Endoglin and soluble endoglin in liver sinusoidal endothelial dysfunction in vivo.

Liver sinusoidal endothelial cells (LSECs) play a crucial role in regulating the hepatic function. Endoglin (ENG), a transmembrane glycoprotein, was shown to be related to the development of endothelial dysfunction. In this study, we hypothesized the relationship between changes in ENG expression and markers of liver sinusoidal endothelial dysfunction (LSED) during liver impairment. Male C57BL/6J mice aged 9-12 weeks were fed with 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) diet (intrahepatic cholestasis) or choline-deficient l-amino acid defined high-fat diet (CDAA-HFD) (non-alcoholic steatohepatitis (NASH)). Significant increases in liver enzymes, fibrosis, and inflammation biomarkers were observed in both cholestasis and NASH. Decreased p-eNOS/eNOS and VE-cadherin protein expression and a significant increase in VCAM-1 and ICAM-1 expression were detected, indicating LSED in both mouse models of liver damage. A significant reduction of ENG in the DDC-fed mice, while a significant increase of ENG in the CDAA-HFD group was observed. Both DDC and CDAA-HFD-fed mice showed a significant increase in MMP-14 protein expression, which is related to significantly increased levels of soluble endoglin (sENG) in the plasma. In conclusion, we demonstrated that intrahepatic cholestasis and NASH result in an altered ENG expression, predominantly in LSECs, suggesting a critical role of ENG expression for the proper function of liver sinusoids. Both pathologies resulted in elevated sENG levels, cleaved by MMP-14 expressed predominantly from LSECs, indicating sENG as a liver injury biomarker.

Protective potential of different compounds and their combinations with MESNA against sulfur mustard-induced cytotoxicity and genotoxicity.

The purpose of this study was to evaluate the efficacy of potential candidate molecules or their combinations against strong alkylation agent sulfur mustard (SM) on the human lung alveolar epithelial cell line A-549. Candidate molecules were chosen on the basis of their previously observed protective effects in vitro. The tested compounds, including antioxidants, sulfhydryl or other sulfur-containing molecules, nitrogen-containing molecules, PARP inhibitors and a NO synthase inhibitor, were applicated 30min before SM treatment. The efficiency of candidate molecules to protect cells against DNA damage and cell death induced by SM was determined using single-cell gel electrophoresis (comet assay) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction by viable cells. The damage of DNA was assessed 1 and 24h after dose 50µM SM. Cell survival was assessed 24 and 72h after the exposure. To achieve maximal cytoprotection, combinations of selected compounds with sodium 2-mercaptoethane sulphonate (MESNA) were tested. We found significant protective effects by several drugs used individually and also in combination with MESNA. High protection was achieved by sodium thiosulphate, which was further potentiated when combined with MESNA. Most of the selected compounds or mixture provided only moderate genoptotection without having any effect towards cell viability.

High soluble endoglin levels do not induce changes in structural parameters of mouse heart.

A soluble form of endoglin (sEng) released into the circulation was suggested to be a direct inducer of endothelial dysfunction, inflammation and contributed to the development of hypertension by interfering with TGF-ß signaling in cardiovascular pathologies. In the present study, we assessed the hypothesis that high sEng level-induced hypertension via a possible sEng interference with TGF-ß signaling pathways may result in inflammatory, structural or fibrotic changes in hearts of Sol-Eng+ mice (mice with high levels of soluble endoglin) fed either chow or high-fat diet. Female Sol-Eng+ mice and their age matched littermates with low plasma levels of sEng were fed either chow or high-fat diet (HFD). Heart samples were subsequently analyzed by histology, qRT-PCR and Western blot analysis. In this study, no differences in myocardial morphology/hypertrophy and possible fibrotic changes between Sol-Eng+ mice and control mice were detected on both chow and HFD. The presence of sEng did not significantly affect the expression of selected members of TGF-ß signaling (membrane endoglin, TGFßRII, ALK-5, ALK-1, Id-1, PAI-1 and activated Smad proteins-pSmad 1,5 and pSmad 2,3), inflammation, heart remodeling (PDGFb, Col1A1) and endothelial dysfunction (VCAM-1, ICAM-1) in the hearts of Sol-Eng+ mice compared to control mice on both chow and high-fat diet. High levels of soluble endoglin did not affect microscopic structure (profibrotic and degenerative cardiomyocyte changes), and specific parts of TGF-ß signaling, endothelial function and inflammation in the heart of Sol-Eng+ mice fed both chow diet or HFD. However, we cannot rule out a possibility that a long-term chronic exposure (9 months and more) to soluble endoglin alone or combined with other cardiovascular risk factors may contribute to alterations of heart function and structure in Sol-Eng+ mice, which is the topic in our lab in ongoing experiments.

Soluble endoglin modulates the pro-inflammatory mediators NF-κB and IL-6 in cultured human endothelial cells.

AIMS: Endoglin is a transmembrane glycoprotein, that plays an important role in regulating endothelium. Proteolytic cleavage of membrane endoglin releases soluble endoglin (sEng), whose increased plasma levels have been detected in diseases related to the cardiovascular system. It was proposed that sEng might damage vascular endothelium, but detailed information about the potential mechanisms involved is not available. Thus, we hypothesized that sEng contributes to endothelial dysfunction, leading to a pro-inflammatory phenotype by a possible modulation of the TGF-ß and/or inflammatory pathways. MAIN METHODS: Human umbilical vein endothelial cells (HUVECs) and Human embryonic kidney cell line (HEK293T) were treated with different sEng concentration and time in order to reveal possible effect on biomarkers of inflammation and TGF-ß signaling. IL6 and NFκB reporter luciferase assays, quantitative real-time PCR analysis, Western blot analysis and immunofluorescence flow cytometry were used. KEY FINDINGS: sEng treatment results in activation of NF-κB/IL-6 expression, increased expression of membrane endoglin and reduced expression of Id-1. On the other hand, no significant effects on other markers of endothelial dysfunction and inflammation, including eNOS, peNOSS1177, VCAM-1, COX-1, COX-2 and ICAM-1 were detected. SIGNIFICANCE: As a conclusion, sEng treatment resulted in an activation of NF-κB, IL-6, suggesting activation of pro-inflammatory phenotype in endothelial cells. The precise mechanism of this activation and its consequence remains to be elucidated. A combined treatment of sEng with other cardiovascular risk factors will be necessary in order to reveal whether sEng is not only a biomarker of cardiovascular diseases, but also a protagonist of endothelial dysfunction.

High Levels of Soluble Endoglin Induce a Proinflammatory and Oxidative-Stress Phenotype Associated with Preserved NO-Dependent Vasodilatation in Aortas from Mice Fed a High-Fat Diet.

AIMS: A soluble form of endoglin (sEng) was proposed to participate in the induction of endothelial dysfunction in small blood vessels. Here, we tested the hypothesis that high levels of sEng combined with a high-fat diet induce endothelial dysfunction in an atherosclerosis-prone aorta. METHODS AND RESULTS: Six-month-old female and male transgenic mice overexpressing human sEng (Sol-Eng+) with low (Sol-Eng+low) or high (Sol-Eng+high) levels of plasma sEng were fed a high-fat rodent diet containing 1.25% cholesterol and 40% fat for 3 months. The plasma cholesterol and mouse sEng levels did not differ in the Sol-Eng+high and Sol-Eng+low mice. The expression of proinflammatory (P-selectin, ICAM-1, pNFκB and COX-2) and oxidative-stress-related markers (HO-1, NOX-1 and NOX-2) in the aortas of Sol-Eng+high female mice was significantly higher than in Sol-Eng+low female mice. Endothelium-dependent vasodilatation induced by acetylcholine was preserved better in the Sol-Eng+ high female mice than in the Sol-Eng+low female mice. CONCLUSION: These results suggest that high concentrations of sEng in plasma in combination with a high-fat diet induce the simultaneous activation of proinflammatory, pro-oxidative and vasoprotective mechanisms in mice aorta and the balance of these biological processes determines whether the final endothelial phenotype is adaptive or maladaptive.

High soluble endoglin levels do not induce endothelial dysfunction in mouse aorta.

Increased levels of a soluble form of endoglin (sEng) circulating in plasma have been detected in various pathological conditions related to cardiovascular system. High concentration of sEng was also proposed to contribute to the development of endothelial dysfunction, but there is no direct evidence to support this hypothesis. Therefore, in the present work we analyzed whether high sEng levels induce endothelial dysfunction in aorta by using transgenic mice with high expression of human sEng. Transgenic mice with high expression of human sEng on CBAxC57Bl/6J background (Sol-Eng+) and age-matched transgenic littermates that do not develop high levels of human soluble endoglin (control animals in this study) on chow diet were used. As expected, male and female Sol-Eng+ transgenic mice showed higher levels of plasma concentrations of human sEng as well as increased blood arterial pressure, as compared to control animals. Functional analysis either in vivo or ex vivo in isolated aorta demonstrated that the endothelium-dependent vascular function was similar in Sol-Eng+ and control mice. In addition, Western blot analysis showed no differences between Sol-Eng+ and control mice in the protein expression levels of endoglin, endothelial NO-synthase (eNOS) and pro-inflammatory ICAM-1 and VCAM-1 from aorta. Our results demonstrate that high levels of soluble endoglin alone do not induce endothelial dysfunction in Sol-Eng+ mice. However, these data do not rule out the possibility that soluble endoglin might contribute to alteration of endothelial function in combination with other risk factors related to cardiovascular disorders.

DNA crosslinks, DNA damage and repair in peripheral blood lymphocytes of non-small cell lung cancer patients treated with platinum derivatives.

Lung cancer is the leading cause of cancer-related mortality in the world. Chemotherapy has been the mainstay of treatment for advanced non-small cell lung cancer (NSCLC) and platinum-based derivatives have been shown to improve overall survival. The aim of the present study was to investigate the DNA damage [single strand breaks (SSBs) and DNA crosslinks] and DNA repair in peripheral blood lymphocytes in patients with NSCLC treated with platinum derivatives using modified comet assay. Twenty patients in the final (4th) stage of NSCLC and 10 age-corresponding healthy controls participated in the study. Alkaline comet assay was performed according to the appropriate protocol. The DNA base excision repair (BER) activity of the controls was significantly higher compared to that of cancer patients, and the activity of DNA nucleotide excision repair (NER) was almost at the same level both in controls and patients. We observed changes in the amount of SSBs and DNA crosslinks during the course of chemotherapy. We found a significantly higher level of SSBs immediately after administration of chemotherapy. Similarly, we found the highest incidence of DNA crosslinks immediately or 1 day after chemotherapy (compared to measurement before chemotherapy). Moreover, we compared the levels of DNA repair in patients who survived chemotherapy with those in patients who died in the course of chemotherapy: the activity of BER was higher in the case of surviving patients, while the levels of NER were essentially the same. The data arising from the present study confirm the findings of other studies dealing with DNA damage and repair in cancer patients treated with chemotherapy. Moreover, our results indicated that despite the fact that cisplatin-DNA adducts are removed by the NER pathway, BER may also play a role in the clinical status of patients and their survival.

Application of the comet assay method in clinical studies.

The comet assay or single-cell gel electrophoresis (SCGE) assay is now widely accepted as a standard method for assessing DNA damage in individual cells. It finds use in a broad variety of applications including human biomonitoring, genotoxicology, ecological monitoring and as a tool for investigation of DNA damage and repair in different cell types in response to a range of DNA-damaging agents. The comet assay should be eminently suitable for use in clinical practice since it is a relatively simple and inexpensive technique which requires only a few cells, and results can be obtained within a matter of hours. This method can be used in the study of cancer as well as in lifestyle and dietary studies. In cancer it is useful for measuring DNA damage before, throughout and after therapy (either radiotherapy or chemotherapy). Another use of this method is in lifestyle study, such as investigation of the effect on DNA of common human activities (e.g. smoking, or working with a potentially genotoxic agent). The final use of comet assay in this paper is dietary study. In this type of study we observe the effects of consumption of specific foods or supplements which may be protective for DNA against damage.