Angiogenesis is believed to be implicated in the pathogenesis of alcoholic liver disease (ALD). We aimed to explore the usefulness and accuracy of plasma angiogenic biomarkers for noninvasive evaluation of the severity of liver failure and ALD outcome. One hundred and forty-seven patients with ALD were prospectively enrolled and assessed based on their (1) gender, (2) age, (3) severity of liver dysfunction according to the Child-Turcotte-Pugh and MELD scores, and (4) the presence of ALD complications. Plasma levels of vascular endothelial growth factor (VEGF-A) and angiopoietins 1 and 2 (Ang1 and Ang2) were investigated using ELISAs. Multivariable logistic regression was applied in order to select independent predictors of advanced liver dysfunction and the disease complications. Significantly higher concentrations of Ang2 and VEGF-A in ALD patients as compared to controls were found. There was no difference in Ang1 levels in both groups. A positive correlation of Ang2 levels with INR (Rho 0.66;
Alcoholic liver disease (ALD) with subsequent progression to cirrhosis and hepatocellular carcinoma (HCC) has become a predominant liver disease in Europe [
Angiogenesis is regulated by a balance between pro- and antiangiogenic factors in a mutually dependent manner. It is crucial for the maintenance of normal structure and function of the human body vasculature [
Vascular endothelial growth factor (VEGF) is best known as the most potent stimulator of both normal and pathological angiogenesis. In the postnatal period, it preserves integrity of endothelium and acts as a mitogen for endothelial cells. VEGF is a potent mediator in wound healing, and it also induces vascular permeability inside injured tissues.
The release of VEGF increases under hypoxic conditions. Its expression is regulated by the hypoxia inducible factor (HIF-1a), which triggers VEGF transcription [
Tyrosine kinase receptors (Tie1 and Tie2) and their ligands angiopoietins 1–4 (Ang1, -2, -3, and -4) play a key role during the late phase of angiogenesis and are responsible for the maturation of newly formed vascular structures. The best described and characterized are two angiopoietins: Ang1 and Ang2. The activity of the angiopoietin/Tie system determines the stabilization of new vessels. Both Ang1 and Ang2 interact with the same site of the Tie2 receptor having similar affinity toward it, but only Ang1 induces its phosphorylation and subsequent activation [
There is growing evidence that the angiopoietin/Tie signaling may influence the evolution of inflammation [
In contrast, Ang2 acts as a competitive antagonist of Ang1 and downregulates Tie2 signaling [
On this background, we have designed a study in order to assess concentrations of selected molecules of angiogenesis, that is, vascular endothelial growth factor (VEGF-A) and angiopoietins 1 and 2 (Ang1 and Ang2) in peripheral blood of patients with ALD in comparison to healthy controls (HC). We hypothesized that their synthesis might be increased during the course of ALD as a consequence of the local and systemic inflammatory response and have an impact on the disease deterioration and the development of complications. We further aimed to investigate the usefulness and accuracy of selected angiogenic biomarkers in the noninvasive evaluation of the degree of liver failure and ALD outcome.
The study cohort has been described in detail in our previously published report concerning the adipokine assessment [
Briefly, 147 consecutive adult inpatients (pts) with ALD, admitted to the Department of Gastroenterology with Endoscopy Unit in Lublin, were prospectively enrolled over a 2-year period and followed for 90 days. Thirty matching volunteers, who pledged abstinence or alcohol consumption as no more than 20 g ethanol per day, served as a control group.
The ALD diagnosis was established based on typical symptoms and physical findings of chronic liver disease, high aminotransferase levels, AST/ALT ratio above 2, and imaging studies in the setting of excessive alcohol intake. Alcohol abuse was confirmed by the AUDIT-C (Alcohol Use Disorders Identification Test-Consumption) questionnaire [
According to the study protocol, eligible patients signed the informed consent, completed their medical history, and answered the AUDIT-C questionnaire prior to the investigation.
Neither corticosteroids nor pentoxifylline were administered to any individual at the time of enrollment. Demographic data as well as all procedures were recorded and performed within 48 hours after hospital admission. Blood samples were collected at 07:30 AM after a minimum 8-hour overnight fast. Other cofactors of chronic liver injury were excluded.
The severity of liver failure at baseline was established using the Child-Turcotte-Pugh (CTP) [
Patients were included into different subgroups according to their gender, age, the severity of liver dysfunction according to the CTP (classes A, B, and C) and MELD (≥20 or <20) scores, the presence of ALD complications at the time of hospital admission, that is, ascites, hepatic encephalopathy (HE), oesophageal varices, cholestasis, and renal impairment.
Subjects with severe comorbidities present at the time of enrollment, that is, malignancy, pulmonary insufficiency, heart failure, and uncontrolled diabetes, were excluded.
Cholestasis was defined in accordance with the recommendations of the European Association for the Study of the Liver (EASL), that is, alkaline phosphatase (AP) greater than 1.5 times above the upper limit of normal (ULN) and the activity of
The presence of esophageal varices was confirmed endoscopically.
The level of serum creatinine above 1.3 mg/dL (the upper limit of normal) was considered a criterion of renal impairment.
Only individuals for whom all the required laboratory data were available at admission were included in the trial.
All enrolled patients were inpatients at the starting point of the study. They were discharged from the hospital once ethanol withdrawal symptoms have disappeared, complications of liver failure (i.e., coagulopathy, jaundice, encephalopathy, etc.) have resolved, and liver function has begun to improve. Subsequent follow-up visits with their examination during next 90 days were set at least once a month (generally every 2 weeks) in the liver clinic or during any hospital admission if required. Two of the nonsurvivors returned to our department after their condition worsened and they died in the hospital. The majority of nonsurvivors (10 out of 12) were treated continuously without any hospital discharge.
We used enzyme-linked immunosorbent assays to measure concentrations of selected angiogenic biomarkers, that is, vascular endothelial growth factor-A (VEGF-A) and angiopoietins 1 and 2 (Ang1 and Ang2) with commercially available kits (Quantikine ELISA kit, R&D Systems, USA). Blood samples were obtained by venipuncture into vacutainer tubes containing EDTA and centrifuged within 30 minutes for 15 minutes at 4°C. As recommended by the R&D Systems instructions, an additional centrifugation step was performed for complete platelets removal. Plasma samples were stored frozen at
The examination was conducted according to the procedure recommended by the producer and described in the attached materials. Measurements were performed using VictorTM3 Reader (PerkinElmer, USA).
The study protocol conforms to the ethical guidelines of the 1975 Declaration of Helsinki (6th revision, 2008) as reflected in a priori approval by the institutional review board of Medical University of Lublin.
Statistical analysis was performed using the Statistica 10 software package (StatSoft, Poland). The distribution of the data in the groups was preliminarily evaluated by Kolmogorov-Smirnov test. A skewed distribution of checked values was found, so continuous variables were presented as medians with interquartile range and assessed using Mann-Whitney
One hundred and forty-seven patients (pts) met the inclusion criteria, 107 males (72.8%) and 40 females (27.2%). Their mean age was
Of the 147 pts with ALD, 12 (8.16%) died from complications of liver failure within 90 days of followup. The matching control group consisted of 17 (56.7%) males and 13 (43.3%) females aged
Basic characteristics of patients with ALD based on their gender
ALD group ( |
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Females ( |
Males ( |
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Median | 95% CI | 25–75 P | Median | 95% CI | 25–75 P | ||
Age |
51.00 | 48.03–54.96 | 45.00–56.00 | 51.00 | 48.00–52.49 | 40.00–60.00 | 0.19 |
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ALT |
39.50 | 28.03–44.93 | 23.00–47.00 | 56.00 | 50.00–69.00 | 35.25–84.00 |
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ASP |
100.50 | 78.45–114.90 | 66.00–120.00 | 110.00 | 78.51–131.00 | 64.50–189.00 | 0.72 |
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AP |
118.50 | 111.68–156.27 | 105.00–179.00 | 129.00 | 118.00–148.00 | 79.00–223.00 | 0.62 |
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GGT |
415.00 | 174.00–543.00 | 172.00–772.00 | 359.00 | 200.50–504.88 | 93.00–1066.00 |
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T-Bil |
4.20 | 3.51–5.27 | 3.30–8.40 | 3.00 | 1.75–4.00 | 1.10–8.10 | 0.70 |
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Alb |
3.10 | 2.70–3.29 | 2.63–3.50 | 3.20 | 3.00–3.30 | 2.73–3.61 | 0.12 |
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INR | 1.45 | 1.39–1.64 | 1.31–1.71 | 1.21 | 1.16–1.30 | 1.07–1.43 |
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Crea |
0.80 | 0.70–0.80 | 0.70–1.00 | 0.90 | 0.90–1.00 | 0.80–1.10 | 0.51 |
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Na |
139.00 | 136.03–140.96 | 134.00–141.00 | 138.00 | 136.51–139.00 | 134.00–140.00 | 0.38 |
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Hgb |
11.20 | 10.34–11.50 | 9.70–12.00 | 12.10 | 11.60–12.70 | 10.30–13.50 |
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RBC |
3.17 | 3.08–3.50 | 2.86–3.52 | 3.86 | 3.57–3.97 | 3.15–4.11 |
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PLT |
135.50 | 114.38–137.96 | 97.00–251.00 | 136.00 | 116.00–166.46 | 80.00–202.00 | 0.81 |
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WBC |
8.12 | 5.42–11.63 | 4.89–13.04 | 7.12 | 6.30–8.28 | 5.01–10.80 | 0.75 |
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NEUT |
8.44 | 3.20–8.97 | 2.57–13.51 | 5.02 | 4.19–6.10 | 2.91–7.92 |
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NLR | 4.38 | 2.34–4.52 | 2.34–7.63 | 3.47 | 3.26–4.45 | 2.13–6.04 | 0.12 |
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CRP |
17.33 | 16.19–33.14 | 5.98–42.17 | 17.53 | 13.40–21.30 | 5.01–43.00 | 0.58 |
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mDF | 17.35 | 12.00–22.96 | 9.00–28.00 | 9.00 | 6.00–12.00 | 4.00–16.74 | 0.21 |
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MELD | 17.50 | 15.03–18.00 | 12.00–20.00 | 15.00 | 14.00–16.00 | 11.00–17.00 |
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CTP | 9.50 | 9.00–10.00 | 8.00–10.00 | 7.00 | 7.00–8.00 | 7.00–9.00 |
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At the beginning, we measured plasma concentrations of three angiogenic molecules in patients (pts) with ALD and healthy controls (HC). While Ang2 and VEGF-A levels were found significantly increased in the ALD group, Ang1 concentrations did not differ in comparison with HC. Moreover, the Ang2/Ang1 ratio was significantly higher in ALD pts (median; 25–75 interquartile range: 1.97; 0.61–9.80 versus 0.91; 0.39–1.28, resp.;
Comparison of plasma angiogenesis-related biomarkers in ALD patients and the control group
Biomarkers of angiogenesis |
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ALD patients ( |
Controls ( |
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Median | 95% CI | 25–75 P | Median | 95% CI | 25–75 P | ||
Ang1 |
2.90 | 2.09–3.26 | 0.99–5.28 | 3.02 | 1.46–4.97 | 1.06–6.12 | 0.83 |
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Ang2 |
4.58 | 3.99–6.09 | 3.12–9.97 | 1.95 | 1.33–2.30 | 1.10–2.43 |
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VEGF-A |
85.27 | 68.73–99.16 | 40.01–207.91 | 48.47 | 36.58–67.30 | 31.71–70.95 |
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We observed no significant differences in plasma concentrations of angiogenesis-related markers between both sexes either in the control or in the ALD group (
Since recently published data have shown that age-related alterations may have an influence on angiogenesis [
Comparison of plasma angiogenic biomarkers according to the age of patients with ALD.
Angiogenesis-related biomarkers in ALD group |
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Age < 50 ( |
Age ≥ 50 ( |
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Median | 95% CI | 25–75 P | Median | 95% CI | 25–75 P | ||
Ang1 |
3.69 | 2.32–5.14 | 1.16–8.57 | 2.09 | 1.69–3.02 | 0.16–4.67 |
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Ang2 |
3.99 | 3.58–4.83 | 2.49–6.21 | 7.23 | 4.46–9.48 | 3.36–11.56 |
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VEGF-A |
100.22 | 67.62–231.94 | 53.02–369.57 | 73.79 | 61.40–89.03 | 30.60–145.22 |
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Our subsequent analysis revealed that of three angiogenic molecules only the level of Ang2 rose significantly with the severity of liver dysfunction classified according to the CTP as well as MELD scores. The results are shown in Table
Plasma angiogenesis-related biomarkers in subgroups of patients with different grades of liver failure.
CTP class
Class A ( |
Class B ( |
Class C ( |
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Median | 95% CI | 25–75 P | Median | 95% CI | 25–75 P | Median | 95% CI | 25–75 P | ||
Ang1 |
2.96 | 1.81–3.26 | 1.16–5.06 | 3.17 | 1.98–4.72 | 1.03–6.20 | 2.08 | 1.02–3.66 | 0.00–4.65 | 0.28 |
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Ang2 |
2.94 | 2.35–3.85 | 1.88–3.99 | 4.56 | 3.57–5.35 | 2.91–7.23 | 10.32 | 9.42–11.86 | 5.12–13.44 |
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VEGF-A |
100.13 | 73.50–120.66 | 62.57–231.66 | 89.21 | 61.40–203.16 | 30.60–358.15 | 67.21 | 48.27–81.25 | 33.74–112.68 | 0.07 |
MELD score
<20 points |
≥20 points ( |
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Median | 95% CI | 25–75 P | Median | 95% CI | 25–75 P | ||
Ang1 |
2.90 | 2.09–3.36 | 1.03–5.84 | 2.71 | 0.11–3.72 | 0.00–5.1 | 0.16 |
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Ang2 |
3.90 | 3.56–4.56 | 2.86–7.72 | 11.37 | 7.05–13.19 | 5.12–15.94 |
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VEGF-A |
86.55 | 71.81–100.18 | 43.10–207.91 | 64.60 | 27.11–148.12 | 23.25–246.83 | 0.20 |
Further analyses concerning liver function parameters showed a positive correlation of plasma Ang1 concentrations with liver enzymes (ALT: Rho 0.28;
Correlation between Ang2 concentrations (ng/mL) and INR.
Correlation between Ang2 concentrations (ng/mL) and serum albumin levels (g/dL).
The studied angiogenic biomarkers weakly correlated with traditional indicators of inflammation: the white blood cell count (Ang1: Rho 0.25;
The next step of our investigation was focused on exploration of a possible association between ALD complications and plasma angiogenic biomarker concentrations.
For angiogenic biomarkers, in which plasma levels were significantly different in subgroups of subjects selected according to the severity of liver dysfunction (MELD ≥ 20) and the presence of ALD complications, the areas under the curve (AUCs) were assessed and their diagnostic accuracy was compared. The results revealed that Ang2 possessed the highest diagnostic and prognostic potential among studied angiogenesis-related molecules. The results are summarized in Tables
Plasma angiogenesis-related biomarkers in subgroups of ALD patients according to the presence of the disease complications.
Ascites |
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Absent ( |
Present ( |
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Median | 95% CI | 25–75 P | Median | 95% CI | 25–75 P | ||
Ang1 |
3.19 | 2.32–5.04 | 1.51–5.29 | 2.09 | 1.50–3.17 | 0.16–4.82 | 0.11 |
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Ang2 |
3.21 | 2.52–3.88 | 1.88–4.58 | 7.53 | 5.35–9.43 | 3.89–11.40 |
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VEGF-A |
100.22 | 82.63–196.53 | 61.40–333.36 | 68.73 | 58.66–86.55 | 29.43–149.34 |
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Hepatic encephalopathy | |||||||
Absent ( |
Present ( |
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Median | 95% CI | 25–75 P | Median | 95% CI | 25–75 P | ||
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Ang1 |
2.96 | 2.09–3.28 | 1.03–5.70 | 1.77 | 0.00–3.64 | 0.00–3.69 | 0.07 |
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Ang2 |
4.45 | 3.64–5.26 | 2.92–8.84 | 10.13 | 5.61–14.87 | 4.83–15.16 |
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VEGF-A |
91.79 | 71.66–115.74 | 44.30–243.11 | 49.17 | 25.50–84.63 | 25.46–85.27 |
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Oesophageal varices | |||||||
Absent ( |
Present ( |
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Median | 95% CI | 25–75 P | Median | 95% CI | 25–75 P | ||
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Ang1 |
3.06 | 2.33–5.14 | 1.75–7.28 | 2.32 | 1.51–3.29 | 0.16–4.70 | 0.08 |
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Ang2 |
3.63 | 2.89–5.26 | 1.88–6.21 | 5.12 | 4.37–8.31 | 3.55–11.46 |
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VEGF-A |
100.22 | 72.73–231.94 | 61.98–358.65 | 71.66 | 52.43–89.51 | 26.62–146.57 |
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Cholestasis | |||||||
Absent ( |
Present ( |
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Median | 95% CI | 25–75 P | Median | 95% CI | 25–75 P | ||
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Ang1 |
2.32 | 1.51–3.05 | 0.49–5.08 | 4.72 | 3.28–6.40 | 2.90–7.28 |
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Ang2 |
4.83 | 3.64–6.55 | 2.90–10.52 | 3.90 | 3.39–4.55 | 3.12–6.21 | 0.28 |
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VEGF-A |
71.81 | 61.40–88.396 | 33.01–168.11 | 121.73 | 101.30–244.22 | 81.52–402.69 |
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Renal impairment | |||||||
Creatinine < 1.3 mg/dL ( |
Creatinine ≥ 1.3 mg/dL ( |
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Median | 95% CI | 25–75 P | Median | 95% CI | 25–75 P | ||
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Ang1 |
2.32 | 1.69–3.18 | 0.65–5.29 | 3.27 | 3.05–5.14 | 2.71–5.28 | 0.08 |
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Ang2 |
4.45 | 3.63–5.12 | 2.92–9.06 | 9.42 | 7.13–11.40 | 5.09–11.99 |
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VEGF-A |
73.79 | 66.81–91.62 | 33.74–231.66 | 112.68 | 85.52–158.08 | 64.60–207.91 | 0.32 |
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Disease outcome | |||||||
Survivors ( |
Nonsurvivors ( |
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Median | 95% CI | 25–75 P | Median | 95% CI | 25–75 P | ||
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Ang1 |
3.05 | 1.98–3.52 | 1.00–5.70 | 2.28 | 0.00–2.71 | 0.00–2.71 | 0.10 |
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Ang2 |
4.51 | 3.80–5.26 | 2.92–8.92 | 11.74 | 9.48–13.44 | 9.48–13.44 |
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VEGF-A |
85.270 | 68.73–95.69 | 40.84–207.31 | 73.14 | 25.46–246.83 | 25.46–246.83 | 0.48 |
Comparison of the diagnostic accuracy (AUC) of single variables in the diagnosis of advanced liver dysfunction (MELD ≥ 20) and ALD complications (univariable analysis)
Complication of ALD | Variable |
|
AUC (95% CI) | SE |
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MELD ≥ 20 |
|
<0.0001 | 0.829 (0.758–0.886) | 0.036 |
CRP | 0.004 | 0.609 (0.527–0.686) | 0.058 | |
RBC | 0.003 | 0.675 (0.596–0.747) | 0.055 | |
WBC | 0.0003 | 0.656 (0.577–0.730) | 0.061 | |
Ascites | 0.003 | 0.652 (0.572–0.725) | 0.050 | |
HE | <0.0001 | 0.666 (0.587–0.739) | 0.058 | |
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Ascites |
|
<0.0001 | 0.772 (0.695–0.837) | 0.041 |
Albumin | <0.0001 | 0.819 (0.748–0.877) | 0.036 | |
ALT | 0.0001 | 0.710 (0.633–0.779) | 0.041 | |
AST | 0.003 | 0.606 (0.526–0.683) | 0.047 | |
INR | <0.0001 | 0.808 (0.739–0.866) | 0.036 | |
RBC | 0.002 | 0.663 (0.584–0.736) | 0.044 | |
WBC | 0.008 | 0.597 (0.517–0.674) | 0.045 | |
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HE |
|
0.0001 | 0.731 (0.652–0.801) | 0.063 |
|
0.022 | 0.705 (0.624–0.777) | 0.050 | |
AP | 0.006 | 0.652 (0.567–0.730) | 0.071 | |
Albumin | 0.005 | 0.686 (0.605–0.759) | 0.055 | |
T-bilirubin | 0.0001 | 0.770 (0.697–0.833) | 0.048 | |
INR | 0.0001 | 0.737 (0.661–0.804) | 0.059 | |
PLT | 0.035 | 0.633 (0.553–0.708) | 0.057 | |
Ascites | 0.012 | 0.646 (0.567–0.720) | 0.056 | |
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Renal impairment |
|
0.003 | 0.692 (0.610–0.765) | 0.062 |
Albumin | 0.034 | 0.654 (0.572–0.729) | 0.059 | |
AST | 0.042 | 0.601 (0.521–0.678) | 0.062 | |
AP | 0.030 | 0.677 (0.593–0.753) | 0.068 | |
Na | 0.012 | 0.588 (0.508–0.666) | 0.080 | |
CRP | 0.001 | 0.714 (0.636–0.784) | 0.060 | |
WBC | 0.011 | 0.689 (0.611–0.760) | 0.053 | |
RBC | 0.031 | 0.688 (0.610–0.759) | 0.059 | |
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Poor outcome (nonsurvival) |
|
0.009 | 0.788 (0.713–0.851) | 0.059 |
Bilirubin | 0.0004 | 0.765 (0.691–0.828) | 0.059 | |
Albumin | 0.0004 | 0.818 (0.747–0.876) | 0.061 | |
Na | 0.003 | 0.751 (0.676–0.816) | 0.081 | |
AP | 0.024 | 0.641 (0.556–0.720) | 0.102 | |
INR | 0.009 | 0.735 (0.659–0.802) | 0.057 | |
HE | 0.005 | 0.652 (0.573–0.726) | 0.086 |
Independent predictors of advanced liver dysfunction (MELD ≥ 20) and ALD complications (multivariable analysis)
Complication of ALD | Variable |
|
Adjusted OR (95% CI) | AUC (95% CI) | SE |
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MELD ≥ 20 |
|
<0.0001 | 1.358 (1.190–1.550) | 0.908 (0.844–0.952) | 0.028 |
HE | 0.021 | 4.796 (1.269–18.124) | |||
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HE |
|
0.010 | 1.256 (1.057–1.493) | 0.934 (0.876–0.970) | 0.029 |
|
0.066 | 0.977 (0.953–1.002) | |||
AP | 0.035 | 1.016 (1.001–1.032) | |||
T-bilirubin | 0.024 | 1.126 (1.015–1.249) | |||
PLT | 0.014 | 0.980 (0.965–0.996) | |||
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Renal impairment |
|
0.009 | 1.128 (1.030–1.236) | 0.775 (0.695–0.842) | 0.060 |
CRP | 0.006 | 1.023 (1.006–1.039) |
Our study represents an in-depth evaluation of the usefulness of angiogenesis-related biomarkers in noninvasive monitoring of the ALD course. It may provide insights into methods of preventing the ALD progression and the development of its complications. Despite intensive research, the role of Ang1, Ang2, and VEGF in the evolution of liver disease remains unclear. To our knowledge, this is the first study which has demonstrated the association of systemic concentrations of Ang2 and VEGF-A with ALD evolution. Nowadays, it is increasingly evident that the liver disease etiology is linked to the dynamics of chronic wound healing process, the development of fibrosis, and the rate of progression to cirrhosis [
The pivotal finding of the study is the identification of Ang2 as an independent predictor of advanced liver dysfunction as well as two major ALD complications (i.e., HE and renal impairment). We found that high baseline plasma Ang2 levels were related to the poor disease outcome and its more aggressive course.
We also observed that levels of circulating Ang1 in healthy adults were higher than Ang2 and the Ang2/Ang1 ratio was significantly lower compared to patients with ALD (median; interquartile range: 0.91; 0.35–1.59 versus 1.97; 0.61–9.80;
Previous experimental results showed the synergistic interaction between inflammation and angiogenesis in the healing of damaged tissues [
On the other hand, angiogenesis generated at the early stage of liver disease may promote the transition of acute into a chronic phase of inflammation. It is also possible that a debilitating immune defect might prevent damping of inflammation in a subgroup of ALD patients. Our study revealed the close relationship between angiogenesis and inflammation in the course of ALD. We found a positive correlation between the levels of three angiogenic molecules and traditional markers of inflammation (i.e., white cells count and CRP level). Our results are consistent with previous reports concerning the similar topic [
In the ALD group, Ang2 and VEGF-A concentrations were significantly higher in comparison to healthy individuals regardless of their gender (Table
These results were in agreement with the results obtained from the next analysis, that is, correlation tests. A significant correlation of Ang2 levels with synthetic liver function parameters was found: negative for the albumin level and positive for INR. Our results suggest that Ang2 may be a relevant biomarker of liver function impairment in ALD pts and indicate the potential for its use in clinical practice.
On the other hand, Ang1 and VEGF-A plasma concentrations showed a positive correlation with cholestatic enzymes (AP and GGT). The levels of both molecules were significantly higher in the subset of pts with signs of cholestasis (Table
Further evaluation showed a different association of Ang2 and VEGF-A plasma levels with the development of ALD complications. Ang2 concentrations were significantly higher, but VEGF-A was significantly lower in patients with ascites, hepatic encephalopathy (HE), and esophageal varices (Table
It is likely that the development of ALD complications may result from endotoxemia which is quite frequent phenomenon in the course of the disease. It has been found that endotoxemia causes microcirculatory endothelial dysfunction with increased vessel permeability and can lead to a disintegration of vascular system together with organ failure [
The results of multivariate logistic regression confirmed the independent impact of Ang2 on the severity of liver failure (MELD ≥ 20) and the development of two major ALD complications, that is, HE and renal impairment (Table
Although many aspects of Ang2 action are still unclear, the observations obtained from experimental models and the results of clinical studies provide an insight into the potential utility of Ang2 as a prognostic predictor in a variety of disorders associated with active vascular remodeling; ALD could be one of them as suggested by our study.
Limitations of the present study come from the relatively small sample size. It was a single-center trial so it should be emphasized that the results before their wide application require being confirmed in future multicenter trials. Such validation may help to avoid possible errors resulting from research techniques or subjective differences in the patient population selection.
If the results are confirmed, two potential prospects emerge from our study. Selected proangiogenic molecules may serve as an easy noninvasive diagnostic tool in the ALD evaluation. The antiangiogenic therapy seems to be able to modulate the disease progression and therefore requires further detailed investigations.
Development of tools and strategies to limit the simultaneous chronic inflammatory response and angiogenesis in the course of ALD may help to avoid their subsequent adverse effects and prevent liver failure and diminish the need for liver transplantation.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interests.
This study was supported by the research Grants from the Medical University of Lublin, Poland (PW445/2010-2011).