Endocan, Novel Potential Biomarker for Systemic Sclerosis: Results of a Pilot Study

Treatable Traits in Systemic Sclerosis

Systemic sclerosis (SSc) is a chronic systemic disease within the spectrum of connective tissue diseases, specifically characterized by vascular abnormalities and inflammatory and fibrotic involvement of the skin and internal organs resulting in high morbidity and mortality. The clinical phenotype of SSc is heterogeneous, and serum autoantibodies together with the extent of skin involvement have a predictive value in the risk stratification. Current recommendations include an organ-based management according to the predominant involvement with only limited individual factors included in the treatment algorithm. Similar to what has been proposed for other chronic diseases, we hypothesize that a "treatable trait" approach based on relevant phenotypes and endotypes could address the unmet needs in SSc stratification and treatment to maximize the outcomes. We provide herein a comprehensive review and a critical discussion of the literature regarding potential treatable traits in SSc, focusing on established and candidate biomarkers, with the purpose of setting the bases for a precision medicine-based approach. The discussion, structured based on the organ involvement, allows to conjugate the pathogenetic mechanisms of tissue injury with the proposed predictors, particularly autoantibodies and other serum biomarkers. Ultimately, we are convinced that precision medicine is the ideal guide to manage a complex condition such as SSc for which available treatments are largely unsatisfactory.

Serum endocan levels in children with rheumatic aortic insufficiency: can it differentiate bicuspid aortic valve disease from rheumatic heart disease?

AIM

In this study, it was aimed to examine the serum endocan levels in patients with rheumatic aortic regurgitation and to investigate whether it has a value in differentiating it from aortic regurgitation due to bicuspid aortic valve.

METHODS

Blood samples were collected from patients with rheumatic aortic regurgitation (Group 1), incidentally diagnosed patients with borderline or definite rheumatic aortic regurgitation (Group 2), children with bicuspid aortic valve accompanied by aortic regurgitation (Group 3) and healthy children (Group 4) of similar age.

RESULTS

There were 12 children in Group 1, 13 in Group 2, 25 in Group 3, and 25 in Group 4. Groups were similar in terms of age (p = 0.291). There was no statistically significant difference between median serum endocan levels of Group 1 and Group 2 (p = 0.624), and Group 3 and Group 4 (p = 0.443). Despite that, the median serum endocan levels of Group 1 and Group 2 were significantly higher than that of both Group 3 and Group 4 (p = 0.000 for all).

CONCLUSIONS

Our results indicate that serum endocan level can be used to differentiate rheumatic aortic regurgitation from non-rheumatic aortic regurgitation. It is thought that the prognostic role of this marker should be confirmed in long-term, prospective studies with larger samples.

Endocan and Circulating Progenitor Cells in Women with Systemic Sclerosis: Association with Inflammation and Pulmonary Hypertension

Background: Systemic sclerosis (SSc) is characterized by early vasculopathy and fibrosis in the skin, lungs, and other tissues. Vascular manifestations of SSc include Raynaud’s phenomenon, digital ulcers, and pulmonary artery hypertension (PAH). PAH is the second most common cause of mortality in SSc. Circulating CD34+ cells associated with cardiovascular health status in several conditions, including chronic immune-inflammatory disease. CD34+ cell numbers have been found inconstantly reduced in SSc. Endocan, a proteoglycan expressed by endothelial cells, was recently suggested as a marker of vascular stress. We tested the relationships among CD34+ cells, endocan, inflammatory markers, vitamin D levels, and clinical parameters in SSc patients with PAH. METHODS: Standard echocardiography was performed. Vitamin D levels, CD34+ cells, inflammatory markers, endocan plasma levels were determined in 36 female SSc patients (24 diffuse/12 limited) and 36 matched controls (HC). RESULTS: We found no difference in CD34+ and vitamin D levels in SSc as compared to controls; ESR, CRP, fibrinogen, endocan, sPAP were higher in SSc with respect to controls. We found a correlation between endocan and: CD34+ cells (r: −0.540, p = 0.002), pulmonary arterial pressure (sPAP) (r: 0.565, p < 0.001), tricuspid annular plane excursion (TAPSE) (r: −0.311, p < 0.01), and E/A ratio (r: −0.487, p < 0.001), but not with ejection fraction (r: −0.057, p = 0.785) in SSc. CD34+ cells correlate with fibrinogen (r: −0.619, p < 0.001), sPAP (r: −0.404, p = 0.011), E/A (r: 0.470, p < 0.005 in SSc. CONCLUSION: CD34+ cell number was significantly correlated with endocan levels and with sPAP in SSc; endocan and CD34+ progenitor cells might be suggested as a potential marker of disease status.

Endocan: A Novel Marker for Colchicine Resistance in Familial Mediterranean Fever Patients?

Introduction: Familial Mediterranean fever (FMF) patients had 5-10% colchicine resistance. Although FMF attacks are characterized by acute phase elevation, there are no biomarkers that can show colchicine resistance yet. The serum endocan levels may elevate in inflammatory and auto-inflammatory diseases. Objectives: This study aimed to evaluate serum endocan levels in FMF patients according to whether attack and colchicine resistance or not and also compare them with classical acute phase reactants. Methods: In this single-center and cross-sectional study, a total of 111 FMF patients and 60 healthy individuals were enrolled. All patients' basic demographic and clinical data were recorded and blood samples were collected. Results: A total of 46 (41.4%) FMF patients had colchicine resistance. In comparison to the FMF patients according to colchicine response, colchicine resistance patients had a significantly higher median (IQR) endocan levels than colchicine responsive patients [36.98 ng/ml (97.41) vs. 13.57 ng/ml (27.87), p = 0.007], but there were no differences between in terms of median ESR and CRP levels. Inversely, serum endocan levels were similar during an attack and attack-free period in FMF patients, although ESR and CRP levels were significantly different. Interestingly, the highest serum endocan levels were in the control group. Conclusion: In conclusion, serum endocan levels were higher in colchicine resistance than colchicine responsive patients, but attack state had no effect on serum endocan levels in our study. Unlike ESR and CRP, serum endocan may be a novel biomarker for detection of colchicine resistance and distinguish the FMF attacks.

The role of endocan and selected pro-inflammatory cytokines in systemic lupus erythematosus

INTRODUCTION

Systemic lupus erythematosus (SLE) is a multisystem inflammatory autoimmune disease with a wide spectrum of clinical manifestations. Cytokines such as interleukin-1 (IL-1) and tumour necrosis factor α (TNF-α) are involved in its pathogenesis. Endocan is a novel marker of endothelial dysfunction and is likely to be engaged in proinflammatory processes in SLE.

AIM

To determine whether endocan serum concentration in SLE patients vary from healthy controls.

MATERIAL AND METHODS

The study included 36 patients with SLE. SLEDAI-2K score was used to assess disease activity. The control group comprised 23 healthy volunteers. ELISA kits were used to assess serum concentrations of endocan, IL-1β, TNF-α, vascular endothelial growth factor (VEGF) and high-sensitivity C reactive protein (hs-CRP).

RESULTS

The serum concentration of endocan was significantly higher (p < 0.001) in the SLE group than in healthy individuals. A positive correlation was found between serum levels of endocan and IL-1β (r = 0.47, p < 0.05). Active SLE patients (SLEDAI-2K score above 6 points) with an elevated total cholesterol level (above 5.17 mmol/l) were found to have VEGF concentration higher than those with a normal cholesterol level (p < 0.03). No other relevant relationships were found between the serum concentration of endocan, other laboratory parameters, anthropometric features, activity and duration of SLE.

CONCLUSIONS

A higher serum level of endocan in SLE patients indicates its possible role in the pathogenesis of the disease and reflects endothelial dysfunction. Our findings indicate that endocan could serve as a potential marker of endothelial dysfunction in SLE.

Validity of endocan as a biomarker in systemic sclerosis: relation to pathogenesis and disease activity

Background

Systemic sclerosis (SSc), an autoimmune disease, has endothelial dysfunction and tissue fibrosis. The lack of its specific activity markers urges the research. Endocan is an immunomodulatory protein associated with endothelial dysfunction. We aimed to measure of the endocan level in systemic sclerosis (SSc) patients’ sera to test its relation to disease activity and treatment responses. Also, to evaluate its specificity by comparing these data with Behçet’s disease (BD) and rheumatoid arthritis (RA) patients’ data.

Results

SSc and RA patients were in activity but in the BD group; eight were active and seven were inactive. The endocan level was higher in the three groups in comparison to the controls without statistically significant differences (p value RA 0.697, SSc 0.063, and BD 0.196). A statistically significant difference in endocan levels between SSc patients with and without vascular manifestations (pulmonary hypertension and finger pitting ulcers, p < 0.0001, p = 0.0097, respectively). There were no significant correlations between endocan level and the erythrocyte sedimentation rate and C-reactive protein (positive rheumatoid factor for RA) in the three groups (p > 0.05). There were no significant correlations between endocan level and activity scores in the three groups (p > 0.05). The cut-off value of endocan was 1.3 ng/ml.

Conclusion

Endocan is a non-specific marker for the vascular pathogenesis in systemic sclerosis but not a good predictor for its activity.

Elevated plasma endocan and BOC in heart failure patients decrease after heart transplantation in association with improved hemodynamics

BACKGROUND

The prevalence of heart failure (HF) is rising with ageing population and constitutes a major health problem globally. A common complication of HF is pulmonary hypertension (PH) which negatively impacts survival. A pathophysiological association between HF and PH with tumorigenic processes has been suggested. We aimed to identify the plasma levels of, and the association between tumour-related proteins and hemodynamic improvements in patients with HF and PH due to left heart disease (LHD) before and 1-year after heart transplantation (HT).

METHODS

Forty-eight tumour-related proteins were measured with proximity extension assay in plasma from 20 controls and 26 HF patients before and 1-year after HT. Patients' hemodynamics were measured with right heart catheterization.

RESULTS

Out of 48 proteins, specifically, plasma levels of endocan and brother of CDO (BOC) were elevated in end-stage HF patients compared to controls (p < 0.001), but decreased after HT (p < 0.01), towards controls' levels. The decrease of endocan levels after HT correlated with improved mean pulmonary arterial pressure (rs = 0.80, p < 0.0001), pulmonary arterial wedge pressure (rs = 0.63, p = 0.0012), and pulmonary vascular resistance (rs = 0.70, p < 0.001). The decrease and normalization of BOC after HT correlated with decreased mean right atrial pressure (rs = 0.61 p = 0.0015) and NT-proBNP (rs = 0.57, p = 0.0022), as well as increased cardiac index (rs = - 0.51, p = 0.0086) and left-ventricular stroke work index (rs = - 0.57, p = 0.0039).

CONCLUSION

Our results suggest that (i) plasma endocan in HF may reflect the state of pulmonary vascular congestion and PH-LHD, whereas (ii) plasma BOC may reflect the cardiac function and the hemodynamic overload in HF. The exact role of these proteins and their clinical applicability as biomarkers in HF and PH-LHD ought to be investigated in larger cohorts.

Endocan and Lumican in Relation to Cardiometabolic Risk in a Pediatric Overweight and Obese Cohort: A Cross-Sectional Study

The aim of the study was to evaluate serum Endocan and Lumican levels as biomarkers for pediatric Nonalcoholic Fatty Liver Disease (NAFLD) and to explore their associations with pediatric cardiometabolic risk factors. We conducted a cross-sectional study on 68 pediatric obese and overweight (O&O) patients. Ten healthy controls were recruited. Serum Lumican and Endocan levels were analyzed using ELISA kits. O&O patients had lower levels of Endocan compared to healthy controls (p < 0.001). There were no differences between serum Endocan levels in O&O patients with NAFLD and those without (p = 0.53). Patients considered having Nonalcoholic Steatohepatitis (NASH) had lower Endocan levels compared to O&O patients without NASH (p = 0.026). Patients with metabolic syndrome had lower levels of Endocan (p = 0.003). There were no significant differences between serum Lumican levels in O&O children compared to healthy controls. Lumican levels were higher in patients with hypertension (p = 0.04). In O&O patients, Lumican levels were negatively correlated with Endocan levels (r = −0.37, p = 0.002). Endocan seems a promising biomarker for the evaluation of pediatric NASH. Lumican was not confirmed as a biomarker for NAFLD in our cohort but was associated with higher arterial pressure. Low Endocan levels are accompanied by high serum Lumican levels, and this could be an early signature of cardiometabolic risk.

Endothelial Cell-Specific Molecule 1 Promotes Endothelial to Mesenchymal Transition in Renal Fibrosis

The endothelial-to-mesenchymal transition (EndoMT) is involved in the complex pathogenesis of renal fibrosis. The soluble proteoglycan endothelial cell-specific molecule 1 (ESM1) is significantly upregulated in many tumor cells and cirrhosis-related disease. The role of ESM1 in renal fibrosis is unknown. This study investigates the role of ESM1 in renal fibrosis, using an in vivo unilateral ureteral obstruction (UUO) mouse model of renal fibrosis and in vitro mouse kidney MES 13 cells overexpressing ESM1. We observed that ESM1 overexpression significantly increased the motility and migration of MES 13 cells, independent of cell viability. In ESM1-overexpressing MES 13 cells, we also observed elevated expression of mesenchymal markers (N-cadherin, vimentin, matrix metallopeptidase 9 (MMP9)) and the fibrosis marker α-smooth muscle actin (α-SMA) and decreased expression of the endothelial marker vascular endothelial cadherin (VE-cadherin) and CD31. In a mouse model of fibrosis induced by unilateral ureter obstruction, we observed time-dependent increases in ESM1, α-SMA, and vimentin expression and renal interstitial collagen fibers in kidney tissue samples. These results suggest that ESM1 may serve as an EndoMT marker of renal fibrosis progression.

Plasma Glycosaminoglycan Profiles in Systemic Sclerosis: Associations with MMP-3, MMP-10, TIMP-1, TIMP-2, and TGF-Beta

The aim of the study was to determine whether plasma levels of total glycosaminoglycans (GAGs), matrix metalloproteinases (MMPs) (MMP-3, MMP-10), and their tissue inhibitors (TIMPs) (TIMP-1, TIMP-2) as well as transforming growth factor β (TGF-β) differ in the patients with systemic sclerosis (SSc) in relation to the healthy subjects. Plasma samples were obtained from 106 people (64 patients with SSc and 42 healthy individuals) and measured for MMP-3, MMP-10, TIMP-1, TIMP-2, and TGF-β levels using ELISA methods. GAGs isolated from plasma samples were quantified using a hexuronic acid assay. The plasma levels of total GAGs, TIMP-1, TIMP-2, and TGF-β were significantly higher, while MMP-3 was significantly decreased in SSc patients compared to the controls. We have revealed a significant correlation between plasma GAGs and TGF-β (r = -0.47) and TIMP-2 (r = 0.38), respectively. The results of this study revealed that remodeling of the extracellular matrix, reflected by quantitative changes in plasma glycosaminoglycans, occurs during systemic sclerosis. Thus, the alterations in GAG metabolism connected with SSc may lead to systemic changes in the properties of the connective tissue extracellular matrix.

Novel Biomarkers for Evaluation of Endothelial Dysfunction

Endothelial dysfunction is one of the earliest indicators of cardiovascular (CV) dysfunction, and its evaluation would be of considerable importance to stratify CV risk of many diseases and to assess the efficacy of atheroprotective treatments. Flow-mediated dilation is the most widely used method to study endothelial function. However, it is operator-dependent and can be influenced by physiological variations. Circulating biomarkers are a promising alternative. Due to the complexity of endothelial function, many of the biomarkers studied do not provide consistent information about the endothelium when measured alone. New circulating markers are being explored and some of them are thought to be suitable for the clinical setting. In this review, we focus on novel biomarkers of endothelial dysfunction, particularly endothelial microparticles, endocan, and endoglin, and discuss whether they fulfill the criteria to be applied in clinical practice.

The diagnostic and prognostic value of serum endocan in patients with cirrhotic cardiomyopathy

BACKGROUND

We aimed to determine the relationship between endocan and cirrhotic cardiomyopathy.

MATERIALS AND METHODS

Patients with liver cirrhosis and no heart disease were included in a prospective observational study with liver disease decompensation and death as primary outcomes.

RESULTS

83 cirrhotic patients were included and 32 had cirrhotic cardiomyopathy. Endocan levels were significantly lower in patients with cirrhotic cardiomyopathy (5.6 vs. 7 ng/mL, p = 0.034). Endocan correlated with severity of cirrhosis, time to decompensation or death from liver disease (OR 4.5 95% CI 1.06-31.1).

CONCLUSION

Endocan is a promising biomarker of severity of cirrhosis and may help in the diagnosis of cardiac dysfunction in this population.

Serum Level of Endothelial Cell-Specific Molecule -1 (ESM -1) as a New Potential Biomarker for Rheumatoid Arthritis Disease Activity

Background:

Rheumatoid arthritis is a chronic inflammatory autoimmune disease characterized by destruction of the joint cartilage and bone. Endothelial dysfunction (ED) in RA may be related to disease activity. Our objective is to explore serum levels of endothelial cell-specific molecule-1 (ESM-1) as a biomarker for RA disease activity.

Methods:

A cross-sectional study was carried out and included 83 adult patients with RA, in addition to 20 healthy subjects (age and sex-matched) as a control group. Based on Disease Activity Score in 28 joints (DAS-28), the patient's group was subdivided into four subgroups(remission, mild, moderate and severe disease activity state). The demographic & clinical data, BMI, DAS-28 and Serological assessment [Erythrocyte Sedimentation Rate (ESR), CRP, Rheumatoid Factor (RF) and Anti-Citrullinated Peptide Antibody (ACPA)] were recorded. ESM-1was assayed for all participants.

Results:

Serum levels of ESM1 were significantly higher in the patient group than the control group (P< 0.0001). ESM-1 serum levels were significantly higher in patients with severe disease activity subgroup compared with patients with remission and mild disease activity subgroups (P< 0.0001). ESM-1 was positively and significantly correlated with DAS-28 score, The Health Assessment Questionnaire Disability Index (HAQ-DI) and modified Larsen score (P= 0.002, 0.0001 & 0.0001 respectively).

Conclusion:

ESM-1 could be a biomarker for RA disease activity.

The Assessment of Serum Endocan Levels in Children With Juvenile Idiopathic Arthritis

Objectives

This study aims to evaluate the levels of serum endocan in children with juvenile idiopathic arthritis (JIA).

Patients and methods

Sixty-seven children with JIA (30 males, 37 females; mean age 10.4±4.9 years; range 2 to 18 years) and a sex- and age- matched healthy control group of 39 children (16 males, 23 females; mean age 9.3±4.1 years; range 1 to 17 years) were recruited. Patients with JIA were divided into two groups as the clinically active JIA group (n=27) and inactive JIA group (n=40).

Results

The median serum endocan level in patients with JIA was significantly higher than in the control group (633.75 ng/L vs. 379.76 ng/L, p<0.01). Comparison between patients with active JIA and inactive JIA was not significant in terms of endocan levels (618.70 ng/L vs. 687.36 ng/L, p=0.34). There was a weak negative correlation between Childhood Health Assessment Questionnaire scores of patients with JIA and serum endocan levels.

Conclusion

The high level of serum endocan highlighted the endothelial damage in patients with JIA.