Rat Cardiac Microvascular Endothelial Cells Research Articles

Interleukin 33 inhibits lipopolysaccharide-induced high permeability of cardiac microvascular endothelial cells

Objective: To investigate the effect of interleukin-33 (IL-33) on lipopolysaccharide (LPS)-induced permeability of rat cardiac microvascular endothelial cells (RCMECs). Methods: RCMECs were cultured in vitro to be divided into control group, LPS group, IL-33 group and LPS+IL-33 group. The effect of IL-33 on the proliferation of RCMECs was detected by cell counting reagent (CCK8). Fluorescein isothiocyanate (FITC)-dextran assay was used to evaluate the permeability of RCMECs. The expression of vascular endothelial calmodulin, ras homologous gene family (Rho) member A (RhoA) and phosphorylated Rho-associated coiled-coil-containing protein kinase (p-ROCK2) proteins were tested by western blot. High-throughput sequencing and gene ontology (GO) were performed for gene expression in LPS and LPS+IL-33 groups. Results: No significant effect of IL-33 at 10-50 ng/ml on the proliferation of RCMECs was observed (P>0.05). Compared with the control group, the permeability of RCMECs (permeability coefficient ratio 1.404±0.029 vs. 1.000±0.200, P<0.05) was significantly increased in LPS group and the expression of vascular endothelial calmodulin (relative gray value 0.429 5±0.012 9 vs. 0.594 9±0.014 2, P<0.05) was down-regulated, while the permeability of monolayers (permeability coefficient ratio, 0.948±0.013, P<0.01) was decreased in LPS+IL-33 group and the expression of vascular endothelial calmodulin (relative grayscale value 0.549 1±0.012 0, P<0.005) was up-regulated compared with the LPS group. High-throughput sequencing data revealed that the differential genes downregulated in the LPS and LPS+IL-33 groups were associated with cytoskeleton and Rho signaling pathway. Compared with the control group, RhoA (relative gray value 0.211 4±0.009 9 vs. 0.135 0±0.007 6, P<0.000 1) and p-ROCK (relative gray value 0.656 3±0.013 2 vs. 0.503 6±0.036 2, P<0.000 1) protein expression was upregulated in the LPS group. When compared with LPS group, RhoA (relative gray value 0.157 7±0.010 7, P=0.000 2), p-ROCK (relative gray value 0.427 7±0.003 8, P<0.000 1) protein expression was decreased in LPS+IL-33 group. Conclusion: IL-33 may improve LPS-induced hyperpermeability of RCMECs by inhibiting RhoA and p-ROCK protein expression in Rho/Rho-associated coiled-coil-containing protein kinase signaling pathway.

Dendritic cell‑derived exosomal miR‑494‑3p promotes angiogenesis following myocardial infarction.

Infiltration by dendritic cells (DCs) is markedly increased in the infarcted area following myocardial infarction (MI), and DC ablation has been shown to impair angiogenesis in mice post-MI. Exosomes (EXs) have long been known to act as messengers between cells; however, whether EXs derived from DCs can enhance myocardial angiogenesis post-MI remains unknown. The aim of the present study was to elucidate whether EXs derived from DCs induce myocardial angiogenesis via paracrine signaling post-MI. In vitro, suspensions of mouse bone marrow-derived DCs (BMDCs) were incubated with the supernatant of necrotic or normal cultured HL-1 myocardial cells (as the MI or control group, respectively) for 24 h. EXs isolated from the supernatant of BMDCs were termed DEXs, which were added to primary cultures of rat cardiac microvascular endothelial cells (CMECs), and angiogenesis was evaluated by measuring tube formation and vascular endothelial growth factor (VEGF) expression. In vivo, different groups of DEXs were injected into the infarcted myocardium of MI model mice. Then, angiogenesis was evaluated by measuring the number of vessels and the expression of VEGF and CD31 in the infarcted myocardium using immunohistochemistry. Moreover, the expression profile of microRNAs (miRNAs or miRs) in splenic DCs of MI model mice was analyzed by Affymetrix miRNA 4.0 chip assays, then certified in DEXs by reverse transcription-quantitative PCR analysis. Finally, miRNA-loaded DEXs were used to induce tube formation by CMECs and angiogenesis in MI model mice. It was observed that, compared with the control group, DEXs from the MI group significantly upregulated the expression of VEGF in CMECs, enhanced tube formation by CMECs, and upregulated the expression of VEGF and CD31 in the infarcted myocardium of MI model mice. miR-494-3p and miR-16a-5p, which are associated with angiogenesis, were significantly upregulated in splenic DCs of MI model mice by Affymetrix miRNA 4.0 chip assays, miR-494-3p was significantly upregulated and highly enriched in DEXs from the MI group compared with the control, and DEX-miR-494-3p enhanced tube formation by CMECs and angiogenesis in mice post-MI. These results suggest that miR-494-3p may be secreted from DCs via EXs and promotes angiogenesis post-MI. These findings indicate a novel DEX-based approach to the treatment of MI.

Qiliqiangxin Prescription Promotes Angiogenesis of Hypoxic Primary Rat Cardiac Microvascular Endothelial Cells via Regulating miR-21 Signaling.

Angiogenesis is the most important repair process of tissues subjected to ischemic injury. The present study aims to investigate whether the pro-angiogenic effect of Qiliqiangxin prescription (QL) is mediated through miR-21 signaling. Cardiac microvascular endothelial cells (CMECs) were isolated and cultured from 2-3 weeks old SD rats by the method of planting myocardium tissues. The purity was identified by CD31 immunofluorescence staining. CMECs were then cultured under 1% O2 hypoxia or normoxia condition for 24h in the presence or absence of QL pretreatment (QL, 0.5mg/ml, 24h). The mimics and inhibitors of miR-21 were transfected into CMECs. miR-21, HIF-1α, and VEGF expressions of CMECs were then detected by qRT-PCR and/or Western blot. The proliferation, migration, and tube formation functions of CMECs were assessed using the BrdU assay, wound healing test, and tube formation assay, respectively. The results showed that compared with the control group, hypoxia significantly upregulated the expression of miR-21 and impaired CMECs proliferation, migration, and tube formation functions. Compared with the hypoxia group, QL further upregulated miR-21, HIF-1α, and VEGF expressions, and improved cell proliferation, migration, and tube formation of hypoxic CMECs. These effects of QL were abolished by a knockdown of miR-21. Conversely, treatment with miR-21 mimics further enhanced QL induced changes in hypoxic CMECs. Results indicate that the pro-angiogenesis effects of QL on hypoxic CMECs are mediated by activating miR-21 and its downstream HIF-1α/VEGF pathway possibly.

Effects of Chronic Artificial Sweetener Consumption on Type 1 Diabetes Susceptibility

As the diabetes epidemic grows worldwide, there is a heightened awareness of how modern day diets may contribute to the increased incidence of disease. To combat the dietary intake of sugar, there has been a drastic increase in the daily consumption of non‐caloric artificial sweeteners (NCAS). However, a number of studies suggest that NCAS cause counterintuitive metabolic derangements that may contribute to negative health outcomes. Conversely, there are limited duration studies focused on weight management suggesting the opposite, thus creating controversy. The impact of chronic NCAS consumption in type 1 diabetes (T1D) patients or those with a high genetic susceptibility for T1D is also unknown. T1D has a strong genetic basis; however, environmental factors likely underlie the rapid increase in T1D incidence in the past few decades. Children with T1D frequently consume NCAS as a way of managing postprandial hyperglycemia and insulin doses. Increased availability of NCAS within the home likely also translates to more NCAS consumption by non‐diabetic siblings with a higher risk to develop T1D. Our study aimed to test the effects of chronic consumption of NCAS subtypes on high T1D susceptibility backgrounds. To test this, we supplemented the diet of T1D susceptible BioBreeding DR+/+ rats with aspartame (metabolized) and acesulfame potassium (Ace‐K+, not metabolized) for three weeks in their drinking water. DR+/+ rats consuming NCAS water had a significant increase in blood glucose versus normal water controls. Metabolomics analysis of plasma from these rats revealed alterations in lipid and energy metabolism, with a greater effect resulting from Ace‐K+. Using a novel mass spectrometry‐based quantification assay we developed, we found that Ace‐K+ also accumulated in the plasma these DR+/+ rats (21+10 μM; N=6) following chronic consumption. Further follow‐up was performed in vitro using rat cardiac microvascular endothelial cells (RCMVECs) to measure cardiometabolic effects. The RCMVECs were treated with an Ace‐K+ dose‐response for three weeks and they exhibited impairment during in vitro tube formation and cell viability tests (p&lt;0.05; N=3). Gene expression analysis of the RCMVECs displayed significant differences in insulin signaling, glucose metabolism, and inflammatory regulation (p&lt;0.05; N=4). In further tests, we also observed that chronic Ace‐K+ consumption accelerated the rate of type 1 diabetes onset in DRlyp/lyp rats. Overall, these results suggest that the accumulation of absorbed intact NCAS subtypes, like Ace‐K+, have the potential to lead to metabolic flux that may be important in pre‐ and post‐onset T1D, whereas the metabolized aspartame caused less fluctuation. We are now focused on translating these studies to a pediatric T1D population and are implementing a novel NCAS food frequency questionnaire and plasma quantification test to better measure consumption clinically.Support or Funding InformationSupport for this project was provided by the Medical College of Wisconsin Clinical and Translational Science Institute, the Mayo Clinic Metabolomics Resource Core (pilot award provided by the U24DK100469 grant to BRH), and the Children’s Research Institute (CRI19301 to MH).

Hyperglycemia‐Induced Inhibition of the Angiotensin II Type 1 Receptor Pathway in the Vascular Endothelium

Hyperglycemia, associated with diabetes, is known to damage blood vessels and contribute to negative cardiovascular health outcomes. However, the etiology behind the negative influence of the exposure to prolonged elevated glucose on endothelial cells is not yet fully understood. Our laboratories’ previous study identified changes in endothelial cell surface glycosylation resulting from hyperglycemia. One such modified protein was the Angiotensin II type 1 receptor (AT1R), which was N‐glycosylated adjacent to the active site. Activation of AT1R by angiotensin II (AngII) at subpressor doses is associated with positive endothelial cell growth, proliferation, and tube formation. However, AngII binding to the Angiotensin II type 2 receptor (AT2R), has been shown to elicit opposing effects. The objective of this study was to further investigate the effects of this hyperglycemia‐induced glycosylation of AT1R. A two‐week high glucose treatment (25 mM) of rat cardiac microvascular endothelial cells (RCMVECs) displayed impaired function by tube formation analysis (TFA) in comparison to a normal glucose treatment (4.5 mM). The decrease tube formation was further exacerbated by the addition of a subpressor dose of AngII. To further test the influence of hyperglycemia‐induced AT1R N‐glycosylation on signaling we treated RCMVECs with the PNGaseF enzyme for N‐glycosylation removal at the cell surface in combination with functional assays and AngII treatment under varying glycemic conditions. The efficacy of this treatment was tested through TFA and measurements of ERK1/2 activation through phosphorylation (known contributor to AT1R signaling). We observed a decrease in tube length, tube area, and number of branch points in a high glucose environment plus Ang‐II and were able to recover functionality with the addition of PNGaseF. While normal glucose treated cells had shown ERK1/2 activation, no observable increases in ERK1/2 were observed in response to AngII in the high glucose conditions. In the high glucose plus AngII treatment group we also observed a significant decrease in Vegfr2 gene expression compared to the normal glucose plus AngII treatment group. Further analysis is currently underway to further validate this mechanism of AT1R signaling impairment, but the data we have so far lead us to believe that hyperglycemia‐induced glycosylation blocks the AT1R active site to decrease functionality. It is possible that the hyperglycemia‐induced glycosylation of AT1R inhibits AngII binding, allowing for a higher rate of binding in the AT2R to further impair endothelial cell functionality.Support or Funding InformationSupport for this project has been provided by the National Institutes of Health National Institute of Diabetes and Digestive and Kidney Diseases (K01‐DK105043 to BRH) and the Department of Biomedical Engineering at the Medical College of Wisconsin and Marquette University.

Overexpression of microRNA-136-3p Alleviates Myocardial Injury in Coronary Artery Disease via the Rho A/ROCK Signaling Pathway

Coronary artery disease (CAD) is a cardiovascular disease that poses a fatal threat to human health, and the identification of potential biomarkers may help to delineate its pathophysiological mechanisms. Accumulating evidence has implicated microRNAs (miRNAs) in the pathogenesis and development of cardiovascular diseases. The present study aims to identify the expression of miRNA-136-3p (miR-136-3p) in CAD and further investigate its functional relevance in myocardial injury both in vitro and in vivo. Initially, CAD models were induced in rats by high-fat diet and intraperitoneal injection of pituitrin. Next, the effect of overexpressed miR-136-3p on cardiac function and pathological damage in myocardial tissue, cardiomyocyte apoptosis, oxidative stress and inflammatory response were assessed in CAD rats. Rat cardiac microvascular endothelial cells (CMECs) were isolated and cultured by the tissue explant method, and the CMEC injury model was induced by homocysteine (HCY). The function of miR-136-3p in vitro was further evaluated. miR-136-3p was poorly expressed in the myocardial tissue of CAD rats and CMEC injury models. In vivo assays indicated that overexpressed miR-136-3p could improve cardiac function and alleviate pathological damage in myocardial tissue, accompanied by reduced oxidative stress and inflammatory response. Moreover,in vitro assays suggested that overexpression of miR-136-3p enhanced proliferation and migration while inhibiting apoptosis of HCY-stressed CMECs. Notably, we revealed that EIF5A2 was a target gene of miR-136-3p, and miR-136-3p inhibited EIF5A2 expression and activation of the Rho A/ROCK signaling pathway. In conclusion, the overexpression of miR-136-3p could potentially impede myocardial injury in vitro and in vivo in CAD through the blockade of the Rho A/ROCK signaling pathway, highlighting a potential miR-136-3p functional relevance in the treatment of CAD.

Oroxylin A Reduces Vasoconstriction in Rat Aortic Rings through Promoting NO Production and NOS Protein Expression via Estrogen Receptor Signal Pathway.

Oroxylin A, a flavonoid, is naturally produced in many medicinal plants. Our previous study identified it as a phytoestrogen. Based on this, the present study investigated its vasoconstriction reducing effects and whether the action was mediated by the estrogen receptor (ER) signal pathway. Long-term in vitro treatment with oroxylin A reduced Ach-induced vasorelaxation and NE-mediated or KCl-mediated contractile responses in rat aortic rings. These effects were interfered by an ER inhibitor ICI 182,780. Rat cardiac microvascular endothelial cells (CMECs) and aortic vascular smooth muscle cells (VSMCs) were used to study the possible underlying mechanisms. Oroxylin A activated the ER signal pathway. In CMECs, it increased NO production and eNOS protein expression. In VSMCs, it promoted NO production and iNOS protein expression. These effects were also inhibited by ICI 182,780. Besides, oroxylin A stimulated ERα and ERβ protein expression in CMECs and VSMCs. All these findings suggest that the ER signal pathway takes part in the vasoconstriction reducing effects of oroxylin A.

Influence of a Hyperglycemic Microenvironment on a Diabetic Versus Healthy Rat Vascular Endothelium Reveals Distinguishable Mechanistic and Phenotypic Responses.

Hyperglycemia is a critical factor in the development of endothelial dysfunction in type 2 diabetes mellitus (T2DM). Whether hyperglycemic states result in a disruption of similar molecular mechanisms in endothelial cells under both diabetic and non-diabetic states, remains largely unknown. This study aimed to address this gap in knowledge through molecular and functional characterization of primary rat cardiac microvascular endothelial cells (RCMVECs) derived from the T2DM Goto-Kakizaki (GK) rat model in comparison to control Wistar-Kyoto (WKY) in response to a normal (NG) and hyperglycemic (HG) microenvironment. GK and WKY RCMVECs were cultured under NG (4.5 mM) and HG (25 mM) conditions for 3 weeks, followed by tandem mass spectrometry (MS/MS), qPCR, tube formation assay, microplate based fluorimetry, and mitochondrial respiration analyses. Following database matching and filtering (false discovery rate ≤ 5%, scan count ≥ 10), we identified a greater percentage of significantly altered proteins in GK (7.1%, HG versus NG), when compared to WKY (3.5%, HG versus NG) RCMVECs. Further stringent filters (log2ratio of > 2 or < –2, p < 0.05) followed by enrichment and pathway analyses of the MS/MS and quantitative PCR datasets (84 total genes screened), resulted in the identification of several molecular targets involved in angiogenic, redox and metabolic functions that were distinctively altered in GK as compared to WKY RCMVECs following HG exposure. While the expression of thirteen inflammatory and apoptotic genes were significantly increased in GK RCMVECs under HG conditions (p < 0.05), only 2 were significantly elevated in WKY RCMVECs under HG conditions. Several glycolytic enzymes were markedly reduced and pyruvate kinase activity was elevated in GK HG RCMVECs, while in mitochondrial respiratory chain activity was altered. Supporting this, TNFα and phorbol ester (PMA)-induced Reactive Oxygen Species (ROS) production were significantly enhanced in GK HG RCMVECs when compared to baseline levels (p < 0.05). Additionally, PMA mediated increase was the greatest in GK HG RCMVECs (p < 0.05). While HG caused reduction in tube formation assay parameters for WKY RCMVECs, GK RCMVECs exhibited impaired phenotypes under baseline conditions regardless of the glycemic microenvironment. We conclude that hyperglycemic microenvironment caused distinctive changes in the bioenergetics and REDOX pathways in the diabetic endothelium as compared to those observed in a healthy endothelium.

MicroRNA-128 confers protection against cardiac microvascular endothelial cell injury in coronary heart disease via negative regulation of IRS1.

Cardiac microvascular endothelial cells (CMECs) play a critical role in the physiological regulation of coronary blood flow and its dysfunction is associated with myocardium ischemic injury. This study was performed to clarify the effect of microRNA-128 (miR-128) on the CMEC injury in coronary heart disease (CHD) by binding to insulin receptor substrate 1 (IRS1). The rat CMECs were cultured by explant culture method and identified by CD31 immunofluorescence assay. CMECs were treated with homocysteine (Hcy), which underwent stress of CHD, followed by treatment of miR-128 mimics/inhibitors or IRS1 siRNA. Expression of miR-128, IRS1, and vascular endothelial growth factor (VEGF) was determined. The viability, apoptosis, migration ability, and tube formation ability of CMECs were evaluated. The superoxide dismutase (SOD), malondialdehyde (MDA), and reactive oxygen species (ROS) of CMECs were evaluated, respectively. In rat CMECs, miR-128 was poorly expressed and IRS1 was highly expressed. Notably, miR-128 targeted and negatively regulated IRS1. Additionally, the treatment with Hcy in CMECs led to reduced viability, migration ability, tube formation, VEGF expression, SOD activity as well as increased cell apoptosis, MDA and ROS levels. The experimental results demonstrated that miR-128 mimics and IRS1 siRNA in rat CMECs promoted viability, migration ability, tube formation, VEGF expression, SOD activity, while repressing cell apoptosis, MDA and ROS levels. MiR-128 inhibitors could reverse the tendencies. Collectively, our study provides evidence that miR-128 targeted and negatively regulated IRS1 expression, whereby the functional injury of CMECs induced by Hcy was ameliorated. Furthermore, protection of miR-128 was stimulated by reducing oxidative stress.

Teneligliptin protects against hypoxia/reoxygenation-induced endothelial cell injury

Cardiovascular complications are the main causes of mortality in diabetic patients. Teneligliptin is a newly developed anti-diabetic agent. It has been reported that teneligliptin has a vascular protective capacity in preclinical studies and diabetes patients. In this study, we investigated the effect of teneligliptin on hypoxia/reoxygenation (H/R)-induced endothelial cell injury in rat cardiac microvascular endothelial cells (CMECs). We showed that teneligliptin pretreatment suppressed H/R-induced production of reactive oxygen species (ROS), NADPH oxidase 4 (NOX4) expression and promoted glutathione production. Teneligliptin pretreatment reduced H/R-induced LDH release and improved cell viability. Teneligliptin significantly relieved the reduction in mitochondrial membrane potential (MMP) induced by H/R. Moreover, teneligliptin suppressed H/R-induced cytokine production and production of vascular adhesion molecules such as IL-1β, TNF-α and ICAM-1. Mechanistically, we showed that teneligliptin inhibited the expression of transcriptional factor Egr-1, which regulates cytokine production and vascular adhesion. Collectively, our data support the notion that teneligliptin is a protective agent in CMECs and has the potential for therapeutic use in the treatments of vascular complications in diabetes patients.

Statins protect diabetic myocardial microvascular endothelial cells from injury

To study the protective effect and mechanism of statins on myocardial microvascular endothelial cells injury in diabetic rats. The rats were administrated with atorvastatin (10 mg/kg/day), rosuvastatin (5 mg/kg/day), or placebo for 1 week. The expression of small GTP-binding protein dissociation stimulator (SmgGDS) was analyzed using western blot. The expression of SmgGDS was also analyzed in cultured rat cardiac microvascular endothelial cells using western blot. The cells were divided into normal glucose group, hyper glucose group, and atorvastatin-treated group. The superoxide dismutase (DHE) staining was used to detect the oxidative stress in the rat cardiac microvascular endothelial cells. The expression of SmgGDS was detected using TUNEL staining after knockout of Akt1 and β1-integrin in cardiac microvascular endothelial cells. The followings were the significant findings of this study: (1) SmgGDS was expressed in aorta endothelium of diabetic rats and cardiac microvascular endothelial cells cultured with high glucose, (2) high glucose increased the production of ROS, the activity of NADPH, and the rate of apoptosis in cardiac microvascular endothelial cells, but after atorvastatin pretreatment, the production of ROS, the activity of NADPH, and the rate of apoptosis in cardiac microvascular endothelial cells decreased, (3) the expression of SmgGDS decreased and the oxidative stress increased after knockdown of Akt1 or β1-integrin. Statins can protect diabetic microvascular endothelial cells from oxidative stress and apoptosis by upregulating SmgGDS partly through β1-integrin/Akt1 pathway.

Qiliqiangxin attenuates hypoxia-induced injury in primary ratcardiac microvascular endothelial cells via promoting HIF-1α-dependent glycolysis.

Protection of cardiac microvascular endothelial cells (CMECs) against hypoxia injury is an important therapeutic strategy for treating ischaemic cardiovascular disease. In this study, we investigated the effects of qiliqiangxin (QL) on primary rat CMECs exposed to hypoxia and the underlying mechanisms. Rat CMECs were successfully isolated and passaged to the second generation. CMECs that were pre‐treated with QL (0.5 mg/mL) and/or HIF‐1α siRNA were cultured in a three‐gas hypoxic incubator chamber (5% CO2, 1% O2, 94% N2) for 12 hours. Firstly, we demonstrated that compared with hypoxia group, QL effectively promoted the proliferation while attenuated the apoptosis, improved mitochondrial function and reduced ROS generation in hypoxic CMECs in a HIF‐1α‐dependent manner. Meanwhile, QL also promoted angiogenesis of CMECs via HIF‐1α/VEGF signalling pathway. Moreover, QL improved glucose utilization and metabolism and increased ATP production by up‐regulating HIF‐1α and a series of glycolysis‐relevant enzymes, including glucose transport 1 (GLUT1), hexokinase 2 (HK2), 6‐phosphofructokinase 1 (PFK1), pyruvate kinase M2 (PKM2) and lactate dehydrogenase A (LDHA). Our findings indicate that QL can protect CMECs against hypoxia injury via promoting glycolysis in a HIF‐1α‐dependent manner. Lastly, the results suggested that QL‐dependent enhancement of HIF‐1α protein expression in hypoxic CMECs was associated with the regulation of AMPK/mTOR/HIF‐1α pathway, and we speculated that QL also improved HIF‐1α stabilization through down‐regulating prolyl hydroxylases 3 (PHD3) expression.

Nestin expression is upregulated in the fibrotic rat heart and is localized in collagen-expressing mesenchymal cells and interstitial CD31(+)- cells.

Renal and lung fibrosis was characterized by the accumulation of collagen-immunoreactive mesenchymal cells expressing the intermediate filament protein nestin. The present study tested the hypothesis that nestin expression was increased in the hypertrophied/fibrotic left ventricle of suprarenal abdominal aorta constricted adult male Sprague-Dawley rats and induced in ventricular fibroblasts by pro-fibrotic peptide growth factors. Nestin protein levels were upregulated in the pressure-overloaded left ventricle and expression positively correlated with the rise of mean arterial pressure. In sham and pressure-overloaded hearts, nestin immunoreactivity was detected in collagen type I(+)-and CD31(+)-cells identified in the interstitium and perivascular region whereas staining was absent in smooth muscle α-actin(+)-cells. A significantly greater number of collagen type I(+)-cells co-expressing nestin was identified in the left ventricle of pressure-overloaded rats. Moreover, an accumulation of nestin(+)-cells lacking collagen, CD31 and smooth muscle α-actin staining was selectively observed at the adventitial region of predominantly large calibre blood vessels in the hypertrophied/fibrotic left ventricle. Angiotensin II and TGF-β1 stimulation of ventricular fibroblasts increased nestin protein levels via phosphatidylinositol 3-kinase- and protein kinase C/SMAD3-dependent pathways, respectively. CD31/eNOS(+)-rat cardiac microvascular endothelial cells synthesized/secreted collagen type I, expressed prolyl 4-hydroxylase and TGF-β1 induced nestin expression. The selective accumulation of adventitial nestin(+)-cells highlighted a novel feature of large vessel remodelling in the pressure-overloaded heart and increased appearance of collagen type I/nestin(+)-cells may reflect an activated phenotype of ventricular fibroblasts. CD31/collagen/nestin(+)-interstitial cells could represent displaced endothelial cells displaying an unmasked mesenchymal phenotype, albeit contribution to the reactive fibrotic response of the pressure-overloaded heart remains unknown.

Fenofibrate protects endothelial cells against the harmful effects of TNF-alpha

Introduction: Fenofibrate exerts pleiotropic effects on endothelial cells (ECs) by, amongst others, increasing nitric oxide (NO) production. We aimed to investigate fenofi brate’s putative beneficial actions in healthy or TNF-alpha-induced dysfunctional ECs. Methods: Fenofi brate-induced pro-vasodilatory responses were assessed in aortic rings (50 - 125μM; 30min) with and without L-NMMA (100μM). Rat cardiac microvascular ECs were treated with fenofibrate (30 and 50μM; 1h). In the pre-treatment experiments, fenofibrate (50μM) was administered one hour before TNFalpha treatment (20ng/ml; 24h). NO-production (DAF-2/DA or Griess assay), mitochondrial ROS-production (MitoSox™), cell viability (propidium iodide staining), and changes in the expression/phosphorylation of critical endothelial proteins were measured by Western blotting. Results: Fenofibrate increased NO-production ˜2-fold in healthy ECs (p<0.05 vs. vehicle). A ˜23% pro-vasodilatory response was induced in aortic rings, which was reversed by L-NMMA (p<0.05 vs. fenofibrate). Fenofibrate pretreatment ameliorated TNF-alpha-induced endothelial dysfunction by reversing the loss of NO, improving oxidative stress, restoring cell viability and preventing caspase-3 activation. Protective effects were underpinned by ˜47% and ˜49% up-regulation of activated eNOS and AMP-kinase, respectively (p<0.05 vs. TNFalpha). Conclusions: Fenofibrate protects TNF-alpha-induced dysfunctional ECs via up-regulated eNOS-NO, reduced oxidative stress and improved cell viability. These novel findings warrant further investigations to explore the potential use of fenofibrate as an anti-endothelial dysfunction therapeutic agent.

Ulinastatin protects against lipopolysaccharide-induced cardiac microvascular endothelial cell dysfunction via downregulation of lncRNA MALAT1 and EZH2 in sepsis.

The present study aimed to evaluate the effects of ulinastatin on the permeability and apoptosis of lipopolysaccharide(LPS)-induced cardiac microvascular endothelial cells(CMVECs), and investigate its molecular mechanisms in sepsis. The sepsis rat model was induced by cecal ligation and puncture(CLP), and rat CMVECs were isolated and treated with LPS or/and ulinastatin. Then, cell permeability was evaluated by transendothelial electrical resistance, reactive oxygen species(ROS) levels were assessed by 2,7-dichlorofluorescein diacetate, cell apoptosis was detected using AnnexinV-FITC apoptosis detection kit, and the expression levels of Bcl-2, Bax, caspase-3, metastasis-associated lung adenocarcinoma transcript1 (MALAT1) and EZH2 were detected by RT-qPCR and/or western blotting. In addition, the relationship of MALAT1 and EZH2 was evaluated by RNA immunoprecipitation(RIP) assay and chromatin immunoprecipitation(ChIP) assay. Compared with LPS-induced CMVECs, treatment with ulinastatin significantly reduced CMVEC permeability and the percentage of apoptotic cells, as well as an increased level of Bcl-2 and inhibited the levels of ROS, caspase-3 and Bax (all p<0.05). In addition, long non-coding RNA(lncRNA) MALAT1 was confirmed to interact with EZH2 in CMVECs. Overexpression of lncRNA MALAT1 and EZH2 was found in the hearts of the sepsis rat and LPS-induced CMVECs, while ulinastatin inhibited the upregulation of lncRNA MALAT1 and EZH2 in the LPS-induced CMVECs (all p<0.05). Ulinastatin protected against LPS-induced CMVEC cell hyperpermeability and apoptosis via downregulation of lncRNA MALAT1 and EZH2 in sepsis.

Antioxidant activities of aqueous extracts from 12 Chinese edible flowers in vitro and in vivo

ABSTRACTThe antioxidant function of edible flowers have attracted increasing interest. However, information is lacking on the impact of edible flowers on oxidative injury including hypoxia-re-oxygenation and hyperlipidemia. The antioxidant activities of aqueous extracts from 12 Chinese edible flowers were assessed in four different antioxidant models, including total antioxidant capacity (TAC), oxygen radical absorbance capacity (ORAC), scavenging hydroxyl radical capacity (SHRC) and scavenging superoxide anion radical capacity (SSARC). Subsequently, the potential antioxidant effects on rat cardiac microvascular endothelial cells (rCMEC) treated with hypoxia-re-oxygenation and hyperlipidemia rats induced by high-fat diet were also evaluated. The highest TAC, ORAC, SHRC and SSARC were Lonicera japonica Thunb., Rosa rugosa Thunb., Chrysanthemum indicum L. and Rosa rugosa Thunb., respectively. Most aqueous extracts of edible flowers exhibited good antioxidant effects on injury of rCMEC induced by hypoxia-re-oxygenation. In addition, the aqueous extracts of Lonicera japonica Thunb., Carthamus tinctorius L., Magnolia officinalis Rehd. et Wils., Rosmarinus officinalis L. and Chrysanthemum morifolium Ramat. could suppress the build-up of oxidative stress by increasing serum superoxide dismutase, glutathion peroxidase, and reducing malonaldehyde concentration in hyperlipidemia rats. These findings provided scientific support for screening edible flowers as natural antioxidants and preventative treatments for oxidative stress-related diseases.

Nupr1/Chop signal axis is involved in mitochondrion-related endothelial cell apoptosis induced by methamphetamine.

Methamphetamine (METH) abuse has been a serious global public health problem for decades. Previous studies have shown that METH causes detrimental effects on the nervous and cardiovascular systems. METH-induced cardiovascular toxicity has been, in part, attributed to its destructive effect on vascular endothelial cells. However, the underlying mechanism of METH-caused endothelium disruption has not been investigated systematically. In this study, we identified a novel pathway involved in endothelial cell apoptosis induced by METH. We demonstrated that exposure to METH caused mitochondrial apoptosis in human umbilical vein endothelial cells and rat cardiac microvascular endothelial cells in vitro as well as in rat cardiac endothelial cells in vivo. We found that METH mediated endothelial cell apoptosis through Nupr1–Chop/P53–PUMA/Beclin1 signaling pathway. Specifically, METH exposure increased the expression of Nupr1, Chop, P53 and PUMA. Elevated p53 expression raised up PUMA expression, which initiated mitochondrial apoptosis by downregulating antiapoptotic Bcl-2, followed by upregulation of proapoptotic Bax, resulting in translocation of cytochrome c (cyto c), an apoptogenic factor, from the mitochondria to cytoplasm and activation of caspase-dependent pathways. Interestingly, increased Beclin1, upregulated by Chop, formed a ternary complex with Bcl-2, thereby decreasing the dissociative Bcl-2. As a result, the ratio of dissociative Bcl-2 to Bax was also significantly decreased, which led to translocation of cyto c and initiated more drastic apoptosis. These findings were supported by data showing METH-induced apoptosis was significantly inhibited by silencing Nupr1, Chop or P53, or by PUMA or Beclin1 knockdown. Based on the present data, a novel mechanistic model of METH-induced endothelial cell toxicity is proposed. Collectively, these results highlight that the Nupr1–Chop/P53–PUMA/Beclin1 pathway is essential for mitochondrion-related METH-induced endothelial cell apoptosis and may be a potential therapeutic target for METH-caused cardiovascular toxicity. Future studies using knockout animal models are warranted to substantiate the present findings.

Hepatocyte growth factor suppresses hypoxia/reoxygenation-induced XO activation in cardiac microvascular endothelial cells.

Hypoxia/reoxygenation (H/R) is one of the cellular stresses in pathological conditions, such as myocardial infarction, stroke and organ transplantation. Oxidative stress caused by reactive oxygen species (ROS) is a crucial element of H/R injury in vascular endothelial cells (ECs). Xanthine oxidase (XO) has been recognized to contribute to H/R injury. Of note, xanthine oxidoreductase is synthesized as xanthine dehydrogenase (XDH) and needs to be converted to XO to become a source of superoxide. Hepatocyte growth factor (HGF) has been found to protect ECs against H/R injury. The relation, however, between HGF and XO in ECs under H/R conditions remains to be determined. Primary cultured rat cardiac microvascular endothelial cells (CMECs) were exposed to 4 h of hypoxia and followed by 1 h of reoxygenation. Generation of ROS and cytosolic Ca2+ concentration was measured by flow cytometry qualification of DCFHDA and fluo-3 AM staining cells, respectively. XDH mRNA was qualified by qRT-PCR analysis. XO activity was determined by colorimetric assay and XO protein levels were determined by Western blot. Cell apoptosis was assessed by caspase-3 activity and Annexin V/PI staining. After H/R, cellular ROS production significantly increased. Both XO activity and XO protein increased after H/R. Cellular ROS elevation was inhibited by allopurinol (a potent XO inhibitor), indicting XO accounting for the generation of ROS after H/R. In addition, XDH mRNA increased after H/R, indicating a de novo XDH synthesis, which needs to be converted to XO to become a source of superoxide. Pretreatment of HGF inhibited the elevation of XO activity and XO protein level after H/R; however, HGF has no effect on the increase of XDH mRNA. We also find an increase of the cytosolic Ca2+ in CMECs after H/R. BAPTA-AM, a cell-permeable Ca2+ chelator, prevented the increase of XO activity and XO protein levels, implicating the elevated cytosolic Ca2+ concentration involvement in XO conversion and XO activation. HGF inhibited the elevation of cytosolic Ca2+ concentration in CMECs after H/R. Furthermore, HGF ameliorated H/R-induced CMECs apoptosis. These findings suggest a novel mechanism whereby HGF inhibited XO-generated ROS production after H/R treatment. H/R induces a de novo synthesis of XDH, the XO precursor. In addition, H/R increases cytosolic Ca2+ concentration and promotes a Ca2+ -involved XO conversion and XO activation. HGF has no effect on the increase of XDH mRNA; however, HGF inhibited the elevation of XO protein level and XO activity after H/R in the post-transcriptional level primarily by inhibiting the increase of cytosolic Ca2+ concentration. HGF protects CMECs from H/R-induced apoptosis by inhibiting the elevation of XO protein level and XO activity.

NADPH oxidase 4 promotes cardiac microvascular angiogenesis after hypoxia/reoxygenation in vitro

Microvascular endothelial cell dysfunction plays a key role in myocardial ischemia/reperfusion (I/R) injury, wherein reactive oxygen species (ROS)-dependent signaling is intensively involved. However, the roles of the various ROS sources remain unclear. This study sought to investigate the role of NADPH oxidase 4 (Nox4) in the cardiac microvascular endothelium in response to I/R injury. Adult rat cardiac microvascular endothelial cells (CMECs) were isolated and subjected to hypoxia/reoxygenation (H/R). Our results showed that Nox4 was highly expressed in CMECs, was significantly increased at both mRNA and protein levels after H/R injury, and contributed to H/R-stimulated increase in Nox activity and ROS generation. Downregulation of Nox4 by small interfering RNA transfection did not affect cell viability or ROS production under normoxia, but exacerbated H/R injury as evidenced by increased apoptosis and inhibited cell survival, migration, and angiogenesis after H/R. Nox4 inhibition also increased prolyl hydroxylase 2 (PHD2) expression and blocked H/R-induced increases in HIF-1α and VEGF expression. Pretreatment with DMOG, a specific competitive PHD inhibitor, upregulated HIF-1α and VEGF expression and significantly reversed Nox4 knockdown-induced injury. However, Nox2 was scarcely expressed and played a minimal role in CMEC survival and angiogenesis after H/R, though a modest upregulation of Nox2 was observed. In conclusion, this study demonstrated a previously unrecognized protective role of Nox4, a ROS-generating enzyme and the major Nox isoform in CMECs, against H/R injury by inhibiting apoptosis and promoting migration and angiogenesis via a PHD2-dependent upregulation of HIF-1/VEGF proangiogenic signaling.

Simvastatin promotes cardiac microvascular endothelial cells proliferation, migration and survival by phosphorylation of p70 S6K and FoxO3a

Restenosis severely limits the overall efficacy of interventions. One of the reasons is the lack of reendothelialization related to inhibition of endothelial cell proliferation and migration since drug is delivered to the luminal surface. Statins can promote angiogenic processes by improving endothelial function, proliferation and migration in cardiac microvascular endothelial cells (CMECs). This study clarified the effect of simvastatin on Akt/mTOR/p70 S6K and FoxO3a signalling pathways in rat CMECs following pretreated with rapamycin. Rapamycin treatment for 24 h inhibited CMECs' proliferation, migration and NO (nitric oxide) secretion, but with increased cell apoptosis and reactive oxygen species (ROS) production. In contrast, simvastatin pretreatment significantly improved proliferation, migration and NO secretion, and inhibited CMECs' apoptosis and ROS production in rapamycin-induced CMECs. Western blot assay showed that, after treatment with simvastatin, the phosphorylation of Akt/mTOR/p70 S6K and FoxO3a were up-regulated in rapamycin-induced CMECs, which was significantly reversed by pretreatment with LY294002. The data suggest that simvastatin inhibits rapamycin-induced CMECs dysfunction and apoptosis, probably through activation of PI3K/Akt/mTOR/p70 S6K and mTOR/FoxO3a signalling pathway in a sequential manner and this pathway may be important in some of the pleiotropic effects of statins.