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.

Soluble endoglin, hypercholesterolemia and endothelial dysfunction.

A soluble form of endoglin (sEng) is known to be an extracellular domain of the full-length membrane endoglin, which is elevated during various pathological conditions related to vascular endothelium. In the current review, we tried to summarize a possible role of soluble endoglin in cardiovascular pathologies, focusing on its relation to endothelial dysfunction and cholesterol levels. We discussed sEng as a proposed biomarker of cardiovascular disease progression, cardiovascular disease treatment and endothelial dysfunction. We also addressed a potential interaction of sEng with TGF-ß/eNOS or BMP-9 signaling. We suggest soluble endoglin levels to be monitored, because they reflect the progression/treatment efficacy of cardiovascular diseases related to endothelial dysfunction and hypercholesterolemia. A possible role of soluble endoglin as an inducer of endothelial dysfunction however remains to be elucidated.

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.

Endoglin is not expressed with cell adhesion molecules in aorta during atherogenesis in apoE-deficient mice.

Endoglin (TGF-ß receptor III), has been demonstrated to affect vascular endothelium and atherosclerosis. Moreover, it was also demonstrated that endoglin is involved in inflammation and plays a role in leukocyte adhesion and transmigration in vitro and in vivo but not in atherosclerosis related vessels. In this study, we wanted to evaluate endoglin expression in two different parts of the aorta (heart aortic sinus and ascending aorta) and assess its potential simultaneous expression with cell adhesion molecules in non-atherosclerotic and atherosclerotic aortas of apoE-deficient mice. Ten-week-old female apolipoprotein E-deficient mice on a C57BL/6J background (n=24) were randomly subdivided into three groups and were fed either chow diet (for another two months) or Western type diet (for another two or four months). Immunohistochemical staining of endoglin, VCAM-1 and P-selectin in aortic sinus and ascending aorta was performed. Endoglin expression was detected only in endothelial cells and varied during atherogenic process in aorta but not in aortic sinus. Moreover, its expression seemed to be weaker in aorta when compared to aortic sinus and the positivity was detected only in endothelium covering atherosclerotic lesions but not in non-atherosclerotic endothelium regardless of the plaque size. Endoglin was not expressed with P selectin and VCAM-1 in aortic endothelium in any studied group. This study shows that endothelial expression of endoglin is related to the atherogenic process predominantly in aorta outside the heart. Moreover, endoglin is not localized with cell adhesion molecules involved in atherosclerosis, suggesting it might not participate in leukocyte accumulation in aorta of apoE-deficient mice during atherogenesis.

Cell adhesion molecules and eNOS expression in aorta of normocholesterolemic mice with different predispositions to atherosclerosis.

C57BL/6J (B6) mice were demonstrated to be the most susceptible and C3H/HeJ (C3H) mice the most resistant to development of atherosclerosis. We hypothesized, whether pro-atherogenic (P-selectin, VCAM-1, and ICAM-1) and anti-atherogenic (endoglin and eNOS) proteins are expressed differently in aorta before the onset of atherosclerosis in these two mouse strains. B6 mice (n = 16) and C3H mice (n = 16) sustained on either chow or cholesterol (1 %) diet for 8 weeks. Biochemical analysis of lipoprotein profile and Western blot analysis of P-selectin, VCAM-1, ICAM-1, eNOS, endoglin, peNOS and TGF-ßRII in aorta were performed. Western blot analysis revealed a lower expression of P-selectin by 7 %, VCAM-1 by 51 %, ICAM-1 by 6 %, and a higher expression of eNOS (by 18 %) in C3H mice in comparison with B6 mice after cholesterol diet. Further analysis revealed that cholesterol diet significantly increased the expression of endoglin (by 97 %), TGF-ßRII (by 50 %), eNOS (by 21 %) and peNOS (by 122 %) in C3H mice, but not in B6 mice. We propose that lower expression of P-selectin, VCAM-1 and ICAM-1 and higher expression of eNOS in vivo in aorta of C3H mice might represent another potential mechanism for C3H mice being less susceptible to atherosclerosis when compared to B6 mice. In addition, endoglin seems to be involved in an upregulation of eNOS only in C3H mice. Thus, we propose that aorta of C3H mice is less prone to the expression of pro-inflammatory and endothelial dysfunction markers when compared to B6 mice, regardless of lipoprotein profile and before any signs of atherosclerotic process.

Study of the retention behavior of small polar molecules on different types of stationary phases used in hydrophilic interaction liquid chromatography.

The retention behavior of a large group of analytes (35) with varied properties (pKa and logP) was studied on eight hydrophilic interaction LC columns with different surfaces, stationary phase chemistries, and types of particles. The acetonitrile content (5-95%), buffer concentration (0.5-200 mM), and pH of the mobile phase (3.8 and 6.8) were evaluated for their effects on the retention behavior. The type of stationary phase had a significant impact on the selectivity and retention time of the tested analytes. Completely different selectivity was observed on the aminopropyl stationary phase. In this study, the influence of the buffer concentration was similar for all tested columns, except for the aminopropyl stationary phase. Increasing the buffer concentration led to decreased retention times for the basic compounds and increased retention times for the acidic compounds, while the inverse behavior was observed on the aminopropyl stationary phase. The selectivity of the individual stationary phases was evaluated at pH 3.8 and 6.8. Much lower selectivity differences between the stationary phases were observed at pH 6.8 than pH 3.8. Bare silica stationary phases were used in the comparison of the particles (fused-core and fully porous particles of 3 and 1.7 µm) and the columns provided by different manufacturers.