Detection on Dynamic Changes of Endothelial Cell Specific Molecule–1 in Acute Rejection After Renal Transplantation

Can endocan serve as a molecular "hepatostat" in liver regeneration?

BACKGROUND

Intriguingly, liver regeneration after injury does not induce uncontrolled growth and the underlying mechanisms of such a "hepatostat" are still not clear. Endocan, a proteoglycan, was implicated in liver regeneration. It can support the function of hepatocyte growth factor/scatter factor in tissue repair after injury. Endostatin, a 20 kDa C-terminal fragment of collagen XVIII, may modulate the cessation of liver regeneration. eEF2K, a protein kinase that regulates protein synthesis, can regulate angiogenesis. Thus, we investigated the role of endocan, endostatin and eEF2K during normal liver regeneration.

METHODS

Serum samples and regenerating remnant liver tissues were obtained on various days after partial hepatectomy in rats. mRNA expression levels of Vegf and Pcna were analyzed in addition to immunohistochemical evaluations. Liver tissue protein levels of endostatin, endocan and p-eEF2K/eEF2K were determined with Western blot. Serum levels of endostatin and endocan were assessed with ELISA.

RESULTS

Pcna expression level in residual liver tissues peaked on day-1, while Vegf expression reached its highest level on days 1-3 after partial hepatectomy (70%). Endocan activity declined gradually on days 1-7. The decrease in liver endocan expression was accompanied by an increase in serum endocan levels. Partial hepatectomy induced a rapid increase in liver endostatin levels. Following its surge on day-1, endostatin expression gradually declined, which was accompanied by a peak in serum endostatin. Finally, partial hepatectomy was shown to regulate eEF2K; thus, increasing protein translation.

CONCLUSIONS

We revealed possible mechanistic insights into liver regeneration by examining the associations of Pcna, Vegf, endocan, endostatin, eEF2K with hepatic regeneration after partial hepatectomy. Indeed, endocan might serve as a useful biomarker to monitor clinical prognosis in a plethora of conditions such as recovery of donor's remaining liver after living-donor liver transplant. Whether endocan might represent a strategy to optimize liver regeneration when given therapeutically needs to be investigated in future studies.

Machine learning algorithm-based identification and verification of characteristic genes in acute kidney injury

Background

Acute kidney injury is a common renal disease with high incidence and mortality. Early identification of high-risk acute renal injury patients following renal transplant could improve their prognosis, however, no biomarker exists for early detection.

Methods

The GSE139061 dataset was used to identify hub genes in 86 DEGs between acute kidney injury and control samples using three machine learning algorithms (LASSO, random forest, and support vector machine-recursive feature elimination). We used GSEA to identify the related signal pathways of six hub genes. Finally, we validated these potential biomarkers in an in vitro hypoxia/reoxygenation injury cell model using RT-qPCR.

Results

Six hub genes (MDFI, EHBP1L1, FBXW4, MDM4, RALYL, and ESM1) were identified as potentially predictive of an acute kidney injury. The expression of ESM1 and RALYL were markedly increased in control samples, while EHBP1L1, FBXW4, MDFI, and MDM4 were markedly increased in acute kidney injury samples.

Conclusion

We screened six hub genes related to acute kidney injury using three machine learning algorithms and identified genes with potential diagnostic utility. The hub genes identified in this study might play a significant role in the pathophysiology and progression of AKI. As such, they might be useful for the early diagnosis of AKI and provide the possibility of improving the prognosis of AKI patients.

Endocan in Acute Leukemia: Current Knowledge and Future Perspectives

Endocan is a soluble dermatan sulfate proteoglycan expressed by endothelial cells and detected in serum/plasma. Its expression is increased in tumors/tumor vessels in several human malignancies, and high expression (high serum/plasma levels or tumor levels) has an adverse prognostic impact in several malignancies. The p14 endocan degradation product can also be detected in serum/plasma, but previous clinical studies as well as previously unpublished results presented in this review suggest that endocan and p14 endocan fragment levels reflect different biological characteristics, and the endocan levels seem to reflect the disease heterogeneity in acute leukemia better than the p14 fragment levels. Furthermore, decreased systemic endocan levels in previously immunocompetent sepsis patients are associated with later severe respiratory complications, but it is not known whether this is true also for immunocompromised acute leukemia patients. Finally, endocan is associated with increased early nonrelapse mortality in (acute leukemia) patients receiving allogeneic stem cell transplantation, and this adverse prognostic impact seems to be independent of the adverse impact of excessive fluid overload. Systemic endocan levels may also become important to predict cytokine release syndrome after immunotherapy/haploidentical transplantation, and in the long-term follow-up of acute leukemia survivors with regard to cardiovascular risk. Therapeutic targeting of endocan is now possible, and the possible role of endocan in acute leukemia should be further investigated to clarify whether the therapeutic strategy should also be considered.

Prognostic and Diagnostic Value of Endocan in Kidney Diseases

Endocan, previously called endothelial cell-specific molecule-1, is a soluble proteoglycan that is predominantly expressed in vascular endothelial cells of the lungs and kidneys. It is upregulated by proinflammatory cytokines and plays a critical role in inflammatory, proliferative, and neovascularization processes. The utility of endocan as a biomarker in a wide spectrum of diseases is being increasingly acknowledged. In this review, we summarize the current evidence concerning the role of endocan in kidney diseases, with emphasis on its prognostic and diagnostic value. It seems that the determination of plasma endocan levels may provide useful prognostic information in many types of renal failure such as chronic kidney disease, IgA nephropathy, and diabetic nephropathy. Endocan could additionally improve the early diagnostic evaluation of acute kidney disease, chronic renal allograft injury, and acute rejection after kidney transplantation, thus contributing to endothelial cell injury monitoring in a timely manner.

The Role of Endocan in Selected Kidney Diseases

Endocan, previously referred to as an endothelial-cell-specific molecule-1 (ESM-1) is a member of a proteoglycan family that is secreted by vascular endothelial cells of different organs, mainly lungs and kidneys. It is assumed to participate in endothelial activation and the triggering of inflammatory reactions, especially in microvasculatures. Thanks to its solubility in human fluids, i.e., urine and blood plasma, its stability and its low concentrations in physiological conditions, endocan has been proposed as an easily available, non-invasive biomarker for identifying and predicting the course of many diseases. Recently, endocan has been studied in relation to kidney diseases. In general, endocan levels have been linked to worse clinical outcomes of renal dysfunction; however, results are conflicting and require further evaluation. In this review, authors summarize available knowledge regarding the role of endocan in pathogenesis and progression of selected kidney diseases.

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.

Endocan as a marker of microvascular inflammation in kidney transplant recipients

Endocan is a water-soluble proteoglycan exclusively secreted by vascular endothelium. Endocan levels may be elevated in kidney transplant recipients experiencing antibody-mediated rejection (ABMR), which is characterized by vascular inflammation in transplanted kidney. We evaluated the clinical relevance of endocan as markers of microvascular inflammation in patients who underwent kidney transplantation. Plasma and urinary endocan levels were measured in 203 kidney transplant recipients and were compared across different etiologies of allograft dysfunction and various pathologic scores. Both plasma and urinary endocan levels were significantly higher in patients with acute ABMR than those in patients with normal pathology, acute tubular necrosis (ATN), acute pyelonephritis, BK virus associated nephropathy (BKVN), and T-cell mediated rejection (TCMR). Patients with chronic active ABMR also exhibited significantly higher plasma and urinary endocan levels than patients with long-term graft survival. Scores of glomerulitis and peritubular capillaritis, which are typical features of microvascular inflammation, were significantly elevated in patients with higher plasma and/or urinary endocan levels. Furthermore, plasma and urinary endocan levels could effectively discriminate ABMR from ATN, BKVN, and TCMR. Finally, patients exhibiting high urinary and plasma endocan levels in acute ABMR group showed significantly worse renal survival. Altogether, plasma and urinary endocan levels may serve as potential markers of microvascular inflammation in kidney transplant recipients.

Increase of endocan, a new marker for inflammation and endothelial dysfunction, in acute kidney injury

OBJECTIVE:

In this study, the clinical relevance of the levels of serum endocan and 25-hydroxyvitamin D [25(OH)D] was investigated in patients with acute kidney injury (AKI). Endocan or the endothelial cell-specific molecule 1 is a soluble proteoglycan secreted by vascular endothelial cells. It plays a significant role in immunity, inflammation, and endothelial function.

METHODS:

A total of 39 patients with AKI (19 females, 20 males) and 38 healthy individuals (18 females, 20 males) were included in the study. The levels of serum endocan, vitamin D, and other biochemical parameters were compared between the two groups.

RESULTS:

In the AKI group, the values of serum creatinine, endocan, parathormone, phosphorus, and uric acid were found to be higher, and the total protein, albumin, and calcium levels were lower compared to the control group. There was no difference between the two groups in terms of the serum vitamin D, magnesium, alkaline phosphatase, and gamma-glutamyl transferase.

CONCLUSION:

In patients with AKI, an increased endocan level is a significant marker of inflammation and endothelial injury. In addition, these patients experience vitamin D deficiency.

Endocan Concentration in Kidney Transplant Recipients

INTRODUCTION

Endocan is a novel soluble dermatan sulfate proteoglycan derived from endothelium. It has the capacity of binding to different biologically active molecules associated with cellular signaling, adhesion and regulating proliferation, differentiation, migration, and adhesion of different cell types in health and pathology. Elevated endocan levels are connected with endothelial activation/damage, neo-angiogenesis, and inflammation or carcinogenesis.

MATERIALS AND METHODS

The level of serum endocan among 63 kidney transplant recipients on three immunosuppressives (calcineurin inhibitors, mycophenolate mofetil, steroids) in correlation with other markers of endothelial damage was estimated. Additionally, 22 healthy volunteers were studied. Using a cross-sectional study design, the markers of endothelial damage like endocan, von Willebrand factor (vWF), intracellular adhesion molecule (ICAM), vascular cell adhesion molecule (VCAM); markers of inflammation high-sensitivity C-reactive protein (hsCRP) and IL-6; and marker of kidney function cystatin C were measured using commercially available assays.

RESULTS

Endocan, vWF, IL-6, hsCRP, ICAM, and VCAM levels were significantly higher in kidney transplant recipients comparing to healthy volunteers. In kidney transplant recipients, endocan levels correlated with renal function (estimated glomerular filtration rate by Modification of Diet in Renal Disease, r = -0.24, P < .05, creatinine r = 0.26, P < .05), time after transplantation r = -0.24, P < .05, activity of aspartate aminotransferase r = -0.46, P < .001, alanine aminotransferase r = 0.34, P < .01), ICAM r = -0.53, P < .001, VCAM r = -0.34, P < .01, hsCRP r = 0.35, P < .01, IL-6 r = 0.28, P < .05, vWF r = 0.26, P < .05. In a multifactorial analysis, the predictors of endocan levels were creatinine, ICAM, and VCAM predicting 59% of variability.

CONCLUSION

Endocan concentration among kidney transplant recipients is potentially connected with endothelial damage dependent upon graft function and time after transplantation.

Could "calprotectin" and "endocan" serve as "Troponin of Nephrologists"?

AKI, a serious, common and occasionally under-recognized condition, which is a significant contributor to the growing incidence of CKD and end-stage renal disease (ESRD). To date, the diagnosis of AKI is made by serial measurement of Cr and BUN which are late and imprecise markers of kidney injury. "Calprotectin" and "endocan" are two biomarkers that could reflect renal tubular injury and glomerular/endothelial-vascular damage, respectively. Measurement of urinary calprotectin could help the physicians to diagnose tubular degradation and differentiate prerenal AKI from intrinsic AKI. Serum level of endocan could signify endothelial damage. Herein it is hypothesized that calprotectin and endocan may help the clinicians to diagnose intrinsic AKI, earlier than rise of serum creatinine, differentiate AKI from acute presentation of CKD and also discriminate tubular injury from glomerular/vascular-endothelial injury, assess the prognosis and extent of renal damage and plan for appropriate therapy which may render these biomarkers as potentially applicable equivalents of Troponin in the field of nephrology.

Serum Endocan Levels Associated with Hypertension and Loss of Renal Function in Pediatric Patients after Two Years from Renal Transplant

Endocan is an important biomarker of inflammation and endothelial dysfunction that increases in association with several chronic diseases. Few published data have described the role of endocan in pediatric renal transplant (RT) patients. We evaluated the endocan concentrations in 62 children who underwent renal transplantation and assessed their relationships with the patients' blood pressure and loss of renal function. The endocan levels were significantly elevated in the pediatric RT patients who had hypertension and a loss of renal function. We determined positive correlations between the endocan concentrations and the hemodynamic variables (systolic blood pressure: r = 0.416; P = 0.001; pulse pressure: r = 0.412; P = 0.003). The endocan levels were inversely correlated with the estimated glomerular filtration rate (r = −0.388; P = 0.003). An endocan cutoff concentration of 7.0 ng/mL identified pediatric RT patients who had hypertension and a loss of renal function with 100% sensitivity and 75% specificity. In conclusion, the endocan concentrations were significantly elevated in pediatric RT patients who had both hypertension and a loss of renal function. The correlations between the endocan levels and the hemodynamic variables and the markers of renal function strengthen the hypothesis that it is an important marker of cardiorenal risk.

Vitamin D Treatment Effect on Serum Endocan and High-Sensitivity C-Reactive Protein Levels in Renal Transplant Patients

Context:

Endocan is a marker showing endothelial dysfunction and inflammation. Significantly increased endocan levels have been observed in serum of patients with sepsis and cancer.

Objective:

Our aim was to investigate the relationship between vitamin D treatment and serum endocan and high-sensitivity C-reactive protein (hs-CRP) levels as inflammatory markers in transplant patients.

Design:

Prospective.

Setting:

Nephrology clinic.

Patients:

Thirty-eight renal transplant patients with serum 25-hydroxy-vitamin D (25-OH-vitamin D) levels below 20 ng/mL and transplanted at least 12 months.

Intervention:

One-time oral dose of 300 000 IU vitamin D3.

Main Outcome Measures:

Before and after vitamin D treatment, serum endocan, hs-CRP, calcium, phosphorus, and parathyroid hormone (PTH) levels were measured.

Results:

Median serum endocan and PTH values before vitamin D were significantly higher than those of after treatment values ( P = .001 and P < .001, respectively). On the other hand, serum total calcium and phosphorus levels before vitamin D treatment were lower than the values obtained after vitamin D treatment ( P = .0013 and P < .001, respectively). Serum hs-CRP was lower after vitamin D therapy than before, but the difference was not statistically significant ( P = .06). A moderate negative correlation was determined between endocan and 25-OH-vitamin D levels after treatment with vitamin D ( r = −.36, P = .02).

Conclusion:

This study has revealed that vitamin D treatment reduced markers of endothelial dysfunction in patients with renal transplantation and vitamin D deficiency.

Endocan Concentration and Chronic Inflammatory Process Among Heart Transplant Recipients

BACKGROUND

Endocan is a novel soluble dermatan sulfate proteoglycan derived from endothelium. It has the capacity of binding to different biologically active molecules associated with cellular signaling, adhesion, and regulating proliferation, differentiation, migration, and adhesion of different cell types in health and pathology. Its elevated level is connected with endothelial activation, neovascularization, and inflammation or carcinogenesis.

METHODS

The level of serum endocan among 131 heart transplant recipients on 3-drug immunosuppression (calcineurin inhibitor, mycophenolate mofetil/mycophenolic acid, steroid) in correlation with other markers of endothelial damage was determined. In addition, 22 healthy volunteers were studied. In cross-sectional study, markers were measured with the use of commercially available assays of endothelial damage-endocan and von Willebrand factor (VWF)-inflammation-high-sensitivity C-reactive protein (hsCRP), interleukin (IL) 6-and kidney function-cystatin C.

RESULTS

The endocan, VWF, IL-6, hsCRP, and cystatin C levels were significantly higher in heart transplant recipients compared with healthy volunteers. In our cohort, endocan level was correlated with renal function (estimated glomerular filtration rate: r = -0.21; P < .05), creatinine (r = 0.21; P < .05), erythrocyte count (r = -0.24; P < .01), hemoglobin (r = -0.33; P < .01), N-terminal pro-B-type natriuretic peptide (r = 0.25; P < .01), cholesterol (r = -0.22; P < .05), LDL (r = -0.21; P < .05), New York Heart Association functional class (r = 0.21; P < .05), hsCRP (r = 0.32; P < .01), IL-6 (r = 0.31; P < .01), and VWF (r = 0.27; P < .01). In multifactorial analysis, the predictors of endocan levels were cholesterol level, cystatin C, and IL-6, predicting 54% of variability.

CONCLUSIONS

Endocan concentration among heart transplant recipients is potentially connected with endothelial damage caused by subclinical inflammation resulting from hyperlipidemia.

An Insight Into the Immunologic Events and Risk Assessment in Renal Transplantation

Organ transplantation has always been considered to be the optimal therapeutic intervention in patients with end-stage organ failure. In the US, approximately 615,000 patients are diagnosed with end-stage renal disease and less than 30% have received a kidney transplant. One of the crucial drawbacks in successful renal transplantation is allograft rejection. Survival rates among transplant recipients have greatly improved due to better understanding of transplant biology and more effective immunosuppressive agents. Post-transplant immune monitoring and optimization of the immunosuppressive therapy using non-invasive biomarkers can effectively predict impending graft rejection and may spare the need for renal biopsy. This article provides an insight into the immunomodulations of renal transplant recipients. It depicts the immune system including several types of kidney rejection and reviews the biomarkers that may serve in near future, as surveillance tools for graft monitoring. Finally, a summary on the main immunosuppressive drugs used in kidney transplant both in the induction and maintenance phases is also covered.

Endocan as a potential diagnostic or prognostic biomarker for chronic kidney disease

Developing specific markers for early detection of adverse events such as kidney failure, cardiovascular events, and all-cause mortality in chronic kidney disease (CKD) patients remains a major challenge. Cardiovascular events are the main cause of morbidity and mortality in CKD patients. Recent research supposes endocan as a biomarker for evaluating cardiovascular events, inflammatory diseases, and cancers. Yilmaz et al. propose serum endocan levels as a novel prediction marker of all-cause mortality and cardiovascular events in CKD patients.

Effect of Glycemic Regulation on Endocan Levels in Patients With Diabetes

Endothelial-specific molecule 1 (endocan) is expressed by endothelial cells and may have a major role in the regulation of cell adhesion and in the pathogenesis of inflammatory disorders. We aimed to assess change in endocan levels after 3 months of lifestyle change recommendations and guideline-based treatment. Diabetic patients (n = 77) who had neither chronic kidney disease nor chronic inflammatory disease were included. After baseline evaluation, the patients were advised lifestyle changes, and their medical treatment was determined individually according to recommendations of the American Diabetes Association (ADA) guidelines. At the end of third month patients were reevaluated. Baseline endocan levels were significantly increased in the study group compared with the control group. The third-month laboratory workup showed significant reductions in hemoglobin A1c, urinary albumin-to-creatinine ratio (UACR), and endocan levels. Only δ-UACR was independently correlated with δ-endocan in multivariate linear regression analysis. Our findings suggest that serum endocan concentrations are elevated in patients with type 2 diabetes and decrease following anti-hyperglycemic treatment. Furthermore, decrease in endocan concentrations might be associated with improved glycemic control and reductions in UACR.

Endocan: A new marker for cancer and a target for cancer therapy

Endocan, previously known as endothelial cell-specific molecule-1 (ESM-1), was cloned from the human umbilical vein endothelial cell cDNA library. Endocan is a novel ESM, and a 50 kDa soluble proteoglycan. Endocan is secreted into the blood as the soluble proteoglycan, which is the form in the presence of chondroitin sulfate. In normal tissues, chondroitin sulfate/dermatan sulfate proteoglycan is expressed by endothelial cells (such as lung and kidney) and is overexpressed in several carcinoma endothelial cells. There are studies that identified high endocan expression in lung cancer, uterine cancer, kidney cancer, liver cancer, brain glioblastoma, breast cancer and other tumors. Tumor prognosis, metastasis and angiogenesis were shown to be associated with endocan expression. The majority of investigators believe that endocan regulates the tumor by tumor-associated inflammation, angiogenesis, lymphangiogenesis, the tumor cells themselves and other aspects. Endocan may be a new target for cancer therapy.

Endocan: a new molecule playing a role in the development of hypertension and chronic kidney disease?

Recently, endocan-formerly known as endothelial cell-specific molecule 1 (ESM-1)--was found to be associated with entities such as cancer, hypertension, renal transplant rejection, and chronic renal failure. Endothelial cells of many organs secrete endocan, but the exact functions of this relatively new molecule have not been elucidated completely. Emerging evidence suggests, however, that endocan plays an important role in inflammation, upregulation of cell adhesion molecules, lymphocyte functions, and endothelial cytoskeleton rearrangement. As suggested above, endocan has a prognostic impact in hypertension, transplant rejection, and chronic renal failure. In the current review, the evidence regarding endocan, hypertension, and chronic renal failure are summarized.