Interpretable attention-based deep learning ensemble for personalized ovarian cancer treatment without manual annotations.

Inhibition of pathological angiogenesis has become one of the first FDA approved targeted therapies widely tested in anti-cancer treatment, i.e. VEGF-targeting monoclonal antibody bevacizumab, in combination with chemotherapy for frontline and maintenance therapy for women with newly diagnosed ovarian cancer. Identification of the best predictive biomarkers of bevacizumab response is necessary in order to select patients most likely to benefit from this therapy. Hence, this study investigates the protein expression patterns on immunohistochemical whole slide images of three angiogenesis related proteins, including Vascular endothelial growth factor, Angiopoietin 2 and Pyruvate kinase isoform M2, and develops an interpretable and annotation-free attention based deep learning ensemble framework to predict the bevacizumab therapeutic effect on patients with epithelial ovarian cancer or peritoneal serous papillary carcinoma using tissue microarrays (TMAs). In evaluation with five-fold cross validation, the proposed ensemble model using the protein expressions of both Pyruvate kinase isoform M2 and Angiopoietin 2 achieves a notably high F-score (0.99±0.02), accuracy (0.99±0.03), precision (0.99±0.02), recall (0.99±0.02) and AUC (1.00±0). Kaplan-Meier progression free survival analysis confirms that the proposed ensemble is able to identify patients in the predictive therapeutic sensitive group with low cancer recurrence (p<0.001), and the Cox proportional hazards model analysis further confirms the above statement (p=0.012). In conclusion, the experimental results demonstrate that the proposed ensemble model using the protein expressions of both Pyruvate kinase isoform M2 and Angiopoietin 2 can assist treatment planning of bevacizumab targeted therapy for patients with ovarian cancer.

Plasma Interleukin-6 (IL-6), Angiopoietin-2, and C-Reactive Protein Levels Predict Subsequent Type 1 Myocardial Infarction in Persons With Treated HIV Infection.

BACKGROUND: HIV infection leads to endothelial activation, promoting platelet adhesion, and accelerating atherosclerosis. Our goal was to determine whether biomarkers of endothelial activation and hemostasis/thrombosis were elevated in people with treated HIV (PWH) before myocardial infarction (MI). METHODS: In a case-control study nested within the CFAR Network of Integrated Clinical Systems (CNICS) cohort, we compared 69 adjudicated cases with type 1 MI with 138 controls matched for antiretroviral therapy regimen. We measured angiopoietin-1, angiopoietin-2 (ANG-2), intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13), von Willebrand factor, C-reactive protein (CRP), interleukin-6 (IL-6), plasminogen activation inhibitor-1, P-selectin, serum amyloid-A, soluble CD14, and apolipoprotein A1 in stored plasma. Conditional logistic regression identified associations with subsequent MI, with and without adjustment for Atherosclerotic Cardiovascular Disease (ASCVD) and Veterans Aging Cohort Study (VACS) scores. RESULTS: Higher IL-6 was associated with MI after adjustment for ASCVD score (adjusted odds ratio [AOR] 1.51, 95% confidence interval [95% CI]: 1.05 to 2.17 per standard-deviation-scaled log 2 increment). In a separate model adjusting for VACS score, higher ANG-2 (AOR 1.49, 95% CI: 1.04 to 2.14), higher CRP (AOR 1.45, 95% CI: 1.06 to 2.00), and higher IL-6 (AOR 1.68, 95% CI: 1.17 to 2.41) were associated with MI. In a sensitivity analysis excluding PWH with viral load ≥400 copies/mL, higher IL-6 remained associated with MI after adjustment for ASCVD score and after adjustment for VACS score. CONCLUSIONS: Among PWH, higher levels of plasma IL-6, CRP, and ANG-2 predict subsequent type 1 MI, independent of conventional risk scores. IL-6 had the most consistent associations with type 1 MI, regardless of viral load suppression.

Serum Angiopoietin-2 Predicts the Occurrence and Recurrence of Hepatocellular Carcinoma after Direct-Acting Antiviral Therapy for Hepatitis C.

Progressive liver fibrosis after anti-HCV treatment is a risk factor for HCC. Angiopoietin-2 (Ang2) is associated with non-regression of liver fibrosis after direct-acting antiviral (DAA). This study evaluated the predictive value of serum Ang2 levels for HCC occurrence or recurrence after DAA administration. In this retrospective study, 310 HCV-infected patients treated with DAAs in 2014-2020 were screened and evaluated for HCC occurrence or recurrence every three-six months. Multivariate Cox regression analysis revealed that age ≥ 75 years (HR: 2.92, 95% CI: 1.34-6.33; p = 0.007) and baseline Ang2 level ≥ 464 pg/mL (HR: 2.75, 95% CI: 1.18-6.37; p = 0.019) were significantly associated with HCC occurrence after DAA therapy. A high or low risk of HCC after DAA therapy could be distinguished by the combination of age and baseline Ang2 level. The cumulative incidences of de-novo HCC at two and four years were 0.8% and 3.8% in the low-risk group and 22.6% and 27.1% in the high-risk group, respectively. Baseline Ang2 level ≥ 402 pg/mL was significantly associated with HCC recurrence in patients who achieved sustained virological response with DAAs (HR: 3.68). In conclusion, serum Ang2 levels can predict HCC occurrence and recurrence after successful HCV eradication by DAAs.

Severe acute pancreatitis exhibits distinct cytokine signatures and trajectories in humans: a prospective observational study.

Severe acute pancreatitis (SAP) is associated with substantial morbidity and mortality. Several cytokines have been identified to have pathophysiological significance in SAP, but studies characterizing their early trajectories are lacking. Here we characterize the early trajectories of seven key cytokines associated with SAP and compare them with non-SAP subjects. Five proinflammatory cytokines (angiopoietin-2, interleukin-6, interleukin-8, monocyte chemoattractant protein-1, resistin) and two anti-inflammatory cytokines (hepatocyte growth factor, and soluble tumor necrosis factor-α receptor-1A) were measured in a prospective cohort of acute pancreatitis subjects (2012-2016) at the time of enrollment and then every 24 h for 5 days or until discharge. The cytokines' levels and trajectories were calibrated based on date of pain onset and were compared between healthy controls and three severity categories (mild, moderate, and severe). The cohort (n = 170) consisted of 27 healthy controls, 65 mild, 38 moderate, and 40 SAP. From day 1 of symptom onset, SAP subjects exhibited significantly higher levels of both pro- and anti-inflammatory cytokines compared with non-SAP and healthy subjects. But in SAP subjects, all proinflammatory cytokines' levels trended downward after day 2 (except for a flat slope for angiopoeitin-2) whereas for non-SAP subjects, the trajectory was upward: this trajectory difference between SAP versus non-SAP subjects resulted in narrowing of the differences initially seen on day 1 for proinflammatory cytokines. For anti-inflammatory cytokines, the trajectories were uniformly upward for both SAP and non-SAP subjects. Proinflammatory cytokine response is an early and time-sensitive event in SAP that should be accounted for when designing future biomarker studies and/or therapeutic trials.NEW & NOTEWORTHY In this study, we showed that the proinflammatory cytokine response in SAP is an early event, with subsequent downregulation of proinflammatory cytokines beginning at day 1 of symptom onset. Our findings underscore the importance of enrolling subjects very early in the disease course when conducting studies to investigate early immune events of SAP; this current study also serves as an important reference for the design of future biomarker studies and therapeutic trials in SAP.

Two phase I studies of BI 836880, a vascular endothelial growth factor/angiopoietin-2 inhibitor, administered once every 3 weeks or once weekly in patients with advanced solid tumors.

BACKGROUND: BI 836880 is a humanized bispecific nanobody® that inhibits vascular endothelial growth factor and angiopoietin-2. Here, we report results from two phase I, nonrandomized, dose-escalation studies (NCT02674152 and NCT02689505; funded by Boehringer Ingelheim) evaluating BI 836880 in patients with confirmed locally advanced or metastatic solid tumors, refractory to standard therapy, or for which standard therapy was ineffective. PATIENTS AND METHODS: Patients aged ≥18 years, with an Eastern Cooperative Oncology Group performance status of 0-2 and adequate organ function received escalating intravenous doses of BI 836880 once every 3 weeks (Q3W; Study 1336.1) or once weekly (QW; Study 1336.6). Primary objectives were maximum tolerated dose (MTD) and recommended phase II dose of BI 836880, based on dose-limiting toxicities (DLTs) during the first cycle. RESULTS: Patients received one of five dosages of 40-1000 mg Q3W (29 patients) or 40-240 mg QW (24 patients). One DLT occurred with Q3W treatment [Grade (G) 3 pulmonary embolism (1000 mg)]. Five DLTs occurred in four patients treated QW [G2 proteinuria (120 mg); G3 hypertension (180 mg); G3 proteinuria and G3 hypertension (240 mg); and G4 respiratory distress (240 mg)]. All patients experienced adverse events, most commonly hypertension with Q3W treatment (89.7%; G3 41.4%), and asthenia with QW treatment (62.5%). Two patients treated Q3W (both 1000 mg) and three patients treated QW (120 mg, 2 patients; 180 mg, 1 patient) experienced partial response. CONCLUSIONS: The MTD of BI 836880 was 720 mg Q3W and 180 mg QW. BI 836880 was generally manageable and demonstrated preliminary efficacy. CLINICAL TRIAL REGISTRATION: ClinicalTrials.govNCT02674152; https://clinicaltrials.gov/ct2/show/NCT02674152 and NCT02689505; https://clinicaltrials.gov/ct2/show/NCT02689505.

Colivelin, a synthetic derivative of humanin, ameliorates endothelial injury and glycocalyx shedding after sepsis in mice.

Endothelial dysfunction plays a central role in the pathogenesis of sepsis-mediated multiple organ failure. Several clinical and experimental studies have suggested that the glycocalyx is an early target of endothelial injury during an infection. Colivelin, a synthetic derivative of the mitochondrial peptide humanin, has displayed cytoprotective effects in oxidative conditions. In the current study, we aimed to determine the potential therapeutic effects of colivelin in endothelial dysfunction and outcomes of sepsis in vivo. Male C57BL/6 mice were subjected to a clinically relevant model of polymicrobial sepsis by cecal ligation and puncture (CLP) and were treated with vehicle or colivelin (100-200 µg/kg) intraperitoneally at 1 h after CLP. We observed that vehicle-treated mice had early elevation of plasma levels of the adhesion molecules ICAM-1 and P-selectin, the angiogenetic factor endoglin and the glycocalyx syndecan-1 at 6 h after CLP when compared to control mice, while levels of angiopoietin-2, a mediator of microvascular disintegration, and the proprotein convertase subtilisin/kexin type 9, an enzyme implicated in clearance of endotoxins, raised at 18 h after CLP. The early elevation of these endothelial and glycocalyx damage biomarkers coincided with lung histological injury and neutrophil inflammation in lung, liver, and kidneys. At transmission electron microscopy analysis, thoracic aortas of septic mice showed increased glycocalyx breakdown and shedding, and damaged mitochondria in endothelial and smooth muscle cells. Treatment with colivelin ameliorated lung architecture, reduced organ neutrophil infiltration, and attenuated plasma levels of syndecan-1, tumor necrosis factor-α, macrophage inflammatory protein-1α and interleukin-10. These therapeutic effects of colivelin were associated with amelioration of glycocalyx density and mitochondrial structure in the aorta. At molecular analysis, colivelin treatment was associated with inhibition of the signal transducer and activator of transcription 3 and activation of the AMP-activated protein kinase in the aorta and lung. In long-term outcomes studies up to 7 days, co-treatment of colivelin with antimicrobial agents significantly reduced the disease severity score when compared to treatment with antibiotics alone. In conclusion, our data support that damage of the glycocalyx is an early pathogenetic event during sepsis and that colivelin may have therapeutic potential for the treatment of sepsis-associated endothelial dysfunction.

Arsenic trioxide inhibits angiogenesis of hepatocellular carcinoma after insufficient radiofrequency ablation via blocking paracrine angiopoietin-1 and angiopoietin-2.

OBJECTIVES: Angiogenesis occurs during tumor progression of hepatocellular carcinoma (HCC) after insufficient radiofrequency ablation (RFA). Arsenic trioxide (ATO) shows promising therapeutic potential in advanced HCC. Whether ATO regulates angiogenesis and can be used to prevent tumor progression in HCC after insufficient RFA is still unknown. METHODS: Insufficient RFA was simulated using a water bath. MTT assay and tube formation assay were used to evaluate the effects of ATO on viability and proangiogenic abilities of SMMC7721 and HepG2 cells after insufficient RFA in vitro. The molecular changes with the treatment of ATO were evaluated through Western blot. An ectopic nude mice model was used to evaluate the effect of ATO on the tumor of SMMC7721 cells in vivo after insufficient RFA. RESULTS: In this study, HepG2 and SMMC7721 cells after insufficient RFA (named HepG2-H and SMMC7721-H, respectively) showed higher proliferation than the untreated cells and promoted tube formation of endothelial cells in a paracrine manner. ATO eliminated the difference in proliferation between untreated and RFA-treated cells and suppressed angiogenesis induced by HCC cells after insufficient RFA through the Ang-1 (angiopoietin-1)/Ang-2 (angiopoietin-2)/Tie2 pathway. Hif-1α overexpression abolished the inhibitory effect of ATO on angiogenesis in HCC after insufficient RFA. ATO inhibited tumor growth and angiogenesis in HCC after insufficient RFA. CONCLUSIONS: Our results demonstrate that ATO blocks the paracrine signaling of Ang-1 and Ang-2 by inhibiting p-Akt/Hif-1α and further suppresses the angiogenesis of HCC after insufficient RFA.

Endothelial biomarkers as predictors for haemodialysis need in severe leptospirosis patients (Weil's disease).

OBJECTIVE: To investigate the prediction ability of vascular injury biomarkers for haemodialysis requirement in patients with severe leptospirosis. METHODS: Prospective study with severe leptospirosis patients hospitalised in Fortaleza, Brazil. Blood samples were collected hospital admission to quantify vascular injury biomarkers: syndecan-1, ICAM-1, VCAM-1, angiopoietin-2 and FGF-23. Two groups were evaluated according to haemodialysis requirement during hospital stay. RESULTS: Twenty-seven patients were included, with a mean age of 39 ± 18 years. 88.9% were males. 53.8% needed haemodialysis and presented higher levels on hospital admission of syndecan-1 (572 [300-811] vs. 263 [106-421] ng/ml; p = 0.03), angiopoietin-2 (1.52 [0.72-2.72] vs. 0.63 [0.4-1.38] ng/ml; p = 0.01), and FGF-23 (291 [56-2031] vs. 10 [10-806] pg/ml; p = 0.021). Syndecan-1 showed significant correlation with creatinine (r = 0.546; p = 0.05) and total bilirubin levels (r = 0.534; p = 0.013) on hospital admission. Angiopoietin-2 showed significant correlation with creatinine levels (r = 0.513; p = 0.009) on hospital admission and with number of haemodialysis sessions (r = 0.406; p = 0.049). No significant correlation was found with FGF-23. Regarding prognostic performance, combined syndecan-1 and angiopoietin-2 levels had a better ability to predict haemodialysis need in patients with severe leptospirosis (AUC-ROC = 0.744 [95% CI: 0.545-0.943] p = 0.035). CONCLUSION: Syndecan-1 and angiopoietin-2 were associated with haemodialysis need in patients with severe leptospirosis and may be useful to improve therapeutic approach and reduce mortality.

Viewpoints: Dual-blocking antibody against VEGF-A and angiopoietin-2 for treating vascular diseases of the eye.

Faricimab, a bispecific antibody that targets the endothelial cell growth factors vascular endothelial growth factor-A (VEGF-A) and angiopoietin-2 (Angpt2), was recently approved for treating neovascular age-related macular degeneration and diabetic macular edema. Here, Koh and Augustin review how mechanistic studies have translated into therapies, while Campochiaro evaluates their impact and value for clinical practice.

Itraconazole versus propranolol: therapeutic and pharmacologic effect on serum angiopoietin-2 in patients with infantile hemangioma.

BACKGROUND: The initial recommendation propranolol usage in managing infantile hemangioma was in 2008 followed by various researches assessing the dosage, efficacy, and other parameters. Itraconazole is a world-wide tolerated antifungal but only a few studies have focused on its assessment in the treatment of infantile hemangiomas (IH). OBJECTIVE: This study aimed to investigate the newly proposed antifungal drug ICZ and characterize different aspects of its usage as an antiangiogenic drug. METHODS: This was an interventional clinical trial to assess the efficacy of ICZ versus propranolol in the treatment of infantile hemangioma with studying the change in serum angiopoietin 2 (Ang2). A total of 36 pediatric patients were divided into two equal groups: firstly treated with oral itraconazole and secondly treated by oral propranolol. RESULTS: Response to treatment was observed using a modified IH score. In itraconazole-treated infants, good response was observed in 44.4% of the patients. This was slightly higher than the propranolol group which showed 22.2% with good response. We observed a decrease in serum ang2 level after usage of ICZ and propranolol and the change in serum Ang2 level before and after treatment in each group was statistically significant (p < .001). CONCLUSION: Oral itraconazole can be an equivalent option for oral propranolol while safer and shorter treatment periods.

Evaluation of GLUT1, IGF-2, VEGF, FGF 1, and angiopoietin 2 in infantile hemangioma.

INTRODUCTION: Infantile hemangioma (IH) is a common vascular tumor in children. It is reported that IHs are associated with immunochemical markers such as vascular endothelial growth factor (VEGF)-A, glucose transporter isoform 1 (GLUT1), and insulin-like growth factor-2 (IGF-2). MATERIAL AND METHODS: This cross-sectional study focused on pediatric patients with IH. A total of 46 patients (mean age 14.2±21.9 months) with IH and 45 healthy controls (mean age 21.8±15.08 months) were enrolled. Demographic data, clinical findings, and laboratory parameters were recorded. Blood samples were collected. Serum GLUT1, IGF-2, VEGF-A, fibroblast growth factor 1 (FGF1), and angiopoietin 2 levels were assessed by enzyme-linked immunosorbent assay. RESULTS: Serum GLUT1, IGF-2, and VEGF-A levels were significantly higher in patients with IH than in healthy controls (8.80±4.07pg/mL vs. 5.66±4.34pg/mL, 281.10±84.12pg/mL vs. 234.19±75.38pg/mL, 1196.99±389.34pg/mL vs. 996.99±349.16pg/mL, respectively, p=0.026, p=0.030, and p=0.036). Serum GLUT1, IGF-2, and VEGF-A levels in patients with complicated hemangioma were significantly higher than in healthy controls (9.69±3.94pg/mL vs. 5.66±4.34pg/mL, 289.94±83.18pg/mL vs. 234.19±75.38pg/mL, 1276.22±388.24pg/mL vs. 996.99±349.16pg/mL, respectively, p=0.017, p=0.022, and p=0.011). Serum GLUT1, IGF-2, and VEGF-A levels in patients with hemangioma receiving propranolol treatment were significantly higher than in healthy controls. Serum FGF1 levels were higher in patients with IH, complicated hemangioma, and hemangioma receiving propranolol treatment than in healthy controls but the difference was not statistically significantly. CONCLUSION: Serum GLUT1, IGF-2, and VEGF-A levels were positively correlated with disease severity in patients with hemangioma, for example, in complicated hemangioma and hemangioma requiring propranolol treatment. However, further research on larger and different age subgroups is warranted to assess these markers.

Blood angiopoietin-2 predicts liver angiogenesis and fibrosis in hepatitis C patients.

BACKGROUND: Pathological angiogenesis is involved in the development of hepatocellular carcinoma. In patients with chronic hepatitis C (CHC), the level of angiogenic factor angiopoietin (ANGP)-2 is reported to be increased in the blood, correlating with fibrosis. In this study, we aimed to clarify whether blood ANGP-2 is useful as a biomarker for liver angiogenesis and fibrosis in CHC patients and to further reveal the relationship between such pathology in a carbon tetrachloride (CCl4)-treated liver fibrosis mouse model. METHODS: Plasma levels of ANGP-2, expression of a liver sinusoidal endothelial cell (LSEC) marker (CD31), collagen deposition (Sirius Red staining) in the liver, clinical fibrosis markers (Mac-2 binding protein glycosylation isomer, virtual touch quantification, and liver stiffness measurement), and liver function (albumin bilirubin score) were examined in CHC patients. To determine the effects of an anti-angiogenic agent on liver fibrosis in vivo, sorafenib was administered to the CCl4-treated mice (BALB/c male). RESULTS: The plasma levels of ANGP-2 were increased in CHC patients compared to healthy volunteers and decreased by the eradication of hepatitis C with direct-acting antivirals. In addition, plasma ANGP-2 levels were correlated with CD31 expression, collagen deposition, clinical fibrosis markers, and liver function. Sorafenib inhibited liver angiogenesis and fibrosis in the CCl4-treated mice and was accompanied by decreased ANGP-2 expression in LSECs. CONCLUSIONS: ANGP-2 may serve as a useful biomarker for liver angiogenesis and fibrosis in CHC patients. In addition, angiogenesis and fibrosis may be closely related.

Prognostic and Pathogenic Role of Angiopoietin-1 and -2 in Pneumonia.

RATIONALE: During pneumonia, pathogen-host interaction evokes inflammation and lung barrier dysfunction. Tie2 activation by angiopoietin-1 reduces, whereas Tie2 blockade by angiopoietin-2 increases, inflammation and permeability during sepsis. The role of angiopoietin-1/-2 in pneumonia remains unidentified. OBJECTIVES: To investigate the prognostic and pathogenic impact of angiopoietins in regulating pulmonary vascular barrier function and inflammation in bacterial pneumonia. METHODS: Serum angiopoietin levels were quantified in pneumonia patients of two independent cohorts (n = 148, n = 395). Human postmortem lung tissue, pneumolysin- or angiopoietin-2-stimulated endothelial cells, isolated perfused and ventilated mouse lungs, and mice with pneumococcal pneumonia were investigated. MEASUREMENTS AND MAIN RESULTS: In patients with pneumonia, decreased serum angiopoietin-1 and increased angiopoietin-2 levels were observed as compared with healthy subjects. Higher angiopoietin-2 serum levels were found in patients with community-acquired pneumonia who died within 28 days of diagnosis compared with survivors. Receiver operating characteristic analysis revealed improved prognostic accuracy of CURB-65 for 28-day survival, intensive care treatment, and length of hospital stay if combined with angiopoietin-2 serum levels. In vitro, pneumolysin enhanced endothelial angiopoietin-2 release, angiopoietin-2 increased endothelial permeability, and angiopoietin-1 reduced pneumolysin-evoked endothelial permeability. Ventilated and perfused lungs of mice with angiopoietin-2 knockdown showed reduced permeability on pneumolysin stimulation. Increased pulmonary angiopoietin-2 and reduced angiopoietin-1 mRNA expression were observed in Streptococcus pneumoniae-infected mice. Finally, angiopoietin-1 therapy reduced inflammation and permeability in murine pneumonia. CONCLUSIONS: These data suggest a central role of angiopoietin-1/-2 in pneumonia-evoked inflammation and permeability. Increased angiopoietin-2 serum levels predicted mortality and length of hospital stay, and angiopoietin-1 may provide a therapeutic target for severe pneumonia.

Angiopoietin-2 impairs collateral artery growth associated with the suppression of the infiltration of macrophages in mouse hindlimb ischaemia.

BACKGROUND: Angiopoietin-2 (Ang-2), a ligand of the Tie-2 receptor, plays an important role in maintaining endothelial cells and in destabilizing blood vessels. Collateral artery growth (arteriogenesis) is a key adaptive response to arterial occlusion. It is unknown whether the destabilization of blood vessels by Ang-2 can affect arteriogenesis and modulate mononuclear cell function. This study aimed to investigate the effects of Ang-2 on collateral artery growth. METHODS: Hindlimb ischaemia model was produced in C57BL/6 mice by femoral artery ligation. Blood flow perfusion was measured using a laser Doppler perfusion imager quantitative RT-PCR analysis was applied to identify the level of angiogenic factors. RESULTS: After the induction of hindlimb ischaemia, blood flow recovery was impaired in mice treated with recombinant Ang-2 protein; this was accompanied by a reduction of peri-collateral macrophage infiltration. In addition, quantitative RT-PCR analysis revealed that Ang-2 treatment decreased monocyte chemotactic protein-1 (MCP-1), platelet-derived growth factor-BB (PDGF-BB) mRNA levels in ischaemic adductor muscles. Ang-2 can lead to macrophage M1/M2 polarization shift inhibition in the ischaemic muscles. Furthermore, Ang-2 reduced the in vitro inflammatory response in macrophages and vascular cells involved in arteriogenesis. CONCLUSIONS: Our results demonstrate that Ang-2 is essential for efficient arteriogenesis, which controls macrophage infiltration.

Efficacy of Cotargeting Angiopoietin-2 and the VEGF Pathway in the Adjuvant Postsurgical Setting for Early Breast, Colorectal, and Renal Cancers.

Antiangiogenic tyrosine kinase inhibitors (TKI) that target VEGF receptor-2 (VEGFR2) have not been effective as adjuvant treatments for micrometastatic disease in phase III clinical trials. Angiopoietin-2 (Ang2) is a proangiogenic and proinflammatory vascular destabilizer that cooperates with VEGF. The purpose of this study was to test whether CVX-060 (an Ang2-specific CovX-body) can be combined with VEGFR2-targeting TKIs (sunitinib or regorafenib) to successfully treat postsurgical metastatic disease in multiple orthotopically implanted human tumor xenograft and syngeneic murine tumor models. In the MDA-MB-231.LM2-4 human breast cancer model, adjuvant sunitinib was ineffective, whereas adjuvant CVX-060 delayed the progression of pulmonary or distant lymphatic metastases; however, overall survival was only improved with the adjuvant use of a VEGF-A/Ang2-bispecific CovX-body (CVX-241) but not when CVX-060 is combined with sunitinib. Adjuvant CVX-241 also showed promise in the EMT-6/CDDP murine breast cancer model, with or without an immune checkpoint inhibitor (anti-PD-L1). In the RENCA model of mouse renal cancer, however, combining CVX-060 with sunitinib in the adjuvant setting was superior to CVX-241 as treatment for postsurgical lung metastases. In the HCT116 and HT29 xenograft models of colorectal cancer, both CVX-060 and regorafenib inhibited liver metastases. Overall, our preclinical findings suggest differential strategies by which Ang2 blockers can be successfully combined with VEGF pathway targeting in the adjuvant setting to treat micrometastatic disease-particularly, in combination with VEGF-A blockers (but not VEGFR2 TKIs) in resected breast cancer; in combination with VEGFR2 TKIs in resected kidney cancer; and as single agents or with VEGFR2 TKIs in resected colorectal cancer. Cancer Res; 76(23); 6988-7000. ©2016 AACR.

Role of angiopoietin-2 in infection - A double-edged sword?

The endothelial angiopoietin (Angpt)/Tie2 ligand receptor system maintains vascular quiescence and modulates the response to injury. Angpt-1 is considered the natural Tie2 agonist and receptor ligation leads to its phosphorylation inducing various protective downstream pathways. The natural antagonist - Angpt-2 - appears to inhibit these protective effects. In sepsis, the balance between both ligands is shifted in favor for Angpt-2 and the vasculature is highly dysfunctional, activated and leaky. Circulating levels of Angpt-2 strongly predict mortality in septic patients. Consistently, experimental strategies that target Angpt-2 (e.g. antibody, RNAi, etc.) can protect the vascular barrier and improve survival. However, in vitro is has also been shown that Angpt-2 can act as a dose-dependent Tie2 agonist/antagonist. Based on this, people have wondered if Angpt-2 is per se injurious or if it might have protective effects dependent on the scenario. A recent paper by Safioleas and colleagues showed survival benefits after a therapeutic injection of recombinant Angpt-2 in experimental pyelonephritis. Here, we discuss their counter-intuitive but interesting findings and put them into a global context with respect to the existent literature in the angiopoietin/Tie2 sepsis field.

Modulation of the release of Ang-2 in experimental endotoxic shock by a species-specific circulating factor.

OBJECTIVES: To study the modulation of the release of angiopoietin-2 (Ang-2) in experimental endotoxic shock. METHODS: Twelve pigs were studied; eight became septic after the intravenous infusion of lipopolysaccharide (LPS) of Escherichia coli O55:B5. The concentrations of LPS, angiopoietin-2 (Ang-2), tumour necrosis factor-alpha (TNFα) and malondialdehyde (MDA) were measured soon after the LPS infusion in the serum samples from the pulmonary and systemic circulation. Peripheral blood mononuclear cells (PBMCs) were isolated from two healthy swine, from two healthy human donors and from four patients with septic shock. The PBMCs were cultured with the serum of the septic animals in the presence or absence of polymyxin B. Concentrations of Ang-2 and TNFα were measured in supernatants. RESULTS: Serum Ang-2 was higher in the systemic circulation than in the pulmonary circulation. Increased Ang-2 release was noted in swine PBMCs in the presence of polymyxin B. A reciprocal decrease in TNFα release was observed, typically after incubation with serum sampled from the pulmonary circulation. CONCLUSION: There is evidence for a circulating factor that primes Ang-2 release from blood monocytes in the event of septic shock. The finding indicates a possible site of interference within the septic shock cascade.

Angiopoietin-2 modulates eEOC-mediated renoprotection in AKI in a dose-dependent manner.

BACKGROUND: Early endothelial outgrowth cells (eEOCs) significantly protect mice from acute kidney injury (AKI). Angiopoietin-2 (Ang-2) has been shown to be critically involved in vascular repair and homeostasis. The aim of this study was to investigate consequences of Ang-2 treatment of syngeneic murine eEOCs in a cell-based therapeutic approach for AKI. METHODS: Male 8- to 12-week-old C57/Bl6N mice, subjected to unilateral renal ischemia (40 minutes) postuninephrectomy were systemically injected with 0.5 × 10(6) untreated or Ang-2-pretreated syngeneic murine eEOCs. Renal function and morphology were analyzed 48 hours later. Cellular consequences of eEOC treatment with Ang-2 were evaluated using different in vitro assays (direct and indirect migration, apoptosis/necrosis, ELISA studies). RESULTS: Administration of untreated eEOCs did not protect mice from AKI. Ang-2 dose-dependently modulated cell effects in AKI. While incubating the cells at a concentration of 200 ng/mL (1 hour) did not have any effect on renal function, doubling the concentration (400 ng/mL) resulted in significant renoprotection of cell-injected mice. With 800 ng/mL, cell injection dramatically worsened renal function of treated animals. In vitro analysis showed significantly accelerated migration of cultured mature endothelial cells after incubation with supernatant from Ang-2-treated eEOCs (200 and 400 ng/mL). These effects were most pronounced with 400 mg/mL. In addition, Ang-2 promoted survival of eEOCs. Cellular releases of VEGF and IL-6 were decreased by Ang-2, while TGF-ß levels in the medium of Ang-2-stimulated eEOCs were not different from those in untreated cells. CONCLUSION: Ang-2 acts as modulator of eEOCs in AKI. The migration analysis indicates that the Ang-2 significantly alters indirect (paracrine) activity of eEOCs, thus promoting renoprotection in a dose-dependent manner.

Angiopoietin-2 enhances survival in experimental sepsis induced by multidrug-resistant Pseudomonas aeruginosa.

Levels of circulating angiopoietin-2 (Ang-2) increase in sepsis, raising the possibility that Ang-2 acts as a modulator in the sepsis cascade. To investigate this, experimental sepsis was induced in male C57BL6 mice by a multidrug-resistant isolate of Pseudomonas aeruginosa; survival was determined along with neutrophil tissue infiltration and release of proinflammatory cytokines. Survival was significantly increased either by pretreatment with recombinant Ang-2 2 h before or treatment with recombinant Ang-2 30 min after bacterial challenge. Likewise, Ang-2 pretreatment protected against sepsis-related death elicited by Escherichia coli; however, Ang-2 failed to provide protection in lipopolysaccharide (LPS)-challenged mice. The survival advantage of Ang-2 in response to P. aeruginosa challenge was lost in tumor necrosis factor (TNF)-deficient mice or neutropenic mice. Infiltration of the liver by neutrophils was elevated in the Ang-2 group compared with saline-treated animals. Serum TNF-α levels were reduced by Ang-2, whereas those of interleukin (IL)-6 and IL-10 remained unchanged. This was accompanied by lower release of TNF-α by stimulated splenocytes. When applied to U937 cells in vitro, heat-killed P. aeruginosa induced the secretion of IL-6 and TNF-α; low levels of exogenous TNF-α synergized with P. aeruginosa. This synergistic effect was abolished after the addition of Ang-2. These results put in evidence a striking protective role of Ang-2 in experimental sepsis evoked by a multidrug-resistant isolate of P. aeruginosa attributed to modulation of TNF-α production and changes in neutrophil migration. The protective role of Ang-2 is shown when whole microorganisms are used and not LPS, suggesting complex interactions with the host immune response.

Inhibition of in vivo tumor angiogenesis and growth via systemic delivery of an angiopoietin 2-specific RNA aptamer.

BACKGROUND: Cellular events mediated by the Tie2 receptor are important to tumor neovascularization. Despite the complex interplay of the best-characterized Tie2 ligands, angiopoietins 1 and 2, Ang2 is purportedly "proangiogenic" in the presence of vascular endothelial growth factor. We examined whether in vivo administration of an RNA aptamer that specifically blocks Ang 2 would inhibit tumor angiogenesis and growth. METHODS: Ang2-mediated Tie2 receptor phosphorylation was assessed in vitro in the absence and presence of aptamer coupled to polyethylene glycol. IN VIVO ANGIOGENESIS ASSAY: CT26 murine colon carcinoma cells expressing green fluorescent protein were delivered into mouse dorsal skinfold window chambers. Animals received daily intraperitoneal injections of phosphate-buffered saline, low-dose (Ang2 aptamer-LD; 1 mg/kg/d), or high-dose aptamer (Ang2 aptamer-HD; 10 mg/kg/d). Vascular length density was measured under fluorescence microscopy. PRIMARY TUMOR GROWTH: CT26 cells expressing luciferase were injected into flanks of BALB/c mice to allow tumor growth monitoring by bioluminescence imaging. Animals received continuous phosphate-buffered saline or aptamer (1 mg/kg/d) via ALZET pumps. Tumors were assessed for CD31/PECAM-1 immunostaining and Hoechst dye uptake. RESULTS: Pegylated aptamer inhibited Tie2 phosphorylation. Systemic aptamer administration reduced vascular length density (P < or = 0.03) and decreased bioluminescence emission (P < 0.04), corresponding to 50% decrease in tumor volume (P = 0.04). Control tumors displayed abundant vascular marker staining, in contrast to tumors from aptamer-treated animals. CONCLUSIONS: in vivo administration of a clinically relevant, pegylated RNA aptamer specifically designed against Ang2 inhibited tumor angiogenesis and growth. These findings support targeted Ang2 inhibition as a relevant anti-angiogenic, anti-neoplastic strategy.