in blood-brain barrier integrity and function, including alterations in endothelial cells and the contribution of pericytes, immune cells, and matrix metalloproteinases. Identification of cell types, pathways, and molecules that control vascular changes before and after ischemia may result in novel approaches to slow the progression of cerebrovascular disease and lessen both the frequency and impact of ischemic events.

Signaling events in pathogen-induced macrophage foam cell formation

Macrophage foam cell formation is a key event in atherosclerosis. Several triggers induce low-density lipoprotein (LDL) uptake by macrophages to create foam cells, including infections with Porphyromonas gingivalis and Chlamydia pneumoniae, two pathogens that have been linked to atherosclerosis. While gene regulation during foam cell formation has been examined, comparative investigations to identify shared and specific pathogen-elicited molecular events relevant to foam cell formation are not well documented. We infected mouse bone marrow-derived macrophages with P. gingivalis or C. pneumoniae in the presence of LDL to induce foam cell formation, and examined gene expression using an atherosclerosis pathway targeted plate array. We found over 30 genes were significantly induced in response to both pathogens, including PPAR family members that are broadly important in atherosclerosis and matrix remodeling genes that may play a role in plaque development and stability. Six genes mainly involved in lipid transport were significantly downregulated. The response overall was remarkably similar and few genes were regulated in a pathogen-specific manner. Despite very divergent lifestyles, P. gingivalis and C. pneumoniae activate similar gene expression profiles during foam cell formation that may ultimately serve as targets for modulating infection-elicited foam cell burden, and progression of atherosclerosis.

Current Advances in the Biochemical and Physiological Aspects of the Treatment of Type 2 Diabetes Mellitus with Thiazolidinediones

The present review summarizes the current advances in the biochemical and physiological aspects in the treatment of type 2 diabetes mellitus (DM2) with thiazolidinediones (TZDs). DM2 is a metabolic disorder characterized by hyperglycemia, triggering the abnormal activation of physiological pathways such as glucose autooxidation, polyol's pathway, formation of advance glycation end (AGE) products, and glycolysis, leading to the overproduction of reactive oxygen species (ROS) and proinflammatory cytokines, which are responsible for the micro- and macrovascular complications of the disease. The treatment of DM2 has been directed toward the reduction of hyperglycemia using different drugs such as insulin sensitizers, as the case of TZDs, which are able to lower blood glucose levels and circulating triglycerides by binding to the nuclear peroxisome proliferator-activated receptor gamma (PPARγ) as full agonists. When TZDs interact with PPARγ, the receptor regulates the transcription of different genes involved in glucose homeostasis, insulin resistance, and adipogenesis. However, TZDs exhibit some adverse effects such as fluid retention, weight gain, hepatotoxicity, plasma-volume expansion, hemodilution, edema, bone fractures, and congestive heart failure, which limits their use in DM2 patients.

Rhizoma Dioscoreae Nipponicae polysaccharides protect HUVECs from H2O2-induced injury by regulating PPARγ factor and the NADPH oxidase/ROS-NF-κB signal pathway

AIM

Polysaccharides were extracted from Rhizoma Dioscoreae Nipponicae to investigate whether Rhizoma Dioscoreae Nipponicae polysaccharides (RDNP) can act as an antioxidant and PPARγ agonist to protect HUVECs from H2O2-induced injury.

METHODS

HUVECs (human umbilical vein endothelial cells) were treated with RDNP in the presence/absence of H2O2. Kits and Fenton reaction were used to produce free radicals. Reagent kits of LDH, MDA, SOD, T-AOC and GSH-Px were used to evaluate the cell injuries and the antioxidant activity of RDNP. Intracellular reactive oxygen species (ROS) generation was detected by 2', 7'-dichlorofluorescein diacetate (DCFH-DA). Western blot was used to evaluate the protein expression of Nox4, p22phox, NF-κB/p65, phospho-NF-κB/p65, IκB as well as PPARγ, ICAM-1 and VCAM-1. Real time quantitative reverse transcriptive polymerase chain reaction (qRT-PCR) was used to confirm the expressions of Nox4, p22phox, ICAM-1 and VCAM-1 mRNA.

RESULTS

RDNP inhibited the production of superoxide anion radical, hydroxyl radical and the lipid peroxidation both in hepatic cells and red blood cells (RBC). It also reduced LDH and MDA levels and enhanced intracellular SOD, T-AOC as well as GSH-Px activities in H2O2-treated HUVECs. Furthermore, RDNP could inhibit ROS generation, Nox4, p22phox, NF-κB/p65, phospho-NF-κB/p65, ICAM-1 and VCAM-1 expression, and it could also inhibit IκB degradation and activate PPARγ expression in HUVECs.

CONCLUSIONS

RDNP could protect HUVECs from H2O2-induced injury through interfering PPARγ-NADPH oxidase/ROS-NF-κB pathway. This study will provide new pharmacological evidence that RDNP has positive significance for prevention and treatment of atherosclerosis (AS).

Systems pharmacology augments drug safety surveillance

Small molecule drugs are the foundation of modern medical practice yet their use is limited by the onset of unexpected and severe adverse events (AEs). Regulatory agencies rely on post-marketing surveillance to monitor safety once drugs are approved for clinical use. Despite advances in pharmacovigilance methods that address issues of confounding bias, clinical data of AEs are inherently noisy. Systems pharmacology– the integration of systems biology and chemical genomics – can illuminate drug mechanisms of action. We hypothesize that these data can improve drug safety surveillance by highlighting drugs with a mechanistic connection to the target phenotype (enriching true positives) and filtering those that do not (depleting false positives). We present an algorithm, the modular assembly of drug safety subnetworks (MADSS), to combine systems pharmacology and pharmacovigilance data and significantly improve drug safety monitoring for four clinically relevant adverse drug reactions.

Patients with chronic three-vessel disease in a 15-year follow-up study: genetic and non-genetic predictors of survival

Genetic and non-genetic predictors of 15-year survival in patients with chronic three-vessel disease (3VD) were investigated. Coronary angiography was performed on 810 subjects with symptoms of stable ischemic heart disease in 1998. The patients with 3VD were genotyped for 23 candidate polymorphisms covering the PPAR-RXR pathway, matrix metalloproteinase-2, renin-angiotensin-aldosterone system, endothelin-1, cytokine genes, MTHFR and APO E variants. Fifteen-year survival data were obtained from the national insurance registry. All data were available in the case of 150 patients with 3VD. Statistical analysis used stepwise Cox regression with dominant, recessive, or additive mode of genetic expression. Involved variables included age, sex, BMI, blood pressure, diabetes, ejection fraction, left main stenosis, previously diagnosed coronary stenosis, myocardial infarction in personal history, and coronary bypass along with polymorphisms pre-selected by log-rank tests. Out of the 23 polymorphisms, four were included in the model construction. SNP in the IL-6 gene rs1800795 (-174 G/C) has been found to be a significant predictor of survival. This SNP was in a linkage disequilibrium with rs1800797 (-597 G/A) in the same gene (D'=1.0), which was also found to constitute a significant predictor of survival when rs1800795 was not included in the model construction. Age, increased BMI, diabetes, low EF, and left main stenosis were also significant predictors in all models. Age, increased BMI, diabetes, low ejection fraction, left main stenosis, and genetic variation in the IL-6 promoter were established as significant independent risk factors for the survival of patients with three-vessel disease.

Oct-2 transcription factor binding activity and expression up-regulation in rat cerebral ischaemia is associated with a diminution of neuronal damage in vitro

Brain plasticity provides a mechanism to compensate for lesions produced as a result of stroke. The present study aims to identify new transcription factors (TFs) following focal cerebral ischaemia in rat as potential therapeutic targets. A transient focal cerebral ischaemia model was used for TF-binding activity and TF-TF interaction profile analysis. A permanent focal cerebral ischaemia model was used for the transcript gene analysis and for the protein study. The identification of TF variants, mRNA analysis, and protein study was performed using conventional polymerase chain reaction (PCR), qPCR, and Western blot and immunofluorescence, respectively. Rat cortical neurons were transfected with small interfering RNA against the TF in order to study its role. The TF-binding analysis revealed a differential binding activity of the octamer family in ischaemic brain in comparison with the control brain samples both in acute and late phases. In this study, we focused on Oct-2 TF. Five of the six putative Oct-2 transcript variants are expressed in both control and ischaemic rat brain, showing a significant increase in the late phase of ischaemia. Oct-2 protein showed neuronal localisation both in control and ischaemic rat brain cortical slices. Functional studies revealed that Oct-2 interacts with TFs involved in important brain processes (neuronal and vascular development) and basic cellular functions and that Oct-2 knockdown promotes neuronal injury. The present study shows that Oct-2 expression and binding activity increase in the late phase of cerebral ischaemia and finds Oct-2 to be involved in reducing ischaemic-mediated neuronal injury.

Retinoid X receptors in macrophage biology

Retinoid X receptors (RXRs) form a distinct and unique subclass within the nuclear receptor (NR) superfamily of ligand-dependent transcription factors. RXRs regulate a plethora of genetic programs, including cell differentiation, the immune response, and lipid and glucose metabolism. Recent advances reveal that RXRs are important regulators of macrophages, key players in inflammatory and metabolic disorders. This review outlines the versatility of RXR action in the control of macrophage gene transcription through its heterodimerization with other NRs or through RXR homodimerization. We also highlight the potential of RXR-controlled transcriptional programs as targets for the treatment of pathologies associated with altered macrophage function, such as atherosclerosis, insulin resistance, autoimmunity, and neurodegeneration.

Inflammatory markers in patients with internal carotid artery stenosis

INTRODUCTION

Available reports underline the significance of the inflammatory process in the development, progression and destabilisation of atherosclerotic plaques in the internal carotid artery (ICA). The aim of this study was to evaluate the relationship between the degree of ICA stenosis, ultrasound plaque morphology and serum concentration of selected inflammatory markers.

MATERIAL AND METHODS

Sixty-five patients with ICA stenosis > 50% (39 symptomatic) and 30 healthy volunteers were enrolled in the study. Clinical, neurological examination and laboratory evaluation (leucocyte count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), fibrinogen, tumour necrosis factor-α (TNF-α), interleukins (1β, 6 and 10), anti-cytomegalovirus IgG antibody titre) were performed. Stenosis grade ≥ 70%, ulcerations on the plaque surface and a hypoechoic (or predominantly hypoechoic) structure of the plaque, obtained by colour-coded duplex examination, were accepted as the characteristics of unstable stenoses.

RESULTS

Unstable ultrasound features of ICA stenosis were found significantly more often in symptomatic than in asymptomatic patients (71.79% vs. 30.71% for stenosis degree ≥ 70%, p = 0.001 and 61.23% vs. 38.46% for unstable plaque morphology, p = 0.01). Patients with ICA stenosis had significantly higher serum concentrations of interleukin-6, fibrinogen, ESR and higher CRP values than the individuals from the control group (p = 0.001, p = 0.009, p = 0.036, p = 0.009 respectively). Patients with unstable plaques structure had significantly higher concentrations of TNF-α, interleukin-6, fibrinogen, higher number of leukocytes, monocytes and higher CRP values than patients with stable plaques (p = 0.008, p = 0.049, p = 0.012, p = 0.0002, p = 0.006, p = 0.0003 respectively). No significant differences in above-mentioned parameters between the groups with stenosis < 70% and ≥ 70% were found.

CONCLUSIONS

There is a relationship between the activity of the selected inflammatory markers in serum and atherosclerotic unstable internal carotid artery stenosis. There is no relationship between serum concentration of inflammatory markers and degree of carotid artery stenosis.

Lipemia retinalis - an unusual cause of visual acuity deterioration

Background

Hyperlipidemia is an identified factor of premature vessel atherosclerosis. Lipemia retinalis is an unusual retinal manifestation of hyperlipidemia and is thought to be directly correlated with the serum triglyceride level.

Case Report

This paper discusses the case of a 55-year-old patient with lipemia retinalis, which deteriorated his visual acuity. The patient had an extremely high serum cholesterol level (1053 mg/dl) and a very high level of triglycerides (1513 mg/dl). The normalization of serum lipids, reversion of retinal vessels alterations and visual acuity improvement was achieved after an intensive statin lipid-lowering therapy. Pathological changes of the patient’s retina, connected with lipemia retinalis, disappeared completely.

Conclusions

Hyperlipidemia can cause lipemia retinalis, which is characterized by the hyperlipidemic vascular lesions-whitish color of vessels, lipid infiltration into the retina and decrease of visual acuity. The lipid-lowering therapy may lead to the normalization of the appearance of the fundus and restore the visual acuity.

Reduction in atherosclerotic events: a retrospective study in an outpatient cardiology practice

INTRODUCTION

Although atherosclerotic disease cannot be cured, risk of recurrent events can be reduced by application of evidence-based treatment protocols involving aspirin, beta blockers, angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, and statin medications. We studied atherosclerotic event rates in a patient population treated before and after the development of aggressive risk factor reduction treatment protocols.

MATERIAL AND METHODS

We performed a retrospective chart review of patients presenting for follow-up treatment of coronary artery disease in a community cardiology practice, comparing atherosclerotic event rates and medication usage in a 2-year treatment period prior to 2002 and a 2-year period in 2005-2008. Care was provided in both the early and later eras by 7 board-certified cardiologists in a suburban cardiology practice. Medication usage was compared in both treatment eras. The primary outcome was a composite event rate of myocardial infarction, cerebrovascular events, and coronary interventions.

RESULTS

Three hundred and fifty-seven patients were studied, with a follow-up duration of 12.1 (±3.5) years. There were 132 composite events in 104 patients (29.1%) in the early era compared to 40 events in 33 patients (9.2%) in the later era (p < 0.0001). From the early to the later eras, there was an increase in use of β-blockers (66% to 83%, p < 0.0001), angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (34% to 80%, p < 0.0001), and statins (40% to 90%, p < 0.0001).

CONCLUSIONS

Application of aggressive evidence-based medication protocols for treatment of atherosclerosis is associated with a significant decrease in atherosclerotic events or need for coronary intervention.