Suppression of inflammatory response and endothelial nitric oxide synthase downregulation in hyperlipidaemic C57BL/6J mice by eugenosedin-A

Impaired endothelial cell proliferative, migratory, and adhesive abilities are associated with the slow endothelialization of polycaprolactone vascular grafts implanted into a hypercholesterolemia rat model

Most small diameter vascular grafts (inner diameter<6 mm) evaluation studies are performed in healthy animals that cannot represent the clinical situation. Herein, an hypercholesterolemia (HC) rat model with thickened intima and elevated expression of pro-inflammatory intercellular adhesion molecular-1 (ICAM-1) in the carotid branch is established. Electrospun polycaprolactone (PCL) vascular grafts (length: 1 cm; inner diameter: 2 mm) are implanted into the HC rat abdominal aortas in an end to end fashion and followed up to 43 days, showing a relative lower patency accompanied by significant neointima hyperplasia, abundant collagen deposition, and slower endothelialization than those implanted into healthy ones. Moreover, the proliferation, migration, and adhesion behavior of endothelial cells (ECs) isolated from the HC aortas are impaired as evaluated under both static and pulsatile flow conditions. DNA microarray studies of the HC aortic endothelium suggest genes involved in EC proliferation (Egr2), apoptosis (Zbtb16 and Mt1), and metabolism (Slc7a11 and Hamp) are down regulated. These results suggest the impaired proliferative, migratory, and adhesive abilities of ECs are associated with the bad performances of grafts in HC rat. Future pre-clinical evaluation of small diameter vascular grafts may concern more disease animal models with clinical complications. STATEMENT OF SIGNIFICANCE: During the development of small diameter vascular grafts (D<6 mm), young and healthy animal models from pigs, sheep, dogs, to rabbits and rats are preferred. However, it cannot represent the clinic situation, where most cardiovascular grafting procedures are performed in the elderly and age is the primary risk factor for disease development or death. Herein, the performance of electrospun polycaprolactone (PCL) vascular grafts implanted into hypercholesterolemia (HC) or healthy rats were evaluated. Results suggest the proliferative, migratory, and adhesive abilities of endothelial cells (ECs) are already impaired in HC rats, which contributes to the observed slower endothelialization of implanted PCL grafts. Future pre-clinical evaluation of small diameter vascular grafts may concern more disease animal models with clinical complications.

Eugenosedin-A improves obesity-related hyperglycemia by regulating ATP-sensitive K+ channels and insulin secretion in pancreatic β cells

Eugenosedin-A (Eu-A) has been shown to protect against hyperglycemia- and hyperlipidemia-induced metabolic syndrome. We investigated the relationship of K_ATP channel activities and insulin secretion by Eu-A in vitro in pancreatic β-cells, and examined the effect of Eu-A on streptozotocin (STZ)/nicotinamide (NA)-induced type 2 diabetes mellitus (T2DM) in vivo. We isolated pancreatic islets from adult male Wistar rats (250-350 g) and identified pancreatic β-cells by the cell size, capacitance and membrane potential. Perforated patch-clamp and inside-out recordings were used to monitor the membrane potential (current-clamp mode) and channel activity (voltage-clamp mode) of β-cells. The membrane potential of β-cells was raised by Eu-A and reversed by the K_ATP channel activator diazoxide. Eu-A inhibited the K_ATP channel activity measured at - 60 mV and increased the intracellular calcium concentration ([Ca²⁺]_i), resulting in enhanced insulin secretion. Eu-A also reduced Kir6.2 protein on the cell membrane and scattered in the cytosol under normal glucose conditions (5.6 mM). In our animal study, rats were divided into normal and STZ/NA-induced T2DM groups. Normal rats fed with regular chow were divided into control and control+Eu-A (5 mg/kg/day, i.p.) groups. The STZ/NA-induced diabetic rats fed with a high-fat diet (HFD) were divided into three groups: T2DM, T2DM+Eu-A (5 mg/kg/day, i.p.), and T2DM+glibenclamide (0.5 mg/kg/day, i.p.; a K_ATP channel inhibitor). Both Eu-A and glibenclamide decreased the rats' blood glucose, prevented weight gain, and enhanced insulin secretion. We found that Eu-A blocked pancreatic β-cell K_ATP channels, caused membrane potential depolarization, and stimulated Ca²⁺ influx, thus increasing insulin secretion. Furthermore, Eu-A decreased blood glucose and increased insulin levels in T2DM rats. These results suggested that Eu-A might have clinical benefits for the control of T2DM and its complications.

Chronic peroxisome proliferator-activated receptorβ/δ agonist GW0742 prevents hypertension, vascular inflammatory and oxidative status, and endothelial dysfunction in diet-induced obesity

OBJECTIVE

Endothelial dysfunction plays a key role in obesity-induced risk of cardiovascular disease. The aim of the present study was to analyze the effect of chronic peroxisome proliferator-activated receptor (PPAR)β/δ agonist GW0742 treatment on endothelial function in obese mice fed a high-fat diet (HFD).

METHODS AND RESULTS

Five-week-old male mice were allocated to one of the following groups: control, control-treated (GW0742, 3 mg/kg per day, by oral gavage), HFD, HFD + GW0742, HFD + GSK0660 (1 mg/kg/day, intraperitoneal) or HFD-GW0742-GSK0660 and followed for 11 or 13 weeks. GW0742 administration to mice fed HFD prevented the gain of body weight, heart and kidney hypertrophy, and fat accumulation. The increase in plasma levels of fasting glucose, glucose tolerance test, homeostatic model assessment of insulin resistance, and triglyceride found in the HFD group was suppressed by GW0742. This agonist increased plasma HDL in HFD-fed mice and restored the levels of tumor necrosis factor-α and adiponectin in fat. GW0742 prevented the impaired nitric oxide-dependent vasodilatation induced by acetylcholine in aortic rings from mice fed HFD. Moreover, GW0742 increased both aortic Akt and endothelial nitric oxide synthase phosphorylation, and inhibited the increase in caveolin-1/endothelial nitric oxide synthase interaction, ethidium fluorescence, NOX-1, Toll-like receptor 4, tumor necrosis factor-α, and interleukin-6 expression, and IκBα phosphorylation found in aortae from the HFD group. GSK0660 prevented all changes induced by GW0742.

CONCLUSION

PPARβ/δ activation prevents obesity and exerts protective effects on hypertension and on the early manifestations of atherosclerosis, that is, endothelial dysfunction and the vascular pro-oxidant and pro-inflammatory status, in HFD-fed mice.

Low-dose aspirin ameliorated hyperlipidemia, adhesion molecule, and chemokine production induced by high-fat diet in Sprague-Dawley rats

In this study the effects of low-dose aspirin (5 mg/kg) on adhesion molecule and chemokine expression in a hyperlipidemic rat model. Six-week-old Sprague-Dawley (SD) rats were assigned to two control groups receiving either a regular diet or high-fat diet (HFD) and a treatment group fed HFD with 5 mg/kg aspirin for a 10-week period. Compared with the regular diet control group, the HFD control group had higher body weight, lower levels of high-density lipoprotein, higher concentrations of insulin, triglyceride, total cholesterol, and low-density lipoprotein, but no differences in blood glucose and glycated hemoglobin. The prothrombin time (PT) and activated partial thromboplastin time (aPTT) were clearly shortened in the HFD group. That group also had increased expression of intercellular adhesion molecule-1 (ICAM-1), ICAM-2, ICAM-3, vascular cell adhesion molecule (VCAM), platelet endothelial cell adhesion molecule (PECAM) and P-selectin in platelets and vascular adhesion protein-1 in lymphocyte and in aorta increased expressions of ICAM-1, ICAM-2, ICAM-3, VCAM, PECAM, E-selectin, monocyte chemoattractant protein-1 (MCP-1) and CCR2. The HFD rats also had increased PKCα, IκB kinase α (IKKα), p65, mitogen-activated protein kinases (MAPKs) (p38, c-Jun N-terminal kinases 1, extracellular signal-regulated kinase 1/2), and their phosphorylated forms. Low-dose aspirin improved HFD-induced hyperinsulinemia and hyperlipidemia, recovered PT and aPTT, inhibited upregulation of adhesion molecules and chemokines and reduced expression of PKCα, IKKα, p65, and MAPKs. Low-dose aspirin ameliorates HFD-induced hyperlipidemia and hyperinsulinemia, and prevents HFD-induced expression of adhesion molecules and chemokine formation.

Eugenosedin-A ameliorates hyperlipidemia-induced vascular endothelial dysfunction via inhibition of α1-adrenoceptor/5-HT activity and NADPH oxidase expression

Eugenosedin-A (Eu-A) effects on vascular endothelial dysfunction and oxidative stress in a hyperlipidemic rat model were investigated. Rats were randomly divided into four groups: two control groups and two treatment groups. The control rats received a regular diet or high fat diet (HFD); the treatment rats fed received an HFD with 5 mg/kg Eu-A or atorvastatin for 10 weeks. No changes in serotonin levels were observed in the four groups; norepinephrine levels were enhanced in the HFD group which was attenuated by Eu-A and atorvastatin. In the HFD group, the vascular reactivity was increased by vasoconstrictors (5-nonyloxytryptamine, 5-HT, and phenylephrine) and decreased by an endothelium-dependent vasorelaxant, carbachol. Protein levels of α1-adrenergic receptors (not 5-HT1B/2A), reactive oxygen species (ROS) p47(phox), p67(phox), and gp91(phox), and oxidative damage markers 3-nitrotyrosine (3-NT) and 4-hydroxy-2-nonenal (4-HNE) were increased, but endothelial nitric oxide synthase (eNOS), P-eNOS and vasodilator-stimulated phosphoprotein phosphorylation (P-VASP) were decreased. Catalase and superoxide dismutase (SOD-1 and SOD-2) proteins were increased, but glutathione peroxidase (GPx) was decreased in the aorta. Eu-A and atorvastatin reduced vasoconstrictor-induced aortic contractions that might be related to 5-HT1B/2A and α1-adrenergic receptors inhibitory activities. Eu-A and atorvastatin improved eNOS/P-eNOS, P-VASP, GPx, and malondialdehyde (MDA) levels, and decreased ROS and oxidative damage markers. Taken together, we suggest that Eu-A can ameliorate hyperlipidemia-induced vascular endothelial dysfunction and oxidative dysregulation.

Eugenosedin-A prevents high-fat diet increased adhesion molecules through inhibition of MAPK- and p65-mediated NF-κB pathway in rat model

Objectives

Previous studies have shown eugenosedin-A, a 5-HT1B/2A and α1/α2/β1-adrenergic blocker, is able to decrease cholesterol levels, hyperglycaemia and inflammation in hyperlipidaemic mice induced by high-fat diet (HFD). The aim of this study is to examine the effects of eugenosedin-A on the inhibition of adhesion molecules of platelets, the aorta and acyl-coenzymeA:cholesterol acyltransferase-1 (ACAT-1) of macrophages in a hyperlipidaemic rat model.

Methods

Six-week-old Sprague–Dawley rats were randomly divided into two control and treatment groups. The control rats received either a regular diet or HFD and the treatment groups were fed HFD with either 5 mg/kg eugenosedin-A or atorvastatin for a 10-week period.

Key findings

Compared with the two control groups, the HFD group had lower levels of high-density lipoprotein, higher concentrations of triglycerides, total cholesterol, low-density lipoprotein and insulin. The expression of adhesion molecules in platelets, aorta and monocyte-macrophage were enhanced by HFD. HFD also increased upstream proteins and their phosphorylated form in the aorta. In treatment groups, eugenosedin-A and atorvastatin improved HFD-induced hyperlipidaemia and levels of insulin. Eugenosedin-A reduced the upregulation of P-selectin, ICAM-1, ICAM-2, ICAM-3, VCAM, PECAM in platelets and inhibited E-selectin, ICAM-1, ICAM-2, ICAM-3, VCAM and PECAM protein levels in the aorta. Eugenosedin-A reduced the ACAT-1 protein expression of monocyte-macrophages. The expression of PKCα, MAPKs, IKKα and p65 and their phosphorylated form were reduced in treatment groups.

Conclusions

Taken together, hyperlipidaemia enhances the expression of adhesion molecules and ACAT-1 protein, and eugenosedin-A ameliorates those increases. Through inhibition of MAPK- and p-65-mediated NF-κB pathway, eugenosedin-A decreases the quantity of adhesion molecules.