A panel of selected serum protein biomarkers for the detection of aggressive prostate cancer

Background: Current PSA-based tests used to detect prostate cancer (PCa) lack sufficient specificity, leading to significant overdetection and overtreatment. Our previous studies showed that serum fucosylated PSA (Fuc-PSA) and soluble TEK receptor tyrosine kinase (Tie-2) had the ability to predict aggressive (AG) PCa. Additional biomarkers are needed to address this significant clinical problem. Methods: A comprehensive Pubmed search followed by multiplex immunoassays identified candidate biomarkers associated with AG PCa. Subsequently, multiplex and lectin-based immunoassays were applied to a case-control set of sera from subjects with AG PCa, low risk PCa, and non-PCa (biopsy negative). These candidate biomarkers were further evaluated for their ability as panels to complement the prostate health index (phi) in detecting AG PCa. Results: When combined through logistic regression, two panel of biomarkers achieved the best performance: 1) phi, Fuc-PSA, SDC1, and GDF-15 for the detection of AG from low risk PCa and 2) phi, Fuc-PSA, SDC1, and Tie-2 for the detection of AG from low risk PCa and non-PCa, with noticeable improvements in ROC analysis over phi alone (AUCs: 0.942 vs 0.872, and 0.934 vs 0.898, respectively). At a fixed sensitivity of 95%, the panels improved specificity with statistical significance in detecting AG from low risk PCa (76.0% vs 56%, p=0.029), and from low risk PCa and non-PCa (78.2% vs 65.5%, p=0.010). Conclusions: Multivariate panels of serum biomarkers identified in this study demonstrated clinically meaningful improvement over the performance of phi, and warrant further clinical validation, which may contribute to the management of PCa.

Effects of Negative Pressure Wound Therapy on Levels of Angiopoetin-2 and Other Selected Circulating Signaling Molecules in Patients with Diabetic Foot Ulcer

BACKGROUND AND AIMS

Diabetic foot ulcers (DFUs) are linked to amputations and premature deaths. Negative pressure wound therapy (NPWT) has been used for DFUs. The mechanism of NPWT's action may be associated with its influence on circulating molecules. We assessed NPWT's effect on the plasma levels of angiopoietin-2 (Ang2), a key regulator of angiogenesis, and its microvesicular receptors (Tie2) as well as the microvesicles (MVs) themselves in DFU patients.

MATERIALS AND METHODS

We included 69 patients with type 2 diabetes mellitus (T2DM) and neuropathic, noninfected DFUs-49 were treated with NPWT and 20 were treated with standard therapy (ST). Assigning patients to the NPWT group was not random but based on DFU characteristics, especially wound area. Ang2 was measured by ELISA in the entire group, while in a subgroup of 19 individuals on NPWT and 10 on ST, flow cytometry was used to measure Tie2+ and the corresponding isotype control (Iso+) and annexin V (AnnV+) as well as total MVs. Measurements were performed at the beginning and after 8 ± 1 days of therapy.

RESULTS

Treatment groups were similar for basic characteristics but differed by their median DFU areas (10.3 (4.2-18.9) vs. 1.3 (0.9-3.4) cm², p = 0.0001). At day 0, no difference was observed in Ang2 levels, total MVs, MV Tie+, and MV AnnV+ between the groups. Ang2 decreased after 8 days in the NPWT group, unlike in the ST group (3.54 (2.40-5.40) vs. 3.32 (2.33-4.61), p = 0.02, and 3.19 ± 1.11 vs. 3.19 ± 1.29 ng/mL, p = 0.98, respectively). No other parameters were identified that may have been influenced by the NPWT treatment.

CONCLUSION

NPWT in T2DM patients with neuropathic, noninfected DFU seems to lead to reduction of the Ang2 level. Influencing the level of Ang2 may constitute one of NPWT-related mechanisms to accelerate wound healing.

Plasma Tie2 is a tumor vascular response biomarker for VEGF inhibitors in metastatic colorectal cancer

Oncological use of anti-angiogenic VEGF inhibitors has been limited by the lack of informative biomarkers. Previously we reported circulating Tie2 as a vascular response biomarker for bevacizumab-treated ovarian cancer patients. Using advanced MRI and circulating biomarkers we have extended these findings in metastatic colorectal cancer (n = 70). Bevacizumab (10 mg/kg) was administered to elicit a biomarker response, followed by FOLFOX6-bevacizumab until disease progression. Bevacizumab induced a correlation between Tie2 and the tumor vascular imaging biomarker, Ktrans (R:-0.21 to 0.47) implying that Tie2 originated from the tumor vasculature. Tie2 trajectories were independently associated with pre-treatment tumor vascular characteristics, tumor response, progression free survival (HR for progression = 3.01, p = 0.00014; median PFS 248 vs. 348 days p = 0.0008) and the modeling of progressive disease (p < 0.0001), suggesting that Tie2 should be monitored clinically to optimize VEGF inhibitor use. A vascular response is defined as a 30% reduction in Tie2; vascular progression as a 40% increase in Tie2 above the nadir. Tie2 is the first, validated, tumor vascular response biomarker for VEGFi.

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.

Plasma markers of angiogenesis in pregnancy induced hypertension

This study tests the hypothesis that abnormalities in plasma indices of angiogenesis, such as Vascular Endothelial Growth Factor (VEGF) and angiopoietins (Ang-1, Ang-2), as well as their soluble receptors Flt-1 (sflt-1) and Tie 2 (sTie-2) respectively, are present in women with in pregnancy-induced hypertension (PIH). We also measured platelet levels of VEGF and Ang-1 (pVEGF and pAng-1 respectively). We studied 69 consecutive women with PIH (34 without proteinuria, and 35 with proteinuria, i.e. preeclampsia) who were compared to 64 consecutive women with normotensive pregnancies and 30 normotensive non-pregnant women, in a cross-sectional study. Using ELISA, we measured levels of plasma VEGF, Ang-1 &2, Tie-2 and sflt-1, and also the levels of angiogenic markers within the platelet [platelet VEGF (pVEGF) and platelet Ang-1 (pAng1)] by lysing a fixed number of platelets with 0.5% tween. Results show that levels of plasma VEGF, Ang-1, Ang2, sFlt-1 and Tie-2 were significantly different between the study groups. Post hoc analyses revealed plasma Ang-1 was highest in the preeclampsia group (p<0.001), whilst Ang-2 was highest in the normotensive pregnant group (p-=0.018). Plasma Tie-2 was highest in the PIH group. VEGF levels were significantly different between the preeclampsia group and the PIH group (p<0.05). Platelet VEGF levels were higher in the non-pregnant group than in the pregnant group, but there were no significant differences in the platelet levels of Ang-1 between the different groups. Ang-2, sFlt-1 and Tie-2 were undetectable in the platelet lysate in any of the patient groups or controls. Blood pressure was a major determinant of the different angiogenic factors studied. Abnormal indices of angiogenesis are evident in PIH and preeclampsia, with higher levels of sFlt-1 and lower levels ofVEGF; in PIH, increased levels of Ang-1 and Tie-2, but reduced Ang-2, are evident compared to normal pregnancy. These abnormalities may have implications for the pathogenesis of PIH and preeclampsia.

Angiopoietin-2 and soluble Tie-2 receptor plasma levels in children with obstructive sleep apnea and obesity

OBJECTIVE

Obstructive sleep apnea (OSA) is a prevalent condition, especially in children with obesity, and is associated with increased risk for metabolic syndrome (MetS). Angiopoietins have been identified as potential biomarkers of endothelial dysfunction and MetS. In adults, angiopoietin-2 (Ang-2) and its soluble receptor (sTie-2) are associated with diabetes, hypertension, and obesity and could be increased in children with OSA and obesity, particularly those with evidence of cardiometabolic alterations.

METHODS

One hundred twenty-six children (7.4 ± 2.0 years) were consecutively recruited and underwent overnight polysomnography, as well as endothelial function and BMI z score assessments and a fasting blood draw the morning after the sleep study. In addition to lipid profile, glucose and insulin levels, and homeostatic model assessment of insulin resistance (HOMA-IR), Ang-2 and sTie-2 concentrations were determined.

RESULTS

Children with obesity and OSA had significantly elevated plasma Ang-2 and sTie-2 levels compared to corresponding controls with and without obesity. Furthermore, endothelial function (Tmax) and HOMA-IR were linearly and independently associated with Ang-2 and sTie-2 levels. In a small subset of children (n = 14), treatment of OSA by adenotonsillectomy resulted in reductions of Ang-2 and sTie-2 (P < 0.01).

CONCLUSIONS

Ang-2 and sTie-2 plasma levels are increased in pediatric OSA and obesity, particularly when endothelial dysfunction or insulin resistance is detectable, and appear to decrease upon OSA treatment.

Circulating Angiopoietin-2 and Its Soluble Receptor Tie-2 Concentrations Are Related to Renal Function in Two Population-Based Cohorts

Background

An intact angiopoietin/Tie-2 ligand receptor system is indispensable for life. High circulating angiopoietin-2 (Ang-2) concentrations are strongly associated with kidney disease involving the progressive loss of glomerular filtration. The aim of our study was to investigate the associations between renal function and serum Ang-2 or serum Tie-2 concentrations in the general population.

Methods

Data of 3081 and 4088 subjects from two population-based studies, the Study of Health in Pomerania (SHIP-1) and SHIP-Trend, were used. Renal function was assessed by serum creatinine, cystatin C concentration, creatinine-based estimated glomerular filtration rate [eGFR(crea)], cystatin C-based eGFR [eGFR(cys)] and urinary albumin-to-creatinine ratio (uACR). Analyses of variance and linear regression models were calculated.

Results

In both cohorts, strong positive associations between serum cystatin C concentrations and serum Ang-2 or Tie-2 concentrations as well as inverse associations between eGFR(cys) and serum Ang-2 or Tie-2 concentrations were found. These relations were also present in a subpopulation without hypertension or diabetes mellitus type 2. Furthermore, we detected weak U-shaped associations between serum creatinine concentrations or eGFR(crea) and serum Ang-2 concentrations. With respect to uACR a strong positive association with serum Ang-2 concentrations was revealed.

Conclusion

Serum Ang-2 concentrations are strongly associated with sensitive parameters of renal impairment like serum cystatin C, uACR and eGFR(cys). These findings persisted even after exclusion of subjects with hypertension or diabetes mellitus type 2, conditions that predispose to chronic renal disease and are associated with increased Ang-2 concentrations. Interestingly, we did not detect the same strong relations between serum creatinine and eGFR(crea) with serum Ang-2 concentration. Additionally, significant association of serum Tie-2 concentrations with cystatin C and eGFR(cys) were detected.

Angiopoietin-2, its soluble receptor Tie-2, and metabolic syndrome components in a population-based sample

OBJECTIVE

Since angiopoietin-2 (Ang-2) levels strongly correlate with cardiovascular mortality and subclinical cardiovascular disease, it was hypothesized that levels of Ang-2 and its soluble receptor (sTie-2) were associated with the metabolic syndrome (MetS) and individual MetS components.

METHODS

Within the population-based Study of Health in Pomerania, two sets of analyses were performed. First, Ang-2 and sTie-2 were related to the prevalence of MetS and its components cross-sectionally (n = 3,205). Second, the association between baseline Ang-2 and sTie-2 and incident MetS or longitudinal changes in its components in 1,295 individuals was investigated.

RESULTS

High Ang-2 levels (90th percentile), compared with low Ang-2 levels (10th percentile), were positively associated with MetS (OR: 1.78) and with the following MetS criteria: increased triglycerides, lower HDL cholesterol, and higher non-fasting glucose. Furthermore, high sTie-2 levels (90th percentile), compared with low levels (10th percentile), were positively related to MetS (OR: 1.58) and most of its components. However, Ang-2 and sTie-2 levels were not associated with incident MetS or longitudinal change in components of MetS.

CONCLUSIONS

Ang-2 and sTie-2 levels were cross-sectionally associated with MetS and several of its components. However, Ang-2 and sTie-2 levels were not associated with incident MetS or changes in individual MetS components during follow-up.

Biomarkers of Host Response Predict Primary End-Point Radiological Pneumonia in Tanzanian Children with Clinical Pneumonia: A Prospective Cohort Study

Background

Diagnosing pediatric pneumonia is challenging in low-resource settings. The World Health Organization (WHO) has defined primary end-point radiological pneumonia for use in epidemiological and vaccine studies. However, radiography requires expertise and is often inaccessible. We hypothesized that plasma biomarkers of inflammation and endothelial activation may be useful surrogates for end-point pneumonia, and may provide insight into its biological significance.

Methods

We studied children with WHO-defined clinical pneumonia (n = 155) within a prospective cohort of 1,005 consecutive febrile children presenting to Tanzanian outpatient clinics. Based on x-ray findings, participants were categorized as primary end-point pneumonia (n = 30), other infiltrates (n = 31), or normal chest x-ray (n = 94). Plasma levels of 7 host response biomarkers at presentation were measured by ELISA. Associations between biomarker levels and radiological findings were assessed by Kruskal-Wallis test and multivariable logistic regression. Biomarker ability to predict radiological findings was evaluated using receiver operating characteristic curve analysis and Classification and Regression Tree analysis.

Results

Compared to children with normal x-ray, children with end-point pneumonia had significantly higher C-reactive protein, procalcitonin and Chitinase 3-like-1, while those with other infiltrates had elevated procalcitonin and von Willebrand Factor and decreased soluble Tie-2 and endoglin. Clinical variables were not predictive of radiological findings. Classification and Regression Tree analysis generated multi-marker models with improved performance over single markers for discriminating between groups. A model based on C-reactive protein and Chitinase 3-like-1 discriminated between end-point pneumonia and non-end-point pneumonia with 93.3% sensitivity (95% confidence interval 76.5–98.8), 80.8% specificity (72.6–87.1), positive likelihood ratio 4.9 (3.4–7.1), negative likelihood ratio 0.083 (0.022–0.32), and misclassification rate 0.20 (standard error 0.038).

Conclusions

In Tanzanian children with WHO-defined clinical pneumonia, combinations of host biomarkers distinguished between end-point pneumonia, other infiltrates, and normal chest x-ray, whereas clinical variables did not. These findings generate pathophysiological hypotheses and may have potential research and clinical utility.

Circulating angiopopietin-1 correlates with the clinical course of multiple organ dysfunction syndrome and mortality in patients with severe sepsis

To determine plasma concentrations of angiopoietin (Ang)-1, Ang-2, Tie-2, and vascular endothelial growth factor (VEGF) in patients with sepsis-induced multiple organ dysfunction syndrome (MODS) and determine their association with mortality.The study prospectively recruited 96 consecutive patients with severe sepsis in a l intensive care unit of a tertiary hospital. Plasma Ang-1, Ang-2, Tie-2, and VEGF levels and MODS were determined in patients on days 1, 3, and 7 of sepsis. Univariate and Cox proportional hazards analysis were performed to develop a prognostic model.Days 1, 3, and 7 plasma Ang-1 concentrations were persistently decreased in MODS patients than in non-MODS patients (day1: 4.0 ± 0.5 vs 8.0 ± 0.5 ng/mL, P < 0.0001; day 3, 3.2 ± 0.6 vs 7.3 ± 0.5 ng/mL, P < 0.0001, day 7, 2.8 ± 0.6 vs 10.4 ± 0.7 ng/mL, P < 0.0001). In patients with resolved MODS on day 7 of sepsis, Ang-1 levels were increased from day 1 (4.7 ± 0.6 ng/mL vs 9.1 ± 1.4 ng/mL, n = 43, P = 0.004). Plasma Ang-1 levels were lower in nonsurvivors than in survivors on days 1 (4.0 ± 0.5 vs 7.1 ± 0.5 ng/mL, P < 0.0001), 3 (3.8 ± 0.6 vs 7.1 ± 0.5 ng/mL, P < 0.0001), and 7 (4.7 ± 0.7 vs 11.0 ± 0.8 ng/mL, P < 0.0001) of severe sepsis. In contrast, plasma Ang-2 levels were higher in nonsurvivors than in survivors only on day 1 (15.8 ± 2.0 vs 9.5 ± 1.2 ng/mL, P = 0.035). VEGF and Tie-2 levels were not associated with MODS and mortality. Ang-1 level less than the median value was the only independent predictor of mortality (hazard ratio, 2.57; 95% CI 1.12-5.90, P = 0.025).Persistently decreased Ang-1 levels are associated with MODS and subsequently, mortality in patients with sepsis.

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.

Circulating angiostatin, bFGF, and Tie2/TEK levels and their prognostic impact in bladder cancer

OBJECTIVE

To assess the role and prognostic significance of angiostatin, basic fibroblast growth factor (bFGF), and tyrosine endothelial kinase (TEK/Tie2) in transitional cell bladder carcinoma.

MATERIALS AND METHODS

Angiostatin, bFGF, and TEK serum concentrations were measured in 82 bladder cancer patients and 20 age-matched healthy controls using enzyme-linked immunosorbent assay. Results were compared with clinicopathologic and follow-up data with the Mann-Whitney U test and Kaplan-Meier, univariate and multivariate Cox regression analyses.

RESULTS

We found significantly decreased angiostatin and TEK serum levels and mildly elevated bFGF concentrations in samples of bladder cancer patients compared with controls (P < .001, P < .001, and P = .083, respectively). Furthermore, high TEK serum levels were correlated with poor disease-specific and metastasis-free survival in muscle-invasive bladder cancer (P = .013, P = .018), whereas angiostatin and bFGF concentrations did not show any correlation with patients' prognosis. Multivariate analysis revealed high TEK levels (<1.60 ng/mL) as borderline significant independent risk-factor of disease-specific survival (HR 1.83, 95% CI 0.97-3.44, P = .061) and metastasis-free survival (HR 2.65, 95% CI 0.93-7.55, P = .069).

CONCLUSION

The characteristic differences in the circulating levels of angiostatin, TEK, and bFGF between patients and controls, suggest the presence of a tumor-induced proangiogenic milieu in bladder cancer. Serum TEK levels may contribute to a more reliable preoperative risk stratification in muscle-invasive bladder cancer and therefore may help to optimize therapeutic decisions.

Relation of vascular growth factors with CT-derived measures of body fat distribution: the Framingham Heart Study

BACKGROUND

Visceral adiposity is associated with metabolic risk. Given that angiogenesis is a key feature of adipogenesis, variation in the association of levels of circulating vascular growth factors (and their soluble receptors) with distinct body fat compartments may explain differences in the systemic pathogenicity of regional fat depots.

METHODS AND RESULTS

Four body fat compartments [visceral adipose tissue (VAT), sc adipose tissue (SAT), thoracic periaortic fat, and pericardial fat] derived from computed tomography were related to serum concentrations of vascular endothelial growth factor (VEGF), the soluble VEGF receptor (fms-like tyrosine kinase-1), hepatocyte growth factor (HGF), and angiopoietin-2 and its soluble receptor (soluble tyrosine kinase with immunoglobulin-like and EGF-like domains 2 sTie-2) in 1806 Framingham Heart Study participants (mean age 44.9 yr, 44.5% women). In multivariable models, we observed positive associations between several fat compartments and VEGF and HGF levels. The magnitude of the associations were similar for VAT, SAT, and periaortic fat. We observed effect modification by sex. A stronger association was observed between VAT and HGF levels in women; higher VAT and periaortic fat were jointly associated with higher HGF concentrations (P=0.02 and P=0.051, respectively). In women within the highest tertile of VAT, HGF levels significantly increased with higher periaortic fat (P=0.0005).

CONCLUSIONS

In our large community-based sample, greater adiposity was associated with higher circulating growth factor levels in general. Additional studies are warranted to confirm the stronger association of VAT and periaortic fat with HGF in women and to examine its potential contribution to the sex-related differences in cardiometabolic risk.

Influence of surgical resection on plasma endoglin (CD105) level in non‑small cell lung cancer patients

BACKGROUND AND AIM

Endoglin is a proliferation-associated antigen on endothelial cells and essential for angiogenesis. Soluble endoglin (s‑endoglin), formed by proteolytic cleavage of ectodomain of membrane receptor could be an indicator of tumor‑activated endothelium. The aim of present study was to analyze changes of s‑endoglin level in plasma of lung cancer patients following surgical resection and to estimate the correlation of s‑endoglin with other soluble receptors, sTie2 and sVEGF R1.

PATIENTS AND METHODS

The study group consisted of 37 patients with stage I of non-small cell lung cancer. Plasma concentrations of s‑endoglin, sTie2 and sVEGF R1 were evaluated by ELISA, three times: before surgical resection and on postoperative day 7 and 30.

RESULTS

The median of s‑endoglin concentration decreased significantly on postoperative day 7 when compared with preoperative level and next increased on 30(th) day and it was comparable with that before surgery. s-Endoglin correlated with another soluble receptors, with sTie2 both before surgery (r=0.44) and on postoperative day 7 (r=0.52) and on 30(th) day (r=0.58), with sVEGF R1 - only on postoperative day 7 (r=0.75).

CONCLUSION

The increased level of serum endoglin in lung cancer patients compared to controls and its changes after surgical treatment suggest potential application of soluble form of endoglin as potential tumor marker.

Decreased circulating soluble Tie2 levels in preeclampsia may result from inhibition of vascular endothelial growth factor (VEGF) signaling

OBJECTIVES

Recent studies have found dysregulation in circulating levels of a number of angiogenic factors and their soluble receptors in preeclampsia. In this study, we examined the mechanism of production of soluble Tie2 (sTie2) and its potential connection to the failure of vascular remodeling in preeclamptic pregnancies.

DESIGN/SETTING/PATIENTS

Serum samples were collected prospectively from 41 pregnant subjects at five different time points throughout pregnancy. Five of these subjects developed preeclampsia. For a second study, serum and placental samples were collected at delivery from preeclamptic and gestational age-matched controls. We examined serum sTie2 levels, and angiopoietin 1, angiopoietin 2, and Tie2 mRNA expression and localization in placental samples from the central basal plate area. We also examined the effects of vascular endothelial growth factor (VEGF) and a matrix metalloproteinase (MMP) inhibitor on proteolytic shedding of Tie2 in uterine microvascular endothelial cells.

RESULTS

Serum sTie2 levels were significantly lower in preeclamptic subjects starting at 24-28 wk of gestation and continued to be lower through the time of delivery. In culture experiments, VEGF treatment significantly increased sTie2 levels in conditioned media, whereas the MMP inhibitor completely blocked this increase, suggesting that VEGF-induced Tie2 release is MMP dependent.

CONCLUSIONS

Our data suggest, for the first time, an interaction between VEGF and Tie2 in uterine endothelial cells and a potential mechanism for the decrease in circulating sTie2 levels in preeclampsia, likely through inhibition of VEGF signaling. Further studies on VEGF-Tie2 interactions during pregnancy should provide new insights into the mechanisms underlying the failure of vascular remodeling in preeclampsia and other pregnancy complications.

[Correlation of angiopoietin-2 and angiopoietin-2 receptor expressions in serum and placenta with preeclampsia]

OBJECTIVE

To investigate the correlation of the expressions of angiopoietin-2 (Ang-2) and angiopoietin-2 receptor (Tie-2) in serum and placenta with preeclampsia.

METHODS

From May 2009 to April 2010, 62 women with preeclampsia who delivered in Affiliated Hospital of Qingdao University Medical College were recruited in the study, including 30 women with moderate preeclampsia (MPE group) and 32 women with severe preeclampsia (SPE group). Another 30 healthy pregnant women were taken as control group. ELISA was used to measure the serum Ang-2 in these women. Semiquantitative reverse transcription (RT)-PCR was used to investigate the expressions of Ang-2 mRNA and Tie-2 mRNA in placenta. Western blot was used to determine the expression of Ang-2 protein in placenta.

RESULTS

(1) The serum concentrations of Ang-2 in MPE group and SPE group were (5.4 ± 1.8) µg/L and (5.1 ± 1.7) µg/L, respectively. Both were significantly lower than that in control group (16.2 ± 4.5) µg/L (P < 0.01). There was no significant difference between MPE group and SPE group (P > 0.05). (2) The expressions of Ang-2 mRNA in placenta of MPE group (2.1 ± 0.7) and SPE group (2.0 ± 0.6) were both significantly lower than that of control group (5.8 ± 0.8; P < 0.01). But there was no significant difference in Ang-2 mRNA expression between MPE group and SPE group (P > 0.05). (3) No significant difference was found in the expressions of Tie-2 mRNA in placenta among MPE group (1.33 ± 0.04), SPE group (1.35 ± 0.05) and control group (1.34 ± 0.04; P > 0.05). (4) The expressions of Ang-2 protein in placenta of MPE group (2.0 ± 0.8) and SPE group (2.0 ± 0.8) were both significantly lower than that of control group (5.7 ± 0.9; P < 0.01), while no significant difference was found between MPE group and SPE group (P > 0.05). (5) In MPE group and SPE group, the serum concentrations of Ang-2 were positively correlated with the levels of Ang-2 mRNA and Ang-2 protein in placenta (r = 0.651, 0.627; P < 0.01).

CONCLUSIONS

Decreased expressions of Ang-2 mRNA and Ang-2 protein in placenta reduced serum concentration of Ang-2. Low expression of Ang-2 may be involved in the pathophysiological process of preeclampsia by affecting the formation of placenta in early pregnancy.

The association of the angiopoietin/Tie-2 system with the development of metastasis and leukocyte migration in neuroendocrine tumors

The aim of this study was to explore the possible involvement of the angiopoietin (Ang)-1, -2/Tie-2 system in the development, growth, and metastases evolution of gastroenteropancreatic-neuroendocrine tumors (GEP-NETs). We prospectively examined the serum levels of Tie-2, Ang-1, and Ang-2 by ELISA in 42 patients with proven GEP-NETs and 27 controls. We also determined the expression of the Ang/Tie-2 system in freshly isolated peripheral blood monocytes and in tumor cells from malignant primary tumors and/or liver metastases samples from GEP-NET patients by flow cytometry and/or RT-PCR. Furthermore, the function of the Ang/Tie-2 system in monocytes from controls and patients was assessed by a chemotaxis assay. GEP-NET patients showed enhanced serum levels of soluble form of Tie-2 (sTie-2), Ang-1, and Ang-2 (P<0.05 in all cases), compared to controls. sTie-2 and Ang-2 levels were significantly higher in GEP-NETs with metastases compared to those with no metastases. In addition, a significant correlation was detected between Ang-2 levels and chromogranin A or sTie-2 concentrations or 5-hydroxy-indole acetic acid excretion (r=0.71, r=0.60, and r=0.81 respectively, P<0.01 in all cases). Furthermore, we observed an enhanced expression of Ang-1, Ang-2, and Tie-2 in freshly isolated tumor cells from GEP-NET both by immunohistochemistry and by RT-PCR. Interestingly, an enhanced expression and function of Tie-2 was detected in monocytes from GEP-NET patients. Our data suggest that the Ang/Tie-2 system is involved in the growth and development of metastases of GEP-NETs, and that favors the recruitment of Tie-2(+) monocytes to the tumor site, where they can promote inflammation and angiogenesis.

[Study on Tie2 mRNA level in peripheral blood associated with the severity of sepsis]

OBJECTIVE

To investigate the possibility that the level of Tie2 mRNA in peripheral blood could reflect the severity of sepsis.

METHODS

Trauma patients in intensive care unit (ICU) were recruited, and they were divided into sepsis group (n=13) and non-sepsis group (n=19). The severity of disease was evaluated with acute physiology and chronic health evaluation II (APACHEII) score on the day of ICU admission. Blood of patients was sampled on day 1, 3, 7 after ICU admission to determination of the white blood cell (WBC) count, contents of alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN) and creatinine (Cr), mRNA levels of Tie2 in blood measured by quantitative real-time polymerase chain reaction (PCR), and the contents of plasma von Willebrand factor (vWF) with enzyme linked immunosorbent assay (ELISA).

RESULTS

No significant difference in contents of ALT, AST and plasma vWF was found between sepsis group and non-sepsis group [ALT (U/L): 53.30 (199.58) vs. 80.65 (202.62), AST (U/L): 316.53 (49.90) vs. 66.10 (285.03), vWF: (272.47+/-114.61)% vs. (246.66+/-128.77)%, all P>0.05]. The number of WBC [x10(9)/L, 18.26 (21.82) vs. 10.11 (4.72)], the contents of BUN [mmol/L, 20.70 (11.20) vs. 7.70 (5.45)] and Cr [micromol/L: 252.00 (364.55) vs. 68.00(23.20)], and the circulating mRNA levels of Tie2 (1.86+/-0.67 vs. 0.91+/-0.42) in sepsis group were higher than those in the non-sepsis group (all P<0.01). The Tie2 mRNA level in peripheral blood of each patient was positively correlated with APACHEII score (r=0.532, P<0.01). The linear regression equation was Y=12.66+4.922 X (R2=0.283). Besides, there was a significant correlation between the amount of Tie2 mRNA and plasma levels of vWF (r=0.334, P<0.05). The linear regression equation was Y=180.932+57.93 X (R2=0.112).

CONCLUSION

The level of Tie2 mRNA in peripheral blood could reflect the damage of endothelial cell and severity of sepsis.

Maternal serum angiopoietin-1 and -2 and tie-2 in early pregnancy ending in preeclampsia or intrauterine growth retardation

CONTEXT

The antiangiogenic growth factor angiopoietin-2 (Ang-2) antagonizes, whereas angiopoietin-1 (Ang-1) activates the endothelial cell-specific tyrosine kinase receptor-2 (Tie-2). In preeclampsia, circulating concentrations of Ang-1 are increased and those of Ang-2 and Tie-2 are decreased.

OBJECTIVE

We wanted to study whether maternal serum concentrations of Ang-1, Ang-2, and Tie-2 are altered at gestational wk 12-15 or 16-20 in women with subsequent preeclampsia or intrauterine growth retardation (IUGR).

DESIGN

This was a case-control study.

SETTING

The study was conducted in Helsinki University Central Hospital, a tertiary referral center.

PATIENTS

This study comprised 124 pregnant women, of whom 49 developed preeclampsia and 16 gave birth to infants with IUGR, and 59 healthy women served as controls.

MAIN OUTCOME MEASURES

Serum concentrations of Ang-1, Ang-2, and Tie-2 were assessed by ELISA. Data were combined with our earlier data on soluble VEGF receptor (sVEGFR)-1.

RESULTS

At gestational wk 12-15, the median concentrations of Ang-1, Ang-2, or Tie-2 were all similar between the study groups. At 16-20 wk, Ang-2 concentrations were higher in women with subsequent preeclampsia [25.0 ng/ml, 19.3-39.5 ng/ml; median, interquartile range (IQR)] than in the controls (17.7 ng/ml, 10.8-27.4 ng/ml, P = 0.006). The odds ratio of high Ang-2 concentrations for subsequent preeclampsia was 4.2 (95% confidence interval 1.4-12.6; P = 0.011) and high Ang-2 combined with high sVEGFR-1, 6.4 (95% confidence interval 2.2-18.7; P = 0.001).

CONCLUSION

Maternal serum Ang-2 concentrations are increased prior to preeclampsia. High concentrations of both Ang-2 and sVEGFR-1 indicate subsequent disease.

Serum levels of angiogenic molecules in autoimmune thyroid diseases and their correlation with laboratory and clinical features

CONTEXT

Because angiogenesis has a role in the pathogenesis of inflammatory conditions, we studied angiogenesis soluble markers in autoimmune thyroid diseases.

OBJECTIVE

The aim of the study was to measure concentrations of angiopoietins, Tie-2, and vascular endothelial growth factor in sera from autoimmune thyroid disease patients.

DESIGN

Soluble Tie-2 (sTie-2), angiopoietin-1, angiopoietin-2, and vascular endothelial growth factor were quantified by ELISA in sera from 44 untreated Graves' disease (GD) patients, 25 untreated Hashimoto's thyroiditis (HT) patients, 13 non-GD hyperthyroid patients, and 22 age-matched controls. Subgroups of patients with active and non-active Graves' ophthalmopathy (GO) were analyzed. Correlations among these markers and clinical parameters were assessed by bivariate and multivariate analyses.

RESULTS

STIE-2 levels were higher in GD or HT patients compared to controls (P < 0.01). In addition, serum Ang-2 concentrations were higher in untreated GD patients compared to controls, HT patients, or non-GD hyperthyroid patients (P < 0.01), and no difference was observed between HT patients and controls. Significant correlations were found between free T(4)/sTie-2 and free T(4)/Ang-2 levels (r = 0.464, P < 0.01; and r = 0.463, P < 0.01, respectively) as well as between sTie-2/anti-TSH receptor antibody (r = 0.527; P < 0.01) and sTie-2/Ang-2 (r = 0.563; P = 0.001). Furthermore, sTie-2 levels were significantly higher in patients with active GO when compared to those with inactive GO (P < 0.05). Interestingly, Ang-2 levels decreased significantly after treatment with antithyroid drugs (P < 0.01).

CONCLUSIONS

Ang-2 and sTie-2 could participate in the pathogenesis of GD and potentially be used as markers of GO activity. Antithyroid drugs affect the angiogenic pattern in GD.

Plasma concentration of angiopoietin-1, angiopoietin-2 and Tie-2 in cervical cancer

PURPOSE OF INVESTIGATION

Angiogenesis is important in the promotion and progression of malignancy. The formation of new blood vessels is coordinated by many factors, angiopoietins among others. Overexpression of angiopoietins has been observed in various tumors. The aim of the study was to evaluate plasma concentration of Ang-1, Ang-2 and Tie-2 in cervical cancer.

METHODS

The study group consisted of 34 patients with cervical cancer and the control group of 20 healthy volunteers. Plasma concentrations of Ang-1, Ang-2 and Tie-2 were evaluated by ELISA.

RESULTS

Plasma concentrations of Ang-1, Ang-2, Tie-2 and Ang-1/Ang-2 ratios were significantly higher in cervical cancer patients than in controls. Although there was no correlation between concentration of Ang-1, Ang-2, Tie-2 and clinical stage (FIGO), the Ang-1/Ang-2 ratio was higher in Stage I than in II-III. Ang-1 correlated positively with Ang-2 and Tie-2 in a subgroup with Stage II-III and Ang-2 with Tie-2 in a subgroup with Stage I.

CONCLUSION

Plasma concentrations of Ang- 1, Ang-2 and Tie-2 may be useful additional tumor markers in cervical cancer.

Angiogenic molecule Tie-2 and VEGF in the pathogenesis of pleural effusions

BACKGROUND

The role of angiogenesis in the pathogenesis of pleural effusion (PE) has not been determined. The expression of angiogenic factors may represent useful markers for the diagnosis and prediction of disease outcome. To measure the pleural fluid (PF) and serum levels of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and Tie receptor tyrosine kinase (Tie-2) in order to investigate their role in the pathogenesis of PEs.

METHODS

Sixty-seven, 17 with transudative PEs due to heart failure and 50 with exudative PEs (malignant, 22; inflammatory, 15; undiagnosed, 13) were included in the study. PF and serum levels of the growth factors (VEGF, bFGF and Tie-2) were measured using enzyme-linked immunosorbent assays.

RESULTS

PF and serum VEGF levels but not bFGF and Tie-2 levels were higher (p<0.005) in exudates than in transudates. PF VEGF levels were significantly higher in malignant than inflammatory and undiagnosed PEs (p=0.03). In addition, PF Tie-2 levels were not found different in malignant or in parapneumonic PEs.

CONCLUSION

Our results showed that VEGF is one of the main mediators in exudative PEs, but this effect is not mediated through the angiogenetic pathway Ang-1/Tie-2. However, the role of angiogenesis and its pathways in the pathogenesis of exudative PEs needs further exploration.

Role of vascular endothelial growth factor and angiopoietin systems in serum of Crohn's disease patients

BACKGROUND

The purposes of this study were to determine soluble angiogenic factors in Crohn's disease (CD) patients and to compare these factors according to the pathological behavior of the disease in order to establish a possible relationship with its evolution in patients with CD.

METHODS

Blood samples were collected from 70 patients with CD, grouped according to their phenotypic behavior, and from 30 healthy controls. Vascular endothelial growth factor (VEGF), placental growth factor (PlGF), angiopoietin 1 (Ang1), angiopoietin 2 (Ang2), and their cognate receptors [VEGFR1, VEGFR2, and angiopoietin receptor tyrosine kinase (Tie2)] were assayed by ELISA.

RESULTS

Circulating levels of VEGF, PlGF, VEGFR1, Ang2, and Tie2 were significantly higher in CD patients than in healthy controls (489 +/- 271 versus 335 +/- 118 pg/mL, P < 0.001; 31 +/- 9 versus 23 +/- 9 pg/mL, P < 0.001; 1.7 +/- 0.4 versus 1.0 +/- 0.3 ng/mL, P < 0.001; 4.8 +/- 2.0 versus 3.9 +/- 2.0 ng/mL, P < 0.05; and 36 +/- 5 versus 22 +/- 7 ng/mL, P < 0.001, respectively). Conversely, CD patients showed significantly lower serum levels of Ang1 than healthy controls (40 +/- 12 versus 67 +/- 22 ng/mL; P < 0.001). No differences between the groups were found in VEGFR2 serum level. The circulating levels of the angiogenic factors did not differ significantly when the CD patients were classified according to pathological phenotype.

CONCLUSIONS

In comparison with healthy controls, CD patients were found to have an active angiogenic profile, as detected by significant alterations in levels of angiogenesis soluble markers. These patients did not differ in serum levels of angiogenic factors according to phenotypic disease behavior.

VEGF induces Tie2 shedding via a phosphoinositide 3-kinase/Akt dependent pathway to modulate Tie2 signaling

OBJECTIVE

Tie2 and its ligands, the angiopoietins (Ang), are required for embryonic and postnatal angiogenesis. Previous studies have demonstrated that Tie2 is proteolytically cleaved, resulting in the production of a 75-kDa soluble receptor fragment (sTie2). We investigated mechanisms responsible for Tie2 shedding and its effects on Tie2 signaling and endothelial cellular responses.

METHODS AND RESULTS

sTie2 bound both Ang1 and Ang2 and inhibited angiopoietin-mediated Tie2 phosphorylation and antiapoptosis. In human umbilical vein endothelial cells, Tie2 shedding was both constitutive and induced by treatment with PMA or vascular endothelial growth factor (VEGF). Constitutive and VEGF-inducible Tie2 shedding were mediated by PI3K/Akt and p38 MAPK. Tie2 shedding was blocked by pharmacological inhibitors of either PI3K or Akt as well as by overexpression of the lipid phosphatase PTEN. In contrast, sTie2 shedding was enhanced by overexpression of either dominant negative PTEN, which increased Akt phosphorylation, or constitutively active, myristoylated Akt.

CONCLUSIONS

These findings demonstrate that VEGF regulates angiopoietin-Tie2 signaling by inducing proteolytic cleavage and shedding of Tie2 via a novel PI3K/Akt-dependent pathway. These results suggest a previously unrecognized mechanism by which VEGF may inhibit vascular stabilization to promote angiogenesis and vascular remodeling.

Circulating angiopoietin-2 is a strong prognostic factor in acute myeloid leukemia

Angiogenesis plays an important role in solid tumors and hematologic malignancies. The angiopoietins act as essential regulators in this process. We investigated the impact of circulating angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2) and soluble Tie2 (sTie2) on overall survival in patients with acute myeloid leukemia (AML). Ang-1, Ang-2 and sTie2 were measured in plasma samples from 68 AML patients and 11 controls using enzyme-linked immunosorbent assay. Circulating levels of Ang-2 and sTie2 (median (range): 1098.0 (361.4-4147.6) pg/ml and 3.40 (1.21-10.00) ng/ml, respectively) were significantly elevated in AML patients as compared to controls (307.9 (199.7-1225.0) pg/ml and 2.88 (1.71-3.29) ng/ml; P<0.001 and P=0.014). In a univariate Cox proportional hazards model, higher levels of Ang-2 and sTie2 were predictive of poor survival. In multivariate analyses, Ang-2 and cytogenetics proved to be independent prognostic factors, with a relative risk of 4.07 (95% confidence interval (CI) 1.88-8.81) and 2.70 (95% CI 1.25-5.81), respectively. The 3-year survival rate for AML patients with Ang-2 levels>/=1495.6 pg/ml was only 14.7% compared to 64.7% for those with Ang-2 levels<1495.6 pg/ml. These data provide evidence that circulating Ang-2 represents an independent prognostic factor in AML and may be used as a prognostic tool in the risk-adapted management of AML.

Changes in plasma vascular endothelial growth factor, angiopoietins, and their receptors following surgery for breast cancer

BACKGROUND

Vascular endothelial growth factor (VEGF), a major angiogenic growth factor, is involved in the pathogenesis of cancer. Plasma VEGF is raised in breast cancer and falls after successful surgery. Less is known about angiopoietins 1 and 2 (Ang-1, Ang-2). All three growth factors act on cells via receptors; Flt-1 for VEGF and Tie-2 for the angiopoietins. Cancer is also marked by abnormalities in platelet activation (marked by soluble P selectin) and inflammation (interleukin-6 [IL6]). We hypothesised altered plasma Ang-1, Ang-2, Flt-1 and Tie-2 in breast cancer that would normalize after 3 and 12 months treatment (i.e., surgery plus chemo/radiotherapy).

METHODS

Baseline venous blood was obtained from 40 women with breast cancer and 30 age-matched women with benign breast disease (BBD) also requiring surgery. Samples were taken again 3 months and 1 year later. Soluble P selectin, IL6, VEGF, Ang-1, Ang-2, Flt-1 and Tie-2 were measured in citrated plasma by ELISA.

RESULTS

Women with breast cancer had raised VEGF (7-fold), Ang-1 (50% higher) and Tie-2 (2-fold), but lower Flt-1 (to 26%), compared to the BBD women that broadly correlated with markers of platelet activation and inflammation. A level of Tie-2 or VEGF >95th percentile of the BBD group correctly identified 68% and 52% of the women with breast cancer. After 3 months of treatment, VEGF and Ang-1 normalized (as did IL6 and soluble P selectin) but Tie-2 was significantly lower only after 1 year. There were no significant changes in the women with BBD.

CONCLUSIONS

Treatment for breast cancer (surgery followed by chemotherapy and/or radiotherapy) is effective in reducing plasma VEGF, Tie-2 and Ang-1. These may be linked pathogenically with coagulation and inflammation.

Angiopoietin 1 (Ang-1), angiopoietin 2 (Ang-2) and Tie-2 (a receptor tyrosine kinase) concentrations in peripheral blood of patients with thyroid cancers

There are limited and conflicting studies investigating the role of the angiopoietin family in human thyroid cancer development and progression. We have investigated cytokines angiopoietin-1, -2 and their receptor (Tie-2), known to be involved in angiogenesis, in the serum of 52 thyroid cancer patients (21 cases of papillary cancers, PTC; 8 follicular cancers, FTC; 12 medullary cancers, MTC and 11 anaplastic cancers, ATC), using ELISA assays. The control consisted of 27 healthy volunteers. Statistically significant lower concentrations of Ang-1 were found in patients with thyroid cancers as compared with the control (p<0.003). The levels of Ang-2 and Tie-2 did not differ significantly between thyroid cancer patients and control. We have also compared the results of Ang-1, Ang-2, and Tie-2 determinations obtained in different histopathological subgroups of cancer patients. These results revealed lower Ang-1 concentrations in ATC (p<0.05), MTC (p<0.02), FTC (p<0.01) and in PTC patients (p<0.05) than control. We have also observed lower Ang-2 concentration in PTC patients (p<0.03) and Tie-2 in FTC patients (p<0.02 ) in comparison to controls. In conclusion, the Angs/Tie-2 system dysfunction may play an important role in thyroid cancerogenesis and decreased concentration of Ang-1 in serum can be a useful additional biomarker for the presence of thyroid cancers.

Angiopoietin-1, Angiopoietin-2 and Tie-2 in the Coronary Circulation of Patients With and Without Coronary Collateral Vessels

BACKGROUND

The role of the angiopoietin (Ang)/Tie-2 system in coronary collateral growth is not well understood, so the purpose of this study was to investigate and elucidate the relationship of this system to coronary collateral formation in patients with coronary artery disease (CAD).

METHODS AND RESULTS

Fifty-nine patients with CAD were recruited. Blood samples from the left ventricle (LV) and coronary sinus (CS) were obtained during cardiac catheterization, and serum concentrations of Ang-1, Ang-2, and Tie-2 were measured by enzyme-linked immunosorbent assay. Patients were then classified as mild CAD (n=30), defined as </=90% stenosis of the coronary arterial luminal diameter, or severe CAD (n=29), which was total (or near total) coronary occlusion requiring coronary collateral growth. Ang-1, Ang-2, and Tie-2 in the LV and CS sera were not significantly different between groups. In the severe CAD group, spillover of Tie-2 (CS-LV value) from the coronary circulation was found in comparison with the mild CAD group (3.43+/-2.22 vs -3.29+/-1.54 ng/ml, p=0.01), whereas the CS-LV values of Ang-1 and Ang-2 did not differ between groups. Tie-2 production was markedly increased in patients with well-developed collaterals. A positive and significant correlation was found between coronary Ang-2 and Tie-2 levels (r=0.44, p<0.001).

CONCLUSIONS

Tie-2 is probably produced in the coronary circulation and may induce the development or maintenance of coronary collaterals in CAD patients. Furthermore, the role of Ang-2 in the formation of coronary collaterals may be more important than that of Ang-1.

Antiangiogenic effect of Lygodium flexuosum against N-nitrosodiethylamine-induced hepatotoxicity in rats

The antiangiogenic effect of Lygodium flexuosum extract was evaluated in Wistar rats intoxicated with N-nitrosodiethylamine (NDEA) in preventive and curative models. In preventive groups, NDEA was administered for 20 weeks. Daily doses of L. flexuosumn-hexane extract (200mg/kg) started 1 week before the onset of NDEA intoxication and continued for 20 weeks. In curative animals, NDEA was administered for 20 weeks followed by treatment with the n-hexane extract of L. flexuosum for 28 days. Rats intoxicated with NDEA had elevated levels of serum gamma-GT, AST, ALT, LDH levels and hepatic MDA and decreased levels of hepatic GSH. When treated with L. flexuosum extract had normal levels of gamma-GT, AST, ALT, LDH levels, hepatic MDA and GSH. NDEA administered rat liver showed an overexpressed levels of angiopoietins 1 (Ang-1) and 2 (Ang-2) and its receptor Tie-2 mRNA. L. flexuosum extract treatment significantly (p<or=0.05) reduced the levels of Ang-1 and Ang-2 and Tie-2 in rat livers evidenced by RT-PCR. Immunohistochemical analysis showed that vascular endothelial growth factor (VEGF) was overexpressed and localized around periportal area of liver sections intoxicated with NDEA and its overexpression was effectively reduced by the treatment with L. flexuosum extract. Histopathological observations also substantiated NDEA-induced hepatotoxicity and the effect was significantly (p<or=0.05) reduced by L. flexuosum extract treatment. Thus, L. flexuosum extract at a dose of 200mg/kg effectively reversed the hepatotoxicity induced by N-nitrosodiethylamine in both experimental models.

Differential levels of soluble angiopoietin-2 and Tie-2 in patients with haematological malignancies

The system involving angiopoietin-2 (Ang-2) and its receptor, Tie-2, appears to play an important role not only in tumor angiogenesis, but also in the biology of haematological and non-haematological malignancies. In the present study we evaluated the serum levels of soluble Ang-2 (sAng-2) and soluble Tie-2 (sTie-2) in patients with haematological malignancies. Measurements were carried out in 15 patients with chronic myeloid leukaemia (CML), 25 with essential thrombocythemia (ET), 24 with multiple myeloma (MM) and six with monoclonal gammopathy of undetermined significance (MGUS). In addition, we correlated the levels of angiopoietins with known prognostic factors. sAng-2 and sTie-2 were quantified with enzyme-linked immunosorbent assay (ELISA). In patients with CML and MM the levels of sAng-2 were significantly higher (1686.53 +/- 936.41 pg/mL and 1917.82 +/- 1427 pg/mL, respectively) than in controls (n = 15; 996.096 +/- 414.65 pg/mL) (P < 0.01). In patients with MM sAng-2 levels were significantly increased with increasing stage of disease, from stage I to stage III (P < 0.03) and presented a trend of correlation with Beta2-microglobulin levels (r = 0.317) and grade of bone involvement. Furthermore, the levels of sAng-2 determined after 6 months of chemotherapy in CML patients were significantly lower than at diagnosis in the patients who achieved haematological remission. Circulating sTie-2 levels were increased in patients with ET (17.5 +/- 9.2 vs 9 +/- 3.5 ng/mL; P < 0.01) and in those with CML (16.29 +/- 8.7 ng/mL; P < 0.04). In conclusion, abnormal levels of sAng-2 and sTie-2 are present in some haematological malignancies. These markers may play a role in the pathophysiology of these conditions and their progression.

Serum levels of angiogenic factors indicate a pro-angiogenic state in adults with sickle cell disease

Hypoxia-induced angiogenesis may play an important role in the pathophysiology of sickle cell disease (SCD). Serum levels of angiopoietin (Ang)-1, Ang-2, vascular endothelial growth factor, placenta growth factor (PlGF), soluble tunica intima endothelial kinase 2 (sTIE2), erythropoietin (EPO) and endothelial activation markers (soluble vascular adhesion molecule-1, soluble intercellular adhesion molecule-1) were determined in controls, HbSS (n = 35) and HbSC (n = 23) patients. In the asymptomatic phase, serum Ang-2 (P < 0.001), EPO (P < 0.001) and sTIE2 (P = 0.03) were elevated in patients. During painful crises, increased Ang-2 (P < 0.001) and PlGF (P = 0.04) occurred in HbSS and Ang-2 (P = 0.05) in HbSC patients. These results indicate a pro-angiogenic state in SCD, mainly because of elevated Ang-2 levels.

A novel siRNA-lipoplex technology for RNA interference in the mouse vascular endothelium

For the application of RNA interference (RNAi) in vivo the functional delivery of short interfering RNAs (siRNAs) is still the major obstacle. Therefore, delivery technologies need to be established for the systemic application of RNAi in vivo. Here we report uptake, biodistribution and in vivo efficacy of siRNA molecules formulated into siRNA-lipoplexes. The applied formulation is based on complex formation of positively charged liposomes, a mixture of cationic and fusogenic lipids complexed with the negatively charged siRNA. We determined by fluorescence microscopy the temporal and spatial distribution of fluorescently labeled siRNA-lipoplexes, the body clearance and endothelial cell type specific uptake after single intravenous injection. Furthermore, by using siRNA molecules for targeting endothelia-specifically expressed genes, such as CD31 and Tie2, we were able to demonstrate downregulation of the corresponding mRNA and protein in vivo. Taken together, we show the applicability of this non-viral delivery technology for inducing RNAi in the vasculature of mice after systemic application.

Potential role of soluble angiopoietin-2 and Tie-2 in patients with inflammatory bowel disease

BACKGROUND

Angiogenesis has been suggested to play an important role in inflammatory bowel disease (IBD). The aim of the study was to evaluate the serum markers of angiogenesis angiopoietin-2 (Ang-2) and soluble angiopoietin receptor Tie-2 in patients with ulcerative colitis (UC) and Crohn's disease (CD).

MATERIALS AND METHODS

Serum Ang-2 and Tie-2 serum levels were measured in 160 IBD patients (79 UC and 81 CD) and in 80 matched healthy controls using commercially available enzyme-linked immunosorbent assays. Serum Ang-2 and Tie-2 levels were correlated with the disease activity, as well as the type, localization and treatment of the disease.

RESULTS

Median serum Ang-2 and Tie-2 levels were significantly higher in both the UC patients and the CD patients compared with the healthy controls (P < 0.05 and P < 0.001, respectively). The IBD patients with early disease (diagnosis < 2 years) had significantly higher (P = 0.04) median serum Ang-2 levels but significantly lower (P = 0.02) median serum Tie-2 levels as compared with IBD patients with late disease (diagnosis > 2 years). The CD patients with active disease had significantly higher levels of Ang-2 compared with non-active disease (P = 0.02). Serum levels of both Ang-2 and Tie-2 were not correlated with laboratory markers such as ESR, CRP, white blood cell count, platelet count and albumin.

CONCLUSIONS

Serum Ang-2 and Tie-2 levels are elevated in patients with IBD. These markers may mediate angiogenesis and vascular permeability in the mucosa of patients with IBD.

Serum C-reactive protein and soluble angiopoietin receptor Tie-2 in patients with acute myocardial infarction and its detection by optical proteinchip

Serum C-reactive protein (CRP) and soluble angiopoietin receptor Tie-2 (sTie) were detected in patients with acute myocardial infarction (AMI). The results indicated that mean serum CRP and Tie-2 levels were significantly higher in the patients with AMI than the control group. Increasing CRP was related to an increased infarction area and adverse prognosis. Levels of sTie-2 increased in the AMI patients and the maximum level of sTie-2 appeared at day 2 after onset of AMI. The feasibility of using to detect serum CRP and Tie-2 was also presented in this study. Measurement for CRP by optical proteinchip with imaging ellipsometry (OPC-IE) and immunobidimetric analyzer showed no obvious difference (p<0.01). Also, the measurement for Tie-2 by ELISA and OPC-IE showed no obvious difference (p<0.01).

Abnormal angiopoietins 1&2, angiopoietin receptor Tie-2 and vascular endothelial growth factor levels in hypertension: relationship to target organ damage [a sub-study of the Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT)]

BACKGROUND

The increased risk of target organ damage (TOD) in hypertension may be related to a prothrombotic or hypercoagulable state, with abnormalities in platelet activation. Altered angiogenesis, possibly related to increased plasma vascular endothelial growth factor (VEGF) is also a feature of hypertension. We hypothesized a link between altered angiogenesis and TOD in hypertension. Accordingly, the angiogenic growth factors VEGF, angiopoietin 1 and 2 (Ang 1 & 2) and soluble angiopoietin receptor Tie-2 in plasma and in platelets were assessed in terms of the presence or absence of hypertensive TOD.

METHODS

We studied 199 patients (75% men; mean age 68 years) with hypertension. Of these, 125 had evidence of hypertensive TOD (stroke, previous myocardial infarction, angina, left ventricular hypertrophy and mild renal failure). Patients were compared with 74 healthy normotensive controls (69% men; mean age 68 years). Plasma VEGF, Ang 1 & 2 and Tie-2, and total platelet levels of VEGF and Ang-1 (obtained by lysing a known number of platelets with 0.5% Tween) were measured by an enzyme-linked immunosorbent assay.

RESULTS

Hypertensive patients had higher levels of plasma VEGF, Ang-1, Ang-2, Tie-2 and platelet VEGF (all P<or=0.01), but not platelet Ang-1, when compared with normotensive controls. Patients with TOD had higher levels of platelet VEGF and Ang-1 (both P<0.001), and plasma Ang-1 (P<0.001). Amongst the hypertensives, plasma levels of VEGF correlated significantly with Ang-1, Ang-2, Tie-2 and platelet VEGF, whilst platelet VEGF correlated strongly with plasma levels of VEGF and Ang-1 (all P<0.05).

CONCLUSION

Patients with hypertension have evidence of changes in plasma angiogenic growth factors that correlate with the platelet levels of these molecules. Platelets may be involved in the abnormal angiogenesis seen in hypertension.

The angiopoietin/Tie-2 system in proliferative sickle retinopathy: relation to vascular endothelial growth factor, its soluble receptor Flt-1 and von Willebrand factor, and to the effects of laser treatment

AIM

To determine plasma levels of angiopoietin-1 and angiopoietin-2 (Ang-1, Ang-2), their soluble receptor Tie-2, vascular endothelial growth factor (VEGF), its soluble receptor Flt-1 (as indices of angiogenesis), and von Willebrand factor (vWf, marking endothelial damage/dysfunction) in sickle cell disease (SCD) patients with proliferative sickle retinopathy (PSR), with non-proliferative retinopathy (NPR), or no retinopathy (NR) and in control subjects with normal haemoglobin (AA subjects). In addition, to determine changes with panretinal laser photocoagulation (PRP) therapy.

METHODS

Research indices were measured (ELISA) in 24 SCD patients who had PSR, 16 with NPR, 16 with NR, and from 23 AA subjects. Eight patients received PRP therapy and plasma was obtained before laser treatment and at 6 months after the last PRP session.

RESULTS

Ang-1, Ang-2, VEGF, and vWf (but not Tie-2 or sFlt-1) were raised in SCD patients compared to AA subjects (p<0.01) but there were no differences among the three SCD subgroups. Significant correlations were between Ang-1 and VEGF, Ang-1 and Tie-2, and VEGF and sFlt-1 in patients with SCD (r = 0.67-0.88). Plasma Ang-2, VEGF, sFlt-1, and vWf levels did not change, but Ang-1 fell and Tie-2 rose significantly following PRP therapy.

CONCLUSIONS

SCD patients have raised plasma angiopoietins (Ang-1, Ang-2), VEGF, and vWf compared to AA subjects. These indices did not differ according to severity of retinopathy and only limited changes occurred following PRP. The elevated growth factor levels in SCD may have obscured any association with retinopathy.

Increase of serum angiopoietin-2 during pregnancy is suppressed in women with preeclampsia

BACKGROUND

Numerous recent reports demonstrated that changes in serum levels of angiogenesis-related factors were associated with preeclampsia. Here, we determined the serum concentration of angiopoietin-2 (Ang-2), a natural antagonist of angiopoietin-1 (Ang-1) involved in promoting angiogenesis in the presence of angiogenic stimuli such as vascular endothelial growth factor (VEGF), in women with preeclampsia.

METHODS

The levels of serum Ang-2 and Tie-2, a receptor for Ang-1 expressed on endothelial cells, were determined by enzyme-linked immunosorbent assay.

RESULTS

The concentrations of serum Ang-2 were significantly elevated in healthy pregnant women (18.9 ng/mL) as compared to nonpregnant women or women in postpartum period. Increase in the levels of serum Ang-2 was significantly suppressed in preeclamptic women (4.5 ng/mL). The serum Ang-2 concentrations inversely correlated with gestational age in healthy pregnant women, but not in preeclamptic women. The serum Ang-2 concentrations positively correlated with placental weight or mean blood pressure (BP) in healthy pregnant women, but not in preeclamptic women. The serum Ang-2 concentrations inversely correlated with proteinuria in preeclamptic women. The serum concentrations of Tie-2 were not significantly different between preeclamptic and nonpreeclamptic women.

CONCLUSIONS

These results suggest the potential requirement of circulating Ang-2 in proper formation of placental vasculatures during pregnancy. Although we cannot exclude the possibility that suppression in the increase of serum Ang-2 levels during pregnancy in preeclampsia as a consequence rather than a cause, measurement of serum Ang-2 concentration in pregnant women may serve as a useful marker in the diagnosis and potentially in predicting subsequent development of preeclampsia.

Plasma vascular endothelial growth factor and serum soluble angiopoietin receptor sTIE-2 in patients with dural arteriovenous fistulas: a pilot study

Our aim was to correlate concentrations of circulating vascular endothelial growth factor (VEGF) and serum soluble angiopoietin receptor (sTIE-2) before and after endovascular treatment with the grading in human dural arteriovenous fistulas (DAVFs). In ten patients with DAVFs undergoing diagnostic cerebral angiography and endovascular intervention, pre-treatment and post-treatment levels of plasma VEGF and serum TIE-2 were examined in a prospective study design. A total of 32 plasma samples and 19 serum samples was collected from the cubital vein, the arterial sheath before and--if applicable--after intervention. Plasma VEGF and serum Tie-2 levels were measured by standardized ELISA protocols. In eight of ten patients with DAVF increased circulating VEGF levels (elevation of more than mean + 2 SD of published normal values) were found, whereas two patients showed increased sTIE-2 levels. Six of the seven patients treated by endovascular embolization displayed a post-interventional decrease of VEGF values. The serum TIE-2 levels decreased slightly after intervention. Pre-treatment vVEGF levels varied significantly between patients with grades I and II/III fistulas according to the Cognards classification system. Our pilot study suggests that assessment of angiogenesis parameters in patients with DAVFs might correlate with the DAVFs' grade. To support the hypothesis that a change in angiogenic indicators may serve as indicators for a response to therapy, a larger number of patients should be followed for a longer time period.

Soluble angiopoietin receptor Tie-2 in patients with acute myocardial infarction and its effects on angiogenesis

Tie-2 receptor has been shown to play a role in the neovascularization of tumors, but little is known about the role it may play in acute myocardial infarction (AMI). The aims of this research are (1) To study the variety of soluble Tie-2 (sTie-2) in patients with AMI. (2) To study the effects of recombinant soluble Tie-2/Fc on HUVECs viability and tube formation in vitro. Serum levels of sTie-2 in 27 patients with AMI were measured on admission (day 1), day 2, day 3 and day 7 after onset of chest pain and 28 healthy controls by ELISA. In addition, the viability of HUVECs and tube formation area were measured after stimulated with recombinant Tie-2/Fc chimera. Median level of sTie-2 increased significantly in the AMI patients when compared with the controls and the maximum level appeared at day 2 after onset of AMI. Tie-2/Fc induced EC apoptosis and inhibited HUVEC tube formation in vitro. Results of this study showed that the level of sTie-2 increased in AMI. The effects of Tie-2/Fc on EC viability and tube formation indicated that angiogenesis might be inhibited in the acute phase of AMI.

Plasma vascular endothelial growth factor, angiopoietin-2, and soluble angiopoietin receptor tie-2 in diabetic retinopathy: effects of laser photocoagulation and angiotensin receptor blockade

BACKGROUND

Proliferative diabetic retinopathy (PDR) may be a response to abnormal angiogenic growth factors such as vascular endothelial growth factor (VEGF), angiopoietin-2 (Ang-2), and the soluble angiopoietin receptor tie-2. The authors hypothesised the following: (a) there are differences in plasma levels of these growth factors in different grades of diabetic retinopathy; and (b) that the effects of intervention with panretinal laser photocoagulation (PRP) for PDR, and angiotensin receptor blockade (using eprosartan) for patients with other grades of diabetic retinopathy will be to reduce levels of the growth factors.

METHODS

Cross sectional and interventional study (using PRP and eprosartan) in diabetic patients. VEGF, Ang-2, and tie-2 were measured by ELISA.

RESULTS

VEGF (p<0.001) and Ang-2 levels (p<0.001) were significantly higher in 93 diabetic patients compared to 20 healthy controls, with the highest levels in grade 2 and grade 3 diabetic retinopathy (p<0.05). Tie-2 was lower in diabetics compared to controls (p = 0.008), with no significant differences between the diabetic subgroups. Overall, VEGF significantly correlated with Ang-2 (p<0.001) and tie-2 (p = 0.004) but the correlation between Ang-2 and tie-2 levels was not significant (p = 0.065). Among diabetic patients only, VEGF levels were significantly correlated with Ang-2 (p<0.001) and tie-2 (p<0.001); the correlation between Ang-2 and tie-2 levels was also significant (p<0.001). There were no statistically significant effects of laser photocoagulation on plasma VEGF, Ang-2, and tie-2 in the 19 patients with PDR, or any effects of eprosartan in the 28 patients with non-proliferative diabetic retinopathy.

CONCLUSION

Increased plasma levels of VEGF and Ang-2, as well as lower soluble tie-2, were found in diabetic patients. The highest VEGF and Ang-2 levels were seen among patients with pre-proliferative and proliferative retinopathy, but there was no relation of tie-2 to the severity of retinopathy. As the majority of previous research into Ang-2 and tie-2 has been in relation to angiogenesis and malignancy, the present study would suggest that Ang-2 and tie-2 may be used as potential indices of angiogenesis in diabetes mellitus (in addition to VEGF) and may help elucidate the role of the angiopoietin/tie-2 system in this condition.

Expression of Vascular Endothelial Growth Factor Receptor-2 or Tie-2 on Peripheral Blood Cells Defines Functionally Competent Cell Populations Capable of Reendothelialization

BACKGROUND

Receptor tyrosine kinases that include vascular endothelial growth factor (VEGFR)-1, VEGFR-2, and Tie-2 regulate cardiovascular development and physiological and pathological angiogenesis. We were interested in the phenotypic and functional characterization of peripheral blood cells expressing these receptors and their therapeutic potential in vascular injury.

METHODS AND RESULTS

VEGFR-1+, VEGFR-2+, and Tie-2+ cells constituted approximately 3.0+/-0.2%, 0.8+/-0.5%, and 2.0+/-0.3%, respectively, of the total population of mononuclear cells in blood. Phenotypic analysis demonstrated that all 3 cell populations mainly expressed markers of monocytic/macrophage lineage. Only VEGFR-2+ and Tie-2+ cells phenotypically, morphologically, and functionally differentiated to endothelial cells after culture, whereas VEGFR-1+ cells did not. None of the cell types proliferated in vitro. Only freshly isolated VEGFR-2+ or Tie-2+ cells but not VEGFR-2- or Tie-2- cell populations significantly contributed to efficient endothelialization of balloon-injured femoral arteries of nude mice. Furthermore, these cells also differentiated into -actin-positive smooth muscle cells. Administration of bromodeoxyuridine to animals transplanted with human endothelial progenitor cells showed that VEGFR-2+ and Tie-2+ cells proliferated in vivo.

CONCLUSIONS

These data demonstrate that expression of VEGFR-2 and/or Tie-2 on peripheral blood cells defines functionally competent cell populations that proliferate in vivo and that contribute to reendothelialization. These findings may have implications for a cell-based approach in vascular diseases.

[Markers in patients with squamous cell carcinoma of the oral cavity. Expression and long-term follow-up of VEGF, FLT-1 and Tie2 in serum]

OBJECTIVE

The quantification of serum or plasma levels of angiogenic factors in patients with malignancies aims at the description of these factors or their receptors and allows a tissue independent study of biological tumor behavior.

METHODS

In 51 patients with untreated squamous cell carcinoma of the oral cavity (SCCOC) and 10 healthy controls, plasma levels of VEGF and serum levels of the VEGF-receptor FLT-1 and the Ang1-receptor Tie2 were measured. Using an ELISA technique, the concentration of these factors was measured preoperatively and postoperatively over a period of 5 weeks.

RESULTS

No statistically significant correlation could be found between the serum and plasma levels and the clinical or pathological parameters. There was no difference between the patients with SCCOC and healthy controls.

CONCLUSIONS

In patients with SCCOC, plasma levels of VEGF and serum levels of FLT-1 and Tie-2 do not provide any further information on the biological tumor behavior like proliferation or expression of metastases.

Plasma angiopoietin-1, angiopoietin-2, angiopoietin receptor tie-2, and vascular endothelial growth factor levels in acute coronary syndromes

BACKGROUND

Angiopoietin (Ang) -1 and -2, their receptor Tie-2, and vascular endothelial growth factor (VEGF) regulate angiogenesis and may be important in myocardial collateral development. Elevated levels of growth factors and their receptors are reported in myocardial infarction (MI), but changes after an acute coronary event are unknown.

METHODS AND RESULTS

Plasma Ang-1, Ang-2, Tie-2, and VEGF levels were measured on admission (baseline) and at 48 hours (acute stage) in 126 patients with acute coronary syndrome (82 MI, 44 unstable angina pectoris). Baseline levels were compared with those of 40 patients with stable angina and 40 healthy controls. Measurements were repeated in 38 MI patients at 6 and 18 weeks (chronic stage). Baseline Ang-2 and Tie-2 levels were highest in MI patients (P<0.001). Patients with MI and unstable angina pectoris had higher VEGF levels compared with stable angina patients and healthy control subjects (P<0.001). In patients with acute MI, serial changes in all indexes from baseline to 18 weeks were observed (all P<0.001). Ang-1 levels were unchanged from baseline to 6 weeks but were elevated at 18 weeks. Ang-2 changes followed a biphasic pattern, being higher at baseline and 6 weeks but lower at 48 hours and 18 weeks. Tie-2 levels increased from baseline and remained elevated in the chronic phase. VEGF peaked at 6 weeks and then decreased toward baseline at 18 weeks.

CONCLUSIONS

Plasma Ang-2, Tie-2, and VEGF levels but not Ang-1 levels were increased in patients with acute coronary syndrome. Serial changes in the plasma levels and interrelationships among Ang-1, Ang-2, Tie-2, and VEGF levels from the acute to the chronic stages in MI may reflect the progressive stages of angiogenesis activity in the ischemic-necrotic myocardium in vivo.

Changes in serum soluble VEGFR-1 and Tie-2 receptors in colorectal cancer patients following surgical resections

AIM

Determination of changes in serum levels of soluble (s) VEGFR-1 and Tie-2 receptors in colorectal cancer patients following resection in the search for novel tumour markers.

PATIENTS AND METHODS

Forty-five patients with primary colorectal cancer and 29 normal subjects were recruited. Serum sVEGFR-1 and sTie-2 receptors were assayed using ELISA.

RESULTS

sVEGFR-1 was detectable in 27% (10/37) and 12.5% (1/8) of cancer patients prior to curative and palliative resections, respectively, whilst 65.5% (19/29) of normal controls had detectable sVEGFR-1 levels. sTie-2 receptor levels were significantly raised in patients when compared with normal controls (p=0.0018). Furthermore, sTie-2 receptor levels were significantly higher in patients with metastases than those without (p=0.02). sTie-2 receptors demonstrated a significant drop in patients undergoing both curative (p<0.0001) and palliative resections (p=0.012).

CONCLUSION

sVEGFR-1 levels were suppressed and sTie-2 receptor levels were raised in colorectal cancer patients. This data supports the potential use of sTie-2 receptor as a tumour marker.

Plasma angiopoietin-1, angiopoietin-2, and angiopoietin receptor tie-2 levels in congestive heart failure

OBJECTIVES

The goal of this research was to test the hypothesis that plasma angiopoietin (Ang-1), its soluble receptor tie-2, and Ang-2 levels would be abnormal in patients with acute and chronic congestive heart failure (CHF) when compared with healthy controls.

BACKGROUND

Increased plasma vascular endothelial growth factor (VEGF) in CHF is suggestive of excess angiogenesis-possibly driven by tissue hypoxia. However, other growth factors also have a major role in angiogenesis, such as those of the angiopoietin family (e.g., Ang-1, which exerts its activity via its receptor, tie-2, and Ang-2).

METHODS

We recruited 39 patients with acute CHF (mean age 67 +/- 10 years), 40 patients with chronic CHF (mean age 63 +/- 9 years), and 17 healthy controls (mean age 67 +/- 7 years), all in sinus rhythm. Citrated plasma was analyzed for Ang-1, Ang-2, tie-2, and VEGF by enzyme-linked immunosorbent assay.

RESULTS

Angiopoietin-2 (p < 0.001), tie-2 (p < 0.05), and VEGF (p < 0.05) levels were all higher in acute CHF compared with controls. The Ang-2 levels were higher in acute CHF compared with chronic CHF (p < 0.001), but there were no significant differences in Ang-1 levels between the groups. The principal significant correlations were between Ang-2 and tie-2 (Spearman, r = 0.407; p < 0.0001) and between Ang-2 and ejection fraction (r = -0.241, p = 0.043). Although only marginally raised, levels of VEGF correlated with both Ang-2 (r = 0.468, p < 0.001) and tie-2 (r = 0.569, p < 0.001).

CONCLUSIONS

We have demonstrated abnormal levels of Ang-2 and tie-2, but normal Ang-1, in both CHF patients. These abnormalities may, alongside VEGF, indicate a role for these angiogenic factors in the pathophysiology of CHF.

Plasma angiopoietin-1, angiopoietin-2 and Tie-2 in breast and prostate cancer: a comparison with VEGF and Flt-1

BACKGROUND

Angiogenesis is essential for tumour growth and metastasis, and is coordinated by several classes of growth factors mediating their effect through receptors linked, in turn, to tyrosine kinase. These growth factors include angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2) and vascular endothelial growth factor (VEGF), which act through receptors Flt-1 and Tie-2.

MATERIALS AND METHODS

In order to further determine abnormalities in levels of Ang-1, Ang-2, Tie-2, sFlt-1 and VEGF in human cancer (and their interrelationships), these molecules were measured in plasma from 30 patients with breast cancer, 30 patients with prostate cancer and 12 healthy controls per cancer group.

RESULTS

In breast cancer, levels of Ang-1 (P=0.0005), Ang-2 (P=0.0173), Tie-2 (P=0.0001), and VEGF (P=0.0001) were all significantly raised, and plasma levels of sFlt-1 (P=0.045) were significantly reduced compared with controls. However, in prostate cancer, only levels of VEGF and Tie-2 were significantly higher (both P=0.001). There were no significant differences between levels of any molecule between the two groups of cancer. The only difference between the healthy control groups was lower Ang-1 in the women compared with men. Significant correlations were found between levels of Ang-1 and Tie-2 both in breast (r=0.498, P=0.005) and prostate cancer (r=0.643, P=<0.001). Angiopoietin-1 was also positively correlated with Ang-2 in both breast (r=0.422, P=0.02) and prostate cancer (r=0.543, P=0.002).

CONCLUSIONS

Abnormal levels of Ang-1, Ang-2 and their receptor, Tie-2, are present in breast and prostate cancer, and their interrelationships may be important in the pathophysiology of these conditions.