Activation Of Vascular Endothelial Cells Research Articles

Cdc42 has important roles in postnatal angiogenesis and vasculature formation

Cdc42, a Rho family low molecular weight G protein, has important roles in various cell functions, including cytoskeletal rearrangement, cell adhesion and cell proliferation and differentiation. To investigate the involvement of Cdc42 in the activities of vascular endothelial cells, we generated Cdc42 conditional knockout mice in which Cdc42 was time -specifically deficient in vascular endothelial cells (Cdc42 ​fl/fl; VE-Cad CreERT: Cdc42 cKO). When the Cdc42 gene was deleted after birth, Cdc42 cKO mice were smaller than the control mice, and died between postnatal day 8 (P8) and P10. Necropsy findings confirmed that these mice had various pathological aberrances in the vessels of most organs, such as blood flow congestion and blood cell invasion. Electron microscopic observations also revealed that capillary endothelial cells were detached from the basement membrane as well as phagocytosis of dead endothelial cells induced by macrophages. Moreover, vascular sprouting from aortic rings induced by VEGF-A was diminished in samples from the Cdc42 cKO mice because of an endothelial cell proliferation defect. These results suggest that Cdc42 in vascular endothelial cells has important roles in blood vessel formation after birth.

Canine Angiostrongylus vasorum-Induced Early Innate Immune Reactions Based on NETs Formation and Canine Vascular Endothelial Cell Activation In Vitro.

Simple SummaryAngiostrongylus vasorum is a cardiopulmonary nematode that affects canids, residing in the pulmonary artery and right atrium/ventricle. Due to its location, the parasite will have a close interaction with the different components of the innate immune system, including endothelial cells and polymorphonuclear neutrophils (PMN). Here we evaluated the expression of adhesion molecules of canine aortic endothelial cells (CAEC), and NETs formation by co-culture of freshly isolated canine PMN with A. vasorum L3. Overall, we found distinct inter-donor variations in adhesion molecule expression among CAEC isolates. Additionally, PMN and A. vasorum co-culture induced NETs release without affecting larval viability.Due to its localization in the canine blood stream, Angiostrongylus vasorum is exposed to circulating polymorphonuclear neutrophils (PMN) and the endothelial cells of vessels. NETs release of canine PMN exposed to A. vasorum infective stages (third stage larvae, L3) and early pro-inflammatory immune reactions of primary canine aortic endothelial cells (CAEC) stimulated with A. vasorum L3-derived soluble antigens (AvAg) were analyzed. Expression profiles of the pro-inflammatory adhesion molecules ICAM-1, VCAM-1, P-selectin and E-selectin were analyzed in AvAg-stimulated CAEC. Immunofluorescence analyses demonstrated that motile A. vasorum L3 triggered different NETs phenotypes, with spread NETs (sprNETs) as the most abundant. Scanning electron microscopy confirmed that the co-culture of canine PMN with A. vasorum L3 resulted in significant larval entanglement. Distinct inter-donor variations of P-selectin, E-selectin, ICAM-1 and VCAM-1 gene transcription and protein expression were observed in CAEC isolates which might contribute to the high individual variability of pathological findings in severe canine angiostrongylosis. Even though canine NETs did not result in larval killing, the entanglement of L3 might facilitate further leukocyte attraction to their surface. Since NETs have already been documented as involved in both thrombosis and endothelium damage events, we speculate that A. vasorum-triggered NETs might play a critical role in disease outcome in vivo.

Nur77 Attenuates Inflammasome Activation by Inhibiting Caspase-1 Expression in Pulmonary Vascular Endothelial Cells

Inflammasomes are intracellular multiprotein complexes that help trigger and maintain the inflammatory response as part of the innate immune system. Recently, it has been increasingly recognized that aberrant inflammasome activation is critically involved in endothelial dysfunction in a variety of human diseases, such as atherosclerosis, acute lung injury (ALI), and type 2 diabetes. The molecular mechanisms underlying endothelial inflammasome activation, however, have not been completely elucidated. In the present study, we identified orphan nuclear receptor Nur77 as a novel regulator in controlling inflammasome activation in vascular endothelial cells (ECs). We demonstrated that LPS-induced inflammasome activation was significantly inhibited by ectopic overexpression of Nur77, predominantly through transcriptional suppression of caspase-1 expression in vascular ECs. Consistent with this observation, we found that LPS-induced inflammasome activation was significantly augmented in lung ECs isolated from Nur77-knockout mice. Mechanistically, we showed that Nur77-induced inhibition of caspase-1 expression was due to an inhibition of IRF1 (IFN regulatory factor 1) expression and its subsequent binding to the caspase-1 promoter. Importantly, in a mouse model of LPS-induced ALI, Nur77 knockout led to a marked activation of caspase-1 in the lung, increased alveolar and circulating IL-1β levels, and exacerbated ALI, all of which were substantially inhibited by administration of caspase-1 inhibitor. Together, our results support the presence of an important role for Nur77 in controlling inflammasome activation in vascular ECs and suggest that Nur77 could be a novel therapeutic target for the treatment of human diseases associated with aberrant inflammasome activation, such as ALI and atherosclerosis.

MicroRNA-126 Attenuates the Effect of Chemokine CXCL8 on Proliferation, Migration, Apoptosis, and MAPK-Dependent Signaling Activity of Vascular Endothelial Cells Cultured in a Medium with High Glucose Concentration.

We studied the mechanisms by which microRNA-126 regulates proliferation and migration of human umbilical vein endothelial cells (HUVEC) cultured in a medium with high glucose concentration and treated with chemokine CXCL8. Cell proliferation, apoptosis, and migration were analyzed by the CCK-8 assay, Annexin V-PI staining, and Transwell assay, respectively. The ratios of p-ERK/ERK, p-P38/P38, p-JNK/JNK were determined by ELISA. HUVEC cells cultured in the presence of high glucose concentration (30 mmol/ml) and treated with CXCL8 (50 ng/ml) demonstrated more intensive proliferation, migration, and p-ERK/ERK, p-P38/P38, and p-JNK/JNK ratios and significantly lower apoptosis rate than control cells (high glucose, no treatment) and cells treated with CXCL8 and transfected with microRNA-126-mimic. Thus, microRNA-126 regulates proliferation and migration of HUVEC cells cultured in the presence of high glucose concentrations and treated with CXCL8 through inhibition of MAPK signaling pathway.

Platelets in COVID-19: “innocent by-standers” or active participants?

One of the most dangerous features of the new coronavirus infection caused by the SARS-CoV-2 virus is the tendency of the hemostasis system of patients to excessive thrombus formation. Among the possible causes of this pathology, both the activation of vascular endothelial cells, leading to the exposure of tissue factor by these cells, and direct activation of the plasma hemostasis were named. Besides, there is a significant change in platelet responses to activation, which is not accompanied by significant thrombocytopenia. The mechanism of platelet dysfunction is rather controversial. On the one hand, there are suggestions that platelets can act as a direct “container” for the virus, thus spreading it throughout the body. On the other hand, the presence of viral RNA in platelets has been demonstrated in only one study, while other authors have obtained the opposite result. Another mechanism of the virus's direct effect on platelets is the penetration of the virus into megakaryocytes and the subsequent violation of thrombocytopoiesis. However, three of the four published works show that platelets from patients with SARS-CoV-2 are in an activated state (the so-called platelet pre-activation). This phenomenon can be caused by the direct influence of the virus and the effect of thromboinflammation in the lungs on platelet functions. Here we review the known data and possible causes of the platelet functionality changes observed in patients with SARS-CoV-2.

MMP-9 Mediates Cross-Talk between Neutrophils and Endothelial Cells in Psoriasis

In their report, Chen etal. provide new insights into psoriasis pathogenesis, showing that neutrophil infiltration of skin lesions increases vascular endothelial cell (VEC) activation, leading to cutaneous vasodilation and enhanced vascular permeability. In patients with psoriasis, neutrophil-derived matrix metalloproteinase 9 (MMP-9) plays a pivotal role in VEC barrier dysfunction, via extracellular signal-regulated kinase-1/2 and p38 pathways. Pharmacologic inhibition of MMP-9 in two different models confers reduced cutaneous vasodilation, vascular permeability, and inflammation, suggesting MMP-9 as a target in psoriasis pathogenesis.

Metabolic Reprogramming of Vascular Endothelial Cells: Basic Research and Clinical Applications.

Vascular endothelial cells (VECs) build a barrier separating the blood from the vascular wall. The vascular endothelium is the largest endocrine organ, and is well-known for its crucial role in the regulation of vascular function. The initial response to endothelial cell injury can lead to the activation of VECs. However, excessive activation leads to metabolic pathway disruption, VEC dysfunction, and angiogenesis. The pathways related to VEC metabolic reprogramming recently have been considered as key modulators of VEC function in processes such as angiogenesis, inflammation, and barrier maintenance. In this review, we focus on the changes of VEC metabolism under physiological and pathophysiological conditions.

Antiphospholipid syndrome: diagnosis and management

Antiphospholipid syndrome (APS) is an acquired thrombophilia associated with autoimmunity and is a syndrome that should always be considered when examining patients with thrombosis and pregnancy complications. As per the Sydney criteria, a diagnosis can be established with at least one clinical finding, such as arteriovenous thrombosis and the presence of at least one of the antiphospholipid antibodies (aPL), such as anticardiolipin antibodies (aCL). Moreover, phosphatidylserine-dependent anti-prothrombin antibody and anti-b2GPI-domain 1 antibody are correlated with APS manifestations and enable APS diagnosis. In addition to the inhibition of physiological coagulation inhibitors, such as protein C, the activation of vascular endothelial cells and complement activation by aPL is presumed to be the thrombus mechanism of APS. The mainstay of treatment is anticoagulant therapy with warfarin. For treating APS that has developed by arterial thrombosis, antiplatelet agent alone or in combination with warfarin is considered. In the triple positive aPL (aCL, anti-b2GPI antibodies, and lupus anticoagulant are detected at the same time) cases, sufficient anticoagulant therapy is required. Direct oral anticoagulants are not recommended in cases of triple positive aPL or arterial thrombosis. For patients with catastrophic APS, heparin therapy, plasmapheresis, and steroid pulse therapy are recommended.

Effects of Long Non-Coding RNA MALAT1 Induced by High Glucose on the Biological Characteristics in Stroke

To investigate the effect of high glucose-induced long non-coding ribonucleic acid metastasis associated lung adenocarcinoma transcript 1 on the biological properties of stroke cells. Rat brain micro vascular endothelial cells were cultured in vitroand divided into non-high glucose culture group and high glucose culture group. Long non-coding ribonucleic acid- metastasis associated lung adenocarcinoma transcript 1 was overexpressed and silenced by cell transfection, and the expression levels of long non-coding ribonucleic acid- metastasis associated lung adenocarcinoma transcript 1 and miR-181a-5p were detected by reverse transcription polymerase chain reaction under different culture methods. The Cell TiterBlue assay was also used to analyze the changes of cell viability after various transfection treatments; the double fluorophore reporter gene assay was used to verify the targeting effect of long non-coding ribonucleic acid- metastasis associated lung adenocarcinoma transcript 1 and miR-181a-5p. The results showed that non-high glucose cultured rat brain micro vascular endothelial cells significantly down-regulated the expression of Long non-coding ribonucleic acid- metastasis associated lung adenocarcinoma transcript 1 compared to high glucose cultured rat brain micro vascular endothelial cells, but the expression level of miR-181a-5p was significantly increased with statistically significant differences (p<0.05). Compared with the control group, the viability of rat brain micro vascular endothelial cells expression long non-coding ribonucleic acid- metastasis associated lung adenocarcinoma transcript 1 was significantly enhanced (p<0.05), while silencing long non-coding ribonucleic acid- metastasis associated lung adenocarcinoma transcript 1 significantly inhibit the viability of rat brain micro vascular endothelial cells (p<0.05). Reverse transcription polymerase chain reaction experiments showed that long non-coding ribonucleic acidmetastasis associated lung adenocarcinoma transcript 1 regulated the viability of rat brain micro vascular endothelial cells with miR-181a-5p expression levels at a positive correlation level, while dual fluorophore enzyme reporter gene assays suggested a region of complementary binding between long non-coding ribonucleic acid- metastasis associated lung adenocarcinoma transcript 1 and miR-181a-5p. Long noncoding ribonucleic acid- metastasis associated lung adenocarcinoma transcript 1 can achieve the effect on the activity of rat brain micro vascular endothelial cells under high glucose stimulation by regulating miR-181a-5p.

GPR120 Agonist GW9508 Ameliorated Cellular Senescence Induced by ox-LDL.

Introduction Oxidized low-density lipoprotein (ox-LDL)-induced endothelial senescence is involved in the pathogenesis of atherosclerosis and many cardiovascular diseases. G-protein-coupled receptor 120 (GPR120), a type of orphan G-protein-coupled receptors (GPRs), plays a vital role in mediating anti-inflammatory and insulin-sensitizing effects. The biological function of GPR120 in vascular endothelial cells is largely unknown. Methods The human aortic endothelial cells (HAECs) were treated with ox-LDL (100 μg/mL) in the presence or absence of GW9508 (50 μM) or AH9614 (1 μM) for 24 h. The LDH assay was used to determine cell death. The dihydroethidium (DHE) staining assay was used to measure intracellular levels of reactive oxidative species (ROS), and a senescence β-galactosidase assay kit was used to determine endothelial senescence. Gene and protein expressions were measured using real-time polymerase chain reaction (PCR) and western blot analysis, respectively. Results Ox-LDL treatment decreased the expression of GPR120 by more than half in HAECs. Typically, 100 μg/mL of ox-LDL- induced 35.2% LDH release, which was reduced to 16.9% by 50 μM GW9508, the agonist of GPR120. Importantly, GW9508 relieved cytotoxicity and suppressed the ox-LDL-induced increase in the activity of senescence-associated β-galactosidase (SA-β-Gal) (from 3.3-fold to 1.6-fold of the control group) and the generation of cellular reactive oxidative species (ROS) (from 3.8-fold to 1.6-fold of the control group). Furthermore, we found that GW9508 ameliorated ox-LDL-induced endothelial cell cycle arrest at the G0/G1 phase and the expression of key senescence proteins, including p53 and plasminogen activator inhibitor-1(PAI-1). Mechanistically, we showed that GW9508 promoted ox-LDL-induced transcriptional factor NF-E2-related factor 2 (NRF2) (increase by 47.3%) translocation into the nucleus. The effect of GW9508 is dependent on its receptor GPR120, the blockage of which by its specific antagonist, AH7614, abolished the antisenescence effect of GW9508. Conclusion Collectively, this study revealed the protective effect of GPR120 activation in vascular endothelial cells, implying that GPR120 is a promising therapeutic target for the treatment of cardiovascular diseases.

Mechanism of maggot debridement therapy in promoting wound angiogenesis in patients with diabetic foot ulcer

Mechanism of maggot debridement therapy in promoting wound angiogenesis in patients with diabetic foot ulcer

Von Willebrand factor:antigen and ADAMTS-13 level, but not soluble P-selectin, are risk factors for the first asymptomatic deep vein thrombosis in cancer patients undergoing chemotherapy

BackgroundThere is a high incidence of deep vein thrombosis (DVT) among cancer patients undergoing chemotherapy. Chemotherapy-induced vascular endothelial cell activation (VECA) is characterized by increased plasma levels of von Willebrand factor (vWF) and soluble P-selectin (sP-selectin), leading to the activation of endothelial cells and signaling cascades. The biological role of a disintegrin-like and metalloproteinase with thrombospondin type 1 motif, member 13 (ADAMTS-13) is to control the activity of vWF and consequently the risk of thrombosis. The objective of this study was to investigate the roles of sP-selectin, vWF, and ADAMTS-13 as risk factors for the first episode of DVT in cancer patients undergoing chemotherapy.MethodsThis prospective cohort study was conducted at Dr. Kariadi Hospital, Indonesia, on 40 cancer patients. Prechemotherapy (baseline) and postchemotherapy sP-selectin, vWF antigen (vWF:Ag), and ADAMTS-13 plasma levels were determined with ELISAs before and 3 months after chemotherapy. The clinical characteristics of the patients, cancer type, cancer stage, chemotherapy regimen, ABO blood type, D-dimer level and Khorana risk score were also analyzed using logistic regression. Patients were observed for the possibility of developing DVT during chemotherapy.ResultsDVT was confirmed in 5 patients (12.5%) after a period of 3 months. In patients with DVT, sP-selectin and vWF were significantly higher while ADAMTS-13 was lower than in their counterparts. The levels of baseline vWF:Ag and ADAMTS-13, with cut-off points ≥ 2.35 IU/mL and ≤ 1.03 IU/mL, respectively, were found to independently predict the incidence of DVT. In the multivariate logistic regression analysis, the relative risk (RR) for DVT in patients with high vWF:Ag was 3.80 (95% CI 1.15–12.48, p = 0.028), and that for patients with low ADAMTS-13 was 2.67 (95% CI 1.22–23.82, p = 0.005). The vWF:Ag/ADAMTS-13 ratio and both vWF:Ag and ADAMTS-13 dynamics during treatment were also able to differentiate those with prospective DVT. However, sP-selectin and other covariates showed no statistical significance.ConclusionWe found that prechemotherapy plasma levels of vWF:Ag ≥ 2.35 IU/mL and ADAMTS-13 ≤ 1.03 IU/mL are independent risk factors for DVT incidence among cancer patients.

MiR-223-3p inhibits rTp17-induced inflammasome activation and pyroptosis by targeting NLRP3.

The incidence of syphilis caused by Treponema pallidum subsp pallidum (T pallidum) infection is accompanied by inflammatory injuries of vascular endothelial cells. Studies have revealed that T pallidum infection could induce inflammasome activation and pyroptosis in macrophages. MicroRNA‐223‐3p (miR‐223‐3p) was reported to be a negative regulator in inflammatory diseases. The present study aimed to explore whether miR‐223‐3p regulates T pallidum‐induced inflammasome activation and pyroptosis in vascular endothelial cells, and determine the mechanisms which underlie this process. MiR‐223‐3p levels in syphilis and control samples were determined. The biological function of miR‐223‐3p in the NLRP3 inflammasome and pyroptosis was evaluated in T pallidum‐infected human umbilical vein endothelial cells (HUVECs). We observed a dramatic decrease in miR‐223‐3p levels in syphilis patients (n = 20) when compared to healthy controls (n = 20). Moreover, miR‐223‐3p showed a notable inhibitory effect on recombinant Tp17 (rTP17)‐induced caspase‐1 activation, resulting in decrease in IL‐1β production and pyroptosis, which was accompanied by the release of lactate dehydrogenase (LDH) in HUVECs. Additionally, the dual‐luciferase assay confirmed that NLRP3 is a direct target of miR‐223‐3p. Moreover, NLRP3 overexpression or knockdown largely blocked the effects of miR‐223‐3p on T pallidum‐induced inflammasome activation and pyroptosis in HUVECs. Most importantly, a notable negative correlation was observed between miR‐223‐3p and NLRP3, caspase‐1, and IL‐1β, respectively, in the serum of syphilis patients and healthy controls. Taken together, our results reveal that miR‐223‐3p targets NLRP3 to suppress inflammasome activation and pyroptosis in T pallidum‐infected endothelial cells, implying that miR‐223‐3p could be a potential target for syphilis patients.

Short-term exposure to air pollution and novel markers of cardiovascular effect: a repeated measures study in the Multi-Ethnic Study of Atherosclerosis (MESA)

Background: Several pathophysiologic mechanisms have been proposed to underlie the associations between ambient air pollutants and cardiovascular disease. We employed a repeated measures design to investigate the short-term associations of outdoor concentrations of four air pollutants – particulate matter smaller than 2.5 micrometers in diameter (PM2.5), nitrogen dioxide (NO2), ozone (O3) and sulfur dioxide (SO2) – with two blood markers involved in vascular effects of oxidative stress, soluble lectin-like oxidized LDL receptor-1 (sLOX-1) and nitrite, using data from the MESA study.Methods: 740 participants who submitted blood samples at three MESA exams between 2002 and 2007 were included. sLOX-1 and nitrite were measured in plasma samples. Daily concentrations of PM2.5, NO2, O3 and SO2 0-7 days prior to blood draw at each exam were estimated from central monitors in the six MESA regions, pre-adjusted using splines of meteorology, indicators for day of the week, and splines of site-specific time trend. Unconstrained distributed lag linear mixed effect models and generalized estimating equations were used to estimate net effects over several days with adjustment for demographic, socioeconomic and behavioral factors.Results: Median detectable nitrite and sLOX-1 concentrations were 24.7 umol/L and 94.5 pg/ml, respectively. Higher short-term PM2.5 concentrations, but not other pollutants, were associated with elevated sLOX-1 level analyzed both as a continuous outcome (percent change per interquartile increase: 18.5%, 95%CI: 2.4-37.2%) and dichotomized at the median (odds ratio per interquartile increase: 1.21, 95%CI: 1.01-1.44); the finding was not meaningfully changed after adjustment for additional covariates or in several sensitivity analyses. Pollutant concentrations were not associated with nitrite levels. Conclusion: This study adds to the evidence that short-term PM2.5 exposure is associated with higher sLOX-1 and supports the mechanistic hypothesis that oxidative modification of endogenous phospholipids in the lung by PM2.5 drives vascular endothelial cell activation via cell surface pattern recognition receptors.

Allicin can suppress the activity of vascular endothelial cells probably by regulating JAK2/STAT3 pathway.

Whether allicin can suppress the angiogenesis via inhibiting the activity of vascular endothelial cells (VECs) in preventing epidural hypertrophic scars remains unknown. VECs were treated by allicin at a gradient of concentrations. Cell activity was measured by CCK-8 assay, scratch assay and flow cytometry. Reverse-transcription PCR and Western Blot were used to measure the expression levels of relevant genes and proteins. After treated with allicin at concentrations of 0, 25, 50 and 100mg/L, the viability of VECs significantly decreased at 24h (p < 0.001*) and 48h (p < 0.001*), and migration rate significantly decreased in scratch assay (p = 0.017*) and in Transwell assay (p = 0.021*). As the concentrations of allicin increased, the apoptosis rate of VECs rose up (p = 0.018*). There was no significant difference on cell numbers at S phase (p = 0.25), but cell numbers at G1 phase decreased (p = 0.039*) and at G2 phase increased (p = 0.047*). With the increase of allicin concentrations, the ability of tube formation for VECs significantly decreased (p < 0.001*). Comparing with control group, the expression of PCNA and BCL-2 decreased (p < 0.001*), while the expression of BAX increased significantly (p < 0.001*). Regarding to JAK2/STAT3 pathway, the expression levels of JAK3 and STAT3 decreased significantly with the increase of allicin concentrations (p < 0.001*). Allicin can suppress the activity of VECs probably by regulating JAK2/STAT3 pathway.

Pericyte coverage of cardiac capillaries is decreased in diabetic obese mice

Heart failure with preserved ejection fraction (HFpEF) which results from diastolic dysfunction is a growing epidemiologic problem. The pathophysiology of this disease is poorly understood nevertheless a theory suggests a central role of microvessel disease. Our goal is to investigate the role of pericyte in the pathophysiology of cardiac microvessel disease and diastolic dysfunction. Pericytes are mural cells known to be essential for microvascular integrity especially in the brain, and in the retina. We have used Leptin receptor deficient (Leprdb/db) female mice as a model of HFpEF and assessed pericyte coverage of cardiac capillaries. Besides, to identify factors that may cause pericyte loss in the heart, we performed, cell viability assays using cultured human pericytes from placenta. In Leprdb/db mice, end-diastolic pressure (EDP) signing diastolic dysfunction is significantly increased from 3 month of age [12.0 ± 1.4 vs 4.4 ± 0.4 mmHg ( P < 0.001)]. It is correlated with signs of microvessel disease especially vascular leakage and endothelial cell activation. Interestingly, we found that pericyte coverage of cardiac capillaries is significantly reduced in Leprdb/db female mice from 6 weeks of age [93.88 ± 2.30 vs 54.67 ± 5.32 ( P < 0.001)]. Notably, this anomaly precedes the onset of endothelial dysfunction and diastolic dysfunction. Cell culture assay showed that oxidized LDLs but not high glucose or TNFα significantly decrease pericyte survival [100.00 ± 6.48 vs 76.22 ± 4.49 with 30 μg/mL ( P < 0.01)]. Our results show that pericyte coverage of capillaries is significantly decreased in the heart of diabetic obese mice probably because of increased oxidized LDL and support that degeneration of cardiac pericytes may contribute to the development of cardiac microvessel disease and diastolic dysfunction in diabetic obese mice and may be due to oxidized LDL.

The G-protein-coupled chemoattractant receptor Fpr2 exacerbates neuroglial dysfunction and angiogenesis in diabetic retinopathy.

Diabetic retinopathy (DR) as a retinal neovascularization‐related disease is one of the leading causes of irreversible blindness in patients. The goal of this study is to determine the role of a G‐protein‐coupled chemoattractant receptor (GPCR) FPR2 (mouse Fpr2) in the progression of DR, in order to identify novel therapeutic targets. We report that Fpr2 was markedly upregulated in mouse diabetic retinas, especially in retinal vascular endothelial cells, in associated with increased number of activated microglia and Müller glial cells. In contrast, in the retina of diabetic Fpr2 −/− mice, the activation of vascular endothelial cells and glia was attenuated with reduced production of proinflammatory cytokines. Fpr2 deficiency also prevented the formation of acellular capillary during diabetic progression. Furthermore, in oxygen‐induced retinopathy (OIR) mice, the absence of Fpr2 was associated with diminished neovasculature formation and pathological vaso‐obliteration region in the retina. These results highlight the importance of Fpr2 in exacerbating the progression of neuroglial degeneration and angiogenesis in DR and its potential as a therapeutic target.

NLRP3 Inflammasome Activation in Lung Vascular Endothelial Cells Contributes to Intestinal Ischemia/Reperfusion-Induced Acute Lung Injury.

Intestinal ischemia/reperfusion (I/R) injury is a life-threatening complication that leads to inflammation and remote organ damage. The NLRP3 inflammasome regulates the caspase-1-dependent release of IL-1β, an early mediator of inflammation after I/R injury. In this study, we investigated the role of the NLRP3 inflammasome in mice with intestinal I/R injury. Deficiency of NLRP3, ASC, caspase-1/11, or IL-1β prolonged survival after intestinal I/R injury, but neither NLRP3 nor caspase-1/11 deficiency affected intestinal inflammation. Intestinal I/R injury caused acute lung injury (ALI) characterized by inflammation, reactive oxygen species generation, and vascular permeability, which was markedly improved by NLRP3 deficiency. Bone marrow chimeric experiments showed that NLRP3 in non-bone marrow-derived cells was the main contributor to development of intestinal I/R-induced ALI. The NLRP3 inflammasome in lung vascular endothelial cells is thought to be important to lung vascular permeability. Using mass spectrometry, we identified intestinal I/R-derived lipid mediators that enhanced NLRP3 inflammasome activation in lung vascular endothelial cells. Finally, we confirmed that serum levels of these lipid mediators were elevated in patients with intestinal ischemia. To our knowledge, these findings provide new insights into the mechanism underlying intestinal I/R-induced ALI and suggest that endothelial NLRP3 inflammasome-driven IL-1β is a novel potential target for treating and preventing this disorder.

The Role of Methionine Aminopeptidase 2 in Lymphangiogenesis.

During the metastasis process, tumor cells invade the blood circulatory system directly from venous capillaries or indirectly via lymphatic vessels. Understanding the relative contribution of each pathway and identifying the molecular targets that affect both processes is critical for reducing cancer spread. Methionine aminopeptidase 2 (MetAp2) is an intracellular enzyme known to modulate angiogenesis. In this study, we investigated the additional role of MetAp2 in lymphangiogenesis. A histological staining of tumors from human breast-cancer donors was performed in order to detect the level and the localization of MetAp2 and lymphatic capillaries. The basal enzymatic level and activity in vascular and lymphatic endothelial cells were compared, followed by loss of function studies determining the role of MetAp2 in lymphangiogenesis in vitro and in vivo. The results from the histological analyses of the tumor tissues revealed a high MetAp2 expression, with detectable sites of co-localization with lymphatic capillaries. We showed slightly reduced levels of the MetAp2 enzyme and MetAp2 mRNA expression and activity in primary lymphatic cells when compared to the vascular endothelial cells. The genetic and biochemical manipulation of MetAp2 confirmed the dual activity of the enzyme in both vascular and lymphatic remodulation in cell function assays and in a zebrafish model. We found that cancer-related lymphangiogenesis is inhibited in murine models following MetAp2 inhibition treatment. Taken together, our study provides an indication that MetAp2 is a significant contributor to lymphangiogenesis and carries a dual role in both vascular and lymphatic capillary formation. Our data suggests that MetAp2 inhibitors can be effectively used as anti-metastatic broad-spectrum drugs.

Dietary nitrate attenuated endothelial dysfunction and atherosclerosis in apolipoprotein E knockout mice fed a high-fat diet: A critical role for NADPH oxidase

Nitric oxide (NO) deficiency and NADPH oxidase plays key roles in endothelial dysfunction and atherosclerotic plaque formation. Recent evidence demonstrates that nitrate-nitrite-NO pathway in vivo exerts beneficial effects upon the cardiovascular system. We aimed to investigate the effects of dietary nitrate on endothelial function and atherosclerosis in apolipoprotein E knockout (ApoE−/-) mice fed a high-fat diet. It was shown that dietary nitrate significantly attenuated aortic endothelial dysfunction and atherosclerosis in ApoE−/- mice. Mechanistic studies revealed that dietary nitrate significantly improved plasma nitrate/nitrite, inhibited vascular NADPH oxidase activity and oxidative stress in ApoE−/- mice, while xanthine oxidoreductase (XOR) expression and activity was enhanced in ApoE−/- mice in comparison with wide type animals. These beneficial effects of nitrate in ApoE−/- mice were abolished by PTIO (NO scavenger) and significantly prevented by febuxostat (XOR inhibitor). In the presence of nitrate, no further effect of apocynin (NADPH oxidase inhibitor) was observed, suggesting NADPH oxidase as a possible target. In vitro, NO donor significantly inhibited NADPH oxidase activity in vascular endothelial cells via the induction of heme oxygenase-1. Altogether, boosting this nitrate-nitrite-NO signaling pathway resulted in the decreases of vascular NADPH oxidase-derived oxidative stress and endothelial dysfunction, and consequently protected ApoE−/- mice against atherosclerosis. These findings may have novel nutritional implications for the preventive and therapeutic strategies against vascular endothelial dysfunction in atherosclerotic disease.