Peroxisome proliferator-activated receptor (PPAR α/γ) agonists as a potential target to reduce cardiovascular risk in diabetes

Vimentin protein is a factor for decreasing breast cancer cell proliferation co-culture with human bone marrow-derived mesenchymal stem cells pre-treated with thiazolidinedione solutions

BACKGROUND

Our previous study investigated the levels of soluble growth factors in the conditioned media of bone marrow-derived mesenchymal stem cells (BMSCs) pre-treated with thiazolidinedione solutions. The present study aimed to investigate the complex intracellular proteins extracted from BMSCs pre-treated with pioglitazone and/or rosiglitazone using proteomics.

METHODS

The proliferative effect of the identified protein on MCF-7 cells that interacted non-adhesively with BMSCs pre-treated with pioglitazone and/or rosiglitazone was evaluated using cell culture inserts and conditioned media. The mRNA expression of proliferation and lipid accumulation markers was also evaluated in the interacted MCF-7 cells by reverse transcription-quantitative PCR. Finally, the correlation between the identified protein and fibroblast growth factor 4 (FGF-4) protein in the conditioned media of the pre-treated BMSCs was evaluated by ELISA.

RESULTS

The present study identified vimentin as the specific protein among the complex intracellular proteins that likely plays a role in MCF-7 cell proliferation when the breast cancer cells interacted non-adhesively with BMSCs pre-treated with a combination of pioglitazone and rosiglitazone. The inhibition of this protein promoted the proliferation of MCF-7 cells when the breast cancer cells interacted with pre-treated BMSCs. Gene expression analysis indicated that pre-treatment of BMSCs with a combination of pioglitazone and rosiglitazone decreased the mRNA expression of Ki67 and proliferating cell nuclear antigen in MCF-7 cells. The pre-treatment did not induce mRNA expression of PPARγ, which is a sign of lipid accumulation. The level of vimentin protein was also associated with the FGF-4 protein expression level in the conditioned media of the pre-treated BMSCs. Bioinformatics analysis revealed that vimentin regulated the expression of FGF-4 through its interaction with SRY-box 2 and POU class 5 homeobox 1.

CONCLUSIONS

The present study identified a novel intracellular protein that may represent the promising target in pre-treated BMSCs to decrease the proliferation of breast cancer MCF-7 cells for human health and wellness.

PPARγ Acetylation in Adipocytes Exacerbates BAT Whitening and Worsens Age-Associated Metabolic Dysfunction

Aging and obesity are the two prominent driving forces of metabolic dysfunction, yet the common underlying mechanisms remain elusive. PPARγ, a central metabolic regulator and primary drug target combatting insulin resistance, is hyperacetylated in both aging and obesity. By employing a unique adipocyte-specific PPARγ acetylation-mimetic mutant knock-in mouse model, namely aKQ, we demonstrate that these mice develop worsened obesity, insulin resistance, dyslipidemia, and glucose intolerance as they age, and these metabolic deregulations are resistant to intervention by intermittent fasting. Interestingly, aKQ mice show a whitening phenotype of brown adipose tissue (BAT) manifested in lipid filling and suppressed BAT markers. Diet-induced obese aKQ mice retain an expected response to thiazolidinedione (TZD) treatment, while BAT function remains impaired. This BAT whitening phenotype persists even with the activation of SirT1 through resveratrol treatment. Moreover, the adverse effect of TZDs on bone loss is exacerbated in aKQ mice and is potentially mediated by their increased Adipsin levels. Our results collectively suggest pathogenic implications of adipocyte PPARγ acetylation, contributing to metabolic dysfunction in aging and thus posing as a potential therapeutic target.

Advances in pig models of human diseases

Animal models of human diseases play a critical role in medical research. Pigs are anatomically and physiologically more like humans than are small rodents such as mice, making pigs an attractive option for modeling human diseases. Advances in recent years in genetic engineering have facilitated the rapid rise of pig models for use in studies of human disease. In the present review, we summarize the current status of pig models for human cardiovascular, metabolic, neurodegenerative, and various genetic diseases. We also discuss areas that need to be improved. Animal models of human diseases play a critical role in medical research. Advances in recent years in genetic engineering have facilitated the rapid rise of pig models for use in studies of human disease. In the present review, we summarize the current status of pig models for human cardiovascular, metabolic, neurodegenerative, various genetic diseases and xenotransplantation.

High-Dose Omega-3 Fatty Acids in Cardiovascular Prevention: Finally Living Up to Their Potential?

Despite the widespread use of statins in the setting of high cardiovascular risk, many patients continue to experience clinical events. This highlights the need to identify additional therapeutic strategies for high-risk patients. Interest in the use of omega-3 polyunsaturated fatty acids to prevent cardiovascular disease has been high for several decades. Despite promising results from before the statin era, many clinical trials have produced disappointing findings regarding products containing conventional doses of omega-3 fatty acids. More recent clinical trials using high doses of omega-3 fatty acids in targeted populations have suggested potential benefit when targeting the risk driven by atherogenic dyslipidemia. We review the clinical implications of completed and ongoing trials.

Assessment of omega-3 carboxylic acids in statin-treated patients with high levels of triglycerides and low levels of high-density lipoprotein cholesterol: Rationale and design of the STRENGTH trial

It is uncertain whether omega-3 fatty acids are beneficial in statin-treated patients. Epanova is a mix of omega-3 free fatty acids, not requiring co-ingestion with food, which can lower triglycerides by up to 31%. STRENGTH will examine whether Epanova 4 g daily reduces the rate of cardiovascular events in statin-treated patients with hypertriglyceridemia and low levels of HDL-C at high risk for developing cardiovascular events. STRENGTH is a randomized, double-blind, placebo-controlled trial. Patients had a triglyceride level ≥ 180 to <500 mg/dL and HDL-C < 42 mg/dL (men) or < 47 mg/dL (women) in the presence of either (1) established atherosclerotic cardiovascular disease, (2) diabetes with one additional risk factor, or (3) were other high-risk primary prevention patients, based on age and risk factor assessment. Patients should be treated with a statin, for >4 weeks, and have LDL-C < 100 mg/dL, but were also eligible if LDL-C was ≥100 mg/dL while on maximum tolerated statin therapy. The study will extend from October 30, 2014 to October 30, 2019. 13 086 patients were randomized to Epanova 4 g or placebo daily in addition to standard medical therapy. The primary efficacy outcome is time to first event of cardiovascular death, myocardial infarction, stroke, coronary revascularization or hospitalization for unstable angina. The trial will continue until 1600 patients reach the primary endpoint, with a median duration of therapy of 3 years. STRENGTH will determine whether Epanova 4 g daily will reduce cardiovascular events in statin-treated high-risk patients with hypertriglyceridemia and low HDL-C levels.

Gene-gene interaction between PPARG and CYP1A1 gene on coronary artery disease in the Chinese Han Population

AIMS

To observe the influence of the peroxisome proliferator-activator receptor-G (PPAR-G) gene and cytochrome P4501A1 (CYP1A1) single-nucleotide polymorphisms (SNPs), and interactions among several SNPs on coronary artery disease (CAD) risk.

METHODS

A total of 1106 participants (including 583 males and 523 females) including 550 CAD patients and 556 control subjects were recruited in this study, and the mean age for these participants was 55.5 ± 11.8 years old. Logistic regression was used to observe association of SNP within PPARG and CYP1A1 with CAD risk and GMDR model was used to screen the best interaction combinations.

RESULTS

CAD susceptibility was higher in those with homozygous mutant of rs10865710, rs1805192 and rs4646903 than those with wild-type homozygotes, OR (95%CI) were 1.47 (1.15-1.92), 1.69 (1.27-2.09) and 1.72 (1.35-2.32), respectively. We also found a significant two-locus model involving rs1805192 and rs4646903 (p = 0.0107), and the cross-validation consistency of this locus model was 10 of 10, the testing accuracy of this model is 62.17%. Logistic regression shown that CAD risk was the highest in those with rs1805192- Pro/Ala or Ala/Ala and rs4646903- AG+GG genotype, and was lowest in those with rs1805192- Pro/ Pro and rs4646903- AA genotype, OR(95%CI) = 3.56 (1.91-5.42).

CONCLUSIONS

Polymorphism in rs10865710, rs1805192 and rs4646903 and interaction between rs1805192 and rs4646903 were related with increased CAD susceptibility.

Insulin resistance and vascular dysfunction in chronic kidney disease: mechanisms and therapeutic interventions

Insulin resistance (IR) is a novel cardiovascular risk factor that has been implicated in the pathogenesis of cardiovascular disease (CVD) in patients with chronic kidney disease (CKD). Beyond its metabolic effects, insulin can potentially mediate the increased risk for CVD through its vasoactive properties. This review examines key clinical data and potential mechanisms linking IR and cardiovascular risk in CKD. While lifestyle interventions and pharmacotherapies with known insulin-sensitizing properties are promising therapeutic targets to reduce the CVD burden in this population, clinical trial data on the effect of insulin sensitization on vascular function in CKD are either lacking or conflicting and are limited by small sample size and short duration of intervention. Affirming the role of IR in lowering CVD risk in CKD will require prospective randomized controlled studies with sufficient sample size and hard clinical outcomes. Future research efforts should be directed at assessing the efficacy, safety and mechanisms by which novel insulin sensitizers such as bile acid sequestrant, selective and dual peroxisome proliferator-activated receptor modulators and modulators of gut microbiota and uraemic toxins alter vascular function in patients with CKD.

Diabetes and cardiovascular disease: let's push forward with translational research

Albeit advances in therapy have reduced morbidity and mortality in patients with diabetes, cardiovascular (CV) risk is far to be eradicated. This is partially due to the fact that breakthrough therapies have yet to be approved to counteract the atherosclerotic burden in this setting. Therefore, it is very important to understand the molecular mechanisms underpinning diabetes-related CV complications. Growing evidence is supporting the concept that translational research is perhaps the best approach to unveil novel insights into disease etiology and its link with CV phenotypes. The recent employment of high throughput "omics" (i.e., metabolomics, transcriptomics, proteomics) is a clinically relevant approach which may provide insightful interpretations of diabetes-related biological signals. The possibility to analyse thousands or more molecules simultaneously has given "omics" the ability to generate enormous quantities of data which may somehow offer a precious "window on the disease". In the present article, we critically discuss the importance of translational research in diabetes, including potential difficulties which may arise in the implementation and development of promising technologies from the laboratory to the marketplace.

5-Caffeoylquinic acid decreases diet-induced obesity in rats by modulating PPARα and LXRα transcription

BACKGROUND

Chlorogenic acids (CGAs) are widely distributed in plant material, including foods and beverages. 5-Caffeoylquinic acid (5-CQA) is the most studied CGA, but the mechanism of its hypolipidaemic effect remains unclear. This study aimed to determine the effect of 5-CQA on lipid metabolism in the liver of Sprague-Dawley rats fed a high-fat diet (HFD).

RESULTS

5-CQA suppressed HFD-induced increases in body weight and visceral fat-pad weight, serum lipid levels, and serum and hepatic free fatty acids in a dose-dependent manner. Real-time polymerase chain reaction revealed that 5-CQA altered the mRNA expression of the transcription factors peroxisome proliferator-activated receptor α (PPARα) and liver X receptor α (LXRα) and target genes involved in hepatic fatty acid uptake, β-oxidation, fatty acid synthesis, and cholesterol synthesis. Moreover, hepatic tissue sections from HFD-fed rats showed many empty vacuoles, suggesting that liver cells were filled with more fat droplets. However, 5-CQA significantly ameliorated this effect.

CONCLUSION

5-CQA may improve lipid metabolism disorders by altering the expression of PPARα and LXRα, which are involved in multiple intracellular signalling pathways.

Observational study of effects of Saroglitazar on glycaemic and lipid parameters on Indian patients with type 2 diabetes

Cardiovascular risk reduction is an important issue in the management of patients with Type 2 diabetes mellitus. Peroxisome proliferator activated receptor (PPAR) agonists favourably influence glycaemic and lipid parameters in patients with Type 2 diabetes and a dual PPAR agonist is expected to have favourable effect on both parameters. In this study we have analyzed the effect of Saroglitazar, a novel dual PPAR alpha & gamma agonist, on glycaemic and lipid parameters in Indian patients with Type 2 diabetes. After a mean follow-up period of 14 weeks in 34 patients, treatment with Saroglitazar, in a dose of 4 mg daily, resulted in significant improvement in both glycaemic and lipid parameters. There were significant mean reductions of fasting plasma glucose (36.71 mg/dl; p = 0.0007), post-prandial plasma glucose (66.29 mg/dl; p = 0.0005), glycosylated haemoglobin (1.13%; p < 0.0001), total cholesterol (48.16 mg/dl; p < 0.0001), low- density lipoprotein cholesterol (24.04 mg/dl; p = 0.0048), triglyceride (192.78 mg/dl; p = 0.0001), non-high density lipoprotein cholesterol (48.72 mg/dl; p < 0.0001) and the ratio of triglyceride and high density lipoprotein cholesterol (5.30; p = 0.0006). There was no significant change in body weight, blood pressure, high-density lipoprotein cholesterol and serum creatinine.

Current progress of genetically engineered pig models for biomedical research

The first transgenic pigs were generated for agricultural purposes about three decades ago. Since then, the micromanipulation techniques of pig oocytes and embryos expanded from pronuclear injection of foreign DNA to somatic cell nuclear transfer, intracytoplasmic sperm injection-mediated gene transfer, lentiviral transduction, and cytoplasmic injection. Mechanistically, the passive transgenesis approach based on random integration of foreign DNA was developed to active genetic engineering techniques based on the transient activity of ectopic enzymes, such as transposases, recombinases, and programmable nucleases. Whole-genome sequencing and annotation of advanced genome maps of the pig complemented these developments. The full implementation of these tools promises to immensely increase the efficiency and, in parallel, to reduce the costs for the generation of genetically engineered pigs. Today, the major application of genetically engineered pigs is found in the field of biomedical disease modeling. It is anticipated that genetically engineered pigs will increasingly be used in biomedical research, since this model shows several similarities to humans with regard to physiology, metabolism, genome organization, pathology, and aging.

The clinical burden of type 2 diabetes in patients with acute coronary syndromes: prognosis and implications for short- and long-term management

Type 2 diabetes mellitus (T2DM) is associated with increased morbidity and mortality in patients with acute coronary syndromes (ACS). Cardiometabolic risk factors, including hyperglycaemia, insulin resistance, atherogenic dyslipidaemia, increased visceral fat and inflammation, are associated with increased risk in this population and represent potential targets for treatment. In this review, management strategies for patients with T2DM post-ACS, both in the acute-care setting and in the long-term, are discussed. Although the benefits of long-term, aggressive, multifactorial risk factor modification are well established, a significant burden of recurrent events remains and the search for novel strategies continues. Several studies are assessing the potential cardiovascular (CV) benefits and safety of various classes of newer agents. Of these, AleCardio (aleglitazar), Examination of Cardiovascular Outcomes With Alogliptin versus Standard of Care in Patients With Type 2 Diabetes Mellitus and Acute Coronary Syndrome (EXAMINE; alogliptin) and Evaluation of LIXisenatide in Acute Coronary Syndrome (ELIXA; lixisenatide) specifically address patients with type 2 diabetes post-ACS. The mechanisms of action of these new therapies and aims of the CV outcome studies are briefly reviewed. The prevalence of type 2 diabetes continues to increase worldwide highlighting the need for new strategies that address the complex underlying processes that drive atherosclerosis and CV events in this high-risk patient population.

Role of PPARs in inflammatory processes associated with metabolic syndrome (Review)

Metabolic syndrome (MS) includes the presence of arterial hypertension, insulin resistance, dyslipidemia, cardiovascular disease (CVD) and abdominal obesity, which is associated with a chronic inflammatory response, characterized by abnormal adipokine production, and the activation of certain pro-inflammatory signaling pathways. Furthermore, the changes presented by the adipose tissue in MS favors the secretion of several molecular mediators capable of activating or suppressing a number of transcription factors, such as the peroxisome proliferator-activated receptors (PPARs), whose main functions include storage regulation and fatty acid catabolization. When they are activated by their ligands (synthetic or endogenous), they control several genes involved in intermediate metabolism, which make them, together with the PPAR gamma coactivator-1-α (PGC-1) and the silent information regulator T1 (SIRT1), good targets for treating metabolic diseases and their cardiovascular complications.

Open tubular columns containing the immobilized ligand binding domain of peroxisome proliferator-activated receptors α and γ for dual agonists characterization by frontal affinity chromatography with mass spectrometry detection

The peroxisome proliferator-activated receptors (PPARs) belong to the nuclear receptor superfamily. In the last years novel PPARs ligands have been identified and these include PPARα/γ dual agonists. To rapidly identify novel PPARs dual ligands, a robust binding assay amenable to high-throughput screening toward PPAR isoforms would be desirable. In this work we describe a parallel assay based on the principles of frontal affinity chromatography coupled to mass spectrometry (FAC-MS) that can be used to characterize dual agonists. For this purpose the ligand binding domain of PPARα receptor was immobilized onto the surface of open tubular capillaries to create new PPAR-alpha-OT columns to be used in parallel with PPAR-gamma-OT columns. The two biochromatographic systems were used in both ranking and Kd experiments toward new ureidofibrate-like dual agonists for subtype selectivity ratio determination. In order to validate the system, the Kd values determined by frontal analysis chromatography were compared to the affinity constants obtained by ITC experiments. The results of this study strongly demonstrate the specific nature of the interaction of the ligands with the two immobilized receptor subtypes.

L-Carnitine protects against arterial hypertension-related cardiac fibrosis through modulation of PPAR-γ expression

Cardiac fibrosis is a pathogenic factor in a variety of cardiovascular diseases and is characterized by an abnormal accumulation of extracellular matrix protein that leads to cardiac dysfunction. l-Carnitine (LC) plays an essential role in the β-oxidation of long-chain fatty acids in lipid metabolism. We have previously demonstrated the beneficial effects of LC in hypertensive rats. The aim of this study was to analyze the effect of LC on arterial hypertension-associated cardiac fibrosis and to explore the mechanisms of LC action. To this end, four groups of rats were used: Wistar (control), rats treated with 400mg/kg/day of LC, rats treated with 25mg/kg/day of l-NAME (to induce hypertension), and rats treated with LC+l-NAME simultaneously. We found an elevation in the myocardial expression of profibrotic factors (TGF-β1 and CTGF), types I and III of collagen, and NADPH oxidase subunits (NOX2 and NOX4), in hypertensive rats when compared with normotensive ones. In addition, an increase in myocardial fibrosis was also found in the l-NAME group. These results were accompanied by a down-regulation of PPAR-γ in the heart of hypertensive animals. When hypertensive rats were treated with LC, all these alterations were reversed. Moreover, a significant negative correlation was observed between myocardial interstitial fibrosis and mRNA expression of PPAR-γ. In conclusion, the reduction of cardiac fibrosis and the down-regulation of NOX2, NOX4, TGF-β1 and CTGF induced by LC might be, at least in part, mediated by an upregulation of PPAR-γ, which leads to a reduction on hypertension-related cardiac fibrosis.

Genetically engineered pig models for human diseases

Although pigs are used widely as models of human disease, their utility as models has been enhanced by genetic engineering. Initially, transgenes were added randomly to the genome, but with the application of homologous recombination, zinc finger nucleases, and transcription activator-like effector nuclease (TALEN) technologies, now most any genetic change that can be envisioned can be completed. To date these genetic modifications have resulted in animals that have the potential to provide new insights into human diseases for which a good animal model did not exist previously. These new animal models should provide the preclinical data for treatments that are developed for diseases such as Alzheimer's disease, cystic fibrosis, retinitis pigmentosa, spinal muscular atrophy, diabetes, and organ failure. These new models will help to uncover aspects and treatments of these diseases that were otherwise unattainable. The focus of this review is to describe genetically engineered pigs that have resulted in models of human diseases.

Molecular and metabolic mechanisms of cardiac dysfunction in diabetes

Diabetes mellitus type 2 (T2DM) is a widespread chronic medical condition with prevalence bordering on the verge of an epidemic. It is of great concern that cardiovascular disease is more common in patients with diabetes than the non-diabetic population. While hypertensive and ischemic heart disease is more common in diabetic patients, there is another type of heart disease in diabetes that is not associated with hypertension or coronary artery disease. This muscle functional disorder is termed "diabetic cardiomyopathy". Diastolic dysfunction characterized by impaired diastolic relaxation time and reduced contractility precedes systolic dysfunction and is the main pathogenic hallmark of this condition. Even though the pathogenesis of "diabetic cardiomyopathy" is still controversial, impaired cardiac insulin sensitivity and metabolic overload are emerging as major molecular and metabolic mechanisms for cardiac dysfunction. Systemic insulin resistance, hyperinsulinemia, dysregulation of adipokine secretion, increases in circulating levels of inflammatory mediators, aberrant activation of renin angiotensin aldosterone system (RAAS), and increased oxidative stress contribute dysregulated insulin and metabolic signaling in the heart and development of diastolic dysfunction. In addition, maladaptive calcium homeostasis and endothelial cell dysregulation endoplasmic reticular stress play a potential role in cardiomyocyte fibrosis/diastolic dysfunction. In this review, we will focus on emerging molecular and metabolic pathways underlying cardiac dysfunction in diabetes. Elucidation of these mechanisms should provide a better understanding of the various cardiac abnormalities associated with diastolic dysfunction and its progression to systolic dysfunction and heart failure.