Free radicals act as secondary messengers, modulating a number of important biological processes, including gene expression, ion mobilization in transport systems, protein interactions and enzymatic functions, cell growth, cell cycle, redox homeostasis, among others. In the cardiovascular system, the physiological generation of free radicals ensures the integrity and function of cardiomyocytes, endothelial cells, and adjacent smooth muscle cells. In physiological conditions, there is a balance between free radicals generation and the activity of enzymatic and non-enzymatic antioxidant systems. Redox imbalance, caused by increased free radical’s production and/or reduced antioxidant defense, plays an important role in the development of cardiovascular diseases, contributing to cardiac hypertrophy and heart failure, endothelial dysfunction, hypertrophy and hypercontractility of vascular smooth muscle. Excessive production of oxidizing agents in detriment of antioxidant defenses in the cardiovascular system has been described in obesity, diabetes mellitus, hypertension, and atherosclerosis. The transcription factor Nrf2 (nuclear factor erythroid 2–related factor 2), a major regulator of antioxidant and cellular protective genes, is primarily activated in response to oxidative stress. Under physiological conditions, Nrf2 is constitutively expressed in the cytoplasm of cells and is usually associated with Keap-1, a repressor protein. This association maintains low levels of free Nrf2. Stressors, such as free radicals, favor the translocation of Nrf2 to the cell nucleus. The accumulation of nuclear Nrf2 allows the binding of this protein to the antioxidant response element of genes that code antioxidant proteins. Although little information on the role of Nrf2 in the cardiovascular system is available, growing evidence indicates that decreased Nrf2 activity contributes to oxidative stress, favoring the pathophysiology of cardiovascular disorders found in obesity, diabetes mellitus, and atherosclerosis. The present mini-review will provide a comprehensive overview of the role of Nrf2 as a contributing factor to cardiovascular risk in metabolic diseases.

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Aldosterone excess aggravates endothelial dysfunction in diabetes and hypertension by promoting the increased generation of reactive oxygen species, inflammation, and insulin resistance. Aldosterone activates the molecular platform inflammasome in immune system cells and contributes to vascular dysfunction induced by the mineralocorticoid hormone. It is unclear as to whether the NLRP3 inflammasome associated with the mineralocorticoid receptor contributes to vascular dysfunction in diabetic conditions. Here, we tested the hypothesis that an excess of aldosterone induces vascular dysfunction in type 2 diabetes, via the activation of mineralocorticoid receptors (MR) and assembly of the NLRP3 inflammasome. Mesenteric resistance arteries from control (db/m) and diabetic (db/db) mice treated with vehicle, spironolactone (MR antagonist) or an NLRP3 selective inhibitor (MCC950) were used to determine whether NLRP3 contributes to diabetes-associated vascular dysfunction. Db/db mice exhibited increased vascular expression/activation of caspase-1 and IL-1β, increased plasma IL-1β levels, active caspase-1 in peritoneal macrophages, and reduced acetylcholine (ACh) vasodilation, compared to db/m mice. Treatment of db/db mice with spironolactone and MCC950 decreased plasma IL-1β and partly restored ACh vasodilation. Spironolactone also reduced active caspase-1-positive macrophages in db/db mice, events that contribute to diabetes-associated vascular changes. These data clearly indicate that MR and NLRP3 activation contribute to diabetes-associated vascular dysfunction and pro-inflammatory phenotype.

Introduction NLRP3 inflammasome is a molecular platform of innate immune system that regulates the inflammatory response through the activation of caspase‐1 and IL‐1β. It can be activated by several ligands, for example, mitochondrial DNA (mDNA). Some studies have shown that circulating mDNA is increased in patients with diabetes and play a role in the development of the disease; however, its role in vascular changes is still unknown. In this sense, we tested the hypothesis that mDNA contributes to vascular inflammatory/oxidative processes associated to type 1 diabetes (T1D) via NLRP3 inflammasome activation. Methods Wild‐type and NLRP3‐deficient (NLRP3−/−) mice were treated with vehicle (Veh) or streptozotocin (40 mg/kg) (T1D) for 5 days. Vascular reactivity was determined in mesenteric arteries. Caspase‐1 and IL‐1β expression were evaluated by western blot. Pancreatic mDNA was extracted from control (cmDNA) and diabetic animals (dmDNA) for endothelial cells stimulation. ROS generation was determined by chemiluminescence. Hydrogen peroxide (H2O2) production and calcium influx were determined by fluorescence. Data are presented as mean ± standard error of the mean. Results Diabetes increased vascular caspase‐1 and IL‐1β activation [arbitrary units (a.u.), 1.2±0.1 vs. 0.8±0.1; 4.8±1.1 vs. 0.8±0.5 vs. the Veh, respectively, p <0.05]. However, this activation was attenuated in T1D NLRP3−/−. Mesenteric arteries from T1D exhibited decreased ACh‐induced vasodilatation vs. Veh [(Emax), 46.6±4.0 vs. 91.5±2.8, n=4–5, p<0.05], which was not observed in T1D NLRP3−/−. The NLRP3 inhibitor MCC950 acutely improved endothelium‐dependent vasodilation in T1D [(Emax), 62.5±3.8 vs. 85.6±3.7, n=4–5, p<0.05]. ROS generation [(Relative luminescence unit, RLU), 1.5×107±2.3 vs. 48.9×103±1.1, n=4–5, p<0.05] as well as H2O2 production [(Relative fluorescence unit, RFU), 1082±242.6 vs. 232.0±42.8, n=4–5, p<0.05] were lower in mesenteric bed from T1D NLRP3−/− than T1D. Only incubation with dmDNA reduced ACh‐induced vasodilation [(Emax), 48.4 ± 4.1 vs. 90.7 ± 3.4, n=4–5, p<0.05], which was attenuated by the presence of an antioxidant [(Emax), 48.4 ± 4.1 vs. 71.5 ± 3.1, n=4–5, p<0.05]. Similarly, only LPS‐primed cells incubated with dmDNA had significant NLRP3 activation (caspase‐1 and IL‐1β activation, respectively) [(u.a.), 1.6 ± 0.2 vs. 0.9 ± 0.1; and 1.6 ± 0.2 vs. 1.0 ± 0.1, n=4–5, p<0.05]. The dmDNA induced in a time‐dependent way both calcium influx and ROS generation in endothelial cells, being the last reversed by the presence of an antioxidant. Likewise, T1D patients had increased circulating mDNA vs. healthy volunteers and also higher NLRP3 serum expression, and caspase‐1/IL‐1β activation. Conclusion The T1D increases mDNA release which in turn stimulates increased calcium influx, induces ROS generation, and triggers vascular NLRP3 inflammasome activation contributing to inflammatory response and endothelial dysfunction in diabetes. Support or Funding Information Financial Support: FAPESP and CAPES. Ethics Committee number (026/2015)...

Background: The understanding of obsesity-related vascular dysfunction remains controversial mainly because of the diseases associated with vascular injury. Exercise training is known to prevent vascular dysfunction. Using an obesity model without comorbidities, we aimed at investigating the underlying mechanism of vascular dysfunction and how exercise interferes with this process.Methods: High-sugar diet was used to induce obesity in mice. Exercise training was performed 5 days/week. Body weight, energy intake, and adipose tissues were assessed; blood metabolic and hormonal parameters were determined; and serum TNFα was measured. Blood pressure and heart rate were assessed by plethysmography. Changes in aortic isometric tension were recorded on myograph. Western blot was used to analyze protein expression. Nitric oxide (NO) was evaluated using fluorescence microscopy. Antisense oligodeoxynucleotides were used for inducible nitric oxide synthase isoform (iNOS) knockdown.Results: Body weight, fat mass, total cholesterol, low-density lipoprotein cholesterol fraction, insulin, and leptin were higher in the sedentary obese group (SD) than in the sedentary control animals (SS). Exercise training prevented these changes. No difference in glucose tolerance, insulin sensitivity, blood pressure, and heart rate was found. Decreased vascular relaxation and reduced endothelial nitric oxide synthase (eNOS) functioning in the SD group were prevented by exercise. Contractile response to phenylephrine was decreased in the aortas of the wild SD mice, compared with that of the SS group; however, no alteration was noted in the SD iNOS−/− animals. The decreased contractility was endothelium-dependent, and was reverted by iNOS inhibition or iNOS silencing. The aortas from the SD group showed increased basal NO production, serum TNFα, TNF receptor-1, and phospho-IκB. Exercise training attenuated iNOS-dependent reduction in contractile response in high-sugar diet–fed animals, decreased iNOS expression, and increased eNOS expression.Conclusion: Obesity caused endothelium dysfunction, TNFα, and iNOS pathway up-regulation, decreasing vascular contractility in the obese animals. Exercise training was an effective therapy to control iNOS-dependent NO production and to preserve endothelial function in obese individuals.

Silva et al.Anti-inflammatory Effects of Acute O-GlcNAcylation also increased survival rates in mice submitted to cecal ligation and puncture (CLP), a sepsis model. In conclusion, increased O-GlcNAc reduces systemic inflammation and cardiovascular disfunction in experimental sepsis models, pointing this pathway as a potential target for therapeutic intervention.

BACKGROUND AND PURPOSEReduced NO availability has been described as a key mechanism responsible for endothelial dysfunction in atherosclerosis. We previously reported that neuronal NOS (nNOS)-derived H2O2 is an important endothelium-derived relaxant factor in the mouse aorta. The role of H2O2 and nNOS in endothelial dysfunction in atherosclerosis remains undetermined. We hypothesized that a decrease in nNOS-derived H2O2 contributes to the impaired vasodilatation in apolipoprotein E-deficient mice (ApoE -/-). EXPERIMENTAL APPROACHChanges in isometric tension were recorded on a myograph; simultaneously, NO and H2O2 were measured using carbon microsensors. Antisense oligodeoxynucleotides were used to knockdown eNOS and nNOS in vivo. Western blot and confocal microscopy were used to analyse the expression and localization of NOS isoforms. KEY RESULTS Aortas from ApoE-/-mice showed impaired vasodilatation paralleled by decreased NO and H2O2 production. Inhibition of nNOS with L-Arg NO2 -L-Dbu, knockdown of nNOS and catalase, which decomposes H2O2 into oxygen and water, decreased ACh-induced relaxation by half, produced a small diminution of NO production and abolished H2O2 in wild-type animals, but had no effect in ApoE -/-mice. Confocal microscopy showed increased nNOS immunostaining in endothelial cells of ApoE -/-mice. However, ACh stimulation of vessels resulted in less phosphorylation on Ser852 in ApoE -/-mice. CONCLUSIONS AND IMPLICATIONSOur data show that endothelial nNOS-derived H2O2 production is impaired and contributes to endothelial dysfunction in ApoE -/-aorta. The present study provides a new mechanism for endothelial dysfunction in atherosclerosis and may represent a novel target to elaborate the therapeutic strategy for vascular atherosclerosis.