Serum syndecan-4 correlates with blood pressure and cardiovascular parameters but not proinflammatory markers in healthy older women.

Aging is accompanied by a low-grade proinflammatory status that plays a role in age-related vascular alterations. Syndecan-4 (SDC4) is a key component of the endothelial glycocalyx, and its extracellular domain can be shed by matrix metalloproteinase-9 (MMP-9). In vitro studies demonstrated that MMP-9-mediated shedding of SDC4 is induced by tumor necrosis factor-α (TNF- α) in human endothelial cells. However, the relationship between circulating shed SDC4, systemic inflammation, and age-related vascular alterations remains unknown. Here, we used linear regression models to examine the associations of serum SDC4 levels with cardiovascular hemodynamic phenotypes, serum MMP-9, and serum TNF-α and inteleukin-6 in healthy older women (n = 74). Serum SDC4 was not associated with proinflammatory cytokines or arterial elasticity. Nevertheless, we found significant correlations of SDC4 with MMP-9, heart rate, left ventricular ejection time, systemic vascular resistance, and blood pressure. Our preliminary evidence suggests that systemic inflammation might not induce SDC4 shedding in healthy aging.

A reduction in the vascular smooth muscle cell focal adhesion component syndecan-4 is associated with abdominal aortic aneurysm formation.

BACKGROUND: Abdominal aortic aneurysm (AAA) is a serious vascular disease for which there is no effective drug treatment. The incidence of AAA increases significantly as a subject ages, and the molecular mechanism of AAA formation remains elusive. In the present study, we investigated the role of syndecan-4 (SDC4), an important component of focal adhesions, in AAA formation and its association with phenotypic changes in vascular smooth muscle cells (VSMCs). METHODS AND RESULTS: The protein expression levels of SDC4 were significantly decreased in human AAA tissue and those of an AAA mouse model. Moreover, SDC4 knockout (KO) in mice accelerated the formation and rupture of AAAs induced by angiotensin II (Ang II) and calcium chloride (CaCl2 ) Mechanistically, the decrease in SDC4 led to the transformation of cultured VSMCs from a contractile to a secretory phenotype. The RhoA-F/G-actin-myocardin-related transcription factor-A (MRTF-A) signalling pathway was shown to be involved in SDC4-dependent VSMC alteration. Sphingosine-1-phosphate (S1P), a G-protein-coupled receptor, attenuated the AAA formation in SDC4-KO and wild-type (WT) mice in response to Ang II and CaCl2 stimulation. CONCLUSION: We herein demonstrated that silencing SDC4 was associated with increased AAA formation and phenotypic changes in VSMCs via the RhoA-F/G-actin-MRTF-A pathway. These findings indicated that a reduction in SDC4 expression was an important pathological alteration and potential therapeutic target for AAA formation.

Association Between Factors Involved in Bone Remodeling (Osteoactivin and OPG) With Plasma Levels of Irisin and Meteorin-Like Protein in People With T2D and Obesity.

The musculoskeletal system consisting of bones and muscles have been recognized as endocrine organs secreting hormones that are involved in regulating metabolic and inflammatory pathways. Obesity and type 2 diabetes (T2D) are associated with several musculoskeletal system complications. We hypothesized that an interaction exists between adipomyokines namely, irisin and METRNL, and various molecules involved in bone remodeling in individuals with obesity and T2D. A total of 228 individuals were enrolled in this study, including 124 non-diabetic (ND) and 104 T2D. A Multiplex assay was used to assess the level of various osteogenic molecules namely osteoactivin, Syndecan, osteoprotegerin (OPG) and osteonectin/SPARC. Our data shows elevated levels of Osteoactivin, Syndecan, OPG and SPARC in T2D as compared to ND individuals (p ≤ 0.05). Using Spearman's correlation, a positive correlation was observed between irisin and Osteoactivin as well as OPG (p < 0.05). Similarly, a positive association was observed between METRNL and Osteoactivin (p < 0.05). The strong positive association shown in this study between irisin, METRNL and various molecules with osteogenic properties emphasize a possible interaction between these organs. This report suggests that having a dysregulation in the level of the aforementioned molecules could potentially affect the development of bone and muscle related complications that are associated with obesity and T2D.

Serum syndecan-4 is associated with nonalcoholic fatty liver disease.

OBJECTIVES: The accelerated shedding of extracellular domains of syndecan-4 (SDC4) is associated with central obesity and insulin resistance, while the association between serum SDC4 and nonalcoholic fatty liver disease (NAFLD) is unknown. We aimed to examine the association between SDC4 and NAFLD. METHODS: Adults undergoing a health examination from 1 June 2019 to 31 December 2019 were enrolled. A diagnosis of NAFLD was made with an abdominal ultrasound. Logistic regression models and the receiver operating characteristic (ROC) curves were used to evaluate the role of SDC4 in predicting NAFLD. RESULTS: In total, 533 eligible participants were finally enrolled, among them 157 (29.46%) had NAFLD. The proportion of patients with NAFLD increased with the increasing quartiles of serum SDC4. With the increase of serum SDC4 levels, metabolic features including waist circumference, serum triglyceride, total cholesterol, fasting blood glucose, fasting insulin and homeostasis model assessment of insulin resistance were significantly increased. SDC4 was an independent factor for NAFLD (odds ratio 1.963, 95% confidence interval [CI] 1.628-2.367, P < 0.001). The area under the ROC curve of SDC4 for predicting NAFLD was 0.934 (95% CI 0.910-0.959). The optimal cut-off value was 6.575 ng/mL at Youden's index of 0.767. SDC4 had the highest diagnostic sensitivity (84.1%), positive predictive value (82.5%), negative predictive value (93.3%) and positive likelihood ratio (11.356) among all the variables. CONCLUSIONS: Elevated serum SDC4 level is associated with metabolic disorders and the prevalence of NAFLD among general population. Serum SDC4 may serve as a biomarker of NAFLD.

Circulating Levels of the Heparan Sulfate Proteoglycan Syndecan-4 Positively Associate with Blood Pressure in Healthy Premenopausal Women.

Syndecans (SDCs) are transmembrane proteins that are present on most cell types where they play a role in multiple physiological processes, including cell-matrix adhesion and inflammation. Growing evidence suggests that elevated levels of both shed SDC1 and SDC4 are associated with hypertension and cardiovascular diseases, but their relationships with cardiovascular risk factors in healthy individuals are unknown. The primary objective of this study was to investigate whether serum levels of SDC4 and SDC1 were associated with body composition, hemodynamic parameters, pro-inflammatory cytokine concentrations, and urinary noradrenaline and dopamine levels in healthy women (17 African American and 20 European American) between the ages of 20 and 40 years old. Univariate analyses revealed only a significant (p < 0.05) inverse correlation between serum SDC1 and body fat percentage. On the other hand, serum SDC4 was positively correlated with systolic blood pressure, diastolic blood pressure, and urinary levels of noradrenaline and dopamine. Serum SDC4 was also a significant predictor of systolic blood pressure in a multivariate regression model that included fat-free mass and urinary dopamine levels as significant independent variables. The result did not change even adjusting for race. Our findings indicate that SDC4 has an important role in the physiological regulation of blood pressure.

Acute exercise increases syndecan-1 and -4 serum concentrations.

The effects of acute and long-term exercise on syndecans and the relationship to insulin sensitivity are not fully explored. We aimed to examine the effects of acute and 12 weeks of exercise on (1) serum levels of syndecan-1 and -4, (2) gene expression related to syndecan synthesis and modification in skeletal muscle and adipose tissue, and (3) the relationship to insulin sensitivity. Sedentary men with (n = 13) or without (n = 13) dysglycemia underwent two 45 min acute bicycle tests interspersed by 12 weeks of exercise intervention. Euglycemic hyperinsulinemic clamp and mRNA-sequencing of skeletal muscle and adipose tissue biopsies were performed before and after intervention. Serum syndecan-1 and -4 levels were quantified before, immediately after and 2 h after bicycling. Syndecan-1 and -4 serum concentrations increased in response to acute physical exercise. Baseline syndecan-4 but not syndecan-1 concentrations were higher in dysglycemic compared to normoglycemic men, and correlated to change in insulin sensitivity, but did not change during the 12 weeks exercise intervention. Only syndecan-4 was expressed in skeletal muscle and adipose tissue. Adipose tissue mRNA levels of transcripts affecting syndecan structure and shedding were upregulated in dysglycemia, and muscle mRNA responded to long-term physical activity. The increase in serum syndecan-1 and -4 due to acute exercise suggest increased syndecan shedding and disruption of glycocalyx in response to increased blood flow. The higher syndecan-4 baseline serum levels in dysglycemia, association to insulin sensitivity, and changes in mRNA transcripts may suggest syndecan-4 involvement in muscle and adipose tissue response to exercise.

Serum suPAR and syndecan-4 levels predict severity of community-acquired pneumonia: a prospective, multi-centre study.

BACKGROUND: Community-acquired pneumonia (CAP) is a major cause of death worldwide and occurs with variable severity. There are few studies focused on the expression of soluble urokinase-type plasminogen activator receptor (suPAR) and syndecan-4 in patients with CAP. METHODS: A prospective, multi-centre study was conducted between January 2014 and December 2016. A total of 103 patients with severe CAP (SCAP), 149 patients with non-SCAP, and 30 healthy individuals were enrolled. Clinical data were recorded for all enrolled patients. Serum suPAR and syndecan-4 levels were determined by quantitative enzyme-linked immunosorbent assay. The t test and Mann-Whitney U test were used to compare between two groups; one-way analysis of variance and the Kruskal-Wallis test were used to compare multiple groups. Correlations were assessed using Pearson and Spearman tests. Area under the curve (AUCs), optimal threshold values, sensitivity, and specificity were calculated. Survival curves were constructed and compared by log-rank test. Regression analyses assessed the effect of multiple variables on 30-day survival. RESULTS: suPAR levels increased in all patients with CAP, especially in severe cases. Syndecan-4 levels decreased in patients with CAP, especially in non-survivors. suPAR and syndecan-4 levels were positively and negatively correlated with severity scores, respectively. suPAR exhibited high accuracy in predicting SCAP among patients with CAP with an AUC of 0.835 (p < 0.001). In contrast, syndecan-4 exhibited poor diagnostic value for predicting SCAP (AUC 0.550, p = 0.187). The AUC for predicting mortality in patients with SCAP was 0.772 and 0.744 for suPAR and syndecan-4, respectively; the respective prediction threshold values were 10.22 ng/mL and 6.68 ng/mL. Addition of both suPAR and syndecan-4 to the Pneumonia Severity Index significantly improved their prognostic accuracy, with an AUC of 0.885. Regression analysis showed that suPAR ≥10.22 ng/mL and syndecan-4 ≤ 6.68 ng/mL were reliable independent markers for prediction of 30-day survival. CONCLUSION: suPAR exhibits high accuracy for both diagnosis and prognosis of SCAP. Syndecan-4 can reliably predict mortality in patients with SCAP. Addition of both suPAR and syndecan-4 to a clinical scoring method could improve prognostic accuracy. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03093220 . Registered on 28 March 2017 (retrospectively registered).

Lack of association between serum syndecan-4, myocardial fibrosis and ventricular dysfunction in subjects with chronic Chagas disease.

BACKGROUND: Syndecan-4 is a transmembrane glycoprotein associated with inflammation and fibrosis. Increased syndecan-4 levels were previously detected after acute myocardial infarction and in subjects with heart failure. However, the levels of syndecan-4 in subjects with Chagas disease have not so far been investigated. The aim of this study was to investigate the potential role of serum sydencan-4 as a novel biomarker for myocardial fibrosis and cardiac dysfunction in subjects with Chagas disease. METHODS: This study comprised subjects with Chagas disease (n = 56), being 14 (25%) with the indeterminate form, 16 (29%) with the cardiac form without ventricular dysfunction, and 26 (46%) with the cardiac form with ventricular dysfunction. RESULTS: Syndecan-4 serum concentrations did not correlate with presence or absence of myocardial fibrosis (P = 0.386) nor disease severity in subjects with Chagas disease (P = 0.918). Additionally, no correlation was found either between the degree of myocardial fibrosis and serum syndecan-4 [r = 0.08; P = 0.567] or between left ventricular ejection fraction and syndecan-4 [r = 0.02; P = 0.864]. In contrast, NT-proBNP levels correlated with ejection fraction and myocardial fibrosis. CONCLUSIONS: Our results demonstrate the lack of correlations between serum syndecan-4, myocardial fibrosis and cardiac dysfunction in subjects with Chagas disease. Further studies are required to show if syndecan-4 concentrations can be marker for prognosis assessment or disease progression.

Baseline serum syndecan-4 predicts prognosis after the onset of acute exacerbation of idiopathic interstitial pneumonia.

BACKGROUND: Patients with idiopathic interstitial pneumonia can experience acute respiratory worsening, also known as acute exacerbation, with a large deterioration on prognosis. The precise mechanism remains unclear; however, syndecan-4 may be involved. Syndecan-4, a transmembrane heparan sulfate proteoglycan expressed in a variety of cells (e.g., epithelial cells, macrophages, fibroblasts, etc.), performs various biological roles by binding to several proteins through its heparan sulfate glycosaminoglycan side chains. The goal of this study was to clarify the role of syndecan-4 in acute exacerbation of idiopathic interstitial pneumonia. METHODS: Patients with idiopathic interstitial pneumonia who had been sequentially admitted to our hospital due to acute exacerbation were retrospectively analyzed. First, serum syndecan-4 levels in the acute exacerbation and clinically stable phases were compared. Second, the relationship between serum syndecan-4 levels and clinical parameters was analyzed. Third, the relationship between serum syndecan-4 levels and prognosis was evaluated. RESULTS: Serum syndecan-4 levels were significantly lower in patients with acute exacerbation of idiopathic interstitial pneumonia than in patients in the clinically stable phase. Serum syndecan-4 levels also showed a significant positive correlation with white blood cell count and a weak positive tendency with KL-6 and baseline %VC. Prognosis was significantly worse in patients with idiopathic interstitial pneumonia with high baseline serum syndecan-4 levels than with low baseline levels. Multiple logistic analysis indicated baseline serum syndecan-4 level as the only prognostic predictor following acute exacerbation. CONCLUSIONS: Baseline serum syndecan-4 is a possible prognostic biomarker after the onset of acute exacerbation of idiopathic interstitial pneumonia.

Increased syndecan-4 expression in sera and skin of patients with atopic dermatitis.

Syndecan-4 (SDC-4) is a cell surface proteoglycan, which participates in signaling during cell adhesion, migration, proliferation, endocytosis, and mechanotransduction, and is expressed on various cells, including endothelial cells, epithelial cells, T cells, and eosinophils. Emerging evidences have suggested that SDC-4 might contribute to Th2-driven allergic immune responses. Here, we examined the role of SDC-4 in patients with atopic dermatitis (AD). Serum SDC-4 levels in AD patients were significantly higher than in healthy individuals, and they increased according to the disease severity. Importantly, they positively correlated with Eczema Area and Severity Index and itch visual analogue scale scores. Furthermore, serum SDC-4 levels decreased after treatment. We also analyzed SDC-4 expression in AD lesional skin. SDC-4 mRNA levels in AD skin were significantly higher than those of normal skin. Immunohistochemical staining revealed that SDC-4 was highly expressed in the epidermis and endothelial cells in AD lesional skin. Taken together, our study has demonstrated that SDC-4 expression was increased in sera and skin of AD patients, suggesting that SDC-4 may contribute to the development of AD.

Measurement of lipocalin-2 and syndecan-4 levels to differentiate bacterial from viral infection in children with community-acquired pneumonia.

BACKGROUND: In this study, we evaluated the lipocalin-2 (LIP2) and syndecan-4 (SYN4) levels in children who were hospitalized for radiologically confirmed CAP in order to differentiate bacterial from viral infection. The results regarding the LIP2 and SYN4 diagnostic outcomes were compared with the white blood cell (WBC) count and C reactive protein (CRP) levels. METHODS: A total of 110 children <14 years old who were hospitalized for radiologically confirmed CAP were enrolled. Serum samples were obtained upon admission and on day 5 to measure the levels of LIP2, SYN4, and CRP as well as the WBC. Polymerase chain reaction of the respiratory secretions and tests on blood samples were performed to detect respiratory viruses, Streptococcus pneumoniae, and Mycoplasma pneumoniae. RESULTS: CAP was considered to be due to a probable bacterial infection in 74 children (67.3 %) and due to a probable viral infection in 16 children (14.5 %). Overall, 84 children (76.4 %) were diagnosed with severe CAP. The mean values of the WBC count and the LIP2 and SYN4 levels did not differ among the probable bacterial, probable viral, and undetermined cases. However, the CRP serum concentrations were significantly higher in children with probable bacterial CAP than in those with probable viral disease (32.2 ± 55.5 mg/L vs 9.4 ± 17.0 mg/L, p < 0.05). The WBC count was the best predictor of severe CAP, but the differences among the studied variables were marginal. The WBC count was significantly lower on day 5 in children with probable bacterial CAP (p < 0.01) and in those with an undetermined etiology (p < 0.01). The CRP and LIP2 levels were significantly lower 5 days after enrollment in all of the studied groups, independent of the supposed etiology of CAP (p < 0.01 for all comparisons). No statistically significant variation was observed for SYN4. CONCLUSIONS: Measuring the LIP2 and SYN4 levels does not appear to solve the problem of the poor reliability of routine laboratory tests in defining the etiology and severity of pediatric CAP. Currently, the CRP levels and WBC, when combined with evaluation of clinical data, can be used to limit the overuse of antibiotics as much as possible and to provide the best treatment to the patient.

The multi-biomarker approach for heart failure in patients with hypertension.

We assessed the predictive ability of selected biomarkers using N-terminal pro-brain natriuretic peptide (NT-proBNP) as the benchmark and tried to establish a multi-biomarker approach to heart failure (HF) in hypertensive patients. In 120 hypertensive patients with or without overt heart failure, the incremental predictive value of the following biomarkers was investigated: Collagen III N-terminal propeptide (PIIINP), cystatin C (CysC), lipocalin-2/NGAL, syndecan-4, tumor necrosis factor-α (TNF-α), interleukin 1 receptor type I (IL1R1), galectin-3, cardiotrophin-1 (CT-1), transforming growth factor ß (TGF-ß) and N-terminal pro-brain natriuretic peptide (NT-proBNP). The highest discriminative value for HF was observed for NT-proBNP (area under the receiver operating characteristic curve (AUC)=0.873) and TGF-ß (AUC=0.878). On the basis of ROC curve analysis we found that CT-1>152 pg/mL, TGF-ß<7.7 ng/mL, syndecan>2.3 ng/mL, NT-proBNP>332.5 pg/mL, CysC>1 mg/L and NGAL>39.9 ng/mL were significant predictors of overt HF. There was only a small improvement in predictive ability of the multi-biomarker panel including the four biomarkers with the best performance in the detection of HF-NT-proBNP, TGF-ß, CT-1, CysC-compared to the panel with NT-proBNP, TGF-ß and CT-1 only. Biomarkers with different pathophysiological backgrounds (NT-proBNP, TGF-ß, CT-1, CysC) give additive prognostic value for incident HF in hypertensive patients compared to NT-proBNP alone.

Serum Syndecan-4 as a Possible Biomarker in Patients With Acute Pneumonia.

BACKGROUND: Syndecan-4 is a transmembrane heparan sulfate proteoglycan expressed in a variety of cells, and glycosaminoglycan side chains of syndecan-4 bind to several proteins, suggesting several biological functions. However, the role of syndecan-4 in acute bacterial pneumonia has not yet been elucidated. METHODS: Serum syndecan-4 levels were measured in patients with acute pneumonia, and the relationships between serum syndecan-4 levels and clinical parameters were analyzed. Next, we treated wild-type and syndecan-4-deficient mice with Streptococcus pneumoniae intranasally and analyzed the phenotype of syndecan-4-deficient mice. RESULTS: In the patients with acute pneumonia, serum syndecan-4 levels were significantly higher than in the healthy volunteers and correlated negatively with the pneumonia severity score. In addition, in patients who improved with short-term antibiotic therapy, serum syndecan-4 levels were higher on admission and gradually increased during antibiotic therapy. Furthermore, in syndecan-4-deficient mice, the survival rate was significantly worse, and total neutrophil counts in bronchoalveolar lavage fluid, bacterial counts in blood, and plasma levels of inflammatory cytokines were significantly higher than in wild-type mice. CONCLUSIONS: These results suggest that syndecan-4 has an anti-inflammatory function in acute pneumonia and could serve as a useful biomarker in these patients.

[Changes and clinical significance of serum level of syndecan-4 protein in patients with chronic congestive heart failure].

OBJECTIVE: To detect serum level of syndecan-4 protein in patients with chronic congestive heart failure (CHF) and investigate its correlation with New York Heart Association (NYHA) class and echocardiographic parameters. METHODS: The concentration of serum syndecan-4 protein was measured by enzyme-linked immunosorbent assay (ELISA) in 40 patients with CHF and 40 healthy controls (NCD), respectively. The parameters such as left ventricle ejection fraction (LVEF), fraction shortening (FS), left ventricle end-diastolic diameter (LVDd), left ventricle end-systolic diameter (LVDs), left ventricle end-diastolic volume (LVEDV) and left ventricle end-systolic volume (LVESV) were detected by echocardiography in 40 patients of CHF. Meanwhile, the patients' cardiac function was graded according to NYHA class. RESULTS: The levels of serum syndecan-4 protein significantly increased in CHF group as compared with control group (P<0.01). In CHF group, as the increased grading of NYHA cardiac function, the levels of serum syndecan-4 protein significantly increased (P<0.05). The more upgraded the NYHA grading, the higher level of serum syndecan-4 protein. In bivariate correlations analysis showed that the level of serum syndecan-4 protein was significantly negatively correlated with LVEF and FS (P<0.05) and was significantly positively correlated with LVDd, LVDs, LVEDV and LVESV, respectively (P<0.05). CONCLUSION: Serum syndecan-4 concentration significantly increased in CHF patients, and it was closely correlated with NYHA class and left ventricle function parameters, so the level of serum syndecan-4 protein may have an important value in detection and surveillance of CHF.

Serum syndecan-4 is a novel biomarker for patients with chronic heart failure.

BACKGROUND: Syndecan-4 is a transmembrane heparan sulfate-carrying glycoprotein that mediates signal transduction pathways activated by growth factors and cell surface receptors, thereby modulating tissue regeneration, angiogenesis, and focal adhesion. The aim of the present study was to determine the clinical use of serum syndecan-4 concentration for diagnosis of heart failure. METHODS: Concentration of serum syndecan-4 and other biomarkers of heart failure was measured in 45 patients with heart failure and 21 healthy subjects. Clinical and echocardiographic parameters of cardiac function were recorded. RESULTS: Serum syndecan-4 concentration significantly increased in proportion to the decrease in ejection fraction (r=-0.599, p<0.001) and increase in the left ventricular (LV) mass index (r=0.315, p<0.05). Serum syndecan-4 concentration was significantly correlated with LV geometrical parameters (i.e. LV mass index, LV end-diastolic volume, and LV dimension), while B-type natriuretic peptide (BNP) was significantly correlated with pressure-related parameters [i.e. early transmitral flow velocity/early diastolic velocity of the mitral valve annulus (E/e'), right ventricular systolic pressure, and left atrial volume index]. Syndecan-4 concentration did not significantly correlate with plasma BNP, transforming growth factor-1, matrix metalloproteinase-2, and tenascin-C concentrations. Serum syndecan-4 concentration could predict cardiac death and re-hospitalization due to heart failure (area under curve, 0.706, p<0.05). CONCLUSION: Serum syndecan-4 concentration shows promise as a novel diagnostic and prognostic biomarker for heart failure. Since syndecan-4 correlated with LV geometrical rather than hemodynamic parameters, serum syndecan-4 may represent a biomarker of LV remodeling in the failing heart.