The angiopoietin:Tie 2 interaction: a potential target for future therapies in human vascular disease

An Overview of Cancer Biology, Pathophysiological Development and It's Treatment Modalities: Current Challenges of Cancer anti-Angiogenic Therapy

A number of conditions and factors can cause the transformation of normal cells in the body into malignant tissue by changing the normal functions of a wide range of regulatory, apoptotic, and signal transduction pathways. Despite the current deficiency in fully understanding the mechanism of cancer action accurately and clearly, numerous genes and proteins that are causally involved in the initiation, progression, and metastasis of cancer have been identified. But due to the lack of space and the abundance of details on this complex topic, we have emphasized here more recent advances in our understanding of the principles implied tumor cell transformation, development, invasion, angiogenesis, and metastasis. Inhibition of angiogenesis is a significant strategy for the treatment of various solid tumors, that essentially depend on cutting or at least limiting the supply of blood to micro-regions of tumors, leading to pan-hypoxia and pan-necrosis inside solid tumor tissues. Researchers have continued to enhance the efficiency of anti-angiogenic drugs over the past two decades, to identify their potential in the drug interaction, and to discover reasonable interpretations for possible resistance to treatment. In this review, we have discussed an overview of cancer history and recent methods use in cancer therapy, focusing on anti-angiogenic inhibitors targeting angiogenesis formation. Further, this review has explained the molecular mechanism of action of these anti-angiogenic inhibitors in various tumor types and their limitations use. In addition, we described the synergistic mechanisms of immunotherapy and anti-angiogenic therapy and summarizes current clinical trials of these combinations. Many phase III trials found that combining immunotherapy and anti-angiogenic therapy improved survival. Therefore, targeting the source supply of cancer cells to grow and spread with new anti-angiogenic agents in combination with different conventional therapy is a novel method to reduce cancer progression. The aim of this paper is to overview the varying concepts of cancer focusing on mechanisms involved in tumor angiogenesis and provide an overview of the recent trends in anti-angiogenic strategies for cancer therapy.

Role of Angiopoietin/Tie2 System in Sepsis: A Potential Therapeutic Target

Sepsis is a disorder of host response caused by severe infection that can lead to life-threatening organ dysfunction. There is no specific treatment for sepsis. Although there are many different pathogens that can cause sepsis, endothelial dysfunction is a frequent mechanism resulting in vascular leakage and coagulation problem. Recent studies on the regulatory pathways of vascular endothelium have shown that the disturbance of angiopoietin (Ang) /Tie2 axis can induce endothelial cell activation, which is the core pathogenesis of sepsis. In this review, we aim to discuss the regulation of Ang/Tie2 axis and the biomarkers involved in the context of sepsis. Also, we attempt to explore the prospective and feasibility of Ang/Tie2 axis as a potential target for sepsis intervention to improve clinical outcomes.

Targeting VEGF using Bevacizumab attenuates sepsis-induced liver injury in a mouse model of cecal ligation and puncture

Sepsis, a life-threatening condition resulting from an uncontrolled host response to infection, often leads to severe liver damage and remains a significant cause of mortality in critically ill patients despite advances in antibiotic therapy and resuscitation. Bevacizumab, a neutralizing antibody targeting vascular endothelial growth factor (VEGF), is approved for treating certain cancers. However, its potential impact on sepsis-related liver injury is not well understood. This study aimed to explore the potential hepatoprotective effect of Bevacizumab on sepsis-induced liver injury. Twenty-four mice were divided into four groups: a sham group subjected to a midline incision only, a cecal ligation and puncture induction (CLP) group, a vehicle-treated group that received a vehicle one hour before CLP induction, and a Bevacizumab-treated group that received Bevacizumab one hour before CLP induction. Blood samples were collected, and angiopoietin-2 (ANGPT2), alanine transaminase (ALT), and aspartate transaminase (AST) serum levels were measured. Liver tissue homogenates were analyzed for IL-6, TNFα, intracellular adhesion molecule (ICAM-1), macrophage inhibitory factor (MIF), vascular endothelial growth factor (VEGF), F2-isoprostane, and caspase-11 levels. A histological examination was performed to assess the extent of liver damage. Mice exposed to CLP had high levels of the biomarkers mentioned above with a high degree of liver injury compared to the sham group. In contrast, treatment with Bevacizumab notably reduced these markers and mitigated liver damage. In conclusion, Bevacizumab may be a protective agent against sepsis-induced liver injury.

Overfit deep neural network for predicting drug-target interactions

Drug-target interactions (DTIs) prediction is an important step in drug discovery. As traditional biological experiments or high-throughput screening are high cost and time-consuming, many deep learning models have been developed. Overfitting must be avoided when training deep learning models. We propose a simple framework, called OverfitDTI, for DTI prediction. In OverfitDTI, a deep neural network (DNN) model is overfit to sufficiently learn the features of the chemical space of drugs and the biological space of targets. The weights of trained DNN model form an implicit representation of the nonlinear relationship between drugs and targets. Performance of OverfitDTI on three public datasets showed that the overfit DNN models fit the nonlinear relationship with high accuracy. We identified fifteen compounds that interacted with TEK, a receptor tyrosine kinase contributing to vascular homeostasis, and the predicted AT9283 and dorsomorphin were experimentally demonstrated as inhibitors of TEK in human umbilical vein endothelial cells (HUVECs).

The circ_006573/miR-376b-3p Axis Advances Spinal Cord Functional Recovery after Injury by Modulating Vascular Regeneration

Abnormal expression of non-coding RNAs after spinal cord injury (SCI) is associated with pathophysiological outcomes. We bioinformatically predicted a circRNA-miRNA-mRNA axis in SCI. A total of 4690 mRNAs, 17 miRNAs, and 3928 circRNAs were differentially expressed, with co-expressed RNAs predicted to regulate pathways related to wound healing. Among the most highly differentially expressed circRNAs, circ_006573, but not circ_016395, weakened the viability and migration of rat aortic endothelial cells, and its biological effects were rescued with miR-376b-3p mimics. Furthermore, circ_006573 overexpression induced changes in Cebpb, IL-18, and Plscr1 expression that were reversed by miR-376b-3p. In a rat model, circ_006573 shRNA administration improved the pathological manifestations of SCI and ameliorated motor function. Moreover, the expression of CD31, CD34, and VEGF-A in spinal cord tissues was significantly elevated after circ_006573 shRNA treatment, indicating that circ_006573 may be involved in vascular regeneration and functional recovery after SCI. Thus, the circ_006573-miR-376b-3p axis offers a foundation for understanding pathophysiological mechanisms and predicting strategies for treating SCI.

Signaling pathways and intervention for therapy of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) represents one of the fastest growing epidemic metabolic disorders worldwide and is a strong contributor for a broad range of comorbidities, including vascular, visual, neurological, kidney, and liver diseases. Moreover, recent data suggest a mutual interplay between T2DM and Corona Virus Disease 2019 (COVID-19). T2DM is characterized by insulin resistance (IR) and pancreatic β cell dysfunction. Pioneering discoveries throughout the past few decades have established notable links between signaling pathways and T2DM pathogenesis and therapy. Importantly, a number of signaling pathways substantially control the advancement of core pathological changes in T2DM, including IR and β cell dysfunction, as well as additional pathogenic disturbances. Accordingly, an improved understanding of these signaling pathways sheds light on tractable targets and strategies for developing and repurposing critical therapies to treat T2DM and its complications. In this review, we provide a brief overview of the history of T2DM and signaling pathways, and offer a systematic update on the role and mechanism of key signaling pathways underlying the onset, development, and progression of T2DM. In this content, we also summarize current therapeutic drugs/agents associated with signaling pathways for the treatment of T2DM and its complications, and discuss some implications and directions to the future of this field.

Polymorphisms in TIE2 and ANGPT-1 genes are associated with protection against diabetic retinopathy in a Brazilian population

Objective

The objective of this study was to investigate the association between SNPs in the TIE2 and ANGPT-1 genes and diabetic retinopathy (DR).

Subjects and methods

This study comprised 603 patients with type 2 diabetes mellitus (T2DM) and DR (cases) and 388 patients with T2DM for more than 10 years and without DR (controls). The TIE2 rs639225 (A/G) and rs638203 (A/G) SNPs and the ANGPT-1 rs4324901 (G/T) and rs2507800 (T/A) SNPs were genotyped by real-time PCR using TaqMan MGB probes.

Results

The G/G genotype of the rs639225/TIE2, the G/G genotype of the rs638203/ TIE2 and the T allele of the rs4324901/ANGPT-1 SNPs were associated with protection against DR after adjustment for age, glycated hemoglobin, gender, and presence of hypertension (P = 0.042, P = 0.003, and P = 0.028, respectively). No association was found between the rs2507800/ANGPT-1 SNP and DR.

Conclusion

We demonstrated, for the first time, the association of TIE2 rs638203 and rsrs939225 SNPs and ANGPT-1 rs4324901 SNP with protection against DR in a Brazilian population.

Potential Biomarkers for Early Diagnosis, Evaluation, and Prognosis of Sepsis-Induced Coagulopathy

Sepsis-induced coagulopathy (SIC) is a life-threatening complication characterized by the systemic activation of coagulation in sepsis. The diagnostic criteria of SIC consist of three items, including Sequential Organ Failure Assessment (SOFA) score, platelet count, and prothrombin time (PT)-international normalized ratio (INR). SIC has a high prevalence and it can lead to a higher mortality rate and longer length of hospital and ICU stay. Thus, the early detection of SIC is extremely important. It is unfortunate that there is still no precise biomarker for early diagnosis and assessment of the prognosis of SIC. We reviewed the current literature and discovered that some potential biomarkers, such as soluble thrombomodulin (sTM), thrombin-antithrombin complex (TAT), tissue plasminogen activator-inhibitor complex (t-PAIC), α2-plasmin inhibitor-plasmin complex (PIC), C-type lectin-like receptor 2 (CLEC-2), neutrophil extracellular traps (NETs), prothrombin fragment 1.2 (F1.2), Angiopoietin-2 (Ang-2), plasminogen activator inhibitor-1 (PAI-1), and tissue inhibitor of metalloproteinase-1 (TIMP-1) may be useful for early diagnosis, evaluation, and prognosis of SIC. Early initiation of treatment without missing any therapeutic opportunities may improve SIC patients' prognosis. Further large-scale clinical studies are still needed to confirm the role of these biomarkers in the diagnosis and prognosis assessment of SIC.

Vascular Distribution and Expression Patterns of Angiogenic Factors in Caruncle during the Early Stage of Pregnancy in Goats (Capra hircus)

The placenta is a temporary maternal−fetal organ, and its maternal placenta (caruncle) is essential for fetal growth and development. The exchange function of the placenta requires vascular development (angiogenesis). However, the angiogenesis of the caruncle is poorly understood in goats during the early stage of pregnancy. Here, we investigated the vascular distribution, mRNA expression of major angiogenic factors, and the methylation levels of ANGPT2 in the goat caruncle. It showed that CAD (capillary area density), CSD (capillary surface density), and APC (area per capillary) increased gradually, while CND (capillary number density) showed an insignificant change, probably due to the variability between animals. The proportion of proliferating cells was observed to be very high (>26%) and increased (p < 0.002) approximately 2-fold from day 20 to 60 of pregnancy. Furthermore, the expression patterns of major angiogenic factors changed during the early stage of pregnancy. Interestingly, we discovered an absolute correlation between the mRNA for ANGPT2, TEK, FGF2, and vascular distribution. Subsequently, we evaluated the DNA methylation of ANGPT2, where we found that mean methylation was negatively correlated with CAD. The methylation at the CpG sites, such as CpG 4/18, CpG 9.10.11, and CpG 15, showed significant changes during the early stage of pregnancy. Thus, our findings suggest that the methylation of ANGPT2 may be involved in the regulation of caruncle angiogenesis during the early stage of pregnancy.

Serum angiopoietin-1 concentration does not distinguish patients with ischaemic stroke from those presenting to hospital with ischaemic stroke mimics

Background

A previous study found that circulating angiopoietin-1 (angpt-1) concentrations were significantly lower in patients who had a recent ischaemic stroke compared to healthy controls. The primary aim of this study was to assess whether serum angpt-1 could be used as a diagnostic test of ischemic stroke in patients presenting to hospital as an emergency. Exploratory analyses investigated the association of proteins functionally related to angpt-1 (angpt-2, Tie-2, matrix metalloproteinase-9 and vascular endothelial growth factors A, C and D) with ischaemic stroke diagnosis.

Methods

Patients presenting to Townsville University Hospital for emergency assessment of stroke-like symptoms were consecutively recruited and provided a blood sample. After assessment by a consultant neurologist, patients were grouped into those who did, or did not have ischaemic stroke. The potential for serum angpt-1 to diagnose ischaemic stroke was assessed using receiver operator characteristic (ROC) curves. Cross-sectional analyses appraised inter-group differences in the serum concentration of other proteins.

Results

One-hundred and twenty-six patients presenting to Townsville University Hospital for emergency assessment of stroke-like symptoms were recruited (median time from symptom onset to hospital presentation: 2.6 (inter-quartile range: 1.2–4.6) hours). Serum angpt-1 had poor ability to diagnose ischaemic stroke in analyses using the whole cohort, or in sensitivity analyses (area under the ROC curve 0.51 (95% CI: 0.41–0.62) and 0.52 (95% CI: 0.39–0.64), respectively). No associations of serum angpt-1 concentration with ischaemic stroke severity, symptom duration or aetiology were observed. Serum concentrations of the other assessed proteins did not differ between patient groups.

Conclusions

Serum angpt-1 concentration is unlikely to be useful for emergency diagnosis of ischaemic stroke.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02918-w.

Ceruletide and Alpha-1 Antitrypsin as a Novel Combination Therapy for Ischemic Stroke

Ischemic stroke is a primary cause of morbidity and mortality worldwide. Beyond the approved thrombolytic therapies, there is no effective treatment to mitigate its progression. Drug repositioning combinational therapies are becoming promising approaches to identify new uses of existing drugs to synergically target multiple disease-response mechanisms underlying complex pathologies. Here, we used a systems biology-based approach based on artificial intelligence and pattern recognition tools to generate in silico mathematical models mimicking the ischemic stroke pathology. Combinational treatments were acquired by screening these models with more than 5 million two-by-two combinations of drugs. A drug combination (CA) formed by ceruletide and alpha-1 antitrypsin showing a predicted value of neuroprotection of 92% was evaluated for their synergic neuroprotective effects in a mouse pre-clinical stroke model. The administration of both drugs in combination was safe and effective in reducing by 39.42% the infarct volume 24 h after cerebral ischemia. This neuroprotection was not observed when drugs were given individually. Importantly, potential incompatibilities of the drug combination with tPA thrombolysis were discarded in vitro and in vivo by using a mouse thromboembolic stroke model with t-PA-induced reperfusion, revealing an improvement in the forepaw strength 72 h after stroke in CA-treated mice. Finally, we identified the predicted mechanisms of action of ceruletide and alpha-1 antitrypsin and we demonstrated that CA modulates EGFR and ANGPT-1 levels in circulation within the acute phase after stroke. In conclusion, we have identified a promising combinational treatment with neuroprotective effects for the treatment of ischemic stroke.

Morin Attenuated Cerebral Ischemia/Reperfusion Injury Through Promoting Angiogenesis Mediated by Angiopoietin-1-Tie-2 Axis and Wnt/β-Catenin Pathway

Cerebral damage following cerebral ischemia/reperfusion injury affects the neurological deficits and motor impairment of stroke patients in the long-term period. Angiogenesis, the essential process for restoration of cerebral blood flow (CBF) in the ischemic brain, promotes the recovery of neurological function following ischemia. The aim of this study was to investigate the long-term effects of morin on angiogenesis and functional outcomes in a middle cerebral artery occlusion (MCAO) and reperfusion model. Male Wistar rats were subjected to MCAO, and they were administered 30 mg/kg of morin at reperfusion via i.p. injection daily for 14 days. Fourteen days after I/R injury, the rats were evaluated for the brain damage, and angiogenic factors involved in Ang1/Tie-2 and Wnt/β-catenin signaling. In addition, at 1, 7, and 14 days after reperfusion, rotarod and pole tests were performed to investigate the functional recovery. We found morin significantly reduced the infarct size, blood-brain barrier (BBB) leakage, and apoptotic cells at 14 days after I/R injury. It also promoted angiogenesis via boosting the expression of angiogenic proteins, such as angiopoietin 1 (Ang1), Tie-2, Wnt3α, β-catenin, and cyclin D1. Morin-mediated angiogenesis was confirmed by a significant increase in microvessel's density in the penumbra area and an increase in von Willebrand factor (vWF) protein expression of the morin-treated rats. Moreover, the rotarod and pole tests also demonstrated morin increased functional recovery in the morin-treated rats compared to the vehicle rats. Therefore, our data exposed that morin promotes angiogenesis and improves functional outcomes in MCAO and reperfusion rats.

Angiopoietin-1 Mimetic Nanoparticles for Restoring the Function of Endothelial Cells as Potential Therapeutic for Glaucoma

A root cause for the development and progression of primary open-angle glaucoma might be the loss of the Schlemm’s canal (SC) cell function due to an impaired Angiopoietin-1 (Angpt-1)/Tie2 signaling. Current therapeutic options fail to restore the SC cell function. We propose Angpt-1 mimetic nanoparticles (NPs) that are intended to bind in a multivalent manner to the Tie2 receptor for successful receptor activation. To this end, an Angpt-1 mimetic peptide was coupled to a poly(ethylene glycol)-poly(lactic acid) (PEG-PLA) block co-polymer. The modified polymer allowed for the fabrication of Angpt-1 mimetic NPs with a narrow size distribution (polydispersity index < 0.2) and the size of the NPs ranging from about 120 nm (100% ligand density) to about 100 nm (5% ligand density). NP interaction with endothelial cells (HUVECs, EA.hy926) as surrogate for SC cells and fibroblasts as control was investigated by flow cytometry and confocal microscopy. The NP–cell interaction strongly depended on the ligand density and size of NPs. The cellular response to the NPs was investigated by a Ca²⁺ mobilization assay as well as by a real-time RT-PCR and Western blot analysis of endothelial nitric oxide synthase (eNOS). NPs with a ligand density of 25% opposed VEGF-induced Ca²⁺ influx in HUVECs significantly which could possibly increase cell relaxation and thus aqueous humor drainage, whereas the expression and synthesis of eNOS was not significantly altered. Therefore, we suggest Angpt-1 mimetic NPs as a first step towards a causative therapy to recover the loss of SC cell function during glaucoma.

LncRNA-mRNA Co-expression Profiles Relative to Vascular Remodeling in Moyamoya Patients Without RNF213 Mutation

OBJECTIVE

Moyamoya disease (MMD) is an idiopathic cerebrovascular disease with unknown etiology. Long noncoding RNA (lncRNA) and messenger RNA (mRNA) profiles in MMD remain unknown. In this current study, we aim to investigate lncRNA-mRNA co-expression pattern and their biological functions in superficial temporal artery (STA) of MMD.

METHODS

STA of 3 MMD patients without RNF213 mutation and 3 age-matched controls were obtained for transcriptomic RNA sequencing. Bioinformatics analysis was performed to investigate their molecular functions and interactions. Then, differentially expressed genes relative to vascular remodeling were further validated by quantitative real-time polymerase chain reaction and immunofluorescence. WNT5A functions were tested by tube formation assay and wound scratching assay in human microvascular endothelial cells (HMECs).

RESULTS

We detected 6235 different lncRNAs and 2065 different mRNAs from the RNA-sequencing between MMD patients and controls (P < 0.05; fold change >2.0). Gene ontology showed that altered mRNAs were enriched for endothelial cell morphogenesis and positive regulation of angiogenesis, which were closely related with vascular remodeling. We then searched 76 altered genes related with vascular remodeling and applied Kyoto Encyclopedia of Genes and Genomes analysis. Integrated analysis of lncRNA-TF-mRNA co-expression networks and gene verifications indicated that molecular including WNT5A, TEK, and GATA2 may contribute to the vascular malformation of MMD. Overexpression of WNT5A in HMECs promoted tube formation and cell migration.

CONCLUSIONS

In MMD patients, genes related to vascular remodeling including WNT5A and their regulators were aberrantly disrupted. These results will help elucidate the complicated pathogenic mechanism of MMD and develop potential therapeutic targets facilitating MMD angiogenesis in the future.

COMP-Ang1: Therapeutic potential of an engineered Angiopoietin-1 variant

The Angiopoietin-1/2 system is an opportune target for therapeutic intervention in a wide range of vascular pathologies, particularly through its association with endothelium. The complex multi-domain structure of native human Angiopoietin-1 has hindered its widespread applicability as a therapeutic agent, prompting the search for alternative approaches to mimicking the Ang1:Tie2 signalling axis; a system with highly complex patterns of regulation involving multiple structurally similar molecules. An engineered variant, Cartilage Oligomeric Matrix Protein - Angiopoietin-1 (COMP-Ang1), has been demonstrated to overcome the limitations of the native molecule and activate the Tie2 pathway with several fold greater potency than Ang1, both in vitro and in vivo. The therapeutic efficacy of COMP-Ang1, at both the vascular and systemic levels, is evident from multiple studies. Beneficial impacts on skeletal muscle regeneration, wound healing and angiogenesis have been reported alongside renoprotective, anti-hypertensive and anti-inflammatory effects. COMP-Ang1 has also demonstrated synergy with other compounds to heighten bone repair, has been leveraged for potential use as a co-therapeutic for enhanced targeted cancer treatment, and has received considerable attention as an anti-leakage agent for microvascular diseases like diabetic retinopathy. This review examines the vascular Angiopoietin:Tie2 signalling mechanism, evaluates the potential therapeutic merits of engineered COMP-Ang1 in both vascular and systemic contexts, and addresses the inherent translational challenges in moving this potential therapeutic from bench-to-bedside.

New mechanism-based approaches to treating and evaluating the vasculopathy of scleroderma

PURPOSE OF REVIEW

Utilizing recent insight into the vasculopathy of scleroderma (SSc), the review will highlight new opportunities for evaluating and treating the disease by promoting stabilization and protection of the microvasculature.

RECENT FINDINGS

Endothelial junctional signaling initiated by vascular endothelial-cadherin (VE-cadherin) and Tie2 receptors, which are fundamental to promoting vascular health and stability, are disrupted in SSc. This would be expected to not only diminish their protective activity, but also increase pathological processes that are normally restrained by these signaling mediators, resulting in pathological changes in vascular function and structure. Indeed, key features of SSc vasculopathy, from the earliest signs of edema and puffy fingers to pathological disruption of hemodynamics, nutritional blood flow, capillary structure and angiogenesis are all consistent with this altered endothelial signaling. It also likely contributes to further progression of the disease including tissue fibrosis, and organ and tissue injury.

SUMMARY

Restoring protective endothelial junctional signaling should combat the vasculopathy of SSc and prevent further deterioration in vascular and organ function. Indeed, this type of targeted approach has achieved remarkable results in preclinical models for other diseases. Furthermore, tracking this endothelial junctional signaling, for example by assessing vascular permeability, should facilitate insight into disease progression and its response to therapy.

Associations of Angiopoietins With Heart Failure Incidence and Severity

BACKGROUND

Angiopoietin-1 and 2 (Ang1, Ang2) are important mediators of angiogenesis. Angiopoietin levels are perturbed in cardiovascular disease, but it is unclear whether angiopoietin signaling is causative, an adaptive response, or merely epiphenomenon of disease activity.

METHODS AND RESULTS

In a cohort free of cardiovascular disease at baseline (Multi-Ethnic Study of Atherosclerosis [MESA]), relationships between angiopoietins, cardiac morphology, and subsequent incidence of heart failure or cardiovascular death were evaluated. In cohorts with pulmonary arterial hypertension or left heart disease, associations between angiopoietins, invasive hemodynamics, and adverse clinical outcomes were evaluated. In MESA, Ang2 was associated with a higher incidence of heart failure or cardiovascular death (hazard ratio 1.21 per standard deviation, P < .001). Ang2 was associated with increased right atrial pressure (pulmonary arterial hypertension cohort) and increased wedge pressure and right atrial pressure (left heart disease cohort). Elevated Ang2 was associated with mortality in the pulmonary arterial hypertension cohort.

CONCLUSIONS

Ang2 was associated with incident heart failure or death among adults without cardiovascular disease at baseline and with disease severity in individuals with existing heart failure. Our finding that Ang2 is increased before disease onset and that elevations reflect disease severity, suggests Ang2 may contribute to heart failure pathogenesis.

Vascular endothelial growth factors and angiopoietins as new players in mastocytosis

Mastocytosis is a disorder characterized by the abnormal proliferation and/or accumulation of mast cells in different organs. More than 90% of patients with systemic mastocytosis have a gain-of-function mutation in codon 816 of the KIT receptor on mast cells (MCs). The symptoms of mastocytosis patients are related to the MC-derived mediators that exert local and distant effects. MCs produce angiogenic and lymphangiogenic factors, including vascular endothelial growth factors (VEGFs) and angiopoietins (ANGPTs). Serum concentrations of VEGF-A, VEGF-C, VEGF-D, ANGPT1 and ANGPT2 were determined in 64 mastocytosis patients and 64 healthy controls. Intracellular concentrations and spontaneous release of these mediators were evaluated in the mast cell lines ROSA^{KIT WT} and ROSA ^{KIT D816V} and in human lung mast cells (HLMCs). VEGF-A, ANGPT1, ANGPT2 and VEGF-C concentrations were higher in mastocytosis patients compared to controls. The VEGF-A, ANGPT2 and VEGF-C concentrations were correlated with the symptom severity. ANGPT1 concentrations were increased in all patients compared to controls. ANGPT2 levels were correlated with severity of clinical variants and with tryptase levels. VEGF-A, ANGPT1 and VEGF-C did not differ between indolent and advanced mastocytosis. ROSA^{KIT WT}, ROSA^{KIT D816V} and HLMCs contained and spontaneously released VEGFs and ANGPTs. Serum concentrations of VEGFs and ANGPTs are altered in mastocytosis patients.

Recent advances in the research and management of sepsis-associated DIC

Disseminated intravascular coagulation (DIC) is a common and life-threatening complication in sepsis. Sepsis-associated DIC is recognized as the systemic activation in coagulation with suppressed fibrinolysis that leads to organ dysfunction in combination with systemic intravascular inflammation. In this process, thrombin contributes a key role in connecting both coagulation and inflammation. Endothelial injury, a result of sepsis, causes DIC due to the effect of multiple activated factors that include neutrophils, platelets, and damage-associated molecular patterns. Recent advances in the understanding of pathophysiology have made it possible to diagnose sepsis-associated DIC at earlier timing with better accuracy. However, progress in the treatment is still limited, and new therapeutics for sepsis-associated DIC are needed.

Dexmedetomidine protects against endothelial injury in septic rats induced by cecal ligation and puncture by decreasing angiopoietin 2 and increasing vascular endothelial cadherin levels

The aim of the present study was to investigate the protective effect of dexmedetomidine (Dex) on endothelial injury in a cecal ligation and puncture (CLP)-induced rat model of sepsis. A total of 36 male Sprague-Dawley rats were divided into three groups: Sham, CLP and CLP + Dex. The wet/dry (W/D) ratio of lung weight, hematoxylin and eosin (H&E) staining of lung tissue, plasma levels of angiopoietin (Ang)1 and 2, ratio of Ang2/1 and vascular endothelial (VE)-cadherin protein expression levels in lung tissue were determined. The W/D ratio of lung tissue in the CLP + Dex group was significantly lower than that in the CLP group (P<0.01). The H&E staining results indicated that Dex treatment reduced the levels of CLP-induced alveolar septum widening, infiltrating white blood cells and congestion, when compared with CLP alone. In addition, the expression levels of plasma Ang2 and the Ang2/1 ratio in the CLP + Dex group were significantly lower than those of the CLP rats (P<0.01). Furthermore, the level of VE-cadherin protein in lung tissue of the CLP + Dex group was higher than that of the CLP group (P<0.05). The results indicated that Dex had a protective effect against CLP-induced endothelial injury, through the ability to reduce expression of the endothelial injury factor Ang2 and increase the expression of the endothelial adhesion junction factor VE-cadherin in a septic rat model. These data suggest a potential application of Dex in the clinical treatment of sepsis.

Essential contribution of macrophage Tie2 signal mediated autophagy in laser-induced choroidal neovascularization

Autophagy plays critical roles in various ocular diseases, including age-related macular degeneration (AMD). Tie2-expressing macrophages (TEMs) play crucial roles in angiogenesis. To investigate the role of TEMs and autophagy in the development of AMD, we employed macrophage-specific Tie2 knockout mice and used a laser-induced choroidal neovascularization (CNV). The results showed that TEMs can promote CNV formation by up-regulating the level of autophagy. These results were further verified by in vitro cell experiments that peritoneal macrophages from Tie2 knockout mice can inhibit the expression of autophagy-related factors and inhibit the expression of angiogenic factor of VEGF by activating AMPK signaling pathway. Our results suggest that TEMs and macrophage Tie2 signal mediated-autophagy play critical role in experimental CNV, and they may be novel preventive targets for AMD treatment.

Angiopoietin-1/Tie-2 signal after focal traumatic brain injury is potentiated by BQ788, an ETB receptor antagonist, in the mouse cerebrum: Involvement in recovery of blood-brain barrier function

Angiopoietin-1, an angiogenic factor, stabilizes brain microvessels through Tie-2 receptor tyrosine kinase. In traumatic brain injury, blood-brain barrier (BBB) disruption is an aggravating factor that induces brain edema and neuroinflammation. We previously showed that BQ788, an endothelin ET_B receptor antagonist, promoted recovery of BBB function after lateral fluid percussion injury (FPI) in mice. To clarify the mechanisms underlying BBB recovery mediated by BQ788, we examined the involvements of the angiopoietin-1/Tie-2 signal. When angiopoietin-1 production and Tie-2 phosphorylation were assayed by quantitative reverse transcription polymerase chain reaction and western blotting, increased angiopoietin-1 production and Tie-2 phosphorylation were observed in 7-10 days after FPI in the mouse cerebrum, whereas no significant effects were obtained at 5 days. When BQ788 (15 nmol/day, i.c.v.) were administered in 2-5 days after FPI, increased angiopoietin-1 production and Tie-2 phosphorylation were observed. Immunohistochemical observations showed that brain microvessels and astrocytes contained angiopoietin-1 after FPI, and brain microvessels also contained phosphorylated Tie-2. Treatment with endothelin-1 (100 nM) decreased angiopoietin-1 production in cultured astrocytes and the effect was inhibited by BQ788 (1 μM). Five days after FPI, increased extravasation of Evans blue dye accompanied by reduction in claudin-5, occludin, and zonula occludens-1 proteins were observed in mouse cerebrum while these effects of FPI were reduced by BQ788 and exogenous angiopoietin-1 (1 μg/day, i.c.v.). The effects of BQ788 were inhibited by co-administration of a Tie-2 kinase inhibitor (40 nmol/day, i.c.v.). These results suggest that BQ788 administration after traumatic brain injury promotes recovery of BBB function through activation of the angiopoietin-1/Tie-2 signal.

COMP-Ang1 Stabilizes Hyperglycemic Disruption of Blood-Retinal Barrier Phenotype in Human Retinal Microvascular Endothelial Cells

Purpose

Current treatments for diabetic retinopathy (DR) have considerable limitations, underpinning the need for new therapeutic options. In this article, the ability of an engineered angiopoietin-1 variant (COMP-Ang1) to ameliorate the injurious effects of hyperglycemia on barrier integrity in a human retinal microvascular endothelial cell (HRMvEC) model is comprehensively investigated.

Methods

Confluent HRMvECs were treated (0–72 hours) with d-glucose (5 or 30 mM) in the absence and presence of COMP-Ang1 (10–200 ng/mL). l-glucose (30 mM) was used as osmotic control. Posttreatment, intact cell monolayers were monitored for permeability to FITC-dextran 40 kDa. Cells were also harvested for analysis of interendothelial junction targets by RT-qPCR and Western blotting. The impact of receptor tyrosine kinase Tie2 gene silencing on COMP-Ang1 efficacy was also evaluated.

Results

Treatment with 30 mM d-glucose (but not l-glucose) demonstrated a time-dependent elevation in the mean rate of FITC-dextran diffusion across intact HRMvEC monolayers, in parallel with significant reductions in mRNA/protein levels of occludin, claudin-5, ZO-1, and VE-Cadherin. These effects were all attenuated by COMP-Ang1 in a concentration-dependent fashion, with 200 ng/mL recovering barrier function by ∼88%, and recovering reduced interendothelial junction protein levels by more than 50%. Finally, Tie2 knockdown by small interfering RNA silencing blocked the ability of COMP-Ang1 to mitigate against hyperglycemia-induced permeabilization of HRMvECs and depletion of junctional expression levels.

Conclusions

In summary, this article presents a reproducible in vitro cell study that quantifies the concentration-dependent efficacy of COMP-Ang1 to mitigate the injurious effects of hyperglycemic challenge on HRMvEC barrier properties via Tie2-mediated signaling.

Propranolol inhibits proliferation and induces apoptosis of hemangioma-derived endothelial cells via Akt pathway by down-regulating Ang-2 expression

Hemangioma is one of the commonest benign vascular tumors among children. Propranolol is the first-line therapeutic drug for hemangioma. However, the effects and mechanisms of propranolol in hemangioma have not been thoroughly elaborated. In this study, the effects and mechanisms of propranolol were explored using hemangioma-derived endothelial cells (HemECs). The expression of GLUT1 were determined by immunofluorescence staining. qRT-PCR assay was conducted to detect the mRNA expressions of angiopoietin-2 (Ang-2) and Tie-2. Western blot assay was carried out to measure the protein levels of Ang-2, Tie-2, protein kinase-B (Akt) and phospholyrated-Akt (p-Akt). Cell proliferation was assessed by Cell Counting Kit-8 (CCK-8) assay and Western blot of Ki67 protein level. Cell apoptosis was measured by flow cytometry analysis and Western blot of Bax and Bcl-2 levels. We found that propranolol inhibited proliferation and induced apoptosis in human umbilical vein endothelial cells (HUVECs) and HemECs. Moreover, propranolol inhibited the expressions of Ang-2 and Tie-2 in HUVECs and HemECs. Functional analysis revealed that Ang-2 attenuated the effects of propranolol on HemEC proliferation and apoptosis. Mechanistical analysis showed that propranolol inhibited the Akt pathway by regulating Ang-2 expression in HemECs. Futhermore, inhibition of the Akt pathway attenuated the effects of Ang-2 on proliferation and apoptosis in HemECs. In conclusion, propranolol inhibited proliferation and induced apoptosis of HemECs via Akt pathway by down-regulating Ang-2 expression, which contributes to our understanding on the pathogenesis of hemangioma and promotes the development of therapeutic approaches for hemangioma.

The effect of angiopoietin-1 upregulation on the outcome of acute ischaemic stroke in rodent models: A meta-analysis

Clinical studies report that low circulating angiopoietin-1 concentration at presentation predicts worse outcomes after ischaemic stroke. Upregulating angiopoietin-1 may therefore have therapeutic benefit for ischaemic stroke. This systematic review assessed whether upregulating angiopoietin-1 improved outcomes in rodent models of ischaemic stroke. Random-effects models quantified the effect of angiopoietin-1 upregulation on stroke severity in terms of the size of cerebral infarction and the extent of blood-brain barrier permeability. Eleven studies utilising rat and mouse models of ischaemic stroke fulfilled the inclusion criteria. Meta-analyses demonstrated that angiopoietin-1 upregulation significantly reduced cerebral infarction size (standardised mean difference: -3.02; 95% confidence intervals: -4.41, -1.63; p < 0.001; n = 171 animals) and improved blood-brain barrier integrity (standardized mean difference: -2.02; 95% confidence intervals: -3.27, -0.77; p = 0.002; n = 129 animals). Subgroup analyses demonstrated that angiopoietin-1 upregulation improved outcomes in models of transient, not permanent cerebral ischaemia. Six studies assessed the effect of angiopoietin-1 upregulation on neurological function; however, inter-study heterogeneity prevented meta-analysis. In conclusion, published rodent data suggest that angiopoietin-1 upregulation improves outcome following temporary cerebral ischaemia by reducing cerebral infarction size and improving blood-brain barrier integrity. Additional research is required to examine the effect of angiopoietin-1 upregulation on neurological function during stroke recovery and investigate the benefit and risks in patients.

Angiopoietin 2 signal complexity in cardiovascular disease and cancer

The angiopoietin signal transduction system is a complex of vascular-specific kinase pathways that plays a crucial role in angiogenesis and maintenance of vascular homeostasis. Angiopoietin1 (Ang1) and 2 (Ang2), the ligand proteins of the pathway, belong to a family of glycoproteins that signal primarily through the transmembrane Tyrosine-kinase-2 receptor. Despite a considerable sequence homology, Ang1 and Ang2 manifest antagonistic effects in pathophysiological conditions. While Ang1 promotes the activation of survival pathways and the stabilization of the normal mature vessels, Ang2 can either favor vessel destabilization and leakage or promote abnormal EC proliferation in a context-dependent manner. Altered Ang1/Ang2 balance has been reported in various pathological conditions in association with inflammation and deregulated angiogenesis. In particular, increased Ang2 levels have been documented in human cancer and cardiovascular disease (CVD), including ischemic myocardial injury, heart failure and other cardiovascular complications secondary to diabetes, chronic renal damage and hypertension. Despite the obvious phenotypic differences, CVD and cancer share some common Ang2-dependent etiopathological mechanisms such as inflammation, epithelial (or endothelial) to mesenchymal transition, and adverse vascular network remodeling. Interestingly, both cancer and CVD are negatively affected by thyroid hormone dyshomeostasis. This review provides an overview of the complex Ang2-dependent signaling involved in CVD and cancer, as well as a survey of the related clinical literature. Moreover, on the basis of recent molecular acquisitions in an experimental model of post ischemic cardiac disease, the putative novel role of the thyroid hormone in the regulation of Ang1/Ang2 balance is also briefly discussed.

Differential regulation of blood vessel formation between traumatic temporomandibular joint fibrous ankylosis and bony ankylosis in a sheep model

OBJECTIVES

Clinical and experimental studies show that the etiology of traumatic temporomandibular joint (TMJ) fibrous ankylosis and bony ankylosis are associated with the severity of trauma. However, how the injury severity affects the tissue differentiation is not clear. We tested the hypothesis that angiogenesis affects the outcomes of TMJ trauma, and that enhanced neovascularization after severe TMJ trauma would promote the development of bony ankylosis.

METHODS

Bilateral condylar sagittal fracture and discectomy were performed for each sheep, with the glenoid fossa receiving either severe trauma to induce bony ankylosis or minor trauma to induce fibrous ankylosis. At days 7, 14, 28, and 56 after surgery, total RNA was extracted from the ankylosed callus. Temporal gene expressions of several molecules functionally important for blood vessel formation were studied by real-time PCR.

RESULTS

Histological examination revealed a prolonged hematoma phase and a lack of cartilage formation in fibrous ankylosis. mRNA expression levels of HIF-1α, VEGF, VEGFR2, SDF1, Ang1, Tie2, vWF, CYR61, FGF2, TIMP1, MMP2, and MMP9 were distinctly lower in fibrous ankylosis compared with bony ankylosis at several time points.

CONCLUSIONS

Our study indicates that inhibition of angiogenesis after TMJ trauma might be a promising strategy for preventing bony ankylosis in the future.

Materials Science and Design Principles of Growth Factor Delivery Systems in Tissue Engineering and Regenerative Medicine

Growth factors (GFs) are signaling molecules that direct cell development by providing biochemical cues for stem cell proliferation, migration, and differentiation. GFs play a key role in tissue regeneration, but one major limitation of GF-based therapies is dosage-related adverse effects. Additionally, the clinical applications and efficacy of GFs are significantly affected by the efficiency of delivery systems and other pharmacokinetic factors. Hence, it is crucial to design delivery systems that provide optimal activity, stability, and tunable delivery for GFs. Understanding the physicochemical properties of the GFs and the biomaterials utilized for the development of biomimetic GF delivery systems is critical for GF-based regeneration. Many different delivery systems have been developed to achieve tunable delivery kinetics for single or multiple GFs. The identification of ideal biomaterials with tunable properties for spatiotemporal delivery of GFs is still challenging. This review characterizes the types, properties, and functions of GFs, the materials science of widely used biomaterials, and various GF loading strategies to comprehensively summarize the current delivery systems for tunable spatiotemporal delivery of GFs aimed for tissue regeneration applications. This review concludes by discussing fundamental design principles for GF delivery vehicles based on the interactive physicochemical properties of the proteins and biomaterials.

Angiopoietins in Diabetic Retinopathy: Current Understanding and Therapeutic Potential

Diabetic retinopathy (DR) is the commonest cause of blindness in the working-age population of the developed world. The molecular pathophysiology of DR is complex, and a complete spatiotemporal model of the disease is still being elucidated. Recently, a role for angiopoietin (Ang) proteins in the pathophysiology of DR has been proposed by several research groups, and several aspects of Ang signalling are being explored as novel therapeutic strategies. Here, we review the role of the Ang proteins in two important forms of DR, diabetic macular oedema and proliferative diabetic retinopathy. The function of the Ang proteins in regulating blood vessel permeability and neovascularisation is discussed, and we also evaluate recent preclinical and clinical studies highlighting the potential benefits of modulating Ang signalling as a treatment for DR.

Comparative 1D Blue-Native electrophoresis analysis of Plasmodium falciparum and human proteins associated with cytoadherence

Background

To understand more about changes to the molecular components that occur when host endothelium interacts with Plasmodium falciparum-infected erythrocytes, a combined technique of protein separation (1D Blue-Native electrophoresis) and mass spectrometry of infected erythrocytes with endothelial cells (EC) in a co-culture system has been used.

Methods

Native proteins were extracted from co-cultures and identified by mass spectrometry. Proteomic data from different parasite strains, either adhesion proficient (to endothelial cells) or non-adherent, were analysed in parallel to reveal protein associations linked to cytoadherence. Informatic approaches were developed to facilitate this comparison.

Results

Blue-Native gel separation and LC/MS/MS identification revealed major differences in samples produced from endothelial cell co-culture with adherent and non-adherent parasite strains. This approach enabled us to identify protein associations seen only with the adhesion proficient parasite strain.

Conclusions

The combination of proteomic and analytical approaches has identified differences between adherent and non-adherent parasite lines in co-culture with EC, providing potential candidates for complexes or associations formed during cytoadherence involved in cell structure, signalling and apoptosis.

Electronic supplementary material

The online version of this article (10.1186/s12936-018-2445-8) contains supplementary material, which is available to authorized users.

Secreted Phospholipases A2 in Hereditary Angioedema With C1-Inhibitor Deficiency

Background

Hereditary angioedema (HAE) caused by deficiency (type I) or dysfunction (type II) of the C1 inhibitor protein (C1-INH-HAE) is a disabling, potentially fatal condition characterized by recurrent episodes of swelling. We have recently found that patients with C1-INH-HAE have increased plasma levels of vascular endothelial growth factors and angiopoietins (Angs), which have been associated with vascular permeability in several diseases. Among these and other factors, blood endothelial cells and vascular permeability can be modulated by extracellular or secreted phospholipases A₂ (sPLA₂s).

Objective

We sought to investigate the enzymatic activity and biological functions of sPLA₂ in patients with C1-INH-HAE.

Methods

sPLA₂s enzymatic activity was evaluated in the plasma from 109 adult patients with C1-INH-HAE and 68 healthy donors in symptom-free period and attacks. Plasma level of group IIA sPLA₂ (hGIIA) protein was measured in selected samples. The effect of C1-INH-HAE plasma on endothelial permeability was examined in vitro using a vascular permeability assay. The role of hGIIA was determined using highly specific sPLA₂ indole inhibitors. The effect of recombinant hGIIA on C1-INH activity was examined in vitro by functional assay.

Results

Plasma sPLA₂ activity and hGIIA levels are increased in symptom-free C1-INH-HAE patients compared with controls. sPLA₂ activity negatively correlates with C1-INH protein level and function. C1-INH-HAE plasma increases endothelial permeability in vitro, and this effect is partially reverted by a specific hGIIA enzymatic inhibitor. Finally, recombinant hGIIA inhibits C1-INH activity in vitro.

Conclusion

sPLA₂ enzymatic activity (likely attributable to hGIIA), which is increased in C1-INH-HAE patients, can promote vascular permeability and impairs C1-INH activity. Our results may pave the way for investigating the functions of sPLA₂s (in particular, hGIIA) in the pathophysiology of C1-INH-HAE and may inform the development of new therapeutic targets.

Angiopoietin 2 Levels in the Risk Stratification and Mortality Outcome Prediction of Sepsis-Associated Coagulopathy

It has been well established that angiopoietin 2 (Ang-2), a glycoprotein involved in activation of the endothelium, plays an integral role in the pathophysiology of sepsis and many other inflammatory conditions. However, the role of Ang-2 in sepsis-associated coagulopathy (SAC) specifically has not been defined. The aim of this study was to measure Ang-2 plasma levels in patients with sepsis and suspected disseminated intravascular coagulation (DIC) in order to demonstrate its predictive value in SAC severity determination and 28-day mortality outcome. Plasma samples were collected from 102 patients with sepsis and suspected DIC at intensive care unit (ICU) admission. The Ang-2 plasma levels were quantified using a sandwich enzyme-linked immunosorbent assay method. The International Society on Thrombosis and Haemostasis DIC scoring system was used to compare the accuracy of Ang-2 levels versus clinical illness severity scores in predicting SAC severity. Mean Ang-2 levels in patients with sepsis and DIC were significantly higher in comparison to healthy controls (P < 0.0001), and median Ang-2 levels showed a downward trend over time (P = 0.0008). Baseline Ang-2 levels and clinical illness severity scores were higher with increasing severity of disease, and Ang-2 was a better predictor of DIC severity than clinical illness scores. This study demonstrates that Ang-2 levels are significantly upregulated in SAC, and this biomarker can be used to risk stratify patients with sepsis into non-overt DIC and overt DIC. Furthermore, the Ang-2 level at ICU admission in a patient with sepsis and suspected DIC may provide a predictive biomarker for mortality outcome.

[Phosphodiesterase 4 inhibition for treatment of endothelial barrier and microcirculation disorders in sepsis]

Sepsis is commonly associated with loss of microvascular endothelial barrier function (capillary leak) and dysfunctional microcirculation, which both promote organ failure. The development of a distinct therapy of impaired endothelial barrier function and disturbed microcirculation is highly relevant because both of these phenomena constitute crucial processes which critically influence the prognosis of patients. Numerous in vivo and in vitro trials over the past years have fostered a better understanding of the pathophysiology of capillary leak. Furthermore, promising data in animal models show that therapeutic modulation of endothelial barrier function and microcirculation can be achieved by stabilizing endothelial cAMP (cyclic adenosine monophosphate) levels followed by activation of Rho-GTPase Rac1, e. g. by phosphodiesterase 4 inhibitors. This review summarizes and discusses recent findings of cellular mechanisms and in vivo trials.

Differential Roles of LTβR in Endothelial Cell Subsets for Lymph Node Organogenesis and Maturation

Cellular cross-talk mediated by lymphotoxin αβ-lymphotoxin β receptor (LTβR) signaling plays a critical role in lymph node (LN) development. Although the major role of LTβR signaling has long been considered to occur in mesenchymal lymphoid tissue organizer cells, a recent study using a VE-cadherin^creLtbr^fl/fl mouse model suggested that endothelial LTβR signaling contributes to the formation of LNs. However, the detailed roles of LTβR in different endothelial cells (ECs) in LN development remain unknown. Using various cre transgenic mouse models (Tek^cre , a strain targeting ECs, and Lyve1^cre , mainly targeting lymphatic ECs), we observed that specific LTβR ablation in Tek^cre+ or Lyve1^cre+ cells is not required for LN formation. Moreover, double-cre-mediated LTβR depletion does not interrupt LN formation. Nevertheless, Tek^creLtbr^fl/fl mice exhibit reduced lymphoid tissue inducer cell accumulation at the LN anlagen and impaired LN maturation. Interestingly, a subset of ECs (VE-cadherin⁺Tek^cre-low/neg ECs) was found to be enriched in transcripts related to hematopoietic cell recruitment and transendothelial migration, resembling LN high ECs in adult animals. Furthermore, endothelial Tek was observed to negatively regulate hematopoietic cell transmigration. Taken together, our data suggest that although Tek^cre+ endothelial LTβR is required for the accumulation of hematopoietic cells and full LN maturation, LTβR in VE-cadherin⁺Tek^cre-low/neg ECs in embryos might represent a critical portal-determining factor for LN formation.

MiR-876-5p suppresses cell proliferation by targeting Angiopoietin-1 in the psoriasis

Psoriasis is an autoimmune disease characterized by abnormal differentiation and hyper-proliferation of epidermal keratinocytes. The object of the study is to investigate the role of miRNA-876-5p in psoriasis. It reported that MicroRNAs (miRNAs) played roles in the malignant progression in psoriasis development. The expression of miR-876-5p was found to be down-regulated in psoriasic tissue and blood of patients. The luciferase assay verified the targeting role of miR-876-5p to 3'UTR of Angiopoietin-1 (Ang-1). Proliferation of psoriasic cells were inhibited by miR-876-5p and hold on G0/G1 phase. Further studies showed that miR-876-5p suppressed proliferation by restraining the expression of Ang-1, which would regulate the phosphorylation level of PI3K, AKT, mTOR and ERK in psoriasic cells. Invasion and adhesion, serving as important behavioral traits of epidermal keratinocytes cells, were suppressed by excessive miR-876-5p in psoriasic cells also. MiR-876-5p would be expected to be biomarker and potential therapeutic targets for the treatment of psoriasis.

miR144-3p inhibits PMVECs excessive proliferation in angiogenesis of hepatopulmonary syndrome via Tie2

BACKGROUND/AIM

Increasing evidence show microRNAs (miRNAs) are associated with hepatopulmonary syndrome (HPS). The aim of this study was to investigate the role of miR-144 in the angiogenesis of HPS, as well as to identify its underlying mechanism.

METHODS

The expression levels of miR-144-3p were assessed in pulmonary micro-vascular endothelial cells (PMVECs), as well as in lung tissues from rats with HPS. We predicted the potential target of miR-144-3p. Tyrosine kinase 2(Tie2) was identified as a target gene of miR144-3p, which has an essential role in the angiogenesis of lung vessel. In addition, the effects of miR-144-3p regulated on Tie2 was examined. The upregulation and down-regulation of miR-144-3p can affect the proliferation of PMVECs.

RESULTS

We found that the levels of miR-144-3p were frequently downregulated in HPS tissues and cell lines, and overexpression of miR-144-3p dramatically inhibited PMVECs proliferation and cell cycle. We further verified the Tie2 as a novel and direct target of miR-144-3p in HPS.

CONCLUSION

miR-144-3p can negatively regulate PMVECs proliferation by Tie2 expression. In addition, overexpression of miR-144-3p may prove beneficial as a therapeutic strategy for HPS treatment.

In Development-A New Paradigm for Understanding Vascular Disease

Under physiological conditions, the arterial endothelium exerts a powerful protective influence to maintain vascular homeostasis. However, during the development of vascular disease, these protective activities are lost, and dysfunctional endothelial cells actually promote disease pathogenesis. Numerous investigations have analyzed the characteristics of dysfunctional endothelium with a view to understanding the processes responsible for the dysfunction and to determining their role in vascular pathology. This review adopts an alternate approach: reviewing the mechanisms that contribute to the initial formation of a healthy protective endothelium and on how those mechanisms may be disrupted, precipitating the appearance of dysfunctional endothelial cells and the progression of vascular disease. This approach, which highlights the role of endothelial adherens junctions and vascular endothelial-cadherin in endothelial maturation and endothelial dysfunction, provides new insight into the remarkable biology of this important cell layer and its role in vascular protection and vascular disease.

Hypoxia-Inducible Factor-Dependent Expression of Angiopoietin-Like 4 by Conjunctival Epithelial Cells Promotes the Angiogenic Phenotype of Pterygia

Purpose

Disappointing results from clinical studies assessing the efficacy of therapies targeting vascular endothelial growth factor (VEGF) for the treatment of pterygia suggest that other angiogenic mediators may also play a role in its development. We therefore explore the relative contribution of VEGF, hypoxia-inducible factor (HIF)-1α (the transcription factor that regulates VEGF expression in ocular neovascular disease), and a second HIF-regulated mediator, angiopoietin-like 4 (ANGPTL4), to the angiogenic phenotype of pterygia.

Methods

Expression of HIF-1α, VEGF, and ANGPTL4 were examined in surgically excised pterygia, and in immortalized human (ih) and primary rabbit (pr) conjunctival epithelial cells (CjECs). Endothelial cell (EC) tubule formation assays using media conditioned by ihCjECs in the presence or absence of inducers/inhibitors of HIF-1 or RNA interference (RNAi) targeting VEGF, ANGPTL4, or both were used to assess their relative contribution to the angiogenic potential of these cells.

Results

HIF-1α and VEGF expression were detected in 6/6 surgically excised pterygia and localized to CjECs. Accumulation of HIF-1α in was confirmed in ihCjECs and prCjECs, including stratified prCjECs grown on collagen vitrigel, and resulted in expression of VEGF and the promotion of EC tubule formation; the latter effect was partially blocked using RNAi targeting VEGF mRNA expression. We demonstrate expression of a second HIF-regulated angiogenic mediator, ANGPTL4, in CjECs in culture and in surgically excised pterygia. RNAi targeting ANGPTL4 inhibited EC tubule formation and was additive to RNAi targeting VEGF.

Conclusions

Our results support the development of therapies targeting both ANGPTL4 and VEGF for the treatment of patients with pterygia.

Role of Angiopoietins and Tie-2 in Diabetic Retinopathy

OBJECTIVE

The aim of this study was to determine the serum levels of angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), soluble vascular endothelial tyrosine kinase receptor (Tie-2) and vascular endothelial growth factor (VEGF), in the serum of type 2 diabetic patients having non-proliferative (NPDR) or proliferative diabetic retinopathy (PDR).

METHODS

One hundred patients with type 2 diabetes mellitus were involved in this cross-sectional study. They were classified into 25 diabetic patients without retinopathy, 35 patients with NPDR and 40 PDR patients. The study was carried out in the outpatients clinic of the Research Institute of Ophthalmology, Giza, Egypt from August 2016 through May 2017. Serum VEGF, Ang-1, Ang-2 and Tie-2 receptor levels were assayed using enzyme linked immunosorbent assay (ELISA). Data were analyzed by SPSS version 20 and Microsoft Excel (Version 10) using ANOVA, Harman's single factor test, and Pearson's Product Moment Correlation.

RESULTS

The serum levels of Ang-2 and VEGF were significantly elevated in NPDR groups and PDR group compared to diabetics without retinopathy groups (p<0.001). The serum levels of Ang-1 were significantly higher in the NPDR group compared to the diabetics without retinopathy groups (p<0.01), while no significant difference was observed between the PDR and diabetics without retinopathy groups. Ang-1/Ang-2 ratio was the lowest in the PDR group compared to the NPDR and diabetics without retinopathy groups. The serum levels of Tie-2 were not significantly changed among the three studied groups, serum Ang-2 was positively correlated with VEGF and Tie-2 in the PDR and NPDR groups.

CONCLUSION

The angiopoietin/Tie system and VEGF are essential features in the commencement and development of PDR.

Identification of Four Novel Loci in Asthma in European American and African American Populations

RATIONALE

Despite significant advances in knowledge of the genetic architecture of asthma, specific contributors to the variability in the burden between populations remain uncovered.

OBJECTIVES

To identify additional genetic susceptibility factors of asthma in European American and African American populations.

METHODS

A phenotyping algorithm mining electronic medical records was developed and validated to recruit cases with asthma and control subjects from the Electronic Medical Records and Genomics network. Genome-wide association analyses were performed in pediatric and adult asthma cases and control subjects with European American and African American ancestry followed by metaanalysis. Nominally significant results were reanalyzed conditioning on allergy status.

MEASUREMENTS AND MAIN RESULTS

The validation of the algorithm yielded an average of 95.8% positive predictive values for both cases and control subjects. The algorithm accrued 21,644 subjects (65.83% European American and 34.17% African American). We identified four novel population-specific associations with asthma after metaanalyses: loci 6p21.31, 9p21.2, and 10q21.3 in the European American population, and the PTGES gene in African Americans. TEK at 9p21.2, which encodes TIE2, has been shown to be involved in remodeling the airway wall in asthma, and the association remained significant after conditioning by allergy. PTGES, which encodes the prostaglandin E synthase, has also been linked to asthma, where deficient prostaglandin E₂ synthesis has been associated with airway remodeling.

CONCLUSIONS

This study adds to understanding of the genetic architecture of asthma in European Americans and African Americans and reinforces the need to study populations of diverse ethnic backgrounds to identify shared and unique genetic predictors of asthma.

Angiogenesis Dysregulation in Psoriatic Arthritis: Molecular Mechanisms

There is evidence that psoriatic arthritis is closely linked to angiogenesis. Morphological changes described in blood vessels of psoriatic arthritis joints suggest the presence of a dysregulated angiogenesis resulting in the formation of immature vessels. Even if the reason of this inefficient angiogenesis is still unclear, an imbalance between angiogenic and antiangiogenic factors is probably responsible for inducing a dysregulated angiogenesis in psoriatic arthritis, which seems to be involved in its pathogenesis and clinical features. Nevertheless, among chronic arthritides, while angiogenesis in rheumatoid arthritis has been largely studied with a great amount of literature data, limited data on angiogenesis role in psoriatic arthritis are available. This review article is focused on current knowledge on the mechanisms responsible for dysregulated angiogenesis in psoriatic arthritis.

Two natural eudesmane-type sesquiterpenes from Laggera alata inhibit angiogenesis and suppress breast cancer cell migration through VEGF- and Angiopoietin 2-mediated signaling pathways

Eudesmane-type sesquiterpenes are natural sesquiterpenes with anti-inflammatory properties, but their anti-angiogenic activities are not known. The present study demonstrated that 5α-hydroxycostic acid and hydroxyisocostic acid, two eudesmane-type sesquiterpenes (ETSs), isolated from the herb Laggera alata, possessed anti-angiogenic effects. Under non-toxic dosage, ETSs suppressed VEGF‑induced proliferation in human umbilical vein endothelial cells (HUVECs) and vessel formation in zebrafish embryos. Moreover, ETSs inhibited VEGF-stimulated HUVEC migration, stress fibers and tube formation. Results from real‑time PCR analysis involving in vivo and in vitro experiments indicated that pro-angiogenic-related mRNA levels were downregulated, including VEGFA, VEGFR2 and Tie2 genes after ETS treatments. Western blot analysis showed that ETSs suppressed VEGF-stimulated VEGFR2 phosphorylation and activation of its downstream molecules, such as Src/AKT/eNOS, FAK, PLCγ/ERK1/2 and p38. Moreover, the VEGF-stimulation of angiopoietin 2 (Ang2) mRNA level increase was significantly downregulated in the presence of ETSs. ETSs inhibited Ang2-induced phosphorylation of the receptor Tie2 in HUVECs, which indicated that ETSs not just suppressed VEGF/VEGFR2 axis, but also the Ang2/Tie2 one. Furthermore, the wound-healing assay revealed that ETSs reduced the migration of Ang2-stimulated human breast cancer (MCF-7) cells. Mechanistically, the anti-migration effect of ETSs correlated with the blockade of Ang2-induced E-cadherin loss and AKT activation. Collectively, the present study suggests that ETSs possess anti-angiogenic ability by interfering the VEGF- and Ang2-related pathways, and they may be good drug candidates.

Intravenous Arginine Administration Promotes Proangiogenic Cells Mobilization and Attenuates Lung Injury in Mice with Polymicrobial Sepsis

This study investigated the influence of intravenous arginine (Arg) administration on alteration of circulating proangiogenic cells and remote lung injury in a model of polymicrobial sepsis. Mice were assigned to one normal control group (NC) and two sepsis groups that were induced by cecal ligation and puncture (CLP). One of the sepsis groups was injected with saline (SS), whereas the other (SA) was administered with a single bolus of 300 mg Arg/kg body weight via the tail vein 1 h after CLP. Septic mice were sacrificed at either 24 or 48 h after CLP, with their blood and lung tissues collected for analysis. Results showed that septic groups had higher proangiogenic cells releasing factors and proangiogenic cells percentage in blood. Also, concentration of inflammatory cytokines and expression of angiopoietin (Angpt)/Tie-2 genes in lung tissues were upregulated. Arg administration promoted mobilization of circulating proangiogenic cells while it downregulated the production of inflammatory cytokines and expression of Angpt/Tie-2 genes in the lung. The results of this investigation suggested that intravenous administration of Arg shortly after the onset of sepsis enhanced the mobilization of circulating proangiogenic cells, maintained the homeostasis of the Angpt/Tie-2 axis, and attenuated remote organ injury in polymicrobial sepsis.

Discovery of multi-target receptor tyrosine kinase inhibitors as novel anti-angiogenesis agents

Recently, we have identified a biphenyl-aryl urea incorporated with salicylaldoxime (BPS-7) as an anti-angiogenesis agent. Herein, we disclosed a series of novel anti-angiogenesis agents with BPS-7 as lead compound through combining diarylureas with N-pyridin-2-ylcyclopropane carboxamide. Several title compounds exhibited simultaneous inhibition effects against three pro-angiogenic RTKs (VEGFR-2, TIE-2 and EphB4). Some of them displayed potent anti-proliferative activity against human vascular endothelial cell (EA.hy926). In particular, two potent compounds (CDAU-1 and CDAU-2) could be considered as promising anti-angiogenesis agents with triplet inhibition profile. The biological evaluation and molecular docking results indicate that N-pyridin-2-ylcyclopropane carboxamide could serve as a hinge-binding group (HBG) for the discovery of multi-target anti-angiogenesis agents. CDAU-2 also exhibited promising anti-angiogenic potency in a tissue model for angiogenesis.

Angiogenesis in the atherosclerotic plaque

Atherosclerosis is a multifocal alteration of the vascular wall of medium and large arteries characterized by a local accumulation of cholesterol and non-resolving inflammation. Atherothrombotic complications are the leading cause of disability and mortality in western countries. Neovascularization in atherosclerotic lesions plays a major role in plaque growth and instability. The angiogenic process is mediated by classical angiogenic factors and by additional factors specific to atherosclerotic angiogenesis. In addition to its role in plaque progression, neovascularization may take part in plaque destabilization and thromboembolic events. Anti-angiogenic agents are effective to reduce atherosclerosis progression in various animal models. However, clinical trials with anti-angiogenic drugs, mainly anti-VEGF/VEGFR, used in anti-cancer therapy show cardiovascular adverse effects, and require additional investigations.