Jana Rathouska

The role of endoglin in atherosclerosis

Endoglin (CD 105, TGF-β receptor III) is a homodimeric transmembrane glycoprotein that plays a regulatory role in TGF-β signaling. Its functional role in the context of atherosclerosis has yet to be defined and should be stated here. Therefore, we focused on the role of endoglin in atherosclerosis in both humans and experimental animals. Endoglin expression was demonstrated in atherosclerotic vessels predominantly in endothelial cells and smooth muscle cells in various types of blood vessels in mice and humans, suggesting its participation in atherogenesis. Endoglin expression was also related to the expression of eNOS in endothelium, repair of the vessel wall, plaque neoangiogenesis, production of collagen and stabilization of atherosclerotic lesions. In addition, increased levels of soluble endoglin were associated with hypercholesterolemia, atherosclerosis, acute myocardial infarction and were related to inhibition of TGF-β signaling in the vessel wall. Moreover, soluble endoglin levels were significantly lowered after a series of extracorporeal eliminations in patients with familial hypercholesterolemia. Additionally, statin treatment decreased levels of soluble endoglin and increased its expression in aorta, which was related to reduced atherosclerosis in mice. In conclusion, we propose that measurement of soluble endoglin might give information about progression of the atherosclerotic process or the efficacy of therapeutic interventions, which is the task that must be answered in clinical trials.

Statin therapy and plasma cortisol concentrations: A systematic review and meta-analysis of randomized placebo-controlled trials

This study aimed to perform a systematic review and meta-analysis of randomized controlled trials (RCTs) in order to calculate the effect size of statin therapy in changing plasma cortisol concentrations. Following a systematic search in Medline, SCOPUS, Web of Science and Google Scholar databases (by up to March 01, 2015), 7 eligible RCTs were selected. Random-effects meta-analysis suggested a significant increase in plasma cortisol concentrations following statin therapy (WMD: 6.34%, 95% CI: 1.80, 10.87, p=0.006). Subgroup analysis confirmed the significance of the effect with lipophilic statins comprising atorvastatin, simvastatin, and lovastatin (WMD: 7.00%, 95% CI: 2.21, 11.79, p=0.004) but not with hydrophilic statins (rosuvastatin and pravastatin) (WMD: 0.60%, 95% CI: -13.46, 14.66, p=0.933). In the meta-regression analysis, changes in plasma cortisol concentrations following statin therapy were found to be independent of treatment duration. Results of this meta-analysis of RCTs suggest a significant elevation in plasma cortisol levels following statin therapy.

Statin impact on disease activity and C-reactive protein concentrations in systemic lupus erythematosus patients: A systematic review and meta-analysis of controlled trials.

BACKGROUND AND PURPOSE Efficacy and safety of statin therapy in patients with systemic lupus erythematosus (SLE) is controversial. The aim of this meta-analysis was to evaluate whether statin therapy affects SLE disease activity and systemic inflammation (C-reactive protein, CRP) according to the evidence from controlled clinical trials. EXPERIMENTAL APPROACH A systematic review followed by a bibliographic search in Medline and SCOPUS (up to March 2015) was performed. Quantitative data synthesis was performed using a random-effects model and the generic inverse variance weighting method. Effect sizes were expressed as weighted mean difference (WMD) and 95% confidence interval (CI). KEY RESULTS Meta-analysis of five controlled trials reporting statin impact on SLE disease activity did not suggest any significant effect of statin therapy on SLEDAI. Evaluation of seven controlled trials with reported effects on CRP levels suggested a significant reduction of plasma CRP concentrations in patients with SLE independent of the treatment duration. The effect size on plasma CRP concentrations was significant with lipophilic (atorvastatin) but not hydrophilic (pravastatin and rosuvastatin) statins. CONCLUSION AND IMPLICATIONS The present results suggest that statin therapy is likely to be safe in patients with SLE. In addition, statin-treated SLE patients may benefit from CRP reduction in terms of managing severe cardiovascular complications associated with the disease.

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-β/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.

Spirulina platensis and phycocyanobilin activate atheroprotective heme oxygenase-1: a possible implication for atherogenesis

Spirulina platensis, a water blue-green alga, has been associated with potent biological effects, which might have important relevance in atheroprotection. We investigated whether S. platensis or phycocyanobilin (PCB), its tetrapyrrolic chromophore, can activate atheroprotective heme oxygenase-1 (Hmox1), a key enzyme in the heme catabolic pathway responsible for generation of a potent antioxidant bilirubin, in endothelial cells and in a mouse model of atherosclerosis. In vitro experiments were performed on EA.hy926 endothelial cells exposed to extracts of S. platensis or PCB. In vivo studies were performed on ApoE-deficient mice fed a cholesterol diet and S. platensis. The effect of these treatments on Hmox1, as well as other markers of oxidative stress and endothelial dysfunction, was then investigated. Both S. platensis and PCB markedly upregulated Hmox1 in vitro, and a substantial overexpression of Hmox1 was found in aortic atherosclerotic lesions of ApoE-deficient mice fed S. platensis. In addition, S. platensis treatment led to a significant increase in Hmox1 promoter activity in the spleens of Hmox-luc transgenic mice. Furthermore, both S. platensis and PCB were able to modulate important markers of oxidative stress and endothelial dysfunction, such as eNOS, p22 NADPH oxidase subunit, and/or VCAM-1. Both S. platensis and PCB activate atheroprotective HMOX1 in endothelial cells and S. platensis increased the expression of Hmox1 in aortic atherosclerotic lesions in ApoE-deficient mice, and also in Hmox-luc transgenic mice beyond the lipid lowering effect. Therefore, activation of HMOX1 and the heme catabolic pathway may represent an important mechanism of this food supplement for the reduction of atherosclerotic disease.

Endoglin as a possible marker of atorvastatin treatment benefit in atherosclerosis.

Endoglin (a type III TGF-β receptor) is able to modulate ligand binding and signaling by association with the TGF-β type I receptors (ALK-1 and ALK-5). In this study, we hypothesized whether atorvastatin treatment affects endoglin/ALK-1/p-Smad1/VEGF expression in the aorta and endoglin levels in serum in ApoE/LDLR double knockout mice. ApoE/LDLR double knockout mice were fed with a diet containing either 1% of cholesterol (CHOL) or cholesterol with atorvastatin (ATV) at a dose of 50mg/kg/day. Biochemical analysis of cholesterol levels and ELISA analysis of endoglin levels in serum, lesion area size, immunohistochemistry and Western blot analysis in mice aorta were performed. Atorvastatin treatment resulted in a significant decrease of total, VLDL and LDL cholesterol, atherosclerotic lesion size and endoglin serum levels in comparison with CHOL mice. On the other hand, atorvastatin treatment significantly increased the expressions of endoglin by 1431%, ALK-1 by 310%, p-Smad1 by 135% and VEGF by 62% in aorta when compared to CHOL mice. In conclusion, it has been demonstrated that atorvastatin increases endoglin/ALK-1/p-Smad1/VEGF expression in aorta and decreases the size of atherosclerotic lesions, suggesting that activation of this endothelial-protective pathway might support the antiatherogenic effects of atorvastatin. Moreover, atorvastatin concurrently decreased serum levels of endoglin suggesting that monitoring of endoglin levels in blood might represent an important marker of the progression and/or treatment of atherosclerosis.

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, 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 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‐&bgr; 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‐&bgr; signaling. IL6 and NF&kgr;B 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‐&kgr;B/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‐&kgr;B, 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.

The Role of TGF-β and TGF-β Receptors in Atherosclerosis

Researchers discovered a new cytokine with the capability to transform fibroblasts in 1983 while studying epidermal and platelet derived growth factors in rat fibroblasts. Originally called sarcoma growth factor, TGF┚ was first isolated from neoplastic mouse tissue by Moloney sarcoma virus (Assoian et al., 1983). After more than three decades TGF-┚ family comprise several members including – nodals, activins, bone morphogenic proteins (BMPs), myostatin, anti-Muellerian hormone (AMH) and others – control cell division, differentiation, migration, adhesion, organization and programmed cell death (Massague, 1998). There are three TGF-┚ isoforms currently described in humans, including TGF-┚1, TGF-┚2, and TGF-┚3. Alignment of the amino acid sequences of the three mammalian TGF-┚ isoforms reveals that the different isoforms share a high level of similarity between the active domains; TGF┚3 is 86% similar to that of TGF┚1 while it shares 91% similarity with that of TGF-┚2. However, despite TGF┚2 and ┚3 sharing the highest level of sequence similarity of the three isoforms, TGF┚2 binds to the TGF-┚ receptor II (T┚RII) in a different way from TGF ┚1 and ┚3. Furthermore, while TGF-┚1 and -┚3 are both capable of binding directly to the type II receptor, presentation of TGF-┚2 to the receptor requires the presence of a co-receptor (beta glycan or endoglin), which may explain the differences in activities of TGF-┚2 and -┚1 (Laverty et al., 2009). The importance of TGF-┚ isoforms in mammalian biology is highlighted by the lack of viability in TGF-┚−/− mice. Targeted disruption of the TGF-┚1 genes leads to hematopoietic and vasculogenic defects that result in death of about half of null embryos by 10 days gestation. Moreover, embryos that survive die within 3 weeks due to widespread inflammatory disease (Shull et al., 1992). TGF-┚2 null mice die in the perinatal period due to cyanotic heart disease, pulmonary insufficiency, and another abnormalities in urogenital, visual, auditory, neural and skeletal systems (Sanford et al., 1997). Additionally, mice lacking TGF-┚3 exhibit cleft palate with 100% penetration and die immediately after birth due to an inability to suckle effectively (Proetzel et al., 1995). In addition, other organs are not affected when compared with mice lacking TGF-┚1 and TGF-┚2. Several other papers showed differences in postnatal effects of different TGF-┚ isoforms, including different role in neovascularization (Wu et al., 1997), collagen production and bone production (ten Dijke et al., 1990). Moreover, TGF-betas are released by immune cells