Amanda Lopes

Obesity is a risk factor associated with cardiovascular diseases that may lead to heart failure (HF). However, in HF, overweight and obese patients have longer survival than underweight patients, a phenomenon known as the obesity paradox. MiRNAs play a fundamental role in gene regulation involved in obesity and HF. The main objective of this study was to identify and validate differentially expressed circulating miRNAs in HF–obese and HF–lean patients. This case–control study was carried out in two phases: discovery and validation. In the discovery phase, plasma samples from 20 HF patients and from 10 healthy controls were analyzed using the miRNA 4.0 Affymetrix GeneChip array. Differentially expressed miRNAs were ranked and selected for validation. In this phase, plasma miRNAs -451a, -22-3p, and -548ac from 80 patients and controls were analyzed by qPCR. Target analysis and functional enrichment analysis were performed. When comparing HF–lean and HF–obese groups compared to controls, miRNAs -451a and -22-3p were up-regulated in both discovery and validation phases, while -548ac was down-regulated in the discovery phase and up-regulated in the validation phase, indicating that miRNA changes are independent of obesity. These miRNAs regulate genes and different biological processes associated with metabolic, morphological, and functional outcomes.

Exercise promotes physiological cardiac hypertrophy and activates the renin-angiotensin system (RAS), which plays an important role in cardiac physiology, both through the classical axis [angiotensin II type 1 receptor (AT1R) activated by angiotensin II (ANG II)] and the alternative axis [proto-oncogene Mas receptor (MASR) activated by angiotensin-(1–7)]. However, very intense exercise could have deleterious effects on the cardiovascular system. We aimed to analyze the cardiac hypertrophy phenotype and the classical and alternative RAS axes in the myocardium of mice submitted to swimming exercises of varying volume and intensity for the development of cardiac hypertrophy. Male Balb/c mice were divided into three groups, sedentary, swimming twice a day without overload (T2), and swimming three times a day with a 2% body weight overload (T3), totaling 6 wk of training. Both training groups developed similar cardiac hypertrophy, but only T3 mice improved their oxidative capacity. We observed that T2 had increased levels of MASR, which was followed by the activation of its main downstream protein AKT; meanwhile, AT1R and its main downstream protein ERK remained unchanged. Furthermore, no change was observed regarding the levels of angiotensin peptides, in either group. In addition, we observed no change in the ratio of expression of the myosin heavy chain β-isoform to that of the α-isoform. Fibrosis was not observed in any of the groups. In conclusion, our results suggest that increasing exercise volume and intensity did not induce a pathological hypertrophy phenotype, but instead improved the oxidative capacity, and this process might have the participation of the RAS alternative axis.

Circulating advanced glycation end products (AGE) and their receptor, RAGE, are increased after a myocardial infarction (MI) episode and seem to be associated with worse prognosis in patients. Despite the increasing importance of these molecules in the course of cardiac diseases, they have never been characterized in an animal model of MI. Thus, the aim of this study was to characterize AGE formation and RAGE expression in plasma and cardiac tissue during cardiac remodeling after MI in rats. Adult male Wistar rats were randomized to receive sham surgery (n = 15) or MI induction (n = 14) by left anterior descending coronary artery ligation. The MI group was stratified into two subgroups based on postoperative left ventricular ejection fraction: low (MI^lowEF) and intermediate (MI^intermEF). Echocardiography findings and plasma levels of AGEs, protein carbonyl, and free amines were assessed at baseline and 2, 30, and 120 days postoperatively. At the end of follow-up, the heart was harvested for AGE and RAGE evaluation. No differences were observed in AGE formation in plasma, except for a decrease in absorbance in MI^lowEF at the end of follow-up. A decrease in yellowish-brown AGEs in heart homogenate was found, which was confirmed by immunodetection of N-ε-carboxymethyl-lysine. No differences could be seen in plasma RAGE levels among the groups, despite an increase in MI groups over the time. However, MI animals presented an increase of 50% in heart RAGE at the end of the follow-up. Despite the inflammatory and oxidative profile of experimental MI in rats, there was no increase in plasma AGE or RAGE levels. However, AGE levels in cardiac tissue declined. Thus, we suggest that the rat MI model should be employed with caution when studying the AGE-RAGE signaling axis or anti-AGE drugs for not reflecting previous clinical findings.

Antioxidant-rich foods may decrease oxidative stress and have a direct impact on atherosclerosis by reducing low-density lipoprotein (LDL) oxidation. Our aim was to assess the impact of a flavonoid-rich diet on oxidative stress, inflammatory response, and lipid profile in patients with coronary artery disease submitted to elective percutaneous coronary intervention (PCI). Thirty-three patients submitted to elective PCI were randomly allocated to follow either a flavonoid rich antioxidant (AOX) diet or a control diet based on National Cholesterol Education Program Adult Treatment Panel III recommendations. Patients were followed for 6 months. Dietary intake was recorded at the start and at the end of the follow-up period, as were oxidative stress markers (ferric reducing ability of plasma and protein sulphydryl) and Creactive protein (CRP). Patients randomized to follow the AOX diet had a reduction in energy, carbohydrate, and lipid intake, as well as increased flavonoid intake. Compared to the control group, there were no changes in oxidative stress markers or CRP in the patients following the AOX diet, but these patients had a significant decrease in LDL cholesterol levels. In conclusion, the findings of this study suggest that a flavonoid-based antioxidant-rich diet is not associated with reductions in oxidative stress or inflammatory markers 6 months after percutaneous coronary intervention. Nonetheless, patients in the intervention group experienced significant reductions in LDL cholesterol, which may indicate cardiovascular benefits of AOX diets despite of inflammation and oxidative stress markers.

The antioxidant N-acetycysteine can turn into a prooxidant molecule in presence of iron ions. Thus, our goal was to test if the association of N-acetylcysteine (NAC) and an iron chelator (deferoxamine—DFX) in a rodent model of acute myocardial infarction (AMI) improves cardiac function. Male Wistar rats were subjected to a SHAM surgery or AMI. The animals were randomized: vehicle, NAC (25 mg/kg for 28 days), DFX (40 mg/kg for 7 days), or NAC plus DFX (NAC plus DFX, respectively). Animals were killed 28 days after the AMI. Animals treated with NAC/DFX showed an increase in left ventricular ejection fraction at 28 days when compared with vehicle group (45.2 ± 10.9 % vs. 34.7 ± 8.7 %, p = 0.03). Antioxidant effect of NAC/DFX treatment decreased 4-hydroxynonenal when compared to AMI group (p = 0.06). In conclusion, we showed beneficial effect of NAC/DFX association in improving left ventricle function in an experimental AMI.

MicroRNAs (miRs) are a class of small non-coding RNAs that regulate gene expression. Studies of transgenic mouse models have indicated that deregulation of a single miR can induce pathological cardiac hypertrophy and cardiac failure. The roles of miRs in the genesis of physiological left ventricular hypertrophy (LVH), however, are not well understood. To evaluate the global miR expression in an experimental model of exercise-induced LVH. Male Balb/c mice were divided into sedentary (SED) and exercise (EXE) groups. Voluntary exercise was performed on an odometer-monitored metal wheels for 35 days. Various tests were performed after 7 and 35 days of training, including a transthoracic echocardiography, a maximal exercise test, a miR microarray (miRBase v.16) and qRT-PCR analysis. The ratio between the left ventricular weight and body weight was increased by 7% in the EXE group at day 7 (p<0.01) and by 11% at day 35 of training (p<0.001). After 7 days of training, the microarray identified 35 miRs that were differentially expressed between the two groups: 20 were up-regulated and 15 were down-regulated in the EXE group compared with the SED group (p = 0.01). At day 35 of training, 25 miRs were differentially expressed: 15 were up-regulated and 10 were decreased in the EXE animals compared with the SED animals (p<0.01). The qRT-PCR analysis demonstrated an increase in miR-150 levels after 35 days and a decrease in miR-26b, miR-27a and miR-143 after 7 days of voluntary exercise. We have identified new miRs that can modulate physiological cardiac hypertrophy, particularly miR-26b, -150, -27a and -143. Our data also indicate that previously established regulatory gene pathways involved in pathological LVH are not changed in physiological LVH.