Angela Maria Vicente Tavares

Bone marrow derived cells decrease inflammation but not oxidative stress in an experimental model of acute myocardial infarction

AIMS Bone marrow cell (BMC) therapy is thought to exert beneficial effects on the infarcted heart. We assessed cardiac function and its correlation with redox status and inflammation in cardiac tissue early post-AMI in rats treated with BMC. MAIN METHODS Male Wistar rats (8-week-old) were randomized into four groups: Sham-operated (S); AMI; S+treatment (ST) and AMI+treatment (AMIT). Therapy with BMC was carried out immediately post-experimental left anterior coronary artery ligation induced-AMI, and assessments made 48h later. Cardiac function and morphometrics were evaluated by echocardiographyc parameters in vivo. Cardiac tissue tumor necrosis factor (TNF)-α and interleukin (IL)-6 were measured by Western Blot. Oxidative stress parameters including reduced (GSH) and oxidized (GSSG) glutathione ratio, hydrogen peroxide level, lipid and protein oxidation, superoxide dismutase, catalase and glutathione peroxidase activities were measured spectrophotometrically. KEY FINDINGS Ejection fraction was lower in infarcted groups and did not improve in BMC-treated animals: AMI (51±5%) vs. S (74±7%) and AMIT (56±10%) vs. ST groups (73±3%). Both TNF-α and IL-6 myocardial expression increased post-AMI and were reduced following BMC therapy. Nonetheless, there was a decrease in GSH/GSSG ratio in infarcted groups which was greater in BMC-treated groups: AMI (8.21±3.8) vs. S (14.61±3.4) and AMIT (2.1±0.7) vs. ST (4.7±1.5). SIGNIFICANCE The data suggest that BMC promoted a redox status favorable to the oxidation of the pro-inflammatory cytokines in the myocardium, exerting an anti-inflammatory-like effect.

Effects of different physical training protocols on ventricular oxidative stress parameters in infarction-induced rats

AIM Physical exercise is important in the prevention and treatment of cardiovascular diseases. Nevertheless, controversy remains around type and intensity of effort required for significant biochemical protective changes. This study investigates two exercise protocols on ventricular oxidative parameters in rats post-infarction. MAIN METHODS Thirty-six 2-month-old male Wistar rats were divided in two groups (n=18): Sham and acute myocardial infarction (AMI) conducted by blocking the coronary artery. Thirty days after AMI, animals were divided in 6 subgroups (n=6): sham, sham+continuous training (60 min), sham+interval training, AMI, AMI+continuous training, and AMI+interval training. Training was conducted in water (30-32°C) 5 times a week for 6 weeks. Animals were sacrificed 48 h after the last exercise routine. Left ventricles were used for oxidative stress analyses (antioxidant enzyme activity and level, oxidative damage) and HIF1α and cit c oxidase expression. KEY FINDINGS After AMI, both exercise models decreased superoxide levels significantly. Training routines did not alter SOD expression and activity, though CAT expression increased with continuous training and GPX level diminished in both training groups, which coincided with the increase in GPX activity. Lipid damage decreased only in the continuous training group, while protein damage decreased only in the interval training group. Cytochrome C increased in both groups, while HIF-1 α dropped significantly after both exercise protocols. SIGNIFICANCE Significant improvement occurred in myocardium redox status in rats challenged with AMI after different training routines. However, continuous training seems to be more efficient in improving the parameters analyzed.

Redox-sensitive prosurvival and proapoptotic protein expression in the myocardial remodeling post-infarction in rats

In this study, we investigated the oxidative stress influence in some prosurvival and proapoptotic proteins after myocardial infarction (MI). Male Wistar rats were divided in two groups: Sham-operated (control) and MI. MI was induced by left coronary artery occlusion. 28-days after surgery, echocardiographic, morphometric, and hemodynamic parameters were evaluated. Redox status (reduced to oxidized glutathione ratio, GSH/GSSG) and hydrogen peroxide levels (H2O2) were measured in heart tissue. The p-ERK/ERK, p-Akt/Akt, p-mTOR/mTOR and p-GSK-3β/GSK-3β ratios, as well as apoptosis-inducing factor (AIF) myocardial protein expression were quantified by Western blot. MI group showed an increase in cardiac hypertrophy (23%) associated with a decrease in ejection fraction (38%) and increase in left ventricular end-diastolic pressure (82%) when compared to control, characterizing ventricular dysfunction. Redox status imbalance was seen in MI animals, as evidenced by the decrease in the GSH/GSSG ratio (30%) and increased levels of H2O2 (45%). This group also showed an increase in the ERK phosphorylation and a reduction of Akt and mTOR phosphorylation when compared to control. Moreover, we showed a reduction in the GSK-3β phosphorylation and an increase in AIF protein expression in MI group. Taken together, our results show increased H2O2 levels and cellular redox imbalance associated to a higher p-ERK and AIF immunocontent, which would contribute to a maladaptive hypertrophy phenotype.

Cardioprotective effects of thyroid hormones in a rat model of myocardial infarction are associated with oxidative stress reduction.

Reactive oxygen species (ROS) are involved with progression from infarction to heart failure. Studies show that thyroid hormones (TH) present cardioprotective effects. This study aims to evaluate whether TH effects after infarction are associated to redox balance modulation. Male Wistar rats were divided into four groups: Sham-operated (SHAM), infarcted (AMI), sham-operated+TH (SHAMT), and infarcted+TH (AMIT). During 26 days, animals received T3 (2 μg/100g/day) and T4 (8 μg/100g/day) by gavage. Echocardiographic parameters were assessed and heart tissue was collected to biochemical analysis. AMIT rats presented absence of lung congestion, less cardiac dilatation, and normalization in myocardial performance index, compared with AMI. AMI rats presented an increase in hydrogen peroxide levels and in lipid peroxidation and a decrease in GSH/GSSG. TH prevented these alterations in AMIT. In conclusion, TH seem to reduce the levels of ROS, preventing oxidative stress, and improving cardiac function in infarcted rats.

Time course of hydrogen peroxide–thioredoxin balance and its influence on the intracellular signalling in myocardial infarction

We investigated the myocardial thioredoxin‐1 and hydrogen peroxide concentrations and their association with some prosurvival and pro‐apoptotic proteins, during the transition from myocardial infarction (MI) to heart failure in rats. Male Wistar rats were divided into the following six groups: three sham‐operated groups and three MI groups, each at at 2, 7 and 28 days postsurgery. Cardiac function was analysed by echocardiography; the concentration of H2O2 and the ratio of reduced to oxidized glutathione were measured spectrophotometrically, while the myocardial immunocontent of thioredoxin‐1, angiotensin II, angiotensin II type 1 and type 2 receptors, p‐JNK/JNK, p‐ERK/ERK, p‐Akt/Akt, p‐mTOR/mTOR and p‐GSK3β/GSK3β was evaluated by Western blot. Our results show that thioredoxin‐1 appears to make an important contribution to the reduced H2O2 concentration. It was associated with lower JNK expression in the early period post‐MI (2 days). However, thioredoxin‐1 decreased, while renin–angiotensin system markers and levels of H2O2 increased, over 28 days post‐MI, in parallel with some signalling proteins involved in maladaptative cardiac remodelling and ventricular dysfunction. These findings provide insight into the time course profile of endogenous antioxidant adaptation to ischaemic injury, which may be useful for the design of therapeutical strategies targeting oxidative stress post‐MI.

Intraperitoneal implant of recombinant encapsulated cells overexpressing alpha- L -iduronidase partially corrects visceral pathology in mucopolysaccharidosis type I mice

BACKGROUND AIMS Mucopolysaccharidosis type I (MPS I) is characterized by deficiency of the enzyme alpha-L-iduronidase (IDUA) and storage of glycosaminoglycans (GAG) in several tissues. Current available treatments present limitations, thus the search for new therapies. Encapsulation of recombinant cells within polymeric structures combines gene and cell therapy and is a promising approach for treating MPS I. METHODS We produced alginate microcapsules containing baby hamster kidney (BHK) cells overexpressing IDUA and implanted these capsules in the peritoneum of MPS I mice. RESULTS An increase in serum and tissue IDUA activity was observed at early time-points, as well as a reduction in GAG storage; however, correction in the long term was only partially achieved, with a drop in the IDUA activity being observed a few weeks after the implant. Analysis of the capsules obtained from the peritoneum revealed inflammation and a pericapsular fibrotic process, which could be responsible for the reduction in IDUA levels observed in the long term. In addition, treated mice developed antibodies against the enzyme. CONCLUSIONS The results suggest that the encapsulation process is effective in the short term but improvements must be achieved in order to reduce the immune response and reach a stable correction.

Aerobic Exercise Promotes a Decrease in Right Ventricle Apoptotic Proteins in Experimental Cor Pulmonale.

Abstract: Pulmonary arterial hypertension is characterized by progressive increases in resistance and pressure in the pulmonary artery and Cor pulmonale. The effect of exercise on hydrogen peroxide–dependent signaling in the right ventricle (RV) of Cor pulmonale rats was analyzed. Rats were divided into sedentary control (SC), sedentary monocrotaline (SM), trained control (TC), and trained monocrotaline (TM) groups. Rats underwent exercise training (60% of VO2 max) for 5 weeks, with 3 weeks after monocrotaline injection (60 mg/kg intraperitoneally). Pulmonary resistance was enhanced in SM (2.0-fold) compared with SC. Pulmonary artery pressure was increased in SM (2.7-fold) and TM (2.6-fold) compared with their respective controls (SC and TC). RV hypertrophy indexes increased in SM compared with SC. Hydrogen peroxide was higher in SM (1.7-fold) than SC and was reduced by 47% in TM compared with SM. p-Akt was increased in TM (2.98-fold) compared with SM. The Bax/Bcl-2 ratio and caspase 3 were also increased (2.9-fold and 3.9-fold, respectively) in SM compared with SC. Caspase 3 was decreased in TM compared with SM (P < 0.05). Therefore, exercise training promoted a beneficial response by decreasing hydrogen peroxide concentrations, and consequently, apoptotic signaling in RV.

Association of the time course of pulmonary arterial hypertension with changes in oxidative stress in the left ventricle.

1. This study investigates the time course of pulmonary arterial hypertension (PAH) due to monocrotaline (MCT) and its association with cardiac function and oxidative stress markers in the left ventricle (LV).

Effects of purple grape juice in the redox-sensitive modulation of right ventricular remodeling in a pulmonary arterial hypertension model.

Abstract: The effects of purple grape juice (PGJ) pretreatment in signaling proteins involved in cardiac remodeling in rats with pulmonary arterial hypertension (PAH) induced by monocrotaline (MCT) were investigated. Male Wistar rats (control, MCT, PGJ, and MCT + PGJ groups) were treated for 6 weeks with water or PGJ (10 mL·kg−1·d−1) by gavage. In the third week, they were administered a single dose of MCT (60 mg/kg ip). Pulmonary vascular resistance was determined by echocardiography, and hemodynamic analysis was performed in the right ventricle (RV). Hydrogen peroxide (H2O2) concentration and lipid peroxidation were quantified and thioredoxin-1 (Trx-1), p-ERK1/2/ERK1/2, p-Akt/Akt, p-JNK/JNK, and cleaved caspase-3 were detected at RV by Western blot. Pretreatment with PGJ attenuated pulmonary vascular resistance and improved hemodynamic parameters in MCT-induced PAH. PGJ and MCT groups exhibited increased H2O2 levels, which were reduced to baseline in MCT + PGJ. ERK1/2 phosphorylation showed the same profile of H2O2 changes. No changes in p-JNK/JNK and p-Akt/Akt expressions were found. An enhanced cleaved caspase-3 immunodetection was induced by the model, which was reversed in the MCT + PGJ group and associated with increased Trx-1 and reduced lipid peroxidation. Improvement in functional parameters mediated by PGJ pretreatment may be associated with the induction of Trx-1, influencing the expression of proteins involved in RV remodeling.

Progressive heart disease in mucopolysaccharidosis type I mice may be mediated by increased cathepsin B activity

Mucopolysaccharidosis type I (MPS I) is a lysosomal disorder characterized by a deficiency of alpha-L-iduronidase and storage of undegraded glycosaminoglycans (GAGs). Clinical findings of the disease include heart failure, and patients often need valve replacement. It has been shown that, later in life, MPS I mice develop those abnormalities, but to date, there have not been studies on the progression and pathogenesis of the disease. Therefore, in the present study, we evaluated heart function in normal and MPS I male mice from 2 to 8 months of age. Echocardiographic analysis showed left ventricular enlargement with progressive reduction in ejection fraction, fractional area change, and left ventricular fractional shortening in the MPS I hearts at 6 and 8 months of age and a reduction in acceleration time/ejection time ratio of the pulmonary artery starting at 6 months of age, which suggests pulmonary vascular resistance. Histological and biochemical analysis confirmed progressive GAG storage from 2 months of age and onwards in the myocardium and heart valves, which had also increased in thickness. Additionally, macrophages were present in the MPS I heart tissue. Collagen content was reduced in the MPS I mouse valves. Cathepsin B, an enzyme that is known to be able to degrade collagen and is involved in heart dilatation, displayed a marked elevation in activity in the MPS I mice and could be responsible for the heart dilatation and valves alterations observed. Our results suggest that the MPS I mice have progressive heart failure and valve disease, which may be caused by cathepsin B overexpression.