The non glycanated endocan polypeptide slows tumor growth by inducing stromal inflammatory reaction

Evaluation of Endocan as a Treatment for Acute Inflammatory Respiratory Failure

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a life-threatening condition resulting from acute pulmonary inflammation. However, no specific treatment for ARDS has yet been developed. Previous findings suggest that lung injuries related to ARDS could be regulated by endocan (Esm-1). The aim of this study was to evaluate the potential efficiency of endocan in the treatment of ARDS.

METHODS

We first compared the features of acute pulmonary inflammation and the severity of hypoxemia in a tracheal LPS-induced acute lung injury (ALI) model performed in knockout (Esm1^-/-) and wild type (WT) littermate C57Bl/6 mice. Next, we assessed the effects of a continuous infusion of glycosylated murine endocan in our ALI model in Esm1^-/- mice.

RESULTS

In our ALI model, we report higher alveolar leukocytes (p < 0.001), neutrophils (p < 0.001), and MPO (p < 0.001), and lower blood oxygenation (p < 0.001) in Esm1^-/- mice compared to WT mice. Continuous delivery of glycosylated murine endocan after LPS-induced ALI resulted in decreased alveolar leukocytes (p = 0.012) and neutrophils (p = 0.012), higher blood oxygenation levels (p < 0.001), and reduced histological lung injury (p = 0.04), compared to mice treated with PBS.

CONCLUSIONS

Endocan appears to be an effective treatment in an ARDS-like model in C57Bl/6 mice.

Tumor-Associated Extracellular Matrix: How to Be a Potential Aide to Anti-tumor Immunotherapy?

The development of cancer immunotherapy, particularly immune checkpoint blockade therapy, has made major breakthroughs in the therapy of cancers. However, less than one-third of the cancer patients obtain significant and long-lasting therapeutic effects by cancer immunotherapy. Over the past few decades, cancer-related inflammations have been gradually more familiar to us. It’s known that chronic inflammation in tumor microenvironment (TME) plays a predominant role in tumor immunosuppression. Tumor-associated extracellular matrix (ECM), as a core member of TME, has been a research hotspot recently. A growing number of studies indicate that tumor-associated ECM is one of the major obstacles to realizing more successful cases of cancer immunotherapy. In this review, we discussed the potential application of tumor-associated ECM in the cancer immunity and its aide potentialities to anti-tumor immunotherapy.

Diagnostic and Prognostic Value of Serum Endocan Levels in Patients With COVID-19

We aimed to evaluate whether there was a relationship between endocan (human endothelial cell-specific molecule-1) levels and disease prognosis in patients who presented to the emergency department with coronavirus disease 2019 (COVID-19). A total of 60 patients with COVID-19 who were hospitalized from the emergency department to clinical wards and a control group consisting of healthy adult individuals (n = 28), were included in the study. The majority (93.3%) of the patients were discharged after recovery; 6.7% died. The median endocan value was 243.5 ng/mL in the patient group versus 201.5 ng/mL in the control group (P = .002). The median endocan level was 240.5 ng/mL in those discharged with recovery and 558 ng/mL in those who died (P = .001). There was no significant relationship in hospitalization duration, sex, tomography findings, and clinical outcomes. A 202 ng/mL serum endocan level had 86.7% sensitivity and 50% specificity for COVID-19. Serum endocan levels may be a useful biomarker both for the diagnosis of COVID-19 and to predict mortality.

Cleaved endocan acts as a biologic competitor of endocan in the control of ICAM-1-dependent leukocyte diapedesis

Dysregulated leukocyte diapedesis is a major contributor to acute severe inflammatory states like sepsis and acute respiratory distress syndrome, which are common conditions in critically ill subjects. Endocan is a circulating proteoglycan that binds to the leukocyte integrin LFA-1 and blocks its interaction with its endothelial ligand ICAM-1, subsequently leading to the inhibition of leukocyte recruitment. Recent data have highlighted the hypothetic role of p14, endocan's major catabolite found in the bloodstream of septic patients, as a potential antagonist of endocan, thus participating in the regulation of acute inflammation. We hereby characterize the role of p14 as a biologic competitor of endocan, through assessment of its molecular interactions with LFA-1, endocan, and ICAM-1, as well as its effects on human leukocyte trafficking. Using immunodetection assay, we report that p14 can bind to LFA-1, thus inhibiting the interaction between LFA-1 and endocan, which in turn leads to the restoration of the ICAM-1/LFA-1 interaction. In primary human T cells trafficking assays, we underline the absence of effect of p14 on ICAM-1-dependent adhesion and migration, as well as on transendothelial migration. However, in those models, p14 reverses the antimigratory effect of endocan. To conclude, our study supports the hypothesis of an antagonistic role of p14 versus endocan in its effect on the LFA-1/ICAM-1-dependent human leukocyte recruitment.

Prediction and identification of novel HLA-A*0201-restricted cytotoxic T lymphocyte epitopes from endocan

Background

Prediction and identification of cytotoxic T lymphocyte (CTL) epitopes from tumor associated antigens is a crucial step for the development of tumor immunotherapy strategy. Endocan has been identified as antigen overexpressed in various tumors.

Methods

In this experiment, we predicted and identified HLA-A2-restricted CTL epitopes from endocan by using the following procedures. Firstly, we predicted the epitopes from the amino acid sequence of endocan by computer-based methods; Secondly, we determined the affinity of the predicted peptide with HLA-A2.1 molecule by peptide-binding assay; Thirdly, we elicited the primary T cell response against the predicted peptides in vitro; Lastly, we tested the specific CTLs toward endocan and HLA-A2.1 positive target cells.

Results

These data demonstrated that peptides of endocan containing residues 4–12 and 9–17 could elicit specific CTLs producing interferon-γ and cytotoxicity.

Conclusions

Therefore, our findings suggested that the predicted peptides were novel HLA-A2.1-restricted CTL epitopes, and might provide promising target for tumor immunotherapy.

Endocan regulates acute lung inflammation through control of leukocyte diapedesis

Acute respiratory distress syndrome is a severe form of respiratory failure, occurring in up to 20% of patients admitted to the intensive care unit with sepsis. Dysregulated leukocyte diapedesis is a major contributor to acute respiratory distress syndrome. Endocan is a circulating proteoglycan that binds to the leukocyte integrin leukocyte functional antigen-1 and blocks its interaction with its endothelial ligand, ICAM-1. The objective of this study was to evaluate the role of endocan in the control of acute lung inflammation. In vitro, endocan inhibited human leukocyte transendothelial migration as well as ICAM-1-dependent migration but had a very mild effect on ICAM-1-dependent adhesion. Endocan also acted as an inhibitor of transendothelial migration of mouse leukocytes. The effect of systemic administration of recombinant human endocan was assessed in a model of acute lung inflammation in BALB/c mice. Treatment with endocan 1 h after intratracheal LPS challenge reduced the alveolar inflammatory response, diminished histological features of acute lung injury, and improved respiratory function. These results highlight the anti-inflammatory role of human endocan and its protective effect against acute lung injury.NEW & NOTEWORTHY We show here that endocan inhibits ICAM-1-dependent human leukocyte transendothelial migration and ICAM-1-dependent adhesion. We also found that in BALB/c mice with tracheal LPS-induced acute lung injury treatment with recombinant human endocan reduces lung inflammation, notably through reduction of neutrophilic recruitment, and restores normal lung function. These results confirm the hypothesis that human endocan may have a protective effect against acute lung inflammation.

Proteoglycans and Immunobiology of Cancer-Therapeutic Implications

Disparity during the resolution of inflammation is closely related with the initiation and progression of the tumorigenesis. The transformed cells, through continuously evolving interactions, participate in various exchanges with the surrounding microenvironment consisting of extracellular matrix (ECM) components, cytokines embedded in the ECM, as well as the stromal cells. Proteoglycans (PGs), complex molecules consisting of a protein core into which one or more glycosaminoglycan (GAG) chains are covalently tethered, are important regulators of the cell/matrix interface and, consecutively, biological functions. The discrete expression of PGs and their interacting partners has been distinguished as specific for disease development in diverse cancer types. In this mini-review, we will critically discuss the roles of PGs in the complex processes of cancer-associated modulation of the immune response and analyze their mechanisms of action. A deeper understanding of mechanisms which are capable of regulating the immune response could be harnessed to treat malignant disease.

Endocan, sepsis, pneumonia, and acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) and hospital-acquired pneumonia (HAP) are major problems of public health in intensive care units (ICUs), occurring in 15% of critically ill patients. Among the factors explaining ARDS development, sepsis is known as a frequent cause. Sepsis, ARDS, and HAP increase morbidity, mortality, length of stay in the ICU, and the overall costs of healthcare. The major challenge remains to identify accurately among critically ill patients those at risk of poor outcomes who could benefit from novel therapies. Endocan is released by the pulmonary endothelium in response to local or systemic injury. It inhibits mainly leukocyte diapedesis rather than leukocyte rolling or adhesion to the endothelial cells both in vitro and in vivo. Endocan was evaluated in 25 clinical reports, including 2454 critically ill patients and 452 healthy controls. The diagnostic value of endocan for sepsis or sepsis severity was equal to procalcitonin but its prognostic value was better. A predictive value for postoperative pneumonia was evidenced in two studies, and a predictive value for ARDS in four studies from three independent centers. This review presents an overview of the structure, expression, and functions of endocan. We also hereby summarize the potential applications of endocan in the prediction and prognosis of ARDS and HAP, as well as in the prognosis of sepsis.

Is Endocan a Diagnostic Marker for Pneumonia After Cardiac Surgery? The ENDOLUNG Study

BACKGROUND

Postoperative pneumonia is frequent after cardiac surgery and is associated with increased morbidity and mortality. We tested the hypothesis that endocan is an early biomarker for the detection of pneumonia after cardiac surgery.

METHODS

Between January and May 2016, 155 patients scheduled to undergo elective cardiac surgery with cardiopulmonary bypass were prospectively included in the study. Serum level of endocan was measured at five timepoints (preoperative, and at 6, 24, 48, and 72 hours after the end of surgery). Procalcitonin and C-reactive protein were measured at 24 and 72 hours. The preoperative and postoperative characteristics of the patients were recorded. Independent predictors of postoperative pneumonia were identified by logistic regression. Threshold values of endocan predictive of postoperative pneumonia were determined using receiver-operating characteristics curve analysis.

RESULTS

Seventeen patients (11%) had pneumonia after surgery. Endocan greater than 3.7 ng/mL before induction of anesthesia, or greater than 12.1 ng/mL at 6 hours after surgery, as well body mass index higher than 27 kg/m² and duration of surgery were independent predictors of postoperative pneumonia. At induction of anesthesia, an endocan cutoff value of 3.7 ng/mL had 65% sensitivity and 72% specificity for the prediction of postoperative pneumonia; whereas at 6 hours, with a cutoff value of 12.1 ng/mL, these values were 71% and 75%, respectively. The time saved by endocan dosage compared with clinical diagnosis of postoperative pneumonia was 96 hours.

CONCLUSIONS

This study shows that endocan is an early marker of postoperative pneumonia in patients after cardiac surgery.

Loss of endothelial cell-specific molecule 1 promotes the tumorigenicity and metastasis of prostate cancer cells through regulation of the TIMP-1/MMP-9 expression

The Endothelial cell specific molecule-1 (ESM1) protein has been involved in proliferation and metastatic progression in multiple tumors. However, there are no studies regarding the mechanism of ESM1 in prostate cancer. We found that ESM1 knockdown in prostate cancer cells resulted in increased cell proliferation and colony formation ability response evidenced by decreased expression of p21 and increased expression of cyclin D1 in prostate cancer cells. Moreover, we revealed that knockdown ESM1 also induced the epithelial-mesenchymal transition (EMT), motility and invasiveness in accordance with the upregulated the MMP-9 expression, while downregulated the TIMP-1 expression. Recombinant human (Rh) TIMP-1 significantly attenuated ESM1-mediated cell migration and invasion. Additionally, ESM1 knockdown increased in vivo tumorigenicity and metastasis of prostate cancer cells. These findings provide the first evidence that the imbalance of MMP-9/TIMP-1, is one of the regulation mechanisms by which ESM1 promotes tumorigenicity and metastasis of prostate cancer cells.

Endocan as a prognostic biomarker of triple-negative breast cancer

PURPOSE

Triple-negative breast cancer (TNBC) has aggressive characteristics and fewer treatment options than other subtypes. The purpose of this study was to explore prognostic biomarkers for TNBC that can be easily detected from the blood samples.

METHODS

MDA-MB-231 and MDA-MB-231BR, a brain metastatic variant of the human TNBC cell line MDA-MB-231, were used as less and more aggressive models of TNBC, respectively. The extent to which the candidate gene/protein identified by RNA sequencing correlated well with aggressiveness of TNBC and how much protein was detected from the blood of tumor-bearing mice were evaluated.

RESULTS

Both the in vitro proliferation and in vivo tumor growth of MDA-MB-231BR were more rapid than those of MDA-MB-231. RNA sequencing identified ESM1 as a gene that was expressed significantly more in MDA-MB-231BR than in MDA-MB-231, and qRT-PCR confirmed a significantly higher expression of ESM1 in MDA-MB-231BR xenograft in vivo. Furthermore, Kaplan-Meier analysis of relapse-free survival demonstrated that TNBC patients with high ESM1 expression had clearly worse relapse-free survival than those with low ESM1 expression, which was consistent with our preclinical findings. Endocan, a protein of ESM1 gene product, was successfully detected in both conditioned medium from MDA-MB-231BR and plasma samples from mice bearing MDA-MB-231BR xenograft, which showed a significantly distinct pattern from less aggressive MDA-MB-231. Moreover, bisulfite sequence analysis revealed that overexpression of ESM1 in MDA-MB-231BR might be attributed to DNA demethylation in an upstream region of the ESM1 gene.

CONCLUSION

This study indicates that endocan could be used as a blood-based prognostic biomarker in TNBC patients.