Therapeutic Implications of PPARgamma in Cardiovascular Diseases

Optimized synthesis characterization and protective activity of quercetin and quercetin–chitosan nanoformula against cardiotoxicity that was induced in male Wister rats via anticancer agent: doxorubicin

The study’s goal was to look into the protective properties of quercetin (QU) in natural form and QU nanoparticles-loaded chitosan nanoparticles (QU-CHSNPs) against cardiotoxicity. The ionotropic gelation approach was adopted to form QU-CHSNPs. The characterizations were performed using advanced techniques. In vitro, the release profile of QU was studied. Cardiotoxicity was induced by doxorubicin (DOX) and protected via concurrent administration of QU and QU-CHSNPs. The heart's preventive effects of QU and QU-CHSNPs were manifested by a decrease in elevated serum activities of cardiac enzymes, as well as an improvement in the heart's antioxidant defence system and histological changes. The findings substantiated QU-CHSNPs' structure with an entrapment efficiency of 92.56%. The mean of the zeta size distribution was 150 nm, the real average particle size was 50 nm, and the zeta potential value was − 27.9 mV, exhibiting low physical stability. The percent of the free QU-cumulative release was about 70% after 12 h, and QU-CHSNPs showed a 49% continued release with a pattern of sustained release, reaching 98% after 48 h. And as such, QU and QU-CHSNPs restrained the induced cardiotoxicity of DOX in male Wistar rats, with the QU-CHSNPs being more efficient.

The Protective Role of Peroxisome Proliferator-Activated Receptor-Gamma in Seizure and Neuronal Excitotoxicity

The peroxisome proliferator-activated receptor (PPAR) family, type II nucleus receptors have been successfully tested for their neuroprotective potential in certain central nervous system diseases. The aim of the present study was to determine if modulation by PPAR-γ could attenuate pilocarpine-induced seizures and decrease neuronal excitability. Adult male C57BL/6 mice were divided into two groups: one group received pretreatment with pioglitazone and the other received dimethyl sulfoxide (DMSO) for a period of 2 weeks. Status epilepticus was then induced in both groups by lithium-pilocarpine, after which seizure susceptibility, severity, and mortality were evaluated. Hippocampal histopathology was carried out on all mice at 24 h post-status epilepticus as well as blood-brain barrier (BBB) damage analysis. With the aid of patch clamp technology, the hippocampal neuronal excitability from mice with PPAR-γ 50% expression (Pparg^C/C) and PPAR-γ 25% expression (Pparg^C/-), as well as the effect of pioglitazone on the sodium currents in hippocampal neurons, were evaluated. It was found that pioglitazone, a PPAR-γ agonist, could attenuate pilocarpine-induced seizure severity in mice. Pathological examination showed that pioglitazone significantly attenuated pilocarpine-induced status epilepticus-related hippocampal neuronal loss and BBB damage. Further characterization of neuronal excitability revealed higher excitability in the brain slices from mice with Pparg^C/- expression, compared with the Pparg^C/C group. It was also found that pioglitazone could decrease sodium currents in hippocampal neurons. In conclusion, PPAR-γ deficiency aggravated neuronal excitability and excitotoxicity. PPAR-γ attenuated pilocarpine-induced seizure severity, neuronal loss, BBB damage, and sodium currents in hippocampal neurons. Modulation of PPAR-γ could be a potential novel treatment for epileptic seizures.

Pioglitazone stabilizes atherosclerotic plaque by regulating the Th17/Treg balance in AMPK-dependent mechanisms

Background

Pioglitazone (PIO), a thiazolidinediones drug, is a well-known anti-diabetic medicine, but its anti-atherosclerotic effects remain controversial. Thus it is important to investigate the effects of PIO on atherogenesis and the relevant mechanisms.

Methods

For in vitro studies, primary cultured or AMP-activated protein kinase (AMPK) inhibited splenocytes were treated with oxidized low density lipoprotein (ox-LDL) or ox-LDL plus PIO. Percentage of T helper 17 (Th17) and regulatory T (Treg) cells were determined by flow cytometry. Expression of AMPK, interleukin-17 (IL-17) and forkhead box P3 (FoxP3) were detected by Western blots. For in vivo studies, apolipoprotein E–deficient (apoE−/−) mice fed with western diet were treated with PIO or vehicle for 8 weeks respectively. Percentage of Th17 and Treg cells in spleen were measured by immunohistochemical analysis. The atherosclerotic lesions were analyzed using oil red O staining, and collagen types I and III in atherosclerotic lesions were stained by Sirius red. Expression of IL-17 and FoxP3 were determined by quantitative polymerase chain reaction.

Results

In cultured primary splenocytes, PIO dramatically inhibited Th17 and raised Treg. Intriguingly, pharmacological and genetic AMPK inhibitions abolished PIO-induced Treg elevation and Th17 inhibition. Moreover, PIO significantly induced AMPK phosphorylation, decreased IL-17⁺ and increased FoxP3⁺ cells in spleen of apoE−/− mice. Finally, PIO did not alter plaque area, but intriguingly, stabilized atherosclerotic plaque through collagen induction in apoE−/− mice. PIO treatment also improved Th17/Treg balance in atherosclerotic lesions.

Conclusions

PIO exhibits anti-atherosclerotic effects for stabilization of atherosclerotic plaque through regulating the Th17/Treg balance in an AMPK-dependent manner.

Peroxisome Proliferator-Activated Receptor γ Activity is Required for Appropriate Cardiomyocyte Differentiation

Objective

Peroxisome proliferator-activated receptor γ (PPARγ) is a member of the PPAR nuclear receptor superfamily. Although PPARγ acts as a master transcription factor in adipocyte differentiation, it is also associated with a variety of cell functions including carbohydrate and lipid metabolism, glucose homeostasis, cell proliferation and cell differentiation. This study aimed to assess the expression level of PPARγ in order to address its role in cardiac cell differentiation of mouse embryonic stem cells (mESCs).

Materials and Methods

In this an intervening study, mESCs were subjected to cardiac differentiation. Total RNA was extracted from the cells and quantitative real time polymerase chain reaction (qPCR) was carried out to estimate level of gene expression. Furthermore, the requirement of PPARγ in cardiac differentiation of mESCs, during cardiac progenitor cells (CPCs) formation, was examined by applying the respective agonist and antagonist.

Results

The obtained data revealed an elevation in the expression level of PPARγ during spontaneous formation of CPCs and cardiomyocytes. Our results indicated that during CPC formation, PPARγ inactivation via treatment with GW9662 (GW) reduced expression of CPC and cardiac markers.

Conclusion

We conclude that PPARγ modulation has an effective role on cardiac differentiation of mESCs at the early stage of cardiomyogenesis.

PPAR Gamma Expression Levels during Development of Heart Failure in Patients with Coronary Artery Disease after Coronary Artery Bypass-Grafting

Genetic research has elucidated molecular mechanisms of heart failure (HF). Peroxisome proliferator-activated receptors (PPARs) seem to be important in etiology of HF. The aim of study was to find the correlation between PPARγ expression during development of HF in patients and coronary artery disease (CAD) after coronary artery bypass-grafting (CABG). Methods and Results. We followed up 157 patients (mean age 63) with CAD without clinical, laboratory, or echo parameters of HF who underwent CABG. Clinical and laboratory status were assessed before CABG and at 1, 12, and 24 months. During CABG slices of aorta (Ao) and LV were collected for genetic research. HF was defined as LVEF <40% or NT-proBNP >400 pg/mL or 6MWT <400 m. Patients were divided into 2 groups: with and without HF. PPARγ expression in Ao and LV was not increased in both groups at 2-year follow-up. Sensitivity of PPARγ expression in Ao above 1.1075 in detection of HF was 20.5% (AUC 0.531, 95% CI 0.442–0.619). Positive predictive value (Ppv) was 85.7%. Sensitivity and specificity of PPARγ expression in the LV in detection of HF were 58% and 92.9%, respectively (AUC 0.540, 95% CI 0.452–0.626). Ppv was 73.2%. Conclusion. PPARγ expression in Ao and LV was comparable and should not be used as predictive factor for development of HF in patients with CAD after CABG.

Classical swine fever virus NS5A protein localizes to endoplasmic reticulum and induces oxidative stress in vascular endothelial cells

Classical swine fever virus (CSFV) causes a severe disease of pigs that is characterized by hemorrhage, disseminated intravascular coagulation, and leucopenia. Until now, the role of the nonstructural protein 5A (NS5A) produced by CSFV in the pathogenesis of CSF is not well known. In this study, we investigated the function of CSFV NS5A by examining its role in the induction of oxidative stress and related intracellular events. Stable swine umbilical vein endothelial cell lines expressing CSFV NS5A were established and showed that CSFV NS5A is localized to endoplasmic reticulum and induces oxidative stress associated with enhanced reactive oxygen species production. The expression of NS5A protein exerts different effects on the three major antioxidants. Particularly, it exhibits a significant increase in transcriptional activities of antioxidant proteins thioredoxin and peroxiredoxin-6, but accompanied by a concomitant decrease of antioxidant protein heme oxygenase-1. Further studies showed that cyclooxygenase-2, a pro-inflammatory protein related to oxidative stress, is up-regulated while anti-inflammatory protein peroxisome proliferator-activated receptor-γ, an important mediator in vascular functional regulation, is down-regulated in CSFV NS5A expressing cells. This study suggested that CSFV NS5A plays important roles in the induction of oxidative stress and inflammatory response in vascular endothelial cells. These findings provide novel information on the function of the poorly characterized CSFV NS5A and provide an insight into the mechanism by which CSFV NS5A can alter intracellular events associated with the viral infection.

Effects of telmisartan and losartan on cardiovascular protection in Japanese hypertensive patients

The Telmisartan and Losartan Cardiac Evaluation Trial, a multicenter, prospective, randomized, open-labeled, blinded-endpoint trial, was designed to compare the effects of two angiotensin II receptor blockers (ARBs), telmisartan and losartan, on cardiovascular protection in Japanese patients with mild to moderate essential hypertension. We compared the effects of telmisartan and losartan on left ventricular (LV) hypertrophy, cardiac function, atherosclerosis of carotid arteries and surrogate markers related to the actions of peroxisome proliferator-activated receptor-γ. A total of 58 patients were enrolled in the present trial and the follow-up period was 1 year. There were no significant differences in blood pressure (BP) levels between the telmisartan group and the losartan group throughout the trial. The percentage of the patients treated with ARB monotherapy was significantly higher in the telmisartan group compared with the losartan group. In addition, the progression of intima-media thickness of common carotid artery was significantly inhibited in the telmisartan group compared with the losartan group. Neither group experienced significant changes in cardiac function and LV mass index. There were no differences between the groups with respect to changes in surrogate markers such as serum adiponectin, creatinine, homeostasis model assessment index, plasminogen activator inhibitor-1 and high sensitivity C-reactive protein. Although BP levels were equal and well controlled in both groups, telmisartan showed more protective vascular effects than losartan.