Role Of Ang-2 Research Articles

MiR-221-3p targets Ang-2 to inhibit the transformation of HCMECs to tip cells.

Postembryonic angiogenesis is mainly induced by various proangiogenic factors derived from the original vascular network. Previous studies have shown that the role of Ang-2 in angiogenesis is controversial. Tip cells play a vanguard role in angiogenesis and exhibit a transdifferentiated phenotype under the action of angiogenic factors. However, whether Ang-2 promotes the transformation of endothelial cells to tip cells remains unknown. Our study found that miR-221-3p was highly expressed in HCMECs cultured for 4 h under hypoxic conditions (1% O2 ). Moreover, miR-221-3p overexpression inhibited HCMECs proliferation and tube formation, which may play an important role in hypoxia-induced angiogenesis. By target gene prediction, we further demonstrated that Ang-2 was a downstream target of miR-221-3p and miR-221-3p overexpression inhibited Ang-2 expression in HCMECs under hypoxic conditions. Subsequently, qRT-PCR and western blotting methods were performed to analyse the role of miR-221-3p and Ang-2 on the regulation of tip cell marker genes. MiR-221-3p overexpression inhibited CD34, IGF1R, IGF-2 and VEGFR2 proteins expression while Ang-2 overexpression induced CD34, IGF1R, IGF-2 and VEGFR2 expression in HCMECs under hypoxic conditions. In addition, we further confirmed that Ang-2 played a dominant role in miR-221-3p inhibitors promoting the transformation of HCMECs to tip cells by using Ang-2 shRNA to interfere with miR-221-3p inhibitor-treated HCMECs under hypoxic conditions. Finally, we found that miR-221-3p expression was significantly elevated in both serum and myocardial tissue of AMI rats. Hence, our data showed that miR-221-3p may inhibit angiogenesis after acute myocardial infarction by targeting Ang-2 to inhibit the transformation of HCMECs to tip cells.

Ang1 and Ang4 differentially affect colitis and carcinogenesis in an AOM-DSS mouse model.

Angiogenin-1 (Ang1) and angiogenin-4 (Ang4) are 14-kDa ribonucleases with potent angiogenic and antimicrobial properties. The role of Ang1 and Ang4 in chronic colitis and colitis-associated cancer has not been previously studied. Wild-type (WT) and angiogenin-1 knock-out (Ang1-KO) C57BL/6 mice were given azoxymethane, a colon carcinogen, 2 days in advance of three cycles of 3.5% dextran sodium sulfate (DSS). Disease activity index (DAI) was recorded, a colonoscopy was performed after each DSS treatment, and mice were euthanized (colitis, recovery, cancer) with tissue evaluated by histopathology. Ang1, Ang4, TNF-α, Il-1F062, IL-6, IL-10, IL-23, IL-33 mRNA levels were analyzed by RT-PCR. Ang1-KO mice exhibited more severe colitis compared to WT mice during both the acute (P<0.05) and recovery (P<0.05) phases of each DSS cycle. Consistent with these results, colonic TNF-α, IL1-β, IL-6, IL-10, and IL-33 mRNA levels were significantly upregulated in Ang1-KO mice (P<0.05). While Ang4 increased to similar levels in both WT and Ang1-KO mice during colitis and recovery phases, WT mice were distinguished by a significant upregulation of Ang1. Interestingly, despite the reduced colitis, WT mice developed significantly more tumors compared to Ang1-KO mice (P<0.05). 134 tumors formed in WT mice (4.6 tumors/mouse) while only 46 tumors formed (1.5 tumors/mice) in Ang1-KO mice, which were also characterized by a 34-fold decrease in Ang4 compared to WT mice and the complete absence of Ang1. In a mouse model of colitis-associated cancer, Ang1-KO mice develop more severe colitis, but fewer tumors compared to WT mice. Ang1 levels correlate with the severity of colitis and the development of colitis-associated cancer, while Ang4 was upregulated during both colitis and cancer. Ang1 and Ang4 play important regulatory roles in the response to chronic colitis and the development of colitis-associated cancer and may serve as novel therapeutic targets.

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.

Identification of proteins associated with clinical and pathological features of proliferative diabetic retinopathy in vitreous and fibrovascular membranes.

PurposeTo identify the protein profiles in vitreous associated with retinal fibrosis, angiogenesis, and neurite formation in epiretinal fibrovascular membranes (FVMs) in patients with proliferative diabetic retinopathy (PDR).MethodsVitreous samples of 5 non-diabetic control patients with vitreous debris and 7 patients with PDR membranes were screened for 507 preselected proteins using the semi-quantitative RayBio® L-series 507 antibody array. From this array, 60 proteins were selected for a custom quantitative antibody array (Raybiotech, Human Quantibody® array), analyzing 7 control patients, 8 PDR patients with FVMs, and 5 PDR patients without FVMs. Additionally, mRNA levels of proteins of interest were measured in 10 PDR membranes and 11 idiopathic membranes and in retinal tissues and cells to identify possible sources of protein production.ResultsOf the 507 proteins screened, 21 were found to be significantly elevated in PDR patients, including neurogenic and angiogenic factors such as neuregulin 1 (NRG1), nerve growth factor receptor (NGFR), placental growth factor (PlGF) and platelet derived growth factor (PDGF). Angiopoietin-2 (Ang2) concentrations were strongly correlated to the degree of fibrosis and the presence of FVMs in patients with PDR. Protein correlation analysis showed PDGF to be extensively co-regulated with other proteins, including thrombospondin-1 and Ang2. mRNA levels of glial-derived and brain/derived neurotrophic factor (GDNF and BDNF) were elevated in PDR membranes. These results were validated in a second study of 52 vitreous samples of 32 PDR patients and 20 control patients.ConclusionsThis exploratory study reveals protein networks that potentially contribute to neurite outgrowth, angiogenesis and fibrosis in the formation of fibrovascular membranes in PDR. We identified a possible role of Ang2 in fibrosis and the formation of FVMs, and of the neurotrophic factors NRG1, PDGF and GDNF in neurite growth that occurs in all FVMs in PDR.

Abstract 1825: Angiopoietin-Tie-2 functional axis in colorectal cancer liver metastasis (CRCLM) provides a new marker for stratification and evaluation of tumor progression

Abstract Colorectal cancer (CRC) is the third leading cause of cancer in Canadians, with liver metastases being the major cause of death from this disease. Tumors induce angiogenesis, a phenomenon known as the ‘angiogenic switch’, which is an essential step in tumor progression whereby the balance of pro- and anti-angiogenic factors are important for active angiogenesis. Clinical efficacy of targeted VEGF (anti-angiogenic) treatment has been validated as a cancer therapy. Our group, together with others, has identified unique histological growth patterns HGPs (desmoplastic, replacement and pushing) within liver metastases that have different responses to anti-angiogenic therapy. The patients with Desmoplastic HGP (DHGP) that received anti-angiogenic plus chemotherapy prior to resection had a significantly better pathologic response and survival than patients with Replacement HGP (RHGP). The aim of this study was to explore the role of Ang-1, Ang-2, Tie-2 and VEGF in the development and progression of CRCLM tumors with distinct HGPs. Here, human CRCLM tumor samples were analyzed by quantitative real-time PCR (Q-PCR) and immunohistochemistry (IHC) staining. The Q-PCR results demonstrated that the expression of Ang-2 was lower in RHGP tumor samples compared with DHGP tumor samples. This data was validated by IHC, were IHC scoring results showed that the ratio of Ang-2: Ang-1 expression in DHGP tumors was higher compared to RHGP tumors. VEGF and Tie2 proteins were expressed in both tumor patterns. Thus vascular quiescence maintained by constitutive Ang-1/Tie-2 signaling, found in RHGP tumors, prevails over destabilization and pro-inflammatory Ang-2/Tie-2 signaling, which is higher in the DHGP tumor samples. Since vascular remodelling is driven by Ang-2/Tie-2 in DHGP, which is dependent on VEGF we would expect anti-angiogenic therapy to be effective on DHGP. Furthermore, the RHGP had low levels of Ang-2 and high levels of Ang-1, together with the presence of Tie-2, and then one would predict that VEGF is not required for the growth of these tumors and thus would not respond to anti-angiogenic therapy, as has been shown in our patients’ cohort. Taken together, these data suggest that the Angiopoietin/Tie-2 functional axis is an important player in CRCLM tumor progression and can be a potential target for CRCLM cancer therapy with stratification of patients by HGPs. Citation Format: Nisreen S. Ibrahim. Angiopoietin-Tie-2 functional axis in colorectal cancer liver metastasis (CRCLM) provides a new marker for stratification and evaluation of tumor progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1825. doi:10.1158/1538-7445.AM2017-1825

Angiopoietin 2 in placentation and tumor biology: The yin and yang of vascular biology

There are several parallels between placental and tumor biology. Both require rapid acquisition of a blood supply to supply oxygen and nutrients, the placenta through neoangiogenesis and tumors by co-opting the existing vasculature. In addition, successful pregnancy also requires remodeling of the maternal uterine spiral arteries. Angiopoietins (Angs) are a family of angiogenic growth factors, the best studied being Ang-1 and Ang-2, which signal through the membrane tyrosine kinase receptor Tie2, and in simple terms have opposite effects with Ang-1 acting to stabilize newly formed blood vessels and Ang-2 having a destabilizing effect. The roles of Ang-1, and in particular Ang-2 in placental and tumor biology are discussed in this review.

Reverse kinetics of angiopoietin-2 and endotoxins in acute pyelonephritis: Implications for anti-inflammatory treatment?

Based on former studies showing an antagonism between angiopoietin-2 (Ang-2) and bacterial endotoxins (LPS), we investigated the role of Ang-2 as immunomodulatory treatment. At first, kinetics of circulating LPS in Gram-negative pyelonephritis developing after urinary obstruction was studied. Serum LPS, interleukin (IL)-6 and Ang-2 were measured in 25 patients with acute pyelonephritis and sepsis before and after removal of the obstruction performed either with insertion of a pigtail catheter (n=12) or percutaneous drainage (n=13). At a second stage, Ang-2 was given as anti-inflammatory treatment in 40 rabbits one hour after induction of acute pyelonephritis by ligation of the ureter at the level of pelvo-ureteral junction and upstream bacterial inoculation. Survival was recorded; blood mononuclear cells were isolated and stimulated for the production of tumour necrosis factor-alpha (TNFα). The decrease in circulating LPS was significantly greater among patients undergoing drainage than pigtail insertion. This was accompanied by reciprocal changes of Ang-2 and IL-6. Treatment with Ang-2 prolonged survival from Escherichia coli pyelonephritis despite high levels of circulating LPS. When Ang-2 was given as treatment of Pseudomonas aeruginosa pyelonephritis, sepsis-induced decrease of TNFα production by circulating mononuclear cells was reversed without an effect on tissue bacterial overgrowth. It is concluded that Ang-2 and LPS follow reverse kinetics in acute pyelonephritis. When given as experimental treatment, Ang-2 prolongs survival through an effect on mononuclear cells.

Angiopoietin-1 blocks neurotoxic zinc entry into cortical cells via PIP2 hydrolysis-mediated ion channel inhibition

Excessive entry of zinc ions into the soma of neurons and glial cells results in extensive oxidative stress and necrosis of cortical cells, which underlies acute neuronal injury in cerebral ischemia and epileptic seizures. Here, we show that angiopoietin-1 (Ang1), a potent angiogenic ligand for the receptor tyrosine kinase Tie2 and integrins, inhibits the entry of zinc into primary mouse cortical cells and exerts a substantial protective effect against zinc-induced neurotoxicity. The neuroprotective effect of Ang1 was mediated by the integrin/focal adhesion kinase (FAK) signaling axis, as evidenced by the blocking effects of a pan-integrin inhibitory RGD peptide and PF-573228, a specific chemical inhibitor of FAK. Notably, blockade of zinc-permeable ion channels by Ang1 was attributable to phospholipase C-mediated hydrolysis of phosphatidylinositol 4,5-bisphosphate. Collectively, these data reveal a novel role of Ang1 in regulating the activity of zinc-permeable ion channels, and thereby protecting cortical cells against zinc-induced neurotoxicity.

ME-05 * COUNTERATTACKING THE FORCE BEHIND GLIOMA INVASION

Brain tumor dispersal is the major cause behind the extreme difficulty of treatment and the inevitable recurrence of malignant gliomas. Determining the mechanism underlying the invasion of brain tumor cells will suggest rational therapeutic strategies. Importantly, acquisition of a highly aggressive invasive phenotype is being observed in patients with recurrent malignant gliomas treated with antiangiogenesis therapy and is considered to be responsible for the therapy failure. Although the cause for this tumor behavior remains elusive, it has been hypothesized that the tumor microenvironment may be one major influence in the invasive development. In this regard, we have recently described the recruitment of Tie2-expressing monocytes (TEMs) into the tumor/normal brain interface upon anti-VEGF therapies in preclinical models and in human surgical specimens, and reported that this specific myeloid population is responsible for the heightened invasive properties of brain tumor stem cells. Here we investigated changes in the cytokine milieu of these tumors and identified increased expression of Angiopoietin 2 (Ang2), a Tie2 ligand, after therapies targeting either VEGF (bevacizumab, aflibercept) or VEGFR (DC101), but no after standard chemotherapy. In vitro and in vivo models were combined to decipher the role of Ang2, and we observed that expression of Ang2 functioned as a potent chemoattractant of TEMs. Moreover, we observed that Ang2 stimulates the tissue remodeling properties of TEMs, further enhancing the pro-invasive properties of this tumor recruited population. Of interest, modulation of molecules blocking the Ang/Tie2 axes in a preclinical model jeopardizes the tumor recruitment of TEMs and drastically resulted in a complete abolition of the heightened invasion induced by antiangiogenesis therapy. These results might have important implications in the clinical scenario since decrease of the invasive tumor pattern could potentially render recurrent tumors amenable to surgical removal ultimately prolonging the survival of patients with malignant gliomas.

Abstract 33: In vitro functional study of Ang 2 in colorectal cancer cell line and the significance of Ang 2 expression in colorectal cancer patients

Abstract Objectives: Angiopoietin 2 (Ang-2) is an important regulator of angiogenesis, blood vessel maturation and integrity of the vascular endothelium. The correlation between the dynamic expression of Ang-2 in tumors with regions of high angiogenic activity and a poor prognosis in many tumor types makes Ang-2 an ideal drug target. The function and mechanism of Angiopoietin 2 in colorectal cancer proliferation, invasion, metastasis and angiogenesis have not been fully elucidated to date. The aim of present study was to evaluate the biological roles of Ang-2 in the colorectal cancer cell line and to correlate the Ang-2 overexpression with the clinicopathological factors of colorectal cancers. Methods: The biological roles of Ang-2 were investigated in LoVo colorectal cancer cell line that expresses high level of Ang-2 by knockdown Ang-2 with shRNA transfection. The functional roles of Ang-2 were evaluated by invasion assay, wound healing cell migration assay, MTT assay and tube formation assay. Moreover, Ang-2 expression was investigated by immunohistochemistry on tissue microarrays of 415 cases of colorectal cancer and the association of Ang-2 expression was examined with clinicopathologic features. Results: The LoVo cell line knockdowned Ang-2 by shRNA revealed significant decreases of viability, invasion, migration and tube formation compared to that of control (p&amp;lt;0.005) respectively. The Ang-2 was overexpressed in 45.8% of colorectal cancers. The overexpression of Ang-2 was significantly associated with pT (p=0.048), pN (p&amp;lt;0.001), vascular invasions (p-=0.023), lymphatic invasions (p&amp;lt;0.001) and TNM stages (p=0.022). Multivariate Cox regression analysis showed that the overexpression of Ang-2 in pN stage 1 and 2 were an independent prognostic factor of decreased survival [pN stage 1, HR=5.17 (95% CI: 6.36-19.59, p=0.016); pN stage 2, HR=7.01 (95% CI: 1.76-27.96, p=0.006)]. The overall survival was significantly decreased in patients of Ang-2 high expression [HR=6.78 (95% CI: 4.16-11.05, p&amp;lt;0.001)]. The cumulative survival was significantly decreased in patients of Ang-2 high expression compared to those of Ang-2 low expression by Kaplan-Meier analysis (log rank test, p&amp;lt;0.001). Conclusion: The overexpression of Ang-2 is significantly associated with tumor progression rather than carcinogenesis in colorectal cancer. It can be a valuable poor prognostic marker of colorectal cancer and the Ang-2 can be used in therapeutic strategies. Citation Format: Moo Jun Baek, Dongjun Jeong, Chang-Jin Kim, Tae Hyun Kim, Han Jo Kim, Tae Sung Ahn, Sang Byung Bae, Sang Han Lee. In vitro functional study of Ang 2 in colorectal cancer cell line and the significance of Ang 2 expression in colorectal cancer patients. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 33. doi:10.1158/1538-7445.AM2014-33

The angiopoietin1–Akt pathway regulates barrier function of the cultured spinal cord microvascular endothelial cells through Eps8

In mammalian central nervous system (CNS), the integrity of the blood–spinal cord barrier (BSCB), formed by tight junctions (TJs) between adjacent microvascular endothelial cells near the basement membrane of capillaries and the accessory structures, is important for relatively independent activities of the cellular constituents inside the spinal cord. The barrier function of the BSCB are tightly regulated and coordinated by a variety of physiological or pathological factors, similar with but not quite the same as its counterpart, the blood–brain barrier (BBB). Herein, angiopoietin 1 (Ang1), an identified ligand of the endothelium-specific tyrosine kinase receptor Tie-2, was verified to regulate barrier functions, including permeability, junction protein interactions and F-actin organization, in cultured spinal cord microvascular endothelial cells (SCMEC) of rat through the activity of Akt. Besides, these roles of Ang1 in the BSCB in vitro were found to be accompanied with an increasing expression of epidermal growth factor receptor pathway substrate 8 (Eps8), an F-actin bundling protein. Furthermore, the silencing of Eps8 by lentiviral shRNA resulted in an antagonistic effect vs. Ang1 on the endothelial barrier function of SCMEC. In summary, the Ang1–Akt pathway serves as a regulator in the barrier function modulation of SCMEC via the actin-binding protein Eps8.

Ectopic expression of human angiopoietin-1 promotes functional recovery and neurogenesis after focal cerebral ischemia

Neuropathologic processes such as cerebral ischemia can enhance neurogenesis. Angiopoietin-1 (Ang1) emerges as a critical regulator of physiological and pathological angiogenesis during embryonic and postnatal life. Although Ang1 could protect peripheral vasculature from vascular leakage following ischemic injury, the role of Ang1 in long-term neurological recovery after ischemic stroke remains elusive. This study aims to examine whether Ang1 overexpression via lentivirus-mediated gene transfer enhances neurovascular remodeling and improves functional outcome in a rat model of focal cerebral ischemia. Our results demonstrated that lentivirus-mediated Ang1 gene transfer led to improved neurological behavior and reduced infarction volume, and protected against blood–brain barrier (BBB) leakage in the ischemic rats. In addition, we revealed that these effects of Ang1 are related to the ability of Ang1 to increase vascular density and accelerate endogenous neuronal differentiation. These findings suggest that Ang1 is a promising agent for the treatment of cerebral ischemia.

Angiopoietin-1 regulates microvascular reactivity and protects the microcirculation during acute endothelial dysfunction: Role of eNOS and VE-cadherin

The growth factor angiopoietin-1 (Ang-1) plays an essential role in angiogenesis and vascular homeostasis. Nevertheless, the role of Ang-1 in regulating vascular tone and blood flow is largely unexplored. Endothelial nitric oxide synthase (eNOS) and the junctional protein VE-cadherin are part of the complex signalling cascade initiated by Ang-1 in endothelial cells. In this study, we aimed to investigate the mechanisms underlying acute effects of Ang-1 on microvascular reactivity, permeability and blood flow, and hypothesise that eNOS and VE-cadherin underpin Ang-1 mediated vascular effects that are independent of angiogenesis and proliferation.Myography of isolated microarterioles from male C3H/HeN mice (7–10 weeks) was employed to measure vascular reactivity in vitro. Microcirculatory function in vivo was evaluated by intravital microscopy and Doppler fluximetry in dorsal window chambers. Ang-1 and its stable variant MAT.Ang-1 induced a concentration-dependent vasodilation of arterioles in vitro, which was blocked with nitric oxide (NO) synthesis inhibitor l-NAME. In vivo, MAT.Ang-1 restored to control levels l-NAME induced peripheral vasoconstriction, decreased blood flow and microvascular hyperpermeability. Tissue protein expression of VE-cadherin was reduced by NOS inhibition and restored to control levels by MAT.Ang-1, whilst VE-cadherin phosphorylation was increased by l-NAME and subsequently reduced by MAT.Ang-1 administration. Moreover, MAT.Ang-1 alone did not modulate systemic levels of angiogenetic factors.Our novel findings report that Ang-1 induces arteriolar vasodilation via release of NO, suggesting that Ang-1 is an important regulator of microvascular tone. As MAT.Ang-1 ameliorates detrimental effects on the microcirculation induced by inhibition of NO synthesis and stabilizes the endothelial barrier function through VE-cadherin, we propose that this Ang-1 variant may serve as a novel therapeutic agent to protect the microcirculation against endothelial dysfunction.

Serum Levels of Angiopoietin-2, but not Angiopoietin-1, are Elevated in Patients with Erythrodermic Cutaneous T-cell Lymphoma

Angiogenesis is a crucial process in the growth and progression of cancer, correlating with the metastatic potential of tumour cells. Angiopoietins are ligands for the endothelium-specific tyrosine kinase Tie2 receptor, which comprise 4 structurally related proteins, termed angiopoietin (Ang)-1, Ang-2, Ang-3 and Ang-4. The roles of Ang-1 and Ang-2 have recently been clarified as crucial in angiogenesis. In this report, we measured serum Ang-1 and Ang-2 levels in patients with cutaneous T-cell lymphoma (CTCL). Serum levels of Ang-2, but not Ang-1, in patients with Sézary syndrome were significantly higher than those in patch mycosis fungoides (MF), plaque/tumour MF, and healthy controls. In patients with CTCL, serum Ang-2 correlated with disease activity. Moreover, the numbers of Ang-2+ cells in lesional skin of CTCL were significantly larger than those in normal skin. These results suggest that Ang-2 may have important roles in the development of CTCL.

Significance of serum levels of angiopoietin-2 and its relationship to Doppler ultrasonographic findings in rheumatoid arthritis patients

BackgroundAngiopoietin-2 (Ang-2) is connected to angiogenesis in synovial regions, but the significance of its levels in patients with rheumatoid arthritis (RA) is still unclear. Aim of the workTo evaluate the significance of serum levels of Ang-2 in patients with RA. Also, to determine Ang-2 relationship to the findings of joints Doppler ultrasonographic findings. Patients and methodsThis study included 40 patients with RA, and 25 matched healthy controls. All patients were subjected to assessment of pain using visual analogue scale (VAS), assessment of personal activity using the Health Assessment Questionnaire (HAQ) score, and calculation of disease activity score (DAS 28). Laboratory assays of complete blood count (CBC), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), rheumatoid factor (RF) titre, and measurement of serum levels of Ang-2 by ELISA. Doppler ultrasonography (US) assessment for eight joints, with calculation of synovial thickness and total signal score (TSS), was done. ResultsSerum Ang-2 levels were significantly higher among patients (3191.3±594.9pg/ml) than controls (1771.7±103.1pg/ml) (p<0.001). Serum Ang-2 levels were significantly correlated with ESR, CRP, DAS28, and duration of morning stiffness (p<0.001, p<0.001, p<0.001, and p=0.025, respectively). There was a significant correlation between serum Ang-2 levels and findings of US, regarding joint synovial thickness, and TSS (p<0.001, for both). ConclusionPatients with RA had significantly higher levels of serum Ang-2 versus controls. In those patients, serum Ang-2 levels were significantly correlated with disease activity markers (ESR, CRP), DAS28, and duration of morning stiffness. Moreover, these levels were significantly correlated with synovial thickness, and TSS. The role of Ang-2 in RA pathogenesis might open the door to the development of new therapeutic strategies, particularly which target angiogenesis.

THU0198 Serum angiopoietin-2 level strongly reflects the disease activity and renal function in ANCA-associated vasculitis

BackgroundAngiopoietin-2 (Ang-2) has emerged as a key mediator of endothelial cell activation. Ang-1 and Ang-2 are antagonistic ligands which bind with similar affinity to the extracellular domain of the tyrosine...

Source of angiopoietin-2 in the sera of women during pregnancy

Placental development requires coordinated angiogenesis regulated by multiple factors including angiopoietins. Previously we demonstrated that the concentration of angiopoietin-2 (Ang-2) in the sera of women rises markedly in pregnancy in early gestation. This increase is reduced in pregnancies subsequently complicated by intrauterine growth restriction (IUGR). We now show that the concentration of Ang-2, but not Ang-1, in maternal serum is increased during normal pregnancy, peaking at the end of the first trimester. We also demonstrate that a key source of the elevated Ang-2 levels during pregnancy is decidual endothelial cells (DECs) but not cytotrophoblasts. Secretion of Ang-2 by DECs relies on the release from intracellular stores and the synthesis of new Ang-2 protein and is regulated by serum factors at a translational level. Further studies on the role of Ang-2 during pregnancy are warranted as well as the evaluation of Ang-2 as a marker to predict adverse pregnancy outcomes.

Levels of angiopoietins 1 and 2 in induced sputum supernatant in patients with COPD

Pathological features of chronic obstructive pulmonary disease (COPD) include lung vascular remodeling and angiogenesis. Angiopoietin-1 (Ang-1), is an essential mediator of angiogenesis by establishing vascular integrity, whereas angiopoietin-2 (Ang-2) acts as its natural inhibitor. We determined the levels of angiopoietins in sputum supernatants of patients with COPD and investigated their possible association with mediators and cells involved in the inflammatory and remodeling process.Fifty-nine patients with COPD, 25 healthy smokers and 20 healthy non-smokers were studied. All subjects underwent lung function tests, sputum induction for cell count identification and Ang-1, Ang-2, VEGF, TGF-β1, MMP-2, LTB4, IL-8, albumin measurement in sputum supernatants. Airway vascular permeability (AVP) index was also assessed.Ang-2 levels were significantly higher in patients with COPD compared to healthy smokers and healthy non-smokers [median, interquartile ranges pg/ml, 267 (147–367) vs. 112 (67–171) and 98 (95–107), respectively; p<0.001]. Regression analysis showed a significant association between Ang-2 levels and AVP index, VEGF, IL-8 and MMP-2 levels in COPD, the strongest being with VEGF.Our results indicate that induced sputum Ang-2 levels are higher in COPD compared to healthy smokers and healthy non-smokers. Moreover, Ang-2 is associated with AVP, IL-8, MMP-2, and VEGF, indicating a possible role for Ang-2 in the pathogenesis of the disease.

Timing and expression of the Angiopoietin-1/Tie-2 pathway in murine lung development and congenital diaphragmatic hernia (CDH)

SUMMARYCongenital diaphragmatic hernia (CDH) is one of the most common congenital abnormalities. Children born with CDH suffer a number of co-morbidities, the most serious of which is respiratory insufficiency from a combination of alveolar hypoplasia and pulmonary vascular hypertension. All children born with CDH display some degree of pulmonary hypertension, the severity of which has been correlated with mortality. The molecular mechanisms responsible for the development of pulmonary hypertension in CDH remain poorly understood. Angiopoitein-1 (Ang-1), a central mediator in angiogenesis, participates in the vascular development of many tissues, including the lung. Although previous studies have demonstrated that Ang-1 might play an important role in the development of familial pulmonary hypertension, the role of Ang-1 in the development of the pulmonary hypertension associated with CDH is poorly understood. The aim of this study was to examine the role of the Ang-1 pathway in a murine model of CDH. Here, we report that Ang-1 appears important in normal murine lung development, and have established its tissue-level expression and localization patterns at key time-points. Additionally, our data from a nitrofen and bisdiamine-induced murine model of CDH suggests that altered expression patterns of Ang-1, its receptor Tie-2 and one of its transcription factors (epithelium-specific Ets transcription factor 1) might be responsible for development of the pulmonary vasculopathy seen in the setting of CDH.

Angiopoietin-2 promotes inflammatory lymphangiogenesis and its effect can be blocked by the specific inhibitor L1-10

Angiopoietin (Ang)-2, a ligand of the receptor tyrosine kinase Tie2, is known to be involved in the regulation of embryonic lymphangiogenesis. However, the role of Ang-2 in postnatal pathological lymphangiogenesis, such as inflammation, is largely unknown. We used a combination of imaging, molecular, and cellular approaches to investigate whether Ang-2 is involved in inflammatory lymphangiogenesis. We observed strong and continuous expression of Ang-2 on newly generated lymphatic vessels for 2 wk in sutured corneas of BALB/c mice. This expression was concurrent with an increased number of lymphatic vessels. TNF-α expression also increased, with peak TNF-α expression occurring before peak Ang-2 expression was reached. In vitro experiments showed that TNF-α stimulates Ang-2 and Tie2 and ICAM-1 expression on human lymphatic endothelial cells (LECs) and blood vascular endothelial cells (BECs). Ang-2 alone did not affect the biological behavior of LECs, whereas Ang-2 combined with TNF-α significantly promoted the proliferation of LECs but not BECs. In mouse models, blockade of Ang-2 with L1-10, an Ang-2-specific inhibitor, significantly inhibited lymphangiogenesis but promoted angiogenesis. These results clearly indicate that Ang-2 acts as a crucial regulator of inflammatory lymphangiogenesis by sensitizing the lymphatic vasculature to inflammatory stimuli, thereby directly promoting lymphangiogenesis. The involvement of Ang-2 in inflammatory lymphangiogenesis provides a strong rationale for the exploitation of anti-Ang-2 treatment in the prevention and treatment of tumor metastasis and transplant rejection.