Microcirculatory perfusion disturbances following cardiac surgery with cardiopulmonary bypass are associated with in vitro endothelial hyperpermeability and increased angiopoietin-2 levels.

BACKGROUND: Endothelial hyperpermeability following cardiopulmonary bypass (CPB) contributes to microcirculatory perfusion disturbances and postoperative complications after cardiac surgery. We investigated the postoperative course of renal and pulmonary endothelial barrier function and the association with microcirculatory perfusion and angiopoietin-2 levels in patients after CPB. METHODS: Clinical data, sublingual microcirculatory data, and plasma samples were collected from patients undergoing coronary artery bypass graft surgery with CPB (n = 17) before and at several time points up to 72 h after CPB. Renal and pulmonary microvascular endothelial cells were incubated with patient plasma, and in vitro endothelial barrier function was assessed using electric cell-substrate impedance sensing. Plasma levels of angiopoietin-1,-2, and soluble Tie2 were measured, and the association with in vitro endothelial barrier function and in vivo microcirculatory perfusion was determined. RESULTS: A plasma-induced reduction of renal and pulmonary endothelial barrier function was observed in all samples taken within the first three postoperative days (P < 0.001 for all time points vs. pre-CPB). Angiopoietin-2 and soluble Tie2 levels increased within 72 h after CPB (5.7 ± 4.4 vs. 1.7 ± 0.4 ng/ml, P < 0.0001; 16.3 ± 4.7 vs. 11.9 ± 1.9 ng/ml, P = 0.018, vs. pre-CPB), whereas angiopoietin-1 remained stable. Interestingly, reduced in vitro renal and pulmonary endothelial barrier moderately correlated with reduced in vivo microcirculatory perfusion after CPB (r = 0.47, P = 0.005; r = 0.79, P < 0.001). In addition, increased angiopoietin-2 levels moderately correlated with reduced in vitro renal and pulmonary endothelial barrier (r = - 0.46, P < 0.001; r = - 0.40, P = 0.005) and reduced in vivo microcirculatory perfusion (r = - 0.43, P = 0.01; r = - 0.41, P = 0.03). CONCLUSIONS: CPB is associated with an impairment of in vitro endothelial barrier function that continues in the first postoperative days and correlates with reduced postoperative microcirculatory perfusion and increased circulating angiopoietin-2 levels. These results suggest that angiopoietin-2 is a biomarker for postoperative endothelial hyperpermeability, which may contribute to delayed recovery of microcirculatory perfusion after CPB. TRIAL REGISTRATION: NTR4212 .

The relationship with clinical course and prognosis of serum endothelin-1, angiopoietin-2, and tie-2 levels in Crimean-Congo hemorrhagic fever

Background/aim: Crimean-Congo hemorrhagic fever (CCHF) is a serious illness characterized by fever and hemorrhage. Endothelin-1 (ET-1), angiopoietin-2 (Ang-2), and endothelial cell-specific receptor tyrosine kinase (Tie-2) are believed to be important markers of the pathogenesis, clinical course, and prognosis of the disease. The aim of this study was to determine ET-1, Ang-2, and Tie-2 levels in adults with CCHF and investigate the associations between these markers and pathogenesis and disease course. Materials and methods: Sixty CCHF patients were included in the study. The patients were classified according to disease severity criteria and Ang-2, Tie-2, and ET-1 levels were compared. Results: Mean serum ET-1 level was 36.62 ± 27.99 pg/mL in the patient group and 3.70 ± 4.71 pg/mL in the control group (P = 0.001). Mean serum Ang-2 levels were 2511.18 ± 1018.64 pg/mL in the patient group and 3570.76 ± 209.52 pg/mL in the control group (P = 0.001). Mean serum Tie-2 levels were 7.35 ± 7.75 ng/mL in the patient group and 0.67 ± 1.26 ng/mL in the control group (P = 0.001). Conclusion: Elevated ET-1 and Tie-2 levels were associated with more severe disease course, while Ang-2 level was negatively correlated with severity in adult CCHF patients. ET-1, Tie-2, and Ang-2 levels are important prognostic parameters in CCHF and may contribute significantly to treatment and follow-up.

Circulating Vascular Growth Factors and Magnetic Resonance Imaging Markers of Small Vessel Disease and Atrophy in Middle-Aged Adults.

Background and Purpose- Little is known about associations between vascular growth factors and magnetic resonance imaging (MRI) markers in midlife. We investigated the association of serum VEGF (vascular endothelial growth factor), Ang2 (angiopoietin 2), sTie2 (soluble tyrosine kinase with immunoglobulin-like and EGF-like domains 2), and HGF (hepatocyte growth factor) concentrations with MRI markers of brain aging in middle-aged adults. Methods- We evaluated 1853 participants (mean age, 46±9 years; 46% men) from the Framingham Heart Study. Serum growth factor concentrations were measured using standardized immunoassays. Outcomes included total brain, cortical and subcortical gray matter, white matter, cerebrospinal fluid, and white matter hyperintensity volumes derived from MRI; as well as fractional anisotropy in white matter tracts from diffusion tensor imaging. We related VEGF, Ang2, sTie2, and HGF to MRI measures using multivariable regression models adjusting for vascular risk factors. We tested for interactions with APOE (apolipoprotein E) genotype and CRP (C-reactive protein). Results were corrected for multiple comparisons. Results- Higher sTie2 was associated with smaller total brain (estimate by SD unit±SE=-0.08±0.02, P=0.002) and larger white matter hyperintensity (0.08±0.02, P=0.002) volumes. Furthermore, higher Ang2 (0.06±0.02, P=0.049) and HGF (0.09±0.02, P=0.001) were associated with larger cerebrospinal fluid volumes. Finally, higher Ang2 was associated with decreased fractional anisotropy, in APOE-ε4 carriers only. Conclusions- Vascular growth factors are associated with early MRI markers of small vessel disease and neurodegeneration in middle-aged adults.

Circulating angiopoietin-2 and its soluble receptor Tie-2 concentrations are related to inflammatory markers in the general population.

BACKGROUND: The Angiopoietin/Tie (Tyrosine kinase with Ig and EGF homology domains) signaling axis has crucial influences on angiogenesis and the vasculature's reorganization. Moreover, angiopoietin-2 (Ang2) is discussed as a biomarker for diseases' severity and development. Previous studies reported increased Ang2 levels in patients with inflammatory diseases and associations of Ang2 with inflammation markers in relatively small samples. We aimed to assess the relation of Ang2 and Tie2 with inflammation markers in the general population. METHODS AND RESULTS: Data of 6624 participants of the population-based Study of Health in Pomerania (SHIP-1) and the independent SHIP-Trend were used. Ang2, Tie2 and inflammatory biomarkers, including fibrinogen, high-sensitive C-reactive protein (hsCRP) and white blood cell count (WBC), were measured. Adjusted analysis of variance (ANOVA) and linear/logistic regression models were performed in the entire sample and in individuals free of hypertension and diabetes. ANOVA [adjusted means of the 1st vs. 4th Ang2 quartile: fibrinogen 3.0 vs. 3.2 g/l; hsCRP 1.2 vs. 1.6 mg/l; WBC 5.9 vs. 6.6 Gpt/l] and regression models adjusted for potential confounders revealed positive relations of Ang2 with all considered inflammation markers. These associations persisted after the exclusion of individuals with hypertension and diabetes. In contrast, Tie2 showed no clear association pattern with the investigated inflammatory markers even if a trend toward a positive relation with fibrinogen became apparent. CONCLUSION: Ang2 was positively associated with fibrinogen, hsCRP and WBC in a large population-based setting. These findings partly agree with previous results, largely obtained in clinical samples. Ang2 has diverse postulated effects on inflammation processes, like increase of vascular leakage or influences on the adhesion of leukocytes to the vessel wall. The proinflammatory character of these effects is similar to these of fibrinogen which conforms to our findings of relations between the markers. However, further research is needed to elucidate possible functional mechanisms.

Elevated Serum CD95/FAS and HIF-1α Levels, but Not Tie-2 Levels, May Be Biomarkers in Patients With Severe Endometriosis: A Preliminary Report.

STUDY OBJECTIVE: To evaluate serum values of cluster of differentiation 95 (CD95/FAS), hypoxia-inducible factor 1-alpha (HIF-1α), and tyrosine kinase receptor 2 (Tie-2) as possible biomarkers of disease presence and severity in women with endometriosis, and to characterize the changes in these values in women with stage I/II and stage III/IV endometriosis. DESIGN: Prospective study (Canadian Task Force classification I). SETTING: University hospital. PATIENTS: Thirty women with endometriosis and 30 healthy women without endometriosis. INTERVENTION: For the diagnosis of endometriosis and prediction of its severity, we measured the serum levels of CD95/FAS, which assess apoptotic conditions, and of HIF-1α and Tie-2, which assess angiogenesis. Endometriosis was diagnosed and staged through surgical laparoscopy and later confirmed histologically. During the surgery, the patients with endometriosis were divided into 2 groups based on disease stage. Eleven patients had stage I/II endometriosis, and 19 had stage III/IV endometriosis. MEASUREMENTS AND MAIN RESULTS: Endometriosis was associated with increased serum CD95/FAS and HIF-1α levels, but not Tie-2 levels. We also determined that stage III/IV endometriosis was associated with higher serum CD95/FAS and HIF-1α levels, but not Tie-2 levels, compared with stage I/II endometriosis. CONCLUSION: Endometriosis, in accordance with its severity, increases serum CD95/FAS and HIF-1α levels, but not Tie-2 levels. These biomarkers may be useful for reproductive surgeons to improve the quality of counseling women about the presence and severity of endometriosis.

Markers of endothelial function in migraine patients: Results from a bi-center prospective study.

BACKGROUND: Numerous studies suggest an increased vascular risk in patients with migraine, in particular in those with aura. A possible link between both conditions might be a dysfunction of the vascular endothelium. This observational study analyzed the endothelial markers angiopoietin-1, angiopoietin-2, Tie-2, sFlt-1 and NT-proBNP for the first time in migraineurs, patients with other primary headache disorders and healthy controls. METHODS: Patients with episodic migraine with and without aura, episodic cluster headache, tension-type headache and healthy controls were included. Blood samples were obtained during migraine attacks and headache-free periods in migraineurs, in and out of bout in cluster headache and during headache-free periods in tension-type headache and healthy individuals to analyze markers of endothelial function. RESULTS: No significant difference in endothelial markers between migraine, other headache disorders and healthy controls was detected. There was no significant difference between migraine attacks and headache-free intervals. Additionally, no distinction could be found between migraine with and without aura. DISCUSSION: The endothelial markers analyzed do not display a characteristic pattern in different headache disorders especially migraine compared to healthy controls. The novel findings of our study indicate that factors other than endothelial dysfunction seem to be responsible for the at least statistical association of migraine with vascular disease.

Angiopoietin-2-induced arterial stiffness in CKD.

The mechanism of vascular calcification in CKD is not understood fully, but may involve collagen deposition in the arterial wall upon osteo/chondrocytic transformation of vascular smooth muscle cells (VSMCs). Increased levels of circulating angiopoietin-2 correlate with markers of CKD progression and angiopoietin-2 regulate inflammatory responses, including intercellular and vascular adhesion and recruitment of VSMCs. Here, we investigate the potential role of angiopoietin-2 in the pathogenesis of arterial stiffness associated with CKD. In a cohort of 416 patients with CKD, the plasma level of angiopoietin-2 correlated independently with the severity of arterial stiffness assessed by pulse wave velocity. In mice subjected to 5/6 subtotal nephrectomy or unilateral ureteral obstruction, plasma levels of angiopoietin-2 also increased. Angiopoietin-2 expression markedly increased in tubular epithelial cells of fibrotic kidneys but decreased in other tissues, including aorta and lung, after 5/6 subtotal nephrectomy. Expression of collagen and profibrotic genes in aortic VSMCs increased in mice after 5/6 subtotal nephrectomy and in mice producing human angiopoietin-2. Angiopoietin-2 stimulated endothelial expression of chemokines and adhesion molecules for monocytes, increased Ly6C(low) macrophages in aorta, and increased the expression of the profibrotic cytokine TGF-ß1 in aortic endothelial cells and Ly6C(low) macrophages. Angiopoietin-2 blockade attenuated expression of monocyte chemokines, profibrotic cytokines, and collagen in aorta of mice after 5/6 subtotal nephrectomy. This study identifies angiopoietin-2 as a link between kidney fibrosis and arterial stiffness. Targeting angiopoietin-2 to attenuate inflammation and collagen expression may provide a novel therapy for cardiovascular disease in CKD.

Disturbed balance between serum levels of receptor tyrosine kinases Tie-1, Tie-2 and angiopoietins in systemic sclerosis.

OBJECTIVE: The aim of this study was to determine the characteristic factors for vascular development and maintenance levels as well as correlation between Tie-1 receptors, Tie-2 receptors and the corresponding ligands--angiopoietins--in systemic sclerosis (SSc) patients. MATERIALS AND METHODS: Serum levels of Tie-1, Tie-2, Ang-1 and Ang-2 were measured in 25 SSc patients and healthy controls. RESULTS: There was a statistically significant difference in serum Tie-1 (p = 0.009) and Ang-2 (p = 0.001) levels in SSc patients compared with healthy controls. Significant correlations between Tie-1 and Tie-2 (ρ = 0.70, p = 0.0001) and between Tie-1 and Ang-2 (ρ = -0.92, p = 0.002) were found in the SSc group. Serum levels of Tie-2 were positively associated with esophagus changes (U = 2.03, p = 0.041) and Ang-1 was negatively correlated with duration of Raynaud's phenomenon (ρ = -0.75, p = 0.00008). CONCLUSION: The increase in serum concentration of Tie-1 and Ang-2 in patients with SSc may confirm a molecular imbalance between receptor tyrosine kinases Tie and their ligands.

Fluid bolus increases plasma hyaluronan concentration compared to follow-up strategy without a bolus in oliguric intensive care unit patients.

Fluid therapy is a fundamental part of supportive therapy in critical care. However, it is also a suspected risk for endothelial glycocalyx degradation which is associated with poor clinical outcomes. This secondary analysis of RESPONSE randomized trial compares the effect of follow-up strategy (FU) on endothelial biomarkers to that of 500 ml crystalloid fluid bolus (FB) in oliguric, hemodynamically optimized intensive care unit (ICU) patients. 130 adult subjects were enrolled in two Finnish ICUs from January 2017 to November 2020. Blood and urine samples of 63 patients in FU group and 67 patients in FB group were collected before and after the intervention and analyzed using enzyme-linked immunosorbent assays. Single fluid bolus, given after median of 3887 ml (interquartile range 2842; 5359 ml) resuscitation fluids in the preceding 24 h, increased plasma hyaluronan concentration compared to the follow-up strategy (difference in medians 29.2 ng/ml with 95% CI [14.5ng/ml; 55.5ng/ml], P < 0.001). No treatment effect was detected in the plasma levels of syndecan-1, , angiopoietin-2, angiopoietin receptors Tie2 and Tie1, or in soluble thrombomodulin in the adjusted median regression analysis. The increase in hyaluronan was independent of its simultaneous renal clearance but correlated moderately with the increase in endothelium-specific Tie1. The follow-up strategy did not show consistent endothelium-sparing effect but protected against hyaluronan increase. The mechanisms and consequences of hyaluronan fluctuations need further clarification. Trial registration: clinicaltrials.gov, NCT02860572. Registered 1 August 2016, https://www.clinicaltrials.gov/study/NCT02860572?term=NCT02860572&rank=1.

The Angiopoietin-Tie-2 Axis in Children and Young Adults with Dengue Virus Infection in the Philippines.

Dengue virus (DENV) infection is associated with plasma leakage, which may progress to shock. The angiopoietin (Ang)-tyrosine kinase with immunoglobulin and epidermal growth factor homology domain 2 (Tie-2) axis regulates endothelial permeability. We examined the clinical utility of Ang-1, Ang-2, and the Ang-2-to-Ang-1 ratio for prediction of progression to severe DENV in a prospective cohort study of children and young adults (age 1 to <26 years) with DENV infection. Ang-1, Ang-2, Tie-2 were measured at presentation to an outpatient clinic in the Philippines from stored plasma by multiplex Luminex® assay. Patients were followed prospectively to document the clinical course (hospitalization, length of stay, intravenous fluid resuscitation, and transfer to a higher level facility). We included 244 patients (median age 9 years, 40% female). At presentation, 63 patients (26%) had uncomplicated dengue, 179 (73%) had dengue with warning signs, and 2 (0.82%) had severe dengue. One hundred eighty-one patients (74%) were hospitalized. Ang-1 levels were lower and Ang-2 higher in patients who required hospitalization. Ang-2-to-Ang-1 ratio >1 was associated with a relative risk of hospitalization of 1.20 (95% CI: 1.03-1.36, P = 0.016). A higher Ang-2-to-Ang-1 ratio was associated with longer length of hospital stay, higher frequency of transfer to a higher level facility, larger intravenous fluid requirement, hemoconcentration, and thrombocytopenia. Angiopoietin-2 was correlated with procalcitonin (Kendall's τ = 0.17, P = 0.00012), a marker of systemic inflammation, as well as soluble vascular cell adhesion molecule-1 (τ = 0.22, P <0.0001) and Endoglin (τ = 0.14, P = 0.0017), markers of endothelial activation. In conclusion, altered Ang-2-to-Ang-1 ratio can be detected early in the course of DENV infection and predicts clinically meaningful events (hospitalization, length of stay, and fluid resuscitation).

Population pharmacokinetic-pharmacodynamic modeling of serum biomarkers as predictors of tumor dynamics following lenvatinib treatment in patients with radioiodine-refractory differentiated thyroid cancer (RR-DTC).

Lenvatinib is a receptor tyrosine kinase (RTK) inhibitor targeting vascular endothelial growth factor (VEGF) receptors 1-3, fibroblast growth factor (FGF) receptors 1-4, platelet-derived growth factor receptor-α (PDGFRα), KIT, and RET that have been implicated in pathogenic angiogenesis, tumor growth, and cancer. The primary objective of this work was to evaluate, by establishing quantitative relationships, whether lenvatinib exposure and longitudinal serum biomarker data (VEGF, Ang-2, Tie-2, and FGF-23) are predictors for change in longitudinal tumor size which was assessed based on data from 558 patients with radioiodine-refractory differentiated thyroid cancer (RR-DTC) receiving either lenvatinib or placebo treatment. Lenvatinib PK was best described by a 3-compartment model with simultaneous first- and zero-order absorption and linear elimination from the central compartment with significant covariates (body weight, albumin <30 g/dL, ALP>ULN, RR-DTC, RCC, HCC subjects, and concomitant CYP3A inhibitors). Except for body weight, none of the covariates have any clinically meaningful effect on exposure to lenvatinib. Longitudinal biomarker measurements over time were reasonably well defined by a PK/PD model with common EC50, Emax, and a slope for disease progression for all biomarkers. Longitudinal tumor measurements over time were reasonably well defined by a tumor growth inhibition Emax model, which in addition to lenvatinib exposure, included model-predicted relative changes from baseline over time for Tie-2 and Ang-2 as having significant association with tumor response. The developed PK/PD models pave the way for dose optimization and potential prediction of clinical response.

Serum levels of angiopoietin-2 are associated with the growth of multiple myeloma.

Angiopoietins and their receptor, Tie-2, have crucial role in angiogenesis. We measured serum levels of angiopoietin-2 (Ang-2), soluble Tie-2, and factors of burden and prognosis in myeloma (LDH, CRP, beta-2 microglobulin, and interleukin-6) in 55 newly diagnosed patients, with 30 of them in plateau phase, in order to note correlations among them. Levels of Ang-2 were higher in patients in advanced stage of disease, decreased in plateau phase, and correlated with all other factors. Circulating Ang-2 in myeloma patients significantly correlated to factors of disease burden and prognosis, and therefore measuring its levels may be important for the valuation of the disease.

A clinicopathological correlation of the expression of the angiopoietin-Tie-2 receptor pathway in the brain of adults with Plasmodium falciparum malaria.

BACKGROUND: Plasma angiopoietin (Ang)-2 is associated with disease severity and mortality in adults and children with falciparum malaria. However the mechanism of action of the angiopoietins in fatal malaria is unclear. This study aimed to determine whether the expression of Ang-1 and Ang-2 and their receptor Tie-2 in cerebral endothelial or parenchymal cells was specific to cerebral malaria (CM), correlated with coma or other severe clinical features, and whether plasma and CSF levels of these markers correlated with the clinical and neuropathological features of severe and fatal malaria in Vietnamese adults. METHODS: Immunohistochemistry was performed for Ang-1, Ang-2 and Tie-2 on post-mortem brain tissue from fatal malaria cases and controls. Quantitative ELISA for plasma and cerebrospinal fluid levels of Ang-1, Ang-2 and Tie-2 was done to compare fatal cases with surviving patients from the same study. RESULTS: Immunohistochemistry revealed significant differences in expression in endothelial and parenchymal cells compared to controls. However there was no significant difference in expression of these markers on endothelial cells, astroglial cells or neurons between CM and non-cerebral malaria cases. Immunostaining of Ang-1, Ang-2 and Tie-2 was also not associated with Plasmodium falciparum-infected erythrocyte sequestration in the brain. However Ang-1 and Ang-2 expression in neurons was significantly correlated with the incidence of microscopic haemorrhages. Plasma levels of Ang-2 and Ang-2/Ang-1 ratio were associated with the number of severe malaria complications and were significant and independent predictors of metabolic acidosis and fatal outcome. CONCLUSIONS: The independent prognostic significance of Ang-2 and the Ang-2/Ang-1 ratio in severe malaria was confirmed, although immunohistochemistry in fatal cases did not reveal increased expression on brain endothelium in cerebral versus non-cerebral cases. Activation of the Ang-Tie-2 pathway in severe malaria is therefore related to acidosis, number of severity criteria and outcome, but is not a specific event in the brain during cerebral malaria.

Circulating angiopoietin and Tie-2 levels in systemic sclerosis.

To determine the potential effects of angiopoietins Ang-1 and Ang-2 and their receptor Tie-2 in patients with systemic sclerosis (SSc). Twenty-six patients with limited SSc (l-SSc) and fourteen patients with diffuse SSc (d-SSc) were evaluated and compared to age-matched controls. Plasma levels of soluble sAng-1, sAng-2, sTie-2, vascular endothelial growth factor (VEGF), placental growth factor (PlGF) and endostatin were measured. Associations between these factors and clinical parameters were assessed. Levels of circulating factors and the ratios sAng-2/sAng-1 and sAng-2/sTie-2 were not different between l-SSc and d-SSc cases but were collectively higher compared to their controls: sAng-1 (p = 0.0108); sAng-2 (p < 0.0001); sTie-2 (p < 0.0001); endostatin (p < 0.0001), PlGF (p < 0.0001); VEGF (p = 0.0006); sAng-2/sAng-1 (p < 0.0001); sAng-2/sTie-2 (p < 0.0001). Concerning significant correlations among the angiopoietins and Tie-2, sAng-2 associated with sTie-2 (Spearman r = 0.47, p = 0.0155) in l-SSc only. sAng-1 did not show statistically significant correlations with any of the clinical variables, but sAng-2 did between PAP (r = 0.51, p = 0.0148) and predicted DLCO (r = -0.31, p = 0.0242) in l-SSc cases. sTie-2 negatively correlated with disease duration in l-SSc (r = -0.55, p = 0.0049). The sAng-2/sTie-2 ratio shows a positive association with disease activity in both l-SSc (r = 0.50, p = 0.0547) and d-SSc (r = 0.60, p = 0.0317). Levels of sAng-1, sAng-2 and sTie-2 are higher in SSc cases suggesting a pro-inflammatory state in an active endothelium. The near doubling of the sAng-2/sTie-2 ratio in SSc cases compared to controls suggests a shift toward vascular regression and angiostasis perhaps caused by Ang-2 blocking the action of Tie-2.

Prognostic value of serum Tie-2 and vascular endothelial growth factor levels in cancer patients.

BACKGROUND: Angiogenesis is a very essential process in tumor biology. Vascular endothelial growth factor (VEGF), angiopoietin and its receptor (TIE-2) are very important mediators for angiogenesis. In this trial, we aimed to analyze the role of these mediators on chemotherapy response and survival. PATIENTS AND METHODS: Forty four cancer patients and 22 healthy controls were included in the study. Baseline serum samples were obtained from all participants and post-chemotherapy serum samples were obtained from the cancer patients. Serum vascular endothelial growth factor and TIE-2 levels were measured with quantitative enzyme-linked immunosorbent assay techniques. RESULTS: The baseline serum vascular endothelial growth factor level was 187.5 and 120.2 pg/ml in cancer patients and the control group (p = 0.006). The baseline serum TIE-2 level was 615.9 and 242.5 pg/ml in the patients and control group (p < 0.001). There was a significant difference between patients' baseline and post-chemotherapy VEGF levels (111.9 pg/ml; p < 0.001) and patients' baseline and post-chemotherapy TIE-2 levels (344.5 pg/ml; p < 0.001). The overall survival rate was better in patients who had lower baseline VEGF and TIE-2 levels and whose TIE-2 level had decreased with chemotherapy. CONCLUSIONS: Higher baseline TIE-2 and VEGF levels are related and worsen survival. Decreasing levels of TIE-2, but not VEGF, which, with chemotherapy, may be predictive for survival.

sVEGF R1 and Tie-2 levels during chemotherapy of lung cancer patients.

Angiogenesis plays important role in tumor growth and development. Protein ligands and their receptor tyrosine kinases are crucial in tumor related angiogenesis. Ligand/receptor systems such as vascular endothelial growth factor (VEGF), and tyrosine kinase with immunoglobulin-like and epidermal growth factor homology domains (Tie) family play important role in this phenomenon. The aim of this study was to evaluate the concentration of soluble receptor of VEGF (sVEGF R1) and Tie-2 domain in plasma of lung cancer patients before and after chemotherapy. Forty four lung cancer patients, 11 with small lung cancer (SCLC), 5 females and 6 males (mean age 60.2, range 39-72 years), and 33 patients with non-small cell lung cancer (N-SCLC), 6 females and 27 males (mean age 61.9, range 42-78 years) received four courses of chemotherapy. Control group consisted of 44 patients with COPD, 4 females and 40 males (mean age 37.1, 18-60 years). In all cases clinical partial response was achieved. Both sVEGF R1 and Tie-2 concentrations were elevated in cancer group before treatment compared with control: sVEGF (pg/ml): 60.7 and 66.2 vs. 48.8 and Tie-2 (ng/ml): 37.3 and 37.5 vs. 30.7 in SCLC and N-SCLC vs. C, respectively. Treatment decreased sVEGF R1 (pg/ml): 66.7 vs. 11.6 (p < 0.05) and 66.2 vs. 14.39 (p < 0.001), and Tie-2 (ng/ml): 37.3 vs. 26.3 (p < 0.05) and 37.5 vs. 25.7 (p < 0.001) in SCLC and N-SCLC, respectively. We conclude that VEGF R1and Tie-2 receptors may play important role in lung cancer development and their receptor concentrations may reflect the patients' response to treatment.

Analysis of Tie2-expressing monocytes (TEM) in patients with colorectal cancer.

Tie2-expressing monocytes (TEM) promote tumor angiogenesis and growth in experimental cancer models. The role of TEM in cancer patients is unknown. We studied TEM in healthy volunteers and colorectal cancer (CRC) patients. Although TEM were detectable in the blood and tumor lesions of CRC patients, their frequency and functional phenotype showed no correlation with levels of angiopoietin-2 or vascular endothelial growth factor, microvessel density, tumor markers, tumor stage, or outcome of antiangiogenic therapy. These unexpected findings are at odds with murine tumor models and question the diagnostic or therapeutic value of TEM in human cancer.

Angiopoietin-2 levels predict mortality in CKD patients.

BACKGROUND: The pathophysiology of aggravated atherosclerosis in chronic kidney disease (CKD) is still incompletely understood. However, there is an increasing focus on non-traditional risk factors, including endothelial dysfunction. Angiopoietin-2 (Ang-2) impairs endothelial function by inhibiting the binding of Angiopoietin-1 (Ang-1) to their shared receptor Tie2 and is increased in diabetes, hypertension, coronary heart disease and CKD. Furthermore, Ang-2 levels are associated with the prevalent vascular burden of CKD patients. Thus, we aimed to investigate its impact on outcome in CKD, the population most likely to die of cardiovascular events. METHODS: We prospectively studied 128 CKD patients [43 CKD Stage 4, 85 CKD Stage 5 (57 haemodialysis, 28 peritoneal dialysis)] over a follow-up period of 4 years. Biochemical and clinical parameters, including objective scoring of vascular calcification (VC) by computed tomography (CT) and arterial stiffness by applanation tonometry (including radial-dorsalis pedis pulse wave velocity (PWVrd)) were recorded. Baseline Ang-1 [enzyme-linked immunosorbent assay (ELISA)], Ang-2 [immunoluminometric assay (ILMA)] and soluble Tie2 (sTie2) (ELISA) levels were measured in this group as well as in 20 healthy controls. RESULTS: Ang-2 values were significantly higher in CKD patients than in controls (2.01 ± 0.94 versus 1.00 ± 0.47 ng/mL, P < 0.0001). Furthermore, Ang-2 was significantly higher in dialysis than in Stage 4 CKD patients and correlated with markers of vascular disease [cholesterol, hsCRP, osteoprotegerin (OPG)]. However, elevated Ang-2 was not associated with the degree of VC or with arterial stiffness. Cox-regression analysis detected Ang-2 as an independent predictor of mortality in both unadjusted [hazard ratio (HR) 1.15; P = 0.002] and models adjusted for age and VC (HR 1.14; P = 0.003). CONCLUSIONS: Ang-2 levels are associated with systemic markers/mediators of micro-inflammation in CKD patients. Furthermore, elevated Ang-2 levels are strong predictors of long-term mortality, independent of conduit arterial stiffness or VC.

Significant decrease in maternal serum concentrations of angiopoietin-1 and -2 after delivery.

OBJECTIVE: To characterize the physiological distribution of angiopoietins (Ang)-1 and Ang-2 and soluble endothelial cell-specific tyrosine kinase receptor-2 (Tie-2) at term and following delivery. DESIGN: A prospective, descriptive study. SETTING: Helsinki University Central Hospital. POPULATION: Twenty healthy term pregnant women undergoing elective cesarean delivery and their newborns. METHODS: The concentrations were analysed by enzyme-linked immunosorbent assay in maternal antepartum and the first postpartum day sera, umbilical serum, amniotic fluid and maternal and newborn urine. MAIN OUTCOME MEASURES: Concentrations of Ang-1, Ang-1 and Tie-2. Results. Concentrations of maternal serum Ang-1 and Ang-2 decreased after delivery {[median (range)]: Ang-1, from 33 (25-51) to 30 (18-49) ng/mL, p= 0.017; and Ang-2, from 5.4 (1.8-18) to 1.4 (0.7-4.6) ng/mL, p < 0.0001}, whereas Tie-2 concentrations remained stable [23 (13-41) vs. 25 (14-29) ng/mL, p= 0.107]. Compared with maternal antepartum serum, umbilical serum concentrations of Ang-1 [46 (28-59) ng/mL, p < 0.0001] and Tie-2 [45 (21-71) ng/mL, p < 0.0001] were higher and those of Ang-2 similar [5.4 (1.8-18) vs. 4.2 (2.9-6.0) ng/mL; p= 0.067]. Low concentrations of Ang-1 [1.2 (0.1-2.2) ng/mL], Ang-2 [1.1 (0.3-4.1) ng/mL] and Tie-2 [0.4 (0.08-0.9) ng/mL] were observed in amniotic fluid, but they were undetectable in newborn urine and in most of the maternal urine samples. CONCLUSIONS: Maternal Ang-1 and Ang-2 concentrations decreased following delivery. Umbilical concentrations of Ang-1 and Tie-2 were higher than the maternal concentrations.

Elevated peripheral blood plasma concentrations of tie-2 and angiopoietin 2 in patients with neuroendocrine tumors.

BACKGROUND: Gastro-entero-pancreatic/neuroendocrine (NET) tumors are highly vascularized neoplasms. However, our knowledge concerning circulating levels of the angiogenic factors in NET patients still remains insufficient. METHODS: The aim of this study was to measure plasma concentrations of VEGF, angiopoietin 1 (Ang-1), angiopoietin 2 (Ang-2), soluble Tie-2, endostatin, osteopontin (OPN) and chromogranin A (CgA) in 36 NET patients and 16 controls. RESULTS: Only the plasma concentrations of Tie-2 and CgA were higher in NET patients as compared to controls. These levels were within the reference range in controls; however one control demonstrated slightly elevated Tie-2 and 4 elevated CgA. Similarly, in the subgroup of patients with carcinoid syndrome, only Tie-2 and CgA concentrations were higher than those in patients with non-functioning NETs. In turn, in the subgroup of metastatic patients, only Ang-2 levels were higher than in those with localized disease. A positive correlation was found between Ang-2 and Tie-2 levels in metastatic patients and between Ang-1 and Tie-2 in localized NETs. CONCLUSIONS: The plasma concentration of Tie-2 is proposed as an additional marker for NET patients and seems to be similarly effective as the currently used CgA level. Moreover, higher plasma levels of Ang-2 together with the positive correlation between Ang-2 and Tie-2 levels in metastatic subjects, implies that cases with a Tie-2 level above the upper limits, together with higher level of Ang-2 seem to be highly predictive of metastases.