The role of oxidative stress in the crosstalk between leptin and mineralocorticoid receptor in the cardiac fibrosis associated with obesity.

We have investigated whether mineralocorticoid receptor activation can participate in the profibrotic effects of leptin in cardiac myofibroblasts, as well as the potential mechanisms involved. The presence of eplerenone reduced the leptin-induced increase in protein levels of collagen I, transforming growth factor ß, connective tissue growth factor and galectin-3 and the levels of both total and mitochondrial of superoxide anion (O2.-) in cardiac myofibroblasts. Likewise, the MEK/ERK inhibitor, PD98059, and the PI3/Akt inhibitor, LY294002, showed a similar pattern. Mitochondrial reactive oxygen species (ROS) scavenger (MitoTempo) attenuated the increase in body weight observed in rats fed a high fat diet (HFD). No differences were found in cardiac function or blood pressure among any group. However, the cardiac fibrosis and enhanced O2.-levels observed in HFD rats were attenuated by MitoTempo, which also prevented the increased circulating leptin and aldosterone levels in HFD fed animals. This study supports a role of mineralocorticoid receptor in the cardiac fibrosis induced by leptin in the context of obesity and highlights the role of the mitochondrial ROS in this process.

Mitochondrial and nuclear DNA matching shapes metabolism and healthy ageing.

Human mitochondrial DNA (mtDNA) shows extensive within population sequence variability. Many studies suggest that mtDNA variants may be associated with ageing or diseases, although mechanistic evidence at the molecular level is lacking. Mitochondrial replacement has the potential to prevent transmission of disease-causing oocyte mtDNA. However, extension of this technology requires a comprehensive understanding of the physiological relevance of mtDNA sequence variability and its match with the nuclear-encoded mitochondrial genes. Studies in conplastic animals allow comparison of individuals with the same nuclear genome but different mtDNA variants, and have provided both supporting and refuting evidence that mtDNA variation influences organismal physiology. However, most of these studies did not confirm the conplastic status, focused on younger animals, and did not investigate the full range of physiological and phenotypic variability likely to be influenced by mitochondria. Here we systematically characterized conplastic mice throughout their lifespan using transcriptomic, proteomic,metabolomic, biochemical, physiological and phenotyping studies. We show that mtDNA haplotype profoundly influences mitochondrial proteostasis and reactive oxygen species generation,insulin signalling, obesity, and ageing parameters including telomere shortening and mitochondrial dysfunction, resulting in profound differences in health longevity between conplastic strains.

The lysyl oxidase inhibitor (ß-aminopropionitrile) reduces leptin profibrotic effects and ameliorates cardiovascular remodeling in diet-induced obesity in rats.

Lysyl oxidase (LOX) is an extracellular matrix (ECM)-modifying enzyme that has been involved in cardiovascular remodeling. We explore the impact of LOX inhibition in ECM alterations induced by obesity in the cardiovascular system. LOX is overexpressed in the heart and aorta from rats fed a high-fat diet (HFD). ß-Aminopropionitrile (BAPN), an inhibitor of LOX activity, significantly attenuated the increase in body weight and cardiac hypertrophy observed in HFD rats. No significant differences were found in cardiac function or blood pressure among any group. However, HFD rats showed cardiac and vascular fibrosis and enhanced levels of superoxide anion (O2(-)), collagen I and transforming growth factor ß (TGF-ß) in heart and aorta and connective tissue growth factor (CTGF) in aorta, effects that were attenuated by LOX inhibition. Interestingly, BAPN also prevented the increase in circulating leptin levels detected in HFD fed animals. Leptin increased protein levels of collagen I, TGF-ß and CTGF, Akt phosphorylation and O2(-) production in both cardiac myofibroblasts and vascular smooth muscle cells in culture, while LOX inhibition ameliorated these alterations. LOX knockdown also attenuated leptin-induced collagen I production in cardiovascular cells. Our findings indicate that LOX inhibition attenuates the fibrosis and the oxidative stress induced by a HFD on the cardiovascular system. The reduction of leptin levels by BAPN in vivo and the ability of this compound to inhibit leptin-induced profibrotic mediators and ROS production in cardiac and vascular cells suggest that interactions between leptin and LOX regulate downstream events responsible for myocardial and vascular fibrosis in obesity.

The lysyl oxidase inhibitor ß-aminopropionitrile reduces body weight gain and improves the metabolic profile in diet-induced obesity in rats.

Extracellular matrix (ECM) remodelling of the adipose tissue plays a pivotal role in the pathophysiology of obesity. The lysyl oxidase (LOX) family of amine oxidases, including LOX and LOX-like (LOXL) isoenzymes, controls ECM maturation, and upregulation of LOX activity is essential in fibrosis; however, its involvement in adipose tissue dysfunction in obesity is unclear. In this study, we observed that LOX is the main isoenzyme expressed in human adipose tissue and that its expression is strongly upregulated in samples from obese individuals that had been referred to bariatric surgery. LOX expression was also induced in the adipose tissue from male Wistar rats fed a high-fat diet (HFD). Interestingly, treatment with ß-aminopropionitrile (BAPN), a specific and irreversible inhibitor of LOX activity, attenuated the increase in body weight and fat mass that was observed in obese animals and shifted adipocyte size toward smaller adipocytes. BAPN also ameliorated the increase in collagen content that was observed in adipose tissue from obese animals and improved several metabolic parameters - it ameliorated glucose and insulin levels, decreased homeostasis model assessment (HOMA) index and reduced plasma triglyceride levels. Furthermore, in white adipose tissue from obese animals, BAPN prevented the downregulation of adiponectin and glucose transporter 4 (GLUT4), as well as the increase in suppressor of cytokine signaling 3 (SOCS3) and dipeptidyl peptidase 4 (DPP4) levels, triggered by the HFD. Likewise, in the TNFα-induced insulin-resistant 3T3-L1 adipocyte model, BAPN prevented the downregulation of adiponectin and GLUT4 and the increase in SOCS3 levels, and consequently normalised insulin-stimulated glucose uptake. Therefore, our data provide evidence that LOX plays a pathologically relevant role in the metabolic dysfunction induced by obesity and emphasise the interest of novel pharmacological interventions that target adipose tissue fibrosis and LOX activity for the clinical management of this disease.

Interleukin-33/ST2 system attenuates aldosterone-induced adipogenesis and inflammation.

Interleukin-33 (IL-33) but not soluble ST2 (sST2) exerts anti-inflammatory and protective effects in several tissues. Aldosterone, a proinflammatory mediator which promotes adipogenesis, is elevated in obese patients. The aim of this study was to investigate the interactions between IL-33/ST2 system and Aldosterone in adipose tissue. Rats fed a high fat diet presented increased sST2 expression, diminished IL-33/sST2 ratio and enhanced levels of differentiation and inflammation in adipose tissue as compared to controls. A similar pattern was observed in adipose tissue from C57BL/6 Aldosterone-treated mice. In both animal models, Aldosterone was correlated with sST2. Treatment of 3T3-L1 adipocytes with IL-33 delayed adipocyte differentiation diminished lipid accumulation and decreased inflammation. Aldosterone decreased IL-33 and increased sST2 expressions in differentiated adipocytes. Aldosterone-induced adipocyte differentiation and inflammation were blocked by IL-33 treatment, but sST2 did not exert any effects. The crosstalk between IL-33/ST2 and Aldosterone could be relevant in the metabolic consequences of obesity.

The impact of galectin-3 inhibition on aldosterone-induced cardiac and renal injuries.

OBJECTIVES: This study investigated whether galectin (Gal)-3 inhibition could block aldosterone-induced cardiac and renal fibrosis and improve cardiorenal dysfunction. BACKGROUND: Aldosterone is involved in cardiac and renal fibrosis that is associated with the development of cardiorenal injury. However, the mechanisms of these interactions remain unclear. Gal-3, a ß-galactoside-binding lectin, is increased in heart failure and kidney injury. METHODS: Rats were treated with aldosterone-salt combined with spironolactone (a mineralocorticoid receptor antagonist) or modified citrus pectin (a Gal-3 inhibitor), for 3 weeks. Wild-type and Gal-3 knockout mice were treated with aldosterone for 3 weeks. Hemodynamic, cardiac, and renal parameters were analyzed. RESULTS: Hypertensive aldosterone-salt-treated rats presented cardiac and renal hypertrophy (at morphometric, cellular, and molecular levels) and dysfunction. Cardiac and renal expressions of Gal-3 as well as levels of molecular markers attesting fibrosis were also augmented by aldosterone-salt treatment. Spironolactone or modified citrus pectin treatment reversed all of these effects. In wild-type mice, aldosterone did not alter blood pressure levels but increased cardiac and renal Gal-3 expression, fibrosis, and renal epithelial-mesenchymal transition. Gal-3 knockout mice were resistant to aldosterone effects. CONCLUSIONS: In experimental hyperaldosteronism, the increase in Gal-3 expression was associated with cardiac and renal fibrosis and dysfunction but was prevented by pharmacological inhibition (modified citrus pectin) or genetic disruption of Gal-3. These data suggest a key role for Gal-3 in cardiorenal remodeling and dysfunction induced by aldosterone. Gal-3 could be used as a new biotarget for specific pharmacological interventions.

Leptin induces cardiac fibrosis through galectin-3, mTOR and oxidative stress: potential role in obesity.

OBJECTIVE: Leptin acts as a cardiac profibrotic factor. However, the mechanisms underlying this effect are unclear. Therefore, we sought to elucidate the mediators involved in this process and the potential role of leptin in cardiac fibrosis associated with obesity. METHODS: Male Wistar rats were fed either a high-fat diet (HFD; 33.5% fat), or a standard diet (3.5% fat) for 6 weeks. RESULTS: HFD animals show cardiac hypertrophy, fibrosis and an increase in O2- production as evaluated by dihydroethidium. Echocardiographic parameters of cardiac structure and systolic function were similar in both groups. Cardiac levels of leptin, collagen I, galectin-3 and transforming growth factor ß (TGF-ß) were higher in HFD than in controls. In cardiac myofibroblasts, leptin (10-100 ng/ml) increased O2-, collagen I, galectin-3, TGF-ß and connective tissue growth factor production (CTGF). These effects were prevented by the presence of either melatonin (10 mmol/l) or the inhibitor of mTOR, rapamycin (10 mmol/l). Blockage of galectin-3 activity by N-acetyllactosamine (LacNac 10 mmol/l) reduced both collagen I and O2(*-) production induced by leptin. The p70S6 kinase activation/phosphorylation, the downstream mediator of mTOR, induced by leptin was not modified by melatonin. Leptin reduced the metalloproteinase (MMP) 2 activity and the presence of melatonin, rapamycin or LacNac were unable to prevent it. CONCLUSION: The data suggest that leptin locally produced in the heart could participate in the fibrosis observed in HFD by affecting collagen turnover. Collagen synthesis induced by leptin seems to be mediated by the production of galectin-3, TGF-ß and CTGF through oxidative stress increased by activation of mTOR pathway.

A role for soluble ST2 in vascular remodeling associated with obesity in rats.

BACKGROUND: The function of the Interleukin-33 (IL-33)/ST2 system has been mainly investigated on immunological aspects, but recent data suggest that this pathway plays also an important role in cardiovascular system and adipose tissue. Whereas IL-33 has been demonstrated to exert anti-inflammatory and protective effects, circulating soluble ST2 (sST2) has emerged as a prognostic biomarker in patients with myocardial infarction and heart failure. Furthermore, sST2 is increased in severe obesity, although its role in the pathogenesis of vascular remodeling associated with obesity is still not well defined. METHODOLOGY/PRINCIPAL FINDINGS: Male Wistar rats fed standard diet (Control) or high fat diet (HFD) for 6 weeks. Aortic tunica media from diet-induced obese animals showed hypertrophy and fibrosis. The IL-33/ST2 system was spontaneously expressed in the aorta from Wistar rats. Administration of HFD in animals did not modify IL-33 expression at the transcriptional level. By contrast, HFD group showed an increase in aortic soluble sST2 and a decrease in the transmembrane isoform (ST2L) levels, resulting in decreased protective pathway activity. Aortic sST2 mRNA levels were associated with parameters showing vascular hypertrophy and fibrosis. In vitro experiments showed that primary cultured vascular smooth muscle cells (VSMCs) spontaneously expressed the IL-33/ST2 system. VSMCs stimulated with sST2 showed an increase in collagen type I, fibronectin and profibrotic factors. CONCLUSIONS: This is the first study demonstrating a deleterious role for sST2 in the vascular remodeling associated with obesity. In addition, we demonstrated that sST2 may act not only as a decoy receptor by binding IL-33 and preventing ST2L, but also modulating ECM remodeling and turnover. Thus, sST2 could be a new therapeutic target to reduce vascular remodeling in the context of obesity.

Left and right ventricle late remodeling following myocardial infarction in rats.

BACKGROUND: The mechanisms involved in cardiac remodeling in left (LV) and right ventricles (RV) after myocardial infarction (MI) are still unclear. We assayed factors involved in collagen turnover in both ventricles following MI in rats either presenting signs of heart failure (pulmonary congestion and increased LVEDP) or not (INF-HF or INF, respectively). METHODS: MI was induced in male rats by ligation of the left coronary artery. Four weeks after MI gene expression of collagen I, connective tissue growth factor (CTGF), transforming growth factor ß (TGF-ß) and lysyl oxidase (LOX), metalloproteinase-2 (MMP2) and tissue inhibitor metalloproteinase-2 (TIMP2) as well as cardiac hemodynamic in both ventricles were evaluated. RESULTS: Ventricular dilatation, hypertrophy and an increase in interstitial fibrosis and myocyte size were observed in the RV and LV from INF-HF animals, whereas only LV dilatation and fibrosis in RV was present in INF. The LV fibrosis in INF-HF was associated with higher mRNA of collagen I, CTGF, TGF-ß and LOX expressions than in INF and SHAM animals, while MMP2/TIMP2 mRNA ratio did not change. RV fibrosis in INF and INF-HF groups was associated with an increase in LOX mRNA and a reduction in MMP2/TIMP2 ratio. CTGF mRNA was increased only in the INF-HF group. CONCLUSIONS: INF and INF-HF animals presented different patterns of remodeling in both ventricles. In the INF-HF group, fibrosis seems to be consequence of collagen production in LV, and by reductions in collagen degradation in RV of both INF and INF-HF animals.

Galectin-3 mediates aldosterone-induced vascular fibrosis.

OBJECTIVE: Aldosterone (Aldo) is involved in arterial stiffness and heart failure, but the mechanisms have remained unclear. Galectin-3 (Gal-3), a ß-galactoside-binding lectin, plays an important role in inflammation, fibrosis, and heart failure. We investigated here whether Gal-3 is involved in Aldo-induced vascular fibrosis. METHODS AND RESULTS: In rat vascular smooth muscle cells Gal-3 overexpression enhanced specifically collagen type I synthesis. Moreover Gal-3 inhibition by modified citrus pectin or small interfering RNA blocked Aldo-induced collagen type I synthesis. Rats were treated with Aldo-salt combined with spironolactone or modified citrus pectin for 3 weeks. Hypertensive Aldo-treated rats presented vascular hypertrophy, inflammation, fibrosis, and increased aortic Gal-3 expression. Spironolactone or modified citrus pectin treatment reversed all the above effects. Wild-type and Gal-3 knock-out mice were treated with Aldo for 6 hours or 3 weeks. Aldo increased aortic Gal-3 expression, inflammation, and collagen type I in wild-type mice at both the short- and the long-term, whereas no changes occurred in Gal-3 knock-out mice. CONCLUSIONS: Our data indicate that Gal-3 is required for inflammatory and fibrotic responses to Aldo in vascular smooth muscle cells in vitro and in vivo, suggesting a key role for Gal-3 in vascular fibrosis.

The impact of bariatric surgery on renal and cardiac functions in morbidly obese patients.

BACKGROUND: Cardiac adaptation to obesity includes both structural and functional alterations in the heart. The kidneys also suffer the consequence of excessive increase of body weight. This study aims to assess the functional, cardiac and renal changes in a cohort of morbidly obese patients, as well as changes after bariatric surgery-the last therapeutic option for these patients. METHODS: Patients referred for bariatric surgery were prospectively included. In each case, transthoracic echocardiography and a blood test were performed before the procedure and repeated 1 year after surgery. The estimation of the glomerular filtration rate (GFR) was addressed by the Cockroft-Gault lean body weight formula. RESULTS: Sixty-one patients completed the 1-year follow-up. Of these, 81.9% were female. The mean age was 41.1 ± 9.8 years and the mean body mass index was 47.4 ± 5 kg/m(2), decreasing to 30.5 ± 5.07 kg/m(2) after the procedure. Before surgery, the estimated GFR was 92.7 ± 25.4 mL/min, with hyperfiltration being present in 14.8% of patients, whereas an impaired GFR was detected in 8.3%. Patients showed preserved systolic function and cardiac remodelling. Diastolic function was abnormal in 27.9% of patients. At the 1-year follow-up, favourable changes in the left ventricular geometry and related haemodynamic status were observed. There was no significant change in the estimated GFR in the overall group, although hyperfiltration was ameliorated in 9.8% and a poor GFR was improved in 3.3.%. The improvement was not associated with changes in either blood pressure or the BMI. However, in this group of patients the amelioration of the GFR was associated with an increased stroke volume and improvement in diastolic function. CONCLUSIONS: In morbidly obese patients, GFR is usually normal and only a small percentage of them show hyperfiltration or a reduced GFR. Bariatric surgery has a favourable impact on renal function in only a reduced group of patients who also experience an improvement in cardiac performance.

Ezetimibe inhibits PMA-induced monocyte/macrophage differentiation by altering microRNA expression: a novel anti-atherosclerotic mechanism.

Ezetimibe, a selective inhibitor of intestinal cholesterol absorption, effectively reduces plasma cholesterol both in monotherapy or combined with a statin. However, its effect on atherosclerosis plaque progression is certainly unknown. MicroRNAs are short non-encoding RNA molecules dynamically implicated in monocytic differentiation which is considered an essential process during atherosclerosis development. The purpose of this study was to investigate the effect of ezetimibe on monocyte/macrophage differentiation as well as the implication of microRNAs (miRNAs) in this process. THP-1 differentiation with PMA became cells adherent to the plastic surface, and induced the expression of macrophage surface markers (CD11a, CD11b and ICAM-1) and miR-155, miR-222, miR-424 and miR-503. In the presence of ezetimibe, the adhesive capacity of THP-1 cells was decreased in a dose-dependent manner (P<0.05) and the expression of CD11a, CD11b and ICAM-1 was almost totally inhibited (P<0.05). The expression of miR-155, miR-222, miR-424 and miR-503 was reduced by 55%, 100%, 75% and 100%, respectively (P<0.05). Further mechanistic studies demonstrated that ezetimibe suppressed the PMA-induced phosphorylation of ERK/MAPK and inhibited the NF-κB activity, which are upstream signalling molecules in the differentiation process. In conclusion, ezetimibe inhibits PMA-induced THP-1 cell differentiation into macrophage-like cells in association with the inhibition of miRNA pathways. Our study suggests that inhibition of miRNAs might form a novel mechanism of anti-atherosclerotic effect of ezetimibe.

DIOL triterpenes block profibrotic effects of angiotensin II and protect from cardiac hypertrophy.

BACKGROUND: The natural triterpenes, erythrodiol and uvaol, exert anti-inflammatory, vasorelaxing and anti-proliferative effects. Angiotensin II is a well-known profibrotic and proliferative agent that participates in the cardiac remodeling associated with different pathological situations through the stimulation and proliferation of cardiac fibroblasts. Therefore, the aim of the study was to investigate the preventive effects of the natural triterpenes erythrodiol and uvaol on the proliferation and collagen production induced by angiotensin II in cardiac myofibroblasts. Their actions on cardiac hypertrophy triggered by angiotensin II were also studied. METHODOLOGY/PRINCIPAL FINDINGS: The effect of erythrodiol and uvaol on angiotensin II-induced proliferation was evaluated in cardiac myofibroblasts from adult rats in the presence or the absence of the inhibitors of PPAR-γ, GW9662 or JNK, SP600125. The effect on collagen levels induced by angiotensin II was evaluated in cardiac myofibroblasts and mouse heart. The presence of low doses of both triterpenes reduced the proliferation of cardiac myofibroblasts induced by angiotensin II. Pretreatment with GW9662 reversed the effect elicited by both triterpenes while SP600125 did not modify it. Both triterpenes at high doses produced an increase in annexing-V binding in the presence or absence of angiotensin II, which was reduced by either SP600125 or GW9662. Erythrodiol and uvaol decreased collagen I and galectin 3 levels induced by angiotensin II in cardiac myofribroblasts. Finally, cardiac hypertrophy, ventricular remodeling, fibrosis, and increases in myocyte area and brain natriuretic peptide levels observed in angiotensin II-infused mice were reduced in triterpene-treated animals. CONCLUSIONS/SIGNIFICANCE: Erythrodiol and uvaol reduce cardiac hypertrophy and left ventricle remodeling induced by angiotensin II in mice by diminishing fibrosis and myocyte area. They also modulate growth and survival of cardiac myofibroblasts. They inhibit the angiotensin II-induced proliferation in a PPAR-γ-dependent manner, while at high doses they activate pathways of programmed cell death that are dependent on JNK and PPAR-γ.

A wound-like inflammatory aortic response in chronic portal hypertensive rats.

Long-term prehepatic portal hypertension in the rat produces a low-grade splanchnic inflammation with liver steatosis and dyslipidemia. It has been suggested that in this experimental model these inflammatory alterations could represent a risk factor of vascular disease. Therefore, our aim was to investigate whether long-term prehepatic portal hypertension (PH) induces vascular pathology, fundamentally inflammatory aortopathy. Male Wistar sham-operated (SO) rats and rats with triple partial portal vein ligation in the very long-term (22 months) of postoperative evolution were used. Serum lipid profile, pro- and anti- inflammatory cytokines and ACTH and corticosterone were assayed by spectrophotometric and ELISA techniques. Aorta mRNA expression of oxidative and nitrosative stress enzymes, NFκB e IκB, immune-related cytokine production and vascular fibrosis parameters, were evaluated by real time RT-PCR. In addition, aortic p22phox subunit immunostaining, morphometry and vascular fibrosis in aorta were analyzed. PH rats have increased serum cholesterol, triglyceride, low-density lipoproteins (LDL) and very low-density lipoproteins (VLDL), while high-density lipoproteins (HDL) were lower than in SO rats. Serum ACTH and corticosterone decreased in PH rats. Also, serum TNF-α, IL-1ß and IL-6 were significantly higher in PH-rats. Portal hypertensive-rats showed aortic oxidative stress with increased mRNA expressions of NAD(P)H oxidase p22phox, XDh, SOD and eNOS; higher aortic levels of pro-inflammatory cytokines, including TNF-α, IL-1ß and IL-6; remodeling markers, like collagen I, CTGF and MMP-9; and finally, higher protein production of p22phox and collagen and extracellular matrix density were significantly higher in rats with PH. The results from the current study suggest that very long-term prehepatic portal hypertension in rats induces an abdominal aortic inflammatory and fibrotic response. Therefore, it could be considered that portal hypertension aggravates aortic inflammaging and one of its more severe complications, which is remodeling by a wound healing reaction.

Papel de la angiotensina II en el proceso aterosclerótico / Role of angiotensin II in the development of atherosclerosis

La angiotensina II, el péptido efector del sistema renina-angiotensina, está implicado en la patogénesis de la aterosclerosis a distintos niveles. Existen numerosas evidencias experimentales que demuestran que tanto la inhibición de la síntesis de angiotensina II mediante la administración de inhibidores de la enzima de conversión de la angiotensina II como mediante el empleo de antagonistas de su receptor AT1 inhiben la formación y la progresión de la lesión aterosclerótica. La angiotensina II es capaz de estimular la producción de especies reactivas de oxígeno en el vaso que desempeñan un papel clave en la disfunción endotelial y en la oxidación de las lipoproteínas de baja densidad (LDL). Asimismo, la angiotensina II participa en la inducción de la respuesta inflamatoria en la pared vascular mediante la producción de moléculas de adhesión y citoquinas quimiotácticas y proinflamatorias. Este péptido estimula la proliferación y la migración de células de músculo liso y modula su cambio fenotípico, dando lugar a un aumento en la síntesis de la matriz extracelular. Finalmente, la angiotensina II también participa en las complicaciones de la aterosclerosis al favorecer la ruptura de la placa y la trombogenicidad de la misma. Por tanto, la angiotensina II juega un papel importante tanto en el inicio del proceso al favorecer la disfunción endotelial, en la progresión de la lesión ateromatosa, en la ruptura de la placa y en la aparición de accidentes trombóticos (AU)

Angiotensin II, the effector peptide of the renin-angiotensin system, may be involved in various factors affecting the pathogenesis of atherosclerosis. There is abundant experimental evidence that both pharmacological antagonism of angiotensin II formation by angiotensin converting enzyme inhibition and blockade of angiotensin II by angiotensin type I receptor blockade inhibits the formation and progression of atherosclerotic lesions. Angiotensin II is able to stimulate the production of reactive oxygen species in blood vessels, which play a key role in endothelial dysfunction and oxidation of low-density lipoproteins. In addition, angiotensin II participates in the induction of the inflammatory response in the vascular wall through the production of adhesion molecules and chemotaxic and proinflammatory cytokines. This peptide stimulates the proliferation and migration of smooth muscle cells and modulates phenotypic changes in these cells, thus increasing the synthesis of extracellular matrix. Finally, angiotensin II also contributes to the complications of atherosclerosis by favoring plaque rupture and thrombogenicity. Therefore, angiotensin II plays an important role both in the beginning of the process -promoting endothelial dysfunction- in atherosclerotic lesion progression, in plaque rupture, and in the occurrence of thrombotic accidents (AU)

Spironolactone prevents alterations associated with cardiac hypertrophy produced by isoproterenol in rats: involvement of serum- and glucocorticoid-regulated kinase type 1.

Persistent ß-adrenergic receptor stimulation with isoproterenol is associated with cardiac hypertrophy as well as cardiac synthesis of angiotensin II. Serum- and glucocorticoid-regulated kinase type 1 (SGK-1) is a key mediator in structural, functional and molecular cardiac effects of aldosterone in rats. This study was designed to investigate the cardiac effects of the mineralocorticoid receptor antagonist spironolactone on the response to isoproterenol treatment in rats, as well as the involvement of the main mediator of cellular aldosterone action, SGK-1, in the heart. Male Wistar rats received isoproterenol (3 mg kg(-1) day(-1)) or vehicle for 15 days. Half of the animals in each group were simultaneously treated with spironolactone (200 mg kg(-1) day(-1)). Systolic and diastolic blood pressures were not significantly different among groups. Treatment with spironolactone normalized the increased left ventricular end-diastolic pressure observed in isoproterenol-treated rats. Isoproterenol treatment induced cardiac hypertrophy and increased collagen content, both of which were normalized by spironolactone treatment. The mRNA levels of transforming growth factor ß, connective tissue growth factor, matrix metalloprotease 2, matrix metalloprotease inhibitor 2, tumour necrosis factor α, interleukin 1ß, p22phox and xanthine dehydrogenase were increased (P < 0.05) in isoproterenol-treated rats, and this effect was prevented by spironolactone (P < 0.05). Spironolactone also reduced the elevated SGK-1 expression in isoproterenol-treated rats. The observed reduction of the principal mediator of aldosterone cellular actions, SGK-1, by spironolactone in hearts from isoproterenol-treated rats suggests a role of mineralocorticoids in the cardiac hypertrophy, fibrosis, inflammation, oxidation and diastolic dysfunction induced by isoproterenol treatment in rats.

The effects of adiponectin and leptin on human endothelial cell proliferation: a live-cell study.

The effect of adiponectin and leptin on the proliferation of the human microvascular endothelial cell line (HMEC-1) was studied in the absence or presence of fetal bovine serum (FBS). The participation of extracellular signal-regulated kinase (ERK) and phosphatidylinositol 3-kinase/Akt (PI-3K/Akt) pathways in this effect were evaluated. We studied the effect of both adipokines on the motility, mitosis, proliferation and cell death processes of HMEC-1 cells using live-cell imaging techniques. Adiponectin but not leptin further increased the proliferative effect induced by FBS on HMEC-1. This effect seems to be the consequence of an increase in the mitotic index in adiponectin-treated cells when compared to untreated ones. The presence of either the mitogen-activated protein kinase (MAPK) inhibitor (PD98059), or PI-3K inhibitor (LY294002), reduced the effect of adiponectin in a dose-dependent manner. Neither adipokine was able to affect HMEC-1 proliferation in FBS-free conditions. Duration of mitosis, cell motility and the cell death process were similar in all conditions. These data suggest that adiponectin and leptin exert different effects on endothelial cell function. Adiponectin was able to potentiate proliferation of HMEC-1. This effect involves the activation of both PI3-K/Akt and ERK/MAPK pathways. However, it seems to exert minimal effects on HMEC-1 function in the case of leptin.

Cardiac benefits of exercise training in aging spontaneously hypertensive rats.

OBJECTIVE: To evaluate the effect of low-intensity chronic exercise training (ExT) on blood pressure (BP), as well as the cardiac alterations associated with hypertension in aging hypertensive rats. METHODS: Male spontaneously hypertensive rats (SHR; 21 months old) and their normotensive control Wistar-Kyoto (WKY) rats were submitted to low-intensity training protocol for 13 weeks. BP, cardiac morphological and morphometric analysis, as well as gene expression of fibrotic and inflammatory factors were analyzed at the end of the training period. RESULTS: ExT reduced BP and heart rate in aged SHR. Left ventricle hypertrophy, collagen volume fraction and wall-to-lumen ratio of myocardium arterioles were also decreased in trained SHR. However, ExT was unable to reverse the either reduced capillary density or the cardiac myocyte hypertrophy observed in SHR as compared with WKY rats. Trained SHR showed higher metalloproteinase-2/tissue inhibitor metalloproteinase-2 (MMP-2/TIMP-2) ratio and lower levels of α-smooth muscle actin, but similar levels of connective tissue growth factor, transforming growth factor beta or IL-1 beta to that of nontrained SHR. CONCLUSION: Low to moderate-intensity chronic ExT reverses the cardiac alterations associated with hypertension: myocardial arteriole, left ventricle hypertrophy, collagen content and tachycardia. These changes could be consequence or cause of the reduction in BP observed in trained SHR. In addition, ExT does not worsen the underlying inflammatory burden associated with hypertension. Therefore, the data support a beneficial effect of ExT in aging SHR similar to that reported in young or middle-aged individuals, confirming that exercise is a healthy habit that induces cardiac improvements independently of age.

Efecto del tratamiento con candesartan sobre los mecanismos y factores implicados en el desarrollo de la enfermedad cardiovascular asociada a sobrepeso y exceso de tejido adiposo visceral en la rata / Effect of candesartan therapy on mechanisms and factors involved in the development of cardiovascular disease associated with overweight and excess visceral adipose tissue in rats

Objetivo: El sistema renina-angiotensina participa en el desarrollo del síndrome metabólico. El presente trabajo tiene como objetivo evaluar el papel que juega la angiotensina ii en las alteraciones metabólicas y vasculares asociadas a esta patología en un modelo de obesidad inducida por la dieta. Métodos: El estudio se llevó a cabo en ratas Sprague Dawley divididas en tres grupos: 1) ratas alimentadas con dieta estándar utilizadas como grupo control; 2) ratas alimentadas con una dieta con alto contenido en grasas (SBP) (33,5% del contenido calórico), y 3) ratas en las mismas condiciones que el grupo 2 a las que se les administró un antagonista de receptores AT1 de angiotensina ii (candesartan) (2 mg/kg/día). El periodo de evolución fue de 7 semanas. Se evaluó el peso corporal, el tejido adiposo blanco y marrón, las concentraciones plasmáticas y los niveles proteicos en tejido adiposo blanco de leptina y adiponectina, así como el metabolismo glucídico y lipídico. Resultados: Las ratas alimentadas con dieta grasa experimentaron un aumento del peso corporalasí como de tejido adiposo epididimal y lumbar. El candesartan atenuó todos estos valores. La alteración del balance leptina/adiponectina, así como el aumento en la expresión proteica de estas adipocinas, se normalizaron tras el tratamiento con candesartan, que también mejoró la sensibilidad a la insulina y el perfil lipídico. Conclusión: La corrección del balance leptina/adiponectina podría ser uno de los mecanismos a través de los cuales el candesartan ejerce su efecto protector en ratas alimentadas con dieta grasa (AU)

Objective: The rennin angiotensin system has been shown to participate in the development of metabolic syndrome. The aim of this study was to determine whether the angiotens in ii type 1 receptor blocker, candesartan, exerts a protective effect against metabolic and vascular abnormalities in rats fed a high fat diet (HFD).Methods: Sprague Dawley rats (n = 30) were divided into three groups: 1) rats fed a standard diet for 7 weeks, used as a control group; 2) rats fed a HFD (33.5% fat) for 7 weeks; and 3) rats fed a HFD (33.5% fat) treated with candesartan (2 mg/kg/day) for 7 weeks. Body weight, white and brown adipose tissue weight, plasma concentrations and protein expression of leptin andadiponectin in white adipose tissue, glucose and lipid metabolism were investigated. Results: HFD rats showed increased body, epididymal and lumbar adipose tissue (..) (AU)