Angiopoietins: a link between angiogenesis and inflammation

Raynaud's Phenomenon: Reviewing the Pathophysiology and Management Strategies

Raynaud's phenomenon (RP) is a multifactorial vasospastic disorder characterized by a transient, recurrent, and reversible constriction of peripheral blood vessels. RP is documented to affect up to 5% of the general population, but variation in its prevalence is commonly recognized owing to many factors, including varied definitions, gender, genetics, hormones, and region. Furthermore, RP may be idiopathic or be a clinical manifestation of an underlying illness. Patients with RP classically describe a triphasic discoloration of the affected area, beginning with pallor, followed by cyanosis, and finally ending with erythema. This change in color spares the thumb and is often associated with pain. Each attack may persist from several minutes to hours. Moreover, the transient cessation of blood flow in RP is postulated to be mediated by neural and vascular mechanisms. Both structural and functional alterations observed in the blood vessels contribute to the vascular abnormalities documented in RP. However, functional impairment serves as a primary contributor to the pathophysiology of primary Raynaud's. Substances like endothelin-1, angiotensin, and angiopoietin-2 play a significant role in the vessel-mediated pathophysiology of RP. The role of nitric oxide in the development of this phenomenon is still complex. Neural abnormalities resulting in RP are recognized as either being concerned with central mechanisms or peripheral mechanisms. CNS involvement in RP may be suggested by the fact that emotional distress and low temperature serve as major triggers for an attack, but recent observations have highlighted the importance of locally produced factors in this regard as well. Impaired vasodilation, increased vasoconstriction, and several intravascular abnormalities have been documented as potential contributors to the development of this disorder. RP has also been observed to occur as a side effect of various drugs. Recent advances in understanding the mechanism of RP have yielded better pharmacological therapies. However, general lifestyle modifications along with other nonpharmacological interventions remain first-line in the management of these patients. Calcium channel blockers, alpha-1 adrenoreceptor antagonists, angiotensin-converting enzyme inhibitors, nitric oxide, prostaglandin analogs, and phosphodiesterase inhibitors are some of the common classes of drugs that have been found to be therapeutically significant in the management of RP. Additionally, anxiety management, measures to avoid colder temperatures, and smoking cessation, along with other simple modifications, have proven to be effective non-drug strategies in patients experiencing milder symptoms.

Endothelial dysfunction in preterm infants: The hidden legacy of uteroplacental pathologies

Millions of infants are born prematurely every year worldwide. Prematurity, particularly at lower gestational ages, is associated with high mortality and morbidity and is a significant global health burden. Pregnancy complications and preterm birth syndrome strongly impact neonatal clinical phenotypes and outcomes. The vascular endothelium is a pivotal regulator of fetal growth and development. In recent years, the key role of uteroplacental pathologies impairing endothelial homeostasis is emerging. Conditions leading to very and extremely preterm birth can be classified into two main pathophysiological patterns or endotypes: infection/inflammation and dysfunctional placentation. The first is frequently related to chorioamnionitis, whereas the second is commonly associated with hypertensive disorders of pregnancy and fetal growth restriction. The nature, timing, and extent of prenatal noxa may alter fetal and neonatal endothelial phenotype and functions. Changes in the luminal surface, oxidative stress, growth factors imbalance, and dysregulation of permeability and vascular tone are the leading causes of endothelial dysfunction in preterm infants. However, the available evidence regarding endothelial physiology and damage is limited in neonates compared to adults. Herein, we discuss the current knowledge on endothelial dysfunction in the infectious/inflammatory and dysfunctional placentation endotypes of prematurity, summarizing their molecular features, available biomarkers, and clinical impact. Furthermore, knowledge gaps, shadows, and future research perspectives are highlighted.

A Comparative Study of Serum Angiogenic Biomarkers in Cirrhosis and Hepatocellular Carcinoma

Simple Summary

The progression of liver disease is accompanied by pathological angiogenesis, a prerequisite for the development of HCC. In this paper, we analyzed the clinical significance of serum angiogenic markers VEGF, Ang-1, Ang-2, angiopoietin receptor Tie1/2, HGF, and PECAM-1 in 62 patients with liver disease, out of which 33 were diagnosed with HCC and 29 with liver cirrhosis without signs of neoplasia. Biomarkers levels were investigated as a function of “Model for End-Stage Liver Disease” (MELD) score and Fibrosis Index (FI). HCC patients showed higher HGF levels than ones with cirrhosis, while high Ang-1 levels appeared to have a protective role in HCC as well as prognostic significance; we also found a strong correlation between HGF levels, Ang-2, and VEGF levels, further supporting their role in tumor angiogenesis. Due to the complexity of angiogenesis and the small size of the study group, further investigations are widely desired especially in the era of immunotherapy and HCC-targeted anti-angiogenic drugs.

Abstract

Background: Hepatocellular carcinoma (HCC) is a global health problem associated with chronic liver disease. Its pathogenesis varies according to the underlying etiological factors, although in most cases it develops from liver cirrhosis. The disease progression is accompanied by pathological angiogenesis, which is a prerequisite that favors the development of HCC. Aims: This study aims at contributing to our understanding of the role of angiogenic factors in the progression of liver disease. For this purpose, we evaluate the clinical significance of serum angiogenic markers (VEGF, Ang-1, Ang-2, the angiopoietin receptor Tie1/2, HGF, and PECAM-1) first in cirrhotic and HCC patients separately, and then comparing cirrhotic patients with and without HCC. Materials and Methods: We enrolled 62 patients, out of whom 33 were diagnosed with HCC and 29 with liver cirrhosis without signs of neoplasia. Patients underwent venous blood sampling before and after receiving treatments for the diagnosed disease. Serum markers were evaluated using ELISA assays for Tie1 and the Bio-Plex Multiplex system for the remaining ones. Biomarker levels were investigated as a function of clinical scores for disease staging (MELD and Fibrosis Index, FI). Results: In cirrhotic patients, Ang-1 and Ang-2 correlate with MELD (ρ_Ang-1 = −0.73, p = 2E−5) and FI (ρ_Ang-1 = −0.52, p = 7E−3, ρ_Ang-2 = 0.53, p = 3E−3). A reduction of Ang-2 levels (p = 0.047) and of the Ang-2/Ang-1 ratio (p = 0.031) is observed in cirrhotic patients diagnosed with viral hepatitis after antiviral treatments. In HCC patients, Ang-1 negatively correlates with FI (ρ = −0.63, p = 1E−4), and PECAM-1 positively correlates with MELD (ρ = 0.44, p = 0.01). A significant Ang-1 reduction was observed in deceased patients during the study compared to ones who survived (p = 0.01). In HCC patients, VEGF levels were increased after tumor treatment (p = 0.037). Notably, HGF levels in cirrhotic patients with HCC are significantly raised (p = 0.017) compared to that in those without HCC. Conclusions: Our results suggest that serum angiogenic markers, with emphasis on Ang-1/2, can contribute to the development of quantitative tools for liver disease staging and therapy monitoring. The comparison between cirrhotic patients with and without HCC suggests that HGF levels are potentially useful for monitoring the insurgence of HCC after a cirrhosis diagnosis. High Ang-1 levels in HCC patients appear to have a protective role as well as prognostic significance.

Modulation of the Permeability-Inducing Factor Angiopoietin-2 Through Bifonazole in Systemic Inflammation

BACKGROUND

Vascular barrier breakdown in sepsis represents a key component of the maladaptive host response to infection and the release of endothelial Angiopoietin-2 (Angpt-2) is a mechanistic driver of endothelial hyperpermeability. Angpt-2 is associated with morbidity and mortality but a targeted therapeutic approach is not available. We screened for U.S. Food and Drug Administration (FDA) approved drugs that might have off-target effects decreasing Angpt-2 and therefore, ameliorating capillary leakage.

METHODS

Endothelial cells were isolated from human umbilical veins (HUVECs) and used for in vitro studies at baseline and after stimulation (FDA-library screening, RT-PCR, ELISA, immunocytochemistry, MTT assay). On the functional level, we assessed real-time transendothelial electrical resistance (TER) using an electric cell-substrate impedance sensing device.

RESULTS

We found that the anti-fungal Bifonazole (BIFO) reduces spontaneous Angpt-2 release in a time- and dose-dependent manner after 8, 12, and 24 h (24 h: veh: 15.6 ± 0.7 vs. BIFO: 8.6 ± 0.8 ng/mL, P < 0.0001). Furthermore, we observed a reduction in its intra-cellular content by 33% (P < 0.001). Stimulation with tumor necrosis factor α induced a strong release of Angpt-2 that could analogously be blocked by additional treatment with BIFO (veh: 1.58 ± 0.2 vs. BIFO: 1.02 ± 0.1, P < 0.0001). Quantification of endothelial permeability by TER revealed that BIFO was sufficient to reduce Thrombin-induced barrier breakdown (veh: 0.82 ± 0.1 vs. BIFO: 1.01 ± 0.02, P < 0.05).

CONCLUSION

The antifungal BIFO reduces both release and biosynthesis of the endothelial-destabilizing factor Angpt-2 in vitro thereby improving vascular barrier function. Additional studies are needed to further investigate the underlying mechanism and to translate these findings to in vivo models.

Combining CTLA-4 and angiopoietin-2 blockade in patients with advanced melanoma: a phase I trial

Background

Angiogenic factors promote the growth of tumor vasculature, modulate lymphocyte trafficking into tumors, and inhibit maturation of dendritic cells. We hypothesized that MEDI3617, a human IgG1 kappa monoclonal antibody directed against human angiopoietin-2, in combination with tremelimumab (treme), an IgG2 monoclonal antibody blocking cytotoxic T-lymphocyte-associated protein- (CTLA-4), is safe in patients with advanced melanoma.

Methods

In a phase I, 3+3 dose escalation trial, patients with metastatic or unresectable melanoma received treme in combination with MEDI3617. The primary objectives of the study were safety and determination of recommended phase II dose (RP2D). The secondary objectives included determination of 6-month and 1-year overall survival and best overall response rate. Immune cell populations and soluble factors were assessed in peripheral blood and metastatic tumors using Fluorescence activated cell sorting (FACS), Luminex, and multiplexed immunofluorescence.

Results

Fifteen patients (median age: 62) were enrolled in the study (3 patients in cohort 1: treme at 10 mg/kg and MEDI3617 at 200 mg; and 12 patients in cohort 2: treme at 10 mg/kg and MEDI3617 at 600 mg). The most common all-grade treatment-related adverse events were rash, pruritus, fatigue, and extremity edema. No dose-limiting toxicities were observed. Cohort 2 was determined to be the RP2D. There were no patients with confirmed immune-related complete response or immune-related partial response. Six of 15 patients had immune-related stable disease, resulting in a disease control rate of 0.40 (95% CI 0.16 to 0.68). An increase in frequencies of circulating inducible T-cell costimulator (ICOS)⁺ and human leukocyte antigen (HLA)-DR⁺ CD4⁺ and CD8⁺ T cells and production of Interleukin-2 and Interleukin-10 was observed post therapy.

Conclusions

Tremelimumab in combination with MEDI3617 is safe in patients with advanced melanoma. Angiopoietin-2 inhibition in combination with immune checkpoint inhibition warrants further exploration.

Trial registration number

NCT02141542.

The Angiopoietin-Tie2 axis contributes to placental vascular disruption and adverse birth outcomes in malaria in pregnancy

Background

Malaria during pregnancy is a major contributor to the global burden of adverse birth outcomes including fetal growth restriction, preterm birth, and fetal loss. Recent evidence supports a role for angiogenic dysregulation and perturbations to placental vascular development in the pathobiology of malaria in pregnancy. The Angiopoietin-Tie2 axis is critical for placental vascularization and remodeling. We hypothesized that disruption of this pathway would contribute to malaria-induced adverse birth outcomes.

Methods

Using samples from a previously conducted prospective cohort study of pregnant women in Malawi, we measured circulating levels of angiopoietin-1 (Angpt-1) and Angpt-2 by Luminex (n=1392). We used a preclinical model of malaria in pregnancy (Plasmodium berghei ANKA [PbA] in pregnant BALB/c mice), genetic disruption of Angpt-1 (Angpt1^+/− mice), and micro-CT analysis of placental vasculature to test the hypothesis that disruptions to the Angpt-Tie2 axis by malaria during pregnancy would result in aberrant placental vasculature and adverse birth outcomes.

Findings

Decreased circulating levels of Angpt-1 and an increased ratio of Angpt-2/Angpt-1 across pregnancy were associated with malaria in pregnancy. In the preclinical model, PbA infection recapitulated disruptions to the Angiopoietin-Tie2 axis resulting in reduced fetal growth and viability. Malaria decreased placental Angpt-1 and Tie2 expression and acted synergistically with reduced Angpt-1 in heterozygous dams (Angpt1^+/−), to worsen birth outcomes by impeding vascular remodeling required for placental function.

Interpretation

Collectively, these data support a mechanistic role for the Angpt-Tie2 axis in malaria in pregnancy, including a potential protective role for Angpt-1 in mitigating infection-associated adverse birth outcomes.

Funding

This work was supported by the Canadian Institutes of Health Research (CIHR), Canada Research Chair, and Toronto General Research Institute Postdoctoral Fellowship Award. The parent trial was supported by the European & Developing Countries Clinical Trials Partnership and the Malaria in Pregnancy Consortium, which was funded by the Bill & Melinda Gates Foundation. The funders had no role in design, analysis, or reporting of these studies.

Deciphering the focal role of endostatin in Alzheimer's disease

Alzheimer's disease (AD) is a paramount chronic neurodegenerative condition that has been affecting elderly people since the 1900s. It causes memory loss, disorientation, and poor mental function. AD is considered to be one of the most serious problems that dementia sufferers face. Despite extensive investigation, the pathological origin of Alzheimer's disease remains a mystery. The amyloid cascade theory and the vascular hypothesis, which stresses the buildup of Aβ plaques, have dominated research into dementia and aging throughout history. However, research into this task failed to yield the long-awaited therapeutic miracle lead for Alzheimer's disease. Perhaps a hypothetical fragility in the context of Alzheimer's disease was regarded as a state distinct from aging in general, as suggested by the angiogenesis hypothesis, which suggests that old age is one state associated with upregulation of angiogenic growth factors, resulting in decreased microcirculation throughout the body. There has also been evidence that by controlling or inhibiting the components involved in the sequence of events that cause angiogenesis, there is a visible progression in AD patients. In Alzheimer's disease, one such antiangiogenic drug is being used.

Placental pathology in women with HIV

Recognizing the importance of placental features and their unique functions can provide insight into maternal health, the uterine environment during the course of pregnancy, birth outcomes and neonatal health. In the context of HIV and antiretroviral therapy (ART), there have been great strides in the prevention of mother to child transmission of HIV. However, there is still paucity of data on the impact of HIV/ART exposure on placental pathology and studies available only examine specific patterns of placental injury, further justifying the need for a more defined and comprehensive approach to the differential diagnoses of HIV/ART-exposed placentae. The purpose of this review is to consolidate findings from individual studies that have been reported on patterns of placental injury in the context of HIV/ART exposure. In both the pre- and post-ART eras HIV and/or ART has been associated with placental injury including maternal vascular malperfusion as well as acute and chronic inflammation. These patterns of injury are further associated with adverse birth outcomes including preterm birth and current evidence suggests an association between poor placental function and compromised fetal development. With the ever increasing number of pregnant women with HIV on ART, there is a compelling need for full incorporation of placental diagnoses into obstetric disease classification. It is also important to take into account key elements of maternal clinical history. Lastly, there is a need to standardize the reporting of placental pathology in order to glean additional insight into the elucidation of HIV/ART associated placental injury.

Single-Cell Transcriptome Profiling Reveals the Suppressive Role of Retinal Neurons in Microglia Activation Under Diabetes Mellitus

Diabetic retinopathy, as one of the common complications of diabetes mellitus, is the leading cause of blindness in the working-age population worldwide. The disease is characterized by damage to retinal vasculature, which is associated with the activation of retina microglial and induces chronic neurodegeneration. Previous studies have identified the effects of activated microglial on the retinal neurons, but the cellular and molecular mechanisms underlying microglial activation is largely unknown. Here, we performed scRNA-seq on the retina of non-human primates with diabetes mellitus, and identified cell-type-specific molecular changes of the six major cell types. By identifying the ligand-receptor expression patterns among different cells, we established the interactome of the whole retina. The data showed that TNF-α signal mediated the activation of microglia through an autocrine manner. And we found TGFβ2, which was upregulated in cone dramatically by hyperglycemia, inhibited microglia activation at the early stage of diabetic retinopathy. In summary, our study is the first to profile cell-specific molecular changes and the cell-cell interactome of retina under diabetes mellitus, paving a way to dissect the cellular and molecular mechanisms underlying early-stage diabetic retinopathy.

Niclosamide suppresses macrophage-induced inflammation in endometriosis†

Endometriosis is a common gynecological disease, which causes chronic pelvic pain and infertility in women of reproductive age. Due to limited efficacy of current treatment options, a critical need exists to develop new and effective treatments for endometriosis. Niclosamide is an efficacious and FDA-approved drug for the treatment of helminthosis in humans that has been used for decades. We have reported that niclosamide reduces growth and progression of endometriosis-like lesions via targeting STAT3 and NFĸB signaling in a mouse model of endometriosis. To examine the effects of niclosamide on macrophage-induced inflammation in endometriosis, a total of 29 stage III-IV endometrioma samples were used to isolate human endometriotic stromal cells (hESCs). M1 or M2 macrophages were isolated and differentiated from fresh human peripheral blood samples. Then, hESCs were cultured in conditioned media (CM) from macrophages with/without niclosamide. Niclosamide dose dependently reduced cell viability and the activity of STAT3 and NFκB signaling in hESCs. While macrophage CM stimulated cell viability in hESCs, niclosamide inhibited this stimulation. Macrophage CM stimulated the secretion of proinflammatory cytokines and chemokines from hESCs. Most of these secreted factors were inhibited by niclosamide. These results indicate that niclosamide is able to reduce macrophage-induced cell viability and cytokine/chemokine secretion in hESCs by inhibiting inflammatory mechanisms via STAT3 and/or NFκB signaling.

Putting function back in dysfunction: Endothelial diseases and current therapies in hematopoietic stem cell transplantation and cellular therapies

Endothelial dysfunction is characterized by altered vascular permeability and prothrombotic, pro-inflammatory phenotypes. Endothelial dysfunction results in end-organ damage and has been associated with diverse disease pathologies. Complications observed after hematopoietic stem cell transplantation (HCT) and chimeric antigen receptor-T cell (CAR-T) therapy for hematologic and neoplastic disorders share overlapping clinical manifestations and there is increasing evidence linking these complications to endothelial dysfunction. Despite advances in supportive care and treatments, end-organ toxicity remains the leading cause of mortality. A new strategy to mitigate endothelial dysfunction could lead to improvement of clinical outcomes for patients. Statins have demonstrated pleiotropic effects of immunomodulatory and endothelial protection by various molecular mechanisms. Recent applications in immune-mediated diseases such as autoimmune disorders, chronic inflammatory conditions, and graft-versus-host disease (GVHD) have shown promising results. In this review, we cover the mechanisms underlying endothelial dysfunction in GVHD and CAR-T cell-related toxicities. We summarize the current knowledge about statins and other agents used as endothelial protectants. We propose further studies using statins for prophylaxis and prevention of end-organ damage related to extensive endothelial dysfunction in HCT and CAR-T.

Circulating proteins protect against renal decline and progression to end-stage renal disease in patients with diabetes

Diabetic kidney disease (DKD) and its major clinical manifestation, progressive renal decline that leads to end-stage renal disease (ESRD), are a major health burden for individuals with diabetes. The disease process that underlies progressive renal decline comprises factors that increase risk as well as factors that protect against this outcome. Using untargeted proteomic profiling of circulating proteins from individuals in two independent cohorts with type 1 and type 2 diabetes and varying stages of DKD followed for 7 to 15 years, we identified three elevated plasma proteins-fibroblast growth factor 20 (OR, 0.69; 95% CI, 0.54 to 0.88), angiopoietin-1 (OR, 0.72; 95% CI, 0.57 to 0.91), and tumor necrosis factor ligand superfamily member 12 (OR, 0.75; 95% CI, 0.59 to 0.95)-that were associated with protection against progressive renal decline and progression to ESRD. The combined effect of these three protective proteins was demonstrated by very low cumulative risk of ESRD in those who had baseline concentrations above median for all three proteins, whereas the cumulative risk of ESRD was high in those with concentrations below median for these proteins at the beginning of follow-up. This protective effect was shown to be independent from circulating inflammatory proteins and clinical covariates and was confirmed in a third cohort of diabetic individuals with normal renal function. These three protective proteins may serve as biomarkers to stratify diabetic individuals according to risk of progression to ESRD and might also be investigated as potential therapeutics to delay or prevent the onset of ESRD.

Melatonin as an Adjuvant to Antiangiogenic Cancer Treatments

Melatonin is a hormone with different functions, antitumor actions being one of the most studied. Among its antitumor mechanisms is its ability to inhibit angiogenesis. Melatonin shows antiangiogenic effects in several types of tumors. Combination of melatonin and chemotherapeutic agents have a synergistic effect inhibiting angiogenesis. One of the undesirable effects of chemotherapy is the induction of pro-angiogenic factors, whilst the addition of melatonin is able to overcome these undesirable effects. This protective effect of the pineal hormone against angiogenesis might be one of the mechanisms underlying its anticancer effect, explaining, at least in part, why melatonin administration increases the sensitivity of tumors to the inhibitory effects exerted by ordinary chemotherapeutic agents. Melatonin has the ability to turn cancer totally resistant to chemotherapeutic agents into a more sensitive chemotherapy state. Definitely, melatonin regulates the expression and/or activity of many factors involved in angiogenesis which levels are affected (either positively or negatively) by chemotherapeutic agents. In addition, the pineal hormone has been proposed as a radiosensitizer, increasing the oncostatic effects of radiation on tumor cells. This review serves as a synopsis of the interaction between melatonin and angiogenesis, and we will outline some antiangiogenic mechanisms through which melatonin sensitizes cancer cells to treatments, such as radiotherapy or chemotherapy.

Circular RNAs: Novel target of diabetic retinopathy

In diabetic patients, diabetic retinopathy (DR) is the leading cause of blindness and seriously affects the quality of life. However, current treatment methods of DR are not satisfactory. Advances have been made in understanding abnormal protein interactions and signaling pathways in DR pathology, but little is known about epigenetic regulation. Non-coding RNAs, such as circular RNAs (circRNAs), have been shown to be associated with DR. In this review, we summarized the function of circRNAs and indicated their roles in the pathogenesis of DR, which may provide new therapeutic targets for clinical treatment.

miR‑135a‑5p inhibits tumor invasion by targeting ANGPT2 in gallbladder cancer

Gallbladder cancer (GBC) is the most aggressive cancer type in the biliary tract, and our previous studies observed that microRNA (miR)-135a-5p expression was downregulated in GBC tissues. However, few studies have focused on the mechanism of action of the miR-135a-5p target genes in GBC. The present study aimed to investigate the regulatory role of miR-135a-5p signaling in GBC. The present study found that miR-135a-5p expression was downregulated in GBC tissue, as detected by immunohistochemistry and reverse transcription-quantitative PCR. In addition, overexpression of miR-135a-5p significantly inhibited the proliferation and migration of GBC-SD cells. Using a luciferase activity assay, it was identified that angiopoietin-2 (ANGPT2) was a potential target gene of miR-135a-5p in GBC. Knockdown of ANGPT2 expression significantly inhibited the proliferation and invasion of GBC-SD cells. In conclusion, the present results suggested that miR-135a-5p affected GBC cell proliferation and invasion by targeting ANGPT2. Moreover, miR-135a-5p may be a potential biomarker for GBC progression and a potential target for GBC therapeutic intervention.

DPP4 Activity, Hyperinsulinemia, and Atherosclerosis

CONTEXT

Obesity and type 2 diabetes are associated with chronic hyperinsulinemia, elevated plasma levels of dipeptidyl peptidase-4 (DPP4), and a pro-atherosclerotic milieu.

EVIDENCE ACQUISITION

PubMed search of the term "insulin and atherosclerosis," "hyperinsulinemia," "atherosclerosis," or "cardiovascular outcomes" cross-referenced with "DPP4." Relevant research and review articles were reviewed.

EVIDENCE SYNTHESIS

Hyperinsulinemia in the setting of insulin resistance promotes vascular inflammation, vascular smooth muscle cell growth, pathological cholesterol profile, hypertension, and recruitment of immune cells to the endothelium, all contributing to atherosclerosis. DPP4 has pleiotropic functions and its activity is elevated in obese humans. DPP4 mirrors hyperinsulinemia's atherogenic actions in the insulin resistant state, and genetic deletion of DPP4 protects rodents from developing insulin resistance and improves cardiovascular outcomes. DPP4 inhibition in pro-atherosclerotic preclinical models results in reduced inflammation and oxidative stress, improved endothelial function, and decreased atherosclerosis. Increased incretin levels may have contributed to but do not completely account for these benefits. Small clinical studies with DPP4 inhibitors demonstrate reduced carotid intimal thickening, improved endothelial function, and reduced arterial stiffness. To date, this has not been translated to cardiovascular risk reduction for individuals with type 2 diabetes with prior or exaggerated risk of cardiovascular disease.

CONCLUSION

DPP4 may represent a key link between central obesity, insulin resistance, and atherosclerosis. The gaps in knowledge in DPP4 function and discrepancy in cardiovascular outcomes observed in preclinical and large-scale randomized controlled studies with DPP4 inhibitors warrant additional research.

Imaging the Renal Microcirculation in Cell Therapy

Renal microvascular rarefaction plays a pivotal role in progressive kidney disease. Therefore, modalities to visualize the microcirculation of the kidney will increase our understanding of disease mechanisms and consequently may provide new approaches for evaluating cell-based therapy. At the moment, however, clinical practice is lacking non-invasive, safe, and efficient imaging modalities to monitor renal microvascular changes over time in patients suffering from renal disease. To emphasize the importance, we summarize current knowledge of the renal microcirculation and discussed the involvement in progressive kidney disease. Moreover, an overview of available imaging techniques to uncover renal microvascular morphology, function, and behavior is presented with the associated benefits and limitations. Ultimately, the necessity to assess and investigate renal disease based on in vivo readouts with a resolution up to capillary level may provide a paradigm shift for diagnosis and therapy in the field of nephrology.

Biomarkers of Angiogenesis and Neuroplasticity as Promising Clinical Tools for Stroke Recovery Evaluation

Several key issues impact the clinical practice of stroke rehabilitation including a patient’s medical history, stroke experience, the potential for recovery, and the selection of the most effective type of therapy. Until clinicians have answers to these concerns, the treatment and rehabilitation are rather intuitive, with standard procedures carried out based on subjective estimations using clinical scales. Therefore, there is a need to find biomarkers that could predict brain recovery potential in stroke patients. This review aims to present the current state-of-the-art stroke recovery biomarkers that could be used in clinical practice. The revision of biochemical biomarkers has been developed based on stroke recovery processes: angiogenesis and neuroplasticity. This paper provides an overview of the biomarkers that are considered to be ready-to-use in clinical practice and others, considered as future tools. Furthermore, this review shows the utility of biomarkers in the development of the concept of personalized medicine. Enhancing brain neuroplasticity and rehabilitation facilitation are crucial concerns not only after stroke, but in all central nervous system diseases.

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.

Ultrafiltration and Injection of Islet Regenerative Stimuli Secreted by Pancreatic Mesenchymal Stromal Cells

The secretome of mesenchymal stromal cells (MSCs) is enriched for biotherapeutic effectors contained within and independent of extracellular vesicles (EVs) that may support tissue regeneration as an injectable agent. We have demonstrated that the intrapancreatic injection of concentrated conditioned media (CM) produced by bone marrow MSC supports islet regeneration and restored glycemic control in hyperglycemic mice, ultimately providing a platform to elucidate components of the MSC secretome. Herein, we extend these findings using human pancreas-derived MSC (Panc-MSC) as "biofactories" to enrich for tissue regenerative stimuli housed within distinct compartments of the secretome. Specifically, we utilized 100 kDa ultrafiltration as a simple method to debulk protein mass and to enrich for EVs while concentrating the MSC secretome into an injectable volume for preclinical assessments in murine models of blood vessel and islet regeneration. EV enrichment (EV+) was validated using nanoscale flow cytometry and atomic force microscopy, in addition to the detection of classical EV markers CD9, CD81, and CD63 using label-free mass spectrometry. EV+ CM was predominately enriched with mediators of wound healing and epithelial-to-mesenchymal transition that supported functional regeneration in mesenchymal and nonmesenchymal tissues. For example, EV+ CM supported human microvascular endothelial cell tubule formation in vitro and enhanced the recovery of blood perfusion following intramuscular injection in nonobese diabetic/severe combined immunodeficiency mice with unilateral hind limb ischemia. Furthermore, EV+ CM increased islet number and β cell mass, elevated circulating insulin, and improved glycemic control following intrapancreatic injection in streptozotocin-treated mice. Collectively, this study provides foundational evidence that Panc-MSC, readily propagated from the subculture of human islets, may be utilized for regenerative medicine applications.

Dynamic angiopoietin-2 assessment predicts survival and chronic course in hospitalized patients with COVID-19

This study examined the association between dynamic angiopoietin-2 assessment and COVID-19 short- and long-term clinical course. We included consecutive hospitalized patients from 1 February to 31 May 2020 with laboratory-confirmed COVID-19 from 2 Italian tertiary referral centers (derivation cohort, n = 187 patients; validation cohort, n = 62 patients). Serum biomarker levels were measured by sandwich enzyme-linked immunosorbent assay. Lung tissue from 9 patients was stained for angiopoietin-2, Tie2, CD68, and CD34. Cox model was used to identify risk factors for mortality and nonresolving pulmonary condition. Area under the receiver operating characteristic curve (AUROC) was used to assess the accuracy of 3- and 10-day angiopoietin-2 for in-hospital mortality and nonresolving pulmonary condition, respectively. Three-day angiopoietin-2 increase of at least twofold from baseline was significantly associated with in-hospital mortality by multivariate analysis (hazard ratio [HR], 6.69; 95% confidence interval [CI], 1.85-24.19; P = .004) with AUROC = 0.845 (95% CI, 0.725-0.940). Ten-day angiopoietin-2 of at least twofold from baseline was instead significantly associated with nonresolving pulmonary condition by multivariate analysis (HR, 5.33; 95% CI, 1.34-11.77; P ≤ .0001) with AUROC = 0.969 (95% CI, 0.919-1.000). Patients with persistent elevation of 10-day angiopoietin-2 levels showed severe reticular interstitial thickening and fibrous changes on follow-up computed tomography scans. Angiopoietin-2 and Tie2 were diffusely colocalized in small-vessel endothelia and alveolar new vessels and macrophages. Angiopoietin-2 course is strongly associated with COVID-19 in-hospital mortality and nonresolving pulmonary condition. Angiopoietin-2 may be an early and useful predictor of COVID-19 clinical course, and it could be a relevant part of disease pathogenesis. Angiopoietin-2 blockade may be a COVID-19 treatment option.

Accuracy of angiopoietin-2 for predicting organ failure in patients with acute pancreatitis: a systematic review and meta-analysis

Objective

Our aim was to assess the accuracy of angiopoietin-2 (Ang-2) as a prognostic marker for acute pancreatitis (AP) with organ failure (OF).

Methods

We undertook a systematic search of the PubMed, Cochrane Library, Embase, Chinese Journals Full-text, Wanfang, China Biology Medicine disc, and Weipu databases to identify eligible cohort studies on the predictive value of Ang-2 for AP with OF. The main outcome measures were sensitivity and specificity. The effects were pooled using a bivariate mixed-effects model.

Results

Six articles with seven case-control studies (n = 650) were included. Pooled sensitivity, specificity, and positive and negative likelihood ratios with 95% confidence intervals (CI) for AP with OF were 0.93 (95%CI: 0.75–0.99), 0.85 (95%CI: 0.75–0.92), 6.40 (95%CI: 3.36–12.19), and 0.08 (95%CI: 0.02–0.36), respectively. The area under the summary receiver operating characteristic curve was 0.95 (95%CI: 0.92–0.96), and the diagnostic odds ratio was 83.18 (95%CI: 11.50–623.17). Subgroup analysis showed that admission time of AP onset (< or ≥24 hours) was a source of overall heterogeneity. Sensitivity analysis supported this finding.

Conclusion

Ang-2 had high diagnostic accuracy for AP with OF; the best prediction of Ang-2 may be 24 to 72 hours after onset of AP.

Procalcitonin as a Marker of Comorbid Atrial Fibrillation in Chronic Kidney Disease and History of Sepsis

Cardiovascular disease and infection are the leading causes of mortality in patients with stage 5 chronic kidney disease on hemodialysis (CKD5-HD). Inflammation is a large component in the pathogenesis of both atrial fibrillation (AF) and sepsis and may link these conditions in CKD5-HD. Procalcitonin (PCT) is an inflammatory biomarker elevated in systemic infection and CKD5-HD, yet its value with regard to comorbid AF has not been thoroughly investigated. The aim of this study sought to evaluate circulating inflammatory markers, including PCT, Angiopoietin-1, Angiopoetin-2, CD40-L, C-reactive protein, d-dimer, and von Willebrand factor in relation to these conditions. Plasma levels of inflammatory markers were measured by enzyme linked immunosorbent assay method in CKD5-HD (n = 97) patients and controls (n = 50). Procalcitonin levels were significantly elevated (P = .0270) in CKD5-HD with comorbid AF compared to those without AF. Further analysis of patients with a history of sepsis demonstrated significantly elevated levels of PCT (P = .0405) in those with comorbid AF (160.7 ± 39.5 pg/mL) compared to those without AF (117.4 ± 25.3 pg/mL). This study demonstrates that the inflammatory biomarker PCT is further elevated in the presence of both AF and a history of sepsis in hemodialysis patients and suggests that underlying chronic inflammation following sepsis resolution may place these patients at greater risk of developing AF.

ICU Admission Levels of Endothelial Biomarkers as Predictors of Mortality in Critically Ill COVID-19 Patients

Endotheliopathy is suggested to be an important feature of COVID-19 in hospitalized patients. To determine whether endotheliopathy is involved in COVID-19-associated mortality, markers of endothelial damage were assessed in critically ill COVID-19 patients upon intensive care unit (ICU) admission. Thirty-eight critically ill COVID-19 patients were included in this observational study, 10 of whom died in the ICU. Endothelial biomarkers, including soluble (s)E-selectin, sP-selectin, angiopoietin 1 and 2 (Ang-1 and Ang-2, respectively), soluble intercellular adhesion molecule 1 (sICAM-1), vascular endothelial growth factor (VEGF), soluble vascular endothelial (VE)-cadherin, and von Willebrand factor (vWf), were measured upon ICU admission. The ICU cohort was subsequently divided into survivors and non-survivors; Kaplan-Meier analysis was used to explore associations between biomarkers and survival, while receiver operating characteristic (ROC) curves were generated to determine their potential prognostic value. sE-selectin, sP-selectin, Ang-2, and sICAM-1 were significantly elevated in ICU non-survivors compared to survivors, and also associated with a higher mortality probability in the Kaplan-Meier analysis. The prognostic values of sE-selectin, Ang-2, and sICAM-1 from the generated ROC curves were greater than 0.85. Hence, we conclude that in our cohort, ICU non-survivors had higher levels of specific endothelial markers compared to survivors. Elevated levels of these markers upon ICU admission could possibly predict mortality in COVID-19.

Serum levels and gene polymorphisms of angiopoietin 2 in systemic lupus erythematosus patients

This study aimed to discuss association between serum Angiopoietin2 (Ang2) levels, Ang2 gene polymorphisms and systemic lupus erythematosus (SLE) susceptibility. It was carried out by 235 SLE, 342 other inflammatory autoimmune diseases patients and 380 healthy individuals. Serum Ang2 levels was examinated by ELISA, and Ang2 rs12674822, rs1823375, rs1868554, rs2442598, rs3739390 and rs734701 polymorphisms were genotyped using KASP. Increased Ang2 concentrations in SLE patients were observed compared with healthy controls and patients with other inflammatory autoimmune diseases. For allelic contrast, except for rs1823375 (P = 0.058) and rs2442598 (P = 0.523), frequencies of alleles for other polymorphisms were significantly different between SLE patients and controls. Genotypes for rs12674822 (TT), rs1868554 (TT, TA and TT+TA), rs734701 (TT) were negatively correlated with SLE susceptibility (OR = 0.564 for rs12674822; OR = 0.572, OR = 0.625, OR = 0.607 for rs1868554; OR = 0.580 for rs734701). Patients carrying rs1868554 T allele and rs3739390 G allele were more likely to develop hematuria (P = 0.039; P = 0.003). The G allele frequencies of rs12674822 and rs2442598 were higher in SLE patients with proteinuria (P = 0.043; P = 0.043). GC genotype frequency of rs3739390 was higher in patients with ds-DNA (+) (P = 0.024). In summary, SLE had increased serum Ang2, which may be a potential biomarker, and the polymorphisms correlated with SLE.

Angiopoietin-2 blockade ameliorates autoimmune neuroinflammation by inhibiting leukocyte recruitment into the CNS

Angiopoietin-2 (Ang2), a ligand of the endothelial Tie2 tyrosine kinase, is involved in vascular inflammation and leakage in critically ill patients. However, the role of Ang2 in demyelinating central nervous system (CNS) autoimmune diseases is unknown. Here, we report that Ang2 is critically involved in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), a rodent model of multiple sclerosis. Ang2 expression was induced in CNS autoimmunity, and transgenic mice overexpressing Ang2 specifically in endothelial cells (ECs) developed a significantly more severe EAE. In contrast, treatment with Ang2-blocking Abs ameliorated neuroinflammation and decreased spinal cord demyelination and leukocyte infiltration into the CNS. Similarly, Ang2-binding and Tie2-activating Ab attenuated the development of CNS autoimmune disease. Ang2 blockade inhibited expression of EC adhesion molecules, improved blood-brain barrier integrity, and decreased expression of genes involved in antigen presentation and proinflammatory responses of microglia and macrophages, which was accompanied by inhibition of α5β1 integrin activation in microglia. Taken together, our data suggest that Ang2 provides a target for increasing Tie2 activation in ECs and inhibiting proinflammatory polarization of CNS myeloid cells via α5β1 integrin in neuroinflammation. Thus, Ang2 targeting may serve as a therapeutic option for the treatment of CNS autoimmune disease.

Vanucizumab mode of action: Serial biomarkers in plasma, tumor, and skin-wound-healing biopsies

Vanucizumab is a novel bispecific antibody inhibiting vascular endothelial growth factor (VEGF-A) and angiopoietin-2 (Ang-2) that demonstrated safety and anti-tumor activity in part I of a phase I study of 42 patients with advanced solid tumors. Part II evaluated the pharmacodynamic effects of vanucizumab 30 or 15 mg/kg every 2 weeks in 32 patients. Serial plasma samples, paired tumor, and skin-wound-healing biopsies were taken over 29 days to evaluate angiogenic markers. Vanucizumab was associated with marked post-infusion reductions in circulating unbound VEGF-A and Ang-2. By day 29, tumor samples revealed mean reductions in density of microvessels (-32.2%), proliferating vessels (-47.9%) and Ang-2 positive vessels (-62.5%). Skin biopsies showed a mean reduction in density of microvessels (-49.0%) and proliferating vessels (-25.7%). Gene expression profiling of tumor samples implied recruitment and potential activation of lymphocytes. Biopsies were safely conducted. Vanucizumab demonstrated a consistent biological effect on vascular-related biomarkers, confirming proof of concept. Skin-wound-healing biopsies were a valuable surrogate for studying angiogenesis-related mechanisms.

Thalidomide Inhibits Angiogenesis via Downregulation of VEGF and Angiopoietin-2 in Crohn's Disease

Immune-mediated angiogenesis is important in the pathogenesis of inflammatory bowel disease and targeted treatment could alleviate the disease. Thalidomide is an effective drug in inflammatory bowel disease, which might be related to its multiple role in anti-inflammatory, immunoregulatory, and anti-angiogenesis. This study is to investigate the effect of thalidomide on angiogenesis in tissues from patients and in vitro cells. Angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), VEGF, and CD31 expressions in intestinal mucosa from pediatric CD patients before and after thalidomide treatment were measured by immunohistochemistry. Western blotting and polymerase chain reaction were performed to characterize the change of angiogenic factors before and after treatment in remission. Human umbilical vein endothelial cells (HUVECs) treated by thalidomide were used to examine its effect on endothelial cell proliferation and migration and capillary-like structures. Results showed that VEGF and Ang-2 levels were significantly greater in CD patients over controls. Thalidomide produced a significant reduction in protein expression of Ang-2 and VEGF, along with a decrease in mRNA expression of Ang-2. While, Ang-1 level did not show a statistically significant change. Thalidomide significantly inhibited cell proliferation in a dose-dependent manner. It also suppressed VEGF- and Ang-2-induced cell migration and capillary-like tube formation in HUVECs. Therefore, our study suggests that VEGF and Ang-2 levels are up-regulated in pediatric CD patients. It also indicated that thalidomide can be able to deactivate endothelium by the downregulation effect on angiogenic factors by targeting VEGF and Ang-2.

Proteomics and Informatics for Understanding Phases and Identifying Biomarkers in COVID-19 Disease

The emergence of novel coronavirus disease 2019 (COVID-19), caused by the SARS-CoV-2 coronavirus, has necessitated the urgent development of new diagnostic and therapeutic strategies. Rapid research and development, on an international scale, has already generated assays for detecting SARS-CoV-2 RNA and host immunoglobulins. However, the complexities of COVID-19 are such that fuller definitions of patient status, trajectory, sequelae, and responses to therapy are now required. There is accumulating evidence-from studies of both COVID-19 and the related disease SARS-that protein biomarkers could help to provide this definition. Proteins associated with blood coagulation (D-dimer), cell damage (lactate dehydrogenase), and the inflammatory response (e.g., C-reactive protein) have already been identified as possible predictors of COVID-19 severity or mortality. Proteomics technologies, with their ability to detect many proteins per analysis, have begun to extend these early findings. To be effective, proteomics strategies must include not only methods for comprehensive data acquisition (e.g., using mass spectrometry) but also informatics approaches via which to derive actionable information from large data sets. Here we review applications of proteomics to COVID-19 and SARS and outline how pipelines involving technologies such as artificial intelligence could be of value for research on these diseases.

Chemically defined human vascular laminins for biologically relevant culture of hiPSC-derived brain microvascular endothelial cells

BACKGROUND

In recent years, differentiation of human induced pluripotent stem cells (hiPSCs) into brain-specific microvascular endothelial cells (iBMECs) has frequently been used to model the blood-brain barrier (BBB). However, there are limitations in the use of iBMECs for in vitro studies, such as transendothelial electrical resistance (TEER) instability, weak junctional expression of VE-cadherin, and lack of proper fluid shear stress response. In vivo, the basement membrane (BM) composition of the BBB evolves throughout development, and laminins become the dominant component of the mature vascular BM. However, laminin isoforms of the endothelial BM have not been used for culture of differentiated iBMECs. The main goal of this study is to investigate the effect of different laminin isoforms of the endothelial BM on iBMEC functionality and to determine whether better recapitulation of the physiological BM in vitro can address the aforementioned limitations of iBMECs.

METHODS

Using a previously reported method, hiPSCs were differentiated into iBMECs. The influence of main laminins of the endothelial BM, LN 411 and LN 511, on iBMEC functionality was studied and compared to a collagen IV and fibronectin mixture (CN IV-FN). Quantitative RT-PCR, immunocytochemistry, and TEER measurement were utilized to assess gene and protein expression and barrier properties of iBMECs on different extracellular matrices. Single-channel microfluidic devices were used to study the effect of shear stress on iBMECs.

RESULTS

LN 511, but not LN 411, improved iBMEC barrier properties and resulted in more sustained TEER stability. Immunocytochemistry showed improved junctional protein expression compared to iBMECs cultured on CN IV-FN. iBMECs cultured on LN 511 showed a reduction of stress fibers, indicating resting endothelial phenotype, whereas gene expression analysis revealed upregulation of multiple genes involved in endothelial activation in iBMECs on CN IV-FN. Finally, culturing iBMECs on LN 511 enhanced physiological responses to shear stress, including morphological changes and enhanced junctional protein association.

CONCLUSION

LN 511 improves the functionality and long-term barrier stability of iBMECs. Our findings suggest that incorporation of physiologically relevant LN 511 in iBMEC culture would be beneficial for disease modeling applications and BBB-on-a-chip platforms that accommodate fluid flow.

Treatment of Staphylococcus aureus skin infection in vivo using rifampicin loaded lipid nanoparticles

We have previously reported on a novel nanoparticle formulation that was effective at killing Staphylococcus aureus in vitro. Here, we report for the first time, the antibacterial effects of a lipidic nano-carrier containing rifampicin (NanoRIF) which can be used to successfully treat Methicillin-Resistant S. aureus (MRSA) infection at a reduced antibiotic dosage compared to the free drug in a skin wound model in mice. The formulation used contains the lipid monoolein, a cationic lipid N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium methyl-sulfate (DOTAP) and the antibiotic. We have shown that rifampicin-loaded nanoparticles are more effective at treating infection in the skin wound model than the antibiotic alone. Cryo-TEM was used to capture for the first time, interactions of the formed nanoparticles with the cell wall of an individual bacterium. Our data strongly indicate enhanced binding of these charged nanoparticles with the negatively charged bacterial membrane. The efficacy we have now observed in vivo is of significant importance for the continued development of nanomedicine-based strategies to combat antibiotic resistant bacterial skin infections.

Automated prediction of sepsis using temporal convolutional network

Multiple organ failure is the trademark of sepsis. Sepsis occurs when the body's reaction to infection causes injury to its tissues and organs. As a consequence, fluid builds up in the tissues causing organ failure and leading to septic shock eventually. Some symptoms of sepsis include fever, arrhythmias, blood vessel leaks, impaired clotting, and generalised inflammation. In order to address the limitations in current diagnosis, we have proposed a cost-effective automated diagnostic tool in this study. A deep temporal convolution network has been developed for the prediction of sepsis. Septic data was fed to the model and a high accuracy and area under ROC curve (AUROC) of 98.8% and 98.0% were achieved respectively, for per time-step metrics. A relatively high accuracy and AUROC of 95.5% and 91.0% were also achieved respectively, for per-patient metrics. This is a novel study in that it has investigated per time-step metrics, compared to other studies which investigated per-patient metrics. Our model has also been evaluated by three validation methods. Thus, the recommended model is robust with high accuracy and precision and has the potential to be used as a tool for the prediction of sepsis in hospitals.

Significance of Serum Angiopoietin-2 in Patients with Hemorrhage in Adult-Onset Moyamoya Disease

Background

Moyamoya disease (MMD) is a progressive occlusive cerebrovascular disease that is characterized by abnormal angiogenesis at the base of the brain. This pathological abnormal angiogenesis is susceptible to disturbances, including spontaneous hemorrhage and vasogenic edema. However, the underlying mechanisms of pathological angiogenesis and occurrence of hemorrhage are unclear. Angiopoietins play a fundamental role in the pathophysiology of central nervous system disorders in angiogenesis. This study was aimed at examining whether angiopoietins are associated with formation of abnormal collateral vessels and the occurrence of hemorrhage in adult-onset moyamoya disease (HMMD).

Methods

A total of 27 consecutive adult patients with HMMD were enrolled from June 2011 to May 2017. Serum levels of angiopoietin-1 (Ang-1) and angiopoietin-2 (Ang-2) were examined by enzyme-linked immunosorbent assay. Patients with HMMD were compared with those with spontaneous hemorrhage (controls) and nonhemorrhagic-onset MMD (NHMMD).

Results

Serum Ang-2 levels were significantly higher in patients with adult HMMD than in those with spontaneous hemorrhage and NHMMD. The ROC curve identified that a baseline serum Ang-2 level > 1230 ng/ml may be associated with adult HMMD with 88.39% sensitivity and 70.37% specificity (area under the curve (AUC), 0.89; 95% CI, 0.808-0.973; P < 0.001). Moreover, serum Ang-2 levels were significantly elevated in stages II, III, and IV. In subgroup analysis of a high and low degree of moyamoya vessels, serum Ang-2 levels were significantly higher in the high moyamoya vessel group than in the low moyamoya vessel group. Serum Ang-2 levels were also significantly higher in the low moyamoya vessel group compared with the control group. Serum Ang-1 levels were not significantly different among the groups.

Conclusion

Increased serum Ang-2 levels may contribute to pathological abnormal angiogenesis and/or to the instability of vascular structure and function, thus causing brain hemorrhage in adult HMMD.

Higher serum angiopoietin 2 levels are independently associated with coronary microvascular dysfunction in patients with angina in the absence of obstructive coronary artery disease

Background

Angiopoietin-2 (Ang-2) is a type of endothelial growth factor involved in angiogenesis and vascular remodeling. Circulating Ang-2 levels are elevated in patients with obstructive coronary artery disease (CAD). This study aimed to evaluate the association between serum Ang-2 levels and coronary microvascular dysfunction in patients without obstructive CAD.

Methods

A total of 125 patients with angina in the absence of obstructive CAD were included in this cross-sectional study. Coronary flow reserve (CFR) was measured in the distal left anterior descending coronary artery by trans-thoracic Doppler echocardiography. The patients were divided into the following two sub-groups according to CFR: the impaired CFR group with CFR values <2.5 and the preserved CFR group with CFR values ≥2.5. Serum Ang-2 levels were determined using enzyme-linked immunosorbent assay. Independent predictors for impaired CFR were identified by binary logistic regression analysis. The receiver-operating characteristic curve was determined to evaluate the ability of serum Ang-2 in predicting impaired CFR.

Results

We found that age, percentage of female sex, N-terminal pro-B-type natriuretic peptide levels, Ang-2 levels (763.3 ± 264.9 vs. 579.7 ± 169.3 pg/mL, P < 0.001), and the left atrial volume index were significantly higher in patients with impaired CFR than in patients with preserved CFR. Serum Ang-2 levels were negatively correlated with CFR (r = −0.386, P < 0.001). Binary logistic regression analysis showed that Ang-2 (odds ratio: 1.004, 95% confidence interval [CI]: 1.001–1.006, P = 0.003) and age (odds ratio: 1.088, 95% CI: 1.023–1.156, P = 0.007) were independently associated with impaired CFR. Furthermore, Ang-2 was a significant predictor of impaired CFR on the receiver-operating characteristic curve (P < 0.001). The area under the curve was 0.712 (95% CI: 0.612–0.813).

Conclusions

High serum Ang-2 levels are independently associated with impaired CFR in patients with angina in the absence of obstructive CAD.

Partial Deletion of Tie2 Affects Microvascular Endothelial Responses to Critical Illness in A Vascular Bed and Organ-Specific Way

Supplemental Digital Content is available in the text

Tyrosine kinase receptor (Tie2) is mainly expressed by endothelial cells. In animal models mimicking critical illness, Tie2 levels in organs are temporarily reduced. Functional consequences of these reduced Tie2 levels on microvascular endothelial behavior are unknown. We investigated the effect of partial deletion of Tie2 on the inflammatory status of endothelial cells in different organs. Newly generated heterozygous Tie2 knockout mice (exon 9 deletion, ΔE9/Tie2^+/−) exhibiting 50% reduction in Tie2 mRNA and protein, and wild-type littermate controls (Tie2^+/+), were subjected to hemorrhagic shock and resuscitation (HS + R), or challenged with i.p. lipopolysaccharide (LPS). Kidney, liver, lung, heart, brain, and intestine were analyzed for mRNA levels of adhesion molecules E-selectin, vascular cell adhesion molecule 1 (VCAM-1), and intercellular cell adhesion molecule 1 (ICAM-1), and CD45. Exposure to HS + R did not result in different expression responses of these molecules between organs from Tie2^+/− or Tie2^+/+ mice and sham-operated mice. In contrast, the LPS-induced mRNA expression levels of E-selectin, VCAM-1, and ICAM-1, and CD45 in organs were attenuated in Tie2^+/− mice when compared with Tie2^+/+ mice in kidney and liver, but not in the other organs studied. Furthermore, reduced expression of E-selectin and VCAM-1 protein, and reduced influx of CD45⁺ cells upon LPS exposure, was visible in a microvascular bed-specific pattern in kidney and liver of Tie2^+/− mice compared with controls. In contrast to the hypothesis that a disbalance in the Ang/Tie2 system leads to increased microvascular inflammation, heterozygous deletion of Tie2 is associated with an organ-restricted, microvascular bed-specific attenuation of endothelial inflammatory response to LPS.

Temporal Dysregulation of the Angiopoietin-2/-1 Ratio After Trauma and Associations With Injury Characteristics and Outcomes

Traumatic injury and hemorrhagic shock result in endothelial cell activation and vascular dysfunction that, if not corrected, can propagate multiorgan failure. Angiopoietin-1 and angiopoietin-2 are important regulators of endothelial cell function, and the ratio of plasma angiopoietin-2-to-1 is a useful indicator of overall vascular health. We therefore characterized plasma angiopoietin-2/-1 ratios over time after trauma in adults in an effort to gain insight into the pathophysiology that may drive post-traumatic vasculopathy and organ injury. We performed a single-center prospective observational study to measure plasma angiopoietin-1 and -2 levels and determine angiopoietin-2/-1 ratios in adult trauma patients upon hospital arrival and after 12, 24, and 48 h. Compared with levels in healthy adults, angiopoietin-1 levels were significantly elevated at hospital arrival, and angiopoietin-2 levels were significantly elevated at 12, 24, and 48 h. These kinetics translated in angiopoietin-2/-1 ratios that were significantly greater than controls at 24 and 48 h. After regression analysis, elevated angiopoietin-2 levels were independently associated with blunt injuries at admission, with coagulopathy at admission and 12 h, and with hemorrhagic shock at 24 and 48 h. Significant correlations were observed between both angiopoietins and 24-h transfusion requirements. Angiopoietin-2/-1 ratios correlated with mechanical ventilation duration and intensive care unit and hospital lengths of stay. In this study, we demonstrate novel temporal associations between angiopoietin dysregulation and blunt injuries, acute coagulopathy, and hemorrhagic shock. Moreover, our findings highlight the presence of endothelial activation following traumatic insults in adults that may contribute to worse clinical outcomes.

Angiopoietins, Vascular Endothelial Growth Factors and Secretory Phospholipase A2 in Ischemic and Non-Ischemic Heart Failure

Heart failure (HF) is a growing public health burden, with high prevalence and mortality rates. In contrast to ischemic heart failure (IHF), the diagnosis of non-ischemic heart failure (NIHF) is established in the absence of coronary artery disease. Angiopoietins (ANGPTs), vascular endothelial growth factors (VEGFs) and secretory phospholipases A₂ (sPLA₂s) are proinflammatory mediators and key regulators of endothelial cells. In the present manuscript, we analyze the plasma concentrations of angiogenic (ANGPT1, ANGPT2, VEGF-A) and lymphangiogenic (VEGF-C, VEGF-D) factors and the plasma activity of sPLA₂ in patients with IHF and NIHF compared to healthy controls. The concentrations of ANGPT1, ANGPT2 and their ratio significantly differed between HF patients and healthy controls. Similarly, plasma levels of VEGF-D and sPLA₂ activity were higher in HF as compared to controls. Concentrations of ANGPT2 and the ANGPT2/ANGPT1 ratio (an index of vascular permeability) were increased in NIHF patients. VEGF-A and VEGF-C concentrations did not differ among the three examined groups. Interestingly, VEGF-D was selectively increased in IFH patients compared to controls. Plasma activity of sPLA₂ was increased in IHF and NIHF patients compared to controls. Our results indicate that several regulators of vascular permeability and smoldering inflammation are specifically altered in IHF and NIHF patients. Studies involving larger cohorts of these patients will be necessary to demonstrate the clinical implications of our findings.

Genetic variability of ANG2-35G>C gene as a predictor factor in sepsis

To date it is unknown if there is a predisposition to sepsis. In this respect, genetic studies have been conducted with the aim to find gene variants which can point out a higher predisposition to developing sepsis. The primary objective of this study is to highlight whether the genetic polymorphism of Angiopoietin-2 gene (ANG2-35G>C) is present mainly in septic patients. As secondary objectives we aimed to evaluate if there are any associations between ANG2-35G>C polymorphism and the severity scores Acute Physiology and Chronic Health Evaluation II (APACHE II) and Simplified Acute Physiology Score (SAPS) as well as routine tests in septic patients such as C reactive protein (CRP), procalcitonin (PCT). We enrolled adult patients admitted to the Intensive Care Unit (ICU). After admission to the ICU and the diagnosis of sepsis, blood samples were collected and the severity scores: APACHE II, SAPS were calculated on the first day of ICU admission. We recorded the following from the blood samples: CRP, PCT, angiopoietine2 (Ang-2). We performed several one-way ANOVA tests to determine any significant mean difference of the analyzed variables. We observed that variant genotypes of ANG2-35G>C gene polymorphism are significantly related to CRP, aspect which increases this biomarker credibility compared with others (i.e., PCT), in septic patients. ANG2-35G>C gene polymorphism is associated with severity scores, APACHE II, and SAPS in sepsis.

Endometriotic inflammatory microenvironment induced by macrophages can be targeted by niclosamide†

Endometriosis causes severe chronic pelvic pain and infertility. We have recently reported that niclosamide treatment reduces growth and progression of endometriosis-like lesions and inflammatory signaling (NF${\rm \small K}$B and STAT3) in a mouse model. In the present study, we examined further inhibitory mechanisms by which niclosamide affects endometriotic lesions using an endometriotic epithelial cell line, 12Z, and macrophages differentiated from a monocytic THP-1 cell line. Niclosamide dose dependently reduced 12Z viability, reduced STAT3 and NF${\rm \small K}$B activity, and increased both cleaved caspase-3 and cleaved PARP. To model the inflammatory microenvironment in endometriotic lesions, we exposed 12Z cells to macrophage conditioned media (CM). Macrophages were differentiated from THP-1 cells using 12-O-tetradecanoylphorbol-13-acetate as M0, and then M0 macrophages were polarized into M1 or M2 using LPS/IFNγ or IL4/IL13, respectively. Conditioned media from M0, M1, or M2 cultures increased 12Z viability. This effect was blocked by niclosamide, and cell viability returned to that of CM from cells treated with niclosamide alone. To assess proteins targeted by niclosamide in 12Z cells, CM from 12Z cells cultured with M0, M1, or M2 with/without niclosamide were analyzed by cytokine/chemokine protein array kits. Conditioned media from M0, M1, and/or M2 stimulated the secretion of cytokines/chemokines from 12Z cells. Production of most of these secreted cytokines/chemokines in 12Z cells was inhibited by niclosamide. Knockdown of each gene in 12Z cells using siRNA resulted in reduced cell viability. These results indicate that niclosamide can inhibit the inflammatory factors in endometriotic epithelial cells stimulated by macrophages by targeting STAT3 and/or NF${\rm \small K}$B signaling.

Association between serum angiopoietin-2 concentrations and periprocedural myocardial injury in patients undergoing elective percutaneous coronary intervention

Angiopoietin-2 (Ang-2) is a proangiogenic factor that mediates inflammation and atherosclerosis. We evaluated the predictive value of circulating Ang-2 levels for periprocedural myocardial injury (PMI) in 145 patients undergoing elective percutaneous coronary intervention (PCI), and investigated whether post-PCI Ang-2 levels are influenced by PMI. PMI was defined as a post-procedural troponin elevation above the 5×99^th percentile upper reference limit. Blood samples for Ang-2 analysis were collected at admission and on postoperative days 1 and 3. PMI occurred in 40 patients (28%). At baseline, there was no difference in Ang-2 levels between PMI and non-PMI patients (P=0.554). However, a significant interaction effect between PMI occurrence and time on Ang-2 levels was observed (interaction P=0.036). Although serum Ang-2 levels in non-PMI patients gradually decreased, Ang-2 levels in PMI patients did not change between different time-points. Multiple logistic regression analysis revealed that age, total stent length, and serum levels of N-terminal pro-brain natriuretic peptide were independent PMI predictors. These findings indicate that pre-procedural Ang-2 levels do not impact PMI occurrence after elective PCI. However, changes in Ang-2 levels after the procedure are closely related to PMI.

Early Heterogenic Response of Renal Microvasculature to Hemorrhagic Shock/Resuscitation and the Influence of NF-κB Pathway Blockade

Supplemental Digital Content is available in the text

Hemorrhagic shock (HS) is associated with low blood pressure due to excessive loss of circulating blood and causes both macrocirculatory and microcirculatory dysfunction. Fluid resuscitation after HS is used in the clinic to restore tissue perfusion. The persistent microcirculatory damage caused by HS and/or resuscitation can result in multiple organ damage, with the kidney being one of the involved organs. The kidney microvasculature consists of different segments that possess a remarkable heterogeneity in functional properties. The aim of this study was to investigate the inflammatory responses of these different renal microvascular segments, i.e., arterioles, glomeruli, and postcapillary venules, to HS and resuscitation (HS/R) in mice and to explore the effects of intervention with a nuclear factor-kappa B (NF-κB) inhibitor on these responses. We found that HS/R disturbed the balance of the angiopoietin-Tie2 ligand-receptor system, especially in the glomeruli. Furthermore, endothelial adhesion molecules, proinflammatory cytokines, and chemokines were markedly upregulated by HS/R, with the strongest responses occurring in the glomerular and postcapillary venous segments. Blockade of NF-κB signaling during the resuscitation period only slightly inhibited HS/R-induced inflammatory activation, possibly because NF-κB p65 nuclear translocation already occurred during the HS period. In summary, although all three renal microvascular segments were activated upon HS/R, responses of endothelial cells in glomeruli and postcapillary venules to HS/R, as well as to NF-κB inhibition were stronger than those in arterioles. NF-κB inhibition during the resuscitation phase does not effectively counteract NF-κB p65 nuclear translocation initiating inflammatory gene transcription.

Pathogenic functions and diagnostic utility of cytokines/chemokines in EHEC-HUS

Hemolytic - uremic syndrome (HUS) is a severe complication of infection by Shiga toxin (STx)-producing enterohemorrhagic Escherichia coli. Hemolytic - uremic syndrome is defined clinically as a triad of non-immune microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injuries. Neurologic complications such as acute encephalopathy are also observed. In humans, endothelial cells, proximal tubular epithelial cells, mesangial cells, podocytes, intestinal epithelial cells, and monocytes / macrophages are susceptible to STx-mediated injury. Shiga toxin induces the secretion of inflammatory cytokines and chemokines from susceptible cells, including tumor necrosis factor-α interleukin (IL)-1, IL-6, and IL-8. These cytokines and chemokines contribute to the pathogenesis of HUS and encephalopathy by enhancing STx-induced cytotoxicity and inducing inflammatory cell infiltration. Serum cytokine/chemokine levels are therefore useful as indicators of disease activity and predictors of progression from acute kidney injury to chronic kidney disease. Anti-inflammation therapy combined with apheresis to remove excessive cytokines / chemokines and methylprednisolone pulse therapy to suppress cytokine/chemokine production may be an effective treatment regimen for severe E. coli-associated HUS. However, this regimen requires careful monitoring of potential side effects, such as infections, thrombus formation, and hypertension.

Identification of putative biomarkers for Infantile Hemangiomas and Propranolol treatment via data integration

Infantile hemangiomas (IHs) are the most common benign tumors in early childhood. They show a distinctive mechanism of tumor growth in which a rapid proliferative phase is followed by a regression phase (involution). Propranolol is an approved treatment for IHs, but its mechanism of action remains unclear. We integrated and harmonized microRNA and mRNA transcriptome data from newly generated microarray data on IHs with publicly available data on toxicological transcriptomics from propranolol exposure, and with microRNA data from IHs and propranolol exposure. We identified subsets of putative biomarkers for proliferation and involution as well as a small set of putative biomarkers for propranolol's mechanism of action for IHs, namely EPAS1, LASP1, SLC25A23, MYO1B, and ALDH1A1. Based on our integrative data approach and confirmatory experiments, we concluded that hypoxia in IHs is regulated by EPAS1 (HIF-2α) instead of HIF-1α, and also that propranolol-induced apoptosis in endothelial cells may occur via mitochondrial stress.

EphA4/Tie2 crosstalk regulates leptomeningeal collateral remodeling following ischemic stroke

Leptomeningeal anastomoses or pial collateral vessels play a critical role in cerebral blood flow (CBF) restoration following ischemic stroke. The magnitude of this adaptive response is postulated to be controlled by the endothelium, although the underlying molecular mechanisms remain under investigation. Here we demonstrated that endothelial genetic deletion, using EphA4fl/fl/Tie2-Cre and EphA4fl/fl/VeCahderin-CreERT2 mice and vessel painting strategies, implicated EphA4 receptor tyrosine kinase as a major suppressor of pial collateral remodeling, CBF, and functional recovery following permanent middle cerebral artery occlusion. Pial collateral remodeling is limited by the crosstalk between EphA4-Tie2 signaling in vascular endothelial cells, which is mediated through p-Akt regulation. Furthermore, peptide inhibition of EphA4 resulted in acceleration of the pial arteriogenic response. Our findings demonstrate that EphA4 is a negative regulator of Tie2 receptor signaling, which limits pial collateral arteriogenesis following cerebrovascular occlusion. Therapeutic targeting of EphA4 and/or Tie2 represents an attractive new strategy for improving collateral function, neural tissue health, and functional recovery following ischemic stroke.

2,7-Dibromocarbazole interferes with tube formation in HUVECs by altering Ang2 promoter DNA methylation status

2,7-Dibromocarbazole (2,7-DBCZ) is one of the most frequently detected polyhalogenated carbazoles (PHCZs) in the environmental media. 2,7-DBCZ has attracted public attention for its potential for dioxin-like toxicity and cardiovascular toxicity. However, researches on the potential mechanism of angiogenesis inhibition by 2,7-DBCZ is still insufficient. Herein, human umbilical vein endothelial cells (HUVECs) were applied to explore the angiogenic effect of 2,7-DBCZ and the potential underlying mechanisms. 2,7-DBCZ significantly inhibited tube formation in HUVECs in the non-toxic concentration range. PCR array showed that 2,7-DBCZ reduced the expression proportion between VEGFs and Ang2, thereby inhibiting tube formation in HUVECs. Then, small RNA interference and DNA methylation assays were adopted to explore the potential mechanisms. It has been found that angiopoietin2 (Ang2)-silencing recovered the tube formation inhibited by 2,7-DBCZ. The DNA methylation status of Ang2 promoter also showed a demethylation tendency after exposure. In conclusion, 2,7-DBCZ could demethylate the Ang2 promoter to potentiate Ang2 expression, thus altering angiogenic phenotype of HUVECs by reducing the proportion between Ang2 and VEGFs. The data presented here can help to guide safety measures on the use of dioxin-like PHCZs for their potential adverse effects and provide a method for identifying the relevant biomarkers to assess their cardiovascular toxicity.

Brief Report: Higher Levels of Angiopoietin-1 Are Associated With Early and Sustained Viral Suppression in Children Living With Vertically Acquired HIV

BACKGROUND

Systemic inflammation, platelet dysfunction, and endothelial activation persist in people living with HIV despite sustained virologic suppression (SVS) with combined antiretroviral therapy (cART) and may lead to complications such as atherosclerosis and cardiovascular disease. Angiopoietin-1 (Ang-1) is a key regulator of angiogenesis and endothelial activation and has been studied as an objective biomarker in disease states such as atherosclerosis, sepsis, and severe malaria.

SETTING

Eight pediatric HIV care centers across Canada.

METHODS

Cross-sectional study of 61 children living with vertically acquired HIV on cART with undetectable RNA viral load. Plasma levels of Ang-1 were measured by ELISA and analyzed in relation to clinical characteristics abstracted from medical records.

RESULTS

Ang-1 levels were directly correlated with clinical indices of virologic control: cumulative proportion of life on effective cART (ρ = +0.35, P = 0.0078) and cumulative proportion of life with SVS (ρ = +0.36, P = 0.0049). Furthermore, higher Ang-1 levels were associated with younger age at SVS (ρ = -0.56, P < 0.0001). These associations remained statistically significant in multivariable linear regression models adjusting for potential confounders (P < 0.05 for all associations).

CONCLUSIONS

Early effective cART and SVS were associated with higher Ang-1 levels in children living with vertically acquired HIV-1.

Release of endothelial activation markers in lungs of patients with malaria-associated acute respiratory distress syndrome

Background

Malaria-associated acute respiratory distress syndrome (MA-ARDS) is an understudied complication of malaria and is characterized by pulmonary inflammation and disruption of the alveolar-capillary membrane. Its pathogenesis remains poorly understood. Since endothelial activation plays an important role in other malarial complications, the expression of two endothelial activation markers, von Willebrand factor (VWF) and angiopoietin-2 (ANG-2), was investigated in the lungs of patients with MA-ARDS.

Methods

Post-mortem lung sections of Plasmodium falciparum-infected patients without alveolar oedema (NA), P. falciparum-infected patients with alveolar oedema (MA-ARDS), and uninfected people who died accidentally with no pathological changes to the lungs (CON) were immunohistochemically stained for VWF and ANG-2, and were evaluated with semi-quantitative analysis.

Results

Alveolar oedematous VWF and ANG-2 and intravascular VWF staining were significantly increased in patients with MA-ARDS versus infected and uninfected control groups. The levels of VWF in the alveolar septa and endothelial lining of large blood vessels of patients with MA-ARDS was significantly decreased compared to controls. ANG-2 expression was increased in the alveolar septa of malaria patients without alveolar oedema versus control patients, while ANG-2⁺ leukocytes were increased in the alveoli in both infected patient groups.

Conclusions

This study documents a high level of VWF and ANG-2, two endothelial activation markers in the oedematous alveoli of post-mortem lung sections of Thai patients with MA-ARDS. Decreased detection of VWF in the endothelial lining of blood vessels, in parallel with an increased presence of intravascular VWF staining suggests marked endothelial activation and Weibel–Palade body release in the lungs of patients with MA-ARDS.

Markers of endothelial cell activation in suspected late onset neonatal sepsis in Surinamese newborns: a pilot study

BACKGROUND

Serum levels of markers of endothelial cell activation are associated with bacteremia and mortality in sepsis in adults, children, and newborns with early onset sepsis. We hypothesize that levels of these markers are associated with these outcomes in hospitalized newborns with suspected late onset neonatal sepsis (LONS).

METHODS

In this prospective cohort study, newborns admitted to the tertiary neonatal care facility of Suriname were included upon clinical suspicion of LONS and before start of antibiotic treatment, between April 1, 2015 and May 31, 2016. Serum concentrations of angiopoietin-1, angiopoietin-2, and soluble isoforms of P-selectin, E-selectin, vascular cell adhesion molecule-1 (sVCAM-1), intercellular adhesion molecule-1 (sICAM-1), platelet and endothelial cell adhesion molecule-1 (sPECAM-1), matrix metalloproteinase-9 (MMP-9), neutrophil elastase, and tissue-inhibitor of metalloproteinases-1 (TIMP-1) were measured.

RESULTS

Twenty-thee newborns were included. Baseline characteristics were similar between newborns with and without bacteremia and between non-survivors and survivors. Only soluble E-selectin (sE-selectin) was higher in newborns with bacteremia versus non-bacteremia (P=0.04) and lower in non-survivors (P=0.04). No conclusions could be made for sVCAM-1 due to high serum concentrations.

CONCLUSIONS

In conclusion, the data from this pilot study indicate that serum levels of markers of endothelial cell activation are poorly associated with bacteremia and mortality.