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

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, pNFkB 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

Urinary excretion of nitrites in <i>Sol-Eng</i>^<i>+</i> and control mice.

<p>Urinary excretion of nitrites was measured in urine from <i>Sol-Eng</i>^<i>+</i> and control mice collected in metabolic cages, and corrected by creatinine concentration. Data are shown as mean ± S.E.M. Unpaired t-test.</p

Pressure responses to agonists or antagonists of the NO-cGMP-system in <i>Sol-Eng</i>^<i>+</i> and control mice.

<p>Maximal hypotensive effect of sodium nitroprusside (SNP; 2 mg/Kg b.w.) in <i>Sol-Eng</i>^<i>+</i> and control mice (A). Maximal hypertensive effect of L-NAME (50 mg/Kg b.w.) in <i>Sol-Eng</i>^<i>+</i> and control mice (B). Effects were measured by telemetry. SABP: Systolic blood arterial pressure. Data are shown as mean ± S.E.M. ANOVA and unpaired t-test with respect to control, *p≤0.05; ANOVA and paired t-test with respect to basal conditions, ^#p≤0.05.</p

Concentrations of human soluble endoglin in plasma of <i>Sol-Eng</i>^<i>+</i> and control mice.

<p>Human soluble endoglin concentrations in plasma from female (control n = 53, <i>Sol-Eng</i>^<i>+</i> n = 22) (A) and male (control n = 31, <i>Sol-Eng</i>^<i>+</i> n = 19) (B) mice. Data are shown as mean ± S.E.M. Mann-Whitney test, ***p≤0.001.</p

Impaired vascular contractility in female <i>Sol-Eng</i>^<i>+</i> mice as compared to control mice.

<p>Maximal contraction to KCl (30 mM) (A). Maximal contraction to PGF2α (10μM) (B) and to PHE (1 μM) (C) in <i>Sol-Eng</i>^<i>+</i> and control mice. Comparison of dose-response to PGF2α (D) and PHE (E) in <i>Sol-Eng</i>^<i>+</i> as compared to control mice. Data are shown as mean ± S.E.M. Unpaired t-test, **p≤0.01, ***p≤0.001.</p

Blood pressure (A) and heart rate (B) in <i>Sol-Eng</i>^<i>+</i> and control male mice assessed by telemetry.

<p>SABP: Systolic arterial blood pressure; DABP: Diastolic arterial blood pressure; MABP: mean arterial blood pressure. Data are shown as mean ± S.E.M. ANOVA and unpaired t-test with respect to control mice, *p≤0.01.</p

Endothelium-dependent responses in <i>Sol-Eng</i>^<i>+</i> and control mice.

<p>Acetylcholine-induced relaxation in PHE or PGF2α (1 μM) pre-constricted vessels (A). Effect of L-NAME on the PHE (1 μM)-induced contraction (B). Data are shown as mean ± S.E.M. Mann-Whitney test, unpaired t-test, *p≤0.05, ***p≤0.001.</p