Altered bioavailability of epoxyeicosatrienoic acids is associated with conduit artery endothelial dysfunction in type 2 diabetic patients.

BACKGROUND: This pathophysiological study addressed the hypothesis that soluble epoxide hydrolase (sEH), which metabolizes the vasodilator and anti-inflammatory epoxyeicosatrienoic acids (EETs) to dihydroxyeicosatrienoic acids (DHETs), contributes to conduit artery endothelial dysfunction in type 2 diabetes. METHODS AND RESULTS: Radial artery endothelium-dependent flow-mediated dilatation in response to hand skin heating was reduced in essential hypertensive patients (n = 9) and type 2 diabetic subjects with (n = 19) or without hypertension (n = 10) compared to healthy subjects (n = 36), taking into consideration cardiovascular risk factors, flow stimulus and endothelium-independent dilatation to glyceryl trinitrate. Diabetic patients but not non-diabetic hypertensive subjects displayed elevated whole blood reactive oxygen species levels and loss of NO release during heating, assessed by measuring local plasma nitrite variation. Moreover, plasma levels of EET regioisomers increased during heating in healthy subjects, did not change in hypertensive patients and decreased in diabetic patients. Correlation analysis showed in the overall population that the less NO and EETs bioavailability increases during heating, the more flow-mediated dilatation is reduced. The expression and activity of sEH, measured in isolated peripheral blood mononuclear cells, was elevated in diabetic but not hypertensive patients, leading to increased EETs conversion to DHETs. Finally, hyperglycemic and hyperinsulinemic euglycemic clamps induced a decrease in flow-mediated dilatation in healthy subjects and this was associated with an altered EETs release during heating. CONCLUSIONS: These results demonstrate that an increased EETs degradation by sEH and altered NO bioavailability are associated with conduit artery endothelial dysfunction in type 2 diabetic patients independently from their hypertensive status. The hyperinsulinemic and hyperglycemic state in these patients may contribute to these alterations. Trial registration NCT02311075. Registered December 8, 2014.

Impact of high-fat diet and vitamin D3 supplementation on aortic stenosis establishment in waved-2 epidermal growth factor receptor mutant mice.

OBJECTIVE: The use of animal models of aortic stenosis (AS) remains essential to further elucidate its pathophysiology and to evaluate new therapeutic strategies. The waved-2 mouse AS model has been proposed; data have indicated that while aortic regurgitation (AR) is effectively induced, development of AS is rare. We aimed to evaluate the effect of high-fat diet (HFD) and vitamin D3 supplementation in this model. METHODS: HFD and subcutaneous vitamin D3 injections were initiated at the age of 6 weeks until the age of 6 (n = 16, 6-month treatment group) and 9 (n = 11, 9-month treatment group) months. Twelve waved-2 mice without supplementation were used as control. Echocardiography was performed at 3, 6 and 9 months. Blood serum analysis (calcium, 1,25(OH)2D3 and cholesterol), histology and immunohistochemistry (CD-31, CD-68 and osteopontin) were evaluated at the end of the experiment (6 or 9 months). RESULTS: Total cholesterol and 1,25(OH)2D3 were significantly increased relative to the control group. HFD and vitamin D3 supplementation did result in improvements to the model, since AS was only detected in 6 (15.3%) mice (2 in the 3 groups) and AR was developed in the remaining animals. Echocardiographic parameters, fibrosis, thickness, inflammation and valvular calcification, were not significantly different between the 6-month treatment and control groups. Similar results were also observed in the 9-month treatment group. CONCLUSION: These results suggest that HFD and vitamin D3 supplementation have no effect in the waved-2 mouse model. This model essentially mimics AR and rarely AS. Further studies are needed to find a reliable animal model of AS.

A role for intestinal TLR4-driven inflammatory response during activity-based anorexia.

Anorexia nervosa (AN) is associated with low-grade systemic inflammation and altered gut microbiota. However, the molecular origin of the inflammation remains unknown. Toll-like receptors are key regulators of innate immune response and their activation seems also to be involved in the control of food intake. We used activity-based anorexia (ABA) model to investigate the role of TLR4 and its contribution in anorexia-associated low-grade inflammation. Here, we found that ABA affected early the intestinal inflammatory status and the hypothalamic response. Indeed, TLR4 was upregulated both on colonic epithelial cells and intestinal macrophages, leading to elevated downstream mucosal cytokine production. These mucosal changes occurred earlier than hypothalamic changes driving to increased levels of IL-1ß and IL-1R1 as well as increased levels of plasma corticosterone. Paradoxically, TLR4-deficient mice exhibited greater vulnerability to ABA with increased mortality rate, suggesting a major contribution of TLR4-mediated responses during ABA-induced weight loss.

Selective Stimulation of Cardiac Lymphangiogenesis Reduces Myocardial Edema and Fibrosis Leading to Improved Cardiac Function Following Myocardial Infarction.

BACKGROUND: The lymphatic system regulates interstitial tissue fluid balance, and lymphatic malfunction causes edema. The heart has an extensive lymphatic network displaying a dynamic range of lymph flow in physiology. Myocardial edema occurs in many cardiovascular diseases, eg, myocardial infarction (MI) and chronic heart failure, suggesting that cardiac lymphatic transport may be insufficient in pathology. Here, we investigate in rats the impact of MI and subsequent chronic heart failure on the cardiac lymphatic network. Further, we evaluate for the first time the functional effects of selective therapeutic stimulation of cardiac lymphangiogenesis post-MI. METHODS AND RESULTS: We investigated cardiac lymphatic structure and function in rats with MI induced by either temporary occlusion (n=160) or permanent ligation (n=100) of the left coronary artery. Although MI induced robust, intramyocardial capillary lymphangiogenesis, adverse remodeling of epicardial precollector and collector lymphatics occurred, leading to reduced cardiac lymphatic transport capacity. Consequently, myocardial edema persisted for several months post-MI, extending from the infarct to noninfarcted myocardium. Intramyocardial-targeted delivery of the vascular endothelial growth factor receptor 3-selective designer protein VEGF-CC152S, using albumin-alginate microparticles, accelerated cardiac lymphangiogenesis in a dose-dependent manner and limited precollector remodeling post-MI. As a result, myocardial fluid balance was improved, and cardiac inflammation, fibrosis, and dysfunction were attenuated. CONCLUSIONS: We show that, despite the endogenous cardiac lymphangiogenic response post-MI, the remodeling and dysfunction of collecting ducts contribute to the development of chronic myocardial edema and inflammation-aggravating cardiac fibrosis and dysfunction. Moreover, our data reveal that therapeutic lymphangiogenesis may be a promising new approach for the treatment of cardiovascular diseases.

Prevention of tungiasis and tungiasis-associated morbidity using the plant-based repellent Zanzarin: a randomized, controlled field study in rural Madagascar.

BACKGROUND: Tungiasis, a parasitic skin disease caused by the female sand flea Tunga penetrans, is a prevalent condition in impoverished communities in the tropics. In this setting, the ectoparasitosis is associated with important morbidity. It causes disfigurement and mutilation of the feet. Feasible and effective treatment is not available. So far prevention is the only means to control tungiasis-associated morbidity. METHODOLOGY: In two villages in Central Madagascar, we assessed the efficacy of the availability of closed shoes and the twice-daily application of a plant-based repellent active against sand fleas (Zanzarin) in comparison to a control group without intervention. The study population was randomized into three groups: shoe group, repellent group and control group and monitored for ten weeks. The intensity of infestation, the attack rate and the severity of tungiasis-associated morbidity were assessed every two weeks. FINDINGS: In the repellent group, the median attack rate became zero already after two weeks. The intensity of the infestation decreased constantly during the observation period and tungiasis-associated morbidity was lowered to an insignificant level. In the shoe group, only a marginal decrease in the intensity of infestation and in the attack rate was observed. At week 10, the intensity of infestation, the attack rate and the severity score for acute tungiasis remained significantly higher in the shoe group than in the repellent group. Per protocol analysis showed that the protective effect of shoes was closely related to the regularity with which shoes were worn. CONCLUSIONS: Although shoes were requested by the villagers and wearing shoes was encouraged by the investigators at the beginning of the study, the availability of shoes only marginally influenced the attack rate of female sand fleas. The twice-daily application of a plant-based repellent active against sand fleas reduced the attack to zero and lowered tungiasis-associated morbidity to an insignificant level.

Omega-3 polyunsaturated fatty acids delay the progression of endotoxic shock-induced myocardial dysfunction.

Septic shock has a high mortality rate, partially related to myocardial dysfunction. Polyunsaturated fatty acids (omega-3 PUFAs) possess anti-inflammatory and antioxidant properties, but whether omega-3 PUFAs exert beneficial effects on myocardial function is unknown. We investigated, in a rat model of endotoxic shock, the effects of omega-3 PUFAs pretreatment on cardiac hemodynamics, function, and oxidative stress as well as intestinal barrier. Endotoxic shock was induced by lipopolysaccharide (LPS; 20 mg/kg IP) administered to rats pretreated or not with omega-3 PUFAs (Omegaven®; 0.5 g/kg IP, 90 min before injection of LPS). Two or 5 h after LPS, left ventricular function and arterial pressure were measured, followed by assessment left ventricular total glutathione as well as tumor necrosis factor alpha expression, occuldin expression, and proteasome activities. LPS reduced mean arterial blood pressure to the same extent 2 and 5 h after its administration, but cardiac output was more markedly decreased after 5 h. Omega-3 PUFAs pretreatment did not significantly modify the effect of LPS on mean arterial pressure and total peripheral resistance, but prevented the decrease in cardiac output 2 h after LPS. LPS increased oxidized glutathione after 2 h, and this increase was significantly attenuated by omega-3 PUFAs. Simultaneously, omega-3 PUFAs increased myocardial hemeoxygenase-1 (HO-1) mRNA expression. Finally, omega-3 PUFAs prevented the reduction of intestinal occludin expression. Omega-3 PUFAs pre-treatment improves myocardial dysfunction during endotoxemia and increases myocardial HO-1 expression. Moreover, the preservation of the intestinal occludin induced by omega-3 PUFAs precedes myocardial protection, suggesting the involvement of the intestinal barrier in the myocardial improvement observed with omega-3 PUFAs parenteral supplementation.

Selenium diet-supplementation improves cocaine-induced myocardial oxidative stress and prevents cardiac dysfunction in rats.

Chronic cocaine abuse causes cardiac dysfunction and induces oxidative stress. The goal of this study was to evaluate whether an enhanced antioxidant pool, induced by the administration of selenium, may prevent the myocardial dysfunction induced by cocaine. Cocaine was administered for 7 days (15 mg/kg/day, i.p.) to rats pretreated for 4 weeks with selenium (1.16 mg/L/day, p.o.). Cardiac function was evaluated by cardiac index and left ventricular (LV) fractional shortening (FS) measured by echocardiography. The redox ratio and enzymatic activities of glutathione peroxidase (GPX) and superoxide dismutase (SOD) were measured in the LV myocardium. Cocaine administration induced a cardiac dysfunction, as evidenced by a decrease in cardiac index and LV FS as well as by an increase in LV diameters. Moreover, antioxidant markers and redox ratio were altered in rats after cocaine exposure. Selenite supplementation induced a significant limitation of cardiac index and FS alterations observed after cocaine administration. This improvement in cardiac function was associated with a redox ratio recovery while SOD and GPX activities remained unchanged. Thus, selenite reversed both the oxidative stress and the contractile dysfunction induced by cocaine administration. These results suggest a major role of oxidative stress in the cocaine-induced cardiotoxicity.

Long-term heart rate reduction induced by the selective I(f) current inhibitor ivabradine improves left ventricular function and intrinsic myocardial structure in congestive heart failure.

BACKGROUND: Heart rate reduction (HRR) improves left ventricular (LV) filling, increases myocardial O2 supply, and reduces myocardial O2 consumption, which are all beneficial in congestive heart failure (CHF). However, the long-term effects of HRR on cardiac function and remodeling are unknown. METHODS AND RESULTS: We assessed, in rats with CHF, the effects of long-term HRR induced by the selective I(f) current inhibitor ivabradine (as food admix for 90 days starting 7 days after coronary artery ligation). To assess intrinsic modifications of LV tissue induced by long-term HRR, all parameters were reassessed 3 days after interruption of treatment. Ivabradine decreased heart rate over the 90-day treatment period (-18% versus untreated at 10 mg x kg(-1) x d(-1)), without modifying blood pressure, LV end-diastolic pressure, or dP/dt(max/min). Ivabradine significantly reduced LV end-systolic but not end-diastolic diameter, which resulted in preserved cardiac output due to increased stroke volume. In the Langendorff preparation, ivabradine shifted LV systolic but not end-diastolic pressure-volume relations to the left. Ivabradine decreased LV collagen density and increased LV capillary density without modifying LV weight. Three days after interruption of treatment, the effects of ivabradine on LV geometry, shortening, and stroke volume persisted despite normalization of heart rate. CONCLUSIONS: In rats with CHF, long-term HRR induced by the selective I(f) inhibitor ivabradine improves LV function and increases stroke volume, preserving cardiac output despite the HRR. The improvement of cardiac function is related not only to the HRR per se but also to modifications in the extracellular matrix and/or function of myocytes as a consequence of long-term HRR.