Activation of ERK pathway is required for 15-HETE-induced angiogenesis in human umbilical vascular endothelial cells

Role of oxylipins generated from dietary PUFAs in the modulation of endothelial cell function

Oxylipins, which are circulating bioactive lipids generated from polyunsaturated fatty acids (PUFAs) by cyclooxygenase, lipooxygenase and cytochrome P450 enzymes, have diverse effects on endothelial cells. Although studies of the effects of oxylipins on endothelial cell function are accumulating, a review that provides a comprehensive compilation of current knowledge and recent advances in the context of vascular homeostasis is lacking. This is the first compilation of the various in vitro, ex vivo and in vivo reports to examine the effects and potential mechanisms of action of oxylipins on endothelial cells. The aggregate data indicate docosahexaenoic acid-derived oxylipins consistently show beneficial effects related to key endothelial cell functions, whereas oxylipins derived from other PUFAs exhibit both positive and negative effects. Furthermore, information is lacking for certain oxylipin classes, such as those derived from α-linolenic acid, which suggests additional studies are required to achieve a full understanding of how oxylipins affect endothelial cells.

The effect of olmesartan on aortic intimal thickening after balloon injury through Apelin/APJ

PURPOSE

Restenosis is the main complication after percutaneous coronary intervention. The proliferation of new intima contributes to the process. In this study, we aimed to explore the effect of olmesartan on intimal thickening after balloon injury and possible mechanism.

METHODS

Aortic endothelial denudation model was made by a 2F balloon catheter. Thirty-six rats were randomly allocated into three groups: Control (n = 12) Surgery (n = 12, received vascular balloon injury) and Olmesartan (n = 12, received 3 mg^.kg^-1.d^-1olmesartan after injury). Fourteen and 28 days after injury, HE staining was used to assess the aortic endothelial injury. Radioimmunological method was used to examine the level of angiotensin II (Ang II). Western blotting and reverse transcription polymerse chain reaction (RT-PCR) were employed to detect the protein and mRNA level of Apelin/APJ.

RESULTS

After vascular balloon injury, the proliferation of vascular smooth muscle cells and the intimal thickening were increased. The mRNA and protein level of Ang II, AT1, Apelin and APJ mRNA were promoted by vascular balloon injury. Olmesartan decreased the proliferation of vascular smooth muscle cells and the intimal thickening. Olmesartan decreased the expression of Ang II and AT1, but further increased the expression of Apelin and APJ. Balloon injury also induced the activation of Extracellular signal-regulated kinase (ERK) signaling and olmesartan decreased the effect.

CONCLUSION

Olmesartan inhibits the intimal thickening through activating Apelin/APJ and inhibiting AngII-AT1 and ERK pathway.

Oxidized Phospholipids in Healthy and Diseased Lung Endothelium

Circulating and cell membrane phospholipids undergo oxidation caused by enzymatic and non-enzymatic mechanisms. As a result, a diverse group of bioactive oxidized phospholipids generated in these conditions have both beneficial and harmful effects on the human body. Increased production of oxidized phospholipid products with deleterious effects is linked to the pathogenesis of various cardiopulmonary disorders such as atherosclerosis, thrombosis, acute lung injury (ALI), and inflammation. It has been determined that the contrasting biological effects of lipid oxidation products are governed by their structural variations. For example, full-length products of 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine oxidation (OxPAPC) have prominent endothelial barrier protective and anti-inflammatory activities while most of the truncated oxidized phospholipids induce vascular leak and exacerbate inflammation. The extensive studies from our group and other groups have demonstrated a strong potential of OxPAPC in mitigating a wide range of agonist-induced lung injuries and inflammation in pulmonary endothelial cell culture and rodent models of ALI. Concurrently, elevated levels of truncated oxidized phospholipids are present in aged mice lungs that potentiate the inflammatory agents-induced lung injury. On the other hand, increased levels of full length OxPAPC products accelerate ALI recovery by facilitating production of anti-inflammatory lipid mediator, lipoxin A4, and other molecules with anti-inflammatory properties. These findings suggest that OxPAPC-assisted lipid program switch may be a promising therapeutic strategy for treatment of acute inflammatory syndromes. In this review, we will summarize the vascular-protective and deleterious aspects of oxidized phospholipids and discuss their therapeutic potential including engineering of stable analogs of oxidized phospholipids with improved anti-inflammatory and barrier-protective properties.

Use of Human Umbilical Vein Endothelial Cells (HUVEC) as a Model to Study Cardiovascular Disease: A Review

Cardiovascular disease (CVD) is the leading cause of death worldwide, and extensive research has been performed to understand this disease better, using various experimental models. The endothelium plays a crucial role in the development of CVD, since it is an interface between bloodstream components, such as monocytes and platelets, and other arterial wall components. Human umbilical vein endothelial cell (HUVEC) isolation from umbilical cord was first described in 1973. To date, this model is still widely used because of the high HUVEC isolation success rate, and because HUVEC are an excellent model to study a broad array of diseases, including cardiovascular and metabolic diseases. We here review the history of HUVEC isolation, the HUVEC model over time, HUVEC culture characteristics and conditions, advantages and disadvantages of this model and finally, its applications in the area of cardiovascular diseases.

A dual role of 12/15-lipoxygenase in LPS-induced acute renal inflammation and injury

Recent studies suggest a potential role of bioactive lipids in acute kidney injury induced by lipopolysaccharide (LPS). The current study was designed to determine the profiling activities of various polyunsaturated fatty acid (PUFA) metabolizing enzymes, including lipoxygenases (LO), cyclooxygenase, and cytochrome P450 in the plasma of LPS-injected mice using LC-MS. Heat map analysis revealed that out of 126 bioactive lipids screened, only the 12/15-LO metabolite, 12-HETE, had a significant (2.24 ± 0.4) fold increase relative to control (P = 0.0001) after Bonferroni Correction (BCF α = 0.003). We then determined the role of the 12/15-LO in LPS-induced acute kidney injury using genetic and pharmacological approaches. Treatment of LPS injected mice with the 12/15-LO inhibitor, baicalein, significantly reduced levels of renal injury and inflammation markers including urinary thiobarbituric acid reactive substance (TBARs), urinary monocyte chemoattractant protein-1 (MCP-1), renal interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α). Similarly, knocking-out of 12/15-LO reduced levels of renal inflammation and injury markers elicited by LPS injection. Next, we tested whether exogenous supplementation with docosahexaenoic acid (DHA) as a substrate would divert the role of 12/15-LO from being pro-inflammatory to anti-inflammatory via increased production of the anti-inflammatory metabolite. DHA treatment restored the decreased in plasma level of resolvin D2 (RvD2) and reduced renal injury in LPS-injected mice whereas DHA treatment failed to provide any synergistic effects in reducing renal injury in LPS injected 12/15-LO knock-out mice. The ability of RvD2 to protect kidney against LPS-induced renal injury was further confirmed by exogenous RvD2 which significantly reduced the elevation in renal injury in LPS injected mice. These data suggest a double-edged sword role of 12/15-LO in LPS-induced acute renal inflammation and injury, depending on the type of substrate available for its activity.

Carvacrol encapsulated nanocarrier/ nanoemulsion abrogates angiogenesis by downregulating COX-2, VEGF and CD31 in vitro and in vivo in a lung adenocarcinoma model

Nanoemulsion-based synthesis has been introduced to enhance the bioavailability of natural compounds at target sites for their various biomedical applications. In this study, we synthesized carvacrol nanoemulsion (CN) an oil-in-water (O/W) as a nano-emulsion vehicle system by using ultrasonication emulsification for anti-angiogenesis therapy formulated by combining MCT, lecithin, and polysorbate 80 at the O/W interface called carvacrol encapsulated nanoemulsion (CEN). The diameter of CEN determined by TEM analysis was 105.32 nm. The hydrodynamic droplet size was 101.0 nm with a -39.38-mV zeta potential. The stability of the synthesized CEN was approved till 100 days without any change in diameter size distribution and encapsulation efficiency. We evaluated the role of CEN on angiogenesis in lung adenocarcinoma A549 cells both in vitro and in vivo and observed that it reduced the growth and MMP levels of A549 cells in a dose-dependent manner. Exposure to CEN decreased the activation of MAPK p38 as well as ERK. Moreover, we found that CEN reduced the expression of VEGF and CD31 in A549 cells both in vitro and in vivo. Our in-silico study also indicated the binding of carvacrol to COX-2 and VEGF at the active and allosteric sites of CD31 with low binding energy. Overall, CEN induced anti-angiogenic effects in A549 cells in vitro, in silico, and in vivo, thereby establishing its potential as targeted drug delivery vehicle against angiogenesis.

15-oxoeicosatetraenoic acid mediates monocyte adhesion to endothelial cell

Background

A great number of studies reported that 12/15-lipoxygenase (12/15-LO) played an important role in atherosclerosis. And its arachidonic acid(AA) metabolite, 15(S)-hydroperoxy-5,8,11,13-(Z,Z,Z,E)-eicosatetraenoic acid (15(S)-HETE), is demonstrated to mediate endothelial dysfunction. 15-oxo-5,8,11,13-(Z,Z,Z,E)-eicosatetraenoic acid (15-oxo-ETE) was formed from 15-hydroxyprostaglandin dehydrogenase (PGDH)-mediated oxidation of 15(S)-HETE. However, relatively little is known about the biological effects of 15-oxo-ETE in cardiovascular disease. Here, we explore the likely role of 15-lipoxygenase (LO)-1-mediated AA metabolism,15-oxo-ETE, in the early pathogenesis of atherosclerosis.

Methods

The 15-oxo-ETE level in serum was detected by means of liquid chromatography and online tandem mass spectrometry (LC-MS/MS). And the underlying mechanisms were illuminated by molecular techniques, including immunoblotting, MTT assay, immunocytochemistry and Immunohistochemistry.

Results

Increased 15-oxo-ETE level is found in in patients with acute myocardial infarction (AMI). After 15-oxo-ETE treatment, Human umbilical vein endothelial cells (HUVECs) showed more attractive to monocytes, whereas monocyte adhesion is suppressed when treated with PKC inhibitor. In ex vivo study, exposure of arteries from C57 mice and ApoE−/−mice to 15-oxo-ETE led to significantly increased E-selectin expression and monocyte adhesion.

Conclusions

This is the first report that 15-oxo-ETE promotes early pathological process of atherosclerosis by accelerating E-selectin expression and monocyte adhesion. 15-oxo-ETE -induced monocyte adhesion is partly attributable to activation of PKC.

Electronic supplementary material

The online version of this article (doi:10.1186/s12944-017-0518-2) contains supplementary material, which is available to authorized users.

Venous component in scar penetrating neovascularisation

BACKGROUND

The impact of old scar tissue on the venous anatomy of a flap's pedicle is an important question in reconstructive surgery. This study tried to investigate the venous component in scar penetrating neovascularisation.

METHODS

Fifty Sprague-Dawley rats were used in this experimental study. Two experimental groups were designed. In the first group, incisions were performed over the epigastric flap pedicles. In the second group, 1 cm wide segments were excised over the pedicles. Ten weeks after the initial operations, angiographies and histological examinations were performed. A control group was used to demonstrate the normal arterial and venous anatomy of the pedicle.

RESULTS

Arterial angiographies revealed that axial pattern arteries were visible in the incision group as opposed to the excision group. Although venous angiographies showed that there were more venous capillary formations in the incision group, none of the experimental groups had regenerated a vein with an axial pattern. Histological examinations revealed that venous vessel formations were significantly less in the distal samples of the experimental groups when compared to the control group (p < 0.05).

CONCLUSIONS

In this study, it has been observed that arterial pedicles do regenerate over old incision scars as opposed to veins. In the excision scars neither arterial or venous restoration of the axial pedicle was possible. In these cases, only a random type of limited circulation was restored.

The 15-LO-1/15-HETE system promotes angiogenesis by upregulating VEGF in ischemic brains

OBJECTIVES

Angiogenesis promotes neurobehavioral recovery after cerebral ischemic stroke. 15(S)-hydroxyeicosatetraenoic acid (15-HETE) is one of the major metabolites of arachidonic acid by 15-lipoxygenase (15-LO) and stimulates the production of vascular endothelial growth factor (VEGF), thus, inducing autocrine-mediated angiogenesis. The present study aimed to investigate the role of 15-LO/15-HETE system on VEGF expression and angiogenesis in brain ischemia.

METHODS

Rat cerebral arterial vascular endothelial cells were used to set up a cell injury model of oxygen-glucose deprivation and reoxygenation (OGD/R), mimicking a condition of brain ischemia. A mouse model of middle cerebral artery occlusion (MCAO) was established.

RESULTS

Oxygen-glucose deprivation increased cellular expression of 15-LO-1 and VEGF. Transfection of 15-LO-1 siRNA depleted cells of 15-LO-1, and sequentially induced downregulation of VEGF expression; while, incubation of 15-HETE increased the expression of VEGF. Incubation of 15-HETE attenuated the reduction in cell viability induced by oxygen-glucose deprivation, and promoted cell migration, while transfection of 15-LO-1 siRNA showed an opposite effect. In animal experiments, the density of microvessels in hypoxic regions of brains was significantly increased after MCAO, while intracerebroventricular delivery of 15-LO-1 siRNA significantly reduced the density of microvessels, and downregulates VEGF expression.

DISCUSSION

The results indicate that the 15-LO-1/15-HETE system promotes angiogenesis in ischemic brains by upregulation of VEGF, representing a potential target for improving neurobehavioral recovery after cerebral ischemic stroke.

Inhibition of development of laser-induced choroidal neovascularization with suppression of infiltration of macrophages in Smad3-null mice

We evaluated the effects of the loss of Smad3 on the development of experimental argon laser-induced choroidal neovascularization (CNV) in mice. An in vitro angiogenesis model was also used to examine the role of transforming growth factor-β1 (TGFβ1)/Smad3 signaling in vessel-like tube formation by human umbilical vein endothelial cells (HUVECs). CNV was induced in eyes of 8-12-week-old B6.129-background Smad3-deficient (KO) mice (n=47) and wild-type (WT) mice (n=47) by argon laser irradiation. Results showed that the size of the CNV induced was significantly smaller in KO mice as compared with WT mice at day 14 as revealed by high-resolution angiography with fluorescein isothiocyanate-dextran. Immunohistochemistry and real-time reverse transcription-polymerase chain reaction of RNA extracted from laser-irradiated choroidal tissues were conducted on specimens at specific timepoints. Invasion of macrophages (F4/80+), but not neutrophils (myeloperoxidase+), and appearance of myofibroblasts (α-smooth muscle actin+) were suppressed in laser-irradiated KO tissues. mRNA expression of inflammation-related factors, that is, vascular endothelial growth factor (VEGF), macrophage-chemoattractant protein-1 (MCP-1), interleukin-6 (IL-6) and TGFβ1 in choroidal tissues was suppressed by the loss of Smad3. We then examined the effects of adding a Smad3 inhibitor, SIS3, or an ALK5 inhibitor, SB431542, on tube formation promoted by TGFβ1 or VEGF in HUVECs cocultured with fibroblast feeder. Further addition of SIS3 or SB431542 augmented vessel-like tube formation by HUVECs in the presence of TGFβ1 or VEGF. In conclusion, lack of Smad3 attenuated the growth of laser-induced CNV with suppression of inflammation by macrophages in mice. Because blocking TGFβ1/Smad3 signal stimulated the activity of angiogenesis of HUVECs in vitro, the reduction of CNV in vivo in KO mice is attributed to a decrease in growth factor levels in the tissue by the loss of Smad3.